When energy comes from us
The average person produces around a pound of feces each day, but it all ends up in enormous wastewater treatment plants, which clean the water and dispose of the rest as best they can, either by destroying or landfilling it. Even worse, in areas where flushing systems are unavailable, homeowners construct cesspits and outhouses, where sludge accumulates and must be cleared eventually.
We constantly get rid of waste since it spreads diseases. However, scientists and engineers now claim that we have really been squandering our own waste. This low-cost, entirely renewable, and widely available material, which is regularly created by all 7 billion people on the earth, may be used to grow food, cook meals, fuel cars, and generate electricity when properly recycled. Here are five technologies that are attempting to turn feces into energy but not only.
1. Cooking
Nairobi’s urban areas are so densely populated that there isn’t enough space to build toilets, even the most basic outdoor latrines. As a result, residents relieve themselves into plastic bags and dump them to the side of the road, where they accumulate, spread, and float around when the area is flooded by a strong downpour. This bag phenomenon is called “Kenya’s flying toilets”.
Kenya, on the other hand, has a serious deforestation problem. Because wood is most people’s primary source of energy, they cut down trees and convert them to charcoal, which is used for everything from cooking dinners to drying tea leaves for the country’s tea industry.
Sanivation, a startup, has stepped in to solve both issues with the same material. Sanivation equips low-income households with small porta-potties that collect waste in sanitary containers beneath the toilet seats, which are then collected and taken to a repurposing site by a service team. Lignin, a complex organic polymer derived from the cell walls of the plants we eat, is abundant in human excreta. This lignin converts excrement into a sticky material when heated. More burnable fiber, such as sawdust or agricultural waste, can be added to the sticky mix and shaped and dried into fuel briquettes. According to Sanivation founder Emily Woods, factory demand is extremely large: in their fourth month, they sold 50 tons. “We are only limited by how much we can produce”, she says.
2. Fertilizer
Manually collecting feces and turning it into firewood is unlikely to find a large market in the Western world, but there are other ways to recycle our metabolic waste here. Ajay Singh, an Ontario scientist, noticed a number of big trucks buzzing around his area on a regular basis. The trucks were hauling human excrement, it turned out. Typically, the sewage is dewatered, and the water is purified sufficiently to be released back into the environment but the biosolids remain a problem. Biosolids are frequently disposed of in landfills or burnt, resulting in greenhouse gas emissions. They’re also directed into so-called “lagoons” in some places, which are essentially gigantic cesspits silently seething beneath their PVC covers.
In the sewage sector, biosolids are not well-liked because no one wants them since they’re too gunky, chunky, and stinking to pump or purify like liquid. They are, nevertheless, high in nutrients like nitrogen and phosphorus, which make them great fertilizers.
Singh and a colleague invented a system for blending biosolids into a “sewage smoothie”. They created an industrial-sized mixer that turns the biosolids into a milkshake consistency. They tested with a conventional kitchen blender to test the idea. The blender solves two problems at once, thanks to an ultra-sharp blade that spins at such a high speed, it shreds the bacterial cells in the sludge and it destroys the pathogens, and homogenizes the mixture to the point where it can be pumped into trucks and injected onto farmed soil. Lystek, the name of their startup, now turns biosolids into LysteGro, nutrient-rich health food for plants.
3. Methane
Another kitchen-inspired solution to upcycling feces comes from DC Water, which uses a pressure cooker rather than a blender. The facility employs 24 massive pressure cookers to cook the city’s output for half an hour at 320°F and six times the normal atmospheric pressure you’re experiencing right now. All of the pathogens are killed at the end of this cycle, and the sewage stew is dumped into large concrete tanks known as biodigesters, where a swarm of bacteria digests through the sludge. Then they expel methane as a byproduct of this process, which the firm gathers and burns to power the plant’s electrical turbines.
DC Water produced 1100 tons of biosolids per day but now, bacteria have reduced to around 450 tons per day, with the rest being transformed to gas for green energy production. Some carbon is returned to the earth from which it started: The microorganisms leave behind a black gooey compost at the conclusion of their feast, which is dewatered and dried into Bloom, an organic fertilizer product packaged in neat bags and accessible for purchase by anybody, from farmers to landscapers to gardeners. According to Christopher Peot, director of the resource recovery at DC Water, “There’s no such thing as waste, only wasted resources”.
4. Cheaper energy and fertilizer
A large pressure cooker is beyond reach for most families, but there are smaller and less expensive biodigester solutions. HomeBiogas, an Israeli company, offers inexpensive personal biodigesters that can “digest” food leftovers in the same way. They can also be connected to pump toilets, which flush with manual pumps and so use a lot less water. The digesters, which look like domes, are seeded with microorganisms that degrade biomass and convert it to methane, which is piped to a stove or a hot-water heater via a hose. The digester’s other valuable output, a brown, goopy liquid that can be an effective fertilizer and slowly collects in a bucket, drips out the digester’s back.
According to Yair Teller, one of the company’s founders, HomeBiogas digesters (costing around $600-$700) can give considerable savings in nations where electricity is expensive. Biodigesters could be a source of low-cost organic fertilizer in the United States, where energy is cheap. They could also be beneficial to off-the-grid communities, regardless of their location.
5. Petroleum
Excrement may be used to power almost anything, including vehicles, in addition to kitchen stoves. The Metro Vancouver wastewater treatment plant in British Columbia is putting a novel technology to the test, which transforms sewage into a crude oil-like substance. The complex device’s centerpiece is a silver serpentine pipe developed by the Pacific Northwest National Laboratories (PNNL), one of the US Department of Energy’s labs. The sludge is heated to around 660°F and squashed at 200 times the typical air pressure once it is loaded within the pipe.
These dreadful circumstances, known scientifically as hydrothermal liquefaction (HTL), are similar to those that formed oil and gas deep beneath the world’s seas over millions of years. The sludge does not cook at these temperatures and pressures, but its lengthy organic molecules break down into shorter, smaller carbon compounds, which are the components of oil and gas. The difference is that it takes millions of years to be done naturally, but the PNNL technique only takes 15 minutes to produce a substance with a high economic value.
It still needs to be refined like any other oil, but it helps with sewage disposal and lessens the quantity of the oil that needs to be collected from the soil because we still rely on fossil fuels, according to Paul Kadota, Metro Vancouver’s program manager. The project is still in its early stages, but if it succeeds, Vancouver residents will be able to physically power their automobiles with leftover meals.
Source mentalfloss.com
