Influence of bulking agents on organic matter evolution during sewage sludge composting; consequences on compost organic matter stability and N availability.
The influence of bulking agents on organic matter (OM) stability and nitrogen (N) availability in sludge composts was investigated. Seven mixtures were composted over a 12-week period in 170 L-reactors using the same sludge with different bulking agent mixtures. The OM evolution was characterised by carbon (C) and N mass balances in biochemical fractions. The evolution of OM stability and N potential availability were measured during soil incubations. The type of bulking agent had little influence on the intensity of OM stabilisation and the N availability in final composts. However, they influenced the time to reach similar OM stability and the biochemical evolution of OM. Depending on their ligno-cellulosic characteristics and a careful control of aeration, initial mixtures with high C:N ratio and rather biodegradable carbonaceous materials could favour the organisation of initially present mineral N or easily mineralisable sludge N and therefore limit NH3 volatilisation responsible for the low compost N availability measured.
Doublet
J
J
INRA, UMR 1091 Environnement et Grandes Cultures, F-78850 Thiverval-Grignon, France.
Francou
C
C
Poitrenaud
M
M
Houot
S
S
D002244:Carbon / Q000032:analysis; D005591:Chemical Fractionation; D009584:Nitrogen / Q000032:analysis*; D009930:Organic Chemicals / Q000032:analysis* / Q000138:chemical synthesis / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
D009930:Organic Chemicals; D012722:Sewage; D012987:Soil; D002244:Carbon; D009584:Nitrogen