Cleaning parameters water quality

Figure 8.7 Water quality parameter as a function of clean membrane pore diameter.

Third, a water quality parameter (WQP), which considers colloid, organics, and salt rejection, was developed for the membranes investigated. A linear relationship beween WQP and log pore diameter was found. Finally, a partial cost analysis of various options was undertaken by evaluation of a) membrane cost as a function of clean water flux and operation at fouled conditions, b) WQP as a function of membrane cost, c) ferric chloride cost, and d) energy costs. 

The amount of oxygen used up in microbial oxidation is - the biochemical oxygen demand (BOD) - another important water-quality indicator. The BOD is taken as a realistic measure of water quality - a clean river would have a BOD value of less than 5 ppm, whereas a very polluted river could have a BOD value of 17 ppm or more. A BOD determination takes a few days, so another parameter called the chemical oxygen demand (COD) is sometimes measured. In a COD determination, acid dichromate is used to oxidize the organic matter in a sample of water. The measurement takes only a couple of hours. 

Hydrophobic and hydrophilic membranes Control of operating parameters (critical flux) Rinsing water quality Cleaning agents and chemical cleaning Backpulsing... 

The most often used subphase is water. Mercury and otlier liquids [12], such as glycerol, have also occasionally been used [13,14]. The water has to be of ultrapure quality. The pH value of tire subphase has to be adjusted and must be controlled, as well as tire ion concentration. Different amphiphiles are differently sensitive to tliese parameters. In general it takes some time until tire whole system is in equilibrium and tire final values of pressure and otlier variables are reached. Organic contaminants cannot always be removed completely. Such contaminants, as well as ions, can have a hannful influence on tire film preparation. In general, all chemicals and materials used in tire film preparation have to be extremely pure and clean. 

Utility boilers generally require waterside chemical cleaning of all boiler surfaces every 300 to 500 days of operation, and this work may be carried out by specialist contractors. It is regarded as a routine function, irrespective of water chemistry, laboratory involvement, or the quality of FW treatment and water management provided. Chemical cleaning of utility boilers is designed to permit the boilers to operate at peak performance and within knife-edge control parameters. 

The effluent obtained after solids removal and microbiological disinfection could be reused as cooling water, cleaning water or industrial process water in many industrial uses. A final polishing step may be necessary if higher quality requirements are needed in some specific industrial uses, e.g., cooling and boiler feed-water. Membrane processes such as NF or RO eliminate inorganic ions and reduce parameters like conductivity, alkalinity or salinity, etc. 

After purification, quality control of solvent purity is necessary. For this purpose, many different analytical methods are utilized. Generally, chromatographic methods such as GC, GC-MS, and HPLC are used. Moreover, UV, infrared, and nuclear magnetic resonance spectroscopy can also be applied but they tend to be less sensitive toward trace impurities. Water in organic solvents is usually determined by Karl-Fisher titration. On the basis of experimental data obtained before and after purification, the efficiency of the clean-up procedure is determined. In general, the efficiency of purification, e.g., the recovery, is expressed by the coefficient R. This parameter is defined as the ratio of the amount of impurities removed to the amount of solvent before purification ... 

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