Potential of Ulva lactuca for municipal wastewater bioremediation and fly food

Macroalgae are considered a promising approach for wastewater treatment and could also ultimately provide an alternative animal food source in addition to a biofuel feedstock. Their large size and/or tendency to grow as dense floating mats or substrate-attached turfs lead to lower separation and drying costs than microalgae. In this study, the macroalgae species Ulva lactuca (U. lactuca) were used to investigate their capacity for treating municipal wastewaters, and the feasibility of using the harvested biomass as a feed for the fruit fly Drosophila melanogaster, an animal model for biological research. Results indicated that U. lactuca could successfully grow on three types of wastewaters studied with biomass productivities of 8.12-64.3 g.DW (dry weight)/(m(2).d). The secondary wastewater (SW) was demonstrated as the most effective wastewater medium for U. lactuca growth. However, both high nitrogen (92.5%-98.9%) and phosphorus (64.5%-88.6%) removal efficiencies were observed in all wastewaters, particularly in primary wastewater and SW, while the highest removal rates (N 24.7 +/- 0.97 and P 0.69 +/- 0.01 mg/(g.DW.d)) were obtained in centrate wastewater. Moreover, the addition of 20% washed U. lactuca into 80% standard fly food (w/w) led to an extended life span and stable body weights in flies while not for the food treatment with 20% unwashed U. lactuca. This study demonstrates an effective approach for the macroalgae-based treatment of municipal wastewater and the biomass for animal feed.