CN105585115A

CN105585115A - Method for reducing membrane pollution of high-salt wastewater MBR (membrane bioreactor) treatment system

Info

Publication number: CN105585115A
Application number: CN201610021642.9A
Authority: CN
Inventors: 吴兵; 张徐祥; 沈卓彦; 刘苏; 郭学超
Original assignee: Nanjing University
Current assignee: Nanjing University
Priority date: 2016-01-14
Filing date: 2016-01-14
Publication date: 2016-05-18

Abstract

The invention discloses a method for reducing membrane pollution of a high-salt wastewater MBR (membrane bioreactor) treatment system and belongs to a technology of water and wastewater treatment. The membrane pollution in a high-salt wastewater MBR is controlled with a ferric flocculant adding method. Trivalent ferric salt is directly added to the MBR, and certain flocculation is provided in an aeration manner, so that the trivalent ferric salt and macromolecule substances in a sludge mixing solution are sufficiently contacted to form flocculent bodies; besides, sodium bicarbonate is added to balance pH fluctuation caused by a flocculant, the pH is controlled in the range from 7 to 8, and a microbial phase is prevented from being affected by pH change. The method has the benefits that the membrane pollution speed of the MBR running for a long time can be effectively controlled, the cleaning period of the membrane is remarkably prolonged, and influence of high-salt impact on the activated sludge treatment effect is reduced to a certain extent. Moreover, the cost of the flocculation process is very low, and the running cost of the MBR is reduced.

Description

A kind of method that slows down high salt sewage MBR treatment system film pollution

Technical field

The present invention relates to a kind of method that high salt sewage MBR treatment system film pollutes that slows down, belong to water and technical field of waste water processing.

Background technology

China's shortage of water resources, spatial and temporal distributions inequality. Rationally utilizing under the prerequisite of limited water resources, Application and Development sewage reuse techuique has become the important channel of alleviating water resources problems. In recent years, membrane bioreactor (MembraneBioreactor, MBR) receive much concern as a kind of new and effective sewage disposal and technology of middle water recycle, it adopts membrane module to replace the second pond in traditional activated sludge process, both can effectively remove pollutant, biomass can be trapped in reactor again, extend sludge age. Compare the advantage such as MBR has that pollutants removal rate is high, water outlet can direct reuse, floor space is few, surplus sludge volume is few, system is reliable with traditional activated sludge process. But membrane pollution problem is the Main Bottleneck that restriction MBR applies.

Metal ion is the important water quality parameter of sewage. Study report and show, metal ions in sewage kind and change in concentration can change film and pollute process. Salt metalloid (Na⁺、K⁺) in the industrial wastewater of department's discharges such as chemical industry, pharmacy, food processing, concentration is higher, fluctuates larger, the physiological characteristic and the pollutant treatment effeciency that have been proved microorganism have material impact. In the MBR of high salt industrial waste water processing procedure, salt metalloid only has a positive charge, can not between EPS or between EPS and microorganism, produce bridging action, on the contrary, the increase of salt metal concentration can cause biological floe solution wadding, causes the increase of EPS and SMP in supernatant, and aggravation film pollutes. The impact of salt metalloid can affect the structure of mud flco in addition, stimulates Microbiological release EPS and SMP, and then worsens the filtrability of mud.

High volence metal ion (Fe³⁺Deng) electrically charged can the formation with electronegative carboxyl, hydroxyl, amino and acylamino-in EPS etc. of institute build bridge or complex compound, enhanced biological flocculation activity, can strengthen the flocculation ability of mud, improve the filtrability of mud, can promote mud to form the cake layer decelerating membrane pollution of short texture. Now, become and alleviated the Important Action that film pollutes to adding high volence metal ion monomer or condensate in MBR. But whether can be applied to slow down in high-salt wastewater MBR processing film pollution aspect for high volence metal ion and not carry out application, because in the time that different valence state metal ion coexists in MBR system, because EPS and SMP have the binding sites of different metal ion, make the interaction between coexistent metallic ion and influence process that film is polluted more complicated. Select suitable high volence metal ion monomer or condensate flocculant, determine that high volence metal ion can effectively reduce high salt and cause that film pollutes the valid density scope of aggravation, and the effective processing to high-salt wastewater is provided new process means by the scope of application of high-salt wastewater.

Summary of the invention

The mode by adding high volence metal ion flocculant of the object of the invention is is improved the characteristic of high-salt wastewater MBR mud mixed liquid, decelerating membrane pollution, improve the disposal ability to high salt sanitary wastewater, for the efficient operation of Membrane Bioreactor for Wastewater Treatment high-salt wastewater provides a kind of effective method.

Specifically, the present invention has adopted following technical scheme:

Slow down the method that high salt sewage MBR treatment system film pollutes, described method is applicable to integral type film biological reactor, it is characterized in that, described method comprises: the COD value of 1) adjusting sewage water inlet is 150-600mg/L, and ammonia nitrogen is 20-200mg/L; 2) in membrane bioreactor, directly drop into trivalent iron salt, wherein the amount of the trivalent iron salt that drops into is in mass, in ferric ion, with the ratio of contained sodium ion in sewage be 1-3:100; 3) in reactor, carry out that aeration provides turbulent flow so that molysite fully contacts formation flock with mud mixed liquid, wherein aeration rate is through controlling so that the amount of oxygen in water is 3-4mg/L; 4) regulate the pH in reactor, whole process pH is controlled between 7-8.

Preferably, in described adjusting reactor, the step of pH comprises to adding sodium acid carbonate in reactor and reduces owing to adding the pH that trivalent iron salt causes and raise.

In addition, input trivalent iron salt is to be selected from iron chloride, ferric sulfate or its combination.

As another preferred version, step 2) in ferric ion and sewage the mass ratio of contained sodium ion be 1.5-2:100.

Beneficial effect of the present invention is: can slow down the membrane fouling rate of the high salt sanitary sewage of Membrane Bioreactor for Wastewater Treatment, and the cleaning frequency of membrane component and prolong and the service life of film, thus reduce the expense of moving. In addition, can improve to a certain extent shock resistance and the impact recovery capability of microorganism to high salt sanitary sewage. Be conducive to promote the application of membrane bioreactor in sanitary sewage disposal, improve the utilization rate of water resource.

Brief description of the drawings

Fig. 1 is the structural representation of the present invention integral type MBR used.

Detailed description of the invention

The invention belongs to water and wastewater processing technology, control the film pollution in high salt sewage membrane bioreactor by adding the method for ferric flocculant. Adopt to the method that directly adds trivalent iron salt in membrane bioreactor, provide certain turbulence intensity by aeration mode, trivalent iron salt is fully contacted with the macromolecular substances in mud mixed liquid, formed flock. Add in addition sodium acid carbonate and carry out the pH fluctuation that balance flocculant causes, pH is controlled between 7-8, to prevent that pH from changing the impact on microbial. Beneficial effect of the present invention is effectively to control the membrane fouling rate of long-term operation membrane bioreactor, has obviously extended the cleaning frequency of film, has reduced to a certain extent high salinity and has impacted the impact on active sludge treatment effect. In addition, flocculation process expense is very low, is conducive to reduce the operating cost of membrane bioreactor.

For achieving the above object, set up integral type MBR, membrane material is hollow polyvinylidene fluoride film. Water body is influent COD 150-600mg/L, ammonia nitrogen 20-200mg/L.

MBR reactor is subject to after high sodium salt waste water (1%-3%), and film pollutes aggravation, adds the trivalent iron salt (FeCl of 100-750mg/L₃、Fe₂(SO₄)₃) come decelerating membrane pollution, the cleaning frequency of membrane component and prolong. The molysite adopting is ferric flocculant material common in water treatment, in having ensured effect, has also reduced processing cost expense.

In reactor, carrying out aeration provides turbulent flow, and molysite is fully contacted with mud mixed liquid, forms flock. The amount of aeration control oxygen in water is at 3-4mg/L.

In MBR running, interpolation sodium acid carbonate carrys out balance and adds the pH decline that molysite causes, whole process pH is controlled between 7-8.

Further describe the present invention in detail by specific embodiment below.

Embodiment 1

Build integral type film biological reactor, experimental provision is as Fig. 1. Adopt Kynoar (PVDF) hollow-fibre membrane, membrane aperture is 0.03um, and effective film area is 0.2mm². The discharge of designing of reactor is 0.66L/h, and aeration rate is 2L/min, and hydraulic detention time is 14 hours, is continuous aeration and continuous effluent, not spoil disposal in whole process of the test. The MBR cycle of operation is 60 days. Reactor influent COD is 300mg/L, and ammonia nitrogen is 25mg/L.

MBR is subject to 1.5% Na+ impact after, the clearance of COD is having salt group to be starkly lower than blank group, minimum clearance only has 7% left and right. The clearance of COD starts steady rise subsequently. With about 20 days, the clearance of COD is progressively stable, but its removal efficiency is still lower slightly compared with control group. Similar to the removal of COD, in the incipient stage of reactor operation, salt impacts larger on the impact of ammonia nitrogen removal, and the removal efficiency of ammonia nitrogen significantly reduces compared with control group, and minimum clearance only has 6%. But different, it is slower compared with COD that ammonia nitrogen removal recovers the normal time, probably needs the time of 30 days, ammonia nitrogen just starts to recover. And final removal efficiency in high salt group also lower than the reactor of control group. Aspect film pollution, Na⁺Obviously increased the speed that film pollutes, as after having moved 9 weeks, the transmembrane pressure of MBR, after operation 4 days, is respectively 27Kpa and 47Kpa in the value of control group and 1.5%NaCl group.

MBR reactor is standing Na⁺When impact, add FeCl₃, every day, dosage was 200mg/L. Discovery adds ferric flocculant group COD clearance and drops at most 80% left and right. Equally, ammonia nitrogen removal frank also has similar conclusion. When reactor moves approximately 10 days, COD comeback of removal rate is normal; While moving approximately 25 days, it is normal that ammonia nitrogen removal frank recovers. Aspect film pollution, the MBR reactor membrane fouling rate that adds iron chloride flocculant is starkly lower than high sodium salt waste water control group, suitable with Cardia Salt waste water control group membrane fouling rate.

Embodiment 2

MBR is subject to 2.5% Na+ impact after, the clearance of COD is there being salt group to be starkly lower than control group, with about 30 days, the clearance of COD is progressively stablized, ammonia nitrogen removal is similar to the removal of COD, and ammonia nitrogen removal to recover the normal time slower compared with COD. Aspect film pollution, Na⁺Obviously increase the speed that film pollutes.

MBR reactor is standing Na⁺When impact, add FeCl₃, every day, dosage was 500mg/L. Discovery adds ferric flocculant group COD clearance and drops at most 70% left and right. Equally, ammonia nitrogen removal frank also has similar conclusion. When reactor moves approximately 15 days, COD comeback of removal rate is normal; While moving approximately 30 days, it is normal that ammonia nitrogen removal frank recovers. Aspect film pollution, the MBR reactor membrane fouling rate that adds iron chloride flocculant is starkly lower than high sodium salt waste water control group, higher than Cardia Salt waste water control group membrane fouling rate.

With specific embodiment, embodiments of the present invention are described in detail by reference to the accompanying drawings above, but the invention is not restricted to above-mentioned embodiment, in the ken possessing at affiliated technical field those of ordinary skill, can also under the prerequisite that does not depart from aim of the present invention, make a variety of changes.

Claims

1. slow down the method that high salt sewage MBR treatment system film pollutes, described method is applicable to integral type film biological reactor, it is characterized in that, described method comprises: the COD value of 1) adjusting sewage water inlet is 150-600mg/L, and ammonia nitrogen is 20-200mg/L; 2) in membrane bioreactor, directly drop into trivalent iron salt, wherein the amount of the trivalent iron salt that drops into is in mass, in ferric ion, with the ratio of contained sodium ion in sewage be 1-3:100; 3) in reactor, carry out that aeration provides turbulent flow so that molysite fully contacts formation flock with mud mixed liquid, wherein aeration rate is through controlling so that the amount of oxygen in water is 3-4mg/L; 4) regulate the pH in reactor, whole process pH is controlled between 7-8.

2. as claimed in claim 1ly slow down the method that high salt sewage MBR treatment system film pollutes, it is characterized in that, in described adjusting reactor, the step of pH comprises to adding sodium acid carbonate in reactor and reduces owing to adding the pH that trivalent iron salt causes and raise.

3. the method that slows down high salt sewage MBR treatment system film pollution as claimed in claim 1, is characterized in that, input trivalent iron salt is to be selected from iron chloride, ferric sulfate or its combination.

4. as claimed in claim 1ly slow down the method that high salt sewage MBR treatment system film pollutes, it is characterized in that step 2) in ferric ion and sewage the mass ratio of contained sodium ion be 1.5-2:100.