**5. Concluding remarks**

This chapter presents the treatment performance of palm oil mill effluent by utilizing chitosan as natural coagulant. Chitosan is natural, food-based and environmentally friendly biopolymer which has enormous potential to be used to treat POME before discharged to watercourse. Some of the methods for combinations, as suggested in the study. The pollutant removal performance measure in terms of COD, color, and TSS removal percentage. The main contribution of this chapter is to provide a low cost and simple method to small and medium oil palm processing industry in processing their wastewater before discharge to the environment. For chitosan, the main advantage is that low dosage would contribute to high removal of suspended solids in POME. However, the disadvantage is that if paired with other methods such as ultrasound cavitation and ferric chloride, it would not have significant improvement in terms of pollutant removal percentage. On the other hand, ferric chloride could work with other methods to improve pollutant removal significantly. Nevertheless, utilizing chitosan would not contribute to significant increment in the overall treatment cost, which would encourage palm oil mill to adapt this method in treating their wastewater.
