Tag Archives: Review of Methods

Modern Electroplating Wastewater Neutralization

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Electroplating wastewater. Electroplating facilities and shops produce toxic solid waste in the form of ions of heavy metals, acids and alkalis that can cause water pollution. It is due to the electrochemical technology requiring large volumes of water.

Generally, the decontamination and neutralization of electroplating wastewater is performed by a special unit which uses reagent purification. Despite the mainstream use of this approach, it is not without flaws. Its drawback is ineffective wastewater treatment that leads to excess of unwanted substances in the water output. Other drawbacks of the reagent method are high reagent consumption and high salt content, which do not allow the water to return back into the cycle; it also requires large bulky equipment.

Therefore, scientists continue to search for new methods to improve the efficiency of existing technologies. A solution was found by GlobeCore in its vortex layer device (AVS). These devices were developed in the last century by Logvinenko. In his book “The Intensification of Technological Processes in a Vortex Layer Unit” he demonstrated the positive results obtained with the AVS in wastewater treatment. But the low capacity of the device precluded its mass introduction into the wastewater treatment industry, because a large industrial enterprise required many AVS units for neutralization of wastewater, until recently. The newly developed high-performance devices cover the necessary volumes of wastewater treatment.

The GlobeCore design department studied the effectiveness of the AVS for cleaning and neutralizing wastewater from electroplating facilities. The data is shown in the table below.

Heavy metal wastewater treatment from galvanizing plant using AVS 100

№

Parameter

Rating

Maximum concentration level (European Union legislation)

Before treatment

After treatment
1

рН

1,75

6,74

6,5-8,5
2

Fe, mg/l

9,7

2,77

2-20
3

Cu, mg/l

18,29

0,65

0,1-4
4

Ni, mg/l

5,8

<0,02 (not detected)

0,5-3
5

Cr+6, mg/l

19,08

<0,005 (not detected)

0,1-0,5

The use of the AVS-100 vortex layer device in wastewater treatment from electroplating plants reduces the concentration of heavy metals to values ​​not exceeding the maximum permissible concentration accepted in the European Union. It achieves complete absence of nickel and hexavalent chromium in the treated water and shows the possibilities of future use of the vortex layer devices in countries with more stringent demands for hexavalent chromium and nickel concentrations.

Wastewater treatment is immediate and does not require high expenditure of reagents. The sedimentation with the AVS occurs much faster than with a stirrer.

Removal of Phosphorus From Wastewater: a Review of Methods

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Removal of Phosphorus From Wastewater. Wastewater generated by the industry and agriculture in many cases contains large amounts of ammonium and phosphorus. Insufficient removal of these from wastewater is a source of contamination of ground and surface water and causes eutrophication of water bodies. Biogenic elements cause proliferation of cyanobacteria. Excessive activity of algae degrades operation of water intakes and fishing, reduces the hydraulic parameters of the flow (the speed of flow near the banks); algal bloom reduces the amount of solved oxygen, has a negative impact on flora and fauna and disrupts normal functions of natural ecosystems.

High level of phosphates in wastewater has been a problem in the last decade, when the content of phosphate has grown from 6-8 mg/liter to 20-25 mg/liter. The main source of phosphates in sewage is, statistically, household wastewater and various industries, which use many synthetic detergents.

The problem of removing phosphates from wastewater has no optimal solution at this time and requires more research. Biological treatment of wastewater cannot achieve the required degree of contaminant removal, while the physical and chemical methods, while offering good results, require significant investment and create the problem of processing sediment, which forms in the process of chemical treatment.

Removal of Phosphorus From Wastewater. The biological method of phosphorous compound removal is based on the metabolism of biological sludge. Certain amounts of phosphorus are required for the formation of living cells, as well as a medium of transfer of energy, used to accumulate nutrients in a cell. The method of thorough removal of biogenic elements from wastewater is based on a traditional biological treatment combining aerobic and anaerobic processes. The biological phosphorus removal is based on the ability of several bacteria to accumulate soluble orthophosphates in cell in the form of insoluble polyphosphate. Oxidation of previously accumulated organic substances occurs in the aerobic part of the cell, and the energy is used by the bacteria to consume orthophosphate from the environment and turn it into polyphosphate to repeat the cycle of cell growth. However, the insoluble forms of phosphorus may hamper purification, since such compounds, in their solid form, cannot be consumed by microorganisms, thus requiring filtration or settling of the wastewater before biological treatment.

If the content of phosphorus is high, it may not always be possible to remove biologically. Chemical methods are used in this case. Reagent selection depends on its availability and cost in the area. The place of mixing the chemical with wastewater is determined individually based on previous laboratory research and later testing of the results in industrial applications.