Feasibility Study on the Utilisation of Rubber Latex Effluent for the Production of Bacterial Biopolymers

The natural rubber industry ranks second to the palm oil industry in Malaysia. It is estimated that about 100 million litres of effluent is discharged daily from rubber. processing factories. Rubber latex effluent is the most polluting source, with a high biochemical oxygen demand (BOD). Utilisation of this effluent such as use of a coupled system not only can reduce the cost of treatment but also yield a fermentation feedstock for the production of bioplastic. This study initially was carried out to increase the production of organic acids by anaerobic treatment of rubber latex effluent. It was found that through anaerobic treatment the concentration of organic acids did not increase. This was caused by the bioconversion of the volatile fatty acids (VFA) to biogas. Consequently, separation of organic acids from rubber latex effluent by anion exchange resin were examined as a preliminary study of recovering acetic and propionic acids. However, the suspended solids (SS) content in the raw effluent was rather high which partially blocked the ion-exchange columns. Lime was used to remove the SS in the rubber latex effluent. At pH 12, SS removal involved aggregation of the SS as floes that can be easily sedimented. After the lime precipitation process, organic acids were found to adsorb strongly onto the anion exchange resin. Less adsorption of organic acids onto the resin was observed before the lime precipitation. This was probably due to more sites being occupied by colloidal particles on the resin thus inhibiting the adsorption of organic acids. Thus, removal of the SS was necessary. The breakthrough curve showed that the exchange capacity for treated effluent subjected to Dowex SBR anionic-exchange column after separation by Dowex 88 cationic-exchange column was improved . The initial concentration of organic acids in the raw effluent was 3.9 g/L. After ion exchange, the concentration of the organic acids increased to 27 g/L, which could be utilised for production of polyhydroxyalkanoates (PHA).

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