Abstract:
A method of treating liquid waste containing inorganic salt and organic matter. The method includes diluting the liquid waste by a large volume of water or clear effluent, and subsequently causing the organic matter to coagulate and form a sludge.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a treatment of coloured liquid waste.  
           [0002]    It is known to require a method of treating coloured liquid waste such as organic waste from a water treatment facility, for instance a magnetic ion exchange water treatment facility. Such waste can have a high salt concentration, a high level of sulphates and a high level of organic material.  
           [0003]    Common methods of treating waste containing high levels of organic material are not effective when the waste also contains a high salt concentration. Known methods of treating such waste require expensive processes.  
         SUMMARY OF THE INVENTION  
         [0004]    In accordance with the present invention there is provided a method of treating aqueous liquid waste containing inorganic salt and organic matter, the method comprising the steps of diluting the liquid waste with aqueous liquid, causing the organic matter to settle and separating the inorganic salt from the organic matter. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]    The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0006]    [0006]FIG. 1 is a flow chart showing the method of the present invention in a first embodiment;  
         [0007]    [0007]FIG. 2 is a flow chart showing the method of the present invention in a second embodiment; and  
         [0008]    [0008]FIG. 3 is a flow chart showing the method of the present invention in a third embodiment. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0009]    Referring to the Figures, there is shown a Magnetic Ion Exchange Water Treatment Plant  12 , with a waste stream  14 . The waste stream  14  typically contains 20 g/L dissolved organic carbon (DOC), 7-20 g/L sulphate and 100 g/L NaCl, although it will be appreciated that the invention may be applied to other concentrations. The waste stream  14  is fed into a balancing storage tank  16 . The balancing storage tank  16  is preferably sized so as to contain the waste generated over at least 24 hours.  
         [0010]    A waste water treatment plant  18  is also shown, with a wastewater inlet stream  17  and an clear effluent discharge flow  20 . The clear effluent discharge flow  20  may be a primary, secondary or higher treatment level effluent discharge flow and is composed of treated waste water, which is in a condition to be discharged to the environment. A proportion of the clear effluent discharge flow  20  is diverted to a tank input stream  21 .  
         [0011]    The tank input stream  21  and the waste from the balancing storage tank  16  are combined at an interchange  22  to form a combined stream  24 . The combination is such that the dilution of the waste by the clear effluent may be in the order of 20:1 to 100:1 by volume.  
         [0012]    In an alternative embodiment, the waste stream  14  may be fed directly to the interchange  22 , this eliminating the balancing storage tank  16 .  
         [0013]    The combined stream  24  is typically augmented by the addition of a coagulant  26  such as alum, ferric salts and/or polyelectrolytes. The coagulant  26  may be added to obtain a concentration in the order of 10 to 20 times that of conventional water treatment processes. The concentration of the coagulant  26  can, however, be varied according to the coagulation conditions. A preferred coagulant  26  is ferric chloride used in sufficient quantity to create a concentration of between 300 mg/L and 500 mg/L within the combined stream  24 .  
         [0014]    After a delay to initiate flocculation, typically about 3 to 5 minutes, the combined stream  24  may be further augmented by the addition of flocculants  28  such as anionic or nonionic polyelectrolytes. The flocculants  28  are added to the combined stream  24  in concentrations similar to that of the coagulant  26 , but these concentrations may also be varied according to the flocculation conditions.  
         [0015]    A tapered flocculation tank (not shown) may be used if required.  
         [0016]    The combined stream  24  is then fed into a clarifier or thickener  30 . It will be appreciated that the clarifier or thickener  30  may be replaced with flotation or other separation techniques.  
         [0017]    The clarifier  30  acts to separate the combined stream  24  into clarified brine  32  containing sulfates and a sludge  34  containing the organic matter and the added chemicals.  
         [0018]    The clarified brine  32  can be released into the environment, for instance into the ocean. The clarified brine  32  may be injected into the effluent discharge flow  20  for release into the environment.  
         [0019]    The sludge  34  can be further treated in a sludge thickener  36  or a centrifuge or other dewatering devices before being discharged to be used in landfill. Alternatively, the sludge  34  can be discharged to a lagoon for evaporation of excess water.  
         [0020]    A further alternative is for the sludge to be combined with biosolids extracted in the waste water treatment plant  18 .  
         [0021]    A second embodiment of the present invention is shown in FIG. 2. In this embodiment the sludge  34  is directed to the waste water treatment plant  18  for treatment.  
         [0022]    A third embodiment of the present invention is shown in FIG. 3. In this embodiment the combined stream  24 , augmented by coagulants  26  and flocculents  28  is directed to the waste water treatment plant  18 . In this embodiment the waste water treatment plant  18  replaces the clarifier  30 .  
         [0023]    Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.