A basic understanding of reclaim systems will go a long way before choosing one for your carwash. We all know that manufacturers of any type can provide positive references, but it’s important to realize that water chemistry, climate conditions, wash systems and chemicals all conspire to produce good results.
In this article, we’ll take a look at the important necessary characteristics to consider when purchasing a water reclaim system.
It’s dirt, man, and it has to go somewhere
The water from washing cars is really dirty. It possibly contains earth, sand, salt, organic material such as bird droppings, oil, wax, surfactants (detergents, soaps), and any manner of other dissolved or suspended solids.
These contaminants must be altered and/or removed to an acceptable degree from the wash effluent before the water is reclaimed sufficiently for reuse as wash (not rinse) water. They must be substantially treated and removed from the water released somewhere.
The material to be removed may go to just one place (your settling tanks if using biological or chemical systems with auto back wash filters) or it can be split between two places if you use a chemical system with bags filter and the settling tanks. (For more on bag filters, see sidebar.)
Biological, chemical, and filtration systems all work best under different conditions.
If filters are being used, the first sediment remover is usually a vortex or cyclone filter which ejects heavy suspended solids, especially sand, with the effluent usually going to one of the settling tanks. This is a constant process because vortex filters don’t have a place for the sediment to accumulate and depend on a constant flow of the effluent. If your system has a valve in the drain line from the vortex filter, it must be at least partly open at all times.
After the cyclone filter (also called “sand separator”) the system has bag filters, possibly an activated charcoal filter, and/or auto backwash filters.
The system costs, filter efficacy, maintenance requirements, and rate of sludge build-up in the settling tanks are different for the different filter methods, and are entirely the choice of the buyer. Reclaim manufacturers may offer all choices, and it is important that you understand accurately the differences in labor, cost and results before you invest in a reclaim system. Don’t be afraid to grill your salesperson.
Two hybrid filter schemes
At least one manufacturer offers a sludge interceptor for use with an auto backwash filter. The sludge interceptor does use an off-line bag, which requires maintenance similar to normal in-line filter bags, but far less frequently, and it will keep nearly all the sludge from the auto backwash filters out of the settling tanks.
Remember that auto backwash filters can filter only down to about 25 microns, and that is coarser than many pump manufacturers recommend. There are systems available which offer an in-line bag filter at 10 microns or so following the auto backwash filter.
While this again requires bag maintenance, it is far less frequently because the bag is capturing only solids smaller than 25 microns that pass through the ABF filters. You end up with a low-maintenance system, but with reclaim water filtered down to 10 microns for cleaner filtrate and longer mechanical equipment life.
Selection of wash chemicals
Although not a part of the reclaim system itself, it is prudent to consider the choice of wash chemicals at the same time you are selecting your reclaim system, because they can greatly influence the operation of the reclaim system. This is not to say that your reclaim system will not work with non-friendly (to reclaim systems) chemicals, but it will work better using reclaim friendly chemicals.
Your reclaim salesperson should be able to give you more specific information on the effects of friendly and non-friendly chemicals as well as supply you a list of claimed reclaim friendly products from several manufacturers. Again, you have a wide range of choices. Be informed and choose prudently.
Reclaim compatible chemicals
Some wash chemicals, e.g. pre-soaks, soaps and detergents, tire cleaners, windshield treatments, waxes, etc. are claimed to be reclaim compatible and some are not. Because there are different reclaim methods, it is possible that some chemicals are compatible with one method but not another.
I have studied the claims of many manufacturers and have never seen a specific type of reclaim for which a chemical manufacturer claimed or disclaimed compatibility. Probably the best that you can do is to get it in writing, for example on a specification sheet or a catalog listing, that your chemical selections are reclaim compatible, and you will probably be OK.
That’s all, folks (for now)
There are many subjects that beg to be expanded upon, such as the relative merits of reclaim systems that are filter only, versus biological, versus chemical (ozone), as well as their effects on the chemistry of various contaminants, and a more detailed discussion of when auto backwash filters do need maintenance. We’ll have to get to these in Reclaim 201.
Keith Brecken has been an engineer since 1954 and is enjoying his “third career,” this time in the water treatment and reclaim industry, as director of operations & marketing for Custom Applied Technology (CATEC) in Sarasota, Fl.
He was most recently president of T’comm Enterprises, Inc. from which he retired in 2001. He can be contacted at (941) 751-5656 or via email to firstname.lastname@example.org