Читать книгу Introduction to Desalination - Louis Theodore - Страница 58

1 The suspended particulate concentration in a brackish water source has been determined to be 27.6 mg/L. Convert this value to units of µg/L, g/L, lb/ft3, and lb/gal.

2 As part of a plant’s proposed desalination process cold seawater is mixed with recycled water from a dehumidifier (D), and the mixture then passes through a waste heat boiler (W), which uses air (A) as the heat transfer medium. The hot air and water mixture then pass through a humidifier (H), in which humid air is generated and then passed through the dehumidifier (D) and condensed to form potable water. Prepare a simplified process flow diagram for this process.

3 Precision and accuracy are two terms used to describe measurements and measurement error. Discuss the difference between these two terms in the context of quantitative parameter measurements.

4 A common English volumetric flowrate unit in water and wastewater treatment applications in the United States is million gallons per day, MGD. A desalination plant is being designed for an average flow of 25 MGD. Determine the plant’s capacity in other common volumetric flow units shown in Table 3.4 of gpm, cfs, and m3/d.

5 The concentration of many organic chemicals at which they are potentially toxic or hazardous to human health or the environment is often very low. Many emerging contaminants, for example PFAS (per- and polyfluoroalkyl substances) are very persistent in the environment and in the human body, and there is evidence that exposure to PFAS can lead to adverse human health effects. The drinking water health advisory for two of these PFAS compounds, PFOA and PFOS, is 70 parts/trillion or 70 ng/L. For these two PFAS compounds, determine the following: (1) what is their daily dose at the health advisory limit if the average adult water consumption rate is 1 L/d? (2) if a desalination plant is treating combined brackish water and recharged treated wastewater at a ratio of 50 to 1 on a volume basis, the concentration of PFOA + PFOS in the treated wastewater is 8 ng/L, and the plant is expected to provide 98% PFAS removal, what is the margin of exposure (MOE = NOEL/Actual Dose, g/d) if the health advisory limit dose from (1) is assumed to be the no-observed-adverse-effect level (NOEL)? (3) If the MOE is recommended to be > 100, comment on the MOE for this facility and indicate any corrective action or modified operating conditions that should be implemented to ensure the safety of this produced water supply.