WO2002083573A2

WO2002083573A2 - Method to treat soapy wastewater

Info

Publication number: WO2002083573A2
Application number: PCT/IB2002/000543
Authority: WO
Inventors: Juan Amescua Rebollar
Original assignee: Juan Amescua Rebollar
Priority date: 2001-04-10
Filing date: 2002-02-25
Publication date: 2002-10-24
Also published as: AU2002236116A1; WO2002083573A3

Abstract

It is described a procedure to potabilize water from a soapy wastewater source that comprises:(a) Adding aluminium chlorhydroxide polymers of the formula (Aln(OH)mCl3nm) flocculate-coagulate to the soapy wastewater flow; (b) Adding a base or alkaline salt to the soapy wastewater, (c) directing the mix of stage (b) to a storage tank where the suspended particles in the wastewater are flocculated and coagulated; (d) filtering the water that comprises the coagulated flocculates through at least one diatomaceous earth filter; (e) storing the water in a storage and recycling tank; (f) filtering the water flow through at least one diatomaceous earth filter; (g) injecting hydrogen peroxide (H2O2) or ozone (O3); and (h) recycling the water flow to the storage tank on stage (e) until the desired water quality is obtained.

Description

METHOD TO TREAT SOAPY WASTEWATER

This invention refers to a method for the treatment of wastewater, soapy water in particular, to remove contaminating elements and obtain water with sufficient quality to be used for showers, sanitary services, irrigation of green areas, etc.

The method of the following invention also permits the possibility to make potable water from soapy water, so that this water can be used for its consumption.

Background of the invention

There are different types and techniques that are known for the treatment of wastewater. These treatments depend on the substances that are found dissolved or suspended in water. Some water treatment methods use sedimentation, inverse osmosis (see United States patent 5,401,421), treatment with rotating biological discs, evaporation, ionic interchange, active sludge, centrifugation (see United States patent 4,168,231) and by filtering (see United States patent US3550778). For filtration there are different types of filters; for example, sand filters, filter press, and diatomaceous earth filters. The results of the traditional procedures of water treatments of the prior art get a certain recuperation of the properties that potable water has before contamination, and according to prior art techniques, potable water from wastewater has been obtain by inverse osmosis, which are methods that are extremely expensive and therefore commercially inefficient for the treatment of large volumes of water.

For example; the wastewater known as black or gray water are only treated in such a way that they can only be used for irrigation and in the best of the cases in laundry. In other words even with the treatment these types of water still conserve remnant quantities, but unacceptable quantities of toxic substances and microorganisms, which are dangerous for health, thus, this water cannot be used as potable water.

In the case of water which is used in swimming pools, there is a large quantity of suspended organic substances, such as hair, fat and dust that must be removed from these bodies of water. Furthermore in case that said body of water becomes stagnated, algae, fungi and other microorganisms tend to form, so said water should be treated periodically and eventually substituted with new potable water. The methods used in the treatment of swimming pool water include treatment with sand filters and chlorinated chemical compounds. Other methods incorporate ammonium compounds. If swimming pool water is not considered gray water or soapy water, they still share certain undesirable characteristics and present similar treatment problems. With the present invention swimming pool water will be considered soapy water.

Sand filter treatment presents certain disadvantages. First of all, they require too much time to be prepared before they begin to filter effectively. Secondly, it is difficult to filter particles that have less than 23 microns pore in diameter. Moreover a lot of water is wasted when the filters are washed back. This quantity of water is significant in comparison to the volumes of water that are filtered.

Regarding chemical water treatment of swimming pool water, it is common to use trichloroisocyanuric acid. The indiscriminate addition of said chemical agent during prolonged periods of time cause an increment in the concentration of cyanide that could result in being toxic.

Soapy water, like the wastewater produced by people when they shower, has the principal problem the separation of organic and inorganic soluble compounds, such as soap, detergent and shampoo. The solubility of said compounds makes the sand filter treatment highly inefficient.

The use of diatomaceous earth filters is known to be used to remove fats from aquatic stream, these fats have large particle diameters. However this technique does not recognize the use of diatomaceous earth filters to eliminate soap, shampoo and organic and inorganic detergents.

With this in mind there isn't a viable procedure now to reconvert wastewater, especially soapy water into potable water, since it has already been stated that they are soluble in water.

Therefore it is one of the objectives of the invention to obtain a treatment method of gray and black water.

Another purpose of the invention consists of obtaining a method to clarify wastewater, particularly black and gray water that contains dissolved soap, shampoo and water-soluble detergents.

Another purpose of the invention consists in making clarified and wastewater potable, particularly soapy water.

Another purpose of the invention consists on the treatment of pool water. Description of the invention

In order to go over the problems of the prior art we have invented a method of water purification in which it is possible to make potable water. The method of treating water in the present invention consists in a physical-chemical process of clarifying that involves different operations of flocculation, coagulation and filtration operations by using diatomaceous earth. One embodiment of the present invention includes a potabilization stage that includes the filtration of a stream of clarified water through a filter of diatomaceous earth. Another embodiment of the present invention includes a stage of filtration of a stream of clarified water in a filter of diatomaceous earth and after that oxidation with ozone (0₃), hydrogen peroxide (H₂0₂), finally passing through activated carbon filters, with this we can obtain water that meets the requirements of quality for human consumption.

Brief description of the drawings Figure 1 illustrates the clarification stage of the treatment according to our invention.

Figure 2 illustrates the potabilization method treatment of water according to our invention.

Detailed description of the invention

The degree of water contamination is variable and depends on the use it has, the contaminants in soapy wastewater vary from the total amount of pool water, and of course black water.

Once that the polluting agents in the wastewater are removed from the water in different stages through the whole process. It is convenient to determine at the beginning of the process and in each one of the subsequent stages the concentration of said contaminants, to determine the most adequate conditions of the operation for the water treatment and the efficiency of the method.

The different stages that comprise the method of the invention are described later in FIGS. 1 and 2.

Clarification

The stage of clarification in conformity with the invention is comprised of the stages of flocculation- coagulation and filtering through filters that contain diatomaceous earth.

The stages of flocculation and coagulation promote an agglomeration of the contaminants and it is an essential stage of the procedure. Once the soap, detergent and shampoo are water soluble, it is required that these acquire big enough particle diameters to be retained in a filter medium. For this effect the stages of coagulation and flocculation are needed.

A source of wastewater, for example, soapy water, is put through an independent hydraulic meshwork to storage container (1). Then the water is sent to flocculation tank (2) using pump (3). During the trajectory, the flocculent-coagulant and a base or alkaline salt are injected in the conduct through two dosing devices

(4) and (5) respectively.

As flocculent agents can be used any type of flocculent known in the art, but it is preferable to use inorganic polymers, in particular aluminum chlorhydroxide polymers of the formula (Al_n(OH)_mCI_3nm) at 50% V/N. Said polymers are available in the market through the trademark GELIMAR made by Quimica

Rosmar S.A de C.V.

The addition stage of the aluminum chlorhydroxide polymers of the formula (Al_n(OH)_mCI_3nιτl) at 50% VW, is critical in the procedure of this invention. This flocculent has the ability of flocculate soap, shampoo, organic detergents and even inorganic detergents.

Normally, the inorganic detergents are eliminated through a physicochemical process through the use of iron or aluminum salts and other means well known in the art. The use of the aluminum chlorhydroxide polymers of the formula (Al_n(OH)_mCI_3nm) at 50% V7V flocculent offers the possibility to also eliminate inorganic detergents.

The base or alkaline salt has the purpose of increasing the pH of the solution until reaching light alkaline concentration. In according to this invention it has been found that the stages of flocculation and coagulation have a better result in a pH between 7.5 and 8.0. The base or alkaline salt could be any organic or inorganic base or salt, however it is preferable to use light carbonate sodium (soda ash), since this compound has the property of dissolving rapidly in water and also conserving an alkaline pH value even though there may be variations in the sodium carbonate concentration.

The wastewater composition, for example, soapy wastewater, the flocculent and the base or salt are held in tank 2 enough time so that the particles be 5 flocculated and agglomerated. It has been found that the optimum time of flocculation-coagulation is approximately 15 to 20 minutes.

Once the wastewater has remained in tank 2 so that the disperse substances flocculate and coagulate, the water is sent to a filtration stage in filters 7 that contain diatomaceous earth. o The method of treatment of this invention operates by lots. So that the diatomaceous earth filter has to be prepared each time that it treated a lot of water.

The diatomaceous earth filters are prepared at the place of the procedure for any method known in that subject, however it is preferable that they 5 be prepared by the following method. In a container comprising base for the filter, preferably a stainless steel mesh pass a suspension of diatomaceous earth. When the diatomaceous earth makes contact with the mesh it will begin to deposit itself in the mesh. The flow will be repeated until all of the diatomaceous earth is deposited on the mesh. When this happens the water in the suspension will start coming out of o the filter clarified.

An advantage of using this method is that the diatomaceous earth filter is compressed because of the pressure exhibited by the pump, so that during this filtration operation the diatomaceous earth bed will not be broken down.

The diatomaceous earth is an abundant product that is commercially 5 available and is offered by various distributors. It is preferable to use diatomaceous earth that poses a pore diameter of one-micron average.

When passing wastewater that contains suspended particles through a filter of diatomaceous earth, the flocculated particles are eliminated with the suspended solids that did not flocculate. One or more filters that contain diatomaceous earth can make the filtration.

When the previous stage ends, the clarified water is deposited in tank (8). In the method of this invention, manometers or flow indicators that indicate the degree of saturation of the filters are optionally available. When the filters are obstructed because they are saturated with the impurities that are removed from the principal wastewater, it needs to replace the earth of the filters.

To replace the earth of the filters it needs to apply a counter flow of air or steam through the filter. The earth as a whole should detach from the support mesh. The diatomaceous earth is then compacted in a filter press and eventually thrown away as a mass composed of earth and mud that is easy to dispose off.

The treated water that is obtained in tank 8 is crystalline water that can be used for irrigation, washing and even as water for swimming pools. When we talk about pool water an agent that prevents the growth of algae and microorganisms should be added.

As it would be obvious for a skilled on the art, additional stages can be added in the procedure, for example incorporating filtration stages with sand filters or any other filters before the water is deposited in flocculation tank 2, or before of after the water is deposited in tank 8. In a similar way, it can be used a decantation stage so that the particles that precipitate can be removed before the water that contains the flocculated particles is sent to filters 7. these variations are considered included within this invention.

Table 1 illustrates the characteristics of soapy water treated in regards in this invention. The first column indicates the characteristics of soapy wastewater. In the second column the characteristics of clarified water are indicated in regards to this invention, while the third column illustrates the characteristics of the potable water resulting from this invention. Said potable water can be compared with the current standard 127SSA for potable water which characteristics are described in the fourth column.

In regards to an embodiment of this invention, a stage is included, which has the aim of making water potable according to the previously mentioned procedure.

Potabilization

In order to make potable water, the residual organic detergents, dissolved organic matter and microorganisms like bacteria and viruses that could exist are removed by oxidants.

According to the method of the invention, the use of aluminum chlorhydroxide polymers of the formula (Al_n(OH)_mCI_3nm) provoke traces of said compound in the clarified water and its effective elimination is essential to obtain potable water. According to the official standard 127SSA for potable water, the aluminum does not have exceed 0.20 mg/liter.

To eliminate the dissolved organic material and microorganisms such as bacteria and virus, and also the residual aluminum chlorhydroxide polymers of the formula (Al_n(OH)_mCI _nm) and residual detergents, it needs to oxidize, preferably with a combination of ozone (0₃) and hydrogen peroxide (H₂0₂). The use of such oxidants has the advantage that the resultant products of its reduction, this is water and oxygen does not contaminate potable water.

According to the modality of the invention, the clarified water stored in tank 8 is sent through the set of filters of diatomaceous earth 10. For this effect at least pump 9 is needed. At the end of filters 10 the oxidant is injected in the flow of water. Figure 2 illustrates the injection of hydrogen peroxide (H₂0₂) through dosing device 11 and immediately ozone is injected (0₃). Produced by ozone generator 12. The ozone (0₃)is introduced in the flow of water through venturi 13, the flow is sent to contact reactor 14, this gives time for the ozone to react in the water and destroy the organic material in the flow. The flow that goes out of contact reactor 14 is sent back to tank 8.

The oxidation stage with hydrogen peroxide and ozone has the aim to oxidize all compounds that are present in the water. As a result of said oxidation, organic and inorganic material precipitates and can be efficiently removed from the flow of water through filters of diatomaceous earth. It is required that the water is submitted though the oxidants and the filtration with diatomaceous earth several times, this is obtained by recycling the water through this process.

The recycling time is variable, but it depends basically on the quality of the desired water. A monitoring of the concentration and properties of the water stored in tank 8 will determine the moment when the recycling of the water should be suspended.

It is important to mention that the chemical demand of DQO oxygen in the resulting water is 0.0. In other words, all living material and all chemical organic and inorganic products that can be oxidized will be effectively oxidized.

Once the desired quality is obtained, as option water can be sent through filters with activated carbon 15 filters with the aim of retaining to the maximum the last traces of soluble substances.

The last stage of potabilization consists in adding enough sodium hypochlorite to obtain a concentration of 0.5 ppm to avoid contamination by algae and microorganisms, while it remains in storage in distribution cistern 17, from where it is sent to different services.

The laboratory analysis in this last stage will indicate the quality of water obtained to be used as potable water, according to the current standards. Table 1 illustrates the properties of potable water according to this invention.

In regards to swimming pool water after being purified with this invention, we can obtain water from which all kinds of dissolved fats and also soap and shampoo have been removed without the need of using chlorine and also without the need of disposing large volumes of water that are normally disposed of, when the retro wash of the sand filters used in this technique is made.

Additionally, due to the fact that DQO is equal to 0.0, water is not exposed to the quick development of microorganisms and fungi, which used to mean longer maintenance times with current traditional methods. In addition, it is important to mention that the water treated with ozone acquires a nice blue color that is not obtained with the traditional methods.

Example

An example of the application according to the invention will be illustrated in the following passage.

Before starting the treatment of a wastewater lot, a filter of diatomaceous earth is prepared by recycling a suspension of diatomaceous earth. The treatment starts by injecting 0.00075 of aluminum chlorhydroxide polymers of the formula (Al_n(OH)_mCI3_nm) at 50% V/N compound per liter of water and a kg of light sodium carbonate (soda ash) per 10,000 liters of water increasing the pH to optimize flocculation and coagulation.

The floccules formed and the other contaminants pass to a filtration system with filters of diatomaceous earth, with a pore diameter of approximately one micron.

The resulting flow is sent to a tank and then it is passed again through diatomaceous earth filters.

To inject the wastewater in the diatomaceous earth filters, a pump, which is used to recycle the dispersion that prepares the diatomaceous earth filter, is used. For this effect, a valve arrangement is needed. After this, the flow of water passes through the contact reactors with ozone (0₃), at 60 grams per hour and injecting at the same time hydrogen peroxide (H₂0₂) at 30% to maintain a concentration of 0.5 ppm.

In this process the fat, oil, organic material, detergents, bacteria and virus are eliminated.

The water is recycled through the stages already mentioned until reaching the required quality. Finally, it passes through filters with activated carbon for the final destination of the process.

During the process different laboratory analysis should be made to verify the efficiency of the process in each stage and the obtained quality.

The following table illustrates the wastewater properties and the properties of the obtained water after the clarification and potabilization stages.

Table 1. Wastewater, clarified water and potable water properties.

Table 1. Wastewater, clarified water and potable water properties.

Claims

1. A procedure to treat soapy wastewater that comprises a wastewater storage stage and a clarification stage of said water, characterized in that clarification stage comprising: a) Adding a flocculent-coagulant to a wastewater flow of aluminum chlorhydroxide polymers of the formula (Aln(OH)_mCl3_nm)- b) Adding a base or alkaline salt to the wastewater flow. c) Conveying the mix of water and flocculate-coagulate agents and a base or alkaline salt to a permanency tank in where the suspended particles in the wastewater are flocculated and coagulated; and, d) Filtering the water that contains the flocculated, coagulated in at least one filter that contains diatomaceous earth.

2. The procedure according to claim 2, wherein the flocculate- coagulate comprises aluminum chlorhydroxide polymers of the formula

(Al_n(OH)_mCI_3nm) at 50% V/N.

3. The procedure according to claim 1, wherein the salt comprises sodium carbonate.

4. The procedure according to claim 1 , wherein the diatomaceous earth comprises a pore diameter of approximately one micron.

5. The procedure according claim 1, wherein the wastewater is swimming pool water.

6. A procedure to clarify water that is comprised of; a) Adding a flocculate-coagulate of aluminum chlorhydroxide polymers of the formula (Aln(OH)_mCI3_nm) to a wastewater flow, b) Adding a base or alkaline salt to the wastewater flow: c) Directing the Mixture of water and flocculate-coagulate agents and a base or alkaline SALT to a storage tank where the suspended particles in the wastewater are flocculated and coagulated; and, d) Filtering the water that contains the flocculate coagulated in at least one filter that contains diatomaceous earth.

7. The procedure according to claim 9, wherein the coagulant comprises aluminum chlorhydroxide polymers of the formula (Al_n(OH)_rnCI_3nm) at 50% V/N.

8. The procedure according to claim 8, wherein the salt comprises sodium carbonate.

9. The procedure according to claim 8, wherein the diatomaceous earth comprise a pore diameter of approximately one micron.

10. The procedure according to claim 1 , wherein the water is swimming pool water.

11. A procedure to make potable water that includes; a) Storing water in a storage and recycling tank. b) Having a flow of water passing by at least one filter of diatomaceous earth; c) Injecting an oxidant that comprises an addition of hydrogen peroxide (H₂0₂); and ozone (0₃) and; d) Recycling the water flow to the storage tank until the desired quality is obtained.

12. A procedure to potables water according to claim 15, wherein the diatomaceous earth comprises a pore diameter of approximately one micron.

13. A procedure to potables water according to claim 15 that comprises an additional stage of contact with the water with at least one filter with activated carbon that has the aim of retaining to the maximum the last traces of soluble substances.

14. A procedure to potabilize water according to claim 15 that comprises an additional stage of addition of sodium hypochlorite.

15. A procedure to potabilize water from a wastewater source that includes; a) Adding a flocculate-coagulate of aluminum chlorhydroxide polymers of the formula (Al_n(OH)_mCl_3nm) to a wastewater flow. b) Adding a base or alkaline salt to a wastewater flow; c) Directing the mix of water and flocculate-coagulate agents and a base or alkaline salt to a storage tank where the suspended particles in the wastewater are flocculated and coagulated. d) Filtering the water that comprises the flocculate coagulate by at least one diatomaceous earth filter. e) Storing water in a storage and recycling tank. f) Passing the water flow through at least one diatomaceous earth filter. g) Injecting an oxidant that comprises an addition of hydrogen peroxide (H₂0₂) and an ozone (0₃); and. h) Recycling the flow to the storage tank on stage (e) until the desired water quality is obtained.

16. the procedure to potabilize water according to claim 19 that comprises an additional stage of water contact with at least one filter with activated carbon with the aim of retaining to the maximum the last trace of soluble substances.

17. The procedure to potabilize water according to with claim 19 that comprises a stage of sodium hypochlorite addition.

18. The procedure according to claim 22, wherein the coagulant comprises aluminum chlorhydroxide polymers of the formula (Al_n(OH)_mCI_3nm) at 50% V/V.

19. The procedure according to claim 19, wherein the salt comprises sodium carbonate.

20. The procedure according to claim 19, wherein the diatomaceous earth comprise a pore diameter of approximately one micron.

21. The procedure according to claim 19, wherein the soapy wastewater is swimming pool water.