The efficiency and capabilities assessment of some local materials in wastewater treatment using the multi soil layering

چکیده مقاله

Releasing the effluents of urban wastewater treatment plants (UWTP) downstream especially in populated areas, can negatively affect the surface water, groundwater quality. A new method, Multi soil layering (MSL) ecotechnology introduced last few decades, a cost-efficient treatment system can reduce those negative issues. In this study, three MSL systems were developed to UWTP effluent released in environment. Zeolite and for the first time silica materials were used in the permeable layers. Clay soil and for the first time waste stone powder from the stone factory with iron filing, sawdust and charcoal were used in soil mixture layers to investigate the ability of different friendly materials on the pollutant removal rate in the MSL ecotechnology. The material properties were determined using X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, contact angle measurement, surface roughness analysis, Thermogravimetry (TG) and Fourier-transform infrared spectroscopy (FTIR) analyses. The results proved the performance of MSLs and the effectiveness of the materials used. The highest removal rates of COD and BOD5 were 67.5% and 80% respectively in MSL-1 system, while PO4 3- and NO3- were 99% and 80% respectively in MSL-3 system. Result showed MSL system could reduce metal ions Cr6+, Pb2+ and Hg2+. The results also indicated that a lower contact angle or higher surface roughness does not necessarily imply better wettability and consequently better treatment performance of the materials.