Fig. 1.

Sampling of anaerobic digesters in Thuringia (Germany). Seven different facilities with a total of nine reactors were sampled in Schlossvippach, Weimar, Jena (two plants, one of them with three reactors), Schmölln, Rudolstadt, and Saalfeld. Sampling was repeated twice at a 1-week interval, and three replicates were processed (54 samples in total). CD three-stage plant, SS sewage plants, LB leach-bed reactors, S1 plug flow reactor, S2 continuous stirred tank reactor, S3 storage tank for digestion remnants