Textile wastewater treatment by heterogeneous catalytic ozonation using microcellulose loaded ZIF 67 catalyst

The textile industry, being a significant consumer of fresh water, generates large amounts of wastewater, leading to serious environmental problems. The high levels of pollutants present in textile wastewater pose a significant risk to the environment and disrupt the ecosystem. As a result, it is essential to implement effective treatment steps to mitigate these harmful effects. This research focuses on the performance of a novel catalyst, namely microcrystalline cellulose zeolitic imidazolate frameworks (MCC@ZIF-67), in a heterogeneous catalytic ozonation process (HCOP) for the treatment of real textile effluent. The textile wastewater was characterized by a chemical oxygen demand (COD) of 490 mg/L, a 5 days biochemical oxygen demand (BOD₅) of 206 mg/L, a total dissolved solids (TDS) concentration of 3500 mg/L, and intense red color. The study investigated the influence of several parameters like ozone dose, pH, catalyst dosage, and treatment time. The experimental results showed a 79.01 % decolourization, 72.40 % COD removal, and 66.51 % BOD₅ removal after 30 min of treatment at optimum conditions of pH 9, ozone concentration 0.4 mg/min, and MCC@ZIF 67 dose of 50 mg/L. The comparison with control tests revealed the beneficial synergistic effects of HCOP with a process efficiency in the order of HCOP(O₃/MCC@ZIF-67) > O₃ > MCC@ZIF-67. Scavenging tests allowed to better support the explanation of possible degradation mechanisms. This study demonstrates the potential of MCC@ZIF-67 in the HCOP process for the effective treatment of textile effluent and, depending on the characteristics of textile wastewater and standards for effluent disposal, may serve either as standalone process, a pre-treatment for subsequent biological process or tertiary treatment.