An Issaquah company is taking a method once reserved for treating sewage sludge and using it to make organic fertilizer from a grocery store’s food waste.

WISErg has been working with PCC Natural Markets for two years to unveil its first “harvester” at Pickering Place.

Each week PCC would send about 600-800 pounds of tossed food to the local compost processor. Larry Lesueur, WISErg CEO, saw something greater in the spoiled greens and cold pizza, which are much more nutrient rich than grass clippings.

“We wanted to do something bigger and better than compost,” he said. “Expert gardeners know that you need fertilizer too.”

So in 2009 he paired up with another former Microsoft techie, Jose Lugo, who was also interested in environmental issues. Their idea was to build the harvesters where the scraps are dumped.

Compost haulers typically visit PCC 2-3 times a week, whereas WISErg now sends a truck every 10 days. It’s hoping to reduce trips to once or twice a month, meaning even less transportation.

Most of the processing happens in the harvester, although each batch has to be balanced for nutrients and nitrogen levels.

Behind the store, employees skip the dumpsters and unload their food scraps into the grinder, which works much like an oversized sink disposal. Water sprays down on top of greens and cobs of corn, while hefty grinders mash the mixture.

The machine then pumps the liquid into a 12-foot holding tank, which swirls it at a cozy 96 degrees, the perfect temperature for what scientists call “anaerobic digestion” – composting without air.

“It’s like a big brewery,” said Brandon Baker of WISErg.

The company’s first model came with a stench, but after reworking the design, the installation is now odor free. It also has safety mechanisms.

Unlike synthetic fertilizers, which is like steroids for plants, the organic fertilizer adds nutrients to the soil and plants. It might even require less fertilizer, Lesueur said.

PCC plans to sell the finished product, WISErganic, in several of its stores.