Efficient-nitrogen-and-phosphorus-removing and resource recycling technology and device for iron phosphate production wastewater

Abstract

The invention discloses an efficient-nitrogen-and-phosphorus-removing and resource recycling technology and device for iron phosphate production wastewater. According to the characteristics of the extremely-low pH value, the high concentration of pollutants such as nitrogen, phosphorus, sulfur and iron and the like of the iron phosphate production wastewater, based on analysis of the quality and the quantity of the production wastewater, the wastewater treatment and nitrogen and phosphorus resource recycling treating technology in which waste is controlled by waste is provided. The technology includes the steps that magnesium oxide serves as a pH-value regulating agent and a precipitating agent, different pollutants are removed in a stepping-and-grading mode, the characteristic that aging filtering-pressing concentrated water is rich in phosphorus is fully used, one part of the concentrated water serves as an absorbing agent of an ammonia nitrogen blowing-off unit, the other part of the concentrated water serves as a precipitating agent of the magnesium ammonium phosphate technology, waste is controlled by waste, and wastewater treating cost is greatly reduced. By means of the technology, nitrogen and phosphorus removing can be effectively achieved, and nitrogen and phosphorus resources are recycled in ammonium-phosphate and magnesium-ammonium-phosphate modes while wastewater pollution is solved. The technology is suitable for industry and agriculture wastewater containing high-concentration nitrogen and high-concentration phosphorus at the same time and particularly suitable for the iron phosphate production wastewater.

Description

technical field [0001] The invention relates to the technical field of water treatment, in particular to an efficient nitrogen and phosphorus removal and resource recovery process and equipment for ferric phosphate production wastewater. Background technique [0002] Lithium iron phosphate (LiFePO 4 ) is considered to be the most promising cathode material for lithium-ion batteries, and iron phosphate is its precursor. During the production of ferric phosphate, a large amount of acidic wastewater containing high concentrations of nitrogen, phosphorus, sulfur and iron will be produced. Nitrogen and phosphorus in wastewater are not only pollution factors that cause eutrophication of water bodies, but also highly valuable nutrients, especially phosphorus is a non-renewable precious resource. If this kind of production wastewater cannot be treated well, on the one hand, it will cause serious pollution to the environment and waste resources, and it will also damage the green ba...

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Problems solved by technology

[0008] Third, sodium hydroxide is used in most ammonia nitrogen stripping processes to adjust the pH value of wastewater, so that sodium ions are introduced into wastewater, which increases the salt content of wastewater. It needs to be combined with other processes such as membrane technology and three-effect evaporation technology to remove it from the water Removed, increasing the cost of wastewater treatment;

[0009] Fourth, the premise of forming magnesium ammonium phosphate precipitation is that there is a certain proportion of NH in water 4 + 、PO 4 3- , and Mg 2+ , when treating high-concentration ammonia-nitrogen wastewater, it is necessary to add a large amount of phosphate and precipitant, resulting in higher treatment costs of magnesium ammonium phosphate precipitation method, which hinders practical application

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