Resourceful treatment method of desulfurization waste liquid and harmless wastewater treatment system

Abstract

The invention discloses a resourceful treatment method for desulfurization waste liquid and a harmless treatment system for waste water, which are characterized in that components of the desulfurization waste liquid are subjected to fractional precipitation, toxicant precipitates are separated out, detoxification is performed by adopting an oxidation method and a complexing method, medicaments are recycled, a denitrified electron donor is obtained, and the resourceful treatment method can also be used for treating high-nitrogen-content waste water. According to the scheme provided by the invention, the chemical reaction, the chemical separation and the biological process are combined, the common problem of safe conversion treatment of the desulfurization waste liquid and coprocessing of the coking wastewater is systematically solved, and the invention of the process mode has the technical characteristic of combining treatment of waste with waste and low-carbon pollution control.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and more specifically, to a method for the resource-based treatment of desulfurization wastewater and a system for the harmless treatment of wastewater. Background Technology

[0002] Desulfurization wastewater from the coking industry is a complex system, mainly composed of sulfides and three salts: ammonium thiocyanate, ammonium thiosulfate, and ammonium sulfate. It is a byproduct of the desulfurization process. The desulfurization wastewater produced by wet desulfurization in coking plants (commonly ammonia-based desulfurization methods such as HPF, PDS, and FRC) is a complex, highly toxic, and difficult-to-treat industrial wastewater. Its composition and concentration vary significantly depending on the desulfurization process, gas composition, operating conditions (such as temperature, pH, and catalyst type), desulfurization efficiency, and the location of wastewater extraction (such as from the bottom of the regeneration tower or from periodically discharged rich liquid from the system). The main components and typical concentration ranges of the desulfurization wastewater are as follows: Ammonium thiocyanate / sodium thiocyanate: This is the most concentrated and relatively economically valuable component in desulfurization wastewater. It is the final product of the reaction between HCN in the coal gas and ammonia (or alkali) and sulfur (from H2S oxidation) in the desulfurization liquid. Typical concentration range: 100~350 g / L, but in extreme cases it can reach above 400 g / L or as low as below 50 g / L. It is the second largest contributor to the toxicity of desulfurization wastewater. The concentration of ammonium thiocyanate / sodium thiocyanate in the desulfurization wastewater generated by Shaogang's coking plant is not high, lacking resource recovery value and making it difficult to obtain a return on investment.

[0003] Ammonium thiosulfate / sodium: This is the second most concentrated major component. It is an intermediate or byproduct of H2S oxidation. It accumulates in large quantities when oxidation is incomplete. Its toxicity is relatively low. Typical concentration range: 50~200 g / L; Ammonium sulfate / sodium: It is generated by the over-oxidation of H2S, or by the reaction of small amounts of O2, CO2, etc. in coal gas with ammonia. Its concentration is usually lower than the former two. Typical concentration range: 20~100 g / L; Elemental sulfur: Sulfur particles precipitated during desulfurization regeneration. It exists in suspension and its concentration varies greatly. It is one of the main causes of wastewater turbidity; Tar / coal dust / dust: It comes from coal gas. Although there is pretreatment, a small amount still enters the desulfurization system and accumulates in the wastewater; Ammonia nitrogen: It exists in the form of free ammonia or fixed ammonium salts. The total ammonia nitrogen concentration is usually very high. Typical concentration range: 1~10 g / L (as N); Cyanide: It mainly exists in the form of thiocyanate (already included in thiocyanate). It contains tens of mg / L to hundreds of mg / L (as CN). -The total toxicity is estimated at several g / L, but it may also contain small amounts of free cyanide or complexed cyanide (ferric cyanide complexes, etc.), which are extremely toxic and rank first. Chemical oxygen demand (COD): mainly contributed by high concentrations of reducing inorganic substances such as thiocyanate and thiosulfate, and organic substances such as phenol, resulting in extremely high COD values, typically ranging from 20,000 to 40,000 mg / L. Chloride ions: originate from makeup water or coal gas, are corrosive, and have an adverse effect on subsequent treatments (such as crystallization), with concentrations reaching several g / L to tens of g / L. Sulfide ions: may exist in the form of polysulfides, with concentrations reaching several g / L to tens of g / L. Sulfites / bisulfites: exist as intermediate products. Heavy metal ions: such as trace amounts of iron, zinc, lead, etc., originating from coal gas, equipment corrosion, or catalyst leaching. Phenolic compounds: some phenolic substances carried in the coal gas dissolve into the desulfurization liquid, with concentrations ranging from hundreds of mg / L to 1-2 mg / L. g / L; pH value: usually weakly alkaline, with a pH between 7.5 and 9.5, depending on the desulfurization process selected.

[0004] In summary, desulfurization wastewater is mainly composed of thiocyanate, thiosulfate, and sulfate (accounting for 20%–40%), with thiocyanate having the highest concentration. High salt content, high COD, high ammonia nitrogen, and high toxicity are the most prominent common characteristics of desulfurization wastewater, making direct biological treatment extremely difficult. Direct addition to coking wastewater biological treatment systems without pretreatment severely inhibits nitrification and denitrification, and also generates residual total cyanide. The composition of desulfurization wastewater is complex and highly variable, influenced by various factors; the composition and concentration of desulfurization wastewater from different coking plants, and even from the same coking plant at different times, can vary significantly. The resource utilization technology route for desulfurization wastewater has been unsuccessful, mainly due to small-scale operations, the complexity of separation technologies, low product value, and difficulty in gaining user trust. Harmless treatment technologies are inhibited by toxicity, and pure chemical oxidation is expensive. In fact, desulfurization wastewater has a severe toxic impact on coking wastewater treatment systems. Therefore, the disposal of desulfurization waste liquid has been a persistent problem for the safe production of coking and steel enterprises across the country, becoming a bottleneck for enterprise development.

[0005] The scale of desulfurization waste liquid generated by coking enterprises is generally 1 / 20 to 1 / 10 of the volume of coking wastewater, which is very unfavorable for large-scale production. Currently, almost all invested enterprises are operating at cost. The path to resource utilization is constrained by factors such as high toxicity, complex composition, low product value, and small scale. However, its environmental hazards are particularly prominent. Therefore, it is very necessary to seek feasible technological breakthroughs and comprehensively consider the enterprises' affordability to solve the problem of waste liquid treatment. Although coking wastewater is also toxic and difficult to treat industrial wastewater, its toxicity is only 1 / 100 to 1 / 1000 of that of desulfurization wastewater. It has been proven that using the OHO process to treat coking wastewater can achieve partial or complete nitrification under high organic load influent conditions in the first aerobic unit, O1. Thus, the components in the desulfurization wastewater are transformed and partially separated through a chemical detoxification mechanism, retaining its reducing electron-donating ability. The pretreated desulfurization wastewater is used as a denitrification electron donor to match the denitrification treatment of coking wastewater, reducing the amount of chemicals used in coking wastewater treatment. This links the desulfurization wastewater and coking wastewater for synergistic purification, resulting in a clean production process technology with low material and energy consumption and fewer secondary pollutant emissions. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a method for resource-based treatment of desulfurization waste liquid and a system for harmless treatment of wastewater.

[0007] The present invention solves its technical problem by adopting the following technical solution.

[0008] This invention provides a method for the resource-based treatment of desulfurization wastewater containing sulfides, cyanides, thiocyanates, phenolic compounds, and nitrogen-containing compounds. The method for resource-based treatment of the desulfurization wastewater includes: After the sulfides in the desulfurization wastewater are precipitated, ferric chloride is added to the filtered supernatant to convert the cyanides in the desulfurization wastewater into ferric cyanide complex precipitates. The filtered ferric cyanide complex precipitates are then oxidized and dissolved to obtain a solution containing ferric chloride.

[0009] This invention also provides a method for the resource-based treatment of desulfurization wastewater, wherein the desulfurization wastewater contains sulfides, cyanides, thiocyanates, phenolic compounds, and nitrogen-containing compounds, and the method for resource-based treatment of the desulfurization wastewater includes: After the sulfides in the desulfurization waste liquid are precipitated, ferric chloride is added to the filtered supernatant to convert the cyanide in the desulfurization waste liquid into ferric cyanide complex precipitate. The filtered ferric cyanide complex precipitate is then oxidized and dissolved to obtain a solution containing ferric chloride. Furthermore, the supernatant of the desulfurization waste liquid is used as an electron donor for biological denitrification of nitrogen-containing wastewater, preferably the nitrogen-containing wastewater is coking wastewater.

[0010] This invention also provides a wastewater harmless treatment system, comprising: a pre-physicochemical unit, mainly used for the removal of cyanide and sulfide from desulfurization wastewater; a water collection and equalization tank, used to balance the influent flow rate and water quality fluctuations; four units in the OHHO process, used for biological denitrification treatment of the supernatant of the desulfurization wastewater and the raw water of coking wastewater; and a post-physicochemical unit, used for the removal of suspended solids and color treatment of the biological effluent generated by the OHHO process; and the OHHO process includes an O1 unit and an H1 unit. The system comprises three units: the pre-physicochemical unit (H1 unit, H2 unit, and O2 unit). The outlet of the pre-physicochemical unit is connected to the inlet of the regulating water collection tank. The outlet of the regulating water collection tank is connected to the inlet of the O1 unit via a booster pump. The outlet of the O1 unit is connected to the inlet of the H1 unit. The outlet of the H1 unit is connected to the inlet of the H2 unit. The outlet of the H2 unit is connected to the inlet of the O2 unit. The outlet of the O2 unit is connected to the inlet of the post-physicochemical unit.

[0011] The present invention has the following beneficial effects: This invention involves the stepwise precipitation of components in desulfurization wastewater to precipitate toxic precipitates. These precipitates are then detoxified using oxidation and complexation methods, and the reagents are recycled. Electron donors for nitrogen removal are obtained, and the solution can also be used for total nitrogen removal in biological processes. The entire process demonstrates the resource-based nitrogen removal effect of desulfurization wastewater, systematically solving the common problems of harmless treatment of desulfurization wastewater and deep nitrogen removal from coking wastewater. This invention is suitable for low-consumption nitrogen removal treatment of coal chemical industry wastewater, reducing operating costs and clearly demonstrating the technical characteristics of combining waste-to-waste treatment with carbon emission reduction. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of a wastewater treatment system; Figure 2 This is a schematic diagram of a resource-based treatment method for desulfurization wastewater. Figure 3 The process flow diagram shows the four operating modes; Figure 4 The nitrogen removal efficiency of the OHHO process under four different modes is shown in (a) the total nitrogen concentration and removal rate of the influent and effluent under the four operating modes, and (b) the total nitrogen concentration and total nitrogen removal rate of each unit reactor. Figure 5The changes in the form of total nitrogen in each stage of the OHHO process under four different operating modes: concentrations of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen in the effluent (a) O1 reactor, (b) H1 reactor; (c) O2H2 reactor; Figure 6 To assess the effects of each reaction unit on COD and SCN under the four operating modes of the dual physicochemical synergistic OHHO process. - and TCN's contribution to removal; Figure 7 The community composition at the microbial phylum level for the four operating modes of the OHHO process; Figure 8 The microbial community composition at the genus level for the four operating modes of the OHHO process. Detailed Implementation

[0014] To make the objectives, 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. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0015] This invention provides a resource-based treatment method for desulfurization wastewater and a system for harmless wastewater treatment. The method involves stepwise precipitation of the components in the desulfurization wastewater to precipitate toxic precipitates. Detoxification is achieved using oxidation and complexation methods, and the reagents are recycled to obtain electron donors for nitrogen removal in biological processes. Ferrous sulfate, calcium chloride, and ferric chloride are selected as precipitants. First, ferrous sulfate is added to the desulfurization wastewater, precipitating a mixed precipitate of ferrous sulfide and ferrous sulfite. Second, calcium chloride is added, precipitating calcium sulfate, calcium sulfite, and calcium thiosulfate. Third, ferric chloride is added to the residual solution, converting cyanide into Prussian blue and Thunberg blue precipitates (Fe₄[Fe(CN)₆]₃·xH₂O, with extremely low solubility and Ksp less than 10). -35 The precipitate consists of ferrocyanide complexes; the main components remaining in the solution are: ferrocyanide complexes and ferrocyanide complexes of low concentration, i.e., dissolved complex ions (Fe(CN)6). 3- Fe(SCN)6 3- The fourth step involves using a cyclone separator to separate the three precipitates. The first precipitate is used in the H2 unit of the OHHO process to achieve autotrophic denitrification. The second precipitate is used in the H1 unit of the OHHO process to achieve synergistic denitrification through heterotrophic and autotrophic denitrification. The precipitate from the third step undergoes an ozone detoxification reaction, converting the cyanide in the Prussian blue and Thunberg blue precipitates into carbonates and nitrates. All ferrous iron is oxidized to ferric iron, dissolved in hydrochloric acid, and used as a precipitant in the third step. The precipitate also contains dissolved complex ions (Fe(CN)6). 3-Fe(SCN)6 3- The entire solution enters the O1 reactor. By controlling the dissolved oxygen concentration in different reactor units of the OHHO process, the nitrification reaction in the O1 reactor is achieved. Combined with the denitrification reaction in the H reactor, the entire process demonstrates the resource-based denitrification effect of the desulfurization wastewater, systematically solving the common problems of harmless treatment of desulfurization wastewater and deep denitrification of coking wastewater. This invention is suitable for low-consumption denitrification treatment of coal chemical industry wastewater, reducing operating costs and clearly demonstrating the technical characteristics of combining waste-to-waste treatment with carbon emission reduction.

[0016] The following is a detailed description of a resource-based treatment method for desulfurization wastewater and a wastewater harmless treatment system provided by embodiments of the present invention.

[0017] In a first aspect, the present invention provides a method for the resource-based treatment of desulfurization wastewater, wherein the desulfurization wastewater contains sulfides, cyanides, thiocyanates, phenolic compounds, and nitrogen-containing compounds, and the method for resource-based treatment of the desulfurization wastewater includes: After the sulfides in the desulfurization wastewater are precipitated, ferric chloride is added to the filtered supernatant to convert the cyanides in the desulfurization wastewater into ferric cyanide complex precipitates. The filtered ferric cyanide complex precipitates are then oxidized and dissolved to obtain a solution containing ferric chloride.

[0018] Desulfurization wastewater is highly toxic. Its toxicity is a complex system of synergistic and superimposed effects, rather than a simple sum of individual substances. Currently, the main components of desulfurization wastewater generated by the coking industry are: sulfides (elemental sulfur, thiosulfate, sulfite, sulfate), thiocyanates, cyanides (containing nitrile compounds), phenolic compounds, and nitrogen-containing compounds (inorganic nitrogen and organic nitrogen).

[0019] To achieve the resource-based treatment of desulfurization wastewater, this invention provides a method for the resource-based treatment of desulfurization wastewater, see [link to relevant documentation]. Figure 2 The following treatment approach was adopted: The components of the desulfurization wastewater were precipitated in stages to convert most of the sulfides into precipitates. Then, ferric chloride was added to combine with cyanide ions, ferric ions, and ferrous ions in the cyanide, precipitating toxic precipitates. Detoxification was performed using oxidation and complexation methods, and the reagents were recycled to obtain electron donors for nitrogen removal in biological processes. The precipitants used for staged precipitation were ferrous sulfate, calcium chloride, and ferric chloride. The steps included: First, ferrous sulfate was added to the desulfurization wastewater to precipitate a mixed precipitate of ferrous sulfide and ferrous sulfite; second, calcium chloride was added to the supernatant after precipitate removal to precipitate calcium sulfate, calcium sulfite, and calcium thiosulfate; third, ferric chloride was added to the supernatant after precipitate removal to convert cyanide into Prussian blue and Thunberg blue precipitates (Fe4[Fe(CN)6]3·xH2O, with extremely low solubility, Ksp < 10). -35The main components remaining in the solution are: iron complexes of thiocyanate and iron complexes of low-concentration cyanide, i.e., dissolved complex ions (Fe(CN)6). 3- Fe(SCN)6 3- The above treatment method can detoxify desulfurization wastewater containing highly toxic cyanide (including nitrile compounds), sulfides, and thiocyanates. The cyanide is converted into a precipitate, which is then detoxified and dissolved by ozone to obtain a solution containing ferric chloride. Specifically: The desulfurization wastewater was collected in a corrosion-resistant collection tank, aerated and mixed to ensure uniformity, and accumulated to a certain volume. Sampling and analysis were then performed on the COD, total nitrogen, total cyanide, thiocyanate, and pH value in the desulfurization wastewater. According to calibration, the average electron donor equivalent in the desulfurization wastewater was approximately 1.99 × 10⁻⁶. 4 mol -e / t. The raw desulfurization wastewater is labeled as wastewater (1-1). The raw wastewater (1-1) is treated as follows: a 25% ferrous sulfate solution is added according to the volume ratio, and the mixture is pneumatically stirred for 10 minutes. The precipitate (2-1) and supernatant (1-2) are separated by cyclone separation. The volume ratio of the precipitate to the supernatant is approximately 10% and 90%, respectively. The sludge (2-1) contains ferrous sulfide (Ksp = 6.0 × 10⁻⁶). -18 ), ferrous sulfite (Ksp=1.0×10), -15 When the concentration reaches 30%~40% by weight, the electron donor equivalent is approximately 2.98×10⁻⁶. 3 mol -e / t; Add 15% calcium chloride solution to the supernatant (1-2), stir pneumatically for 10 minutes, add 20 mg / L PAM solution, and separate the sludge (2-2) by cyclone separation. The sludge (2-2) contains calcium sulfide (Ksp=(0.1~1.0)×10 -6 ), calcium sulfite (Ksp=6.8×10), -8 ) and calcium sulfate (Ksp=4.9×10 -5 The supernatant (1-3) was left behind. The volume ratio of precipitate to supernatant was approximately 10% and 90%, respectively. The electron donor equivalent in the precipitate was approximately 1.00 × 10⁻⁶. 3 mol -e / t; The supernatant (1-3) contains a mixture of ferrous thiosulfate / ferric (no Ksp, soluble), ferrous sulfate / ferric (no Ksp, soluble), calcium thiosulfate (no Ksp, soluble), as well as thiocyanate and cyanide complexes. This part can also be used as an electron donor solution; Ferric chloride is added to the supernatant (1-3) after separating the precipitate (2-2) to form precipitate (2-3), and the solution (1-4) is separated; The precipitate (2-3) contains a mixture of Prussian blue and Tönnies blue precipitates. More than 90% of the cyanide is removed by ozone oxidation, and then the precipitate is dissolved in 3% hydrochloric acid solution to obtain solution (1-4); The solution (1- 4) The supernatant (1-4) is reused in the previous step to replace the addition of ferric chloride. Any deficiency in solution (1-4) can be replenished from external sources. The supernatant (1-4) is pumped to the O1 unit of the OHHO biological process for coking wastewater treatment to achieve partial nitrification. Simultaneously, the aerobic sludge multiplication mechanism overcomes the toxicity of the wastewater. The H1 unit receives over 20%–30% of the raw coking wastewater, sediment (2-2), and nitrified liquid from the O1 unit. The H2 unit receives sediment (2-1), treated water from the H1 unit, and reflux nitrified liquid from the O2 unit. The biological effluent is discharged from the O2 unit of the OHHO process and enters the next set of post-physicochemical treatment systems. Application prerequisites: For successful biological denitrification using desulfurization wastewater, thorough wastewater characteristic analysis and necessary pretreatment (such as pH adjustment, suspended solids / heavy metal removal, and dilution with recycled water) are crucial. For wastewater with extremely complex compositions or high levels of toxic substances (such as typical coking desulfurization wastewater), direct biological treatment can be very difficult, requiring more complex combined processes or pretreatment. Therefore, before considering the use of desulfurization wastewater as an electron donor, it is essential to conduct a comprehensive water quality analysis and assess its applicability, required pretreatment measures, and potential impact on the biological denitrification system based on the analysis results.

[0020] The resource-based treatment method for desulfurization wastewater provided by this invention involves stepwise precipitation of sulfides in the wastewater, followed by conversion of the cyanides contained therein into ferrocyanide complex precipitates. These ferrocyanide complex precipitates are primarily Prussian blue and Tennant blue precipitates, with molecular structures of Fe4[Fe2+] and Fe2+, respectively. (CN)6]3、Fe3[Fe [CN]6]2, their solubility product constants are equal. Without the addition of ferric ions, no precipitate will form. Using this principle, cyanide can be separated from other sulfides. Since the solubility product constants of Prussian blue and Tönnies blue are very small, they can be completely separated from the solution by the principle of cyclone separation. Based on the solubility product constant, the two precipitates are difficult to oxidize with conventional oxidants such as oxygen and hydrogen peroxide. Therefore, ozone oxidation technology is selected to break down more than 90% of the cyanide and convert it into nitrate and carbonate. The ferrous ions in the central ligand are almost completely converted into ferric ions and precipitated in the form of ferric hydroxide. After being dissolved in 3% hydrochloric acid solution, it can be reused in the precipitation step (3) to convert all the thiocyanate and the remaining small amount of low-concentration cyanide into complexes, reducing the total toxicity of the waste liquid. The toxicity test by zebrafish showed that the toxicity decreased to less than 1 / 550 of the original liquid, which is comparable to the toxicity of the coking wastewater. It can enter the biochemical system at a low load flow rate. This step has become a breakthrough in the detoxification principle technology. No separation of ammonia nitrogen in the supernatant is required; the solution directly enters the O1 unit of the special biochemical process OHHO. Specifically, the supernatant (1-4) of the desulfurization wastewater, after three-step sedimentation and sludge separation pretreatment, is introduced into the coking wastewater treatment system at a certain ratio, controlled between 15:1 and 10:1. This addresses the common issues of both toxic load and organic load control. The main costs of this treatment process come from the precipitant and the oxidant targeting cyanide. The pretreatment cost per ton of desulfurization wastewater is less than 9 yuan, which is 1 / 10 to 1 / 5 of the operating cost of current high-temperature hydrolysis and salt separation processes. This is because the desulfurization wastewater, after undergoing toxicity conversion, serves as a reagent for the biological treatment of coking wastewater.

[0021] The elemental composition of the supernatant depends on the type and dosage of the precipitant, as well as pH control. Based on the precipitation order of the precipitates (sulfide, thiosulfate, sulfite, sulfate, and cyanide ions with ferrous, calcium, and iron ions respectively), the order of precipitation is: ferrous sulfide (2-1), a calcium-iron mixed precipitate of thiosulfate, sulfite, and sulfate (2-2), and a complex precipitate of cyanide (Prussian blue and Thunberg's blue) (2-3). Unprecipitated ions include thiocyanate (mainly in the form of iron complexes), chloride, bicarbonate, and ammonium ions. The toxicity of the supernatant has been reduced to below the level of coking wastewater (the overall toxicity is less than 1 / 550 times that of the original solution), and it can be used in a biological treatment process for carbon removal and ammonia oxidation. The sludge concentration (MLSS) in the bioreactor is controlled at approximately 8000 mg / L. The sludge multiplication mechanism overcomes the overall toxicity after mixing wastewater and waste liquid, achieving partial nitrification of nitrogenous compounds under high-load operation. Because the reactor adopts a fluidized bed structure, combined with in-situ selective functional separation of sludge, the value of the desulfurization wastewater as an electron donor for nitrogen removal lies in the certain proportion of reducing compounds (SO3) it contains.2- S2O3 2- S 2- SCN - CN - In the descending zone of the reactor, O2 and NO2 in the electron acceptor - NO3 - Simultaneous biological reduction reaction occurs, exhibiting an aerobic denitrification mechanism in the SND process, enabling the total nitrogen removal rate of the O1 unit reactor to reach between 30% and 35%.

[0022] In practical applications, the specific process needs to be dynamically adjusted based on the following factors: 1) the concentration and form of sulfur compounds in the desulfurization wastewater (sulfites, sulfides, thiocyanates, etc.); 2) the concentration and source of nitrate nitrogen in the wastewater requiring denitrification, which needs to be coordinated with the process; 3) suitable microbial communities (such as Thiobacillus, AOB / NOB); 4) optimal process parameters (pH, DO, temperature, HRT, SRT, OLR, etc.); 5) possible byproducts (such as pH changes caused by sulfate formation, which need to be separated in a timely manner). This method is particularly suitable for industrial scenarios that simultaneously generate desulfurization wastewater and high-nitrogen wastewater, such as coal-fired power plants, steel plants, and coking plants. Pre-treating the desulfurization wastewater and using it as an electron donor for biological denitrification (mainly denitrification) has become a promising "waste-to-waste" resource utilization technology. Its core is to use the reducing compounds in the desulfurization wastewater to replace the organic carbon sources (such as methanol, sodium acetate, glucose, etc.) required for traditional denitrification, driving microorganisms to reduce nitrate nitrogen to nitrogen gas. Therefore, the important contribution of this invention lies in stepwise precipitation, separating electron donors of different purities, identifying toxic components and controlling detoxification steps (precipitation-complexation-oxidation), and utilizing electron donors of different forms / phases in different unit reactions in the combined process.

[0023] Secondly, the present invention also provides a method for resource-based treatment of desulfurization wastewater, wherein the desulfurization wastewater contains sulfides, cyanides, thiocyanates, phenolic compounds, and nitrogen-containing compounds, and the method for resource-based treatment of the desulfurization wastewater includes: After the sulfides in the desulfurization waste liquid are precipitated, ferric chloride is added to the filtered supernatant to convert the cyanide in the desulfurization waste liquid into ferric cyanide complex precipitate. The filtered ferric cyanide complex precipitate is then oxidized and dissolved to obtain a solution containing ferric chloride. Furthermore, the supernatant of the desulfurization waste liquid is used as an electron donor for biological denitrification of nitrogen-containing wastewater, preferably the nitrogen-containing wastewater is coking wastewater.

[0024] The above-mentioned solution provided by the present invention, after precipitation and detoxification treatment of desulfurization wastewater, contains a large amount of reduced inorganic sulfur compounds (such as sulfur dioxide). 2- S2O32- S 0 SO3 2- Therefore, this invention further uses the supernatant of the desulfurized wastewater obtained after detoxification treatment as a denitrification agent for wastewater such as coking wastewater, especially for denitrification treatment in the biological denitrification process of coking wastewater, thereby significantly reducing the carbon source addition cost for wastewater denitrification. The denitrification process in biological denitrification refers to the process by which microorganisms, under anaerobic conditions, utilize organic or inorganic substances as electron donors to convert nitrates (NO3-) into nitrogen oxides. - ) or nitrite (NO2) - The process of gradually reducing nitrogen (N2) to nitrogen gas requires the consumption of electron donors.

[0025] The total nitrogen (TN) in the raw coking wastewater was as high as 290±25 mg / L (NH4). + (N content is less than 40%), where nitrogen is mainly in the form of reduced Org-N and NH4+. + -N、SCN - CN - It exists in a form that contains almost no NO2. - -N and NO3 - -N, therefore, reduced nitrogen must undergo aerobic nitrification before denitrification can remove it. Traditional AAO processes place the aerobic tank downstream, requiring successful nitrification and a high reflux ratio for effective nitrogen removal; however, reflux limits the complete removal of high-concentration TN. For coking wastewater, this invention also designs an OHHO biological treatment process, in which the organic load of the biological influent (supernatant from desulfurization wastewater and raw coking wastewater) is controlled at 1.6~2.0 kgCOD / m³. 3d. The hydraulic retention times of units O1, H1, H2, and O2 are controlled at 36, 30, 30, and 24 hours, respectively, with corresponding MLSS controlled at approximately 8000, 6000, 6000, and 3600 mg / L. All bioreactor units are designed with in-situ sludge separation capabilities, eliminating the need for sludge recirculation. Only the nitrification liquor recirculation ratio of the O2 unit is controlled at 1:1, and the water temperature is maintained within the range of 28–38℃. The dissolved oxygen (DO) concentrations (DO) of units O1, H1, H2, and O2 are controlled at 1.5–2.5, 0–0.2, 0–0.5, and 3.0–4.0, respectively. Within the mg / L range, phosphate nutrients are supplemented into the O1 influent, controlling the C:N:P ratio to approximately 200:10:1. The O1 unit is supplemented with NaHCO3 to maintain alkalinity above pH 8.0. Excess sludge from O1 and O2 is separated by a hydrocyclone separator and added to the H1 unit at a flow rate of approximately 2%–3% of the treated water volume, ensuring continuous and stable flow of wastewater and gas supply, thus serving as a process platform for disposing of desulfurization wastewater. The treatment capacity is controlled to be more than 10 times the flow rate of the desulfurization wastewater. In terms of process design, parameters need optimization. pH, temperature, C / N ratio (actually S / N ratio), and the selection of microbial communities all need to be adjusted in real time according to the specific wastewater composition. The abundance ratio of mixed microorganisms in each reactor is controlled by adjusting the sludge age, while simultaneously optimizing the treatment of carbon, nitrogen, and sulfur. The selected reactor type possesses functions such as enhanced mixing and mass transfer, in-situ sludge separation, matching of organic load, flow load, and weir load, and cooperation between underwater plug flow and circulating sequential flow, eliminating problems of pipe blockage or sludge loss.

[0026] The sludge (2-1) contains ferrous sulfide (Ksp=6.0×10⁻⁶). -18 ), ferrous sulfite (Ksp=1.0×10), -15 Add 15% calcium chloride solution to the supernatant (1-2), stir pneumatically for 10 minutes, add 20 mg / L PAM solution, and separate the sludge (2-2) by cyclone separation. The sludge (2-2) contains calcium sulfide (Ksp=(0.1~1.0)×10). -6 ), calcium sulfite (Ksp=6.8×10), -8 ) and calcium sulfate (Ksp=4.9×10 -5The supernatant (1-3) is retained, containing a mixture of ferrous thiosulfate / ferric sulfate (Ksp-free, soluble), ferrous sulfate / ferric sulfate (Ksp-free, soluble), and calcium thiosulfate (Ksp-free, soluble), as well as thiocyanate and cyanide complexes. Ferric chloride is added to the supernatant (1-3) after the precipitate (2-2) is separated, forming precipitate (2-3). Solution (1-4) is then separated. Precipitate (2-3) contains a mixture of Prussian blue and Tönnies blue precipitates. More than 90% of the cyanide is removed by ozone oxidation, and then dissolved in 3% hydrochloric acid solution. The precipitate is used to obtain solution (1-4); solution (1-4) is reused in the previous step to replace the addition of ferric chloride, and any insufficient solution (1-4) can be supplemented from outside; the supernatant (1-4) is pumped to the O1 unit of the OHHO biological process for coking wastewater treatment to achieve partial nitrification; more than 20%~30% of the raw coking wastewater and sludge (2-2) and the nitrified liquid from the O unit are received in the H1 unit, and the sludge (2-1) and the water from H1 are received in the H2 unit, while the reflux nitrified liquid from O2 is also received. The effluent is discharged from the O2 unit of the OHHO process. It should be noted here that, since the supernatant of the desulfurization wastewater still contains some ferricyanide and thiocyanate, the high-load sludge concentration proliferation principle of the O1 unit is used to degrade the thiocyanate and convert it into ammonia nitrogen, nitrite nitrogen, carbonate and sulfate, providing electron acceptors for denitrification. The relatively pure precipitate (2-1) is used in the H2 unit, and the multi-component precipitate (2-2) is used in the H1 unit, thus completely denitrifying in sequence.

[0027] The dosing pattern and optimization of reagents in the denitrification process. The dosing strategy in the OHHO biological treatment process for coking wastewater generated from the desulfurization wastewater production line includes separate dosing of solid and liquid materials. Ferrous sulfide and ferrous sulfite (2-1) separated from the desulfurization wastewater are added to the H2 unit of the OHHO process, calcium and iron precipitates (2-2) are added to the H1 unit, and the supernatant (1-4) of the desulfurization wastewater is added to the O1 unit. A sludge cyclone separator is installed to discharge excess sludge from each reactor unit online, controlling the sludge concentration in the reactors.

[0028] The reaction equation using sulfides as electron donors can be expressed as follows: 5S 2- + 8NO3 - + 8H + → 5SO4 2- + 4N2↑+ 4H2O S2O3 2- + 2NO3 - + 2H + → 2SO4 - + N2↑+ H2O 5SO3 2- + 2NO3 - + 2H + → 5SO4 2- + N2↑+ H2O The reaction equation using cyanide / thiocyanate as electron donors can be expressed as: 3CN - + 2NO2 - + 5H + + 5H₂O → N₂↑ + 3HCO₃ - + 3NH4 + 5CN - + 2NO3 - + 7H + + 9H2O → N2↑+ 5HCO3 - + 5NH4 + 3CN - + 5NO2 - + 5H + → 4N2↑ + 3HCO3 - + H2O 3CN - +1.99NO2 - +1.8H + →1.35N2↑+0.26NO3 - +0.93HCO3 - +0.066CH2O 0.5 N 0.15 +0.36H2O The reaction equation using ferrous iron as an electron donor can be expressed as: 10Fe 2+ + 2NO3 - + 12H + → 10Fe 3+ + N2↑+ 6H2O The advantages are manifested in the following ways: "Waste-to-waste" treatment, reducing costs: Using desulfurization wastewater as a low-cost electron donor can significantly reduce the cost of external carbon sources (such as methanol, sodium acetate, etc.) required in traditional denitrification processes, while simultaneously treating the desulfurization wastewater, achieving waste resource utilization. High treatment efficiency: Sulfur autotrophic denitrification rates are generally faster than heterotrophic denitrification, allowing for more compact reactor designs. Low sludge production: Autotrophic bacteria utilize CO2 as a carbon source for growth, and their cell yield is much lower than that of heterotrophic bacteria, resulting in less residual sludge and reducing sludge treatment and disposal costs. Avoiding secondary pollution: Excessive addition of traditional organic carbon sources can lead to excessive COD levels in the effluent.

[0029] Sulfur autotrophic denitrification: Specific types of chemoautotrophic bacteria (such as Thiobacillus spp.) Thiobacillus It can utilize reduced inorganic sulfur compounds (such as S) 2- S2O3 2- S 0 SO3 2- ( ) as an electron donor, converting CO2 / HCO3 - As an inorganic carbon source, it also contains NO3 - or NO2 - It is reduced to N2. Its basic reaction formula can be simplified to: Sulfur compounds + NO3 - + CO2 + H2O + Microorganisms → N2 + SO4 2- + Biomass The above process requires avoiding several issues, including: ensuring the amount of electron donors from the desulfurization wastewater is insufficient in both O1 and H1, and then supplementing with nitrogen-free electron donors such as ferrous sulfide and sodium acetate to guarantee the complete denitrification reaction. The sulfur autotrophic denitrification process will generate a certain alkalinity (from the H in the reaction equation). + As can be seen from the consumption (which helps maintain the pH stability of the system), it helps maintain the pH stability of the system. However, at the same time, the form of sulfides is greatly affected by pH (H2S / HS). - / S 2- The pH needs to be controlled within the optimal range (usually slightly alkaline) to ensure microbial activity and prevent H2S gas escape. Specific sulfur-autotrophic denitrifying bacteria (such as...) need to be cultured and enriched. Thiobacillus denitrificans These microbial communities require time to initiate and acclimatize, and are more sensitive to operating conditions than traditional heterotrophic denitrification. The final product of the reaction is sulfate (SO4). 2- Excess sulfate ions are removed from the process flow through calcium salt precipitation. The ratio of the source materials of the desulfurization wastewater to the nitrogen-containing wastewater is controlled as much as possible; the theoretical sulfur-to-nitrogen ratio (S / N, in electron equivalents) is approximately 5:2 (in S...). 2- / NO3 -The design is reasonable, but requires experimental optimization in actual operation. The composition of desulfurization wastewater is complex: it may contain heavy metals, fluorides, chloride ions, suspended solids, unreacted limestone, and other impurities. These impurities may inhibit or toxicize denitrifying bacteria, or deposit in the reactor causing blockage. Wastewater typically requires pretreatment (e.g., sedimentation, filtration) to remove solid impurities and some heavy metals. Reaction rate: Compared to heterotrophic denitrification, the specific reaction rate of sulfur autotrophic denitrification is generally slower, potentially requiring a larger reactor volume or a longer hydraulic retention time. Therefore, the volume ratio of the H unit is designed as H1:H2=2:1. Improper reaction control may lead to nitrite accumulation or sulfur precipitation, affecting denitrification efficiency and system operation; a reasonable ORP value range needs to be controlled. It is important to avoid oxygen competition, which can cause reducing sulfur compounds to be easily oxidized and compete with denitrifying bacteria for electron donors.

[0030] Secondly, the present invention also provides a wastewater harmless treatment system, comprising: a pre-physicochemical unit, mainly used for the removal of cyanide and sulfide from desulfurization wastewater; a water collection and equalization tank, used to balance the influent flow rate and water quality fluctuations; four units in the OHHO process, used for biological denitrification treatment of the supernatant of the desulfurization wastewater and the raw water of coking wastewater; and a post-physicochemical unit, used for the removal of suspended solids and color treatment of the biological effluent generated by the OHHO process; and the OHHO process includes an O1 unit, an H... The system comprises three units: Unit 1, Unit H2, and Unit O2. The outlet of the pre-physicochemical unit is connected to the inlet of the regulating water collection tank. The outlet of the regulating water collection tank is connected to the inlet of Unit O1 via a booster pump. The outlet of Unit O1 is connected to the inlet of Unit H1. The outlet of Unit H1 is connected to the inlet of Unit H2. The outlet of Unit H2 is connected to the inlet of Unit O2. The outlet of Unit O2 is connected to the inlet of the post-physicochemical unit.

[0031] Furthermore, the wastewater harmless treatment system also includes: a VOCs purification tower and an activated carbon feeding tower. The outlet of the activated carbon feeding tower is connected to the inlet of the post-physicochemical unit. The outlet of the post-physicochemical unit containing activated carbon sludge is connected to the inlet of the VOCs purification tower. The outlets of the regulating water collection tank and the pre-physicochemical unit containing volatile organic compounds are both connected to the inlet of the VOCs purification tower containing volatile organic compounds. The outlet of the VOCs purification tower containing activated carbon sludge is connected to the inlet of the biological process O1 unit.

[0032] The present invention will be further described below with reference to embodiments.

[0033] The raw coking wastewater used is mainly ammonia stripping wastewater, with a flow rate of 45 m³ / h. 3 / h, entering the water collection and equalization tank to balance other incoming water (gas water seal water, desulfurization wastewater, fire-fighting water, road cleaning water, etc.) 10 m 3 After being pumped into the biological treatment system at a rate of / h, the concentration of the main nitrogenous components in the coking wastewater is shown in Table 1. The amount of desulfurization wastewater generated is approximately 3 m³. 3 / h, the main pollutant components and concentrations are shown in Table 2.

[0034] Table 1. Concentration of nitrogenous components in coking wastewater (unit: mg / L)

[0035] Note: "L" is below the detection limit.

[0036] Table 2 Concentrations of pollutants in desulfurization wastewater (unit: mg / L)

[0037] The original coking wastewater treatment project (located at Baowu Shaogang Iron & Steel Co., Ltd. in Shaoguan City, Guangdong Province, China) used an AAO + post-physicochemical treatment process. After modification, the new process flow is pre-physicochemical treatment + biological treatment system (OHHO) + post-physicochemical treatment, and its process flow diagram is as follows. Figure 2 As shown. The inoculated sludge in each reactor of the OHHO process is high-performance activated sludge from the secondary sedimentation tank of the AOHO process in the second phase of the plant, with MLSS of 4000~6000 mg / L. The wastewater treatment capacity of the OHHO process is 1320 m³. 3 / d, total HRT is 160 h. Ferrous salt and polyacrylamide (PAM) are added to the pre-physicochemical tank to precipitate and complex the high concentration of sulfur in the raw water. 2– CN - and SCN - To reduce its biotoxicity, the collection and equalization tank balances the water quality and quantity from the pre-physicochemical effluent and other wastewater before pumping it to the biological treatment system. The pretreatment of desulfurization wastewater is incorporated into the pre-physicochemical system, as illustrated in the patent application. The O1 tank is an internally circulating aerobic biological fluidized bed, a first-of-its-kind design by our research group. It can control the DO concentration by adjusting the aeration intensity to achieve ammonification, nitrification, and nitrification stages, while simultaneously removing most organic matter. Phosphate and alkaline solutions are added to ensure the nutrients needed for microbial growth and to replenish the alkalinity consumed by nitrification. H1 and H2 are anaerobic hydrolysis and denitrification tanks, which can further anaerobicly degrade recalcitrant organic matter. Carbon sources can also be added for autotrophic denitrification (HetDen) reactions. O2 further thoroughly removes carbon and nitrifies. The post-physicochemical tanks add polyferric sulfate, activated carbon, liquid alkali, and PAM to further reduce suspended solids and color in the biological effluent. Activated carbon sequentially passes through the post-physicochemical unit, the VOCs tower, and the pre-physicochemical unit, achieving stepwise adsorption saturation of pollutants from low to high concentrations.

[0038] The following designs four pilot operation modes for the CT2PC-OHHO (Combined technology of pre- and post-physicochemical treatment with OHHO) process, and evaluates their effectiveness: A 180-day commissioning period was conducted on the OHHO process during its initial construction phase to investigate the feasibility and operational effectiveness of various denitrification modes. Based on the characteristics of multiple denitrification pathway combinations in the H1 and H2 dual denitrification regions, the migration, transformation, and fate of nitrogen were explored under four operating modes throughout the entire process. Table 3 provides detailed information on the four operating modes of the OHHO process. Figure 3 The process flow diagrams for four operating modes are presented. The addition of glucose and pre-physicochemical sludge / desulfurization wastewater sludge as electron donors were investigated in heterotrophic denitrification denitrification in H1 and H2. In each mode, the carbon source dosage was gradually increased over a short period until a stable C / N ratio was achieved. In Mode II, O2 nitrification liquid was recirculated to H2, while in Modes III and IV, the excess water from the equalization tank and pre-coagulated sludge was added to H1. Different excess water volumes reduced the external carbon source dosage to varying degrees, but also introduced reduced nitrogen from the raw water. When the excess exceeded 20% (11 m³), ​​the reduction was significant. 3 When raw water is converted to H1, the amount of external carbon source added can be reduced by 37.4%.

[0039] Table 3 Operating parameters of the OHHO process

[0040] Note: Glucose is added as an external carbon source, while the raw water in the equalization tank and the pre-physicochemical sediment are used as internal carbon sources. 1) Sampling point setup and water quality indicator testing methods Sampling points for this experiment were set up at the following locations: the inlet pipe of the pre-physicochemical treatment tank (representing raw water), the pre-physicochemical treatment tank outlet, the equalization tank, the outlet of the O1 tank, the outlet of the H1 tank, the outlet of the H2 tank, the outlet of the secondary sedimentation tank (replacing the outlet of the O2 tank), and the outlet of the post-physicochemical treatment tank (replacing the external drainage). Sampling was conducted at 9:00 AM daily, with samples taken every other day. Immediately after sampling, various physicochemical and water quality indicators were tested. All water samples were filtered through a 0.45 μm filter membrane before analysis. Physicochemical indicators T, pH, DO, and conductivity were measured using an AZ86031 portable testing instrument (Hengxin Technology Co., Ltd.), and ORP was measured using a 501ORP composite electrode (Shanghai Instrument & Electronics Scientific Instruments Co., Ltd.). COD was measured by potassium dichromate titration; TN was measured by ultraviolet spectrophotometry (alkaline potassium persulfate digestion); nitrate nitrogen (NO3) was measured... - -N) was measured using ultraviolet spectrophotometry (activated carbon decolorization to shield against background color interference), NH4+ -N and nitrite nitrogen (NO2) - -N) was determined spectrophotometrically (ammonia nitrogen underwent pretreatment via distillation and reflux); organic nitrogen was obtained by subtracting ammonia nitrogen from Kjeldahl nitrogen; CN - Total cyanide (TCN) was determined using the isonicotinic acid-pyrazolone spectrophotometric method; all the above detection methods were determined according to the standard methods of the State Environmental Protection Administration. - After color development with ferric nitrate (III), the samples were detected using a UV-Vis spectrophotometer, and all samples were analyzed three times.

[0041] 2) Methods for analyzing microbial diversity Sludge samples were collected from each tank during OHHO process modes I-IV, freeze-dried, and stored at -80°C. The freeze-dried samples were then sent to Majorbio (Shanghai, China) for Illumina MiSeq sequencing. Microbial community DNA was extracted according to the EZNA® soil DNAkit (Omega Bio-tek, Norcross, GA, US) instructions. The extracted genomic DNA was then detected by 1% agarose gel electrophoresis, and DNA concentration and purity were determined using NanoDrop 2000. The V4-V5 hypervariable region of the bacterial 16S rRNA gene was amplified using a thermally cycled PCR system (GeneAmp9700, ABI, USA) with primers 515F (5'-GTGCCAGCMGCCGCGG-3') and 806R (5'-GGACTACHVGGGTWTCTAAT-3'). To ensure the accuracy and reliability of subsequent data analysis, amplification was performed using the lowest possible cycle number and ensuring consistent cycle numbers for each sample. All samples were processed according to standard experimental conditions, with three replicates per sample. PCR products from the same sample were pooled and detected by 2% agarose gel electrophoresis. PCR products were recovered by gel excision using the AxyPrep DNA Gel Recovery Kit (Axygen Biosciences, UnionCity, CA, USA), eluted with Tris_HCl, and detected by 2% agarose gel electrophoresis. Based on the preliminary quantification results from electrophoresis, PCR products were quantified using the QuantiFluor™–ST blue fluorescence quantitative system (Promega, USA), and then pooled according to the sequencing volume requirements for each sample. Library construction was performed using the NEXTFLEX Rapid DNA-Seq Kit. Sequencing was performed using the Illumina Miseq PE300 platform.

[0042] This study investigated the migration and transformation pathways of nitrogen in the OHHO process during continuous operation for 180 days, revealing the TN removal rate and its speciation in different process units under four different operating modes. Figure 4 (a) It can be seen that when the influent TN concentration is 290±25.0 mg / L, the effluent TN concentrations under the four operating modes (Ⅰ, Ⅱ, Ⅲ and Ⅳ) are 180±10.0 mg / L, 45±7.5 mg / L, 30±4.5 mg / L and 16.5±1.5 mg / L, respectively, with removal rates of 37.9%±3.5%, 84.5%±2.5%, 89.7%±1.5% and 94.5%±0.5%, respectively. Compared with mode Ⅱ adding carbon source to H2 and mode Ⅲ adding carbon source to H1, mode Ⅳ (exceeding 20% ​​of the raw water to H1, reflux ratio 1, adding carbon source to H1 and H2) has the highest TN removal rate, and the effluent TN concentration drops below 20 mg / L.

[0043] Depend on Figure 4 (b) It can be seen that in the four operating modes, the total nitrogen (TN) of the raw water decreased by 20.7±2.0% and 10.3±2.5% after passing through the equalization tank and O1 tank, respectively. This is because of the dilution effect of other wastewater in the equalization tank and the growth and proliferation of microbial cells in the O1 aerobic tank on NH4+. + -N assimilation and absorption. In Mode I (no overshoot, no external carbon source added, and no reflux) and Mode II (no overshoot, external carbon source added to H2, and reflux ratio 3), adjusting DO to 1.5~2.0 mg / L can keep the O1 tank in the nitrification stage, resulting in TN in the effluent of both the O1 and H1 reactors being NH4. + -N (3.5% ± 0.5%), NO2 - -N (83.0% ± 2.0%) and NO3 - -N (7.0% ± 2.0%). In the absence of electron donors, the main function of tanks H1 and H2 is to further anaerobic hydrolyze recalcitrant organic matter into low-molecular-weight organic matter. After further thorough nitrification by O2 in the aerobic tank, the effluent total nitrogen (TN) is mainly composed of NO3-. - It exists in the form of -N. Compared with Mode I, Mode II achieves a TN removal rate of 65.0%±2.5% in the H2 tank by recirculating the O2 nitrification liquid to H2 and adding glucose to H2 as an external carbon source, and the TN concentration in the effluent is reduced to 50.0±5.0 mg / L. However, relying on the recirculation of nitrification liquid makes it difficult to achieve the discharge standard of high-concentration TN wastewater below 20 mg / L.

[0044] To avoid the energy waste caused by the large amount of carbon source (glucose) added in Mode II and the denitrification limitation caused by nitrification liquor recirculation, Mode III (exceeding 20% ​​raw water, adding external carbon source to H1 and recirculation ratio 1) can achieve complete nitrification in the O1 tank by adjusting DO to 2.5~3.5 mg / L (NO3 in effluent TN).- -N content is 95%±2%), to prevent the production of NH4 from incomplete nitrification. + -N is difficult to remove in subsequent processes. In Mode III, the external carbon source is gradually transferred from reactor H2 to reactor H1, where denitrification completely removes TN. Simultaneously, more than 20% of the raw water is fed to reactor H1, utilizing dissolved organic matter and reducing inorganic substances (such as SCN) in the raw water. - Using TCN as an internal carbon source for denitrification, the external carbon source addition was reduced by 37.4%. However, an increase in TN in the external wastewater was observed in the early stages of Model III operation. Figure 4 This is because the total nitrogen (TN) in reactor H1 of the process section increases, at which point the NH4+ effluent from H1... + -N increased to 62.5 mg / L ( Figure 5 The likely reaction is that H1 undergoes dissimilatory reduction of nitrate to ammonia (DNRA). Studies have shown that when the C / N ratio increases and the environment is anaerobic and sulfur-rich, DNRA competes with denitrification for the electron acceptor nitrate, directly reducing NO3-. - -N is reduced to NH4 + -N, which leads to the failure of denitrification. Nitrospira These bacteria play a crucial role in the DNRA bacterial community. In addition, over 20% of the raw water contains nitrogenous compounds (Org-N, CN). - and SCN - It is hydrolyzed into NH4 + -N, this part of NH4 + -N is difficult to remove in H1 and H2 reactors, requiring solutions that exceed water volume and introduce NH4. + The optimal balance point for -N. Addressing various issues encountered during Mode III operation, in Mode IV operation, exceeding 20% ​​of the raw water to H1, and adding an external carbon source at a 1:1 ratio (H1:H2 = 1:1) allows for combined regulation of internal and external carbon sources, achieving 40.0% ± 1.5% TN removal in H1. Figure 5 and Figure 6 It can be seen that the main component of TN in the effluent of H1 is NO3. - -N was 55±5 mg / L and NH4+ was 17.5±2.5 mg / L, exceeding the levels produced by the hydrolysis of nitrogenous compounds in water. + -N, further achieving TN removal of 22% ± 1.5% in H2. After complete nitrification of O2, the TN in the effluent is mainly in the form of NO3. - -N exists in the form of ( Figure 5 (c)).

[0045] Compared to operating modes I, II, and III, mode IV, through the regulation of internal and external carbon sources, removes most of the nitrogen in H1 and the remaining TN in H2, achieving stable TN removal with low energy consumption. This avoids the limitation of TN removal by the reflux ratio and exceeds the NH4+ caused by internal electron donors.+ Problems such as DNRA caused by nitrogen release and excessive carbon source addition were identified. In summary, the dual denitrification operation mode of the OHHO process achieved stable TN removal, which has not been reported in previous literature. The new process theory may serve as an effective demonstration for solving the current problem of TN non-compliance in wastewater treatment plants.

[0046] Effects of pH and DO pH and DO concentrations play a crucial role in regulating ammonification, nitrification, denitrification, hydrolysis, digestion, aerobic oxidation, and carbon removal. The pH of the raw coking wastewater is 9.5±1.0, and this slightly alkaline raw water effectively provides the alkalinity required for nitrification in the pre-O1 reactor, avoiding the need for large-scale liquid alkali addition. Studies have shown that when glucose is used as a carbon source for HetDen denitrification, organic acids are produced during metabolism, and the pH gradually increases after being utilized by denitrifying bacteria. Therefore, H1 and H2 denitrification via HD results in a slight increase in the effluent pH. The alkalinity generated by H1 and H2 denitrification is used to meet the alkalinity consumed by O2 for complete nitrification, avoiding continuous liquid alkali addition. Based on the high oxygen utilization rate of the BFBR and the aeration distribution of the two Os, the DO concentrations of O1 and O2 are maintained at 1.5~2.5 mg / L and 4.0~5.0 mg / L, respectively, with air-to-water ratios of (20~25):1 and (10~12):1. Compared to the AAO single-O reactor with an air-to-water ratio of (40-50):1, the OHHO dual-O reactor reduces aeration energy consumption by approximately 30%. However, the recirculation of nitrifying liquor from O2 to H2 results in a high concentration of DO. Therefore, denitrification in the H2 reactor requires the utilization of some carbon sources to consume DO. HetDen only begins when the DO in the H2 reactor drops below 0.5 mg / L. In summary, the OHHO process cleverly utilizes the characteristics of water quality changes during system operation to adjust pH and DO, achieving flexible material distribution and reducing energy and reagent consumption throughout the process. Using sludge from desulfurization wastewater pretreatment as an electron donor necessitates consideration of toxicity inhibition.

[0047] COD, SCN - And the impact of TCN After treatment with the CT2PC-OHHO process, the COD of the highly toxic coking wastewater and desulfurization wastewater with a high C / N ratio stabilized below 80 mg / L in the effluent. When the COD of the coking wastewater was around 3900 mg / L, the COD value in the collection and equalization tank, mixed with the supernatant of the desulfurization wastewater, remained almost unchanged, with fluctuations of less than 3%. The COD removal rate of the effluent under all four operating modes reached over 90%. Figure 5-7The reduction of COD in the pre-physicochemical reactor is mainly achieved through the addition of ferrous salts and PAM to precipitate and complex some reducing inorganic and organic matter, as well as the mixing and dilution effect in the equalization tank. The reduction of COD in the O1 tank is mainly achieved through the oxidation of organic matter such as phenols, heterocyclic aromatics, and polycyclic aromatics, relying on the high oxygen utilization rate of the BFBR to ensure complete nitrification while removing organic matter under low DO conditions. Figure 6 It can be seen that during the operation of modes III and IV, the COD of the effluent from the H1 tank is higher than that of the influent. This is due to the overflow of carbon source caused by the addition of excessive electron donors. This part of the COD will be used for further HD denitrification reaction in the H2 tank. At the same time, the O2 tank ensures complete COD removal by increasing the DO concentration.

[0048] As is well known, CN - Extremely toxic, primarily through direct ingestion, skin contact, and inhalation of volatile CN compounds. - CN in water can enter organisms through contact with cyanide-containing wastewater and other pathways. - A concentration of 0.05 mg / L can cause poisoning and death in aquatic organisms. (SCN) - The toxicity of CN is higher. - The toxicity is about 100 times lower, when CN - with Fe 2+ and Fe 3+ The toxicity of Prussian blue (Fe4[Fe(CN)6]3·xH2O) complex precipitate was reduced by approximately 1950 times, and SCN... - with Fe 3+ Ferric thiocyanate, which forms a complex, can also significantly reduce SCN levels. - Inhibitory effect on microbial toxicity. Based on long-term water quality monitoring at the engineering site, the CN content in the raw coking wastewater... - The initial concentration was 12±2.5 mg / L, and the weighted average concentration of the desulfurization wastewater reached 16±3.5 mg / L. The TCN concentration was 32±5 mg / L, and the SCN concentration was... - The concentration of CN was 700±50 mg / L, a high concentration. - and SCN - Introducing microorganisms into the biological treatment tank will inevitably cause severe toxic inhibition of microorganisms, leading to the failure of denitrification. Figure 6 It can be seen that SCN in the CT2PC-OHHO process - The removal rates of CN and TCN reached over 99.9% and 95.5% respectively, and the removal rates of free CN in the external drainage were also significantly reduced. - The concentration was below 0.2 mg / L. 85% of TCN was removed in the pre-physicochemical tank by adding ferrous salt, including free CN. - The removal rate reached over 98%, with the remaining TCN existing in a metal-cyanide complex form, which was gradually oxidized in subsequent biological processes. Compared to TCN, SCN...- Only about 20% of the pollutants are removed in the pre-physicochemical treatment tank; the majority, in a low-toxicity dissolved ferric thiocyanate complex, is completely oxidized and hydrolyzed into ammonia nitrogen and sulfate ions in the O1 tank. This also demonstrates the necessity of a pre-aerobic tank in the new coking wastewater treatment process. Based on the internal circulation structure of the biological fluidized bed reactor and the solution properties of the coking wastewater, the O1 tank exhibits strong resistance to toxic shocks and high load carrying capacity. This action eliminates toxicity inhibition and carbon source inhibition, playing a decisive role in the high abundance enrichment and continuous stable operation of denitrifying microorganisms in subsequent reactors. Therefore, this new process provides a reference for treating wastewater with characteristic toxic pollutants.

[0049] The microbial community of sludge samples from each reactor under four different operating modes was analyzed using 16S rRNA amplicon sequencing. Table 4 shows the richness and diversity indices of the microbial community in the sludge samples. A total of 46,362–62,708 high-quality sequences were obtained from all samples, with OUT values ​​ranging from 296 to 643. High coverage (99.6%–99.8%) was observed in all samples, indicating that the sequencing depth in this study can well cover the microbial community in the OHHO process. ACE and Chao indices were used to assess the number of OTUs present in the community, both of which were positively correlated with community richness. Shannon and Simpson indices are commonly used to describe the species diversity of bacterial communities; a higher Shannon index and a lower Simpson index represent higher community diversity, respectively. During the operation of the four modes, compared with H1, H2, and O2, reactor O1 had the lowest Shannon index (2.195, 2.515, 2.962, and 3.047) and the highest Simpson index (0.275, 0.167, 0.141, and 0.129), indicating that reactor O1 had the lowest species diversity. This may be related to the inhibition of selective growth of functional microorganisms by high COD and toxicity. Compared with mode I, after adding a carbon source in modes II-IV, the Shannon, Ace, and Chao indices of reactors H1 and H2 decreased, while the Simpson index increased, indicating lower microbial diversity and abundance. This may be due to the enrichment of denitrifying bacteria caused by the addition of a carbon source. The microbial community diversity in each unit reactor showed a decreasing trend from mode I to mode IV, indicating that process-based regulation and carbon source management achieved the selection and enrichment of functional bacteria.

[0050] Table 4. OUT and diversity indices of bacterial system types in sludge samples

[0051] Figure 7The relative abundance of major phyla with a sequence percentage greater than 0.1% is shown, along with the relative abundance of other taxa, including unclassified, unidentified, norank, and taxa with a relative abundance less than 0.1%. At the phylum level, the sludge mainly contains... Proteobacteria , Acidobacteriota , Chloroflexi , Actinobacteriota , Bacteroidota , Planctomycetota , Patescibacteria , Desulfobacterota and Nitrospirota The results showed that Proteobacteria (11.99%~68.68%) and Acidobacteriota (9.52%~48.63%) are the most widely represented groups in the OHHO process. These two groups have proven to be the main groups in coking wastewater, landfill leachate, and petrochemical wastewater treatment systems, thus indicating that the coking wastewater treatment system has achieved bacterial enrichment at the group level. Under optimal operating mode IV conditions, the main bacterial groups in reactors H1 and H2 are Chloroflexi and Actinobacteriota The main bacterial communities in pools O1 and O2 are Bacteroidota and Planctomycetota Compared to Mode I, in Operation Mode IV, which simultaneously injects carbon sources into both pools H1 and H2, Actinobacteriota , Patescibacteria and Desulfobacterota The proportion of bacteria increased. These results indicate that under different operating modes of the OHHO process, most bacterial phyla exhibited spatial redistribution and readjustment, suggesting that the addition of dissolved oxygen and carbon sources affects the enrichment and fate of microorganisms during the treatment of coking wastewater.

[0052] At the genus level, 91 bacterial genera were detected. 67.46% of the total sequences were unclassifiable and norank, indicating that some taxa remain undiscovered during the OHHO process. Figure 8 The microbial communities and structures at the genus and species level in each reactor under the four operating modes of the OHHO process are shown. Ottowia (15.4%~19.6%) and Limnobacter (1.8%~7.4%) are the two genera with the highest relative abundance in the OHHO process system, and their proportion is higher in the double O reactor than in the double H reactor. Based on previous studies, Ottowia and Limnobacter It can effectively degrade organic compounds such as phenols and PAHs, which also confirms that most of the COD removal is achieved in the O1 and O2 reactors. In Modes III and IV, the O1 reactor... Ferruginibacter (0.4%~1.9%) and PseudolabrysThe relative abundance of these two genera (0.3%–1.5%) was generally higher than that of other reactors, and there are reports that they can remove organic matter and degrade toxic substances (such as SCN). - CN - The above results indicate that the BFBR-based O1 reactor exhibits strong shock resistance under high load and high toxicity conditions.

[0053] like Figure 8 As shown, it was detected in modes I-IV. Nitrosomonas (0.7%~2.4%) and Nitrospira (0.3%~1.7%), their relative abundance was highest observed in the double O reactor. Nitrosomonas and Nitrospira It is the most important ammonia-oxidizing bacteria (which convert NH4+ into nitrogen dioxide). + -N and convert to NO2 - -N) and nitrite-oxidizing bacteria (which convert NO2) - -N is converted to NO3 - -N), while AOB and NOB are autotrophic microorganisms with low growth rates and yields, are sensitive to changes in the external environment, and are easily affected by toxic substances. Nitrification was observed in the O1 and O2 reactors. Ellin6067 and Pleomorphomonas These microbiological results demonstrate the feasibility of using a dual-O reactor to regulate ammoniation, nitrification, and nitrification. Furthermore, Micropruina , SM1A02 and Pedomicrobium They also have denitrification capabilities, and these microorganisms are found in dual H (H1 and H2). Thiobacillus It is another dominant genus in the OHHO process, with relative abundance values ​​of 14.94%, 2.31%, 6.99%, and 6.74% in Model IV, respectively. Based on previous studies, Thiobacillus Members are multifunctional, reducing sulfur degraders (such as S...) 2– NO3 can be used - -N or O2 act as electron acceptors, and they are commonly observed in industrial wastewater treatment systems. In this study, organic matter and toxicity inhibition (SCN) were investigated. - TN was effectively removed in reactor O1; while TN was removed in reactors H1 and H2 through regulation and enrichment by functional microorganisms.

[0054] A comprehensive comparison of the chemical consumption, electricity consumption, greenhouse gas emissions, and residual sludge production of AAO, AOO, AOHO, and OHO processes in coking wastewater treatment revealed that the OHO process exhibited the most stable and reliable operation with the lowest chemical costs and average energy consumption. As shown in Table 5, chemical consumption, electricity and aeration energy consumption, sludge disposal, and operation and maintenance costs constitute the basic operating costs of the CT2PC-OHHO process. Under the optimal operating mode IV, these costs accounted for 45.4%, 46.7%, 2.1%, and 5.8%, respectively, with chemical reagents and energy consumption exceeding 90% of the costs. The usage of liquid alkali and glucose depends on the process operating mode and reactor efficiency. Maximizing the utilization of internal carbon sources (including those from desulfurization wastewater) and controlling alkali production and consumption during the denitrification process minimized the use of liquid alkali and glucose. The agitator and pumps were the main factors affecting electricity consumption; the electricity generated by the Roots blower to produce compressed air was converted into gas consumption. Average energy consumption is related to the DO and HRT maintained in the aerobic reactor. O1 can control DO within the range of 1.0~1.2 mg / L to rapidly degrade COD. The remaining recalcitrant COD is removed in O2 after anaerobic hydrolysis by H1 and H2. The two-step aerobic unit effectively shortens the HRT of the aerobic tank, reducing energy input in wastewater treatment. Compared with the AAO process, although the OHHO process has two aerobic units, the O1 reactor combined with the BFBR structure effectively reduces COD while improving oxygen utilization, reducing the load on the O2 reactor, and enhancing the adaptability of the entire system to the characteristics of coking wastewater. This significantly reduces the energy consumption of the entire process system. The distribution and use of oxygen creates a favorable environment for subsequent denitrification reactions. Combined with the process's avoidance of sludge recirculation, it saves energy consumption from microbial functional adaptation and the energy consumption from volume-doubling mixing. In addition, the O1 effluent provides suitable water quality conditions for the survival of anaerobic ammonia-oxidizing bacteria, which offers the possibility of new, lower-energy-consumption denitrification pathways.

[0055] As shown in Table 5, the total operating cost of the O1 reactor and the post-physicochemical treatment unit exceeded 50%. This was due to the high aeration volume in the O1 tank leading to increased air consumption, the need to add liquid alkali for nitrification acid production, and the increased chemical consumption in the post-physicochemical treatment tank due to the addition of polyferric sulfate, activated carbon, liquid alkali, PAM, and other agents. Chemical consumption accounted for nearly half of the total cost. This was because ferrous salts were needed in the pre-physicochemical treatment to reduce the toxicity of the raw water. Furthermore, the difficulty in removing high and low concentrations of suspended solids in the biological effluent resulted in unavoidable consumption of large amounts of chemicals in the post-physicochemical treatment of coking wastewater. Based on the solution properties of coking wastewater, the cost of the OHHO process mainly lies in chemical consumption, but it has lower electricity consumption and lower infrastructure investment costs. Nevertheless, the amount of chemicals used in the OHHO process after modification is only 75%~80% of that used in the original AAO process. Combined with the reduction in electricity consumption, the total operating cost is between 8.26 and 10.32 yuan / m³. 3This reduced the water quality by more than 30%, while significantly improving the quality of the effluent.

[0056] Table 5. Economic Analysis of CT2PC-OHHO Process Operation (Unit: Yuan / m³) 3 )

[0057] As can be seen from the above, this invention develops an in-situ sludge separation process using a dual physicochemical synergistic aerobic-hydrolysis & denitrification-hydrolysis & denitrification-aerobic (CT2PC-OHHO) method. This process achieves complete removal of typical pollutants and total nitrogen (TN) through the rational allocation of energy and internal carbon source / electron donors. Compared with existing technologies, it has the following advantages: (1) In the proposed process, the CT2PC function realizes the fractional utilization of electron donors hidden in wastewater / waste liquid; the O1 reactor makes the main contribution to the removal of organic matter and complete nitrification; the dual H reactors (H1 and H2) achieve deep reduction of total nitrogen (high concentration - low concentration) through combination and coupling of denitrification pathways; the O2 reactor further ensures complete carbon removal and nitrification.

[0058] (2) The results of 180 days of continuous operation of the project show that when the influent load is 1.5~1.7 kg COD / (m³) 3 ·d) and 0.11~0.13 kg TN / (m 3 ·d) In the optimal operating mode, the removal rates of COD and TN were 97.5% and 94.5%, respectively; the project was implemented under the nationwide bidding process of Baowu Group, and it gained recognition and attention from the industry after the project was accepted.

[0059] (3) Microbial analysis of the entire process showed that Nitrosomonas (0.7%~2.4%) and Nitrospira (0.3%~1.7%) Dominant bacteria play a major role in nitrification, while efficient removal of organic matter is achieved by… Ottowia (15.4%~19.6%) and Limnobacter The dominant bacteria (1.8%~7.4%) and others; the OHHO process of the sludge system realizes the spatial recombination and distribution of functional microorganisms.

[0060] (4) The total operating cost of the entire process is approximately RMB 9.18 / m 3 The CT2PC-OHHO process is a promising alternative wastewater treatment technology to the traditional AAO process because it demonstrates high efficiency and stability in the removal of typical pollutants.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for resourceful treatment of desulfurization waste liquid, characterized in that, The desulfurization waste liquid contains sulfides, cyanide, thiocyanide, phenolic compounds, and nitrogen-containing compounds. A method for resourceful treatment of the desulfurization waste liquid comprises: After the sulfides contained in the desulfurization waste liquid are precipitated, ferric chloride is added to the filtered supernatant to convert cyanide in the desulfurization waste liquid into ferricyanide precipitate. The filtered ferricyanide precipitate is subjected to oxidation and dissolution treatment to obtain a solution containing ferric chloride.

2. The method of claim 1, wherein, The method comprises the following steps: Ferrous sulfate is added to the desulfurization waste liquid to perform a first precipitation reaction, and a primary precipitate and a primary supernatant are obtained through separation. Calcium chloride is added to the primary supernatant to perform a second precipitation reaction, and then polyacrylamide is added, and a secondary precipitate and a secondary supernatant are obtained through separation. Ferric chloride is added to the secondary supernatant to perform a third precipitation reaction, and ferricyanide precipitate and desulfurization waste liquid supernatant are obtained through separation. The desulfurization waste liquid supernatant contains ferrous sulfide, ferrous sulfite, ferrous sulfate, ferric sulfate, calcium thiosulfate, and complexes of thiocyanide and residual cyanide. The ferricyanide precipitate is subjected to oxidation and dissolution treatment to obtain a solution containing ferric chloride. Preferably, the desulfurization waste liquid is pretreated by at least one of pH adjustment, suspended solids / heavy metal removal, and dilution with recycled water before precipitation.

3. The method of claim 1 or 2, wherein, The primary precipitate contains ferrous sulfide and ferrous sulfite, the secondary precipitate contains calcium sulfide, calcium sulfite, and calcium sulfate, and the ferricyanide precipitate contains Prussian blue precipitate and Tenn's blue precipitate. Preferably, the ferricyanide precipitate is oxidized by ozone oxidation, and the acid used for dissolution is hydrochloric acid. More preferably, the solution containing ferric chloride obtained by oxidation and dissolution treatment of the ferricyanide precipitate is returned as a reagent for cyanide precipitation.

4. A method for resourceful treatment of desulfurization waste liquid, characterized in that, The desulfurization waste liquid contains sulfides, cyanide, thiocyanide, phenolic compounds, and nitrogen-containing compounds. A method for resourceful treatment of the desulfurization waste liquid comprises: After the sulfides contained in the desulfurization waste liquid are precipitated, ferric chloride is added to the filtered supernatant to convert cyanide in the desulfurization waste liquid into ferricyanide precipitate. The filtered ferricyanide precipitate is subjected to oxidation and dissolution treatment to obtain a solution containing ferric chloride. The desulfurization waste liquid supernatant is used as an electron donor for biological denitrification of nitrogen-containing wastewater, preferably coking wastewater.

5. The method of claim 4, wherein, The method comprises the following steps: Pre-treatment: ferrous sulfate is added to the desulfurization waste liquid to perform a first precipitation reaction, and a primary precipitate and a primary supernatant are obtained through separation. Calcium chloride is added to the primary supernatant to perform a second precipitation reaction, and then polyacrylamide is added, and a secondary precipitate and a secondary supernatant are obtained through separation. Ferric chloride is added to the secondary supernatant to perform a third precipitation reaction, and ferricyanide complex precipitate and desulfurization waste liquid supernatant are obtained through separation. The ferricyanide complex precipitate is subjected to oxidation and dissolution treatment to obtain a solution containing ferric chloride. Biological denitrification treatment: the desulfurization waste liquid supernatant and coking wastewater raw water are mixed to remove total nitrogen. Post-physical treatment: polyferric chloride, activated carbon, liquid alkali and polyacrylamide are added into the biological effluent produced by biological denitrification treatment in sequence to remove suspended solids and decolorize.

6. The method of claim 5, wherein, The biological denitrification treatment comprises: sequentially performing nitrification treatment, denitrification treatment and nitrification treatment on the mixed solution of the desulfurization waste liquid supernatant and the coking wastewater raw water to remove the nitrogen-containing compounds in the mixed solution of the desulfurization waste liquid supernatant and the coking wastewater raw water; Preferably, the flow ratio of the coking wastewater and the desulfurization waste liquid for nitrification treatment is 15:1 to 10:

1.

7. The method of claim 6, wherein, The biological denitrification treatment comprises the following steps: pumping the desulfurization waste liquid supernatant and 70% to 80% of the coking wastewater raw water into an O1 unit in a biological treatment OHHO process to achieve partial nitrification of the nitrogen-containing compounds in the desulfurization waste liquid supernatant and the coking wastewater raw water and degradation of the complex of thiocyanide and the complex of residual cyanide in the desulfurization waste liquid supernatant, receiving 20% to 30% of the coking wastewater raw water, secondary precipitation and nitrification liquid from the O1 unit in an H1 unit, receiving primary precipitation, treated water from the H1 unit and partial reflux nitrification liquid from O2 in an H2 unit, and discharging biological effluent from the O2 unit; Preferably, the volume ratio of the H1 unit and the H2 unit is 2:

1.

8. The method of claim 7, wherein, Further comprising: Phosphorus salt nutrients are supplemented in the O1 unit, and the alkalinity is appropriately supplemented with NaHCO3 to a pH value greater than 8.0, the biological unit reactors are all designed with sludge in-situ separation function, and sludge reflux is not required, and the suitable MLSS concentration, DO value, temperature and hydraulic retention time of the O1 unit, the H1 unit, the H2 unit and the O2 unit are controlled to achieve the nitrification treatment, denitrification treatment and nitrification treatment of the desulfurization waste liquid supernatant and most of the coking wastewater raw water in the best state.

9. A wastewater innoculation treatment system characterized by, Comprising: a pre-physical unit mainly used for removal of cyanide and sulfide in the desulfurization waste liquid, a water collection and adjustment tank used for balancing the flow and water quality fluctuation of the influent, four units in the OHHO process used for biological denitrification treatment of the desulfurization waste liquid supernatant and the coking wastewater raw water, and a post-physical unit used for removal of suspended solids and color treatment of the biological effluent produced by the OHHO process, and the OHHO process comprises an O1 unit, an H1 unit, an H2 unit and an O2 unit, the effluent outlet of the pre-physical unit is connected with the influent inlet of the water collection and adjustment tank, the effluent outlet of the water collection and adjustment tank is connected with the influent inlet of the O1 unit through a booster pump, the effluent outlet of the O1 unit is connected with the influent inlet of the H1 unit, the effluent outlet of the H1 unit is connected with the influent inlet of the H2 unit, the effluent outlet of the H2 unit is connected with the influent inlet of the O2 unit, and the effluent outlet of the O2 unit is connected with the influent inlet of the post-physical unit.

10. The wastewater innocuity treatment system according to claim 9, characterized by Further comprising: The VOCs purification tower is connected with the activated carbon feeding tower, the activated carbon feeding tower is connected with the post-physical and chemical unit, the post-physical and chemical unit is connected with the VOCs purification tower, the VOCs purification tower is connected with the volatile organic matter outlet of the adjusting water collecting pool and the volatile organic matter outlet of the pre-physical and chemical unit, and the VOCs purification tower is connected with the biological process O1 unit.

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