CN219279701U - System for reducing COD of circulating sewage discharged by reclaimed water source - Google Patents

Abstract

The utility model provides a system for reducing COD of circulating sewage discharged by adopting a reclaimed water source, which comprises a denitrification tank, a chemical oxidation tank and a coagulating sedimentation tank which are sequentially communicated, wherein the inlet end of the denitrification tank is connected with a first adsorption tank, the outlet end of the coagulating sedimentation tank is connected with a second adsorption tank, and active carbon in the second adsorption tank can be transferred into the first adsorption tank for reuse. According to the utility model, sewage wastewater after reclaimed water circulation concentration is subjected to primary adsorption through the waste activated carbon in the first adsorption tank to reduce partial COD, microorganisms in the denitrification tank are used for removing nitrogen and sterilizing and removing most short-chain organic matters through the chemical oxidation tank, bacteria and particulate matters are removed through the coagulating sedimentation tank, and finally COD is further reduced through the new carbon with excellent performance in the second activated carbon, so that wastewater with the concentration ratio of reclaimed water being more than 3.5 is discharged up to standard.

Description

System for reducing COD of circulating sewage discharged by reclaimed water source

Technical Field

The utility model relates to the technical field of sewage treatment, in particular to a system for reducing COD (chemical oxygen demand) of circulating sewage discharged by adopting a reclaimed water source.

Background

The water resource is basic natural resource and strategic economic resource, and is an important foundation for sustainable development of social economy, ecological balance maintenance and harmony environment maintenance. The water consumption of thermal power generation is 20% of the total industrial water consumption, and the water consumption of thermal power generation becomes a limiting factor for the development of the power industry.

Reclaimed water (reclaimed water) is used as a water source of a circulating water system of a power plant unit, is an important link of sustainable development of economy and society, but discharged wastewater has the characteristics of poor biodegradability, high total nitrogen content, high pH value, high salinity and the like, and has great treatment difficulty; for this reason, the chinese patent of application No. 202210597996.3 discloses a method and system for reducing total nitrogen and COD of circulating sewage, comprising S1, circulating sewage flowing to a water storage tank; s2, circulating water discharged from the water storage tank flows into a fixed bed aeration microbial filter;

s3, circulating water sewage flowing out of the fixed bed aeration microbial filter tank flows into a Fenton reaction tank; s4, discharging. According to the method, the sewage flows into the fixed bed aeration microbial filter tank and then flows into the Fenton reaction tank, so that the effect of reducing total nitrogen and COD of the circulating sewage is improved, and the effluent is ensured to reach the discharge standard; however, the system can only treat wastewater with concentration ratio not higher than 3.5 by Fenton advanced oxidation, and has complex treatment process, difficult treatment of sludge and even secondary pollution.

In view of this, the present utility model has been made.

Disclosure of Invention

The utility model solves the problems that the COD treatment effect of the circulating sewage with the concentration ratio of more than 3.5 is poor and the cost is high in the prior art. COD (Chemical Oxygen Demand), chemical oxygen demand, is an important and relatively rapid measurement of the amount of reducing substances that need to be oxidized in a water sample by chemical means.

In order to solve the problems, the utility model provides a system for reducing COD of circulating sewage adopting a reclaimed water source, which comprises a denitrification tank, a chemical oxidation tank and a coagulating sedimentation tank which are sequentially communicated, wherein the inlet end of the denitrification tank is connected with a first adsorption tank, the outlet end of the coagulating sedimentation tank is connected with a second adsorption tank, and active carbon in the second adsorption tank can be transferred into the first adsorption tank for reuse.

The sewage wastewater after reclaimed water circulation concentration is adsorbed once through the waste activated carbon in the first adsorption tank to reduce partial COD, then is sterilized and most short-chain organic matters are removed through the microorganism in the denitrification tank by the nitrogen removal and chemical oxidation tank, then thalli and particulate matters are removed through the coagulating sedimentation tank, and finally the COD is further reduced through the new carbon with excellent performance in the second activated carbon, so that the wastewater with concentration ratio more than 3.5 is discharged up to the standard.

Preferably, stirring paddles are arranged in the first adsorption tank and/or the second adsorption tank, and are in driving connection with the driving motor. This arrangement prevents compaction of the activated carbon in the cell and enhances its ability to adsorb organic matter.

Preferably, the capacities of the first adsorption tank and the second adsorption tank are respectively V ₁ 、V ₂ Wherein V is ₁ ＝(1.5～3)*V ₂ . The arrangement can maximize the efficacy of the activated carbon and further reduce the sewage treatment cost. Preferably, the V ₁ ＝2*V ₂ 。

Preferably, the system for reducing COD of the circulating sewage adopting the reclaimed water source further comprises a new carbon pool connected with the second adsorption pool for supplementing carbon to the second adsorption pool. Preferably, the system for reducing COD of the circulating sewage adopting the reclaimed water source further comprises a sludge pond connected with the coagulating sedimentation pond and used for accommodating sludge formed by the coagulating sedimentation pond.

Preferably, the system for reducing COD of the circulating sewage adopting the reclaimed water source is connected with a circulating water system, the circulating water system comprises a cooling tower and a circulating water tank, the output end of the circulating water tank is connected with the input end of the cooling tower sequentially through a first circulating water pipeline and a second circulating water pipeline, a sewage drain pipeline is arranged at the bottom of the circulating water tank, and the outlet end of the sewage drain pipeline is communicated with the first adsorption tank. The device has simple structure, small change to the prior equipment and realizes on-site treatment.

Preferably, the second circulating water pipeline is provided with a dosing pipeline, and the dosing pipeline is sequentially provided with a dosing tank and a dosing pump. The setting can be used for adding medicine and discharging sewage according to the water quality parameters of the circulating water and calculating the concentration multiple; the medicine adding pump is used for providing power, and the medicine adding box is used for adding the needed medicine to meet the requirement of the water quality standard of the circulating water.

Preferably, the circulating water tank is provided with a water supplementing pipeline, and the water supplementing pipeline is provided with a water supplementing pump and a first electric conductivity meter. The sewage pump and the water supplementing pump can be adjusted according to the needs to be started to control the sewage flow and the water supplementing flow, so that the conductivity and the concentration ratio of the circulating cooling water are maintained in a certain range, and the first conductivity meter can be used for detecting the water quality of the circulating water on line.

Preferably, the first circulating water pipeline is sequentially provided with a circulating pump and a condenser.

Compared with the prior art, the system for reducing the COD of the circulating sewage adopting the reclaimed water source has the following beneficial effects: 1) The Fenton method can be replaced to realize the standard discharge of sewage and wastewater with concentration ratio of more than 3.5 generated by reclaimed water, and the treatment equipment is simple and has low cost; 2) The activated carbon adsorption mode is adopted, so that the effluent quality is very stable; the occupied area is small, and the operation is simple and convenient; 3) The whole process generates less waste and does not cause secondary pollution.

Drawings

FIG. 1 is a schematic diagram of a system for reducing COD in a circulating sewage using a reclaimed water source according to an embodiment of the present utility model;

FIG. 2 is a schematic structural view of a chemical oxidation basin according to an embodiment of the present utility model;

fig. 3 is a schematic structural diagram of a circulating water system according to an embodiment of the present utility model.

Reference numerals illustrate:

1-a cooling tower; 2-a circulating water tank; 3-a sewage drain pipe; 31-a sewage pump; 4-a water supplementing pipeline; 41-a first conductivity table; 42-a water supplementing pump; 5-a circulation pump; a 6-pH sensor; 7-a second conductivity table; 8-a first circulating water pipe; 9-a condenser; 10-a second circulating water pipe; 11-a dosing pipeline; 111-a dosing tank; 112-a dosing pump; 12-corrosion rate meter; 13-a first adsorption cell; 14-a denitrification tank; 141-a pool body; 1411-a first zone; 1412-second region; 1413-third zone; 1414-fourth region; 142-filter plates; 143-a supporting layer; 144-a bio-filler layer; 145-a first air inlet; 146-liquid inlet pipe; 147-a second air inlet; 148-a second outlet; 149—a first inlet; 1401-return line; 1402-first inlet chamber; 1403-second inlet chamber; 1404-a first drainage chamber; 1405-second drainage chamber; 15-a chemical oxidation tank; 16-coagulating sedimentation tank; 17-a second adsorption tank; 18-a new carbon pool; 19-a sludge tank.

Detailed Description

In order that the above objects, features and advantages of the utility model will be readily understood, a more particular description of the utility model will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. The features of the embodiments of the present utility model may be combined with each other without conflict.

At present, the total annual water consumption in China breaks through 6000 hundred million cubic meters, and the water resource per capita is only 2100 cubic meters, which is 28% of the worldwide water resource per capita.

Because the water consumption of thermal power generation is 40% of the total industrial water consumption, the utilization of reclaimed water (reclaimed water) as a water source of a circulating water system of a power plant unit is greatly advocated by the nation.

The COD content of the circulating water discharged by adopting a reclaimed water source is high, so that the circulating water becomes a pain point for popularization of the technology. For wastewater with high Chemical Oxygen Demand (COD), the existing method mostly adopts a precipitation method, a Fenton oxidation method and the like for treatment, but the technology is complex, the effect is still not ideal, and particularly, when the concentration ratio is high. For this, the applicant proposes the following technical solutions:

example 1

As shown in fig. 1-2, a system for reducing the COD of the circulating sewage adopting a reclaimed water source comprises a denitrification tank 14, a chemical oxidation tank 15 and a coagulating sedimentation tank 16 which are sequentially communicated, wherein the inlet end of the denitrification tank 14 is connected with a first adsorption tank 13, and the outlet end of the coagulating sedimentation tank 16 is connected with a second adsorption tank 17, so as to transfer activated carbon in the second adsorption tank 17 to the first adsorption tank 13.

The sewage wastewater after the reclaimed water circulation concentration is adsorbed once by the waste activated carbon in the first adsorption tank 13 to reduce part of COD, then is sterilized by the microorganism in the denitrification tank 14 to remove nitrogen and the chemical oxidation tank 15 and most of short-chain organic matters are removed, then is subjected to the removal of thalli and particulate matters by the coagulating sedimentation tank 16, and finally is further reduced by the new carbon with excellent performance in the second activated carbon, so that the wastewater with the concentration ratio more than 3.5 is discharged up to the standard.

Preferably, at least two first adsorption tanks 13 are arranged in parallel. The arrangement can realize continuous treatment of the sewage, after one of the first adsorption tanks 13 is adsorbed, solid-liquid separation is carried out on the sewage through a horizontal decanter centrifuge or a plate filter and the like, and the adsorbed waste carbon is transported outwards; at the same time, the carbon adsorbed in the second adsorption tank 17 is transferred to the other first adsorption tank 13 for adsorption.

As shown in fig. 2, the denitrification tank 14 includes a tank body 141, a first water inlet chamber 1402 and a second water inlet chamber 1403 are sequentially disposed on one side of the top of the tank body 141, and the first water inlet chamber 1402 is located outside the second water inlet chamber 1403 and connected to the water outlet of the first adsorption tank 13; the other side at the top of the tank body 141 is provided with a first drainage cavity 1404 and a second drainage cavity 1405 which are communicated in sequence, the second drainage cavity 1405 is located in the first drainage cavity 1404 and is connected with the chemical oxidation tank 15, the bottom of the second drainage cavity 1405 is provided with a second outlet 148, and the bottom of one side of the tank body 141, which is close to the first drainage cavity 1404, is provided with a first inlet 149. Preferably, the outlet end of the second water discharge chamber 1405 is communicated with the first water inlet chamber 1402 through a return pipe 1401, and the return pipe 1401 is provided with a valve body (not shown in the figure).

A fourth area 1414 is arranged at the bottom of the tank body 141, a second air inlet 147 is arranged on one side wall of the fourth area 1414, and the fourth area 1414 is communicated with the second water inlet cavity 1403 through a liquid inlet pipe 146. Preferably, the second outlet 148 is located on the opposite side wall of the fourth zone 1414 from the second air inlet 147.

The filter plate 142, the supporting layer 143 and the bio-filler layer 144 are sequentially arranged above the fourth area 1414, the bio-filler layer 144 is positioned above the supporting layer 143, and the side wall of the bio-filler layer 144, which is close to one side of the second air inlet 147, is provided with a first air inlet 145. Preferably, the bio-filler layer 144 includes a first region 1411 and a second region 1412, the second region 1412 being located on an upper side of the first region 1411 and away from the first air inlet 145, the first air inlet 145 being located between the first and second regions 1411 and 1412; this arrangement ensures that the first zone 1411 is an anaerobic zone and the second zone 1412 is an aerobic zone, and simultaneously effects of organic removal, nitrification and deamination, denitrification and dephosphorization are exhibited. Preferably, a third zone 1413 is disposed above the second zone 1412, the third zone 1413 being configured for natural settling of biological packing, and an outlet end of the third zone 1413 being in communication with the first drainage chamber 1404.

The wastewater treated by the first adsorption tank 13 enters the first water inlet chamber 1402, is mixed with part of reflux liquid passing through the reflux pipe 1401 and enters the second water inlet chamber 1403, then enters the fourth region 1414 through the liquid inlet pipe 146, is uniformly distributed through the filter plate 142 under the action of water pressure, sequentially passes through the supporting layer 143 and the biological filler layer 144, completes the removal of organic matters and nitrogen in the water in the third region 1413, and then sequentially enters the first water outlet chamber 1404 and the second water outlet chamber 1405 or flows back to the first water inlet chamber 1402 through the reflux pipe 1401.

After a period of operation, the bio-filler layer 144 becomes clogged by the trapped suspended matter. At this time, liquid feeding to the denitrification tank 14 is stopped, the first air inlet 145 is closed, the second air inlet 147, the first air inlet 149 and the second air outlet 148 are opened, gas and cleaning water enter the fourth area 1414, the whole biological filler layer 144 is back-flushed in a stroke, and the back-flushed water is discharged through the second air outlet 148.

Sodium hypochlorite is added to the chemical oxidation tank 15 to remove most of the COD. The specific adding amount and the operation method are the prior art. The coagulating sedimentation tank 16 is internally provided with a coagulant which is one or more selected from the group consisting of polyaluminum chloride, polyaluminum sulfate, polyferric chloride and polyferric sulfate, the adding amount of the coagulant is 25-50 mg/L, and the coagulant is filtered after stirring and reacting for 5-20 min.

Preferably, stirring devices are arranged in the first adsorption tank 13 and/or the second adsorption tank 17, and the stirring devices comprise a driving motor and stirring paddles which are connected with each other and are used for preventing the activated carbon in the tank from being compacted and enhancing the capability of the activated carbon in the tank for adsorbing organic matters.

Preferably, the system for reducing COD of the circulating sewage water using the reclaimed water source further comprises a new carbon tank 18 connected with the second adsorption tank 17 for supplementing the second adsorption tank 17 with activated carbon.

Preferably, the system for reducing COD of the recycled wastewater using the reclaimed water source further comprises a sludge tank 19 connected with the coagulating sedimentation tank 16 for accommodating sludge formed by the coagulating sedimentation tank 16. The sludge in the sludge tank 19 is transported outwards after further filter pressing.

Example 2

As shown in fig. 3, a system for reducing COD of a circulating sewage water using a reclaimed water source further comprises a circulating water system, wherein the circulating water system comprises a cooling tower 1, a circulating water tank 2, a sewage drain pipe 3, a sewage drain pump 31, a water supplementing pipe 4, a first electric conductivity meter 41, a water supplementing pump 42, a circulating pump 5, a ph sensor 6, a second electric conductivity meter 7, a first circulating water pipe 8, a condenser 9, a second circulating water pipe 10, a medicine adding pipe 11, a medicine adding box 111, a medicine adding pump 112 and a corrosion rate meter 12;

the circulating water output end of the circulating water tank 2 is connected with one end of the water side of the condenser 9 through the first circulating water pipeline 8, the other end of the water side of the condenser 9 is connected with the circulating water input end of the cooling tower 1 through the second circulating water pipeline 10, and the dosing pipeline 11 is connected with the second circulating water pipeline 10.

Preferably, a 220v fixed power supply is selected near the condenser 9 and connected to the vicinity of a grid plate at the upper side of the drain pump pit, each path of the No. 1 and No. 2 units is provided with 0.5kW of power, and the power is respectively used as the power supply of the second electric conductivity meter 7 and the pH sensor 6.

Specifically, the first circulating water pipe 8 is sequentially provided with a circulating pump 5 and a condenser 9.

The pH sensor 6, the second conductivity meter 7 and the corrosion rate meter 12 are sequentially arranged on the first circulating water pipeline 8, the pH value of circulating cooling water can be monitored by the circulating cooling water system installation pH sensor 6 in the scheme, the water quality of the circulating water can be detected on line by the second conductivity meter 7, and the instantaneous corrosion rate of the circulating cooling water to metal can be monitored on line by the corrosion rate meter 12.

Specifically, the sewage drain pipe 3 and the water supplementing pipe 4 are respectively connected with the circulating water tank 2, a sewage drain pump 31 is arranged on the sewage drain pipe 3, the outlet end of the sewage drain pipe 3 is communicated with the first adsorption tank 13, and the water supplementing pipe 4 is provided with a water supplementing pump 42 and a first electric conductivity meter 41. In this application scheme, can adjust the start-up of dredge pump 31, moisturizing pump 42 as required and control blowdown flow, moisturizing flow thereby make circulation cooling water's conductivity, concentration multiplying power all maintain in certain scope, but first conductivity meter 41 on-line measuring circulating water's quality of water.

Specifically, the dosing pipeline 11 is provided with a dosing tank 111 and a dosing pump 112, and in the scheme of the application, the water quality parameters of the circulating water can be detected according to the pH sensor 6, the first conductivity meter 41 and the second conductivity meter 7, and concentration multiples can be calculated to carry out dosing and pollution discharge; the medicine adding pump 112 is used for providing power, and the medicine adding box 111 is used for adding the required medicine to meet the requirement of the water quality standard of the circulating water.

Preferably, the circulating water system further comprises a control system, and the control system is electrically connected with the pH sensor 6, the first electric conductivity meter 41, the second electric conductivity meter 7, the chemical adding pump 112 of the corrosion rate meter 12, the water supplementing pump 42 and the sewage pump 31 respectively. The arrangement can realize the automatic control of the circulating water system.

Example 3

The applicant carried out the following adsorption experiments with activated carbon for raw water of different concentrations with a concentration ratio exceeding 3.5 to reduce the COD of the sewage to 15mg/L, and calculated the running cost, and the adsorption time was 2h for each experiment.

1. For low concentration raw water

As shown in the table above, the adsorption capacity of the activated carbon can reach 6.9% at a time, namely, 1g of activated carbon can reach 0.069g of COD, and the adsorption capacity of the activated carbon can reach 11.2% at two times. When the actual water inflow average concentration is 35mg/L and the water outflow concentration is 15mg/L, the COD (chemical oxygen demand) of 20kg is needed to be removed for treating 1000 tons of water, 178kg of active carbon is needed, the cost of the active carbon is 178kg multiplied by 15 yuan/kg=2678 yuan, and the cost of the ton of water is 2.68 yuan.

2. For high-concentration raw water

As shown in the table above, the adsorption capacity of the activated carbon can reach 20% at a time, namely, 1g of the activated carbon can reach 0.20g of COD, and the adsorption capacity of the activated carbon can reach 27% at two times; according to the average COD concentration of the actual inflow water of 80mg/L and the concentration of the discharged water of 15mg/L, the COD of 1000 tons of water is required to be removed by 65kg, 240kg of activated carbon is required, the cost of the activated carbon is 240kg multiplied by 15 yuan/kg=3600 yuan, and the cost of the activated carbon is reduced to 3.60 yuan for ton of water.

The above results are based on the results of two adsorption experiments, a single adsorption time of 2 hours and a total adsorption time of 4 hours; in actual engineering, the adsorption time of the activated carbon in the first adsorption tank 13 or the second adsorption tank 17 is as long as hundreds of hours, so that the utilization rate of the activated carbon is higher than that of the two adsorption experiment results.

3. Adsorption time and adsorption cell size

3.1 for low concentration water samples, tests were performed with 3% and 5% activated carbon content, and the results are shown in the following table:

3.2 for high concentration water samples, tests were performed with 3% and 5% active carbon content, and the results are shown in the following table:

as is clear from the above table, the adsorption equilibrium can be achieved for the high concentration and low concentration raw water with a residence time of 2-3 minutes under the conditions that the concentration of the activated carbon is 3% and 5%. The activated carbon adsorption tank mode is adopted, so that the water is very stable; the control of the effluent quality can be carried out by means of experiments such as residence time adjustment, active carbon concentration adjustment, active carbon updating time adjustment and the like, the operation is simple and convenient, and the risk of exceeding the standard of the effluent quality is avoided; in practical application, two-stage adsorption can be adopted, the first-stage adsorption adopts old carbon, the retention time is 20 minutes, and the COD is reduced by 50%; the second stage of adsorption adopts new carbon, the residence time is 10 minutes, and the COD is reduced to below 15 mg/L.

Although the present utility model is disclosed above, the present utility model is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the utility model, and the scope of the utility model should be assessed accordingly to that of the appended claims.

Claims (9)

1. The utility model provides a reduce system of circulating sewage COD who adopts reclaimed water source, its characterized in that, including denitrification pond (14), chemical oxidation pond (15), the coagulating sedimentation tank (16) that communicate in proper order, the entrance point of denitrification pond (14) links to each other with first adsorption tank (13), the exit end of coagulating sedimentation tank (16) links to each other with second adsorption tank (17), the active carbon in second adsorption tank (17) can shift to in first adsorption tank (13) is recycled.

2. The system for reducing COD of a circulating sewage utilizing a reclaimed water source according to claim 1, wherein stirring paddles are arranged in the first adsorption tank (13) and/or the second adsorption tank (17), and the stirring paddles are in driving connection with a driving motor.

3. The system for reducing COD of a circulating sewage using a reclaimed water source according to claim 2, wherein the capacities of the first adsorption tank (13) and the second adsorption tank (17) are respectively V ₁ 、V ₂ Wherein

V ₁ ＝(1.5～3)*V ₂ 。

4. The system for reducing COD of a circulating sewage using a reclaimed water source according to claim 1, further comprising a fresh carbon tank (18) connected to the second adsorption tank (17) for replenishing the second adsorption tank (17) with carbon.

5. The system for reducing COD of a circulating sewage using a reclaimed water source according to claim 4, further comprising a sludge tank (19) connected to the coagulating sedimentation tank (16) for holding sludge formed by the coagulating sedimentation tank (16).

6. The system for reducing the COD of the circulating sewage adopting the reclaimed water source according to claim 1, wherein the system for reducing the COD of the circulating sewage adopting the reclaimed water source is connected with a circulating water system, the circulating water system comprises a cooling tower (1) and a circulating water tank (2), the output end of the circulating water tank (2) is sequentially connected with the input end of the cooling tower (1) through a first circulating water pipeline (8) and a second circulating water pipeline (10), a sewage drain pipeline (3) is arranged at the bottom of the circulating water tank (2), and the outlet end of the sewage drain pipeline (3) is communicated with the first adsorption tank (13).

7. The system for reducing COD of a circulating sewage employing a reclaimed water source according to claim 6, wherein the second circulating water pipeline (10) is provided with a dosing pipeline (11), and the dosing pipeline (11) is sequentially provided with a dosing tank (111) and a dosing pump (112).

8. The system for reducing COD of a circulating sewage utilizing a reclaimed water source according to claim 6, wherein the circulating water tank (2) is provided with a water supplementing pipe (4), and the water supplementing pipe (4) is provided with a water supplementing pump (42) and a first conductivity meter (41).

9. The system for reducing COD of the circulating sewage discharged by adopting the reclaimed water source according to claim 6, wherein the circulating pump (5) and the condenser (9) are sequentially arranged on the first circulating water pipeline (8).

Images