Carbon Fiber Amended Anaerobic Biofilm Reactor for Source-separated Blackwater Treatment

Abstract

Decentralized domestic wastewater treatment is a new sanitation concept by separating greywater and blackwater at source for different treatment procedures. Anaerobic treatment is regarded as the core technology for simultaneous organic matter removal and biomethane production from source-separated blackwater, which possesses huge potential for bioenergy recovery. In this study, a promising treatment system, named carbon fiber amended anaerobic biofilm reactor, was designed and operated for evaluation of long-term performance and system stability for high-strength blackwater. At different hydraulic retention times (HRTs) ranging from 20 to 5 days and organic loading rates (OLRs) varied from 0.77 to 3.01 g COD/L-d in four stages, superior and stable performance was observed during the long-term operation about 250 days. With the increase of OLRs, the specific methane production rate increased from 105.3 to 304.6 mL/L-d with high purity of methane (75.5-83.0 %). The maximum methane yield was achieved at HRT of 15 days, which was 38.4% out of 45% biochemical methane potential (BMP). Highest organic compound and suspended solid removal (80-83 %) was achieved at 20-days HRT, while the increased OLRs resulting in diminished removal efficiencies. The state variables including pH, total ammonia nitrogen (TAN), short-chain volatile fatty acids (SCVFAs) and soluble COD (SCOD), indicated the system had a great capacity to withstand the high organic loading rates for anaerobic blackwater treatment.