CLIAMS:1. A system (100) for advanced sewage treatment, recovery and recycling of sewage containing biodegradable and non-biodegradable pollutants, said system (100) comprising a primary treatment means, a secondary treatment means, and a tertiary treatment means for treating sewage to provide clear, disinfected and reusable water,

wherein,

said primary treatment means including screening means (116) for separating suspended inorganic and organic matter from the sewage/effluent to obtain screened sewage/effluent;

said secondary treatment means including: equalization means (101) for equalization of said screened sewage/effluent to obtain equalized sewage, settling means (110) for settling suspended solids in said equalized sewage/effluent to obtain a clarified sewage/effluent, and a first filtering means (114) for filtering said clarified sewage/effluent to obtain a further clarified sewage/effluent; and

said tertiary treatment means including: an oxidation reactor (125) in operative communication with a radiation unit (129), where said further clarified sewage/ effluent is oxidized in said oxidation reactor (125) and a portion of said oxidized sewage/effluent from said oxidation reactor (125) is continuously conveyed through said radiation unit (129) for exposing to UV radiations to effect oxidation and break-down of complex organic molecules in said sewage/effluent to produce a treated sewage/effluent having set standards, and a second filtering means (134) for filtering said treated sewage/effluent to remove solids, odor and color, and provide the clear, disinfected and reusable water.
2. The system (100) as claimed in claim 1, wherein said screening means (116) include a bar screen.

3. The system (100) as claimed in claim 1, wherein said equalization means (101) further comprise aeration means (117) for aerating the sewage/effluent.

4. The system (100) as claimed in claim 1, wherein said secondary treatment means further comprise a coagulant dosing means (104 & 105) for adding a coagulant to said equalized sewage/effluent from said equalization means (101).

5. The system (100) as claimed in claim 1, wherein said secondary treatment means further comprise a flocculant dosing means (106 & 107) for adding a flocculant to said equalized sewage/effluent from said equalization means (101).

6. The system (100) as claimed in claims 4 & 5, wherein said secondary treatment means further comprise a mixing unit (108) and a flocculation tank (109) for allowing formation of stable flocs of the suspended solids, said mixing unit (108) and said flocculation tank (109) being located prior to said settling means (110) into which said equalized sewage/effluent containing flocs flows.

7. The system (100) as claimed in claim 1, wherein said secondary treatment means further comprise a sludge collection and digestion tank (102) provided in operative communication with said settling means (110) for collecting and digesting the settled suspended solids.
8. The system (100) as claimed in claim 1, wherein said secondary treatment means further comprise a clarified sewage/effluent tank (112) for receiving said clarified sewage/effluent from said settling means (110) prior to filtering said clarified sewage/effluent in said first filtering means (114).

9. The system (100) as claimed in claim 1, wherein said first filtering means (114) include a pressure sand filter.

10. The system (100) as claimed in claim 1, wherein said tertiary treatment means further comprise an oxidant dosing means (122 & 123) for adding an oxidant to said further clarified sewage/effluent from said first filtering means (114).

11. The system (100) as claimed in claim 10, wherein said tertiary treatment means further comprise a bag filter (124) for filtering oxidant-dosed further clarified sewage/effluent from said oxidant dosing means (122 & 123).

12. The system (100) as claimed in claim (1), wherein said tertiary treatment means further comprise ozone generation means (132 & 133) for generating ozone which is circulated in said oxidation reactor (125) via an eductor (126).

13. The system (100) as claimed in claim (1), wherein said second filtering means (134) include an activated carbon filter.
,TagSPECI:TECHNICAL FIELD

The present disclosure relates to a system for treatment of sewage/wastewater.
More particularly, the present disclosure relates to a system for advanced treatment of domestic sewage/effluent by using photochemical oxidation/paraozone oxidation.

BACKGROUND

Water scarcity is a major global issue which affects every continent. Worldwide, agriculture, thermoelectric plants and industry account for most of the fresh-water consumption. Only about 10% of the fresh-water consumption is for domestic use like cleaning, washing, drinking, and sanitation. The water scarcity can be reduced if sewage/effluent or used water is treated to be reusable for agriculture, power generation, industry and domestic purposes.

The sewage is water carrying waste from human use. This contains inorganic matter like plastic, glass, metal, concrete, and organic matter like human waste, animal waste, food waste, paper, yard waste, chemicals, nutrients, oil and grease. Typically, sewage water comprises 99% water and 1% solids including the inorganic and organic matter. The sewage/effluent must be treated completely before discharging in river, ocean or sea.

The conventional sewage/effluent treatment comprises screening and/or sedimentation to remove the inorganic matter and settable solids, and a biological treatment with micro-organisms to degrade the organic matter to remove the nutrients from the sewage/effluent. The treated sewage/effluent confirming with the disposal standards is then discharged in the water bodies. Additional treatment steps such as coagulation and flocculation may be incorporated if the sewage comprises chemicals, heavy metals, and pesticides.

However, recently, as urbanization has advanced and the living standards have risen, the concentration of sewage/effluent contamination, and the increased inflow of sewage/effluent, and the various sources of sewage/effluent have increased. The increased use of chemicals/cosmetics has resulted in inclusion of non-biodegradable waste in the domestic sewage/effluent.

The conventional sewage/effluent treatment, therefore, cannot meet the treatment needs of today. Also, the conventional sewage treatment does not provide treated sewage/effluent which complies with the standards for reuse.

Other drawbacks of the conventional sewage/effluent treatment include: the treatment is not adaptable with the load fluctuation, thereby unable to handle fluctuating load condition or intermittent/inadequate sewage/effluent generation; the treatment plant occupies a large footprint; in case of process upsets - its identification and correction takes about 20 - 30 days; sludge treatment and disposal is tedious and very costly; the biological treatment gives foul odors, thus the treatment plant must be located away from the city/residence; process efficiency is between 60 – 70%; possibility of bacterial contamination in the water bodies; the plant size cannot be easily augmented to handle greater load; and tertiary treatments to provide treated effluent/sewage suitable for reuse are extensive and expensive.

There is therefore felt a need to provide a system for “Advanced Sewage Treatment” which will address the above-noted problem with respect to conventional biological sewage/effluent treatment.

OBJECTS

An object of the present disclosure, which an embodiment herein satisfies, is to provide a system for advanced sewage treatment, recovery and recycling of sewage/effluent comprising biodegradable and non-biodegradable pollutants, which - gives treated sewage suitable for recycling and reuse, does not require bacterial cultivation, thus does not generate secondary sludge and foul smell, does not depend upon the environmental conditions, can be operated in batch or continuous mode depending upon the sewage generation, provides 90 – 98% efficiency, can be augmented to handle more load, can handle shock loads, and in case of process upsets, the problem is identified and rectified within a few hours.

These and other objects of the present disclosure will be more apparent from the following description.

SUMMARY

In accordance with the present disclosure, there is disclosed a system for advanced sewage/effluent treatment of sewage containing biodegradable and non-biodegradable pollutants, said system comprising a primary treatment means, a secondary treatment means, and a tertiary treatment means for treating sewage/effluent to provide clear, disinfected and reusable sewage/effluent,
wherein,

said primary treatment means including screening means for separating suspended inorganic and organic matters from the sewage to obtain screened sewage/effluent;

said secondary treatment means including: equalization means for equalization of said screened sewage/effluent to obtain equalized sewage, settling means for settling suspended solids in said equalized sewage/effluent to obtain a clarified sewage/effluent, and a first filtering means for filtering said clarified sewage/effluent to obtain a further clarified sewage/effluent; and

said tertiary treatment means including: an oxidation reactor in operative communication with a radiation unit, where said further clarified sewage/effluent is oxidized in said oxidation reactor and a portion of said oxidized effluent from said oxidation reactor is continuously conveyed through said radiation unit for exposing to UV radiations to effect oxidation and break-down of complex organic molecules in said effluent to produce a treated sewage/effluent having set standards, and a second filtering means for filtering said treated sewage/effluent to remove solids, odor and color, and provide the clear, disinfected and reusable sewage/effluent.

Typically, in accordance with the present disclosure, said screening means include a bar screen.

Preferably, in accordance with the present disclosure, said equalization means further comprise aeration means for aerating the sewage/effluent.

Typically, in accordance with the present disclosure, said secondary treatment means further comprise a coagulant dosing means for adding a coagulant to said equalized sewage/effluent from said equalization means.

Additionally, said secondary treatment means comprise a flocculent dosing means for adding a flocculent to said equalized sewage/effluent from said equalization means. Still further, said secondary treatment means comprise a mixing unit and a flocculation tank for allowing formation of stable flocs of the suspended solids, said mixing unit and said flocculation tank being located prior to said settling means into which said equalized sewage/effluent containing flocs flows.

In accordance with the present disclosure, said secondary treatment means comprise a sludge collection and digestion tank provided in operative communication with said settling means for collecting and digesting the settled suspended solids.

Preferably, in accordance with the present disclosure, said secondary treatment means further comprise a clarified sewage/effluent tank for receiving said clarified sewage/effluent from said settling means prior to filtering said clarified sewage/effluent in said first filtering means.
Typically, in accordance with the present disclosure, said first filtering means include a pressure sand filter.

Preferably, in accordance with the present disclosure, said tertiary treatment means further comprise an oxidant dosing means for adding an oxidant to said further clarified sewage/effluent from said first filtering means. Additionally, said tertiary treatment means comprise a bag filter for filtering oxidant-dosed further clarified sewage/effluent from said oxidant dosing means.

Typically, in accordance with the present disclosure, said tertiary treatment means comprise ozone generation means for generating ozone which is circulated in said oxidation reactor via an “eductor”.

Preferably, in accordance with the present disclosure, said second filtering means include an activated carbon filter.

BRIEF DESCRIPTION OF THE DRAWING

The disclosure will now be described with the help of the accompanying drawing, in which,

FIGURE 1 illustrates a preferred embodiment of the system for advanced sewage treatment, in accordance with the present disclosure.

DETAILED DESCRIPTION

The embodiment herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiment in the following description. Descriptions of well-known components and techniques are omitted so as to not unnecessarily obscure the embodiment herein. The examples used herein are intended merely to facilitate an understanding of the ways in which the embodiment herein may be practiced and to further enable those of skill in the art to practice the embodiment herein. Accordingly, the examples should not be construed as limiting the scope of the embodiment herein.

The description herein after, of the specific embodiment will so fully reveal the general nature of the embodiment herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiment without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiment. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiment herein has been described in terms of preferred embodiment, those skilled in the art will recognize that the embodiment herein can be practiced with modification within the spirit and scope of the embodiment as described herein.

The present disclosure relates to a system for advanced treatment of domestic sewage comprising both biodegradable and non-biodegradable pollutants. The present disclosure provides a physico-chemical treatment as opposed to the conventional biological process which typically uses an activated sludge treatment that is time-consuming, generates excess sludge, foul smell, and requires thriving microorganisms for process efficiency. The present disclosure does not require cultivation of microorganisms, thereby eliminating the secondary sludge and foul smell, and requirement of environmental conditions that favor growth of the microorganisms. Also, the system of the present disclosure can be operated in a batch or continuous mode depending on the load conditions. The system of the present disclosure provides 90 – 98% efficiency as compared to the 60 – 70% efficiency obtained by the conventional biological process. Further, the system for the present disclosure in modular, therefore the capacity of the system can be easily augmented leaving space for expansion. The system is adapted to handle shock loads, and if the process upsets, the system is adapted to rectify the error within a few hours, where, if the conventional biological process gets upset by shock loads, it may require about 20 to 30 days for correction. The system of the present disclosure occupies a smaller footprint, about 20 – 30% less than the conventional systems. The treated sewage is clear and disinfected, and can be used for sanitation, gardening, industry, agriculture, washing, cleaning, power generation, and the like. The system can be positioned below ground level, since it does not require atmospheric oxygen.

A preferred embodiment of the system for advanced sewage treatment is illustrated in the FIGURE 1, the system being generally referenced by the numeral 100. The sewage/effluent containing the biodegradable and the non-biodegradable pollutants is treated by means of a physico-chemical process. The sewage/effluent received at line 120 is passed through a primary treatment means which includes screening means 116 for separating the suspended inorganic and organic matter from the sewage/effluent. The screening means 116 is typically a bar screen for removing plastic, glass, gravel, paper, plants, and such materials which are large in size and therefore difficult to degrade, or non-degradable. The screened sewage/effluent is then passed through a secondary treatment means. The secondary treatment means include equalization means 101 which allows a four to eight hours retention to the screened sewage/effluent to achieve equalization of the sewage/effluent. The equalization means 101 is provided in communication with aeration means 117 for aerating the sewage/effluent, thereby providing complete equalization. The equalization process gives uniform sewage/effluent characteristics which helps at increasing the efficiency of the treatment.

The secondary treatment means further comprise a settling means 110. The equalized sewage/effluent is pumped to the settling means 110 by means of a settling tank feed pump 103. The equalized sewage/effluent is settled in the settling means 110 to separate suspended solids and obtain a clarified sewage/effluent. Suspended solids, which contribute to about 50 to 60% BOD (biochemical oxygen demand), are made to settle down by addition of chemicals such as coagulants and flocculants. A coagulant dosing means including a coagulant dosing tank 104 and a coagulant dosing pump 105 are provided for adding a coagulant to the equalized sewage/effluent prior to the settling means 110. The coagulant is typically selected from alum or poly aluminium chloride (PAC). The coagulant neutralizes the negative charge of the suspended solids, thereby reducing the zeta-potential and resulting in the formation of flocs. A flocculant dosing means including a flocculant dosing tank 106 and a flocculant dosing pump 107 are provided subsequent to the coagulant dosing means for adding a flocculant to the coagulant-dosed sewage/effluent. The flocculant is typically a polymer which traps the flocs with its long-chain structure and increases the density of the flocs to produce macroflocs that settle easily.

The coagulant and flocculant dosed sewage/effluent is then received in a mixing unit 108 where the sewage/effluent is subjected to rigorous mixing by air received via a blower 118. The retention time in the mixing unit 108 is between 1 to 3 minutes. The mixed sewage/effluent is then conveyed to a flocculation tank 109 for allowing formation of stable flocs of the suspended solids. The retention time of the sewage/effluent in the flocculation tank 109 is between 10 – 20 minutes. In the flocculation tank 109, gentle mixing by means of air from the blower 118 is provided to effect building of stable macroflocs of the suspended solids. The sewage/effluent with the macroflocs is then settled in the settling means 110 to clarify the effluent and settle the sludge.

In the settling means 110, a retention time of between 1 – 2 hours is provided to allow the macroflocs in the sewage/effluent to settle. The settling means 110 typically comprise a tube settler for enabling the solid-liquid separation. The tube settler utilizes slanted tubular media to achieve a laminar flow in the media within a short distance, thereby obtaining better separation. The media traps the flocs, which accumulate on the surface of the media and slide down due to gravity. The separated suspended solids are collected at the bottom of the settling means 110. These suspended solids are removed via a discharge means 111 at regular intervals and collected in a sludge collection and digestion tank 102. The sludge collected in the tank 102 is digested, typically an-aerobically.

The clarified effluent from the settling means 110 is collected in a clarified effluent tank 112. The clarified effluent is further clarified by filtering through a first filtering means 114 to remove the flocs and finely suspended particles. The clarified sewage/effluent from the clarified sewage/effluent tank 112 is pumped to the first filtering means 114 by filter feed pump 113. The first filtering means 114 is typically a pressure sand filter. The clarified sewage/effluent is passed through the first filtering means 114 to remove particles having size between about 40 to 50 microns. The first filtering means 114 must be periodically backwashed with water to remove the clogging.

The further clarified effluent is pumped by a reactor feed pump 121 to a tertiary treatment means including an oxidation reactor 125 in operative communication with a radiation unit 129. An oxidant dosing means including an oxidant dosing tank 122 and an oxidant dosing pump 123 is provided prior to the oxidation reactor 125 for adding an oxidant to the further clarified effluent. The oxidant is typically selected from sodium hypochlorite or hydrogen peroxide. The oxidant-dosed effluent is passed through a bag filter 124 for removing fine particles having size between 10 – 25 microns, so that the particles do not cause interference with the UV lamps in the radiation unit 129. The effluent from the bag filter 124 is then conveyed to the oxidation reactor 125.

The effluent is provided a retention time of 10 – 20 minutes in the oxidation reactor 125. Ozone generated by ozone generation means including a concentrator 132 and ozonator 133 is circulated in the oxidation reactor 125 via an eductor 126. The ozone is also re-circulated in the oxidation reactor 125 through the eductor 126 via an ozone recirculation pump 127. Atmospheric air is taken through line 130 in the concentrator 132 to generate oxygen. The oxygen from the concentrator 132 is conveyed to the ozonator 133 for generating ozone. This ozone is injected in the oxidation reactor 125 via the eductor 126. A portion of the oxidized effluent from the oxidation reactor 125 is pumped via a radiation unit feed pump 128 to the radiation unit 129. The irradiated effluent is recycled to the oxidation reactor 125. The cycle is continued till treated sewage/effluent of desired set standards is obtained. The radiation unit 129 uses UV radiations for effecting advanced oxidation to break-down complex organic molecules in the effluent to simple chain molecules. The treated effluent may be continually or intermittently discharged from the oxidation reactor 125. The treated sewage/effluent from the oxidation reactor 125 is then filtered in a second filtering means 134. The second filtering means 134 is typically an activated carbon filter which is adapted to adsorb the simple chain molecules. The second filtering means 134 also removes odor and color from the treated effluent to provided treated sewage/effluent which is clear, disinfected and reusable. The treated sewage/effluent is collected in a treated sewage/effluent collection tank 136. The first filtering means 114 and the second filtering means 134 must be backwashed after a running time of about 20 – 25 hours or when the pressure difference exceeds. The treated sewage/effluent can be pumped via backwash feed pump 135 for cleaning the first filtering means 114 and the second filtering means 134. The backwash water must contain less than 25 mg/l of suspended solids. The backwash drain may be treated by adding to the system 100 at the equalization means 101, shown by line 137.

The present disclosure will now be described with respect to the following non-limiting example. The example should not be construed as limiting the scope of the embodiment herein.

EXAMPLE 1

The system of the present disclosure was used to treat domestic sewage. The results are shown in Table 1.

Table 1:

ECONOMIC SIGNIFICANCE AND TECHNICAL ADVANCEMENT

A system for advanced sewage treatment of sewage comprising biodegradable and non-biodegradable pollutants, as described in the present disclosure, has several technical advantages including, but not limited to, the realization of:
provides a physico-chemical treatment for giving treated sewage suitable for recycling and reuse;
the treatment does not require bacterial cultivation, thus does not generate secondary sludge and foul smell;
the treatment does not require thriving microorganisms, thus does not depend upon the environmental conditions;
the system can be operated in a batch or continuous mode depending upon the sewage generation;
the system provides 90 – 98% efficiency;
the system occupies a smaller footprint, about 20 – 30% less than the conventional systems;
the system can be positioned below ground level;
the system is modular and can be augmented to handle more load, thereby leaving space for expansion;
the system is adapted to handle shock loads; and in case the process upsets, the system is adapted to identify the problem and rectify it within a few hours.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results.

Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the invention as it existed anywhere before the priority date of this application.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the invention, unless there is a statement in the specification specific to the contrary.

In view of the wide variety of embodiments to which the principles of the present invention can be applied, it should be understood that the illustrated embodiment is exemplary only. While considerable emphasis has been placed herein on the particular features of this invention, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiment without departing from the principle of the invention. These and other modifications in the nature of the invention or the preferred embodiment 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.