STUDY OF TOXICITY CONTROL STRATEGIES ON THE ANAEROBIC SLUDGE DIGESTION PROCESS AND STABILIZED SLUDGE QUALITY
- 1. Selçuk University, Engineering Faculty, Environmental Engineering Department, Konya, Turkey
- 2. Selçuk University, Engineering Faculty, Environmental Engineering Department, Konya, Turkey
- 3. Selçuk University, Engineering Faculty, Environmental Engineering Department, Konya, Turkey
- 4. Selçuk University, Engineering Faculty, Environmental Engineering Department, Konya, Turkey
Abstract: Mesophilic anaerobic digestion of sewage sludge was conducted in a continuously fed mixed lab-scale reactor implementing hydrogen sulphide control strategies as T: 35 ve 38˚C, 75 and 150 rpm, hydraulic retention time (HRT) (25 and 30 d) and iron chloride dosing (20, 25 ve 50 mg/L) to investigate any potential for improvement in system performance parameters as methane production, volatile solid (VS) removal and dewaterability of the effluent sludge. Higher mixing rate and iron chloride addition had a positive effect on the system performance in addition to reduction in H2S concentration. Volatile fatty acid (VFA)/alkalinity rate changed between 0.01-0.1 at operational parameters of 35 oC, 75 and 150 rpm and VS loading rate of 0.72-0.95 kg VS/m3.d. Dewaterability improved at higher mixing level and iron chloride dosing. Control strategies and reduction in HRT resulted in a reduction VFA and pH increase and stabilization at 7.44-7.52. Maximum methane production and VS removal were obtained as 0.6 L methane/VSfed and 54%, respectively, for HRT 30 d, 150 rpm and 25 mg/L iron chloride.