PubMed · 10314966
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R R Demers. 1975. Veriflo oxygen controller quality control.. https://pubmed.ncbi.nlm.nih.gov/10314966/
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This paper presents the results of a research aiming at evaluating the effects of storage on wastewater characteristics. Wastewater discharged from the Caltagirone (Eastern Sicily) plant after secondary treatment was stored in an earth reservoir with a capacity of about 25,000 m3 and a depth of 5 m. Wastewater inflow in the reservoir was continuous throughout the experimental activities, while discharge was discontinuous, depending on irrigation demand. Removal efficiency resulted highly influenced by the operation regime of the reservoir and by influent wastewater characteristics. BOD5 and COD removal efficiency was above 50%. Removal efficiency of faecal coliforms, faecal streptococci and Escherichia coli was between 2 and 5 log units. Single and multiple regressions were tested to determine the reservoir design characteristics and operation parameters that most significantly affected water quality changes.
The unexplained occurrence of anoxic phosphorus (P) accumulation has largely hampered modeling of nitrification denitrification biological excess P removal (NDBEPR) systems. The aim of this study was, therefore, to isolate and identify denitrifying-P accumulating heterotrophic bacteria (DPBs) from a NDBEPR system in order to evaluate anoxic P accumulation and the specific mechanisms involved. Results of the study showed various heterotrophic bacteria to be capable of anoxic P accumulation utilising nitrate (NO3) as electron acceptor. While Pseudomonas spp. predominated, Serratia spp. and Vibrio spp. demonstrated the most efficient anoxic P accumulation with 7.10 and 7.29 mgPO4-P/L removal, respectively, at an initial NO3 concentration of 13.54 mgNO3-N/L and P concentration of 16.34 mgPO4-P/L. Weaker DPBs were also identified which were only capable of accumulating small amounts of P at low initial P and NO3 concentrations due to weak denitrification capacity. Anoxic P release was also observed due to the presence of acetate.
The chemistry of technetium in certain high-level nuclear waste (HLW) tanks at the Hanford Site complicates the treatment and vitrification of HLW. A major problem is the presence, in certain tanks, of unidentified, lower-valent technetium species, which are difficult to remove from the waste by current separation processes. Radiolytic reduction of TcO4- in alkaline solutions containing selected organic compounds, approximating the conditions in HLW, was investigated to determine the classes of compounds that can be formed under these conditions. Insoluble TcO2 x xH2O is the primary radiolysis product with the majority of organic compounds investigated, including citrate, dibutyl phosphate, and aminopolycarboxylates. X-ray absorption fine structure (XAFS) measurements show that TcO2 x xH2O has a one-dimensional chain structure consisting of edge-sharing TcO6 octahedra with bridging oxide and trans water ligands. When diols, such as ethylene glycol, are present, only soluble, Tc(IV) alkoxide compounds are produced. The XAFS and UV-visible spectra of these compounds provide evidence for a binuclear structure similar to (H2EDTA)2Tc2(mu-O)2. The properties of the Tc(IV) alkoxide complexes were determined and are consistent with those observed for the soluble, lower-valent technetium complexes that complicate the treatment of HLW at the Hanford site.