Treatment method of heavy metal wastewater

Abstract

The invention discloses a treatment method of heavy metal wastewater. The treatment method of heavy metal wastewater comprises the following steps of: delivering heavy metal wastewater supernatant liquor subjected to pretreatment into an A3O biochemical reaction system comprising a hydrolytic acidification reaction tank, an oxygen-poor denitrification reaction tank, an oxygen-poor dephosphorization reaction tank and an activated sludge tank; delivering effluent into a heavy metal membrane reactor, adding obligate bacteria for degrading organic matters in the reactor; and refluxing the wastewater in the heavy metal membrane reactor at intervals into the oxygen-poor dephosphorization reaction tank. According to the treatment method, the A2O biochemical treatment process is replaced by the A3O biochemical treatment process, the reflux ratio is adjusted, and the effects of reducing chemical oxygen demand (COD) of the biochemical system, adsorbing heavy metal, denitrifying and dephosphorizing without increasing the hydraulic retention time, the tank volume and the project cost are strengthened; and besides, a secondary sedimentation tank is replaced by M-MBR, the concentration of activated sludge and the biochemical reaction rate are improved, the COD and BOD are further reduced, and the equipment and process are simple. The treatment method can be popularized and applied on a large scale.

Description

technical field [0001] The invention relates to a method for treating wastewater, in particular to a method for treating heavy metal wastewater. Background technique [0002] Heavy metals are one of the main pollutants in the water environment, which are extremely harmful to the natural environment, humans and animals. In order to reduce the harm of heavy metals to the environment, the state has implemented measures to raise the standard of sewage treatment and discharge of heavy metal wastewater, from the standard in Table 2 of the "Electroplating Pollutant Discharge Standard (GB21900-2008)" implemented in January 2008 to the standard in Table 3 . [0003] Through searching the technical development and patent disclosure in related fields, we found that A 2 The combination of O biochemical treatment and MBR membrane separation technology has some precedents in the treatment of heavy metal sewage, but there are some congenital deficiencies in varying degrees, such as: in t...

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Problems solved by technology

[0003] Through searching the technical development and patent disclosure in related fields, we found that A 2 The combination of O biochemical treatment and MBR membrane separation technology has some precedents in the treatment of heavy metal sewage, but there are some congenital deficiencies in varying degrees, such as: in the prior art, the activated sludge is returned to the hydrolysis acidification reaction tank, which makes nitric acid Salt enters the pool, destroying the hydrolysis and acidification state of the hydrolysis acidification reaction pool and reducing the subsequent phosphorus removal rate; and insufficient carbon sources will also lead to poor nitrogen and phosphorus removal effects in the biochemical system, and it is impossible to achieve the refractory heavy metals stipulated by the state. Full factor compliance of wastewater

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