Project description:Two-stage two-phase biogas reactor systems consisting each of one batch downflow hydrolysis reactor (HR, vol. 10 L), one process fluid storage tank (vol. 10 L), and one downstream upflow anaerobic filter reactor (AF, vol. 10 L), were operated at mesophilic (M, 37 °C) and thermophilic (T, 55 °C) temperatures and over a period of > 750 d (Figure 1, Additional file 1). For each reactor system and for each process temperature, two replicates were conducted in parallel, denominated further as biological replicates. Further process details were as previously published. Start-up of all fermenters were performed using liquid fermenter material from a biogas plant converting cattle manure in co-digestion with grass and maize silage and other biomass at varying concentrations and at mesophilic temperatures. Silage of perennial ryegrass (Lolium perenne L.) was digested as sole substrate in batches of varying amounts with retention times of 28 d (storage of bale silage at -20 °C, cutting length 3 cm, volatile substances (VS) 32 % of fresh mass (FM), total Kjeldahl nitrogen 7.6 g kgFM-1, NH4+-N 0.7 g kgFM-1, acetic acid 2.6 g kgFM-1, propionic acid < 0.04 g kgFM-1, lactic acid 2.6 g kgFM-1, ethanol 2.2 g kgFM-1, C/N ratio 19.3, chemical oxygen demand (COD) 357.7 g kgFM-1, analysis of chemical properties according to [6]. No spoilage was observed in the silage. Biogas yields were calculated as liters normalized to 0 °C and 1013 hPa (LN) per kilogram volatile substances (kgVS). For chemical analysis, samples were taken from the effluents of HR and AF. For sequencing of 16S rRNA gene amplicon libraries, microbial metagenomes, and microbial metatranscriptomes, samples were taken from the silage digestate in the HR digested for 2 d. At this time point, high AD rates were detected as indicated by the fast increase of volatile fatty acids (VFA), e.g., acetic acid. Sampling was performed at two different organic loading rates (OLR), i.e., batch-fermentation of 500 g (denominated as “low OLR”, samples MOLR500 and TOLR500) and 1,500 g silage (denominated as “increased OLR”, samples MOLR1500 and TOLR1500).
Project description:Heavy metals have been postulated as significant nitrification inhibitor in wastewater treatment plant. The effect of heavy metals such as Cd2+, Cu2+ and Hg2+ to nitrifying bacterium, Nitrosomonas europaea, was studied in pseudo-steady state batch reactor. Under incubation of Nitrosomonas europaea with 1 ?M CdCl2 for 1 hour, transcripts for 66 of 2460 genes were found at high level, yet transcripts of 50 genes were found at low level. Mercury resistance genes (merACDPT) showed 277-fold up regulation. Keywords: cadmium, stress response, global transcription, mercury resistance genes, merA,
Project description:Heavy metals have been postulated as significant nitrification inhibitor in wastewater treatment plant. The effect of heavy metals such as Cd2+, Cu2+ and Hg2+ to nitrifying bacterium, Nitrosomonas europaea, was studied in pseudo-steady state batch reactor. Under incubation of Nitrosomonas europaea with 1 ?M CdCl2 for 1 hour, transcripts for 66 of 2460 genes were found at high level, yet transcripts of 50 genes were found at low level. Mercury resistance genes (merACDPT) showed 277-fold up regulation. Keywords: cadmium, stress response, global transcription, mercury resistance genes, merA, The 1 uM CdCl2 caused more than 50 % inhibition in physiological response for 1 hour incubation. Transcriptional levels of the cells inhibited by cadmium were compared with the cells under control condition.
Project description:Increased replication rates of Chloroflexi that perform dissimilatory nitrogen reduction to ammonium leads to loss of anammox reactor performance
Project description:Our study revealed a synergistic effect between biological nitrogen fixation and current generation by G. sulfurreducens, providing a green nitrogen fixation alternative through shifting the nitrogen fixation field from energy consumption to energy production and having implications for N-deficient wastewater treatment.
Project description:The ammonia-oxidizing bacterium Nitrosomonas europaea has been widely recognized as an important player in the nitrogen cycle as well as one of the most abundant members in microbial communities for the treatment of industrial or sewage wastewater. Its natural metabolic versatility and extraordinary ability to degrade environmental pollutants enable it to thrive under various harsh environmental conditions. This model of N. europaea (iGC535) is the most accurate metabolic model for a nitrifying organism to date, reaching an average prediction accuracy of over 90% under several growth conditions. The manually curated model can predict phenotypes under chemolithotrophic and chemolithoorganotrophic conditions while oxidating methane and wastewater pollutants.
It is the first upload of the model.