Integration Of Water Networks With Multiple Properties

Water is an indispensable and important resource on the earth.The shortage of water resources has seriously threatened the sustainable development of human society.Water saving and emission reduction have become urgent research topics.The traditional water network integration,in which only contaminant concentrations are taken as the limiting factor for reuse and emission of streams,has become mature.However,besides the contaminant concentrations,the properties and functions of water streams also affect the allocation and emission of water streams in water networks.Therefore,it is of great practical significance to study the property integration of water networks.This paper mainly studied the property integration of water networks with multiple properties.The specific research contents are as follows:1.Based on the concepts of operator potential,a new design method was proposed for integration of water networks with multiple properties,in which only reuse is considered.The precedence order of demands was identified with the operator potential values of the demands.A linear programming approach was used to determine the allocation of sources to demands.The above design method was illustrated in detail by two literature examples.2.A new design method was presented for design of complex total water networks.The design steps are as follows:(1)A water-using network without regeneration unit was designed.The initial properties of the regenerated stream were estimated based on the above network,and the flowrate of the regenerated stream was to be determined.(2)The regenerated stream obtained above was taken as an additional source stream of the system to form the network with regeneration unit.By using the design method proposed in Chapter 2,the water network with regeneration unit was designed.(3)The final design of the above network could be obtained after several iterations.(4)If the properties of the discharged wastewater did not meet the environmental discharge requirements,the flowrate for wastewater to be treated could be adjusted to meet the environmental requirements,and the final results were obtained.The design procedure was illustrated in detail by two literature examples.The freshwater consumptions obtained in this work are less than that obtained by the mathematical programming methods in the literature.3.Based on the concepts of operator potential,new methods were proposed for the total water networks with property interceptors.From the point of view of mixing or not of the source streams which pass through the interceptors,there are two types of networks:non-mixing networks and mixing-networks.In a non-mixing network,the sources will not mix before entering an interceptor.In a mixing-network,the stream can be mixed before entering an interceptor.For a non-mixing network,appropriate property interceptor was identified for each source,so that the properties of each treated source are as close as posslble(or completely meet)the property constraints of all the demands.Then the treated sources will be regarded as the additional sources of the system to form network with interceptors.The above network could be designed with the method proposed in the above Chapters.Finally,the property interceptors were used to treat the discharged wastewater to meet the environment requirements.For a mixing-network,a water-using network without interceptor was designed first.The un-reused sources in the above network would form the mixed stream before interception.Then,the appropriate property interceptors were identified to treat the mixed stream to obtain the initial properties of the treated stream.After several iterations,the water network involving the property interceptors could be obtained.Finally,the wastewater treatment system was designed to meet the environment emission standards.The results obtained by this work are comparable to those obtained by mathematical programming methods in the literature.It can be concluded that the methods proposed in this paper are simple in calculation and have clear engineering meaning.