Integrated nitrogen and phosphorus recovery device in struvite method

Abstract

The invention discloses an integrated nitrogen and phosphorus recovery device in a struvite method, which relates to the field of environmental engineering water treatment and is a reactor for treating nitrogen and phosphorus-containing wastewater in a physicochemical method. Substances nitrogen and phosphorus in the wastewater are removed in a magnesium ammonium phosphate (struvite) form, and the substances are recovered and reused. The reaction device is in an integrated form, which comprises a precipitation zone, a mixing reaction zone, a crystal growth zone and a crystal trapping and water discharging zone from bottom to top sequentially, the mixing reaction zone is provided with a first-grade aerator, which is mainly a wastewater and reagent fully mixing and reacting zone; the crystal growth zone is provided with a second-grade aerator, which is mainly a struvite growth zone; in the precipitation zone, large-grain struvite crystals are mainly precipitated; and the crystal trapping and water discharging zone recovers the struvite crystals by a filter screen. In addition, the device uses external reflux to reinforce and to control the supersaturated rate of the struvite reaction, thus promoting the crystal growth. The device has simple technological process and has the advantages of short hydraulic retention time, high nitrogen and phosphorus recovery efficiency, high recovery pureness, little occupied area, low operation and maintenance cost and the like.

Description

technical field [0001] The invention belongs to the field of environmental engineering water treatment, and relates to a reaction device for treating wastewater containing nitrogen and phosphorus by physical and chemical methods, in particular to a device for recovering nitrogen and phosphorus in sewage by crystallization of magnesium ammonium phosphate (struvite). Background technique [0002] rich in PO 4 3- -P and NH 4 + -N wastewater is an important cause of water eutrophication. This kind of wastewater has a wide range of sources and a large displacement, and its pollution cannot be ignored. At the same time, phosphorus is a very important non-renewable resource. According to estimates from the United States Geological Survey (USGS), the reserves of phosphorus rock resources on the earth can only last for 90 years. However, in my country's phosphate rock reserves, the impurity content is low, and the high-grade phosphate rock is expected to be mined in the next 10 ...

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Problems solved by technology

However, there are also some shortcomings: ①The fluidized bed reaction device is usually equipped with external seed crystal feeding equipment or a struvite carrier packing stripping separator outside the reactor, which increases the complexity of the device structure and the investment in supporting equipment. more, the difficulty of operation increases; ②The sedimentation tank reaction device usually uses struvite to settle to the bottom of the reactor, and it is regularly removed

The actual wastewater contains a large amount of suspended solids and organic particles. During the struvite precipitation process, these particles will be caught by nets, which will increase the impurity content in the sediment and increase the trouble of subsequent recycling; ③The crystallization reactor device usually has a complex structure and can High consumption, complex operation process, and few applications; ④ When the supersaturation of the solution is large, struvite crystallizes in a short time to form fine particles, which are easily lost from the effluent, reducing the struvite recovery rate to about 60% ~70%; ⑤Struvite is easy to scale, and many reactors have significant wall hanging phenomenon at present, which seriously affects the recovery efficiency of struvite, and reduces the effective volume of the reactor, reducing the efficiency of the reactor

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