Printed circuit board (PCB) wastewater treatment

From July to August 2014, Tongji University made a survey on typical sewage treatment process in South China including Zhejiang Province, Jiangsu Province, Hubei Province, Guangdong Provinces, Shanghai Municipality and Guangxi Autonomous Region and then issued a report entitled "Typical Wastewater Treatment Technologies in the South of China", and introduced some mainstream wastewater treatment technologies used in South China.

The survey report is mainly about industrial and municipal wastewater treatment, sludge treatment and disposal, and sewage treatment equipment. The purpose of this survey is to identify the appropriate technologies which have potential to be adopted in African countries and other developing countries.

Printed circuit board (PCB) wastewater treatment: activated sludge + membrane bioreactor (MBR) process

Printed circuit board (PCB) wastewater usually contains high concentration of heavy metals, COD and some other pollutants. The integration of activated sludge and membrane bioreactor (MBR) could be used to treat this kind of wastewater, which could reduce the concentration of COD effectively by microbial degradation as well as heavy metals by membrane filtration.

Application scope：The designed capacity is approximately several hundred cubic meters per day.

Condition：As one of biological treatment, activated sludge process requires appropriate temperature and pH value (generally 6~9) to meet the basic living needs of microorganisms; the BOD/COD should not be too low to make sure that enough biodegradable organics are supplied; there should not be too much toxic materials.

Advantage：This method utilizes both activated sludge and MBR process, which could achieve great performance on COD and heavy metal removal. The effluent is of great quality.

Disadvantage：The cost of this process is high: to remove heavy metal in wastewater efficiently, large volume of agent should be added. In addition, the membrane needs to be washed periodically.

Investment and operating cost: The investment is typically 6000 Yuan/m3, the electricity consumption is 0.6kWh/m3 and cost on agents 7~12 Yuan/m3.

Case：Wastewater treatment project of PCB Company in Dongguan

The company has established a specialized sewage treatment plant in which sewage generated from the production process is treated. Activated sludge and MBR technology is used in the plant, mainly dealing with Cu, Ni, and COD and other pollutants. Approximately 1-2 tons of sludge is produced per day, which is dewatered and transported to a special department to be treated. Sludge treatment and disposal costs about 1000 Yuan/ton, PAM needs to be added when the sludge is dewatered.