Batik dye wastewater treatment: A comprehensive review

Batik wastewater is a significant environmental concern due to its high pollutant load, including dyes, heavy metals, and organic compounds. This review comprehensively examines various treatment technologies, focusing on physical, chemical, and biological approaches, along with sustainable and green alternatives. Physical treatments, such as nanofiltration, have achieved up to 99% dye removal, while ultrafiltration membranes blended with polyvinylidene fluoride (PVDF) have demonstrated chemical oxygen demand (COD) and total suspended solids (TSS) reductions of over 80%. Chemical treatments, including electrocoagulation with aluminium electrodes, have reduced colour by 96.45% and COD by 60%, whereas natural coagulants like Moringa oleifera seeds achieved TSS removal of 84.47%. Biological methods, such as sulphate-reducing bacteria (SRB) bioremediation, demonstrated 94% chromium removal, while fungal decolourization using Trichoderma yunnanense and Aspergillus tamarii achieved 96.3% and 96.89% dye removal, respectively. Green technologies, such as TiO₂/activated carbon photocatalysis, have successfully degraded over 90% of dye pollutants, while biochar-based adsorbents have exhibited heavy metal removal efficiencies exceeding 85%. Integrated approaches, such as up flow anaerobic reactors (UAR) combined with horizontal flow subsurface constructed wetlands (HFSCW), have achieved COD and BOD removal efficiencies of 94.3% and 94.5%, respectively. This review highlights advancements in treatment strategies explores future directions toward sustainable and cost-effective solutions for batik wastewater treatment.