P2: Then and Now

This article's intent is to share recycling expertise so the reader can consider equipment to recover and reuse aqueous cleaners. We would all love to save the planet, keep it green, minimize waste and satisfy every other buzz phrase that is or ever was popular reflection of the sentiment toward reuse of vital resources. What if there actually is a way to reclaim all that wastewater generated from your washing operations? Pie-in-the-sky dream or reality?

The premise here is the latter. To begin, let us examine the concept, starting with an explanation of the heart of the technology used for equipment such as Washer Washer (small scale) and WWPro (larger scale) - membranes.

Membranes have been around for years in die casting plant applications. The two most common uses within the die casting industry are ultra-purification of incoming water and pre-treatment prior to sewer discharge. Focusing on the end-of-pipe scheme, the membrane selected often has pores that would be categorized as relatively "tight" - in hope of removing as much as can be achieved without severely curtailing the speed of processing. Materials of construction differ from vendor to vendor, but, in a majority of cases, consist of a polymer "skin" surface atop a fiberglass substrate. For limited pH range and ambient temperature projects, such as either of the above would typically be, these components serve well. However, when dealing with highly alkaline cleaners or very low pH combination phosphatizer/degreasers, especially at the elevated temperatures often seen in washing operations, they simply do not hold up. Additionally, the benefits of "tightness" prior to sewer discharge will now actually be detrimental to reuse because some of the "good stuff" may be removed during the processing.

Membranes intended for use in recycling are not so "tight," and are typically made to thrive under conditions where others might fail. Arbortech's equipment utilizes titanium dioxide membranes with a 316L stainless steel substructure. Hence, this module and others so designed can tackle applications where pH is anywhere from 0-14, at temperatures to 200° F - what it often takes to recycle water-based cleaners. The mechanism for removal and concentration of the "yuck" is cross-flow (not dead-end as in traditional bag or cartridge filters), pressure-driven (generated by a circulation pump) and multiple pass, with the long-term effect being that oils and soils are retained on one side of the membrane, while the water plus materials in true solution with water (like the cleaning product) pass through to the other side. With an in-line system set-up, permeate (that which passes through the membrane) is normally returned directly to the wash bath while the reject is slowly concentrated in a small (compared to the wash bath) process tank for later disposal. As a result, the wash bath stays perpetually near to freshly-made-up condition and the contamination concentrates in the recycling system's process tank instead of the wash bath, therefore no ( or at least greatly reduced) dump/recharge-just continual reuse. In one unusually successful case, a company that formerly dumped and recharged its 5000+ gallon bath quarterly before implementing a recycling system, only did so once in the next seven years... when they moved the operation out of one building and into another. While this performance is quite extraordinary, prolonging of bath life from 4-to-6 times is very common. Beyond extended bath life, what other direct or indirect contributions to the bottom line might be expected from installation of a good recycling system?

There are many factors to consider when purchasing a new washer water recycler such as part cleanliness, improved rinsing, increased production, less labor, cost efficiency and environmental benefits.