CN102040317B - System and method for taking and reusing water from riverway supplemented with recycling water - Google Patents

Abstract

The invention relates to a system and a method for reusing water from a river course supplied by regenerated water, belonging to the technical field of water pollution treatment. The invention adopts the combination method of reoxygenation type shore filter and nanofiltration membrane, draws water from the river channel supplied by regenerated water, and reuses various types of non-direct drinking water after purification. The reclaimed water entering the river meets the requirements of Class IV water in the Surface Water Environmental Quality Standard (GB3838-2002) (TN<10mg/L). Reoxygenation-type bank filters are set up along the river to remove some dissolved organic matter, ammonia nitrogen and other substances in the river water through microbial degradation; the water filtered out of the bank enters a two-stage nanofiltration system to remove most of the remaining organic matter, nitrate nitrogen and other substances in the water. Inorganic salts and other substances. The nanofiltration effluent can meet the requirements of the three types of groundwater quality standards, and can be used for urban landscape, irrigation, greening, urban miscellaneous and process water, etc.

Description

A system and method for reusing water from reclaimed water-fed rivers

technical field

The invention relates to a system and a method for reusing water from a river channel replenished with regenerated water, and belongs to the technical field of water pollution treatment.

Background technique

In nature, surface runoff (such as rivers, lakes, etc.) formed by atmospheric precipitation is an important part of surface water. However, it cannot be ignored that with the in-depth development of sewage resources in our country, a large amount of urban reclaimed water enters surface water bodies and becomes an important part of recharging river and lake water bodies. For example, in the urban area of Beijing, according to the plan for the utilization of recycled water, nine sewage treatment plants in the urban area will implement recycled water utilization projects, so that the recycled sewage can reach the Class IV standard of surface water (TN<10mg/L), forming the city’s second water source. Most of the recycled water will be used as replenishment for urban rivers and lakes, and some urban rivers (such as Qinghe) will all rely on recycled water for replenishment.

The organic pollutants in the river channel recharged by reclaimed water are complex, such as pesticides, medicinal compounds, endocrine disruptors, organic halogenated substances, etc., and are also rich in nutrients such as nitrogen and phosphorus. How to draw water from reclaimed water supply rivers and reuse it for various indirect drinking after purification is a very thorny and difficult problem in water pollution control.

Organic pollutants in rivers recharged by reclaimed water can be divided into natural organic matter, synthetic organic matter and their metabolites according to their sources. Natural organic matter is dominated by humic substances, which are difficult to biodegrade. Synthetic organic matter mainly includes organic matter in the effluent of urban reclaimed water plants and organic pollutants from non-point source pollution. After these organic matters have been biologically treated in sewage treatment plants and migrated in rivers for long distances, the remaining substances are also difficult to biodegrade. of.

After the water is taken from the reclaimed water supply river, it must be treated and purified before it can be reused for various indirect drinking. Most of the residual organic pollutants in river water are natural or synthetic organic substances and their metabolites that are difficult to biodegrade, and simple biological treatment methods are difficult to meet the treatment requirements. Some organic matter can be removed by activated carbon adsorption technology, but it is expensive and difficult to regenerate activated carbon. Biological aerated filter can remove some dissolved organic pollutants, but it has poor treatment effect on most natural organic matter, and the removal degree of nutrients is low. The combination of ozone oxidation technology and biological treatment technology can remove most of the organic pollutants. Foreign researchers use magnetic resin to remove natural organic matter, nitrate, sulfate, phosphate, etc. in water through ion exchange, which is an effective way to purify water from surface water bodies.

Membrane technology can effectively remove organic pollutants, which is currently a research hotspot in the world. In view of the fact that water contains a large amount of organic matter that causes membrane fouling, membrane technology usually needs to be used in conjunction with other technologies. The combination of membrane and shore filtration can give full play to the advantages of each other. Membranes can reduce the salinity of regenerated water and remove macromolecular organic matter, while shore filtration has more advantages in removing low molecular weight organic matter, and the two present a strong complementarity. The hydraulic retention time of ordinary shore filtration is short, and it is mainly used to remove suspended solids in water, and has limited effect on the removal of dissolved organic matter.

Contents of the invention

The purpose of the present invention is to provide a system and method for reusing water from reclaimed water-supplied rivers. By adopting the combination of reoxygenated bank filter and nanofiltration membrane, water is drawn from regenerated water-supplied rivers, and the purified water satisfies the The third type of groundwater water quality standard requirements, can be used for urban landscape, irrigation, greening, urban miscellaneous, process water and other non-direct drinking water.

Technical scheme of the present invention is as follows:

A system for reusing water from regenerated water supply rivers, characterized in that: the system includes a reoxygenation bank filter, a clear water tank, a flow control valve and a nanofiltration system, and the reoxygenation bank filter is set at Along the river channel, fill the sand layer in the reaerobic bank filter, and lay non-woven fabrics on the side of the bank filter near the river; the clear water pool is set between the reaerobic bank filter and the river bank, and A baffle is laid on one side of the reaerobic bank filter, and a fine mesh grid and a filter are arranged on the lower part of the baffle; the clean water pool is connected to the nanofiltration system through a pipeline and a flow control valve.

The technical feature of the present invention is that the nanofiltration system is composed of a first-stage nanofiltration system and a second-stage nanofiltration system connected in series. The height of the fine grid is less than or equal to 1/5 of the height of the reaerobic bank filter. The grain size of the sand layer in the reoxygenation type shore filter is 0.5-3.0mm, and the height of the sand layer exceeds the water surface by 0.1-0.5m.

The present invention provides a method for reusing water from a river channel replenished with regenerated water, which is characterized in that the method comprises the following steps:

1) Except for the condition of TN<10mg/L, the reclaimed water entering the river from the reclaimed water plant shall meet the requirements of Class IV water in the surface water environmental quality standard GB3838-2002;

2) A reoxygenation type bank filter is installed along the river. After the river water enters the bank filter through the non-woven fabric, it uses microbial degradation to remove part of the dissolved pollutants, and then enters the clear water pool after being filtered by a fine mesh grid and a filter in turn. ; Reoxygenation shore filter filtration rate ≤ 1m/day, hydraulic retention time ≥ 1 day;

3) The water from the clean water tank enters the nanofiltration system through the flow control valve.

In the above method, it is also characterized in that: the water coming out of the clear water tank first enters the first-stage nanofiltration system through the flow control valve to remove organic matter, nitrate nitrogen and inorganic salts in the water, and then enters the second-stage nanofiltration system system to further remove residual nitrate nitrogen, inorganic salts, and residual organic matter; the concentrated water from the nanofiltration membrane of the second-stage nanofiltration system returns to the first-stage nanofiltration system to continue water production; the nanofiltration membrane in the first-stage nanofiltration system The filter membrane is an aromatic polyamide composite nanofiltration membrane with a molecular weight cut-off of 150-300 and a stable desalination rate of CaCl ₂ of 40-60%. 300, the CaCl ₂ stable desalination rate reaches more than 85%. Clean the non-woven fabric and the filter once a week; turn over the surface of the sand layer once a week, and the depth of turning over is ≥ 0.1m.

The present invention has the following advantages and prominent effects: ① The combination of nanofiltration membrane and reoxygenation type shore filtration can give full play to the advantages of each other. Membrane treatment can reduce the salinity of reclaimed water and remove macromolecular organic matter, while shore filtration has more advantages in removing low molecular weight organic matter. Compared with reverse osmosis and ultrafiltration, nanofiltration and reoxygenation shore filtration are more complementary, and are acceptable in reducing energy consumption and removing pollutants. ②The nanofiltration membrane is placed after the reoxygenation type bank filter, and the bank filter is fully used to remove the organic matter that causes the membrane blockage, so as to protect the stable operation of the membrane. ③ Utilizing the present invention to take water from the regenerated water supply river for reuse, the effluent can meet the requirements of the three types of groundwater water quality standards, and can be used for urban landscape, irrigation, greening, urban miscellaneous purposes, process water, etc.

Description of drawings

Fig. 1 is structural principle and process flow chart of the present invention.

In the picture: In the picture: 1-river; 2-reoxygenation bank filter; 3-non-woven fabric; 4-clear water pool; 5-baffle; 6-fine grid; 7-filter; 8-flow control Valve; 9-first stage nanofiltration system; 10-second stage nanofiltration system.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a structural principle and a process flow diagram of a system and method for reusing water from regenerated water supply rivers provided by the present invention, the system includes a re-oxygenation bank filter 2, a clear water tank 4, and a flow control valve 8 and nanofiltration system; reoxygenation bank filter is set along the river, and sand layer is filled in the reoxygenation bank filter, and non-woven fabric 3 is laid on the side of the bank filter close to the river channel 1; clear water tank 4 is set in Between the reoxygenation type bank filter 2 and the river bank, a baffle plate 5 is laid on the side of the reoxygenation type bank filter tank in the clear water pool, and a fine mesh grid 6 and a filter screen 7 are arranged at the lower part of the baffle plate; the clear water pool passes through the pipeline and the flow rate The control valve 8 is connected with the nanofiltration system. The nanofiltration system can be formed by connecting a first-stage nanofiltration system 9 and a second-stage nanofiltration system 10 in series. The height of the fine mesh grid should generally be less than or equal to 1/5 of the height of the reaerobic shore filter. The particle size of the sand layer in the reoxygenated shore filter is generally 0.5-3.0mm, and the height of the sand layer should exceed the water surface by 0.1-0.5m.

Technology of the present invention is as follows:

1) Except for the condition of TN<10mg/L, the reclaimed water entering the river from the reclaimed water plant shall meet the requirements of Class IV water in the surface water environmental quality standard GB3838-2002;

2) A reoxygenation type bank filter is set up along the river. After the river water enters the bank filter through the non-woven fabric 3, some dissolved pollutants (such as dissolved organic matter and most of the organic matter that cause membrane fouling) can be removed by microbial degradation. and ammonia nitrogen and other substances), and then enter the clear water pool 4 after being filtered through the fine mesh grid 6 and the filter screen 7 in turn; the filtration speed of the reoxygenated shore filter is ≤1m/day, and the hydraulic retention time is ≥1 day; the non-woven fabric is cleaned weekly Cloth 3 and filter screen 7 once; Turn over and air the surface of the sand layer once a week, and the depth of turning over is ≥0.1m.

3) The water coming out of the clean water pool enters the nanofiltration system with negatively charged nanofiltration membrane through the flow control valve 8. The nanofiltration system preferably employs two stages. The water coming out of the clear water pool first enters the first-stage nanofiltration system 9 through the flow control valve, removes most of the organic matter and part of nitrate nitrogen and inorganic salts remaining in the water, and then enters the second-stage nanofiltration system 10, further Remove residual nitrate nitrogen, inorganic salts and residual organic matter; the nanofiltration membrane concentrated water of the second-stage nanofiltration system returns to the first-stage nanofiltration system to continue water production; the nanofiltration membrane selection in the first-stage nanofiltration system The aromatic polyamide composite nanofiltration membrane _has a molecular weight cut-off of 150-300, and the stable desalination rate of CaCl ₂ is 40-60%. The stable desalination rate reaches above 85%.

Example 1:

After the advanced treatment of the secondary effluent from the urban sewage plant, it meets the requirements of Class IV water in the surface water environmental quality standard (GB3838-2002) (TN<10mg/L), and is discharged into the river. Arrange reoxygenated bank filters along the river, and use microbial degradation to remove some dissolved organic matter and ammonia nitrogen in the river. The filter material of reoxygenation shore filter is engineering sand, the particle size is 1-3mm, the height of the sand layer is 0.5m above the water surface, the surface layer is covered with non-woven fabric, the non-woven fabric is cleaned every week, the surface layer of the sand layer is turned over to dry, and the depth of the turnover is to 0.1m below the water surface. The filtration rate is 1.0 m/day, the residence time is 1.5 days, and the effluent from the shore filter enters the clear water pool. The size of the clean water pool is 6m×1.5m×0.4m. A baffle is laid on the side of the clean water pool close to the shore filter. A fine mesh grid and a filter screen are installed on the lower part of the baffle. The height of the fine mesh grid is 30cm, and the filter screen is cleaned every week. Shore filtration can remove 30% of DOC, 50% of total phosphorus and 50% of ammonia nitrogen. The water in the clear water tank enters the first-stage nanofiltration system through the flow control valve. The nanofiltration membrane is an aromatic polyamide composite nanofiltration membrane with a medium desalination rate, which is negatively charged, with a molecular weight cut-off of 300 and a stable desalination rate (CaCl ₂ ) of 40. ~60%, the recovery rate was controlled at 15%. Through the first-stage nanofiltration system, 80% of DOC, 40% of total dissolved solids and 10% of nitrate can be removed. The effluent from the first-stage nanofiltration system enters the second-stage nanofiltration system. The second-stage nanofiltration system adopts a nanofiltration membrane with a high desalination rate, which is negatively charged, has a molecular weight cut-off of 150, and has a desalination rate of (CaCl ₂ ) of 85%. The secondary nanofiltration system removes 80% of nitrate and 90% of sulfate, and the effluent can meet the requirements of the third type of groundwater quality standards, and can be used for urban landscape, irrigation, greening, urban miscellaneous purposes, process water, etc.

Example 2:

After the advanced treatment of the secondary effluent from the urban sewage plant, it meets the requirements of Class IV water in the surface water environmental quality standard (GB3838-2002) (TN<10mg/L), and is discharged into the river. Arrange reoxygenated bank filters along the river, and use microbial degradation to remove some dissolved organic matter and ammonia nitrogen in the river. The filter material of reoxygenation shore filter is engineering sand, the particle size is 0.5-3mm, the height of the sand layer is 0.2m above the water surface, the surface layer is covered with non-woven fabric, the non-woven fabric is cleaned every week, the surface layer of the sand layer is turned over to dry, and the depth of the turnover is to 0.1m below the water surface. The filtration rate is 0.5 m/day, the residence time is 2 days, and the effluent from the shore filter enters the clear water pool. The size of the clean water pool is 6m×1.2m×0.4m. A baffle is laid on the side of the clean water pool close to the shore filter. A fine mesh grid and a filter screen are arranged on the lower part of the baffle. The height of the fine mesh grid is 30cm, and the filter screen is cleaned every week. Shore filtration can remove 40% of DOC and 50% of total phosphorus. At the same time, the shore filtration system can effectively remove proteinaceous substances and humic substances, which constitute 60% of the organic matter that causes subsequent nanofiltration membrane fouling. The filter membrane of the first-stage nanofiltration system is an aromatic polyamide composite nanofiltration membrane with a medium desalination rate, negatively charged, a molecular weight cut-off of 300, a stable desalination rate (CaCl ₂ ) of 40-60%, and a recovery rate of 10%. . The second-stage nanofiltration system adopts a nanofiltration membrane with a desalination rate, which is negatively charged, has a molecular weight cut-off of 300, and a desalination rate (CaCl ₂ ) of 90%. The two-stage nanofiltration has a removal efficiency of more than 90% for trihalomethane precursors, 80% for TDS, and more than 80% for nitrate, chloride, and sulfate, which can meet the requirements of three types of groundwater Water quality standard requirements, can be used for urban landscape, irrigation, greening, urban miscellaneous, process water, etc.

Example 3:

After the advanced treatment of the secondary effluent from the urban sewage plant, it meets the requirements of Class IV water in the surface water environmental quality standard (GB3838-2002) (TN<10mg/L), and is discharged into the river. Arrange reoxygenated bank filters along the river, and use microbial degradation to remove some dissolved organic matter and ammonia nitrogen in the river. The filter material of reoxygenated shore filter is engineering sand, the particle size is 0.5-3.0mm, the height of the sand layer is 0.2m above the water surface, the surface layer is covered with non-woven fabric, the non-woven fabric is cleaned every week, and the surface layer of the sand layer is turned over to dry. Depth to 0.1m below the water surface. The filtration rate is 0.5 m/day, the residence time is 2 days, and the effluent from the shore filter enters the clear water pool. The size of the clean water pool is 6m×1.2m×0.4m. A baffle is laid on the side of the clean water pool close to the shore filter. The lower part of the baffle is equipped with fine grids and non-woven fabrics. The height of the fine grids is 30cm. The non-woven fabrics are cleaned every week. Shore filtration can remove 50% of DOC, 50% of total phosphorus and 60% of ammonia nitrogen. The water in the clear water tank enters the first-stage nanofiltration system through the flow control valve. The nanofiltration membrane is an aromatic polyamide composite nanofiltration membrane with a medium desalination rate, which is negatively charged, with a molecular weight cut-off of 150 and a stable desalination rate (CaCl ₂ ) of 40. ~60%, the recovery rate was controlled at 10%. Through the first-stage nanofiltration system, 80% of DOC, 85% of UV254, 45% of total dissolved solids and 10% of nitrate can be removed. The effluent from the first-stage nanofiltration system enters the second-stage nanofiltration system. The second-stage nanofiltration system adopts a nanofiltration membrane with a desalination rate, which is negatively charged and has a molecular weight cut-off of ₁₅₀ . The nanofiltration system removes 85% of TDS, 85% of nitrate, 90% of sulfate, Cr, Ni, etc. are not detected, and the effluent can meet the requirements of the three types of groundwater quality standards, and can be used for urban landscape, irrigation, greening, Urban miscellaneous, process water, etc.

Claims (7)

1. A water intake reuse system from the river channel of regenerated water supply, is characterized in that: said system comprises reoxygenation type bank filter (2), clear water pool (4), flow control valve (8) and nanofiltration system, The reoxygenation type bank filter is arranged along the river channel, the sand layer is filled in the reoxygenation type bank filter, and non-woven fabric (3) is laid on the side of the bank filter close to the river channel (1); the described The clean water pool (4) is arranged between the reoxygenation type bank filter and the river bank, and the clean water pool is laid with a baffle (5) on one side of the reoxygenation type bank filter, and a fine mesh grid (6) and a filter screen ( 7); the clean water pool is connected with the nanofiltration system through a pipeline and a flow control valve (8). 2. according to claim 1, a kind of water intake reuse system from the river channel replenished by regenerated water is characterized in that: the nanofiltration system is composed of a first-stage nanofiltration system (9) and a second-stage nanofiltration system ( 10) formed in series. 3. According to claim 1, a system for reusing water from reclaimed water supply rivers, characterized in that: the height of the fine grid (6) is less than or equal to 1 of the height of the reaerobic bank filter (2) /5. 4. According to claim 1, 2 or 3, a system for water intake and reuse from regenerated water replenished river courses, characterized in that: the particle size of the sand layer of the reaerobic type bank filter is 0.5-3.0 mm, and the sand layer The height is 0.1-0.5m above the water surface. 5. adopt a kind of method for reclaiming water from the river channel of reclaimed water supply as claimed in claim 1, it is characterized in that the method comprises the steps: 1) Except for the condition of TN<10mg/L, the reclaimed water entering the river from the reclaimed water plant shall meet the requirements of Class IV water in the surface water environmental quality standard GB3838-2002; 2) A reoxygenation type bank filter is set up along the river. After the river water enters the bank filter through the non-woven fabric (3), it uses microbial degradation to remove part of the dissolved pollutants, and then passes through the fine mesh grid (6) and the filter in turn. The net (7) enters the clean water pool (4) after being filtered; the filtration rate of the reoxygenation type shore filter is ≤1m/day, and the hydraulic retention time is ≥1 day; 3) The water coming out of the clean water tank enters the nanofiltration system with negatively charged nanofiltration membrane through the flow control valve (8). 6. according to claim 5, a kind of method for reclaiming water from the regenerated water replenishment river course, it is characterized in that: the water coming out from the clean water pool first enters the first-stage nanofiltration system (9) through the flow control valve (8) ), remove organic matter, nitrate nitrogen and inorganic salt substances in the water, and then enter the second-level nanofiltration system (10), further remove residual nitrate nitrogen, inorganic salt substances and residual organic substances; The concentrated water from the nanofiltration membrane of the filtration system returns to the first-stage nanofiltration system to continue water production; the nanofiltration membrane in the first-stage nanofiltration system selects aromatic polyamide composite nanofiltration membrane, with a molecular weight cut-off of 150-300, and a stable desalination rate of CaCl ₂ The nanofiltration membrane in the second-stage nanofiltration system adopts a nanofiltration membrane with a high desalination rate, the molecular weight cut-off is 150-300, and the CaCl ₂ stable desalination rate reaches more than 85%. 7. according to claim 5 or 6 described a kind of method for taking water from the river channel of reclaimed water supply and reuse, it is characterized in that: clean non-woven fabric (3) and filter screen once every week; Once, turn over and dry to a depth of ≥0.1m. the

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