Versatile energy generation from sewage sludge

water treatment plant

A Lausanne-based start-up has developed a system that uses sewage sludge to convert 99% of all organic waste into reusable products such as fertiliser, renewable gas and minerals.

For a long time, sewage sludge from wastewater treatment plants was disposed of directly as fertiliser. Although sewage sludge contains plant nutrients such as phosphorus and nitrogen, it also contains a whole range of pollutants and pathogens from industry, commerce, and private households. Due to these major concerns, Switzerland banned the use of sewage sludge in agriculture back in 2023.

Capturing the true value of waste products

Until recently, there was no practicable method for recovering phosphorus from wastewater streams so that sewage sludge could be used as fertiliser – it had to be incinerated instead. In 2015, engineers at the EPFL in Lausanne began designing a system capable of this, which has now resulted in the TreaTech spin-off. Thanks to a technology developed at the Paul Scherrer Institute, the TreaTech system can also produce biogas, salts and minerals from wastewater. This is possible with the help of hydrothermal gasification (HTG).

Our system can recover sludge directly from wastewater treatment plants without the need for drying or other pre-treatment

Fréderic Juillard, CEO and founder of TreaTech

A circular way of processing waste

By converting 99% of the organic carbon in any waste product into pollutant-free gas, it is possible to power the entire waste treatment process in a circular way and to replace fossil fuels. This circular economy is further supported by recovering minerals that can be transformed into fertiliser or clean water. The water can then also be reused on or off site, creating a closed-loop waste treatment solution.

According to the company, the technology has been tested in wastewater-treatment plants in Switzerland and France and is now being used by various clients. Furthermore, the technology has also been validated with more than 20 different industrial feedstocks including residues from monomer production, plastic and paint. With the help of a recent series A financing round of over CHF 9 billion, the technology advancements and expansion of the customer base can proceed at an even faster rate.

Website of TreaTech