Performance of ecological concrete-based ecological systems (ECBESs) for nitrogen removing from synthetic farmland drainage water

Efficiency and mechanism of nitrogen removals by ecological concrete-based ecological systems (ECBESs) were investigated in this study. Results show that ECBES performed well on denitrification. Ecological concrete as matrix of the ecological was positive for nitrogen removing according to that the experimental ECBESs achieved a greater TN removal compared to the control system. This result was possibly attributable to a higher biomass and increased bacteria diversity in ECBESs, since ecological concrete could be a carrier of microorganism. Vegetation could further improve TN removals. Acorus calamus L. - ECBES, Ipomoea aquatica Forsk - ECBESs, Oenanthe javanica (Bl.) DC. - ECBES and Zizania aquatica - ECBES achieved an average TN removal of 67.87%, 81.93%, 76.18%, 66.22%, respectively, in a test cycle. Nitrogen transformation in the ECBESs indicated the occurrence of ammonification, nitrification and denitrification. Moreover, bacteria related to nitrogen transformation was identified from the bio-film immobilized on the ecological concrete.