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Compost - Can It Recycle Our Drugs?

A half-mile down the dusty road of a northern California ranch stands a large, black rectangle, silhouetted against the afternoon sun. Under a black water-resistant cover sit nine of the most sophisticated compost piles on earth. They’re squeezed together with large hay bales. Buried inside are moisture and gas sensors, thermometers, air ventilators, and strangely, lots of prescription drugs.

This is the site of an experiment by Gary Andersen, a researcher at the Lawrence Berkeley National Lab. With prescription drugs and antibiotics increasingly appearing in our drinking water or taken up by plants, Andersen wants to know whether the same tiny microorganisms that chew up your coffee grounds and apple cores, can also be used to destroy drugs so they don’t wind up in our environment.

Andersen’s office is perched above the University of California, Berkeley campus on a hillside at the Lawrence Berkeley National Lab. The government-funded lab is better known as the home of super-computers and subatomic particle research, than studies about the potential benefits of compost. Andersen, who resembles a slightly older version of comedian Steve Carell, is a senior scientist here, and the head of the lab’s Ecology Department.

Several years ago, Andersen was studying water quality in Marin County, north of San Francisco. Marin is home to a host of dairies and ranches, and Andersen was studying sewage pollution from livestock and community septic systems on California beaches when he began wondering: was there another way to dispose of these pesky sewage outflows? Then the idea of compost came up.

“It was always in the back of my mind,” Andersen said. But, as a scientist at a respected research institution, he worried that focusing on compost would be the seen as “some boring old thing that your grandfather used to do.” But his curiosity prevailed and he launched the study. “We started looking into it and it started to make a lot of sense.”

Using compost to break down livestock and human waste quickly brought up the question of pharmaceuticals and antibiotics—the drugs we take when we get sick and the ones some farmers feed cows, chickens, and pigs to make them grow bigger and stay healthy. As a water researcher, Andersen knew that pharmaceuticals pose a major challenge at wastewater treatment facilities. After they’ve gone through our bodies and been flushed down the drain, they end up at treatment plants where, he says, “they go through relatively unscathed.” From there, pharmaceuticals wind up in creeks, rivers, and oceans where they get consumed by fish, shellfish, and bottom-dwelling marine creatures.

Having these drugs in our environment also poses a problem by increasing antibiotic resistance. When they pass through our bodies or our livestock, and cycle out into the environment in small doses, the bacteria they’re meant to kill can start to develop resistance. Andersen knew microbes were used for bioremediation to break down spills of oil, solvents, or pesticides. But there was little research to show if the microbes in compost could degrade these chemicals from drugs. Could it be done?

At his research site, Andersen pushes back the thick black cover shielding the compost piles that lay beneath. He grabs a string that disappears into the loose woody mixture and, with a slow tug, pulls out a black mesh bag the size of a soccer ball. Inside, he had mixed compost with the equivalent of about 500 pills of dissolved ibuprofen. In an adjacent pile he’s done the same with ciprofloxacin, a common antibiotic. According to Anderson these are two of the most commonly prescribed and most problematic compounds found at wastewater treatment plants.

While a compost pile like Andersen’s may appear anything but exciting, under the right conditions it will be alive with trillions of tiny microorganisms–bacteria, fungi, and actinomycetes. A tablespoon of compost can hold billions of them, in a frenzy of consumption, birth, and death. Feed them the right nutrients and they can turn your food scraps into a soil-like substance in a matter of weeks. The energy given off from one of these tiny organisms is undetectable, but together they break chemical bonds and release energy in the form of heat.

The compost pile where Andersen is now up to his elbows has passed the hot stage, but when they’re really cooking, he says, it will get up to 130 degrees Fahrenheit. Andersen is using the sensors and instruments to optimize these aerobic conditions to create a super-charged compost pile, and in the process, trick those trillions of microorganisms into doing his dirty work for him.

Compost microbes may not typically be attracted to chemical drugs, but in the right environment, that can change. “Say you’re a kid,” Andersen says, “and you have a whole bunch of Snickers bars.” For every thousand pieces of candy, you have a sprig of broccoli, he continues. Have those kids play all day long, until they’re ravenous, and then unleash them on the bounty of candy. They won’t take the time to separate out a few pieces of broccoli. Thus the broccoli, or in this case the drugs, are broken down and eaten by a trillion microorganisms. At the same time, the resulting heat is enough to kill pathogens carried in human and animal waste. Just like our bodies try to kill a virus by running a fever, the heat generated in the compost piles appears to be enough to kill fecal-borne pathogens.

So what could Andersen’s research mean for the drugs in our environment today? First, it has the potential to get rid of a lot of expired medications. The Lawrence Berkeley National Lab is located in Alameda County. Each year, through the county’s drug disposal programs, residents bring in a whopping seven tons of prescription drugs and the only legal way to get rid of them is to burn them up. That’s better than having them leaking out into San Francisco Bay, but because incinerators aren’t allowed in the county, the drugs are currently shipped out of state to one of several commercial incinerators, further increasing their greenhouse gas footprint than if they were burned up locally.

Secondly, Andersen’s work could simply create a lot more food-grade compost, a resource that’s in demand from farmers, and which could provide an alternative to chemical fertilizers. Right now, there are strict rules about using the treated human waste that comes out of wastewater treatment facilities (called biosolids), meaning only around half of the biosolids we produce get reused. And while none of those rules appear to regulate antibiotic residue, specifically, it is a concern. A 2014 study found that crops treated with un-composted biosolids contained genes associated with antibiotic resistance. If wide-scale composting were done, it could destroy the drugs and be a solution to putting more recycled waste to use.

Similarly, animal waste from concentrated animal feeding operations (CAFOs) is frequently contained in holding ponds and applied raw to fields where it can leach into water systems. While a portion of the organic fertilizers used on farms comes from animal waste that is heat-dried and pasteurized to kill pathogens, that process requires energy and emits greenhouse gases at a much higher rate than the composting process does. If Andersen can prove that composting can safely kill pathogens and destroy drugs, it could dramatically increase the stock of available compost, which is also better for the soil than pasteurized fertilizer.

So far Andersen’s study has been in the pilot phase, but the results are promising. “Safety is the number one issue,” he says. The challenge of seeing if he can destroy the excess drugs in our environment is a scientific one. But it’s more of a mental game to convince people of all the benefits that can come from a word as dirty as compost.

Source:, Erik Neumann, 6-01-16 

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