Application Of Electrocoagulation Process In Treatment Of Tea Factory Effluent: A Case Study Of Emrok Tea Factory Nandi County

Abstract

Tea processing industries in Kenya face a major challenge of waste water management despite the intervention of the government and other environmental agencies. This discard of large quantities of untreated tea processing wastewater into the aquatic ecosystem has hazardous effect on the environment and human health in consequence. Biological treatment method of waste water by use of free water surface ponds has been used with limited success in the removal of colour, chemical oxygen demand and biological oxygen demand (COD and BOD). The study purpose to evaluate performance of electrocoagulation process in colour removal and COD reduction in tea effluents. The study sought to examine the effect of optimal electrocoagulation operating variables on removal efficiency of colour and reduction of COD, determining the effect of rate of reaction on removal efficiency of colour and COD besides evaluating the energy consumption and operating cost in tea factory effluent treatment. In this study response surface methodology of full factorial experimental design with three factors at two levels was used to optimize and investigate the influence of current intensity, electrode distance and electrolysis time which are the process variables on removal efficiency of colour and reduction of COD in tea factory effluent. After selection of variables (independent) and their ranges, 8 experiments were established based on complete full factorial design. Design Expert 9 statistical software was used to analyse the data and carry out optimization using response surface methodology. Analysis of variance (ANOVA) was used to check the adequacy of the mathematical models. The study found that at optimal conditions of colour and COD removal were 99.43 % and 98.62 % respectively at Electrolysis time of 18 minutes, Electrode distance of 6 mm and current intensity of 250 mA/cm2 . Energy consumption was found to be 0.0018Kwh/m3 at an operating cost of 𝑈𝑆$ 0.004179032 /𝑚3 at laboratory scale. The findings further showed that at industrial scale design parameters such as Diameter, height, electrode spacing, retention time, current intensity and reactor volume were 100 cm, 150 cm, 60 mm, 59.94 minutes, 25 Amps and 1.2 m 3 respectively which equally reduces COD and Colour removal at 99.43 % and 98.62 with energy consumption of 4.8Kwh/m3 at an operating cost𝑈𝑆$ 0.744. In conclusion EC provides the most feasible alternative for treatment of tea effluent with a view of COD reduction and colour removal.