Biotechnological application of microalgae for integrated palm oil mill effluent (POME) remediation: a review

Microalgae have received great attention as a source of bioenergy production and potential for industrial effluent remediation. Malaysian palm oil industry is discharging a huge amount of industrial effluent in the form of palm oil mill effluent (POME) containing a high amount of biological oxygen demand, chemical oxygen demand, and heavy metals, which can cause severe pollution to the environment. Consequently, the palm oil industry is facing remarkable challenges to obey environmental regulations. POME has its own potential for sustainable reuse through biotechnological advancement. Microalgae cultivation limitation and expensive growth medium are the main drawback for the algal industry; therefore, the incorporation of wastewater treatment has provided a possible solution to reduce dependency on commercial medium while it remediates the wastewater. The integrated POME treatment by culturing microalgae could potentially reduce the retention time for wastewater treatment and eliminate toxic elements, which are utilized as a nutrient by the microalgae. Furthermore, harvesting of microalgal cells from treated effluent is also the main challenge. This review article discusses the potential, benefits, strategies, and challenges of microalgae to be used for integrated effluent treatment, mainly (POME) due to its hazardous properties. Immobilization of microalgae for continuous, efficient POME treatment and harvesting of immobilized microalgae through simple filtration method have also been discussed.