Modelling the coag-flocculation kinetics of cashew nut testa tannins in an industrial effluent

The coagulant behaviour of tannins of Anacardium occidentale (CANTETA) testa was assessed for the removal of suspended solids from a fibre-cement industry effluent. A series of flocculation experiments were conducted to examine the optimal concentration of the coagulant together with the pH of the effluent needed to obtain the best results. The results showed that CANTETA have significant flocculation properties particularly at lower doses and in alkaline medium. Optimum efficiency for TSS removal was 84% with 100 mg/L CANTETA at initial effluent pH of 12. The kinetics of the coagulation process suitably fits the second order kinetic model.