Sotec Technology Helps Achieve the First Wastewater Zero Liquid Discharge in China's Sludge Sector

On June 17, the Dongguan Shatian Lishadao C-Park Sludge Centralized Treatment and Disposal Project was successfully put into full operation. This world-class sludge disposal mega-plant, with a total investment of 1.918 billion yuan and a daily treatment capacity of 2,000 tonnes of sludge (with 700 tonnes/day reserved for expansion), has achieved two domestic firsts: China's first standalone sludge incineration power generation project, and China's first sludge-sector project to achieve wastewater zero liquid discharge (ZLD). As the core service provider for the ZLD section of the project, Chengdu Sotec Technology Co., Ltd. has delivered a green solution for water resource recycling with its full suite of proprietary process solutions.

As early as May 2024, under the witness of the commerce departments of China and France, Dongguan Water Group signed a strategic cooperation agreement with France's SUEZ Group to establish this world-class centralized sludge treatment facility — a landmark project in bilateral energy transition and green and low-carbon cooperation. Covering an area of 132.95 mu (about 8.86 hectares) and equipped with five incineration production lines, the plant will achieve 100% harmless centralized disposal of sludge from over 50 wastewater treatment plants across Dongguan upon full operation. It will generate 96 million kWh of electricity annually, reduce carbon dioxide emissions by 55,000 tonnes per year, and achieve a power self-sufficiency rate of over 50%. All incineration ash is fully recovered and used as raw material for cement and building materials, forming a complete closed-loop circular economy system and providing solid support for Dongguan's "Zero-Waste City" initiative.

The desulfurization wastewater generated during sludge disposal is characterized by high salinity and high pollutant concentrations, making it extremely difficult to treat — a long-standing environmental pain point in the industry. In 2024, Sotec Technology successfully won the bid for the full ZLD section of this project, adopting the process train of "equalization tank + coagulation sedimentation + quartz sand filtration + ultrafiltration (UF) + DTRO" to ensure that effluent quality meets high standards. The concentrate is further treated via evaporation and drying technology to efficiently manage high-concentration wastewater, achieving zero liquid discharge. Once the entire system operates stably, the project will recycle 400,000 cubic meters of reclaimed water annually, making all in-plant production water fully self-sufficient — truly realizing full-process wastewater ZLD in the sludge industry, filling a technological gap in domestic sludge incineration closed-loop water treatment, and establishing a replicable and scalable "Guangdong Model" for the industry.

From groundbreaking in March 2024 to successful commissioning in June 2026, over 786 days, Sotec Technology provided full-chain one-stop services covering process design, equipment supply, installation and commissioning, integrated trial operation, and operational maintenance support. To address engineering challenges such as cross-construction interfaces, tight schedules, and high system integration requirements, the engineering team remained on-site throughout, precisely coordinating with the main incineration construction schedule to ensure that the ZLD system was commissioned, put into production, and met compliance standards simultaneously with the main incineration lines, fully guaranteeing the project's successful passage through all environmental acceptance checks.

Sludge reduction, resource recovery, and low-carbon treatment are core development directions for the solid waste and environmental protection industry, and wastewater ZLD is a hard-core mandatory indicator for green factories and zero-waste facilities. The successful implementation of this benchmark project in Dongguan represents a significant achievement for Sotec Technology's ZLD technology in the large-scale municipal sludge incineration sector, fully validating the company's process adaptability, large-scale implementation capability, and long-term operational reliability. Looking ahead, Sotec Technology will continue to iterate its core water treatment technologies, leveraging the practical experience gained from this global benchmark project to provide full-chain ZLD solutions for sludge disposal and solid waste comprehensive utilization projects in cities across China, contributing robust environmental technologies to the national "Zero-Waste City" initiative and the realization of the carbon peaking and carbon neutrality goals.