Out of sight, out of mind — that’s what happens with many of the “goods” supply houses distribute to the plumbing and construction trades. Whether in homes, commercial buildings or part of our civic infrastructure, pipe, valves, connectors and related parts are essential to the daily functioning of communities. As suppliers to the trades, you know their value well — but also know that they are not well understood or appreciated by the average citizen.

That attitude is the same with food waste disposers (aka garbage disposals). But now, with increased attention in many cities to the challenges of dealing with food waste, disposers are becoming a new focus of interest for their role as environmental management tools — and also shine a spotlight on wastewater treatment plants and their ability to turn food waste sent there into renewable energy.

The question: If concerned about the environment, what should be done with a banana peel?

In simple terms, food waste treated as trash causes environmental problems whether buried in landfills (where it contributes to greenhouse gases and toxic leachate) or burned in incinerators. Composting facilities face challenges, too, including the use of trucks to collect and transport putrescible material and the odors associated with it.

But at wastewater treatment plants, the banana peel can be converted into fertilizer products and also help generate heat and power for the plant, requiring less from the community. That’s where disposers take center stage, emerging from behind cabinet doors.

Food scraps constitute 15% to 20% of waste from homes. And those food scraps are 70% water, which makes it easy for disposers to pulverize into a slurry sent through waste lines. Recent advances in disposer technology — including InSinkErator’s Evolution series — make it possible to discard all types of food scraps, without concern for noise or clogs. It’s literally possible to eliminate ALL food scraps from landfills through proper use of a new generation disposer.

At the wastewater treatment plant, methane generated from food waste and solids processing can be converted into heat and electricity for use by the plant. Milwaukee Metropolitan Sewerage District estimates it saves about $2 million dollars each year by generating its own renewable power, thus saving residents money and lessening the demand on electrical producers.

Progressive wastewater utilities encourage the use of disposers.

In the United Kingdom, Worcestershire County’s “Sink Your Waste” campaign is a catchy way to describe a direct subsidy of more than $100 (U.S) to encourage residential installations.

The “Food = Energy” initiative of the Milwaukee Metropolitan Sewerage District launched earlier this year in the United States reminds customers that using their food waste disposer is good for the environment. Even Stockholm, following a comprehensive study, encourages disposer usage because biogas is an important fuel for its bus fleet.

Food scraps become a valuable resource when sent to a wastewater treatment facility.

The discussion about upgrading wastewater treatment systems — whether funded by federal stimulus programs or state and local funds — needs to take into account the broader picture of what’s best for the environment and the economic impact of each alternative. But as the nation is driving to find sources of renewable energy, it makes sense to consider what many communities already have: food waste processing at wastewater treatment plants represents a significant source of renewable energy that can help pay for the system upgrade in the long term.

For supply houses, understanding this aspect of municipal infrastructure can also contribute to sales. Upgrading wastewater treatment systems requires significant investment in pipe, pumps, valves and related equipment from wholesale distributors.

Sandi Kegebein, the sustainability coordinator at First Supply in Madison, WI, sees these issues gaining in attention: “Like most cities, Madison needs to re-invest in its capacity to treat wastewater with state-of-the-art technology. We can’t put off this investment any longer, and we need to do it as smartly as possible. That means thinking broadly about the environmental challenges we face, including how we turn resources like food scraps into opportunities for renewable energy.”