DOCSLIB.ORG

Controlled-Released Fertilizers Using Zeolites

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Controlled-Released Fertilizers Using Zeolites U.S. Department of the lnterior U.S. Geological Survey Controlled-Release Fertilizers Using Zeolites Introduction Controlled-release nitrogen The smaller the size the quicker the fertilizer release. The relationship is shown by The ultimate fertilizer should be the following equation: wt. percent inexpensive and long lasting, should Urea is one of the most common N = 20 + 40 (log mean particle size in tend to increase soil fertility through nitrogen fertilizers. It is very soluble mm). repeated use, and should release in water, and can be leached through nutrients to plants as they are needed, the root zone. In addition, urea is Controlled-release phosphorous thereby eliminating pollution and converted into ammonium ions by an fertilizers inefficiencies. Whether or not such enzyme found in most soils. Soil systems will be realized will depend bacteria then convert these ammonium Phosphate (H2PO4-) can be released to on agricultural research into ions into readily leachable nitrate ions. plants from phosphate rock (P-rock) technologies that are fine-tuned to Using zeolitic rocks in fertilizer can composed largely of the calcium ecologically sustainable methods. help prevent these nutrient losses. phosphate mineral apatite by mixing U.S. Geological Survey (USGS) the rock with zeolite having an preliminary experiments indicate that A controlled-release nitrogen (N) exchange ion such as ammonium. The the use of zeolites in agriculture is a fertilizer can be produced by heating approximate reaction in soil solution 0 promising avenue for such research. zeolite rock chips to about 400 C to is as follows: (P-rock) + (NH4-zeolite) drive out all zeolitic and pore water, = (Ca-zeolite) + (NH4+) +(H2PO4-). Background which is replaced with molten urea. The urea crystallizes at about 1320C. The zeolite takes up Ca2+ from the The use of soluble fertilizers can lead The rate of nitrogen release from the phosphate rock, thereby releasing both to water pollution and to wasted zeolitic rock is slowed in three ways: phosphate and ammonium ions. nutrients. Nitrogen, for example, can (1) by containing urea in the rock Unlike the leaching of very soluble leach into ground and surface waters, pores and zeolite crystals, thus phosphate fertilizers (for example, especially in sandy soils, and preventing the leaching of urea from superphosphate), the controlled- phosphate may become fixed and the root zone; (2) by slowing the release phosphate is released as a unavailable to plants, especially in conversion of urea by soil enzymes, result of a specific chemical reaction tropical soils. Zeolites, porous thus delaying the formation of in the soil. As phosphate is taken up minerals with high cation-exchange ammonium ions; and (3) by taking up by plants or by soil fixation, the capacity, can help control the release ammonium ions onto exchange sites chemical reaction releases more of plant nutrients in agricultural in the zeolite, thus protecting them phosphate and ammonium in the systems. Zeolites also can free soluble from nitrifying bacteria. Potassium- attempt to reestablish equilibrium. nutrients already in soil for use by saturated zeolite prepared by the The rate of phosphate release is plants, and may improve soil fertility above method contained approx- controlled by varying the ratio of and water retention. Because zeolites imately 17 wt. percent elemental N. P-rock to zeolite. Phosphorus is also are common, they could be useful on The rate of N release can be controlled released from the rock by the lowering a large scale in agriculture. USGS by changing the size of the rock chips. of soil pH as ammonium ions are research uses zeolites in several ways converted to nitrate. to control the release of nutrients in soil. Controlled-release fertilizers were and K-, Ca-, and NH4-poor zeolites Information tested in greenhouse pot experiments can scavenge these ions from soil with sorghum-sudangrass using NH4- solutions and thereby limit plant For further information, contact: saturated zeolite (clinoptilolite) and P- growth when used in soils that am rock with a phosphate application rate deficient in these nutrients. These Dennis D. Eberl of 340 mg P per kg soil, and zeolite/P- negative results emphasize the need U.S. Geological Survey rock ratios ranging from 0 to 6. Total to use appropriate zeolites during 3215 Marine Street phosphate uptake and phosphate agricultural experimentation. Boulder, Colorado 80303 concentration measured for the grass 303-54 l-3028; Fax 303-447-2505 were related linearly to the zeolite/P- Selected references E-mail: [email protected] rock ratio, and yields summed over four cuttings were as much as four Barbarick, K.A., Eberl, D.D., and Lai, times larger than control experiments. T.M., 1988, Response of sorghum- sudangrass in soils amended with Release of trace nutrients phosphate rock and NH4exchanged zeolite (clinoptilolite): Technical Experiments indicate that zeolite in Bulletin TB88-1, Department of soil can aid in the release of some Agronomy, Colorado State University, trace nutrients and in their uptake by 62 p. plants. The release of phosphorus, potassium (K), manganese (Mn), zinc -1991, Pine Ridge zeolite and (Zn), iron (Fe), and copper (Cu) was Fort Hall mill shale P effects on enhanced by the presence of zeolite in sorghum-sudangrass: Technical a neutral soil. The concentration of Cu Bulletin TB9l-2, Department of and Mn in sudangrass (in mg/kg) was Agronomy, Colorado State University, significantly related to the zeolite/P- 47 p. rock (x) in experimental systems that used two different NH4 saturated Barbarick, K.A., Lai,T.M., and clinoptilolites, two different soils, and Eberl, D.D., 1990, Exchange fertilizer two different forms of P-rock. For (phosphate rock plus ammonium- example, the relation for one system zeolite) effects on sorghum- was: Cu = 2.78 + 0.83x -0.06x2 (R2 = sudangrass: Soil Science Society of 0.94), and Mn = 40.03 + 18.49x + America Journal, v. 54, p. 911-916. 0 . 76x2 (R2 = 0.99). The mechanism for this effect may be similar to that Lai, T.M. and Eberl, D.D., 1986, discussed above: sparingly soluble Controlled and renewable release of minerals are dissolved as an effect of phosphorus in soils from mixtures of preferential exchange on the zeolite. phosphate rock and NH4exchanged Trace nutrients on the zeolite clinoptilolite: Zeolites, v. 6, p. 129- exchange sites are then freed for 132. uptake by plants. Pond, W.G. and Murnpton, EA., Potential harmful effects eds. 1984, Zeo-Agriculture: Use of natural zeolites in Agriculture and Zeolites can be harmful as well as Aquaculture: Westview Press, Boulder, helpful to plant growth. For example, Colorado, 296 p. zeolites with sodium as the chief exchange ion can be toxic to plants, November 1993.
Load more

Recommended publications
  • O Lunar and Planetary Institute Provided by the NASA Astrophysics Data System WHITLOCKITE SATURATION
    WHITLOCKITE SATURATION IN LUNAR BASALTS, J.E. Dickinson and P.C. Hess, Dept. of Geological Sciences, Brown University, Providence, RI 02912 As part of a continuing program initiated to evaluate the evolution of late-stage lunar magmas and the possible effects of crystallization of minor phases on their geochemistry, we have determined the saturation surface for whitlockite, Ca (PO ), in a liquid composition produced by crystallization of KREEP basalt 15386 lf~able1). Whitlockite is by far the most abundant phos- phate mineral in lunar rocks and in all probability is more abundant than other minor phases such as zircon, zirccnolite, monazite, and tranquillityite (1). Whitlockite is also an important component of mesosiderites, reported average modal phosphate abundances in mesosiderites ranging from 0.0-3.7% (avg. 1.9%) (2). Even higher phosphate abundances (up to 9.4%) have been observed in basaltic lithic clasts of presumed impact melt origin found in mesosiderites (3). Analyses of lunar whitlockites commonly show Ce203and Y203 contents up to 3 wt% and REE contents that may be as high as 1-2 wt% for La203and Nd203 de- creasing to levels of -0.1-0.2 wt% for the HREE (1). It has been shown that whitlockite is generally more enriched in REE's relative to chondrites than other minor phases in the same rock (4). Uranium and thorium may also be present in significant amounts although other minerals may contain more. Whit- lockite may, therefore, be an important reservoir of rare earth and heat producing elements. In addition, the amount of FeO and MgO in whitlockite is variable (Table 1).
    [Show full text]
  • Validation of Zeolites to Maximize Ammonium and Phosphate Removal from Anaerobic Digestate by Combination of Zeolites in Ca and Na Forms Page 1
    Validation of zeolites to maximize ammonium and phosphate removal from anaerobic digestate by combination of zeolites in Ca and Na forms Page 1 Abstract Ammonium and phosphate are fundamental nutrients for human life, but their excess in water can lead to eutrophication, an uncontrolled growth of biomass with a consequent deficit of oxygen (hypoxia) that can be really dangerous for water life. This excess is principally due to human activities such as industry and agriculture (detergents, fertilizers) and the problem is expected to grow during next years. Then, it is necessary to find an efficient, simple and low cost technology able to remove the nutrients from water in order to avoid environmental damages. Moreover, the population growth, the constant improvement in agriculture and the consequent increase in fertilizers demand have made the recovery of nutrient from water a real need, as it has been estimated that a 20% of the total needs of Europe could be recovered from wastewaters. Although both ammonium and phosphate have to be recovered from wastewater, their simultaneous removal by means of one adsorbent material has rarely been reported hitherto. The merit of using one material for the simultaneous removal is obvious, even if it has not been achieved yet. In general, most of the solutions proposed for the simultaneous removal of ammonium and phosphate are based on the use of two types of reagents. A large list of removal technologies, ranging from biological to physic-chemical methods, have been widely studied: in this work, zeolites in Ca and Na forms were evaluated as sorbents for phosphate and ammonium from synthetic water and real anaerobic digestate.
    [Show full text]
  • Monazite, Rhabdophane, Xenotime & Churchite
    Monazite, rhabdophane, xenotime & churchite: Vibrational spectroscopy of gadolinium phosphate polymorphs Nicolas Clavier, Adel Mesbah, Stephanie Szenknect, N. Dacheux To cite this version: Nicolas Clavier, Adel Mesbah, Stephanie Szenknect, N. Dacheux. Monazite, rhabdophane, xenotime & churchite: Vibrational spectroscopy of gadolinium phosphate polymorphs. Spec- trochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Elsevier, 2018, 205, pp.85-94. 10.1016/j.saa.2018.07.016. hal-02045615 HAL Id: hal-02045615 https://hal.archives-ouvertes.fr/hal-02045615 Submitted on 26 Feb 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Monazite, rhabdophane, xenotime & churchite : vibrational spectroscopy of gadolinium phosphate polymorphs N. Clavier 1,*, A. Mesbah 1, S. Szenknect 1, N. Dacheux 1 1 ICSM, CEA, CNRS, ENSCM, Univ Montpellier, Site de Marcoule, BP 17171, 30207 Bagnols/Cèze cedex, France * Corresponding author: Dr. Nicolas CLAVIER ICSM, CEA, CNRS, ENSCM, Univ Montpellier Site de Marcoule BP 17171 30207 Bagnols sur Cèze France Phone : + 33 4 66 33 92 08 Fax : + 33 4 66 79 76 11 [email protected] - 1 - Abstract : Rare-earth phosphates with the general formula REEPO4·nH2O belong to four distinct structural types: monazite, rhabdophane, churchite, and xenotime.
    [Show full text]
  • An Overview of Phosphate Mining and Reclamation in Florida
    An Overview of Phosphate Mining and Reclamation in Florida Casey Beavers Graduate Committee: Dr. Rex Ellis, Chairman Dr. Edward Hanlon Dr. Greg MacDonald April 2013 Introduction Phosphate has significant economic importance in Florida, yet 70% of surveyed Florida residents claimed that they were uninformed about the industry (Breeze, 2002). Residents who are aware of phosphate mining and fertilizer manufacturing in Florida tend to have strong opinions either in favor or in opposition to its presence. This document is meant to provide an overview of phosphate mining and reclamation in Florida to address the following questions: Why do we care about phosphate? Why is phosphate mined in Florida? How is phosphate mined? Who is impacted by Florida phosphate mining? What happens to the land after mining? What are some of the controversies of phosphate mining? The following topics will be discussed: phosphate as a resource, the geology of the Florida phosphate deposits, the economics of phosphate mining and fertilizer production, the history of mining in Florida, the regulations involved in mining, the process of phosphate mining, the reclamation or restoration of the mined areas, and lastly--the controversies surrounding phosphate mining in Florida. Phosphate Plants and animals are unable to live without phosphorus. It is an essential component in ATP, an energy-bearing compound that drives biochemical processes. Phosphorus also comprises much of the molecular composition of DNA, RNA, and phospholipids that are necessary to the function of cellular membranes. Nitrogen, another essential element, may be fixed from the atmosphere, meaning its supply is limitless. Phosphorus, present as phosphate minerals in the soil, is a non-renewable resource.
    [Show full text]
  • Turquoise and Variscite by Dean Sakabe MEETING Wednesday
    JANUARY 2015 - VOLUME 50, ISSUE 1 Meeting Times Turquoise and Variscite By Dean Sakabe MEETING We are starting the year off with Tur- Wednesday quoise and Variscite. January 28, 2015 Turquoise is a copper aluminum phosphate, whose name originated in 6:15-8:00 pm medieval Europe. What happened was Makiki District Park that traders from Turkey introduced the blue-green gemstone obtained Admin Building from Persia (the present day Iran) to Turquoise (Stabilized), Europeans. Who in turn associated Chihuahua, Mexico NEXT MONTH this stone with the Turkish traders, Tucson Gem & rather than the land of the stones origin. Hence they called this stone Mineral Show “Turceis” or, later in French “turquois.” Over time english speakers adopted this French word, but adding an “e” (Turquiose). The Spanish called this stone “Turquesa”. LAPIDARY The gemstone grade of Turquoise has a hardness of around 6, however Every Thursday the vast majority of turquoise falls in the softer 3–5 range. With the 6:30-8:30pm exception being the Turquoise from Cripple Creek, Colorado which is in the 7-8 range. Turquoise occurs in range of hues from sky blue to grey Makiki District Park -green. It is also found in arid places that has a high concentration of 2nd floor Arts and copper in the soil. The blue color is created by copper and the green Crafts Bldg by bivalent iron, with a little amount of chrome. Turquoise often, has veins or blotches running MEMBERSHIP through it, most often brown, but can be light gray or black DUE COSTS 2015 depending on where it was Single: $10.00 found.
    [Show full text]
  • 12018 Olivine Basalt 787 Grams
    12018 Olivine Basalt 787 grams Figure 1: Original “mug shot” for 12018 PET showing main pieces and smaller pieces. NASA #S69-64111. Note the apparent encrustation. Introduction Mineralogy 12018 is an olivine basalt with an apparent Olivine: Kushiro et al. (1971) reported Fo -Fo for accumulation of mafic minerals. Figures 1 and 14 show 73 43 olivine phenocrysts. Walter et al. (1971) found that an apparent “encrustation” on the surface of 12018. olivine in 12018 had lower trace element contents (figure 5) than for other rocks. Petrography Walter et al. (1971) report that 12018 is comprised of Pyroxene: Walter et al. (1971), Brown et al. (1971) about 70% larger olivine and pyroxene crystals set in and Kushiro et al. (1971) determined that the pyroxene 20% variolitic matrix (figure 2). French et al. (1972) composition in 12018 did not trend towards Fe- describe the sample “as medium-grained with an enrichment (figure 4). average grain size of about 0.4 to 1.0 mm”. They found that 12018 was “virtually undeformed and no shock- Plagioclase: Plagioclase is An90-94 (Walter et al. 1971). metamorphic effects were observed.” The plagioclase in 12018 has the least trace element content (figure 6). 12018 also contains an association of fayalite-K-rich glass-phosphate that is interpreted as residual melt (El Goresy et al. 1971). Lunar Sample Compendium C Meyer 2011 Figure 3: Photomicrographsof 12018,9 showing highly mafic proportions. NASA S70-49554 and 555. Scale is 2.2 mm Figure 2: Photo of thin section of 12018 showing large cluster of mafic minerals. NASA # S70-30249.
    [Show full text]
  • The Importance of Minerals in Coal As the Hosts of Chemical Elements: a Review
    The importance of minerals in coal as the hosts of chemical elements: A review Robert B. Finkelmana,b, Shifeng Daia,c,*, David Frenchd a State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, China b University of Texas at Dallas, Richardson, TX 75080, USA c College of Geoscience and Survey Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China d PANGEA Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia *, Corresponding author: [email protected]; [email protected] Abstract Coal is a complex geologic material composed mainly of organic matter and mineral matter, the latter including minerals, poorly crystalline mineraloids, and elements associated with non- mineral inorganics. Among mineral matter, minerals play the most significant role in affecting the utilization of coal, although, in low rank coals, the non-mineral elements may also be significant. Minerals in coal are often regarded as a nuisance being responsible for most of the problems arising during coal utilization, but the minerals are also seen as a potentially valuable source of critical metals and may also, in some cases, have a beneficial effect in coal gasification and liquefaction. With a few exceptions, minerals are the major hosts of the vast majority of elements present in coal. In this review paper, we list more than 200 minerals that have been identified in coal and its low temperature ash, although the validity of some of these minerals has not been confirmed. Base on chemical compositions, minerals found in coal can be classified into silicate, sulfide and selenide, phosphate, carbonate, sulfate, oxide and hydroxide, and others.
    [Show full text]
  • The Phosphate Mineral Association of the Granitic Pegmatites of the Fregeneda Area (Salamanca, Spain)
    The phosphate mineral association of the granitic pegmatites of the Fregeneda area (Salamanca, Spain) E. RODA Dept. de Mineralogfa y Petrologfa, Univ. del Pals Vasco/EHU, Apdo. 644, 48080 Bilbao, Spain F. FONTAN Univ. Paul Sabatier, URA 067, Toulouse, France A. PESQUERA AND F. VELASCO Dept. de Mineralogfa y Petrologfa, Univ. del Pals Vasco/EHU, Apdo. 644, 48080 Bilbao, Spain Abstract In the Fregeneda area different pegmatitic types can be distinguished on the basis of their mineralogy, internal structure and field relationships. The most common type corresponds with simple pegmatites with a homogeneous internal structure, but Li and Sn-bearing pegmatites are also relatively widespread, besides a minority group of Fe-Mn phosphate-bearing pegmatites that has recently been characterized. These pegmatites are located in an intermediate zone, between the barren pegmatites and the most evolved Li and Sn-bearing bodies, and they carry a complex association of phosphate minerals. The study of these phosphates has allowed the identification of the primary phases as wyllieite, graflonite, sarcopside, triplite-zwieselite and ferrisicklerite; the secondary phosphates are rosemaryite, heterosite-purpurite, alluaudite and v/iyrynenite. In this study, the main characteristics of these phosphate minerals are reported, including their chemical composition, analysed by electron microprobe, and their unit-cell parameters, calculated using X-ray powder diffraction techniques. A common transformation mechanism in this phosphate association is the oxidation of the transition metal cations at the same time as Na-leaching in wyllieite to generate rosemaryite, and Li-leaching in ferrisicklerite to generate heterosite. The occurrence of sarcopside lamellae in ferrisicklerite and heterosite is evidence of the replacement processes of the former by the latter.
    [Show full text]
  • The Occurrence of Li-Fe-Mn Phosphate Minerals in Granitic Pegmatites of Namibia
    Communs geol. Surv. Namibia, 7 (1991) 21-35 The occurrence of Li-Fe-Mn phosphate minerals in granitic pegmatites of Namibia Paul Keller Institut für Mineralogie und Kristallchemie der Universität, Pfaffenwaldring 55, D- W7000 Stuttgart 80, Germany This is the first comprehensive account of Li-Fe-Mn phosphates (triphylite-lithiophilite and the topotactic alteration products ferrisick- lerite-sicklerite and heterosite-purpurite) from 46 granitic pegmatites of the Damara Sequence (Namibia). The Li-Fe-Mn phosphates display a wide range of Fe/(Fe+Mn) ratios. Preliminary ratios 0.125 ≤ Fe/(Fe+Mn) ≤ 0.845 have been determined by wet chemical and microprobe analyses. Relationships appear to be developed between the Fe/(Fe+Mn) ratios and the observed economic minerals, e.g. beryl, Ta-Nb oxides, petalite, and gem tourmaline. There is evidence for regional distribution patterns of Fe/(Fe+Mn) ratios regarding 8 portions and swarms of 4 pegmatite belts. There is fairly good accordance between the degree of fractionation, and differentiation, and the Fe/(Fe+Mn) ratio (hypothesis of Ginsburg) for a great number of pegmatites, although conspicuous deviations from that hypothesis were also noted. From the occurrence of arborescent Li-Fe-Mn phosphates, seen in 22 pegmatites, important arguments could be found for both the mode of the pegmatite evolution and for their economic mineralisation. Recent field observations prove that thermal under- cooling is predominantly responsible for the arborescent shape of Li-Fe-Mn phosphates in most of the Damaran pegmatites. Introduction erals (Keller, 1974, 1980, 1985, 1987, 1988; Keller & von Knorring, 1985, 1989; Fransolet, Keller & Fontan, The Precambrian Damara Sequence of Namibia is 1986).
    [Show full text]
  • Carbonate, Sulfate and Phosphate Minerals Groups
    University of Anbar Collage of Science Department of Geology Minerals / 1st stage. Carbonate, Sulfate and Phosphate Minerals Groups Assistant lecturer Nazar Zaidan Khalaf Carbonate, Sulfate and phosphate minerals groups Lecture seven Carbonate mineral group 2- • The carbonate minerals contain the anionic complex CO3 , ,which is triangular in its coordination—i.e., with a carbon atom at the center and an oxygen atom at each of the corners of an equilateral triangle. These anionic groups are strongly bonded individual units and do not share oxygen atoms with one another. The triangular carbonate groups are the basic building units of all carbonate minerals and are largely responsible for the properties particular to the class. • The common anhydrous (water-free) carbonates are divided into three groups that differ in structure type: calcite, aragonite, and dolomite. • The copper carbonates azurite and malachite are the only notable hydrous varieties. • This anion group usually occurs in combination with calcium, sodium, uranium, iron, aluminum, manganese, barium, zinc, copper, lead, or the rare-earth elements. The carbonates tend to be soft, soluble in hydrochloric acid, and have a marked anisotropy in many physical properties (e.g., high birefringence) as a result of the planar structure of the carbonate ion. • There are approximately 80 known carbonate minerals, but most of them are rare. The commonest varieties, calcite, dolomite, and aragonite, are prominent constituents of certain rocks: calcite is the principal mineral of limestone's and marbles; dolomite occurs as a replacement for calcite in limestone's, and when this is extensive the rock is termed dolomite; and aragonite occurs in some recent sediments and in the shells of organisms that have calcareous skeletons.
    [Show full text]
  • Joint Meeting
    Joint Meeting 19. Jahrestagung der Deutschen Gesellschaft für Kristallographie 89. Jahrestagung der Deutschen Mineralogischen Gesellschaft Jahrestagung der Österreichischen Mineralogischen Gesellschaft (MinPet 2011) 20.-24. September 2011 Salzburg Referate Oldenbourg Verlag – München Inhaltsverzeichnis Plenarvorträge ............................................................................................................................................................ 1 Goldschmidt Lecture .................................................................................................................................................. 3 Vorträge MS 1: Crystallography at High Pressure/Temperature ................................................................................................. 4 MS 2: Functional Materials I ........................................................................................................................................ 7 MS 3: Metamorphic and Magmatic Processes I ......................................................................................................... 11 MS 4: Computational Crystallography ....................................................................................................................... 14 MS 5: Synchrotron- and Neutron Diffraction ............................................................................................................. 17 MS 6: Functional Materials II and Ionic Conductors ................................................................................................
    [Show full text]
  • Vivianite Impacts on Solids Processes
    FACT SHEET Vivianite Impacts on Solids Processes By: Bipin Pathak Introduction Causes of Formation Vivianite is named in honor of John Henry Vivian In chemical phosphorus removal, (1785 - 1855), an English mineralogist and mine orthophosphate (PO4 3-) binds to iron or owner who first discovered this mineral in aluminum and precipitates out of solution. Iron Cornwall. Pure, fresh vivianite is colorless but salts are a common choice over other metal salts oxidizes very easily and changes color from deep because of additional benefits in controlling odor blue to black. It is an iron-phosphate mineral and hydrogen sulfide production during (Fe3[PO4]2.8H2O), formed in an anaerobic system anaerobic digestion. Parameters including redox in the presence of dissolved ferrous ions and conditions, pH, alkalinity, presence of organic phosphorous (P) with relatively low sulfide substances, and particle morphology influence concentrations. It is different from struvite the binding and release of phosphorus. The (magnesium ammonia phosphate precipitate) in solubility of ferrous and ferric ions varies with pH terms of chemical composition and and oxidation reduction potential (Figure 2a). appearance. Struvite deposits generally appear The reduction of ferric into ferrous iron in as white or off-white crystallizations. anaerobic environments leads to P release from Fe-P minerals. In precipitation reactions, ferrous Vivianite is a hard scale build-up that can form iron exhibits preference for some chemicals over on flow meters, valves, pumps, heat exchangers, other chemicals (Figure 2b). This can create dewatering equipment and other areas conditions that favor formation of vivianite by downstream of the anaerobic digestion process binding the reduced Fe with P released in the (Figure 1).
    [Show full text]