Optimization of CO₂ sequestration by Microalgae Chlorella Sp. growing in palm oil mill effluent (POME) from polishing pond

Palm oil mill effluent (POME) is one of the high constituted waste in a palm oil processing plant, this waste has high biological oxygen demand (BOD) which disables it to be released directly to natural water source. Recent technology allows POME to be manipulated into bioenergy that is digestion to produce methane through anaerobic digestion. Unfortunately, this conversion produces high amount of carbon dioxide (CO₂). A novel attempt has been idealized to lower the BOD of POME and at the same time sequestered the CO₂ produced from the conversion of bioenergy. In this study, a microalgae species of Chlorella sorokiniana was used to treat the POME and simultaneously sequestered CO₂ gas. An optimization study was done to find the optimum condition that gives maximum growth of the microalgae with two variables controlling the process which were CO₂ concentration and sparging rate. Optimization of the microalgae growth was done by response surface methodology where data was obtained from factorial experiments and composite experiments. The data was fitted in logistic equation by using MATLAB R2013a software. The data obtained from the regressions are evaluated to see the validity of the points and are then extrapolated into quadratic equation to obtain a maximum point. Form the quadratic equation plot, it was found that at sparging rate of 0.800 vvm and at CO₂ concentration of 16%, the maximum biomass concentration is 1.7882 g/L. However, these conditions is of a contradiction towards the growth rate.