Tag Archives: Biological wastewater treatment

Activation of Catalysts for Carbon Nanomaterial Production

The most important stage of preparing heterogeneous catalysts for carbon nanomaterial (CNM) is their activation, which is understood as a complex of physical influence on the catalytic material, which allows to significantly increase the efficiency of nanostructure synthesis.

This can be achieved by researching mechanical (dispersion) and physical (electromagnetic and ultrasonic) activation methods.

One of the most important factors defining catalyst efficiency is its granulometric composition. It is known that reduction of the particle size (less than 3 nanometers) causes capsulation inside nanotubes, while increasing it above 25 nanometers leads to uneven size distribution and defects in nanotubes. This is due to the fact the using large catalyst particles (25 to 100 nanometers) prevents carbon scattering from the surfaces where hydrocarbon decay occurs to the surfaces where carbon is deposited; as a consequence, no CNM growth occurs on such particles. Therefore, it is important to define reasonable catalyst particle size, as well as dispersion and classification methods.

Note that dispersion of catalyst microparticles causes both the reduction of size and the changes in the microstructure, e.g. destruction and reduction of pore depth, increasing the boundary of nano-seeds, where graphitized carbon is deposited.

Catalyst was activated in a drum mill and an electromagnetic vortex layer device (AVS). The distinguishing characteristic of the vortex layer in electromagnetic units is the multitude of high frequency and strength shocks, as well as friction, which not only break solid particles, but significantly activate their surfaces due to the deformation of their crystalline lattice. Enormous energy is concentrated in a volume of this process, which direct influence on the material. The influence is so high that it changes the structure as deeply as the atom’s valency shells. The process causes deep changes in the structure of the material.

Mean energy conducted to a volume of the vortex layer reaches 103 kW/m3. This is several orders of magnitude higher than in vibration mills, for instance. Besides, the energy is localized in certain areas, e.g. in the locations where the ferromagnetic particles collide, where mean power reaches even higher.

The electromagnetic vortex layer unit consisted of a process section and a control section, connected by oil tubes and a power cable. The process section consisted of a support, an enclosure, an induction coil for the rotating electromagnetic field, and a detachable operating chamber.

The catalyst activation process was performed with 1…1.5 mm by 10…15 mm PVC encapsulated ferromagnetic particles.

The chamber was loaded with 0.120 kg of the catalyst and 0.060 kg of ferromagnetic particles; retention time varied from 5 to 60 seconds. The granulometric composition of the Ni/MgO catalyst after the dispersion was done by fractionating sieve analysis. The catalyst after activation was separated into fractions and used for CNM synthesis under a unified method of testing various catalyst samples.

The results of the experiment show that the optimal duration time for the finest grinding constitutes 10 seconds, with initial catalyst particle size of 500 micron.

The observed increase of catalyst particle size after 10 or more seconds of dispersion is apparently due to the fact that with time the particles accumulate sufficient energy for spontaneous aggregation.

The analysis of the influence of the catalyst size composition on the mean output of CNM leads to the conclusion: the output increases in inverse proportion to catalyst particle size. This is due to the increased active surface of the catalyst. The experiments demonstrated that the actual method of catalyst dispersion has no significant influence on nanomaterial output.

Modern Electroplating Wastewater Neutralization

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 magnetic mill (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



Maximum concentration level (European Union legislation)

Before treatment

After treatment







Fe, mg/l





Cu, mg/l





Ni, mg/l


<0,02 (not detected)



Cr+6, mg/l


<0,005 (not detected)


The use of the AVS-100 magnetic mill 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.

Livestock Farm Wastewater Treatment

Farm Wastewater Treatment. The degree of contamination of wastewater is characterized by the amount of mineral, organic and bacterial materials solved or unsolved in the water.

Wastewater is treated by mechanical, chemical, physical or biological methods.

Biological processes involve oxidation of organic substances in waste water in the form of suspensions, colloids and solutions by microbes.

There are two type of facilities for biological treatment of wastewater. The first type are facilities where biological treatment occurs in conditions similar to natural (sewage farms, absorption fields and biological sewage ponds. The second type are facilities with artificial conditions (biological filters and aerotanks). The treatment process in the first group occur slowly, with the oxygen in the soil and in the water and due to the metabolism of microbes, which oxidize organic contaminants. Treatment is much more intensive in the second group of facilities.

Since the requirements to the degree of wastewater treatment keep growing, and biological treatment alone may not always be able to meet them, livestock farm wastewater must be processed additionally.

Treatment of such wastewater is a complicated process. It requires thorough consideration of the capabilities of each facility on a case by case basis. Methods used for such treatment are biological (biological ponds with natural or biological aeration) and physical and chemical (flotation, sorption and ozonation).

Every milliliter of livestock farm wastewater contains 10^8 of aerobic and up to 10^7 of anaerobic bacteria, therefore thorough decontamination must precede release of the water into water bodies or into sewage farms.

Biological wastewater treatment facilities are available to large livestock farms, but even their wastewater does not meet the purity requirements for release into water bodies. Purification of such wastewater is quite complicated. It requires two problems to be solved: technical and technological. The former occurs with pumping of wastewater and its mixing in tanks. The latter is related to the quality of processed water and the cost of its treatment. The cost of purifying highly concentrated wastewater from livestock farms with traditional treatment methods is defined by the energy cost of the process and the formation of large amounts of sludge.

Sometimes the problem of removing nitrogen and phosphorus from waste water arises.

Technical problems are solved by using modern equipment. For instance, for pumping of waste with high concentration of manure, hay or sand, submerged pumps with special wheels of various types are used.

The characteristics of wastewater must be taken into account, among them the concentration of suspended particles, abrasive particles, fibers etc.

For economical solution of mixing highly concentrated waste water, submerged mixers are used.

Aeration, the process of supplying oxygen to the biological processes, has always been problematic for livestock farm wastewater treatment. DUe to the high content of salts, organics and surfactants formed in the process of hydrolysis, the mass transfer of oxygen is 40% slower than in fresh water.

For a time, these problems were addressed by using ejector aerators with submerged pumps.

They have since been replaced by submerged pneumatic/mechanical aerators, which operate on the principle of atomizing bubbles with consecutive horizontal stirring of the sludge with a powerful stream generated by the mixer.

This results in formation of very small bubbles and high oxygen saturation.

Biological treatment of livestock wastewater is performed in two stages. Removal of nitrogen and phosphorus is not provided for in such facilities, as a rule. The high energy costs and a large amount of sludge is an unavoidable part of wastewater treatement.

The development of pneumatic and mechanical aerators and their capability of stirring without air facilitates the process of nitrodenitrification with periodic aeration without additional equipment, to set up the aeration process when oxygen is available and stirring when it is not.

The new technology is based on nitrodenitrification (a biological method of nitrogen removal) and anaerobic treatment of wastewater.

In the process of anaerobic purification, fatty acids are removed, hydrolysis of organic material occurs with formation of ammonium nitrogen. The result is the growth of pH to 7.6-7.9, with the formation of magnesium-ammonium-phosphate, which settles on the walls of pipelines. Up to 80-90% of phosphorus is removed.