WO2016174562A2

WO2016174562A2 - Dissolved ozone floatation effluent treatment system

Info

Publication number: WO2016174562A2
Application number: PCT/IB2016/052325
Authority: WO
Inventors: Sumit Mahendrachandra PANDEY
Original assignee: Pandey Sumit Mahendrachandra
Priority date: 2015-04-25
Filing date: 2016-04-25
Publication date: 2016-11-03
Also published as: WO2016174562A3; WO2016174562A4

Abstract

The present disclosure provides a dissolved ozone floatation effluent treatment system for treating and purifying wastewater comprising: (a) a holding tank for receiving a wastewater to be treated; (b) a contact tank having a water inlet for receiving the wastewater and a treated water outlet for outputting treated water, (c) a first re -circulation fluid line connected to the outlet of the contact tank for carrying wastewater from the contact tank; (d) an ozone injection system connected to the first re -circulation fluid line for dissolving a regulated quantity of ozone in the re-circulated stream of wastewater from the contact tank; (e) a second re-circulation fluid line for conducting the wastewater with dissolved ozone to the contact tank; (f) a container for collecting floating sludge from surface of the treated water in the contact tank; (g) an aerating means in fluid communication with the contact tank for receiving and aerating the ozone treated water; and (h) a discharge line extending from the aerating means for discharging clean water. The present disclosure further provides a method for treating and purifying a wastewater stream.

Description

DISSOLVED OZONE FLOATATION EFFLUENT TREATMENT SYSTEM

FIELD OF THE INVENTION

[001] The present disclosure pertains to systems and methods for treating wastewater. In particular, the present disclosure pertains to systems and methods that facilitate ozone treatment and purification of liquid effluent and other wastewater.

BACKGROUND OF THE INVENTION

[002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[003] Wastewater may contain human wastes, cooking wastes, insoluble substances such as, fats, oils and greases, suspended solids, animal matter, petroleum products, pesticides, paints, infectious microorganisms and any number of other wastes which are typically associated with water through common cleaning and waste disposal processes. These wastes are typically high in their biochemical oxygen demand (BOD), chemical oxygen demand (COD) and their suspended solids (SS) levels. Therefore, it is required to lower the BOD and COD levels to acceptable limits before discharging the wastewater into environmental streams or recycling the same for further industrial or domestic use.

[004] It is known that ozone can be used for oxidizing the contaminants in wastewater and for disinfection. The use of ozone at wastewater plants is increasing in popularity due to the rising demand for recycled water. Ozone injection causes inorganic contaminants to oxidize to soluble oxides and converts organic components to carbonaceous residues and carbon dioxide.

[005] While ozone has many advantages over other oxidizing agents in the treatment of wastewater, the utilization of ozone has been limited because it is expensive to generate and must be used in relatively large quantities and also the low concentration of ozone output. For example, it requires more than 30 mg of ozone per liter (>30 ppm) to achieve the removal of both the undesirable contaminants and the microorganisms aimed for. This high quantity ozone addition is associated with high investment and operating costs.

[006] Further, wastewater treatment systems that utilize ozone technology require large installations comprise several chambers, large tanks and the like, to handle different volumes of wastewater processing and normally increases the processing time. Further, the known systems are basically inefficient, have large space requirements, normally require transportation of wastewater for considerable distances, and cannot provide on-location wastewater or effluent treatment. Also, for individual and small scale wastewater producers, it is essential that the wastewater treatment system be compact and low cost to operate.

[007] There is thus a need in the art for a compact and highly efficient ozone based wastewater treatment system that can be economically employed by small to large producers of wastewater, and that effectively eliminates objectionable quantities of contaminants from wastewater. There is also a need in the art for a method of processing wastewater in a compact and high capacity system that discharges water capable of immediate reuse if desired.

[008] The present disclosure satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.

OBJECTS OF THE INVENTION

[009] It is therefore an object of the present disclosure to provide a wastewater treatment system with increased efficiency of ozone oxidation of contaminants and disinfection of pathogenic microorganisms in wastewater.

[0010] It is therefore an object of the present disclosure to provide a wastewater treatment system that requires relatively low concentration of ozone and achieves maximum ozone concentration that can be maintained.

[0011] It is a further object of the present disclosure to provide a wastewater treatment system that is compact and simple in construction.

[0012] It is another object of the present disclosure to provide a wastewater treatment system that requires relatively low concentration of ozone and thereby avoiding high costs associated with the generation of large quantities of ozone.

[0013] It is another object of the present disclosure to provide a wastewater treatment system that effectively reduces the biochemical oxygen demand (BOD), chemical oxygen demand

(COD) and total suspended solids (SS) of wastewater.

[0014] It is another object of the present disclosure to provide a wastewater treatment system that achieves effective removal of color and odor from the wastewater and also enables effective disinfection of various pathogenic microorganisms within a short retention period.

[0015] It is another object of the present disclosure to provide a wastewater treatment system that can be economically employed by small to large producers of wastewater. [0016] It is another object of the present disclosure to provide a process for purifying wastewater which efficiently reduces BOD, COD and total SS of wastewater.

SUMMARY OF THE INVENTION

[0017] The present disclosure provides a dissolved ozone floatation effluent treatment system with increased efficiency of ozone oxidation of objectionable contaminants and disinfection of pathogenic microorganisms in wastewater. The system facilitates injection of ozone into re -circulating stream of wastewater and thereby achieving maximum ozone concentration that can be maintained. The system further facilitates increased contact time between ozone and wastewater resulting in a maximum oxidation and disinfection of objectionable contaminants in the wastewater.

[0018] According to embodiments of the present disclosure, the dissolved ozone floatation effluent treatment system for treating and purifying wastewater can include: (a) a holding tank for receiving a wastewater to be treated; (b) a contact tank having a water inlet for receiving the wastewater and a treated water outlet for outputting treated water, (c) a first recirculation fluid line connected to the outlet of the contact tank for carrying wastewater from the contact tank; (d) an ozone injection system connected to the first re -circulation fluid line for dissolving a regulated quantity of ozone in the re-circulated stream of wastewater from the contact tank; (e) a second re -circulation fluid line for conducting the wastewater with dissolved ozone to the contact tank; (f) a container for collecting floating sludge from surface of the treated water in the contact tank; (g) an aerating means in fluid communication with the contact tank for receiving and aerating the ozone treated water; and (h) a discharge line extending from the aerating means for discharging clean water.

[0019] According to embodiments, the dissolved ozone floatation effluent treatment system of the present disclosure can further comprise one or more separator(s) in the contact tank. The separators can be high velocity plate separators that can provide large separation area in a small volume.

[0020] In one exemplary embodiment, the dissolved ozone floatation effluent treatment system can optionally comprise an additional contact tank along with an ozone injection system and water recirculation means that can be serially connected to the discharge line of the aerating means for further ozonating the aerated water to further reduce the BOD and COD levels if desired.

[0021] The present disclosure further provides a method for treating a wastewater comprising the steps of: (i) receiving a wastewater stream to be treated in the holding tank; (ii) re- circulating all or a portion of the wastewater through the ozone injection system using the first and second re -circulation fluid lines; (iii) injecting ozone into re-circulating stream of wastewater received in the ozone injection system in a concentration of 10 to 30 ppm; (iv) maintaining ozone in contact with the wastewater as it circulates through the contact tank for an adequate time; (v) allowing the ozone treated wastewater to pass into the aerating means; and (vi) collecting clean water from the aerating means after aerating the ozone treated wastewater.

[0022] In an embodiment of the present disclosure, the contact time between ozone and wastewater during the wastewater treatment process can be 40 minutes.

[0023] According to embodiments of the present disclosure, the method for treating wastewater can further comprise the step of introducing an ionic polymer into wastewater received in the contact tank to flocculate the suspended solids in the wastewater.

[0024] According to embodiments of the present disclosure, the method for treating wastewater can further comprise the step of periodically removing the floating sludge from the surface of treated wastewater in the contact tank and collecting it in the sludge container.

[0025] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0027] FIG. 1 is a schematic diagram of the dissolved ozone floatation effluent treatment system in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0028] Unless the context needs otherwise, throughout the specification which follow, the word "comprise" and variations thereof, such as, "comprises" and "comprising" are to be construed in an open, inclusive sense that is as "including, but not limited to."

[0029] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in numerous places throughout this specification are not necessarily all referring to the same embodiment. Additionally, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0030] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. It should also be noted that the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.

[0031] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term "about." Accordingly, in some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable.

[0032] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. "such as") provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0033] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.

[0034] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.

[0035] The present disclosure provides a dissolved ozone floatation effluent treatment system with increased efficiency of ozone oxidation of objectionable contaminants and disinfection of pathogenic microorganisms in wastewater. The system can facilitate injection of ozone into re-circulating stream of wastewater and thereby achieving maximum ozone concentration that can be maintained. The system can further facilitate increased contact time between the ozone and the wastewater resulting in a maximum oxidation and disinfection of objectionable contaminants in the wastewater.

[0036] As used herein, the term "wastewater" or "effluent" refers to a stream of waste, particularly aqueous waste disposed from domestic, municipal, commercial, industrial and agricultural uses.

[0037] FIG. 1 illustrates a preferred configuration of dissolved ozone floatation effluent treatment system 100 of the present disclosure. As shown in FIG. 1, the system 100 can include (a) a holding tank 102 for receiving a wastewater to be treated; (b) a contact tank 104 having a water inlet for receiving the wastewater and a treated water outlet for outputting treated water, (c) a first re -circulation fluid line 112 connected to the outlet of the contact tank 104 for carrying wastewater from the contact tank 104 ; (d) an ozone injection system 106 connected to the first re-circulation fluid line 112 for dissolving a regulated quantity of ozone in the re-circulated stream of wastewater from the contact tank 104; (e) a second recirculation fluid line 114 for conducting the wastewater with dissolved ozone to the contact tank 104; (f) a container 110 for collecting floating sludge from surface of the treated water in the contact tank 104; (g) an aerating means 108 in fluid communication with the contact tank for receiving and aerating the ozone treated water; and (h) a discharge line 116 extending from the aerating means 108 for discharging clean water.

[0038] According to embodiments, the holding tank 102 can be provided with a filter to separate visible particles such as leaves, plastic bags and the like from wastewater to be treated, and the filtered water can be allowed to pass into the contact tank 104 for ozone treatment.

[0039] According to embodiments, the contact tank 104 can be provided with one or more separator(s). The separators can be high velocity plate separators that can provide large separation area in a small volume. In an exemplary implementation, the separator can be provided to separate the wastewater received from the holding tank with the partially treated water.

[0040] In accordance with one or more embodiments, the dissolved ozone floatation effluent treatment system 100 can optionally include an additional contact tank along with a ozone injection system and water recirculation means that can be serially connected to the discharge line 116 of the aerating means 106 in case a further ozonation of aerated water that exits from the aerating means 106 is required to further reduce the BOD and COD levels.

[0041] The unique design of the dissolved ozone floatation effluent treatment system 100 can enable both separation of suspended solids and emulsions and oxidation of chemical compounds by ozone in wastewater.

[0042] The system 100 can be configured to achieve a maximum ozone concentration within the contact tank 104 by re-circulating all or a portion of wastewater through the ozone injection system 106 to receive additional injections of ozone. Since ozone has strong oxidizing potential and very short half life, dissolved ozone in wastewater may decompose into active oxygen and thereby further reducing the COD and BOD levels and also increasing the oxygen level of the treated water.

[0043] The system 100 can be configured to provide adequate contact time between ozone and wastewater in the contact tank 104 for efficient oxidation and removal of undesirable contaminants from wastewater. The adequate retention time or contact time between ozone and wastewater can allow for effective oxidation of organic and inorganic contaminants, disinfection of various pathogens, effective removal of suspended solids (SS), emulsions, color and odor from wastewater.

[0044] In accordance an embodiments of the present disclosure, the aerating means 108 can be connected a gas source and can supply a continuous flow of pressurized air to produce air bubbles to agitate, circulate, and aerate the wastewater flowing through the aerating means 108. Ozone treated water contained in the aerating means 108 can be aerated for a selected period of time in order satisfies any particular environmental regulations.

[0045] Levels of COD, BOD, suspended solids (SS), pathogens and other possible contaminants in the reclaimed water can conform to quality standards and hence the reclaimed water can be safely reused or discharged into environmental streams.

[0046] The present disclosure further provides a method for treating a wastewater using the dissolved ozone floatation effluent treatment system 100 of the present disclosure, wherein the method can comprise the steps of: (i) receiving a wastewater stream to be treated in the holding tank 102; (ii) re -circulating all or a portion of the wastewater through the ozone injection system through the first and second re-circulation fluid lines, 112 and 114 respectively; (iii) injecting ozone into re-circulating stream of wastewater received in the ozone injection system 106 in a concentration of 10 to 30 ppm; (iv) maintaining ozone in contact with the wastewater as it circulates through the contact tank 104 for an adequate time; (v) allowing the ozone treated water to pass into the aerating means 108; and (vi) collecting clean water from the aerating means 108 after aerating the ozone treated water.

[0047] In accordance with one or more embodiments, the contact time between ozone and wastewater during the wastewater treatment process can be 40 minutes.

[0048] According to embodiments of the present disclosure, the method for treating wastewater can further comprise the step of introducing an ionic polymer into wastewater received in contact tank 104 to flocculate the suspended solids in the wastewater. As ozone micro bubbles adsorb to surfaces of solid particles, it tends to cause the solid particles to become buoyant and float towards the top of contact tank 104. The polymer can be cationic or anionic and it may be added to wastewater in contact tank 104 as a pure liquid stream or as an aqueous stream containing the polymer.

[0049] In accordance with one or more embodiments, floating materials and sludge can be periodically removed from the surface of treated wastewater in the contact tank 104 and can be collected in the sludge container 110 during the treatment process. A skimmer may be used to remove the sludge and other floating materials from the surface of treated wastewater.

[0050] If additional contact tank and ozone injection system are used, aerated water that exits from aerating means 106 through discharge line 116 can pass into the additional contact tank and the aerated water can be re-circulated through the additional ozone injection system to undergo repeated cycles of ozone injection which can range from 10 to 20 ppm.

ADVANTAGES OF THE PRESENT INVENTION

[0051] The present disclosure provides a dissolved ozone effluent treatment system that is compact and low cost to operate.

[0052] The present disclosure provides a dissolved ozone effluent treatment system that mitigates the capital and operating expenses associated with use of ozone technologies.

[0053] The present disclosure provides a dissolved ozone effluent treatment system that requires relatively less quantities of ozone compared to the known systems and provides highly efficient ozone oxidation of the contaminants. [0054] The present disclosure provides a dissolved ozone effluent treatment system that can remove a wide range of contaminates from wastewater.

[0055] The present disclosure provides a dissolved ozone effluent treatment system that achieves effective removal of suspended solids (SS), color, odor from the wastewater and also enables effective disinfection of various pathogenic microorganisms within a short retention time.

[0056] The present disclosure provides a dissolved ozone effluent treatment system that facilitates thickening of the sludge and thereby making storage and disposal of waste easier.

[0057] The output water from the dissolved ozone effluent treatment system of the present disclosure meets the quality standards for reuse.

[0058] The present disclosure provides a dissolved ozone effluent treatment system that overcomes the drawbacks of the prior art.

Claims

I Claim:

1. A dissolved ozone floatation effluent treatment system comprising - a holding tank for receiving wastewater to be treated;

a contact tank having an inlet for receiving the wastewater from the holding tank;

an ozone injection system configured to receive the wastewater from an outlet of the contact tank through a first re-circulating fluid line, dissolve a regulated quantity of ozone in wastewater present inside the first re-circulated fluid line, and output partially treated wastewater through a second re -circulating fluid line to the contact tank, wherein the partially treated wastewater is wastewater with dissolved ozone;

a mean for periodically removing floating sludge from the treated water from surface of the contact tank;

an aerating means in fluid communication with the contact tank for receiving and aerating the partially treated water; and

a discharge line extending from the aerating means for discharging clean water after the aerating of the partially treated water.

2. The system of claim 1, wherein the system further comprises one or more separator(s) in the contact tank, wherein the one or more separator(s) is high velocity plate separator that provide large separation area in a small volume to separate the wastewater received from the holding tank with the partially treated water.

3. The system of claim 1, wherein the system further comprises an additional contact tank attached with the ozone injection system, and a water recirculation mean that is serially connected to the discharge line of the aerating means to output the aerated water for reprocessing by the ozone injection system to further reduce biochemical oxygen demand (BOD) level and chemical oxygen demand (COD) level, if desired.

4. The system of claim 1, wherein the regulated quantity of ozone is dissolved in the water wastewater present inside the first re-circulating fluid line to achieve a concentration of 10 to 30 ppm in the partially treated water.

5. The system of claim 1, wherein the ozone injection system is configured to dissolve the regulated quantity of ozone in the wastewater present inside the first re-circulating fluid line by maintaining contact of ozone with the wastewater present inside the first re -circulating fluid line for an adequate time.

6. The system of claim 1, wherein the system further comprises a means for introducing an ionic polymer into the wastewater stored in the contact tank to flocculate suspended solids in the wastewater.

7. A method for dissolved ozone floatation effluent treatment, the method comprising steps of - receiving wastewater to be treated in a holding tank; receiving the wastewater from the holding tank into a contact tank through an inlet;

outputting the wastewater from the contact tank through an outlet; receiving the wastewater from the outlet of the contact tank through a first re-circulating fluid line, at an ozone injection system ;

dissolving, by the ozone injection system, a regulated quantity of ozone in wastewater present inside the first re-circulated fluid line; outputting partially treated wastewater through a second re -circulating fluid line to the contact tank, wherein the partially treated wastewater is wastewater with dissolved ozone;

periodically removing floating sludge from the treated water from surface of the contact tank;

aerating the partially treated water; and

discharging clean water after the aerating of the partially treated water.

8. The method of claim 7, wherein the method further comprises steps of recirculating the aerated water for reprocessing by the ozone injection system to further reduce biochemical oxygen demand (BOD) level and chemical oxygen demand (COD) level, if desired.

9. The method of claim 7, wherein the regulated quantity of ozone is dissolved in the water wastewater present inside the first re-circulating fluid line to achieve a concentration of 10 to 30 ppm in the partially treated water.

10. The method of claim 7, wherein the ozone injection system is configured to dissolve the regulated quantity of ozone in the wastewater present inside the first re-circulating fluid line by maintaining contact of ozone with the wastewater present inside the first re -circulating fluid line for an adequate time.

11. The system of claim 1, wherein the method further comprises step of introducing an ionic polymer into the wastewater stored in the contact tank to flocculate suspended solids in the wastewater.