On the barrier and nature of [1.2]-hydrogen migrations in HCN/HNC and their cation radicals

The Science of Nature -     

Source identification of PCDD/Fs in a sewage treatment plant of a German village

The PCDD/F levels in the sewage sludge of a village in North-East Germany were substantially above the limit of 100 pg I-TEq/g for sludge applied to land. A study was initiated to identify the PCDD/F sources in the sewage of this treatment plant. It was found that the PCDD/F contamination entered the plant through the faecal inlet, where the content of faecal storage tanks was emptied into the treatment plant. The isomeric patterns of the higher chlorinated homologues were similar to that of PCP, while incineration showed some influence on the lower chlorinated homologues. Cluster analysis revealed a profile similar to that of PCP.     

Umweltdatenbanken bei STN International — ihre Nutzung in der Praxis

Der Beitrag umfa?t eine übersicht über die Entwicklung wesentlicher Segmente des in Deutschland und international zug?nglichen Angebots an Umweltdatenbanken. Anschlie?end werden wichtige Umweltdatenbanken im Angebot von STN International dargestellt. Anhand ausgew?hlter Beispiele aus der Recherchepraxis werden schlie?lich Ablauf (Stufen der Vorbereitung, Durchführung und Nachbereitung) sowie Ergebnisse der Online-Recherche in wichtigen STN-Umweltdatenbanken dargestellt.     

Toward a high-rate enhanced biological phosphorus removal process in a membrane-assisted bioreactor.

A membrane enhanced biological phosphorus removal (MEBPR) process was studied to determine the impact of hydraulic retention time (HRT) and solids retention time (SRT) on the removal of chemical oxygen demand (COD), nitrogen, and phosphorus from municipal wastewater. The MEBPR process was capable of delivering complete nitrification independent of the prevailing operating conditions, whereas a significant improvement in COD removal efficiency was observed at longer SRTs. In the absence of carbon-limiting conditions, the MEBPR process was able to achieve low phosphorus concentrations in the effluent at increasingly higher hydraulic loads, with the lowest HRT being 5 hours. The MEBPR process was also able to maintain optimal phosphorus removal when the SRT was increased from 12 to 20 days. However, at higher suspended solids concentrations, a substantial increase was observed in carbon utilization per unit mass of phosphorus removed from the influent. These results offer critical insights to the application of membrane technology for biological nutrient removal systems.