Water-based Ink Washes

 

What is Ultra-Filtration?

Very simply, Ultra-Filtration (or U/F for short) uses permeable membranes to separate water-based solutions, emulsions and suspensions. Under pressure, the membranes allow smaller molecules (such as water) to pass through the membrane and larger molecules (like ink components) to remain behind.

Why would I need U/F?

As more and more printers are converting from solvent-based cleaners to aqueous, the resulting spent cleaners become a problem. If you generate water-based ink wastes in your operations, you need to either dispose of the wastes off-site (which can be expensive) or treat them yourself to remove the waste contaminants. U/F is usually the most cost-effective and least labor-intensive way of treating aqueous printing wastes so the water can be discharged to sewer.

What happens to the contaminants?

With U/F we process in batches, either out of a tank or drum. The liquid being processed is pumped from the tank, through the U/F unit, and back to the tank – this is done as a constantly re-circulating loop. As the liquid passes through the U/F unit, a small amount of water diffuses through the membrane. The volume of waste in the tank drops as its contents become more and more concentrated with contaminants. This continues until no more water can be extracted, at which point the batch is done. The concentrated contaminants are then emptied to a drum or tank for eventual disposal. Now the process tank or drum can be re-filled with a new batch of waste.

How often do I need to change membranes?

One of the beauties of U/F is that the membranes typically last for one to two years. All that’s needed to keep them performing properly is to run a detergent solution through the U/F unit to remove the contaminants that build up on the membrane surface. The dirty detergent can then be transferred to the process tank for cleaning with the next batch if desired. The frequency of cleaning varies with the nature and level of contaminants. It can be after every batch or it could be on a weekly basis. Experience will indicate what works best.

How expensive is a U/F system?

U/F is almost always more cost effective than the alternatives when compared on a per-gallon basis. Off-site disposal is one of the most costly choices and allows a third party to expose you to potential long-term liability. Evaporators are expensive, have very high energy costs to operate, and often require permitting as a point source for air emissions. Chemical treatment requires expensive equipment and chemicals and is labor intensive.

U/F represents a one-time purchase of a machine, minimal costs for detergent, and replacement of the membrane every year or two. INFINITEX U/F machines are designed to be run with minimal labor. Someone needs to turn the machine on, and empty the concentrated contaminants when it’s done. The machines are fully automated and will shut themselves off when they finish a batch, if they run dry, if they get bumped or tilted, or if they sense any condition that could endanger either the machine or an operator.

The cost of a U/F system depends on the volume of waste you need to process. Typically as the daily volume goes up, the per gallon system costs decline. Our models start with machines that can process up to 50 gallons per day. Our larger units can handle thousands of gallons per day.