Enhanced tannery wastewater remediation using a synergistic Bacillus licheniformis and Auxenochlorella pyrenoidosa consortium

Abstract

Tannery wastewater (TWW) contains high levels of organic and inorganic pollutants as well as heavy metals. Its complex composition necessitates adequate treatment to minimize harmful impacts on aquatic and terrestrial ecosystems and to ensure its safe reuse in crop irrigation. Conventional treatment methods, such as bacterial processes, have several drawbacks, including secondary pollutant generation and sludge formation. In this study, a bacterial and microalgal consortium comprising Bacillus licheniformis and Auxenochlorella pyrenoidosa was developed for the effective treatment of TWW and for utilizing the resulting biomass to produce value-added products. The study showed that the developed consortium was an efficient and sustainable alternative to conventional treatment methods achieving reductions in chemical oxygen demand (COD), total nitrogen (TN), phosphate, nitrite, fluoride and sulphate by 98.36%, 99.95%, by 99.57%, 98.89%, 80.88% and 99.15% respectively. GC-MS analysis confirmed the degradation of organic compounds such as mesitylene, spiro[9,9']difluorene and plumbane trimethyl(1-methylpropyl). Furthermore, toxicity reduction was evaluated on Zea mays plants and the results indicated that TWW treated with consortium significantly improved seed germination and growth parameters, suggesting potential applicability of developed bacterial-microalgal consortium for industrial wastewater treatment. This study uniquely employs GC-MS profiling to elucidate compositional changes in TWW following bacterial-microalgal consortium treatment, revealing compound-specific degradation patterns rarely explored in existing literature.