Flocculation process and device

Abstract

The present invention is in the field of laundry processes and devices. In particular the invention relates to the saving of water. It is an object of the present invention to reduce the water consumption in conventional washing methods, especially machine washing methods. It is found that the continuous pH controlled sequential dosing of an electrolyte, followed by dosing of a polymer and a solid liquid separation step during a full wash cycle of a washing machine, provides continuous clarification of the wash liquor and enables the continuous reuse of the water during said wash cycle.

1 . A process for continuous purification of wash water fro chamber using a sequential device comprising:
 a a first dosing point, in fluid communication with   b a first mixing point; in fluid communication with   c a second dosing point, in fluid communication with   d a second mixing point; in fluid communication with   e a solid/liquid separator unit, in fluid communication with   f the chamber (a)   
       wherein the process comprises the steps of:
 a pumping the water from the chamber into the sequential device; 
 b continuous, stepped or pulsed dosing of an electrolyte composition selected from aluminium and ferric salts to the wash water at the first dosing point; 
 c continuous dosing of a polymer composition comprising neutral or anionically modified poly acryl amide polymer (MW>100 kD) to the wash water at the second dosing point 
 
       characterised in that the dosing of the electrolyte and the polymer is controlled by the pH of the water between the first mixing point and the second dosing point, wherein electrolyte is dosed until the pH drops to between 6.8 and 8,2; and
 wherein the dosing of the electrolyte follows the dosing profile according to the formula: 
 C t   Electrolyte =C 0   Electrolyte e −v   0   t/V    
 
       wherein: C t   Electrolyte  means the concentration of electrolyte at any time t, C 0   Electrolyte  means the concentration of electrolyte at time t=0, v 0  means the volumetric flow rate at time=t at which the wash liquor is drawn from the wash and V means the total volume of wash liquor to be treated. 
     
     
         2 . A process according to  claim 1 , where a buffer composition is added together with either the electrolyte or the polymer at their respective dosing points, 
     
     
         3 . A process according to  claim 1 , wherein the solid/liquid separator unit comprises a:
 a particle filter; or   b a hydro cyclone; or   c a settling chamber;   
       or combinations thereof. 
     
     
         4 . A water clarification and purification device for operating the process according to  claim 1 , comprising an assembly for continuous purification of wash water from a chamber, using a sequential device, in fluid communication with the chamber comprising:
 a a first dosing point, connected to an electrolyte source, in fluid communication with   b a first mixing point; in fluid communication with   c a second dosing point, connected to a source of neutral or anionically modified poly acryl amide, in fluid communication with   d a second mixing point; in fluid communication with   e a solid/liquid separator unit, in fluid communication with   f the chamber (a)   
       characterised by a control system adapted for dosing of the electrolyte following the dosing profile according to the formula:
 C t   Electrolyte =C 0   Electrolyte e −v   0   t/V    
 
       wherein: C t   Electrolyte  means the concentration of electrolyte at any time t, C 0   Electrolyte  means the concentration of electrolyte at time t=0, v 0  means the volumetric flow rate at time=t at which the wash liquor is drawn from the wash and V means the total volume of wash liquor to be treated; and wherein electrolyte is dosed until the pH of the wash water between the first mixing point and the second dosing point drops to between 6.8 and 8.2. 
     
     
         5 . A washing machine comprising the water clarification and purification device according to  claim 4 , wherein the chamber is the washing machine tub or a separate wash water storage tank.