San Francisco Chronicle: Device Makes Turning Human Waste Into Compost Safer
Your toilet bowl may hold the key to replenishing forests, growing crops and saving countless gallons of water.
Andersen has invented a device that tracks the decomposition of compost made of human feces, a function that he says could help improve environmental health all over the world.
In earthquake-ravaged Haiti, the technology is being used to monitor sanitary waste in an effort to accelerate the production of disease-free, nutrient-rich compost for agriculture and reforestation. Soon, in a small pilot project in Bolinas, the technology will help make compost out of waste from special toilets that will use less water and possibly ease perpetual water shortages.
The study of decomposing waste is useful, Andersen insists – and not as icky as it sounds. “There’s really very little smell,” he said.
Andersen focuses on aerobic composting, a compost pile that sits in open air and contains, for instance, septic waste and other organic matter such as lawn clippings.
As microorganisms break down and digest the waste, the energy they spend in the process generates so much heat that the temperature in the compost pile can rise above 160 degrees Fahrenheit in just a few days.
At the same time, the unappetizing odors fade. “You go right up to a whole bunch of this stuff,” Andersen said, “and you can’t smell anything but fresh air.”
After a few weeks, the heat in the compost kills organisms that could potentially carry diseases. What remain are “healthy” bacteria, known as thermophilic bacteria, which further break down the heap into soil.
“You completely ensure you have something that’s completely safe and that has no remnants of any of the original waste bacteria,” Andersen said.
It’s a natural process that’s been happening for thousands of years. But it can be tricky to pinpoint the exact stage when the pathogens die and the thermophilic bacteria take over. It’s the difference between nutrient-rich fertilizer that’s safe for growing food, and soil that carries traces of a disease.
This was a problem on Andersen’s mind back in 2003 when he invented the PhyloChip, a palm-size device that identifies tens of thousands of different types of bacteria in any environmental sample, like air, water or soil. Recognized in 2008 with an R&D 100 Award, also known as the Oscar of inventions, the $150 PhyloChip reveals how many and what kind of bacteria are in, say, a hot compost pile. All the PhyloChip needs is a drop of liquid containing extracted DNA from the sample.
Andersen knew the invention was useful, but didn’t fully consider its potential global significance until he met Sasha Kramer.
Kramer is the co-founder and executive director of Sustainable Organic Integrated Livelihoods, or SOIL, a U.S. nonprofit that operates in Haiti.
In this Caribbean nation, where 10 million people are still struggling to recover from a catastrophic earthquake in 2010, waste treatment is almost nonexistent. Most toilets flush directly into rivers, the sea or simply onto land, where untreated waste raises the risk of disease outbreak.
SOIL, which was founded in 2006, works to turn human excrement into compost for agriculture and reforestation efforts. Every month, it treats more than 17,500 gallons of waste and produces 8,000 gallons of compost.
World Health Organization guidelines say that compost piles have to be hotter than 122 degrees Fahrenheit for at least a week to kill fecal bacteria. But SOIL hasn’t had the scientific tools to determine exactly when the pathogens died, so out of caution, the organization waited six to nine months before offering a pile of compost for sale.
“We’re getting it hot enough to kill all the pathogens, but the challenging thing in Haiti is finding laboratories that can do verification for you,” Kramer said.
Bay Area connection
The solution eventually came from the Bay Area.
Early last year, Kramer learned that a donor to SOIL also backs the Marin Carbon Project, a group that layers compost on grazing lands and open spaces. By removing carbon from the atmosphere and storing it in soil, the process cuts down on greenhouse gases and spurs plant growth.
John Wick, who runs the Marin Carbon Project, owns a ranch in Nicasio. He and Andersen had been experimenting with compost piles on his property, with the scientist successfully using the PhyloChip to track bacteria’s decomposition.
Kramer got to know Wick and, in turn, Andersen. They realized that Andersen’s invention could be very useful in Haiti.
There was one problem: The PhyloChip requires DNA that’s been extracted from a sample, and SOIL’s staff had no idea how to extract DNA.
So last month, Andersen and Gabrielle Pecora, a colleague from Lawrence Berkeley National Laboratory, flew to Port-au-Prince. They brought DNA-extraction kits that fit on a desk – a mini lab. In a dusty office with unstable electricity, they spent two weeks training the nonprofit’s staff how to extract DNA from one-fourth of a gram of compost.
“We could take this cutting-edge technology from Berkeley and use it in Haiti – that was really amazing for all of us,” Kramer said.
The SOIL team is now gathering DNA to send to Berkeley, where Andersen will analyze it. With the PhyloChip, Andersen estimates that a pile of compost needs to be monitored for up to six months until it can be safely used, lopping at least three months off the process.
“Haiti is a ripe situation for this because the soil has been completely degraded,” Andersen said. “The compost actually adds nutrients back to the soil and makes it more into its natural state.”
Port-au-Prince may not seem to have much in common with Marin County, one of the wealthiest communities in the United States.
But waste treatment is somewhat of a problem in the seaside enclave of Bolinas. This isolated town of 1,620, an hour north of San Francisco, draws its water from a single creek – although recent droughts have forced it to turn to its small reservoir at times.
In Bolinas, every drop matters. Since 1971, the town has had a moratorium on water meters, which are required to build a house and hook up to the local water system. During a 2009 dry spell, the town imposed a strict limit on water use: Each household could use no more than 150 gallons a day. That rule has since been lifted, but residents remain aware that every toilet flush uses water that could otherwise go toward, say, a shower.
Another problem is the toilets themselves. Homes in downtown Bolinas are hooked up to the town’s sewage treatment system. But the vast majority of houses in the community funnel waste into individual septic tanks, which only last three or so decades. If they fail, they can leak into the ground and they are costly to replace: about $60,000 for a typical household.
By the end of this year, Andersen and Wick plan to start a pilot project that might ease Bolinas’ water shortage, produce plenty of fertilizer, and, as Wick put it, “establish whether it’s a good idea or not in the real world.”
In 20 homes, they will install vacuum-type toilets that will separate water from the septic system. The water, free of pathogens, will be quickly recycled and reused for irrigation, and all waste will be sent into an outdoor vault.
The waste will be picked up every month by septic pumping trucks, emptied at a central composting site and mixed with organic waste. Andersen will monitor the bacterial decomposition until the compost is deemed safe and reused, possibly as fertilizer.
Cut water use 60%
Wick estimates that homes that use this new system could reduce water use by as much as 60 percent. Each toilet will cost around $4,000, he said.
“We’re always looking for ways to save water,” said Don Smith, who is on the board of directors for Bolinas’ public utility district. “This project offers that opportunity, as well as turning a waste product into a resource.”
State and county regulators have approved the pilot project, and there is talk of expanding it to elsewhere in the region. Andersen and Wick have gotten interest from the city of San Francisco, where a back-up plan would be needed were the sewage system to fail during a disaster, as well as the Golden Gate National Recreation Area, where dog poop perpetually abounds.
Andersen hopes his work will eventually help preserve the environment and improve health around the world. And on a more personal note, his international research has reminded him to appreciate the luxuries of home.
“What I’m really grateful for now,” he admitted, “is just having a place to go to the bathroom.”
Online: Learn more about the project at www.thermopileproject.com.