Integrated anaerobic reactor and intermittently aerated constructed wetland for enhanced textile wastewater treatment

Abstract

The potential of the sequential anaerobic-intermittent aerobic system for treating real textile wastewater was investigated at a pilot scale. The intermittent aerated reactor consisted of an intermittently aerated constructed wetland (CW) connected in series with an anaerobic reactor. The volumetric ratio of textile to domestic wastewater (77:23) was used in the pilot system. The treatment temperature in the anaerobic reactor was controlled at 35 ± 2 °C, and the initial pH was in the range of 7.5–8.5, which resulted from mixing the textile and domestic wastewater. The highest chemical oxygen demand (COD) removal observed in the anaerobic reactor, nonaerated CW and intermittently aerated CW were 65.0 %, 87.6 % and 90.4 %, respectively. The highest decolourization rate achieved for the pilot system after the anaerobic reactor was 82.5 %, and after intermittent aeration in the CW was 86.5 %. On the other hand, the highest colour removal achieved for the wastewater that went through nonaerated CWs was 84.5 %. The biodegradation of dyes and their corresponding biodegradation byproducts was analysed via GC–MS. The pilot-scale system showed enhanced dye degradation. The aromatic amines detected after anaerobic treatment were not detected after intermittent aerated or nonaerated CWs. There was a continuous removal of hydrocarbons throughout the treatment system. 100 % removal efficacy of nitrates and ammonia was observed in the pilot system. However, phosphate removal was observed to be very low. The pilot system was found to be very effective in removing colour, COD, aromatic amines, ammonia, and nitrates.