Urban reclaimed water reuse

I would like to know information on this aspect as well.

Code, Item, Standard: 1. Color – Chroma not exceeding 40 degrees; 2. Odor – No unpleasant smell; 3. pH – 6.5–9.0; 4. Suspended solids – Not exceeding 10 mg/L; 5. Biochemical oxygen demand (5 days at 20°C) – Not exceeding 10 mg/L; 6. Chemical oxygen demand (potassium dichromate method) – Not exceeding 50 mg/L; 7. Anionic synthetic detergents – Not exceeding 2 mg/L; 8. Total bacterial count – Not more than 100 per 1 ml of water; 9. Total coliforms – Not more than 3 per 1 liter of water; 10. Free residual chlorine – Not less than 0.2 mg/L at the end of the distribution network. You might also want to take a look at this: Reuse of urban wastewater – Quality standards for urban non-potable water, GB/T 18920-2002. Water used in industrial processes includes things such as recycled water, fire-fighting water, water used for coal washing, and concrete production; the specifics depend on the company in question! ! ! This post was last edited by johncom on 2009-4-9 07:58]

After treatment, the reclaimed water in cities must meet the relevant standards set for pollutant emissions in urban sewage treatment plants. When this water is reused for various purposes, it must also comply with the appropriate standards; for example, when used for flushing toilets, landscaping, or car washing, it must meet the standards applicable to recycled urban wastewater for such uses. If it is used in concrete mixing, then it must satisfy the standards for water used in concrete production

Reuse of urban sewage – Water quality for non-potable urban uses – GB-T18920-2002; Water quality for landscape and environmental use – GB-T18921-2002. Standards for controlling the quality of reclaimed water: The quality standards for reused reclaimed water are based on the Class A standard set for wastewater treated by urban sewage treatment plants. In China, wastewater treatment is divided into three levels; depending on the environmental functions and protection objectives of surface water bodies to which wastewater from urban sewage treatment plants is discharged, as well as the treatment processes used in these plants, the standard values for conventional pollutants are classified into Class 1, Class 2, and Class 3 standards. The first-level standard scores are further divided into A standard and B standard. Standard A of the first-level standards represents the basic requirements for wastewater from urban sewage treatment plants to be used as recycled water. When the effluent from wastewater treatment plants is discharged into rivers and lakes with limited dilution capacity for use as urban landscape water and general recycled water, Standard A of the first-level standards is applied. Standard A of the first-level standards is the strictest. The specific values are shown in the table below. Sequence Number | Basic Control Parameters | Standard A | Standard B | Second-level Standards | Third-level Standards
1 | Chemical Oxygen Demand (COD) | 50 | 60 | 100 | 120①
2 | Biological Oxygen Demand (BOD5) | 10 | 20 | 30 | 60①
3 | Suspended Solids (SS) | 10 | 20 | 30 | 50
4 | Animal and Plant Oils | 1 | 3 | 5 | 20
5 | Petroleum Products | 1 | 3 | 5 | 15
6 | Anionic Surfactants | 0.5 | 1 | 2 | 5
7 | Total Nitrogen (in N) | 15 | 20 | – | –
8 | Ammonia Nitrogen (in N)② | 5 (8) | 8 (15) | 25 (30) | –
For facilities constructed before December 31, 2005: 1 | 1.5 | 3 | 5
9 | Total Phosphorus (in P) | For facilities constructed from January 1, 2006 onwards: 0.5 | 1 | 3 | 5
10 | Colority (dilution factor) | 30 | 30 | 40 | 50
11 | pH | 6–9
12 | Coliforms per liter | 10³ | 10⁴ | 10⁴ -

Urban reclaimed water has specific water quality standards, which are already mentioned; there’s no need to go over that again. Speaking of the industries that use reclaimed water, it is most commonly used for irrigation purposes and for washing cars. It is also utilized as water in industrial cooling systems; however, since such systems have requirements regarding salt content, the water must be treated first. Furthermore, reclaimed water can be used, after disinfection, as supplementary water for landscaping, for use in rivers, and for cleaning surfaces. Many cities have begun to use reclaimed water for flushing toilets as well. Reclaimed water has a wide range of applications; with further treatment, its uses can become even broader. Especially in modern society where water resources are becoming increasingly scarce, advances in technology will lead to an expansion of the applications of reclaimed water.

Quality standards for reclaimed water: These are based on the Class A standard for wastewater treatment and discharge from urban sewage treatment plants. In China, wastewater treatment is divided into three levels; depending on the environmental functions and protection objectives of surface water bodies to which wastewater from urban sewage treatment plants is discharged, as well as the treatment processes used in these plants, the standard values for conventional pollutants are set at three levels: Class 1, Class 2, and Class 3. The first-level standard scores are further divided into A standard and B standard. Standard A of the first-level standards represents the basic requirements for wastewater from urban sewage treatment plants to be used as recycled water. When the effluent from wastewater treatment plants is discharged into rivers and lakes with limited dilution capacity for use as urban landscape water and general recycled water, Standard A of the first-level standards is applied. Standard A of the first-level standards is the strictest. The specific values are shown in the table below. Sequence Number | Basic Control Parameters | Standard A | Standard B | Second-level Standards | Third-level Standards
1 | Chemical Oxygen Demand (COD) | 50 | 60 | 100 | 120①
2 | Biological Oxygen Demand (BOD5) | 10 | 20 | 30 | 60①
3 | Suspended Solids (SS) | 10 | 20 | 30 | 50
4 | Animal and Plant Oils | 1 | 3 | 5 | 20
5 | Petroleum Products | 1 | 3 | 5 | 15
6 | Anionic Surfactants | 0.5 | 1 | 2 | 5
7 | Total Nitrogen (in N) | 15 | 20 | – | –
8 | Ammonia Nitrogen (in N)② | 5 (8) | 8 (15) | 25 (30) | –
For facilities constructed before December 31, 2005: 1 | 1.5 | 3 | 5
9 | Total Phosphorus (in P) | For facilities constructed from January 1, 2006 onwards: 0.5 | 1 | 3 | 5
10 | Colority (dilution factor) | 30 | 30 | 40 | 50
11 | pH | 6–9
12 | Coliforms per liter | 10³ | 10⁴ | 10⁴ -

Each issue should be analyzed on its own; industrial water and domestic water have their respective characteristics. It cannot be generalized and mixed together

It’s not entirely clear yet, but it’s a good approach. Hasn’t someone suggested recycling urban rainwater? I think this method is quite good – there are too many impurities in domestic water! ! !

Will using reclaimed water for cooling purposes prevent an increase in the concentration ratio?