Studies on efficacy of different additives in enhancing biogas production in low temperature regime
Loading...
Date
2005-07
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The energy generation system in rural sector of India largely depend upon local renewable biomass sources such as animal wastes, crop residues, fire wood etc. The overall rate of waste utilization and methane production mainly depends on the certain process parameters like temperature, pH, carbon-nitrogen ratio, total alkalinity, ammonia-nitrogen concentration, total solids, and volatile solids. Biogas production is satisfactory in tropical regions since ambient temperature always remains in mesophilic range. In low temperature regime where the process temperature never reaches the optimum requirement for maximum yield of biogas production, the biogas production can be enhanced by using certain additives like urea, cattle urine, ferric chloride and biogas spent slurry. To assess the efficacy of these additives, an experiment was conducted in actual field conditions on 0.5 m3 capacity insulated and uninsulated Pant Tarai biogas plants. The level of selected additives daily added with inlet slurry was 10 g urea d-1 m-3 digester volume, 440 ml urine d-1 m-3 digester volume, 0.5 g ferric chloride d-1 m-3 digester volume and biogas spent slurry at the rate of 10 percent of inlet slurry.
The results reveal that in low temperature range of 5.7-18.80C, the cumulative biogas production was highest (61.3 %) where combination of urea and biogas spent slurry was added in substrate. In the temperature range of 9.7-21.60C, the cumulative biogas production was 48.6 % higher on substrate having urea as additive in cattle manure compared with untreated substrate. The total solids reduction during the entire course of experiment was found highest in the substrate where combination of urea and biogas spent slurry was used as additive. The volatile solids reduction in the same temperature range was higher when urea, cattle urine and combination of urea and biogas spent slurry were added in cattle manure. During the entire course of experiment the Total Kjeldhal Nitrogen content was highest in the substrate containing combination of urea and biogas spent slurry. In the ambient temperature range of 5.7-33.40 C, the phosphorous and potassium content was observed highest when cattle urine was added with cattle manure. The cumulative biogas production during 92 days of experiment was higher in the substrates containing urea, cattle urine and biogas spent slurry than the substrate having no additive.
The addition of additives thus, enhanced the reduction of total solids, volatile solids and biogas production as well as the Total Kjeldhal Nitrogen, phosphorous and potassium content in outlet slurry. The use of biogas spent slurry to enhance the gas production at low ambient temperature require is therefore, recommended.
Description
Keywords
null