GB1600180A - Apparatus for the purification of waste water - Google Patents

Description

(54) APPARATUS FOR THE PURIFICATION OF WASTE WATER (71) We, SCHOLL AG, a corporation organised and existing under the laws of Switzerland, of CH 4800 Zofingen, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention refers to apparatus for the purification of waste water.

The apparatus of the present invention is especially suited for the purification of waste water from textile dyeing factories, but equally well for the purification of waste water from chemical industries, as well as for the purification of rain water to provide drinking water. The invention provides apparatus for the purification of water comprising: an elongate collection tank having an inlet at one end for feeding raw waste water and an outlet for draining sedimented waste at an end remote from said inlet; said collection tank enclosing a plurality of communicating compartments separated by walls and interconnected by means of a labyrinth conduit formed by said walls; a recirculating pipe and a pump for circulating waste from a chamber at the inlet to an intermediate chamber of said collection tank; an air mixing chamber inserted into said recirculating pipe to provide a first stage of oxidation by waste water-air mixing and deliver the air water mixture to the first compartment adjacent the inlet of the collection tank, thereby recirculating oxidized water through said collection tank; exhaust pipe means connected to the free space above the water in the oxidation chamber; a second oxidation chamber provided with a water-air mixing means fitted with a pump and an inlet pipe taking water from the first oxidation chamber to the second oxidation chamber; an air supply pipe means above the water level in the second oxidation chamber to supply ozone containing air from said water-air mixing means to the waste water in the second oxidation chamber; a racial dispenser forcing air under pressure through the water-air mixing means; a siphon means to draw off treated water under pressure from the second oxidation chamber; a pump and additional waterair mixing means including recirculation pipe means to recirculate treated water under pressure in the second oxidation chamber; a third oxidation chamber connected by pipe means to the second oxidation chamber and provided with a pressure pipe means extending below the waste water level and a compressor for air fitted to the pressure pipe to form fine bubbles of air; and a sedimentation tank including a flocculation compartment for collecting solids separated in the third oxidation chamber and conduit means between said third chamber and the flocculation compartment being fed with polyelectrolyte to flocculate suspended solids while the supernatant liquid is removed. It is especially advantageous when the water is drawn off from the first chamber, enriched with ozone and air and recirculated back to the first chamber to be supplied there in even distribution, whereby preoxidation is performed by the absorption of ozone.

Preferably, the waste water is aerated by means of air or CO2 or flue gas, prior to the preoxidation by means of ozone from the second chamber.

The water may be treated with ozone carrying air at least in two following steps in the second stage for decoloration and decomposition of the organic substances. In the drawings, there is schematically shown one embodiment of an installation according to the invention.

The first stage of the installation for the purification of waste water comprises an elongate collection tank 1 with an intake compartment 2, in which there is provided a rake 3. The waste water is fed to the intake compartment 2 by means of a pipe 4. The collection tank 1 is divided into a number of communicating compartments by means of walls 5, 6 and 7, providing a labyrinth conduit. The compartment of the collection tank 1 between walls 5 and 6 is covered by a roof construction 8. At the end of the tank 1, in the compartment 24 between the walls 6 and 7, there is provided a recess 9 in the bottom of the compartment. This compartment 24 is used for presedimentation of the sedimentable solids in the waste water. Solids and slurry are deposited in the recess 9, sucked off by a slurry pump and are fed via a pipe 11 to a slurry concentrator and or to a dehydrating filter. A part of the water in the compartment 13 of the collection tank 1 is circulated by means of a circulation pipe 12 into the compartment 14. The circulation pipe 12 is provided with a pump 15 as well as with a water-air-mixing chamber 16, connected by a pipe 17 to a second stage, which will be described later. The pressure side of the circulation pipe 12 is connected to the bottom of the compartment 14 and is provided, at its end, with a dispersion unit 18 dispersing the recirculated water mixed with air evenly in said compartment 14. Further, the compartment 14 is partially filled as at 141 with a catalyst to provide a preoxidation of the waste water therein.

An exhaust pipe 19 is connected to the free space in top of the compartment 14 to suck off air therefrom and to lead this air to a water separator 21 and further to a chamber 22 filled with a catalyst, where any O3 eventually contained in the air is extracted.

The water from the water separator 21 is fed back to the tank 1 by means of a pipe 20.

If the waste water has to be neutralized prior to oxidation, CO2 or flue gas is introduced into the preoxidation compartment 14 by means of a pipe 23.

In the first stage described above, the variations caused by the organic burdens of the waste water are equalized and a preoxidation and presedimentation is effected. The water from the first stage is removed by a pump 26 and supplied via a pipe 25 to the second stage. Initially, the water is led to a first contacting chamber 27 forming part of the second stage, the oxidation stage.

The first contacting chamber 27 is provided with a catalyst package 28 effecting an acceleration of the oxidation and thereby causing a decomposition of the organic contents contained in the water supplied via pipe 25 to the bottom of this chamber 27. A pipe 29 opens to the chamber 27 above the water level to supply activated air into the interior of said chamber 27. This air is blow into the fluid contained in the chamber 27 by means of a radial dispenser 30, whereby the fluid-airmixture is forced to pass through the catalyst package 28. Water and O3-containing air are drawn off from the fluid level by a syphon 31 and are, as a mixture, fed to the following, second contacting chamber 38 by means of a pressure pipe 32. If heavily wasted water has to be treated, a further external circulation pipe 33 is provided connected near the bottom to the chamber 27 and comprising a pump 34 feeding the recirculated water back to the upper part of the contacting chamber 27. Above the catalyst package 28, there are provided one or two cylindrical inserts 35 filled with a catalyst. The pipe 33 opens into two branches which are connected to the bottom of said inserts 35 to supply them with circulated water containing 03 Gas. The tops of the inserts 35 are connected together by a common pipe which opens to a collection pipe 36 leading to a slited tube 37.

The tube 37 is transversely arranged in top of the inserts 35 in the interior of the contacting chamber 27, which is closed by a cover 37A.

Water and the excess of activated air is drawn off from the first contacting chamber 27 and supplied to the following, second contacting chamber 38 by means of a pipe 32 The pressure pipe 32 is connected to the contacting chamber 38 at the bottom thereof, and the interior of the chamber 38 is filled with a catalyst 39. The compressed, activated air from pipe 32 expands on entering the chamber 38 and goes up through the catalyst in form of fine air bubbles.

Above the fluid level the air is drawn off by a compressor 41 and fed, via pipe 40, partially to a pipe 42 leading back to the bottom of the contacting chamber 38 and partially to a pipe 45 leading to a third contacting chamber 46.

The third contacting chamber 46 is filled with a catalyst 39. A mixing unit 47, connected with its outlet to the bottom of the chamber 46, is fed via pipes 43 and 45 with water and air.

The water from the second stage, comprising the three contacting chambers 27, 38 and 46, is supplied to the following third stage by means of a pump 49 and a pipe 48. An exhaust pipe 17 is connected to the third contacting chamber 46 of the second stage. If necessary, there can be provided more than two contacting chambers 38 and 46, whereby an oxidation process takes place in every contacting chamber.

While an oxidation process is performed in the above described second stage, a third stage is connected to the second stage, where a flocculation is performed and where the remaining organic content in the water is eliminated.

An important item of the third stage is a slurry concentrator, and its exit is connected to a dehydrating filter for removing the water contained in the slurry.

Further, the third stage comprises a sedimentation tank 52 with a flocculation compartment 65 and a groove-like channel 64 as well as a collection recess 53 for collecting the slurry therein. By means of a pipe 54, the slurry is removed from the collection recess 53 and fed to the slurry concentrator 50. In the interior of the sedimentation tank, there are still provided clearing means 55. Water supply to the sedimentation tank is effected from the last contacting chamber 46 via a static mixing unit 63 by a pipe 56. Further pipes 57 and 58 connected to the mixer 63 are intended to supply polyelectrolytic products, i.e. macromolecular substances to accelerate the sedimentation, from a container 59, and to dosably supply flocculation substances from a container 60. Both containers 59 and 60 are equipped with agitators 61 and 62, respectively, for stirring the content of the container.

The water is drawn off from the sedimentation stage and is fed via a pipe 66 to a filtration stage where microflocks are removed from the water. The filtration is effected in counterflow in the interior of a pressure filter vessel 67, which contains an upper filter layer 68 of coarse filtration substance to perform a prefiltration, as well as a lower filtration layer 71 of fine filtration substance.

Between the two filtration layers 68 and 71, there are provided drainage means 69. The water having passed the coarse filtration layer 68 is collected by the drainage means 69 and fed via a pipe 70 to the bottom of the filter vessel 67. Then, the water is forced upwards to pass the fine filtration layer 71 and is finally collected by a second drainage means 80 to be removed from the filter vessel 67 by means of a pipe 81.

The purified water is neutralized and desalinated in a following last stage. A neutralisation unit 82, comprised in said last stage, receives the water and lowers its pH-value.

This is effected with the help of a regeneratable substance, e.g. a ionexchange resin contained in the neutralisation unit 82. The resin being exhausted, it is treated with a reclaiming agent. Simultaneously, a desalination is performed in this unit 82. The purified, neutralized water is removed from the last stage by means of a pipe 85 for reuse.

The above described installation is operated as follows: The waste water to be purified is fed via pipe 4 to the intake compartment 2 and comes into the collection tank 1 after having passed the fine-mesh rake 3, where the variations of the ballast substances are equalized.

The amount of water is metered and registered. Slurry and sediments are collected in the recess 9. These solids from recess 9 are drawn off by means of the slurry pump 10 and fed to the slurry concentrator 50. The water contained in the collection tank 1 is circulated by means of the circulation pipe 12 with pump 15, and it is fed back to the compartment 14 of the collection tank evenly distributed. Simultaneously, activated air is drawn off from the second stage via pipe 17 and is fed to the preoxidation stage in the compartment 14. In addition, the first compartment of the preoxidation stage is intensively aerated by an air flow from a pipe 86.

The air collected within the roof construction 8 is removed through pipe 19 and fed to the water separator 21 and thereafter to the chamber 22 filled with a catalyst, where any O3-gas eventually contained in the water is removed. The water from the water separator 21 flows back to the compartment 24 of the collection tank 1 via pipe 20.

In the presedimentation stage, i.e. in the compartment 24, the sedimentable substances have been removed from the water and the water is oxygenated. Then it is fed via pipe 25 to the second stage into the first contacting chamber 27 where a catalytic oxidation of the organic materials by means of activated air is performed. In this first contacting chamber, an intensive contact between waste water and activated air takes place. The activated air is generated by a high tension electro unit 87 to create O3-gas, which is supplied via pipe 29 to the radial dispenser 30.

Water and any excess of O2-gas is drawn off from the first contacting chamber 27 by means of the syphon 31 and is fed via pipe 32 to the following, second contacting chamber 38 at the bottom thereof. The O2-gas will expand upon entering the second contacting chamber 38 and will go up through the catalyst 39 in the form of fine gas bubbles. O3- gas is drawn off from the top of the second contacting chamber 38 by means of the compressor 41. This gas stream is divided into two branches: One branch flows to the bottom of the third contacting chamber 46, and the other one flows back to the bottom of the second contacting chamber 38.

The O3-activated air from the dispenser 30 passes through the water and is collected in the top of the chamber 27, where it is mixed with the drops escaping from the slitted tube 37. Thereby a large contact area is assured so that the O3-gas is nearly completely absorbed by the water. Any excess of O3-gas as well as water is drawn off by the syphon 31 and supplied to the following contacting chamber 38. The fluid level in each contacting chamber remains constant, but is lower in each following chamber than in the preceding chamber.

Thereby is assured that the water flows from one chamber to the following without the help of a pump. The wa ter is declolorated in the contacting chambers, but remains opaque. The remaining decomposition products generated by the oxidation process have to be removed by coagulation and sedimentation.

After the above described treatment in the second stage, a further treatment of the water in the following sedimentation stage is performed. There, the remaining organic compositions and the opaqueness have to be removed by adding flocculation agents.

Before certain flocculation agents are added in metered amounts, the pH-value is lowered by adding H2SOo or flue gas. The pH-value is continuously checked and controlled by an automatic control unit. The deposited slurry is collected in the concentrator 50 and fed to the dehydration press 51 to remove any water.

The main part of the slurry generated in the flocculation chamber 64 will rise to the surface under the influence of the air and CO2 -gas dissolved in the water. The concentrated slurry is drawn off from the groove 64 to the slurry collection recess 53. After the sedimentation step, the purified water will be filtered in the counterflow filter 67.

The filtered purified water then will be fed to the neutralisation- and desalination stage.

Usually the neutralisation is effected by the ionexchange methode. The ionexchange resin can be regnerated by a suitable reclaiming agent. If necessary, the neutralisation stage can be arranged preceeding the sedimentation stage, but the remaining stages operate in the same manner and sequence as described.

Sometimes, it may be of advantage to perform the neutralisation step with the help of flue gas.

WHAT WE CLAIM IS: 1. Apparatus for the purification of water comprising: an elongate collection tank having an inlet at one end for feeding raw waste water and an outlet for draining sedimented waste at an end remote from said inlet; said collection tank enclosing a plurality of communicating compartments separated by walls and interconnected by means of a labyrinth conduit formed by said walls; a recirculating pipe and a pump for circulating waste from a chamber at the inlet to an intermediate chamber of said collection tank; an air mixing chamber inserted into said recirculating pipe to provide a first stage of oxidation by waste water-air mixing and deliver the air water mixture to the first compartment adjacent the inlet of the collection tank, thereby recirculating oxidized water through said collection tank; exhaust pipe means connected to the free space above the water in the oxidation chamber; a second oxidation chamber provided with a water-air mixing means fitted with a pump and an inlet pipe taking water from the first oxidation chamber to the second oxidation chamber; an air supply pipe means above the water level in the second oxidation chamber to supply ozone containing air from said water-air mixing means to the waste water in the second oxidation chamber; a radial dispenser forcing air under pressure through the water-air mixing means; a siphon means to draw off treated water under pressure from the second oxidation chamber; a pump and additional water-air mixing means including recirculation pipe means to recirculate treated water under pressure in the second oxidation chamber; a third oxidation chamber connected by pipe means to the second oxidation chamber and provided with a pressure pipe means extending below the waste water level and a compressor for air fitted to the pressure pipe to form fine bubbles or air; and a sedimentation tank including a flocculation compartment for collecting solids separated in the third oxidation chamber and conduit means between said third chamber and the flocculation compartment being fed with polyelectrolyte to flocculate suspended solids while the supernatant liquid is removed.

2. Apparatus as claimed in Claim I, further including a meter at the inlet pipe to measure the quantity of waste water being treated and wherein the collection tank is provided with a roof, including a draw off pipe in the roof, for removing ozone containing gas in the free space above the collection tank.

3. Apparatus for the purification of waste water substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. the dehydration press 51 to remove any water. The main part of the slurry generated in the flocculation chamber 64 will rise to the surface under the influence of the air and CO2 -gas dissolved in the water. The concentrated slurry is drawn off from the groove 64 to the slurry collection recess 53. After the sedimentation step, the purified water will be filtered in the counterflow filter 67. The filtered purified water then will be fed to the neutralisation- and desalination stage. Usually the neutralisation is effected by the ionexchange methode. The ionexchange resin can be regnerated by a suitable reclaiming agent. If necessary, the neutralisation stage can be arranged preceeding the sedimentation stage, but the remaining stages operate in the same manner and sequence as described. Sometimes, it may be of advantage to perform the neutralisation step with the help of flue gas. WHAT WE CLAIM IS:

1. Apparatus for the purification of water comprising: an elongate collection tank having an inlet at one end for feeding raw waste water and an outlet for draining sedimented waste at an end remote from said inlet; said collection tank enclosing a plurality of communicating compartments separated by walls and interconnected by means of a labyrinth conduit formed by said walls; a recirculating pipe and a pump for circulating waste from a chamber at the inlet to an intermediate chamber of said collection tank; an air mixing chamber inserted into said recirculating pipe to provide a first stage of oxidation by waste water-air mixing and deliver the air water mixture to the first compartment adjacent the inlet of the collection tank, thereby recirculating oxidized water through said collection tank; exhaust pipe means connected to the free space above the water in the oxidation chamber; a second oxidation chamber provided with a water-air mixing means fitted with a pump and an inlet pipe taking water from the first oxidation chamber to the second oxidation chamber; an air supply pipe means above the water level in the second oxidation chamber to supply ozone containing air from said water-air mixing means to the waste water in the second oxidation chamber; a radial dispenser forcing air under pressure through the water-air mixing means; a siphon means to draw off treated water under pressure from the second oxidation chamber; a pump and additional water-air mixing means including recirculation pipe means to recirculate treated water under pressure in the second oxidation chamber; a third oxidation chamber connected by pipe means to the second oxidation chamber and provided with a pressure pipe means extending below the waste water level and a compressor for air fitted to the pressure pipe to form fine bubbles or air; and a sedimentation tank including a flocculation compartment for collecting solids separated in the third oxidation chamber and conduit means between said third chamber and the flocculation compartment being fed with polyelectrolyte to flocculate suspended solids while the supernatant liquid is removed.

2. Apparatus as claimed in Claim I, further including a meter at the inlet pipe to measure the quantity of waste water being treated and wherein the collection tank is provided with a roof, including a draw off pipe in the roof, for removing ozone containing gas in the free space above the collection tank.

3. Apparatus for the purification of waste water substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.