Long-term operating performance of a poultry slaughterhouse wastewater treatment plant

This paper evaluates the performance and process stability of a full-scale poultry slaughterhouse wastewater treatment plant in removing organic matter over a 4-year operation. The wastewater treatment system is composed of rotary and static screens, an equalization tank, a dissolved-air flotation (DAF) system and two upflow anaerobic sludge blanket (UASB) reactors. The operating strategy for UASB reactors to treat slaughterhouse wastewater involves the use of a tank to dampen fluctuations in flow and organic load, a DAF system to remove oil and grease (O&G) and suspended solids (SS) and an intermittent operation. Surface-loading rates of 1.6 ± 0.4 m3/m2 h applied to the DAF system in the operation under study resulted in O&G and SS removal efficiencies of 51 ± 16% and 37 ± 16%, respectively. The organic loading rate of 1.6 ± 0.4 kg COD/m3 day and the upflow velocities of 0.3 ± 0.1 m/h applied to the UASB reactors resulted in a similar and satisfactory performance, showing total chemical oxygen demand and soluble chemical oxygen demand removal efficiencies of 67% and 85%, respectively. Although the organic matter removal efficiencies of the treatment plant reached about 90%, the nutrients concentrations in the treated effluent pointed to the need for advanced wastewater treatment.