COMPOSTING OF SPENT PIG LITTER IN TURNED AND FORCED-AERATED PILES

A study was carried out to compare the composting efficiency of spent litter (a mixture of partially decomposed pig manure and sawdust) in t urned and forced-aerated piles. Duplicate piles were built with manual turning (every 4 days) during composting, and duplicate piles were se t up with forced aeration using an air pump. The present study demonst rated that the efficiency of composting in the turned and forced-aerat ed piles was similar. Spent litter in these piles reached maturity at the same time (60 days). The forced-aerated piles went through similar physical, chemical, and microbial changes with the turned piles durin g composting. The forced-aerated composting system was also as effecti ve as the turned system in eliminating Salmonella sp. in the spent lit ter. These results suggest that a forced-aerated composting system cou ld be used as an alternative method in composting spent litter. The si milarities in temporal changes in temperature, chemical, and microbiol ogical properties of the forced-aerated piles, compared with the turne d piles, indicate that addition of a bulking agent under forced aerate d composting of spent litter is not necessary. The partially decompose d sawdust in the spent litter provided enough free air space, allowing the delivery of oxygen for the microorganisms in the spent litter pil es. (C) 1998 Elsevier Science Ltd. All rights reserved.