Turning waste into water

There are numerous technologies under development dedicated to disassembling human and livestock waste.

One of the most famous is OmniProcessor, financially backed by Bill Gates with a $25 million grant.

Engineered by Janicki Bioenergy in Seattle, the initial OmniProcessor concept impressed Gates to the extent that he pumped $25 million into the project, as another step toward solving human waste contamination and health problems in developing countries.

Related story: Dairy farm gets manure management makeover

That first OmniProcessor was slated to manage organic dairy slurry on a new 5,000 cow organic dairy farm in Indiana, being constructed by a large Texas organic dairy operation known as Natural Prairie Farms.

In the following blog, Gates describes his experience when touring a human sewage OmniProcessor facility in Africa.

The blog says, “I watched piles of feces go up the conveyer belt and drop into a large bin. They made their way through the machine, getting boiled and treated. A few minutes later I took a long taste of the end result: a glass of delicious drinking water.

“The occasion was a tour of a facility that burns human waste and produces water and electricity, plus a little ash. I have visited lots of similar sites, like power plants and paper mills, so when I heard about this one I was eager to check it out. It’s part of the Gates Foundation’s effort to improve sanitation in poor countries.

“The water tasted as good as any I’ve had out of a bottle. Having studied the engineering behind it, I would happily drink it every day. It’s that safe.”

Gates states in his blog that at least two billion people in the world use latrines that aren’t properly drained. Others simply defecate out in the open. The waste contaminates drinking water for millions.

Dairy slurry goes into the front end of the OmniProcessor. Pure potable water comes out the back end. Having a glass of freshly brewed water, Bill Gates says he’s confident the technology holds great promise for developing third world nations. | Natural Prairie Farms photo

His blog says diseases caused by poor sanitation kill 700,000 children each year and they prevent many more from fully developing mentally and physically.

He states that if we can develop safe, affordable ways to deal with human waste, we can prevent many of those deaths and help more children grow up healthy.

Obviously, if there’s valid technology to process human waste, it can also be applied to dairy and hog slurry, says engineer/entrepreneur Peter Janicki.

He says his system uses something called mechanical vapor compression, a thermal process that kills pathogens.

The patented technology removes ammonia from the liquid stream, creating liquid fertilizer. The remaining solids are dried and turned into organic soil nutrients. This technology can treat effluents that are not effective or viable to treat by conventional techniques.

It only looks complicated because it is. Slurry is pumped in at one end of the facility. Depending on each facility’s setup, the end products are a mix of dry or liquid fertilizer, electricity and potable water. The De Jong plant was made by Sedron. | Natural Prairie Farms photo

A mechanical vapor recompression vacuum evaporator is a lot of words to describe his device that treats waste effluent at a low energy cost.

High efficiency is created by a rotary blower, or a steam compressor, which increases heat from the mechanical action of volumetric compression. A small amount of energy is used to power the compressor.

The compressed steam heats the effluent so it evaporates and consequently condenses the vapor to produce distilled water. Vacuum evaporators extract high quality water from concentrated contaminant by the application of thermal energy.

The Janicki OmniProcessor (J-OP) waste treatment plant employs three well-proven, industry-standard processes in a single package.

  • Solid fuel combustion — Fecal sludge, biosolids and other wet waste streams enter a dryer where moisture is removed. The dried solid waste is now a fuel that’s burned in a combustion chamber, reducing the solids to dry ash.
  • Steam power generation — Heat generated in the combustion chamber transfers to a boiler to generate high-pressure, high-temperature steam. This steam goes to a steam expander such as a steam engine or steam turbine. These motors turn a generator to produce electricity used to power the whole J-OP system. There is often surplus electricity to be sold back to the utility grid or used locally. Exhaust steam from the expander travels back to the heat exchanger surfaces of the dryer to provide heat to dry incoming wet waste. In transferring heat back, exhaust steam condenses back to water and is pumped back to the boiler.
  • Water treatment — Water evaporated from the wet waste is captured. This vapor is filtered before being condensed back to water. If desired, this water can then be treated all the way to clean drinking water standards, or be used for other recycled or reuse water applications. Useful heat can also be captured from the condenser to be used for a variety of purposes.

Janicki made further changes to his processor and changed the company name to Sedron and the process to Varcor.

The Varcor website says the system is based on the well-proven process called mechanical vapor recompression. The solid and liquid fractions are separated through thermal evaporation and the resulting vapor is sent to a compressor where it undergoes mechanical recompression. The highly compressed vapor is used as the heat source for the evaporation process. The low boiling point constituents such as ammonia are separated.

Varcor is flexible, modular and scalable to different contexts.

It can serve populations ranging from community-scale to city-scale in developing and developed countries. With minor adjustments, output can be optimized in response to market needs. In locations where the value of electricity is high, power production can increase.

Conversely, in markets where clean water is especially valuable, water production can be prioritized to increase the quantity of that output. This optimization can be done on the fly and does not require design or hardware changes on the equipment.

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