Post-treatment wastewater at factories, production, business and service establishments and dedicated wastewater treatment plants needs to be reused, reducing production costs and improving the environment and climate.

Functional units check the quality of treated wastewater before being reused for watering plants and regulating climate at a resort in Ngu Hanh Son District, Da Nang. Photo: HOANG HIEP

Within the framework of the project ‘Join hands to protect water resources’ funded by the United States Agency for International Development (USAID), the Centre for Environmental and Community Research (CECR), the Viet Nam Water Conservation Network Nam (VIWACON) and the Ha Noi and Da Nang universities of Science and Technology are joining forces to promote wastewater reuse initiatives in businesses to approach the circular economy.

The aforementioned units have installed a demonstration system to reuse treated wastewater with a water use capacity of 10m3/day at a resort in Ngu Hanh Son District to water plants and vegetation in the resort. At the same time, a similar system with a capacity of 15m3/day has also been installed at the seafood processing factory of Thien Ma Company Limited in Son Tra District-based Tho Quang Seafood Service Industrial Park for irrigation and the clean-up of the factory.

After a period of installation, testing and technical adjustment, the quality of reused water meets the set requirements and is economical, reducing wastewater treatment costs and resource use tax, underground water exploitation costs and the amount of tap water used by the enterprise as well.
Water reuse (also commonly known as water recycling or water reclamation) reclaims water from a variety of sources then treats and reuses it for beneficial purposes such as agriculture and irrigation, potable water supplies, groundwater replenishment, industrial processes, and environmental restoration.

Director of Thien Ma Company Limited Le Van Vuong said: “Currently, the company is reusing treated wastewater for cleaning, floor irrigation, factory cooling and other purposes and is researching the use of cooling water for freezing and air-conditioning systems. The reuse of water brings many benefits, so we also look forward to studying to increase the capacity of the plant to reuse the entire wastewater after treatment every day”.

At some resorts, the volume of wastewater generated from daily activities of tourists is very large, mainly from bathing, washing, water discharge from swimming pools. The wastewater is treated at in-resort standard wastewater treatment systems and then is discharged into the city's wastewater collection system to make its way to the city’s centralised treatment stations before being discharged into the environment.

As reported by D.Ph Nguyen Dinh Huan, Dean of the Faculty of Environment, the Da Nang University of Science and Technology, through surveys at resorts, hotels, manufacturing and processing factories in the city, many businesses want to reuse wastewater after treatment and they are in need of technical and professional support for waste water reuse. This will help businesses gain economic benefits such as reducing monthly water bills and wastewater treatment fees. The system to reuse treated wastewater is highly feasible and environmentally meaningful.

Director of the Office of SEEN Engineering JSC in Da Nang Pham Van Thuan affirmed that the cost of recycling and reuse of wastewater is getting lower and lower due to the significantly improved treatment technology, which is suitable for replenishing water for many purposes.

Da Nang has invested a lot in building a widespread wastewater collection and treatment system with a total daily wastewater treatment capacity of nearly 350,000m³. Treated wastewater is an extremely valuable resource and has great potential for reuse. In the dry season, the water level of lakes and canals is usually lowered, causing environmental problems, especially the situation of dead fish and the release of bad odors into the environment.

Based these facts, it is a need to pump post-treatment wastewater reserves with a total daily capacity of nearly 350,000m³ to the upstream of canals and lakes to create circulating water, ensure the environment and regulate the climate.

For the time being, more than 88% of urban domestic wastewater in the city has been collected and treated. Besides, 100% of the wastewater discharged from industrial zones is collected, treated and monitored automatically and continuously.

The Da Nang Department of Natural Resources and Environment is coordinating with domestic and foreign organisations on conducting research and technology transfer of wastewater reuse from domestic and industrial wastewater treatment stations as well as post-treatment wastewater reuse solutions, as well as to operate water circulating systems at factories, businesses and service establishments.

Reporting by HOANG HIEP - Translating by A.THU