Dynamic remediation test of polluted river water by Eco-tank system

Abstract

Dynamic remediation of river water polluted by domestic sewage using an aquatic plants bed-based Eco-tank system was investigated. Over a period of 18 days, the test demonstrated that average effluent concentrations of chemical oxygen demand (COD), ammonium nitrogen () and total phosphorus (TP) were as low as 17.28, 0.23 and 0.03 mg/L, respectively, under the hydraulic retention time (HRT) of 8.7 d. The average removal efficiencies in terms of COD, and TP could reach 71.95, 97.96 and 97.84%, respectively. The loss of both and TP was mainly ascribed to the uptake by plants. Hydrocotyle leucocephala was effective in promoting the dissolved oxygen (DO) level, while Pistia stratiotes with numerous fibrous roots was significantly effective for the removal of organic compounds. The net photosynthetic rate, stomatal conductance, transpiration rate and biomass accumulation rate of Myriophyllum aquaticum were the highest among all tested plants. Thus, the Eco-tank system could be considered as an alternative approach for the in situ remediation of polluted river water, especially nutrient-laden river water.

Keywords:

• polluted river water
• Eco-tank
• dynamic test
• remediation
• removal efficiency

Acknowledgements

This work was supported by the National Major Science and Technology Specific Projects on Water Pollution Control and Treatment of China (No.2008ZX07101-006-08) and the Key Project of Zhejiang Province (No.2009C03006-3).