Research on the Duckweed Cultivation in Alcohol Wastewater and Energy Utilization

Abstract:

The freshwater duckweed（Lemna minor） from the campus lake is cultured in the alcohol waste water（oxidation pond effluent）. The optimum dilution ratio of alcohol waste water is 10 times. The maximum Relative Growth Rate（RGR） and protein content are 9.11% and 28.50%,respectively when the initial seeding density is 149 g/m²（wet weight）；The removal efficiencies of TN，TP，NH4+-N and COD of alcohol wastewater are similar under different seeding density. They are 46%~49%，70%~79%，78%~82% and 35%~38% respectively after culturing the duckweed for 8 days. The results show that duckweed has the ability to produce methane individually by the anaerobic digestion process；Methane-producing acidification period is shortened and the gas production capacity is improved for the advantages of complementary substrate by mixing the duckweed with excess sludge. The actual value of cumulative gas production is 2 963 mL，which is 11% higher than calculated value of 2 669 mL；In addition，methane purity is improved，from 50.29% of duckweed group to 56.93% of mixed group.