How to Treat Textile and Printing & Dyeing Wastewater

The textile and printing & dyeing industry has always been a major water user and polluter. According to statistics, the industry accounts for about 6% of total industrial water consumption, with annual wastewater discharge exceeding 2 billion tons. The wastewater contains high concentrations of dyes, auxiliaries, heavy metals, and refractory organic compounds, characterized by complex composition, high color, high toxicity, and high salinity. As environmental policies tighten and water costs continue to rise, how to efficiently treat textile printing & dyeing wastewater to achieve discharge compliance and resource recovery has become a key focus of the industry.

1. Where does textile printing & dyeing wastewater come from?

Textile printing & dyeing wastewater mainly comes from fabric pretreatment, dyeing, printing, and finishing processes. Among these, desizing wastewater from the pretreatment stage contains large amounts of sizing agents (such as PVA) and alkalis, with extremely high COD concentrations. Dyeing and printing wastewater contains dyes, auxiliaries, and surfactants, showing high color and poor biodegradability. Finishing wastewater contains resins, softeners, and other organic compounds. Due to large variations in water quality across different processes and significant fluctuations, the wastewater generally contains high concentrations of organic pollutants, deep color, and strong alkalinity, making treatment significantly more difficult than general industrial wastewater.

2. What are the mainstream treatment processes?

Currently, textile printing & dyeing wastewater treatment mainly adopts a combined process route of "physicochemical pretreatment + biochemical treatment + advanced treatment".

Physicochemical pretreatment is the first step, including screening, equalization, air flotation, coagulation sedimentation, etc., to remove suspended solids, fiber impurities, and part of the color, and to equalize water quality and flow, creating favorable conditions for subsequent biochemical treatment.

Biochemical treatment is the core step. Common processes include hydrolytic acidification + aerobic (A/O), membrane bioreactor (MBR), etc. To address the poor biodegradability of printing & dyeing wastewater, studies have developed a modified iron‑carbon micro‑electrolysis coupled with hydrolytic acidification‑anoxic/oxic (A/O) process. This enhances organic degradation through the synergistic effect of electrochemical reduction and adsorption. Continuous operation monitoring shows that this process achieves removal rates of up to 93.3% for COD, 74.4% for ammonia nitrogen, and 65.0% for color. In a practical application at a textile industrial park in Jiangsu Province, a combined process of AO/MBR + ozone catalytic oxidation + biological aerated filter (BAF) effectively solved the problems of large water quality fluctuations and poor biodegradability, with the effluent stably meeting the Class 1A standard, and the treated tail water was reused by enterprises in the park.

Advanced treatment is used to further improve effluent quality and achieve water reuse. Common advanced treatment technologies include ozone advanced oxidation, membrane separation (ultrafiltration, nanofiltration, reverse osmosis), and activated carbon adsorption. Among them, membrane separation technology can achieve high‑precision solid‑liquid separation and effectively remove residual organics and salts.

3. Cutting‑edge technologies and typical cases

In recent years, driven by technological progress and policy support, textile printing & dyeing wastewater treatment has been accelerating towards "near‑zero discharge" and "resource utilization".

At the policy level, the Ministry of Industry and Information Technology and the Ministry of Water Resources jointly released a national directory of encouraged industrial water‑related processes, technologies, and equipment in 2025, covering more than 100 water‑related processes in 13 industries including textile printing & dyeing. At the same time, a new version of the "Discharge Standard of Water Pollutants for Textile Industry" is being revised. The China Dyeing and Printing Association also held an Energy Conservation and Environmental Protection Annual Conference in March 2026, focusing on hot topics such as wastewater treatment, resource recycling, and synergistic pollution and carbon reduction.

In terms of technical practice, the dyeing MLD project of Foshan Jalida Environmental Protection Technology Co., Ltd. stands as a benchmark. This project innovatively adopted "near‑zero discharge" technology and a "single‑stage dual‑membrane method" water reuse system, successfully applying the world's first "salt separation and purification" technology for textile printing & dyeing wastewater. It treats 160,000 tons of industrial wastewater discharged daily from nearly 200 enterprises in the park, achieving water reuse of 142,000 tons per day (a reuse rate of 88.7%), and recovering 1,000 tons per day of sodium chloride brine and 200 tons per day of sodium sulfate. Thanks to its groundbreaking technological innovation, the project won the "Industrial Project of the Year" award at the Global Water Awards 2025.

In East China, the first phase of the Jiangyin Changjing No.1 Wastewater Treatment Plant, with a daily treatment capacity of 50,000 tons, achieved a reuse rate of 50% for printing & dyeing wastewater, with effluent quality meeting the strictest national standards. It successfully solved the industry pain point of "high‑concentration wastewater being difficult to degrade and low‑concentration wastewater resources being wasted".

In addition, for desizing wastewater containing refractory substances like PVA, researchers both domestically and internationally are actively exploring advanced oxidation processes (Fenton, ozone catalysis, etc.), ultrafiltration, and chemical coagulation methods to break through the bottleneck of biochemical efficiency.

4. Future development trends

Looking ahead, textile printing & dyeing wastewater treatment will continue to evolve towards "high efficiency, low carbon, and resource utilization". First, further optimization of membrane‑based integrated processes and advanced oxidation technologies will push water reuse rates towards over 90%. Second, the promotion of resource recovery technologies such as "salt separation and purification" will convert effective components in wastewater into recyclable industrial raw materials. Third, the introduction of intelligent and digital management tools will greatly improve the operational efficiency and stability of wastewater treatment plants. Synergistic pollution and carbon reduction is becoming the only path for the printing & dyeing industry to achieve green transformation.