Treating manufacturing effluent

Effluent arising from STM is heavily contaminated with oil and grease, organic material, salts and heavy metals. The 'Eco-efficient management of water in the manufacturing industry' (ECOWAMA) project developed a new method for treating wastewater from the STM industry.

Each year, metal finishing and coating operations in Europe use over 100 million cubic metres of water for cleaning surfaces and as a basis for galvanic solutions. The ECOWAMA project is devising a chemical-free closed-loop process that will create zero emissions. This cost-effective and sustainable approach combines wastewater treatment with the recovery of extremely pure water, valuable metals and energy.

An innovative system is being developed using electrocoagulation, electro-oxidation and electrowinning technologies. Hydrogen produced during the electrocoagulation/electro-oxidation processes will be used in fuel cells to generate electricity, thereby reducing energy demand for the entire process.

Heavy metals will be separated from wastewater using an electro-precipitation process. A new electrowinning process will use novel electrodes to reclaim the metals at a high level of purity, which can be sold or reused in STM operations.

Researchers also developed and adapted pulsed field technology and adapted it to the STM effluent. In addition, multi-stage humidification–dehumidification technology was included as a post-treatment step and as a method for concentrating diluted wastewater streams before electrolytic treatment.

The success of ECOWAMA will encourage the acceptance and wider use of electrochemical and physical wastewater treatment in industry as a 'green' alternative to standard processes. It will reduce water consumption, increase energy efficiency, avoid the use of hazardous chemicals and help recover valuable materials. It will also help Europe to compete in the STM global market through its focus on environmentally friendly wastewater treatment.