Tag Archives: Wastewater

Vortex layer device for decontamination of liquid pig and cow manure

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Livestock production generates large amounts of liquid manure, which may contain a variety of pathogenic microorganisms and helminth eggs. If such manure falls into the environment without preliminary treatment, it will cause epidemics among the local population. If there is no prompt response, the epidemics can spread to the neighboring towns and villages.

The microorganisms in liquid manure that can cause the greatest danger are infectious agents such as:

  • Salmonellosis;
  • Leptospirosis;
  • Brucellosis;
  • Anthrax and others.

Now the livestock farms use the following method for deteсting pathogenic microorganisms in liquid manure. The manure is kept in special containers for the incubation period (5 days) of the most dangerous pathogens. If during this time there was no outbreak, the manure can be placed in permanent storage, and used for composting. Otherwise it goes through a decontamination process.

The traditional methods do not always give the desired results. Therefore, GlobeCore offers the equipment for decontamination of liquid pig and cow manure: a vortex layer device (AVS).

The AVS regrinds manure particles to less than than 1 mm, destroys weed seeds, pathogens and helminths and their eggs.

Experimental studies confirm that the use of vortex layer device for disinfection of liquid manure:

  • Achieves complete decontamination and cancels manure quarantine period;
  • The manure can be used as fertilizer straight after treatment;
  • Ensures a high level of manure homogenization, reducing the costs of storage, and ease of loading and further use.

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.

Treating wastewater from electroplating plants

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Treating wastewater. Improving environmental safety through development of low-waste technologies, efficient treatment equipment, resource recovery wastewater treatment are the priority directions of the modern industry.

Natural water resources are becoming a critical problem of today, because of outdated industrial water supply processes, poor state of wastewater treatment plants and old wastewater treatment technologies. They all lead to aggravation of the environmental situation. While towns and settlements suffer from the lack of fresh water, industrial plants dump polluted industrial wastewater into the water bodies. One of the biggest sources of pollution are galvanic electroplating facilities. Their insufficiently treated galvanic wastewater pollutes waterways with thousands of tons of highly toxic heavy metals such as zinc, nickel, chromium, and others annually, considerably complicating the environmental situation.

One of the most dangerous is the wastewater containing toxic hexavalent chromium. Hexavalent chromium damages natural environment, poisons water, further contaminates the ecosystem, disrupting the ecological balance.

In order to protect the biosphere from chromium compounds electroplating wastewater is treated with electrocoagulation method, which simultaneously reduces the hexavalent chromium and sediments it in the form of hydroxides. The electrogenerated sediment sludge has a stable form that does not leak into the environment during prolonged storage or when used as a secondary raw material in construction, metallurgy and roadworks. Still, electrocoagulation method is rarely used because of its technological complexity and high cost.

Considering the abovementioned problem of treatment galvanic plant wastewater and the continuing search for new and more effective approaches, GlobeCore designed the AVS vortex layer devices that are successfully operated in production lines in various industries at the moment.

The intensifying factors in vortex layer devices are:

  • electrochemical factors, electromagnetic treatment with activation of substances;
  • dispersed phase;
  • geometric parameters and hydrodynamic factors that ensure intensive mixing of the processed media.

We conducted the experiment treating wastewater from an electroplating facility removing heavy metals with the AVS-100 (laboratory unit). The reducing agent used in the experiment was ferrous sulfate FeSO4. The reduction of trivalent and hexavalent chromium with the reagent was performed in an alkaline medium, introducing lime milk Ca(OH)2 into the water.

Because a reducing agent in an alkaline medium is iron(II) sulphate, there is no need to increase wastewater acidity. During the experiment, 10 mg of 10% iron sulfate solution was added into the  0.5 liters of wastewater.

The ferromagnetic particles for processing in the operating chamber of AVS were 20 mm long and 1.8 mm in diameter (total weight 200 g) The treatment duration was 3 seconds.

Table 1 shows the results of treating wastewater from an electroplating plant, removing heavy metals with the AVS-100 vortex layer device,  and comparing them with the maximum permissible concentrations according to the European Union standards.

Table 1

The results of removing heavy metals from electroplating wastewater with the AVS-100 vortex layer device.

№

Parameters

Value

Maximum

permissible concentration (European Union)

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 research leads to the following conclusions

1) Treating wastewater from electroplating facilities with the AVS-100 vortex layer device reduces the concentration of heavy metals to values ​​not exceeding the maximum permissible concentration for the European Union. A complete absence of nickel and hexavalent chromium in the treated water was achieved. It shows the future perspectives for vortex layer devices in countries with more stringent regulations for concentrations of hexavalent chromium and nickel.

2) The treatment of wastewater is instant and does not overuse the reagents.

3) Sediment settles quicker than when using stirring devices.

Biological wastewater treatment to remove nitrogen and phosphorus compounds

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Biological wastewater treatment. Wastewater treated with traditional biological methods contains large amounts of leftover biogenic substances (nitrogen and phosphorus compounds), which cause a lot of damage in natural water bodies.

The rapid growth of algae in the water causes secondary water pollution, intense coloration and reduction of oxygen concentration. Blooming water greatly complicates its use as drinking water for residences and industrial facilities. Therefore, the content of biogenic substances in wastewater is strictly limited.

There are many methods for wastewater treatment to remove biogenic substances: physico-chemical, biological, and chemical methods. The most efficient and inexpensive is the biological method for removing nitrogen and phosphorus compounds.

Biological purification of wastewater from nitrogen compounds is based on nitrification and denitrification. The essence of these processes is the oxidation of ammonia to nitrate (nitrification) and subsequent reduction of nitrates to nitrogen gas (denitrification). The nitrates containing oxygen reduce the amount of air needed for aeration of wastewater and, as a result, reduce the energy consumption.

The biological treatment of wastewater from phosphorus compounds is based on the ability of certain groups of bacteria (predominantly Acinetobacter) to remove significantly more phosphorus from the liquid phase in artificially created extreme temperature conditions (changing bacteria from anaerobic to aerobic). This process is also called “phosphorus absorption”.

Aerotanks can increase phosphorus removal rate by combining biological methods with chemical sedimentation.

Industrial wastewater treatment from lead

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Industrial wastewater. Wastewater containing lead is extremely toxic. This metal is hazardous and has toxic and mutagenic effects on living organisms.

It has an extremely negative effect on the human reproductive system. For these reasons, the presence of lead is strictly limited in the wastewater of industrial facilities. When industrial wastewater is discharged into municipal sewage systems, the maximum permissible discharge (MPD) of lead should not exceed 0.1-0.05 mg / dm3, and the discharge into waterways should be less than 0.03 mg / dm3.

Industrial wastewater does not always contain lead. Significant concentrations of lead come from the production of sliding bearings and crystal glass.

Such wastewater contains many different metals and pollutants that are difficult to extract. The wastewater from sliding bearings production contains heavy metals (copper, zinc, nickel, tin), a wide range of organic impurities, particularly alkylsulfonic acid and a mixture of surfactants. The wastewater from crystal glass manufacturing contains glass colloidal particles and glass grinding pastes, as well as zinc and organic compounds. Thus, the wastewater from these processes are characterized by significant fluctuations in the concentrations of contaminants and the pH value.

Lead ions could be precipitated with the help of reagents in water solution in the form of hydroxides, sulfides and carbonates. Since lead hydroxides have a significant solubility (S = 1,0-0,95 mg/dm3), it is recommended to precipitate them in less soluble compounds as basic carbonate or lead sulfide.

Modern chemical methods of wastewater treatment are characterized by high consumption of reagents, complex treatment facilities and long duration of the process.

GlobeCore offers the AVS vortex layer devices for the industrial wastewater purification from lead. They were developed in the 1960-1970s. Even then they showed excellent results in the intensification of different technological processes.

Experiments confirmed the efficiency of the AVS for purification of wastewaters of different origins, which was achieved due to a number of effects and processes occurring in the operating chamber of the unit: the impact of electromagnetic field, electrolysis, intensive mixing, acoustic impact etc. The chemical reactions, which in traditional equipment would last minutes or hours,  only last seconds or tens of seconds in the AVS.

The unit is compact and can be integrated into virtually any existing wastewater treatment line. With proper placement (serial or parallel) of multiple units, the processing rate is virtually unlimited.

Chemical Purification of Wastewater

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Chemical Purification of Wastewater. Water going into the sewage system must be processed to remove heavy metals and other hazardous contaminants. This purification requires a complex of measures.

Wastewater can be classified by origin:

  • industrial;
  • household;
  • precipitation (snow, ice etc).

Chemical purification of wastewater implies the use of special reagents which react the contaminants. Such reagents are chlorine, potassium permanganate, chlorine and sulfur acid, sodium hydroxide, ozone, lime etc.

Chemical purification often precedes biological purification. Let us look at chemical wastewater purification in mode detail.

Neutralization of wastewater implies bringing pH of the wastewater to 6.5-8.5. In practice this may be achieved by mixing acidic and basic wastewater, chemical introduction and filtration. Acidic water can absorb ammonia, basic wastewater can dissolve gases.

Oxidation is used for decontamination when removal of contaminants is not required. Some of the oxidants used are chlorine dioxide, calcium chloride, air oxygen, ozone and other substances.

The oxidation process make the wastewater less contaminated and allows to remove toxic substances. The most efficient oxidant is fluorude. However, this substance is rather aggressive, making it hard to use in large quantities. So in many cases chlorine is prefered as a means to remove hydrogen sulfide, cyanides, methyl-sulfuric compounds etc.

Electrolysis is the oxidation of wastewater by electrochemical methods. The latter are efficient in purification of wastewater, removing organic and inorganic substances.

Even when using well-known and proven methods, several problems remain: long duration of the process, large footprint required, high chemical consumption. Hence the need to improve process efficiency.

GlobeCore offers a solution: installation of vortex layer device into the water treatment systems.

The ferromagnetic particles located in the chamber of the AVS unit, intensively stir and mix the reagents in the chamber. Under the influence of the shocks and friction, the materials are broken down into colloidal particle sizes. The colloidal metal is good reduction agent. At the same time, electrolysis causes formation of hydrogen in the vortex layer. Both factors have significant influence on reduction of hexavalent chrome and other metals in wastewater. This ability of the vortex layer allows to reduce iron sulfide consumption, or even achieve complete reduction of hexavalent chrome due to colloid metal and hydrogen only. The process in the AVS occurs in fractions of second, making the process continuous. Intensive mixing of reagents and the influence of the EM field, as well as the dispersion of the product compounds causes the formed metal hydroxides to be more dispersed than materials obtained in mechanical agitators. Interestingly, increased dispersion of the sediment does not slow the process of settling. On the contrary, sedimentation of the solid particles after the AVS process occurs up to two times faster than in a mechanical agitator. This is due to the intensive magnetic influence on the suspension, which changes the interfacial tension on phase boundary.

An important feature of the vortex layer is the fact that after the processing, the chemical and physical properties change, which in turn changes the chemical activity of the resulting product.

Using a unit with mechanical agitators requires a lot of space and investment. The duration of a purification cycle in this method can be 30 to 120 minutes. A system based on the AVS vortex layer device to decontaminate wastewater by reducing chrome with chemical reduction agent in basic media and precipitation of the contaminants as metal hydroxides only includes vessels for iron sulfide and lime milk with portioning devices, the AVS vortex layer device and a filter or solid waste settling tank.

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.