Robot pig drives German drying plants

By STEFAN NICOLA, UPI Germany Correspondent

FILDERSTADT-BERNHAUSEN, Germany, March 11 (UPI) -- Pig Balthazar draggles and ploughs through the mud all day and still does not need to be fed -- Balthazar is an electrical pig built by German company Thermo-System GmbH, the world leader in solar sludge-drying systems.

Some 100 electrical pigs are operating all over the world: Each is named and works day and night to reduce sewer sludge disposal costs and protect the environment.


Based in Filderstadt near Stuttgart, Thermo-System was founded in 1997 by four up-and-coming scientists from the University of Hohenheim, after the students developed a cost-effective and environmentally friendly solar drying process, which may solve waste disposal problems of sewage plants all over in the world.

The stainless steel pigs, which resemble child-sized Volkswagen Beetle convertibles, belong to a larger drying system patented by Thermo-System.

The likes of Balthazar work in greenhouse-like sheds, in which the wet sewage sludge is spread for drying. Conventional drying processes burn up non-renewable energy, but Thermo-System harvests the sun's infinite resources to dry the mud.


The sludge absorbs the heat from the solar rays, and an innovative ventilation system based on sensors and microprocessors keeps the air inside the shed warm and dry. In comes the electrical pig, a fully automated robot. With its mixing tools, it turns over and aerates the microbiologically highly active sludge and thus accelerates the drying process and helps prevent rotting. The whole system works fully automatically, uses up very little energy and can be easily maintained.

Tilo Conrad, the company's founder and its head, and two other students built the first electrical pig in his dad's garage some 10 years ago.

"The image of the beetle is not wrong at all: When we developed the pig, we thought: How would a machine look like if it lived in the sludge?"

But why dry the mud in the first place? Containing mostly water, 90 to 95 percent of the wet mud's mass can be done away through the economically friendly drying process.

"Germany alone produces roughly 60 million tons of sewage sludge per year," Conrad, sitting in his spacious office in an industrial district building in Filderstadt-Bernhausen, told United Press International. "Given the fact that it costs between 75 and 100 euros to get rid of 1 ton, communities can save a considerable amount of money."


Sewage sludge used to be deposited or is spread over farmland as fertilizer, but both processes have increasingly come under scrutiny. The sludge, generated in the process of recycling sewage water, may be full of harmful materials, such as germs, hormones or chemical substances.

"After the drying process, the sludge has lost its strong odor, it is virtually free of bacteria and its burning value has increased fourfold," Conrad said. "Imagine 600 tons of sludge that turn into 60 tons -- you need much less fossil fuels to transport that mud and you need much less fossil fuels to burn it."

A small sludge drying system starts at roughly $180,000; the biggest, which can cover a city of 300,000, costs roughly $1.8 million. The company has sold plants to more than 60 locations in Germany, France, Brazil, Australia and Austria.

In the United States, operators of sewage treatment plants in Rogue River, Ore., Riovista, Renn., Discovery Bay, Calif., and Keowee Key, S.C., are already betting on the environmentally friendly drying process.

In South America, Thermo-System's solar wood drying systems are becoming increasingly popular.

Despite double-digit growth numbers and sales of some $4.8 million last year, Thermo-System remains a mid-sized business: Only 20 employees, 11 of who are engineers, work for Conrad.


"I think the main problem is that not many people know of this new technique. It's still a nice market, but we are growing each year as the system is getting better known," Conrad told UPI. "We are especially expecting more business from the new states from Eastern Europe that are joining the European Union. These countries have to bring their environmental technology up to EU standards."

Growing economies in China and India may be a market for the future, but not for now, Conrad said.

"We have had several inquiries from China already, but we are wary of property rights violations. One firm even asked us to send them the plans for the electrical pig. So we are a bit cautious, and won't enter the market there until maybe in some years a real opportunity comes along."


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