Anaerobic co-digestion of septage and landfill leachate

This paper examines the operating parameters and treatment efficiency in di gestion of septage with landfill leachate. Four lab-scale CSTR digesters we re operated at 35 +/- 1 degrees C. Septage and leachate were mixed at the r atio of 1:0, 1:1, 2:1 and 3:1 on the basis of chemical oxygen demand (COD). For each digester, the solids retention times (SRT) were controlled at 20, 10, and 5.3 days. The organic loadings and volatile solids loadings ranged from 0.3 similar to 1.4 kg COD/m(3)/day to 0.79 similar to 3.7 kg/m(3)/day , respectively. For the same SRT, a higher ratio of septage increased the r emoval efficiencies of total GOD, ammonia nitrogen and total phosphorus (T- P). The presence of septage enhanced the decrease of the NH3-N concentratio n of the leachate by 40%. When the organic loading was increased to 0.315 k g COD/m(3)/day (septage/leachate = 3:1) based on SRT 20 days, the removal e fficiencies of total COD, NH3-N, T-P, volatile solids, carbohydrate and pro tein were 86, 69, 86, 28, 82 and 80%, respectively. The methane yield incre ased with an increasing septage fraction. The dewaterability of the digeste d sludge was also determined. (C) 1998 Elsevier Science Ltd. All rights res erved.