This thesis was commissioned by HAMK University of Applied Sciences based on a company commission. The literature part of the thesis analysed the consistencies of different kinds of biowaste. The experimental part examined the production of biogas and methane from biowaste sludge mix and followed the state of the process.

On the basis of the literature part, it could be concluded that the change of seasons did not have as big an effect on biowaste consistency as how the waste was collected. Of the examined biowaste, the biowaste collected separately from canteens was the most homogenous, whereas the mechanically sorted organic fraction of municipal solid waste had the worst quality for biological treatment.

The experimental part of the thesis was carried out by the 200 l pilot reactor situated in HAMK Visamäki unit. The state of the reactor was monitored by the following analyses: pH, alkalinity, volatile fatty acid, ammonium and total nitrogen, chemical oxygen demand, total solid and organic solid. In addition, biogas production and methane concentration were also measured.

In the trial period, the process achieved a balance with the load 2.5 kgVS/m3d. This was verified from the analyses and measurements made from the process in the reactor. With a homogenous input, the production of biogas was ca. 430 l/kgVS and gas methane concentration ca. 60 %. On the grounds of literature, this biogas production was somewhat lower than biogas production from separately collected biowaste. Sewage sludge in the feed decreased biogas production compared to pure biowaste.