[A-GE28] Energy-Environment-Water Nexus and Sustainable Development

[AGE28-P04] Potential of Microalgal Bacterial Granular Sludge (MBGS) in Polishing and Detoxifying Anaerobically Treated Textile Effluent

*VIVEK KUMAR NAIR^1,2, POOJA GHOSH², ANUSHREE MALIK² (1.School of Interdisciplinary Research, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India., 2.Centre for Rural Development and Technology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, 110016, India.)

Keywords:Textile wastewater , Textile Industry, Microalgal Bacterial Granular Sludge, Phytotoxicity

Textile industries are major contributors to environmental pollution, producing vast amounts of hazardous dye-laden effluent in their unit operations. Anaerobic treatment is a viable option for treating raw textile wastewater, but it can generate harmful intermediate chemicals, excessive turbidity along with residual COD in their treated effluent. Polishing these effluents with aerobic treatment processes like conventional activated sludge treatment also has some limitations which includes its poor settleability, high energy requirement, and generation of waste-activated sludge. To address these issues, this study applied a sustainable and alternative treatment technique, the microalgal bacterial granular sludge (MBGS) process, to polish and detoxify anaerobically treated textile effluent (AnTTE). MBGS system functions on the principle of utilizing photosynthesis for self-aeration, replacing the need for external aeration and the phenomenon of microbial assimilation act synergistically to remove pollutants from wastewater. The resultant algal bacterial granules formed in the MBGS process enhance the settling efficiency, thus promoting easy harvesting and resource recovery from the surplus biomass. In this study, the application of MBGS for the polishing of AnTTE was explored through a batch scale study conducted in a 1L jar at a light intensity of 100 μmol/m²/s with 24:0 light-dark cycle and 60 rpm rotation. The present study demonstrated that after 48 hrs. of continuous operation, MBGS was able to efficiently remove 100% Nitrate, 100% Phosphate, 94% Ammoniacal Nitrogen, 85% Turbidity, 60% sCOD, and 50% residual color from the AnTTE. Additionally, MBGS had excellent settleability with a Sludge Volume Index (SVI) of 27. The phytotoxicity potential of the MBGS polished AnTTE was also evaluated through a seed germination inhibition assay using Lactuca sativa seeds. The result of the assay demonstrates that MBGS polished AnTTE had a relative seed germination, relative root development, and germination index of 96%, 96%, and 93%, respectively. This study for the first time demonstrates the effectiveness of the MBGS process in polishing and detoxifying AnTTE, making it a sustainable alternative to the conventional aerobic treatment methods.