[ Wastewater Management ]
[ Wastewater Management ]
Background The earth contains an estimated 1,386 million cubic kilometres of water . This level is constant ; none of it escapes the earth ’ s atmosphere . There is a theory that this water comes from asteroids and comets that collided with earth ; whatever the truth , for the last few billion years , the figure has remained constant . However , it matters to human beings what form the water is found in . It can be in different phases ( ice , liquid , vapour ); most of it is unfit for consumption , because it is saline or contaminated ; and some of it is difficult to access ( for example , in glaciers or underground ). All in all , only about 0.001 % of water is readily available for human use . This partly explains why , in a world facing heavy population pressures , around 2 billion people do not have access to clean and safe drinking water , while 46 % of the world ’ s population lacks adequate sanitation services . Water availability is influenced by several factors : political , ecological , etc ., and many of the solutions are not a question of technology per se . For instance , carbon emissions cause global warming that gives rise to erratic weather patterns ; planting trees can help fix the water in the ground ; mobile laboratories or public transport can make it easier for rural populations to gain access to a water .
Technology However , technology can make a great deal of difference in a number areas , including efficiency gains , recycling and automation . Efficiency gains : Whether in terms of energy consumption , water consumption or carbon footprint , the latest wastewater and desalination plants are much more efficient than the older ones . Veolia ’ s seawater desalination plant at Hassyan , UAE , due to go online in 2026 , will be powered by solar energy and consume a low 2.9 kilowatt-hours per cubic metre , confirming the progress of RO plants , which have reduced energy consumption by 35 % over the last 10 years . The modernization of Veolia ’ s Greater Lyon wastewater treatment plant at Saint Fons will see a reduction in electricity consumption by 10 %, gas consumption by 72 % and chemical additives by 50 %. Waste heat recovery from nearby incinerators will replace fossil fuels . These are examples of Veolia ’ s 2024-7 “ Strategic Program ”, which aims for efficiency gains in its water management and energy consumption . Desalination is rapidly emerging as a means to ensure adequate supplies of drinking water , especially in dry regions such as the Arabian Gulf . A major problem is what to do with the salt once it has been extracted .
Drought and tourism
Part of the appeal of Mediterranean countries is their hot , dry climate . But this places them in a dilemma . Large parts of Sicily are so parched of water that they have been virtually reduced to desert . So farmers in this region are thinking of replacing their olive and wine production with more drought-resistant African-style foods . In Greece , prolonged drought has reduced the potato harvest to half that of previous years . The pressure from tourism merely adds to the number of people needing to slake their thirst during the hottest months of the year . But tourism is a major source of income . What to do ? The answer is probably to invest in desalination , as is occurring already on the Greek islands .
Discharge back into the sea is scarcely an option given the threat to marine life , while disposal on land harms the soil and vegetation . Solutions have been proposed by MIT , which is studying a process of converting waste materials into useful chemicals , including ones that increase the efficiency of the desalination process itself . The process produces sodium hydroxide ( caustic soda ) that pretreats the seawater before desalination , making it less acid and so less corrosive . Another chemical
Siemens delivered the electrical , automation and instrumentation packages for a solar-powered RO desalination plant in Al Khafji , Saudi Arabia .
16 Stainless Steel World October 2024 www . stainless-steel-world . net