Performance assessment of a puf integrated anaerobic bioreactor for textile effluent decolourization along with lab to pilot scale transition and toxicity assessment

Biological remediation of dye-rich textile effluents remains challenging, as these compounds exert toxic, mutagenic, and carcinogenic impacts on humans and aquatic organisms. To address this, a polyurethane foam (PUF) integrated anaerobic bioreactor was designed and subsequently scaled up to facilitate textile effluent decolourization and detoxification. The lab-scale bioreactor optimized with 24% (w/v) PUF packing rate exhibited superior performance over suspended growth bioreactors, achieving 85.2 ± 9.5% color and ~ 73% turbidity removal within 72 h. Furthermore, successful scale-up to a 200 L pilot-scale bioreactor operated continuously for 71 days under real industrial conditions validated the system’s robustness, sustaining color and COD removal efficiencies of 76 ± 6.7% and 71.9 ± 4.5%, respectively. Scanning electron microscopy (SEM) confirmed dense microbial biofilm formation on PUF after 28 days, indicating effective surface colonization and biomass retention. Toxicity assessment of treated samples from pilot-scale bioreactor showed substantial detoxification, with Lemna minor growth inhibition reducing from 98–100% in untreated effluent to 65–70% in treated samples. Likewise, seed germination assay showed an improvement in growth germination index (GGI%) from 3–5% (in untreated samples) to 75%, 58%, and 20% for treated samples using Vigna radiata, Cicer arietinum, and Lactuca sativa seeds, respectively, which reasonably confirmed the detoxification of treated effluent. Overall, the PUF integrated anaerobic bioreactor exhibited promising decolourization, COD removal, and toxicity reduction. However, incorporation of further aerobic polishing unit can remove residual COD and toxicity to a greater extent.