Exploitation of Phragmites australis (Reeds) in filter basins for the treatment of wastewater

Abstract

Background and Objective: The amount of wastewater produced by small communities and rural areas (Morocco) is not enough for the cost-effective operation of a conventional treatment plant. The development of the vertical flow planted filters (Phragmites australis) for the treatment of household influents tested in our study for effective and appropriate solutions in the treatment of wastewater from the areas haven't connected to sanitation networks. Materials and Methods: In operation, the secondary effluent is supplied separately by the two anaerobic bioreactors whose effluent depends on the treatment of the external bioreactor1 fed with nitrate and the nitrate naturally present in the primary effluent, while the bioreactor 2 comes supplied with nitrate from the primary effluent. This allowed the application of average monthly organic load rates (chemical oxygen demand) of 317.31 mg L-1 with different filters. The nitrate loading of the effluent after pond filtration ranged from 101.77-176.44 mg/day. In addition, the filters were planted by reeds and filtered without vegetation (control). The data were analyzed statistically by one-way ANOVA using SPSS. Results: The filtering basins impact on the elimination of different pollutants from sewage effluents from 46.88-63.24% COD and from 31.72-58.88% of NH4+ conversion, as well as only on the effect of reeds on the absorption of nitrogen was observed. The NH4-N removal rate for the control was 142.14 and 120.6 mg NH4-N/m2/day for the planted filters, while the average loading rate for the influent was 271.01 mg m-2 day and a concentration of 101.77-176.44 mg L-1 nitrate was measured in the treated effluent. In addition, meaningful reduction of fecal coliforms and streptococci was achieved, over 95%. Conclusion: The quality of treated effluents has shown that the use of post-treatment planted filters is an effective and inexpensive technology for wastewater treatment in small urban and rural communities.