Water minimum required concentration

Table F. Minimum required concentration for softened water intended for human consumption...

The minimum mass concentration of oxygen required for fish life is 4 mg-L. (a) Assume the density of lake water to be... 

Since the formulation of the constraints has been presented in detail in Section 4.3 using, only the new constraints will be presented in this section. The new constraints were necessitated by the existence of operations C and E for which the contaminant mass load is zero as aforementioned. Without any modifications in the presented mathematical formulations for scenarios 1 and 3, i.e. fixed outlet concentration, this condition would suggest that there is no need for the utilization of water in operations C and E (see constraints (4.3)). However, water is required in these operations for polishing purposes, although this is not associated with any contaminant removal. The minimum amount of water required in these operations is 300 kg. Therefore, the following new constraints is added to the mathematical formulations for scenarios 1 and 3. 

In concentration interval (200 100 ppm), only process 1 exists, Fig. 12.3. Targeting in this concentration interval is shown in Fig. 12.6. The total amount of water required is 100 t at a concentration of 200 ppm. Since 102.5 t of water at a concentration of 200 ppm is available for reuse from the previous interval, no fresh water is required in this interval. This eventually sets 200 ppm as the pinch concentration, i.e. the concentration beyond which the water target does not change. The total amount of wastewater generated from processes is 102.5 t, which is the minimum wastewater target. 

The minimum mass concentration of oxygen required for fish life is 4 mg-L-1. (a) Assuming the density of lake water to be 1.00 g-mL 1, express this concentration in parts per million by mass, mg-kg L (b) What is the minimum partial pressure of 02 that would supply the minimum mass concentration of oxygen in water in order to support fish life at 20°C (see Table 8.5) (c) What is the minimum atmospheric pressure that would give this partial pressure, assuming that oxygen exerts about 21% of the atmospheric pressure ... 

At a sea salt concentration totaling 3.5 wt%, using the thermodynamic data of Dholabhai et al. (1991) in Chapter 6, a pressure of 4.364 MPa (a minimum seawater depth of 436 m—about 55 m deeper than in pure water) is required to stabilize hydrates at 277 K. Further corrections to the phase boundary are required considering effects of (1) hydrocarbons other than methane, (2) salt concentrations other than 3.5 wt%, and (3) sediment pores or capillary pressure, as indicated in Chapter 5. 

P18.5 Sea water contains approximately 26,000 parts per million of dissolved NaCl, plus smaller amounts of other solutes, principally in the form of salts containing Mg2+, K+, Cl", Br, SO4-, and CO2-. In a water purification procedure, a reverse-osmosis process is used, in which half of the water is removed as pure water, leaving a concentrate that has twice the concentration of NaCl. Calculate the minimum work required to obtain a metric ton (103 kg) of pure water. Ignoring the impurities, the process is... 

The acetone concentration in an effluent air stream is to be reduced from 1% mole to 0.05% mole by scrubbing with water in a countercurrent absorber. Assuming Henry s law holds at these concentrations, and that it may be expressed as T = 2.45X, where X and Y are equilibrium acetone mole fractions in the liquid and gas, calculate the minimum water rate required for an air-acetone mixture rate of 100 kmol/h. How many equilibrium stages would be required if the water rate is twice the minimum What is the concentration of acetone in the water leaving the absorber Assume water vapor in the gas and air dissolved in the water are negligible. Solve this problem graphically. 

MPa, compressive strength 245-303 MPa, water sorption 0.5-0.7/cm ) considerably exceeded the minimum requirement of the specification for dental composite resins (37). If low concentrations are employed in the formulations especially with DEAPAA as accelerator, the cured composites are nearly colorless. No perceptible change occurs in the color of the specimens containing a UV absorber after 24 hours exposure to a UV light source. Because of the excellent overall physical properties, nearly colorless appearance and the potentially better biocompatibility, compositions using these accelerators should yield improved restoratives. 

In many ground-water investigations, more data are collected than the minimum required to describe the carbonate system. Measurements of dissolved CO2 concentrations are often made as part of the suite of analyses for all dissolved gases or by base titrations in the field. Measurements of total dissolved carbonate concentrations made by precipitation of solid carbonate or evolution of CO2 following acidification may also be available. With such redundant analytical data, the internal consistency of all the carbonate data can be tested. 

A vessel 1.0 m in diameter is to be used for stripping chloroform from water by sparging with air at 298 K. The water will flow continuously downward at the rate of 10.0 kg/s at 298 K. The water contains 240 pg/L of chloroform. It is desired to remove 90% of the chloroform in the water using an airflow that is 50% higher than the minimum required. At these low concentrations, chloroform-water solutions follow Henry s law (yj = mx) with m = 220. The sparger is in the form of a ring located at the bottom of the vessel, 50 cm in diameter, containing 90 orifices, each 3 mm in diameter. Estimate the depth of the water column required to achieve the specified 90% removal efficiency. Estimate the power required to operate the air compressor, if the mechanical efficiency of the system is 60%. 

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