CN103408184A

CN103408184A - Method for treating wastewater containing polyvinyl alcohol

Info

Publication number: CN103408184A
Application number: CN2013101762544A
Authority: CN
Inventors: 陈吕军; 孙伟华; 王建龙
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2013-05-14
Filing date: 2013-05-14
Publication date: 2013-11-27
Anticipated expiration: 2033-05-14
Also published as: CN103408184B

Abstract

The invention relates to a method for treating wastewater containing polyvinyl alcohol. The method comprises the following steps: performing ionizing radiation on the wastewater containing the polyvinyl alcohol to obtain pretreated water; and introducing the pretreated water into a membrane bioreactor and performing biological treatment.

Description

The treatment process that contains polyvinyl alcohol waste water

Technical field

The invention belongs to environmental protection technical field, be specifically related to a kind of organic wastewater with difficult degradation thereby treatment process, relate in particular to a kind for the treatment of process that contains polyvinyl alcohol waste water.

Background technology

Polyvinyl alcohol (PVA) is the important industrial chemicals of textile industry, and the dyeing and printing process in textile industry is still used the slurry that contains PVA in a large number at present, and the waste water that contains PVA in the destarch process is discharged easily environment is caused to severe contamination in a large number.In field of waste water treatment, bioremediation relies on equipment and the characteristics such as operational management is simple, working cost is low, environmental friendliness to have overwhelming superiority, and is a kind of effective scheme of generally acknowledging in the industry.Yet PVA belongs to the polymer of difficult for biological degradation, biological treatment is difficult to take effect to PVA waste water.By chemical Treatment PVA waste water (as Chinese patent CN100540481C and Chinese patent application CN102363543A), easily introduce other chemical substances, cause secondary pollution.

Chinese patent application CN101402476A discloses a kind of method that Ionizing Radiation is processed acrylic nitrile waste water of applying, its electron beam that mainly utilizes gamma-rays or rumbatron to produce carries out irradiation to acrylic nitrile waste water, excite or the generation of ionizing water molecule hydroxyl radical free radical, hydrated electron and hydrogen atom isoreactivity particle, promote the vinyl cyanide polymerization reaction take place to generate the polyacrylonitrile throw out that can remove by filtration, thereby realize the removal of vinyl cyanide.

Yet PVA itself has been a kind of polymer organic polymer, the processing problem of PVA waste water still not yet solves.In addition, for the processing problem of a large amount of trade effluents, use separately Ionizing Radiation to have the problems such as required radiation quantity is large, energy consumption is high, be difficult to be applied to Industrial Wastewater Treatment, need to be with the coupling of traditional biological water technology to reduce its running cost.

Summary of the invention

In view of this, necessaryly provide a kind for the treatment of process that can be applied to contain the trade effluent of polyvinyl alcohol.

A kind for the treatment of process that contains the waste water of polyvinyl alcohol comprises: the waste water that will contain polyvinyl alcohol carries out ionizing rays, obtains a pretreated water; And this pretreated water is passed into to membrane bioreactor carry out a biological disposal upon.

Beneficial effect of the present invention is: at first through ionizing rays, process by the waste water that will contain PVA, through membrane bioreactor, carry out a biological disposal upon again, can substantially remove the PVA in waste water, after long-time running, removal effect is stable, is applicable to being applied to Industrial Wastewater Treatment.And, owing to adopting the ionizing rays processing to combine with Membrane Bioreactor for Wastewater Treatment, make ionizing rays process required radiation dose less, reduced the radiation energy consumption.

The accompanying drawing explanation

Fig. 1 is the process schematic diagram of the embodiment of the present invention method of wastewater treatment that contains PVA.

Fig. 2 is the first domestication stage Inlet and outlet water COD temporal evolution data plot.

Fig. 3 is the first domestication stage Inlet and outlet water COD clearance temporal evolution data plot.

Fig. 4 is water outlet COD, COD clearance and the former COD temporal evolution data plot that contains the waste water of PVA after 12 kGy electron beam irradiations.

Fig. 5 be formerly contain the COD of the waste water of PVA, water outlet COD and through the water outlet COD temporal evolution data plot of electron beam irradiation-MBR coupling technique bulk treatment after 12 kGy electron beam irradiations.

Fig. 6 is the water outlet COD clearance through electron beam irradiation-MBR coupling technique bulk treatment.

The main element nomenclature

Electron beam irradiation device	10
		Rumbatron	12
The lower power system of bundle	14
		Membrane bioreactor	20
Reactive tank	202
		Membrane module	204
Water-in	206
		Water outlet	208
Active sludge	210
		Aeration plate	212
Overflow port	214
		Peristaltic pump	30
Water reservoir	40

Following embodiment further illustrates the present invention in connection with above-mentioned accompanying drawing.

Embodiment

Below in conjunction with the accompanying drawings and the specific embodiments the method for wastewater treatment of the PVA of containing provided by the invention is described in further detail.

Refer to Fig. 1, the embodiment of the present invention provides the treatment process of the waste water of a kind of PVA of containing, and it comprises the following steps:

S1, the waste water that will contain PVA carries out ionizing rays, obtains a pretreated water; And

S2, pass into membrane bioreactor (MBR) by this pretreated water and carry out a biological disposal upon.

The method is ionizing rays-biological treatment coupled method, and the waste water that namely this is contained to PVA is first processed through ionizing rays, then carries out a biological disposal upon by membrane bioreactor.

Particularly, in step S1, this ionizing rays can be gamma Rays, electron beam irradiation or X-radiation.Wherein, gamma-rays can pass through ⁶⁰Co or ¹³⁷The Cs radionuclide decay produces; Electron beam and X ray can obtain by the rumbatron device.

When adopting gamma-rays to carry out radiation, can be further comprising the steps: this waste water that contains PVA is put into to radiation-proof; This radiation-proof is placed in to the gamma Rays district and carries out gamma Rays, the gamma-rays dose rate of this radiation zone can adopt ferrous sulfate dosimeter (Fricke quantimeter) to demarcate and monitoring.

Electron beam irradiation device 10 generally includes rumbatron 12, the lower power system 14 of bundle and Controlling System (not shown).Rumbatron 12 is for generation of electronics and make electronics accelerate and draw, form an electron beam irradiation district, the lower power system 14 of bundle is transmitted this electron beam irradiation district of process to accept electron beam irradiation for the waste water that will contain PVA, and Controlling System is for controlling lower power system 14 collaborative works of this rumbatron 12 and bundle.When adopting electron beam to carry out radiation, can be further comprising the steps: the electron beam irradiation district by rumbatron 12 carries out electron beam irradiation with the continuous fluid form by this waste water that contains PVA.This waste water that contains PVA can descend the continuous electron beam irradiation district that passes through this rumbatron of power system 14 by bundle.Particularly, this waste water that contains PVA passes through the electron beam irradiation district of this rumbatron with the form of moisture film, basic vertical this water film surface of the radiation direction of this electron beam.Preferably, the water film thickness by the electron beam irradiation district is no more than the penetration range of electron beam in water, and in one embodiment, this water film thickness is no more than 30 millimeters.The doses of electron beam radiation rate of this radiation zone can adopt film dosage sheet (B3, GEX) to demarcate and monitoring.

Preferably, in the waste water of the handled PVA of containing, the concentration of PVA is 50 mg/L to 110 mg/L.Because PVA is the extremely difficult organism be biodegradable, this contains the biochemical oxygen demand (BOD) of waste water of PVA and the ratio (BOD of chemical oxygen demand (COD) ₅/ COD) all much smaller than 0.3.(radiation dose of namely accepting on the irradiated material unit mass, the kGy of unit=kJ/kg) are greater than 3 kGy to the unit radiation dose that this waste water that contains polyvinyl alcohol is accepted by ionizing rays.Preferably, the unit radiation dose of this ionizing rays is for being greater than 6 kGy and being less than or equal to 12 kGy.

In step S2, this membrane bioreactor 20 mainly comprises reactive tank 202, is placed in membrane module 204 and active sludge 210, water-in 206 and the water outlet 208 of reactive tank 202, also can further comprise aeration plate 212 and overflow port 214 in addition.This water-in 206 is be used to inputting pending waste water, and this water outlet 208 is be used to exporting the water after processing.The kind of this active sludge 210 is restriction not, can be aerobic activated sludge or anaerobic activated sludge.This membrane module 204 can be flat, tubular type, spiral or tubular fibre formula.The material of this membrane module 204 is organic polymer, can be poly(vinylidene fluoride) (PVDF), polyethylene (PE), polyethylene sulfone (PES), polysulfones (PS) or polyacrylonitrile (PAN).When the membrane module 204 of this membrane bioreactor 20 is the tubular fibre formula, the water outlet 208 of this membrane bioreactor 20 is connected with an end of the hollow fiber film thread of this membrane module 204, this water-in 206 is connected with this reactive tank 202, thereby make this pretreated water flow into film silk inside from the tube wall through the film silk outside the film silk, and flow out through water outlet 208.The other end of this hollow fiber film thread is connected with this aeration plate 212.In one embodiment, this reactive tank 202 and inner hollow fiber film thread vertically arrange, and this aeration plate 212 is arranged at the bottom of this reactive tank 202, and is connected with the lower end of hollow fiber film thread.

Particularly, the water-in of this membrane bioreactor 206 can be connected to power system 14 under the bundle of electron beam irradiation device 10 by pipeline, and by peristaltic pump 30, drive these pretreated waters and flow into these membrane bioreactors 20 from this electron beam irradiation device 10.

Before this step S2, can further comprise the activated sludge acclimatization step.For the waste water of avoiding containing PVA brought thump to microorganism, before PVA waste water or pretreated water are passed into to membrane bioreactor 20, can first with the first domestication waste water, tame the active sludge 210 in membrane bioreactor 20.Biochemical oxygen demand (BOD) (the BOD of this first domestication waste water ₅) with the ratio of chemical oxygen demand (COD) (COD), i.e. BOD ₅/ COD is greater than 0.3.This first domestication waste water does not contain PVA, BOD ₅/ COD is greater than 0.3, for being easy to biodegradable waste water.

Particularly, this activated sludge acclimatization step can comprise: before the water-in by this membrane bioreactor is connected to electron beam irradiation device 10, first this water-in 206 is connected to a domestication wastewater disposal basin by pipeline, and make the first domestication waste water pass into this membrane bioreactor 20 by peristaltic pump 30, active sludge 210 is tamed, until the COD value stabilization of the water after processing.

Further, for obtaining better taming effect, can successively adopt the first domestication waste water and the second domestication waste water to carry out the gradient domestication to the active sludge 210 in membrane bioreactor 20, namely first use BOD ₅/ COD value be greater than 0.3 first the domestication waste water carry out first the domestication stage domestication, after system stability, use again BOD ₅/ COD value be less than 0.3 second the domestication waste water carry out second the domestication stage domestication.Preferably, this second domestication waste water is that a domestication obtains after ionizing rays is processed with the waste water that contains PVA.When this ionizing rays was electron beam irradiation, this second domestication waste water can be directly from output this electron beam irradiation device 10.The ionizing rays amount that this second domestication waste water is accepted is 3 kGy to 6 kGy, is preferably 6 kGy.The PVA concentration that this domestication use contains the waste water of PVA is preferably and is less than or equal to 100 mg/L.

Because the nitrogen content of the waste water that contains PVA itself is low, and microbial growth is except needing the macroelement such as carbon, nitrogen, phosphorus, also need the trace elements such as potassium, calcium, magnesium, aforesaid method can further comprise the step of throwing in aid nutrition liquid, this aid nutrition liquid can be thrown in to the waste water that contains PVA, also can throw in to this pretreated water.This aid nutrition liquid contains at least a in the elements such as nitrogen, potassium, calcium and magnesium.

Embodiment

This concentration that contains the waste water of PVA that the present embodiment adopts is 100mg/L, and the COD value is 211.7 ± 26.3 mg/L, BOD ₅Value is 20.9 mg/L, BOD ₅/ COD is 0.09, belongs to the extremely difficult organic waste water be biodegradable.This BOD ₅Value is used BOD determinator (BODTrak II, HACH), adopts the Hash standard testing process that U.S. HACH company provides to measure; The COD value is used the HACH digital reactor of DRB200 type and the portable colorimeter of HACH DR890, and colorimetric method for determining is cleared up in micro-backflow of adopting HACH company to provide.This polymerization degree that contains PVA in the waste water of PVA is 1750 ± 50, and molecular weight is 74800 ~ 79200.

For promoting microbial growth in biological treatment step, to manually adding volume ratio during this contains the waste water of PVA, be at first 0.1 ‰ aid nutrition liquid, this aid nutrition liquid comprises nutritive substance and solvent, the composition of this nutritive substance is as shown in table 1.

Table 1

Nutritive substance	Content (g/L)
		K ₂HPO ₄	8.40
KH ₂PO ₄	2.80
		MgSO ₄	1.32
NH ₄ Cl	150
		NaNO ₃	7.2
FeCl ₃	0.03
		CaCl ₂	0.8
CuCl ₂·4H ₂O	0.02
		MnCl ₂·4H ₂O	0.04
CoCl ₂·6H ₂O	0.26
		Folic acid	0.0002
Nicotinic acid	0.00069

The membrane module 204 of the membrane bioreactor 20 of the present embodiment adopts the tubular fibre formula, comprises a plurality of PVDF hollow fiber film threads, every film filament length 350 mm, internal diameter 1.2 mm, external diameter 1.8 mm, membrane filtration aperture 0.02 μ m.The maximum permeability rate 12.5 L/ (m of each membrane module 204 ²H) (LMH), day processing maximum amount of water 15.4 L.Internal diameter 110 mm of the reactive tank 202 of this membrane bioreactor 20, high 600 mm, design useful volume 4.3 dm ³, a membrane module 204 is set in each reactive tank.

Membrane bioreactor 20 is used aerobic activated sludge 210 to inoculate, and the initial mixed liquor suspended solid, MLSS (MLSS) of aerobic activated sludge 210 is 1.29 g/L, and mixed liquor volatile suspended solid, MLVSS (MLVSS) is 0.93 g/L, and MLVSS/MLSS is 0.72.

The present embodiment is before the water-in 206 by this membrane bioreactor 20 is connected to electron beam irradiation device 10, first this water-in 206 is connected to a domestication wastewater disposal basin, make the first domestication waste water pass into this membrane bioreactor 20, aerobic activated sludge 210 is tamed.This first domestication COD value of waste water is 316.7 mg/L, BOD ₅Value is 245.5 mg/L, BOD ₅/ COD value is 0.78.In the first domestication stage of active sludge, it is 4.1 L/d that this membrane bioreactor 20 is processed the water yield, and hydraulic detention time (HRT) is 23 h, aeration rate 2.24 m in 26 ~ 30 ℃ of water temperatures, unit surface ³/ m ²D, DO remain on 2.0 mg/L, active sludge pH scope 8 ~ 9.

As Figure 2-3, between the domestication of aerobic activated sludge 210, the fluctuation of the influent COD of membrane bioreactor 20 is large, and average COD is 199.7 ± 70.3 mg/L, but water outlet COD is stable, and the water outlet average COD is 59.8 ± 9.7 mg/L, and average removal rate is 65%.

In the second domestication stage, the water-in of this membrane bioreactor 20 206 is connected to electron beam irradiation device 10, domestication is first carried out to ionizing rays through electron beam irradiation device 10 with the waste water that contains PVA, obtain this second domestication waste water, then tame through 20 pairs of aerobic activated sludges 210 of this membrane bioreactor.The water outlet 208 of membrane bioreactor 20 is connected to water reservoir 40 by pipeline, continuous process ionizing rays and the biological treatment of waste water that makes this domestication use contain PVA.In the second domestication stage, this domestication is 6 kGy by the ionizing rays amount that the waste water that contains PVA is accepted.

After this second domestication stage completed, it was 12 kGy that this doses of electron beam radiation is heightened, and adopted this electron beam irradiation device 10 and completed the membrane bioreactor 20 of domestication, and this waste water that contains PVA is processed.

As shown in Figure 4, in the ionizing rays step, when initial COD value is the electron beam irradiation of the waste water that contains PVA of 211.7 ± 26.3 mg/L through 12 kGy, the COD value of the pretreated water obtained is 182.8 ± 22.7 mg/L, and the COD average removal rate is 14 ± 4%.As can be seen from the figure, electron beam irradiation is sane to the COD removal effect, and clearance floats less.

As shown in Fig. 5-6, the pretreated water that processing obtains through electron beam irradiation enters membrane bioreactor and carries out a biological disposal upon, water outlet COD on average drops to 146.8 ± 23.3 mg/L, only the average COD removal in MBR stage is 20 ± 9%, wherein, the system operation MBR stage COD clearance of the 86th day is 40%.Total clearance that whole ionizing rays-membrane bioreactor coupling technique is the 31 ± 7%, 86th day to total clearance of COD is 45%.

Because the COD value of waste water that contains PVA is higher, in the present embodiment, from the clearance of COD, can find out the mode combined by ionizing rays and biological treatment, can effectively reduce the COD of the waste water that contains PVA, thereby explanation the method can reach the purpose of removing the PVA in waste water.

Comparative Examples 1

This Comparative Examples 1 is same as the previously described embodiments, and difference, only only this contains PVA waste water by Membrane Bioreactor for Wastewater Treatment, is namely adopted the identical waste water that contains PVA, processes without ionizing rays, directly inputs membrane bioreactor.This Comparative Examples is handled, and to contain waste water and above-described embodiment of PVA identical, and the specifications parameter of this membrane bioreactor and active sludge kind are also all identical with above-described embodiment, and this active sludge is through first domestication stage same as the previously described embodiments.

This PVA waste water of processing without ionizing rays is directly passed into to the membrane bioreactor through the first domestication stage, and after 12 hours, the phenomenons such as conglomeration, floating have appearred in the active sludge in membrane bioreactor, thereby cause the collapse of whole Sludge System.

This phenomenon shows, as a kind of high molecular polymer that bonding and frothing function are arranged, PVA easily sticks on the membrane module surface of membrane bioreactor, can by Pore Blocking, the interior PVA of reactor be accumulated.This waste water that contains PVA not only is difficult for being decomposed by microorganism, and PVA is accumulated to a certain degree in reactor, and active sludge is bondd.After the mud conglomeration that is bondd by PVA and wrap up or flocculation, cause density to descend, finally produce rising phenomenon, make the Sludge System collapse of membrane bioreactor.

Comparative Examples 2

This Comparative Examples 2 is identical with above-mentioned Comparative Examples 1, and difference was only further carrying out for the second domestication stage to this active sludge.

In the second domestication stage, the waste water that will contain PVA is tamed waste water as second after 6 kGy ionizing radiations are processed, pass into this membrane bioreactor, can see the system normal operation in the second domestication stage, in membrane bioreactor, conglomeration, rising phenomenon do not occur in active sludge.Yet, formal the processing, contain the waste water stage of PVA, in case will not contain the waste water of PVA, process through ionizing radiation, directly pass into this membrane bioreactor, the collapse identical with above-mentioned Comparative Examples 1 still appears in the Sludge System in this membrane bioreactor.

At first the technical program is processed through ionizing rays by the waste water that will contain PVA, then carries out a biological disposal upon through membrane bioreactor, can substantially remove the PVA in waste water, and after long-time running, removal effect is stable, is applicable to being applied to Industrial Wastewater Treatment.And, owing to adopting the ionizing rays processing to combine with Membrane Bioreactor for Wastewater Treatment, make ionizing rays process required radiation dose less, reduced the radiation energy consumption.

In addition, those skilled in the art also can do other variations in spirit of the present invention, and certainly, the variation that these are done according to spirit of the present invention, within all should being included in the present invention's scope required for protection.

Claims

1. treatment process that contains the waste water of polyvinyl alcohol comprises:

The waste water that will contain polyvinyl alcohol carries out ionizing rays, obtains a pretreated water; And

This pretreated water is passed into to membrane bioreactor carries out a biological disposal upon.

2. the treatment process that contains the waste water of polyvinyl alcohol as claimed in claim 1, it is characterized in that, in the waste water of the handled PVA of containing, the concentration of PVA is 50 mg/L to 110 mg/L, and the unit radiation dose that this waste water that contains polyvinyl alcohol is accepted this ionizing rays is greater than 3 kGy.

3. the treatment process that contains the waste water of polyvinyl alcohol as claimed in claim 2, is characterized in that, this waste water that contains polyvinyl alcohol is accepted the unit radiation dose of this ionizing rays for being greater than 6 kGy and being less than or equal to 12 kGy.

4. the treatment process that contains the waste water of polyvinyl alcohol as claimed in claim 1, is characterized in that, this ionizing rays is gamma Rays, electron beam irradiation or X ray.

5. the treatment process that contains the waste water of polyvinyl alcohol as claimed in claim 1, it is characterized in that, the step that this waste water that will contain polyvinyl alcohol carries out ionizing rays is to make this waste water that contains polyvinyl alcohol the electron beam irradiation district by rumbatron carries out electron beam irradiation with the continuous fluid form.

6. the treatment process that contains the waste water of polyvinyl alcohol as claimed in claim 1, is characterized in that, further comprises the step of the active sludge in membrane bioreactor being tamed with the first domestication waste water, the BOD of this first domestication waste water ₅/ COD is greater than 0.3.

7. the treatment process that contains the waste water of polyvinyl alcohol as claimed in claim 1, is characterized in that, further comprises and successively adopt the first domestication waste water and the second domestication waste water the active sludge in membrane bioreactor to be carried out to the gradient domestication, the BOD of this first domestication waste water ₅/ COD is greater than 0.3, and this second domestication waste water domestication obtains after ionizing rays is processed with the waste water that contains PVA.

8. the treatment process that contains the waste water of polyvinyl alcohol as claimed in claim 7, is characterized in that, this domestication is 3 kGy to 6 kGy with the radiation dose that the waste water that contains PVA is accepted this ionizing rays.

9. the treatment process that contains the waste water of polyvinyl alcohol as claimed in claim 8, is characterized in that, this domestication is less than or equal to 100 mg/L by PVA concentration in the waste water that contains PVA.

10. the treatment process that contains the waste water of polyvinyl alcohol as claimed in claim 1, it is characterized in that, further comprise the step of throwing in aid nutrition liquid, this aid nutrition liquid is thrown in to the waste water that contains PVA, or throw in to this pretreated water, this aid nutrition liquid contains at least a in the elements such as nitrogen, potassium, calcium and magnesium.