Enhancement of Bioreactor Performance Using Acclimatised Seed Sludge in Anaerobic Treatment of Chicken Slaughterhouse Wastewater: Laboratory Achievement, Energy Recovery, and Its Commercial-Scale Potential

SIMPLE SUMMARY: Chicken slaughterhouses generate wastewater rich in organic contaminants and nutrients. Chicken slaughterhouse wastewater (CSWW) is considered high-strength wastewater, hence becoming a potential candidate for treatment processes that can recover energy. This study focused on the performance comparison of two sets of upflow anaerobic sludge blanket (UASB) reactors inoculated with different seed sludge treating CSWW. The reactor inoculated with seed sludge acclimatised on modified synthetic wastewater successfully produced a significant methane yield and removed chemical oxygen demand (COD) in the effluent, which complied with the discharge parameter set by the Department of Environment (DOE) Malaysia. At the optimum loading rate of bioreactor operation, energy recovery from laboratory scale (LS) and commercial scale (CS) systems were evaluated and proven to produce significant energy yield for wet market usage. Furthermore, a preliminary design of an on-site CS system was also proposed based on the actual daily volume of CSWW generated, output from process performance study, and existing design of the LS system. ABSTRACT: Lack of good management practice of chicken slaughterhouse wastewater (CSWW) has caused pollution into water bodies. In this study, the potential of seed sludge acclimatised modified synthetic wastewater (MSWW) on bioreactor performance and energy recovery of CSWW treatment was investigated. Two sets of upflow anaerobic sludge blanket (UASB) reactors were employed. The seed sludge in UASB 2 was acclimatised with MSWW for 30 days. In UASB 1, no acclimatisation process was undertaken on seed sludge for control purposes. After the acclimatisation process of UASB 2, both reactors were supplied with CSWW under the same condition of organic loading rate (OLR = 0.5 to 6 gCOD/L/d) and mesophilic condition (37 °C). COD removal efficiencies of UASB 2 were >80% all through the steady-state of the OLR applied. Meanwhile, a drastic decrease in overall performance was observed in UASB 1 when the OLR was increased to 3, 4, 5, and 6 gCOD/L/d. Energy recovery from laboratory scale and projected value from commercial-scale bioreactor were 0.056 kWh and 790.49 kWh per day, respectively. Preliminary design of an on-site commercial-scale anaerobic reactor was proposed at a capacity of 60 m(3).