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CN-122010299-A - Method for synchronously removing nitrate and sulfate in wastewater by using polybutyl butyrate

CN122010299ACN 122010299 ACN122010299 ACN 122010299ACN-122010299-A

Abstract

The invention discloses a method for synchronously removing nitrate and sulfate in wastewater by using polybutylece butyrate. According to the method, an up-flow denitrification biological filter is adopted, PBS is filled in the denitrification biological filter as a unique solid slow-release carbon source and a biological film carrier, wastewater is pumped in from the bottom of the reactor and flows upwards through a PBS filler layer, and denitrification reaction and sulfate reduction reaction are respectively carried out in different height intervals by utilizing biological films on the filler surface, so that nitrate and sulfate are synchronously removed. The invention utilizes the stable slow release performance and the carrier function of PBS, effectively reduces the carbon source competition of denitrifying bacteria and sulfate reducing bacteria through microbial function layering, has the advantages of low operation cost, no secondary pollution, excellent effluent quality, simple process and the like, and is suitable for the advanced treatment of nitrate-and sulfate-containing wastewater.

Inventors

  • LI YAN
  • HUANG ZHIHUA

Assignees

  • 南京理工大学

Dates

Publication Date
20260512
Application Date
20260323

Claims (7)

  1. 1. The method for synchronously removing nitrate and sulfate in wastewater by using polybutylece butyrate is characterized by comprising the following steps of: (1) Regulating the pH value of the wastewater containing nitrate and sulfate to be 7.5+/-0.2, supplementing a phosphorus source and trace elements, and ensuring the normal growth of microorganisms; (2) And (3) using an up-flow biological filter reactor, filling PBS (phosphate buffer solution) in the reactor as a unique solid slow-release carbon source and a biological film carrier, pumping the wastewater containing nitrate and sulfate prepared in the step (1) from the bottom of the reactor, and enabling the wastewater to flow upwards through a PBS filler layer under an anaerobic condition, and simultaneously carrying out denitrification reaction and sulfate reduction reaction by using biological films on the filler surface to realize synchronous removal of nitrate and sulfate.
  2. 2. The method according to claim 1, wherein in the step (1), the nitrate nitrogen concentration in the wastewater containing nitrate and sulfate is 25 mg/L to 50 mg/L and the sulfate concentration is 25 mg/L to 80 mg/L.
  3. 3. The method of claim 1, wherein in step (1), the phosphorus source is selected from potassium dihydrogen phosphate or sodium dihydrogen phosphate.
  4. 4. The method of claim 1, wherein in step (2), the particle size of the PBS is 3mm.
  5. 5. The method of claim 1, wherein in step (2), the hydraulic retention time is 4-8 Hours.
  6. 6. The method of claim 1, wherein in step (2), the PBS fill height is 40 cm or greater.
  7. 7. The method of claim 1, wherein in step (2), the PBS fill height is 60 cm or greater.

Description

Method for synchronously removing nitrate and sulfate in wastewater by using polybutyl butyrate Technical Field The invention belongs to the technical field of sewage treatment, and particularly relates to a method for synchronously removing nitrate and sulfate in wastewater by using polybutylene butyrate. Background With the increasingly strict water environment treatment standard, the deep denitrification of secondary effluent of urban sewage treatment plants has become a key link for slowing down water eutrophication. Because the secondary effluent generally shows low carbon nitrogen ratio (C/N < 3), the requirements of heterotrophic denitrifying bacteria cannot be met, and a carbon source must be additionally added as an electron donor to ensure the denitrification efficiency. The traditional external carbon source is mainly added by adopting small molecular liquid organic matters such as sodium acetate, methanol or ethanol and the like. Although the utilization rate of the carbon source is high, in practical engineering application, a plurality of limitations exist, namely firstly, the adding amount is difficult to be matched with the fluctuating water quality accurately, insufficient adding can lead to incomplete denitrification, excessive adding can easily cause out-of-standard organic matters (COD/TOC) to cause secondary pollution, secondly, the storage and conveying equipment of the liquid carbon source is complex, the operation and maintenance cost is high, part of the carbon source (such as methanol) has inflammable and explosive properties, and potential safety hazards exist. In recent years, denitrification processes utilizing solid slow-release carbon sources instead of liquid carbon sources have received widespread attention. Existing solid carbon sources are largely classified into natural biomass (e.g., corncob, straw, wood chips) and biodegradable polymers (BDPs, e.g., PBS, PCL, PLA). Although natural biomass is low in cost, its composition is complex, the release rate of organics is extremely unstable, and serious chromaticity and large amount of soluble organics (DOC) release are often associated at the initial stage of operation. In contrast, the synthetic polymer has excellent biodegradability, mechanical strength and stable carbon source slow release performance, can serve as an electron donor and a biomembrane carrier of microorganisms at the same time, and simplifies process operation. At present, sewage treatment is mostly carried out by adopting a direct filling mode, for example, polycaprolactone (PCL) (China patent application CN 105800791A) or polybutylene succinate (PBS) (China patent application CN 109019870A) is directly filled as a denitrification solid carbon source and a microorganism growth carrier, and denitrification is carried out under the condition of low carbon nitrogen ratio. However, the actual sewage (especially industrial waste water and part of urban tail water) often contains sulfate with a certain concentration. Under anoxic or anaerobic conditions, the denitrification process and the sulfate reduction process may interfere with each other by competing for the same carbon source. The presence of sulphate may lead to incomplete denitrification processes, to significant accumulation of nitrite nitrogen and to increased emissions of greenhouse gas nitrous oxide. Currently, few applications are explored for the simultaneous removal of nitrate and sulfate from wastewater using a slow-release carbon source. Disclosure of Invention The invention provides a method for synchronously removing nitrate and sulfate in wastewater by using polybutylece butyrate, which avoids exceeding of COD (chemical oxygen demand) of effluent caused by secondary pollution through slowly releasing organic matters and achieves the aim of synchronously removing nitrate and sulfate in wastewater. The technical scheme of the invention is as follows: the method for synchronously removing nitrate and sulfate in wastewater by using polybutylece butyrate comprises the following steps: (1) Regulating the pH value of the wastewater containing nitrate and sulfate to be 7.5+/-0.2, supplementing a phosphorus source and trace elements, and ensuring the normal growth of microorganisms; (2) And (3) using an up-flow biological filter reactor, filling PBS (phosphate buffer solution) in the reactor as a unique solid slow-release carbon source and a biological film carrier, pumping the wastewater containing nitrate and sulfate prepared in the step (1) from the bottom of the reactor, and enabling the wastewater to flow upwards through a PBS filler layer under an anaerobic condition, and simultaneously carrying out denitrification reaction and sulfate reduction reaction by using biological films on the filler surface to realize synchronous removal of nitrate and sulfate. Further, in the step (1), the concentration of nitrate nitrogen in the wastewater containing nitrate and sulfate is 25 mg/L-50 mg/L, and the