State and Biochemical Transformations of Stored Waste Wood. Analysis and Forecast

Chemistry for Sustainable Development 14 (2006) 163169 163 State and Biochemical Transformations of Stored Waste Wood. Analysis and Forecast S. A. MEDVEDEVA1, I. V. VOLCHATOVA1, G. P. ALEKSANDROVA1, I. A. ANTIPOVA1, L. I. ANTONOVA1, O. G. KUZMINA2 and V. A. VEBER2 1Favorsky Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Ul. Favorskogo 1, Irkutsk 664033 (Russia) E-mail: [email protected] 2Sibgiprobum JSC, Ul. Stepana Razina 6, Irkutsk 664033 (Russia) (Received November 10, 2005; revised January 27, 2006) Abstract Physical and chemical composition of the stored waste wood taken from the pits of the Ust-Ilimsk Timber Industrial Complex (TIC) was investigated. The microbiological and sanitary-hygienic status of the waste wood was examined. The experimental data obtained provide evidence that the mass in the pits is friable because of large-size wastes, so oxygen access is provided even to the deep layers in the pit. Aerobic microorganisms (fungi and bacteria) that had occupied the lowest old layers have already created a united community that carries out biochemical destruction of waste wood forming ecologically dangerous lignin- like substances, neutral compounds, phenols and acids. Intense microbiological activity can lead to spontaneous ignition of waste wood, which belongs to the class of fire dangerous substances. INTRODUCTION facilities. The annual yield of this waste prod- uct at the Baikal Pulp and Paper Mill (BPPM) Utilization of wastes comprises one of the alone is about 10 thousand tons. Lignin tailings substantial aspects of the programme of envi- remain almost unused; it is stored in accumu- ronmental protection from anthropogenic im- lating charts. pact. This problem is extremely urgent for the One of the most widespread industrial wood Irkutsk Region because this territory is an in- wastes is hydrolysis lignin (HL); its annual dustrially developed area. The resource poten- amount at the two hydrolysis plants of the tial of the Irkutsk Region provides the lead- Irkutsk Region (Tulun, Biryusa) accounts for ing role of five special complexes, including about 70 thousand tons [1]. Hydrolysis lignin is lumber industry, in the structure of regional transported to dumps almost completely and industry. thus occupies large ground areas acidifying soil According to the data of State Statistics [1], (pHHL ~ 2.5), surface and underground water. more than 60 lumbering and wood processing This brings about the danger of large-scale pol- plants are situated in the Irkutsk Region. These lution of the territories adjacent to the plants. plants are the sources of a substantial amount Fine HL fractions are easily swept away by wind (about 300 thousand m3) of dense waste wood polluting the air. In the recent years, auto-oxi- (bark, sawdust, wood chips). The amount of dation of a large mass of HL has become the their utilization is 79.9 %, the rest mass is trans- reason of systematic fires in the Zima district. ported to proving grounds and dumps. Lignin The dumps of hydrolysis plants contain more tailings are also formed in the pulp and paper than 2 mln tons of HL. 164 S. A. MEDVEDEVA et al. Under the natural conditions, the aerobic EXPERIMENTAL microbiological decomposition of plant residues (wood, forest litter) occurs very slowly. The The objects of investigation were pits (dumps decomposition process takes place as a result of waste wood) of the Ust-Ilimsk Timber of complicated multistep activities of a complex Industrial Complex (TIC). Burying of wood of microorganisms with a characteristic change wastes in the pit No. 83 was carried out since in physiological groups. The main factors 1986; the wastes are stored over the area of determining the microflora population and 29 ha. The depth of the repository is 31 m. Filling predominance of one group of microorganisms of the pit No. 8 was carried out since 1983, the or another and therefore the intensity and storage area is 1.6 ha, dump depth is 56 m. direction of biological destruction include the Samples were taken from the central part chemical composition of structural components of pits at different horizons with intervals (by of wood residues, the degree of their humidity, the core) each 2 m at a depth of 30 m for the temperature and aeration. So, depending on the case of pit No. 83 (samples 19) and 7 m for conditions, the rate of wood material pit No. 8 (samples 1012). The samples were decomposition may vary. Small fallen or felled transported in polyethylene bags.* trees or branches turn into dust within 1015 The fractional and granulometric years. Smaller sized raw material, such as leaf composition of the samples was determined. litter, dry grass, would decompose much more After removing mechanical impurities (stones, rapidly under the same conditions [2]. glass, etc.), humidity and pH of the medium The waste products of wood-processing and were measured. Then the samples were dried wood-chemical plants accumulated in dumps will to the air-dry state and ground in a mill. After transform with time, similarly to other accu- thorough mixing, samples were taken by mulated wastes of organic origin; they will quartering; subsequent analyses (elemental undergo microbiological degradation, as micro- analysis, group composition) were made with flora inhabits them. In the case of HL, popula- the resulting averaged samples. The humidity tion with microflora becomes possible only af- of air-dry samples was taken into account in ter sulphuric acid that impregnates the sub- calculations. The content of cellulose and lignin stance is removed with atmospheric precipita- was calculated for the organic part of samples. tion (rain, snow). That is why lignin dumps stay For biological analyses, the initial samples for more than 50 years. without preliminary treatment were used. The Extractives and the products of biodestruc- samples were kept before analyses at a tem- tion of the lignin from wood or bark are phe- perature of 0 oC. Quantitative determinations nolic compounds and can exhibit toxic and car- of the microorganisms were carried out using cinogenic properties when their concentrations a two-layer agar method according to GF XI are high. Their arrival into underground water (issue 2). To estimate the toxicity, we studied in large amounts may be dangerous from the the germinating capacity of wheat seeds in the viewpoint of ecology. In addition, while time presence of samples to be analysed, in com- goes on, the dump mass may be populated with parison with the reference [3]. potentially dangerous microorganisms (patho- gens and toxicogens) that are able to cause en- teric infection in humans, epidemic in fauna, RESULTS AND DISCUSSION toxicosis in plants. Because of this, it is neces- Analysis of the physical and chemical sary to monitor not only biochemical but also composition of the samples of stored waste sanitary-hygienic status of dumps, pits, and wood in the pits of the Ust-Ilimsk TIC accumulation charts. The goal of the present work was to analyse It was established that the physical compo- chemical and microbiological processes that take sition of the samples under investigation in both part in the stored waste wood, and prediction of the sanitary-hygienic state and temporal *Sampling was carried out by the Geological and changes in these repositories. Geodesy Centre (Bratsk city). STATE AND BIOCHEMICAL TRANSFORMATIONS OF STORED WASTE WOOD. ANALYSIS AND FORECAST 165 TABLE 1 Granulometric composition of samples from the pits of Ust-Ilimsk TIC Sample Depth, m Sample description Content of a fraction, mass % No. Coarse, Medium, Fine, >6.5 cm >3.0 cm <3.0 cm Pit No. 83 1 1 2 Dust; chi ps and bark are not numerous 28.1 18.4 53.5 2 35 Clay lumps, ground, bark pieces; a small amount of chips and dust 67.2 14.1 18.8 3 68 Dust, chips, bark; ground 51.4 18.8 29.8 4 1012 Dust, chips and bark; ground; crushed stone 52.2 17.2 30.7 5 1416 Dust, bark; small amount of chips; ground 49.3 19.4 31.3 6 1820 Dust, bark; small amount of chi ps; crushed stone 40.3 21.2 38.5 7 2224 Dust, chips, bark; ground 56.6 18.9 24.5 8 2628 Dust, chips; crushed stone 37.8 21.7 40.5 9 3031 Dust, chips, bark, crushed stone 55.1 19.7 25.2 Pit No. 8 10 12 Dust 10.0 14.6 75.4 11 46 Dust, chips; stones 38.2 17.9 44.0 12 67 Ground with glass; small amount of dust and chips 48.9 23.2 27.9 pits is not uniform, because it is determined by entered the bottom of the pit. No dependence the quality of waste material and includes of such a type was observed for pit No. 8. chips, bark and dust. Since the wastes to be The samples were mainly weakly alkaline stored were interspersed with ground, a large (pH 7.68.0) (see Table 2). Only some samples number of mechanical impurities were with high bark content were acidic (pH 4.6 present in the samples: sand, ground, clay, 4.8) or neutral (pH 6.37.2). The acidic medium stones, glass, and crushed stone. These for- is characteristic of wood in general and espe- eign bodies were especially noticeable in the cially of bark (pH 4.55.5), so high pH values samples from pit No. 8. (8.08.6) are due to the arrival of alkaline-con- Granulometric composition showed (Table 1) taining materials crushed stone or lime that the coarse fraction with particle size above into the wastes. An optimal pH level is indi- 6.5 cm dominates in the samples; the major part vidual for each microbe culture; however, many of this fraction is represented by the particles bacteria are relatively insensitive to pH varia- with a size of 6.58.5 cm.

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