Application of Chlorella sp. and Daphnia sp. for treating organic waste derived from swine wastewater after UASB system usage

Abstract

The quality of typical treated swine wastewater does not often pass the effluent standard. There are some nutrients and organic matter, which cause deterioration in the water resources. Recycling this wastewater in a sustainable manner presents an important challenge. This study investigates the possibility of changing valuable matter in swine wastewater to algal, Chlorella sp. biomass and then harvesting by the order Cladocera, Daphnia sp.The quality swine wastewater of this experiment is also evaluated.

Samples collected from the effluent at the end of anaerobic and aerobic treatment pond of Dong Hiep farm were chemically analyzed at 430 mg/l, 174 mg/l, 538 mg/l, 191mg/l for COD, BOD₅, total Nitrogen (TN), total Phosphorus (TP), respectively. This sample diluted four times with tap-water before it was cultured Chlorella sp. under conditions of tests was 1000 lux of light intensity, 24^oC of temperature and without add a food for nutrient to remove organic matter, harvest 10⁷ cells/ml the algae biomass. The characteristics of swine effluent, including COD, BOD₅, and total nitrogen were better than the effluent standard and total phosphor wasn’t (18.9-100 mg/l), although its treatment efficiency was 47-56.15%. Then, Chlorella sp. biomass was harvested completely by Daphnia sp. (10 Daphnid (0-24 h old)/ 500 ml) after 16 days of cultivation. Population growth rate of Daphnia sp. were 0.18-0.23. Total nitrogen and phosphor continued to treat to 94.15%, 80%, respectively, and obtained the effluent standard.