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Electrochemical method for recycling low-concentration nitrogen and phosphorus in wastewater in struvite form

A struvite and low-concentration technology, applied in the electrochemical field of low-concentration nitrogen and phosphorus, can solve the problems of cost increase and achieve the effect of saving added cost

Active Publication Date: 2021-06-25
FUJIAN NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

A MAC system is composed of a self-made cylindrical container, magnesium strips, titanium plates, resistors, and a multimeter, and the OH spontaneously generated by MAC is used - and Mg 2+ Provides Mg for struvite crystallization 2+ and alkaline environment, solve the problem of cost increase caused by the addition of magnesium sources and alkaline reagents in the traditional struvite crystallization process, and use the self-discharge process of MAC to obtain electrical energy

Method used

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  • Electrochemical method for recycling low-concentration nitrogen and phosphorus in wastewater in struvite form
  • Electrochemical method for recycling low-concentration nitrogen and phosphorus in wastewater in struvite form
  • Electrochemical method for recycling low-concentration nitrogen and phosphorus in wastewater in struvite form

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Embodiment 1

[0037] The structure of the experimental device in this embodiment is as follows: figure 1 shown.

[0038] Firstly, BMED was used to treat low concentration NH 4 + (2mmol / L) and PO 4 3- (1mmol / L) enriched and pumped to the MAC system (NH 4 + and PO 4 3- The initial concentration is 2 and 1mmol / L respectively), when PO in the MAC system 4 3- When the concentration is higher than 3mmol / L, connect the positive and negative poles of the MAC system, when the PO in the MAC system 4 3- When the concentration is lower than 0.5mmol / L, then disconnect the positive and negative electrodes, when the PO in the MAC system 4 3- When the concentration rises above 3mmol / L again, connect the positive and negative electrodes of MAC again to form an intermittent treatment system. During the experiment, the HRT of BMED ammonia chamber and phosphoric acid chamber is 15min, and the current density of BMED is 4mA / cm 2 . After 199h, NH in waste water tank and MAC system 4 + and PO 4 ...

Embodiment 2

[0041] The structure of the experimental device in this embodiment is as follows: figure 1 shown.

[0042] In order to verify the anti-Ca of the coupled system 2+ interference capability, formulated with electrolyte Na 2 SO 4 Concentration 2mmol / L, NH 4 + 、PO 4 3- and Ca 2+ The simulated wastewater with concentrations of 10, 5.0, and 2.0mmol / L respectively has a current density of 4mA / cm in BMED 2 , under the conditions of HRT 15min in ammonia room and phosphoric acid room, after 124h, the system NH 4 + and PO 4 3- The removal rates were 95% and 76%, respectively, and the wastewater tank Ca 2+ The removal rate was 83%, and the struvite with a purity of 89.1% and electric energy with an output power of 2.39±0.85mW were obtained in the MAC system. X-ray diffraction (XRD), electron microscopy energy spectrum analysis (SEM-EDS) analysis of precipitation obtained from the MAC system, precipitation obtained from the ammonia chamber and commercial struvite, and the outpu...

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Abstract

The invention discloses an electrochemical method for recycling low-concentration nitrogen and phosphorus in wastewater in a struvite form, which comprises the following steps: connecting a double-strike membrane electrodialysis system with a magnesium-air battery system in series, and separating, enriching and concentrating NH4 < + > and PO4 < 3-> in the wastewater by using the double-strike membrane electrodialysis system, adopting a peristaltic pump to pump the enriched NH4 < + > and PO4 < 3-> to the magnesium-air battery system for reaction with Mg < 2 + > spontaneously generated by the magnesium-air battery system to generate struvite, meanwhile, reacting OH <-> generated by a bipolar membrane with Ca < 2 + > enriched by bipolar membrane electrodialysis to generate Ca (OH) 2 sediment, removing Ca (OH) 2 through filtering, so that the influence of Ca < 2 + > on the purity of the struvite is reduced, and meanwhile electric energy is obtained. According to the invention, struvite with the purity of 86.2% can be recovered from low-concentration NH4 < + > (2 mmol / L) and PO4 < 3-> (1 mmol / L) wastewater, and electric energy with the output power of 3.56 + / -0.37 mW is obtained. The struvite with the purity of 89.1% can be recycled from wastewater with the initial concentrations of NH4 < + >, PO4 < 3-> and Ca < 2 + > being 10 mmol / L, 5.0 mmol / L and 2.0 mmol / L respectively, and electric energy with the output power being 2.39 + / -0.85 mW is obtained.

Description

technical field [0001] The invention relates to the field of wastewater treatment, in particular to an electrochemical method for recovering low-concentration nitrogen and phosphorus in wastewater in the form of struvite. Background technique [0002] Nitrogen and phosphorus have become the main pollution indicators of surface water in my country, and their discharge often causes pollution events such as "algae bloom" and "red tide", which have caused great harm to the environment, economy and human health. On the other hand, nitrogen and phosphorus are important elements necessary for all living organisms and play a very important role in cell life activities. In recent years, with the global economic development and population increase, the demand for nitrogen and phosphorus has been increasing. However, phosphate rock is a non-renewable resource with limited reserves and extremely uneven distribution around the world. Compared with phosphorus, nitrogen resources are mor...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F1/469C02F1/42C02F101/10C02F101/16
CPCC02F1/4693C02F1/42C02F2101/10C02F2101/16C02F2001/422C02F2001/425
Inventor 刘耀兴吴晓云戴丽萍丁建国柯雄陈日耀
Owner FUJIAN NORMAL UNIV
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