Abstract:
A method and means for cleaning surface or waste water in which the water is supplied to a sludge separator ( 14 ) for the separation of suspendable material. 
     After the sludge separator the water is supplied to a biostep filter in which pollution is deposited at at least one filter body ( 42, 48 ) of permeable material of a type on which a bioskin may grow to create microprocesses without the permeability decreases and thereafter further to a sorbent filter ( 28, 40 ), whereby the water after this flows to a recipient. A pump ( 24, 124 ) is connected to the plant, preferably between the biostep filter ( 18, 42 ) and the sorbent filter ( 28, 40 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method for cleaning water, especially surface or waste water from buildings or roads, which water is directed to a sludge separator for separating suspended material. The invention also relates to means for carrying out the method. 
     2. Description of Related Art 
     Cleaning of sewage water from separate building or roads or small groups of houses has up til now been effected by a low degree cleaning wilt sludge separators, such as three compartment septic tanks. The water flows by gravity to the well in which coarse pollution sediment at the bottom of the wells. One to two times a year the well is emptied. 
     One type of sludge separator or septic tank is known from U.S. Pat. No. 4,997,562. The tank shown in this document is divided into a plurality of chambers in which the water to be cleaned is brought from each chamber to the next by means of a overflow valve so arranged that the chamber is filled with water up to a certain level before the water flow over to the next chamber. This is for preventing sedimented sludge to leave with the water. At the end of the separator a filter chamber is provided in which the water is filtered through sand and a fibrous organic material. 
     AT-B-396921 describes cleaning means in the form of a three compartment septic tank in which the water passes-one chamber for sedimenting sludge, one cleaning chamber and one filter bed. To increase the effect of the cleaning chamber, a plurality of walls are arranged so that the water is urged to flow in a loop through the chamber. 
     AT-363871 describes cleaning means with three or four chambers, namely, a sludge separator, a filter chamber, an aerating chamber and a final sedimenting chamber. In the filter chamber the water passes from the bottom of the chamber up through a biofilter. 
     Even if the use of sludge separators is an inexpensive and simple measure, the described cleaning measures, in accordance with higher environmental consiousness, are insufficient since they do not fully take care of biological material and/or phosphorus and not at all take care of heavy metals, which therefore come with the water to the recipient. 
     SUMMARY OF THE INVENTION 
     The main object of the invention is therefore to provide a method and cleaning means, which is simple and inexpensive to install and run, but notwithstanding this, result in a high degree cleaning of the water. 
     This object is achieved by giving the invention the features stated in the following claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will in the following be described in more detail in connection with embodiments, illustrated in the drawings, for the effectuation of the method. 
     FIG. 1 illustrates schematically cleaning means according to the invention. 
     FIG. 2 illustrates another embodiment of cleaning means according to the invention. 
     FIG. 3 illustrates a plan view of the means according to FIG.  2 . 
     FIG. 4 illustrates in a larger scale a section through a biostep filter, which may be used in the plants according to FIGS. 1 and 2. 
     FIG. 5 illustrates in a perspective view an altered embodiment of a sorbent chamber. 
     FIG. 6 illustrates a section through the chamber of FIG.  5 . 
     FIG. 7 illustrates a section like in FIG. 6 of an altered embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The plant illustrated in FIG. 1, may for example be used to take care of surface water at roads and the like. The water flows from an existing road embankment  10  or via a conduit  12  in a known way to a sludge separator, such as a three compartment septic tank  14 , in which the most coarse particles sediment from the surface water and stay at the bottom of the well. The sedimented material in the well is emptied at regular intervals, for example 1 to 2 times per year. The water from the sludge separator.  14  is directed via a conduit  16  to a biostep filter  18  in which a degradation of biological material occurs, which is described in more detail below in connection with FIG.  4 . The filter  18  has a surface of permeable, sintered pure polyethene on which microorganisms are acting. In the filter  18  the water rises through the filter insert to the level of a conduit  20 , which directs the water to a pump station  22  in which a, for example, submersible pump  24  pumps the water to a level from which it, via a conduit  26 , flows to a sorbent chamber  28  in which the water, via a manifold pipe  30  with nozzles, is spread and sprinkled over a sorbent material which reduces by an ion exchanger process the content of phosphorus and nitrogen of the water and where appropriate, also heavy metals. The sorbent material may comprise one or more materials, for example polonite™, a calcium silicate which is provided on a perforated bottom. The material is exchanged for example once a year and may after the reception of phosphorus and nitrogen be used as soil improvement agent. From the sorbent chamber flows now the high degree cleaned water via a conduit  32  to a recipient, which could be a lake, moss or the like. 
     A The plant illustrated in the FIGS. 2 and 3 has in principle the same structure as the plant according to FIG. 1, but has a more compact embodiment for use as a smaller sewage plant, for example for separate houses or groups of houses in sparsely-populated areas. The parts comprised in the plant according to FIGS. 2 and 3 have thus obtained the same reference numerals as the corresponding parts in FIG. 1 with an additional 1 in front of the numeral. Thus, the waste water from a building or a group of houses is directed via a conduit  110  to a sludge separator  114 , which for example is of the three compartment septic tank type. The desludged water is thereafter directed via the conduit  116  to the biostep filter of the plant, which filter comprises a compact house  34  divided into three chambers  36 ,  38  and  40  which comprises biostep filter, pump and sorbent filter respectively. The biostep filter has in this embodiment only a filter insert  42  provided in the filter chamber  36  and the water flows, after the passage through this insert  42 , over to the pump chamber  38  where it is pumped by the pump  124  to the upper portion of the sorbent chamber  40  where it via a nozzle  44  is sprinkled and spread over the underlying sorbent material. The sorbent material may thus be a zeolite material or polonite™, as mentioned in connection with the description of FIG.  1 . It is advantagously to stir the material, for example mechanically or by pumping (backflushing) the water through the material, to prevent clogging of the material and also to improve the cleaning effect. The water may also, instead of be sprayed over the material, be supplied through a conduit at the bottom of the sorbent material and pass upwards through the material to an outlet pipe provided above, which will be described in more detail in connection with FIG.  7 . The cleaned water is directed via the conduit  132  to a recipient. 
     In FIG. 4 the bio step filter  18  of FIG. 1 is illustrated in a larger scale. The water flows into the lower part of the filter chamber  46  from the conduit and rises upwards in the filter chamber by hydrostatical pressure and passes through the cylindrical filters  48 . Their cylindrical or pipeshaped filter bodies  48  are of a permeable material, such as sintered pure polyethene, which forms the bottom and walls of the pipe, while the pipe is open upwards. The permeable material is of a type on which, by means of microorganisms, a bio skin may grow to create micro processes without lowering the permeability. The filters  48  lowers in this way BOD-content in waste water and prevent suspended material to reach the following sorbent filter. Thus, at the filters a coating of deposited pollution is formed, which may be flushed clean at regular intervals, for example one to two times a year. The filter bodies  48  are provided, at the top around the opening, with an upper flange  50  with its aid they are sealingly inserted in a plate  52 , which in turn, with an inbetween support of a seal  54 , rest on a bracket  56  provided around the inner periphery of the chamber  46 . The plate  52  is provided with struts  58  with which the insert with the filters  48  may be placed on the ground outside of the well for washing of the filters  48  and which struts  58  are dimensioned in such a way that their weight keeps the plate  52  with the filters  48  pressed against the seal  54  against the pressure of the through flowing water. 
     For lifting the filter insert out of the well  46 , the plate is provided with mountings  60  for a lifting yoke  62 , which is provided at the top with a ring  64  for connection to a lifting hook (not shown). The water which comes in through the conduit  16  flows through the permeable mantle surface of the filters  48  while depositing pollution on said surface, as described above, into the inner of the pipeshaped filters and flow out from the opening of the filters  48  above the plate  52  and further to the outlet conduit  20 , which leads to the pump station  22 . 
     The sorbent chamber  70  illustrated in FIGS. 5 and 6, which may be inserted instead of the sorbent chamber  28  in FIG. 1, comprises a concrete bed  72  in which a number of receptacles  74  are provided, which comprises the sorbent material  76  (FIG.  6 ), for example of the type previously mentioned in connection with FIGS. 1 and 2. As emerges from FIG. 6, the sorbent material  76  is filled up in the receptacles  74  to a level “h”. Above the receptacles  74  is a water supply system provided comprising a central pipe  78  and to this, above every pair of receptacles  74 , connected spray nozzle holder  80  for supporting nozzles or spray nozzles  82 , whereby the pipe  78  and the holder  80  rest on beam profile  84 . The pipe  78  is at its far end closed by a terminal end  86 , while the fore end has connection means  88  for connection with a supply conduit for the water, such as the conduit  26  in FIG.  1 . The sorbent material  76  in each receptacle  74  rest at a bottom  90  of a net or trellis-fabric so that the water after passing the sorbent material  76  may run down into a channel  92  arranged under the bottom  90  and from there via an outlet pipe  94  to a recipient 
     At the embodiment illustrated in FIG. 7 of the sorbent chamber, supply pipes  96  for the water are brought down into the sorbent material  76  with the height h, which pipes open at the bottom of the material. At the supply pipes  96 , agitators  98  is journalled, which stir and keep the sorbent material  76  in movement. This may, as mentioned above, be polonite™, whereby the stirring of the material is done to prevent the forming of lumps and also to improve the cleaning effect. After the water has passed through the sorbent material to its upper portion it is directed away via the conduit  100  to a recipient. 
     As emerges from the above, a method and means according to the invention are provided for taking care of surface and waste water in an effective and inexpensive way even though a high degree cleaning of the water is obtained so that it without impact on the environment may be released to a natural recipient, such as a lake, river or moss. Further, the sludge separated in the sludge separator  14  may after suitable processing, such as composting, be used as soil improving agent and the sorbent material in the sorbent chamber  28 , which is a natural material with high phosphorus binding capacity, may likewise be used as soil improving agent as it also easily emits phosphorus again to the vegetation.