Figure 1.

TA-degrading laboratory-scale anaerobic hybrid bioreactor. (a) Schematic of the laboratory-scale anaerobic TA-degrading hybrid reactor operated with a temperature gradient from ∼46 °C at the bottom to 50 °C in the upper zone. Inserts illustrate freshly grown biofilm biomass on the surface of the media after 2 and 11months of enrichment; and (b) performance of the reactor over 480-day operation. Under the initial operational conditions (that is, TA-loading rate of 0.70–0.78 gTA/d.l, and hydraulic retention time (HRT) of 4 days), TA removal efficiency was gradually improved to 72.7% by day 124. By shortening the HRT (3 d on day 127, 2 d on day 168 and then to 1.5 d on day 182) and increasing the TA loading concentration (to 3.2 g on day 364), the TA loading rate was increased to 2.13 gTA/d.l by day 364. Concurrently, the TA removal efficiency increased over the operation period reaching a 99% removal efficiency by day 308. During the entire operation no sulfate reduction activity was detected. Samples were removed at the indicated time points (arrows) and the genomic DNA was extracted for 16S rRNA clone library construction and metagenomics analysis.