Composting of de-inking paper sludge with poultry manure at three nitrogen levels using mechanical turning: behavior of physico-chemical parameters.
De-inking paper sludge (DPS) is rich in carbon (C) but poor in nitrogen (N). Thus, it has a high C:N ratio which limits the composting process. Accordingly, the goal of this study was to investigate the effect of three N treatments on DPS composting. Compost piles of 100 m3 were formed by mixing raw DPS with poultry manure and chicken broiler floor litter, giving on average 0.6%, 0.7% and 0.9% total N. The changes in physico-chemical parameters, total weight and fiber losses, and maturity of composting piles of DPS were monitored during 24 weeks. The compost piles had a neutral to alkaline pH throughout the study. Inorganic N decreased whereas organic N increased over time for all treatments. These changes in magnitude were different among N treatments resulting in a final total N content of 0.9% for the 0.6% N treatment whereas final total N contents of 0.7% and 0.9% N were measured for the 0.7% and 0.9% N treatments. The total weight, cellulose and hemicellulose losses were higher in 0.6% N treatment giving the lowest C:N ratio after 24 weeks of composting. However, none of the 24 week-old composts of DPS were mature based on their final C:N ratio and colorimetric test of maturity. Except for copper, their final total trace element contents meet most known standards or guidelines for organic soil conditioners. Overall, 0.6% N treatment was the best to enhance DPS composting using mechanical turning, but a period of more than 24 weeks was required to reach compost maturity.
Charest
M H
MH
Department de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, Sainte-Foy, Qué, Canada.
Beauchamp
C J
CJ
D000818:Animals; D008372:Manure / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis; D010209:Paper; D011200:Poultry; D012722:Sewage; D018508:Water Purification / Q000379:methods
D008372:Manure; D012722:Sewage; D009584:Nitrogen