Textile wastewater treatment and reuse through integrated electrocoagulation and carbon assisted aerobic bioprocesses

Textile wastewater, marked by high chemical oxygen demand (COD), intense colouration, and highly variable composition, poses significant treatment challenges that hinder effective remediation and restrict water reuse potential. This study investigates an integrated treatment strategy that combines electrocoagulation (EC) with aerobic biological treatment assisted by carbon-based materials (CBMs), for the effective removal of dyes and other organic contaminants from real textile effluents. Two types of EC pretreatment, using aluminium and iron electrodes, were evaluated, followed by aerobic treatment with activated sludge without and supplemented with activated carbon (AC) or carbon nanotubes (CNTs). Results demonstrated that CNTs significantly enhanced the efficiency of biological treatment, achieving higher COD and colour removal compared to AC or treatments without CBMs, particularly for effluents pretreated with iron electrodes. Upscaled experiments using the optimized EC-CNT-assisted aerobic process produced an effluent suitable for reuse in textile dyeing: COD < 120 mg O2 L−1 and colour < 20 Pt-Co. Laboratory-scale dyeing trials confirmed that effluent reuse at effluent-to-tap water ratios up to 75% did not compromise fabric colour uniformity or quality. Although salinity and chloride levels remained slightly above recommended thresholds, these parameters can be adjusted during subsequent textile processing. Overall, the integration of EC with CBMs-assisted aerobic treatment provides a flexible and sustainable strategy for textile wastewater management, enabling effective pollutant removal and facilitating water reuse, thereby contributing to circular water practices in the textile industry.