Wastewater Rules for Ceramic Manufacturers

Wastewater compliance for ceramic producers in China is not a matter of matching a single set of numbers. The governing framework, the Emission Standard of Pollutants for Ceramic Industry (GB 25464–2010) and its 2014 amendment, structures requirements around where the water goes and what kind of pollutant is involved.

The first distinction is between direct and indirect discharge. Direct discharge means treated effluent enters an environmental water body; indirect discharge means it first enters a municipal sewer and is sent to a wastewater treatment plant. Limits for indirect discharge are generally looser, on the premise that the treatment plant provides a second barrier. A ceramic manufacturer must therefore identify its discharge route before determining which tier of limits applies.

The second distinction concerns monitoring location. Conventional pollutants—pH, suspended solids, chemical oxygen demand, biochemical oxygen demand, ammonia nitrogen, total nitrogen, total phosphorus, petroleum substances, sulfide, and fluoride—are regulated at the enterprise’s final wastewater outlet. 

Heavy metals such as cadmium, chromium, lead, nickel, cobalt, and beryllium, together with adsorbable organic halides, are instead monitored at the workshop or production facility outlet. This is deliberate. Glazes may contain heavy metals, and if glaze-bearing wastewater were mixed with cleaner streams before testing, elevated concentrations could be diluted into apparent compliance. Monitoring at the workshop outlet requires treatment at the point where the contamination originates. 

Fluoride deserves separate attention: it can enter wastewater from clay minerals and wet scrubbing, and precipitation alone is often insufficient to meet the limit.

Two further constraints complete the picture. In areas with limited environmental capacity, stricter special emission limits apply. The standard also sets benchmark discharge volumes per unit of product; exceeding the benchmark can trigger tighter concentration requirements even if individual readings appear acceptable. 

Where local standards are stricter than the national standard, the stricter one governs, and indirect dischargers must also satisfy the receiving treatment plant’s acceptance criteria. Compliance, in short, follows a sequence: discharge route first, monitoring location second, special limits and volume benchmarks third, and the stricter of overlapping standards last.