Longfeng Gelemei Leather Wastewater Treatment Plant Phase III, Mengzhou (40,000 m³/d, Class IV surface-water effluent)

Longfeng Gelemei Fashion Co., Ltd. in Mengzhou, Jiaozuo, Henan, is one of the world's largest sheep-leather processors, handling roughly 40 million hides a year. Leather tanning is a heavily polluting process: sulphur-bearing unhairing effluent, chrome-bearing tanning liquors, degreasing wastewater, general process water, domestic sewage and stormwater differ sharply in character, and the chrome stream is a heavy-metal source in its own right. The company built Phase I and Phase II treatment plants in 2003 and 2015 with RMB 800 million of investment, and added Phase III for RMB 150 million in 2026, bringing cumulative environmental spending above RMB 1.5 billion. Scope Phase III covers 20,000 m2 with a design capacity of 40,000 m3/d. It was commissioned on 5 June 2026, World Environment Day, when Mengzhou held its main commemorative event at the site and opened the treatment facilities to local residents. Process Phase III reinforces the company's six-stream separation system: sulphur wastewater, chrome liquor, degreasing wastewater, general effluent, domestic sewage and stormwater are collected and treated separately, so that unlike pollutants never meet and compound the treatment burden. The chrome liquor runs a closed loop of precipitation, MBR membrane separation and multi-effect evaporation; chrome is fully recovered, with no chrome liquid discharged and no loss of the resource. The general stream passes through biological and advanced treatment - high-efficiency nitrification and deep denitrification - to cut COD, ammonia, total nitrogen and total phosphorus, followed by disinfection. A digital control platform ties collection, treatment, reuse and compliant discharge into one closed management loop. Performance Effluent COD, ammonia and total phosphorus consistently meet China's Class IV surface-water standard, tighter than the Yellow River basin discharge standard for Henan. Plant-wide pollutant discharge fell by more than 20% against the pre-upgrade baseline, and the water recycling rate reached 35%, saving about 1.5 million m3 of fresh water a year at current hide throughput. Chen Zhanguang, vice chairman of the China Leather Industry Association, noted that designing for Class IV surface-water quality is rare in the sector. The site also runs a 500 t/d sludge and leather solid-waste facility (pre-treatment, indirect thermal drying, dedicated incineration, heat recovery) and 440,000 m2 of rooftop PV generating over 30 million kWh a year - three closed loops spanning water, solids and energy. Note: the detailed process train of the advanced stage was disclosed by the design and equipment supplier; this case only restates figures verifiable in Economic Daily and China Leather Industry Association releases. Sources: Economic Daily, "Mengzhou, Henan Delivers a Win-Win Scorecard for Economy and Ecology", 8 June 2026, https://www.jingjiribao.cn/static/detail.jsp?id=661844; China Leather Industry Association (published via leather365.cn), "World Environment Day: Longfeng Gelemei Wastewater Treatment Plant Phase III Commissioning Ceremony", 10 June 2026, http://www.leather365.cn/index/index/news_info/aid/19384.html Image: aerial view of the Longfeng Gelemei Phase III plant, new circular clarifiers and biological tanks in the foreground (Source: Economic Daily, company photo)