Even spilled water can be collected: from sewage to recycled water, "quenching the thirst" of the city!

Guangdong has abundant water resources and is a typical water-abundant region.

However, due to the uneven temporal and spatial distribution of water resources, droughts and water shortages occur from time to time.

How to use recycled water to quench the city’s thirst?

Effectively develop the "second urban water source"

It plays a positive role in alleviating the contradiction between water supply and demand.

1. What is recycled water?

Recycled water refers to urban sewage or domestic sewage that has been treated through appropriate regeneration processes to meet certain water quality standards and meet certain functional requirements, thus being used for beneficial purposes.

From an economic perspective, recycled water has the lowest cost.

From an environmental protection perspective, sewage recycling helps improve the ecological environment and achieve a virtuous cycle of water ecology.

2.Where does recycled water come from?

( 1 ) Primary treatment - mechanical treatment section :

The first step is to give the sewage a major cleansing. The mechanical (primary) treatment section includes structures such as screens, grit chambers, and primary sedimentation tanks, with the aim of removing coarse particles and suspended matter.

The principle of treatment is to achieve solid-liquid separation through physical methods and separate pollutants from sewage. It is a widely used sewage treatment method.

( 2 ) Secondary treatment - biological treatment of sewage:

Biological treatment of sewage belongs to secondary treatment, and its main purpose is to remove unsettled suspended solids and soluble biodegradable organic matter.

There are many types of process structures, which can be divided into biofilm method, activated sludge method, stabilization pond method, land treatment method and other treatment methods.

( 3 ) Tertiary treatment - deep treatment of water:

After secondary treatment, the water body is denitrified and dephosphorized, and then the remaining pollutants in the water body are removed by activated carbon adsorption or reverse osmosis, and ozone or chlorine is used for disinfection to kill bacteria and viruses.

The treated water is then sent into the reclaimed waterway, where it can be used to irrigate green belts, spray streets, and be used as industrial water and fire prevention water sources.

3. Use of recycled water

Although recycled water cannot be used as drinking water, it has been increasingly widely used and has become an important part of urban water resources.

( 1 ) Agriculture, forestry, animal husbandry and fishery

Farmland irrigation, afforestation and seedling raising, animal husbandry and aquaculture.

( 2 ) Urban miscellaneous

Urban greening, toilet flushing, street sweeping, vehicle washing, construction, fire fighting.

( 3 ) Industrial reuse

Cooling water, washing water, boiler water, process water, product water.

( 4 ) Landscape and entertainment use

Water for ornamental landscape environment, water for recreational landscape environment, water for wetland environment

( 5 ) Groundwater recharge

Surface spreading and water injection in the vadose zone.

In October 2022, the Ministry of Water Resources and six other departments announced a list of pilot cities for the allocation of recycled water utilization in typical areas. Huangpu District of Guangzhou City, Shenzhen City, and Dongguan City in Guangdong Province became pilot cities, promoting the expansion of recycled water utilization across the province and injecting renewable power sources into the high-quality development of the economy and society.