Park J B K, Craggs R J, Sukias J P S
National Institute of Water and Atmospheric Research Ltd, PO Box 11-115, Hamilton, New Zealand.
Bioresour Technol. 2008 May;99(8):2711-6. doi: 10.1016/j.biortech.2007.07.009. Epub 2007 Aug 21.
This study investigated the feasibility of using pre-treated plant liquors as organic carbon sources for the treatment of hydroponic wastewater containing high nitrate-N (>300 mg N/L). The waste plant material was pre-treated to extract organic carbon-rich liquors. When this plant liquor was used as an organic carbon source in denitrification filters at the organic carbon:nitrogen dose rate of 3C:N, nitrate removal efficiencies were >95% and final effluent nitrate concentrations were consistently <20mg N/L. However, at this dose rate, relatively high concentrations (>140 mg/L) of organic carbon (fBOD5) remained in the final effluents. Therefore, a 'compromise' organic carbon:nitrogen dose rate (2C:N) was trialled, at which nitrate removal efficiencies were maintained at >85%, final effluent nitrate concentrations were consistently below 45 mg N/L, and effluent fBOD5 concentrations were <25mg/L. This study has demonstrated that waste plant material is a suitable carbon source for the removal of nitrate from hydroponic wastewater in a denitrification filter.
