Bubbles bring water problems
18 Oct 2001
Research carried out by a US graduate student has identified that air bubbles can cause serious problems in water treatment plants.
PhD candidate Paolo Scardina at Virginia Tech in Blacksburg, Virginia, has found that bubbles can allow pathogens to be carried through the water treatment process, and can even cause damage to the equipment in treatment works.
River and lake water flowing into water treatment works often contains dissolved air and other gases, and these can come out of solution during the various stages of the purification process, creating air bubbles. According to Scardina, this can cause problems at several stages of the process. If it happens during the settling process - where solid particles are allowed to drop to the bottom of tanks of water - pathogens can become attached to the bubbles and float on through the plant.
Bubble eruptions can also damage the filters in the plant, he says. Bubble masses can punch tiny holes in filter membranes, allowing pathogens to pass straight through. Filtration is the last line of defence against certain bugs, such as Cryptosporidium and Giarda, which are impervious to chlorine disinfection.
