The project achievement is the heavy metal recovery technology with electrochemical method as the core. The concentration of heavy metals in the effluent can be up to the requirements of Emission Standard of Pollutants for Copper, Nickel, and Cobalt Industry (GB25467-2010). Heavy metals (nickel, copper, zinc, etc.) are recovered in elemental state, and no hazardous waste shall be produced, thus avoiding secondary pollution. With advanced technology and low investment, the project is suitable for the treatment of heavy metal wastewater such as electroplating, metallurgy and hole sealing, and can yield striking economic benefits.

The procedures of the project achievement consist of pretreatment, precipitation, filtration, dissolution, electrodeposition and other procedures. For different heavy metal-containing wastewater, the operation units of each step can be modularized and combined, and each operation unit can be put in one set of control system. Through this treatment system, all types of metal simple substances can be acquired from heavy metal-containing wastewater, and the purity can satisfy the relevant requirements of national standards. The residual liquid after electrochemical treatment returns to the system to achieve closed circulation, and the wastewater can be discharged in line with the standards. The key parameters (pressure, pH, temperature, voltage, current, conductivity) of the major equipment are monitored online, and the entire system is controlled with PLC and equipped with fault alarm function. After equipment commissioning, remote monitoring and unattended operation can be fulfilled in normal and routine operation. A large number of heavy metal-containing wastewater and sludge are produced every year in China's mining, electroplating, metallurgy and metal processing industries, which have not only polluted and endangered the environment, but wasted precious metal resources. The project achievement can convert heavy metals in wastewater, waste residue and sludge containing heavy metals into high-purity metal elements. The advantages of this technology include safety and environmental protection, no secondary pollution, high product value, convenient storage, small occupied space of equipment, automatic operation and the like. This technology turns waste into wealth in the course of wastewater treatment, and it can reap economic benefits while discharging wastewater in line with the standards. Both production enterprises and environmental protection companies are surely willing to transform and apply the project achievement in order to get more economic benefits. Thus, the project achievement boasts broad application prospects and market space.

The project achievement has been applied to the treatment of nickel-containing wastewater in the hole sealing workshop of a cosmetics company in Tianjin. After electrochemical treatment where nickel is recovered the water enters the biochemical wastewater treatment system. Total nickel in wastewater is classified as the first type of pollutants in the National Integrated Wastewater Discharge Standard, which requires a controlled concentration lower than 1.0 mg/L at the discharge port of workshop treatment device. With the wastewater treatment device and taking into account the operation cost, the value of recovered nickel and the saved treatment cost of nickel-containing sludge, etc., the comprehensive treatment cost per ton of wastewater saved can reach 1,100 yuan, which eliminates the hazards of nickel to local water environment and people's health, and yields striking environmental, economic and social benefits.

Intellectual Property Rights and Awards:

This project has acquired 1 utility model patent: an electrochemical system for treating nickel-containing wastewater, patent number: ZC201520166361.3 (authorized) and 1 invention patent: an electrochemical treatment system and electrochemical method for treating nickel-containing wastewater, application number: 201510127982.5.

Moreover, the project has been awarded the Bronze Award of "Invention and Entrepreneurship Award • Project Award" in the 9th International Exhibition of Inventions, and has been successfully applied to the treatment of nickel-containing wastewater in foreign-funded enterprises.

Recycling Treatment Device of Heavy Metal Wastewater