WO2020084459A1 - A system for removal of pathogens from water - Google Patents

Abstract

A system for removal of pathogens from water is provided. The system includes a bio settler configured to mechanically and biologically treat the water and pass it to an anaerobic fluidized baffled reactor configured to combine the treated water released with sludge to decompose the organic pollutants present in the treated water received from the bio settler. The system also includes an anaerobic fixed film reactor, comprising an anaerobic filter, configured to treat non-settleable and dissolved solids. The system also includes a slow sand filter comprising a sand bed, wherein the slow sand filter being configured to percolate the treated water released by the anaerobic fixed film reactor through the sand bed, thereby removing turbidity and pathogenic organisms. The present system is a natural water treatment system and does not use any chemicals or energy source for removing the pathogens present in the water. Therefore, it is cost effective and eco-friendly.

Description

A SYSTEM FOR REMOVAL OF PATHOGENS FROM WATER

This International Application claims priority from a Complete patent application filed in India having Patent Application No. 201841039807, filed on October 22, 2018 and titled “A SYSTEM FOR REMOVAL OF PATHOGENS FROM WATER”.

FIELD OF INVENTION

Embodiments of the present disclosure relate to water filtration, and more particularly to, a system for removal of pathogens from water.

BACKGROUND Treatment of wastewater or sewage water has become a very important issue over a period of time due to ever-increasing quantum of urban population and factories. The sewage is contributing significantly to environmental pollution and to address this issue several systems and methods are being used nowadays. However, the Wastewater treatment methods or Sewage treatment plants are encountering operational challenges of energy consumption, staffing (skilled human resources), sludge production and environmental footprint.

Disinfecting the water after waste water treatment is a big challenge as harmful chemicals like Chlorine are required currently. When chlorine is used carcinogenic Trihalomethanes (THMs) are generated. Some states like Maharashtra has banned used of Chlorine in STPs (Sewage Treatment Plants). The other disinfection choices like UV or Ozonation are expensive as they consume lots of power.

The two methodologies used for disinfection are: a) Anaerobic Digestion process that microbially degrades organic matter without the use of oxygen. The anaerobic process also reduces and inactivates pathogens (Grady et al., 1999). Anaerobic digestion process has been considered as one of the processes of reducing pathogens (Dahab et el., 1996; Eliot, 2003). Ponugoti et al, (1997) and Berg, (1980) showed that indicator bacteria were reduced by 1 to 3 log due to anaerobic digestion. USEPA, mesophilic anaerobic digestion is considered as a part of process to significantly reducing pathogens (PSRP) (Dahab et al, 1996; Eliot, 2003). Berg and Berman (1980) reported that anaerobic digestion inactivated 1.44 to 2.3 Log of fecal coliform, 1.05 to 1.36 Log of Entrovirus and 0.92 to 2.08 Log of Salmonella. Also, Ponoguti et al. (1997) indicated that anaerobic digestion reduced many pathogenic organisms and indicator bacteria by 1 to 3 Log (Ponugoti et al, 1997; Berg, 1980). b) Slow sand filtration is a biological treatment process. Typically, a slow sand filter has a depth of about 0.7 meters and is operated at flow rates of 0.1 to 0.3 meters/hour compared to 5-15 meters/hour in rapid filters. The sand is mixed in size ranging from 0.15 to 0.35 mm. By slow sand filtration, microorganisms are removed because they are not able to pass pores between the sand grains (straining), and by attachment to sand grains. However, the existing sewage treatment plants requires costly setups and maintenance of the same is also not easy. It also requires, frequent monitoring by an expert. Lurther, in most of the cases the treated effluent is not able to meet Total Nitrogen (TN) targets, Total Phosphorus (TP) targets, biochemical oxygen demand (BOD) targets. Presence of high ammonia and high nitrate is also noticed. Adding to this the presence of pathogens in water makes the water available only for limited use.

Therefore, there is a need for an effective a system for removal of pathogens from water.

BRIEF DESCRIPTION In accordance with one embodiment of the present disclosure, a system removal of pathogens from water is provided. The system includes a bio settler for mechanically treating untreated water by filtering contaminants presents in the untreated water by at least one of sedimentation and flotation and biologically treating the untreated water through anaerobic microorganisms configured to partially decompose organic pollutants present in the untreated water. The system also includes an anaerobic fluidized baffled reactor to combine the treated water released by the bio settler with sludge, wherein the sludge comprises bacterial mass configured to decompose the organic pollutants present in the treated water. The system also includes an anaerobic fixed film reactor comprising an anaerobic filter, wherein the anaerobic fixed film reactor treats non-settleable and dissolved solids, present in the treated water released by the anaerobic fluidized baffled reactor, by bringing the non-settleable and dissolved solids in contact with an active bacterial mass fixed on the anaerobic filter and a sand filter comprising a sand bed, wherein the sand filter percolates the treated water released by the anaerobic fixed film reactor through the sand bed, thereby removing turbidity and pathogenic organisms present in the treated water released by the anaerobic fixed film reactor.

To further clarify the advantages and features of the present disclosure, a more particular description of the disclosure will follow by reference to specific embodiments thereof, which are illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the disclosure and are therefore not to be considered limiting in scope. The disclosure will be described and explained with additional specificity and detail with the appended figures. BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:

FIG. 1 is a schematic representation of a system for removal of pathogens from water in accordance with an embodiment of the present disclosure; Fig. 2 is a schematic representation of the bio-settler in accordance with an embodiment of the present disclosure; Fig. 3 is a schematic representation of the anaerobic fluidized baffled reactor in accordance with an embodiment of the present disclosure;

Fig. 4 is a schematic representation of the anaerobic fixed film reactor in accordance with an embodiment of the present disclosure; and Fig. 5 is a schematic representation of the slow sand filter in accordance with an embodiment of the present disclosure.

Further, those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein. DETAILED DESCRIPTION

For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the disclosure as would normally occur to those skilled in the art are to be construed as being within the scope of the present disclosure.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more devices or sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, sub-systems, elements, structures, components, additional devices, additional sub-systems, additional elements, additional structures or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.

In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. The singular forms“a”,“an”, and“the” include plural references unless the context clearly dictates otherwise. FIG. 1 is a schematic representation of a system (100) for removal of pathogens from water in accordance with an embodiment of the present disclosure. The system (100) for removal of pathogens from water includes a bio settler (102), an anaerobic fluidized baffled reactor (104), an anaerobic fixed film reactor (106) and a slow sand filter (108). The bio settler (102) is configured to process two main treatments for the untreated water received via an inlet. The first process is a mechanical treatment to treat the untreated water by filtering contaminants present in the untreated water by sedimentation or flotation and the wastewater from the clarified layers flows through an outlet. The second process is a biological treatment to treat the untreated water through anaerobic microorganisms which are configured to partially decompose organic pollutants present in the untreated water, thereby resulting in a digestion process which ensures that accumulated sludge from the untreated water is reduced and stabilized. The accumulated sludge is removed after the bio settler is used for at least 18 to 24 months. During the digestion process of filtering the biogases are produced, which are let out through the gas vents provided in the system.The average reduction of organic content (Biochemical Oxygen Demand, BOD and Chemical Oxygen Demand, COD) is between 25% and 40%, the bio settler (102) is resistant to shock load and variable inflow. The anaerobic fluidized baffled reactor (FBR) (104) comprises a series of chambers, in which the wastewater flows upstream. Each chamber from the series of chamber comprises activated sludge at the bottom of each chamber. The anaerobic fluidized baffled reactor (104) is configured to intensively mix up the treated water released by the bio settler (102) with the activated sludge, wherein it is inoculated with bacterial mass which decomposes the organic pollutants left in the treated water released by the bio settler (102). The biochemical oxygen demand reduction rate of the anaerobic fluidized baffled reactor can be up to 90%. The anaerobic fluidized baffled reactor (104) is resistant to shock load and variable inflow and the operation and maintenance of the anaerobic fluidized baffled reactor (104) is uncomplicated.

The anaerobic fixed film reactor (106) is also known as a fixed bed and has a similar flow pattern to the anaerobic fluidized baffled reactor (104). The anaerobic fixed film reactor (106) is an anaerobic filter, wherein the filter materials, including but not limited to, such as gravel, rocks or specially formed plastic pieces provide an additional surface area for bacteria to settle. The anaerobic fixed film reactor (106) is configured to treat non-settleable and dissolved solids, present in the treated water released by the bio settler (102). The non-settleable and dissolved solids are treated by bringing them in close contact with a surplus of active bacterial mass fixed on the filter material. The biochemical oxygen demand removal rate is in the range of 70%-90%

The slow sand filter (108) includes a sand bed, wherein the sand filter (108) is configured to percolate the treated water realized by the anaerobic fixed film reactor (106), thereby removing turbidity and pathogenic organisms present in the treated water released by the anaerobic fixed film reactor (106). A set of purifying bacteria is formed and acts on organic matter, thereby the sand filter (108) is also called biological filter, wherein the top layers of the sand become biologically active by the establishment of a microbial community on the top layer of the sand substrate, also referred to as‘schmutzdecke’ or‘filter skin’. In the slow sand filter (108), the microbes of the microbial community usually come from the untreated water and establish a community within a few days. The fine sand and slow filtration rate facilitate the establishment of this microbial community. The‘schmutzdecke’ is a nature’s filter containing a cocktail of algae, diatoms, protozoa, plankton, rotifers and bacteria. This microorganism based ‘living filter’ traps and digests the organic matter in the water passing through. Dead algae and living bacteria are also digested in this layer and converted to inorganic salts. The micro-organisms feed on adsorbed impurities and as the water flow is less at the bottom, the micro-organisms consume less. The bacteria oxide part of the food the micro-organisms need for metabolism (also called dissimilation) and part of the food for their own cell growth (also called assimilation) convert dead substances into living matter. The dissimilation products are carried down for further consumption of micro-organisms. As the water flows to a lower portion of the filter, a zone is formed with no organic nutrients and most harmful bacteria are starved to death. In addition to the zone, many predatory organisms like protozoa and metazoan release biological toxins which reduce most of the intestinal bacteria.

In the slow sand filter (108), adsorption takes place, wherein adsorption is defined as a phenomenon result from electrical forces, chemical bonding and mass attraction within sand particles occurring as the untreated water passes in laminar flow through millions of grins constantly changing direction. During the water flow, millions of minute sedimentation basins are formed where the particles settle down as clear water drips down.

In the slow sand filter (108), adhesion takes place as well, wherein adhesion is defined as a principle applied during the initial ripening process, wherein the organisms reside on the sand grains on the higher levels of filter forming bed for microorganisms to breed and flourish. Diffusion, also known as Brownian movement, brings suspended particles in contact with sand acting independently of the filtration process. The water transport mechanism is aided by Columbus force in addition to the mechanical treatment wherein the water nitrogenous components are broken down and oxidized, resulting in clean water devoid of bacteria, virus and even heavy metals.

Fig. 2 is a schematic representation of the bio-settler in accordance with an embodiment of the present disclosure. In an embodiment, dimensions of the bio settler (102) are in the range of (6.6m+3.4m+4.52m) L, 2.2. m W and 2m D. The bio settler receives the untreated water via an inlet, wherein the bio settler (102) is configured to process mechanical treatment and biological treatment on the untreated water. During the biological treatment, biogases are emitted, which are let out of the bio settler (102) via a gas vent. The treated water, i.e., the untreated water which underwent mechanical treatment and biological treatment, is passed into the anaerobic fluidized baffled reactor (104).

Fig. 3 is a schematic representation of the anaerobic fluidized baffled reactor (104) in accordance with an embodiment of the present disclosure. In an embodiment, dimensions of the anaerobic fluidized baffled reactor (104) are in the range of lm L x 32.5m W x 2m D. The anaerobic fluidized baffled reactor (104) includes a series of chamber, wherein each chamber contains sludge at the bottom. The anaerobic fluidized baffled reactor (104) includes six chambers containing sludge at the bottom of each chamber, wherein each chamber is separated by a l/3rd gap at the top. The treated water received from the bio settler (102) is intensively mixed with sludge which is inoculated with bacterial mass, which decomposes the left-over organic pollutants in the treated water received by the bio settler (102), resulting in the release of biogases. These biogases are released into the atmosphere through gas vents. As the treated water is passed to the next five chambers, the treated water is mixed with sludge, wherein the process reduces the amount of biogases released by the time the treated water reaches the last chamber of the anaerobic fluidized baffled reactor (104). Fig. 4 is a schematic representation of the anaerobic fixed film reactor (106) in accordance with an embodiment of the present disclosure. In an embodiment, dimensions of the anaerobic fixed film reactor (106) are in the range of l.5m L x 32.5m W x 2m D. The anaerobic fixed film reactor (106) including an anaerobic filter wherein the anaerobic fixed film reactor being configured to treat non- settleable and dissolved solids, present in the treated water released by the anaerobic fluidized baffled reactor, by bringing the non-settleable and dissolved solids in contact with an active bacterial mass fixed on the anaerobic filter. The anaerobic fixed film reactor (106) includes a series of chamber containing filter media and filter media slab, wherein the filter media used here is jelly which includes gravel, rocks or specially formed plastic pieces which provide an additional surface area for bacteria to settle. The filter media slab is placed at a 0.60m from the bottom of the system and the filter media of 0.60m is placed above the filter media slab. Say, the anaerobic fixed film reactor (106) includes four chambers, wherein each chamber contains the filter media and filter media slab. The filtering pores of the filter media are decreased in size along the remaining three chambers. The anaerobic fixed film reactor (106) treats the non-settleable and dissolved solids by bringing in close contact with a surplus of active bacterial mass fixed on the filter media, resulting in the production of biogases. The biogases are emitted via a gas vent attached to the anaerobic fixed film reactor (106). The treated water is not passed onto the slow sand filter (108).

Fig. 5 is a schematic representation of the slow sand filter (108) in accordance with an embodiment of the present disclosure.

In an embodiment, dimensions of the slow sand filter (108) are in the range of 13.7m L x 6.3m W x 2m D. The slow sand filter (108) comprising a sand bed, wherein the slow sand filter being configured to percolate the treated water released by the anaerobic fixed film reactor (106) through the sand bed, thereby removing turbidity and pathogenic organisms present in the treated water released by the anaerobic fixed film reactor (106). From bottom to top, the sand filter includes a 40mm jelly and sand, above the jelly, wherein in between the sand, a l9mm Kadapa stone slab is included to divide the sand filter. The treated water received from the anaerobic fixed film reactor (106) is passed through the left portion of sand filter in a‘downward flow’ and water comes out via the right side of the Kadapa stone slab as a‘upwards flow’ movement, wherein the pathogents are filtered. Once the filtration is completed, the treated water is let out via an outlet means.

In an embodiment, the system is configured below ground level, wherein the system is covered with reinforced cement concrete (RCC) M25 roof slab on the top and RCC M25 bottom slab on the bottom of the system. The reinforced cement concrete is placed on all four sides of the system, wherein the system here includes the bio settler (102), the anaerobic fluidized baffled reactor (104) and the anaerobic fixed film reactor (106). Below the RCC M25 bottom slab, a slab of PCC (plain cement concerete) is placed. At the bottom of the sand filter also the PCC layer is done. The gas vents to release the biogases have an opening above the ground level.

The key advantage over existing systems is that the present system is a natural water treatment system and does not use any chemicals or energy source for removing the pathogens present in the water. Therefore, it is cost effective since it can work continuously without being dependent on electricity or any form of power, and eco- friendly as it does not require or release any harmful chemicals as by-product during the process. Further, the present system naturally removes chlorine present in water by way of 'Chlorine Replacement'. Low cost and easy operation make the present system extremely useful in remote areas. The anaerobic treatment by design kills most of the pathogens. Adding to that the‘ slow sand filter' also removes pathogens. The synergistic combination of anaerobic treatment with slow sand filter results in achieving a higher level of pathogen removal. The present system is suitable to function as a sustainable domestic wastewater treatment disinfectant system.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the disclosure and are not intended to be restrictive thereof. While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein. The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, the order of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts need to be necessarily performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.

Claims

WE CLAIM:

1. A system (100) for removal of pathogens from water comprising: a bio settler (102) configured to: mechanically treat untreated water by filtering contaminants present in the untreated water by at least one of sedimentation and flotation; biologically treat untreated water through anaerobic microorganisms configured to partially decompose organic pollutants present in the untreated water; an anaerobic fluidized baffled reactor (104) configured to combine the treated water released by the bio settler (102) with sludge, wherein the sludge comprises bacterial mass configured to decompose the organic pollutants present in the treated water; an anaerobic fixed film reactor (106) comprising an anaerobic filter, wherein the anaerobic fixed film reactor (106) being configured to treat non- settleable and dissolved solids, present in the treated water released by the anaerobic fluidized baffled reactor (104), by bringing the non-settleable and dissolved solids in contact with an active bacterial mass fixed on the anaerobic filter; and a slow sand filter (108) comprising a sand bed, wherein the slow sand filter (108) being configured to percolate the treated water released by the anaerobic fixed film reactor (106) through the sand bed, thereby removing turbidity and pathogenic organisms present in the treated water released by the anaerobic fixed film reactor (106).

2. The system (100) as claimed in claim 1, wherein the bio settler (102) is a hermetically sealed septic tank with a predefined hydraulic retention time.

3. The system (100) as claimed in claim 1, wherein the mechanical treatment and the biological process, performed by the bio settler (102), are configured to reduce and stabilize accumulated sludge.

4. The system (100) as claimed in claim 1, wherein the anaerobic fluidized baffled reactor (104) comprises a plurality of chambers, wherein each chamber of the plurality of chambers contain the sludge at the bottom and the treated water flows up-stream in the plurality of chambers.

5. The system (100) as claimed in claim 1, wherein the anaerobic filter is composed of at least one of a plurality of gravels, a plurality of rocks, a plurality of specially formed plastic pieces configured to provide an additional surface area for the active bacterial mass to settle.

6. The system (100) as claimed in claim 1, wherein a top layer of the sand bed becomes biologically active by the establishment of a microbial community on the top layer.