CN110803833A

CN110803833A - Petrochemical RO strong brine treatment system and method

Info

Publication number: CN110803833A
Application number: CN201911155929.0A
Authority: CN
Inventors: 王晓阳; 巨春燕; 汪德罡; 郝瀚; 谢晓朋; 王寿鹤
Original assignee: BEIJING HANQI ENVIRONMENTAL TECHNOLOGY Co Ltd
Current assignee: BEIJING HANQI ENVIRONMENTAL TECHNOLOGY Co Ltd
Priority date: 2019-11-22
Filing date: 2019-11-22
Publication date: 2020-02-18

Abstract

The invention relates to a petrochemical RO strong brine treatment system and a method thereof, which comprises a first high-efficiency precipitation unit, an ozone catalytic oxidation unit, a stripping unit, a denitrification unit, an MBBR aerobic unit and a second high-efficiency precipitation unit, wherein the first high-efficiency precipitation unit, the ozone catalytic oxidation unit, the stripping unit, the denitrification unit, the MBBR aerobic unit and the second high-efficiency precipitation unit are sequentially communicated along the flow direction of strong brine; the treatment method comprises the steps of hardness removal, coagulation, flocculation, precipitation separation, ozone oxidation, nitrogen stripping, MBBR treatment and dephosphorization precipitation. The invention has the advantages that RO strong brine can be treated, COD, total phosphorus, hardness, alkalinity and total nitrogen in the RO strong brine are reduced, the RO strong brine can be discharged after reaching standards, particularly nitrate nitrogen of the strong brine can be remarkably reduced, and the total nitrogen discharged from the strong brine is less than or equal to 10 mg/L.

Description

Petrochemical RO strong brine treatment system and method

Technical Field

The invention relates to the technical field of strong brine treatment, in particular to a petrochemical RO strong brine treatment system and a method thereof.

Background

At present, RO treatment technology is widely applied to a plurality of fields such as electronics, chemical industry, seawater desalination and the like, has irreplaceable advantages, adopts RO technology to treat strong brine and wastewater, can generate about 1/3 strong brine, contains difficultly biodegradable organic substances harmful to human health and ecological environment in the strong brine, and has concentration exceeding discharge standard, so the treatment of the strong brine becomes a focus of wide RO use.

In particular, the petrochemical RO strong brine has the characteristics of high chloride ions, high COD (chemical oxygen demand) which is difficult to degrade, total nitrogen (mainly nitrate nitrogen is used as main nitrogen, and ammonia nitrogen is less), high total phosphorus and hardness, high alkalinity and the like, and is one of strong brines which are difficult to treat. Since day 4 and 16 in 2015, the emission standard of pollutants for petroleum refining industry (GB 31570-2015) was issued by Ministry of environmental protection, the requirement for total nitrogen was increased in the emission limit of water pollutants, namely, the emission standard was executed from 7 and 1 in 2017, the emission requirement for total nitrogen was not more than 40mg/L, and since the standard was executed, the concentrated brine treatment field of the company in petrochemical industry began to transform the biochemical section, and RO concentrated brine was treated to improve COD, total nitrogen, total phosphorus, hardness and the like in the concentrated brine, thereby achieving the emission standard. Although the TN concentration of the effluent TN of the monitoring pool of the facility for discharging the concentrated brine reaching the standard is gradually reduced to be below 30 mg/L after the biochemical section is reformed, the TN concentration still has a larger difference with the A standard (total nitrogen discharge requirement is less than or equal to 10 mg/L) of the discharge standard of pollutants for concentrated brine treatment plants in cities and towns (DB 12/599) 2015) of the local standard of Tianjin.

Therefore, there is a need for a system and a method for treating a petrochemical RO brine, which can treat the RO brine so that the treated RO brine COD, total phosphorus, hardness, alkalinity and total nitrogen meet the discharge standards, and particularly so that the total nitrogen in the final discharge of the brine is less than or equal to 10 mg/L.

Disclosure of Invention

Aiming at the defects in the prior art, the first object of the invention is to provide a petrochemical RO strong brine treatment system, which has the advantages of treating RO strong brine, reducing COD, total phosphorus, hardness, alkalinity and total nitrogen in RO strong brine, enabling the RO strong brine to reach the discharge standard, and particularly remarkably reducing nitrate nitrogen of the strong brine, so that the total nitrogen in the discharged strong brine is less than or equal to 10 mg/L.

The second purpose of the invention is to provide a petrochemical RO strong brine treatment method, which has the advantages that the RO strong brine can be treated by the method provided by the invention, COD, total phosphorus, hardness, alkalinity and total nitrogen in the RO strong brine are reduced, the RO strong brine can reach the discharge standard, particularly nitrate nitrogen of the strong brine can be remarkably reduced, and the total nitrogen in the discharged strong brine is less than or equal to 10 mg/L.

In order to achieve the first purpose, the invention provides the following technical scheme that the petrochemical RO strong brine treatment system comprises a first efficient precipitation unit, an ozone catalytic oxidation unit, a stripping unit, a denitrification unit, an MBBR aerobic unit and a second efficient precipitation unit, wherein the first efficient precipitation unit, the ozone catalytic oxidation unit, the stripping unit, the denitrification unit, the MBBR aerobic unit and the second efficient precipitation unit are sequentially communicated along the flow direction of strong brine, the first efficient precipitation unit is connected with a water inlet pipe, the second efficient precipitation unit is connected with a first water outlet pipe, the stripping unit comprises a stripping tank, and a stripping piece for introducing nitrogen into the strong brine in the stripping tank is arranged in the stripping tank.

By adopting the technical scheme, when RO strong brine is treated, RO strong brine firstly enters the first high-efficiency precipitation unit to remove hardness, after the hardness removal operation, the sludge yield in the subsequent treatment of the strong brine is less, and the scaling phenomenon in the subsequent ozone catalytic oxidation unit can be reduced, the ozone utilization rate is improved, meanwhile, suspended matters in the strong brine are also removed in the first high-efficiency precipitation unit, the strong brine after high-efficiency precipitation enters the ozone catalytic oxidation unit, the organic matters which are difficult to degrade in the strong brine are converted into organic matters which are easy to degrade by taking ozone as an oxidant, so that the biodegradability of the strong brine is improved, partial COD can be reduced, then the strong brine enters the stripping tank, a stripping piece in the stripping tank introduces nitrogen into the strong brine in the stripping tank, the dissolved oxygen in the strong brine is stripped from the strong brine, and the dissolved oxygen in the water is rapidly reduced, the oxygen dissolving requirement of the denitrification unit is met, then the concentrated brine is removed through the denitrification unit, then the nitrate nitrogen in the concentrated brine is removed, then the concentrated brine enters the MBBR aerobic unit, the residual carbon source added in the denitrification unit and the COD originally existing in the water can be effectively removed through the aerobic unit, the COD in the water is effectively removed, then the concentrated brine enters the second efficient precipitation unit, the second efficient precipitation unit removes phosphorus from the concentrated brine and removes suspended matters again, the COD, the total phosphorus, the hardness, the alkalinity and the total nitrogen in the treated concentrated brine are remarkably reduced, particularly the total nitrogen is less than or equal to 10mg/L, and the discharge requirement is met.

The invention is further configured to: the blowing-off part comprises a nitrogen aeration pipe arranged at the bottom of the blowing-off tank, the nitrogen aeration pipe is connected with a nitrogen source, a plurality of air passing holes are formed in the upper end face of the nitrogen aeration pipe, and the upper end of the blowing-off tank is connected with a ventilation pipe communicated with the atmosphere.

Through adopting above-mentioned technical scheme, be provided with the nitrogen gas aeration pipe of gas pocket and set up and let in nitrogen gas in to the blow-off pond, play the effect that reduces dissolved oxygen, blow in the blow-off pond and let in nitrogen gas and realize the strip back of dissolved oxygen, nitrogen gas and oxygen are arranged to the air from the breather pipe.

The invention is further configured to: the first high-efficiency precipitation comprises a hardness removal reaction tank, a coagulation tank, a flocculation tank and a precipitation separation tank which are sequentially communicated along strong brine, wherein an alkali substance adding pipe is arranged in the hardness removal reaction tank, a coagulant adding pipe is arranged in the coagulation tank, and a flocculant adding ring is arranged in the flocculation tank;

the bottom center part of the sedimentation separation tank is provided with a sludge collecting hopper, the sedimentation separation tank is provided with a sludge scraper for scraping bottom sludge into the sludge collecting hopper, the middle part of the sedimentation separation tank is provided with an inclined tube separation zone, the upper part of the sedimentation separation tank is provided with a plurality of water outlet grooves, and the water outlet grooves are communicated with the ozone catalytic oxidation unit through water outlet channels;

the sludge collecting hopper is communicated with a sludge circulating pipe and a sludge discharging pipe, the sludge circulating pipe is connected with a sludge circulating pump and is communicated with the flocculation tank, the sludge circulating pump is positioned between the sludge collecting hopper and the flocculation tank, and the sludge discharging pipe is connected with a sludge discharging pump.

By adopting the technical scheme, RO strong brine firstly enters a hardness removal reaction tank, alkali is added through an alkali substance adding pipe to remove calcium ions, magnesium ions and the like in the strong brine, the purpose of hardness removal is achieved, then the RO strong brine enters a concrete tank, a coagulant is added into the concrete tank through a coagulant adding pipe, pollutants and suspended matters in the strong brine are destabilized, electrically neutralized, adsorbed, bridged and other complex processes are carried out to form a plurality of fine alum flocs, the strong brine and the fine alum flocs enter a flocculation area, a flocculating agent is added into the flocculation tank through a flocculating agent adding ring, the fine alum flocs are rapidly aggregated to form large dense alum flocs under the action of the flocculating agent, then the strong brine carries the large alum flocs to enter a precipitation separation tank for sludge-water separation, clear water enters an ozone catalytic oxidation unit from a water outlet channel, the heavy alum flocs form sludge and fall into the bottom of the precipitation separation tank, in scraping mud into the mud collection fill that sedimentation tank bottom set up through the mud scraper, then through the sludge circulating pump with partly backward flow of mud to flocculation area utilization, the surplus portion discharges through the mud drainage pump.

The invention is further configured to: the ozone catalytic oxidation unit comprises a plurality of ozone contact tanks, an ozone catalytic oxidation tank and an ozone decomposition tank which are sequentially communicated along the flowing direction of strong brine, wherein ozone aeration discs are arranged at the bottoms of the ozone contact tanks and the ozone catalytic oxidation tank, catalyst layers are further arranged above the ozone aeration discs of the ozone catalytic oxidation tank, and a tail gas destructor is communicated with the upper end of the ozone decomposition tank.

Through adopting above-mentioned technical scheme, the setting up of ozone aeration dish makes ozone come out from the ozone aeration dish and mixes with the strong brine, utilizes the strong oxidizing property of ozone to get rid of the very little partly COD of strong brine, can also make the COD of aquatic difficult degradation carry out the open loop chain scission, becomes the COD that microorganism can be degraded on next step, can reduce the carbon source of denitrification unit and throw the dosage. The setting up of catalyst layer makes ozone utilization ratio in the ozone catalytic oxidation pond higher in the ozone catalytic oxidation pond, and the effect is better, then the strong brine gets into the ozonolysis pond, and the ozonolysis pond provides necessary reaction time for ozone can have sufficient time to decompose, and unnecessary ozone gets into in the tail gas destructor.

The invention is further configured to: the second efficient precipitation unit comprises a phosphorus removal reaction tank, the phosphorus removal reaction tank is connected with a flocculation tank for adding a flocculating agent, the flocculation tank is communicated with a precipitation separation tank for separating mud from water, the phosphorus removal reaction tank is provided with a phosphorus removal agent adding pipe for adding a phosphorus removal agent, and the phosphorus removal reaction tank, the flocculation tank and the precipitation separation tank are sequentially communicated along the flowing direction of strong brine.

Through adopting above-mentioned technical scheme, the strong brine gets into the dephosphorization reaction tank from MBBR good oxygen unit in, gets rid of the phosphorus in the strong brine through the addition of dephosphorization medicament, guarantees that the total phosphorus of play water is up to standard, then carries out flocculation and precipitation separation again, gets rid of the suspended solid in the strong brine.

The invention is further configured to: the system also comprises a carbon filter tank communicated with the second high-efficiency precipitation unit, one end of the carbon filter tank is communicated with the water outlet channel of the second high-efficiency precipitation unit, and the other end of the carbon filter tank is connected with a second water outlet pipe for the outflow of the strong brine.

Through adopting above-mentioned technical scheme, the setting of carbon canister can be to filtering after the strong brine dephosphorization removes the suspended solid in the high-efficient precipitation unit of second, gets rid of the COD that strong brine is difficult to the degradation, guarantees that water COD satisfies emission standard.

In order to achieve the first object, the invention provides the following technical scheme, a petrochemical RO strong brine treatment method is realized by adopting the petrochemical RO strong brine treatment system, and the method comprises the following steps:

and (3) hardness removal: the RO strong brine enters the hardness removal reaction tank through a water inlet pipe, and an alkaline substance is added into the hardness removal reaction tank to remove calcium ions and magnesium ions in the RO strong brine, so that the hardness of the RO strong brine is reduced;

coagulation: adding a coagulant into the coagulation tank, mixing the calcium carbonate precipitate, the magnesium hydroxide precipitate and pollutants and suspended matters in the concentrated brine formed in the step of hardness removal with the coagulant to form small alum flocs, and feeding the small alum flocs into the flocculation tank of the first high-efficiency precipitation unit;

primary flocculation: adding a flocculating agent into a flocculation tank of the first high-efficiency precipitation unit, and allowing concentrated brine carrying small alum flocs in the flocculation tank to aggregate to form compact large alum flocs and then enter a precipitation separation tank of the first high-efficiency precipitation unit;

primary precipitation separation: after primary flocculation, strong brine carrying large alum floc enters an inclined tube separation zone for sludge-water separation, clear water enters a water inlet tank, then the clear water is converged and flows out from a water outlet channel, the clear water enters an ozone catalytic oxidation unit, the large alum floc formed sludge falls to the bottom of the sedimentation separation tank, and the sludge falls into a sludge collecting hopper under the action of a sludge scraper;

catalyzing by ozone: the strong brine enters an ozone catalytic oxidation unit to contact with ozone, and organic matters which are difficult to degrade in the strong brine are converted into organic matters which are easy to degrade;

nitrogen stripping: the strong brine enters a stripping tank, and nitrogen is introduced into the strong brine in the stripping tank to reduce dissolved oxygen in the water;

MBBR treatment: the strong brine subjected to nitrogen stripping enters a denitrification unit to be subjected to denitrification by using denitrifying bacteria, and then enters an MBBR aerobic unit to be subjected to organic matter removal by using aerobic bacteria;

dephosphorization and precipitation: the method comprises the following steps of firstly enabling strong brine to enter a phosphorus removal reaction tank, adding a phosphorus removal medicament into the phosphorus removal reaction tank to remove phosphorus in the strong brine, then enabling the strong brine to enter a flocculation tank of a second high-efficiency precipitation unit for flocculation, then enabling the strong brine to enter the second high-efficiency precipitation unit for mud-water separation, and enabling clear water to flow out of a water outlet channel of the precipitation separation tank.

And (3) allowing the strong brine treated by the MBBR to enter a second high-efficiency precipitation unit, adding a phosphorus removal agent and a flocculating agent into the second high-efficiency precipitation unit to remove phosphorus and suspended matters in the strong brine, then performing mud-water separation, and allowing clear water after mud-water separation to flow out from a first water outlet pipe.

By adopting the technical scheme, calcium ions and magnesium ions in RO strong brine are removed through the hardness removal step, the hardness of the RO strong brine is reduced, suspended matters in the strong brine are removed through coagulation, primary flocculation and primary precipitation separation steps, the SS of the strong brine is reduced, refractory organic matters in the strong brine are converted into easily degradable organic matters through the ozone catalysis step, COD is removed, the dissolved oxygen concentration in the strong brine is reduced through the nitrogen stripping step, the MBBR treatment step is carried out, the strong brine is firstly subjected to denitrification by denitrifying bacteria and then enters the MBBR aerobic unit, the organic matters in the strong brine are removed by aerobic bacteria, finally, the phosphorus removal precipitation step is carried out, the phosphorus in the strong brine is firstly removed, the total phosphorus in the strong brine is reduced, then flocculation and muddy water separation are carried out, the suspended matters in the water are removed, and the total nitrogen, the carbon dioxide and the carbon dioxide in the strong brine are finally treated, The total phosphorus, SS, hardness and alkalinity can reach the discharge standard.

The invention is further configured to: in the nitrogen stripping step, controlling the gas-water ratio of the introduced nitrogen to the concentrated brine to be (1-5): 1.

the invention is further configured to: in the step of hard removing: adding alkaline substances into the hardness removal reaction tank, keeping the pH value in the hardness removal reaction tank above 10.0, and controlling the reaction time of strong brine in the hardness removal reaction tank to be 2-3 min;

in the coagulation step: adding a coagulant into the coagulation tank, keeping the concentration of the coagulant in the coagulation tank at 30-100mg/L, and controlling the reaction time of concentrated brine in a coagulation area to be 2-3 min;

in the primary flocculation step: adding a flocculating agent into a flocculation tank of the first high-efficiency precipitation unit, keeping the concentration of the flocculating agent in the flocculation tank to be 0.5-2.0mg/L, and controlling the reaction time of strong brine in the flocculation zone to be 6-12 min;

in the dephosphorization precipitation step: and adding a phosphorus removal medicament into the phosphorus removal reaction tank, controlling the reaction time of strong brine in the phosphorus removal reaction tank to be 2-3min, adding a flocculating agent into the flocculation tank in the second high-efficiency precipitation unit, maintaining the concentration of the flocculating agent in the flocculation tank to be 0.5-2.0mg/L, and controlling the retention time of the strong brine in the flocculation tank to be 6-12 min.

The invention is further configured to: the method also comprises an active carbon filtering step, wherein if the COD value of the concentrated brine after the effluent of the outlet channel of the second high-efficiency precipitation unit in the dephosphorization precipitation step is treated reaches the standard, the concentrated brine is directly discharged from the outlet channel of the second high-efficiency precipitation unit; and if the COD value of the concentrated brine after the effluent of the water outlet channel of the second high-efficiency precipitation unit in the dephosphorization precipitation step is not up to the standard, filtering the concentrated brine by using activated carbon after the effluent of the water outlet channel of the second high-efficiency precipitation unit in the dephosphorization precipitation step is discharged.

In conclusion, the beneficial technical effects of the invention are as follows:

1. according to the invention, the first efficient precipitation unit is arranged to remove hardness and suspended matters from the concentrated brine, the ozone catalytic oxidation unit is arranged to convert refractory organic matters in the concentrated brine into easily degradable organic matters and remove COD, the stripping unit is arranged to reduce dissolved oxygen in the concentrated brine so as to meet the requirement of denitrification and dissolved oxygen, the denitrification unit is used for denitrifying the concentrated brine so as to remove nitrate nitrogen, the MBBR aerobic unit is used for removing organic matters in the brine, and finally, the dephosphorization precipitation step is carried out to remove phosphorus and suspended matters in the concentrated brine, so that COD, total phosphorus, hardness, alkalinity and total nitrogen in the finally treated concentrated brine are remarkably reduced, especially, the total nitrogen is less than or equal to 10mg/L, and the emission requirement is met;

2. according to the invention, the blow-off unit is arranged to introduce nitrogen into the concentrated brine in the blow-off tank, and the nitrogen is introduced into the concentrated brine to enable oxygen molecules in the concentrated brine to pass through a gas-liquid phase interface and transfer to a gas phase, so that the reverse mass transfer phenomenon of dissolved oxygen in water is realized, the dissolved oxygen in the concentrated brine can be extracted from the concentrated brine, the dissolved oxygen in water can be rapidly reduced to be below 0.5mg/L, the dissolved oxygen requirement of the denitrification unit is met, the operation is more convenient and convenient, the cost is lower, and the treatment effect is better;

3. according to the invention, the ozone aeration disc in the ozone catalytic oxidation unit is arranged to enable ozone to come out from the ozone aeration disc and be mixed with the concentrated brine, a small part of COD in the concentrated brine is removed by utilizing the strong oxidizing property of the ozone, and the COD which is difficult to degrade in the brine can be subjected to open loop and chain scission to become the COD which can be degraded by microorganisms in the next step, so that the carbon source adding amount of the denitrification unit can be reduced.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic diagram of a first high efficiency precipitation unit embodied in the present invention;

FIG. 3 is a schematic structural view of an ozone catalytic oxidation unit and a blow-off unit according to the present invention;

FIG. 4 is a schematic diagram of a second high efficiency precipitation unit embodied in the present invention.

In the figure, 1, a first high-efficiency precipitation unit; 11. distributing a water well; 111. a water inlet pipe; 12. a hardness removal reaction tank; 121. An alkaline substance addition tube; 13. a coagulation tank; 131. a coagulant adding pipe; 14. a flocculation tank; 141. a flocculating agent feeding ring; 142. a draft tube; 143. a first baffle plate; 144. an energy dispersion chamber; 145. a non-mixing chamber; 146. a water passage; 147. a flocculation stirrer; 15. a sedimentation separation tank; 151. a mud collection hopper; 152. a mud scraper; 153. a water outlet groove; 154. a water outlet channel; 155. a sludge circulation pipe; 156. a sludge discharge pipe; 157. a sludge circulating pump; 158. a sludge discharge pump; 159. a pipe chute separation zone; 16. a baffle; 17. a flow passage; 18. a drainage tube; 19. a mixing agitator; 2. an ozone catalytic oxidation unit; 21. an ozone contact tank; 211. a second baffle; 212. an aeration zone; 213. a buffer area; 214. an overflow channel; 22. an ozone catalytic oxidation tank; 221. a catalyst layer; 23. an ozone decomposition tank; 24. an ozone aeration disc; 25. an overflow channel; 26. a tail gas destructor; 3. a stripping unit; 31. a stripping tank; 32. a nitrogen aeration pipe; 33. a breather pipe; 4. a denitrification unit; 41. a stirrer; 42. a carbon source feeding pipe; 5. an MBBR aerobic unit; 6. a second high efficiency precipitation unit; 61. a dephosphorization reaction tank; 611. a phosphorus removal agent addition tube; 62. a third baffle plate; 7. a first water outlet pipe.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

Referring to fig. 1, the RO concentrated brine treatment system for petrochemical industry disclosed by the invention comprises a first high-efficiency precipitation unit 1, an ozone catalytic oxidation unit 2, a stripping unit 3, a denitrification unit 4, an MBBR aerobic unit 5 and a second high-efficiency precipitation unit 6 which are sequentially arranged along the flow direction of concentrated brine, wherein the first high-efficiency precipitation unit 1 is connected with a water inlet pipe 111 through a water distribution well 11, and the second high-efficiency precipitation unit 6 is connected with a first water outlet pipe 7. First high-efficient precipitation unit 1 is used for getting rid of the suspended solid in the RO strong brine, ozone catalytic oxidation unit 2 is used for getting rid of the organic matter in the RO strong brine, blow off unit 3 is used for reducing the dissolved oxygen in the RO strong brine in order to carry out subsequent denitrification, denitrification unit 4 carries out the denitrification under the condition of anaerobism, it spills over to turn into nitrogen with the nitrate nitrogen in aquatic, the aerobic unit 5 of MBBR gets rid of and degrades the aquatic organic matter through aerobic bacteria in aerobic environment, effectively get rid of the COD that the surplus carbon source of throwing in the denitrification unit and originally exist in the aquatic, effectively get rid of the COD in the aquatic. The second efficient precipitation unit 6 removes phosphorus and suspended matters from the strong brine, and after the treatment of the units, COD, total phosphorus, hardness, alkalinity and total nitrogen in the finally treated strong brine are remarkably reduced, particularly the total nitrogen is less than or equal to 10mg/L, so that the discharge requirement is met.

As shown in fig. 1 and 2, the first high-efficiency precipitation unit 1 includes a hardness-removing reaction tank 12, a coagulation tank 13, a flocculation tank 14 and a precipitation separation tank 15 which are sequentially communicated along the flow direction of the concentrated brine, an alkali substance feeding pipe 121 is arranged in the hardness-removing reaction tank 12, a coagulant feeding pipe 131 is arranged in the coagulation tank 13, and a flocculant feeding ring 141 is arranged in the flocculation tank 14. During RO strong brine treatment, RO strong brine enters a de-hardening reaction tank 12 through a water inlet pipe 111, alkali such as sodium hydroxide is added through an alkali substance adding pipe 121 to remove calcium ions, magnesium ions and the like in the strong brine to achieve the purpose of de-hardening, then the RO strong brine enters a coagulation tank 13, a coagulant is added into the coagulation tank 13 through a coagulant adding pipe 131, pollutants and suspended matters in the strong brine are subjected to complex processes such as destabilization, electric neutralization and adsorption bridging to form a plurality of fine alum flocs, the strong brine and the fine alum flocs enter a flocculation area, a flocculating agent is added into a flocculation tank 14 through a flocculating agent adding ring 141, the fine alum flocs are rapidly aggregated to form large dense alum flocs under the action of the flocculating agent, and then the strong brine carries the large alum flocs to enter a precipitation separation tank 15 to perform sludge-water separation.

A guide plate 16 is arranged in the hardness removing reaction tank 12, the lower end face of the guide plate 16 is higher than the bottom wall of the hardness removing reaction tank 12 so as to allow the strong brine to flow through, the hardness removing reaction tank 12 and the coagulation tank 13, the flocculation tank 14 and the precipitation separation tank 15 are communicated through a flow passage 17, the flow passage 17 is positioned on the upper part of the common chamber wall of the hardness removing reaction tank 12 and the coagulation tank 13 or the upper part of the common chamber wall of the flocculation tank 14 and the precipitation separation tank 15, and the coagulation tank 13 and the flocculation tank 14 are communicated through a drainage tube 18. The arrangement enables the concentrated brine to form an upflow flow when flowing through the adjacent treatment tanks, and can further promote the reaction of the concentrated brine with the alkali substance, the coagulant or the flocculant. The hardness removing reaction tank 12 and the coagulation tank 13 are both provided with a mixing stirrer 19 so as to enable the concentrated brine and the coagulant or the alkali substance to be mixed more uniformly.

A first baffle 143 is arranged in the flocculation tank 14 to form an energy dispersion chamber 144 and a non-mixing chamber 145, the lower end face of the first baffle 143 is higher than the bottom of the flocculation area to form a water channel 146, and the energy dispersion chamber 144 and the non-mixing chamber 145 are sequentially arranged along the flow direction of the concentrated brine. The energy dispersion chamber 144 is internally provided with a guide shell 142 which enables part of the concentrated brine in the energy dispersion chamber 144 to circularly flow therein, the concentrated brine inlet end of the guide shell 142 is in a bell mouth shape, and one end of the drainage tube 18 extends into the bell mouth-shaped side of the guide shell 142. A flocculation stirrer 147 is further arranged in the energy dispersion chamber 144, the flocculation stirrer 147 is arranged in the guide shell 142, and a flocculating agent feeding ring 141 is arranged in the guide shell 142. The setting of first baffle 143 makes flocculation basin 14 be the upflow reaction tank, and the strong brine in energy dispersion room 144 gets into non-mixing chamber 145 from water channel 146 after the contact reaction with the flocculating agent, and then gets into in the sedimentation tank 15, and this upflow reaction tank's setting can further promote flocculation, can obtain bigger alum blossom, and alum blossom weight increases, can reach higher sedimentation velocity in the sedimentation tank 15. The horn mouth draft tube 142's setting makes the strong brine get into draft tube 142 from flocculation basin 14 more easily, reacts with the flocculating agent, and the setting of flocculation agitator 147 makes the strong brine and the contact of flocculating agent mix more fully.

The bottom center part of the sedimentation separation tank 15 is provided with a sludge collection hopper 151, the sedimentation separation tank 15 is provided with a sludge scraper 152 for scraping bottom sludge into the sludge collection hopper 151, the middle part is provided with an inclined tube separation zone 159, the upper part is provided with a plurality of water outlet grooves 153, one side of the sedimentation separation tank 15 away from the flocculation tank 14 is provided with a water outlet channel 154 for separated clean water to flow out, and the water outlet channel 154 is communicated with the upper part of the ozone catalytic oxidation unit 2 through a pipeline. The mud scraper 152 is preferably a mud scraper 152 with a thickening rake, which is a mud scraping and stirring device, which rotates slowly around the center of the tank, pushing the sludge sinking at the bottom into the central mud hopper 151, thus promoting the thickening effect of the sludge. Clear water after the strong brine flocculation in the flocculation tank 14 enters the water outlet channel 154 from the water outlet groove 153, then enters the ozone catalytic oxidation unit 2 through a pipeline, heavy alum floc formed sludge falls into the bottom of the sedimentation separation tank 15, and the sludge is scraped into the sludge collection hopper 151 arranged at the bottom of the sedimentation separation tank 15 through the sludge scraper 152.

The upper part of the sludge collecting hopper 151 is connected with a sludge circulating pipe 155, the lower part is connected with a sludge discharging pipe 156, the sludge circulating pipe is communicated with the drainage pipeline, a sludge circulating pump 157 is arranged between the sludge circulating pipe 155 and the drainage pipe 18, and the sludge discharging pipe 156 is connected with a sludge discharging pump 158. Mud circulating pump 157 can follow the upper portion suction mud of sludge collection fill 151 and flow back to drainage tube 18, and then get into flocculation basin 14 cyclic utilization once more, and strong brine contacts with the backward flow mud of high concentration in the flocculation basin 14, and destabilizing impurity and the collision of mud granule reach better flocculation effect, and the alum blossom flocculation that becomes heavy and big is carried, and mud discharge pump 158 is discharged from the suction mud of sludge collection fill 151 bottom after the concentration.

As shown in fig. 3, the catalytic ozonation unit 2 comprises a plurality of ozone contact tanks 21, a catalytic ozonation tank 22 and an ozone decomposition tank 23 which are sequentially communicated along the flow direction of the concentrated brine, and the upper part of the ozone contact tank 21 close to one side of the precipitation separation tank 15 is communicated with the precipitation separation tank 15 through a pipeline. The adjacent ozone contact tanks 21, the ozone catalytic oxidation tank 22 and the ozone decomposition tank 23 of the ozone catalytic oxidation tank 22 are communicated through overflow channels 25, and the overflow channels 25 are arranged on the upper part of the common chamber wall of the adjacent ozone contact tanks 21 or the common chamber wall of the ozone contact tanks 21 and the ozone catalytic oxidation tank 22 or the common chamber wall of the ozone catalytic oxidation tank 22 and the ozone decomposition tank 23. The bottom parts of the ozone contact tank 21 and the ozone catalytic oxidation tank 22 are both provided with an ozone aeration disc 24, and the ozone aeration disc 24 is connected with an ozone source.

A catalyst layer 221 is arranged above the ozone aeration disc 24 of the ozone catalytic oxidation tank 22, and the upper end of the ozone decomposition tank 23 is communicated with a tail gas destructor 26. The concentrated brine gets into ozone contact tank 21, ozone catalytic oxidation pond 22 and ozonolysis pond 23 from outlet channel 154 in proper order, and the concentrated brine contacts with the ozone of the aeration of ozone aeration dish 24, utilizes the strong oxidizing property of ozone to get rid of the very little partly COD in the concentrated brine, can also make the COD of aquatic difficult degradation carry out the open loop chain scission, becomes the COD that microorganism can be degradable on next step, can reduce the carbon source input volume of denitrification unit 4. The setting of catalyst layer 221 in the ozone catalytic oxidation pond 22 makes the ozone utilization ratio in the ozone catalytic oxidation pond 22 higher, and the effect is better, then the strong brine gets into ozone decomposition pond 23, and ozone decomposition pond 23 provides necessary reaction time for ozone can have sufficient time to decompose, and unnecessary ozone gets into in the tail gas destructor 26.

The ozone contact tank 21 and the ozone catalytic oxidation tank 22 are respectively provided with a second baffle 211 to form an aeration zone 212 and a buffer zone 213, the aeration zone 212 and the buffer zone 213 are sequentially arranged along the flowing direction of the concentrated brine, the ozone aeration disc 24 is positioned in the aeration zone 212, and the lower end surface of the second baffle 211 is higher than the bottom wall of the ozone catalytic oxidation unit to form a flow passage 214 for the concentrated brine to flow through. So set up, strong brine gets into aeration zone 212 and buffer zone 213 in proper order, and in aeration zone 212, the ozone in ozone aeration dish 24 gets into strong brine, and the setting of buffer zone 213 provides necessary reaction time for ozone can have sufficient time to dissolve in the water, then gets into next ozone contact tank 21 or ozone catalytic oxidation pond 22 in.

The air stripping unit 3 comprises an air stripping tank 31, the bottom of the ozone decomposition tank 23 and the bottom of the air stripping tank 31 are communicated through a pipeline, an air stripping piece used for introducing nitrogen into the strong brine in the air stripping tank 31 is arranged in the air stripping tank 31, the air stripping piece comprises a nitrogen aeration pipe 32 arranged at the bottom of the air stripping tank 31, the nitrogen aeration pipe 32 is connected with a nitrogen source, and a plurality of air holes are formed in the upper end face of the nitrogen aeration pipe 32. The upper end of the stripping pool 31 is connected with a vent pipe 33 communicated with the atmosphere. When the strong brine flows into in the blow-off pond 31, nitrogen gas aeration pipe 32 lets in nitrogen gas to the strong brine in the blow-off pond 31, nitrogen gas lets in the strong brine and makes the oxygen molecule in the strong brine pass the gas-liquid phase interface and shift to the gas phase, thereby realize that dissolved oxygen takes place reverse mass transfer phenomenon in aqueous, thereby can follow the stripping in the strong brine with the dissolved oxygen in the strong brine, reduce the dissolved oxygen in aqueous fast, and can reduce the dissolved oxygen of aquatic to 0.5mg/L, satisfy the dissolved oxygen demand of denitrification unit 4, blow off and let in nitrogen gas in the pond 31 and realize the strip back of dissolved oxygen, nitrogen gas and oxygen are arranged to the air from breather pipe 33. The operation is more convenient and faster, the cost is lower, and the treatment effect is better.

As shown in fig. 3, the denitrification unit 4 and the MBBR aerobic unit 5 in the present invention are both implemented by using a moving bed biofilm reactor, which includes a reactor body and a suspended carrier disposed in the reactor body, and the main principle is that the suspended carrier in the reactor body moves in the reactor body through mechanical stirring or aeration operation, the suspended carrier forms a biofilm in the moving process, a suspended filler is formed on the biofilm, and the suspended filler has a density similar to that of water, so as to ensure that the suspended filler is suspended in water.

The difference lies in that the moving bed biofilm reactor adopted by the denitrification unit 4 is an anaerobic moving bed biofilm reactor, the moving bed biofilm reactor adopted by the MBBR aerobic unit 5 is an aerobic moving bed biofilm reactor, therefore, the anaerobic moving bed biofilm reactor adopted by the denitrification unit 4 also comprises a stirrer 41, the suspended carrier in the reactor body moves in the reactor body through mechanical stirring, the suspended filler attached with the biofilm in the reactor reaches a certain thickness, an anoxic/anaerobic microenvironment is formed in the biofilm, and the denitrifying bacteria can perform the denitrification process. Referring to fig. 4, the moving bed biofilm reactor adopted by the MBBR aerobic unit 5 further includes an ozone aeration disc 24, the suspended carrier in the water moves through the ozone aeration disc 24, and the dissolved oxygen in the water is above 2mg/L by the ozone aeration disc 24, which is beneficial to the removal and degradation of the organic matters in the concentrated brine by the aerobic bacteria.

The moving bed biofilm reactor is the prior art, the structure of the moving bed biofilm reactor is not specifically explained any more in the embodiment, the defects that a fixed bed reactor needs regular back flushing, a fluidized bed reactor needs carrier fluidization, a submerged biofilter needs cleaning of filter materials and replacement of an aerator are overcome by adopting the moving bed biofilm reactor, and the characteristics of impact load resistance, low sludge yield and long sludge age of a traditional biofilm method are also kept. The moving bed biofilm reactor technology is adopted, suspended fillers are arranged in a reactor body, microorganisms grow and are attached to the suspended fillers, the treatment capacity is stronger compared with that of a traditional activated sludge process, intercepting screens are arranged on the upper portions of a denitrification unit 4 and an MBBR aerobic unit 5 to prevent the fillers from losing, larger microorganism amount in the treatment unit can be ensured, and the strong brine treatment capacity is stronger.

Because most of denitrifying bacteria for denitrification are heterotrophic denitrifying bacteria, a carbon source is usually added into the denitrifying unit 4, and therefore, a plurality of carbon source adding pipes 42 are also arranged on one side, close to the degassing unit, of the denitrifying unit 4, so that the added carbon source can be added in a multi-point adding mode, and the utilization rate of the carbon source and the denitrification efficiency can be fully improved.

As shown in fig. 4, the second efficient precipitation unit 6 includes a phosphorus removal reaction tank 61 communicated along the flow direction of the concentrated brine, the phosphorus removal reaction tank 61 is communicated with a flocculation tank 14, the flocculation tank 14 is communicated with a precipitation separation tank 15, the phosphorus removal reaction tank 61, the flocculation tank 14 and the precipitation separation tank 15 are sequentially communicated along the flow direction of the concentrated brine, the phosphorus removal reaction tank 61 is provided with a phosphorus removal agent adding pipe 611 for adding a phosphorus removal agent, a third baffle 62 is arranged in the phosphorus removal reaction tank 61, and the lower end surface of the third baffle 62 is higher than the bottom of the phosphorus removal reaction tank for the concentrated brine to enter the flocculation tank 14. The structures of the flocculation tank 14 and the sedimentation separation tank 15 are the same as the results of the flocculation tank 14 and the sedimentation separation tank 15 in the first high-efficiency sedimentation unit 1, the bottom of the phosphorus removal reaction tank 61 is communicated with the flocculation tank 14 through the drainage tube 18, one end of the drainage tube 18 extends into the bell-mouth-shaped side of the draft tube 142, and the water outlet channel 154 of the sedimentation separation tank 15 in the second high-efficiency sedimentation unit 6 is communicated with the first water outlet pipe 7.

Further, this petrochemical RO strong brine processing system still includes carbon filter tank (not shown in the figure), and carbon filter tank includes water inlet and delivery port, and the water inlet passes through the pipeline intercommunication with the outlet channel 154 of the sedimentation tank of the high-efficient precipitation unit 6 of second, and the delivery port is connected with the second outlet pipe. The filter material in the carbon filter tank is activated carbon, the carbon filter tank can adsorb COD which can not be degraded by the organisms in the water, and when the COD of the strong brine discharged by the water outlet channel 154 of the second high-efficiency precipitation unit 6 reaches the standard, the strong brine directly passes through the first water outlet pipe 7; if strong brine COD is not up to standard, then go out ditch 154 strong brine and carry out the active carbon filtration through pipeline entering carbon canister in, adsorb the COD that can not pass through biodegradable in the aquatic to guarantee that it is up to standard to go out water COD, SS, total nitrogen, total phosphorus and the hardness of strong brine that finally discharges are all up to standard.

The invention also provides a method for realizing petrochemical RO strong brine treatment by adopting the petrochemical RO strong brine treatment system, which comprises the following steps:

and (3) hardness removal: RO strong brine enters the hardness removal reaction tank 12 through a water inlet pipe 111, alkaline substances are added into the hardness removal reaction tank 12, the alkaline substances can be sodium hydroxide or other alkaline substances, the sodium hydroxide is taken as an example for explanation in the invention, the stirring is carried out, the pH value in the hardness removal reaction tank 12 is kept above 10.0, the reaction time of the strong brine in the hardness removal reaction tank 12 is controlled to be 2-3min, the sodium hydroxide reacts with magnesium ions in water to generate magnesium hydroxide precipitates, the sodium hydroxide reacts with bicarbonate ions and calcium ions in the water to generate calcium carbonate precipitates, so that the hardness in the water is reduced, and the strong brine enters a coagulation tank 13 after the reaction is finished;

coagulation: adding a coagulant into the coagulation tank 13, keeping the concentration of the coagulant in the coagulation tank 13 at 30-100mg/L, preferably 100mg/L, controlling the reaction time of concentrated brine in a coagulation area at 2-3min, mixing pollutants and suspended matters in calcium carbonate precipitate, magnesium hydroxide precipitate and concentrated brine formed in the step of hardness removal with the coagulant to form small alum flocs, and then entering the flocculation tank 14 of the first high-efficiency precipitation unit 1;

primary flocculation: adding a flocculating agent into the flocculation tank 14 of the first high-efficiency precipitation unit 1, keeping the concentration of the flocculating agent in the flocculation tank 14 at 0.5-2.0mg/L, preferably 0.5mg/L, controlling the reaction time of concentrated brine in the flocculation area at 6-12min, taking the flocculating agent and sludge reflowing from the precipitation separation tank of the first high-efficiency precipitation unit 1 as crystal nuclei, and aggregating the concentrated brine carrying small alum flowers to form compact large alum flowers and then feeding the compact large alum flowers into the precipitation separation tank 15 of the first high-efficiency precipitation unit 1;

primary precipitation separation: the strong brine containing alum blossom in the primary flocculation step enters a precipitation separation tank of the precipitation separation tank 15, then enters an inclined tube separation zone 159 for mud-water separation, and clear water enters a water outlet groove 153, then is converged and flows out of a water outlet channel 154, and enters an ozone catalytic oxidation unit 2; sludge formed by alum floc falls on the bottom of the sedimentation separation tank 15 and enters the sludge collection hopper 151 under the action of the sludge scraper 152, so that on one hand, the sludge circulating pump 157 is controlled to return the sludge to the drainage tube 18 and enter the flocculation tank 14, the sludge circulating pump 157 is regulated to make the sludge return flow amount be 3-6% of the water inlet flow amount, and on the other hand, the sludge discharge pump 158 is controlled to discharge redundant sludge;

ozone oxidation: the concentrated brine flowing out of the water outlet channel 154 enters the ozone contact tank 21, the ozone aeration disc 24 in the ozone contact tank 21 is aerated, the retention time of the concentrated brine in the ozone contact tank 21 is controlled to be 15-25min, preferably 20min, then the concentrated brine enters the ozone catalytic oxidation tank 22, the retention time of the concentrated brine in the ozone catalytic oxidation tank 22 is controlled to be 25-35min, preferably 30min, the concentrated brine in the ozone contact tank 21 and the ozone catalytic oxidation tank 22 is fully contacted with ozone and then enters the ozone decomposition tank 23, the concentrated brine is retained in the ozone decomposition tank 23 for 25-35min, preferably 30min, the ozone is fully decomposed, the undecomposed ozone enters the ozone tail gas destructor 26, and the concentrated brine enters the blow-off tank 31;

nitrogen stripping: after the strong brine enters the stripping tank 31, nitrogen is introduced into the strong brine in the stripping tank 31 through the nitrogen aeration pipe 32, and the gas-water ratio of the nitrogen aerated by the nitrogen aeration pipe 32 to the strong brine (namely the ratio of the amount of the introduced nitrogen per hour to the amount of the introduced water per hour) is controlled to be (1-5): 1, preferably 3:1, and reducing the dissolved oxygen in the water to below 0.5 mg/L;

MBBR treatment: the strong brine subjected to nitrogen stripping enters a denitrification unit 4 for denitrification treatment, then enters an MBBR aerobic unit 5, effectively removes the residual carbon source added in the denitrification unit and the COD originally existing in the water, effectively removes the COD in the water, and then enters a second efficient precipitation unit 6;

dephosphorization and precipitation: the concentrated brine firstly enters a phosphorus removal reaction tank 61, phosphorus removal agents are added into the phosphorus removal reaction tank 61, the reaction time of the concentrated brine in the phosphorus removal reaction tank 61 is controlled to be 2-3min, then the concentrated brine enters a flocculation tank 14 in a second high-efficiency precipitation unit 6, a flocculating agent is added into the flocculation tank 14 in the second high-efficiency precipitation unit 6, the concentration of the flocculating agent in the flocculation tank 14 is maintained to be 0.5-2.0mg/L, preferably 0.5mg/L, the retention time of the concentrated brine in the flocculation tank 14 is controlled to be 6-12min, a flocculating agent and sludge reflowing in a precipitation separation tank 15 of the second high-efficiency precipitation unit 6 are used as crystal nuclei to form alum floc, then the alum floc enters a precipitation separation tank 15 of the second high-efficiency precipitation unit 6 to carry out mud-water separation, clear water flows out from a water outlet channel 154 of the precipitation separation tank 15, the alum floc enters a sludge collection hopper 151 of the precipitation separation tank to carry out mud discharge, after the treatment of the step, the suspended matters, the total nitrogen and the total phosphorus in the strong brine reach the standard;

filtering with activated carbon: if the COD value of the treated concentrated brine flowing out of the water outlet channel 154 of the second high-efficiency precipitation unit 6 in the dephosphorization precipitation step reaches the standard, the treated concentrated brine is directly discharged from the water outlet channel 154 of the second high-efficiency precipitation unit 6, and if the COD value of the treated concentrated brine flowing out of the water outlet channel 154 of the second high-efficiency precipitation unit 6 in the dephosphorization precipitation step does not reach the standard, the treated concentrated brine flowing out of the water outlet channel 154 of the second high-efficiency precipitation unit 6 in the dephosphorization precipitation step enters a carbon filter tank, is filtered by activated carbon and then discharged, and adsorbs COD, which cannot pass through biodegradation, in the concentrated brine, so that the COD of the effluent reaches the standard.

The coagulant in the invention can be polyaluminium chloride or Polyferric (PAFC) or a coagulant commonly used in the field, the flocculant can be polyacrylamide or other flocculants commonly used in the field, and the phosphorus removing agent can be ferric salt, aluminum salt or phosphorus removing agents commonly used in the field.

Application example 1

The petrochemical RO strong brine treatment system and the petrochemical RO strong brine treatment method are applied to a certain petrochemical RO strong brine treatment project, the water quality inlet and outlet requirements are shown in the following table 1, and the following detection units are mg/L.

Table 1:

quality of water

SS

COD

Ammonia nitrogen

Total nitrogen

Total phosphorus

Total hardness (as CaCO)₃Meter)

Total alkalinity (as CaCO)₃Meter)

Quality of inlet water

35

200

5.0

30

2

1000

500

Quality of effluent water

≤5

≤30

≤3.0

≤10

≤0.3

≤400

≤100

The application specific operation is as follows:

and (3) hardness removal: RO strong brine enters the hardness removal reaction tank 12 through a water inlet pipe 111, sodium hydroxide is added into the hardness removal reaction tank 12, stirring is carried out, the concentration of the sodium hydroxide in the hardness removal reaction tank 12 is kept at 350mg/L, the reaction time of the strong brine in the hardness removal reaction tank 12 is controlled to be 3min, and the strong brine enters a coagulation tank 13 after the reaction is finished;

coagulation: adding a coagulant PAFC into the coagulation tank 13, keeping the concentration of the coagulant in the coagulation tank 13 at 100mg/L, controlling the reaction time of concentrated brine in the coagulation tank 13 to be 3min, mixing pollutants and suspended matters in calcium carbonate precipitate, magnesium hydroxide precipitate and concentrated brine formed in the step of hardness removal with the coagulant to form small alum flocs, and then entering the flocculation tank 14;

primary flocculation: adding polyacrylamide serving as a flocculating agent into a flocculation tank 14 of the first high-efficiency precipitation unit 1, keeping the concentration of the flocculating agent in the flocculation tank 14 at 0.5mg/L, controlling the reaction time of concentrated brine in a flocculation area to be 10min, taking the flocculating agent and sludge flowing back from a precipitation separation tank 15 of the first high-efficiency precipitation unit 1 as crystal nuclei, and aggregating the concentrated brine carrying small alum flowers to form compact large alum flowers and then feeding the compact large alum flowers into the precipitation separation tank 15 of the first high-efficiency precipitation unit 1;

primary precipitation separation: the wastewater containing alum blossom in the primary flocculation step enters a sedimentation separation tank 15 of a first high-efficiency sedimentation unit 1, then enters an inclined tube separation zone 159 for mud-water separation, and clear water enters a water outlet groove 153, then is converged and flows out from a water outlet channel 154, and then enters an ozone catalytic oxidation unit 2; sludge formed by alum floc falls on the bottom of the sedimentation separation tank 15 and enters the sludge collection hopper 151 under the action of the sludge scraper 152, on one hand, the sludge discharge pump 158 is controlled to discharge sludge, on the other hand, the sludge circulating pump 157 is controlled to return the sludge to the drainage tube 18 and enter the flocculation tank 14 of the first high-efficiency sedimentation unit 1, and the sludge circulating pump 157 is regulated and controlled to ensure that the sludge return flow is 5% of the water inflow;

ozone oxidation: the strong brine flowing out of the water outlet channel 154 enters the ozone contact tank 21, the ozone aeration disc 24 in the ozone contact tank 21 is aerated, the retention time of the strong brine in the ozone contact tank 21 is controlled to be 20min, then the strong brine enters the ozone catalytic oxidation tank 22, the retention time of the strong brine in the ozone catalytic oxidation tank 22 is controlled to be 30min, the strong brine is fully contacted with ozone in the ozone contact tank 21 and the ozone catalytic oxidation tank 22 and then enters the ozone decomposition tank 23, the strong brine is retained in the ozone decomposition tank 23 for 30min, so that the ozone and the strong brine are fully mixed and reacted, then the unreacted ozone enters the ozone tail gas destructor 26, and the strong brine enters the blow-off tank 31;

nitrogen stripping: after the strong brine got into the blowdown pond 31, let in nitrogen gas through nitrogen gas aeration pipe 32 to the strong brine in the blowdown pond 31, the air water ratio of nitrogen gas of control nitrogen gas aeration pipe 32 aeration and strong brine is 3:1, detecting that the dissolved oxygen of the concentrated brine entering the stripping tank 31 is 20mg/L, and the dissolved oxygen of the effluent in the stripping tank 31 after treatment is 0.3 mg/L;

MBBR treatment: the strong brine subjected to nitrogen stripping enters a denitrification unit 4 for denitrification treatment, then enters an MBBR aerobic unit 5 for removing organic matters by using aerobic bacteria, and then enters a second efficient precipitation unit 6;

dephosphorization and precipitation: the concentrated brine firstly enters a phosphorus removal reaction tank 61, phosphorus removal agent aluminum sulfate is added into the phosphorus removal reaction tank 61, the concentration of the phosphorus removal agent in the phosphorus removal reaction tank 61 is maintained at 30 mg/L, the reaction time of the concentrated brine in the phosphorus removal reaction tank 61 is controlled at 3min, then the concentrated brine enters a flocculation tank 14 in a second high-efficiency precipitation unit 6, flocculating agent polyacrylamide is added into the flocculation tank 14 in the second high-efficiency precipitation unit 6, the concentration of a flocculating agent in the flocculation tank 14 is maintained at 0.5mg/L, the retention time of the concentrated brine in the flocculation tank 14 is controlled at 10min, a flocculating agent and sludge which flows back in a precipitation separation tank 15 of the second high-efficiency precipitation unit 6 are used as crystal nuclei to form large alum flocs, then the sludge and water are separated in the precipitation separation tank 15 of the second high-efficiency precipitation unit 6, clear water flows out from a water outlet channel 154 of the precipitation separation tank 15, the large alum flocs enter a sludge collection hopper 151 of the precipitation separation tank 15 to carry out sludge discharge and, the concentrated brine in the outlet channel 154 of the precipitation separation tank 15 was measured, and the measurement results are shown in Table 2 below, where the unit of each measurement index is mg/L.

Table 2:

quality of water	SS	COD	Ammonia nitrogen	Total nitrogen	Total phosphorus	Total hardness (as CaCO)₃Meter)	Total alkalinity (as CaCO)₃Meter)
								Quality of effluent water	3	26	0.2	3.5	0.15	135	90

The detection result of the strong brine in the water outlet channel 154 of the second efficient precipitation unit 6 reaches the standard, and then the strong brine can be directly discharged through the first water outlet pipe 7 without the need of performing the active carbon filtration operation.

Application example 2

The above-mentioned petrochemical RO brine treatment project was treated in accordance with the method in application example 1, except that,

in the nitrogen stripping step: controlling the gas-water ratio of the nitrogen aerated by the nitrogen aeration pipe 32 to the strong brine to be 1: 1, detecting that the dissolved oxygen of the concentrated brine entering the stripping tank 31 is 15.3mg/L, and the dissolved oxygen of the effluent in the stripping tank 31 after treatment is 0.46 mg/L.

The concentrated brine in the outlet channel 154 of the second high efficiency precipitation unit 6 was measured, and the measurement results are shown in table 3 below, where the unit of each measurement index is mg/L.

Table 3:

quality of water	SS	COD	Ammonia nitrogen	Total nitrogen	Total phosphorus	Total hardness (as CaCO)₃Meter)	Total alkalinity (as CaCO)₃Meter)
								Quality of effluent water	3	25	0.1	3.6	0.13	130	90

Application example 3

in the nitrogen stripping step: controlling the gas-water ratio of the nitrogen aerated by the nitrogen aeration pipe 32 to the strong brine to be 5: 1, detecting that the dissolved oxygen of the concentrated brine entering the stripping tank 31 is 23.5mg/L, and the dissolved oxygen of the effluent in the stripping tank 31 after treatment is 0.21 mg/L.

The concentrated brine in the outlet channel 154 of the second high efficiency precipitation unit 6 was measured, and the measurement results are shown in table 4 below, where the unit of each measurement index is mg/L.

Table 4:

quality of water	SS	COD	Ammonia nitrogen	Total nitrogen	Total phosphorus	Total hardness (as CaCO)₃Meter)	Total alkalinity (as CaCO)₃Meter)
								Quality of effluent water	3	24	0.21	2.9	0.12	130	90

As can be seen from the above table, the dissolved oxygen in the concentrated salt water can be quickly and conveniently reduced through the arrangement of the stripping unit 3, so that the dissolved oxygen requirement of the denitrification unit 4 can be met, denitrification by denitrifying bacteria is facilitated, nitrate nitrogen in the concentrated salt water is converted into nitrogen to overflow, and the dissolved oxygen in the water is lower and lower along with the increase of the aeration amount of the nitrogen, and considering that when the gas-water ratio of the nitrogen to the water is 3:1, the dissolved oxygen in the water can reach 0.3 mg/L, the dissolved oxygen is lower, the aeration amount is increased, and the cost is increased, so that the gas-water ratio of the nitrogen to the water is preferably 3: 1. When the gas-water ratio of nitrogen to water provided by the invention is preferably (1-5): 1, the total nitrogen, total phosphorus, hardness, COD and SS of the final concentrated brine all reach the discharge standard, and particularly the total nitrogen is less than or equal to 10mg/L when the concentrated brine is discharged.

The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.

Claims

1. The utility model provides a petrochemical RO strong brine processing system which characterized in that: include along strong brine flow direction in proper order communicate be used for removing the first high-efficient precipitation unit (1), ozone catalytic oxidation unit (2) of hard suspended solid, blow off unit (3), denitrification unit (4), MBBR aerobic unit (5) and be used for the high-efficient precipitation unit (6) of second that the suspended solid was removed in the dephosphorization, first high-efficient precipitation unit (1) is connected with inlet tube (111), the high-efficient precipitation unit (6) of second is connected with first outlet pipe (7), blow off unit (3) including blowing off pond (31), it is used for blowing off the piece to blowing off that strong brine lets in nitrogen gas in blowing off pond (31) to be provided with in blowing off pond (31).

2. The petrochemical RO strong brine treatment system according to claim 1, characterized in that: blow and take off the piece including setting up blow nitrogen gas aeration pipe (32) of taking off pond (31) bottom, nitrogen gas aeration pipe (32) are connected with the nitrogen gas source, nitrogen gas aeration pipe (32) up end is provided with a plurality of air holes of crossing, blow and take off pond (31) upper end and be connected with breather pipe (33) with the atmosphere intercommunication.

3. The petrochemical RO strong brine treatment system according to claim 1, characterized in that: the first efficient precipitation unit (1) comprises a hardness removal reaction tank (12), a coagulation tank (13), a flocculation tank (14) and a precipitation separation tank (15) which are sequentially communicated along concentrated brine, wherein an alkali substance feeding pipe (121) is arranged in the hardness removal reaction tank (12), a coagulant feeding pipe (131) is arranged in the coagulation tank (13), and a flocculant feeding ring (141) is arranged in the flocculation tank (14);

a sludge collecting hopper (151) is arranged at the central part of the bottom of the sedimentation separation tank (15), a sludge scraper (152) for scraping bottom sludge into the sludge collecting hopper (151) is arranged on the sedimentation separation tank (15), an inclined tube separation zone (159) is arranged in the middle of the sedimentation separation tank, a plurality of water outlet grooves (153) are erected at the upper part of the sedimentation separation tank, water outlet channels (154) are communicated with the water outlet channels (154), and the water outlet channels (154) are communicated with the ozone catalytic oxidation unit (2);

the sludge collecting hopper (151) is communicated with a sludge circulating pipe (155) and a sludge discharging pipe (156), the sludge circulating pipe (155) is connected with a sludge circulating pump (157) and communicated with the flocculation tank (14), the sludge circulating pump (157) is positioned between the sludge collecting hopper (151) and the flocculation tank (14), and the sludge discharging pipe (156) is connected with a sludge discharging pump (158).

4. The petrochemical RO strong brine treatment system according to claim 1, characterized in that: ozone catalytic oxidation unit (2) include along a plurality of ozone contact tank (21), ozone catalytic oxidation pond (22) and ozone decomposition pond (23) that strong brine flow direction communicates in proper order, ozone contact tank (21) and ozone catalytic oxidation pond (22) bottom all are provided with ozone aeration dish (24), ozone aeration dish (24) top of ozone catalytic oxidation pond (22) still is provided with catalyst layer (221), ozone decomposition pond (23) upper end intercommunication has tail gas destructor (26).

5. The petrochemical RO strong brine treatment system according to claim 3, characterized in that: the high-efficient precipitation unit of second (6) is including dephosphorization reaction tank (61), dephosphorization reaction tank (61) is connected with and is used for throwing flocculating agent flocculation basin (14), flocculation basin (14) intercommunication has and is used for mud-water separation sedimentation tank (15), dephosphorization reaction tank (61) are provided with and are used for throwing dephosphorization medicament and add pipe (611), outlet channel (154) of the high-efficient precipitation unit of second (6) with first outlet pipe (7) intercommunication, dephosphorization reaction tank (61), flocculation basin (14) and sedimentation tank (15) communicate along strong brine flow direction in proper order.

6. The petrochemical RO strong brine treatment system according to claim 5, characterized in that: the system also comprises a carbon filter tank communicated with the second high-efficiency precipitation unit (6), one end of the carbon filter tank is communicated with a water outlet channel (154) of the second high-efficiency precipitation unit (6), and the other end of the carbon filter tank is connected with a second water outlet pipe for the outflow of the concentrated brine.

7. A petrochemical RO strong brine treatment method which is realized by adopting the petrochemical RO strong brine treatment system of claim 6 and comprises the following steps:

and (3) hardness removal: the RO strong brine enters a hardness removal reaction tank (12) of the first efficient precipitation unit (1), and alkaline substances are added into the hardness removal reaction tank (12) to remove calcium ions and magnesium ions in the RO strong brine, so that the hardness of the RO strong brine is reduced;

coagulation: adding a coagulant into the coagulation tank (13), mixing the calcium carbonate precipitate, the magnesium hydroxide precipitate and pollutants and suspended matters in the concentrated brine formed in the step of hardness removal with the coagulant to form small alum flocs, and feeding the small alum flocs into the flocculation tank (14) of the first high-efficiency precipitation unit (1);

primary flocculation: adding a flocculating agent into a flocculation tank (14) of the first high-efficiency precipitation unit (1), and allowing concentrated brine carrying small alum flocs in the flocculation tank (14) to aggregate to form dense large alum flocs and then enter a precipitation separation tank (15) of the first high-efficiency precipitation unit (1);

primary precipitation separation: after primary flocculation, strong brine carrying alum floc enters an inclined tube separation area (159) for sludge-water separation, clear water flows out of a water outlet channel (154) and enters an ozone catalytic oxidation unit (2), sludge formed by alum floc falls on the bottom of the sedimentation separation tank (15), and enters a sludge collection hopper (151) under the action of a sludge scraper (152);

catalyzing by ozone: the strong brine enters an ozone catalytic oxidation unit (2) to contact with ozone, and organic matters which are difficult to degrade in the strong brine are converted into organic matters which are easy to degrade;

nitrogen stripping: the strong brine enters a stripping tank (31), and nitrogen is introduced into the strong brine in the stripping tank (31) to reduce the dissolved oxygen in the water;

MBBR treatment: the strong brine after nitrogen stripping enters a denitrification unit (4) for denitrification by denitrifying bacteria, and then enters an MBBR aerobic unit (5) for removing organic matters by aerobic bacteria;

dephosphorization and precipitation: the method comprises the following steps that strong brine firstly enters a phosphorus removal reaction tank (61), phosphorus removal agents are added into the phosphorus removal reaction tank (61) to remove phosphorus in the strong brine, then the strong brine enters a flocculation tank (14) of a second efficient precipitation unit (6) to flocculate, then the strong brine enters a precipitation separation tank (15) in the second efficient precipitation unit (6) to separate mud from water, and clean water flows out of a first water outlet pipe (7) through a water outlet channel (154).

8. The method for treating the RO concentrated brine in the petrochemical industry according to claim 7, wherein: in the nitrogen stripping step, controlling the gas-water ratio of the introduced nitrogen to the concentrated brine to be (1-5): 1.

9. the method for treating the RO concentrated brine in the petrochemical industry according to claim 8, wherein: in the step of hard removing: adding alkaline substances into the hardness removal reaction tank (12), keeping the pH value in the hardness removal reaction tank (12) above 10.0, and controlling the reaction time of strong brine in the hardness removal reaction tank (12) to be 2-3 min;

in the coagulation step: adding a coagulant into the coagulation tank (13), keeping the concentration of the coagulant in the coagulation tank (13) at 30-100mg/L, and controlling the reaction time of strong brine in the coagulation tank (13) to be 2-3 min;

in the primary flocculation step: adding a flocculating agent into a flocculation tank (14) of the first high-efficiency precipitation unit (1), keeping the concentration of the flocculating agent in the flocculation tank (14) at 0.5-2.0mg/L, and controlling the reaction time of concentrated brine in the flocculation tank (14) to be 6-12 min;

in the dephosphorization precipitation step: and adding a phosphorus removal medicament into the phosphorus removal reaction tank (61), controlling the reaction time of the concentrated brine in the phosphorus removal reaction tank (61) to be 2-3min, adding a flocculating agent into the flocculation tank (14) in the second high-efficiency precipitation unit, maintaining the concentration of the flocculating agent in the flocculation tank (14) to be 0.5-2.0mg/L, and controlling the retention time of the concentrated brine in the flocculation tank (14) to be 6-12 min.

10. The method for treating the RO concentrated brine in the petrochemical industry according to claim 9, wherein: the method also comprises an active carbon filtering step, wherein if the COD value of the treated strong brine flowing out of the water outlet channel (154) of the second high-efficiency precipitation unit (6) in the dephosphorization precipitation step reaches the standard, the treated strong brine is directly discharged from the water outlet channel (154) of the second high-efficiency precipitation unit (6); and if the COD value of the treated concentrated brine flowing out of the water outlet channel (154) of the second high-efficiency precipitation unit in the dephosphorization precipitation step does not reach the standard, the concentrated brine flowing out of the water outlet channel (154) of the second high-efficiency precipitation unit (6) in the dephosphorization precipitation step enters a carbon filter tank to be filtered by activated carbon and then is discharged from a second water outlet pipe.