OPTIMIZING USE OF HYDROGEN PEROXIDE AND ULTRAVIOLET IRRADIATION TO IMPROVE WASTEWATER QUALITY FROM WET COFFEE PROCESSING

Wet coffee processing utilises large volumes of water in their processing operations. Wastewater from wet coffee processing contains high organic load, color and pH which results to pollution of the water ways when not properly treated. This study was aimed at evaluating the effectiveness of use of oxidizing agents and UV irradiation to improve the wastewater quality from Kabete coffee factory wet coffee processing. Wastewater quality aspects that were assessed include pH, turbidity biological oxygen demand (BOD) and chemical oxygen demand (COD). The quality of dam water used for the coffee processing was significantly low and within the range water quality standard for disposal established by NEMA. The analysis of the wastewater quality established that pH, BOD, COD and turbidity were higher in the coffee processing wastewater and pond treated water. The use of hydrogen peroxide (H2O2) independently resulted in significant improvement of wastewater quality. The treatment of the wastewater with H2O2 reduced BOD and the COD and 81% and 73% respectively. The H2O2 reaction time of 120 min showed the highest on the BOD and COD improvement up to 127 mg/l and 1048 mg/l respectively. UV irradiation alone recorded a reduced effect on the waste water quality, the BOD and the COD were improved by 26% and 35% respectively. The combination of UV irradiation and H2O2 (AOP) significantly enhanced the BOD, COD and turbidity of the wastewater. The combination of ≥ 0.4% H2O2 and 120 min of UV irradiation significantly enhanced the BOD, COD and turbidity of the effluent. Therefore, advanced oxidation process can provide an effective and efficient coffee processing water waste treatment.