Getting rid of waste the clean way:Redwood City company finds a way to turn biosolids into fertilizer with no energy

Starting in April, the small team of Italian natives that make up the Bioforcetech team have the opportunity to make a large dent in a problem most prefer not to think about — what happens to the truckloads of human waste processed at wastewater treatment plants — when they will begin processing half, or 7,000 tons, of the Silicon Valley Clean Water treatment plant’s biosolids, a friendly term the Bioforcetech team uses for human waste.

For Daniel Child, manager of the Silicon Valley Clean Water treatment plant, the Bioforcetech team’s work offers another option for solving a problem with few tried and true solutions. Currently, the biosolids that come through the plant are spread out on land to be dried by the sun for days before they are trucked out of the plant to fertilize farms in Solano County or nearby cities like Sacramento or Modesto.

“Disposal of biosolids is an ongoing challenge in the state of California,” he said. “It’s always good to have more than one option.”

When Presezzi and a few colleagues came to the Silicon Valley Clean Water treatment plant from Italy to explore how their system could work in the United States in 2011, it wasn’t clear the marshy land at the tip of Redwood Shores would become home to their offices.

But ever since 2011, when the plant treating wastewater from Redwood City, San Carlos, Belmont and other jurisdictions voiced support for their team, the six members of the Bioforcetech team have been hard at work refining a college project.

“It wasn’t really that we dreamed about doing this our whole lives,” said Presezzi.

The CEO, who is now 29, came up with the idea to find a new way of dealing with the biosolids collected at wastewater treatment plants with two other friends studying biotechnology at the University of Milan some six years ago.

“Usually, this process was approached by engineers, so nobody thought [about] using bacteria and life to try to dry biosolids,” he said. “So we came up with this idea and we tested it a little bit and it worked on a small scale.”

Spreading the solids out on land or using a gas dryer to shrink them before they are shipped to farms as fertilizer are two methods currently used, causing Presezzi and his friends to wonder if biology might be used to accelerate the process and generate the energy needed to fuel it.

Their curiosity has led them to design a set of large cylinders aimed at accelerating a process similar to compost, in which oxygen-fueled bacteria break down the solid matter into smaller pieces.

“In 48 hours, we are able to dry biosolids without using any gas from about 80 percent water to 20 percent water,” he said.

Presezzi said the process to dry the biosolids using a composting method could take up to 20 days if not accelerated.

Once dried, the shrunken biosolids are then ushered into another machine that heats them up in the absence of oxygen to about 1,100 degrees Fahrenheit, causing more of the mass to evaporate and creating the energy used to fuel the two machines. The process, called pyrolysis, also produces thousands of small, black particles with large pores and a volume that is 8 percent of the volume of the waste fed into it.

While the energy generated through pyrolysis is fed back into the system to fuel the BioDryer and pyrolysis machines, the black particles, which Bioforcetech have named Nutrieno, have also been rid of toxins and chemicals through the high heat of the process.

The presence of trace chemicals, drugs and other toxins in processed biosolids have caused some jurisdictions to ban or restrict their agricultural use, which Presezzi said is another reason why the process Bioforcetech has developed is critical.

Using one-thirtieth of the space needed to spread and dry the biosolids collected at the Redwood City plant, Bioforcetech’s two processes can help save the plant hundreds of trips from truck drivers transporting the dried biosolids from Redwood Shores to farms in rural areas.

Starting in April, the plant will process half of its biosolids by drying them in the sun and shipping the dried solids and the other half using Bioforcetech’s BioDryer and pyrolysis method, which Presezzi estimates can bring the number of trips trucks take in an out of the plant down to 90 from the 1,000 trips clocked annually.

The savings in fuel costs are what make the cost of processing biosolids especially volatile, said Presezzi. He said the costs, which fluctuate with the cost of fuel, can vary from $60 per ton of biosolids to $200 per ton of biosolids, while he estimates Bioforcetech’s costs to stay close to $55 per ton of biosolids.

“The price of treating it won’t grow because it doesn’t grow with energy costs,” he said.

Though the six men ranging in age from 25 to 32 on Bioforcetech’s team have forfeited hobbies and most pursuits outside of their work to perfect their system, their hard work might finally be paying off. Two years after they requested a permit from the Environmental Protection Agency to run their machines, the team has been given the green light to operate. Presezzi estimates he and the team have issued $700 million in quotes to plants in other cities and states. But despite the hype, they remain committed to making their systems work.

“At the stage we are at today, we just wanted to get to a final working product,” he said.

As a member of several organizations focused on best practices for wastewater treatment across the state, Child said hardly any meetings go by without a few requests for an update on Bioforcetech’s work. Child is excited for the startup’s system to begin processing a higher volume of biosolids and hopes he can soon welcome representatives of other plants to Redwood City for a tour.

“This is the very first one in the world,” he said. “We’re excited about being at the forefront and helping the environment.”

Though the company has secured $6 million in funding to date, Presezzi said the team wants to be sure their system is proven before they seek more funds or begin work with other plants.

In the next year, the team hopes to begin selling Nutrieno to cities and property owners, which Presezzi hopes will be available in the coming months. But the group has their eye on the impact their systems can have in the long run, helping wastewater treatment plants develop efficient ways to get rid of waste.

“Our final goal is to ensure that the standard biosolid treatment is this,” he said.

anna@smdailyjournal.com

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