Ecology, Environment and Conservation Paper

THROUGH ENVIRONMENT FRIENDLY ANAEROBIC FERMENTATION

R. Anuradha, P. Prabhu Prasadini, A. Rajashekhar Reddy and Md. Ajaz All Khan

Abstract

The nutrient / manure value of poultry litter before and after biogas production was evaluated at laboratory level. Poultry droppings, biogas slurry and dried biogas slurry were analyzed for moisture content, pH, electrical conductivity and chemical composition i.e. nitrogen, phosphorous, potassium, sodium, iron, copper, zinc and manganese. Microbial assay was conducted for the presence of pathogens namely Salmonella sps and E. coll. Poultry droppings neutral in reaction (pH 7.0), containing 3.34 % N, 1.88% P, 1.73% K, 0.48% Na, 3593 ppm Fe, 20.5 ppm Cu, 60.8 ppm Zn and 237.4 ppm Mn were used in the fresh form for biogas generation. Moisture content was highest in biogas slurry (90.5 %) and lowest in the dried biogas slurry (6.2 %) and in poultry droppings it ranged between 60.9 to 70.3 % within the time interval of 48 hours. In poultry droppings and biogas slurry the pH was neutral and in the dried biogas slurry it was moderately alkaline. Electrical conductivity was almost same through out the process. The nitrogen content of raw droppings and digested slurry was 3.34 % where as it was reduced to 3.06 % on drying of the slurry. Other nutrients like phosphorous, potassium, sodium, iron, copper, zinc and manganese were higher in digested slurry samples compared to poultry droppings. The microbial assay indicated the presence of pathogens such as Salmonella sps and E. coil in poultry droppings. The tests were negative indicating their absence in both fresh and dried biogas slurry samples which could be because of the anaerobic digestion and competitive inhibition inside the digester. Direct benefits of biogas generation from poultry manure include biogas production and biogas slurry as manure. Indirect benefits such as odour control, absence of fly/maggots menace, absence of pathogens viz., Salmonella sps and E. coil, make the technique eco-friendly.