Research Letter
David Nzioka Mutua, Eliud Nyag
Abstract
In the eastern Africa sub-region, many industries discharge untreated effluents to nearby water resources, thereby polluting the environment. This is because the technologies applicable for wastewater treatment are expensive for these small-medium sized companies with low profit margins. Slaughterhouses belong to this category of industrial setup. The objective of this study was to investigate treatment of meat processing wastewater using anaerobic– aerobic/anoxic Sequencing Batch Reactors (SBRs) operated in series. Reactors were operated for one year using meat processing wastewater. Hydraulic retention time was 2 days for the anaerobic SBR, and 1 day for the aerobic/ anoxic SBR while the organic loading was 12.8 kg COD/m3/day. In the anaerobic SBR, removal efficiencies for total and soluble chemical oxygen demand (TCOD and SCOD), total suspended solids (TSS) and turbidity were 79, 76, 79, and 70%, respectively, with effluent mean concentrations of 3554 ± 58 mg/L, 762 ± 3 mg/L, 2307 ± 21, and 2800 ± 9 FAU. Conductivity, ammonia-nitrogen, ortho-phosphates and total phosphorus concentrations increased by 38, 80, 81 and 71%. Pollutant removal efficiencies in the aerobic/anoxic SBR were 98, 96, 97, 89, 74, 97, 91, 90, and 86% for TCOD, SCOD, BOD, TSS, turbidity, ammonium nitrogen (NH4 +–N), total nitrogen (TN), orthophosphorus (o-PO4 3-–P), and total phosphorus (TP), respectively. Except TKN (35 ± 4 mg/L) and o-PO4 3-–P (8 ± 1 mg/L), all other parameters in the aerobically treated effluent met national discharge standards. Thus, abattoir effluent can be treated using anaerobic–aerobic/anoxic SBR system.