Evaluation of a combined anaerobic and aerobic system for the treatment of slaughterhouse wastewater

Abstract

A laboratory scale anaerobic/aerobic (An/Ar) system, comprising an anaerobic filter (AF) coupled to an aerobic sequential batch reactor (SBR), was developed to treat wastewater from a slaughterhouse. The AF operated with organic loadings (OL) from 3.7 to 16.5 kg m⁻³ d⁻¹ and a hydraulic retention time (HRT) ranging from 16 to 72 h. The efficiency of chemical oxygen demand (COD) removal was between 50 and 81% and was shown to be related inversely to the value of the OL. The production rate of methane was in the region of 411 mL per g of COD removed. On the other hand, the degradation of organic matter (OM) by an aerobic pathway in the SBR followed first‐order kinetics with regard to OM concentration; 85% of the remaining OM from the AF was eliminated within 6 h of aeration, and over 95% of total OM was eliminated as COD within 9 h. The optimal treatment conditions in this system were found at OL = 11.0 kg m⁻³ d⁻¹ and HRT = 24 h in the AF, whereas the SBR was most efficient at 9 h of aeration.

Keywords:

• anaerobic filter
• batch reactor
• slaughterhouse
• treatment system
• wastewater
• sequential batch reactor

Acknowledgements

The authors wish to thank the Consejo Nacional de Ciencia y Tecnología (CONACYT), Mexico, for financial support during this research. The authors are also grateful to visiting investigator Dana Erickson, and William Prescott of the United States Peace Corps/Mexico, for their assistance in revising this paper.