phytoremediation of kitchen wastewater by spirulina platensis (nordstedt) geiteler: pigment content, production variable cost and nutritional value

Abstract

Phytoremediation of domestic wastewater by Spirulina platensis was carried out using kitchen wastewater. A complete randomised design (CRD) was created for the experiment which was performed on modified Zarrouk’s medium (Zm), 100% kitchen wastewater (100%Kw) and 90% kitchen wastewater (90%Kw). Water quality, biomass production, pigment content and nutritional value of Spirulina platensis were determined from cultures harvested every 5 days for a period of 15 days. The physico-chemical properties of cultivated wastewater were: water temperature 27-28 oC, pH 8.73-9.77 and DO 0.20-7.20 mg L-1. The 100%Kw and 90%Kw produced lower BOD, COD, TP, NH3-N, ON, TKN, NO3-N, NO2-N, TON and TN compared to Zm with p< 0.05. After cultivation, the treated kitchen wastewater met the standards for safe discharge in Thailand. The highest level of -carotene of S. platensis was achieved in Zm (0.29 mg g-1) and 100%Kw (0.29 mg g – 1) while the highest levels of C-phycocyanin were obtained in 100%Kw (17.95 mg g -1) and 90%Kw (16.31 mg g-1). The highest production variable cost for dry weight of S. platensis was in Zm (310.6 Baht kg -1) and 90%Kw (303.6 Baht kg -1) as compared to 100%Kw (276.6 Baht kg -1), with p<0.05. The highest biomass production of S. platensis was achieved in Zm (0.84 g L-1) and 100%Kw (0.82 g L-1), with protein content of 54.44% and 35.86%, respectively. Implications for the use of S. platensis for phytoremediation and C-phycocyanin production using of 100%Kw and 90% Kw are discussed.