CN110255823B - High-zinc high-ammonia-nitrogen high-thiourea wastewater treatment process - Google Patents
High-zinc high-ammonia-nitrogen high-thiourea wastewater treatment process Download PDFInfo
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Abstract
The invention discloses a high-zinc high-ammonia-nitrogen high-thiourea wastewater treatment process, and belongs to the field of wastewater treatment. The invention mainly comprises 5 treatment processes, namely zinc removal, ammonia nitrogen removal, thiourea removal, biochemical treatment and deep flocculation precipitation. The three steps are used for respectively removing zinc, ammonia nitrogen and oxidative decomposition thiourea, the biochemical treatment is used for removing organic matters in the wastewater and further removing the ammonia nitrogen, total nitrogen and COD remained in the front, then fine suspended matters are removed through deep flocculation precipitation, and the residual filtrate wastewater reaches the standard and is discharged outside to complete the whole treatment process. The process disclosed by the invention is used for treating the high-zinc high-ammonia-nitrogen high-thiourea wastewater, the problem of zinc ion emission of the wastewater can be effectively solved, the energy consumption can be reduced, byproducts can be recovered, the environment-friendly requirement is met, good economic benefits can be generated, and the sustainable development requirement is met.
Description
Technical Field
The invention relates to the field of wastewater treatment, in particular to a treatment process of solar cell industrial wastewater, and particularly relates to a treatment process of high-zinc high-ammonia nitrogen high-thiourea wastewater.
Background
In recent years, the development of the photovoltaic industry in China is rapid, and a new generation of thin film solar cell has low production cost, low pollution, no decline, good low light performance and high photoelectric conversion efficiency, so that the thin film solar cell becomes a new investment hotspot for investment in the domestic photovoltaic field. The production process of the thin-film solar cell can generate wastewater containing a large amount of metal zinc, ammonia nitrogen and macromolecular organic matters. The traditional treatment mode mainly adopts a single treatment method, such as a precipitation method, an ion exchange method, a membrane separation method, a biological method, an adsorption method and the like, and focuses on treating metal zinc, ammonia nitrogen and thiourea, so that the treatment method meets the requirement of indirect discharge of a newly-built project in the discharge Standard of pollutants for Battery industry (GB 30484-2013).
The high-zinc high-ammonia nitrogen high-thiourea wastewater mainly comes from the solar cell industry, main pollutants in the wastewater are zinc sulfate, ammonia water and thiourea, the corresponding concentrations of the main pollutants are all more than 10000mg/L, the wastewater is strongly alkaline due to the existence of a large amount of ammonia water, and the pH value is about 12. According to the data, the zinc ion will generate complexation reaction with ammonia water under alkaline condition to generate [ Zn (NH)3)4]2+The complex can exist stably under alkaline condition. The conventional treatment method of the wastewater comprises the following steps: firstly, removing zinc ions in the wastewater, adding a large amount of acid into the wastewater, adjusting the pH of the wastewater to 8-9, and changing the zinc ions into zinc hydroxide precipitate for removal. The process mainly utilizes the ionization reaction of ammonia water, and H is added into the waste water+Make the ionization balance of ammonia water to NH4 +The ammonia water concentration is reduced by directional movement, and zinc ions are released and then react with OH in the wastewater-Combine to form Zn (OH)2，Zn(OH)2The precipitate can stably exist under the condition of the pH value, and the aim of removing zinc ions is fulfilled after the precipitate is treated by a sedimentation tank.
However, in the actual engineering design, the ionization of ammonia water is a reversible reaction, and after the ionization reaches equilibrium, a part of zinc-ammonia complex still remains in the wastewater, and the zinc ions in the part of complex can cause the blockage of ammonia distillation equipment at the later stage, thereby affecting the stable operation of the ammonia distillation system. In addition, the added acid can increase the salt content in the treatment system, thereby increasing the load of the subsequent wastewater treatment unit, particularly the biochemical treatment unit at the later stage, and a large amount of salt can cause microbial poisoning, so that the whole biochemical system is broken down, and the whole wastewater treatment effect is not ideal.
In view of the above reasons, it is urgently needed to find a more optimized process method for treating the high-zinc high-ammonia nitrogen high-thiourea wastewater.
Disclosure of Invention
The invention aims to provide a high-zinc high-ammonia-nitrogen high-thiourea wastewater treatment process, which aims to solve the problems of high energy consumption and high cost of the existing treatment process.
The technical problem to be solved by the invention is realized by adopting the following technical scheme.
A high-zinc high-ammonia nitrogen high-thiourea wastewater treatment process comprises the following steps:
(1) removing zinc: sequentially heating, precipitating, first-stage zinc removal and second-stage zinc removal the high-zinc high-ammonia-nitrogen high-thiourea wastewater to obtain zinc-removed waste liquid; wherein the heating temperature is 40-50 ℃; the first-stage zinc removal process comprises the steps of adjusting the pH value of filtrate obtained after precipitation to 8-9 by using acid liquor, and then precipitating to separate solid from liquid; the second-stage zinc removal process is to add a precipitator into the filtrate obtained after the first-stage zinc removal, and remove the precipitate;
(2) removing ammonia nitrogen: adjusting the pH value of the dezincification waste liquid to be more than 12 by using alkali liquor, then carrying out primary ammonia distillation, absorbing the obtained ammonia gas by using pure water and converting the ammonia gas into ammonia water for recycling, wherein the residual liquid is the ammonia nitrogen removal waste liquid;
(3) and (3) thiourea removal: sequentially carrying out advanced oxidation and ozone removal on the ammonia nitrogen removal waste liquid, then sequentially adding alkali, PAC and PAM, adjusting the pH value of the solution to 8-9 by using the alkali liquor, removing the catalyst in the advanced oxidation step through flocculation precipitation, then adding alkali liquor into the obtained filtrate to adjust the pH value to be more than 12, and then carrying out secondary ammonia distillation to obtain the thiourea removal waste liquid;
(4) biochemical treatment;
(5) deep flocculation and precipitation; the effluent reaches the standard and is discharged outside.
The invention aims at the high-zinc high-ammonia nitrogen high-thiourea wastewater, wherein the contents of zinc ions, ammonia nitrogen and thiourea are all more than 10000mg/L, such as coating wastewater and ammonia gas spraying absorption wastewater in the solar cell industry. Aiming at the wastewater, the invention mainly comprises 5 treatment processes, namely zinc removal, ammonia nitrogen removal, thiourea removal, biochemical treatment and deep flocculation precipitation. The three steps are used for respectively removing zinc, ammonia nitrogen and thiourea, the biochemical treatment is used for removing organic matters in the wastewater and further removing the ammonia nitrogen, total nitrogen and COD remained in the front, then fine suspended matters are removed through deep flocculation precipitation, and the residual filtrate wastewater reaches the standard and is discharged outside to complete the whole treatment process.
In the process of removing zinc, the invention firstly heats the high-zinc high-ammonia nitrogen high-thiourea wastewater, keeps the heating temperature of the waste liquid within the range of 40-50 ℃, and makes the substances in the waste liquid pre-react with each other by heat preservation and heating and be in a reaction state all the time. When the coating wastewater is discharged from the production process section, the temperature is about 60 ℃, the coating wastewater is directly discharged into the regulating tank from a discharge port of process equipment by using a heat insulation pipeline, and after heat insulation measures are taken for the regulating tank, only a small amount of steam is added to heat the wastewater to keep the temperature at 40-50 ℃, so that the energy consumption can be effectively saved. By adopting the method for removing zinc by heating the wastewater, on one hand, thiourea in the wastewater can be continuously decomposed, and on the other hand, sulfide ions generated by decomposition and zinc in the wastewater generate precipitation to remove zinc. Not only can part of thiourea be decomposed, but also the dosage and the retention time of the advanced oxidation unit are reduced; part of sulfur elements in the thiourea can be removed, the salt content of the sulfur elements converted into sulfate in the advanced oxidation stage is reduced, and the normal operation of a rear-end biochemical system is ensured; meanwhile, part of zinc is removed, and the dosage of subsequent zinc removal is reduced. Then, carrying out solid-liquid separation on the wastewater after the pre-reaction through precipitation to remove zinc sulfide precipitate generated by the reaction in the wastewater. The precipitate of zinc sulfide is formed by decomposition of thiourea to S under heating2-The equilibrium of the zinc ammine complex is shifted towards Zn2+Movement, S2-By reaction of Zn2+And is produced. Thus, the invention can remove a part of zinc preferentially without adding any additive through the two steps of heating and precipitating, the operation is very convenient, and the cost of raw materials can be reduced. Further, the present invention can be used in the industry when heating is performedThe waste water is directly heated by the steam, so that the loss and waste of heat energy are avoided, and the method is green and environment-friendly. After heating, heat preservation and precipitation, the invention removes zinc twice: first-stage zinc removal and second-stage zinc removal, and removing zinc ions in the wastewater. In the first-stage zinc removal, the pH value of the wastewater is adjusted to be 8-9 by acid liquor to form zinc hydroxide precipitate, so that zinc ions are removed. In the second-stage zinc removal, the invention removes zinc ions by adding a precipitator and converting the residual zinc ions into zinc sulfide precipitates.
The invention removes zinc by two completely different methods, and is mainly based on the following points: firstly, adding acid can not remove a large amount of zinc ions, because zinc hydroxide belongs to amphoteric hydroxide, the stable existing pH value is 8-9, and the zinc hydroxide can be dissolved again when the pH value exceeds the range; secondly, a large amount of precipitator sodium sulfide is added to remove most of zinc ions, but the price of the sodium sulfide is higher than that of sulfuric acid, so that the operation cost is higher; in addition, sodium sulfide has high toxicity and great occupational health hazard. Therefore, the invention adopts two different modes to remove zinc respectively, can achieve effective zinc removal and simultaneously control the cost.
In the process of removing ammonia nitrogen, the invention adjusts the pH value of the waste liquid to be more than 12 by using the alkali liquor on the basis of the zinc-removing waste liquid, and ammonia nitrogen in the waste liquid is converted into ammonia gas to be removed by heating and distilling the waste liquid. Before water enters ammonia distillation, the pH value needs to be adjusted to be more than or equal to 12, and in the ammonia water decomposition process, when the concentration of hydroxide ions is increased, the balance is moved leftwards to generate ammonia water, so that the ammonia nitrogen removal effect is better.
In the process of removing thiourea, the invention adopts an advanced oxidation method to completely oxidize the thiourea in the ammonia nitrogen removal waste liquid, thereby realizing the oxidative decomposition of the thiourea. Although thiourea in the waste liquid is decomposed by the advanced oxidation method, the intermediate product of the decomposition is not removed, and in consideration of the integrity and the continuity of the treatment process, the ozone removing step is carried out after the advanced oxidation, so that the condition that the ozone causes microorganism poisoning in the subsequent biochemical process to influence the subsequent biochemical treatment is avoided. After ozone is removed, the method adds a mode of adding alkali, PAC and PAM and adjusting the pH value of the solution to 8-9 by using alkali liquor, so that the waste liquid after ozone removal is subjected to flocculation precipitation to remove a catalyst introduced in advanced oxidation and avoid subsequent microbial poisoning. The invention adjusts the pH value of the solution to 8-9, which is the optimal range for the complete precipitation of the catalyst, otherwise the catalyst cannot be completely removed, and in addition, the addition of PAC and PAM helps the precipitation and removes some suspended substances existing in the wastewater. In addition to taking into account the impurities introduced by the advanced oxidation, the present invention also envisages a secondary ammonia distillation step in the process of removing thiourea. This is because nitrogen in thiourea is converted into ammonia nitrogen and total nitrogen during the oxidative decomposition of thiourea. Therefore, the invention aims at the characteristic of high thiourea content in the wastewater, the concentration of ammonia nitrogen and total nitrogen generated in the oxidation process is necessarily high, the ammonia nitrogen and the total nitrogen generated by decomposing thiourea are removed by secondary ammonia distillation, the microbial poisoning is avoided, and the normal operation of a biochemical unit is ensured.
After the three processes, the zinc and ammonia nitrogen are removed, the thiourea is completely decomposed, the introduced additional substances are also partially removed, and the discharge standard is reached after biochemical treatment and deep flocculation.
Further, in a preferred embodiment of the present invention, the biochemical treatment in step (4) comprises the following steps: mixing the waste liquid of the desulfurized urea with the glass drilling waste water, and carrying out biochemical treatment by adopting A/O after hydrolytic acidification.
When the biochemical treatment is carried out, the desulfurized urea waste liquid and the glass drilling waste water are mixed, on one hand, the desulfurized urea waste liquid is diluted by the glass drilling waste liquid to facilitate the subsequent A/O biochemical treatment, and on the other hand, the glass drilling waste liquid can be discharged after being subjected to flocculation precipitation treatment. According to the invention, the desulfurized urea waste liquid and the glass drilling waste water are mixed and then subjected to biochemical treatment, so that the standard discharge of the high-ammonia nitrogen high-thiourea high-zinc waste water is facilitated, and the requirement that the drilling waste water needs flocculation and precipitation can be met.
Further, in a preferred embodiment of the present invention, the specific process of deep flocculation precipitation in step (5) is: and adding PAC and PAM into the waste liquid after biochemical treatment in sequence, and removing micro suspended substances after coagulating sedimentation.
Further, in a preferred embodiment of the present invention, the step (3) further includes deep zinc removal after the second ammonia distillation, and the deep zinc removal process includes: and (3) sequentially adding a heavy metal capture agent, PAC (polyaluminium chloride) and PAM (polyacrylamide) into the waste liquid obtained after secondary ammonia distillation, and removing zinc ions in the waste liquid after flocculation and precipitation.
The invention further adds a step of 'deep dezincification' to be taken as a security measure. In actual environment, ammonia water and zinc ions in the wastewater can form a zinc-ammonia complex, which is a reversible balance, and a part of zinc ions in the wastewater can not be effectively removed due to the complex in the zinc removal process. After the wastewater is treated by ammonia distillation twice, the ammonia nitrogen concentration is reduced, and zinc ions in the zinc-ammonia complex before ammonia distillation can be released. Therefore, the invention can carry out deep zinc removal after secondary ammonia distillation, and can effectively reduce the concentration of zinc ions in the wastewater. In addition, the tolerance limit of the microorganism to zinc ions is about 10mg/L, and if the concentration of the zinc ions after secondary ammonia distillation is lower than 10mg/L, deep zinc removal measures can be omitted.
Further, in a preferred embodiment of the present invention, the specific process of the advanced oxidation treatment step in step (3) is: ozone is introduced into the ammonia nitrogen removal waste liquid, and hydrogen peroxide and ferrous sulfate heptahydrate serving as a catalyst are added.
Further, in a preferred embodiment of the present invention, the heavy metal scavenger in step (3) is an organic sulfur heavy metal scavenger.
Further, in a preferred embodiment of the present invention, the primary ammonia distillation and the secondary ammonia distillation are positive pressure ammonia distillation.
Further, in a preferred embodiment of the present invention, the acid solution is sulfuric acid, the alkali solution is sodium hydroxide solution, and the precipitant is sodium sulfide.
Further, in a preferred embodiment of the present invention, the processing process further includes:
(6) sludge treatment: collecting sludge obtained in the steps of removing zinc, ammonia nitrogen and thiourea in a chemical sludge storage tank, and then sequentially dehydrating and drying the sludge.
Further, in a preferred embodiment of the present invention, the sludge treatment in step (6) further comprises: collecting the sludge subjected to hydrolytic acidification and biochemical treatment in a biochemical sludge storage tank, and then sequentially dehydrating and drying the sludge.
The invention has the beneficial effects that:
according to the invention, zinc is removed by heating the wastewater, so that part of thiourea can be decomposed, and the dosage and the retention time of the advanced oxidation unit are reduced; part of sulfur elements in the thiourea can be removed, the salt content of the sulfur elements converted into sulfate in the advanced oxidation stage is reduced, and the normal operation of a rear-end biochemical system is ensured; meanwhile, part of zinc is removed, and the dosage of subsequent zinc removal is reduced. According to the invention, ammonia nitrogen is removed after zinc removal, and considering that the wastewater aimed at by the invention contains zinc ions and ammonia water with high concentration (the concentration is more than 10000 mg/L), the zinc ions and the ammonia water can form a zinc-ammonia complex. According to the invention, multistage zinc removal precipitation is adopted in the zinc removal process, so that most of zinc ions in the wastewater are removed as much as possible, and the problem that the stable operation of equipment is influenced because zinc ions in a zinc-ammonia complex are released and block an ammonia distillation system due to the removal of ammonia nitrogen in the wastewater after the wastewater enters the ammonia distillation system is avoided. The ammonia nitrogen in the wastewater can be prepared into ammonia water, and organic matters, heavy metals and particles are removed after refining treatment so as to reach the standard of electronic-grade ammonia water and be reused for production or export sales.
The invention meets the discharge standard, adopts a biochemical method, has low operation cost and strong impact resistance, and can effectively ensure that the discharged water can meet the discharge standard required by the electronic industry. The sludge is treated by a 'dehydration and drying' method, so that the sludge reduction is realized, and the sludge treatment cost is reduced. The method not only effectively solves the problem of discharge of pollutants such as zinc ions in the wastewater generated in the production and processing of the solar thin film battery, but also recycles the byproduct ammonia water, reduces the enterprise cost, meets the environmental protection requirement, generates good economic benefit and meets the requirement of sustainable development. The invention aims at higher wastewater pollutant concentration, especially considers the reduction treatment of sludge and reduces the sludge disposal amount.
By adopting the treatment process, various pollutants in the high-zinc high-ammonia-nitrogen high-thiourea wastewater can be effectively treated in a targeted manner, and pollutants such as zinc ions, ammonia nitrogen, thiourea and the like in the wastewater can be effectively removed under the conditions of saving energy and reducing energy consumption.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed 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 process flow diagram of an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
FIG. 1 is a flow chart of a treatment process according to an embodiment of the present invention.
For the treatment process of the present invention, the treatment system of the present invention involves 6 treatment units, which are respectively (1) a dezincification unit: removing zinc ions in the wastewater; (2) an ammonia nitrogen removal unit: ammonia nitrogen in the wastewater is removed, and the ammonia gas is absorbed, and the ammonia gas is recycled after being prepared into electronic-grade ammonia water; (3) desulfurizing urea unit: carrying out oxidative decomposition on thiourea in the wastewater to provide conditions for biochemical treatment; (4) a biochemical treatment unit: further removing organic matters, ammonia nitrogen and total nitrogen in the wastewater; (5) a depth processing unit: carrying out flocculation precipitation treatment on the wastewater to remove fine suspended substances in the wastewater; (6) a sludge treatment unit: the sludge is subjected to reduction treatment by 'dehydration and drying', so that the sludge treatment amount is reduced.
The standard of wastewater reaching standards is indirect discharge of a new project of discharge Standard of pollutants for Battery industry (GB30484-2013), and the specific requirements are as follows: COD is less than or equal to 150mg/L, SS is less than or equal to 140mg/L, zinc ions are less than or equal to 1.5mg/L, ammonia nitrogen is less than or equal to 30mg/L, and total nitrogen is less than or equal to 40 mg/L.
Examples
Coating wastewater, ammonia spraying absorption wastewater and glass drilling wastewater generated by a certain solar thin film battery production project. The main pollutants of the coating wastewater and the ammonia spraying absorption wastewater are zinc ions, ammonia nitrogen and thiourea, and the water volume of the coating wastewater is 69m3D, the amount of wastewater water absorbed by ammonia spraying is 1.06m3D; the water content of the glass drilling wastewater is 720m3/d。
After the coating wastewater and the ammonia spraying absorption wastewater are mixed, the concentration of main pollutants is as follows: 13080mg/L zinc ion, 21858mg/L ammonia nitrogen concentration and 45672mg/L thiourea.
After being treated by the zinc removal unit, the concentration of zinc ions in the wastewater is reduced to about 20mg/L, then the wastewater enters a positive pressure ammonia distillation system 1 for primary ammonia distillation treatment, the wastewater and steam carry out mass and heat transfer in a positive pressure ammonia distillation tower, ammonia nitrogen in the wastewater is converted into ammonia gas, the ammonia nitrogen concentration of the wastewater after deamination is reduced to 40mg/L, the ammonia gas is absorbed and converted into ammonia water by pure water, the ammonia water concentration is 19-28%, after being refined, the requirement of the quality of electronic-grade ammonia water can be met, and the ammonia water can be recycled to the production process of solar thin film batteries.
Removing thiourea from the wastewater after ammonia nitrogen removal by advanced oxidation; enabling the wastewater without thiourea to enter a positive pressure ammonia distillation system 2 to continue carrying out secondary ammonia distillation on the wastewater, controlling the ammonia nitrogen concentration in the wastewater after deamination to be 40mg/L, and absorbing the ammonia nitrogen with pure water to prepare electronic grade ammonia water with the concentration of 19-28%; the wastewater after secondary deamination enters a deep zinc removal unit, zinc ions with low concentration in the wastewater are removed by using a heavy metal capture agent, effluent and glass drilling wastewater are mixed and then enter a hydrolytic acidification tank together, macromolecules in the wastewater are decomposed into micromolecules, the effluent enters an A/O biochemical reaction tank, pollutants such as ammonia nitrogen, total nitrogen, COD and the like in the wastewater are continuously removed, and after the biochemical effluent is subjected to deep flocculation precipitation to remove suspended matters in the wastewater, the effluent meets the indirect discharge requirement of a newly-built project in the discharge Standard of pollutants for Battery industry (GB30484-2013) and is discharged.
Chemical sludge and biochemical sludge are separately treated, the chemical sludge and the biochemical sludge respectively enter a sludge storage tank, and after dehydration and drying treatment, the water content of the sludge is 30 percent, and the sludge is transported outside.
The specific operation steps are as follows:
(1) dezincification unit
S1, preheating a regulating reservoir: introducing the coating wastewater into a regulating tank, wherein the concentration of main pollutants is as follows: 13080mg/L zinc ion, 21858mg/L ammonia nitrogen and 45672mg/L thiourea; directly heating the wastewater by using steam, controlling the temperature of the heated wastewater to be 40-50 ℃, taking heat preservation measures for the regulating tank, and preserving the heat of the heated wastewater so that the wastewater is always at the temperature of 40-50 ℃ in the retention time of the regulating tank, thereby being beneficial to the wastewater to be always in a reaction state and forming a first waste liquid;
s2, pre-settling tank: carrying out solid-liquid separation on the waste liquid I through a sedimentation tank, and removing zinc sulfide sediment generated in the waste water to form a waste liquid II;
s3, primary zinc removal: adding sulfuric acid into the waste liquid II by using a metering pump to adjust the pH value of the waste liquid II, adjusting the pH value of the waste water to 8-9, generating a large amount of precipitates, then entering a primary sedimentation tank for solid-liquid separation, and removing zinc hydroxide precipitates in the waste water to form a waste liquid III;
s4, secondary zinc removal: adding a precipitator by using a metering pump, reacting the precipitator with zinc ions in the waste liquid III to generate zinc sulfide precipitate, and removing the zinc ions in the waste water by using a secondary sedimentation tank to form a waste liquid IV; and the concentration of zinc ions in the waste liquid IV is reduced to 20 mg/L.
(2) Ammonia nitrogen removal unit
S5, adjusting the pH value of the waste liquid IV to 12 by using sodium hydroxide, enabling the waste liquid IV to enter an ammonia distillation system 1, performing positive-pressure ammonia distillation, performing mass transfer and heat transfer on waste water and steam in a positive-pressure deamination tower, converting ammonia nitrogen in the waste water into ammonia gas, absorbing and converting the ammonia gas into ammonia water with the concentration of 19% by pure water, refining the ammonia water, enabling the contents of organic matters, heavy metals and particles to meet the quality requirement of electronic-grade ammonia water, recycling the ammonia water into a production process of a thin-film solar cell, forming a waste liquid V by using the remaining waste liquid, and reducing the ammonia nitrogen concentration of the waste liquid V to 40 mg/L.
(3) Thiourea removing unit
S6, advanced oxidation: by using "O3+H2O2Carrying out oxidative decomposition on thiourea in the waste liquid five by a catalyst combined oxidation method to form a waste liquid six, wherein the COD concentration in the waste liquid six is not more than 12800 mg/L;
s7, ozone removal: the waste liquid six enters a buffer pool, and ozone dissolved in the waste water is removed to avoid microbial poisoning in the back-end biochemical process to form a waste liquid seven;
s8, flocculating and precipitating: adding sodium hydroxide by using a metering pump, adjusting the pH value of the waste liquid seven to 8-9, sequentially adding PAC and PAM by using an automatic medicine adding device, and removing a catalyst added in the waste water by using flocculation precipitation so as to avoid microbial poisoning in a back-end biochemical process and form a waste liquid eight;
s9, secondary ammonia distillation: adding sodium hydroxide into a metering pump to adjust the pH value of the waste liquid eight to 12, introducing the waste liquid eight into an ammonia distillation system 2, performing positive-pressure ammonia distillation, performing mass transfer and heat transfer on waste water and steam in a positive-pressure deamination tower, converting ammonia nitrogen in the waste water into ammonia gas, absorbing and converting the ammonia gas into ammonia water with the concentration of 19% through pure water, refining the ammonia water to enable the content of organic matters, heavy metals and particles to meet the quality requirement of electronic-grade ammonia water, recycling the ammonia water into a production process of a thin-film solar cell, forming a waste liquid nine from the remaining waste liquid, and reducing the ammonia nitrogen concentration in the waste liquid nine to 40 mg/L;
s10, deep zinc removal: organic sulfur heavy metal capture agent (TMT), PAC and PAM are added in sequence by using an automatic dosing device, zinc ions in the wastewater are further clarified by using flocculation precipitation to form waste liquid ten, the concentration of the zinc ions in the waste liquid ten is reduced to 2mg/L, the concentration of COD is reduced to 12800mg/L, and the total nitrogen concentration is 4700 mg/L.
(4) Biochemical treatment unit
S11, mixing wastewater: glass drilling waste water mixes in middle equalizing basin with waste liquid ten, and the pollutant concentration of waste water after mixing is respectively: zinc ion 0.18mg/L, ammonia nitrogen 3.55mg/L, COD1135mg/L, total nitrogen 416mg/L, salt content 3014mg/L, total water amount after mixing 790.06m3And d. Mixing the two kinds of waste water to form waste liquid eleven;
s12, hydrolysis acidification: enabling the waste liquid eleven to enter a hydrolysis acidification pool, and degrading macromolecular organic matters in the waste water into micromolecular organic matters to form waste liquid twelve;
s13, biochemical treatment: performing biochemical treatment on the waste liquid twelve by adopting A/O (anaerobic/anoxic/oxic) to further reduce pollutants such as COD (chemical oxygen demand), total nitrogen, ammonia nitrogen and the like in the waste water to form waste liquid thirteen;
(5) deep flocculation precipitation unit
S14, adding PAC and PAM by using an automatic dosing device, removing micro suspended substances in waste liquid thirteen through coagulating sedimentation, discharging effluent after reaching the standard, wherein the concentration of each pollutant in the discharged water is as follows: the COD concentration is 145mg/L, the ammonia nitrogen concentration is 1mg/L, the zinc ion concentration is 0.05mg/L, the total nitrogen concentration is 30mg/L, and the SS concentration is 20 mg/L.
(6) Sludge treatment unit
S15, the sludge generated before the step S11 enters a chemical sludge storage pool for temporary storage to form a first waste;
s16, dehydrating the first waste by using a sludge dehydration system to form a second waste;
s17, drying the second waste by using a drying system to form a third waste.
S18, the sludge generated after the step S11 enters a biochemical sludge storage tank for temporary storage to form a fourth waste;
s19, dehydrating the fourth waste by using a sludge dehydration system to form a fifth waste;
s20, drying the waste V by using a drying system to form a waste VI.
The process disclosed by the invention is used for treating the high-zinc high-ammonia-nitrogen high-thiourea wastewater, the problem of zinc ion emission of the wastewater can be effectively solved, the energy consumption can be reduced, byproducts can be recovered, the environment-friendly requirement is met, good economic benefits can be generated, and the sustainable development requirement is met.
The embodiments described above are some, but not all embodiments of the invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Claims (8)
1. A high-zinc high-ammonia nitrogen high-thiourea wastewater treatment process is characterized by comprising the following steps:
(1) removing zinc: sequentially heating, precipitating, first-stage zinc removal and second-stage zinc removal the high-zinc high-ammonia-nitrogen high-thiourea wastewater to obtain zinc-removed waste liquid; wherein the heating temperature is 40-50 ℃; the first-stage zinc removal process comprises the steps of adjusting the pH value of filtrate obtained after precipitation to 8-9 by using acid liquor, and then precipitating to separate solid from liquid; the second-stage zinc removal process is to add a precipitator into the filtrate obtained after the first-stage zinc removal, and remove the precipitate;
(2) removing ammonia nitrogen: adjusting the pH value of the dezincification waste liquid to be more than 12 by using an alkali liquor, then carrying out primary ammonia distillation, absorbing the obtained ammonia gas by using pure water and converting the ammonia gas into ammonia water for recycling, wherein the rest liquid is the ammonia nitrogen removal waste liquid;
(3) and (3) thiourea removal: sequentially carrying out advanced oxidation and ozone removal on the ammonia nitrogen removal waste liquid, then sequentially adding alkali, PAC and PAM, adjusting the pH value of the solution to 8-9 by using the alkali liquor, removing the catalyst in the advanced oxidation step through flocculation precipitation, then adding alkali liquor into the obtained filtrate to adjust the pH value to be more than 12, and then carrying out secondary ammonia distillation to obtain the thiourea removal waste liquid; the deep zinc removal is carried out after secondary ammonia distillation, and the process of deep zinc removal is as follows: sequentially adding a heavy metal capture agent, PAC and PAM into the waste liquid obtained after secondary ammonia distillation, and removing zinc ions in the waste liquid after flocculation and precipitation; the specific process of the advanced oxidation treatment step is as follows: introducing ozone into the ammonia nitrogen removal waste liquid, and adding hydrogen peroxide and a catalyst ferrous sulfate heptahydrate;
(4) biochemical treatment;
(5) deep flocculation and precipitation; the effluent reaches the standard and is discharged outside.
2. The treatment process according to claim 1, wherein the biochemical treatment in the step (4) comprises the following specific processes: mixing the waste liquid of the desulfurized urea with the glass drilling waste water, and carrying out biochemical treatment by adopting A/O after hydrolytic acidification.
3. The treatment process according to claim 1, wherein the specific process of deep flocculation precipitation in the step (5) is as follows: and adding PAC and PAM into the waste liquid after biochemical treatment in sequence, and removing micro suspended substances after coagulating sedimentation.
4. The treatment process of claim 1, wherein the heavy metal scavenger in step (3) is an organosulfur heavy metal scavenger.
5. The process according to claim 1, wherein the primary ammonia distillation and the secondary ammonia distillation are ammonia distillation under positive pressure.
6. The process of claim 1, wherein the acid solution is sulfuric acid, the alkaline solution is sodium hydroxide solution, and the precipitant is sodium sulfide.
7. The treatment process according to any one of claims 2 to 6, further comprising:
(6) sludge treatment: collecting sludge obtained in the steps of removing zinc, ammonia nitrogen and thiourea in a chemical sludge storage tank, and then sequentially dehydrating and drying the sludge.
8. The process of claim 7, wherein the sludge treatment of step (6) further comprises: collecting the sludge subjected to hydrolytic acidification and biochemical treatment in a biochemical sludge storage tank, and then sequentially dehydrating and drying the sludge.
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