DRY- DIGESTION TECHNOLOGY USING KITCHEN, AGRICULTURAL AND MARKET WASTE FOR CONTINUOUS BIOGAS GENERATION AND ITS EFFECTIVENESS

Abstract

For securing the clean energy demand along with the safety of the environment, a feasible renewable energy source could be biogas. Dry anaerobic digestion needs less water, lower logistic costs for fertilizers these factors generate interest in using it for treatment of even high-nitrogen substrates for biogas production. The purpose of this work was to study different type of wastes biogas generation by dry anaerobic digestion technology. This study was carried out for ten weeks in batch type digestion by dry anaerobic digestion of kitchen waste (KW), agricultural waste (AW) and market waste (MW) co digestion with cow dung and urine at 33.3 % of total waste. A total 300 kg of waste for each three treatment group was digested for 49 days. Three digester were operated under each treatment group. Total solid percentage in Treatment 1 (KW, Cow dung, urine), Treatment 2 (AW, Cow dung, urine) and Treatment 3 (MW, Cow dung, urine) 17.34±0.39 %, 19.70±0.44 % and 18.52±0.73% respectively. C/N ratio of KW, AW, MW, CD and urine (28.82 ±1.52, 32.72± 0.28, 30.30 ± 1.03, 24.75 ±0.30, 4.36± 4.55 respectively) highest in AW. Significant variation (p<0.05) were observed among T1, T2 and T3, in gas production, highest gas production was recorded at 40-49 days. Because dry digestion process require high retention period. The temperature ranged from 20ºC to 36ºC during ten weeks. The results indicated that biogas production was 1.48±0.28, 1.30 ± 0.06 and 1.29± 0.07 m³ from T1, T2 and T3 respectively at 1 st week. After a batch study, at 7 th week cumulative biogas production was 50.78±0.48 m³ observed in digester containing MW with cattle dung which was significant (p<0.05) as compared to other reactor. Methane content was recorded for all the digester between 60-65%. As digestion period increases the biogas production was also increased because wastes used in this research work contain more lignin, cellulose and silica therefore it takes more time for digestion. A lot of variation in daily biogas production was also recorded due to fluctuating pH, mixing and other environmental condition. The digestate remaining after biogas production need no further treatment for using as fertilizer, pH and total carbon has no significant variable, total nitrogen content (7.18, 6.74, 7.96 mg/g) was significant among T1, T2 and T3. So, it can be concluded that the treatment of (T3) MW with cow dung and urine considered as the best compared to other treatment and it can be suggested as field level application.