The present disclosure relates to treatment of industrial waste gases. Particularly, the present disclosure relates to an apparatus and a method for deodorizing industrial waste gas generated in Effluent treatment plant (ETP) of refinery, petrochemical complex, fertilizer plant and other chemical plants. More particularly, the present disclosure relates to an apparatus containing packed media bed to promote the growth of microorganism for removal of odorous contaminants from industrial waste gas. More particularly, the present disclosure relates to an improved apparatus and method to promote the growth microorganism which thereby enhances degradation and bio-oxidation of odorous contaminants.
BACKGROUND OF THE INVENTION
It is well known in the industry that large amount of industrial wastewater is generated and sent to Effluent treatment plant (ETP), in petrochemicals, refineries, fertilizer plant and other chemical industries. In this process, ETP receives different type of volatile organic compounds (VOCs) dissolved in wastewater and thereafter these VOCs are emitted as waste gas to atmosphere due to their low boiling point and high vapour pressure at ambient condition. This waste gas emitted is dynamic in nature, considering its changing flowrate and composition, can create carcinogenic and mutagenic effects on human and vegetation in the proximity of emission sources. Hence, these waste gases need to be treated before letting out in environment.
Mostly, the conventional treatment of waste gas is carried out by means of chemical or physical processes. Generally, chemical process is well established and efficient technique, however, it is associated with high operating and maintenance cost and also involves the usage of hazardous chemicals. On the other hand, granular activated carbon (GAC) based adsorption technique is commonly adopted in oil gas and other chemical industries. An adsorption process is exothermic and generates heat in the process. A heat quenching system and variable air flow control may be required to regulate inlet flow and bed temperature. Due to dynamic nature of waste gas, the exact exhaustion time of GAC media bed is difficult to predict which may call for continuous monitoring of process. So, conventional GAC based VOC removal system requires high operating and maintenance cost. Moreover, during regeneration of GAC bed, the adsorbed VOC is again emitted back to the environment.

Therefore, there is a need for development of a microbiological treatment apparatus and a method as an alternative technology to conventional treatment for purifying and deodorizing a waste gas stream.
For instance, the patent literature US7276366B2 discloses a system and method by which undesirable constituents mainly FhS and sulphide are removed from gaseous effluent. The disclosed system comprises of two stage scrubber and a scrubber sump. The method comprises contacting the gas stream with a first biologically active surface, wetting the first biologically active surface with a first liquid stream, contacting the gas stream with a second biologically active surface and wetting the second biologically active surface with a second liquid stream having a pH greater than pH of first liquid stream during a predetermined time interval. The invention disclosed in this document is associated with sulphur removal bacteria such as Thiobacillus thiooxydans, Thiobacillus thioparus and Thiobacillus intermedius which are predominantly efficient in removing hydrogen sulphide. However, this type of system does not address the treatment of industrial waste gas generated in Effluent treatment plant (ETP) of refinery, petrochemical complex, fertilizer plant and other chemical plants. The dynamic nature of waste gas drastically reduces the pH of second stage effluent which may harm the microorganism life; thereby hindering the growth of microorganisms.
The present disclosure provides an apparatus and a method for deodorizing industrial waste gas generated in Effluent treatment plant (ETP) of refinery, petrochemical complex, fertilizer plant and other chemical plants. The disclosed apparatus avoids any introduction of second stage effluent to first stage to provide better pH control and uses engineered media for enhanced bacterial growth. This disclosure is associated with sulphur, nitrification and de-nitrification bacteria for destruction of different types of VOC, FhS, NH3, amines, mercaptans and other sulphidic and nitrogenous compounds present in industrial waste gas.
Another patent literature US8772015B2 discloses a media comprising of adsorbent coated core material. A method for manufacturing a biofilter media comprises soaking a core material, preferably expanded glass, in water, adding adsorbent material to the granules and water and mixing, adding a bonding agent to the adsorbent material, the granules and the water and mixing, and adding microorganisms and nutrients to the adsorbent material, the granules and water, and mixing. However, since bonding agent may block the pores of core material, this type of filter media hinders the flow of waste gas effluent; thereby increasing the pressure drop in the system. Since destruction of odorous compound is adsorption based

biological treatment process, loading of odorous compounds decreases in presence of moisture. Moreover, biofilter has its own limitations when it comes to the treatment of high contamination load, better control of pH for bacterial growth and wash out degradation by product generated in the process.
The present disclosure relates to an apparatus and a cost-effective method which offers the advantage of better pH control and uses engineered media for enhanced bacterial growth, treatment of high inlet contamination such as variety VOCs, H2S, NH3, amines, mercaptans and other organic sulphidic and nitrogenous compounds present in industrial waste gas.
The present disclosure addresses one or more problems as discussed above and other problems associated with the art by providing an apparatus and a cost effective method for deodorizing industrial waste gas generated in Effluent treatment plant (ETP) of refinery, petrochemical complex, fertilizer plant and other chemical plants.
SUMMARY OF THE INVENTION
The present disclosure discloses an apparatus for deodorizing industrial waste gas generated in Effluent treatment plant (ETP) of refinery, petrochemical complex, fertilizer plant and other chemical plants, having contamination such as variety VOCs, H2S, NH3, amines, mercaptans and other sulphidic and nitrogenous compounds.
The apparatus comprises a first stage biotrickling bed (111) for first stage irrigation mode operation; a first gas inlet conduit (101) to supply waste gas to the first stage biotrickling bed (111); a first water inlet conduit (103) to supply water to the first stage biotrickling bed (111); a second stage biotrickling bed (112) for second stage irrigation mode of operation; a second water inlet conduit (104) to supply water to the second stage biotrickling bed (112); a liquid collection tray (109) to collect second stage liquid effluent; an effluent withdrawal conduit (106) to remove/withdraw second stage liquid effluent and an exit conduit (102) to remove deodorized gas.
The present disclosure further discloses a method for deodorizing of industrial waste gas,
comprising steps of
supplying waste gas (201) through a gas inlet conduit (101) to a first stage biotrickling bed (111) for first bulk removal of organic contamination;

supplying water (203) through a first water inlet conduit (103) to the first stage
biotrickling bed (111) to maintain the moisture/ proper wetting of active media
surface;
receiving gaseous effluent from the first stage biotrickling bed (111) in a second
stage biotrickling bed (112) for removal of mostly inorganic contamination;
supplying water (204) through a second water inlet conduit (104) to the second
stage biotrickling bed (112) to maintain the moisture/ proper wetting of active
media surface;
collecting second stage liquid effluent (206) in a liquid collection tray (109);
removing/withdrawing second stage liquid effluent (206) through an effluent
withdrawal conduit (106);
removing deodorized gas through an exit conduit (102).
The above summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects and features described above, further aspects and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
The present disclosure will be further understood with reference to the accompanying drawings. More specifically, the purposes of drawings are to illustrate the preferred and alternate embodiments and are not to be construed as limitations. Furthermore, drawings are not drawn to scale.
FIG. 1 is a schematic layout of an apparatus for deodorizing industrial waste gas.
FIG. 2 is a schematic flow diagram illustrating a method for deodorizing industrial waste gas.
DETAILED DESCRIPTION OF THE INVENTION
While the disclosure is susceptible to various modifications and alternative forms, specific aspect thereof has been shown by way of example and will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the invention.

Before describing in detail embodiments, it is to be noted that a person skilled in the art can be motivated from the present disclosure and modify the various constructions of apparatus. However, such modification should be construed within the scope and spirit of the invention. Accordingly, applicant would like to mention that the examples and comparative studies are mentioned to show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such setup or device. In other words, one or more elements in a system or apparatus proceeded by "comprises... a" does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
The present disclosure discloses an apparatus for deodorizing industrial waste gas generated in Effluent treatment plant (ETP) of refinery, petrochemical complex, fertilizer plant and other chemical plants, in having contamination such as variety VOCs, H2S, NH3, amines, mercaptans and other sulphidic and nitrogenous compounds.
The apparatus comprises a first stage biotrickling bed (111) for first stage irrigation mode operation; a first gas inlet conduit (101) to supply waste gas to the first stage biotrickling bed (111); a first water inlet conduit (103) to supply water to the first stage biotrickling bed (111); a second stage biotrickling bed (112) for second stage irrigation mode of operation; a second water inlet conduit (104) to supply water to the second stage biotrickling bed (112); a liquid collection tray (109) to collect second stage liquid effluent; an effluent withdrawal conduit (106) to remove/withdraw second stage liquid effluent and an exit conduit (102) to remove deodorized gas.
The disclosed apparatus is configured to receive the waste gas through gas inlet conduit followed by gas distributor to ensure proper distribution and water through the water inlet conduit followed by liquid distributor to ensure the proper wetting of active media surface.

The disclosed apparatus is equipped with a liquid collection tray and an effluent withdrawal conduit to remove liquid effluent having low pH of second stage.
In an embodiment of the present disclosure, the apparatus is adapted with packing bed media withdrawal conduit to provide ease of media removal operation during maintenance.
FIG. 1 illustrates an apparatus (100) for deodorizing industrial waste gas as per the present disclosure. The apparatus (100) comprises a first stage biotrickling bed (111) for first stage irrigation mode operation and a second stage biotrickling bed (112) for second stage irrigation mode of operation. The apparatus is configured to receive the waste gas through a first gas inlet conduit (101) followed by a first gas distributor (113) to ensure proper gas distribution to first stage biotrickling bed (111). Water with periodically added nutrients is fed to the first stage biotrickling bed (111) and the second stage biotrickling bed (112) through a first water inlet conduit (103) and a second water inlet conduit (104) followed by a first liquid distributor (114) and a second liquid distributor (115) respectively to ensure the proper wetting of active media surface. The second stage liquid effluent is collected in a liquid collection tray (109) and withdrawn from the apparatus (100) through an effluent withdrawal conduit (106). The liquid collection tray (109) allows gas effluent to enter second stage of packing bed but restricts the flow of liquid effluent to first stage of packing bed. This feature of apparatus facilitates to maintain preferable pH range for microorganism growth in first stage bed. Treated or deodorized gas exits the apparatus (100) through an exit conduit (102). Liquid effluent from first stage of packing bed is drained through a drain conduit (105).
In an embodiment of the present disclosure, the first gas inlet conduit (101) is followed by a first gas distributor (113) to ensure proper distribution of waste gas to the first stage biotrickling bed (111).
In another embodiment of the present disclosure, the first water inlet conduit (103) is followed by a first liquid distributor (114) and the second water inlet conduit (104) is followed by a second liquid distributor (115) to ensure the proper wetting of active media surface of the first stage biotrickling bed (111).

In yet another embodiment of the present disclosure, first stage liquid effluent is drained through a drain conduit (105).
In an embodiment of the present disclosure, packing bed media of the first stage biotrickling bed (111) and the second stage biotrickling bed (112) are placed over inclined perforated plates (110 and 116, respectively). The inclination angle is in the range 5-15°
In another embodiment of the present disclosure, media withdrawal conduits (107 and 108) are provided for media removal. This conduit is placed at an angle 30-45° to provide ease of media removal operation during maintenance.
In yet another embodiment of the present disclosure, engineered media (111 and 112) which may consist of 60- 90% structured specialty plastic in form of fibre or rings and 10-40% naturally occurring media such as wood chips or volcanic rock fragments suitable for microorganism growth. The composition may be varied to design a system based on inlet loading and the concentration of contaminants.
In one embodiment of the present disclosure, a first liquid distributor (114) and a second liquid distributor (115) ensure the proper wetting of active media surface which may be selected from but not limited to ladder type, water sprinkler or any other type.
In another embodiment of the present disclosure, the apparatus (100) can efficiently remove at least 90% of inlet contaminants.
In yet another embodiment of the present disclosure, the apparatus (100) can efficiently deodorise the waste gas having concentration of 6000 ppmv of contaminants.
In one embodiment of the present disclosure, the industrial waste gas may consist of contamination such as variety VOCs, H2S, NH3, amines, mercaptans and other sulphidic and nitrogenous compounds.
In another embodiment of the present disclosure, a first stage packing bed (111) is provided with wide variety of microorganism selected from but not limited to Pseudomonas putida; Rhodococcus sp.; Bacillus sp.; Thiobacillus thioparus or combination thereof, predominantly for bulk removal of organic contaminants.

In yet another embodiment of the present disclosure, a second stage packing bed (112) is provided with wide variety of microorganism selected from but not limited to Nitrosomonas, Nitrosospira, Pseudomonas, Alkaligenes, Bacillus or combination thereof, predominantly for removal of mostly inorganic contaminants.
Microorganisms culture was taken from Applicant's own sewage treatment plant located in Engineer's India Limited office complex and compost produced inside office complex.
The present disclosure further discloses a method for deodorizing of industrial waste gas, comprising steps of
supplying waste gas (201) through a gas inlet conduit (101) to a first stage
biotrickling bed (111) for first bulk removal of contamination;
supplying water (203) through a first water inlet conduit (103) to the first stage
biotrickling bed (111) to maintain the moisture/ proper wetting of active media
surface;
receiving gaseous effluent from the first stage biotrickling bed (111) in a second
stage biotrickling bed (112) for removal of nitrogenous contamination;
supplying water (204) through a second water inlet conduit (104) to the second
stage biotrickling bed (112) to maintain the moisture/ proper wetting of active
media surface;
collecting second stage liquid effluent (206) in a liquid collection tray (109);
removing/withdrawing second stage liquid effluent (206) through an effluent
withdrawal conduit (106);
removing deodorized gas through an exit conduit (102).
The disclosed method comprises steps of receiving of industrial waste gas in first stage biotrickling bed for firstly the bulk removal of contamination through inlet gas distributor and then gaseous effluent from first stage biotrickling bed entering into second stage biotrickling bed for removal of most of the inorganic contamination as well as serve as polishing stage. A step of circulating water with periodically added nutrients into each bed is to maintain the moisture in bed required for microorganism to sustain and grow healthy. A step of withdrawing second stage liquid effluent and adding base solution to circulating water is to maintain preferable pH range for microorganism growth.

As shown in FIG. 2, the disclosed method includes introduction of industrial waste gas (201) through gas inlet conduit (101) followed by gas distributor (113) to ensure proper gas distribution to first stage biotrickling bed (111). Water with nutrients (203 and 204) is fed by using feed pump (212) to first stage biotrickling bed (111) and second stage biotrickling bed (112) through the water inlet conduit (103 and 104 respectively) followed by liquid distributor (114 and 115 respectively) to ensure the proper wetting of active surface. The second stage liquid effluent (206) having low pH is collected in a liquid collection tray (109) and sent to water tank (213). pH of circulating water with periodically added nutrients (203 and 204) is adjusted by adding base solution preferably caustic solution (209) and regulated by pH controller (210) through control valve (211). This step of method facilitates to maintain preferable pH range for enhanced microorganism growth. Treated or deodorized gas (202) exits the apparatus through exit conduit (102) and liquid effluent (205) from first stage of packing bed is routed to water tank (213). Since by-products are generated during treatment waste gas, intermittent bleed (207) is provided and make up water with nutrients (208) is added to water tank (213).
In an embodiment of the present disclosure, the first stage liquid effluent (205) and the second stage liquid effluent (206) collected in liquid collection tray (109) is sent to a water tank (213).
In another embodiment of the present disclosure, water (203 and 204) has periodically added nutrients and pH of water (203 and 204) is adjusted by adding base solution preferably caustic solution (209).
In yet another embodiment of the present disclosure, pH of water (203 and 204) is regulated by a pH controller (210) through a control valve (211).
In yet another embodiment of the present disclosure, an intermittent bleed (207) is provided and make up water with nutrients (208) is added to water tank (213).
In one embodiment of the present disclosure, the method is capable of removing contaminants such as variety VOCs, H2S, NH3, amines, mercaptans and other sulphidic and nitrogenous compounds present in industrial waste gas.
In another embodiment of the present disclosure, during start-up of the apparatus, the method requires some acclimatization time which allows the microorganisms to develop acceptance or tolerance for contaminants to be treated or components that might be toxic to them. The

time required for acclimatization is approximately 7 to 10 days depending upon type of contaminants to be treated and 10-50 % of waste gas is preferable to pass through the apparatus during the acclimatisation period.
In yet another embodiment of the present disclosure, the method includes a step of heating of circulating water to provide preferable environment of 20°C-40°C for enhanced growth of microorganisms.
The following examples are given to illustrate the present invention and should not be construed to limit the scope of the present invention.
EXAMPLES:
Accordingly, to establish the apparatus and the method for deodorizing industrial waste gas, the process was carried out in custom made apparatus according to the present disclosure having as illustrated in FIG 1. Model industrial waste gas is prepared and consists of toluene as volatile organic matter, hydrogen sulphide (H2S) as sulphidic compound and ammonia as nitrogenous compound. Tap water is used as irrigation fluid. Detail description of apparatus, feed specifications, operating window and results for different cases are tabulated below.
Table 1: Detail description of apparatus:

S. NO. ELEMENT DESCRIPTION
1 Gas sparger Gas distribution system. Type: Perforated pipe Pipe Size: 0.5 inch
2 Packing media 80% structured plastic material and 20% wood chips
3 Liquid Distributor Liquid distribution system. Type: Ladder Type Pipe Size: 0.5 inch

4 Dimension of apparatus Diameter: 200 mm Height: 3200 mm
5 Bed Length First Stage: 1000 mm Second Stage: 1000 mm
6 Microorganism source Water from Applicant's own sewage treatment plant and compost produced inside Engineer's India Limited office complex
7 Liquid inlet for first and second stage. Size: 0.5 inch
58 Gas inlet Size: 0.5 inch
Table: 2 Feed specifications

ATTRIBUTES UNIT VALUE
Flow rate of waste gas m3/hr 2.5
Flow rate of irrigation fluid (water and nutrients) lit/hr 50
pH of irrigation fluid 6.5-8.7
Composition of waste gas
Toluene ppmv 2350
H2S ppmv 100
NH3 ppmv 100
Total ppmv 2550
Table: 3 Operating Window

ATTRIBUTES UNIT VALUE

Relative Humidity 60-90%
Temperature °C 24-35 °C
Pressure Bar (g) 0.7
Empty Bed contact Time (EBCT) min -1.5
Table: 4 - Results:

ATTRIBUTES UNIT VALUE
pH of second stage effluent 3.6-4.8
pH of first stage effluent 5.2-6.3
Composition of waste gas
Toluene ppmv 205
H2S ppmv 7.3
NH3 ppmv 9.5
Total ppmv 221.8
Percentage of Removal % 91.3
As evident from the Table 4 above, pH of second stage liquid effluent is in more acidic region which may inhibit the growth of microorganism present in first stage of biotrickling bed if irrigation of first stage is done using second stage effluent. It is also evident that removal of contaminants is at least 90% of inlet concentration.
The advantages of the disclosed invention are thus attained in an economical, practical, and facile manner. While example have been shown and described, it is to be understood that various further modifications and additional configurations will be apparent to those skilled in the art.

List of Elements: 101 - first gas inlet conduit 115 - second liquid distributor
102 - exit conduit 116 - perforated plate

103 - first water inlet conduit 201 -waste gas
104 - second water inlet conduit 203, 204 - water
105 - drain conduit 205 - first stage liquid effluent
106 - effluent withdrawal conduit 206 - second stage liquid effluent
107, 108 - media withdrawal conduit 207 - intermittent bleed
109 - liquid collection tray 208 - water with nutrients
110, 116 - perforated plate 209 - base solution
111 - first stage biotrickling bed 210 - pH controller
112 - second stage biotrickling bed 211 - control valve
113 - first gas distributor 213 -watertank
114 - first liquid distributor

WE CLAIM:

1. An apparatus (100) for deodorizing of industrial waste gas, comprising
a first stage biotrickling bed (111) for first stage irrigation mode operation,
a first gas inlet conduit (101) to supply waste gas to the first stage biotrickling
bed (111),
a first water inlet conduit (103) to supply water to the first stage biotrickling bed
OH),
a second stage biotrickling bed (112) for second stage irrigation mode of
operation,
a second water inlet conduit (104) to supply water to the second stage
biotrickling bed (112),
a liquid collection tray (109) to collect second stage liquid effluent,
an effluent withdrawal conduit (106) to remove/withdraw second stage liquid
effluent,
an exit conduit (102) to remove deodorized gas.
2. The apparatus (100) as claimed in claim 1, wherein the first gas inlet conduit (101) is followed by a first gas distributor (113) to ensure proper distribution of waste gas to the first stage biotrickling bed (111).
3. The apparatus (100) as claimed in claim 1, wherein the first water inlet conduit (103) is followed by a first liquid distributor (114) and the second water inlet conduit (104) is followed by a second liquid distributor (115) to ensure the proper wetting of active media surface of the first stage biotrickling bed (111).
4. The apparatus (100) as claimed in claim 1, wherein first stage liquid effluent is drained through a drain conduit (105).
5. The apparatus (100) as claimed in claim 1, wherein packing bed media of the first stage biotrickling bed (111) is placed over inclined perforated plate (110) and of the second stage biotrickling bed (112) is placed over inclined perforated plate (116).
6. The apparatus (100) as claimed in claim 5, wherein the perforated plates (110 and 116) may be placed at an inclination angle in the range 5-15°

7. The apparatus (100) as claimed in claim 1, wherein the first stage biotrickling bed (111) is provided with a media withdrawal conduit (107) and the second stage biotrickling bed (112) is provided with a media withdrawal conduit (108) to remove media.
8. The apparatus (100) as claimed in claim 7, wherein the media withdrawal conduits (107 and 108) may be placed at an inclination angle in the range 30-45°.
9. The apparatus (100) as claimed in claim 1, wherein the first stage biotrickling bed (111) and the second stage biotrickling bed (112) comprises of 60- 90% structured specialty plastic in form of fibre or rings and 10-40%) naturally occurring media such as wood chips or volcanic rock fragments suitable for microorganism growth.
10. The apparatus (100) as claimed in claim 1, wherein the first liquid distributor (114) and the second liquid distributor (115) can be selected from a ladder type, a water sprinkler or any other type.
11. The apparatus (100) as claimed in claim 1, wherein the waste gas having concentration of 6000 ppmv of contaminants can be deodorized.
12. The apparatus (100) as claimed in claim 1, wherein the first stage packing bed (111) is provided with microorganism selected from Pseudomonas putida; Rhodococcus sp.; Bacillus sp.; Thiobacillus thioparus or combination thereof, and the second stage packing bed (112) is provided with microorganism selected from Nitrosomonas, Nitrosospiras, Pseudomonas, Alkaligenes, Bacillus or combination thereof.
13. A method for deodorizing of industrial waste gas, comprising steps of
supplying waste gas (201) through a gas inlet conduit (101) to a first stage
biotrickling bed (111) for first bulk removal of contamination;
supplying water (203) through a first water inlet conduit (103) to the first stage
biotrickling bed (111) to maintain the moisture/ proper wetting of active media
surface;
receiving gaseous effluent from the first stage biotrickling bed (111) in a second
stage biotrickling bed (112) for removal of nitrogenous contamination;
supplying water (204) through a second water inlet conduit (104) to the second
stage biotrickling bed (112) to maintain the moisture/ proper wetting of active
media surface;

collecting second stage liquid effluent (206) in a liquid collection tray (109); removing/withdrawing second stage liquid effluent (206) through an effluent withdrawal conduit (106); removing deodorized gas through an exit conduit (102).
14. The method as claimed in claim 13, wherein the first stage liquid effluent (205) and the second stage liquid effluent (206) collected in liquid collection tray (109) is sent to a water tank (213).
15. The method as claimed in claim 13, wherein water (203 and 204) has periodically added nutrients and pH of water (203 and 204) is adjusted by adding base solution preferably caustic solution (209).
16. The method as claimed in claim 13, wherein pH of water (203 and 204) is regulated by a pH controller (210) through a control valve (211).
17. The method as claimed in claim 13, wherein an intermittent bleed (207) is provided and make up water with nutrients (208) is added to water tank (213).
18. The method as claimed in claim 13, wherein water (203 and 204) is heated to provide preferable environment of 20°C-40°C for enhanced growth of microorganism.