CN101618921A - TDI wastewater advanced treatment method - Google Patents

Abstract

The invention discloses a TDI wastewater advanced treatment method, mainly comprising cooling, catalytic reduction, catalytic oxidation, neutralization flocculation deposition, membrane bioreactor, ozone-biological activated carbon and other processes. Sewage is cooled firstly; activated iron and supplement stuffing resisting hardening are added into a catalytic reduction device; catalyst and inert agent are filled in a catalytic oxidation tank to be evenly mixed according to the proportion of 1:1, simultaneously, hydrogen peroxide is dosed and used as oxidant; after neutralization flocculation deposition, the obtained mixture enters a membrane bioreactor to be treated and then is subjected to ozone-biological activated carbon advanced treatment to be used as source water for reclaimed water. By adopting wastewater treated by the invention, the removal rate of COD can reach up to 99.5%, COD, color and aniline and nitrobenzene completely meet the national emission standards by detection, therefore, no secondary pollution on the environment is generated.

Description

The TDI advanced waste treatment method

Technical field

The present invention relates to a kind of technology for treating industrial waste water field, particularly relate to a kind of deep treatment method of TDI waste water.

Background technology

TDI is a tolylene diisocyanate, is the basic raw material of polyurethane industrial, and product is widely used in many industries such as automobile, shipbuilding, aircraft, electronics, petrochemical complex, building, light industry, furniture, engineering thermal insulation.The TDI technological process of production is long, the chemical reaction complexity, and the level of automation height, the control difficulty is big, belongs to the contemporary high technology high value-added industries.In the TDI production process, discharge multiple sewage, its toxicity is big, and the Pollutant levels height mainly contains alkali cleaning waste water, and hydrogenation waste water, nitration waste water etc., pollutent mainly contain phenyl amines, nitrobenzene etc.

The TDI wastewater treatment method mainly contains following several at present:

(1) evaporation+burning method: adopt the factory effluent evaporation concentration, then the technology that concentrated solution is burned.This technology is according to water in the solution and organism boiling point different under same pressure, pressure and temperature by the control evaporation, water is separated with organism and inorganic salt, the strong solution that concentrates back organism and inorganic salt is delivered to the incinerator burning, and the distillate that evaporates, the pollutent overwhelming majority such as its COD, colourity, salinity and oil of mirbane are removed, the concentration of pollutent reduces, biodegradability raises, and handles through follow-up biochemistry, materialization, to reach processing requirements again.But this method investment is big, the working cost height, and it is serious to carry organism in the steam condensate secretly, and this kind method can only be handled the nitrobenzene wastewater in the TDI production simultaneously, and powerless to amino benzene analog waste water.Carrying out can causing smoke pollution when concentrated solution burns, pollutent takes place shift.Cangzhou bigization TDI limited liability company just adopts the method for evaporation+burning in calendar year 2001 to 2003 year, wastewater treatment expense height, effect instability, and secondary pollution was comparatively serious, changed other technology in 2003.

(2) ClO 2 catalyzed oxidation method: utilize the catalysed oxidn of dioxide peroxide and catalyzer, phenyl ring and larger molecular organics are decomposed into inorganics or micromolecular organism, to improve the biodegradability of waste water.But this method has following shortcoming: dioxide peroxide decomposes not thorough, easily produces the secondary water pollution; Dioxide peroxide needs field fabrication, and concentration has fluctuation, and is higher and operating environment is relatively poor to operational requirement, and hydrogenchloride is arranged, and gases such as chlorine and dioxide peroxide produce; The treatment effect instability, catalyzer p-nitrophenyl class sensitivity, under the environment that has oil of mirbane to exist, catalyzer is very easy to poison, therefore when handling the TDI factory effluent, a large amount of nitrobenzene matters in the nitrated sewage wherein, aniline category matter need be reduced to earlier and just catalyzed oxidation can be carried out, if pretreating effect is bad, to directly cause poisoning of catalyst, treatment system collapse, and measure such as also need filter before entering the catalyzed oxidation operation removes oils and particulate matter, otherwise very easily result in blockage and catalyst failure.

(3) iron-based-hydrogen peroxide catalytic oxidation method: utilize feton reagent principle to carry out catalyzed oxidation, Fe ²⁺With H ₂O ₂Reacting produces the OH free radical, and the OH free radical has extremely strong oxygenizement, can be with the direct mineralising of organism.But Feton reagent react excessive velocities, the OH of generation has very major part just remove with organism to bury in oblivion voluntarily, cause reagent waste.Hebei Vsain Environmental Protection Group Co., Ltd. discloses " nitrobenzene-containing, aniline pollutent wastewater treatment method " (patent No.: 200610012900) in 2006, this method is iron-based-hydrogen peroxide catalytic oxidation method, this method p-nitrophenyl, amino benzene analog waste water have treatment effect preferably, but this method does not well solve the crystallization in the nitrobenzene waste water in the TDI factory effluent, waste water after the processing can reach emission standard, the water inlet index of water reuse in can't reaching.

Above method is the general processing of this kind waste water, and sewage can reach state sewage emission standard, but if desired to the further reuse of sewage, the influent quality index of water reuse during above method all is difficult to reach.

Summary of the invention

The objective of the invention is the problems referred to above, a kind of TDI advanced waste treatment method is provided, sewage treating efficiency is greatly improved, make sewage reach the water inlet index of middle water reuse at the prior art existence.

The technical solution adopted for the present invention to solve the technical problems is to be prototype with Feton reagent principle, improves, and slows down Fe ²⁺With H ₂O ₂Speed reacts, increase method processing efficiency strengthens oxidation effectiveness, and catalyzer has been carried out innovating (filler is formed and is divided into two portions: first part is a catalyzer, be two cast iron rings of regular shape, add 0.1% bronze medal in cast iron carbon content ≮ 3% and the castingprocesses; Second section is an inert agents, be graphite and Φ 50mm acrylic sphere mixture, the ratio of graphite and acrylic sphere is 1: 1), and perfect subsequent treatment process, sewage is earlier through cooling, in catalytic reduction device, add inert agents through activatory iron and anti-compaction, be filled with catalyzer, inert agents in the catalyzed oxidation groove, catalyzer and inert agents are mixed evenly in 1: 1 ratio, add hydrogen peroxide simultaneously as oxygenant, through in and enter Membrane Bioreactor for Wastewater Treatment behind the flocculation sediment, the source water of water reuse in after ozone-active carbon place degree of depth reason, can be used as again.This TDI method of wastewater treatment comprises the steps:

(1) crystallisation by cooling: the nitrobenzene waste water in the TDI waste water is carried out crystallisation by cooling handle;

(2) regulate pH value: regulate the pH value of waste water, make the pH value reach 2～4;

(3) catalytic reduction: the waste water of regulating behind the pH value carries out reduction reaction in reduction reactor, add in the reduction reactor through the inert agents of activatory iron with anti-compaction, and adding proportion is 1: 1, and mixing stirring in the reactor, to utilize pneumatic blending, steam-water ratio be 8: 1; Waste water residence time in catalytic reduction reactor is 2-5 hour;

(4) re-adjustment pH value: the pH value of re-adjustment waste water makes the pH value reach 2～4;

(5) catalytic oxidation treatment: the waste water of regulating after the pH value carries out catalytic oxidation treatment in catalyst oxidation reactor, be filled with catalyzer, inert agents in the catalyst oxidation reactor, is mixed evenly in 1: 1 ratio, adds concentration simultaneously and be about 30% H ₂O ₂15～30L/ (m ³Waste water), reactor wherein mixes and stirs that to utilize pneumatic blending, gas-water ratio be 8: 1.Waste water residence time in catalyst oxidation reactor is 3～6 hours;

(6) flocculation sediment: during the waste water after catalytic oxidation treatment carries out in tube settler and flocculation sediment, sedimentation time is 3 hours;

(7) membrane biological reaction: the supernatant liquor after flocculation sediment is handled enters membrane bioreactor, and hollow-fibre membrane is housed in the pond, and sludge concentration is 9g/L in the membrane bioreactor, and be 20 hours biochemical effectively duration of contact;

(8) ozone-biological activated carbon is handled: the membrane bioreactor water outlet is handled back discharging, ozone contact time 10h, gac 0.7h duration of contact through ozone-active carbon again;

Ultimate principle of the present invention is:

(1) the nitration waste water temperature in the TDI waste water is very high, during low temperature in the water organism have mass crystallization, before this strand waste water enters Sewage treatment systems,, can have substantial degradation to the load of subsequent disposal with behind its decrease temperature crystalline;

(2) hydrogen peroxide can produce the very strong OH free radical of oxidisability under certain conditions, this hydroxyl radical free radical has higher oxidizing electrode current potential than some other strong oxidizer commonly used, its oxidation activity approximately is 2 times of chlorine, between atomic oxygen and fluorine, therefore, the OH free radical is a kind of very strong oxygenant.The OH free radical can be direct oxidation into inorganics with organic pollutant, or is translated into the intermediate product of the readily biodegradable of low toxicity, thereby the biodegradability of sewage is improved.Hydrogen peroxide with Fe ^2-Form oxidation system, can produce the OH free radical of greater concn, thereby improve oxidation capacity greatly, make the processing reaction time of sewage shorter relatively, be easier to control, more thorough organic degraded.The present invention handles catalyzer, has slowed down Fe in the system ²⁺Release rate, controlled hydrogen peroxide and Fe ²⁺Speed of response, catalyzed oxidation is worked in controlled range.

(3) membrane bioreactor by active sludge make a return journey dewater in biodegradable organic pollutant, owing to adopted hollow-fibre membrane to carry out solid-liquid separation, make the microorganism in the membrane bioreactor not run off, sludge concentration is greatly improved, biomass is more much higher than traditional active sludge, biochemical efficiency improves greatly, and it is extremely low to go out water suspension simultaneously, makes water outlet can satisfy the requirement of further carrying out advanced treatment.

(4) the ozone-active carbon method is a kind of ozone oxidation and the combined method of charcoal absorption that water depth is handled that be used for, and carries out ozone oxidation earlier, after carry out charcoal absorption, biological degradation in addition therebetween.Ozone has extremely strong oxidisability, can react with many materials, remove part pollutent in the water, and for activated carbon filter thereafter provides remaining ozone or oxygen, so give birth to for charcoal absorption organism and microorganism dwell, breeding provides good condition.Like this, activated carbon surface forms microbial film gradually, plays biological degradation.

TDI wastewater treatment degree of depth method of the present invention, the technology practicality, treatment effect is stable, and catalyzer is applied widely, stable performance, maintenance is simple and maintenance cost is low; Decomposing hydrogen dioxide solution does not thoroughly produce the secondary water pollution, does not produce gas contamination.Adopt method of wastewater treatment of the present invention, ton water treatment running cost is about 6 yuan, and the COD clearance can reach 99.5%, and colourity and aniline, oil of mirbane all can reach discharging standards, to the environment non-secondary pollution, the Sewage treatment systems final outflow water can reach middle water reuse influent quality index.

Description of drawings

Fig. 1 is the schematic flow sheet of method of wastewater treatment of the present invention.

1 cooling crystallizer, 2 equalizing tanks, 3 lift pumps, 4 catalytic reduction reactors, 5 middle ponds, 6 lift pumps, 7 catalyst oxidation reactors, 8 tube settlers, 9 membrane bioreactors, 10 membrane modules, 11 lift pumps, 14 biological activated carbons among the figure.

Embodiment

Oil of mirbane sewage is promoted to by lift pump after the cooling crystallizer cooling earlier and carries out reduction reaction in the catalytic reduction reactor, mix with aniline sewage in middle pond through reductive sewage, be promoted to by lift pump and carry out oxidizing reaction in the catalyst oxidation reactor, catalyst oxidation reactor water outlet gravity flow enters flocculation sediment in the tube settler, other sewage of water outlet and plant area is mixed into and carries out biochemical reaction in the membrane bioreactor, sewage in the membrane bioreactor is delivered to after by the tubular fibre membrane filtration of lift pump by membrane module to be removed the pond and fully contacts with ozone, organism in contact tank in the sewage is further decomposed, oxidation, water outlet is promoted to the biological activated carbon jar with pump, biology in the biological activated carbon jar decomposes a small amount of organism that contains in the sewage, makes sewage obtain discharging after the advanced treatment.

The Sewage treatment systems monitoring result:

2010 two class waste water first discharge standards of regulation see Table 1 among the DB37/676-2007 " peninsula, Shandong Province basin water pollutent comprehensive discharge standard "

Table 1

Index	??COD ??(mg/L)	??BOD ??(mg/L)	??SS ??(mg/L)	Ammonia nitrogen (mg/L)	Nitrobenzene (mg/L)	Orthodichlorobenzene (mg/L)	Phenyl amines (mg/L)
								Concentration	??≤60	??≤20	??≤50	??≤10	??≤1.0	??≤0.4	??≤0.5
Index	Volatile phenol (mg/L)	Sulfide (mg/L)	Vegetable and animals oils (mg/L)	Total cyanide (mg/L)	Colourity (doubly)	??PH
								Concentration	??≤0.2	??≤1.0	??≤5.0	??≤0.5	??≤40	??6-9

Table 2 is the detected result of processed waste water.

Table 2

Project name	??COD?mg/L	Aniline mg/L	Oil of mirbane mg/L	??pH
					The waste water former state	??10000-12000	??1000-1200		??9-10
Detected result	??30-50	Do not detect	Do not detect	??6-9
					Standard for acceptance	??≤60	??≤0.5	??≤1.0	??6-9

Can find out that from table 2 adopt the waste water after the inventive method is handled, each test item reaches the requirement of standard for acceptance fully.Effluent quality can reach middle water reuse influent quality index.

Claims (1)

1, a kind of TDI advanced waste treatment method is characterized in that with Feton reagent principle be prototype, improves, and slows down Fe ²⁺With H ₂O ₂Speed reacts, increase method processing efficiency strengthens oxidation effectiveness, and catalyzer has been carried out being bold in innovation (filler is formed and is divided into two portions: first part is a catalyzer, be two cast iron rings of regular shape, add 0.1% bronze medal in cast iron carbon content ≮ 3% and the castingprocesses; Second section is an inert agents, be graphite and Φ 50mm acrylic sphere mixture, the ratio of graphite and acrylic sphere is 1: 1), and perfect subsequent treatment process, sewage is earlier through cooling, in catalytic reduction device, add inert agents through activatory iron and anti-compaction, be filled with catalyzer, inert agents in the catalyzed oxidation groove, be mixed evenly in 1: 1 ratio, add hydrogen peroxide simultaneously as oxygenant, through in and enter Membrane Bioreactor for Wastewater Treatment behind the flocculation sediment, the source water of water reuse in after ozone-active carbon place degree of depth reason, can be used as again.This TDI method of wastewater treatment comprises the steps:

(1) crystallisation by cooling: the nitrobenzene waste water in the TDI waste water is carried out crystallisation by cooling handle;

(2) regulate pH value: regulate the pH value of waste water, make the pH value reach 2～4;

(3) catalytic reduction: the waste water behind the adjusting pH value carries out reduction reaction in reduction reactor, add additional fillers in the reduction reactor through activatory iron and anti-compaction, adding proportion is 1: 1, and mix stirring in the reactor and utilizing pneumatic blending, steam-water ratio is 8: 1; Waste water residence time in catalytic reduction reactor is 2-5 hour;

(4) re-adjustment pH value: the pH value of re-adjustment waste water makes the pH value reach 2～4;

(5) catalytic oxidation treatment: the waste water after the adjusting pH value carries out catalytic oxidation treatment in catalyst oxidation reactor, be filled with catalyzer (the two cast iron rings of regular shape that are mixed in the catalyst oxidation reactor, interpolation 0.1% bronze medal in cast iron carbon content ≮ 3% and the castingprocesses), additional fillers (graphite, φ 50mm acrylic sphere), be mixed evenly in 1: 1 ratio, add concentration simultaneously and be about 30% H ₂O ₂15～30L/ (m ³Waste water), reactor wherein mixes and stirs that to utilize pneumatic blending, gas-water ratio be 8: 1.Waste water residence time in catalyst oxidation reactor is 3～6 hours;

(6) flocculation sediment: during the waste water after catalytic oxidation treatment carries out in tube settler and flocculation sediment, sedimentation time is 3 hours;

(7) membrane biological reaction: the supernatant liquor after flocculation sediment is handled enters membrane bioreactor, and hollow-fibre membrane is housed in the pond, and sludge concentration is 9g/L in the membrane bioreactor, and be 20 hours biochemical effectively duration of contact;

(8) ozone-active carbon is handled: the membrane bioreactor water outlet is handled back discharging, ozone contact time 10h, gac 0.7h duration of contact through ozone-active carbon again.