Effect of thermal-alkaline pretreatment on the anaerobic digestion of streptomycin bacterial residues for methane production.

The anaerobic digestion of streptomycin bacterial residues, solutions with hazardous waste treatments and bioenergy recovery, was tested in laboratory-scale digesters at 35°C at various organic loading rates (OLRs). The methane production and biomass digestion were efficient at OLRs below 2.33 gVS L(-1) d(-1) but were deteriorated as OLR increased because of the increased total ammonia nitrogen (TAN) concentration from cell protein decay. The thermal-alkaline pretreatment with 0.10 NaOH/TS at 70°C for 2 h significantly improved the digestion performance. With the thermal-alkaline pretreatment, the volumetric reactor productivity and specific methane yield of the pretreated streptomycin bacterial residue increased by 22.08-27.08% compared with those of the unpretreated streptomycin bacterial residue at an OLR of 2.33 gVS L(-1) d(-1). The volatile solid removal was 64.09%, with less accumulation of TAN and total volatile fatty acid.