Tham khảo tài liệu 'membranes for industrial wastewater recovery episode 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Introduction 7 operations within the factory are conducted so as. in this instance to limit the freshwater demand. Actual examples of demand management reuse and recycling Table demonstrate that the degree of sophistication of the solution to achieve a significant cost benefit depends upon the existing state of water management. It is apparent from Tables and that the quality of water demanded by industry varies considerably from one duty to another. There exist certain determinants such as the Silt Density Index or SDI Section which are of critical importance for some applications but are meaningless in others. Moreover it is generally the case that the volume of water demanded varies inversely with that of its purity across any one industrial sector. For example according to the figures in Table about 20 times as much water-making up around 90 of the total water demand of the plant - is used for cooling in power generation as that required for boiler feed which demands a high-purity water. Such water can only be produced through a combination of adsorptive and membrane separation processes. Water for once-through non-intrusive cooling on the other hand may not be required to meet any specification based on chemical and biological constituents needing only to be below a certain temperature. For some industrial processes the quality of the discharged water does not substantially differ from that of the feedwater. Cooling towers for example concentrate the water as a result of the evaporative cooling process but do not add significantly if at all to the chemical loading rate in terms of mass flow rate of solutes of the effluent. For most industrial sectors however there is a significant pollutant load resulting from their activity. As already stated the large temporal variation in effluent water quality can preclude water recovery and reuse in many cases due to the high cost of treatment to produce water of a reliable quality particularly by .
