Method for treating wastewater containing DMF, pyridine and pyridine derivatives
Technical Field
The invention relates to the technical field of wastewater treatment, in particular to a method for treating wastewater containing DMF (dimethyl formamide), pyridine and pyridine derivatives.
Background
Two series products of trichloromethylpyridine, trifluoromethylpyridine and derivatives thereof are organic intermediates with high application value, and are widely applied to the fields of pesticides, medicines, fine chemical engineering and the like, and a large amount of wastewater containing DMF, pyridine and pyridine derivatives can be generated in the production process of the trichloromethylpyridine, the trifluoromethylpyridine and the derivatives thereof.
DMF, the name of which is N, N-dimethylformamide, is an organic solvent having stable chemical properties, a high boiling point and excellent performance, and causes an increase in BOD and nitrogen contents in water, causing rapid deterioration of water quality, and is difficult to biodegrade, and DMF poisons microorganisms, causing a great impact on biological treatment. The pyridine and the pyridine derivatives have strong consistency or toxicity to biological bacteria in the biochemical process, so that the biochemical process cannot be carried out, namely, the pyridine substances in the wastewater cannot be biochemically treated, and the sludge is easy to die and is biochemically paralyzed.
In the prior art, DMF and pyridine in wastewater are separated by adopting a high-temperature distillation mode, but the separation effect is poor, the boiling point is high, the distillation energy consumption is high, and the energy-saving and environment-friendly effects are not facilitated.
Therefore, a process for effectively treating the wastewater is needed.
Disclosure of Invention
In view of the above, the present invention provides a treatment method capable of effectively treating wastewater containing DMF, pyridine and pyridine derivatives.
The technical scheme of the invention is realized as follows: the invention provides a method for treating waste water containing DMF, pyridine and pyridine derivatives, which comprises the following steps:
step one, adding a pH regulator into waste water containing DMF, pyridine and pyridine derivatives for pH regulation to obtain regulated waste water;
step two, adding the wastewater obtained in the step one into a triple-effect evaporator for evaporation to obtain an evaporation condensate liquid with part of organic matters removed;
step three, carrying out air stripping treatment on the evaporation condensate obtained in the step two to obtain waste water after air stripping;
step four, adding the blown-off wastewater obtained in the step three into an oil separation regulating tank for oil separation treatment, and collecting a water layer to obtain oil-separated wastewater;
step five, adding the wastewater after oil separation obtained in the step four into a cavitation air flotation device for removing suspended matters, and collecting clear liquid;
step six, adding a coagulant, 30% of hydrogen peroxide and ferrous sulfate into the clear liquid obtained in the step five in sequence, carrying out solid-liquid separation after coagulation and flocculation precipitation reaction, and collecting filtrate;
step seven, carrying out adsorption purification treatment on the filtrate obtained in the step six by using adsorption resin, and collecting the liquid after adsorption purification;
step eight, adding the liquid obtained in the step seven after adsorption and purification into a biochemical reaction tank for biochemical treatment to obtain biochemical treatment wastewater;
and step nine, performing solid-liquid separation on the biochemical treatment wastewater obtained in the step eight by using an MBR system, taking filtrate, adding a disinfectant into the filtrate for disinfection, and discharging after reaching the standard through detection.
On the basis of the above technical scheme, preferably, in the step one, the pH regulator includes sodium hydroxide and hydrochloric acid, and the pH value of the wastewater after regulation is 6.5-7.5.
On the basis of the above technical solution, preferably, the third step further includes: adding sodium hydroxide into the wastewater obtained in the step two for removing partial organic matters, adjusting the pH value to 11-12, transferring the wastewater into a stripping tower for stripping treatment, wherein the stripping treatment temperature is 0-90 ℃, the stripping time is 2-5h, and the stripping gas-liquid ratio is (1000-) -3000): 1(v: v).
On the basis of the technical scheme, preferably, the stripping temperature is 25 ℃, the stripping time is 5 hours, and the stripping gas-liquid ratio is 3000: 1(v: v).
More preferably, in the sixth step, the coagulant is one of polyferric sulfate, PAC and PAM, and the dosage of the coagulant is 0.5-1.5g of coagulant added to 1L of the clear liquid obtained in the fifth step.
On the basis of the technical scheme, preferably, in the sixth step, 0.5-1.5ml of 30% hydrogen peroxide is added into every 1L of the clear liquid obtained in the fifth step, and the dosage of the ferrous sulfate is 1-2g of ferrous sulfate added into every 1L of the clear liquid obtained in the fifth step.
On the basis of the above technical solution, preferably, in step seven, the method for adsorption purification treatment includes: and (4) enabling the filtrate obtained in the sixth step to positively pass through a single resin adsorption column at the flow rate of 1BV/h, and carrying out regeneration on the resin adsorption column once every 5 hours of adsorption.
On the basis of the above technical solution, preferably, in step seven, the regeneration method includes: and (3) introducing 1-5kg of steam into the resin adsorption column from top to bottom for resin regeneration, wherein the regeneration time is 0.8-3h, after the regeneration is finished, 0.1-0.15kg of compressed air is used for pressing out evaporated condensate water in the resin adsorption column, after the pressing out is finished, washing the liquid obtained in the seventh step from bottom to top after adsorption and purification, and taking the upper end effluent as the filtrate obtained in the sixth step.
On the basis of the technical scheme, preferably, the filler used by the resin adsorption column is ultrahigh cross-linked polystyrene macroporous adsorption resin.
On the basis of the above technical solution, preferably, in step eight, the biochemical treatment method includes: and (4) adding the wastewater subjected to adsorption and purification obtained in the step seven into a hydrolysis acidification tank for hydrolysis treatment, adding the wastewater obtained after the hydrolysis treatment into an A2O biochemical tank for denitrification and dephosphorization treatment, and filtering the wastewater subjected to denitrification and dephosphorization treatment by using an MBR (membrane bioreactor) to obtain the biochemical treatment wastewater.
On the basis of the above technical scheme, preferably, in the ninth step, the disinfectant is one of sodium hypochlorite and sodium citrate.
Compared with the prior art, the treatment method of the wastewater containing DMF, pyridine and pyridine derivatives has the following beneficial effects:
(1) the invention provides a wastewater treatment method capable of effectively removing DMF, pyridine and pyridine derivatives in wastewater, wherein a blow-off treatment mode is adopted in the front-stage treatment process, so that the content of ammonia nitrogen, DMF, pyridine and pyridine derivatives is greatly reduced, and meanwhile, in the back-stage treatment process, the residual harmful substances are adsorbed by utilizing a resin adsorption mode, so that the content of ammonia nitrogen, DMF, pyridine and pyridine derivatives entering biochemical treatment is greatly reduced, the poisoning of a biochemical treatment system is avoided, most of toxic harmful organic matters and precipitates are removed in the whole process, the ammonia nitrogen and COD are deeply removed through the biochemical treatment system, and the wastewater reaches the discharge standard;
(2) the whole treatment method can also collect and centralize the generated waste gas, the energy consumed in the treatment process is less, the operation cost is lower, the method is low-carbon and environment-friendly, and the method is green and has no secondary pollution.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The wastewater generated in the production process of trichloropicoline is divided into three groups and is respectively treated as the raw materials of examples 1, 2 and 3.
Example 1
Adding hydrochloric acid and caustic soda flakes into raw material wastewater to adjust the pH value to 6.5, transferring the adjusted wastewater into a triple-effect evaporator to be evaporated, adjusting the evaporation temperature to 60 ℃, the vapor pressure to 0.5MPa, transferring evaporated condensate water into a stripping tower when no obvious liquid flows out by evaporation, adding caustic soda flakes to adjust the pH value to 11, adjusting the temperature of stripping gas to 0 ℃, the stripping time to 5 hours, and the gas-liquid ratio of stripping to 1000:1, passing the liquid layer through an oil separation adjusting tank after stripping is finished to carry out oil separation treatment, taking the middle liquid layer, removing the upper oil layer and the lower slag layer, adding the middle water layer into a vortex concave gas floating device to further remove suspended matters, collecting clear liquid, adding 0.5g PAC into each 1L of clear liquid to carry out coagulation precipitation, adding 1.0ml of 30% hydrogen peroxide and 1.5g of ferrous sulfate into each 1L of clear liquid after settling separation, stirring, reacting and precipitating, collecting the clear liquid and filtering, purifying the filtrate by a resin adsorption column, wherein the filler in the resin adsorption column is ultrahigh crosslinked polystyrene macroporous adsorption resin, treating at a treatment speed of 1 bed volume per hour, performing primary regeneration treatment on the resin adsorption column after treating 5 bed volumes of the filtrate, adding the filtrate adsorbed by the column into a hydrolysis acidification tank for hydrolysis treatment, transferring the wastewater subjected to hydrolysis treatment into an A2O biochemical tank for denitrification and dephosphorization treatment, filtering the wastewater subjected to denitrification and dephosphorization treatment by an MBR (membrane bioreactor) to obtain the treated filtrate, and adding sodium hypochlorite into the filtrate for disinfection to obtain the waste liquid meeting the requirements.
Example 2
Adding hydrochloric acid and caustic soda flakes into raw material wastewater to adjust the pH value to 7.0, transferring the adjusted wastewater into a triple-effect evaporator to carry out evaporation treatment, wherein the evaporation temperature is 60 ℃, the vapor pressure is 0.5MPa, transferring evaporated condensate water into a stripping tower when no obvious liquid flows out by evaporation, adding caustic soda flakes to adjust the pH value to 11.5, adjusting the stripping gas temperature to 25 ℃, the stripping time to 3 hours, and the stripping gas-liquid ratio to 2000:1, carrying out oil separation treatment on a liquid layer through an oil separation adjusting tank after the stripping is finished, taking a middle liquid layer, removing an upper oil layer and a lower slag layer, adding the middle water layer into a cavitation air flotation device to further remove suspended matters, collecting clear liquid, adding 1g of polymeric ferric sulfate into each 1L of clear liquid to carry out coagulation precipitation, adding 0.5ml of 30% hydrogen peroxide and 1g of ferrous sulfate into each L of clear liquid after the sedimentation separation, stirring, reacting, precipitating, standing and separating, collecting supernatant, filtering, purifying filtrate by a resin adsorption column, treating the filler in the resin adsorption column by using ultra-high crosslinked polystyrene macroporous adsorption resin at a treatment speed of 1 bed volume per hour, performing primary regeneration treatment on the resin adsorption column after treating 5 bed volumes of filtrate, adding the filtrate after column adsorption into a hydrolysis acidification tank for hydrolysis treatment, transferring the wastewater after hydrolysis treatment into an A2O biochemical tank for denitrification and dephosphorization treatment, filtering the wastewater after denitrification and dephosphorization treatment by using an MBR (membrane bioreactor) to obtain treated filtrate, and adding sodium citrate into the filtrate for disinfection to obtain the waste liquid meeting the requirements.
Example 3
Adding hydrochloric acid and caustic soda flakes into raw material wastewater to adjust the pH value to 7.5, transferring the adjusted wastewater into a triple-effect evaporator to carry out evaporation treatment, wherein the evaporation temperature is 60 ℃, the vapor pressure is 0.5MPa, transferring evaporated condensate water into a stripping tower when no obvious liquid flows out by evaporation, adding caustic soda flakes to adjust the pH value to 12, adjusting the temperature of stripping gas to 90 ℃, the stripping time is 2 hours, the gas-liquid ratio of stripping is 3000:1, passing a liquid layer through an oil separation adjusting tank after stripping is finished to carry out oil separation treatment, taking a middle liquid layer, removing an upper oil layer and a lower slag layer, adding the middle water layer into a vortex concave gas floating device to further remove suspended matters, collecting clear liquid, adding 1.5g of PAM into each 1L of clear liquid to carry out coagulation precipitation, adding 1.5ml of 30% hydrogen peroxide and 2g of ferrous sulfate into each 1L of filtrate after settling separation, stirring, reacting and precipitating, collecting the supernatant, purifying the filtrate by a resin adsorption column, wherein the filler in the resin adsorption column is ultrahigh crosslinked polystyrene macroporous adsorption resin, treating at a treatment speed of 1 bed volume per hour, performing primary regeneration treatment on the resin adsorption column after treating 5 bed volumes of the filtrate, adding the filtrate adsorbed by the column into a hydrolysis acidification tank for hydrolysis treatment, transferring the wastewater subjected to hydrolysis treatment into an A2O biochemical tank for denitrification and dephosphorization treatment, filtering the wastewater subjected to denitrification and dephosphorization treatment by an MBR (membrane bioreactor) to obtain the treated filtrate, and adding sodium hypochlorite into the filtrate for disinfection to obtain the waste liquid meeting the requirements.
The method comprises the following steps of respectively detecting DMF, pyridine derivatives, COD, TOC, total nitrogen and ammonia nitrogen of the wastewater before treatment and the filtrate filtered by an MBR membrane bioreactor, wherein the detection results are as follows:
detecting items
|
Waste water before treatment
|
Example 1
|
Example 2
|
Example 3
|
DMF/ppm
|
2357
|
67
|
54
|
55
|
Pyridine/ppm
|
1405
|
7
|
8
|
7
|
Pyridine derivative/ppm
|
821
|
4
|
3
|
3
|
COD/ppm
|
15126
|
102
|
100
|
98
|
TOC/ppm
|
7552
|
170
|
153
|
149
|
Total nitrogen/ppm
|
229.4
|
13.54
|
11.74
|
17.70
|
Ammonia nitrogen/ppm
|
25.63
|
4.23
|
4.55
|
4.14 |
The microbial contents of the sludge before and after wastewater treatment in the hydrolysis acidification tank and the A2O biochemical tank of examples 1-3 were simultaneously detected, and the detection results were as follows:
the data show that the treatment method of the invention can not influence the biological activity of the biochemical tank, effectively avoids the microbial poisoning in the biochemical treatment tank, reduces the cost investment, and is more green and pollution-free.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.