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Sustainability
Published in James P Trevelyan, Learning Engineering Practice, 2021
Here’s an example. In the early 2000s, a Brisbane engineer at a food and beverage processing plant saw an opportunity to recycle wastewater… It took ages, but we finally convinced our management to install a reverse osmosis plant so that we could recycle process water, enormously reducing our consumption and also significantly reducing biological nutrient discharge into the waste stream. Both of these were significant gains for environmental sustainability. It took several years, because the management would not compromise on seeking a 25% return on investment. We tried several ways to make the necessary business case before it was finally accepted. Sometime after we installed the reverse osmosis plant, the city water supply was drastically curtailed because of drought. Our competitors had to close down their production lines because they were consuming too much water; they had to import products instead and sell them at a loss to maintain their market presence. We were able to continue at full production and made huge profits, repaying the reverse osmosis investment by several hundred percent. In retrospect, we should have based our case on the risk of water restrictions—it would have been accepted much more readily.
Fabrication and Applications of Functionalized Membranes in Drinking Water Treatment
Published in Sundergopal Sridhar, Membrane Technology, 2018
Somak Chatterjee, Sirshendu De
where, Q are the cross-flow rates (m3/s), ΔP is the transmembrane pressure drop (Pa), η is pump efficiency, and Jw is the permeate flux (m/s). A typical example shows that the organic-inorganic membrane made of hydrous zirconia nanoparticles embedded in the PVDF matrix membrane (Zheng et al., 2011) produced for filtration of arsenic and other water related contaminants consumes 15 Watt hours per unit area of the membrane (m2) and per unit volume of water (m3) produced. However, the energy required for a reverse osmosis plant for desalination is 4 Kwh/m3 at a flow rate of 10 L/m2h. Therefore, the energy required in this case is 1.4 × 106 Kwh per unit area of the membrane (m2) and per unit volume of water (m3) produced (Busch et al., 2009). Hence, the magnitude of energy requirement is high for a typical reverse osmosis plant. The cost of preparing such MMMs is quite low compared to conventional NF or RO membranes. For example, the cost of preparation of a laterite embedded PAN UF membrane is US$ 20.00 per unit area (m2). However, the cost of a typical RO membrane is US$ 40.00 per unit area (m2) (Zhu et al., 2009). This reveals the cost effectiveness of a prepared organic-inorganic membrane for water filtration.
Chapter 22 Safety-Critical Systems And Engineering Design: Cardiac And Blood-Related Devices
Published in B H Brown, R H Smallwood, D C Barber, P V Lawford, D R Hose, Medical Physics and Biomedical Engineering, 2017
A further process that is used for purifying water is reverse osmosis. In principle, this involves placing the impure water, under high pressure, on one side of a semi-permeable membrane. The water which is collected on the other side of the membrane is very pure—typically 97% of the organic matter and 90% of the trace elements in the water supply will have been removed. The semi-permeable membranes are expensive to replace, so that the water supply is usually pre-treated. In particular, the membrane is destroyed by chlorine which is often added to water supplies. A large scale reverse osmosis plant might consist of particle filters to remove suspended matter, an activated carbon column to remove chlorine, a water softener, and then the reverse osmosis unit. Final purification would be done by a de-ionizer followed by bacterial filters.
Value of groundwater to public supply in west-central Florida
Published in International Journal of Water Resources Development, 2022
In 2014, the cost for a 10 mgd reverse-osmosis plant built besides a WWTP was US$70 million in capital costs, with an additional US$5 million in operating and maintenance costs (Herman & Scruggs, 2017). Table 2 shows the total capacity of WWTPs in SWFWMD counties. Conveniently, the flow from these plants amounts to same as GW used for public supply (333 mgd). For this estimated cost, the assumption is made that all the 333 mgd can be purified using IDR.
Desalinated drinking-water provision in water-stressed regions: challenges of consumer-perception and environmental impact lessons from Antofagasta, Chile
Published in International Journal of Water Resources Development, 2022
M. Šteflová, S. H. A. Koop, M. C. Fragkou, H. Mees
Desalination is also linked to significant energy demand (Østergaard et al., 2014). It has been estimated that a reverse osmosis plant requires between 0.5 and 4.0 kWh/m3, which can vary depending on input salinity, temperature and the technology used (Goh et al., 2017; Li et al., 2018). This corresponds to about five times as much energy as traditional drinking water processes (Jacobsen, 2012).