Water-Nutrient-food Nexus The Role of Green Algae for Sustainable Food Production in Urban Wetlands Through Untreated Wastewater

Abstract

The nutrients in domestic wastewater are increasingly being regarded as a valuable resource for energy and nutrient recovery for an Eco-city. The nutrient stream can be used safely for food production through ecological engineering interventions (introduction of green algae in urban wetlands). Effects of wastewater on growth yield and microbial contamination on hydroponic tomato (Lycopersicon esculentum) was studied in pilot scale wetland for 6 month under the presence of green algae (Euglena sp.) with different chlorophyll a concentration. Domestic wastewater (BOD 205 mg.L^-1, TN 29 mg.L^-1 and TP 8 mg.L^-1) with loading rate of 0.9 L.m^-2.d^-1 was used for each wetland. The wastewater did not affect fruit pH, increased their size up to 1.7 ± 0.31 cm in diameter, and weight up to 69.3 ± 6.0 g. Microbial contamination (Total coliforms (TC) and Fecal coliforms (FC)) on fruit surface significantly decreased (p < 0.05) with the increasing algal concentration up to 240 μg.L^-1. Inactivation of bacterial contamination (TC and FC) under the presence of algae associated with high dissolved oxygen concentration (9.7 ± 1.1 mg.L^-1) and pH increases (8.2 ± 0.8) attributes in wetland. In summary, tomato production in urban wetlands under the presence of green algae enhances the importance of safe and sustainable food production through untreated wastewater.