Anaerobia digestion of sheep manure to produce biogas and biofertilizer

Abstract

Objective: To test three different sheep manure management to produce biogas and biofertilizer.

Design/methodology/approach: A 2.51 m³ membrane reactor was used and three ways of preparing the manure were evaluated: fresh crushed, fresh without treatment and dry ground. Each treatment was evaluated for one month and the daily production of biogas, the ambient temperature and the pH of the effluent and the flowing were recorded. The nutritional content of the digest was analyzed.

Results: The highest production of biogas (1.20 m³ día^-1) was obtained with fresh crushed manure, and was statistically higher than that generated with fresh untreated manure (0.86 m³ día^-1) and dry ground manure (0.75 m³ día^-1). These yields were from 0.05 to 0.08 m³ of biogas per kg of manure fed. The liquid effluent showed a low content of nutrients, however, about 56 liters were obtained daily. The mud, on the other hand, presented important contents of nutrients that makes it a material with high potential as a biofertilizer.

Limitations on study/implications: During the evaluation of untreated fresh manure and dry ground manure the ambient temperature was higher, but the biogas production was lower.

Findings/conclusions: It was demonstrated that good production of biogas and biofertilizers can be obtained from sheep manure by means of their anaerobic digestion in a tubular biodigester.