In many communities, stormwater no longer flows untreated off streets, roofs and parking lots into important waterways. Driven in part by federal regulations, many municipal agencies have installed stormwater filters that trap trash, debris, oils, and other contaminants before they enter the environment. Here is a sampling of the stormwater filtration technologies now available from industry manufacturers. Many of these qualify as Best Management Practices under U.S. EPA regulations.
Custom-engineered
The Aqua-Filter stormwater filtration system from AquaShield Inc. is for sites requiring advanced treatment of runoff stormwater that may discharge into sensitive receiving waters. The system can be custom designed for new construction projects or retrofitted for existing storm drainage structures. Its modular shape and HDPE construction make it easy to install.
Peripheral pretreatment of contaminated stormwater is unnecessary, as the system uses a treatment sequence that removes coarse and fine pollutants. The Aqua-Swirl concentrator removes gross pollutants, allowing larger debris to settle before filtration. Third-party testing demonstrates total suspended solids removal of greater than 80 percent, and the effective removal of additional pollutants including free-floating oils and debris, phosphorus, and heavy metals such as copper and zinc.
The system operates under gravitational and hydrodynamic forces with no moving parts or valves. It also runs in an offline configuration as recommended by the Center for Watershed Protection and most municipalities, treating 90 to 95 percent of the annual rainfall on a given site. 888/344-9044; www.aquashieldinc.com.
Phosphorus filtration
FabPhos filters from Fabco Industries Inc. treat total and orthophosphates in surface water runoff. Field studies have confirmed reductions of greater than 50 percent. The media comes in replaceable cartridges to fit StormBasin and StormPod catch basin inserts or in bulk form. 516/433-4148; www.fabco-industries.com.
Canister filters
EcoSenseT stormwater filtration systems from EcoSense International are structural devices tested and used internationally. They have demonstrated greater than 95 percent TSS removal as well as effective removal of pollutants including suspended and emulsified hydrocarbons (oils, grease, and fuels), phosphorus and nitrogen, volatile organic compounds, PCBs, and various organically bound heavy metals, while allowing the treated water to pass through quickly and safely to be reused or discharged.
Media formulations that kill bacteria and remove dissolved heavy metals are available. The systems are designed to deflect materials like leaves and coarse sediments away from the entry ports, minimizing flow impedance. After first flush, the Clean PassT Over Flow bypass system detains floatables, allowing only clean water through. Once the storm event subsides, the filter catches up and continues to filter all incoming stormwater. Filters last six months to two years depending on the appli-cation. Systems are usually installed in less than one hour. Call 866/449-0324 or visit www.ecosenseint.com.
Multiple approvals
The stormwater management StormFilter from Contech Stormwater Solutions removes most target pollutants including fine solids, soluble heavy metals, oil, and total nutrients. Its surface-cleaning system prevents surface blinding to extend cartridge life.
The filter has been field tested and has received hundreds of stand-alone approvals from regulatory agencies. It was the first to receive Final Certification from the New Jersey Department of Environmental Protection as a stand-alone stormwater treatment system. Recent enhancements decrease the overall system size, provide a low-drop cartridge for sites with hydraulic drop limitations, reduce installation time, and simplify maintenance. 800/925-5240; www.contechstormwater.com.
Stainless construction
Hurricane Swing Bolt filters from Harmsco Inc. are built to ASME design with flow rates up to 1,200 gpm. The Hydro-Cyclone tangential inlet and integral inner can create a centrifugal flow that induces pre-filtration by heavy particulate separation.
The upflow design self-purges air from the housing, eliminates bypass contamination during servicing, and improves efficiency by creating an even flow distribution across the filter media. Swing-bolt-style-housing closures are easy to service and allow uniform loading of filter media. Replacement filter cartridges come in assorted models including antimicrobial and activated carbon. One person can perform maintenance. 800/327-3248; www.harmsco.com.
Targets pollutants
The FloGard Perk Filter from Kristar Enterprises Inc. captures and retains sediment, oils, metals, and other constituents close to the source, reducing the total discharge load in stormwater runoff from urban developments. The filter cartridge is made from durable polymeric components with a polymer-coated steel support screen and stainless steel hardware. Its base construction allows various media to address site-specific pollutants.
With modular and scalable design, the filters provide a simple and low-cost solution for installation and long-term maintenance. Units may be installed as a retrofit to suitable existing curb inlets, drop inlets, or combination catch basins, as integral parts of coated steel- or concrete-housed stormwater inlet systems for commercial, residential, and industrial developments, or as centralized modular treatment systems installed online or offline. 800/579-8819; www.kristar.com.
Urban filter
The low-maintenance Ultra-Urban Filter with Smart Sponge from AbTech Industries Inc. treats stormwater runoff for new or retrofitted sites by absorbing oil and grease, and capturing trash and sediment. The system, suitable for municipal, industrial, and construction applications, is identified by the EPA as a Best Management Practice for stormwater management.
The Smart Sponge Plus filter destroys bacteria using an antimicrobial agent that is chemically and permanently bound to the polymer surface. Targeted bacteria include enterococcus and coliforms such as fecal coliforms and E. coli. Filters come in modular units for curb inlet openings and single units for drop-in catch basin drains. 800/545-8999; www.abtechindustries.com.
Antimicrobial chambers
Kleerstream antimicrobial filtration chambers from Katchall Filtration Systems LLC combine two separate filtration technologies inside one reinforced, self-contained concrete structure. Particulates greater than 100 microns, debris, and floating materials are removed in the hydrodynamic separation stage.
In the second stage, antimicrobial filtration weir walls remove total suspended solids, hydrocarbons, nutrients, and heavy metals to less than 50-micron levels, and provide positive pathogen kills up to 99.99 percent with less than one second contact time (results from Microbac Laboratories Inc. in Corona, Calif.).
The shallow-draft chambers are 4 to 6 feet deep and require only a 12-inch height differential between the inlet and outlet pipe elevations. Model 120, the smallest unit, needs less than 40 square feet, is H-20 rated, filters 7.6 cubic feet per second, and retains about 1.5 cubic yards of solid waste materials. Seven sizes are available for inline or offline (first flush) filtration devices. 866/528-2425; www.katchall.net.
Efficient removal
ClearWater BMP stormwater filters from ClearWater Solutions Inc. use a stainless steel filter system that screens, triple settles, and filters stormwater within concrete sidewalk curb inlet drain boxes. The design reduces concentrations of trash, sediment, hydrocarbons, metals, and nutrients.
San Diego State University testing established that units remove 97 percent of total suspended solids, 86 percent of hydrocarbons, 83 percent of zinc, and 81 percent of lead. Designed to retrofit within existing curb and gutter infrastructures, the filters handle heavy storm flows, are non-scouring, use mosquito-free technology, and require no excavation or concrete modification. 800/758-8817; www. clearwaterbmp.com.
Open curb inlet
The Open Curb retrofit installation kit from Transpo Industries Inc. employs the EnviroSafe modular stormwater catch basin filtration system. Designed specifically for open curb inlets, the kit includes a cartridge basin with modular filters or sediment sack, four supporting cleats, two aluminum rails, two mounting flanges, and one flow collector assembly with hardware. The system captures trash, debris, sediments, oils, grease, and soluble metals. Filters incorporate antimicrobial treatment that inhibits bacteria, virus and mold growth. 800/321-7870, ext: 659; www.transpo.com.
