Treatment of Wastewater from Slaughterhouses by Electrocoagulation:Case Study of Gachororo Slaughterhouse, Kiambu County, Kenya

Abstract

Wastewater from slaughterhouses is highly contaminated with high concentrations of organic and colloidal materials such as proteins, cellulose, and fats, as well as suspended solids.  Discharge of this water in the rivers brings about changes which affect the water quality and the microflora, and increases long term biological oxygen demand (BOD) as well as water treatment problems. The conventional methods used to treat this water are characterized by many disadvantages including; production of high levels of sludge, high energy consumption required for aeration, sensitivity to high organic loading rate and long hydraulic retention times. This makes it necessary to explore other alternative treatment methods such as electro-coagulation. This study therefore sought to explore wastewater remediation using electro-coagulation method. The purpose was to establish a method of treating water cheaply and more effectively in an environmental friendly manner. Samples of both raw slaughterhouse effluent and treated water samples were taken and subjected to standard procedures to determine the levels of pH, Chemical Oxygen Demand, Turbidity, Total Suspended Solids, and Biological Oxygen Demand. The results reveal that electro-coagulation method is able to reduce all these parameters in wastewater to levels that are acceptable by regulating boards such as Government of Kenya Standards for treated wastewater and effluent discharge into the environment. Electrocoagulation was able to reduce BOD, COD, TSS and turbidity to 20.78mg/l, 16.33mg/l, 2.33mg/l and 2 NTU from 1278mg/l, 1475mg/l, 405mg/l and 978 NTU respectively at voltage of 25V and surface area of 40 cm² with aluminum electrodes and 90 cm² when  iron electrodes were used. Electro-coagulation is therefore an effective method for treating wastewater from slaughterhouses.

Keywords: Electrocoagulation, slaughterhouse wastewater, Biological Oxygen Demand, Chemical Oxygen Demand, alkalinity, turbidity, conductivity, pH, total soluble solids, Electrodes.