Low price, low installation costs, do not use any chemicals are the advantages of the method of wastewater treatment that natural circulation of scientists at the Center for Environmental Protection and Safety chemical (Chemical Industry Institute) successfully deployed in Hanoi.

In the future, this method will be applied in the wastewater at the Lake of the capital. In 2004 marked a milestone when Centre for Environmental Protection and Chemical Safety, International Centre for Environmental Technology Transfer and Toyo Denka Co. (Japan) to wastewater treatment systems by natural circulation method (NCSWT) has a maximum capacity to work successfully 60m3/ngay night at Cau Dien. The principle of the system based on the activity of microorganisms available in natural to decompose organic compounds to clean wastewater. Therefore, most of the materials used in the system are of natural origin in the operation and do not use chemicals. The system can handle the high efficiency of organic pollutant degradation, compounds of nitrogen, phosphorus, surface-active substances, bacteria, suspended solids, color and odor are in wastewater. That shows that this technology is very suitable for the treatment of domestic wastewater and some industrial wastewater. According to data analysis, the average treatment effect of certain substances after the treatment at Cau Dien shows the environmental indicators of water equivalent to the system is operating in China, Thailand and Japan . NCSWT cost wastewater treatment was lower than some of the technology in operation. If the wastewater treatment system at the Tri City Vietnam (Phu Tho), Confectionery Company Trang An, Bien Hoa Industrial Zone II has cost more then the NCSWT VND/m3 4000, cost only about 1200 VND/m3 to 1400 and still the quality of treated water to reach A. Besides, by NCSWT not use chemicals in processing and construction investment costs low, the cost of system maintenance is very small (about 10 to 15 years to replace the materials handling), operating cost is basically the cost of energy for the blower so the technology is quite suitable NCSWT context of Vietnam. From the results of successful testing, the team of researchers have proposed plans to apply NCSWT clean river water, polluted lake in Hanoi. Initially, the Center for Environment and Chemical Safety proposes three plans for handling the Lich river - the reception of urban waste water from residential areas, wastewater from the production facilities. In the future, systems will contribute to cleaning NCSWT water rivers, lakes, improve the quality of surface water, beautify the landscape and environment of urban residents and rural Vietnam.

(Source of Natural Resources and Environment, LC – ND)