WO2002006168A1

WO2002006168A1 - Method and device for purifying and treating waste water in order to obtain drinking water

Info

Publication number: WO2002006168A1
Application number: PCT/EP2001/007053
Authority: WO
Inventors: Rainer Fülling
Original assignee: Fuelling Rainer
Priority date: 2000-06-30
Filing date: 2001-06-22
Publication date: 2002-01-24
Also published as: ZA200201560B; DE10030984A1; EP1294647A1; AU2002210412A1

Abstract

The invention relates to a method for purifying and treating waste water in order to obtain drinking water, and a device for carrying out the method. Waste water is treated in a first step in a microbiological aerobic manner. Non-biodegradable foreign bodies or particles are then separated from the waste water. This is followed by biological post-purification, and biologically and chemically non-degradable substances are then removed from the treated waste water by means of post-filtration. The following step involves guiding the waste water through a static sand filter, and can involve a dynamic sand filter, an activated carbon filter, and ultrafiltration as further options. The inventive device comprises a microbiologically aerobic waste purification system, a system for separating off non-biodegradable foreign bodies and for removing residual degradable substances, and a post-filtration system.

Description

Method and device for cleaning waste water and treating it into drinking water

The invention relates to a method for cleaning wastewater and treating it into drinking water. The invention also relates to a device for carrying out this method.

Waste water in the context of the invention is used water (dirty water) from households, residential complexes, hotels, housing estates up to 1000 people and small towns. Water is also meant with a dirt composition that is comparable or less.

For the purification of waste water, it is known to treat it biologically, chemically or physically in large sewage treatment plants in such a way that it can be discharged into water. In these known cleaning processes, however, the cleaned wastewater is not treated to drinking water quality.

In the treatment of water by reverse osmosis is not sure that ^'salts remain as the water essential minerals.

Therefore, the known methods for cleaning wastewater are not suitable for leading drinking water for consumption and recycling into a direct cycle without introducing the water as an intermediate step into a body of water or treating it through a bottom passage. In particular, the known cleaning methods are not suitable for the treatment of water that is used in a relatively small consumption unit that is not connected to a public water supply network. For example, the known methods cannot be used for the water supply of hotels, Residential complexes or small towns are used, which are built and operated in areas with little or no water suitable for drinking water supply.

The invention has for its object to make hot water available in a manageable consumption unit such as a hotel independently of public water suppliers and to be able to reprocess it for renewed consumption.

This object is achieved according to the invention with a method which has the features of claim 1. Advantageous refinements and developments of this method are the subject of the dependent claims which refer back to claim 1.

In addition, this object is achieved according to the invention with a device which has the features of claim 5. Advantageous refinements and developments of this device are the subject of the dependent claims which refer back to claim 5.

The invention combines for processing and immediate

Reuse of wastewater biological, chemical and physical purification processes.

In purely biological processing, around 98 to 99% of organic can be produced using air, oxygen, bacteria and other small organisms

Oxidize waste water or wastewater contents to carbon dioxide and water.

However, 1 to 2% of the organic ingredients contained in wastewater are not biodegradable, or not sufficiently quickly. A biological one

It is therefore necessary to clean the filters below. In addition, it is possible to physically extract the organic ingredients from the to remove cleaning wastewater, at least in part by adsorption on activated carbon. The particulate constituents still remaining in the wastewater to be purified can also be separated from the wastewater, for example, by ultrafiltration. Undesired ingredients of organic or inorganic nature and particles, as well as bacteria and viruses, are finally removed in a third step by nanofiltration or reverse osmosis.

Due to the unique pore distribution in nanofilters, nanofiltration ensures that the concentration of water and in particular

Minerals important to drinking water are not broken down by demineralizing the water, but are adjusted to the optimal concentration for living beings.

Bacteria and corresponding particles are preferably separated in several filter stages in the second treatment step provided according to the invention. Ultrafiltration completely retains all bacteria, viruses or other particles on the filter, which means a so-called sterile filtration. Nanofiltration downstream of ultrafiltration is a double safety system. It is also able to completely retain any particles and bacteria that may still be present. Only very small amounts of chemicals are required for the treatment and treatment of the wastewater.

However, ultrafiltration is not absolutely necessary. Rather, in many cases it is also possible, according to the invention, to obtain biologically stabilized drinking water without ultrafiltration.

As the last treatment step, nanofiltration is cheaper than reverse osmosis. If ultrafiltration is dispensed with, energy costs can be saved significantly. Antiscaling agents and also chlorine can be used for the chemical treatment.

a. Antiscaling agent A few milliliters of the antiscaling agent per m ^{3 of} water are used in the

Nanofiltration added to e.g. B. to prevent limescale deposits on the membranes provided for nano-filtering.

b. Chlorination Since contamination in downstream lines or containers can introduce germs into the system, it is planned to add approx. 0.1 to 0.3 mg / 1 chlorine to the sterilized treated water after the final filtration (nanofiltration) in order to re-germinate the downstream ones To prevent containers and piping systems of the device according to the invention.

The invention is explained in detail below on the basis of practical exemplary embodiments of a device for the purification of waste water and for the immediate treatment thereof for drinking water.

activated sludge plant

In an aeration tank comprising, for example, 60 m ^{3 of} wastewater, activated sludge is flaked with the. mixed to wastewater to be cleaned. The organic impurities contained in the wastewater are from the

Activated sludge flakes are absorbed and largely biodegraded within a few hours. The oxygen required for this is introduced into the waste water to be cleaned by fans attached to the bottom of the aeration tank.

A sedimentation tank, which is hydraulically connected to it, borders on the activation tank described here. Set in this non-ventilated sedimentation tank the mud. The clarified, excess wastewater is pumped into a second aeration tank. The sludge slides down and from there back into the aeration tank. In this case, slats standing at an angle below the highest water level can be arranged as inclined clarifiers or lamella clarifiers in order to improve the separation of the

To achieve activated sludge. Since the fins are located deep in the sedimentation basin, this can also be used as a storage tank with a variable water level.

Biodegradation in the wastewater to be treated is promoted in another basin. The basin provided for this purpose contains growth bodies with very high growth areas. The water-cleaning organisms grow on the surface of the fixed bed provided in the pool (solid body) and in particular eliminate components that are difficult to decompose, which have not yet been eliminated in the first pool. This water can also be aerated. Oxygen is also consumed here, albeit significantly less. As an alternative, another revitalized pool is also possible as another pool.

Since small quantities of activated sludge flakes can be discharged from the activation tank, a filter is provided in a second treatment stage provided according to the invention, for example a filter that constantly cleans itself. For example, the water flowing out of the second basin is pumped into the lower third of a dynamic sand filter with a pump and flows through the sand in this filter upwards or from bottom to top. The sand in the dynamic sand filter is pumped upwards with air and water through a pipe inside the filter housing. The resulting swirling means that the sand is constantly washed.

The sand emerging from the inner tube in the upper part of the dynamic sand filter trickles through a chicane onto the surface of the filling of the sand filter. The sand in the sand filter flows a small proportion of the already filtered or treated water and thus prevents dirt from penetrating into the drain of the filtrate.

The water flowing in the dynamic sand filter is returned to the first activation tank together with the washing water of the sand.

As a result of this washing process, constantly contaminated sand slips into the lower zone of the dynamic sand filter, so that fresh sand is constantly available for filtration.

Sand circulation is preferably controlled by the air supply.

The air supply is switched off by a solenoid valve when the system is at a standstill.

By adjusting the air supply, the sand circulation should be regulated in such a way that sand extraction starts again even after the system has come to a standstill. Higher circulation speeds are not necessary.

In addition, according to the invention, in this second treatment stage, a static sand filter is provided, in which further biodegradation of the foreign substances in the waste water to be treated takes place. This biodegradation can lead to the top layer of sand filling becoming denser after some time. This leads to an increase in the pressure in the system, which is indicated by a pressure gauge. For example, if the pressure to be determined by the pressure gauge rises by more than 0.3 bar, it is indicated that the filter has to be backwashed in order to maintain the operability of the system.

In this second treatment stage, the wastewater is preferably also cleaned using an activated carbon filter. This activated carbon filter is used to remove part of the poorly biodegradable waste water contained substances. Depending on the composition of the wastewater, undesirable compression of the surface can also take place in the area of the activated carbon filter, which necessitates backwashing in a period of one to six months.

Some surfactants are only biodegradable to a limited extent. The content of biodegradable surfactants can impair the absorption capacity of the activated carbon of the activated carbon filter until it is exhausted.

The number of bacteria and organic constituents of the wastewater to be treated can be greatly reduced in the second treatment stage by means of several filters connected in series. In order to achieve complete sterilization of the treated wastewater and to avoid deposits in the subsequent nanofiltration (third treatment stage), the wastewater can also be treated by ultrafiltration in the second treatment stage.

So that deposits that form from the membrane surface intended for ultrafiltration can be removed by flushing, compressed air and backwashing water are preferably pressed into the ultrafiltration every thirty minutes. After opening a solenoid valve, the backwash water flows into the return line leading to the first activated pool. This is done automatically. .

By means of the nanofiltration, which is further provided according to the invention as the third treatment stage, the last portions of organic constituents of the water to be treated, such as salts, phosphates, sulfates, hardness formers (such as calcium, magnesium), but also a significant portion of sodium chloride, i.e. common salt, are removed. The concentrate with enriched salt and other ingredients can be discarded, partially returned to the reservoir or revitalized pool, or used for other purposes, such as flushing the toilet. In order to prevent deposits on the surface of the membrane used for nanofiltration, an antiscaling agent is preferably added to the water flowing into the nanofiltration. The dosing is expediently carried out automatically.

In the drawing, two exemplary embodiments of a device according to the invention for carrying out the second step of the method according to the invention for cleaning wastewater and treating it into drinking water are shown schematically, and that shows

Fig. 1 is a schematic representation of one embodiment of the

Device and

Fig. 2 is a schematic representation of the second embodiment of this device according to the invention.

In the embodiment according to FIG. 1, microbiologically pre-cleaned water is conveyed by means of a pump 1 through a line 2 into a basin 3, which serves as a further vitalizing basin.

From this basin 3, the already treated but still to be treated wastewater is conveyed through a line 5 from above to a dynamic sand filter 6 by means of a further pump 4.

In the dynamic sand filter 6 there is a filling 7 made of sand. A pipe 8 runs centrally through this filling 7, into which the water to be treated which is conveyed through the line 5 flows in from above through an inlet 9. Near the lower end of the housing 10 of the dynamic sand filter 6, a conical or funnel-shaped extension 11 is arranged in the same, on which the flow through the tube 8 downward to be treated further

Waste water strikes and there its flow direction corresponds to that in FIG. 1 arrows 12 reversed so that the wastewater, which initially flows downwards, now flows upwards through the sand filling 7.

At the upper end of the housing 10 of the dynamic sand filter 6 there is an overflow 13, via which the wastewater further purified in the dynamic sand filter flows into a drain line 14 which opens into an intermediate basin 15.

From the intermediate basin 15, the wastewater to be further purified is passed by means of a pump 16 through a line 17 into the upper end of a static sand filter 18.

From the static sand filter 18, the wastewater to be treated passes into a further intermediate basin 19, in which a pump 20 is immersed, in order to convey the wastewater from this intermediate basin 19 through a line 21 into the upper end of an activated carbon filter 22.

From the activated carbon filter 22, the waste water further treated there arrives in an additional intermediate basin 23, from which it is conveyed by means of a pump 24 through a line 25 into the lower end of a column-shaped ultrafiltration 26.

A common collecting line 27 serves to return sludge separated from the individual filter elements shown in FIG. 1 into the first activated pool of the plant, not shown in the drawing, for further treatment.

The storage containers of the device, i. H. the pools 15, 19 and 23 can be additionally ventilated in a manner not shown.

In the apparatus shown in FIG. 1, which carries out the further treatment of the waste water, the waste water further purified in the ultrafiltration 26 passes through a line 28 into a nanofiltration 29, in which the previously wastewater that has already been treated is post-treated in order to reliably separate foreign bodies that have not yet separated or unwanted ingredients that have not yet been removed, so that the treated wastewater is of drinking water quality and does not have to be discharged into water, but is available for direct reuse as drinking water stands.

In the embodiment of the device according to the invention shown in FIG. 2, the wastewater largely pre-cleaned in the activated sludge and finally to be post-treated in the nanofiltration can be intermediate treated according to the invention in a single device and thus represents an alternative embodiment to the embodiment shown in FIG. 1.

The device shown in FIG. 2 contains, in a housing 30 into which sewage water, which is biologically or microbiologically pretreated, flows from above through a line 31, a meandering filter 32 made of open-pore foam, including a grate 33 and underneath this a filter consisting of a sand filling Sand filter 34, through which the wastewater to be treated flows in succession from top to bottom.

An outlet valve 36 is connected to the sand filter 34 via an outlet line 35 and can optionally also be connected as an inlet valve in order to be able to backwash the sand in the sand filter 34 for cleaning. The outlet line 35 is designed within the housing 30 as a filter tube.

In addition, a float 37 arranged in the upper end of the housing 30 is arranged on the outlet valve 36 via a reversing mechanism, with the aid of which the water level in the housing 30 can be adjusted and regulated.

Two layers of foam are preferably wound up so that the running-in principle shown in the picture is retained. Because of its numerous pores, the filter 32, which is made of open-pore foam and has a meandering design, is used both for filtering the wastewater flowing through and as a bacterial carrier, so that further biological treatment of the wastewater can take place here.

This configuration leads to a large inflow area, which leads to the high filter efficiency which is ascertained and which has a reduced tendency to clog. Another advantage is the low flow rate.

When the sand filter 34 is backwashed, rinse water can flow back through at least one filter tube 39 with a connection piece 40 arranged under the grate 33 into the first activated pool for treatment.

The combination of the meandering foam filter 32 and the

Sand filter 34 in a housing 30 is not only particularly powerful but also extremely inexpensive. Both can also be designed as separate units. The combined filter shown in Fig. 2 can be used only for the second treatment stage of the waste water.

Claims

Method and device for cleaning wastewater and treating it into drinking water

1.Procedure for the purification of wastewater and treatment of the same to drinking water, the wastewater being treated in a first step microbiologically aerobically, then in a further step non-biodegradable foreign bodies or particles being separated from the wastewater and biological post-purification taking place and finally biological and chemically non-degradable substances are removed from the treated wastewater by post-filtration.

2. The method according to claim 1, characterized in that the waste water is physically and / or mechanically filtered in the further step.

3. The method according to claim 1 or 2, characterized in that the waste water is treated in the further step by ultrafiltration.

4. The method according to claim 3, characterized in that the waste water is treated in the third process step by nanofiltration or reverse osmosis.

5. Device for carrying out the method according to one of claims 1 to 4, characterized in that it has a microbiological aerobic wastewater purification device connected in series, a device for separating non-biodegradable foreign bodies or particles and removal of remaining biodegradable substances and • a post-filtration device.

6. The device according to claim 5, characterized in that the post-filtration device is an anofilter or a reverse osmosis device.

7. The device according spoke 5 or 6, characterized in that the device for separating biodegradable foreign bodies or particles has at least one sand filter and an activated carbon filter.

8. The device according to claim 7, characterized in that the device for the first separation of non-biodegradable foreign bodies or particles has a dynamic sand filter.

9. Device according to one of claims 5 to 8, characterized in that the device for the first separation of non-biodegradable foreign bodies or particles connected in series a dynamic sand filter, a further sand filter has an activated carbon filter and / or an ultrafiltration filter.

10. The device according to claim 5, characterized in that the device for separating non-biodegradable foreign bodies or particles has a filter which in combination has a meandering foam filter and a sand filter.

11. The device according to claim 10, characterized in that the foam filter and the sand filter are arranged in a common housing.