AU2020101669A4 - Resource-based process for simultaneously recovering nitrogen and phosphorus from anaerobic digested sludge - Google Patents
Resource-based process for simultaneously recovering nitrogen and phosphorus from anaerobic digested sludge Download PDFInfo
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- AU2020101669A4 AU2020101669A4 AU2020101669A AU2020101669A AU2020101669A4 AU 2020101669 A4 AU2020101669 A4 AU 2020101669A4 AU 2020101669 A AU2020101669 A AU 2020101669A AU 2020101669 A AU2020101669 A AU 2020101669A AU 2020101669 A4 AU2020101669 A4 AU 2020101669A4
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- phosphorus
- nitrogen
- digested sludge
- sludge
- anaerobic
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/121—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering
- C02F11/122—Treatment of sludge; Devices therefor by de-watering, drying or thickening by mechanical de-watering using filter presses
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/14—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents
- C02F11/143—Treatment of sludge; Devices therefor by de-watering, drying or thickening with addition of chemical agents using inorganic substances
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/105—Phosphorus compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/16—Nitrogen compounds, e.g. ammonia
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Treatment Of Sludge (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses a resource-based process for simultaneously recovering nitrogen and
phosphorus from anaerobic digested sludge, which comprises the following steps: (1)
dissolving phosphorus in digested sludge with sulfuric acid solution; (2) carrying out solid
liquid separation on the acid dissolved product obtained in the step (1) through plate and frame
press filtration; (3) a cation exchange resin is added to the pressure filtration liquid obtained in
the step (2) to remove metal impurities and filter to obtain the filtrate; (4) adding magnesium
salt to the filtrate obtained in the step (3), and adjusting pH to form struvite crystals and
recovering them. According to the invention, phosphorus in the anaerobic digested sludge is
released into biogas slurry through acid dissolution, then metal impurities are removed, and
finally struvite crystals are formed by adjusting pH value with wastes, so that efficient recovery
of nitrogen and phosphorus in the anaerobic digested sludge is synchronously realized.
High solid anaerobic Biogas slurry with high
digested sludge ammonia nitrogen but
low phosphorus
Acid soluble Struvitecrystal
Solid-liquid Ion exchange Biogas slurry with high
separation impurity removal nitrogen andphosphorus
FIG, 1
Description
High solid anaerobic Biogas slurry with high digested sludge ammonia nitrogen but low phosphorus
Acid soluble Struvitecrystal
Solid-liquid Ion exchange Biogas slurry with high separation impurity removal nitrogen andphosphorus
FIG, 1
Resource-based process for simultaneously recovering nitrogen and phosphorus from anaerobic digested sludge
[01] The invention belongs to the technical field of sludge recycling, in particular to a recycling process for synchronously realizing nitrogen and phosphorus recovery in anaerobic digested sludge.
[02] Phosphorus is one of the essential nutrients for all organisms. Due to its limited and non-renewable nature, phosphorus resource recovery has become a strategic demand for global sustainable development. About 1.3 million tons of phosphorus enter sewage treatment plants through sewage every year, which is equivalent to 15%-20% of the global phosphorus demand. In order to prevent eutrophication, more than 90% of phosphorus in the final sewage is transferred to sludge. Therefore, sludge has become an important source of phosphorus recovery.
[03] Considering the pollution properties of sludge, phosphorus-rich sludge cannot be directly used as phosphate fertilizer. Generally, phosphorus in sludge is released to the liquid phase before subsequent recycling. Realizing phosphorus recovery in the process of sludge treatment and disposal is the development trend of sludge harmless and recycling. Anaerobic digestion is one of the most commonly used sludge treatment methods in the world at present. During anaerobic digestion, a large amount of ammonia nitrogen is released, but the phosphorus release rate is low. Therefore, the molar ratio of nitrogen and phosphorus in biogas slurry is relatively high, and most ammonium nitrogen cannot be recovered and needs subsequent treatment. Improved technologies with anaerobic digestion as the core, such as sulphate addition and pH adjustment, have improved the release of phosphorus in sludge to a certain extent, but their inhibition on methane production limits the popularization and application of this technology. Based on this, improving the release of phosphorus from anaerobic digested sludge and simultaneously recovering ammonia nitrogen from biogas slurry are effective means to maximize the recovery of sludge resources.
[04] The invention aims to provide a recycling process for synchronously realizing the recovery of phosphorus and nitrogen in anaerobic digested sludge, which mainly solves the contradiction between the low release efficiency of phosphorus and the high concentration of ammonia nitrogen in biogas slurry in the anaerobic digestion process of the sludge at present, and realizes the technological effect of maximizing the recovery of sludge resources.
[05] In order to achieve the above purpose, the invention provides the following technical scheme:
[06] The invention relates to a resource recovery process for synchronously realizing the recovery of nitrogen and phosphorus in anaerobic digested sludge, which comprises the following specific steps:
(1) taking anaerobic digested sludge for acid dissolution to obtain acid dissolution products;
(2) carrying out plate and frame press filtration on the acid dissolved product obtained in the step (1) to realize solid-liquid separation, and respectively obtaining mud cake and press filtrate;
(3) adding cation exchange resin to the pressure filtrate obtained in the step (2), removing metal impurities, and filtering to obtain filtrate;
(4) adding magnesium salt to the filtrate obtained in the step (3), and adjusting pH to form struvite precipitate for recovery.
[07] As a preferred technical scheme, in the step (1), the anaerobic digested sludge is the high-solid anaerobic digested sludge that is anaerobic digested after dewatering the primary sludge and the excess sludge. The solid content rate is 10% %.
[08] As a preferred technical scheme, in the step (1), sulfuric acid is used for acid dissolution, the concentration of sulfuric acid is 2-4 mol/L, the pH value is adjusted to pH < 2, and the reaction time is 0.5-1 h.
[09] As a preferred technical scheme, in the step (3), the cation exchange resin type is CER732, the solid-liquid ratio is controlled to be between 0.5 and 1 g/mL, and the mixture is stirred at 300 rpm for 30 min.
[010] As a preferred technical scheme, in the step (4), the magnesium salt is MgCl2-6H20, and the Mg: P molar ratio in the filtrate is (1.2-1.4): 1 after the MgCl26H20solution is added.
[011] As a preferred technical scheme, in the step (4), plant ash is used to adjust the pH of the filtrate to 8 to 10.
[012] The invention has the beneficial effects of:
[013] 1. The release rate of phosphorus in sludge is high. Although the amount of phosphorus released from sludge during anaerobic digestion is very small, most organophosphorus is converted into inorganic phosphorus. The inorganic phosphorus in the sludge is released into the biogas slurry in the form of phosphate ion by acid dissolution, greatly improving the release efficiency of phosphorus in sludge, and the release efficiency of phosphorus in sludge reaches more than 90%.
[014] 2. The separation efficiency of phosphorus and metal in biogas slurry is high. Acid dissolution of anaerobic digested sludge results in the co-dissolution of metal ions while a large amount of phosphorus is released. The metal ions, mainly including aluminum, iron, calcium, etc., affect the subsequent recovery of struvite precipitation. After adding cation exchange resin, more than 95% of metal impurities are removed.
[015] 3. Synchronous recovery of nitrogen and phosphorus resources. Ammonia nitrogen in biogas slurry with high solid content anaerobic digestion sludge is as high as 2000 mg/L (0.14 mol/L). Because of the low release rate of phosphorus in sludge during anaerobic digestion, the ratio of nitrogen and phosphorus is too high, and most ammonium nitrogen cannot be recovered and needs subsequent treatment. After acid dissolution, more than 90% of the phosphorus in the sludge is released, making the concentration of phosphorus in the biogas slurry reach 0.08-0.16 mol/L. The pH is adjusted by waste plant ash to form struvite precipitation and recovery, and the recovery rate of nitrogen and phosphorus is as high as over 90%.
[016] Examples
[017] High solid content anaerobic digestion sludge was taken with 10% solid content. The total phosphorus content was 28 mg/g TS, and the ammonia nitrogen concentration in biogas slurry was 1800 mg/L. Adding dilute sulfuric acid to the sludge, adjusting pH=2 and reacting for 0.5 h. When the release rate of phosphate in the sludge reached 90%, the acid dissolved product was filtered by plate and frame pressure, and the concentration of phosphate in the pressurized filtrate was 2520 mg/L. 100 ml of pressurized filtrate was added to 50 g of ion exchange resin and stirred at 300 rpm for min, and 80% of aluminum and iron in the final filtrate were removed. Finally, MgCl2-6H20 was added to the filtrate to make the molar ratio of Mg: P in the filtrate be 1.2. The pH was adjusted to 9 by plant ash, and the filtrate was stirred at 200 rpm for 20 min, and precipitated for 30 min to obtain supernatant liquid. The recovery rate of phosphate in supernatant liquid was 90%, and the removal rate of ammonia nitrogen was 60%.
[018] FIG. 1 is a schematic diagram of a resource-based process of an embodiment of the present invention.
Referring to FIG. 1, there is provided a resource-based process for simultaneously
recovering nitrogen and phosphorus from anaerobic digested sludge, which comprises
the following steps: (1) dissolving phosphorus in digested sludge with sulfuric acid solution; (2) carrying out solid-liquid separation on the acid dissolved product obtained in the step (1) through plate and frame press filtration; (3) a cation exchange resin is added to the pressure filtration liquid obtained in the step (2) to remove metal impurities and filter to obtain the filtrate; (4) adding magnesium salt to the filtrate obtained in the step (3), and adjusting pH to form struvite crystals and recovering them. According to the invention, phosphorus in the anaerobic digested sludge is released into biogas slurry through acid dissolution, then metal impurities are removed, and finally struvite crystals are formed by adjusting pH value with wastes, so that efficient recovery of nitrogen and phosphorus in the anaerobic digested sludge is synchronously realized.
[019] The invention aims to provide a recycling process for synchronously realizing the recovery of phosphorus and nitrogen in anaerobic digested sludge, which mainly solves the contradiction between the low release efficiency of phosphorus and the high concentration of ammonia nitrogen in biogas slurry in the anaerobic digestion process of the sludge at present, and realizes the technological effect of maximizing the recovery of sludge resources.
[020] In order to achieve the above purpose, the invention provides the following technical scheme:
[021] The invention relates to a resource recovery process for synchronously realizing the recovery of nitrogen and phosphorus in anaerobic digested sludge, which comprises the following specific steps:
(1) taking anaerobic digested sludge for acid dissolution to obtain acid dissolution products;
(2) carrying out plate and frame press filtration on the acid dissolved product obtained in the step (1) to realize solid-liquid separation, and respectively obtaining mud cake and press filtrate;
(3) adding cation exchange resin to the pressure filtrate obtained in the step (2), removing metal impurities, and filtering to obtain filtrate;
(4) adding magnesium salt to the filtrate obtained in the step (3), and adjusting pH to form struvite precipitate for recovery.
[022] As a preferred technical scheme, in the step (1), the anaerobic digested sludge is the high-solid anaerobic digested sludge that is anaerobic digested after dewatering the primary sludge and the excess sludge. The solid content rate is 10% %.
[023] As a preferred technical scheme, in the step (1), sulfuric acid is used for acid dissolution, the concentration of sulfuric acid is 2-4 mol/L, the pH value is adjusted to pH < 2, and the reaction time is 0.5-1 h.
[024] As a preferred technical scheme, in the step (3), the cation exchange resin type is CER732, the solid-liquid ratio is controlled to be between 0.5 and 1 g/mL, and the mixture is stirred at 300 rpm for 30 min.
[025] As a preferred technical scheme, in the step (4), the magnesium salt is MgCl2-6H20, and the Mg: P molar ratio in the filtrate is (1.2-1.4): 1 after the MgCl26H20solution is added.
[026] As a preferred technical scheme, in the step (4), plant ash is used to adjust the pH of the filtrate to 8 to 10.
[027] The invention has the beneficial effects of:
[028] 1. The release rate of phosphorus in sludge is high. Although the amount of phosphorus released from sludge during anaerobic digestion is very small, most organophosphorus is converted into inorganic phosphorus. The inorganic phosphorus in the sludge is released into the biogas slurry in the form of phosphate ion by acid dissolution, greatly improving the release efficiency of phosphorus in sludge, and the release efficiency of phosphorus in sludge reaches more than 90%.
[029] 2. The separation efficiency of phosphorus and metal in biogas slurry is high. Acid dissolution of anaerobic digested sludge results in the co-dissolution of metal ions while a large amount of phosphorus is released. The metal ions, mainly including aluminum, iron, calcium, etc., affect the subsequent recovery of struvite precipitation. After adding cation exchange resin, more than 95% of metal impurities are removed.
[030] 3. Synchronous recovery of nitrogen and phosphorus resources. Ammonia nitrogen in biogas slurry with high solid content anaerobic digestion sludge is as high as 2000 mg/L (0.14 mol/L). Because of the low release rate of phosphorus in sludge during anaerobic digestion, the ratio of nitrogen and phosphorus is too high, and most ammonium nitrogen cannot be recovered and needs subsequent treatment. After acid dissolution, more than 90% of the phosphorus in the sludge is released, making the concentration of phosphorus in the biogas slurry reach 0.08-0.16 mol/L. The pH is adjusted by waste plant ash to form struvite precipitation and recovery, and the recovery rate of nitrogen and phosphorus is as high as over 90%.
[031] Examples
[032] High solid content anaerobic digestion sludge was taken with 10% solid content. The total phosphorus content was 28 mg/g TS, and the ammonia nitrogen concentration in biogas slurry was 1800 mg/L. Adding dilute sulfuric acid to the sludge, adjusting pH=2 and reacting for 0.5 h. When the release rate of phosphate in the sludge reached 90%, the acid dissolved product was filtered by plate and frame pressure, and the concentration of phosphate in the pressurized filtrate was 2520 mg/L. 100 ml of pressurized filtrate was added to 50 g of ion exchange resin and stirred at 300 rpm for min, and 80% of aluminum and iron in the finalfiltrate were removed. Finally, MgCl2-6H20 was added to the filtrate to make the molar ratio of Mg: P in thefiltrate be 1.2. The pH was adjusted to 9 by plant ash, and the filtrate was stirred at 200 rpm for 20 min, and precipitated for 30 min to obtain supernatant liquid. The recovery rate of phosphate in supernatant liquid was 90%, and the removal rate of ammonia nitrogen was 60%.
[033] Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms, in keeping with the broad principles and the spirit of the invention described herein.
[034] The present invention and the described embodiments specifically include the best method known to the applicant of performing the invention. The present invention and the described preferred embodiments specifically include at least one feature that is industrially applicable
Claims (6)
1. A recycling process for synchronously realizing the recovery of nitrogen and phosphorus in anaerobic digested sludge is characterized in that it comprises the following steps:
(1) taking anaerobic digested sludge for acid dissolution to obtain acid dissolution products;
(2) carrying out plate and frame press filtration on the acid dissolved product obtained in the step (1) to realize solid-liquid separation, and respectively obtaining mud cake and press filtrate;
(3) adding cation exchange resin to the pressure filtrate obtained in the step (2), removing metal impurities, and filtering to obtain filtrate;
(4) adding magnesium salt to the filtrate obtained in the step (3), and adjusting pH to form struvite precipitate for recovery.
2. The resource recovery process for synchronously realizing nitrogen and phosphorus recovery in anaerobic digestion sludge according to claim 1 is characterized in that in the step (1), the anaerobic digestion sludge is the primary sedimentation sludge of a sewage treatment plant, and after the excess sludge is dehydrated, the high solid content anaerobic digested sludge with anaerobic digestion has a solid content of 10%-20%.
3. The recycling process for synchronously realizing the recovery of nitrogen and phosphorus in anaerobic digested sludge according to claim 1 is characterized in that in the step (1), sulfuric acid is adopted for acid dissolution and the concentration of sulfuric acid is 2-4 mol/L. The pH value is adjusted to pH < 2, and the reaction time is 0.5-lh.
4. The resource recovery process for simultaneously realizing nitrogen and phosphorus recovery in anaerobic digested sludge according to claim 1 is characterized in that in the step (3), the cation exchange resin type is CER732, the dosage solid-liquid ratio is controlled to be between 0.5 and 1 g/mL, and the mixture is stirred at 300 rpm for 30 min.
5. The resource recovery process for simultaneously realizing the recovery of nitrogen and phosphorus in anaerobic digested sludge according to claim 1 is characterized in that in the step (4), the magnesium salt is MgCl2-6H20, and the Mg: P molar ratio in the filtrate is (1.2-1.4): 1 after adding the MgC2-6H20 solution.
6. The resource recovery process for synchronously realizing nitrogen and phosphorus recovery in anaerobic digested sludge according to claim 1 is characterized in that in the step (4), plant ash is used to adjust the pH of filtrate to 8-10.
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| AU2020101669A AU2020101669A4 (en) | 2020-08-05 | 2020-08-05 | Resource-based process for simultaneously recovering nitrogen and phosphorus from anaerobic digested sludge |
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| AU2020101669A AU2020101669A4 (en) | 2020-08-05 | 2020-08-05 | Resource-based process for simultaneously recovering nitrogen and phosphorus from anaerobic digested sludge |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113501651A (en) * | 2021-09-13 | 2021-10-15 | 江苏鹏飞集团股份有限公司 | Sludge drying and filter pressing device |
| CN113880379A (en) * | 2021-10-29 | 2022-01-04 | 河北地势坤环保工程有限公司 | Composite bottom mud modifier and production process thereof |
| CN114291803A (en) * | 2021-12-28 | 2022-04-08 | 常州市深水江边污水处理有限公司 | Method for recovering phosphorus resources in municipal excess sludge |
| CN114315076A (en) * | 2021-12-30 | 2022-04-12 | 苏州嘉济智慧环境科技有限公司 | Method for producing acid and supplying carbon by anaerobic co-fermentation of municipal sludge and kitchen waste |
-
2020
- 2020-08-05 AU AU2020101669A patent/AU2020101669A4/en not_active Ceased
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113501651A (en) * | 2021-09-13 | 2021-10-15 | 江苏鹏飞集团股份有限公司 | Sludge drying and filter pressing device |
| CN113501651B (en) * | 2021-09-13 | 2021-11-16 | 江苏鹏飞集团股份有限公司 | Sludge drying and filter pressing device |
| CN113880379A (en) * | 2021-10-29 | 2022-01-04 | 河北地势坤环保工程有限公司 | Composite bottom mud modifier and production process thereof |
| CN114291803A (en) * | 2021-12-28 | 2022-04-08 | 常州市深水江边污水处理有限公司 | Method for recovering phosphorus resources in municipal excess sludge |
| CN114315076A (en) * | 2021-12-30 | 2022-04-12 | 苏州嘉济智慧环境科技有限公司 | Method for producing acid and supplying carbon by anaerobic co-fermentation of municipal sludge and kitchen waste |
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