Wastewater from Biodiesel Production as a Carbon Source for Denitrification of Sludge Liquor in SBR

摘要

Sludge liquor from an anaerobic sludge digester with an average N-NH4 concentration of γ= 1185 mg L~(-1) was treated in a pilot-scale SBR (sequencing batch reactor) system. The returned activated sludge of a WWTP was used as inoculum. The average efficiency of N-NH4 removal was over η = 90 %. Concentrations of N-NH4 in the effluent were typically below 10 mg L~(-1). The maximal achieved nitrification rate was r_N = 9.1 mg g~(-1) h~(-1) (relative to MLVSS). Wastewater of methyl ester wash arising during biodiesel production was used as an external carbon source for denitrification. A dosage of 3.5 - 4.5 g of COD per 1 g of nitrogen available for denitrification was found optimal. Typical effluent N-NO3 concentration was about y = 25 mg L~(-1) and maximal achieved denitrification rate was r_D = 14.5 mg g~(-1) h~(-1). Operation of the SBR was stable at a HRT of τ = 4 - 5 days.