Potential of the microalgae-based integrated wastewater treatment and CO2 fixation system to treat Palm Oil Mill Effluent (POME) by indigenous microalgae; Scenedesmus sp. and Chlorella sp

Abstract

POME consists of a high concentration of nutrients and organic materials that can pollute the environment if it is not properly treated. In conventional treatment of POME, the ponding system emitted GHGs to the surrounding. Indigenous microalgae species have the potential for treating POME and capture CO2. This work demonstrates the capability of the indigenous strains Scenedesmus sp. and Chlorella sp. cultivated in the integrated treatment system to treat the industrial wastewater which is palm oil mill effluent (POME) and to capture CO2 from the flue gas. The objective of this research is to study the integration system of effluent treatment and CO2 fixation. The microalgae growth study was done by analysing the dry cell weight of the biomass. The nutrient reduction such as TN, PO₄ ³¯, COD and TOC were analysed as the responses while the CO2 fixation rate was calculated based on the final microalgae biomass obtained. The biomass biochemical components such as lipid, carbohydrate, and protein were analysed by the solvent extraction method. The nutrient reduction from the integrated system of effluent treatment and the CO2 fixation by Scenedesmus sp. UKM9 and Chlorella sp. UKM2 were 86% Total Nitrogen (TN), 85% Reactive Phosphate (PO₄¯³), 77% Total Organic Carbon (TOC) and 48% Chemical Oxygen Demand (COD). The CO2 fixation rate by Chlorella sp. UKM2 achieved up to (0.829 g of CO2. L¯¹. day ¯¹). The study proved that integrated effluent treatment and CO2 fixation operation has a higher nutrient reduction in POME and more CO2 fixed in comparison to the individual treatment operation as two microalgae species with different metabolic traits were used in this integrated system to enhance treatment performance. Furthermore, by having this integrated treatment operation, the available nutrients in POME from the first effluent treatment stage is further utilised in the second stage. Thus, more pollutant in POME is reduced. Scenedesmus sp. (UKM9) and Chlorella sp. (UKM2) biomass biochemical composition specifically protein, carbohydrate, and lipid were tested to propose the use of microalgae biomass as resources for the industrial applications.