Optimization of Microalgae Biomass Yield using Chlorella Sp. and Spirulina Sp. Cultivation in secondary treated wastewater effluent

Abstract

Conventional method for domestic wastewater treatment could be inefficient due to active organic loadings and high population. Thus, the treated wastewater still contains high nutrient of nitrogen, phosphorus, and ammonia that can lead to the eutrophication and threaten biodiversity in long run. This study is aimed to concentrate on the capability of microalgae, Chlorella sp. and Spirulina sp. cultivated with secondary treated wastewater effluent for nutrients removal and biomass yield. The secondary treated wastewater effluent sample was collected and analysed the nutrient characterization of total nitrogen (TN = 2.78 mg/L) and total phosphorus (TP = 2.13 mg/L) using standard method by APHA. The optimization of the best dilution of secondary treated wastewater effluent and the microalgae ratio of Chlorella sp. and Spirulina sp. were run by Research Surface Methodology (RSM). The optimum results were found which 100% of Chlorella sp. mixed with 50% of Spirulina sp. cultivated with 70% of secondary treated wastewater effluent dilution. The highest results obtained from microalgae biomass yield was 0.22 g/L. While the NPK were analysed using scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) obtained 0.6 wt% and 0.3 wt% for phosphorus (P) and potassium (K) respectively. Subsequently, the potential traits as a biofertilizer was positively observed based on these responses. This study shows Chlorella sp. and Spirulina sp. was able to grow in wastewater and have ability to become biofertilizer with phosphorus and potassium content.