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At least 433 records · Page 24

Metagenomes and Metagenome-Assembled Genomes from Microbial Communities in the Hamptons Road Sanitary District (HRSD) Biological Nutrient Removal Pilot Plant Operated with High and Low Dissolved Oxygen Conditions

In this study, we aimed to evaluate BNR and investigate microbial community changes when the DO is reduced in the aerated portions of wastewater treatment trains. We present a dataset of metagenomes obtained from activated sludge collected from the Hamptons Road Sanitary District treatment plant at the beginning of operation, when the DO was high, and at the end of operation, when the DO was low

dissolved oxgyen↗

The Characterization of Dissolved Organic Matter in Reclaimed Water and Its Influence on Copper Toxicity

Water samples were collected from five phases of treatment in a municipal sewage reclaimed water plant and the DOM was characterized. Results indicated that the components and properties of DOM varied notably with sequential treatments, such as the fluorescence intensity, the molecular weight and the total acidity. Meanwhile the accumulation of Cu in Daphnia magna was analyzed following exposure to samples spiked with 50 µg/L copper, which were decreased by the presence of DOM in those water samples. Furthermore, this study found significant associations between fluorescence intensity and Cu accumulation (r{sup 2} = 0.778, p < 0.05), while increased total acidity was found to enhance the unit total organic carbon-Cu accumulation (r{sup 2} = 0.979, p < 0.01). This study provides useful information on the safety and effective management of reclaimed water as a potential water resource.

54 ENVIRONMENTAL SCIENCES↗

Fundamentals of alkali-silica gel formation and swelling: Condensation under influence of dissolved salts

The current theory of ASR gel formation in concrete between silicic acid anions with cations and is unable to explain the differences in concentration required for gel formation between e.g. potassium and sodium or the effect of calcium on the gel formation. In this paper, a new gelation mechanism is explained by means of a condensation between silicic acid anions. The role of salts on the ASR gel formation and gel time is described by their charge screening capacity of the silicic acid, resulting in the decreasing concentration range for gelation: Ca < Mg < Cs < Rb < K < Na < Li. A Cation Gelling Strength (CGS) is defined to assess the cation strength when different cations are present. Silica gel formation will moreover in many cases form a calcium silica precipitate rather than a gel that will be difficult to distinguish from CSH formed during hydration.

36 MATERIALS SCIENCE↗