Performance evaluation of anaerobic moving bed bioreactor (An-mbbr) for pretreatment of desizing wastewater

Only a few textile mills in Pakistan have installed wastewater treatment plants, and even if installed, aerobic treatment processes are hardly operational due to high energy requirements. The performance of a pilot-scale anaerobic moving bed bioreactor was thus investigated in terms of organic removal and biogas production as a potentially energy-efficient pretreatment of real textile desizing waste-water. The pilot plant was operated under on-site conditions for 122 d at Kohinoor Mills Limited Kasur, Pakistan. The temperature of the bioreactor was in the mesophilic range of 22°C–36°C, while pH and oxidation-reduction potential were in the range of 7.7–8.0, and –580–630 mV, respectively. The volumetric organic loading rate of the bioreactor varied 0.2–2.0 kgCOD/m³/d. Almost 50% of chemical oxygen demand (COD) removal was achieved and COD conversion into biogas was 0.35 m^{3 /kgCOD}. The produced biogas had a high methane content with a specific methane production of 0.26 m^{3 /kgCOD}. The overall performance of bioreactor was marginally biogas removed methane removed improved when the system was running with low sulfate enzymatic desizing wastewater instead of oxidative peroxydisulfate-treated desizing wastewater. After further optimization overcoming unsatisfying biomass retention, high H₂ S formation, and possible inhibitory effects of detergents used in the desizing process, this technology has the potential for widespread application in the textile sector of semi-arid developing countries.