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The wastewater from baker's yeast production contains above‐average concentrations of organic pollutants (25 000 mg/L total chemical oxygen demand, TCOD), nutrients (1500 mg/L Ntot, 100 mg/L Ptot) and sulphate (2900 mg/L SO42−). Baker's yeast wastewater with a flow rate of 190 m3/day was treated in a mesophilic anaerobic/anoxic continuous stirred tank reactor (CSTR) system. At the expense of the reduction of trimethylglycine (or betaine‐component of sugar‐beet molasses) to other nitrogen‐containing compounds, it was possible to re‐oxidize the sulphides to elemental sulphur, remove them from the wastewater and increase biogas production. Therefore, the average removal efficiency in the anaerobic/anoxic system was 79% by TCOD, 100% by SO42− in which the concentration of sulphides in the effluent did not exceed 50 mg/L. The application of this combined anaerobic/anoxic system to a full‐scale treatment plant supported biogas production up to 1300 m3/day, and the purification of wastewater was feasible without the use of granular sludge.

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Developing and implementing renewable energy systems such as biogas from anaerobic digestion process (AD), based on national and regional biomass resources, will increase the security of the national energy supply and diminish dependency on imported fuels. For Estonia, the EU Directive for renewable energy targets has been set to 25% by 2020. Data about the municipal biodegradable waste produced in Estonia during 2002-2012 were collected. The subject of the analysis was different types of biodegradable waste from landfills, biodegradable waste from food production companies, sludge from waste treatment plants as well as waste from livestock farms, trade companies, gardens and parks in Estonia. The wastes volumes, qualities, and their energy potential were estimated. The GIS (geographic information systems) model was applied for the spatial planning of biogas stations in Estonia.

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