Let’s examine a few myths circulating through the surfacing industry about water recycling systems:
1) Gravity settling, chemical based systems produce clear water acceptable for CNC spindles and critical polishing applications.
2) Gravity settling, chemical based systems take 10 minutes a week to maintain.
3) Filter press based systems take too long to maintain.
4) Air filters and water curtains are the most effective way to deal with air borne silica.
How effective are gravity settling systems?
The surfacing industry includes several gravity settling system suppliers that claim chemical / flocculent based systems can supply closed-loop recycled water good enough for CNC spindles and critical polishing applications. This often includes a requirement for additional settling tanks, and consumable filters to reduce the micron size in their recycled water just to achieve five micron. However, at five micron the recycled water may still be cloudy and inadequate to prevent deposits from accumulating over time causing spindle failure. No such problem exists with Water Treatment Solution’s (WTS) “crystal clear” filter press based solutions. For more than 20 years all of the WTS systems have been designed to provide crystal clear water (looks like bottled water) filtered to non-detectable suspended solids levels.
WTS filter press based solutions do not require chemicals to dewater and filter natural and engineered stone slurry in creating crystal clear water. WTS always puts in writing that the crystal clear water is guaranteed for as long as you own the equipment, provided you maintain it as the company recommends. Be sure to ask for that same guarantee as you research different systems for your facility.
Does it really take just 10 minutes a week to maintain a gravity settling system?
Simply managing the bags filled with wet stone slurry will take longer than that. They cannot be disposed of directly from the system – they must be set aside and allowed to dry for some time before they can be hauled off site. The solids collected in a gravity settling bag often contains twice the water content of the solids generated by a filter press, hence drying to remove multiple gallons of water is required – not to mention the daily clean up. Some companies that haul this waste insist you remove the bags before they will transport to some landfills. But most importantly, the chemicals used in these systems are difficult to control based on variations in production volumes, dwell time in their tanks, natural stone vs. quartz vs. other materials require adjustments to the chemistries, pH may need to be adjusted, filters must be monitored and changed. These procedures, adjustments and service points require labor. Be alert to those who promotes a “set it and forget it” design – as all recycling systems require some form of maintenance. Also keep in mind the need to protect employees and equipment from the corrosive nature of these chemicals – just review the labeling and the PPE requirements on a properly prepared SDS.
How long does it really take to properly clean a filter press?
It is true that filter presses often require 30-60 minutes to complete a proper cleaning cycle. Depending on size, production volumes and the balance of clear water (filtered to less than 2 micron) and gray/white water (filtered to roughly 25 micron) this usually occurs once or twice a week. The recycled water supplied to each piece of fabrication equipment is specified by the manufacturer – so each WTS System is designed for current and often future equipment that a fabrication shop has and plans for.
When we hear that some shops take many hours to clean a filter press, and others require more frequent cleaning – it is important for us to work with the customer to ensure that the service points are being done in a correct and efficient manner. After more than 20 years of designing filter press based systems there are reasons why these systems fall outside the norm, and we can help! Some shops have a high turnover rate, and lack of proper training is one of the key factors in incorrect maintenance of a WTS System. Many shops have experienced growth in production levels that could not have been foreseen in the beginning. A filter press is no different than any other piece of equipment in the shop in terms of its limitations. If production levels grow from say, 500 sq. ft. a day to 1,000 sq. ft., the fabricator has likely added cutting and polishing equipment to keep up with demand. The filter press is no different, it must be expanded, possibly upgraded or a second filter press added to the design. Failure to adjust the water recycling system will invalidate its design principles (the same is true of a gravity settling system).
Different levels of automation can be added to an existing filter press to help manage this growth or to upgrade an older, larger design that may be purely manual. This can be done at substantially lower cost rather than abandoning the system. Also consider that after a WTS System has been in operation 5 – 7 years that it might require a service call from WTS to ensure its efficiency.
Please note, simply removing filter cake from the filter press requires less than five minutes – you can see this process on our web site at www.watertreatmentonline.com. Customers have told us that they have spent as much time maintaining a gravity settling, chemical based system as you would our filter press based solution.
Can you manage your crystalline silica levels with a recycling system, air filters and water curtains – which is the best method?
When you are looking at water recycling systems be sure to discuss how the system can help your shop reduce the crystalline silica levels. Simply incorporating a wet fabrication process is not enough to meet OSHA requirements. The best method to control crystalline silica levels is by using a recycling system that helps to capture as much of the stone sediment as it can and to keep it from drying on the floor & then becoming airborne dust. WTS’s filter press systems produce crystal clear recycled water and using that water to keep equipment and floors clean is the foundation for good housekeeping. Stone dust must be controlled, and good housekeeping is critical to this process – air filters and water curtains will not cover the entire area of a shop. One of our Customers has a sign in their shop – “if its white it ain’t right”, encouraging their team to focus on getting all the solids into the trenches and into the pit – to keep the stone dust from drying on the floor and equipment and becoming air borne the following day.
More and more shops are replacing gravity settling systems for a variety of reasons – some consistently failed to help them meet crystalline silica levels, some do not keep up with water demands and water pressures. Our filter press based recycled crystal clear water systems help our customer base of all size operations – to achieve crystalline silica levels well below OSHA standards.
WTS has been in the water filtration and recycling business for over 20 years and were the first to introduce a filter press based system designed exclusively for the Stone Industry. They are also the first and only system to produce chemical free crystal clear recycled water that meets the requirements of all equipment manufacturers.
