UNITED CHEMICAL & ENVIRONMENT TECHNOLOGY CO., LTD


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Recycle waste water

Recycling waste water is one of the top concerns today, related to water use from individuals, businesses, industrial parks…

Therefore, in the following article, UCE Co., Ltd has compiled the frequently questions as well as answers to customers who have been interested in this recycle. Let’s refer!

1. Frequently questions asked about recycling waste water

Relating to the topic reuse of waste water, many questions have been raised, for example: Can the treated water of waste water system that has met the standards for discharge into the environment be reused or need to be further treated? What is the investing and operating cost? It is more expensive or cheaper than domestic water?

And so on. UCE Co. Ltd will provide some preliminary information as follows:

1.1 How is the effluent quality of waste water treatment before it should be continued being treating for re-use?

Except for situational factors as:

– Waste water treatment systems that had already designed and built redundancy or had selected suitable technology for later just to plus more step of re-use.

– Due to mandatory reuse as required by the industrial park

– Lack of water, so it must be reused

In general, the treated quality of waste water should must be good, at least or higher than the quality of surface water (QCVN 08-MT: 2015/BTNMT) or groundwater (QCVN 09-MT: 2015/BTNMT), then continue to process for reuse because the cost is also quite high.

1.2 What technology should be applied for recycle of waste water?

– In addition to the treated quality of waste water that must be met before further treatment to reuse as described above, the main focus is recyling for what purpose and its quantity, then will have a suitable technology to avoid too high costs or quality not reach.

– For the purpose, it can be based on one of the four groups that are divided into the next section of the World Health Organization ( WHO) or based on the actual demands of factory in need for each production or utility system.

– If used for factories, buildings, etc., first, quality should must reach domestic water level, then depending on each purpose, continue further specializing treatment.

– If used for domestic need, the quality must fully ensure all physicochemical, microbiological criteria according to QCVN:01-1:2018/BYT standard.

– The quality of recycle from waste water may still contain pathogens if used directly or indirectly such as food, medicine, health care, daily activities, so the quality must be closely controlled per each standard for all parameters.

Therefore, depending on the existing quality and the purpose of reuse waste water as well as its capacity to choose the appropriate treatment technology as mentioned in the following section.

recycling-waste-water-is-being-widely-applied

Recycling waste water is being widely applied

1.3 What are the investment and operating cost in recycling waste water?

– In addition to complying with registered standards, including issues related to saving water, energy, etc. that enterprises and industrial parks require when expanding product capacity, it is necessary to make statistics on the re-use water quantity because its investment and operating costs are quite high. In other words, easier to understand, the average investment and operating costs of 1 m3 from system capacity with 1 m3/h, 1m3/hr, 10m3/hr and 100m3/hr are completely different. The higher capacity, the lower investing and operating cost in unit.

– The cost per m3 unit of recycled water from the recycled large central waste water treatment station has the lowest cost due to its high capacity. However, at present, the number of the centralized treatment station for reuse is very low; mainly from the companies have high demand then themself recycling water to use in fields such as dyeing, paper, plating, metal surface treatment, painting, leather shoes…

– If the goal is to reuse waste water, as above mentioned it should be calculated and choose technology from the beginning because if it continues to be an extra step of treatment and reuse, will be much more expensive or treating river water into domestic water instead of recycling waste water

Please refer more at: Treating river water into domestic water

2. Water re-use according to the purposes classification

2.1 By World Health Organization – WHO (4 groups)

Group 1: Watering plant, cleaning roads; flush, wash toilet; supply water for fire fighting, re-landscape of rivers, landscape lakes in urban areas.

  • Quality requirements are not high.
  • Water source for further treatment and re-use: From domestic (sewage) waste water.

Group 2: Consumption for agriculture and forestry

  • It is necessary to know the quality and quantity for each specific tree.
  • Water source from treated domestic or industrial waste water, can be further treated if necessary

Group 3: Consumption for industry

  • The quality of this group is very various, depending on the industry of each factory.
  • Source of water from treated domestic or industrial waste water for further recycling

Group 4: Replenishment into groundwater

  • The quality must be at least according to groundwater standards (QCVN 09-MT:2015/BTNMT).
  • There must be monitoring and evaluation from the local state management agency to avoid pollution into groundwater

2.2 By demands of factory, company

In fact, based on water quality requirements, we have classified them into 4 groups that are related to use for production and ultility consumption for easy discussion, along with the specific requirements of each project there will be the best plan to recycle

different quality water groups of factory, company

different quality water groups of factory, company

2.3 What are common technologies for waste water reuse?

Currently, a number of technologies have been applied to reuse waste water. Which technology to be choosen will depend on the quality level of the treated waste water as well as the goals and amount of reuse? Because of depending on the type of waste water that its discharge regulations are also different, so when there are specific cases, a detailed calculation plan for investment, operation as well as quality is achieved.

The following is a general model to visualize what extra equipment and process will be required for the reuse of waste water.

overall-view-process-of-recycling-waste-water

Overall view process of recycling waste water

3. Recyling waste water for cooling tower and other purposes

It can be said that the most recycled water is used for cooling tower, followed by dyeing and grasses irrigation at large-scale golf course. The re-use of waste water for cooling towers or other purposes should be done with appropriate technology to ensure water quality as well as optimize costs.

Contact us – UCE Co. Ltd for advice on technology to reuse waste water at the lowest cost!