WO1998040572A1

WO1998040572A1 - Street sink

Info

Publication number: WO1998040572A1
Application number: PCT/SE1998/000409
Authority: WO
Inventors: Bo SÖDERGREN
Original assignee: Prolup Absorbenter Ab
Priority date: 1997-03-10
Filing date: 1998-03-09
Publication date: 1998-09-17
Also published as: NO994374D0; SE513035C2; SE9700841D0; PL335565A1; AU6427898A; NO994374L; EP0991825A1; SE9700841L

Abstract

Insert for a street sink where below the inlet of the sink is arranged a filter holder and in this is arranged a filter bag so that oncoming water is filtered through the bag. The bag contains absorption means for oil and can be closed. A grid is arranged over the bag and above this below the sink inlet is arranged a collar or funnel like part that leads the water in from the sink edge securing that water pours down into the filter. Between the filter and the lid of the street sink is arranged a space with lateral passages so that at filled filter or too poor percolation in this water can pass the filter on the outside.

Description

Street sink

At street sinks it is known to arrange a sand trap in the bottom in the shape of a recess below the outlet level of the sink hole. The sand trap functions so that sand that has come into the sink hole sinks down into the sand trap without being swept away by the water flowing away from the sink hole. Since the water movements in the sink hole are comparatively seen calmer than in inlet and outlet the sand has time to sink to the bottom. The sand can then be removed from the sand trap by the sink lid being lifted and the sand being removed by sludge suction, bucket or the like.

In most cases these street sinks work satisfactorily. In some cases however the function is not satisfactorily. This occurs for instance if the material that by the water is brought along to the street sink is too fine, that is with a too small particle size. This material will not have time to sink down into the sand trap in the sink hole but is instead swept away by the water through the outlet, then to accumulate somewhere else in the system where at last the flow speed becomes so low that even these small particles have time to sink to the bottom. This may occur in the outlet pipes as well as in the outlets of these into water courses. In both cases more or less difficultly handled and unwanted problems may result.

Nor are panicles caught in the sand trap of a street drain that has a density that is lower than the water or close to this. Such particles as for instance rubber particles, car tires and other organic material does not sink to the bottom of the water but is swept away with this out in water courses that are polluted by this. In particular at larger collection systems for surface water, as for instance in larger cities this can become a considerable problem. During similar conditions also oil, asphalt and other petroleum products may become a problem when the collection area increases. The total volume of with the water transported oil and the like becomes an environmental problem. In this connection it should perhaps be noted that it is not possible to arrange cleaning plants for the surface water since the water volumes are too big. This in particular in countries with much fall of rain.

The object of the invention is to eliminate the above environment problems so that a cleaner surface water is delivered to collecting water courses.

In accordance with the invention this object is solved by instead of trying to arrange a central cleaning of the surface water this is cleaned in the other end of the system, that is at each street sink. In each street sink a basket or the like of net or perforated sheet is arranged and in this is arranged a filtering fabric lining. The tightness of the fabric is chosen so that desired cleaning is achieved and the area of the basket or corresponding is dimensioned so that at least normal water flow amounts have time to pass through the fabric.

Preferably an inward/downwards sloping collar is arranged below the street sink lid centering the oncoming water securing that this gets into the basket. Between the upper edge of the basket and the street sink lid or the collar respectively is left a space allowing the water at extreme torrential rains to pass on the outside of the basket when the filtering quite simply can't cope. The water may also take this way if the filtering basket should have been filled with collected material.

With advantage the basket hangs in chains that in turn are fastened in a collar that is placed below the street sink lid. The chains allow lateral adaption of the basket location in case the street sink inlet in the street has become displaced in relation to the sink hole. The basket may advantageously be square with chains in the corners. Since it is usual with street sink inlets that are square preferably also the collars are square and possibly adjustable in one direction for adaption to the varying length measurements that can occur for sink lid casings. The chains may be so long that the distance between the lower edge of the collar and the perforated roof or lid is a decimeter or more.

In order to prevent oil pollutions from getting out into the surface water ducts preferably in the basket inside the fabric an oil absorbing means is arranged, for instance in accordance with the Swedish patent application SE 9603221-4, that is a means that absorb oil but that remains uninfluenced by water and that furthermore floats on the water. The filling degree of the oil absorbing means is chosen according to the expected composition of the pollution. Since the means is comparatively cheap and easily destructible one can allow an excess capacity providing a buffer against unintentionall outlets due to for instance traffic accidents and the like.

Above the basket and closing this upwards is a net, perforated sheet or the like arranged. The net fills several functions. To start with a comparatively nonturbulent entering stream of water into the basket is secured reducing the risk of in this present collected material being whirled up and swept over the edge of the basket. Secondly the absorbing means present in the basket is prevented from flowing out of this. The net has preferably a slight roof form, that is an inclination outward downwards so that larger pollutions as branches and stones easily slides off and further down into the sand trap of the sink hole. In order to secure this function it may be of advantage with a perforated sheet of stainless steel, since the remains smooth and slippery at the same time as the holes allow sufficient percolation.

An additional result of the applied net is that even if for one reason or another a street sink lid is removed there is no risk that anybody falls down into the sink hole since the net and the basket prevents this. Due to the low centers of gravity of the basket the risk that this protection against falling down falls away is very small, for a lid to become dislocated it is sufficient with a movement corresponding to the height of the lid. The sink insert ca however not be dislocated in the same unintentionally way. If so is desired also particular locking means can be arranged to prevent unauthorized removal. This is also possible to do with street sink lids but that is considerably more difficult since the street sink lid must be able to withstand the traffic.

The filter material in the basket is preferably arranged in the shape of an insert bag that regularly or when needed is removed and replaced with a new one. The new bag can already at delivery be filled with absorption means for oil and closed in an appropriate manner, for instance by means of a velcro tape or a channel running around the bag with a string therein. If the bag is large it may also be provided with suitable handles for lifting manually or with the help of machinery. The bags are of course preferably made of combustible material that can be burnt together with the oil absorbing material. In this way a certain heat energy is retrieved and furthermore through flue gas cleaning present pollutions can be concentrated in a comfortable way.

One can also consider the upper side of the bag being covered with a fabric membrane with sufficient porosity to let through the pollutions that are to be collected in the bag but sufficiently small to retain the absorbing means and achieve an even flow respectively.

If large street sinks are used alternatively if the shape of these are not circular one can consider to arrange several baskets with matching filter bags in modules. This keeps the weight of the handled bags low and at the same time the filter area can be made large. Furthermore one may sometime achieve the effect that the filter bags feedwise will lie after one another so that it is always one and the same bag that is filled first.

If the amount of sludge that comes to the street sink is large this may adhere and silt together to a sealing surface layer on the bag or the absorbing means in the bag so that this can not exert its cleaning effect on the passing water. In order to remedy this centrally from the upper side of the absorption means a sludge receiving recess is arranged. This can be achieved by means of a centrally placed vessel that is open upwards, but water penetrable downwards and to the sides. For instance the vessel may be made of net or sheet metal with punched holes and be held in place by means of two arms that diametrically extend between net and basket where they are held by the net lid fastening.

The central perforated vessel will receive a collection of sludge on the bottom but the water can still flow out into the absorption material through the sides of the vessel. Between the bottom of the vessel and the bottom of the basket a sufficient distance exist to allow the presence of absorbing means since otherwise water would be able to flow through without being cleaned. Even if sintering sludge would seal the absorbing material on the upwards turned surface water can still enter through the sides of the vessel.

As an alternative to the arranging of a special vessel that extends down into the absorbing material one can consider to shape the bag that holds the absorbing material with a central recess.

The bag containing the absorbing means can either be open upwards or be close upwards. At this it may however be preferable that its upper side as possible inward turned surface has larger openings to let pollutions in that are to be caught by the filter. One can even consider the bag (of plastic) being welded to a netlike lid (of plastic) that on its bottom side is provided with the perforated sludge collecting vessel. In this way the insert can be changed very fast and through a suitable choice of material the insert may be burnt in its entirety.

For the case that the amount of sludge is unproportionally large one can either consider to empty the central sludge collecting vessel more frequently than changing absorption material or that the sludge collecting vessel is made larger at the expense of the volume of absorption means.

Further advantages an characteristics of the invention are apparent form the claims and the following description of an embodiment shown in the enclosed drawing.

The water cleaning device for street drains shown in the drawing includes an insert 1 placed in a sink hole 2 provided with a lid 3. The insert 1 includes in the upper end an all around going flange 4 with which the unit grips over and hangs in the same sink flange 5 that support the sink lid. In level with the flange 4 a removable inner collar 6 is arranged. The collar sees to that the water flows a distance towards the middle of the unit 1. At a distance below the collar, for instance 5 - 10 cm a net 7 is arranged. Between the flange and the net openings 8 are arranged for the diversion of the water past the insert if this should be silted up or not be able to cope. These openings can be constituted of intervals between hooks for hanging. Below the net the insert has the look of a basket or perforated bucket 9 provided with perforations in the side as well as in the bottom. In the bucket is placed a bag 10 of filter material. The bag is in the shown case folded over the upper edge of the basket and is held in this position by the net that has been applied from above. For the lifting of the net this is provided with a suitable handle as is the bag.

When the water flows into the street sink through the perforated sink lid it is fed inward by the collar and falls down on the net. Gravel and rocks that are brought along by the water lands on the net and are with time due to the inclination of the net flushed outward down past the sink insert and down into the sand trap at the bottom of the sink hole. The water together with remaining pollutions pours down into the basket where the particle shaped pollutions are retained by the filter material in the bag. Oil and the like is retained by adhering to or being sucked up by the absorption means. Since the absorption means is considerably lighter than the water and possible light pollutions as rubber particles a part of the absorption means will always float up on top in the bag. This prevents other light particles from being swept out of the basket if the flow resistance should become too large in relation to the oncoming amount of water. The absorption means helps so to say to retain captured material in the bag.

The added absorption means in the bag also reduce the risk in cold whether that in this collected moist material should blast the insert.

As is apparent from the above description the invention offers the possibility of good and effective cleaning of water to a very reasonable price. Existing sinks do not have to be changed and its only necessary with an extra insert. If the sink lid should be lifted too much of the flange of the insert one can consider for instance to make a corresponding machined recess in the edge of the sink lid.

As realized the service time for each street sink becomes considerable shortened in relation to the emptying of a sand trap. By the choice of mesh for the net the amount that is to be allowed to pass on down to the sand trap can be controlled and how much of sand and the like that is to collected by the bag. The removal of a lid, lifting of the net and the bag and the lowering of a new bag and the replacing of net and sink lids is done in a few minutes. The bag weights can be held moderate and consequently easy to handle. Even the following handling of the collected material can be made simple and rational in a centrally placed plant where bags and absorption means are burnt and other collected material is taken care of in a suitable fashion. Due to the short time that it takes take care of a street sink the influence on the trafic normally becomes very small. If so wished the net can be made concave, that is bulging downwards or corrugated or shaped in some other way to catch larger particles as stones and the like so that these can be removed by the lifting of the net so that thereby the considerably more complicated emptying of the sand trap on the bottom of the sink hole is eliminated or considerably reduced.

Preferably the basket or filter container is not provided with lateral outlets higher up but only up to the level that is filled with absorption means. In this way is secured that water not pours out on the side without oil cleaning, that is passage through the absorption means.

The cleaning means in the filter bag may in addition to oil absorbing material include other materials to reduce the load on the environment. For instance it may comprise 80% of the above mentioned oil absorbing hydrophobic material, 10% active carbon and 10% celite, the percentages related to volume percentages. In this way chemically active pollutions as heavy metals effectively can be removed from the water. The celite may be in natural as well as synthetic form.

Claims

1. Insert for street sink, characterized in that below the inlet of the street sink a basket or filter holder is arranged and in this is arranged a filter bag so hat flowing water is filtered through the bag and the basket then to flow further down into the sink hole.

2. Insert according to claim 1, characterized in the bag containing absorption means for oil and/or means for taking care of chemically active substances and heavy metals respectively.

3. Insert according to claim 1 or 2 , characterized in the bag being closable.

4. Insert according to any of the preceding claims, characterized in that the bag is provided with a lifting handle.

5. Insert according to any of the preceding claims, characterized in that a grid or a perforated sheet is arranged over the bag.

6. Insert according to claim 5, characterized in that the grid or the perforated sheet is rooflike and inclined outward downwards so that objects that are too large to pass through can slide off to the side to fall down into the sand trap of the sink hole.

7. Insert according to any of the preceding claims, characterized in that below the inlet a collar or funnel-like part is arranged that leads the water in from the edge and secures that this falls down over the basket.

8. Insert according to any of the preceding claims, characterized in that between the basket and the lid of the street sink is arranged a space with outlet passages laterally so that at filled basket or too bad flow through this the water can pass the basket on the outside of this.

9. Insert according to claim 8, characterized in that the basket hangs in chains fastened in a collar or the like.

10. Insert according to claim 1, characterized in that a sludge retaining vessel is arranged in the absorption means and opens upwards and perforated towards the absorption material laterally and downwards so that even if sludge accumulate on the bottom of the vessel and the upper side of the absorption material the water can through the sides of the vessel continue into the absorption material.

11. Street sink characterized in that it includes an insert according to any of the claims 1 - 10.