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|Title:||ORGANIC MATTER TRANSFORMATIONS INCLUDING TRACE ORGANICS DURING ROTARY DRUM COMPOSTING|
ORGANIC MATTER TRANSFORMATIONS
ROTARY DRUM COMPOSTING
|Abstract:||During the transformation of organic waste in composting process, different groups of carbohydrate such as OH, CH2, CH3 converted into carboxylic (COOH), C=O conjugated, esters (COOC) and C=C groups of aromatic acids. Similarly, in the protein transformation, amide (CONH2) and carboxylate (C=O) groups converted to nitrogenous compounds such as NH3, NO3-. Aliphatic compounds in organic waste get converted to aromatic acids (humic and fulvic acid) by microorganism in a series of steps. The rate kinetics of the transformation of these compounds during composting can be significantly increased by proper mixing, oxygen transfer and enhancing microbial diversity in an enclosed vessel. The degradation time can be reduced to 1/3 to 1/5 compared to conventional techniques_ without causing environmental nuisance such as odor, leachate generation and ground water pollution. The high rate composting technology not only stabilized aggregate organic matter in the• waste material, but also detoxify emerging hazardous organic compounds such as trace hazardous organochlorine pesticides by co-metabolism. Highly available substrate, fast reaction kinetics and microbial diversity during composting can also lead to co-metabolism of trace hazardous organochlorine pesticides. In recent years, spectroscopic techniques such as FT-IR, thermal methods (TG, DTG & DTA) have been used as characterization tools for studying the transformation of organic matter and along with evaluating the maturity of the compost during conventional windrows composting (Chen, 2003; Inbar et al; 1989; Hsu and Lo, 1999). Information on organic matter transformation in high rate composting such as rotary drum composting is rather limited. In addition, considerable studies have been conducted on transformation of trace hazardous organochlorine pesticides in soil, water and a few in conventional windrows composting, however, studies on rotary drum composting is rather limited. 1-Ience, the present work comprises of studies on organic matter transformation including trace hazardous organochlorine pesticides in household batch, full-scale continuous rotary drum and conventional windrow piles using mainly vegetable market waste. Further, the effects of seasonal variations on degradation of trace hazardous organochlorine pesticides were also investigated. v The study is summarized into six chapters with a brief discussion is presented herewith; CHAPTER ONE: Background Information & objectives Provides the background on organic matter (functional groups) transformation including trace hazardous organochlorine pesticides and their degradation. The chapter also includes problem identification, objectives, scope of the work and thesis organization. The study objectives are as follows; 1. Performance evaluation and fate of aggregate organic matter transformation by the application of advanced chemical techniques like FT-IR and thermal methods (TG, DTG & DTA) during full scale continuous rotary drum composting. 2. To study the fate and kinetics of hazardous trace organochlorine-pesticides (Aldrin, Endosulfan a, Endosulfan 13 and Lindane) in household batch and full-scale continuous rotary drum composting and their comparison with conventional windrows composting. 3. To study the effects of seasonal variation on degradation of trace hazardous organochlorine pesticides (Aldrin, Endosulfan a, Endosulfan 13 and Lindane) in full-scale continuous rotary drum composting. CHAPTER TWO: Comprises of experimental methodologies such as composting material characterization, composter configuration, experimental design and analytical methods. CIIAPTER THREE: Part A: Performance evaluation of full-scale continuous rotary drum composter using herbal industry solid waste. • It was found out that composting of herbal waste and cattle manure in 3:1 (w/w) ratio can be successfully conducted in 7-8 days detention period. • Favorable composting conditions were obtained at once a day rotation, during which the inlet zone temperature increased to 70°C leading to higher degradation. Increase in rotation to twice a day couldn't improve the quality. Conversely, it resulted in lowering of thermophilic temperature to 60°C which results in slow degradation, and unstable compost compared to one rotation. • Co-composting of herbal and vegetable wastes gave better quality compost in terms of temperature, moisture, nitrogen, solvita maturity index and aerobic environment due to high moisture content of vegetable waste and bulking agent of herbal waste. vi • FT-IR also revealed that trial-1 (one rotation) to trial-4 (Co-composting herbal & vegetable waste) gave quality compost in terms presence of high intensity peak at the aromatic region and less intense peaks were found in aliphatic region in trial 1 & 4 compared to trial-2 (two rotation) and trial-3 (inocula addition). Part B: Fate of aggregate organic matter transformation (functional groups) and thermal stability during full-scale continuous rotary drum composting. • It was found out that there is increase in molecular complexity of compost by the decrease in aliphatic and polysaccharide components. • New peaks and their intensity in FT-IR bands at 778, 722, and 560 cm-1 are due to aromatic ring, halogen-compounds and some metal-halogen bonds. • A higher degree of maturity was achieved in spring and summer seasons in terms of mass loss (TG), rate of mass loss (DTG), enthalpy change (DTA) compared to winter season. • Correlation between temperature and CO2 emission rate follows Andrews-Kambhu—Haug model compared to the Ratkowsky model because optimum temperature (62. I °C) was obtained due to rapid microbial growth temperature while the later model gave 66.4°C as optimum temperature which is unfavorable for microbial growth. CHAPTER FOUR: Part A: Study on fate and degradation kinetics of organo-chorine pesticides in household batch-scale rotary drum and conventional windrows type composting. • It was found out that about 70% removal of organochlorine pesticides can be achieved within 20-24 days by household batch-scale rotary drum composting. While, in conventional windrows, the removal of pesticides is possible only 50-60% in 30-36 days in which 40=45% removal of pesticides due to leachate generation. • Aldrin after diol formation converted to 1-hydroxychlordene in four days at 55-60 °C, followed by 4, 7-methanoisobenzofuran in eight days at 45-50°C temperature. Finally, it was converted to 4,5,6,7,8,8-hexachloro-1,3,3a,4,7,7a-hexahydro- in twelve days at 35-40°C due to oxidation and reduction reactions. However, in conventional windrows, after aldrin epoxidation to toxic dieldrin it was further converted to aldrindiol. vii • Endosulfan a first changed to endosulfan 13 and subsequently converted to endosulfan sulfate by oxidation process. Librating SO3 gas, it was further converted to endosulfan ether in four days at 55-60°C, followed by chlorendic acid and chlorendic anhydride in eight days at 45-50°C. Finally, it was converted to 4,5,6,7-tetrachloro-3-hydroxy-3H-isobenzofuran-1-one in twelve days at 35-40 °C in household batch-scale rotary drum composter. While in conventional windrows, Endosulfan a converted to endosulfan sulfate followed by Endosulfan ether by removal of SO3 gas. • Lindane gave some oxidative and reductive products, formed in both composting techniques under partially aerobic and anaerobic conditions. • Half life is reduced to 12-20 days from 1095 days, '9-17 days from 160 days, 11-30 days from 60 days and 9-11 days from 270 days in Aldrin, Endosulfan a, Endosulfan 13, and Lindane respectively in household batch-scale rotary drum composting. Similarly, half life is reduced to 15-26 days from 1095 days, 13-25 days from 160 days, 13-59 days from 60 days and 95 days from 270 days in Aldrin, Endosulfan a, Endosulfan (3, and Lindane respectively in conventional windrows composting. Part B- Study on -fate and degradation kinetics of organo-chlorine pesticides in full-scale continuous rotary drum composter • It was found out that removal efficiency of Aldrin, Endosulfan a, Endosulfan 13 and Lindane was calculated as 85.67, 84.95, 83.20 & 81.36% respectively in full-scale continuous rotary drum composting. • First order degradation kinetics of pesticides was observed during full-scale continuous rotary drum composting. Half life of the pesticides, Aldrin, Endosulfan a, Endosulfan 13 and Lindane was reduced to 25.54, 18.43, 18.43, and 27.43 days from 1095 days, 60 days, 270 days and 160 days respectively. • Aldrin converted to Aldrin diol by the hydroxylation reaction in inlet zone. After four days, materials moved to middle zone aldrin diol liberated ethylene molecule to give 1-hydroxychlordene and its isomer. 1 -Hydroxychlordene further oxidized to acidic and aldehydic compounds. Finally, aldehydic compounds of aldrin converted to 4,7-methanoisobenzofuran and 4,5,6,7,8,8-hexachloro-1,3,3a,4,7,7a-hexahydro-by the elimination of H70 during next four days in the outlet zone. viii • Endosulfan isomerized to the endosulfan 13, followed by conversion to endosulfan sulfate, But, it was converted to endosulfan ether in the middle zone of rotary drum composting by liberating SO3 gas in next four days. Finally, materials moved to outlet zone where Endosulfan converted to chlorendic anhydride by hydration and dehydration process. Followed by converted to the 4, 5, 6, 7-tetrachloro-3-hydroxy-3H-isobenzofuran-1-one and 4, 5, 6, 7-tetrachloro-3-hydroxy-3H-isobenzofuran-l-one. • Lindane was converted to 13-Lindane in inlet zone of rotary drum composter, which is most persistent in environment. However, 13-Lindane on dehydrohelogenation and dehalogenation reactions converted to pentachlorocychlohexene (PeCCh) and tetrachlorocychlohexene (TeCCh) respectively. Materials reached to the middle zone where PeCCh converted to pentachlorocychlohexanone, followed by 1,2,3,5-tetrachlorocychlohexanone and 1,2,3 trichlorocychlohexenone due to dehalogenation and dehydrogenation respectively. Finally, in next four days materials moved to outlet zone where TeCCh converted to 1, 3, 5-trichloro-1,4- dihydroxybenzene. 1,2,3-Trichlorocychlohexenone and 1,3 ,5-trichloro- 1,4- dihydroxybenzene. CHAPTER FIVE: Effect of seasonal variations on organochlorine pesticides degradation in full-scale continuous rotary drum composter. • Removal efficiency of Aldrin, Endosulfan a, Endosulfan 13 and Lindane was found out to be 85.67, 84.95, 83.20 and 81.36% respectively during summer season and found higher than the winter and spring seasons i.e. 69.31, 65.03, 69.84 and 71.94% and 64.33, 65.61, 63.28 and 68.23% respectively due to optimum temperature, moisture and pH conditions, which helped in developing microbial activity during depletion of dissolved pesticides in summer season. • In winter season, a part of pesticides (30-35%) removed through leachate generation (1-2L/day). • Higher concentration of pesticides was found in feedstock during winter season composting compared to spring and summer season full-scale rotary drum composting due to lowering ambient temperature (10-15°C), ' leads to less volatilization, less microbial degradation and more accumulations. lx CHAPTER SIX: In toto, a summary of our work done is reported in this chapter. Our observations in contrast of performance of rotary drum, fate of aggregate organic matter transformation during full-scale continuous rotary drum composting, fate and degradation kinetics of organochlorine pesticides during household batch & full-scale continuous rotary drum composting and effects of seasonal variations on degradation of organochlorine pesticides during full-scale continuous rotary drum composting is the best suited technique to check the performance, removal efficiency and fate of trace hazardous pollutants of full-scale composting plants in different seasons and the factors affecting the composting of various kinds of waste.|
|Appears in Collections:||DOCTORAL THESES (chemistry)|
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