A method for treating mixed wastewater from co-production of phosphate fertilizer and flame retardant

Abstract

The application discloses a kind of phosphorus fertilizer-flame retardant co-production mixed production wastewater treatment methods, belong to phosphorus fertilizer-flame retardant co-production fertilizer field, comprising the following steps: S1, adjust raw water pH;S2, one-time dosing composite function reagent, dosing amount 8 g / L~25 g / L, reagent is composed of the following components: zirconium oxyhydroxide 15wt~25wt%, magnesium oxide 20wt%~30wt%, modified zeolite 35wt%~50wt%, PFS 5wt%~10wt%, CPAM 0.5wt%~1.5wt%, total 100%;S3, gradient stirring is carried out for 13min~20min for synergistic reaction;S4, settlement is placed.The application realizes organic phosphorus oxidation degradation, total phosphorus precipitation, ammonia nitrogen crystallization solidification, potassium ion selective adsorption simultaneously in the same reaction unit, and high concentration phosphorus, ammonia nitrogen and potassium ion in wastewater are removed once.

Description

Technical Field

[0001] This invention relates to the field of co-production of phosphate fertilizer and flame retardant, and particularly to a method for treating wastewater from the co-production of phosphate fertilizer and flame retardant. Background Technology

[0002] Both fertilizer production wastewater and flame retardant production wastewater are recognized in the industry as difficult-to-treat industrial wastewater. It is noteworthy that some flame retardant products (such as ammonium polyphosphate) and fertilizer products (such as ammonium phosphate and potassium dihydrogen phosphate) share similar chemical compositions. The main difference lies in the degree of polymerization of the phosphate group—fertilizers are primarily composed of orthophosphates, while flame retardants are mainly composed of polymerized phosphates (such as pyrophosphate, tripolyphosphate, and polyphosphates with higher degrees of polymerization). When the same manufacturer is involved in both fertilizer and flame retardant production, its wastewater exhibits significant specificity and complexity: on the one hand, the wastewater contains large amounts of both orthophosphate and polymerized phosphate; the former is easily removed through precipitation, while the latter, due to polymerization... Phosphorus has high bond energy and large molecular size, and its degradation requires chain scission reactions. The coexistence of two types of phosphorus makes it difficult for a single phosphorus removal mechanism to address both. On the other hand, high concentrations of ammonia nitrogen and potassium ions (originating from fertilizer production) coexist with polymeric phosphate and its intermediates, forming a complex pollution system of "inorganic phosphorus-polymeric phosphorus-ammonia nitrogen-potassium ions-high salt". In addition, polymeric phosphate has a certain hydrolysis lag in wastewater, and some oligomers have the potential to inhibit microbial activity, further increasing the unpredictability of biological treatment. The superposition of the above multiple factors makes the mixed wastewater in this specific scenario far inferior to single-product wastewater in terms of treatability and compliance stability, forming a special treatment problem that is different from general chemical wastewater.

[0003] The existing methods for treating this type of mixed wastewater are the same as those used in general chemical enterprises. The technical routes for the physicochemical treatment stage of these general chemical enterprise wastewater treatment methods are mainly divided into two categories: segmented combined processes and single-function materials / processes.

[0004] While segmented processes (such as "hydrolysis / oxidation → coagulation and sedimentation") can reduce pollutants step by step, there are significant mechanistic conflicts between the units: the chain scission conditions of polyphosphates are contrary to the suitable pH range for precipitation / crystallization reactions.

[0005] In terms of single-function materials / processes, flocculation and sedimentation are basically ineffective against polymerized phosphates; struvite crystallization cannot utilize polymerized phosphates, and high concentrations of potassium ions will compete to form potassium struvite (MgKPO4), reducing ammonia nitrogen removal rate and product purity; in the adsorption method, zirconium-based materials have weak adsorption capacity for polymerized phosphates, and the ammonium exchange sites of zeolite are strongly competed for by potassium ions, and simple mixing of the two cannot achieve synergy.

[0006] It is evident that the fundamental dilemma of existing technologies lies in the fact that the chain-breaking degradation of polymeric phosphates, the precipitation removal of orthophosphates, the solidification of ammonia nitrogen, and the selective separation of potassium ions each rely on different chemical mechanisms. These mechanisms conflict with each other within a single reactor, and the high potassium and high salt background further exacerbates the instability of each mechanism, rather than achieving synergy through simple superposition. The conventional approach in this field is to increase the number of units and strengthen the pretreatment of different components to avoid mechanism conflicts, but this does not solve the fundamental problem of multi-mechanism synergy at the reactor level.

[0007] To date, the physicochemical treatment methods used by fertilizer-flame retardant (ammonium polyphosphate) co-production enterprises for treating production wastewater are the same as those used by general chemical enterprises.

[0008] There is an urgent need for a treatment method specifically for the wastewater from the co-production of phosphate fertilizer and flame retardant. Summary of the Invention

[0009] To address the aforementioned shortcomings, this invention provides a treatment method specifically for wastewater from the co-production of phosphate fertilizer and flame retardant. Within the same reaction unit, organic phosphorus oxidation and degradation, total phosphorus precipitation, ammonia nitrogen crystallization and solidification, and potassium ion selective adsorption are simultaneously achieved, removing high concentrations of phosphorus, ammonia nitrogen, and potassium ions from the wastewater in one step. The process has a short route, strong shock resistance, and the sludge can be utilized as a resource.

[0010] A method for treating wastewater from the co-production of phosphate fertilizer and flame retardant includes the following steps: S1, adjusts the pH of the raw water to form conditioned wastewater; S2, Add a compound functional agent to the conditioned wastewater in a single application at a dosage of 8 g / L to 25 g / L. The agent consists of the following components: Zirconia hydroxya 15wt%~25wt%, magnesium oxide 20wt%~30wt%, modified zeolite 35wt%~50wt%, PFS 5wt%~10wt%, CPAM 0.5wt%~1.5wt%, total 100%; S3, use gradient stirring for synergistic reaction for 13min~20min. The gradient stirring is in two stages, with the stirring speed in the first stage being greater than that in the second stage. S4, allow to settle and obtain the supernatant and the bottom sludge.

[0011] In one or more alternative embodiments of the present invention, in S1, the pH is adjusted to 8.0 to 9.2.

[0012] In one or more alternative embodiments of the present invention, in S2, the modified zeolite is acid-modified clinoptilolite.

[0013] In one or more alternative embodiments of the present invention, acid-modified clinoptilolite is prepared by the following steps: Natural clinoptilolite is crushed to 100-120 mesh, soaked in hydrochloric acid at room temperature, washed with deionized water until neutral, and then dried.

[0014] In one or more optional embodiments of the present invention, the solid-liquid ratio of natural clinoptilolite to hydrochloric acid is 1g:50ml, the concentration of hydrochloric acid is 0.8 mol / L to 1.2 mol / L, and the soaking time is 4h to 6h.

[0015] In one or more optional embodiments of the present invention, in S3, the first stage is stirring at 120 r / min to 150 r / min for 3 min to 5 min, and the second stage is stirring at 30 r / min to 50 r / min for 10 min to 15 min.

[0016] In one or more alternative embodiments of the present invention, in S4, the settling time is 20 min to 30 min.

[0017] In one or more optional embodiments of the present invention, in S4, the supernatant is either discharged directly after meeting the standards or sent to a subsequent deep treatment unit for further processing.

[0018] In one or more optional embodiments of the present invention, in S4, the main components of the bottom sludge are magnesium ammonium phosphate, zirconium-based precipitate, and potassium-loaded zeolite, which are rich in nitrogen, phosphorus, and potassium elements. The bottom sludge is dewatered and then processed into slow-release compound fertilizer.

[0019] In one or more alternative embodiments of the present invention, S1, S2, S3 and S4 are all performed in the same pool.

[0020] Compared with existing technologies, the invention principles and beneficial effects are as follows: Addressing the specific characteristics of mixed wastewater from the co-production of phosphate fertilizer and flame retardants, this invention utilizes a compound formulation and gradient stirring to create a multi-reaction synergistic system. This composite system oxidizes and decomposes organic phosphorus from the flame retardant, complexes and precipitates inorganic phosphorus, and neutralizes some toxic substances, reducing the wastewater's bioinhibitory properties. It also reacts with ammonia nitrogen and phosphate to form magnesium ammonium phosphate (struvite) crystals, solidifying ammonia nitrogen and inorganic phosphorus. The system selectively adsorbs potassium ions and residual ammonia nitrogen from the water, trapping crystalline particles, adsorption fillers, and colloidal pollutants to form dense flocs for rapid solid-liquid separation. Specifically, the first stage of gradient stirring ensures thorough mixing of the reagents and wastewater, initiating organic phosphorus oxidation and ion reactions. The second stage promotes struvite crystal growth, potassium ion adsorption, and floc aggregation.

[0021] In this invention, all reactions occur simultaneously in the same reaction tank, eliminating the need for separate tanks or segmented treatment, and achieving a one-step process of "influent → chemical addition → reaction → sedimentation → effluent". Within the same reaction unit, organic phosphorus oxidation and degradation, total phosphorus precipitation, ammonia nitrogen crystallization and solidification, and potassium ion selective adsorption are achieved simultaneously, removing high concentrations of phosphorus, ammonia nitrogen, and potassium ions from wastewater in one step. The process route is short, has strong shock resistance, and the sludge can be utilized as a resource. Detailed Implementation

[0022] The present invention will be further described below.

[0023] As used in this article: "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0024] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0025] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0026] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents (materials) or instruments (equipment) used without a specified manufacturer are all commercially available conventional products.

[0028] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0029] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (K is any number representing a multiplier). It is important to understand that, unlike the number of parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0030] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0031] In the following examples and comparative examples, the acid-modified clinoptilolite was prepared by the following method: Natural clinoptilolite was crushed to 100 mesh, soaked in 1.0 mol / L hydrochloric acid at room temperature for 5 h (solid-liquid ratio of 1g:50ml), washed with deionized water until neutral, and dried at 105℃ for later use.

[0032] In the following examples and comparative examples, salt-modified clinoptilolite was prepared by the following method: Natural clinoptilolite was crushed to 100 mesh, soaked in 1.0 mol / L sodium chloride solution at room temperature for 5 h (solid-liquid ratio of 1g:50ml), washed with deionized water until neutral, and dried at 105℃ for later use.

[0033] Example 1 S1, the pH of the raw water from the equalization tank is adjusted to 8.6 to form regulated wastewater. The raw water quality is shown in Table 1.

[0034] S2, Add a compound functional agent to the conditioned wastewater in a single application at a dosage of 20 g / L. The agent consists of the following components: Zirconia hydroxya 21.1 wt%, magnesium oxide 26.3 wt%, acid-modified clinoptilolite 44.2 wt%, PFS 7.4 wt%, CPAM 1.1 wt%.

[0035] S3, first stir at 130 r / min for 4 min, then stir at 40 r / min for 12 min.

[0036] S4, let stand and settle for 25 minutes to obtain the supernatant and the bottom sludge.

[0037] S1, S2, S3 and S4 are all conducted in the same pool.

[0038] The results of testing the supernatant are shown in Table 1.

[0039] Example 2 The difference compared to Example 1 is as follows: In this embodiment, the composition is 25 wt% zirconium hydroxya, 25 wt% magnesium oxide, 40 wt% acid-modified clinoptilolite, 8.5 wt% PFS, and 1.5 wt% CPAM.

[0040] In S3, stir at 150 r / min for 3 min, and then stir at 50 r / min for 15 min.

[0041] The results of testing the supernatant are shown in Table 1.

[0042] Example 3 Compared with Example 1, the difference is that in S2, the acid-modified clinoptilolite of Example 1 is replaced with the same weight of salt-modified clinoptilolite.

[0043] Comparative Example 1 The difference compared to Example 1 is as follows: Stir at 130 r / min for 16 min in S.

[0044] The results of testing the supernatant are shown in Table 1.

[0045] Comparative Example 2 The difference compared to Example 1 is as follows: Stir at 40 rpm for 16 minutes in S.

[0046] The results of testing the supernatant are shown in Table 1.

[0047] Comparative Example 3 The difference compared to Example 1 is as follows: In S2, PFS is replaced with PAC of the same weight, and CPAM is replaced with PAM of the same weight.

[0048] The results of testing the supernatant are shown in Table 1.

[0049] Comparative Example 4 The difference compared to Example 1 is as follows: In S2, the reagent does not contain zirconium hydroxide, magnesium oxide, or acid-modified clinoptilolite, but the dosage is the same as in Example 1, and the PFS:CPAM weight ratio is also the same as in Example 1.

[0050] Comparative Example 5 Compared to Comparative Example 4, the difference is: In S2, PFS is replaced with PAC of the same weight, and CPAM is replaced with PAM of the same weight.

[0051] Comparative Example 6 The difference compared to Example 1 is as follows: In S2, the only reagent is magnesium oxide, but the dosage remains unchanged.

[0052] Comparative Example 7 The difference compared to Example 1 is as follows: In S2, the reagent does not contain PFS and CPAM, but the dosage is the same as in Example 1, and the weight ratio of zirconia hydroxya: magnesium oxide: acid-modified clinoptilolite is also the same as in Example 1.

[0053] Example 4 S1, the pH of the raw water from the equalization tank is adjusted to 8.9 to form regulated wastewater. The raw water quality is shown in Table 1.

[0054] S2, A compound functional agent is added to the conditioned wastewater in a single application at a dosage of 22 g / L. The agent consists of the following components: Zirconia hydroxya 26.3 wt%, magnesium oxide 23.2 wt%, acid-modified clinoptilolite 40.0 wt%, PFS 9.5 wt%, CPAM 1.1 wt%.

[0055] S3, first stir at 130 r / min for 4 min, then stir at 40 r / min for 12 min.

[0056] S4, let stand and settle for 25 minutes to obtain the supernatant and the bottom sludge.

[0057] S1, S2 and S3 are carried out in the flocculation tank, while S4 is carried out in the sedimentation tank.

[0058] The results of testing the supernatant are shown in Table 1.

[0059] Example 5 S1, the pH of the raw water from the equalization tank is adjusted to 8.3 to form regulated wastewater. The raw water quality is shown in Table 1.

[0060] S2, Add a compound functional agent to the conditioned wastewater in a single application at a dosage of 20 g / L. The agent consists of the following components: Zirconia hydroxya 18wt%, magnesium oxide 28wt%, acid-modified clinoptilolite 46wt%, PFS 7wt%, CPAM 1wt%.

[0061] S3, first stir at 130 r / min for 4 min, then stir at 40 r / min for 12 min.

[0062] S4, let stand and settle for 25 minutes to obtain the supernatant and the bottom sludge.

[0063] S1, S2, and S3 are all carried out in the flocculation tank, while S4 is carried out in the settling tank. The results of testing the supernatant are shown in Table 1.

[0064] Table 1 As can be seen from Table 1, 1. Comparison of reagent formulation performance: Based on Example 1 with the complete composite reagent, the effluent total phosphorus was only 0.32 mg / L, ammonia nitrogen was 138 mg / L, and COD was 3120 mg / L, demonstrating excellent decontamination effect. However, the treatment effect of Comparative Example 3 (replacing the traditional flocculant), Comparative Examples 4 and 5 (removing the core zirconium-magnesium zeolite component), and Comparative Examples 6 and 7 (single-component reagents) deteriorated significantly. Comparative Example 4 showed a total phosphorus level as high as 216.5 mg / L, proving that the synergistic effect of each component is the core of efficient water purification, and that single or traditional flocculation systems cannot meet the treatment requirements.

[0065] 2. Comparison of the effects of zeolite modification methods: Under the same process conditions, Example 1, which uses acid-modified clinoptilolite, showed excellent treatment results; the effluent quality of Example 3, which replaced it with salt-modified clinoptilolite, decreased significantly, with total phosphorus rising to 1.86 mg / L and potassium ion and COD removal rates significantly reduced, confirming that the adsorption and purification performance of acid-modified zeolite is significantly better than that of salt-modified zeolite.

[0066] 3. Comparison of stirring process parameters: Example 1, which used segmented stirring with both fast and slow speeds, showed stable flocculation and sedimentation effects. Comparative Examples 1 and 2, which used uniform stirring throughout the process, exhibited extremely poor treatment effects, with total phosphorus levels reaching 42.31 mg / L and 36.75 mg / L, respectively. The pollutant removal efficiency decreased significantly, indicating that segmented stirring is a key process for ensuring good flocculation and sedimentation.

[0067] Overall conclusion: Compared with the defective formulations and unreasonable processes of all comparative examples, the multi-component compound agent combined with the segmented stirring process used in the example can stably and efficiently remove total phosphorus, ammonia nitrogen, potassium ions and COD from wastewater simultaneously, adapt to different wastewater concentrations and conditions, and has significant advantages in comprehensive treatment performance.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the 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 treating wastewater from the co-production of phosphate fertilizer and flame retardant, characterized in that, Includes the following steps: S1, adjusts the pH of the raw water to form conditioned wastewater; S2, Add a compound functional agent to the conditioned wastewater in a single application at a dosage of 8 g / L to 25 g / L. The agent consists of the following components: Zirconia hydroxya 15wt%~25wt%, magnesium oxide 20wt%~30wt%, modified zeolite 35wt%~50wt%, PFS 5wt%~10wt%, CPAM 0.5wt%~1.5wt%, total 100%; S3, use gradient stirring for synergistic reaction for 13min~20min. The gradient stirring is in two stages, with the stirring speed in the first stage being greater than that in the second stage. S4, allow to settle and obtain the supernatant and the bottom sludge.

2. The method for treating wastewater from the co-production of phosphate fertilizer and flame retardant according to claim 1, characterized in that, In S1, the pH is adjusted to 8.0–9.

2.

3. The method for treating wastewater from the co-production of phosphate fertilizer and flame retardant according to claim 1, characterized in that, In S2, the modified zeolite is acid-modified clinoptilolite.

4. The method for treating wastewater from the co-production of phosphate fertilizer and flame retardant according to claim 3, characterized in that, Acid-modified clinoptilolite is prepared through the following steps: Natural clinoptilolite is crushed to 100-120 mesh, soaked in hydrochloric acid at room temperature, washed with deionized water until neutral, and then dried.

5. The method for treating wastewater from the co-production of phosphate fertilizer and flame retardant according to claim 4, characterized in that, The solid-liquid ratio of natural clinoptilolite to hydrochloric acid is 1g:50ml, the concentration of hydrochloric acid is 0.8 mol / L ~ 1.2 mol / L, and the soaking time is 4h~6h.

6. The method for treating wastewater from the co-production of phosphate fertilizer and flame retardant according to claim 1, characterized in that, In S3, the first stage is stirring at 120 r / min to 150 r / min for 3 min to 5 min, and the second stage is stirring at 30 r / min to 50 r / min for 10 min to 15 min.

7. The method for treating wastewater from the co-production of phosphate fertilizer and flame retardant according to claim 6, characterized in that, In S4, the settling time is 20-30 minutes.

8. The method for treating wastewater from the co-production of phosphate fertilizer and flame retardant according to claim 1, characterized in that, In S4, the supernatant is either discharged directly after meeting the standards or sent to a subsequent advanced treatment unit for further processing.

9. The method for treating wastewater from the co-production of phosphate fertilizer and flame retardant according to claim 1, characterized in that, In S4, the main components of the bottom sludge are magnesium ammonium phosphate, zirconium-based precipitate, and potassium-loaded zeolite, which are rich in nitrogen, phosphorus, and potassium. The bottom sludge is dewatered and then processed into slow-release compound fertilizer.

10. The method for treating wastewater from the co-production of phosphate fertilizer and flame retardant according to claim 1, characterized in that, S1, S2, S3 and S4 are all conducted in the same pool.

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