Phycoremediation of palm oil mill effluent (POME) and CO₂ fixation by locally isolated microalgae: Chlorella sorokiniana UKM2, Coelastrella sp. UKM4 and Chlorella pyrenoidosa UKM7

The Malaysian palm oil industry generates large amount of palm oil mill effluent (POME) and carbon dioxide (CO2). Appropriate control of this industrial discharge through biological means is essential to achieve sustainable development. This study discloses the practical way of reducing pollutants in POME and fixing CO2 by using three locally isolated microalgae species: Chlorella sorokiniana UKM2, Coelastralla sp. UKM4 and Chlorella pyrenoidosa UKM7. The identification of the microalgal-assimilable organic carbon sources in POME is first reported in this paper. The microalgae strains were cultured independently in 10 % (v/v) POME aerated with 1% (v/v) CO2. Throughout the process, C. sorokiniana UKM2 showed the highest CO2 uptake rate of 567 mg L-1 day(-1) and nutrient removal efficiency (NRE) of ammonium (NH4+), total nitrogen (TN) and total phosphate (TP) of 100 %, 65 % and 56 % respectively. Meanwhile, Coelastella sp. UKM4 and C. pyrenoidosa UKM7 exhibited CO2 fixation rates ranging from 396 to 486 mg L-1 day(-1), whereas the NRE of NH4+-N was 100 %. The NRE of TN and TP ranged from 59 % to 63 % and 41%-56%, respectively. Both Chlorella species presented higher average nutrient removal rates (ANRR) of NH4+-N, TN and TP than Coelastralla sp. UKM4. This study indicated that these three native microalgal species possess great potential for integration into the phycoremediation of POME and CO2 fixation.