Wastewater: Coming Clean Again

April 5, 2005

However, that’s only part of the day’s output. Unless everything is being fabricated dry, there’s a supply of dirty water that’s going … somewhere.

While there are various options for dealing with that water – dumping it on a field, or utilizing a bag-filter system to remove the worst of the particulates, for two – each of those options also has drawbacks. It’s why filter-press technology is gaining a foothold in the industry, especially with larger shops.

Although the initial investment might seem high, the right-sized system can effectively remove particulates as small as 2 microns, producing clear water that can be recycled almost indefinitely – and a clay-like cake of residue that can safely go out with the trash.

CRYSTAL CLEAR

With higher water or wastewater treatment costs and the shadow of more government regulation looming, the idea of reusing water isn’t a new one to the industry. And, for shops not happy with their lower-cost, passive bag-filter systems, the idea of being able to recycle water indefinitely is sure to look more-attractive to more owners as time goes on.

Is it really possible to get water clean enough for hand polishing, or to send through the spindle of a CNC again and again and again? Ask manufacturers of some of the filter-press systems – such as Water Treatment Technologies, Beckart Environmental Inc., ECS EICH, Fraccaroli e Balzan S.p.A. and Filtering Systems – and they’ll say they can do the job.

“Our system filters particulates to less than 2 microns,” says Paula Perry of North Hampton, N.H.-based Water Treatment Technologies. “When wastewater goes through our system, it comes out reusable for stone-fabrication applications and other applications as well.”

However, there are some cautions on the “indefinite,” part of its use. Dan Fedrigon of Kenosha, Wis.-based Beckart, says because of variables in the water initially going into the system, over time there might be some concentration of dissolved salts or – with extreme heat – growth of bacteria.

“That’s why we hit our water with UV (ultraviolet light) to disinfect it,” he says. “There’s nothing in the water itself that’s hazardous; we’re just taking the particulates out.”

Peter Edwards, whose Atlanta-based Euro Stone Machine is the United States agent for the German ECS EICH water-treatment systems, says that company recommends – depending on volume – that the system be emptied, cleaned, and refilled every six months to a year.

Still, that’s a pretty minimal expense for water, given that it’s not unusual for some shops to use 100 gallons a minute or more. However, Edwards says companies contacting him about systems only rarely mention the cost of water.

“Typically, it’s because the government is on their backs,” he says. “It’s to meet regulations either for the local wastewater district they’re in, or for the state.”

Fedrigon says the other major reason shop owners call his company is they’re moving into a new facility and have limited water or wastewater options.

“We’ve had people put systems in because they don’t have a sewer system or they don’t have a very good freshwater supply, such as a well with a limited amount of water,” he says. “If you hook up to the city sewer, you have to deal with permitting issues and city inspectors, but if you’re not using their (sewer) system you don’t have the monitoring and regulation.”

Shop owners who have the systems give a mix of reasons for putting them in. Roland Pfender of Minneapolis-based Pollux Manufacturing says his company came online with an ECS EICH system because of local regulation and the cost of water.

“We didn’t want to become a wastewater-discharge generator and have the permit and the fees and everything else that goes along with that,” he says. “The city of Minneapolis is pretty stringent. And, it really is a money-saver for us to recycle the water, since we use 20,000-25,000 gallons of water per eight-hour shift.”

However, Ron Mercer of Hytec Tops in Columbus, Ohio, says his decision to buy a Beckart system was strictly based on economics.

“I tried several other systems, and we were processing so much water with our CNCs and saws and a line polisher that we had to do something,” Mercer says. “You can’t afford to use 120 gallons of water a minute and not recycle.”

STUDIED APPROACH

Shopping for a filter-press system doesn’t necessarily have to be a difficult process, as long as a buyer recognizes it’s just like buying any other piece of shop equipment and is willing to do due diligence.

Many would-be buyers start by contacting the manufacturers of their shop equipment, who are often willing to make recommendations. Mercer, however, says he turned to the Internet after having poor results with a bag-filter system.

“I knew I wanted to use a filter press because it’s more of a mechanical solution,” he says. “I started looking up press manufacturers and found Beckart.”

However, simply finding a system manufacturer isn’t enough, says Michael Burress of Dallas-based Stoneworkz. Because he knew what he didn’t want, he says it was important for him to see similar systems in use in other shops when his company built a new facility in Orlando, Fla.

“It’s absolutely critical that you understand what you’re buying,” he says. “Understand what it will do and if it meets your expectations, so you’re prepared for it. Just as you’d do when you’re buying a saw or a CNC, go see it in action.”

Once you decide on which system to purchase, the actual process of getting one sized, designed and installed isn’t particularly onerous.

“We design a system for each shop, although there are some basic components that are the same,” says Water Treatment Technologies’ Perry. “What we really need to take into consideration is the water demands of the equipment the customer has.

“We also have to know the volume of solids in the shop. We have to know what they’re producing and what we have to filter out.”

Certainly one factor is how much natural quartz a shop is producing. While everyone agrees these systems handle natural stone and natural quartz equally well, the setups aren’t exactly the same, according to Euro Stone Machine’s Edwards.

“With engineered stone we like to increase the capacity a little bit,” he says. “The resins remain in suspension more than dust, so we prefer to have a larger clarification area.”

Still another important consideration is how much growth a shop anticipates. Beckart’s Fedrigon says the goal in designing a system is not to put the shop in a position where it’s pushing the edge of its capabilities anytime soon.

“We try to err on over-sizing to begin with so you’re not having to shut down production,” he says. “We do more than take care of today’s needs.

“Depending on what you have, we can double the design capacity by expansion. If you really need more water, then without expandability you might end up having to trade in a component to get a larger one.”

Still another factor in sizing can be the maintenance of the machine. Eric Hakanson of Garden Grove, Calif.-based Signature Stoneworks says an important concern for him in his initial conversations with Perry was that he didn’t want to have to clean the machine very frequently.

“I wanted to clean it once a week and she sized the system for my needs,” he says.

While Edwards estimates it should take six to eight weeks to get a system designed, installed, and running (especially when retrofitting an existing shop) there may be some piping challenges.

“Most shops have a methodology where they’re collecting their wastewater, and we need to be near that hole in the ground where it’s collecting,” says Perry. “Otherwise, we don’t need expensive real estate; we can be back in a corner. I’ve yet to see a shop where we couldn’t configure a system for it, but it might require some changes on the customer’s part.”

For best results, it may also require some additional engineering ,says Stoneworkz’s Burress.

“Our system is designed to run a half-million gallons of water a day with two shifts,” he says. “However, we had a local engineering firm do all the piping requirements for the flow rates to all the machines. Not only is the system properly sized, but all the piping requirements to the machinery are sized, and that’s critical. If you put in a 1” pipe but you need a 2” one to keep up the velocity, it can have a huge impact.”

SMOOTH RUNNING

Probably the most attractive aspects of filter-press technology are that it’s easy to maintain the systems – and get rid of the waste.

All the manufacturers say maintenance is primarily a matter of training existing shop personnel, and then having someone keep an eye on the system to make sure it’s running smoothly, although it will require more maintenance than a passive bag-filter system.

“We do start-up training and then some follow-up, but there really isn’t a lot that’s needed,” says Fedrigon. “It’s basically pumps, and unless you have a pump failure, it’s pretty simple.

“We’re probably not talking a half-hour a day on a typical day. It’s more that someone has to walk by once in awhile and make sure there aren’t problems that could cause a flow drop.”

Most shop owners admit to keeping a spare pump or pump components on hand to avoid significant downtime. The systems also typically have some sort of alarm to notify someone in the shop when a problem does develop.

“Part of what we do is train people to watch the reserve tank,” says Water Treatment’s Perry. “If it’s not filling up again, it’s likely something isn’t being done correctly. It’s either a service issue or an education issue.”

Most shop owners who use the systems agree they’re not very difficult to maintain. For instance, Signature Stoneworks’ Hakanson says initially his shop had some problems with the wetness of the brick-like clay residue that’s filtered out of the water, until he realized they weren’t cleaning the screens well enough.

“We weren’t able to get full capacity from our system because we weren’t cleaning the screens properly,” he says. “The clay end-product was too moist because we were using a cheap pressure washer. After we realized that and got a better pressure washer, everything has been okay.”

Hakanson adds that cleaning the filter press is really a one-person job, and with some training and a good step-by-step manual, it’s a task that can even be handled by any employee.

Pollux’s Pfender says he has about four people trained to understand how the system works and maintain it. Other than some greasing of bearings occasionally and spraying down the filter press plates with a hose after a couple automatic cycles, it doesn’t require much.

“We spray it down with a hose in what’s about a five-minute process, and then it goes back into automatic mode” Pfender says. “When the mud and water in the sludge tank reaches a certain level, it hits a sensor and kicks in the pump and that pumps the mud into the filter press and runs a cycle. We fill a two-and-a-half yard dumpster with the mud twice a week.”

Euro Stone Machines’ Edwards notes that end product – which indeed can go out in the dumpster – puts both bag-filter and filter-press systems ahead of systems utilizing chemical flocculants to help remove particulates from the water, because the chemicals are potentially harmful to employees and the end product can’t be disposed of in the local landfill.

However, Stoneworkz’s Burress says he’s a little disappointed by the amount of training and monitoring his system requires to keep it running optimally. One problem he cites with his operation that not everyone grapples with is salinity.

“It monitors the salinity of the water, and automatically drains and injects fresh water in to keep it at a constant level,” he says. “Still, someone has to monitor that and the consistency of the sludge in the filter press. We thought we were designing a stand-alone system, but we found that it still needs a lot of attention.”

Despite the bumps in the road, the users of these systems believe they’re worth it. Still, they advise care in shopping. Pfender, for instance, reiterates Burress’ advice to see systems in action before deciding what to buy.

Hakanson urges would-be buyers to contemplate the true labor costs of a filter-press system compared with other options, as well as overall operating costs.

“I think by the time you do the math you’ll see you’ve saved yourself a lot of money and you’re doing a service to your community,” he says. “Dumping into the system and the damage that causes could come back to haunt you. I don’t think people realize the complications of what they could be facing in the future.”

Hytec’s Mercer has tried to do just that. He says he’s cut his monthly water bill by about 75 percent, even though he had to dig a new pit to adequately handle the volume of water he’s using. As with Hakanson, he advises planning for the future.

“The key is not to skimp on the front end,” he says. “These systems aren’t cheap, but when you look at the long end, you may have to spend extra not to not worry about it later.”