Piyarat Boonsawang, Athirat Rerngnarong, Chakrit Tongurai, and Sumate Chaiprapat

pp. 643 - 649

Abstract

A laboratory scale two-stage anaerobic process was studied in order to treat biodiesel wastewater. The first stage
represented an acidogenic reactor while the second stage was a methanogenic reactor. The effect of nitrogen and phosphorus
on the performance of both reactors was investigated. Biodiesel wastewater was adjusted so that its COD:N and COD:P
within 100:0.1–1.1 and 100:0–1, respectively, and fed into the acidogenic reactor. After COD and pH adjustment, wastewater
discharged from the acidogenic reactor was fed into the methanogenic reactor. The highest VFA concentration of 8.32 g/l was
obtained from the acidogenic reactor at COD:N:P of 100:1.1:0.5. However, the highest CH₄
 yield of 0.170 l CH₄
/g COD_removed
was found at COD:N:P of 100:0.6:0.5 from the methanogenic reactor. Moreover, both nitrogen and phosphorus affected the
acid composition produced in the acidogenic reactor and the long chain fatty acid consumption in the acidogenic and
methanogenic reactors.