Sewage water from some Peninsula cities is collected and treated at Silicon Valley Clean Water in Redwood City. And whiffs of thousands of tons of sewage sludge are unmistakable from the lunch patio at Bioforcetech Corporation, located just steps from its new plant.
"Its smell – you kind of get used to it," said Dario Presezzi, the chief executive officer at Bioforcetech. "We’ve been giving almost 12 hours a day, every day – night times sometimes – because it’s been extremely challenging."
Presezzi and his team of Italian-born engineers and specialists came to Silicon Valley to turn waste to energy in a process he says is not yet allowed in their home country.
"It was just the biggest challenge that was out there, to make energy," Presezzi says. Since solar panels and wind turbines didn't interest him, Presezzi and his team began working with the out-of-sight, out-of-mind tons of sewage sludge running through tunnel systems underground.
Sewage sludge is the human urine and feces that drain from people's toilets. Through this process, it is dried and processed into biosolids, which is the name given for recycled and processed sewage. After it is drained of about 70 percent of its water weight, Bioforcetech runs the biosolids through a flameless burner to create biochar, a charcoal-based fertilizer.