Anaerobic degradation of pulping midcourse wastewater by rumen microorganisms in batch reactor

Abstract

Batch experiments were performed to investigate the anaerobic degradation of pulping midcourse wastewater (PMW) by rumen microorganisms (RM). The operation included two stages. In stage one, 400 mL of PMW and 100 mL of RM were fed into a stirred batch-test reactor (1.2 L) which was kept at 39 ± 1°C for 14 days. The pH of the reactor was maintained at 6.7–7.0 to accommodate rumen organisms. Declined volatile fatty acids production was in line with the trend of the soluble chemical oxygen demand (SCOD) concentration profile. The SCOD removal efficiency was 38.0% at the end of stage one. The results showed that rumen organisms could accommodate PMW. The treatment effect of PMW by RM was investigated in stage two. About 200 mL of fresh PMW was added to the reactor. The maximum SCOD removal efficiency was 53.6% in stage two. Acetate and propionate were the major aqueous fermentation products, while butyrate and valerate were also found in smaller quantities. Generated biogas was composed of carbon dioxide, methane and hydrogen. This research provides useful information for the application of rumen cultures to the treatment of PMW.

Keywords:

• Pulping midcourse wastewater
• Anaerobic degradation
• Rumen microorganisms
• VFA
• SCOD