CN113716775A - Comprehensive treatment method for high-arsenic high-salt wastewater and arsenic-containing grinding wastewater of gallium arsenide chip - Google Patents
Comprehensive treatment method for high-arsenic high-salt wastewater and arsenic-containing grinding wastewater of gallium arsenide chip Download PDFInfo
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Abstract
The invention discloses a comprehensive treatment method for high-arsenic high-salt wastewater and arsenic-containing grinding wastewater of a gallium arsenide chip, and aims to solve the problem of treatment of the high-arsenic high-salt wastewater and the arsenic-containing grinding wastewater of the gallium arsenide chip. The method comprises the following steps: (1) carrying out crystallization desalination and single-effect evaporation pretreatment on the high-arsenic and high-salt wastewater; (2) carrying out precipitation pretreatment on the arsenic-containing grinding wastewater; (3) removing arsenic, phosphorus, fluorine and precipitation from the comprehensive wastewater; (4) performing Fenton ozone secondary oxidation and precipitation treatment; (5) removing ammonia nitrogen; (6) resin adsorption (7) sludge treatment. The method has reasonable process, can solve the problems of blockage and difficult precipitation of the high-arsenic high-salt gallium arsenide chip wastewater crystallization, eliminates the adverse effect of high-salt and grinding fluid superfine suspended matters on resin adsorption, ensures that the treated wastewater reaches the discharge standard, has obvious economic value and environmental value, and has practical significance for promoting the development of semiconductor production.
Description
Technical Field
The invention belongs to the technical field of arsenic-containing wastewater treatment, and particularly relates to a comprehensive treatment method for high-arsenic high-salt wastewater and arsenic-containing grinding wastewater of a gallium arsenide chip.
Background
An integrated circuit chip manufactured by using gallium arsenide as a substrate is an essential key component for realizing high-speed optical fiber communication and high-frequency mobile communication. Gallium arsenide (formula GaAs) has become the most important and mature compound semiconductor material at present based on its own superior characteristics, and is widely used in the fields of optoelectronics and microelectronics.
The gallium arsenide chip production is a production process of forming a circuit pattern on a substrate gallium arsenide chip by adopting a semiconductor planar process method; in the production process, etching wastewater and arsenic-containing grinding wastewater are generated; wherein the etching wastewater contains a large amount of arsenic (1500-2000mg/L), phosphorus (1500mg/L), a small amount of ammonia nitrogen (50mg/L) and a large amount of salt (12%), the pH value is 3-4, and the wastewater is high-arsenic high-salt high-phosphorus wastewater; the arsenic-containing grinding wastewater contains a small amount of arsenic (10mg/L), fluorine (11.4mg/L), a large amount of suspended matters (100mg/L), COD (300mg/L), a small amount of ammonia nitrogen (26.6mg/L) and phosphorus (15 mg/L). A large amount of pollutants such as arsenic and the like can cause great harm to the health of human bodies and the environment, and can also limit the development of the gallium arsenide chip industry. Therefore, the pollutants in the wastewater need to be treated and discharged after reaching the standard (namely, in the discharged wastewater, As is less than 0.1mg/L, F and less than 8mg/L, SS and less than 10mg/L, COD and less than 30mg/L, ammonia nitrogen is less than 8mg/L, and total phosphorus is less than 0.5 mg/L).
At present, the common methods for removing arsenic and phosphorus are iron salt precipitation, ion exchange, extraction, membrane separation and adsorption. Wherein, the iron salt precipitation method is used for precipitating arsenic and phosphorus by adding medicaments such as iron salt and the like.
The inventor finds that the prior arts have at least the following technical problems in the practical use process:
for high-concentration arsenic and phosphorus, after the precipitator is added, the dosage is large, the precipitation effect is poor, and the phenomenon of poor separation of mud and water can occur.
Meanwhile, the iron salt precipitation method can only reduce the arsenic to 0.5mg/L and cannot reach the standard (less than 0.1mg/L), and needs to carry out advanced treatment on trace arsenic by an ion exchange method, an extraction method, a membrane separation method, an adsorption method and the like, while high-concentration salt (12%) and ground superfine suspended matters can influence the advanced treatment on the arsenic, so the high-concentration salt and the ground superfine suspended matters must be removed firstly.
Further, for the high-arsenic high-salt wastewater, when the temperature is lower than 10 ℃ in winter, salt in the wastewater can be crystallized to block pipelines and equipment, so the problem of salt crystallization needs to be considered in winter.
The organic pollutants in the arsenic-containing grinding fluid wastewater are mainly organic additives (isopropanol and acetone) which are difficult to treat, and the organic pollutants have high stability, high oxidative decomposition difficulty, low B/C value and poor biodegradability.
The biological method is difficult to meet the treatment requirement of organic pollutants in arsenic-containing grinding wastewater, cannot normally operate, and an effective advanced oxidation means must be selected to directly degrade organic matters in the arsenic-containing grinding wastewater. Furthermore, the grinding wastewater contains a large amount of ultrafine suspended matters, the surface potential of particles is generally about-40 mV and is in a colloid stable state, and the conventional flocculation precipitation treatment method is difficult to destabilize the particles, and the main reason is probably that fine particle colloids adsorb a large amount of COD, so that the colloids form a space stable state or a vacancy stable state; however, the common electrolyte is difficult to flocculate and precipitate, and the successful destabilization of the ultrafine suspended particles can be realized only by degrading COD through oxidation reaction and gradually reducing the Zeta potential absolute value of the particulate matters. Therefore, oxidation of COD is very necessary. The common advanced oxidation methods are Fenton oxidation and ozone oxidation, and the inventor finds that the COD can not be reduced to below 30mg/L by single Fenton oxidation and ozone oxidation through experiments, so that a combined advanced oxidation method is adopted.
Disclosure of Invention
Aiming at the problems of pipeline blockage due to high-salt crystallization in winter, difficult precipitation of high-concentration arsenic and phosphorus, difficult degradation of organic additives, difficult precipitation of superfine suspended matters and the like in the prior art, the invention provides a comprehensive treatment method for gallium arsenide chip high-arsenic high-salt wastewater and arsenic-containing grinding wastewater, which aims to: the problem of improve high arsenic high salt gallium arsenide chip waste water crystallization in winter and block up the pipeline, difficult sediment is solved, eliminate the high salt and the superfine suspended solid of lapping liquid and to the adsorbed adverse effect of resin, further handle COD composition and arsenic content in the waste water, reduce arsenic content in the discharge water, guarantee that the waste water after handling discharges up to standard.
In order to achieve the purpose, the invention adopts the technical scheme that: the comprehensive treatment method of the high-arsenic high-salt wastewater and the arsenic-containing grinding wastewater of the gallium arsenide chip comprises the following steps:
(1) crystallizing and desalting the high-depth high-salinity wastewater and performing single-effect evaporation pretreatment: when the environmental temperature is less than or equal to 10 ℃, carrying out crystallization and desalination pretreatment, and sending the dehydrated filtrate into a high-arsenic high-salt wastewater adjusting tank; when the environmental temperature is higher than 10 ℃, directly feeding the high-arsenic high-salt gallium arsenide wastewater into a high-arsenic high-salt wastewater regulating tank;
(2) sending the wastewater in the high-arsenic high-salt wastewater adjusting tank into a pH adjusting tank, adjusting the pH, and then performing evaporation treatment to respectively obtain condensate, crystallized salt and mother liquor; sending the condensate into a comprehensive adjusting tank; carrying out outward transportation on the crystallized salt as hazardous waste; the mother liquor returns to the evaporator, and the periodically transported part is treated as hazardous waste;
(3) precipitation pretreatment of arsenic-containing grinding wastewater: firstly, the arsenic-containing grinding wastewater enters a flocculation sedimentation tank, a flocculating agent is added for primary coagulation sedimentation, most of grinding suspended matters and phosphorus are removed, and then the arsenic-containing grinding wastewater is sent into a comprehensive regulation tank;
(4) performing arsenic, phosphorus, fluorine and precipitation treatment on the comprehensive wastewater, adjusting the pH value in a comprehensive adjusting tank to be neutral, sending the wastewater into an arsenic, phosphorus and fluorine removal reaction tank, adding a precipitator to precipitate arsenic, phosphorus and fluorine ions, adding a flocculating agent to perform two-stage coagulation precipitation, and sending the wastewater into a Fenton oxidation tank after flocculation precipitation;
(5) performing secondary oxidation and precipitation treatment by Fenton ozone: after the PH value of the wastewater is adjusted to 3, adding the group A materials to carry out Fenton reaction, after the Fenton reaction is finished, adjusting the PH value of the wastewater to 8, adding a coagulant aid to carry out three-section coagulating sedimentation, after the sedimentation is finished, introducing the wastewater into an intermediate water tank, and adding the group B materials to carry out ozone catalytic oxidation reaction; after the catalytic oxidation of ozone is finished, adding a flocculating agent into the wastewater to carry out four-section coagulating sedimentation;
(6) ammonia nitrogen treatment: adding an oxidant into the wastewater after the four-stage coagulation and precipitation is finished, removing ammonia nitrogen, adding a reducing agent to remove redundant oxidant, and adding strong base to adjust the pH value to 7;
(7) resin adsorption treatment: adsorbing and detecting the wastewater with the pH value of 7 by using ion adsorption resin to realize standard discharge;
(8) sludge treatment: and (3) conveying sludge generated in the first-stage to fourth-stage coagulating sedimentation into a sludge concentration tank, periodically putting into a centrifugal dehydrator, allowing the dehydrated filtrate to enter a high-arsenic high-salt wastewater adjusting tank for continuous treatment, and treating a filter cake as hazardous waste.
The further preferable technical scheme is as follows: in the step (1), the crystallization and desalination pretreatment is to feed the high-arsenic high-salt gallium arsenide wastewater into a crystallization tank for crystallization, dewater the wastewater by a centrifuge after crystallization, and feed the filtrate after dewatering into a high-arsenic high-salt wastewater adjusting tank.
The further preferable technical scheme is as follows: in the step (2), before evaporation treatment, the pH is adjusted to 7 by sodium hydroxide, the evaporation treatment is carried out by using a single-effect evaporator, and the single-effect evaporator adopts a heat-conducting oil furnace as a heat source.
The further preferable technical scheme is as follows: the flocculating agent is basic aluminum chloride and polyacrylamide
The further preferable technical scheme is as follows: in the step (4), the water in the comprehensive adjusting tank can be mixed water in the steps (1), (2) and (3), and the precipitating agent is ferrous sulfate and calcium chloride.
The further preferable technical scheme is as follows: in the step (5), the group A materials are ferrous sulfate and hydrogen peroxide, and the group B materials are ferrous sulfate and ozone.
The further preferable technical scheme is as follows: in the step (5), the pH regulator used for raising the pH is sodium hydroxide, and the pH regulator used for lowering the pH is sulfuric acid.
The further preferable technical scheme is as follows: in the step (5), after the catalytic oxidation of the ozone is finished and before the four-stage coagulating sedimentation, the PH value of the wastewater is adjusted to 8.
The further preferable technical scheme is as follows: in the step (6), the oxidizing agent is sodium hypochlorite, and the reducing agent is sodium bisulfite.
The further preferable technical scheme is as follows: in the step (7), the arsenic content in the dischargeable wastewater is below 0.1 mg/L.
Compared with the prior art, the technical scheme of the invention has the following advantages/beneficial effects:
1. the Fenton reaction combines with ozone catalytic oxidation reaction, can oxidize and get rid of COD, reduces the Zeta electric potential of superfine grinding suspended solid, simultaneously with trivalent arsenic oxidation for pentavalent arsenic and deposit, compare in ordinary Fenton reaction or ozone catalytic oxidation reaction, combine to utilize the synergism of these two kinds of reactions, can be faster better realization to the processing of containing arsenic waste water, effectively reduce the required time of waste water treatment.
2. The high-concentration arsenic-containing and phosphorus-containing wastewater in a low-temperature state is firstly crystallized and desalted according to the temperature, and then is subjected to evaporation arsenic and phosphorus removal and desalting pretreatment. The condensate also contains a large amount of volatilized arsenic, and the arsenic-containing grinding wastewater with low concentration is mixed and treated together, so that the problems of pipeline blockage, difficult precipitation and large dosage in the traditional treatment process of the high-concentration arsenic-containing and phosphorus-containing wastewater are well solved.
3. The traditional flocculation precipitation method cannot precipitate a large amount of superfine suspended matters in the grinding wastewater, and the main reason is that a large amount of COD is possibly adsorbed by fine particle colloid, so that the colloid forms a space stable state or a vacancy stable state; these ultrafine suspensions are particularly prone to clogging of filtration or adsorption equipment during back-end membrane filtration or resin adsorption, so that ultrafine suspensions must be removed. In the invention, advanced oxidation reaction is adopted to degrade COD, so that the Zeta potential absolute value of the particulate matter is gradually reduced, the superfine suspended particles can be successfully destabilized, and then advanced treatment can be carried out by resin adsorption, so that the arsenic content in the discharged water is less than 0.1 mg/L.
4. According to experimental results, the method adopts the primary Fenton oxidation, the secondary ozone oxidation and the flocculation precipitation pretreatment process, can successfully destabilize and precipitate the submicron suspended matters, has clear effluent water quality, and eliminates the influence of the submicron suspended matters on subsequent advanced treatment.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a flow chart of the comprehensive treatment method of high-arsenic high-salt wastewater and arsenic-containing grinding wastewater of a gallium arsenide chip
FIG. 2 shows the water quality test results of water samples at different treatment stages of the comprehensive treatment method for high-arsenic high-salinity wastewater and arsenic-containing grinding wastewater of gallium arsenide chips
FIG. 3-FIG. 5 show Zeta potential detection results of water samples at different treatment stages of the comprehensive treatment method for high-arsenic high-salinity wastewater and arsenic-containing grinding wastewater of gallium arsenide chip
FIG. 6-FIG. 8 show the particle size detection results of water samples in different treatment stages of the comprehensive treatment method for high-arsenic high-salinity wastewater and arsenic-containing grinding wastewater of gallium arsenide chip of the invention
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are a part of the embodiments of the present invention, not all of the embodiments of the present invention. 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. Thus, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention.
Example 1:
the embodiment provides a comprehensive treatment method of high-arsenic high-salt wastewater of gallium arsenide chips and arsenic-containing grinding wastewater, which is particularly suitable for small-volume gallium arsenide chip wastewater generated in scientific research institutions or experimental places, because the high-arsenic high-salt gallium arsenide wastewater has a high salt content (> 12%), and mainly comprises sodium chloride, sodium arsenate and sodium phosphate, wherein the solubility of the sodium arsenate and the sodium phosphate is reduced along with temperature reduction, and when the environmental temperature is less than or equal to 10 ℃, the high-arsenic high-salt gallium arsenide wastewater is crystallized to block pipelines and pumps, so that when the temperature is less than or equal to 10 ℃ in winter, the high-arsenic high-salt gallium arsenide wastewater is crystallized in an advanced crystallization tank, then is dehydrated by a centrifuge, and the dehydrated filtrate enters a high-arsenic high-salt wastewater regulating tank and is subjected to external treatment. When the environmental temperature is higher than 10 ℃, the high-arsenic high-salt gallium arsenide wastewater directly enters a high-arsenic high-salt wastewater regulating tank to be treated.
As the concentration of arsenic (1500-2000mg/L) and phosphorus (1500mg/L) in the high-arsenic high-salt wastewater is too high, the effect is not good by directly adopting an iron salt precipitation method, mud and water can not be separated, and the low-arsenic high-salt wastewater is diluted by 50 times and then precipitated by using iron salt, so that the effect is remarkable, and the low-arsenic high-salt wastewater has a good precipitation effect. Then high salt, high arsenic and high phosphorus in the wastewater are combined, the pH value is adjusted to be neutral, and the neutral pH value is directly fed into an evaporator for evaporation treatment; part of arsenic and ammonia nitrogen are removed through condensate, and a large amount of arsenic salt, phosphorus salt and sodium chloride are removed through evaporation and crystallization, so that the problems that high-concentration arsenic and phosphorus cannot be precipitated and high-concentration salt affects deep treatment are solved. Because the water quantity of the part of water is not large, the investment of the conventional evaporator (multi-effect evaporation, MVR evaporation and the like) is overlarge, a large amount of steam is needed, and a steam generator device is also needed to be matched. Therefore, the single-effect electric evaporator is adopted by combining water quantity, the heat conduction oil furnace is used as a heat source, and the operation is convenient. Since part of the arsenic will be volatilized into the condensate, the condensate will also need to be treated again for arsenic removal. The specific flow is shown in fig. 1, and the specific steps are as follows:
(1) high-arsenic high-salt wastewater crystallization desalination and single-effect evaporation pretreatment
When the environmental temperature is less than or equal to 10 ℃, feeding the high-arsenic high-salt gallium arsenide wastewater into a crystallizing tank for crystallization, dehydrating the crystallized high-arsenic high-salt gallium arsenide wastewater by using a centrifugal machine 1, and feeding the dehydrated filtrate into a high-arsenic high-salt wastewater adjusting tank;
when the environmental temperature is higher than 10 ℃, directly feeding the high-arsenic high-salt gallium arsenide wastewater into a high-arsenic high-salt wastewater regulating tank;
sending the wastewater in the high-arsenic high-salt wastewater adjusting tank into a pH adjusting tank, lifting the high-arsenic high-salt wastewater into the pH adjusting tank by using an adjusting tank lifting pump, adding sodium hydroxide to adjust the pH value to 7, and carrying out aeration stirring on the pH adjusting tank by using an aeration fan; then the steam is lifted to a single-effect evaporator by a single-effect evaporation system water inlet pump for evaporation crystallization, the steam sequentially passes through a gas-water separator, a condensing heat exchanger and a condenser to become condensed water, and then the condensed water is lifted to a comprehensive regulating tank by a condensed water negative pressure pump; the crystallized salt in the evaporator is dehydrated by a centrifuge 2 and then outsourced, the mother liquor enters a mother liquor box, then is pumped back to the evaporator by a mother liquor pump for evaporation again, and is periodically outsourced according to the COD concentration.
(2) Arsenic-containing grinding wastewater precipitation pretreatment
The arsenic-containing grinding wastewater firstly enters a flocculation sedimentation tank 1, flocculating agents PAC and PAM are added for primary coagulation sedimentation, and partial phosphorus reacts with PAC to generate aluminum phosphate sediment to be removed. The wastewater enters a comprehensive adjusting tank, is mixed with the high-arsenic high-salt wastewater condensate, is added with sulfuric acid or sodium hydroxide to adjust the pH value to 7, and is aerated and stirred by an aeration fan in the comprehensive adjusting tank; at this time, the wastewater contains low concentrations of arsenic, phosphorus, fluorine, ammonia nitrogen and COD.
(3) Arsenic, phosphorus, fluorine and precipitation treatment of comprehensive wastewater
Adding acid or alkali into the comprehensive adjusting tank to adjust the pH value of the tank to be neutral; then, the wastewater is sent into an arsenic, phosphorus and fluorine removal reaction tank, and then ferrous sulfate and calcium chloride are added into the wastewater to precipitate arsenic, phosphorus and fluorine ions in the wastewater; and then, adding flocculating agents PAC and PAM into the wastewater, performing two-stage coagulation precipitation, separating precipitates containing arsenic, phosphorus and fluorine into sludge, and simultaneously removing part of ground suspended matters again.
(4) Fenton ozone secondary oxidation and precipitation treatment
Because the wastewater contains a large amount of COD and has poor biodegradability, advanced oxidation is required for removal. Meanwhile, under the condition that a large amount of ultrafine suspended matters in the arsenic-containing grinding wastewater exist in COD, the Zeta potential absolute value is large, destabilization and agglomeration are not easy, and advanced oxidation is also needed to remove the COD. In the traditional method, the COD can be only reduced to 64mg/L by adopting pure Fenton oxidation, and the standard of 30mg/L cannot be reached; the COD can be reduced to 33mg/L only by pure ozone catalytic oxidation, and the COD can not reach the standard of 30 mg/L. Through research, the inventor finds that the COD can be reduced to 12.8mg/L by performing Fenton oxidation and then performing ozone catalytic oxidation, the standard discharge can be realized, the lower the COD value is, the smaller the Zeta potential absolute value of the superfine suspended matters is, the more easy the destabilization and precipitation are, and meanwhile, the arsenic can be precipitated again.
Sending the wastewater subjected to the two-stage coagulation precipitation in the step (3) into a Fenton oxidation tank, and adding sulfuric acid to adjust the pH value to be strong acid (the pH value is 3); adding ferrous sulfate and hydrogen peroxide into the wastewater to carry out Fenton reaction, oxidizing to remove COD, reducing the Zeta potential of the superfine grinding suspended matters, and oxidizing trivalent arsenic into pentavalent arsenic and precipitating;
after the Fenton reaction is finished, adjusting the pH value of the wastewater to 7, adding a coagulant aid PAM, and performing three-stage coagulating sedimentation; separating the precipitate containing arsenic, phosphorus and iron into sludge, removing part of superfine grinding suspended matters, and allowing the supernatant of the three-section coagulating sedimentation tank to enter an intermediate water tank 1.
The supernatant is lifted to an ozone oxidation tank by a lifting pump of the intermediate water tank 1, ozone generated by an ozone generator is introduced, iron ions in the wastewater are used as a catalyst to carry out catalytic oxidation of the ozone, COD is removed by secondary oxidation, and Zeta potential of superfine grinding suspended matters is reduced. After the catalytic oxidation of ozone is finished, adding sodium hydroxide to adjust the pH of the wastewater to 8, adding flocculating agents PAC and PAM into the wastewater, and performing four-stage coagulation precipitation to finish COD oxidation and precipitation separation of arsenic, phosphorus, iron and superfine grinding suspended matters, wherein the residual COD, arsenic, phosphorus, fluorine and superfine suspended matters in the wastewater are only a small amount.
(5) Ammonia nitrogen removal
In order to reduce ammonia nitrogen in the wastewater, the supernatant of the flocculation sedimentation tank 4 enters an ammonia nitrogen oxidation tank, sodium hypochlorite is added to perform inflection point chlorination to remove ammonia nitrogen, in order to avoid the damage of an oxidant to subsequent resin, the wastewater enters an oxidant removal tank, and sodium bisulfite is added to remove redundant oxidant. After the ammonia nitrogen is oxidized by the sodium hypochlorite, the pH value is reduced, so that the pH value is adjusted to 7 by adding the sodium hydroxide.
(6) Resin adsorption
And finally, in order to ensure that the water quality reaches the standard, ion exchange resin is arranged to adsorb arsenic, namely, the water treated in the step (5) is adsorbed by the ion exchange resin, and the arsenic in the effluent is ensured to be below 0.1 mg/L.
And (6) delivering the water treated in the step (5) into an intermediate water tank 2, lifting the water to a special ion adsorption resin for adsorption by an ion exchange system water inlet pump, discharging the discharged water when the discharged water reaches the standard, and delivering the discharged water into the intermediate water tank 1 for secondary treatment when the discharged water does not reach the standard.
(7) Sludge treatment
In the embodiment, sludge generated by the first-stage coagulation sedimentation, sludge generated by the second-stage coagulation sedimentation, sludge generated by the third-stage coagulation sedimentation and sludge generated by the fourth-stage coagulation sedimentation are respectively sent into a sludge concentration tank for collection, and are pumped into the centrifuge 1 or the centrifuge 2 in the step (1) by a sludge concentration tank lifting pump for dehydration, mud cakes are transported outside for treatment, and filtrate enters a high-arsenic high-salt wastewater adjusting tank for new treatment.
Known in the traditional high-concentration arsenic wastewater treatment, the wastewater is very easy to crystallize and block pipelines under the condition of low temperature, and the traditional flocculation precipitation method cannot precipitate a large amount of superfine suspended matters in the grinding wastewater, so that the required dosage is too large due to high concentration. The main reason for this is probably that the fine particle colloids adsorb a large amount of COD, resulting in the colloids forming a steric or vacancy stable state; these ultrafine suspensions are particularly prone to clogging of filtration or adsorption equipment during back-end membrane filtration or resin adsorption, so that ultrafine suspensions must be removed. In the invention, oxidation reaction is adopted to degrade COD, and water quality detection of water samples at different treatment stages shows that the Zeta potential absolute value of the particulate matter is gradually reduced, so that the superfine suspended particles can be successfully destabilized, and then advanced treatment can be carried out by resin adsorption, so that the arsenic content in the discharged water is less than 0.1 mg/L.
The experimental results shown in the attached figures 2-8 show that the primary Fenton oxidation, the secondary ozone oxidation and the flocculation precipitation pretreatment process are adopted, the submicron suspended matters can be successfully destabilized and precipitated, the Zeta potential and particle size detection results of the particles are continuously reduced along with the advancement of multi-stage treatment, and the treatment modes of Fenton oxidation, ozone oxidation and multi-stage flocculation are creatively combined to bring a remarkable progress effect. The high-concentration arsenic wastewater treated by the method has clear effluent quality, and eliminates the influence of submicron suspended matters on subsequent advanced treatment. Compared with the traditional method, the method has the advantages of more thorough treatment effect, less dosage and obviously improved economic benefit.
The single-effect electric evaporator with the heat-conducting oil furnace as the heat source is adopted to carry out evaporation crystallization pretreatment on the high-arsenic high-salt wastewater, so that the problem that high-concentration arsenic, phosphorus and salt are difficult to precipitate is effectively solved, the dosage of the medicament is greatly reduced, the yield of hazardous wastes is reduced, and better economic benefit and environmental benefit are achieved;
the method adopts sodium hypochlorite breakpoint chlorination to oxidize and remove a small amount of ammonia nitrogen, and adopts a reducing agent to remove redundant oxidant, so as to ensure stable operation of ion exchange resin for subsequent treatment;
the invention adopts the special ion exchange resin for arsenic removal to carry out advanced treatment on arsenic, thereby ensuring that the effluent reaches the standard stably;
the method has reasonable process, can meet the requirement of industrial treatment of the high-arsenic high-salt gallium arsenide chip wastewater, can discharge the treated wastewater after reaching the standard, has obvious economic value and environmental value, and has practical significance for promoting the development of semiconductor production.
Table one: monitoring results of wastewater
The above table shows the monitoring results of the high-arsenic high-salt gallium arsenide chip wastewater treated by the method of the invention, tests show that the arsenic content is obviously reduced and is far lower than the discharge limit which can be achieved by the traditional arsenic wastewater treatment method, and the comprehensive treatment method of the high-arsenic high-salt gallium arsenide chip wastewater and the grinding wastewater containing arsenic provided by the invention has extremely obvious progress effect and outstanding substantive progress.
The above is only a preferred embodiment of the present invention, and it should be noted that the above preferred embodiment should not be considered as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. It will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the spirit and scope of the invention, and these modifications and adaptations should be considered within the scope of the invention.
Claims (10)
1. A comprehensive treatment method for high-arsenic high-salt wastewater and arsenic-containing grinding wastewater of a gallium arsenide chip is characterized by comprising the following steps:
(1) crystallizing and desalting the high-depth high-salinity wastewater and performing single-effect evaporation pretreatment: when the environmental temperature is less than or equal to 10 ℃, carrying out crystallization and desalination pretreatment, and sending the dehydrated filtrate into a high-arsenic high-salt wastewater adjusting tank; when the environmental temperature is higher than 10 ℃, directly feeding the high-arsenic high-salt gallium arsenide wastewater into a high-arsenic high-salt wastewater regulating tank;
(2) sending the wastewater in the high-arsenic high-salt wastewater adjusting tank into a pH adjusting tank, adjusting the pH, and then performing evaporation treatment to respectively obtain condensate, crystallized salt and mother liquor; sending the condensate into a comprehensive adjusting tank; carrying out outward transportation on the crystallized salt as hazardous waste; the mother liquor returns to the evaporator, and the periodically transported part is treated as hazardous waste;
(3) precipitation pretreatment of arsenic-containing grinding wastewater: firstly, the arsenic-containing grinding wastewater enters a flocculation sedimentation tank, a flocculating agent is added for primary coagulation sedimentation, most of grinding suspended matters and phosphorus are removed, and then the arsenic-containing grinding wastewater is sent into a comprehensive regulation tank;
(4) performing arsenic, phosphorus, fluorine and precipitation treatment on the comprehensive wastewater, adjusting the pH value in a comprehensive adjusting tank to be neutral, sending the wastewater into an arsenic, phosphorus and fluorine removal reaction tank, adding a precipitator to precipitate arsenic, phosphorus and fluorine ions, adding a flocculating agent to perform two-stage coagulation precipitation, and sending the wastewater into a Fenton oxidation tank after flocculation precipitation;
(5) performing secondary oxidation and precipitation treatment by Fenton ozone: after the PH value of the wastewater is adjusted to 3, adding the group A materials to carry out Fenton reaction, after the Fenton reaction is finished, adjusting the PH value of the wastewater to 8, adding a coagulant aid to carry out three-section coagulating sedimentation, after the sedimentation is finished, introducing the wastewater into an intermediate water tank, and adding the group B materials to carry out ozone catalytic oxidation reaction; after the catalytic oxidation of ozone is finished, adding a flocculating agent into the wastewater to carry out four-section coagulating sedimentation;
(6) ammonia nitrogen treatment: adding an oxidant into the wastewater after the four-stage coagulation and precipitation is finished, removing ammonia nitrogen, adding a reducing agent to remove redundant oxidant, and adding strong base to adjust the pH value to 7;
(7) resin adsorption treatment: adsorbing and detecting the wastewater with the pH value of 7 by using ion adsorption resin to realize standard discharge;
(8) sludge treatment: and (3) conveying sludge generated in the first-stage to fourth-stage coagulating sedimentation into a sludge concentration tank, periodically putting into a centrifugal dehydrator, allowing the dehydrated filtrate to enter a high-arsenic high-salt wastewater adjusting tank for continuous treatment, and treating a filter cake as hazardous waste.
2. The method for comprehensively treating high-arsenic high-salt wastewater and arsenic-containing grinding wastewater of a gallium arsenide chip as claimed in claim 1, wherein in step (1), the crystallization desalination pretreatment is to feed the high-arsenic high-salt gallium arsenide wastewater into a crystallization tank for crystallization, and after crystallization, the high-arsenic high-salt gallium arsenide wastewater is dewatered by a centrifuge, and the filtrate after dewatering is fed into a high-arsenic high-salt wastewater conditioning tank.
3. The method for comprehensively treating high-arsenic high-salt wastewater and arsenic-containing grinding wastewater of gallium arsenide chips as claimed in claim 1, wherein in step (2), before evaporation treatment, the pH is adjusted to 7 by sodium hydroxide, the evaporation treatment is performed by using a single-effect evaporator, and the single-effect evaporator uses a heat-conducting oil furnace as a heat source.
4. The method for comprehensively treating high-arsenic high-salinity wastewater and arsenic-containing grinding wastewater of a gallium arsenide chip according to claim 1, wherein the flocculating agent is aluminum chlorohydrate or polyacrylamide.
5. The method for comprehensively treating high-arsenic high-salt wastewater and arsenic-containing grinding wastewater of a gallium arsenide chip as claimed in claim 1, wherein in step (4), the water in the comprehensive regulation tank can be the mixed water of step (1), step (2) and step (3), and the precipitating agent is ferrous sulfate and calcium chloride.
6. The comprehensive treatment method for high-arsenic high-salinity wastewater and arsenic-containing grinding wastewater of gallium arsenide chips as claimed in claim 5, wherein in step (5), said group A materials are ferrous sulfate and hydrogen peroxide, and said group B materials are ferrous sulfate and ozone.
7. The method of claim 1, wherein in step (5), the pH adjusting agent used for increasing pH is sodium hydroxide, and the pH adjusting agent used for decreasing pH is sulfuric acid.
8. The method for comprehensively treating high-arsenic high-salt wastewater and arsenic-containing grinding wastewater of a gallium arsenide chip as claimed in claim 1, wherein in step (5), after the completion of the catalytic oxidation of ozone, the pH value of the wastewater is adjusted to 8 before the four-stage coagulation and precipitation.
9. The method for comprehensively treating high-arsenic high-salt wastewater and arsenic-containing grinding wastewater of a gallium arsenide chip as claimed in claim 1, wherein in step (6), said oxidizing agent is sodium hypochlorite and said reducing agent is sodium bisulfite.
10. The method for comprehensively treating high-arsenic high-salt wastewater and arsenic-containing grinding wastewater of gallium arsenide chips according to any of claims 1 to 9, wherein in step (7), the arsenic content in the dischargeable wastewater is below 0.1 mg/L.
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