HoSt has started the construction of a Thermal Pressure Hydrolysis (TPH) demo plant for sewage sludge at the wastewater treatment plant in Echten. With this technology, sewage sludge is pre-treated at high pressure and temperature with the aim of improving the biogas production and the dewaterability. Important goals are to increase efficiency, achieve cost benefits and generating additional energy. The project is in collaboration with Water Board Reest and Wieden. In 2012, HoSt built a thermophilic digestion plant in Echten.
HoSt has used a similar technique in biogas plants in the Netherlands and Romania in order to comply with EU hygiene regulations. In these installations, it was found that the biogas production increased. In laboratory tests, which are conducted by HoSt, this also proved to be the case for the application of sewage sludge. With the demo plant at the WWTP in Echten HoSt wants to demonstrate that this technique is also suitable for treatment of sewage sludge on a larger scale.
In the demo plant, sewage sludge is brought under pressure and to a temperature of 160 degrees with the use of steam. With the TPH technique, persistent structures like cells in sludge are degraded. After the pre-treatment the sludge goes to the digesters. Here, the bacteria can break down more organic matter, which leads to a higher biogas production. Also, the dewaterability of the sludge is improved which leads to fewer disposal costs. After the initial trial period, the plant will be operated for a long time during a joint measurement program to measure the effects on the existing digestion plant. The plant will treat a part (50%) of the total sewage sludge.
On Monday, February 9th the main components were installed. The piping, control and cables will be installed in the upcoming weeks. It is expected that the plant will be operational in March 2015.
Both HoSt as Water Board Reest en Wieden face the results with great confidence. Water Board Reest en Wieden intends to take over the demo plant and to build a permanent plant if the results are positive. The construction of the demo installation is made possible by Water Board Reest en Wieden, the Netherlands Enterprise Agency and the European Interreg program.