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Breaking down sewage with bananas and rocks

IPSWICH -- This New England town's very first winter banana harvest is facing an ignominious demise.

The bunches of beautiful, bright green bananas growing in a greenhouse off Old County Road will ripen into an appetizing offering by mid-January, only to be thrown into a compost heap with dead leaves and assorted vines. The problem with eating these bananas, those tending the crop say, is what the bananas are eating.

''Basically, it's raw sewage," said David Del Porto, president of Ecological Engineering Group, a Concord-based company that builds alternative sewage treatment systems. ''The nutrients in raw sewage make these things grow like crazy."

The banana trees and a host of other out-of-place plants serve as the sewer system for New England Biolabs' brand new 140,000-square-foot headquarters. Every day, about 6,000 gallons of human and industrial waste water is being pumped into the open air vats and huge underground garden boxes built into the greenhouse.

The real cash crop is not what's inside the greenhouse, Del Porto said, but what's coming out of it: water nearly clean enough to drink, produced by a high-intensity septic system that uses plants, snails, and a lot of bacteria and algae to eat hundreds of pounds of pollution a day.

The system is called Solar Aquatics, and Del Porto's company is installing them across the state and country. Solar Aquatics breaks down sewage much like conventional septic systems, only with a little more process and a lot less stink.

''It's a mini-rain forest in there," said New England Biolabs chief executive officer Jim Ellard, who has toured the greenhouse a number of times. ''It's a more natural approach to treating waste water. It's sound ecological practice and it's got the added bonus of being beautiful."

A key part of that process at the Ipswich plant are 24 1,100-gallon vats bubbling with sewage and brimming with swamp vines like watercress, willow, and water hyacinth. The 6-foot vats have clear sides that let in sunlight, which fuels waste-eating algae and makes the gray liquid inside ideal for growing gardens, said EEG engineer Mait Walker.

''Sunlight is providing the engine for this system," he said during a recent tour of the Ipswich plant. ''One of the reasons New England Biolabs could build their plant here is Solar Aquatics."

That's because the manufacturer of medical products is too big, too close to wetlands, and too far from the city's conventional sewage treatment plant to hook up. So Del Porto and company were brought in, and the sewage problems were solved, at a cost of $1 million. As a perk, a butterfly garden is being planned alongside the banana plants next spring.

''All we do is create a whole bunch of vessels in which life forms break down the waste in the waste water," Del Porto said. ''Then we string these [vessels] along in a sequence that provides an optimal growing environment for a variety of plants."

The details, however, are a bit more complicated. At the plant EEG built in Ipswich, the waste water leaves New England Biolabs through an 8-inch pipe that discharges it into underground tanks just outside the greenhouse.

There, the water is shot with air to blend the contents and provide oxygen needed to jump-start the bacteria that is key to just about every step of the process that follows. The blended water is then pumped into the clear vats where algae, bacteria, and tiny snails go to work on it.

Next stop is the garden, which is little more than a huge box of small rocks that can grow any plants the customer wants, Del Porto said. But the plants only drink a little of the water.

The rest washes over the roots, which host special bacteria capable of converting harmful liquid nitrogen into harmless nitrogen gas. That box of rocks and roots, called a constructed wetland, is another key component of Solar Aquatics, Del Porto said.

Ultraviolet lights kill off any remaining bacteria, and the crystal-clear end product is returned to the ground water through a leeching field a quarter-mile from the plant.

''The reason you don't smell anything is all the plants," he said standing next to one of the bubbling vats of sewage. ''That's the great thing about these systems; they are not only cleaner, but they also make great neighbors."

For expensive neighborhoods.

West Newbury developer Wayne Vynorius recruited EEG to design a plant for his proposed 268-unit development called Meadowbrook Estates.

The Meadowbrook plant would treat about 60,000 gallons of waste water a day and cost $2.5 million. That plant, like the facility in Ipswich, requires an operator to run. All the costs have to be picked up by the owners, making Solar Aquatics a little too pricey for your average single-family house.

''The cost is a driving factor; you have to have a large project," Vynorius said. ''But it's almost a fail-safe system."

If costly, Solar Aquatics is also a clean septic system alternative for environmentally sensitive land that could otherwise not support any development, Walker said. And components of the system, such as the constructed wetlands, can be used independently to deodorize and clean up existing septic systems for a lot less money than the total package.

''The wetland is just a box of rocks; the land for it is the expensive part," Walker said. ''You can add the constructed wetland to any existing treatment plants and grow native plants year-round without the greenhouse."

EEG built a Solar Aquatics system using native plants for a Weston commercial development that has been running successfully for nine years. Now the state is looking at Solar Aquatics for a proposed expansion of the fire training academy in Stow.

Del Porto said his company is also building Solar Aquatics systems in South Carolina, Arizona, and Colorado. Apparently, as clean water becomes scarce in the Midwest, more and more people are worried about the water they don't use.

''It's only waste water if the water is wasted," Del Porto said. ''This doesn't waste the water, and they look and smell great."

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