WO2010023677A2

WO2010023677A2 - Apparatus and method for wastewater treatment

Info

Publication number: WO2010023677A2
Application number: PCT/IN2008/000649
Authority: WO
Inventors: Dilip Waman Bapat; Kalyan Raman Venkataraman; Vishwanath Pundalik Bhandarkar
Original assignee: Thermax Limited
Priority date: 2008-08-25
Filing date: 2008-10-07
Publication date: 2010-03-04
Also published as: WO2010023677A3

Abstract

An apparatus (100) for treating wastewater comprising a chamber consisting of a bioreactor (1 ) wherein wastewater is treated with microorganisms; said chamber (1 ) is provided with an inlet (2) adapted to introduce waste water into said chamber, an outlet (3) for transferring treated waste water from said chamber; electrode assembly for introducing electrical charges in the wastewater; and characterized in that said electrode assembly is provided in a flow channel (8) between said inlet and said chamber in a manner that it prevents the obstruction in the flow of wastewater through the flow channel.

Description

APPARATUS AND METHOD FOR WASTEWATER TREATMENT

FIELD OF INVENTION

This invention relates to an apparatus and a method for wastewater treatment.

BACKGROUND

The process to treat effluent and to improve the effluent treatment process has been known to certain industries for many years. The wastewater or industrial effluent is the most complex, unusable output of almost all the industries. Wastewater treatment is the removal of impurities and total suspended solids as well as reduction in chemical oxygen demand (COD) and biological oxygen demand (BOD).

The waste water treatment has generally three important factors: a) Pre-treatment. b) COD/BOD reduction. c) Post treatment.

However various effluent treatment processes involves number of stages. Some of the processes use biodegradation means while other intend towards the use of chemical or physical means to meet the stringent requirement of pollution control board. As wastewater is continuously generated from industries (effluents), nature (mudslides), human beings (domestic purpose) there is a need to treat this waste water.

Typically aerobic bioreactor uses various suitable biological cultures along with necessary oxygen supply and food supply to bacterial population. It is also known that the reactors using suspended biomass as a workforce or attached growth of biomass on different substrates are fixed or fluidized. The bioreactor efficiency can be further improved by increasing the efficiency of oxygen transfer from air or gas using proper air or oxygen distributing grids. The organic loading of reactors is typically in the range of 2 to 12 kg/m³ per day. This has been achieved by different designs so far.

Sometimes electrochemical process is proved to be beneficial to treat variety of industrial wastewater including paper mill waste, steel industries effluent, lead and mercury laden effluents, radioactive effluents, textile waste and the like. In view of all these improvements and proper design characteristics of the known art bioreactor, it has been possible to achieve the following result/advantages.

(a) lowest Hydraulic Retention Time (HRT) of 4-5 hours

(b) 90 percent of reduction in COD/BOD using various treatment system in case where BOD are lower than 2000 mg/liter and

(c) a COD/BOD ratio of 2.

In spite of several advantages, the prior art process and the reactor suffers from several drawbacks as follows

(a) HRT increases with COD/BOD ratio increasing beyond 2.

(b) The oxygen demand with very advanced distribution grid is not much less, than 2 kg per 1 kg of BOD degraded in conventional bioreactor.

(c) The percentage earner media with high surface area in the reactor vessel is not less than 50% wherever fluidized bed reactor is used.

In the non-fluidized bed reactor device, there are frequent chances of bulking and floating of biomass with adverse operating conditions. The hydraulic retention time (HRT) is as high as 4-5 hours on minimum side and or as high as 20 to 30 hours on maximum side depending upon the design and technology used i.e. suspended growth, fixed film growth or fluidized bed growth of biomass, fluidized bed reactor being the lowest. However, with such high HRT, the vessel sizes for large capacity plants are very big and the air distribution, liquid feeding and fluidization pose operational problems. The commissioning and stabilizing period is also higher.

EXISTING KNOWLEDGE

CNl 749177 discloses an electrical and biological processing apparatus and method for wastewater containing heavy metal ion and non-degradable organism. The apparatus includes electric and biological reaction tower with top air outlet, bottom air distributor, liquid inlet in the upper part, liquid outlet in the lower part and connected with a precipitator, a tower wall and tower core constituting one electrode pair and insulating layer outside the tower wall. This Chinese invention is related to a pretreatment of non-biodegradable wastewater to become a biodegradable wastewater, which can be further degradable through a subsequent bioreactor. In this Chinese invention, the applied electrical field is used to alter the properties of non-biodegradable wastewater and make them biodegradable. However, there is no such description of enhancement in microbial activity by the application of electrical current.

UAOO 18772 discloses a method for reducing bacterial infectiousness of wastewater. The treatment is earned out by direct current electric field at voltage of electric field being equal to zeta-potential of bacterial cells. However, the aforementioned document does not describes the apparatus used, moreover the electrical charge used here is to destroy the bacteria and not for the enhancement in there microbial activity.

US6187183 discloses a method for treating wastewater with the help of aerobic microbes. The waste water treatment system includes a recirculating treatment zone and a filter/treatment zone. The recirculating zone has a treatment medium that includes aerobic microbes and small beads that create interstices within, and extensive surface area on the medium. These beads actives microbes dwell and through which dead microbes and treated water are permitted to pass easily. However, the method described in US 6187183 does not use electric charge to raise the efficiency of the microbes.

EP0695722 discloses an apparatus for waste water treatment. The apparatus includes two bioreactors which have provision for circulation and aeration. The contact circulation portions herein are packed with charcoal and calcium carbonate filler. The upper portion of the bioreactor is packed with vinylidene chloride fillers. However, in the document EP 0695722 does not show any significance of electrodes and its usage.

JP05228486 discloses an apparatus for biological treatment of waste water. The apparatus includes a dissolved oxygen adjustment mechanism, which adjusts the volume of dissolved oxygen in a biological reaction tank. This makes the ratio of presence amount of bacteria and planktons among the aerobic microbes constant. However, the document JP05228486 the aerobic microbe ratios is maintained but not with the application of electric charge. OBJECTS OF THE INVENTION

One of the objects of the present invention is to provide an improved method for the bio-degradation of effluent with lower hydraulic retention time than hitherto possible.

Another object of the present invention is to provide an improved method, which requires less oxygen demand and still ensure faster reaction rate.

It is a further object of the present invention to provide an improved method, which avoids the problems associated with the conventional bioreactors techniques.

It is a further object of the present invention to provide an improved apparatus, which avoids the problems associated with the conventional bioreactors techniques.

It is a further object of the present invention to provide an improved method, which requires minimum supervision and control and can be easily practiced.

It is a further object of the present invention to provide an improved method which can be incorporated in any waste water system including the membrane bioreactor system.

It is a further object of the present invention to provide an improved biodegradation reactor which ensures effective distribution of air or oxygen. It is a further object of the present invention to provide an improved apparatus which is smaller in size than so far possible and still provide high reaction rate.

A still further object is to provide a method wherein the overall energy inputs are reduced and shock load problems are eliminated.

A still further object of the present invention is to provide a method in which the commissioning and stabilizing period is considerably reduced, and the total packing volume is also minimized compared to the of hitherto known reactor.

It is yet another object of the present invention to provide a method, which improves the COD/BOD ratio of the wastewater for better biodegradation.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided an apparatus for treating wastewater comprising a chamber consisting of a bioreactor wherein wastewater is treated with microorganisms; said chamber is provided with an inlet adapted to introduce waste water into said chamber, an outlet for transferring treated waste water from said chamber; electrode assembly for introducing electrical charges in the wastewater; characterized in that said electrode assembly is provided in a flow channel between said inlet and said chamber in a manner that it prevents the obstruction in the flow of wastewater through the flow channel.

Typically, the electrode assembly is adapted to receive an electrical current in the range of 1 ampere to 30 ampere for wastewater with flow rate of 1000 liter per hour. Typically, the apparatus includes means to connect the electrode of the electrode assembly to a DC power supply adapted to supply electrical current to said electrodes.

Typically, a DC power supply source is used to supply electrical current both to the electrode assembly in said flow channel and in the said chamber.

Typically, the electrode assembly includes an anode and is provided with fitting means which includes an outer member cooperating with the walls of the flow channel and an inner member for securing the anode.

Typically, the fitting means consists of two elements an outer member and an inner member placed operatively along the flow channel.

Typically, the two elements are spaced apart from each other in the flow channel wherein each of the element have an outer member cooperating with the wall of the flow channel and inner member spaced apart from the outer member for stabily fitting the anode.

Typically, the fitting means comprises an outer ring and inner ring secured to outer ring by insulated spokes.

Typically, the inner ring is adapted to locate and fit the anode.

Typically, the electrode assembly includes a cathode, which is the wall of the flow channel, and an anode, which is spaced apart from the wall of the flow channel. Typically, the electrodes are coated electrodes of predetermined shape and size.

Typically, the electrode assembly includes an anode coated with precious metal oxide.

Typically, the electrode assembly includes an anode of dimensionally stable anodic material coated with titanium.

Typically, the electrode assembly includes a cathode made of material selected from the group of materials consisting of mild steel, aluminum, stainless steel and copper.

In accordance with this invention there is also provided a method for treating wastewater by microorganisms in a bioreactor located in a chamber having an inlet and outlet, wherein a flow channel is defined between the inlet and said chamber; the method includes a step of subjecting the wastewater in the flow channel to an electric charge produced by a current having a magnitude of 1 to 30 amperes for a flow rate of 800 to 1200 liters per hour for a period of 0.5 hours to 24 hours.

Typically, an electric charge is produced by a DC electric current provided to electrodes fitted in the flow channel in a continuous manner.

Typically, an electric charge is produced by a DC electric current provided to electrodes fitted in the flow channel in an intermittent manner. Typically, an electric charge is produced by a DC electric current provided to electrodes fitted in the flow channel in a pulsating manner.

Typically, the method includes the step of providing the said electric charge within the bioreactor.

BRIEF DISCRIPTION OF ACCOMPANYING DRAWINGS

The invention will now be described with respect to the accompanying drawings in which:

Figure 1- illustrates the complete apparatus in accordance with this invention;

Figure 2A- shows top view of the flow channel as shown in Figure 1;

Figure 2B-another embodiment of the top view of the flow channel;

Figure 3- is an another embodiment of the apparatus as shown in Figure 1 and

Figure 4- is a graph showing the relationship between electrical current in amperage and COD level.

DETAIL DISCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

A bioreactor chamber to treat wastewater having an electrode assembly installed inside is previously employed. Wastewater is treated inside the bioreactor only and treated water is taken out from an outlet. However, this system does not produce satisfactory result for wastewater containing tougher organic molecule and thereby reducing the COD level. In the present invention, an external electrode assembly is installed inside a flow channel between the feed inlet and the bioreactor chamber to pre-treat the wastewater and to achieve higher COD and BOD reduction.

Referring to Figure 1 and Figure 3, of the accompanying drawings, an apparatus for treatment of wastewater by electro biodegradation is generally indicated by reference numeral (100).

Figure 1 : The figure shows an apparatus for treatment of wastewater by electro biodegradation comprising a bioreactor chamber (1). Wastewater is introduced inside the bioreactor chamber (1) through an inlet pipe (2) and an outlet pipe (3) is provided for transferring treated wastewater from the bioreactor chamber to a clarifier (4). A pump (9) is provided to pump the raw effluent inside the bioreactor chamber (1). Depending on the flow rate of the raw effluent the capacity of pump is decided. For aerobic system an air supply source (6) is installed, which provides air to the chamber (1). Inside the improved bioreactor, the aeration grid (5) is provided at the operative lower end of the bioreactor chamber (1) to supply air. The diameter of aeration grid (5) varies and is based on the hydraulic loads of the reactor. The number of holes in the aeration grid is calculated based on rate of airflow and the air velocity. The diameter of aeration grid (5) depends on the cross-sectional area of the bioreactor (1).

Microbes are introduced inside the bioreactor chamber (1) for carrying out biodegradation. For sewage treatment, no initial inoculations are required as the sewage itself contains numerous microbes and the system is self-sustaining. For treatment of any other waste, the initial microbial inoculation is done using suspended biomass, which later forms attached growth system if a fluidized bed bioreactor with anchoring media is used. The inoculation is normally done at ambient temperature conditions. However, a range between 20-35⁰C is accepted as favorable condition for inoculation.

A flow channel (8) is provided between the inlet pipe (2) and the bioreactor chamber (1). This flow channel (8) is provided with electrode assembly for supplying electrical charge to the raw feed wastewater inside the flow channel (8). The electrode assembly is provided inside the flow channel in such a way that it prevents the obstruction in the flow of wastewater through the flow channel. An electrical power source device is provided to supply electrical current to the electrode assembly.

The electrode assembly consists of an anode, a cathode, fitting means and means to supply electric current to electrodes. The electrodes in the electrode assembly are coated electrode of predetermined shape and size. An anode is fitted in the electrode assembly with the help of fitting means. The said fitting means have an outer member (10) (refer figure 2) and an inner member (12) (refer figure 2). The outer member (10) cooperates with the wall of flow channel (11) and inner member is provided for securing an anode. The inner member is secured to outer member by insulated spokes. Anode is placed inside the inner member securely. Anodes used can be expanded metal type titanium electrodes coated with mixed oxides of precious metals. The wall of the flow channel (11) acts as cathode and anode is spaced apart from the wall of the flow channel. Cathodes are made of stainless steel. For holding of electrode assembly in place in the flow channel, number of engineering alternatives can be used such as electrodes supported on some means from near the bottom, held in position by fixing from top of the flow channel and supported on a flow channel. The cage type of configuration can also be used in the bioreactor for ease of maintenance. The electrode assembly provided in the flow channel is adapted to treat the wastewater before the wastewater is introduced in the bioreactor. In this configuration, the wastewater is pretreated by increasing the oxygen levels. This pretreatment breaks tougher organic molecules to simpler compounds there by increasing the rate of degradation in the subsequent bioreactor system.

Different current densities (in order of 1 - 1000 Amperage) can be applied to the electrodes arranged in either parallel or series by adjusting the amperage of the power source, thus bringing flexibility in operating conditions. For wastewater with flow rate of 1000 liter per hour, an electrical current in the range of 1 ampere to 30 ampere is provided for retention time of 4 hours. Typically, the range between 9 ampere to 21 ampere is accepted as favorable condition.

The treated water is then allowed to pass through on outlet (3) and is collected in a clarifier (4). The treated water so obtained also contains dead microbes, which settle down in the clarifier because of density difference. The sludge is removed from the bottom of the clarifier and treated water is taken from the top of the clarifier by a float mechanism.

Figure 2A: The figure shows a top view of the electrode assembly placed inside the flow channel. The electrode assembly consists of anode (14), cathode (15), inner member (12), fitting means (16) and insulated spokes (13). The outer member cooperates with the wall of flow channel and inner member is provided for securing the anode (14). The outer member is fitted with the help of complementary fitting means (16) with the wall of the flow channel (11). The anode is secured to the inner member by insulated spokes (13). The inner member is secured to the outer member by insulated spokes (13). These spokes are prepared from any insulating material. The Inner member is adapted to locate and fit an anode securely. An anode (14) is placed spaced apart from cathode (15).

Figure 2B: The figure shows top view for another embodiment of the electrode assembly placed inside the flow channel wherein the wall of flow channel itself acts as cathode (15). The electrode assembly consists of anode (14), wall of the flow channel (11) acting as a cathode, outer member (10), inner member (12), fitting means (16) and insulated spokes (13). An anode (14) is spaced apart from cathode (15) with the help of insulated spokes (13).

Figure 3: The figure shows another embodiment of the invention wherein an additional internal electrode assembly (7) is introduced to the system of figure 1 to transfer electrical charge to the microbes present inside the bioreactor chamber. According to this arrangement, feed water is treated twice. The wastewater is treated first inside the flow channel (8) wherein first electrode assembly is placed. The partially treated water is then allowed to pass through second electrode assembly (7) placed inside the bioreactor chamber (1) for optimum result. This arrangement helps to break tougher organic molecules to simpler compound there by increase the rate of degradation in the subsequent bioreactor system.

Thus by applying electrical current to the electrode assembly present inside the flow channel biodegradation is improved having positive impact on COD/BOD reduction, organic loading, HRT. By passing electrical current to both the electrode assemblies, the microbial activity is enhanced by change in the metabolic activity of the microbes. This change in metabolic activity reduces the rate of multiplication of bacterial cell to half of the normal generation time. The growth rate of microbes is calculated by increase in the turbidity with time with and without electrical charged effluent. The experimental results indicate that the rate of metabolic activity of bacterial cell has increased due to applied electrical current.

The invention will now be described with respect to the following examples, which do not limit the invention in any way and only exemplify the invention.

Example 1

An apparatus was set up in accordance with this invention for industrial effluent of synthetic waste containing Mono Ethylene glycol. Flow rate of the effluent was 1000 liter per hour. The raw effluent was stored in the equalization tank of volume 4500 liters. The retention time of the effluent in equalization tank was 4 hours for anaerobic system. A pump of capacity 100 L/hr was used to pump the effluent inside the bioreactor chamber from the equalization tank. The capacity of the bioreactor chamber was 4000 liter. Microbes Pseudomonas alcaligens were inoculated from the broth prepared through minimal media inside the bioreactor chamber. The flow channel was installed between the inlet feed and the bioreactor chamber. The dimensions of the flow channel were 1 ml with 100 mm Dia. Electrical power source device was employed to supply the electrical current to the electrode assemblies. Electrical power source device was used for supply electrical current in the range 1 ampere to 30 ampere to the electrode assembly. Electrode assemblies were placed inside the flow channel and in the bioreactor chamber.

Electrodes assemblies include an anode. Anode was placed inside the flow channel. Here wall of the flow channel was acting as cathode. Anode used in the experiments was metal type titanium electrode coated with metal oxides of precious metals. The treated water was then allowed to pass through outlet in a clarifier. Here in the clarifier the waste sludge was separated from the treated water.

In the first set of experiments, the system was tested without supplying electrical current to either of the electrode assemblies. Here a system was tested without supplying electrical charge inside the flow channel and inside the bioreactor chamber and the results were tabulated.

In a second set of experiments, the system was tested by supplying electrical current only to the electrode assembly placed inside the bioreactor chamber. Here electric current was not supplied to the electrode assembly placed inside the flow channel and the results were tabulated.

In a third set of experiments, the system was tested by supplying electrical current only to the electrode assembly placed inside the flow channel. Here electric current was not supplied to the electrode assembly placed inside the bioreactor chamber and the results were tabulated.

In a fourth set of experiments, the system was tested by supplying electrical current to both the electrode assemblies placed inside the flow channel and inside the bioreactor assemblies. The results were tabulated.

Example 2:

An apparatus was set up in accordance with this invention for industrial effluent of synthetic waste containing sewage. Flow rate of the effluent was 1000 liter per hour. The raw effluent was stored in the equalization tank of volume 800 liters. The retention time of the effluent in equalization tank was 45 minutes for aerobic system. A blower of capacity 5 m3/hr was used for aeration purpose. A pump of capacity 1 m3/hr was used to pump the effluent inside the bioreactor chamber from the equalization tank. The capacity of the bioreactor chamber was 750 liter. Microbes collected from sewage having wide range of wild microbes were inoculated from the broth inside the bioreactor chamber. The dimension of aeration grid was 200 mm xlOO mm based on hydraulic loads of the reactor and the air required for the biodegradation. Number of holes in the aeration grid were 40. The flow channel was installed between the inlet feed and the bioreactor chamber. The dimensions of the flow channel were 1 m L with 100 mm Dia (length, cross- sectional diameter and width). Electrical power source device was used for supply electrical current in the range 1 ampere to 30 ampere to the electrode assembly. Electrode assemblies were placed inside the flow channel and in the bioreactor chamber.

Electrodes assemblies include an anode. Anode was placed inside the flow channel. The wall of the flow channel was allowed to act as cathode.

Anode used in the experiments was metal type titanium electrode coated with metal oxides of precious metals. Cathodes were made of stainless steel. The treated water was then allowed to pass through a clarifier. Here in the clarifier the waste sludge is separated from the treated water. This treated water is available for enduse.

In a first set of experiments, the system was tested without supplying electrical current to either of the electrode assemblies. Here a system was tested without supplying electrical charge inside the flow channel and inside the bioreactor chamber and the results were tabulated.

In a fourth set of experiments, the system was tested by supplying electrical current to both the electrode assemblies placed inside the flow channel and inside the bioreactor assemblies. The results were tabulated for these experiments.

Table 1 -shows the comparative performance of different apparatus in accordance with this invention as compared with the prior art apparatus for synthetic waste containing mono-ethylene glycol. The table shows that consistently the use of the apparatus in accordance with this invention reduces COD and BOD level. It is particularly noticed that use of an external electrode in the flow channel considerably reduces the COD and BOD level. Table 1

Table 2. shows Reduction in COD level with different a system designed for these experiments under various conditions.

For Aerobic System a flow rate of 1000 L / hr and a reactor volume of 750 L and HRT of 45 minutes was maintained.For Anaerobic system a flow rate of

1000 L / hr having a reactor volume of 4000 L and HRT of 4 hrs was maintained. Similar or comparative results can also be obtained for BOD reduction. Table 2

Figure 4: Figure 4 illustrates the graphical relationship between electrical current in amperage and COD (chemical oxygen demand) level. X-axis indicates the optimization of current (amperage) at 1000 liter per hour of sewage flow rate and

Y- axis indicates COD at the outlet for an inlet COD load of 644 mg/1. The graph illustrates reduction in COD level for electrode configuration of system at various conditions.

When the system in accordance with the invention was tested without supplying electrical current to an electrode assembly the reduction in COD was negligible.

When the system was tested by supplying electric current only to the electrode assembly present inside a flow channel, reduction in COD was more than that achieved for the configuration of system without electric current.

When the system was tested by supplying electric current only to the electrode assembly present inside a bioreactor chamber, reduction in COD was comparatively to above said conditions.

When the system was tested by supplying electric current to both the electrode assembly present inside a flow channel and inside the bioreactor, reduction in COD was higher than any configuration tested.

This shows that the reduction in COD level is highest when electric current is supplied to both the electrode assembly present inside the flow channel and inside the bioreactor.

It also shows that the system produces an optimum result when the applied current is between 15 ampere to 20 ampere.

Conclusion

From the experimental results, it was found that the system works most efficiently at 17 ampere to 18 ampere for this particular efficiency. Above 20 ampere, it was found the microbes were extra charged / died and their efficiency tends to fall.

For aerobic and anaerobic system;

It was found that the reduction in COD was more when the system was tested by supplying electrical current to both the electrode assemblies placed inside the flow channel and inside the bioreactor chamber.

When the system was tested by supplying electrical current only to the electrode assembly placed inside the bioreactor chamber and not to the electrode assembly placed in the flow channel the reduction in COD was comparatively less than that achieved by supplying electrical current to both the electrode assemblies.

When the system was tested by supplying electrical current only to the electrode assembly placed inside the flow channel and not to the electrode assembly placed inside the bioreactor chamber the reduction in COD was comparatively less than that achieved by supplying electrical current only to the electrode assembly placed inside the bioreactor chamber and not to the electrode assembly placed in the flow channel.

When the system was tested without supplying electrical current to either of the electrode assemblies the reduction in COD level was not at all significant and was comparatively less than that achieved by any of the arrangement. Thus by using electrical energy in the invented improved bioreactor, biodegradation is improved having positive impact on COD/BOD reduction, organic loading, HRT, volume of carrier media if a fluidized bed bioreactor is used. Due to passage of electrical current, the microbial activity is enhanced by change in the metabolic activity of the microbes. Due to change in the metabolic activity, the rate of multiplication of a bacterial cell reduces to half of the normal generation time. The growth rate of microbes is calculated by increase in the turbidity with time with and without electrical charged effluent.

The experiments also indicate presence of different microbial consortia. The ^" reactor shows the presence of bacterial population and elimination of protozoan and other ciliates. This helps in increase the rate of biodegradation in presence of bacterial population rather than higher organisms. The experimental results indicate that the rate of metabolic activity of bacterial cell has increased due to applied electrical current. This is evident from the rate of bio-degradation and growth rate.

While considerable emphasis has been placed herein on the specific structure of the preferred embodiment, it will be appreciated that many alterations can be made and that many modifications can be made in the preferred embodiment without departing from the principles of the invention. These and other changes in the preferred embodiment as well as other embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation

Claims

Claims:

1. An apparatus for treating wastewater comprising a chamber consisting of a bioreactor wherein wastewater is treated with microorganisms;

• said chamber is provided with an inlet adapted to introduce waste water into said chamber,

• an outlet for transferring treated waste water from said chamber;

• electrode assembly for introducing electrical charges in the wastewater; and

• characterized in that said electrode assembly is provided in a flow channel between said inlet and said chamber in a manner that it prevents the obstruction in the flow of wastewater through the flow channel.

2. An apparatus as claimed in claim 1, wherein the said electrode assembly is adapted to receive an electrical current in the range of 1 ampere to 30 ampere for wastewater with flow rate of 1000 liter per hour.

3. An apparatus as claimed in claim 1, wherein the apparatus includes means to connect the electrode of the electrode assembly to a DC power supply adapted to supply electrical current to said electrodes.

4. An apparatus as claimed in claim 2, wherein a DC power supply source is used to supply electrical current both to the electrode assembly in said flow channel and in the said chamber.

5. An apparatus as claimed in claim 1, wherein said electrode assembly includes an anode and is provided with fitting means which includes an outer member cooperating with the walls of the flow channel and an inner member for securing the anode.

6. An apparatus as claimed in claim 1, wherein said fitting means consists of two elements an outer member and an inner member placed operatively along the flow channel.

7. An apparatus as claimed in claim 6, wherein the two elements are spaced apart from each other in the flow channel wherein each of the element have an outer member cooperating with the wall of the flow channel and inner member spaced apart from the outer member for stabily fitting the anode.

8. An apparatus as claimed in claim 5, wherein the fitting means comprises an outer ring and inner ring secured to outer ring by insulated spokes.

9. An apparatus as claimed in claim 8, wherein the inner ring is adapted to locate and fit the anode.

10.An apparatus as claimed in claim 1, wherein said electrode assembly includes a cathode which is the wall of the flow channel and an anode which is spaced apart from the wall of the flow channel.

11.An apparatus as claimed in claim 1, wherein the electrodes are coated electrodes of predetermined shape and size.

12.An apparatus as claimed in claim 1, wherein the electrode assembly includes an anode coated with precious metal oxide.

13.An apparatus as claimed in claim 1, wherein the electrode assembly includes an anode of dimensionally stable anodic material coated with titanium.

14.An apparatus as claimed in claim 1, wherein an electrode assembly includes a cathode made of material selected from the group of materials consisting of mild steel, aluminum, stainless steel and copper.

15.A method for treating wastewater by microorganisms in a bioreactor located in a chamber having an inlet and outlet, wherein a flow channel is defined between the inlet and said chamber; the method includes a step of subjecting the wastewater in the flow channel to an electric charge produced by a current having a magnitude of 1 to 30 amperes for a flow rate of 800 to 1200 liters per hour for a period of 0.5 hours to 24 hours.

16.A method as claimed in the claim 15, wherein an electric charge is produced by a DC electric current provided to electrodes fitted in the flow channel in a continuous manner.

17. A method as claimed in the claim 15, wherein an electric charge is produced by a DC electric current provided to electrodes fitted in the flow channel in an intermittent manner.

18.A method as claimed in the claim 15, wherein an electric charge is produced by a DC electric current provided to electrodes fitted in the flow channel in a pulsating manner.

19.A method as claimed in the claims 16, 17 and 18 wherein the method includes the step of providing the said electric charge within the bioreactor.