|
A low pH, ethanol-type fermentation process was evaluated for wastewater treatment and bio-hydrogen production from acidic beet sugar factory wastewater in a continuous stirred tank reactor (CSTR) with an effective volume of 9.6？L by anaerobic mixed cultures in this present study. After inoculating with aerobic activated sludge and operating at organic loading rate (OLR) of 12？kgCOD？m？3·d？1, HRT of 8h, and temperature of 35°C for 28？days, the CSTR achieved stable ethanol-type fermentation. When OLR was further increased to 18？kgCOD？m？3·d？1 on the 53rd day, ethanol-type fermentation dominant microflora was enhanced. The liquid fermentation products, including volatile fatty acids (VFAs) and ethanol, stabilized at 1493？mg·L？1 in the bioreactor. Effluent pH, oxidation-reduction potential (ORP), and alkalinity ranged at 4.1–4.5, ？250–(？290)？mV, and 230–260？mgCaCO3？L？1. The specific hydrogen production rate of anaerobic activated sludge was 0.1？L？gMLVSS？1·d？1 and the COD removal efficiency was 45%. The experimental results showed that the CSTR system had good operation stability and microbial activity, which led to high substrate conversion rate and hydrogen production ability. |
