Assessing the Possibilities of Backwash Water Reuse Filters in the Water Treatment System—Case Analysis

Abstract

Due to the worldwide water crisis and diminishing water supplies, it is imperative to reduce water use and reuse it. One possible source of water is the washings created during the purification of drinking water. Backwashing constitutes 2–8% of the treated water used globally; it is more commonly used, primarily for irrigation or to expand surface/groundwater resources. Therefore, recirculating it at the beginning of the water treatment system is reasonable and justifiable, as it can lead to a decrease in the cost of the water that is being used. A study of variations in the content of washings in two water treatment plants revealed the requirement for pollutants to be removed before the water is reused. For the safety of consumers, the presence of microbes in backwashings from both facilities was essential. Variability in the amount and composition of backwashings was higher for surface water treatment in comparison to infiltration water treatment; however, the amount of backwashings was greater in infiltration water. The quantity of microorganisms, including indicator ones, was substantially higher in washings following surface water treatment. On the other hand, in the washings from the infiltration water treatment, large amounts of iron and manganese compounds were present, the recycling of which would reduce the effectiveness of infiltration water treatment. Pre-treatment backwashings from both facilities will be suitable for the suspension separation procedures and disinfection. It is essential to compare the costs connected with water use against the anticipated cost of washing. The potential to purify additional water in the event of a worsening water shortage, however, is the most significant advantage of water reuse. Recycling of the washings will allow to reduce the fees for the use of the environment, even to EUR 150,000 and EUR 250,000 per year for surface and infiltration WTP, respectively.