Biotechnological strategy for tannery wastewater treatment: Bicarbonate/H2O2 oxidation integrated with microalgae cultivation

Abstract

This study proposes a biotechnological strategy integrating an advanced oxidation process based on bicarbonate/H₂O₂ (BAP) with microalgae cultivation to simultaneously address tannery wastewater treatment and resource recovery. The key innovation lies in combining the BAP system with the growth of Chlorella sp., enhancing both wastewater quality and biomass production enriched with valuable metabolites. Under optimal conditions (H₂O₂: 0.2 M, sodium bicarbonate: 0.179 M, 63 °C, pH 5.3, reaction time: 1 h, reactor volume: 2 L, agitation: 550 rpm), the BAP system achieved 95.4 % removal of N–NH₄, 56 % color reduction, and 55–75 % removal of COD, TOC, and BOD. This pretreatment not only improved the biodegradability and reduced the toxicity of the effluent but also provided a more suitable medium for microalgal cultivation. In this context, Chlorella sp. exhibited a significant increase in biomass production (1.86 g L⁻¹) and growth rate (0.13 d⁻¹) compared to controls in untreated media. Furthermore, the integrated system enhanced the accumulation of lipids and proteins in the biomass, emphasizing its potential as biofertilizer and feedstock for biofuels. This interdisciplinary approach offers an effective and sustainable solution for the remediation of complex effluents while promoting circular economy principles by recovering valuable resources. It stands as an innovative environmental technology model with industrial and societal impact.