Freshwater consumption

Based on the previous studies and the above discussions, it is required to achieve environmentally sustainable development in textile industry since closing of water cycle is highly recommended [29]. It can often be done by the application of the combined membrane-biological processes, especially by the implementation of NF-biological and RO-biological processes, which enables the water reuse process, thereby the minimization of freshwater consumption. 

Problem statement Given a set of water using units, freshwater sources, wastewater sink and available regeneration processes with their limiting data, a globally optimum for the freshwater consumption is sought. The corresponding non-liner model to solve this water allocation problem (WAP) written in terms of contaminant mass load is ... 

Selected environmental indicators This smdy assessed global warming potential (GWP) and two additional indicators primary energy demand (PED) and freshwater consumption (Table 10.4). Other indicators were not included due to limitations on availability of inventory data. 

The liquid is partly recycled to the flour to be added together with fresh water to get the slurry prior to liquefaction. The recycling degree must be as high as possible to avoid too much freshwater consumption but is on the other hand limited by the potential negative effect of components from back-stillage on the yeast. 

U.S. Department of Energy National Energy Technology Laboratory, Reducing freshwater consumption at coal-fired power plants Approaches used outside the United States, 2011. Available from http //www.netl.doe.gov/technologies/ coalpower/ewr/water/pdfs/Outside US Approaches%20 NETL%201493.pdf. Accessed June 19, 2013. 

Before starting an end-of-pipe treatment, effiuent segregation is required this separates contaminated fluid from the cleaner streams. The final wastewater is less voluminous and can be treated more effectively and by more appropriate treatment methods, whereas the more clean stream can be reused in the factory with limited or no treatment needed. Vajnhandl and Valh (2014) reviewed the wastewater reuse programs used over the last 10 years covering the European textile finishing industry, with special emphasis on the FP7 project Aquafit4use. The water treatment methodologies presented enable more than a 40% reduction in freshwater consumption. 

Figure 1 Operations included within the system boundary for the shale gas life cycle. GHG emissions and freshwater consumption associated with operations up to and including gas treatment and processing are allocated to pipeline quality gas (which goes on to the transmission pipeUne) and the natural gas liquid (NGL) coproduct in accordance with their heat content (HHV) transportation, fractionation and disposition of NGL are not included within the scope of this study. GHG emissions and freshwater consumption associated with power distribution are also excluded from the scope of this study.

GHG Emissions (kg C02eq/MWh) Fraction of Gross Methane Emitted (%) Freshwater Consumption (gal/MWh)... 

The capabilities of the proposed approach have been illustrated with a case study. In this case ten water using operations with single contaminant are considered. The objective is to design a suitable network with the minimum capital cost and minimum freshwater consumption. Table 1 shows the limiting data for a ten processes problem. In this case there is one fixed source of freshwater and ten fixed operations. Each water user can be described by maximum and minimum allowed concentration (inlet and outlet) and the individual mass load of contaminants or the limiting flow rate. 

Figure 3. Network design with the minimum freshwater consumption.

Concerns about the accessibility of fresh water have led Kofi Annan, Secretary General of the United Nations, to state Global freshwater consumption rose sixfold between 1900 and 1995 - more than twice the rate of population growth. About one third of the world s population already lives in countries considered to be water stressed - that is, where consumption exceeds 10% of total supply. If present trends continue, two out of every three people on Earth will live in that condition by 2025 . The availability of clean water remains a problem in many parts of the world 20... 

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