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The reverse osmosis performance in removing nickel ions from artificial wastewater was experimentally and mathematically assessed. The impact of temperature, pressure, feed concentration, and feed flow rate on the permeate flux and Ni (II) rejection % were studied. Experiments were conducted using a SEPA CF042 Membrane Test Skid-TFC BW30XFR with applied pressures of 10, 20, 30, and 40 bar and feed concentrations of 25, 50, 100, and 150 ppm with varying operating temperatures of 25, 35, and 45 °C, while the feed flow rate was changed between 2, 3.2, and 4.4 L/min. The permeate flux and the Ni (II) removal % were directly proportional to the feed temperature and operating pressure, but inversely proportional to the feed concentration, where the permeate flux increased by 49% when the temperature was raised from 25 to 45 °C, while the Ni (II) removal % slightly increased by 4%. In addition, the permeate flux increased by 188% and the Ni (II) removal % increased to 95.19% when the pressure was raised from 10 to 40 bar. The feed flow rate, on the other hand, had a negligible influence on the permeate flux and Ni (II) removal %. The temperature correction factor (TCF) was determined to be directly proportional to the feed temperature, but inversely proportional to the operating pressure; nevertheless, the TCF was unaffected either by the feed flow rate or the feed concentration. Based on the experimental data, mathematical models were generated for both the permeate flux and nickel removal %. The results showed that both models matched the experimental data well.

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Cellulose contributes approximately one third of the influent suspended solids to wastewater treatment plants and is a key target for resource recovery. This study investigated the temperature impact on biological aerobic degradation of cellulose in laboratory-scale sequencing batch reactors (SBR) at four different temperatures (10-33 °C) and two different solids retention times (SRT) of 15 days and 3 days. The degradation efficiency of cellulose was observed to increase with temperature and was slightly dependent on SRT (80%-90% at an SRT of 15 days, and 78%-85% at an SRT of 3 days). Hydrolysis followed 1st order kinetics, rather than the biomass dependent Contois kinetics (default in the activated sludge models), with a hydrolysis coefficient at 20 °C of 1.14 ± 0.01 day-1.

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PURPOSE: Previous studies in the literature have measured an altitude effect for low-energy brachytherapy seeds; a correction factor applied in addition to PTP to account for the breakdown of Bragg-Gray cavity theory at low energies in well-type ionization chambers. In clinical practice, many centers use altitude correction factors that are not seed-model-specific. The purpose of this work is to present altitude correction factors for several seed models without documented factors in the literature. METHODS: An in-house constructed pressure vessel was used with a well-type ionization chamber to measure the air-kerma strength of the IsoAid Advantage (Pd-103), Theragenics AgX100 (I-125), and Nucletron selectSeed (I-125) at a pressure range representative of those encountered worldwide. The TheraSeed 200 (Pd-103) was also measured for comparison to the originally published correction factor for validation of the experimental process. When correction factors derived in this work were within experimental uncertainties of those published, no new correction factors were proposed. RESULTS: The three seed models measured herein all demonstrated a similar response to change in pressure as previously documented in the literature with the HDR 1000 Plus well-type ionization chamber. Correction factors of the functional form PA=k1(P[torr])k2, consistent with those previously published, were found to be appropriate for these seed models. A new correction factor is proposed for the Theragenics AgX100 and Nucletron selectSeed (k1  = 0.0417, k2  = 0.479). The IsoAid Advantage, however, agreed to within uncertainty with the published altitude correction factor for the TheraSeed 200; thus the application of the same correction factor is appropriate (k1  = 0.0241, k2  = 0.562). CONCLUSIONS: This work presents altitude correction factors for three permanent implant brachytherapy seed models in clinical use. This will allow clinics to utilize model-specific factors, reducing systematic errors in their air-kerma strength verifications.

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