Phycoremediation by simulating marine aquaculture effluent using Tetraselmis sp. and the potential use of the resulting biomass

This study investigates the capability of Tetraselmis sp. for treating mariculture wastewater in a 70-L high-rate algal pond and determines the feasibility of using the resulting biomass. The culture medium contained 45 mg L-1 nitrates, 10 mg L-1 nitrites, 30 mg L-1 ammonium, 17 mg L-1 orthophosphates and 270 mg O2 L-1 of dissolved organic matter as chemical oxygen demand (COD). The culture was kept under a 12 h:12 h light:darkness photoperiod using a photosynthetically active photon flux density of 1500 ?mol m-2 s-1, and a temperature of 23 ± 2 °C. A 4-cycle growth semicontinuous culture was used obtaining on average 1.19 g L?1 dry biomass, with lipid content of 62.16 mg g?1. In the first batch culture cycle, 11.4 percent of highly non-saturated fatty acids were obtained, and a significant decrease thereof was observed in subsequent batch culture cycles. Nutrient removals were 95.5 ± 0.4 percent total nitrogen, 94.4 ± 0.5 percent ortho-phosphates and 61.4 ± 3.9 percent COD. These results show the feasibility of mariculture wastewater treatment using the studied microalga, with the advantage of producing biomass containing accumulated lipids and usable as food for mariculture species. Thus, it may be possible to reduce the cost of wastewater treatment and of culturing marine species.