From the June 2018 issue
Helping Nature Clean Up
Filtration success stories
Some of the best innovations can be sparked by an event that underscores an unmet need, and the outcome is often new technology based on a simple idea.
The Exxon Valdez oil spill of 1989 so shocked Glenn Rink, then of HydroGrowth International, that he was driven to action to find a solution for removing oil from water, which in theory sounds like a simple idea. The disaster “started the wheels turning” and subsequently led Rink to solving the problem and founding AbTech Industries, as Todd Megronigle of the Scottsdale, AZ-based company explains.
“When the tanker Valdez struck a reef in 1989 during its voyage from Alaska to California, it dumped more than ten million gallons of crude oil in the Alaskan Prince William Sound. At that point, Rink, who has a background in polymer technologies, was prompted to start looking into solutions that could remove oil from water and leave the water clean,” says Megronigle. “Then during the 1994 oil spill in Puerto Rico, he witnessed firsthand the antiquated methods of removing oil from open water and became determined to find a better way to clean up the spills.”
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After much experimentation and testing, “he came up with a polymer formula that had hydrophobic and oleophilic qualities,” says Megronigle. In other words, he developed a polymer-based product that repelled water but attracted oils and grease.
From this one idea, the company has continued to evolve, and over the last 17 years has developed several sponge-type media for removing contaminants from water.
“We consider these ‘smart products’ that can identify the differences between oil and water, and we named the first one ‘Smart Sponge,’” he says. “Today, we have more than 20,000 installations in 46 states and 15 countries.” The product line includes Smart Sponge, Smart Sponge Plus, Smart Sponge HM, and Ironwood technologies that can be used across the industrial, wastewater, and oil and gas arenas.
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“This is a proprietary polymer material that is light and airy—it looks a bit like popcorn—and its microporosity allows the Smart Sponge to filter high volumes of water and still retain effectiveness,” explains Megronigle. “We demonstrate how well it works by showing customers a container that is half oil, half water. We dip a Smart Sponge in the liquid, and when it is removed, the oil is attached throughout the sponge and the water is perfectly clear.”
He says that the removed hydrocarbons are actually transformed into a stable solid. The product has passed EPA’s Toxicity Characteristic Leaching Procedure (TCLP). In this test, the solid mass of extracted hydrocarbon material is placed in a vise that exerts high pressure.
“The characteristics of the Smart Sponge actually change the molecular form of the hydrocarbons so they are transformed from liquid to stable solid. The agency tests its absorbency effectiveness by putting this solid mass of hydrocarbon material under pressure for one hour to see if any of the contaminants come out of the saturated Smart Sponge. As no contaminants were found to leach out of the solid, it passed the TCLP.”
He adds that once converted to a solid, the untreated hydrocarbon mass can be sent to waste-to-energy source facilities “as it provides a high value BTU and can be repurposed as an adjunct heat source.” The TCLP rating makes the hydrocarbon easier to dispose of in non-hazardous landfills.
The Smart Sponge product line has utility in several applications for stormwater filtration, including placement in vaults for end-of-pipe filtration, in passive skimmers that float directly on water in retention ponds, and in hydrodynamic separators. The line skimmer/boom series has a cylindrical configuration filled with Smart Sponge, and the unit can create a line of protection in ponds, streams, and clarifying wells.
AbTech’s Ultra-Urban Filter with Smart Sponge helps control nonpoint-source pollution, and one place it’s being deployed is in the Chesapeake Bay watershed. For decades, the nation’s largest estuary has been fighting an intense battle to reduce nutrients, sediment, and contaminants, and the efforts have paid off. According to scientists at the University of Maryland Center for Environmental Sciences, the bay received its highest annual report card grade for improvements since 2006. Now, the Tred Avon River, a tributary of the Choptank River that feeds into the bay off the eastern shore of Maryland, is part of that success story. With a 2008 state initiative, the Tred Avon experienced a renewal as a source for oysters but is nonetheless listed as impaired by the Maryland Department of the Environment, says Midshore Riverkeeper Conservancy spokesperson Tim Junkin.
“Stormwater that drains from the nearby town of Easton, MD, flows directly to the Tred Avon,” says Junkin. With financial assistance from private grant sources and oversight management by the Riverkeeper Conservancy, Smart Sponge-containing filters from AbTech were installed throughout Easton’s stormwater drains.
“We installed hundreds of Ultra-Urban Filters in Easton that will prevent contaminants including TSS [total suspended solids], oil, phosphorus, and metals from entering the Chesapeake Bay,” says Megronigle. “The Smart Sponge inside the filtering system permits a 190-gallons-per-minute hydraulic flow rate in each of the 255 filters installed and is rated to remove more than 80% of these contaminants.
“For high-flow events such as a thunderstorm, the Ultra-Urban Filters are designed with built in bypass to prevent the stormwater from backing up. These installed filters have the capacity to treat almost 50,000 gallons per minute of stormwater before it flows into the Chesapeake Bay, with the ability to remove 2,500 pounds of oil and 15,000 pounds of TSS over the lifespan of the filters,” he reports.
The filters will continue to absorb the contaminants for years, and Megronigle says that Easton’s Public Works staff will change the media out on a location-dependent schedule: “A third of them each year, others at a rate of one to three years, and others three to five years. It all depends on their location and the level of contaminants at each catch basin.”
AbTech has also developed a Smart Sponge Plus that is EPA approved for the reduction of fecal coliform bacteria. Smart Sponge Plus is often deployed around recreational waters and has the ability to help keep beaches open that might otherwise close due to high levels of bacteria. The newest version is Smart Sponge HM, which is blended with nanoparticles to effectively remove heavy metals and phosphorus from stormwater.
“We just installed our first large-scale application with Smart Sponge HM to remove phosphorus at a Los Angeles County Lake in California to prevent algae blooms,” he says. He notes that, like other Smart Sponge products, “it can be retrofitted into existing infrastructure, but it has no moving parts, doesn’t require electricity, and does a terrific job in inexpensively and effectively removing contaminants from entering our waterways.”
Credit: AbTech Industries
Putting Gravity to Work
The Cleveland area of northeast Ohio, like many cities that line the Great Lakes basin, experienced an enviable prosperity in the first half of the 20th century. But with changing times and new environmental regulations, the region’s steel mills, auto manufacturing plants, and industrial facilities declined dramatically.
One company, however, turned the need to manage industrial wastewater into an opportunity. According to spokesperson Jim Petrucci, a four-decade veteran of Cleveland-based Oil Skimmers Inc., “We have been removing oil from water for almost 50 years, in almost any manufacturing or industrial environment you can imagine.
“Just this week for example, we sold one of our oil skimming systems to a company in New England that makes artificial knee joints and one to a company in Paraguay that manufactures products from processed soybeans. Both have water in their process that, at some point, combines with oil. The oil needs to be removed, which is what we do.”
Petrucci explains that oil adheres to a patented free-floating collector tube. “This is a specially formulated plastic tube that is joined into a continuous loop and floats on the water surface. The tube is driven by a unit called an oil skimmer, and the principle is very simple. The oil-covered tube passes through scrapers that remove the oil. Then, by virtue of gravity, the recovered oil flows into a collection tank.”
The skimmer can be used in any scenario where water is in contact with oil. Petrucci cites manufacturing plants, power plants, the military, and steel mills as some of the primary users, “as they are bound by local regulations to remove oils from any water destined for stormwater treatment facilities.”
He adds, “These include process applications; a customer has a coolant process, or is washing, quenching, or machining—all of these use water or water-based liquid that comes into contact with oil.”
However, continuous reuse of water that has been in contact with oil or with other debris such as metals or glass particles “vastly reduces the efficiency of the process, so cleaning it continuously is cost-effective,” Petrucci says.
The skimmer comes in several models, depending on the application it is intended for. Factors that determine which unit to use are the location and size of the application, the amount of oil to be removed, and the scope of the project. Units range in size from those that can be carried in one hand to systems that require a forklift truck for transport.
“We can provide standard, off-the-shelf skimming systems, but we also have a full-time engineering staff to design custom solutions that addresses the customers’ specific challenges,” he says. “The skimmers have a long service life. We have units that have been out in the field that after 40 years are still going strong, and in many applications they are left to run continuously,” he says.
Treating wastewater, he says, can be done onsite or the water can be sent to a municipal treatment plant. In either case, “nobody wants oil in that water, as it drives up water treatment costs and coats probes and sensors. Anyone running a treatment plant will demand that the oil be removed first,” he says. “We like to promote the practice of skimming first and skimming early, as near as possible to the point where water comes into contact with oil.”
He adds that skimming also makes economic sense when the skimmed oils can be reused or sold. “We know of one company that buys skimmed oil from potato chip factories in the UK and uses it to manufacture biodiesel. Customers can also skim valuable hydraulic oils that get into cooling waters, decant it, and have it refined for reuse.”
Technology Engineered for Beauty, Efficiency
Residential developers are keenly aware that first impressions are everything to prospective buyers. When the price tag of properties starts at a million dollars, they take extra effort to showcase luxury features, but sometimes unsightly utility services make this difficult.
“Residents in a high-end neighborhood desire amenities like pools, tennis courts, and park areas as opposed to large traditional bioretention systems,” says biofiltration product manager Alex Macleod of Cincinnati, OH’s Contech Engineered Solutions. “These systems take up a lot of space and are cumbersome to maintain. When not designed or installed properly and then neglected, these systems can lead to a potential eyesore that hurts property values.”
So developers look for alternatives. He cites San Diego’s Robertson Ranch, built by a renowned national luxury home developer, as a case where the solution to stormwater management required an attractive and efficient system.
“With homes in this price range, the developers demanded a high-quality stormwater management system that would filter and clean runoff prior to entering the stormwater system. But they also needed to do so in a manner that was compact, integrated into the site landscaping, and allowed for additional neighborhood amenities.”
The solution included using Contech’s Filterra Bioretention System with its engineered, high-flow bioretention media. “Typically in traditional bioretention systems, media flow rates range from 5 to 20 inches per hour,” says Macleod. “This dictates a system size ranging from 5 to 15% of the contributing drainage area. Additionally, there is little quality control. Contractors typically purchase bioretention media from a quarry or landscape supplier or they may blend it on site. But not everyone is familiar with the media recipe and stormwater treatment goals, so uniformity and consistency can vary with respect to amounts of aggregate, organic material, or additives—all of which affect its treatment flow rate and pollutant removal capacity. Filterra media has been specially engineered to flow at 140 inches per hour, allowing a greatly reduced footprint, typically less than 1% of the drainage area. We follow a rigorous qualification and testing procedure before, during, and quarterly after each batch is blended.”
Macleod says the company blends the media using precise equipment and sources the materials from suppliers whose constituents are qualified prior to each batch blend.
“We blend a year’s supply at a time, and we calibrate and test throughout the blending and over the year to ensure consistency in the product’s flow rate and pollutant-capture capacity.”
For the Robertson Ranch project, precast concrete Filterra Bioscape vaults were set in place with media installed and protected until the contractor had finished the grading and was ready for activation.
“On this site, where very large recessed bioretention systems would have been excavated, we installed a series of precast systems. Due to their efficiency, these allowed more of the property to be used for public space. This conserved area allowed for the building of a playground with equipment, sidewalks, trees, and benches. The bioretention vaults sit at grade, so they are integrated into the landscape like 8-foot by 16-foot planter boxes. Each system utilizes an underdrain, which ties it to the stormwater system.”
Once a site is stable and the sidewalks, sod, and landscaping are in place, Contech activates the Filterra systems and puts them into operation. “The contractor submits an activation checklist to ensure the site is ready, and at that point we deploy a crew to install the mulch and the landscape plants for the vaults, making the system functional,” explains Macleod.
The company typically works with the contractor and engineer to select bioretention landscape plants from those suitable for the climatic region. “The Filterra system has been available since 2003, and in that time we have developed localized lists of plants that we know are available and that will work well in the system. Many times, the plants are similar to those found on local bioretention planting lists.”
But even with the smaller footprint of the Filterra system compared to traditional bioretention, performance is not sacrificed. Filterra systems have been approved and tested to meet industry pollutant removal goals at flows up to 140 inches per hour, he reports.
“The Filterra system has received General Use Level Designation [GULD] by the Washington State Department of Ecology TAPE [Technology Assessment Protocol – Ecology], and has also received certification by New Jersey Department of Environmental Protection, two nationally recognized stormwater programs. We have numerous other field tests as well, following industry-recognized TAPE and TARP [Technology Acceptance Reciprocity Partnership] protocols.”
Once a good root system is established in the 21-inch-deep media, the plants function to uptake some of the captured contaminants. This process helps to rejuvenate the media and minimize the need for maintenance. “The only intervention needed with the Filterra system is removal and replacement of the 3-inch top mulch layer along with contained trash and debris every six to 12 months. Contech includes the first year of maintenance with every Filterra purchase,” he says.
Credit: Bio Clean
Retrofitting in Small Spaces
Montgomery County, MD, has its southern boundary defined by the Potomac River and is home to the historic Chesapeake and Ohio Canal; this gives the 507-square-mile region a direct connection to the Chesapeake Bay. With more than a million residents, this Washington DC suburb is one of country’s top-10 wealthiest communities, packed with luxury residences, corporate offices, and retail shopping.
“Our firm has an ongoing contract with the county to maintain the below-ground stormwater facilities,” says Solomon Zacchini, stormwater manager for Magnolia Plumbing. “Our job is to go in and clean them out and make sure everything is working properly. We have a schedule the county works out for each region, so we work against that and we know what we’ll be doing months from now so we can plan our work.”
Recently he and his crew were on a routine inspection of the facilities that collect stormwater for the Germantown Square Shopping Center, “a very busy, high-traffic—in both cars and people—shopping area. There are a lot of pedestrians and a lot of debris and trash that accumulates,” he says. “We discovered that the old corrugated steel pipe connection had literally fallen in on itself.”
After they cleaned the area up, they inspected the entire system and wrote a report itemizing needed repairs. “But after learning the county didn’t want to go back and use corrugated steel again, we had to come up with something different. They had considered a hardened plastic, but this still breaks over time and the bolts can rust as well, which hastens deterioration,” he says.
“I had actually read in Stormwater magazine about the SNOUT manufactured by Best Management Products [BMP] and was impressed with its capabilities. I talked to the county about using this to retrofit their stormwater system and told them the SNOUT was fiberglass and had a 25-year life. Then in a discussion with the BMP company, we talked about which SNOUT would work for the design that I was envisioning, and they ended up making something for me that was perfect.”
One of the challenges, says Zacchini, was that access was through a manhole just wide enough for a person to get through, but the standard SNOUT was 36 inches wide. “So what they did was make a unit that was fashioned in sections so that we could get it through the access and then, like an Erector Set, put it together once we were underground.”
“Because of our manufacturing flexibility, we were able to provide Montgomery County with a custom solution that used sections from various split SNOUT models that were assembled and modified by Magnolia Plumbing on site,” says T. J. Mullen, Best Management Products president. “We make split parts for just this type of situation. Since split SNOUTs come in multiple sections, which then are assembled in the structure, they are designed specifically for projects such as the one Magnolia Plumbing was about to undertake.”
He adds, “Retrofitting something in an existing underground structure frequently has only a limited access through a manhole or a grate. Having to tear up a parking lot or roadway to gain access for retrofitting parts is disruptive and expensive. But by avoiding that inconvenience, the contractor and facility owner is saving thousands of dollars in lost business and the municipality is reducing the burden and cost of a traffic tie-up or detours.”
Given this scenario that contractors often face, the split SNOUTs are becoming a very popular part of BMP’s product line, Mullen adds.
Zacchini says the crew had to replace the 90-degree elbow using a 72-inch-long SNOUT, and they also replaced a trash rack by using the SNOUT for something it wasn’t originally designed to do.
“Replacing the 90-degree elbow was simple and straightforward thanks to the design team at BMP. They made installation easy and seamless by providing us with the proper directions. When we were replacing the trash rack, however, we had to take two 72-inch-long SNOUTS and then retrofit them for our needs by turning them sideways and drilling the necessary 1-inch holes in the fiberglass for water to pass through.
“Then all we had to do was piece them together in the unit and anchor the ‘new’ system to the wall. Both the county and my team were extremely happy with the overall outcome of the project,” reports Zacchini.
Renewing and Revitalizing
At the Jordan Downs Housing Projects in South Central Los Angeles, CA, Modular Wetlands units were recently installed to improve stormwater quality and increase usable aboveground space. The high-profile project is located “in an impoverished and abandoned industrial area the city wanted to redevelop for housing and retail,” says Cameron McKay, a stormwater management environmental engineer with Bio Clean Environmental. “There was much fanfare and media attention around this revitalization. But it needed infrastructure improvements.”
For nearly two decades Bio Clean, a Forterra Company in Southern California, has been developing stormwater treatment solutions designed to keep up with the changing regulatory environment. The product line now includes everything from stormwater inlet grates, debris filters, and hydrodynamic separators to downspout filters, Kraken membrane filtration, and Modular Wetlands biofiltration units.
According to city announcements, the new “urban village” would include 710 new apartments, retail shops, restaurants, and a grocery store, plus 9 acres of green space. But current residents, while heartened by the news of new housing and revitalization, were concerned about the effect of legacy toxins. The site was formerly used for steel manufacturing and metal processing, and later a trucking company stored fuels and solvents on the site slated for development.
After hundreds of thousands of tons of soil were removed from the building site, testing showed that there was no longer any chemical concentration that posed risks. Nonetheless, the city installed filtration units.
“Natural wetlands are nature’s way to filter water, but as these have been disappearing with new development, our Modular Wetlands acts as a ‘natural wetlands’ to reestablish nature’s presence and rejuvenate the waterways of today’s urban environment,” says McKay. “What we did, in collaboration with Fuscoe Engineering, was to remove the existing 59 bioswales on the Jordan Downs property and replace them with 30 Bio Clean Modular Wetlands.”
He explains that this installation of subsurface filtration allowed the developers to add more housing acreage, allowing up to 200 more residential units than originally planned.
“The bioswales were taking significant aboveground space, but Modular Wetlands can be placed subsurface—under sidewalks and parking lots—and can be in a planted area with attractive vegetation aboveground. When you have more land to work with, you can do more—have more space for shops and public green space for people. If bioswales or detention ponds are taking up space, you can’t build there.
“By using Modular Wetlands, we ensured that the 118-acre property footprint would safely and efficiently remove contaminants of concern including TSS, hydrocarbons, trash, dissolved metals, phosphorous, nitrogen, and bacteria. These units are precast concrete vaults manufactured by Forterra that can be made in various lengths and heights and can attach to curbs or gutters or placed in planted areas, streets, or parking lots, at grade with vegetation or underground without vegetation.
“They can also be attached end to end to create a longer row of filtration units. And since the water filtration process is based on a linear concept that uses a natural horizontal flow that we introduced in 2007, rather than a downward flow, clogging and backups are virtually impossible.”
McKay explains that the two-part biofiltration units (pretreatment and biofiltration) come in three standard widths—4, 8, or 10 feet—and a standard depth of about 4.5 feet. “They can be as shallow as 2 feet and we have made them as deep as 19 feet,” he says.
The pretreatment chambers of the units contain WetlandMEDIA, a proprietary, organic-free, sorptive ceramic media with high ion exchange capacity for nutrient removal. “It also supports a robust vegetation and prevents standing water,” says McKay.
The pretreatment chambers may have built-in curb inlets and can be fitted with an optional internal bypass for high flows. They can also be configured with a grate inlet or can have the stormwater piped in from the side, sub-surface. Trash, debris, hydrocarbons, dissolved metals, and sediments are isolated and removed, which allows the biofiltration chamber to remain unclogged to do its job to its maximum capacity.
“This inorganic media acts like a natural wetland filtering the water. Plant roots take up nitrogen and phosphorous. Microbial communities thrive in the media in this system and realize a high reduction of bacteria.”
The “good bacteria” in the system, as McKay dubs them, work with the surface-layer vegetation to help remove phosphorus, one of the nutrients that can lead to algae blooms and oxygen depletion in surface waters.
With a depth of about 4 feet and a discharge chamber underground that ties into the storm drain system, the vaults at Jordan Downs were placed 75% underground, giving them the appearance of planter boxes.
“You’d never know that what looks like a planter is actually a Modular Wetlands biofiltration system for stormwater,” he says.
He says Bio Clean has an ongoing working relationship with the California Water Board, Orange County Coastkeeper, and the Orange County Transportation Authority “to mitigate and keep down the amounts of cyanobacteria present in [these] waters. Bacteria that used to simply go into the storm drain and then into the bay are significantly reduced. In Orange County alone, we have several hundred Modular Wetlands, and most of the time you’d never know they are even there.”
One new project will deploy a Modular Wetlands unit whose size will break all records. At a redevelopment site in Whittier, CA, the Nelles Youth Correctional Facility, 705 new residences will be built. “We’ll be capturing drainage from the entire area with an 85-foot by 105-foot Wetland Mod, an LA County-approved version of the Modular Wetlands. That is definitely going to be the largest one manufactured to date and will look much like the Madrona Marsh Preserve and Nature Center project in Torrance, CA.”
The Madrona Marsh Preserve attracts so much wildlife that the levels of bacteria had been damaging the ecosystem. He says Bio Clean customized a Modular Wetlands system to mitigate the high levels of bacteria.
“But as with the Jordan Downs site, using these horizontal flow Modular Wetlands units in Whittier will free up space, which in California is at a premium. The developer now has the opportunity to use more of the property for residences instead of detention ponds, drainage outlets, and other stormwater-related components. It’s a bonus for the developer, for the environment, and also for the people who will live there.”