The threat to the waters of Tampa Bay was serious.
Heavy rainfall from a series of tropical storms threatened to send millions of gallons of acidic wastewater from a closed fertilizer plant into the bay. State officials, who had taken over the Piney Point Fertilizer Plant after it closed following a 2001 bankruptcy, needed a solution, and fast.
So in 2002 the state called on USFilter and its fleet of mobile clarifiers to clean the dirty water before it could overflow into Tampa Bay.
“They were the answer to our prayers,” said Louis Timchak, court-appointed receiver for Piney Point Phosphates Inc. “They had to apply a whole lot of ingenuity to this. This was a big project. Everyone in the environmental arena was watching this. And everyone was impressed with how it went.”
USFilter relied on an integrated approach to treat the water, one that included filtration, two-stage reverse osmosis and demineralization. But the company’s mobile clarifiers—which act like typical onsite clarifiers but are far smaller and are sent across the country in trailers—provided the key step. Before USFilter could treat the billions of gallons of water at Piney Point with these other processes, its engineers first had to devise a plan to remove the unacceptable levels of algae and sediment from it.
That’s where the company’s mobile clarification trailers came in. USFilter’s mobile clarifiers—the company has 12 clarifiers in its fleet, all mounted on trailers so that they can be towed to hotspots across the country—are able to treat high-turbidity waters with greater than 1,000 NTU and produce clear effluent. The systems are also able to treat raw water that has extremely low turbidity, high color and high total organic carbon or algae levels.
USFilter treated the brackish pond water at Piney Point with two of these mobile clarifiers. For three years, from 2002 to 2005, the clarifiers stripped the algae, dirt and other sedimentation out, allowing engineers to continue with further treatment. Eventually, the state was able to discharge all the Piney Point water into Tampa Bay without any harm.
“This was something that had never been tried before,” Timchak said. “They deserve credit for sticking to this. It was a difficult situation. USFilter applied whatever resources they had at hand to figure out how to get the water pre-treated and treated, through reverse osmosis and ion exchange, and discharged. It was an incredible undertaking.”
While it may be a unique one, the Piney Point project is really just one example of the growing importance, and versatility, of mobile clarification, a field currently dominated by USFilter.
Clarification in general has garnered headlines following hurricanes Katrina and Rita, two storms that ravaged the Gulf Coast and left untold citizens and businesses without clean drinking water. Mobile clarification would seem to be an ideal solution to such disasters: Clarifiers mounted on trucks can motor to communities hit by natural disasters and turn dirty, untreated water into clean, safe drinking water.
But as the Piney Point example illustrates, mobile clarification isn’t useful only following natural disasters. These clarifiers on wheels have been used at plants and factories when these facilities’ own clarifiers have shut down for planned repairs or because of unplanned failures. They’ve also provided potable water for small nonmunicipal facilities such as resorts, developments and correctional institutions. Clients use mobile clarifiers to treat influent water, eliminate sediment and chemicals from settled wastewater, and to clean dirty water in ponds and reservoirs.
USFilter has even sent one of its mobile clarifiers to a theme park to clean the water in one of its thrill rides.
This versatility has industry experts predicting that the mobile-clarification industry, which is still in its infancy, will only grow in the coming years.
“We are continuing to build two or three trailers a year, and we usually have 70%–80% percent of our trailers out at any one time,” said Chuck McCloskey, market development manager for mobile and onsite services at USFilter. “The demand is there. We’re also looking at more ways to use our mobile clarifiers. We’ve just started doing some work with clarifying secondary effluent, and we think that market is just going to grow for us, too. There are so many uses for these trailers, I can’t predict anything but growth for this sector of our business.”
USFilter has been offering mobile clarifiers for about three years now. And McCloskey doesn’t hesitate when asked to list some of the varied ways in which USFilter’s mobile clarifiers have been used.
From Wineries To Oil Tanks
Back in 2005, for instance, the company sent one of its mobile clarifiers to Wilmington, NC. Construction crews there were in the middle of building a pharmaceutical plant on the shores of a river, on the site of an old fertilizer plant. When crews began digging into the earth to place the new building’s footings and pilings, ground water surged onto the site.
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| All USFilter mobile clarification trailers feature the patented Actiflo technology. |
Normally, this would not have been too major of a problem. In this case, though, the water had a high ammonia content, and a turbidity level between 600 and 800 parts per million, a remnant from the site’s former use as a fertilizer plant. This caused serious problems: Crews could only discharge the water into the local treatment plant if it contained less than 20 parts per million of ammonia.
Construction threatened to come to a halt. That’s when officials called in USFilter’s mobile clarification unit.
Engineers sent the ammonia-laced water through one of USFilter’s mobile units, removing solids, silt, and mud from it so that further treatment with reverse osmosis was possible at a fraction of the hauling cost. Soon the water was clean and cleared for discharge, and construction continued on schedule with no fines levied.
Mobile clarification proved invaluable, too, to the developers of the Diablo Grande Winery and Resort.
In February 2003, the developers called on USFilter to provide a temporary potable water treatment system while work continued on the resort’s own $5-million drinking-water plant. Resort developers estimated that it would take 12–16 months to complete this plant.
Temporary drinking water was important to the developers. It allowed them to continue to sell residential lots while construction crews built the permanent system. It also allowed them to stay on schedule for their other key resort projects, including a hotel, winery and golf courses.
USFilter recommended a mobile treatment system, first using clarification of water provided by the California Aqueduct and then filtration, polishing, chlorination, storage, and distribution. These plans met the California Department of Health Services Standards for NTU, TDS, and chlorination of potable water, all of which allowed resort officials to keep to the construction schedule.
Currently, a mobile clarifier is on the job in the Queens section of New York City, where construction crews are hydro-blasting two large bunker oil tanks that have been taken out of service. The water used to clean the tanks has been collected in a large pit. The goal is to take this water, filled with dirt, oil, and grease, to a local sewer.
This, too, became an ideal situation for mobile clarification. Crews are now running this dirty water through a mobile clarifier and activated carbon vessels to eliminate the last traces of contaminants. Once the water is cleaned, crews are then discharging it into the sewer.
A Growing Market
These examples prove that mobile clarifiers have a variety of uses. Most frequently, though, clients call for one of USFilter’s trailers when they need to clarify raw water going into a plant or facility or surface water before it moves downstream for further treatment. Clients also call on USFilter’s mobile clarifiers when they have a planned or unplanned outage of their own onsite clarifiers. In such situations, the facility’s water still needs clarifying, even when the onsite equipment needs to be replaced or repaired, and it’s a simple matter to have USFilter ship one of its trailers to the site.
This ability—to make a phone call and have a temporary clarifier up and running in days—is a relatively new one for plant operators, private developers, and municipal officials. Before the advent of these mobile treatment centers, these folks would have faced two grim options, McCloskey said.
If the water was extremely dirty and filled with high levels of sediment, operators would have little choice but to shut down the facility until technicians repaired the onsite clarifiers. If the water wasn’t bad enough for a shutdown, facilities could limp along instead, muddying up their filters in the process, McCloskey said. This, of course, would lead to more frequent cleanings and backwashing, and a corresponding dip in production and increase in costs.
Before it began offering mobile clarification, USFilter had already featured the technology to make it work. The company had offered it in larger, permanent clarifiers.
All USFilter mobile clarification trailers feature the patented Actiflo technology. Developed by Denmark-based Kruger Inc., the Actiflo process uses microsand as a seed to enhance floc formation and increase the settling rate of untreated water. This process is ideally suited to treat water that has high or low turbidity, is high in color, is particularly cold or has significant levels of algae.
USFilter’s municipal and industrial customers soon requested smaller clarifiers, a request that eventually led the company toward mobile services.
“Our customers didn’t want something that would take up so much land,” McCloskey said. “They didn’t want a big, sprawling clarifier. They’d always ask why someone couldn’t design something that could process a lot of water in a small area. They wanted something with less concrete, something that took up less space, that could clarify water in a small footprint.”
USFilter listened, and developed smaller clarifiers. These weren’t mobile, but they were closer to that ideal. And once company officials saw that they could build smaller clarifiers, the idea for mobile clarification gained traction.
“We saw the opportunity,” McCloskey said. “We already had been providing reverse osmosis and demineralization on a mobile basis. Once the technology was compacted, miniaturized into something that fit into a trailer, it was a natural opportunity to add it to our fleets.”
McCloskey says he expects the mobile clarification business to increase as more facility managers learn of the technology. USFilter is also adding new mobile-clarification services, having just begun work on clarifying secondary effluent wastewater.
In this process, water usually travels first through a clarifier at the back of a facility following biological treatment processes that cleans it at the discharge point. Facilities face the same issues with secondary effluent as they do with any other form of clarification. These clarifiers break down, too, or need to be shut down for repairs. If that happens, plants discharging secondary effluent without first treating it will be in violation of NPDES regulations or will be discharging high suspended solids to the local POTW, a wastewater treatment facility owned by a state or municipality. Mobile-clarification trailers will provide these facility managers a solution, McCloskey said.
Treating The Treatment Plant
Larry Rogaki doesn’t need convincing. He’s seen firsthand how effective mobile clarification can be.
In 2004, a mobile clarifier from USFilter helped Rogaki, process engineering manager with Rosemount, MN-based Metropolitan Council Environmental Services, battle Minnesota’s legendary cold to keep the city’s wastewater treatment facility in the good graces of national regulators.
“We were fortunate,” Rogaki said. “Our only other option was to risk our permit for three months until we could build something to provide improved particulate removal. To get something installed as quickly as we did with the mobile clarifier was a big help to us.”
USFilter worked with the city of Rosemount for three years to remove high levels of phosphorus from the effluent discharge of the city’s wastewater treatment facility. The facility’s permit only allowed it to discharge wastewater with a maximum average monthly total phosphorus level of 1 part per million. The facility was able to meet this level until winter. Once temperatures dropped below 3°C, though, fine particulate solids formed in the waters. Crews installed new disc filters to remove the treatment facility’s total suspended solids, but the filters did nothing to reduce the phosphorus level.
The city sent a water sample to USFilter for testing. Company engineers determined that the unusually cold temperatures were preventing the disc filters from effectively removing the suspended solids in the waste effluent, something that explained the high levels of phosphorus.
“We thought we were going to be faced with a situation where we weren’t going to be able to do anything about the problem until the temperatures rose,” Rogaki said. “And that wasn’t going to happen for three more months. We faced a serious risk during that time of losing our permit.”
USFilter solved the problem by transporting a high-rate mobile clarification unit to the facility. This unit removed the suspended solids in the wastewater plant’s pond system, quickly reducing the phosphate levels in the facility’s discharge waters. Four days after the system began treating site water, the total phosphorus level of the treated effluent came in at 0.75 parts per million, below the permitted 1 parts per million maximum.
USFilter’s mobile unit stayed onsite for three months, treating an estimated 900,000 gallons of water a day. During that time, the Metropolitan Council Environmental Services improved its clarification system so that it could effectively treat water with smaller particulate solids. Rogaki is confident that the facility will not need to call in USFilter during any future cold snaps.
The Minnesota weather actually caused challenges for both the city and USFilter. Previously, company officials had never set up one of their mobile clarifiers when the temperature had dipped below zero.
“Once we got the machine up and running, it worked with no problems at all,” Rogaki said. “Getting it set up, though, was a bit of a task. It was windy and cold. We had to do a lot of emergency plumbing and power supply. There were some initial startup complexities, but once we got it started and running, it ran very well.”
USFilter’s engineers surrounded the clarifier with hay bales to help protect it from the frigid air. The tops of the mobile clarifiers’ trailers are usually open, but in this case, USFilter installed a temporary cover to provide additional protection. The company also placed extra heaters inside the trailer to keep the equipment at a comfortable temperature.
“They invested a bunch of time,” Rogaki said. “They worked really well to make sure the clarifier functioned the way it was supposed to.”
Timchak, from the Piney Point project in Tampa Bay, likewise needs little convincing that mobile clarification is on the verge of becoming an even bigger business. The technology, after all, provided a solution to a particularly vexing problem at the fertilizer plant.
USFilter’s mobile clarification unit, powered by its Actiflo technology, eliminated enough algae and dead algae to bring the discharge water’s turbidity down to less than 1 part per million.
“This was a unique site and a unique situation,” Timchak said. “We were in a hurry. The hurricane season was coming, and we had a lot of water to deal with. This seemed like one of the best methods of treating this water. It had the promise of bringing it to standards where we could discharge it. We tried other ways to get rid of the algae and dead algae, and this was the only technology we found that could do the job.”
More statements like that, and it seems only a matter of time before mobile clarification becomes a booming business.
DAN RAFTER is a technical writer based in Chesterton, IN.
OW - July/August 2006 |
