Water purification of four aquatic plant species with the presence of iron-carbon interior electrolytic substrates.

Abstract

To compare water purification of common aquatic plants in wetland ecosystem, four common aquatic plant species (Eichhornia crassipes, Nymphaea tetragona, Acorus calamus and Phragmites australis) were used as study species. The effect of aquatic plants on the change of sewage ammonium nitrogen, COD, TP content during different experimental time (1-5 d) with the presence of iron-carbon interior electrolytic substrates were analyzed in small scale experimental apparatus. The results showed that single and combined aquatic plants could effectively remove ammonium nitrogen, COD, TP from the sewage compared with the no-plant control group, but the efficiencies were significantly different among the different species. Ammonium nitrogen removal up to 100% was achieved with E. crassipes in two days, and A. calamus in three days. Each plant combination performed well on ammonium nitrogen removal. Concentration of the sewage COD approached zero with E. crassipes in three days, A. calamus performed secondly. The concentration of COD in combination of E. crassipes and A. calamus water decreased by 85.1% to a minimum of 4.33 mg·L-1. The concentration of TP was the lowest with E. crassipes in four days, and second with P. australis. The lowest concentration of TP was found with the combination of E. crassipes and A. calamusin two days. The combination effect of interior electrolyte and plant was better than that of pure interior electrolyte on the purification of sewage. Plant configuration should be optimized according to the level of pollutants.