Water shortages caused by climate change and urbanization are endangering our freshwater supplies to an ever-increasing extent. According to certain forecasts, almost half of the world’s population will experience drastic water shortages in the decades to come. That is why it is essential to protect and complement our freshwater supplies by finding and using alternative sources of water.
Ildikó Bodnár, a professor at the Department of Environmental Engineering at the Faculty of Engineering (MK) of the University of Debrecen (UD), explained to hirek.unideb.hu that science refers to greywater to identify the generally mildly contaminated, soapy, detergent-containing water that originates from household plumbing units, generated by bathing, doing laundry and dishwashing, but not containing blackwater from flush toilets.
As opposed to rainwater or other kinds of precipitation, which normally fall intermittently, greywater (sometimes spelled grey water, graywater or gray water) is generated in households almost continuously, thus providing a sustainable water source for activities that do not require potable water, such as irrigation, toilet flushing or car washing.
Ildikó Bodnár underlined that the treatment and reuse of greywater has become a particularly important issue in regions struggling with the lack of freshwater resources. It can reduce the demand for freshwater and the infrastructure costs required for supplying it. In addition, this method creates a smaller environmental footprint than, for example, the desalination of seawater.
According to the environmental expert at UD, greywater, which can account for up to 90 percent of household wastewater, is easier to treat than wastewater containing blackwater, which comes from toilet flushing. Among greywater sources, bathroom greywater is contaminated to a lesser extent than kitchen wastewater, which makes it ideal for reuse. However, before actual reuse is possible, greywater must be treated in order to remove certain contaminants, which process can be taken care of through a variety of different methods.
- During the course of our research, we analyzed the efficiency of an improved process of what is known as coagulation-filtration for treating greywater originating from bathrooms. In laboratory experiments, we assessed the effects of two cost-effective inorganic coagulants, ferric chloride and hydrated lime, as well as those of their combination. The tested and improved process demonstrated high removal efficiency for bathroom-origin greywater samples in terms of turbidity, chemical oxygen demand, biochemical oxygen demand and anionic detergent content in greywater samples originating from bathrooms. It also reduced the number of Escherichia coli and coliform bacteria colonies, thus improving the microbiological parameters as well. In addition, statistical analysis also confirmed the claims regarding the efficiency of the treatment method under scrutiny- said Ildikó Bodnár, a professor at the Department of Environmental Engineering at the University of Debrecen.
The efforts and results of the activities of the research group were recognized by the Count István Tisza Foundation for the University of Debrecen and the University of Debrecen with a Publication Award. The researchers shared their findings in an article published in the English-language scientific journal Results in Engineering, the full text of which is available for your reading pleasure here.
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