WO1993017773A1

WO1993017773A1 - Apparatus for separation

Info

Publication number: WO1993017773A1
Application number: PCT/SE1993/000198
Authority: WO
Inventors: Klaus Dieter Zickert
Original assignee: K Z Handels Aktiebolag
Priority date: 1992-03-06
Filing date: 1993-03-05
Publication date: 1993-09-16
Also published as: NO943290D0; SE9200695D0; NO304680B1; NO943290L

Abstract

The present invention relates to a device for increased separation efficiency at waste water purification or purification of other water with large sedimentation amounts and comprising two concentric cylinders, where the waste water is arranged to be introduced in the outer cylinder and is arranged to pass into the inner cylinder, whereby the outer cylinder (1) is provided with an inlet (3), the inner cylinder (2) is provided with an inlet spillway (4), the inner cylinder (2) is provided with a substantially conical insert (5) arranged with its tapering end downwardly directed.

Description

APPARATUS FOR SEPARATION DESCRIPTION Technical field

The present invention relates to a device for increased separa- tion efficiency at waste water purification or purification of other water with large sedimentation amounts and comprising two concentric cylinders, where the waste water is arranged to be introduced in the outer cylinder and is arranged to pass into the inner cylinder.

The object of the present invention is to obtain a possibility of increasing the amount of sludge in a plant for sewage water purification and to lower the amount of COD (oxygen consuming) substances in the water (sludge water) which is fed further in the purification process and/or to a recipient.

Background of the invention

At so called biological purification in a plant for the purifi¬ cation of waste water the water is introduced , after a coarse filtration, into large aeration basins through which the water is allowed to pass during a simultaneous, vigorous aeration by means of air introduced via nozzles in the bottom of the basins before the water (sludge water) is led to a sedimentation basin for precipitation of what is called, in daily language, the bi- ological sludge. The water from the sedimentation basin is then led further on to process steps for chemical precipitation and/or direct to a recipient.

Outgoing water from the precipitation basin contains, however, too large amounts of suspended material and particularly at heavy loaded plants, the outgoing water will also contain large amounts of oxygen consuming material. The more pollutants, which are brought forward to the chemical precipitation step, the more chemicals are needed to reduce the amounts of pollut- ants to an acceptable level. However, there is a desire to re¬ duce the amount o chemicals which are used in a waste water pu¬ rification plant for several reasons, partly economical, as the chemicals is a great cost in the operation of the plant, partly for the risk of dissolving undesired side products, or at very acidic waters, release of dissociated aluminium or iron, which ions can damage biological life. Normally such a risk will not appear but the metal salts used will be precipitated with the so called chemical sludge.

Another process at waste water purification is pre- precipitation where an ingoing waste water is pre-precipitated using a coagulating agent in order to rapidly reduce the amount of settable material in order to reduce the volumes of the waste water plant. The larger the amounts of COD and BOD mate¬ rials, which are present, the larger is the load, and thereby a larger plant is needed for a certain amount of waste water.

Other processes are simultaneous precipitation and post- precipitation, whereby precipitation is carried out using a chemical flocculating agent in different steps of the waste wa¬ ter purification process.

WO 89/09193 discloses a device at sedimentation of sludge, which comprises two concentric cylinders , whereby the outer cylinder is provided with an inlet opening for the waste water, the inner cylinder, at its bottom is provided with an inlet and the two cylinders are provided with a common spillway from the inner cylinder over the outer cylinder. The device is. intended to create an increased dwell time in order to improve contact, and thereby formation of floes by the rotational movement which is created by forcing the water into the outer jacket forming cylinder and further up through the inner cylinder. The device provides a certain improvement, whereby, however, it has been realized that the dwell time and the effect in the inner cylin¬ der are not the expected ones .

Thus demands have been raised for an increased settling effi¬ ciency in the different precipitation steps and thereby a low¬ ered amount of outgoing suspended material to a subsequent pre- cipitation or recipient.

Description of the present invention

It has now surprisingly been shown possible to be able to re- duce the amount of outgoing suspended material by means of the present invention, which is characterized in that the outer cylinder is provided with an inlet, that the inner cylinder is provided with a spillway, that the inner cylinder is provided with a substantially conical insert arranged with its tapering end downwardly directed.

Further characteristics are evident from the accompanying claims .

By means of the present invention it is achieved that the amount of suspended material of a water of a subsequent set- tling step is reduced with up to 70%. The amount of oxygen con¬ suming material, particularly in heavy loaded plants, has also been reduced with up to 50%.

The invention will be described in the following with reference to the accompanying drawings, wherein

FIG 1 schematically shows a plant in accordance with the pre¬ sent invention.

Two concentric cylinders are denoted 1 and 2, whereby the outer cylinder 1 reaches over about half of depth of the inner cylin¬ der 2. The cylinders 1 and 2 have, in the embodiment shown, a common upper plane. The inner cylinder 2 is completely open upwardly and downwardly, while the outer cylinder 1 is closed downwardly. In the lower part of the cylinder 1 an inlet 3 is arranged and in the upper edge of the inner cylinder 2 an in¬ let spillway 4 is arranged. The area of the inlet 3 is about one third of the area of the inlet spillway 4. Further, there is a conical insert 5 in the inner cylinder 2 concentrically arranged with the other cylinders 1 and 2. The conical insert 5 is arranged with its tapering end pointing downwardly, and is further movably arranged in vertical position along its longi¬ tudinal axis. The diameter of the insert 5 is about half the diameter of the diameter of the inner cylinder 2. The insert 5 extends to about two thirds of the depth of the inner cylinder ⁵ 2, as well, preferably to 50 to 80% of the depth of the inner cylinder 2. The height position of the insert 5 can be adjusted in several ways, whereby in the accompanying figure, a scaffold 6 is placed over the inner cylinder and is provided with a mo¬ tor 7, which lifts, and lowers, respectively, a wire/chain 8 1-0 connected to the conical insert 5.

In using the device of the present invention in a sewage water plant, the device preferably being placed over a settling pocket, the sewage water is fed in through the inlet 3 of the ^■-⁵ outer cylinder 1, and will, by means of the jacket effect to be rotated upwardly, and falls into the inner cylinder 2, where it, by means of the conical insert 5 will be rotated downwardly in order to exit the device through the open bottom of the in¬ ner cylinder 2.

20

By means of the rotation both in the outer and in the inner cylinder the water will obtain a considerable dwell time, which influences the formation of floes positively. By means of the present invention the sludge yield can be considerably improved 5 and an increase with up to 25% has been determined in tests made visavi the cylindrical device shown in WO 89/09193.

At higher flow rates through the device the conical insert is raised in order not o counteract the flow too much, while at

30 low flow rates the insert 5 is lowered in order to provide the correct rotation in the device.

5

Claims

1. Device for increased separation efficiency at waste water purification or purification of other water with large sedimen¬ tation amounts and comprising two concentric cylinders, where the waste water is arranged to be introduced in the outer cyl¬ inder and is arranged to pass into the inner cylinder, charac¬ terized in that the outer cylinder (1) is provided with an in¬ let (3), that the inner cylinder (2) is provided with an inlet spillway (4), that the inner cylinder (2) is provided with a substantially conical insert (5) arranged with its tapering end downwardly directed.

2. Device according to claim 1, characterized in that the coni¬ cal insert (5) is movably arranged along its vertical axis.

3. Device according to claims 1-2, characterized in that the conical insert (5) extends over a depth which is 50 to 80 % of the depth of the inner cylinder (2).

4. Device according to claim 3, characterized in that the depth is two thirds of the depth of the inner cylinder (2).

5. Device according to one or more of claims 1 to 4 , character¬ ized in that the diameter of the base of the conical insert (5) is half the diameter of inner cylinder (2).