Treatment of piggery wastewater by contact aeration treatment in coordination with the anaerobic fermentation of three-step piggery wastewater treatment (TPWT) process in Taiwan

The contact aeration treatment process is an improved activated sludge system in which sludge is not returned to the activated sludge basin. It was used to compensate the disadvantage of the activated sludge system in the three-step piggery wastewater treatment (TPWT) process. A wave-shaped vinyl plastic was used as biofilm support substratum for this study. The hydraulic retention time (HRT) for anaerobic fermentation step of TPWT was varied to verify the effects of contact aeration treatment process. The results showed that removal rates of biochemical oxygen demand (BOD), chemical oxygen demand (GOD), and suspended solid (SS) by contact aeration treatment process in coordination with the anaerobic fermentation of TPWT process were all over 90%. Especially, both BOD and SS of effluents met the Effluent Standard for Livestock of 1998 of the R O. C. Environmental Protection Agency(EPA). For COD removal only two experimental sets, anaerobic HRT = 4 and 7.5 days, of COD met the effluent requirement of 1993. Therefore, the application of contact aeration treatment process on the TPWT facilities was proven to remove BOD, GOD, and SS from piggery wastewater efficiently.