Water consumption

The sequence of treatments is illustrated in Figure 4. Water consumption in washing is minimi2ed by using a countercurrent Hquor flow, clean water entering the system at the point where the fiber leaves, and dirty Hquor leaving for chemical recovery at the point where the fiber enters. 

Water loss in operating an HDR faciUty may result from either increased storage within the body of the reservoir or diffusion into the rock body beyond the periphery of the reservoir (38). When a reservoir is created, the joints which are opened immediately fill with water. Micropores or microcracks may fill much more slowly, however. Figure 11 shows water consumption during an extended pressurization experiment at the HDR faciUty operated by the Los Alamos National Laboratory at Fenton Hill, New Mexico. As the microcracks within the reservoir become saturated, the water consumption at a set pressure declines. It does not go to zero because diffusion at the reservoir boundary can never be completely elirninated. Of course, if a reservoir joint should intersect a natural open fault, water losses may be high under any conditions. 

Fig. 11. Water consumption during extended pressurization of an HDR reservoir. The amount of water required to maintain a constant pressure declines with the logarithm of time as the microcracks in the reservoir rock are slowly filled with the pressurized fluid.

Pollution Control in the Bleachery. The quantity of water necessary for bleaching, and consequently the volume of effluents, has been decreased significantly by various schemes for recycle of Hquors, eg, pulp washing using dilute spent Hquors and countercurrent flow. Effort is underway to close bleach plants and further reduce water consumption. 

Food nd W ter Consumption. Measurement of changes in food and water consumption may indicate a toxic potential, and can give guidance on the reason for abnormal body weight gains. 

Water Consumption and Effluent Characterization. Another advantage of CGCC power generation is derived from lower water requirements. Because more than half of the power generated in a CGCC plant comes from the gas turbine, the water requirement is only 70—80% of that required for a coal-fired power plant, where all of the power is generated from steam turbines. 

While process design and equipment specification are usually performed prior to the implementation of the process, optimization of operating conditions is carried out monthly, weekly, daily, hourly, or even eveiy minute. Optimization of plant operations determines the set points for each unit at the temperatures, pressures, and flow rates that are the best in some sense. For example, the selection of the percentage of excess air in a process heater is quite critical and involves a balance on the fuel-air ratio to assure complete combustion and at the same time make the maximum use of the Heating potential of the fuel. Typical day-to-day optimization in a plant minimizes steam consumption or cooling water consumption, optimizes the reflux ratio in a distillation column, or allocates raw materials on an economic basis [Latour, Hydro Proc., 58(6), 73, 1979, and Hydro. Proc., 58(7), 219, 1979]. 

Example 6 Cooling Tower Determine water consumption and amount of heat dissipated per 1000 ftVmin of entering air at 90 F drydsulb temperature and 70 F wet-bulb temperature when the air leaves saturated at 110 F and the makeup water is at 75 F. 

Coarse solids are discharged by siphons extending to the bottom of the hindered-settling zone. Siphon control is obtained by a novel hydrostatically actuated valve which makes or breaks the siphon to flow only when the teeter zone is in correct condition. Discharge by an intermediate fraction from the upper column is by means of additional siphons. Hydraulic-water consumption is considerably lower than required for multipocket sizers. 

Water Consumption Jigs require much water. In most installations, the Harz-type jig uses 0.006 to 0.01 m water/kg (1500 to 2500 gal/ton) material treated. Water requirements for treating minus 10-mm (%-in) iron ore in a Wemco-Bemer rougher-cleaner jig circuit are approximately 0.005 m water/kg (1200 gal/ton) of material processed. 

Equipment with Current Control Based on Water Consumption... 

In water containing sulfate, the use of the electrolysis protection process with low water consumption can sometimes result in the formation of small amounts of HjS, which is detectable by the smell. Sulfate reduction occurs through the action of bacteria in anaerobic areas (e.g., in the slurry zone of the tank). 

In order to reduce fresh-water consumption in the scrubber, the usage of distillation bottoms and the off-gas condensate should be maximized since diey have the least ammonia content. The flowrate resulting from combining these two sources (5.8 kg/s) is sufflcient to run the scrubber. However, its ammonia composition as determined by the lever-arm principle is 12 ppm, which lies outside the zone of permissible recycle to the scrubber. As shown by Fig. 4.7, the maximum flowrate of the off-gas condensate to be recycled to the scrubber is determined to be 4.1 kg/s and the flowrate of fresh water is 0.9 kg/s (5.8 — 0.8 — 4.1). Therefore, direct recycle can reduce the fresh-water consumption (and consequently the... 

As a result of segreg ion, interception and recycle, we have eliminated the use of fresh water in the scrubber leading to a reduchon of fresh water consumption (and influent to biotreatment) by 6.0kg/s. Therefore, the target for segregation, interception and recycle has been realized. Next, we focus our attention on sink/generator manipulation to remove fresh-water consumption in the steam-jet... 

Expensive in water consumption, with large volume flow rates... 

Toxicity alucs for carcinogenic effects also can be c.xprcsscd in terms of risk per unit concentration of the substance in the medium where human contact occurs. These measures, called unit risks, are calculated by dividing the slope factor by 70 kg and multiplying by the inhalation rate (20 m /day) or the water consumption rate (2 L/day), respecti ely, for risk associated with unit concentration in air or water. Where an absorption fraction less than 1.0 has been applied in deriving the slope factor, an additional conversion factor is necessary in the calculation of unit risk so that the unit risk will be on an administered dose basis. The standardized duration assumption for unit risks is understood to be continuous lifetime c.xposure. Hence, when there is no absorption conversion required ... 

EPAct also nationalized state efforts that had gotten underway to regulate water consumption of toilets, plumbing fittings, and showerheads. The faucet and showerhead standards reduce hot water use, thereby saving energy for consumers. The toilet effi-... 

Water consumption for commercial and industrial premises are metered and priced per cubic meter or gallons of usage basis, with additional costs for reading and maintenance of the meter station(s). It is important that assessment of water usage is as accurate as possible, as water charges are based on a sliding scale, i.e. as volume of water usage increases, cost per unit decreases. 

Feedwater costs Depending on the source of water supply, there may be charges for water consumption. This consumption will be dictated by the make-up water needs for the station. 

Much lip service is paid to water re-use, which, on the whole, is more fashionable than practicable. Better opportunities arise from simple economy in water consumption at each point of use. Water reuse after effluent treatment is not often practicable. It appears, if at all, most favorable in the re-use of slightly contaminated water for some low-grade purpose such as washing down. 

Surprisingly the water consumption of a starter battery, provided it contains anti-monial alloys, is affected by the separator. Some cellulosic separators as well as specially developed polyethylene separators (e.g., DARAMIC V [76]) are able to decrease the water consumption significantly. The electrochemical processes involved are rather complex and a detailed description is beyond the scope of this chapter. Briefly, the basic principle behind the reduction of water loss by separators is their continuous release of specific organic molecules, e.g., aromatic aldehydes, which... 

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