Cross-flow filtration system and method for filtering a solvent-particulate waste stream

A method for the filtering and reuse of a water-solvent-particulate waste stream derived from the cleaning of a printing press ink blanket by a water-solvent stream, which method comprises:

• a) washing a printing press blanket with a water-solvent stream to provide a water-solvent-particulate waste stream;
• b) pumping the waste stream into a gravity separator means to provide for the gravity separator of the water and solvent into a lower, water-particulate portion and an upper, solvent-particulate portion;
• c) pumping the water-particulate portion from the gravity separator through a water filter and the filtered water recycled to a blanket wash reservoir for reuse in washing the printing press blanket;
• d) pumping the solvent-particulate portion from the gravity separator through a solvent filter to provide a contaminated solvent stream;
• e) introducing the contaminated solvent stream into a processing container;
• f) pumping at a pressure of greater than about 25 psi the contaminated solvent stream from the processing container through a filter having a pore size of about 0.2 microns or less to provide a filtrate of a clarified solvent stream, while maintaining the flow rate of the contaminated solvent stream at less than about 0.05 gallons per minute per square foot of filter surface area;
• g) recycling after each startup of the filter the filtrate portion of the filter to the processing container for a period of time until the filtrate portion is relatively clear in color and suitable for reuse;
• h) removing the clarified solvent stream from the filter at a rate of less than about 3 gallons of flux per square foot of filter surface area per day;
• i) adding contaminated solvent stream to the processing container;
• j) recycling the clarified solvent stream from the filter to the blanket wash reservoir for reuse in the washing of the printing press blanket;
• and
• k) disposing periodically accumulated particulate-solvent sludge material from the processing container
• thereby providing for a closed loop recycling filtration method for a waste stream from a printing press blanket.