Filter project combats pollution in Long Island Sound

Initial test results confirm technology’s effectiveness in destroying bacteria in stormwater and wastewater.

Th 0607wwi Filter01

Initial test results confirm technology’s effectiveness in destroying bacteria in stormwater and wastewater.

Long Island Sound’s newest environmental hero - the Smart Sponge® Plus - more closely resembles SpongeBob Squarepants than the muscle-bound caped superheroes of yesterday. This non-toxic, funny-looking sponge-like material uses an antimicrobial agent to perform the daunting task of destroying health-threatening microorganisms that contaminate waterways.

Th 0607wwi Filter01
The antimicrobial agent destroys the cell wall of bacteria molecules.
Click here to enlarge image

As part of a stormwater management improvement project, more than 275 storm drains in the US city of Norwalk, Connecticut, have been fitted with high-technology filtration systems equipped with Smart Sponge Plus. According to initial field tests, the project’s filters destroyed a high percentage of bacteria, including E. coli and other fecal coliform. The average removal rate was over 75 percent and the maximum removal rate was 99.9 percent. In addition, the first cleaning of the 275 catch basins yielded over 7.4 tons of trash, debris, leaves, sediment, and sand (including needles and syringes), preventing it from entering the Sound’s recreational waters.

The Arizona-based company AbTech Industries produces the filtration systems - Ultra Urban® Filters with Smart Sponge Plus - and holds the technology’s patent. Norwalk is using the antimicrobial Smart Sponge® Plus4 in the high volume stormwater catch basins selected for this project.

Rodolfo Manzone, Ph.D., the company’s executive vice president and chief technology officer, explained how the product destroys bacteria without using toxic chemicals that would create additional environmental problems: “The Smart Sponge Plus employs an antimicrobial agent, chemically bound to the polymer filtration material, which inactivates health-threatening microorganisms. The mechanism is based on the agent’s electromagnetic interaction with the microorganism cell membrane, causing the microorganism disruption, but no chemical or physical change in the agent. Consequently, the antimicrobial agent is not depleted over time and it maintains its long-term effectiveness.”

Manzone said that AbTech Industries’ antimicrobial technology has definite possibilities beyond stormwater applications. “As a result of the continuing validation we’re receiving from field tests, we are looking at other applications, including the wastewater area, where the Smart Sponge Plus’s unique mechanism of action could offer distinctive advantages. Over the next 12 months, we expect to find suitable partners to enter into this new and exciting phase.”

Th 0607wwi Filter02
Click here to enlarge image

An added benefit of the filtration systems is its ability to encapsulate and transform hydrocarbon pollutants into a stable solid for easy recycling through waste-to-energy facilities. It provides a closed-loop solution to water pollution and allows for less costly and less problematic handling of the waste product.

Th 0607wwi Filter03
Click here to enlarge image

Hal Alvord, Norwalk’s Director of Public Works, said that the project is of critical importance to the community and the environment. The Long Island Sound watershed houses eight million people with another 20 million living within 50 miles of it. The filter project addresses nonpoint source pollution - the most significant threat to Connecticut’s and the nation’s waterways. According to Alvord, “Nonpoint source pollution includes the urban runoff that flows from paved surfaces through our storm drain system.”

Th 0607wwi Filter04
Installation of the lightweight Drop In series of the Ultra Urban® Filter requires no modification to the existing structure. In less than 45 seconds, these installers lifted the grate, placed the filter, and put the grate back in place.
Click here to enlarge image

The City of Norwalk, with a population of 84,000, is different from other Connecticut municipalities in that it has a harbor, marinas, and a shellfish industry. People are equally at risk of exposure to toxins whether they fish in the Sound to feed their families or whether they use the waters for recreation. The public health threats exist primarily because of bacteria.

Alvord said that the part of the city selected for the project includes two drainage areas in Norwalk that have a similar land use - residential, industrial, marinas, and nurseries. The first is a basin with 275 drains, equipped with Smart Sponge Plus antimicrobial filters, which empty through one pipe into Norwalk Harbor on the way to the Long Island Sound. The second, the “control” basin, does not have filters and also flows through one pipe into the harbor.

Much of the project cost - over US$ 500,000 - resulted from legislation sponsored by US Senator Joseph Lieberman and provided by the US Environmental Protection Agency.

The City of Norwalk will continue to evaluate the project’s success according to the percentage of reduction in hydrocarbons, bacteria, and other pollutants entering Long Island Sound from the targeted catch basins. The monitoring will be an effort shared by the Long Island Soundkeeper, the City of Norwalk, and AbTech Industries (through Longo & Longo, a Connecticut-based AbTech distributor). Although the project is a three-year campaign, it will be sustained long after the grant period has ended.

Author’s Note

J.I. Shane is a lecturer at University of California in Los Angeles (UCLA) in the Department of Civil & Environmental Engineering. For more information, visit

More in Environmental