Howard Carter wants people to know that wastewater treatment plants are in the business of protecting — not polluting — the environment. He sees promoting green technology and energy efficiency as ways to help change the public's perceptions.

"The industry, at least in the past, did a very poor job of promoting what we do," says Carter, director of the Water Resource Recovery Division for Saco, Maine, on the Atlantic coast just south of Portland. "The industry has tended to stay out of sight, out of mind," until a main broke or a combined sewer overflowed.

"You've seen a whole paradigm shift in the industry, which is a great thing," Carter says. "We are environmentalists." Using renewable energy helps demonstrate that to people. It also saves money: the Saco Water Resource Recovery Facility has cut its heating oil use by 88 percent since the winter of 2004-05, from about 8,000 gallons per year to 1,000 gallons.

"We're trying to get the next generation to appreciate water," Carter says, in much the same way efforts in the 1970s convinced people to stop littering. "It may take 20 years," he says, "but we have to start somewhere."

Well recognized

Under Carter's leadership, the Saco treatment facility has received several awards including:

• U.S. EPA National First Place Award for combined sewer overflow control program excellence, 2000
• U.S. EPA Region 1 Operations & Maintenance Excellence Award, 2002
• Certificate of achievement from the Maine Department of Environmental Protection for energy efficiency, 2008
• George W. Burke Jr. Facility Safety Award from the Water Environment Federation and New England Water Environment Association, 2009

Carter won NEWEA's 2012 William G. Hatfield Award for his own outstanding performance and professionalism, and received the eco-Excellence award in 2011 from ecomaine, a nonprofit, municipality-owned waste management company. He was recently inducted as a WEF Fellow.

"It's recognition of everyone involved," says Carter. He notes that the awards also help bring attention to protecting the environment. Along with his goal of having his facility become energy neutral, or even an exporter of power, Carter wants people to better understand the importance of water and wastewater treatment.

Starting small

Carter admits the plant staff at first was not as enthusiastic as he is about energy efficiency and green technologies. "Eventually, people started coming around and embraced the concept," he says.

Saco started its Energy Committee in 2005, when it was considering installation of a large wind turbine at its landfill. However, Carter and other committee members selected a small 1.8 kW Skystream microturbine from Southwest Windpower. "Instead of doing a meteorological study for a large turbine for about $40,000, we bought the microturbine for $8,000 and the staff installed it," he says (see article in TPO, July 2009).

The wind turbine doesn't make a big dent in the plant's $6,500 monthly power bill — it only generates about $70 worth of electricity. But it did help draw the public's attention and build support for more green technologies, including effluent heat recovery, solar installations, and sky tubes for lighting.

Carter emphasizes that only so much can be done at a smaller plant like Saco's activated sludge secondary treatment facility with biological nutrient removal, serving 4,800 connections with an average flow of 2.4 mgd (4.2 mgd design). But the plant has certainly done its share to lead the city's efforts to improve efficiency.

The community of nearly 19,000 has converted its downtown street lights to LEDs, bought an electric car, replaced refrigerators and computer monitors in city offices with energy-efficient models, and installed a 50 kW wind turbine at its new transportation center and Amtrak station, built with all recyclable, local materials and with geothermal heating and cooling.

A new fire station commissioned in 2011 is also using geothermal and other energy-efficient designs and just received LEED certification. The city is designing a new Public Works facility that will incorporate many of the same concepts.

Those are the types of things Carter has been doing in his own life for about 20 years. "I have geothermal and solar thermal at my home," he says. He hasn't added photovoltaic panels, but he did orient the house facing south to better capture the sun when he does decide to add them.

Effluent thermal

In winter 2010, the Saco Water Resource Recovery Facility joined the growing number of treatment plants using effluent heat recovery. The $336,000 system was designed by Woodard & Curran and purchased from Nyle Systems in Brewer, Maine. With three 10-ton compressors, it heats and cools a new $3.5 million, 3,070-square-foot process building and a 2,400-square-foot maintenance garage that includes chemical storage.

Carter says effluent thermal technology has been around for more than a decade and is just another version of geothermal. "Now it seems to be the thing to do, and why wouldn't it be? Everyone has all that water going through their plants; they might as well utilize it."

Saco's effluent runs around 70 degrees F in summer; the coldest ever recorded in past years was 48 degrees. "That's a perfect range for geothermal," he says. As a heat pump, the system transfers energy from the effluent to heat buildings in winter, and does just the opposite in summer to provide cooling.

While it's impossible to compare energy use at the old process building to the new facility, the effluent thermal has nearly eliminated fuel oil use at the treatment plant. Only a small administration building still uses oil heat, and total oil use has been cut by nearly 90 percent. As part of the construction project, the city installed a $48,000 power correction system: poor power quality can increase energy use and damage equipment.

Years of investment

Since 2005, the Saco Water Resource Recovery Facility has spent nearly $490,000 on various renewable energy sources and more efficient equipment. The result has been annual savings of nearly $70,000 with a simple payback of about seven years.

The 680-square-foot headworks building is heated with two sets of 30 solar thermal panels (Viessmann) that heat a pair of 80-gallon water reservoirs to serve the radiant heating system. The panels were purchased locally from Saco Solar and installed by staff and a local contractor. "That building hasn't used any fuel oil in five years," notes Carter.

The plant's new administration building, garage and process buildings use SolarSheat solar air units (Your Solar Home) for supplemental heat. Each of these units, also purchased locally at an installed cost of $30,000, can heat up to 1,500 square feet. Ambient air is drawn into the units by a fan, heated by solar energy, and discharged at ceiling height. "Those have been very economical," says Carter. "We have them installed here, at Public Works, and at the fire station."

Solar lighting, in the form of Solatube International light tubes purchased at Saco Solar, serves the process building, the garage and a pump station. Carter calls them "the neatest things in the world." Also called sky tubes, they collect and amplify natural daylight through pipes coated with reflective material.

"It's good natural light so we've been able to turn off a lot of fluorescent lights unless it's real cloudy," Carter says. Since the staff is on site only during the day, no other lighting is needed about 70 percent of the time.

All light fixtures at the facility were upgraded during the construction of the new buildings. Nearly 70 high-efficiency LED and fluorescent fixtures from various companies were installed indoors and outside at a cost of $16,000. All process motors in the facility and at the 31 satellite pumping stations use variable-frequency drives (Toshiba); more than 75 have been installed over the years with electricity savings of about 15 percent.

More to come

Carter also points to new, promising developments that can help the wastewater industry and the environment, such as technologies to capture ammonia and phosphate for fertilizers and microbial fuel cell technology that can generate electricity through chemical energy created by microorganisms. "There's a lot of energy in the water flowing through these facilities that we have yet to tap into."

He believes promoting efficiency and green technology will help bring more attention to the critical infrastructure that is now being ignored. "The roads and bridges get their recognition, as they should," he says. "It's the stuff that's out of sight, out of mind that is really starting to fail throughout this country. If we don't start putting some more money into it, we're going to be in a world of hurt eventually."