Abstract:
A simple and efficient electrochemical method that utilizes two steel electrodes and is capable of
reducing the colour of tea effluent prior to its discharge into the river system has been developed. The effects of
potential difference, inter-electrode distance, surface area of electrodes to effluent volume ratio (S/V), effluent pH,
temperature and effluent dilution on power consumption, were investigated. This method was effective at a
potential difference of 24 volts, inter-electrode distance of 5 mm, S/V of 18.2 m2/m3 and effluent pH of 6. Effluent
dilution led to increase in power consumption while raising temperatures led to a reduction in power
consumption. Electrochemical method reduced COD, BOD and electrical conductivity by 96.6 %, 84.0 % and
31.5 % respectively but increased pH by 10.32 %. The final pH, EC, COD and BOD values were below KBS
maximum contaminant levels. The proposed mechanism in colour removal process was phenol coupling. Phenolic
tea colour pigments were oxidized by electrons from ionization of iron to form keto radicals, which polymerized
to form a long chain polymer. The polymer was electro-floated to the surface by hydrogen gas generated from the
reduction of water and oxidation of theaflavins.
