Disclosure of Invention
The invention aims to provide a refractory industrial wastewater pretreatment system, which solves the problem that organic matters in refractory industrial wastewater cannot be efficiently removed in the prior art.
Another object of the present invention is to provide a process for the above-mentioned refractory industrial wastewater pretreatment system.
The invention adopts a technical scheme that the system comprises a distribution pool, wherein the distribution pool is sequentially connected with a tubular static mixer, a primary sedimentation tank, a first micro-electrolysis tower, a second micro-electrolysis tower, a coagulation tank and a second sedimentation tank through pipelines, an aerator is arranged at a bottom inlet of the second micro-electrolysis tower, inlet pipelines of the first micro-electrolysis tower and the second micro-electrolysis tower are respectively provided with a lifting pump, and filling devices are arranged inside the first micro-electrolysis tower and the second micro-electrolysis tower; and the tubular static mixer and the coagulation tank are respectively provided with a dosing port.
The scheme is also characterized in that:
further, the filler device comprises a support plate, the support plate is vertically arranged in multiple layers and fixed in the micro-electrolysis tower, overflow holes are uniformly formed in the support plate, each layer of support plate is filled with a regulated micro-electrolysis material, and the space filling amount is 230-280 kg/m-3。
Further, the micro-electrolysis material is an oval iron-carbon micro-electrolysis material with the diameter of 3-5 cm.
Furthermore, the dosing ports are respectively connected with automatic dosing devices through pipelines.
Furthermore, a standby third micro-electrolysis tower is arranged between the second micro-electrolysis tower and the coagulation tank, a lifting pump is arranged on an inlet pipeline of the third micro-electrolysis tower, an aerator is arranged at a bottom inlet, and a filler device is arranged inside the third micro-electrolysis tower.
Furthermore, back-washing water distributors are arranged at the top parts in the first micro-electrolysis tower, the second micro-electrolysis tower and the third micro-electrolysis tower, branch pipelines on the water outlets of the two sedimentation tanks are connected with the back-washing water distributors, and lifting pumps are arranged on the branch pipelines.
Further, sludge hoppers are arranged at the bottoms of the primary sedimentation tank and the secondary sedimentation tank.
The invention adopts another technical scheme that a pretreatment method of refractory industrial wastewater adopts the pretreatment system, which comprises the following steps:
step 1, adding acid into raw water in a distribution tank to adjust the pH value, automatically flowing into a tubular static mixer, adding a medicament PAC solution and a PAM solution for coagulation, automatically flowing the effluent of the tubular static mixer into a primary sedimentation tank, flocculating and settling in the primary sedimentation tank, allowing supernatant to flow out from a water outlet at the upper part, and allowing sludge to flow out from the bottom;
step 2, pumping supernatant in the primary sedimentation tank from the bottom of the first micro-electrolysis tower through a lift pump, carrying out reduction reaction of anoxic micro-electrolysis, and discharging effluent after reaction from a water outlet at the top;
step 3, pumping the effluent from the top of the first micro-electrolysis tower from the bottom of the second micro-electrolysis tower through a lift pump, carrying out aerobic micro-electrolysis oxidation reaction under aeration, and discharging the effluent after reaction from a water outlet at the top;
step 4, the effluent from the second micro-electrolysis tower flows into a coagulation tank, and the reagent H is added firstly2O2And (3) carrying out Fenton reaction on the solution, adding a medicament soda lime solution to adjust the pH value to 7-9, automatically flowing into two sedimentation tanks from a water outlet after the Fenton reaction is ended, carrying out flocculation sedimentation in the two sedimentation tanks to finish pretreatment, enabling supernatant to flow out of the water outlet at the upper part of the tank to enter a subsequent unit, and enabling sludge to flow out of the bottom of the tank.
The scheme is also characterized in that:
furthermore, when the wastewater treatment capacity is higher than the treatment load of the first micro-electrolysis tower and the second micro-electrolysis tower, the third micro-electrolysis tower is put into use and arranged between the second micro-electrolysis tower and the coagulation tank, a lifting pump is arranged on an inlet pipeline of the third micro-electrolysis tower, an aerator is arranged at a bottom inlet, a filler device is arranged in the third micro-electrolysis tower, effluent water passing through the second micro-electrolysis tower is pumped from the bottom of the third micro-electrolysis tower through the lifting pump, the aerobic micro-electrolysis oxidation reaction is carried out under aeration, and effluent water flows into the coagulation tank from a top water outlet after the reaction;
further, the addition of the PAC solution and the PAM solution in the step 1 is 1.5-3.0L/m respectively according to the volume of the wastewater treatment3And 1.0-2.0L/m3(ii) a Step 4 of H2O2The addition amount of the solution is 2.0-3.0L/m3。
The invention has the advantages that organic matters in the industrial wastewater difficult to degrade can be efficiently removed by combining the reduction reaction of anoxic micro-electrolysis and the oxidation reaction of aerobic micro-electrolysis for alternate execution and under the action of a medicament, so that the removal rate of the organic matters and suspended matters in the industrial wastewater is improved; meanwhile, the biodegradability of the wastewater is greatly improved in the degradation process, and the subsequent biochemical treatment is facilitated.
Detailed Description
The present invention will be described in detail below with reference to the drawings and specific embodiments, but the present invention is not limited to these embodiments.
The invention discloses a refractory industrial wastewater pretreatment system, which comprises a distribution pool 1 as shown in figure 1, wherein the distribution pool 1 is sequentially connected with a tubular pipe through a pipelineStatic mixer 2, preliminary sedimentation tank 3, little electrolysis tower 4 of a number, little electrolysis tower 5 of a number two, coagulating basin 7 and two sedimentation tanks 8, be provided with the little electrolysis tower 6 of No. three for subsequent use between little electrolysis tower 5 of a number two and coagulating basin 7, No. three little electrolysis tower 6 keeps apart for subsequent use for closing under the normal condition. Inlet pipelines of the first micro-electrolysis tower 4, the second micro-electrolysis tower 5 and the third micro-electrolysis tower 6 are respectively provided with a lift pump, wastewater is pumped in from the bottom of the towers, and the wastewater flows out from the top; little electrolysis tower 4 does not set up the aerator, and No. two little electrolysis towers 5 and No. three little electrolysis tower 6 are provided with the aerator in bottom entrance, and the aerator has the fan through pipe connection, and the aerator can carry out aeration or non-aeration conversion through the fan, starts the fan aeration, carries out the oxidation reaction of good oxygen little electrolysis, closes the fan and is non-aeration, carries out the reduction reaction of oxygen deficiency little electrolysis. The interior of the micro-electrolysis tower is provided with a packing device, the packing device comprises a support plate 9 and micro-electrolysis materials 10, the support plate 9 is arranged in a plurality of layers up and down and is fixed in the tower, overflow holes are uniformly arranged on the support plate 9, the diameter of each overflow hole is 1.0-1.5cm, each layer of support plate 9 is filled with the normalized micro-electrolysis materials 10, and the packing amount of the space in the tower is 230-280kg/m3The micro-electrolysis material 10 is an elliptical iron-carbon micro-electrolysis material with a diameter of 3-5 cm. The wall surface of the tower corresponding to each layer of supporting plate is provided with a charging hole, so that the micro-electrolysis material can be conveniently stored and taken.
The top in the micro-electrolysis tower is provided with a back-washing water distributor which is a water distribution pipe communicated with each other, the water distribution pipe is arranged in a net structure, the water distribution pipe is uniformly provided with water distribution holes, and part of supernatant passing through the water outlets of the two sedimentation tanks 8 is pumped into the water distributor under the action of a lift pump to carry out back-washing operation, so as to wash adhered substances on the surface of the micro-electrolysis material and on the inner wall of the tower.
The tubular static mixer 2 is provided with a PAC dosing port and a PAM dosing port which are respectively connected with an automatic dosing device through pipelines; h is arranged on the coagulation tank 72O2A dosing port and a soda lime dosing port, H2O2The feeding port and the soda lime feeding port are respectively connected with an automatic feeding device through pipelines; the automatic medicine adding device can lead different medicines to different partsAdding the medicines through corresponding medicine adding openings respectively. The coagulation tank 7 is also provided with a mechanical stirring device, so that the medicament and the wastewater can be fully coagulated. The bottom of the primary sedimentation tank 3 and the bottom of the secondary sedimentation tank 8 are provided with sludge hoppers, and the sludge is intensively treated through the discharge ports of the sludge hoppers.
The invention discloses a pretreatment method of refractory industrial wastewater, which comprises the following steps:
step 1, adding acid into raw water in a distribution tank 1 to adjust the pH value to 3-5, then automatically flowing into a tubular static mixer 2, adding a PAC solution and a PAM solution to perform coagulation for 10-15min, then enabling the effluent of the tubular static mixer 2 to automatically flow into a primary sedimentation tank 3, performing flocculation sedimentation in the primary sedimentation tank 3 for 30-60min, enabling the supernatant of the primary sedimentation tank 3 to flow out from an upper water outlet, and enabling sludge to flow out from the bottom;
step 2, pumping supernatant in the primary sedimentation tank 3 from the bottom of the first micro-electrolysis tower 4 through a lift pump, controlling hydraulic ascending flow rate to be 0.5-0.7m/h and hydraulic retention time to be 4-6 hours, carrying out anoxic micro-electrolysis reduction reaction under non-aeration condition, and discharging water after reaction from a top water outlet;
step 3, pumping the effluent from the top of the first micro-electrolysis tower 4 from the bottom of the second micro-electrolysis tower 5 through a lift pump, wherein the hydraulic ascending flow rate and the hydraulic retention time are the same as those in the first micro-electrolysis tower 4, carrying out aerobic micro-electrolysis oxidation reaction under aeration, and discharging the effluent after reaction from a top water outlet;
step 4, the effluent from the second micro-electrolysis tower 5 flows into a coagulation tank 7, and H is added firstly2O2After the solution is subjected to the Fenton reaction for 30-50min, adding soda lime solution to adjust the pH to 7-9, automatically flowing into a secondary sedimentation tank 8 from a water outlet after the Fenton reaction is ended, and forming Fe (OH) through the Fenton reaction3And the high-efficiency flocculating agent is further subjected to flocculation precipitation with pollutants in the wastewater, the wastewater is subjected to flocculation precipitation in a secondary sedimentation tank 8 for 30-60min to finish pretreatment, supernatant flows out of a water outlet at the upper part of the tank and enters a subsequent unit, and sludge flows out of the bottom of the tank.
Wherein, in the step 1, the PAC solution is polyaluminium chloride solution with the concentration of 10 percent, the PAM solution is polyacrylamide solution with the concentration of 1 per mill, the addition amount is calculated by the volume of the wastewater treatment, and the PAC solution isThe addition amounts of the solution and the PAM solution are respectively 1.5-3.0L/m3 and 0.5-2.0L/m 3; step 4H2O2The concentration of the solution is 30 percent, the addition amount is calculated by the volume of the wastewater treatment, H2O2The addition amount of the solution is 2.0-3.0L/m 3.
And when the system runs for 13-15 days, backwashing, pumping part of supernatant of the two sedimentation tanks (8) into a backwashing water distributor through a lift pump to backwash the tower for 1-2 hours.
When the wastewater treatment capacity is higher than the treatment load of the first micro-electrolysis tower 4 and the second micro-electrolysis tower 5, the third micro-electrolysis tower 6 is put into use, the effluent passing through the second micro-electrolysis tower 5 is pumped from the bottom of the third micro-electrolysis tower 6 through a lift pump, the hydraulic ascending flow rate and the hydraulic retention time are the same as those in the second micro-electrolysis tower 5, the oxidation reaction is carried out under aeration, and the effluent after the reaction flows into the coagulation tank 7 from a top water outlet.
According to the invention, PAC solution and PAM solution are added into the tubular static mixer for coagulation and then enter the primary sedimentation tank for flocculation sedimentation, so that suspended matters in wastewater can be removed, and the blockage of gaps of the iron-carbon micro-electrolysis material in the subsequent micro-electrolysis tower is avoided.
The iron-carbon micro-electrolysis technology takes iron as an anode and carbon as a cathode, and when iron chips and activated carbon are mixed and immersed into wastewater, a large number of tiny galvanic cells are formed in the wastewater. The specific cathode and anode reactions are as follows: the cathode reaction under non-aerated conditions is as follows:
anode (Fe): fe-2e-→Fe2+ E(Fe/Fe2+)=0.44V (1)
Cathode (C): 2H++2e-→2[H]→H2 E(H+/H2)=0.00V (2)
The cathode reaction under aeration conditions is as follows:
O2+4H++4e-→2H2O E(O2/H2o) +1.23V (3) (acidic)
O2+2H++2e-→2H2O2 E(O2/H2O2) Not +0.68V (4) (acid)
O2+2H2O+4e-→4OH- E(O2/OH-) 0.40V (5) (neutral, alkalescent)
From the above reaction formula, under the non-aeration condition, the two electrode regions are both in reducing atmosphere, and the reduction capability is strongest at the moment, so that pollutants can be effectively reduced; under the condition of aeration, the strong competitive power of oxygen molecules relative to pollutants on electrons is utilized to generate hydrogen peroxide, and further generate Fenton reaction, and oxidizing degradation of pollutants is utilized. The invention has simple and convenient conversion between the non-aeration process and the aeration process in the electrolytic reaction, only needs to carry out aeration to change the reductive reactor into the oxidative reactor, and can recover after the aeration is stopped. Through the control of aeration, the alternative implementation of the reduction process and the oxidation process is realized, so that the pollutants which are easy to be oxidized are oxidized, and the pollutants which are easy to be reduced are reduced, therefore, the invention does not carry out aeration treatment in a first micro-electrolysis tower, and adopts an anoxic reduction method to remove the pollutants. The second micro-electrolysis tower and the third micro-electrolysis tower adopt an aeration oxidation method to remove pollutants, hydrogen peroxide can be generated at the cathode under aerobic conditions, the hydrogen peroxide can form a Fenton reagent with ferrous ions corroded by the subsequent anode, and the generated OH-The ions can break the chains of the macromolecular organic matters into micromolecular organic matters and carbonized part of organic matters. Meanwhile, the alternative implementation of the reduction process and the oxidation process is realized by controlling the aeration, so that the pollutants which are easy to be oxidized are oxidized and the pollutants which are easy to be reduced are reduced.
The following detailed description will proceed with reference being made to specific embodiments
Example 1
Waste to be treatedCOD of the water is 2000-4000mg/L, BOD5The pretreatment system and the pretreatment process for the refractory industrial wastewater are 100-:
step 1, adding acid into wastewater to be treated in a water distribution tank 1 to adjust the pH value to 4, and automatically flowing into a tubular static mixer 2 according to the proportion of 3.0L/m3And 2L/m3Adding PAC solution and PAM solution respectively for coagulation for 15min, allowing effluent from the tubular static mixer 2 to flow into a primary sedimentation tank 3, performing flocculation sedimentation in the primary sedimentation tank 3 for 60min, allowing supernatant of the primary sedimentation tank 3 to flow out from an upper water outlet, and allowing sludge to flow out from the bottom;
step 2, pumping supernatant in the primary sedimentation tank 3 from the bottom of the first micro-electrolysis tower 4 through a lift pump, controlling hydraulic ascending flow rate to be 0.5m/h and hydraulic retention time to be 6 hours, carrying out anoxic micro-electrolysis reduction reaction under non-aeration condition, and discharging effluent after reaction from a top water outlet;
step 3, pumping the effluent from the first micro-electrolysis tower 4 from the bottom of the second micro-electrolysis tower 5 through a lift pump, wherein the hydraulic ascending flow rate and hydraulic retention time are the same as those in the first micro-electrolysis tower 4, carrying out aerobic micro-electrolysis oxidation reaction under aeration, and discharging the effluent after reaction from a top water outlet;
step 4, the effluent water from the second micro-electrolysis tower 5 flows into a coagulation tank 7 according to the volume of 3.0L/m3Firstly adding H with the concentration of 30 percent2O2After the solution is subjected to the Fenton reaction for 50min, adding soda lime solution to adjust the pH to 8, automatically flowing into a secondary sedimentation tank 8 from a water outlet after the Fenton reaction is ended, and forming Fe (OH) through the Fenton reaction3The high-efficiency flocculating agent is further subjected to flocculation and precipitation with pollutants in the wastewater, after 60min of flocculation and precipitation in the secondary sedimentation tank 8, pretreatment is completed, supernatant flows out of a water outlet at the upper part of the tank and enters a subsequent unit, and sludge flows out of the bottom of the tank.
In order to further illustrate the beneficial effects of the invention, after a chemical plant adopts the method for pretreating the refractory industrial wastewater, the continuous operation result of half a month is detected, and the water inlet and outlet data are shown in table 1.
TABLE 1 Water in and out index test results
Index (I)
|
COD(mg/L)
|
Color intensity
|
Ammonia nitrogen (mg/L)
|
BOD5/COD
|
Inflow water
|
2000-4000
|
200-300 times
|
5-15
|
0.10-0.20
|
Discharging water
|
200-300
|
5-10
|
1-2
|
0.4 or more |
It can be seen that more than 90% of organic matters in the industrial wastewater are degraded, the system can efficiently remove the organic matters in the industrial wastewater, greatly improve the biodegradability of the wastewater, and is very favorable for subsequent biochemical treatment.
Example 2
COD of the wastewater to be treated is 2000-4000mg/L, BOD5800mg/L at 100-
Step 1, waste to be treatedAdding acid into water in a distribution tank 1 to adjust pH to 4, and automatically flowing into a tubular static mixer 2 at a rate of 1.5L/m3And 1.0L/m3Adding PAC solution and PAM solution respectively for coagulation for 10min, allowing effluent from the tubular static mixer 2 to flow into a primary sedimentation tank 3, performing flocculation sedimentation in the primary sedimentation tank 3 for 30min, allowing supernatant of the primary sedimentation tank 3 to flow out from an upper water outlet, and allowing sludge to flow out from the bottom;
step 2, pumping supernatant in the primary sedimentation tank 3 from the bottom of the first micro-electrolysis tower 4 through a lift pump, controlling hydraulic ascending flow rate to be 0.7m/h and hydraulic retention time to be 4 hours, carrying out anoxic micro-electrolysis reduction reaction under non-aeration condition, and discharging effluent after reaction from a top water outlet;
step 3, pumping the effluent from the top of the first micro-electrolysis tower 4 from the bottom of the second micro-electrolysis tower 5 through a lift pump, wherein the hydraulic ascending flow rate and the hydraulic retention time are the same as those in the step 2, carrying out aerobic micro-electrolysis oxidation reaction under aeration, and discharging the effluent after reaction from a top water outlet;
step 4, the effluent water from the second micro-electrolysis tower 5 flows into a coagulation tank 7 according to the volume of 2.0L/m3Firstly adding H with the concentration of 30 percent2O2After the solution is subjected to the Fenton reaction for 30min, adding soda lime solution to adjust the pH to 8, automatically flowing into a secondary sedimentation tank 8 from a water outlet after the Fenton reaction is ended, and forming Fe (OH) through the Fenton reaction3The high-efficiency flocculating agent is further flocculated and precipitated with pollutants in the wastewater, after the flocculation and precipitation are carried out for 30min in the secondary sedimentation tank 8, the pretreatment is completed, the supernatant flows out from the upper water outlet of the tank and enters a subsequent unit, and the sludge flows out from the bottom of the tank.
In order to further illustrate the beneficial effects of the invention, the semi-month continuous operation result is detected after a certain chemical plant adopts the degradation-resistant industrial wastewater pretreatment method, and the water inlet and outlet data are shown in table 2.
TABLE 2 Water in and out index test results
Index (I)
|
COD(mg/L)
|
Color intensity
|
Ammonia nitrogen (mg/L)
|
BOD5/COD
|
Inflow water
|
2000-4000
|
200-300 times
|
5-15
|
0.10-0.20
|
Discharging water
|
300-400
|
8-10
|
2-3
|
0.35 or more |
It can be seen that more than 85% of organic matters in the industrial wastewater are degraded, the system can efficiently remove the organic matters in the industrial wastewater, greatly improve the biodegradability of the wastewater, and is very favorable for subsequent biochemical treatment.
Example 3
COD of the wastewater to be treated is 2000-4000mg/L, BOD5800mg/L at 100-
Step 1, adding acid into wastewater to be treated in a water distribution tank 1 to adjust the pH value to 4, and automatically flowing into a tubular static mixer 2 according to the volume of 2.5L/m3And 1.5L/m3Adding PAC solution and PAM solution respectively for coagulation for 12min, and allowing effluent from the tubular static mixer 2 to flow intoThe primary sedimentation tank 3 is used for flocculating and settling for 45min in the primary sedimentation tank 3, supernatant of the primary sedimentation tank 3 flows out from a water outlet at the upper part, and sludge flows out from the bottom;
step 2, pumping supernatant in the primary sedimentation tank 3 from the bottom of the first micro-electrolysis tower 4 through a lift pump, controlling hydraulic ascending flow rate to be 0.6m/h and hydraulic retention time to be 5 hours, carrying out anoxic micro-electrolysis reduction reaction under non-aeration condition, and discharging effluent after reaction from a top water outlet;
step 3, pumping the effluent from the top of the first micro-electrolysis tower 4 from the bottom of the second micro-electrolysis tower 5 through a lift pump, wherein the hydraulic ascending flow rate and the hydraulic retention time are the same as those in the step 2, carrying out aerobic micro-electrolysis oxidation reaction under aeration, and discharging the effluent after reaction from a top water outlet;
step 4, the effluent water from the second micro-electrolysis tower 5 flows into a coagulation tank 7 according to the volume of 2.5L/m3Firstly adding H with the concentration of 30 percent2O2After the solution is subjected to the Fenton reaction for 40min, adding soda lime solution to adjust the pH to 8, automatically flowing into a secondary sedimentation tank 8 from a water outlet after the Fenton reaction is ended, and forming Fe (OH) through the Fenton reaction3The high-efficiency flocculating agent is further subjected to flocculation and precipitation with pollutants in the wastewater, after 45min of flocculation and precipitation in the secondary sedimentation tank 8, pretreatment is completed, supernatant flows out of a water outlet at the upper part of the tank and enters a subsequent unit, and sludge flows out of the bottom of the tank.
In order to further illustrate the beneficial effects of the invention, the semi-month continuous operation result is detected after a certain chemical plant adopts the method for pretreating the refractory industrial wastewater, and the water inlet and outlet data are shown in table 3.
TABLE 3 Water in and out index test results
Index (I)
|
COD(mg/L)
|
Color intensity
|
Ammonia nitrogen (mg/L)
|
BOD5/COD
|
Inflow water
|
2000-4000
|
200-300 times
|
5-15
|
0.10-0.20
|
Discharging water
|
200-350
|
6-10
|
2-3
|
0.35 or more |
It can be seen that more than 85% of organic matters in the industrial wastewater are degraded, the system can efficiently remove the organic matters in the industrial wastewater, greatly improve the biodegradability of the wastewater, and is very favorable for subsequent biochemical treatment.