Performance comparison of three high rate anaerobic bioreactors for poultry slaughterhouse wastewater treatment

This study evaluated and compared the performance of three highly praised high rate anaerobic bioreactors (HRABs), including the expanded granular sludge bed (EGSB) bioreactor, the static granular bed reactor (SGBR), and the down-flow expanded granular bed reactor (DEGBR), for the treatment of poultry slaughterhouse wastewater (PSW) which is characterized by a high concentration in oil and grease, suspended solids, and nutrients. These three bioreactors were operated under mesophilic conditions and followed a similar operational methodology, which consisted of increasing the organic loading rate (OLR) as the bioreactor responded positively to fluctuating organic loads. The response to the fluctuations of the bioreactors was evaluated with respect to the removal of the organic matter contained in PSW at high throughput rate. This study revealed that the three bioreactors performed differently. This dissimilarity in performance was associated with the difference in the configuration of each reactor and the capacity of maintaining a high performance at increased levels of OLR. These configurations are specifically described in this study. Of the three bioreactors that were investigated, the DEGBR performed the best with total chemical oxygen demand (tCOD), biological oxygen demand (BOD5) and fats, oil, and grease (FOG) maximum removal percentages of 99.6%, 99.9% and 99.4%, respectively, for a maximum OLR of 38.9 gCOD/L.day. While the EGSB also provided appreciable results with 99.1%, 99.5% and 97%, for the maximum removal efficiency of tCOD, BOD5 and FOG, respectively. At last, the SGBR achieved tCOD, BOD5 and FOG maximum percentage removal of 97.6%, 99.2% and 97.7%, respectively.