WO2002058839A1

WO2002058839A1 - Method of sewage treatment and decontamination

Info

Publication number: WO2002058839A1
Application number: PCT/US2002/002122
Authority: WO
Inventors: Olexandr B. Zayika; Vasily P. Bakhar; Edward Levin
Original assignee: Water Works Global, Inc.
Priority date: 2001-01-25
Filing date: 2002-01-25
Publication date: 2002-08-01

Abstract

Sewage is treated and decontaminated with the use of a non-self maintained glow discharge, that will allow to increase average value of the strength of the operating impulse current up to 20A on every pair of the unlike electrodes (25, 26) at the voltage of no more than 500V, as well as to provide for adjustment of the average in time value of strength of an operating current, frequence and relative pulse duration to ensure specific conditions.

Description

Method of Sewage Treatment and Decontamination Field øf Ihe Invention

The proposed invention relates to the domain of the environmental control, namely to methods of treatment of aqueous mediums, and can be applied for sewage treatment in electrolytic and electrochemical production, petrochemical and other production, as well as for domestic sewage treatment, decontamination of any sewage and for extraction of precious metals from aqueous solutions- Background of the I-tyentioa

The most dangerous factors of sewage contamination are toxic and radioactive ions of heavy metals, organic and inorganic compounds, pathogenic and conditionally pathogenic microorganism.

There are known methods of water treatment, including with the purpose of purification and decontamination thereof, consisting in that a surface of a fluid medium is affected by an electric discharge, for example arc discharge (US, 5464513), corona discharge (WO, 98/09722), or glow discharge (RU, 2043969, 2043970, 2043971, 2043972, 2043973, 2043974, 2043975), the effect of which causes production of ions O^", O₂ ^" O₃ ^" OH^" H₂O^", peroxide H2P2 and super-oxide H₂O₃ in an aqueous medium. The said reagents interact with matters, contained in sewage, and have a destructive effect on microorganisms. The cofactors are also photo effect and ultraviolet rays.

There is a known method (US, 5464513) of sewage decontamination, consisting in a fluid treatment by a series of pulsed electrical arc discharges at a current strength of 30 A and a voltage of lO-50 W.

There is a known method (RU, 97117396) of water purification, consisting in treatment thereof by pulsed electric discharges at a voltage of 10 kN in an oxygen-containing gas medium. There is also a known method (RU, 1835161) of water purification, by treating dispersed into drops water by high-voltage electric discharges at a discharge voltage of 1 -35 kN. There is one more known method (RU, 1011545) of fluid decontamination by a high- voltage electric discharge at a voltage of 100-500 kN, and the surface layer of fluid therewith serves as an electrode.

However, high voltage (from 1 to 500 kV) is required for the accomplishment of all the methods described above.

The closest prior art of the invention are the methods of fluid treatment and decontamination with the aid of a glow discharge.

Thus, there is a known method (RU, 2043969) of fluid treatment by electrical glow discharge, produced at a current strength of 50-100 mA and a voltage of 0.5-2 kN above the surface of a treated fluid with the use of unlike electrodes, one of which is submerged in the fluid, and the electrode of reciprocal potential is in a gaseous atmosphere. The temperature in the glow discharge medium therewith is maintained below the boiling point of the treated fluid, the pressure is 50 Torr, and the fluid is fed in a stream 0.4-1.6 mm in depth.

However, this method is deficient in that it does not allow to treat a fluid at a current strength in excess of 1A and relatively low voltage of less than 500V, since with increase of the strength of current a strong heat-up of the electrodes occurs, and especially of those that are in a gaseous atmosphere, and that, in its turn, results in formation of an arc discharge and evaporation of the treated fluid.

Besides, this method does not provide for any adjustment of frequency and duty cycle of the operating current in the glow discharge medium.

It is a basic object of the invention to provide for the conditions, that allow to increase the amount of the applied energy per unit of a treated fluid per unit of the time of treatment.

Another object of the invention is to provide conditions for ionization, support and control of the operating discharge with the aid of additional ionizing (excitant) discharge, applied to the same unlike electrodes, with relatively low impulse operating current up to 5mA and relatively high voltage up to 10kV. One more object of the invention is to make provision for control of the impulse operating current value, clock frequency and duty cycle in the glow discharge medium, as well as to regulate value of the impulse operating current, clock frequency and impulse duration in the medium of additional ionization discharge . Summary of the Invention

These objects are accomplished by the provision of a method of sewage treatment and decontamination by effecting a treated fluid by an electric discharge, produced above the surface of the said fluid with the use of unlike electrodes, one of which is submerged in the said treated fluid, and the electrode of reciprocal potential is in a gaseous atmosphere, wherein, as claimed in the invention, the effect is produced by a non-self-maintained glow discharge.

The said non-self-maintained glow discharge, as claimed in the invention, is a discharge produced with the aid of a high-frequency impulse ionization voltage and featuring average in time strength of the operating current on every pair of unlike electrodes of 0.1-20 A, the voltage of no more than 500 V, the clock frequency of 0.1-100 kHz, and the duty cycle of at least 1.3. The non-self-maintained glow discharge is formed by simultaneous application to the said unlike electrodes of the operating pulse voltage of no more than 500 V with the clock frequency of 0.1-100 kHz, duty cycle no less than 1.3 , and the ionization high frequency (excitant) voltage of 2-10 kN, with average in time strength of current of 30-5000 μA and the pulse duration of 0.01-20 μs. During the treatment by the non-self-maintained glow discharge, the temperature in the discharge medium is maintained below the natural boiling point of the treated fluid, and the pressure is maintained at 30-250 Torr.

During the treatment by the non-self-maintained glow discharge, the said treated fluid is fed mainly in a turbulent flow 0.3-5 mm in depth. Since the basic operating factor, affecting the degree of the fluid treatment is the amount of the applied energy per unit of the treated fluid per unit of the time of treatment, therefore the basic adjustable parameters of the glow discharge used to treat the fluid is the average in time value of the operating impulse current at a constant voltage, clock frequency and duty cycle, and for ionization impulse current its value, clock frequency and impulse duration. The provision, made for regulation of the operatmg parameters, will allow to select the most favorable conditions for treatment of water featuring particular contamination, and to increase the treatment efficiency.

The ionization voltage of the impulse current provides for ionization of plasma of the non- self-maintained glow discharge, and the operating impulse current commands main modes of the fluid treatment in plasma of the non-self-maintained glow discharge. The ionization pulses provides for the conditions to form impulses of the operating current of the non-self-maintained glow discharge, as well as prevent formation of an arc discharge between the electrodes.

To increase efficiency of plasma formation, the non-self-maintained glow discharge is further affected by a magnetic field generated near unlike electrodes with the value of magnetic induction being at least 0.01 T (Tesla).

The average in time value of the operating impulse current, its clock frequency and duty cycle, depth of the treated fluid sheet are basic parameters affecting the efficiency of the fluid treatment.

That is why the ability to control this parameters directly during processing of sewage, permits to find the most suitable parameters for the highest effectiveness during experiments and industrial implementation on sewage treatment. Thus, a method as claimed in the invention is implemented as follows:

- an under-pressure (vacuum) medium is formed;

- a turbulent flow of a treated fluid 0.3-5 mm in depth is formed, which covers one of the unlike electrodes;

- simultaneously, an operating impulse voltage of no more than 500 N with a clock fre- quency of 0.1 -100 kHz, and duty cycles no less than 1 ,3 and an ionization impulse voltage of 2- 10 kV with impulse current featuring average value of strength of 30-5000 μA and a pulse duration of 0.01 -20 μs are applied to unlike electrodes;

- in the zone of the formed non-self-maintained glow discharge the pressure is maintained at 30-250 Torr, and the temperature is maintained below the natural boiling point of the treated fluid;

- additionally, a magnetic field with the value of magnetic induction being at least 0.01 T is established near the unlike electrodes;

- sewage is treated in the medium of the non-self-maintained glow discharge, with the operating impulse current with average in time value of strength 0.1-20 A on every pair of the unlike electrodes with the clock frequency of 0.1 -100 kHz and relative pulse duration of at least 1.3 at the operating voltage of no more, than 500 V.

The essence of the invention is that it is hereby proposed, that sewage be treated and decontaminated with the use of a non-self-maintained glow discharge, that will allow to increase average value of the strength of the operating impulse current up to 20A on every pair of the unlike electrodes at the voltage of no more than 500N as well as to provide for adjustment of the average in time value of strength of an operating current, frequency and relative pulse duration to ensure specific conditions.

Brief Description of the Drawings

A method as claimed in the invention is implemented with the aid of a device for sewage treatment and decontamination, which is figured on the following drawings:

Fig. 1 is a block diagram of the device for sewage treatment and decontamination;

Fig. 2 is a longitudinal sectional view of a reactor where a non-self-maintained glow discharge is induced;

Fig. 3 is a cross-sectional view of the said reactor taken along line A-A. Detailed Description of the Invention

A device for sewage treatment and decontamination (Fig. 1) comprises a reactor 1, where a non-self-maintained glow discharge is produced and proper treatment and decontamination of sewage occur, a reservoir 2 for accumulation of sewage before it is fed to the reactor 1 , a means providing for vacuum development in the reactor 1 and comprising a water-jet ejector 3 and a pump 4, that keeps the ejector 3 operating, a unit 5 for monitoring selected vacuum parameters in the reactor 1, a unit 6 for feeding fluid from the reservoir 2 into the reactor 1, units 7 and 8 for cooling the reactor 1 , a reservoir 9 for collection of a purified fluid connected with the reactor 1 , a pump 10 for pumping out the purified fluid from the reservoir 9, a filter 11 connected with the pump 10, an electrical power supply source 12 for energizing the reactor 1 and a means 13 providing control over and monitoring of operation of the entire device. The means 13 can be made, for example, as a processor. A device, as claimed in the invention, can be made with one reactor 1 or more. The reservoir 2 is equipped with a float valve 14, providing a required level of the treated fluid.

The unit 5 for monitoring the selected vacuum parameters in the reactor 1, comprises a pressure transmitter 15 connected with the reactor 1 and a controller 16 of the pressure transmitter 15, and a solenoid-operated valve 17.

A pipeline 18 connects the ejector 3 to the reactor 1 and the reservoir 9 for vacuum devel- opment therein.

The unit 6 for feeding fluid from the reservoir 2 into the reactor 1 comprises a coarse filter 19, a solenoid-operated valve 20 and a pipeline 21 connecting the reservoir 2 with the reactor 1.

The unit 7 for cooling the reactor 1 is essentially a jacket placed around the reactor 1 connected with the means (not specified on the drawing) for pumping a liquid coolant through the jacket. The unit 8 for cooling the reactor 1 comprises a heat exchanger 22, an oil pump 23 and means for cooling oil in the heat exchanger 22.

The means for cooling oil, in the heat exchanger 22, can be provided by cooled water. The pump 4 is connected to the ejector 3 by a pipeline 24. The pumps 4 and 10, the electric power supply source 12, the controller 16 of the pressure transmitter 15, and the solenoid-operated valve 17, the solenoid-operated valve 20, the oil pump 23 are connected with the control means 13 (the connection is not specified on the drawing).

The reactor 1 (Fig. 2) is made as a chamber and comprises a case 25 being an electrode, that is covered, during the operation, with the treated fluid. There are electrodes 26 installed in the case 25 of the reciprocal, relative to the electrode 25, potential, which are in a gaseous atmosphere during operation of the reactor 1, and a system 27 for cooling the electrodes 26. The reactor 1 is equipped with the means for delivering and forming a stream of the treated fluid, made, for example, as injectors 28. Magnets 29 are installed on the outer side of the case 25 opposite the electrodes 26 with the provision for the removal thereof. The electrodes 26 (Fig_ 3) are made of annular shape with through holes 30, connected with the cooling system 27, made as two coaxial pipes, connected with the unit 8 (Fig. 1) for cooling the reactor 1 by the feed and lateral pipelines (not specified on the drawing).

The magnets 29 are both the permanent magnets, and electromagnets, made of annular shape and installed with the provision for the removal thereof mar the unlike electrodes. The jet injectors 28 have mainly a tangential arrangement along a circle at an equal distance at an angle of 5-30 degrees relative to the horizontal plane of the reactor 1, and are connected by the pipeline 21 to the reservoir 2.

The case 25 being an electrode and the electrodes 26 are electrically connected to the electric power source 12. The electric power supply source 12 comprises sources of the operating impulse voltage and ionization impulse voltage, each being individually connected to the electrodes 25 and 26. The case 25, being an electrode, of the reactor 1 is made in a form of a hollow cylinder (tube) with the inside diameter from 25 up to 250 mm and the height from 150 up to 1500 mm. The case 25 is made of a material, having no catalytic effect on the treated fluid, and is installed spatially upright. The electrode 26 can comprise one or more electrode members. To treat and decontaminate large volumes of fluids, containing a heavy waste load, it is necessary to have a large surface area of the active electrode. Therefore, the electrode 26 can be a cluster electrode. The number of the members thereof is determined by the time required for the treated fluid to stay in the reaction zone, in order the selected efficiency of the process can be achieved. A separate conductor 31 connects every electrode 26 to the electric power supply source 12.

There is a galvanic isolation between the electrodes 26 and the case 25 (being an electrode) of the reactor 1 and between the electrodes proper, provided by dielectric hollow inserts 32 made of ceramics.

The electrodes 26 are installed so that they have a clearance of 4-20 mm, relative to the electrode 25.

The electrodes 26 are made of a metal, having a thermal conductivity of at least 100 W/(mK). The outside surface of the electrodes 26 is covered with a refractory metal, for example, tungsten or nickel-chromium alloy.

The magnets 29 are made so that to provide a magnetic field with a value of magnetic in- duction in the discharge zone of at least 0.01 T(Tesla).

The device, according to the invention, functions in the following manner:

In response to control signals of the control means 13 (a processor), a reduced atmospheric pressure from 30 up to 250 Torr (from 4_*10³ to 3.3*10⁴ Pa), i.e. vacuum, is developed in the case

25 of the reactor 1 with the aid of the water-jet ejector 3 through the pipeline 18. h this case, used as an operating fluid, which develops depression is sewage, subject to treatment, which is fed to the ejector 3 with the aid of the pump 4. While passing through the ejector 3, the water is oxygen- ated from air, since the ejector provides for vigorous mixing of the water and air. The selected vacuum parameters are monitored with the aid of the pressure transmitter 15, the controller 16 of the pressure transmitter 15, and the solenoid-operated valve 17. In so doing, the controller 16 of the pressure transmitter 15 digitizes data received from the pressure transmitter 15 and feeds this information to the processor 13.

Simultaneously, the liquid coolant is pumped through the unit 7, i.e. the cooling jacket of the reactor 1 , and the cooling transformer oil is pumped through the unit 8, connected with the cooling system 27, thus ensuring maintenance of the required temperature of the electrodes 25 and 26 and the treated water below the natural boiling point. After the selected vacuum value has been attained in the reactor 1 and the receiving reservoir 9, the solenoid-operated valve 20 opens in response to a control signal of the processor 13, and sewage is fed for treatment in a turbulent flow 0.3-5 mm in depth from the inlet reservoir 2 through the pipeline 21 and the injectors 28 into the reactor 1. The filter 19 therewith allows to prevent suspension particles in the treated fluid from getting on the injectors 28. After that, the operating impulse voltage of no more than 500 V with the clock frequency of 0.1-100 kHz and duty cycle no less than 1.3, and the ionization impulse voltage featuring the value of 2-10 kN the strength of 30-5000μA and the pulse duration of 0.01-20μs, are simultaneously applied to the electrodes 25 and 26, thus producing a non-self-maintained glow discharge with an adjustable operating current of 0.1-20 A, average in time value on every pair of the unlike electrodes, the voltage of no more than 500N the clock frequency of 0.1-lOOkHz and the duty cycle of at least 1.3.

Such conditions of producing the glow discharge, allow to implement the process at an average in time impulse current strength of up to 20 A and a voltage of no more than 500 V with the provision for adjustment of the clock frequency and duty cycle of the impulse current. The fluid is treated by the non-self-maintained glow discharge, in presence or in absence of a magnetic field. The fluid, treated by the non-self-maintained glow discharge, drains into the reservoir 9, wherefrom it is delivered to the filter 11 by the pump 10 for extraction of insoluble sludge, that coagulates during the fluid treatment.

The best modes for carrying out the invention are presented in the embodiments below: Embodiment 1.

Subject to treatment was sewage containing 22 mg/1 of ions Fe²⁺; 55.5 mg/1 of Cr⁶⁺; 14.3 mg/1 of

N?⁺; 8.0 mg/1 of Mo⁴⁺, 6.0 mg/1 of Co²⁺, having pH=6.5.

The efficiency of treatment of this water was examined in relation to the depth of the treated fluid sheet, and the value of the impulse operating current of a non-self-maintained glow discharge. The sewage sample was treated by plasma of a non-self-maintained glow discharge produced with die aid of the above-described device.

The operating impulse voltage supplied was of 450 V with the clock frequency of 400Hz.

The non-self-maintained glow discharge plasma was produced and controlled by the ionization voltage of 8 kV of the impulse current with average in time value of strength 2mA with the pulse duration of 1 Oμs, and clock frequency 20 kHz.

The sewage sample was treated by the non-self-maintained glow discharge, having the impulse operating current of average in time value of impulse current strength 2A, 3 A, 5 A, on two pairs of the unlike electrodes, with duty cycle of 2.

The distance from the fluid surface to the electrode 26 in the gaseous atmosphere was 8 mm. The pressure in the reactor 1 was maintained at the level of 50 Torr, the inlet fluid temperature at the reactor 1 was T=293 K.

The treated fluid was passed through the non-self-maintained glow discharge plasma in a stream

0.55mm, 0.65mm and 0.75mm in depth.

Simultaneously, the non-self-maintained glow discharge plasma was further affected by a mag- netic field, with the value of magnetic induction being 0.02 T. The treatment results are presented in Table 1. Table 1

The analysis of data, presented in Table 1 shows, that the degree (efficiency) of the sewage treat- ment from ions of heavy metals depends on the average in time value of the strength of the operating impulse current and the depth of the treated fluid.

The most effective, as regards the degree of treatment and power consumption, is the treatment of fluid, passed in a stream 0.55mm in depth through plasma of a non-self-maintained glow discharge, having the average in time value of strength of impulse operating current of 2 A, the volt- age of 450V, the frequency of 400 kHz and the relative pulse duration of 2. The power consumption, during such treatment of sewage from ions of heavy metals is only 1.38kW.hper 1 m³, while the known method of water purification with the aid of a glow discharge (RU, 2043969, Table) requires 1.6-1.9 kW.h for treatment of lm³.

Embodiment 2. Subject to treatment was an aqueous solution of sodium thiosulfate containing 1.0 g 1 of silver and having ρH=7.

The efficiency of the solution-treatment was examined in relation to the value of the operating current and the relative pulse duration of a non-self-maintained glow discharge.

The aqueous solution was treated by plasma of a non-self-maintained glow discharge, produced with the aid of the above-described device. The operating impulse voltage supplied was of 490V with the clock frequency of 1000 kHz. The non-self-maintained glow discharge plasma was produced with the aid of ionization voltage of lOkV , impulse current with average in time value of strength 2mA with the pulse duration of lOμs and clock frequency of 40 kHz. 5 The sewage sample was treated by the non-self-maintained glow discharge, having the average in time value of strength of the impulse operating current of 1 A, 3 A, 6 A and 10 A at 4 pairs of the unlike electrodes and the relative pulse duration of 2, 3 and 4.

The distance from the fluid surface to the electrode 26 in the gaseous atmosphere was 8 mm. The pressure in the reactor 1 was maintained at the level of 50 Torr, the inlet fluid temperature at 0 the reactor 1 was T=293 K.

The treated fluid was passed through the non-self-maintained glow discharge plasma in a stream 0.8 mm in depth.

Simultaneously, the non-self-maintained glow discharge plasma was further affected by a magnetic field, with the value of magnetic induction being 0.02 T.

15 The treatment results are presented in Table 2.

Table 2.

The analysis of data, presented in Table 2 shows, that treat ent-by a non-self-maintained glow discharge, having the strength of the average in time value of strength of the impulse operating current of 10 A and the relative pulse duration of 2,0 at the frequency of 1000Hz and the voltage _0 of 490V results in an increase of the treatment efficiency by up to 100 %. Besides, this embodiment substantiates the possibility of selection of the non-self-maintained glow discharge parameters for accomplishment of the most effective treatment from a particular kind of contamination.

Application of the operating current with the relative pulse duration of 3 and 4, diminishes the treatment efficiency. Thus, the optimal duty cycle of the operating current for sewage treatment from ions of silver is determined as equal 2.

The rate of sewage treatment from ions of silver can be increased, by reducing the pH-value of the solution, which results in destruction of the thiosulfate complex of silver, for example, in presence ofH₄SO₄. Na [Ag ₂ (S₂O₃) ₃] = 3H₂SO₄ + 2Na₂SO₄ + 3H₂O + 3SO₂ + 3S + Ag₂SO₄

Destruction of the complex Na__t[Ag ₂ (S₂O₃) ₃] results in formation of a simple silver compound Ag2SO ₎ which dissociates in the reaction

Ag₂SO₄ = 2Ag ⁺ + SO₄ ^2_ and is easily broken down under the effect of the non-self-maintained glow discharge plasma.

Embodiment 3.

Subject to treatment was an aqueous solution of sodium thiosulfate, containing 1.0 g 1 of silver and having pH=7, to which H₂SO was added in an amount providing for the pH-value of the medium be equal to 3.

The received solution was treated by a non-self-maintained glow discharge as described in Embodiment 2.

The treatment results are presented in Table 3.

Table 3.

The analysis of data, presented in Table 3, as compared to data presented in Table 2 shows, that a reduction of the pH- value of a solution, containing silver ions prior to treatment thereof by a non- self-maintained glow discharge plasma, results in an increase of the treatment efficiency by a factor of 1.5-3.0. A 100-percent efficiency of purification of an aqueous sodium thiosulfate solution containing 1.0 g/1 of silver and having pH=3, was achieved under the effect of plasma of the non-self-maintained glow discharge, having the average in time value of the strength of the impulse operating current of 6 A on two pairs of the unlike electrodes, and the relative pulse duration of 2.0 at the frequency of 1000Hz and the voltage of 490 V. The same efficiency was achieved, during treatment of similar solution by plasma of the non-self- maintained glow discharge, having the average in time value of the strength of the impulse oper- ating current of 10 A, and the relative pulse duration of 2.0 at the frequency of 1000 kHz and the voltage of 490N

This embodiment proves that this method can be applied not only for sewage treatment but also for extraction of precious metals from solutions. Embodiment 4.

Subject to treatment was the aqueous solution containing CΝ-ions in a concentration of 0.01 %,

0.1 % and 1.0 %.

The efficiency of the solution treatment was examined, in relation to the value of the operating current of a non-self-maintained glow discharge, the solution concentration and presence or ab- sence of a magnetic field.

The aqueous solution was treated by plasma of a non-self-maintained glow discharge, induced with the aid of the above-described device.

The operating impulse voltage supplied was of 480V with the clock frequency of 600 Hz.

The non-self-maintained glow discharge plasma was produced with the aid of ionization voltage of 1 OkN, with impulse current with average in time value strength of 4mA with the pulse duration of 5 μs, and clock frequency of 40kHz.

The sewage sample was treated by the non-self-maintained glow discharge, having the average in time value of strength of the impulse operating current of 1A, 3 A, 6A, 10A on the four pairs of unlike electrodes and the relative pulse duration of 2. The distance from the fluid surface to the electrode 26 in the gaseous atmosphere was 12 mm.

The pressure in the reactor 1 was maintained at the level of 50 Torr, the inlet fluid temperature at the reactor 1 was T=293 K.

0.55 mm in depth. Simultaneously, the non-self-maintained glow discharge plasma was further affected by a magnetic field with the value of magnetic induction being 0.02 T, and in absence of the field. Destruction of cyanide ions under the influence of glow discharge takes place, according to the following scheme:

CN^" + 2OH^" =CNO^" + H₂O + 2e^"

CNO^" + 4OH~ = 2CO^" ₂ + N₂ +H₂O + 6 e^"

The treatment results are presented in Table 4.

The effect of the non-self-maintained glow discharge causes redox processes in the solution for the account of generation of peroxide and super-oxide compounds of hydrogen, active radicals, resulting in oxidation of cyanide compounds.

The analysis of data, presented in Table 4 shows, that the degree (efficiency) of solutions treatment from CN-ions, depends on the average in time value of strength of the summarized impulse operating current, and conditions of the process accomplishment (in or off a magnetic field). This method is effective for treatment of solutions, having a wide range (at least from 0.01 % to 1.0 %) of cyanides content, without atmospheric emission thereof.

This method allows to decontaminate solutions, containing CN-ions to meet the requirements of the hygiene and sanitary standards. Embodiment -..

Subject to treatment was a conducting solution, containing 500 mg/1 of a surfactant DC- 10

(oxyethylated spirit).

The efficiency of the solution treatment was examined in relation to the value of the operating current and pulse rate of a non-self-maintained glow discharge.

The aqueous solution was treated by plasma of a non-self-maintained glow discharge, produced with the aid of the above-described device.

The operating impulse voltage supplied was of 470V with the clock frequency of 100 and 400

Hz. The non-self-maintained glow discharge was produced with the aid of impulse ionization voltage of 10 kV, with current with the average value of the strength of 4 mA with the pulse duration of 5 μs and clock frequency of 20 kHz.

The sewage sample was treated by the non-self-maintained glow discharge, having the average value of the strength of the impulse operating current of 0.6 A, 2 A, 4 A, on two pairs of the un- like electrodes and the relative pulse duration of 2.

The distance from the fluid surface to the electrode 26 in the gaseous atmosphere was 8 mm.

The treated fluid was passed through the non-self-maintained glow discharge plasma in a stream 0.65mm in depth.

Simultaneously, the treated fluid was further affected by a magnetic field, with the value of magnetic induction being 0.02 T. The solution treatment results are presented in Table 5. Table 5.

The analysis of data presented in Table 5 shows that the treatment efficiency depends on the value of the average in time of strength of summarized operating current and frequency of the operating current. Thus, the efficiency of the treatment process increases with an increase of the value of the average in time strength of summarized operating current, and frequency of the operating current. The process of treatment of aqueous mediums from surfactants, under the effect of a non^self= maintained glow discharge plasma is based on chemical reduction of components of the organic additives in solutions.

During treatment, a foam is formed on the fluid surface. When the distance from the fluid surface to the electrode in a gaseous atmosphere is less than 5 mm, an electrical breakdown may occur, due to contact with the formed foam, and with an increase of the said distance to over 25 mm the glow discharge becomes unstable and the power consumption significantly grows. This method may be widely used to purify sewage waters from surface-active substances. Embodiment 6.

Subject to treatment were aqueous solutions, containing organic substances: - chloroform, phenol, aniline, petroleum. The efficiency of purification from different combination of contamination type has been investi- gated.

The aqueous solutions have been treated with plasma of non-self-maintained glow discharge, produced with the aid of the describer above device.

The operating impulse voltage supplied was of 480V, clock frequency of 400Hz. The non-self-maintained glow discharge was produced with the aid of ionization impulse voltage of 9kV, with impulse current with average in time value of current strength of 3mA, clock frequency of 40kHz and impulse duration of 15ms.

The sewage water was treaded by non-self-maintained glow discharge, with average in time value of strength of summarized impulse current of 8 A on the two pairs of unlike electrodes and relative pulse duration of 2.

The distance from the fluid surface to the electrode 26 in the gaseous atmosphere was 10mm.

The pressure of the reactor 1 was maintained at the level of 50 Torr, the inlet fluid temperature at the reactor 1 was T=293°K. The treated fluid was passed through plasma of non-self-maintained glow discharge in a stream of 0.6mm in depth; simultaneously, the treated fluid was further affected by a magnetic field with the value of magnetic induction being 0.02T.

The solution treatment results are presented in Table 6.

Table 6

The analysis of data presented in Table 6 shows, that the efficiency of treatment depends on the type of contaminant. The purification from easily oxidized contaminants is more effective. The process of aqueous solutions from organic contaminants, under the influence of plasma of non-self-maintained glow discharge is based on oxidation and destruction of organic contami- nants.

During the purification process of aqueous solutions, containing organic contaminants, the latter has been destroyed with formation of destruction products: - Carbon dioxide and water. This method maybe widely used for purification of municipal sewage, industrial sewage and water, containing organic contaminants (including petrochemical industry, pharmaceutical industry, food industry etc.), paper mils. Embodiment 7. Subject to treatment was the aqueous solution of oxo-uranium nitrate UT, with the activity of 584 Bq/1.

The efficiency of the solution treatment was examined in relation to the value of the operating current of a non-self-maintained glow discharge, and to presence or absence of a magnetic field. The aqueous solution was treated by plasma of a non-self-maintained glow discharge, produced with the aid of the above=described device.

The operating impulse voltage supplied was of 480V with the clock frequency of 2 kHz. The non-self-maintained glow discharge plasma was produced the with the aid of ionization voltage of 9kV, with impulse current of the average in time value of strength of 2mA, with the pulse duration of 1 Oμs and clock frequency of 40kHz. The sewage sample was treated by the non-self-maintained glow discharge, having the average in time value of the impulse operating current of 1 A, 4 A, 9 A, 12 A and 15 A on six pairs of the unlike electrodes and the relative pulse duration of 2.

The distance from the fluid surface to the electrode 26 in the gaseous atmosphere was 6 mm. The pressure in the reactor 1 was maintained at the level of 50 Torr, the inlet fluid temperature at the reactor 1 was T=293 K.

The treated fluid was passed through the non-self-maintained glow discharge plasma in a stream 0.3 mm in depth.

Simultaneously, the treated fluid was further affected by a magnetic field with the value of magnetic induction being 0.02 T, and in absence of the field. The treatment process runs as follows:

UO(OH)₂ ²⁺ + 2H(OOH) — > UO(OH) (OOEQ ₂ + 2H^1" UO(OH)₂ (OOH) ₂ + H₂ O — > UO(OH) ₃OOH+ H₂O₂

The summary reaction of the anhydrous peroxo-uranium acid formation is presented by the following equation:

UO(OH)₂ ²⁺ + H₂O₂ + 3 H₂ O — > UO(OH) ₃OOH+ 2H*

The produced sediment is separated from the basic solution by known methods, for example, by filtration.

The solution treatment results are presented in Table 7.

The analysis of data, presented in Table 7 proves, that sewage purification under the influence of non-self-maintained glow discharge, with average in time value of the strength of the summarized impulse operating current of 15 A, in the presence of magnetic field shows the highest efficiency, absence of magnetic field decreases the efficiency of purification. This method maybe widely used to purify sewage water from radio-nuclides. Embodiment 8.

Subject to treatment was water, containing various microorganisms in a concentration of 10¹² unit/1.

The efficiency of the water decontamination was examined in relation to the value of the operating current of a non-self-maintained glow discharge, and to the depth of the fluid flow. The aqueous solution was treated by plasma of a non-self-maintained glow discharge, produced with the aid of the above=described device. The operating impulse voltage supplied was of 475V with the clock frequency of 2kHz. The non-self-maintained glow discharge plasma was produced with the aid of ionization voltage of lOkV, with the impulse current with average in value of strength of 200μA with the pulse du¬

ration of 5μs. The sewage sample was treated by the non-self-maintained glow discharge, having the average in time value of the summarized impulse operating current of 5 A and 10A on two pairs of the unlike electrodes and the relative pulse duration of 2.

The distance from the fluid surface to the electrode 26 in the gaseous atmosphere was 6 mm. The pressure in the reactor 1 was maintained at the level of 50 Torr, the inlet fluid temperature at the reactor 1 was T=293 K. The treated fluid was passed through the non-self-maintained glow discharge plasma in a stream 0.5 and 1.0 mm in depth.

Simultaneously, the non=self-maintained glow discharge plasma was further affected by a mag= netic field, with the value of magnetic induction being 0.02 T. The most stable microorganisms are the E.Coli bacteria, related to the Enterobacteriacae family, and they are a sanitary indicator of the environmental pollution owing to a greater stability to any exposure.

The treatment results are presented in Table 8. Table 8.

The analysis of data, presented in Table 8 shows, that the rate of decontamination (treatment time before complete inactivation of microorganisms) depends on the average in time value of the of strength of summarized operating current of a non-self-maintained glow discharge, and a treated fluid depth in the stream passed through the non-self-maintained glow discharge plasma. As can be seen from this Table, the maximum time of inactivation of E.Coli is 1.4 s, for yeast-like fimgi of the Candida genus and for pathogenic staphylococcus it is 1.2 s, whereas during a fluid treatment by a glow discharge (see RU, 2043975, Table) the minimum time of inactivation of E.Coli is 7 s, and for yeast-like fimgi of the Candida genus and for pathogenic staphylococcus it is 6 s. The above particular embodiments of the proposed invention confirm, that the invention can be effectively used for treatment and decontamination of industrial and domestic sewage, containing critical concentrations of toxiferous components to a level of the hygiene and sanitary standards and lower, for supplementary purification of sewage after prior treatment by known methods, as well as for extraction of precious metals.

The proposed invention makes it possible to carry out a treatment process at a high average in time value (5-20A) of the strength of current on the pair of unlike electrodes and a relatively low voltage of 500V. The proposed invention makes it possible to increase the efficiency of sewage treatment and decontamination, and thus to reduce the power costs of treatment per volume unit of treated fluids.

Claims

CI-A1MS

1. A method of sewage treatment and decontamination, by effecting a treated fluid by an electric discharge, produced above the sur&ce of said fluid with the use of unlike electrodes, one of which is submerged in said treated fluid, and the electrode of reciprocal potential is in a gaseous atmosphere, wherein the effect is produced by a non-self-maintained glow discharge.

2. A method as claimed in claim 1, wherein for said non-self-maintained glow discharge, the use is made a discharge, produced by the effect of a high frequency impulse voltage.

3. A method, as claimed in any of the foregoing claims 1 and 2, wherein said non-self- maintained glow discharge is produced by simultaneous application of an operating voltage and ionization high frequency impulse voltage to the said unlike electrodes.

4. A method, as claimed in any of the foregoing claims 1 and 2, wherein for said non-self- maintained glow discharge, the use is made of a discharge, having an adjustable operating current of average in time value of strength of 0.1-20 A, a voltage of no more than 500 V, a clock fre- quency of 0=1-100 kHz and a duty cycle of no less, than 1.3

5: A method* as claimed in claim 3, wherein said non-self-maintained glow discharge is produced by simultaneous application to said unlike electrodes of an operating impulse voltage of no more than 500 V, with a clock frequency of 0.1-100 kHz, and ionization impulse voltage of 2= lOkV, average in time value of current strength of 30-5000μA on the pair of unlike electrodes and a pulse duration of 0.01 -20 μs.

6. A method, as claimed in any of the foregoing claims 1 through 5, wherein said treatment is accomplished at a temperature of a treated fluid below the natural boiling point of such fluid.

7. A method, as claimed in any of the foregoing claims 1 through 6, wherein said treatment is accomplished at a pressure maintained at a level of 30-250 Torr.

8. A method, as claimed in any of the foregoing claims 1 through 7, wherein said treatment is accomplished with said treated fluid fed in a sheet 0.3-5 mm in depth.

9. A method, as claimed in any of the foregoing claims 1 through 8, wherein said treatment is accomplished with said treated fluid fed in a stream.

10. A method, as claimed in claim 9, wherein said stream is made as a turbulent flow.

11. A method* as claimed in any of the foregoing claims 1 through 10, wherein a zone of a non-self-maintained glow discharge is further affected by a magnetic field.

12. A method, as claimed in claim 11, wherein for said magnetic field the use is made of a magnetic field, with a value of magnetic induction in the discharge zone being at least 0.01 T.

13. A method of sewage treatment and decontamination by effecting a treated fluid by an electric discharge, produced above- the surface of said fluid with the use of unlike electrodes, one of which is submerged in said treated fluid, and the electrode of reciprocal potential is in a gaseous atmosphere, wherein the effect is produced by a non-self-maintained glow discharge, which is produced by simultaneous application to said electrodes of an operating impulse voltage of no more than 500 V with a clock frequency of 0.1-40 kHz, and ionization impulse voltage of 2-10 kV, with average in time value of the strength of current of 30-5000μA on the pair of unlike elec- trodes and a pulse duration of 0.01-20 μs, with a pressure maintained at a level of 30-250 Torr, a temperature below the natural boiling point of a treated fluid, and a magnetic field with a value of magnetic induction in the discharge zone being at least 0.01 T, whereas a treated fluid is fed in a turbulent flow 0.3-5 mm in depth.

14. A method of sewage treatment and decontamination, by effecting a treated fluid by an electric discharge, produced above the surface of said fluid with the use of unlike electrodes, one of which is submerged in said treated fluid, and the electrode of reciprocal potential is in a gaseous atmosphere, wherein the effect is produced by a non-self-maintained glow discharge with an operating adjustable impulse current with average in time value of strength of 0.1-20 A on the pair of unlike electrodes, a voltage of no more than 500 N, a clock frequency of 0.1-100 kHz and a duty cycle of at least 1.3.

15. A method of sewage treatment and decontamination* by effecting a treated fluid by an electric discharge, produced above the surface of said fluid with the use of unlike electrodes, one of which is submerged in said treated fluid, and the electrode of reciprocal potential is in a gaseous atmosphere, wherein the effect is produced by a non-self-maintained glow discharge with an operating adjustable impulse current with average in time value of strength of 0.1-20 A, a voltage of no more than 500 N, a clock frequency of 0.1-100 kHz and a duty cycle of at least 1.3, which is induced while a pressure of 30-250 Torr and a temperature below the natural boiling point of said treated fluid are maintained in the zone of said discharge, and a treated fluid is fed in a turbulent flow 0.3-5 mm in depth.

16. A method, as claimed in claim 15, wherein a zone of a non-self-maintained glow discharge is further affected by a magnetic field.

17. A method, as claimed in claim 16, wherein for said magnetic field the use is made of a magnetic field with a value of magnetic induction being at least 0.01 T.