ABSTRACT
In a 3-year research project, a new approach to forecast biological N2O formation and emission at high-strength reject water treatment has been developed (ASM3/1_N2OISAH). It was calibrated by extensive batch-tests and finally evaluated by long-term measurement campaigns realized at three wastewater treatment plants (WWTPs) with different process configurations for nitrogen removal of reject water. To enable a model application with common full-scale data, the nitritation-connected supplementary processes that are responsible for N2O formation are not depicted in the model. Instead, within the new model approach the N2O formation is linked to the NH4-N oxidation rate by defining specific formation factors [N2O-Nform/NH4-Nox], depending on the concentrations of NO2 and O2 as well as the NH4 load. A comparison between the measured and the modeled N2O concentrations in the liquid and gas phase at the full-scale treatment plants prove the ability of the proposed modelling approach to represent the observed trends of N2O formation, emission and reduction using the standard parameter set of kinetics and formation factors. Thus, enabling a reliable estimation of the N2O emissions for different operational conditions. The measurements indicate that a formation of N2O by AOB cannot completely be avoided. However, a considerable reduction of the formed N2O was observed in an anoxic environment. Applying the model, operational settings and mitigation strategies can now be identified without extensive measurement campaigns. For further enhancement of the model, first results for kinetics of N2O reduction kinetics by denitrification processes were determined in laboratory-scale batch tests.
Subject(s)
Bioreactors , Water Purification , Denitrification , Nitrogen , Nitrous Oxide/analysis , Oxidation-Reduction , WastewaterABSTRACT
In a yeast two-hybrid screen FKBP13, a member of the FK506 Binding Protein (FKBP) family, was detected to interact with the serpin alpha-1-antichymotrypsin (ACT). The specificity of the interaction was confirmed in vitro and by the lack of interaction of ACT with FKBP25 and FKBP52. Mutational analysis of ACT revealed that the entire protein is necessary to interact with FKBP13. ACT but also different unrelated small regions of the ACT protein were able to interact with the smaller FKBP12, demonstrating a rather nonspecific interaction with this immunophilin. Naturally occuring mutants of ACT were able to interact as well. Antitrypsin (AT) closely related to ACT did only interfere with FKBP12 a protein that does presumably not reside in the same cellular compartment with AT and ACT. Both serpins interacted with the unrelated immunophilin cyclophilin A. In conclusion the serpin alpha-1-antichymotrypsin physiologically interacts with the ER-immunophilin FKBP13 and the secreted immunophilin cyclophilin A in vivo whereas alpha-1-antitrypsin might only react with cyclophilin A; both serpins may be controlled thereby in their genuine function.
