Document Type : Original research
Authors
1
Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines Visayas, Miagao, Iloilo, Philippines
2
College of Agriculture and Forestry, West Visayas State University, Lambunao, Iloilo, Philippines
3
Institute of Aquaculture, College of Fisheries and Ocean Sciences, University of the Philippines Visayas, Miagao, Iloilo, Philippines; School of Marine Fisheries and Technology, Mindanao State University at Naawan, Misamis Oriental, Philippines
Abstract
Microalgae have been utilized as eco-friendly bioremediation agents in aquaculture wastewater with concomitant biomass production. However, growth, bioremediation efficiency, and the nutritional components of the resulting biomass still need assessment to evaluate their potential as bioremediation agents, growth performance, and fertilizer sources. This study evaluated five microalgae, namely, Tetraselmis tetrathele, Nannochlorum sp., Chaetoceros calcitrans, Isochrysis galbana, and Thalassiosira sp., grown using milkfish wastewater. Specific growth rate (SGR), biomass productivity and concentration, nutrient removal efficiency, and the nutritional components of the biomass were analyzed as bases for determination. Results showed that Nannochlorum sp. and Isochrysis galbana had the highest SGR of 0.263 and 0.255 μ day-1, respectively. However, due to their larger size, Tetraselmis tetrathele and Thalassiosira sp. had the highest biomass productivity and concentrations of 0.075 and 0.065 g L-1 day-1 and of 0.933 and 0.879 g L-1, respectively. Tetraselmis tetrathele is best in removing N and P, achieving removal efficiency of 98.24% and 98.87% for NH3-N and NO2-N, respectively, while 72.50% for P. Tetraselmis tetrathele and Thalassiosira sp. had significantly higher N, with no significant difference among microalgae for P. At the same time, Thalassiosira sp. was significantly higher in K. There was no significant difference among algae in terms of Cu, while Tetraselmis tetrathele and Thalassiosira sp. were significantly higher in Zn, Tetraselmis tetrathele, Nannochlorum sp., and Isochrysis galbana for Mn, and Thalassiosira sp. for Fe. Results indicate that Tetraselmis tetrathele emerged as the most efficient species for bioremediating aquaculture wastewater compared to the other microalgae. While Tetraselmis tetrathele and Thalassiosira sp. exhibited high biomass productivity and potential as fertilizer sources, they outperformed the other microalgae.
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