Abstract
More and more effort is being put in the utilization of bio-solids. Bio-solids can be an important source for useful products like fertilizers and biogas. DMT has been developing biogas treatment plants for over 20 years following the market developments closely.

Biogas was first seen as a nuisance at e.g. landfills, creating odor problems and methane emissions. A flare is, therefore, a cheap and simple solution. But with time more and more biogas was produced intentional from bio-solids to generate heat and/or energy in a boiler, gas engine or Combined Heat and Power unit (CHP).

The next step is upgrading biogas to natural gas quality to utilize the maximum amount of energy. The “green gas” can be injected in the gas grid or used as vehicle fuel in e.g. cars, busses, ferries and agricultural machinery.   

In this article a presentation is given about the start-up and first results of two biogas upgrading plants. One full-scale plant in Zwolle (NL), where 550Nm³/h of biogas, produced by digesting of bio-solids, is upgraded to natural gas and injected in the national grid. The other plant is a small scale unit in Zalaegerszeg (HU) at a WWTP where 85Nm³/h of biogas is upgraded to over 97% methane concentration and, thereafter, compressed to 220bar. The compressed biogas (CBG) is used as vehicle fuel for the company’s fleet of cars. 

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