Turning Food Waste into Soil Sauce

Dylan Lew walks up to a shipping container and pulls on a drop–box handle where people dump their leftover french fries, half–eaten salads and other food waste.

In go the food scraps. Out comes “Soil Sauce,” an organic plant fertilizer that is a healthy byproduct of all that waste.

What doesn’t come out of the ZEUS digester system is methane, a gas that leads to global warming and accounts for 8 percent of global emissions just from rotting food waste alone.

Lew, the 25–year–old Chief Executive Officer and Co–Founder of Ecotone Renewables, and his friends in college came up with the digester system as a way to lessen food waste, enrich soil and divert harmful carbon gas from the atmosphere.

“I’m an impatient person,” said Lew, a Carnegie Mellon University materials engineering graduate.

“Food waste is such a big global problem.”

About 40 percent of all food is tossed out before consumption, a startling figure that not only wastes resources but also harms the environment.

The Pittsburgh–based startup has five digester systems in the field, at locations ranging from the Pittsburgh International Airport to Allegheny General Hospital.

The Richard King Mellon Foundation made a $350,000 investment in Ecotone Renewables to help scale to five anaerobic digester systems while improving local soil health and supporting underserved communities. This initial investment helped anchor future investment rounds so they can continue to scale up. The third iteration of the digester is called ZEUS.

The investment is part of the Foundation’s Social–Impact Investment program, which provides capital to mission–driven, for–profit companies to enable them to develop products and services that address societal issues.

Ecotone works with the Greater Pittsburgh Community Food Bank and 412 Food Rescue to make sure any salvageable food goes to people in need.

“They are both incredible organizations that are the frontlines trying to redistribute food before it gets wasted,” Lew said. “I see us as the safety net for food that is already spoiled when it comes to them, and we can sustainably process.”

The company, which sells its Soil Sauce, also donates the fertilizer to community gardens and farmers, and hires local artists such as Juliandra from PBJ Customs, who painted a vibrant mural on the front of one of the systems where people throw their food waste.

The company helps the environment by preventing the costly and fuel–guzzling process of transporting food waste to landfills, while also cutting back on methane and other harmful gasses.

“We’re up to about 180,000 pounds of food waste diverted to date. That’s equivalent to about 25,000 big, mature trees diverting carbon for us,” Lew said.

Living up to its sustainability ethos, the company uses the gas it collects to power the system and keep it heated throughout the year.

The inside of the trailer is filled with pipes, controls, a grinder that pulverizes food and a tank that mimics the process of human digestion by breaking down food anaerobically. Ecotone has two patents pending.

Lew collaborated with fellow Carnegie Mellon, University of Pittsburgh and University of Michigan students on the company’s early inception as Pittsburgh’s first portable farm. This first system used fish waste to feed nutrients to the greenhouse plants on top of the fish tank system. Realizing the process was better suited to a large scale, they pivoted to the digester model, launching the first system in 2019. Lew is joined by Co–Founders Kyle Wyche and Elliott Bennett who are leading the company as COO and CFO respectively.

A foodie who loves to go to restaurants and cook himself, Lew said he enjoys talking to chefs about the digester. Ecotone already has leased one to a vegan restaurant chain in Rhode Island called Plant City and is talking to another national restaurant chain in California.

Lew, the impatient green entrepreneur, is thinking globally. “I see us scaling up to become the much–needed monster gobbling up all the food waste in the world.”