3,142,638 United States Patent Office Patented July 28, 1964

2 3,42,638 been carried through pipe, conduit, or sewers. In some PROCESS FOR SEPARATING SOLIDS embodiments of our invention, the concentrations of FROM SEWAGE wastes of significance to the application at hand may be Donald Stapf Blaisdeil, 780 Sanamit Ave., St. Paul, Minn., only a few parts per million, and in other embodiments and Ruth Elizabeth Barry Klaas, 353 Ridgewood the concentrations may be as high as 10,000 parts per Road, Ardeia Sis, Miinae. milion or even higher. Unless otherwise defined in this a. No Drawing. Fied June 29, 1962, Ser. No. 265,184. specification, the definitions of the terms and tests we 7 Cains. (C. 250-52) use are those set forth in the book, "Standard Methods for the Examination of Water, Sewage, and Industrial This invention relates to the treatment of sewage, and 10 Wastes,' Tenth Edition, published in 1955 by the Ameri this application is a continuation-in-part of application can Public Health Association, of New York City, and for U.S. Letters Patent Serial Numbers 724,785 (filed such standard handbooks and textbooks of chemistry March 31, 1958, now abandoned) and 786,906 (filed as: Lange, "Handbook of Chemistry,” Handbook Pub January 15, 1959 now abandoned) by the present in lishers, Inc., Sandusky, Ohio, 1944; Latimer and Hilde ventors. More specifically, this invention relates to novel 5 brand, “Reference Book of Inorganic Chemistry,” Re compositions useful as additives for sewage, and to novel vised Edition, The Macmillan Company, New York, processes for the treatment of sewage. 1940; Hildebrand, “Principles of Chemistry,” Fifth Edi It is an object of this invention to provide novel sewage tion, The Macmillan Company, New York, 1947; Fuson compositions from which suspended solids settie and and Snyder, "Organic Chemistry,” John Wiley & Sons, can be removed rapidly in treating mechanisms of simple 20 inc., New York, 1942; and Glasstone, “Textbook of design and modest size. Physical Chemistry,” Second Edition, D. Van Nostrand It is a principal object of this invention to provide a Co., Inc., New York, 1946. Thus, for example, the novel type of clarifying agent in the treatment of sewage, term "water-dispersible synthetic organic cationic poly which type of clarifying agent causes rapid flocculation electrolytic flocculating material' will be understood to and sedimentation of solids, either suspended, dissolved, 25 exclude (as being polyampholytic rather than cationic) or both, in said sewage, and makes said solids adapted even polyacrylamide-type polymers that under some con for easy and rapid removal from the major aqueous ditions may actually be anionic by reason of a minor component of Such sewage, at low cost in treating mecha content of carboxylic groups. (Compare Dow, "Separan nisms of simple design and modest size. 2610 In Waste and Sewage Treatment,” October 1956, It is a further principal object of this invention to 30 Dow Chemical Company, Midland, Michigan, and Chem provide novel processes for the treatment of sewage, ical Week, September 17, 1960, page 6.) In other words, wherein chemical additives may be employed to produce we regard an organic polyelectrolytic flocculating ma a treated water of relatively high degree of purity from terial as cationic only if the main bodies of the polymer aqueous liquors containing wastes, such as fecal matter molecules bear overall positive charges at pH levels or other contaminants, in treating mechanisms of simple 35 commonly encountered in sewage; since the ionization design and modest size. constant of the amine groups is polyacrylamide is about Another object is to provide a sewage slude of relatively 10-15, and the ionization constant of carboxylic groups higher solids content, and of relatively lower Volume per is about 10, a modified polyacrylamide polymer con unit volume of sewage treated, than obtained in present taining even a very low percentage of carboxylic groups chemical methods of treating sewage conventionally used. 40 would be anionic at some levels of pH commonly en Another object is to provide a sludge of modified countered in sewage, or the like, and such modified characteristics (e.g. filtration, dispersion, digestion charac polyacrylamide polymers are intended to be excluded teristics), as compared to the characteristics of sludges specifically from the class of materials defined in this obtained in conventional chemical methods of treating specification as "water dispersible synthetic organic cat sewage or such like liquors. 45 ionic polyelectrolytic flocculating material.” Still a further object is to provide waters of a relatively Chemical treatment of sewage, of course, is well known high degree of purity by chemical treatment of aqueous to those versed in the prior art. The voluminous litera liquors containing such wastes as sanitary sewage, in ture of this field mentions the use of the following ma dustrial wastes or other contaminants. terials, among others, in the treatment of sewage or raw Various other objects, advantages, and features of this 50 water: ferric chloride, ferric sulfate, ferrous sulfate, invention will become apparent to those skilled in the chlorinated copperas, calcium oxide, calcium hydroxide, art upon reading the specification and appended claims. aluminum sulfate, alkali hypochlorites, soda ash, activated A broad field of utility for our invention is, of course, silica, calcium carbonte, coal, diatomite, activated carbon, the treatment of municipal sewage. ammonium sulfate, sodium aluminate, sodium silico Sewage ordinarily is a dilute aqueous mixture of the 55 fluoride, sodium flouride, caustic, sulfuric acid, activated wastes from household and industry that is convenient glue, rosin size, pine oil, kerosense, copper sulfate, chlor and economical to carry away by water. As used in amine, sulfur dioxide, sodium sulfite, nitric acid, carbon this specification and the appended claims, the term dioxide, hydrochloric acid, oxygen, ozone, and chlorine. sewage refers to any of the ordinary types of aqueous In the prior art, iron and aluminum salts have been liquors containing significant amounts of wastes, such 60 used as coagulants or flocculants for sewage, and indeed as fecal matter, domestic wastes, industrial wastes, and have a limited degree of effectiveness for removing col such like, and is not to be construed as being limited loidal solids and very finely divided suspended matter. to meaning only aqueous liquors which in lay terms are Both the iron and aluminum salts sometimes used (ferric ordinarily called sewages, nor should it be construed as chloride, alum, and the like) have the property of form being limited to mean aqueous liquors which have actually 65 ing relatively insoluble flocs that enmesh suspended ma 3,142,638 as 4. terial in the sewage, some of which material is swept sued October 25, 1960); Chemical Week, 87 (August out of the sewage as the floc matrix is removed. Fron 6, 1960), pages 26-28; Chemical Week, 87, (September and aluminum salts have been used also in the coagula i7, 1960), page 16; Plant Management and Engineer tion of sewage sludge, particularly in the preparation ing, 23, (March 1961), pages 2 and 3; Aimone and of the sludge for dewatering. (Our compositions are Booth, U.S. Patent 2,740,522 (issued April 3, 1956); also useful in some degree for this purpose.) Contois, U.S. Patent 2,847,403 (issued August 12, 1958); Water-insoluble synthetic organic polyelectrolytes (ion Chemical Engineering, June 1956, page 148; Dow, “Sep exchange resins) have been used in the prior art in the aran. 2610 In Waste and Sewage Treatment,” (October conditioning of certain aqueous liquors, as described in 1956), Dow Chemical Co., Midland, Michigan; "Co the literature by one of us, and by many others in numer 0. agulant Aids,' Bulletin 410-12-2 (1957), Hagan Chem ous references. The performance of carboxylic ex icals & Controls, Inc., Pittsburgh, Pennsylvania; "Hagan changers in the removal of material from certain types Coagulant Aids Nos. 7, 11, and 18 Safe for Drinking of aqueous liquors, for example, has been described by Waters,” Hagan Bulletin 4104-1-12:#HC-5652, Hagan Kunin and Barry, in Industrial and Engineering Chem Chemicals & Controls, Inc., Pittsburgh, Pennsylvania; istry, 41, 1269-72 (1949); by Winters and Kunin, in 5 French Patent 1,123,970 (October 2, 1956); Australian Industrial and Engineering Chemistry, 41, 460 (1949); by Patent 200,883 (April 21, 1955); Uytenbogaart, U.S. McGarvey and Thompson, Industrial and Engineering Patent 2,236,930 (issued April 1, 1941); Ralston and s Chemistry, 43, 741 (1951); and by others. Such water Pool, U.S. Patent 2,315,734 (issued April 6, 1943); insolubie ion exchangers have never found widespread Wilson, U.S. Patent 2,419,930 (issued April 29, 1947); commercial usage in the treatment of municipal sewage, 20 McDonald, U.S. Patent 2,647,084 (issued July 28, 1953); by reason of their relative ineffectiveness especially in the Stautzenberger and MacLean, U.S. Patent 2,903,438 (is light of their high initial and operating costs, and the sued September 8, 1959); Suen and Schiller, Canadian general operational difficulties associated with the use Patent 589,309 (issued December 22, 1959); Weidner and of insoluble ion exchangers in aqueous liquors contain Dunlap, U.S. Patent 2,995,512 (issued August 8, 1961); ing suspended solids. British Patent 10,050 (October 30, 1906); and multi In the separation of suspended inorganic solids from tudinous other references.) Even relatively cheap ani aqueous liquors, of course, certain chemical coagulants onic organic polyelectrolytic coagulants diluted with have been found to be effective at least to some degree. massive amounts of inexpensive anionic polyelectrolytic (See, for example, British Patent 760,869.) flocculant aid such as clay (see Henry, U.S. Patent 2,296,- To date, however, no really satisfactory chemical clari 30 523, issued September 22, 1942, and Ryznar, U.S. Pat fying agent or chemical process for removing from aque ent 2,420,340, issued May 13, 1947) have proved too ous liquors such as sewage, at acceptable costs and in expensive for general use in the chemical treatment of treating mechanisms of simple design and modest size, municipal sewage, although such clay/anionic organic suspended solids comprising substantial amounts of or polyelectrolyte combinations have found some accept ganic material has yet been developed. Even in the ance in the treatment of raw water supplies having rela chemical coagulation of organic solids in raw water Sup tively low concentrations of suspended and/or dissolved plies, wherein the content of suspended or dissolved or organic solids. (See “Coagulant Aid Simplifies Water ganic solids is generally only a few parts per million, ac Clarification," Chemical Engineering, page 148 (June ceptable results have been obtained only by using rela 1956).) tively large and expensive treating equipment, and ex 40 As noted below, our invention involves focculation cessively large amounts of chemical coagulant per unit and clarification of sewage by additives and methods in amount of organic solids removed. (See, "Betz Hand volving a type of cationic organic polymer, as herein book of Industrial Water Conditioning,” W. H. and L. D. specified, and a weighting agent. The relative efficiency Betz, Philadelphia, 1950, especially pages 7 to 11, and of cationic polymers in flocculating sewage, of course, compare with the later edition, “Betz Handbook of In 45 is not surprising, in view of references of the prior art dustrial Water Conditioning.' Betz Laboratories, Inc. cited above. The efficiency of a weighting agent along (1957), pages 10 to 12; see also Hirsch, "Manual for with the cationic polymer is really most surprising, since Water Plant Operators, First Edition, Chemical Publish all of the prior art of which we are aware tends to indi ing Co., Inc., 1945, especially pages 56 to 76; Powell, cate that weighting agents are relatively inefficient, and Industrial and Engineering Chemistry, 46, No. 11, No 50 simply are not economic in any significant proportion vember 1954, pages 85A, 86A and 88A; and many other of sewage treating problems. (See especially Gehm, references.) Attempts to use organic fiocculants with Sewage Works journal, 13, 681-689 (1941).) Anionic out employing weighting agents in the manner herein organic polymer/weighting agent combinations were used disclosed have not met with any substantial commercial for clarifying and purifying liquids and waste waters by success in treating such aqueous liquors as sanitary or 55 Ravenstad (U.S. Patent 1,619,036, issued March 1, 1927) municipal sewage, principally because the specific poly over thirty-five years ago, but never have come into sub mers involved have been relatively ineffective or entirely stantial use, even though iron ore and a magnetic method too costly to justify use on an economic basis. (See of sedimentation were later suggested (Urbain and Stem Schiller and Suen, industrial and Engineering Chemistry, en, U.S. Patent 2,232,294, issued February 18, 1941). 48, 2132-2137 (1957); Hiroshi Nakamura, "High Speed 60 The essence of our invention lies in the interaction of Chemical Treatment of Excreta,” from the 1957 Series cationic polymers, of the type specified herein, and weight of Sewage Treatment, No. 1, Japan Nutrition Association, ing agent, of the type herein specified, in the treatment 4, 2, Yurakuchio, Chiyodaku, Tokyo, Japan (1957) Clem of aqueous liquor. Although it is true that instances of ens, U.S. Patent 2,862,880 (issued December 2, 1958); coaction between metal materials (as free metal, ion, Paschall, U.S. Patent 2,876,217 (issued March 3, 1959); 65 or compound) and organic polymers, due apparently to Gloor, U.S. Patent 2,728,724 and U.S. Patent 2,728,725 the formation of "partially covalent” or "coordinate co (both issued December 27, 1955); Goren, U.S. Patent valent' bonds between the metal material and organic 2,937,143 (issued May 17, 1960); Dunlap, Australian polymer (Kunin and Barry, Industrial and Engineering Patent 216,301 (September 20, 1956); Dow, French Chemistry, 41, 1269 (1949), and Dow, British Patent Patent 1,168,036 (December 3, 1958); British Patent 70 760,869, published November 7, 1956) have been long 773,716 (May 1, 1957); Caldwell, Wurzburg, and Sun, known, no one has ever, to the best of our knowledge, U.S. Patent 2,975,124 (issued March 14, 1961); Huilinger taken advantage of this type of coaction to produce a and Yui, U.S. Patent 2,970,140 (issued January 31, 1961); Synergistic effect in the treatment of sewage. Stephens and Raroport, U.S. Patent 2,938,026 (issued The extent of the coaction of our cationic polymers May 24, 1960); Schifferli, U.S. Patent 2,957,821 (is 75 and weighting agents in the treatment of sewage-that is, 3,142,638 5 6 the extent of the synergistic effect obtained-is far greater conventional chemical methods of clarifying aqueous than the sam of the effects which might reasonably be liquors, as set forth above, may be substantially over expected by consideration of the individual components come, and the objects of this invention, also as set forth thereof. Thus, the synergism obtained in the practice of above, and other objects, are attained. Especially good our invention is so marked (as the examples below make results are obtained if the water-dispersible synthetic or clear) that our additives are normally employed in the ganic cationic polyelectrolytic flocculating material and treatment of sanitary sewage at a concentration of only iron ore are used in combination with about 1 to about about one-hundredth that of the suspended solids in the 300 parts by weight of water-dispersible inorganic cationic sewage; to appreciate the significance of this fact in an polyelectrolytic flocculant aid (such as ferric hydroxide operation where economics is a paramount consideration, O in a Sol formed by reaction of ferric chloride with a large compare Buswell's statement that . . . "the required dos eXcess of water and/or aluminum hydroxide in a sol age of chemical coagulant runs about one pound per formed by the reaction of sewage-grade alum with a large pound of impurities removed . . . ” (Buswell, “Encyclo eXcess of water) per million parts of sewage. pedia of Chemical Technology,” The Interscience Ency (Water-dispersible inorganic polyelectrolytic flocculant clopedia, Inc., New York, 1954, Volume 12, in the para aids useful in the practice of this invention include finely graphs of pages 200–201). ground montmorillonites, attapulgite, Wyoming-type ben The major disadvantages of chemical treatment of tonite, calcium bentonite, bentones (amine derivatives of sewage, as ordinarily practiced in the prior art, are chiefly: bentonite), bauxite, and the like. In this disclosure, of (1) slowness of removal of coagulant focs from the course, Crystals or the like of inorganic polyelectrolytic treated sewage, with consequent need for costly treating 20 material which tend, in suspension, to carry an overall and settling tanks of large size; (2) inefficiency in re negative charge (for example, Wyoming-type bentonite) moval of very finely divided suspended and in particular are regarded as inorganic anionic polyelectrolytic floccu the coagulable or absorbable dissolved solids; (3) rela lant aids, and crystais or the like of inorganic polyelec tively low purity of treated water obtained from the trolytic material which tend, in suspension, to carry an sewage-treatment process, and (4) relatively high volume 25 overall positive charge (for example, Fe2OxHO or of sludge produced per unit volume of sewage treated. Fe(OH)3) are regarded as inorganic cationic polyelec These major disadvantages of the conventional chemical trolytic focculating aids. Inorganic polyelectrolytes as methods of treating sewage have prevented the wide escribed in this specification have, in general, average spread commercial use of such methods on any but ex molecular weights in excess of about 10,000. By the tremely dilute sewages, despite the fact that chemical 30 term "Water-dispersible' material, of course, as used in treatment of sewage offers the possibility of very large this specification and the appended claims, we mean to savings of capital costs in the construction of sewage include water-soluble materials, as well as more or less treatment plants in return for a very small (by compari Solid materials of such fine particle size that, on agitation son) daily outlay for the costs of the necessary treating in water, they settle out of the liquid suspension only chemicals. As Buswell, “Encyclopedia of Chemical Tech slowly and over an appreciable period of time.) nology,” The interscience Encyclopedia, Inc., New York, The iron ore weighting agent having a particle size 1954, Volume 12, pages 200–201, has pointed out, an less than 50 mesh (U.S. Standard Screens), generally enormous amount of work covering practically every Speaking, of an average particle size in the range of 50 known mechanical or chemical coagulant has been done mesh to 200 mesh (U.S. Standard Screens) has been on this problem, and yet the cost of chemicals is still 40 found to coact in synergistic fashion to a most remark usually too high to make the process attractive: normally, able extent with the water-dispersible synthetic organic the required dosage of chemical coagulant runs about cationic polyelectrolytic flocculating material. one pound per pound of impurities removed, the volume The type of process applicable to insure rapid removal of sludge obtained is practically double that obtained by of flocs-gravity, magnetic field, electrostatic field, cen other process, the purification obtained seldom exceeds 45 trifugation, or such like-will in each case of course be 60 percent, and tank capacity required is only slightly determined chiefly by the properties of the specific weight less than that normal for other processes. In conse ing agent and/or organic polyelectrolytic flocculant em quence, chemical coagulants bear a major portion of the ployed, and generally to a lesser degree by the nature of sewage-treating function in only a relatively small pro the suspended solids in the sewage. Weighting material portion of sewage-treating plants in the United States, should be of fairly large particle size-e.g. in the range of although some chemical treatment is practiced, at least 50 to 100 mesh (U.S. Standard Screens) when gravity occasionally, in scores of plants. (See Babbitt and Bau only is used for sedimentation, but may be of much man, “Sewerage and Sewage Treatment,” Eighth Edition, Smaller particle size when magnetic, filtration, centrifugal, John Wiley and Sons, Inc., New York, 1958, especially or such like method of separation is employed. Addi pages 443 to 446; see also Imhoff and Fair, "Sewage 55 tionally there may also be added to the sewage along with Treatment,' Second edition, John Wiley and Sons, Inc., the other classes of treating materials described above New York, 1956, especially pages 78 to 89.) essentially non-ionic absorbents having high surface area Our invention, as described and disclosed herein, pro per unit volume-such as activated carbon. The classes vides means for overcoming these major disadvantages of of treating materials may be combined in various ways, the methods of chemical treatment as practiced in the 60 as will be described further herein, to make compositions prior art, and makes chemical treatment suitable and of matter useful as additives for sewage, industrial wastes, economic for treatment of municipal sewages, effluents raw water, and the like, especially if there is added sepa from septic tank, cess pools, and the like from individual rately to the sewage or raw water, in addition to the com waste sources, industrial wastes, raw water supplies, and position comprising water-dispersible synthetic organic the like. 65 cationic polyelectrolytic flocculating material and iron We have found that the addition of water-dispersible ore, flocculating material of an electrical charge opposite (especially hydrophilic) synthetic organic cationic poly to that of the water-dispersible synthetic organic poly electrolytic flocculating material having a molecular electrolyte employed. weight in excess of 10,000 and at least one amine group We have discovered that the most generally applicable per 10,000 units of molecular weight, at concentrations 70 additives for sewage, in the practice of our invention, con of 1 to 300 parts per million parts of sewage, along with tain from about 1 to about 100 parts of synthetic organic iron ore weighting agent having a particle size smaller cationic polyelectrolytic flocculating material and from than 50 mesh (U.S. Standard Screens) focculates and about 1 to about 100 parts by weight of weighting ma causes the suspended solids of the sewage to settle out terial and also may contain from about 1 to about 100 most efficiently. In this manner, the disadvantages of 75 parts of inorganic polyelectrolytic flocculant aid and/or 3,142,838 7 S from about 1 to about 100 parts by weight of substantially J. C. Bailar, Jr., New York, Reinhold Publishing Corp., non-ionic absorbent material. 1956, especially front inside cover, front cover page, For economic as well as technical reasons, iron ore has pages 1 through 99 and 416 through 471; also, Hilde been found to be outstanding as a weighting agent. In brand, “Principles of Chemistry,” Fifth Edition, New some cases -especially those in which catalytic effects are York, The Macmillan Co., 1947, pages 82 through 104 desired from the presence of the weighting agent, as in and 146 through 152, and Latimer and Hildebrand, "Ref oxidation of the sewage/sewage additive composition by erence Book of Inorganic Chemistry,” Revised Edition, blowing air through same or the clarified liquor obtained New York, The Macmillan Company, 1940, especially pages 98 to 100.) therefrom-other weighting agents, generally selected Substantially non-ionic absorbent material of fine par from the substantially water-insoluble compounds (pref O ticle size (generally speaking in the range of 50 to 200 erably oxides in the case of metals where the oxide en mesh, U.S. Standard Screens) and having a surface area ployed can be selected to be substantially water-insoluble of at least 10 square meters per gram of material may be and non-reactive with water) of metals which form co used in combination with synthetic organic polyelectrolytic ordinate covalent bonds with amines (e.g., mercury, flocculating material and weighting materials and (option copper, platinum, cobalt, nickel, silver, thallium) or with ally) also polyelectrolytic flocculant aids in the composi ammonia (e.g., cobalt, chromium, platinum, copper, tions of matter and processes described herein. In ap silver, zinc, rhodium, mercury, nickel, gold, OSnilin, alt plications of this kind, we have found various grades of minum, thallium) may be admixed with the iron ore in activated charcoal and like materials effective. such fashion as to form weighting agent, or in Sofile cases Water-dispersible synthetic organic cationic polyelectro may be used alone or in combination with each other as 20 lytic flocculating materials most useful in the practice of weighting agents. In general, therefore, weighting agents this invention include water-dispersible types containing useful in the practice of this invention are finely ground primary annine, secondary amine, tertiary amine, quater solids, substantially insoluble in water, having little or no nary amine groups, or combinations thereof. Generally tendency to degrade spontaneously in particle size to par speaking, the most effective types of polyelectrolytes have ticles of colloidal dimensions on standing in water, and average molecular weights in excess of about 10,000. We having a specific gravity substantially in excess of 1, and have found water-dispersible polymerized ethylene innine preferably above 3. We have found such materials as and derivatives thereof obtained by reacting said polyn iron-containing barite, magnetite, hematite, franklinite, erized ethylene imine with aqueous hydrochloric acid iron-containing zirconia, and ilmenite, of an average par and with various amounts of ethyl bromide or aqueous ticle size in the range of 50 mesh to 200 mesh (U.S. 30 ethyl alcohol and like derivatives to be especially effective Standard Screens) particularly effective. Water-sensitive in the treatment of sewage and the like. In addition, iron ore materials such as even those clays which contain we have found that water-dispersible melamine-formalde enough iron to have a yellow or reddish color, which tend hyde resins, ureaformaldehyde resins, and the like, and to form colloidal stable suspensions in water, are specifi compositions obtained by heating said resins with various cally excluded. Likewise it frequently may be desirable 35 announts of an amine such as pyridine, in hot aqueous to include in the soil of water-dispersible inorganic cat hydrochloric acid, and like derivatives, are also useful to ionic focculant aid generally, of ferric hydroxide or attain at least to some degree the objects of this inven aluminum hydroxide (see Bayles and Mills, "Basic Chem tion. (The melamine-formaldehyde resins employed istry for High Schools.” The Macmillan Co., New York, were commercial wet-strength paper-treating resins. 1947, page 131; Latinner and Hildebrand, “Reference 40 Methods of making such resins, generally by condensing Book of Inorganic Chemistry,” Revised Edition, The Idac melamine with aqueous formaldehyde in a melamine: millan Co., New York, 1940, page 393; Hildebrand, formaldehyde ratio of 1:2 to 1:4 at 60° C. to 90° C. and “Principles of Chemistry," Fifth Edition, The Macmillan preferably under slightly alkaline conditions, as in the Co., New York, 1947, pages 355 to 373; McCutcheon, range of pH 8 to pH 9, are well known and are described Seltz and Warner, “General Chemistry," D. Van Nostrand 45 in the prior art.) Although all of the cationic synthetic Co., Inc., New York, 1939, page 335; Rollinson, "Olation organic polyelectrolytes described herein are in themselves and Related Chemical Processes' in “The Chemistry of effective to a Small extent for attaining at least some of the Coordination Compounds,” as edited by Bailar, Rein the objects of this invention, we have found, as noted hold Publishing Corp., New York, 1956, pages 448 to above, that far better results may be achieved, at far lower 471)-if such is used--at least some ions of metals Se 50 cost per volume of sewage treated, by using along with lected from the group consisting of cobalt, chronium, the water-dispersible synthetic organic cationic polyelec platinum, copper, silver, zinc, rhodium, mercury, nickel, trolytic flocculating material, weighting material and pref gold, osmium, aluminum and thalium. The type of erably also cationic inorganic polyelectrolytic flocculant metal(s) and/or metal compound(s) most useful for cata aid and (optionally) substantially non-ionic absorbent ma lytic purposes in the oxidation of sewage of course varies 55 terial, all of these latter classes being of the types used in with the type of solids in the sewage, but almost invariably the coin positions and processes specified elsewhere herein. will be selected from the group consisting of iron, cobalt, For best results, we have found that the water-disper manganese, osmium, silver, copper, tin, vanadium, cerium, sible synthetic organic cationic polyelectrolytic flocculat titanium, platinum, nickel, uranium, chromium, mercury, ing material used in our compositions and processes should molybdenum, aluminum, tungsten, selenium, palladium, 60 have at least one annine group per 10,000 units of molecu and lead-but perhaps most frequently copper or cobalt lar Weight. Especially good results are obtained when or both will be selected; in instances where it is imprac the amine employed is primary or secondary, rather than tical to include the catalytically active metal(s), metal tertiary, quaternary or "hybrid" amine-containing group, compound(s) or both in the weighting agent or water and when the molecular structure of the organic cationic dispersible inorganic cationic flocculant aid or both, it will flocculating material contains an amine group removed usually be possible to include such catalytically active two or three carbon atoms along the skeletal structure of material as a component of the sewage-treating equip the polymer from a substituent amine or hydroxyl ment-for example, as a metal mesh screen or as a metal group-that is, when the polymer contains groupings or metal oxide-bead bed in the air oxidation chamber of Such as the sewage-treating equipment. As noted above, we have 0. found compounds of copper and cobalt especially useful R R oxidation catalysts in the aeration of sewage; copper it self, in the form of metal mesh screening, also serves well --d- Or ---- as a catalyst in air oxidation procedures. (See "The Chemistry of the Coordination Compounds,” edited by 75 wherein "R" is a hydroxyl or amine group and “X” is an 3,142,638 9 amine group. Thus, cationic starch of the type desig and iron ore weighting agent having a particle size smaller nated herein has been found to be, under conditions also than 50 mesh (U.S. Standard Screens), and (b) anionic as specified herein, extraordinarily efficient, in combina flocculating material, said cationic starch, said iron ore tion with iron ore weighting agent. (In this type of chem weighting agent, and said anionic flocculating material be ical structure, the amine group is normally two carbons ing employed in amounts sufficient to cause flocculation removed along the skeletal structure of the polymer from a and accelerated sedimentation of solids in said sewage, and substituent hydroxyl group: thereafter separating from the sewage compositions formed an aqueous portion substantially free of suspended pract pract pilgot Solids. C-0 C-0 C G in the practice of our invention, as described and dis closed herein, we have found that water-dispersible cati V/ y/ N C y onic starches having average molecular weights of about 1,000,000 give excellent results, although some degree of effectiveness has been demonstrated in the use of cationic /N/LAN/N/\ 5 starches having molecular weights as low as about 10,000, and also in the range of molecular weights (as in slightly \ . X H X cross-linked starches) above 1,000,000 and indeed on the Where X=amine (e.g., aminoalkoxy)-group order of several million. Accordingly, our specification of molecular weight in the phrase "cationic starch having (in the end group of the polymer chain in a structure of 20 an average molecular weight of about 1,000,000” is in this type, the amine group may be three carbons removed tended to be an "order-of-magnitude' term only-that from a hydroxyl group.) Other materials of this same is, we mean to have it understood by the term "molecular general type of chemical structure, Such as the so-called weight of about 1,000,000” the whole range of molecular “cationic modified celluloses' are also effective. it should weights from somewhat above 10,000 to perhaps above be noted that cationic polymers having a skeletal chain 25 10,000,000, or as high a molecular weight as the cationic structure that is resistant to degradation by heat, hydroly starch retains the property of dispersibility in water. We sis, bacterial attack, or the like offer Slibstantial advan have also found that cationic starches, to be well adapted tages in the practice of our invention particularly in in for use in this invention, should have at least one basic stances where it is desired to recycle the treating chemical, (normally, amine) group for every 40 to 50 anhydro as (1) by treating the raw sewage with cationic polymer 30 glucose units (equivalent to about 10,000 units of molec and weighting agent, (2) settling the fiocculated solids ular weight, in the starch molecule, and that the ionization containing most of the sewage solids, the cationic poly constant of the basic groups employed should be larger mer, and the weighting agent, (3) degrading the sewage than 101 and preferably on the order of 10-5 or even solids, but not the cationic polymer or the weighting agent higher. It is thought that this requirement of substantial (to any really significant extent), by hydrolysis, oxidation, 35 basic strength may be due to the weakly acidic character heat, bacterial attack, or the like in a vessel preferably of the hydroxyl groups in the starch, which, together separate from the settling/sedimentation vessel, and (4) with, for example, very weakly basic groups such as Tecycling the undegraded polymer and weighting agent amide groups having ionization constant on the order of from the degradation phase along with make-up chemi 10, might tend to confer undesirable polyampholytic cals, back into the main settling/sedimentation vessel. 40 (This general type of recycling process is also applicable character on the starch to such an undesirable degree in the use of weighting agents with anionic and/or certain that the starch might exhibit an isoelectric point at or non-ionic polymers having molecular weights in excess near the pH of the aqueous liquor being treated, with of 10,000 and resistance to hydrolysis, oxidation, heat, consequent effect in the practice of our invention. bacterial attack, or the like.) Starches containing sufficient amine groups such as the Generally speaking, the polymers of utility in the prac p-aminobenzyl, amino, and dimethylamino groups have tice of our invention are hydrophilic-that is, they tend to given good results, in combination with ferruginous mate be quite readily “soluble' in water at the concentrations rial (including iron ore), and so forth, in the clarification of use, and have at least one oxygen or nitrogen aton for of aqueous liquors. Such cationic starches may be made every ten carbon atoms (and usually for every one or two in a great number of different ways, as will be evident carbon atoms) in the molecular structure of the polymer. 50 to those versed in the art of organic chemistry and par As noted above, cationic starch is especially useful in ticularly in the art of starch chemistry, as by amination the practice of our invention, although other cationic poly and/or other appropriate treatment (e.g., reduction, where mers may be used. Thus, the disadvantages of conven applicable) of selected starch derivatives as described in tional chemical methods of clarifying aqueous liquors, Kerr, "Chemistry and Industry of Starch,” Second Edi as set forth above, may be substantially overcome, and 55 tion, Academic Press, Inc., New York, 1950 (Chapter X, the objects of this invention, also as set forth above, and by E. F. Degering, Derivatives of Starch, pages 259 to other objects, are attained by employing as a clarifying 323; chapter XI, by J. M. Newton and G. T. Peckham, agent for sewage a composition of matter comprising Jr., Oxidation of Starch, pages 325 to 343); Bruson, Water-dispersible cationic starch having an average molec U.S. Patent 2,401,607; J. H. van der Meulen, German ular Weight of about 1,000,000, and iron ore having a 60 Patent 624,988 and U.S. Patent 2,053,012; Dreyfus, particle size smaller than 50 mesh (U.S. Standard British Patent 166,767; Lolkema and Moller, Netherland Screens), said cationic starch and said iron ore weighting Patent 56,340; Thomson, “The Direct Chlorination of agent being employed in amounts sufficient to cause foccu Starch,” Thesis, Kansas State College (1945); Gaver, lation and accelerated sedimentation of solids in said sew U.S. Patent 2,518, 135; Konigsberg, U.S. Patent 2,500,950; age, and thereafter separating from the sewage an aqueous 65 and diverse other publications. For the purpose of illus portion Substantially free of suspended solids. In the trating a method of preparing cationic starch, we have treatment of many classes of sewage, even more outstand included among our examples in this disclosure a detailed ing results may be obtained in overcoming the disadvan description of the process whereby we have made in good tages of conventional chemical methods of clarifying sew yieldp-aminobenzyl cationic groups.starch having a substantial content of age, and in attaining the objects of this invention, as set The ferruginous material we have used in the practice forth above, and other objects, by employing a method of of our invention has been, of course, iron ore, in most clarifying aqueous liquor, which comprises mixing with instances along with ferric chloride. Other iron com Said liquor separately (a) water-dispersible cationic starch pounds may be used, but we have found the best results having an average molecular weight of about 1,000,000, 75 are obtained where the ferruginous material is of such 3,142,638 2 a nature that it produces ferrous hydroxide and/or ferric bentonite with hydrochloric acid and subsequent wash hydroxide on reaction with water, and further when any ing with water; the product obtained by heating corn fraction of the ferruginous material which remains a starch with phosphoric acid; exocellular polysaccharide hard, substantially water-insoluble solid on dispersion in having a molecular weight of several millions, and having water has a particle size such that substantially all of said as a repeating unit 5 anhydromannose units one of which fraction passes 50 mesh U.S. Standard Screens. carries a monopotassium orthophosphate group attached Water-dispersible negatively charged flocculating agents at the C6 position, said exocellular polysaccharide being (that is, anionic flocculating material) useful in the prac formed by fermentation of glucose with the yeast Han tice of this invention have been, for the most part, anionic senula holstii NRRL Y-2448 (Bulletin CA-N-7, "Infor polyelectrolytes having molecular weights in excess of O mation on Phosphomannan Y-2448,' United States De about 10,000, of sufficient ionization strength (or con partment of Agriculture, Agricultural Research Service, taining phenolic, carboxylic, sulfonic, or phosphorous Northern Utilization Research and Development Division, containing acidic groups) to form salts with alkalications Peroia, Illinois, October, 1958); and other, like polymers; to a substantial extent in water dispersion at pH values and various combinations of the aforesaid polymers (in below 12, and certain compositions of matter comprising 5 cluding such inorganic polymers as the Wyoming-type such anionic polyelectrolytes. Thus, we have found the bentonite listed) each polyelectrolyte by itself or in com following compositions of matter, among others, useful bination with one or more of the others and/or weight as water-dispersible negatively charged flocculating agents agents such as barium sulfate and/or essentially non-ionic in the practice of our invention: commercial waterproof absorbents having high surface area per unit volume, phenolic glue obtained by methods well known and de 20 such as activated carbon and/or handling aids such as scribed in the prior art, and comprising generally the a finely ground synthetic calcium silicate having a heating of phenol, resorcinol, and aqueous formaldehyde, CaC/SiC) ratio of 25.3/51.7. Exceptionally good results at a phenol-resorcinol:formaldehyde ratio greater than are obtained through the use of resins containing car 1:1 under acidic conditions for several hours; the sodium boxylic groups, as in the case of those compositions of salt of hydrolyzed polyacrylonitrile having an average 25 matter comprising the sodium salt of the copolymer of molecular weight of about 200,000, and nitrogen content styrene and maleic anhydride specified above; however, below about 6 percent by weight; sodium polyacrylate it should be noted that this invention deals with the re having an average molecular weight of about 300,000; moval chiefly of water-insoluble materials of high molec synthetic anionic polymers containing carbohydrate resi ular weight by treatment with compositions of matter dues such as a commercial grade of sodium carboxy 30 comprising water-dispersible resins in some cases con methylcellulose having a degree of substitution of about taining carboxylic groups), in distinct contrast to the 0.80 sodium carboxymethyl group per anhydroglucose earlier work co-authored by one of us wherein is described, unit, and an average molecular weight of about 50,000, for the most part, the removal chiefly of water-soluble or the sodium salt of an acid-ester of starch having a materials of low molecular weight by treatment with sub molecular weight of about 100,000, and prepared by stantially water-insoluble resinous beads containing car acetylation and sulfonation of starch, according to pro boxylic groups (Robert Kunin and Ruth E. Barry, "Equi cedures adapted from Caldwell in British Patent 688,291, librium and Column Behavior of Exchange Resins from Carolles and Blondeau, in Rev. Sci., Ind. Paris, 15, Carboxylic, Weak Acid Types, Cation Exchange Resins,” 69 (1843), and from Tamba in Biochem. Z., 141, 274 Industrial and Engineering Chemistry, , 41, 1269.72 (1923), in the light of the information presented in Kerr, 40 (1949)). -"Chemistry and Industry of Starch, Second Edition, In any consideration of the following examples, it Academic Press, Inc., New York, 1950 (Chapter X, by should of course be kept in mind, as will be obvious to E. F. Degering, Derivatives of Starch, pages 259 to 323) those skilled in the art, that the optimum dosage of chem and in the "Encyclopedia of Chemical Technology, The ical coagulants for any particular sewage to be treated Interscience Encyclopedia, Inc., New York, 1954 (Vol is distinctly an individual problem, and can be best deter - Lime 12, pages 774 and 775; the sodium salt of the co mined only by actual tests (Babbitt and Baumann, "Sewer. polymer formed by the reaction of equimolar amounts of age and Sewage Treatment,' Eighth Edition, John Wiley styrene and maleic anhydride under conditions generally and Sons, Inc., New York, 1958, page 449; Water Works similar to those described in United States Patent 2,333,- and Sewerage, 81, 358 (1938)). However, we have 513, said copolymer having an average molecular weight 50 generally found the optimum concentrations of each of of about 100,000; the sodium salt of a sulfonated poly the chemical classes used in our invention-viz., cationic styrene having a degree of substitution of approximately polymer of the type herein described, iron ore weighting one sulfonate group per styrene nucleus, having an aver agent, and (optionally) negatively charged flocculating age molecular weight of about 10,000, and prepared agent-lie in the range of from about 1 to about 300 parts according to the general methods set forth in United States of chemical per million parts of aqueous liquid to be Patent 2,533,210 or United States Patent 2,533,211; the treated, and quite generally in the range substantially be Sodium salt of a sulfonated polystyrene having a degree of low about 10 parts of chemical per million parts of aque substitution of approximately one sulfonate group per ous liquor to be treated; that is, in specifying chemical styrene nucleus, having an average molecular weight of dosages, the numbers we actually give can be only ap about 70,000, and prepared according to the general meth 6) proximate, and, as it were, “order-of-magnitude” terms. ods set forth in United States Patent 2,533,210 or United Furthermore, in any consideration of the following States Patent 2,533,211; the product obtained by reacting examples, it should be kept in mind that the actual proc phosphoric acid and polyvinyl alcohol together and sub esses of treating and separating aqueous liquors in accord sequently neutralizing with cold aqueous sodium hydrox ance with our invention may involve modifications ide; phosphorylated starches obtained by treating corn 65 Such as, for example, the use of magnetic fields, centrifu starch with phosphorus oxychloride in pyridine, by a pro gation, electrostatic fields, or the like, in addition to, or cedure adapted from Samec, "Kolloidchemie der instead of, gravity to accomplish rapid separation ("sedi Starke, Steinkopff, Leipzig, 1927, said phosphorylated mentation”) of flocculated material-without departing starches having particular advantages in sewage-treating from the intended scope of our invention. In addition, processes wherein air is blown through the sewage (See 70 it should be kept in mind that greatly superior results to Green, "Biological Oxidation,” Scientific American, 199, these reported here may be expected in plant-scale prac 56-62 (July 1958)); Wyoming-type bentonite as it natu tice of our invention, particularly in embodiments em rally occurs in substantially the sodium form near Belle ploying in modified form such processes as the Guggen Fourche, South Dakota; the hydrogen form of Wyoming heim method (Sewage Works Journal, 104 (January. type bentonite, as obtained on treatment of Belle Fourche 75 1942); ibid., 973 (September 1944), or the Putnam meth 8,142,638 4. od (Babbitt and Baumann, "Sewerage and Sewage Treat Water, to the main body of the sewage), and separately ment,' Eighth Edition, John Wiley and Sons, Inc., New fron any anionic flocculating material, to obtain to maxi York, 1958, page 457) or modifications thereof. Finally, mum degree the synergistic effects of our invention. In it should be noted that optimum results, from both tech other words, to capitalize on the synergistic effect of the nical and economic standpoints, are achieved in the prac proper type of cationic polymer, as specified herein, and tice of this invention in accordance with the special proc ferruginous material, comprising iron ore weighting agent, esses described herein, and/or in the types of special treat in the combination disclosed herein, it is important that ing equipment specified herein or currently available for these components be mixed, or preferably ground, to Se. gether prior to addition to the aqueous liquor to be treated. In particular, in instances wherein cationic polymer, 10 In addition, use of such a pre-mixed combination makes Weighting agent, and negatively charged anionic focculat possible economy, ease of control, and ease of handling ing material are employed in the treatment of sewage, the in plant-scale operations. However, some degree of clari proportions of the two materials used is frequently of im fication normally may be effected by mixing these com portance in determining rapidity and completeness of ponents during admixing of the clarifying material with focculation, and overall cost of treatment. Again, for 5 the aqueous liquor to be treated. best economy of operation, it may be desirable in some We have found that the order in which various clarify treating plants, and in particular in some sewage treating ing agents are added may be of importance in some cases, plants, as where the settled solids from the flocculation and special equipment of the type described above is well tanks are dried and burned, to recover at least the iron adapted to take advantage of any efficiencies and/or econ ore weighting material from the burning step, and recycle 20 omies of operation which may be realized through appro at least part of the ferruginous material through the set priate changes in the order and/or method by which our tling process again and again, by means of equipment treating chemicals are added to aqueous liquors. Best re adapted for such purpose. In such recycling operations, sults are obtained, for example, in the treatment of many of course, it should be kept in mind that the most gen sewages (e.g., sanitary sewages, certain raw water Sup erally applicable clarifying agents in the practice of our 25 plies) if negatively charged (i.e. anionic) flocculating ma invention contain from about 1 to about 100 parts of terial is added before the cationic clarifying agent. cationic polymer and from about 1 to about 100 parts of The tests of clarification of aqueous liquors (sewages) iron ore weighting agent, and that in processes wherein set forth in the examples below were run in standard negatively charged (anionic) flocculating material is used Imhoff cones, according to a method adapted from the in addition to cationic clarifying agent comprising cati 30 standard procedure for sewage sedimentation tests set onic polymer and ferruginous material (iron ore weighting forth in the book, “Standard Methods for the Examination agent), the optimum dosage of such negatively charged of Water, Sewage, and Industrial Wastes.' Tenth Edition, flocculating material will generally be about equal to the published in 1955 by the American Public Health Asso dosage of cationic clarifying agent, but may vary, in some ciation, of New York City (page 272). In each instance, instances, from as little as one hundredth to as much as a 35 the aqueous liquor to be processed was poured into a hundred times as much. Again, special equipment may standard Imhoff cone having a capacity of 1000 milliliters, often be desirable for the pre-dispersion prior to intro the chemical reagent(s) added at the top, the liquor con duction into the main body of aqueous liquor to be treated, position stirred for approximately ten seconds with a glass for we have found that our treating agents generally work rod 6 millimeters in diameter and 40 centimeters long, and most efficiently when added in the form of dilute disper 40 the whole composition then allowed to settle for 7% to 60 sions. In the formulation of these dilute dispersions, we minutes. In instances where the chemical treatment was have found that rapid and vigorous agitation of the dry done in two stages, as in the cases below wherein a "First clarifying agent powder in about 30 to 300 times its weight Stage” and "Second Stage” are specified, the chemicals of water gives good results, especially if some heat is ap were added in the “Second Stage,” with the same amount plied to the slurry during the mixing step. Thus, in using of stirring after each stage of treatment, and generally both cationic clarifying agent and negatively charged foc 45 with the elapse of only 30 to 60 seconds between the two culating material in the treatment of aqueous liquor (i.e. stages of chemical treatment. In a few cases where mag sewage), it may sometimes be advantageous to use a netite was included in the ferruginous material, sedimen treating device consisting of a large settling tank fitted tation was accelerated by placing a powerful permanent with a gentle-agitation device, and two smaller mixing magnet under the cone. Novel features and/or modifica tanks, each of which is fitted with vigorous-agitation de 50 tions of the general processes of our invention where such vices and perhaps also heaters, said large settling tank and features are mentioned herein, such as the use of a mag said smaller mixing tanks being connected by valved pas netic field to speed sedimentation, are intended to be in sageways, and where necessary, pumps. in equipment of cluded within the scope of the process claims. Since a this type, the cationic clarifying agent and iron ore weight major reason for employing chemical treating agents is to ing agent may be dispersed rapidly in one tank, the nega reduce the size of the treating equipment, settling times tively charged flocculating material dispersed in the other of 74 to 15 minutes have generally been used for the tank, and the two silurries then added slowly to the larger comparison of various treating agents, rather than the settling tank in a proportion determined by the valves more conventional retention periods of 1 to 3 hours. and/or pumps in the passageways connecting the tanks. Imhoff cones are shallow, as compared to plant-scale set In the invention claimed herein, the cationic polymer and 60 tling equipment, and commercial experience has shown re the iron ore generally should be mixed dry, and predis peatedly that completeness of flocculation, sedimentation, persed separately from any anionic flocculating material and B.O.D. (Biochemical Oxygen Demand) removal, that may be used; however, it is possible, but generally economy and efficiency of operation, and so forth, are not as convenient, to disperse the cationic polymer in generally enhanced by using treating tanks more than 7 water in one tank, disperse the iron ore weighting agent feet deep, recycling at least part of the sludge, and so separately in another tank, and then mix these two slurries forth. Accordingly, the results given in the following with the sewage, all separately from the dispersion of any tables should be interpreted in the light of the conditions anionic flocculating material in the sewage. If the cati of operation, and it would be appreciated that much bet onic polymer is dispersed in the main body of Sewage, 70 terresults may be expected in plant-scale operations. and the iron ore is then added, much of the iron ore will The clarity index of the supernatant liquor obtained in simply drop to the bottom of the tank, without becoming our tests after various periods of sedimentation was meas enmeshed as an integral part of the floc formed. It is ured by observing the amount of light, in foot-candles, important. in other words, to add the cationic polymer transmitted through a layer of supernatant liquor 5 inches and the iron ore together (either dry or predispersed in 75 thick, from a white-light source of constant intensity. 3,142,638 5 6 Raw, unsettled aqueous liquor, before chemical or me about 1,000,000. The ferruginous material employed in chanical treatment of any kind, was assigned a “Clarity the “FIRST SERIES” comprised iron ore and/or ferric Index” of 100. The “Clarity Index” of a treated liquor chloride, said iron ore consisting of hematite from the was calculated by dividing the amount of light, in foot Mesabi iron Range of northern Minnesota, in the United candles (from the white-light source of constant intensity States, and graded so that substantially all of the iron ore previously described), transmitted through a layer of the passed, through an 80-mesh U.S. Standard Screen, but was treated liquor 5 inches thick, by the amount of light, in retained on a 100-mesh U.S. Standard Screen, while the foot-candles, transmitted from the same light source ferric chloride employed was an ordinary grade (so-called through a layer of raw unsettled liquor 5 inches thick "sewage-treatment grade') of ferric chloride. The under the same conditions, and then multiplying the re (anionic) “organic polymer' (flocculating material) Sultant ratio by 100. For example, if the amount of 0 specified in the "FIRST SERIES” was a styrene-maleic light transmitted under the standard conditions described anhydride copolymer of the type made by the general was 6 foot-candles in the case of treated liquor and only method set forth in U.S. Patent 2,333,513, and charac 4 foot-candles in the case of raw unsettled liquor, the terized by a molecular weight of about 100,000. The "Clarity Index” of the treated liquor was calculated to bentonite employed was a Wyoming-type bentonite, pri be (%) x 100, or 150. The “B.O.D. Index (Biochemi 15 marily in the sodium form, obtained in commercial de cal Oxygen Demand Index) was calculated in somewhat posits near Belle Fourche, South Dakota. “Cost of analogous fashion: the "B.O.D. Index,” as set forth in Chemicals per Million Gallons of Sewage Treated,” the tables below, refers to a calculated index value ob wherever presented in this bulletin, is based on the ap tained by measuring the proportion of biochemical oxy 20 proximate 1959 costs of materials, f.o.b. St. Paul, Minne gen demand removed from the raw liquor by chemical sota, U.S.A.: $0.0125 per pound of Wyoming bentonite; treatment of the type specified in the table, multiplying $0.01 per pound of Mesabi iron ore; $0.05 per pound of this quantity by 100, and finally dividing by the pro technical-grade ferric chloride; $0.17 per pound of cat portion of biochemical oxygen demand removed from ionic corn starch; and $0.50 per pound of styrene-maleic the raw unsetled liquor by simple settling over the length 25 anhydride copolymer. Only approximate costs are given, of time specified in the table. For example, if the bio since the synergistic effects obtained by interaction of the chemical oxygen demand of supernatant liquor recovered components in our combinations frequently show a de from a given type of chemical treatment of an aqueous gree of effectiveness at least double-and sometimes ten liquor, after a given period of settling, was found to be times or more-that which might be reasonably expected 40 percent lower than that of the raw unsettled aqueous 30 on the basis of the performance of each of the separate liquor, whereas the supernatant liquor obtained by simple ingredients of our combinations. Notice, for instance, settling of the same type of aqueous liquor was found in this “FIRST SERIES, that very small amounts of our to have a biochemical oxygen demand only 20 percent type of additive, used in accordance with our invention, below that of the raw unsettled aqueous liquor, the effects clarification of sewage at a tiny fraction (see Ex "B.O.D. Index” of the chemically treated aqueous liquor 35 ample 2) of the costs involved in admittedly unsuccessful would be calculated to be (4%0) x 100, or 200. attempts to clarify sewage to roughly the same degree The sanitary sewage used in the “FIRST SERIES” of by means of the component chemicals of our composi examples below was taken from the municipal sewage tions, used separately (see Examples 6, 7, 8, 9 and 10), or system of a small city in the north central part of the conventional chemicals conventionally used (Example 7). FIRST SERIES Sanitary Sewage

Chemical treatment Observed effects of chemical treatment Cost of Amount of cationic clarifying After 7% min. After 15 minutes of settling chemicals Inaterial used of settling per Example - Amount of negatively illion No. charged flocculating gallons material added Clarity Clarity Of Cationic Ferruginous (p.p.m.) Settled index of Settled index of B.O.D. Sewage starch material solids Super- solids Super- Index treated (p.p.m.) (p.p.m.) (ml.) natalint (ml.) natant fluidi fluid

1------3 (40,60 iron ore! 3 (2000/1 bentonited 4.05.0 342 8.56.0 138122 ------GO 0.002.01 Fe Cl3). org. polymer). 9 (40/50 iron ored 9 (2000/1 bentonited 4.0 136 13.0 140 ------6.05 Fe(Cl). org, polyaer). 15 (40/60 iron ore, i5 (2000, bentonited 3.0 49 33.0 149 269 0.05 FeCl3). org. polymer). 30: 60 iron Orel ------25.0 36 20, 0 36 225 7.00 30 (ironeCl3). ore only) 4.0 25 4.5 125 143 2.50 30 (Fe(Cl3 only) 14.0 25 5.0 28 25 12.50 3.5 23 5.0 28 104 3.2 30 (org. polymer 3.5 123 4.5 125 141 25.00

only). ------3.5 23 5.0 26 49 42.50

United States, and contained all of the usual types of In the case of preferred embodiments of our invention household and sanitary wastes, but essentially no indus (such as given in Examples 2 to 4 inclusive), the flocs trial wastes. All of the examples (1 to 10 inclusive) formed on treatment of sanitary sewage are coarse and of the “FIRST SERIES” involved the use of aliquots of tough; there is some breaking up of the floc on vigorous the same batch of municipal sewage, having a chemical 70 stirring, but the floc reforms almost immediately on ces composition approximately normal for sanitary Sewage sation of agitation, and settles rapidly and well, usually in the United States, and being characterized by a pH of compressing in the sludge form over a period of time. 7.6. The cationic starch employed in the "FIRST When the sewage composition formed by adding cationic SERIES” was a cationic modified corn starch having ap polymer of the type described herein and magnetite iron proximately one amino group per 20 anhydroglucose 75 ore having a particle size smaller than 50 mesh (U.S. units, and was characterized by a molecular weight of Standard Screens) is subjected briefly to a strongmag 3,142,638 17 S netic field, the flocs appear to form far more rapidly, and chilled and concentrated, and the product used as a p are coarse and tough, even if the magnetic field is not em aminobenzyl starch/ferric hydroxide combination, usually ployed to effect rapid separation of the solids from the in combination with iron ore of fine particle size. aqueous portion. In Example 16, there was used as negatively charged In the "SECOND SERIES” of examples, tests were con flocculating material, phosphorylated corn starch pre ducted according to methods generally similar to those pared according to a method adapted from Samec, employed in conducting the tests set forth in the “FIRST "Kolloidchemie der Starke,” Steinkopff, Leipzig, (1927) : SERIES” above, except insofar as an industrial (packing 3 grams of corn starch was dispersed in 20 grams of house) waste, containing only a minor component of pyridine, and 2.8 grams of phosphorus oxychloride added sanitary (domestic) sewage, obtained in a small city in O cautiously and with vigorous stirring. This mass was the north central part of the United States, was employed heated on a hot water bath at 90° C. for 60 minutes with as aqueous liquor to be treated. The cationic starch, fer agitation, and the pyridine removed by further heating ruginous material (comprising iron ore except in Exam under vacuum. SECOND SERIES Industrial Waste

Chemical treatment Observed effects of chemical treatment Cost of Amount of cationic clarifying After 10 minutes of perchemicals million Example material added settling gallons of No. Amount of negatively sewage charged flocculating treated material added Settled Clarity (dollars) Cationic starch Ferruginous material (p.p.m.) solids index of (p.p.m.) (p.p.m.) (ml) superna tant fluid

ll------2.2 110 0.00 12------1.2------6 (4060 iron ored 6 (2000/1 bentonited 36.0 150 4.02 FeCl3) org. polymer) 18------3.0------15 (40.60 iron ore, 15 (2000, bentonitel 400 155 0.07 FeCls) org. polymer) 14------6.0------30 (40.60 iron ore? 30 (2000, bentonited 70.0 160 20.14 FeCls) org. polymer) 15.------3.6benzyl (p-amino- 8 (Fe(OH)3).------18org. (2000/1 polymer) bentonitel 60.0 150 ------starch) 16------3.6------6 (40/60 iron ore 6 (phosphorylated 33.0 140 ------FeCls) corn starch)

ple 15), bentonite, and “organic polymer employed in In the “THIRD SERIES” of examples set forth below, this series of experiments were the same types as those tests on the clarification of two contaminated raw water set forth in the “FIRST SERIES” above, with two excep 40 supplies are set forth. Except where otherwise specified, tions: Examples 15 and 16. the cationic starch, ferric chloride, iron ore, organic poly In Example 15, “p-aminobenzyl starch' is specified in mer, and bentonite employed were the same types respec the column with the heading "Cationic Starch (p.p.m.)” tively as were employed in the “FIRST SERIES” of ex in the table identified as “SECOND SERIES' (Industrial amples set forth above, and the tests of the "THIRD Waste)” below. In this example, there was used, instead 45 SERIES' were conducted in a fashion generally analogus of the amino starch utilized in the "FIRST SERIES,' p to that employed in the "FIRST SERIES.” The raw aminobenzyl starch, which is a cationic starch of the type "lake water” specified in the following table was drawn described by Pancirolli, Boll, reparto fibre tessili vegetali from Lake Johanna, a small lake (about 210 acres) in a regia staz sper ind carta e fibre tessili vegetali, 32, 314 heavily populated residential area of Ramsey County, (1937). This starch was made by methods adapted from 50 Minnesota, and was generally turbid, evidently contami Gaver, U.S. Patent 2,518,135, with the nitro groups of nated by Sewage and/or septic-tank effluents draining into the intermediate p-nitrobenzyl starch being reduced by the lake from near-by residences. The raw "well water” a method adapted from those set forth by Schriner and (for the purposes of this disclosure, "sewage') specified Fuson, "The Systematic Identification of Organic Com in the following table was drawn from a shallow well pounds,” John Wiley and Sons, Inc., New York, (1945), 55 only 92 feet deep, situated in the Arden Hills area of pages 74 and 75, and Weygand, “Organic Preparations,” Ramsey County, Minnesota, wherein the only available Interscience Publishers, Inc., New York, (1945), pages method of disposal of sanitary sewage, at the time of the 218-222: 4 grams of sodium hydroxide was dissolved in experiments disclosed herein, involved the use of septic 50 milliliters of ethyl alcohol, and the alcohol-insoluble tank and cesspool systems, drain fields, and similar ex portion filtered off. 5 grams of corn starch was then 60 pedients, which tend to lead to some degree of contami added to the alcoholic caustic, and the mixture refluxed nation of underlying water-bearing strata. The "cross at its boiling point for 4 hours with vigorous agitation. linked amino starch” specified in Example 21 was a ca The refluxed material was then filtered, the filtered prod tionic modified corn starch having approximately one uct washed with alcohol, then with ether, dried, and tertiary dimethylamino substituent group per 20 anhy dispersed in 200 milliliters of petroleum ether. 4.8 grams 65 roglucose units, and being cross-linked in the manner of para-nitrobenzyl chloride was added to this mixture, described in U.S. Patent 2,500,950 to a molecular weight and the mixture refluxed at its boiling point (ca. 100 of several millions. The "hydrogen bentonite” specified C.) for 6 hours. After this heating period, the product in Example 21 was prepared in the following manner: (apparently para-nitrobenzyl starch) was filtered off, and 10 grams of Wyoming-type bentonite, from the Belle dispersed in a mixture of 900 grams of water, 45 grams 70 Fourche (South Dakota) deposits was dispersed in 510 of copperas (FeSO47H2O), and 3.6 grams of sulfuric grams of 0.7 percent aqueous hydrochloric acid, and the acid. To this mixture was added a solution of 108 grams resultant dispersion allowed to stand for 336 hours. At of 50 percent aqueous potassium hydroxide and 360 mil the end of this period, 420 grams of clear supernatant liliters of 95 percent ethyl alcohol. The whole mass liquor was decanted, and the remaining 100 grams com was thoroughly mixed and heated for 5 minutes at 90° C., 75 prising the hydrogen bentonite used in the treatment of 3,142,638 3. 20 aqueous liquor. Sizes of iron ore are specified in mesh equipment. Floc produced in the practice of this inven sizes in Examples 17, 18, 19, and 22-for example, tion is coarse and tough, and can be handled without (-48-1-60) indicates passing through 48 mesh U.S. great danger of permanent re-dispersion; moreover, the Standard Screen, and retained on 60-mesh U.S. Standard settled floc gradually compresses down, over a period of Screen. (In general, iron ore mesh size in other exam time, into a sludge of high solids content, and remarkably ples set forth in this disclosure-where not otherwise low volume content per unit volume of sewage treated. specified lay in the range of -60-200 (passing No deleterious effect has yet been observed on the diges through 60-mesh, and retained on 200-mesh, U.S. Stand tion, filtration, or dispersion characteristics of sludges ard Screens)), obtained in the practice of our invention. The super THIRD SERIES Raw Water Samples

Chemical treatment Example Amount of cationic clarifying Arnout of nega No. Raw water supply material added tively charged Observed effects of chemical treatment focculating nate ria added Cationic starch Ferruginous (p.p.m.) (p.p.m.) material (p.p.m.) 17------Ramsey County 12------60 (4C,60 iron ore 30 (2000/1 benton- Slow and incomplete focculation, much of iron ore we water. (-48-60)f itelorganic dropped to botton of container before foc formed. FeCl3). polymer). 18------do------12------60(-80-100)f (4050 iron ore 30itefolganic (2000/1 benton- Excellentslower than and in Sanitarycomplete sewage. flocculation, Ore apparently but somewhat helped EeCl3). polymer). form floc, and settled as part of floc. 19------do------12------60 (4060 iron ore 30 (2000/1 benton- Characteristic floc formed, but settled very slowly. (-200)/Fecla). itefiorganicpolymer). 20------do------l"------11 (FeCl3).------21 (bentonite Slow formation and settling of floc. Noticeably improved only). visual clarity after 3 hours of standing. 21------Lake Johanna 300 (cross-linked 3 2 (Fe(OH)3).------1000 (hydrogen Clarity index of 10 after 7% minutes, 124 after 30 minutes, lake Water. cationic starch). bentonite). and 126 after 60 minutes. Apparent reduction of con - tent of dissolved mineral Solids. 22------Ramsey County 8------3 (iron ore .------Slow focculation, and slight tendency for iron ore to well water. (-80--100)). Settle out ahead of floc. 23------do------8------3 (FeCl3).------Slow flocculation and settling, but noticeable increase in visual clarity, after 3 hours.

1 Added separately to raw water. 2 Fe(OH)3 was dispersed in the water prior to addition of cross-linked cationic starch. EXAMPLE 24 natant liquor obtained in the practice of preferred em After the experiment set forth in Example 16 had been bodiments of our invention-even after only 15 minutes conducted in an Imhoff cone, it was run on a somewhat of Settling in the case of a typical sanitary sewage-fre larger scale, in a 5-gallon jar, with the bubbling of air quently has sparkling clarity comparable or even superior from the bottom of the jar, up through the sewage con to that of many municipal water supplies. taining suspended and/or dissolved organic solids, in The mechanism underlying the remarkable synergistic cluding the nitrogen-containing cationic starch and the effect which forms the basis for our invention is some phosphorus-containing phosphorylated starch. Bubbling 45 what obscure; however, it is thought that some type of air through the flocculated mass did not break the floc up interaction between the ferruginous material (iron ore seriously, and after the air agitation (aeration/activation) Weighting material) and cationic starch over and above had been stopped, sedimentation was extremely rapid and purely ionic interaction may be involved. It seems con entirely satisfactory. Result obtained appeared to be ceivable, for example, that quasi-covalent bonds or at generally parallel to those obtained in Example 16. How 50 tractive forces may be operative between iron in the ore ever, there is some evidence that in this type of aeration/ and the amine and/or hydroxyl groups of the cationic activation process, the flocculating agents of our inven Starch. tion actually enhance-perhaps by catalytic and/or nu In most of the examples presented above, the practice trient roles-the biological reactions taking place. of our invention has been illustrated in applications in As the above examples make amply clear, a remark 55 volving sewages and/or industrial wastes containing very able synergistic effect is obtained when cationic starch Substantial concentrations of fecal matter and/or other and ferruginous material are used in combination in the waste solids. As the examples of the “THIRD SERIES' treatment of aqueous liquor, with or without Subsequent illustrate, however, certain embodiments of our invention treatment of the aqueous liquor by negatively charged may also be practiced advantageously, in some instances (anionic) flocculating material. In consequence of this 60 at least, in the purification of aqueous liquors containing unique and unexpected effect, low concentrations of our much smaller concentrations of fecal matter or other con chemicais serve for the flocculation and sedimentation taminating materials. of organic as well as inorganic suspended solids in Methods of preparing others of the compositions of aqueous liquors, generally some dissolved organic solids, matter to which we refer above, comprising cationic syn and in one embodiment even some dissolved mineral 65 thetic organic polyelectrolytes and useful as additives for solids. The importance of this synergistic effect is best Sewage are set forth in the examples that follow. The realized by comparing the chemical cost of treatment, by amount of any one of these additives most advantage means of our preferred combinations, with the apparent ously used in the treatment of a given volume of sewage chemical costs necessary in the case of any one of our depends, of course, on the character of the sewage treated. ingredients used alone to produce comparable results. 70 Moreover, the amazing speed with which flocculation EXAMPLE 25 and sedimentation occur in the practice of our invention 2 grams of a polymerized ethylene imine composition in its preferred embodiments, particularly in the treat (50 percent solids in water) having chiefly secondary ment of sanitary sewages, makes possible substantial amine groups and some primary amine groups and being reduction in the size and hence the cost of the treating 75 characterized by an average molecular molecular weight 3,142,638 2. 22 of about 50,000 was dispersed in 100 grams of water, and tageously be varied-that is, be made either similar or 3 grams of hematite (iron ore) having an average par opposite. Again, when sewage is treated with a composi ticle size of about 80 mesh (U.S. Standard Screens) added tion of matter comprising from about 1 to about 100 with vigorous agitation. The resulting mixture was as parts by weight of water-dispersible synthetic organic poly signed the designation "Reagent A,” and was used as an electrolyte and from about 1 to about 100 parts by weight additive for sewage at a concentration of from about 0.1 of weighting material and/or from about 1 to about 100 to about 10 grams but usually about 1.0 gram of Reagent parts by weight of inorganic polyelectrolyte, it is fre A per 1000 grams of sewage treated. quently advantageous also to add to the sewage flocculating EXAMPLE 26 material of an electrical charge opposite to that of the 2 grams of polymerized ethylene imine composition (50 0 water-dispersible synthetic organic polyelectrolyte em percent solids in water) having chiefly secondary amine ployed. groups and some primary amine groups and being charac In the following table of examples of novel sewage com terized by an average molecular weight of about 50,000 positions (“FOURTH SERIES”), “Reagent A,” Reagent was dispersed in 100 grams of water, and 3 grams of iron B,” and “Reagent C” refer to additives for sewage pre oxide containing (pinkish) bauxite type material (alu 5 pared according to the methods set forth in Examples 25, minum oxide) having an average particle size of about 26, and 27 above. 100 mesh (U.S. Standard Screens) added with vigorous “Reagent AA' refers to a composition obtained by agitation. The resulting mixture was assigned the designa mixing together 100 grams of water 3 grams of a com tion "Reagent B,' and was used as an additive for sewage mercial grade of ferric chloride having an empirical for at a concentration of from about 0.1 to about 10 grams, 20 mula corresponding to FeCl36H2O. but generally about 1.0 gram of Reagent B per 1000 “Reagent CC' refers to a composition obtained by grams of sewage treated. mixing together 100 grams of water and 3 grams of a predominantly sodium-base clay of the type commonly EXAMPLE 27 known as Wyoming-type bentonite and being a so-called 1.5 grams of hematite (iron ore) having an average 25 “high-yield” material recovered from the Belle Fourche particle size of about 80 mesh (U.S. Standard Screens) (South Dakota) deposit of such clay. was added, with vigorous agitation, to 50 grams of "Rea The “FOURTH SERIES” (Examples 28 to 36 in gent B” prepared as described in Example 26. The re clusive) were conducted according to methods generally sulting mixture was assigned the designation "Reagent C,' similar to those employed in conducting the first three and was used as an additive for sewage at a concentration 30 “SERIES” of examples, except insofar as a combined of from about 1 to about 10 grams, but usually about 1.0 sewage, having as its major component industrial (pack gram of “Reagent C” per 1000 grams of sewage treated. ing-house) waste and having as only a minor component Additives for sewage formulated as described in above sanitary sewage from a small city in the north central Examples 25, 26, and 27 may be employed to provide novel part of the United States, was employed in this sewage compositions from which suspended solids settle 35 “FOURTH SERIES” of examples. FOURTH SERIES

Chemical treatment Observed results of chemical treatment First stage Second stage After 7% minutes After 5 Iainutes After 30 minutes of Settling Example No. of settling of settling Amount Amount Clarity Clarity Clarity Reagent of reagent Reagent of reagent Settled of super- Settled of super- Settled of super- B.O.D. added added, gr. added added, gr. solids, ml. natant solids, ml. natant solids, ml. natant Index fluid fluid fluid 28------(1) (1) (1) (1) 2.2 20 3.0 20 3.8 150 29------AA 3.0 3.3 20 5.0 180 7.0 80 80------CC 1.0 3.0 180 5.0 200 8.5 220 31------A. 1.0 3.0 190 3.0 190 13.0 200 32-- A. 1.0 CC 1.0 47.0 470 40.0 510 32.0 50 33.-- B i. 0 11.0 230 3.0 260 11.0 300 34-- B ... O CC i.0 34.0 330 3.0 370 26.0 420 35-- -- C ... O 24.0 290 20.0 300 17.0 330

36------C 1.0 CC 1.0 49.0 560 43.0 700 32.0 790 1 Raw or can be removed rapidly in treating mechanisms of It should be emphasized that our invention, as set forth simple design and modest size. Generally speaking, we herein, involves the use of cationic polymers and weight have found addition of from about 1 to about 30 parts of ing agents in the treatment of sewage, although we have additive solids per million parts of sewage treated to be 60 found that some degree of clarification of sewage-type satisfactory from a cost/performance standpoint in the liquors is possible with anionic polymers and weighting treatment of most types of sewages. At any rate, pre agents. Such degree in some cases may provide the basis ferred embodiments of our invention of novel sewage com for an economically feasible method of clarification, par positions generally contain from about 1 to about 300 ticularly if (as suggested above) the anionic polymer is parts by weight of synthetic organic ionic polyelectrolyte 65 resistant to degradation by heat, oxidation, hydrolysis, per million parts of sewage, and from about 1 to about bacterial attack, or such like and the anionic polymer/ 300 parts by weight of weighting agent and from about weighting agent combination (optionally) along with in 1 to about 300 parts by weight of water-dispersible in organic anionic flocculating material (such as bentonite) organic ionic polyelectrolyte. We have also found that is employed in some processes such as (1) treating of in a single-step sewage treating process, the charges on the 70 the sewage-type aqueous liquor with the anionic polymer/ synthetic organic ionic polyelectrolyte and (if any) water weighting agent combination, (2) settling the flocculated dispersible inorganic polyelectrolyte in the additive com solids containing most of the sewage solids, the anionic position employed generally should be similar, whereas in polymer, and the weighting agent, (3) degrading the a multi-stage process the charge on the polyelectrolytes sewage solids, but not the anionic polymer or the weight employed in successive steps of the process may advan 75 ing agent (to any really significant extent), by hydrolysis, 3,142,638 23 24 oxidation, heat, bacterial attack or such like, in a vessel McQueen, “Dispersion Characteristics of Montmoril (preferably) separate from the settling/sedimentation ves lonite, Kaolinite, and Illite Clays in Waters of Varying sel, and (4) recycling the undegraded polymer and weight Quality, and Their Control with Phosphate Dispersants,” ing agent from the degradation vessel (if such is used) Geological Survey Professional Paper 334-G, U.S. De along with make-up chemicals back into the main settling partment of the Interior, Superintendent of Documents, sedimentation vessel. The anionic polymers of utility in Washington, 1960, especially pages 233-4), by precipita this type of process are generally acidic, containing car tion, or otherwise. Alternatively, of course, the aeration boxylic, sulfonic, phosphorus-containing acids, or other may be performed on (optionally, porous) beds of parti acidic groups, or some combination of these classes of cles comprising copper materials, across copper-bearing acidic groups, have molecular weights in excess of 10,000, O screens, or such like. Our catalytic method of oxidation are substantially linear, preferably hydrophilic, water is of great interest, of course, in such Sewage-treating dispersible, and contain at least one acid group per 10,000 tnethods as the Zimmerman process (Bogan, Proc. Am. units of molecular weight. (Thus, Reagent "H' was Soc. Civil Engrs. 85, No. SA4, 13-23 (1959)). prepared by adding 2 grams of activated carbon, having EXAAPLE 3 an average particle size smaller than 200 mesh (U.S. 5 In this experiment, compounds of various metals were Standard Screens) to 100 grams of a mixture obtained added to 1000-milliliter samples of raw sewage in quan by admixing 2 grams of magnetite (iron ore) having an tities as indicated in the table below. The samples were average particle size of about 80 mesh (U.S. Standard aerated for ten minutes by bubbling air through a fritted Screens) and 100 grams of a dispersion obtained by mix glass funnel one and one-half inches in diameter from ing 3 grams of a predominantly sodium-base montmori 20 the bottom of the sewage, up through the sewage, while lonite clay of the type commonly known as Wyoming said sewage was contained in a standard Imhoff cone of type bentonite and being a so-called “high-yield' material 1000-milliliter capacity. Then 3 parts of Additive "Q” recovered from the Belle Fourche (South Dakota) de per million parts of sewage was added to each of the posit of such clay, 100 grams of water, and 15 grams aerated sewage compositions, said Additive "Q" having of an aqueous dispersion containing 1 percent by weight 25 been dispersed in water, at a solids concentration of 3 of the sodium salt of a copolymer of styrene and maleic percent by weight, approximately 30 minutes prior to hydride formed by reaction of equimolar amounts of addition to the sewage, said Additive "Q' consisting of styrene and maleic anhydride under conditions generally cationic starch, of the type employed in Example 2 above, similar to those described in United States Patent 2,333,- Mesabi hematite, and anhydrous ferric chloride, in a 513. 1 gram of Reagent 'H' so prepared was dispersed 30 cationic starch: hematite:ferric chloride ratio of 1:2:3. in 1000 grams of a raw water from a shallow well only Each sewage composition was stirred for a few seconds, 92 feet deep, situated in a relatively heavily populated and 3 parts of Additive 'R' per million parts of sewage part of Ramsey County, Minnesota, wherein the only cur next added to each of the sewage compositions, said rently available method of disposal of sanitary sewage Additive “R” having been dispersed in water, at a solids involved, at the time of this experiment, the use of septic 35 concentration of 3 percent by weight, approximately 30 tank and cesspool systems, drain fields, and similar expedi minutes prior to addition to the sewage, said Additive ents, all of which tend to lead to some degree of con “R” consisting of Belle Fourche bentonite, of the type tamination of underlying water-bearing strata. After 1 employed in Example 2 above, and styrene-maleic an hour of standing, the Supernatant liquor of the treated hydride copolymer, of the type employed in Example 2 water (“sewage') was observed visually to have appre 40 above, in a bentonite:copolymer ratio of 2000:1. The ciably better clarity than untreated raw water, but it was sewage composition was again stirred for a few seconds, apparent that this system of treatment did not approach and then again aerated for ten minutes by the same in efficiency the effectiveness of our cationic polymer/ method as before. The samples were finally allowed to weighting agent systems.) settle for 15 minutes. A 200 cc. aliquot was removed It has been noted above that certain metals or metal 45 from the top of each sample and tested for dissolved oxy compounds, added to or placed in contact with sewage, gen by the "Dissolved Oxygen Test,” as set forth in may act as oxidation catalysts for the solids therein. "Standard Methods for the Examination of Water, Sew Such catalysts have proved to be especially effective for age, and Industrial Wastes,' the standard reference al the degradation of sewage solids by aeration, in the prac ready mentioned previously herein. A standard Bio tice of our invention, although it should be realized that 50 chemical Oxygen Demand test was also performed on metals and metal compounds generally are regarded as the samples with the best dissolved oxygen results and undesirable in the aeration of sewage of such like. (See on a sample of raw sewage to which no catalyst (metal “Betz Handbook of Industrial Water Conditioning,” Third material) had been added. Edition, W. H. & L. D. Betz, Philadelphia 24, Pa., 1950, pages 1 to 6 inclusive; O'Neill, Inst. Sewage Purif., J. 55 Dissolved Proc. 1957, Pt. 2, 150-2, as abstracted in Chemical Ab Concen- oxygen Bio tration of content chemical stracts, 53, 22639g (1959).) It should be noted also Sample reagent immedi- oxygen No. Reagent Solids ately demand that, of the many metals and metal compounds listed as (p.p.m.) after 2d. 5-day having some utility as catalysts in the treatment of sew aeration (p.p.In.) age or such like, certain ones are essentially ineffective 60 (p.p.m.) except on very specific types of sewage solids under very Zinc sulfate------2.0 4.5 specific conditions, while others of the metals or metal Manganese Suifate-...- 2.0 O compounds, listed have fairly broad utility as catalysts Chronite.------2.0 O Copper acetate--- 2. 5.1 for the oxidation of solids in, for example, sanitary sew Manganese ore----- 2.0 O ages. We have found copper materials (e.g., soluble Manganous oxide-- 2.0 G Nickel acetate------0.3 O copper salts) especially useful as catalysts in the oxidation Ammonium molybdat. 0.3 O of municipal sewage: copper materials are effective at Silver nitrate------0.3 O Zirconium Stilfate. - 2.0 O very low concentrations, are inherently cheap, and can Cobait sulfate------0.3 2.5 be removed from the treated sewage (if necessary) by Polymerized ethyleneinine- 2.0 0. absorption on regenerable ion exchanger (see Kunin and Ilmenite composition.------2.0 1.0 Barry, Industrial and Engineering Chemistry, 41, 1269 Raw sewage-no aeration.--- O O (1949) and Kunin and Myers, “Ion Exchange Resins,” John Wiley & Sons, Inc., New York, 1950, especially in the table above, Reagent denotes a commercial pages 26-37, 128, and 135) or on a disposable ion ex grade of ZnSOAHO; Reagent II a crude commercial changer such as montmorillonite (see Rolfe, Miller, and 75 grade of manganese sulfate containing about 65 percent 3,142,638 25 26 by weight of manganese sulfate, 10 percent by weight of as "38-B-Supernatant from Flocculation"-was siphoned ferrous sulfate, 7 percent by weight of silica, and minor off. 4,000 cc. of 38-B-Supernatant from Flocculation amounts of oxides, sulfates, and phosphates of other ele was poured into a vertical cylindrical tube about 3 inches ments; Reagent III an air-floated chromite having an in diameter by five feet high, and compressed air (as tiny average particle size such that 95 percent passed a 325 bubbles) passed through the sewage in this tube from the mesh U.S. Standard Screen, and having a chromium bottom of the tube, through a fritted glass funnel about oxide content of about 44 percent by weight, an iron 1% inches in diameter, for 2% hours. The treated liquor oxide content of about 25 percent by weight, a mag obtained from this aeration was designated as “38-C- nesium oxide content of about 10 percent by weight, a Treated Liquor from Flocculation and Uncatalyzed Aera silica content of about 10 percent, the remainder being IO tion.” oxides, silicates, and the like of various other elements, Another sample of 4,000 cc. of 38-B-Supernatant from especially aluminum and titanium; Reagent IV an essen Flocculation was poured into a vertical cylindrical tube tially chemically pure grade of copper acetate; Reagent about 3 inches in diameter by five feet high, and 2 parts of V a crude manganese oxide/silicate ore having a man copper acetate per million parts of 38-B-liquor was ganese content of about 41 percent, an iron content of 5 added, with thorough mixing. Next compressed air (as about 5 percent, and a particle size of about 100-mesh tiny bubbles) was passed through the sewage in this tube, (U.S. Standard Screens); Reagent VI a crude grade of from the bottom of the tube, through a fritted glass funnel manganese dioxide having a manganese content of about about 1/2 inches in diameter, for 2/3 hours. The treated 48 percent and an average particle size of about 100 liquor obtained from this aeration was designated as “38 mesh (U.S. Standard Screens); Reagent VII a substan 20 D-Treated Liquor from Flocculation and Catalyzed Aera tially pure grade of nickel acetate; Reagent VIII an essen tion.' tially pure grade of (NH4)MorO24.4H2O; Reagent X The characteristics of 38-A, 38-B, 38-C, and 38-D are an essentially pure form of silver nitrate; Reagent X a compared in the following table, in which B.O.D. values commercial grade of Zr(SO4)2.4H2O; Reagent XI a com are set forth, as obtained in the standard 5-day test of mercial grade of cobalt sulfate having a cobalt content 25 biochemical oxygen demand employed by sewage techni of about 21 percent by weight; Reagent XII (not a metal cians generally. compound or metal, but included in this example merely for purposes of comparison) a substantially linear poly Biochemical oxygen mer of ethylene imine having an average molecular demand weight of about 40,000; Reagent XIII an ilmenite compo 30 Sample Appearance sition formed by wetting, with four drops of concentrated P. p.m. Percent sulfuric acid (98 percent), 3 grams of Virginia ilmenite removal having a titanium dioxide content of about 53 percent by 38-A------Dark, dirty gray------l,055 ------weight (with the remainder being largely iron oxides and 38-B------Turbid gray------525 50.2 silicates) and an average particle size of about 50-mesh 35 38 C------> --do------440 58.3 (U.S. Standard Screens), permitting the HSO-wetted 38-D----- Sparklingly clear; water-white----. 265 74.9 ilmenite to stand at 70 F. for 4 minutes, and then adding 100 milliliters of water. The practice of our invention, as set forth herein, is As the table above shows, chemically, the catalytic re thus seen to have provided a remarkable increase in the action provides a remarkable increase in the dissolved 40 efficiency of sewage treatment, and especially the aeration oxygen. Visual observation indicated, however, that the process. The final effluent obtained in the treatment of effect of the weighting agent was largely nullified in this the same sewage through a complete secondary biological example by the aeration after flocculation. Flocculated treating plant averaged a B.O.D. removal of 70.2 percent sewage particles were readily observable in samples taken for the same day on which the above experiments were for a five-day B.O.D. determination; that is, aeration after 45 run. It is seen, therefore, that the process of this inven flocculation tended to make at least some of the floccu tion, using our novel flocculating chemical compositions, lated solids to float, and in any commercial practice of followed by properly catalyzed post-aeration of the super this technique (as where substantially insoluble oxida natant, provides a degree of treatment superior to that at tion catalysts were included in the flocculating chemicals), tained from an operating secondary biological sewage it would be desirable to remove the flocculated solids both 50 treatment plant. by skimming off the top and by draining off the sediment, The literature is replete with references relative to aera tion in sewage treatment processes. In the activated while clarified water could be removed at some mid-point sludge processes, the sludge is aerated, and part of it is (vertically) between the floating solids and the settled returned to the primary phase of the treatment process, in solids. Of course, soluble oxidation catalysts could be part as a method of preventing septicity of the sludge. included in the flocculating chemicals, and the aeration 55 Pre-aeration of sewage before primary sedimentation is delayed until after the flocculation and settling steps. practiced in many operating plants. Pre-aeration and pri EXAMPLE 38 mary sedimentation of sanitary sewage generally produces 12 liters of municipal sewage-designated herein as a reduction of B.O.D. in the range of 45 percent. A small "38-A-Raw Sewage'-having a high content of indus 60 packaged sewage plant provides oxidation and digestion in trial packing-house wastes, from a small city in the north one unit with extended aeration of the sewage. However central part of the United States was treated with 4.5 no attempt is made in such plants to remove either dis parts of Reagent “O'” (see Example 37) solids per million solved or suspended solids as such. The Guggenheim parts of sewage, stirred for a few seconds, and then process consists of the aeration of chemically flocculated treated with 4.5 parts of Reagent “R” (see Example 37) 65 sewage followed by sedimentation with the return of the solids per million parts of sewage, followed again by stir sludge to the aeration tank. ring, the whole "Q'-'R' treatment in this experiment To the best of our knowledge, however, the standard being conducted under the same general conditions and in literature of the sewage disposal field makes no reference a manner parallel to the conditions and manner for the to a process wherein a supernatant of a chemically floc “Q'-“R” treatment of Example 37, except that the vessel 70 culated sewage, either with or without the addition of a employed in this case was a conventional 6 gallon poly catalyst, is post-aerated. ethylene waste basket about eighteen inches high. The EXAMPLE 89 treated sewage composition (without any aeration of any In this experiment, seven reagents were employed in a kind up to this point) was then allowed to settle for 40 comparison of the flocculating efficiencies for treating a minutes, and 8500 cc. of supernatant-designated herein 75 municipal sewage containing high concentrations of indus 3,142,638 27 23 trial (packing-house) wastes from a small city in the EXAMPLE 40 north central part of the United States. In each case, 3 In this experiment, the whole sewage volume of a parts of reagent solids per million parts of sewage treated small industrial city in the north central part of the was added to 1000 milliliters of sewage in a 1000 cc. United States was treated with compositions of our in Imhoff cone, said reagent solids having been dispersed at a vention and according to methods of our invention, over 3 percent solids concentration in water thirty minutes a period of almost nine hours. During this period, prior to use. After addition of the reagent slurry, the flow averaged almost 700,000 gallons per hour, and total sewage composition was stirred with a glass rod for a few flow was over 6,000,000 gallons. In this plant, sewage seconds, and then allowed to settle for 15 minutes. is normally given a "primary' sedimentation treatment, In the case of Reagent 39-A, however, the reagent was O followed by "intermediate' treatment in mechanical floc added to the sewage, the sewage composition stirred for a culating basins stirred slowly by moving paddles, and few seconds with a glass rod, and then 3 parts of Reagent finished by treatment on biological filters and final clari 39-B solids per million parts of sewage was added, fol fication basins. Content of B.O.D. (biochemical oxy lowed by stirring. Reagent 39-A was far more efficient gen demand) of the raw sewage influent during this test than any of the other reagents tested (at equal concentra 5 averaged 1375 parts per million. tions), even if used by itself, and not in association with At the primary stage, there was added at a steady rate Reagent 39-B. The efficacy of Reagent 39-A dropped throughout a nine hour working day through a chemical most dramatically and drastically when hematite was feeder, as an aqueous dispersion having a solids content omitted from its formulation. (Reagent “Q' contained 80 of 4 percent, at a rate equivalent to about 25 pounds of mesh hematite.) 20 solids per hour, an intimate mixture of the proportions: Reagent 39-A was identical to Reagent "Q" described 3 parts anhydrous ferric chloride/2 parts Mesabi hematite in Example 37. of a particle size passing 48 mesh but retained on 60 mesh Reagent 39-B was identical to Reagent “R” described (U.S. Standard Screens)/1 part cationic starch of the in Example 37. type employed in Example 2 above. Through a second Reagent 39-C was a mixture of commercial modified 25 chemical feeder located a few feet downstream from the polyacrylamide polymer having a substantial content of first feeder at the primary stage, there was added at a carboxylic groups (Chemical Week, September 17, 1960, steady rate throughout the day, as an aqueous dispersion page 6), pre-dispersed in water over a period of several of 4 percent, at a rate equivalent to about 25 pounds of months at a content of 0.05 percent solids, and magnetite solids per hour, an intimate mixture of the proportions: iron ore from the Mesabi range of Minnesota having an 30 2000 parts Belle Fourche (South Dakota) bentonite/1 average particle size of about 325 mesh (U.S. Standard part sodium salt of a copolymer of styrene and maleic Screens), the polymer:magnetite ratio of the mixture anhydride formed by reaction of equimolar amounts of being 1:2500. styrene and maleic anhydride under conditions generally Reagent 39-D was a mixture of a crude substantially similar to those described in United States Patent 2,333 linear polyglycolamine having an estimated molecular 35 513. weight of about 1,000 and regarded as a by-product from In the conventional mode of operation of this plant, the standard commercial process for making alkanoi expected B.O.D. removal at the intermediate stage aver amines from cylic oxides (such as ethylene oxide) and ages about 22.4 percent; during the chemical treatment ammonia, and Mesabi magnetite having an average par described above B.O.D. removal at the intermediate stage ticle size of about 325 mesh (U.S. Standard Screens), the 40 was found to be 41.4 percent. polyglycolamine:magnetite ratio being 1:5. In the conventional mode of operation of this plant, Reagent 39-E was substantially identical to Reagent expected B.O.D. removal at the final stage averages 63.8 “Q" of Example 37, except that a commercial grade of percent; during the chemical treatment described above, so-called “cationic cellulose' substantially equivalent, for B.O.D. removal at the final stage was found to be 73.4 the purposes of this experiment, to the "diethylaminohy 45 percent. droxypropylcellulose” described by Gilles Montegudet The results obtained in this full field-scale test are (Peintures, pigments, vernis 34, 204-13, 271-9, 311-19 especially noteworthy since the particular sewage used (1958)) was substituted for cationic starch in the formul in this case had a very high content of industrial (pack lation. ing-house) waste, and an average B.O.D. content about Reagent 38-F was a mixture of a commercial grade 50 400 percent greater than the average B.O.D. content of of sodium aiginate, characterized by a molecular weight ordinary sanitary sewages. Again, the results are note such that a 1 percent solids dispersion of said sodium worthy for the extremely low costs involved; at 1959 alginate in water showed a viscosity of 500 centipoises, costs (f.o.b. St. Paul, Minnesota), the total costs of and finely ground commercial barium sulfate (barite) chemicals for this treatment was only about $2.60 per ore, the aiginate:barite ration of the mixture being 1:5 55 million gallons treated, a figure approximately the same (see Ravnestad, U.S. Patent 1,619,036, issued March 1, as the cost of electricity to pump this same sewage 1927).Reagent 38-G was a mixture of substantially linear through the various stages of the complete plant operation. polymerized ethylene imine having a molecular weight From the foregoing, the compositions of matter and of about 40,000, and Mesabi magnetite having an average 60 processes of our invention it will be readily understood. particle size of about 325 mesh (U.S. Standard Screens), Numerous modifications and changes will readily occur the polymer:magnetite ratio of said mixture being 1:5. to those skilled in the art after a consideration of the foregoing specification and accompanying claims. Ex Wolume of amples of such modifications would include, but in no settled Reagent employed solids Comments 65 way be limited to: a method of recirculation of sludge after 15 minutes chemically activated with compositions of our disclosure; (c.c.) a method of removing the floc formed by the use of our compositions on mesh screening or other similar 39-A, 39-B ------31.0 Extremelyrapidly. heavy floc; settled filter media from the aqueous liquor; a method of sep 70 Poofoc; slow settling. arating the flocs formed by our compositions containing Fair floc;0. gradual settling. magnetically active components by the utilization of either Poor floc; slow settling. Fair foc; gradual settling. permanent or electromagnetic devices capable of exert Raw sewage-standard. ing a magnetic field; additionally, the methods of aerat 75 ing, either with or without a catalyst, the aqueous liquor 3,142,638 29 30 treated with the compositions of our disclosure; and water-dispersible synthetic organic cationic polyelectro equipment adapted for utilizing these methods. lytic flocculating material being employed in an amount, It is not desired to limit the invention to the exact from 1 to 300 parts by weight per million parts of sewage, compositions and processes described, but rather we in Sufficient to cause flocculation and accelerated sedimenta tend to include in the scope of our claims such minor tion of solids, and (b) anionic flocculating material, and modifications or substantial equivalents as may occur to in which, after said flocculation and accelerated sedimen one versed in the art and provided with the benefit of tation of solids, there is separated from the sewage com our disclosure. In particular, we do not intend in any position formed, and subjected to aeration in the presence way to limit the breadth of our invention by the specula of oxidation catalyst, an aqueous portion substantially tions above concerning possible mechanisms which might O free of suspended solids. be useful in explaining the remarkable synergistic effects 5. A process for separating solids from sewage, in which actually observed. there are admixed with said sewage hematite iron ore We claim: weighting agent having a particle size smaller than 50 1. A process for separating solids from sewage, in which mesh (U.S. Standard Screens), and water-dispersible syn there are admixed with said sewage iron ore weighting 5 thetic organic cationic polyelectrolytic flocculating ma agent having a specific gravity in excess of 1 and having a terial having a molecular weight in excess of 10,000 and particle size smaller than 50 mesh (U.S. Standard at least one amine group per 10,000 units of molecular Screens), and water-dispersible synthetic organic cationic weight, said water-dispersible synthetic organic cationic polyelectrolytic flocculating material having a molecular polyelectrolytic flocculating material being employed in weight in excess of 10,000 and at least one amine group 20 an amount, from 1 to 300 parts by weight per million per 10,000 units of molecular weight, said water-dispersible parts of sewage, sufficient to cause flocculation and ac synthetic organic cationic polyelectrolytic flocculating ma celerated sedimentation of solids, and in which, after said terial being employed in an amount, from 1 to 300 parts flocculation and accelerated sedimentation of solids, there by weight per million parts of sewage, sufficient to cause is separated from the sewage composition formed an flocculation and accelerated sedimentation of solids, and 25 aqeuous portion substantially free of suspended solids. in which, after said flocculation and accelerated sedimenta 6. A process for separating solids from sewage, in which tion of solids, there is separated from the sewage composi there are admixed with said sewage magnetite iron ore tion formed an aqueous portion substantially free of sus weighting agent having a particle size smaller than 50 pended solids. mesh (U.S. Standard Screens), and water-dispersible syn 2. A process for separating solids from sewage, in which 30 thetic organic cationic polyelectrolytic flocculating ma there are admixed with said sewage separately (a) iron terial having a molecular weight in excess of 10,000 and ore weighting agent having a specific gravity in excess of at least one amine group per 10,000 units of molecular 1 and having a particle size smaller than 50 mesh (U.S. Weight, said water-dispersible synthetic organic cationic Standard Screens) and water-dispersible synthetic organic polyelectrolytic flocculating material being employed in cationic polyelectrolytic flocculating material having a 35 an amount, from 1 to 300 parts by weight per million molecular weight in excess of 10,000 and at least one parts of sewage, sufficient to cause flocculation and ac amine group per 10,000 units of molecular weight, said celerated sedimentation of solids, and in which, after said water-dispersible synthetic organic cationic polyelectro flocculation and accelerated sedimentation of solids, there lytic flocculating material being employed in an amount, is separated from the sewage composition formed an from 1 to 300 parts by weight per million parts of sewage, 40 aqueous portion substantially free of suspended solids. sufficient to cause flocculation and accelerated sedimenta 7. A magnetic process for separating solids from sew tion of solids, and (b) anionic flocculating material, and age, in which there are admixed with said sewage iron ore in which, after said flocculation and accelerated sedi weighting agent having a particle size smaller than 50 mentation of solids, there is separated from the sewage mesh (U.S. Standard Screens), and water-dispersible syn composition formed an aqueous portion substantially free 45 thetic organic cationic polyelectrolytic flocculating ma of suspended solids. terial having a molecular weight in excess of 10,000 and 3. A process for separating solids from sewage, in which at least one amine group per 10,000 units of molecular there are admixed with said sewage iron ore weighting Weight, said water-dispersible synthetic organic cationic agent having a specific gravity in excess of 1 and having polyelectrolytic flocculating material being employed in a particle size smaller than 50 mesh (U.S. Standard 50 an amount, from 1 to 300 parts by weight per million Screens), and water-dispersible synthetic organic cationic parts of sewage, sufficient to cause flocculation and ac polyelectrolytic flocculating material having a molecular celerated separation of solids in an artificially imposed weight in excess of 10,000 and at least one amine group magnetic field, and in which, after said flocculation and per 10,000 units of molecular weight, said water-dispers accelerated separation of solids in said artificially im ible synthetic organic cationic polyelectrolytic flocculating 55 posed magnetic field, there is separated from the sewage material being employed in an amount, from 1 to 300 composition formed an aqueous portion substantially free parts by weight per million parts of sewage, sufficient to of suspended solids. cause flocculation and accelerated sedimentation of solids, and in which, after said flocculation and accelerated sedi References Cited in the file of this patent mentation of solids, there is separated from the sewage 60 composition formed, and subjected to aeration in the UNITED STATES PATENTS presence of oxidation catalyst, an aqueous portion sub 1,619,036 Ravnestad ------Mar. 1, 1927 stantially free of suspended solids. 2,867,584 Scott ------Jan. 6, 1959 4. A process for separating solids from sewage, in which 2.919,898 Marwil et al. ------Jan. 5, 1960 there are admixed with said sewage separately (a) iron 65 2,937,143 Foren ------May 17, 1960 ore weighting agent having a specific gravity in excess of 1 and having a particle size smaller than 50 mesh (U.S. FOREIGN PATENTS Standard Screens), and water-dispersible synthetic organic 860 Great Britain ------of 1877 cationic polyelectrolytic flocculating material having a OTHER REFERENCES molecular weight in excess of 10,000 and at least one 70 Dow: "Separan 2610 in Waste and Sewage Treatment,” amine group per 10,000 units of molecular weight, said October 1956, pages 10-15 relied on.