Water Treatment Plant Austin and Alison
Source Water and Intake • Water treatment plants usually draw water from rivers • Water may be treated differently depending on where the water is originally from. • Surface water generally requires more treatment than ground water. • Surface water is also more prone to pollution from pesticides, factories and septic tanks.
Pretreatment and Screening • Pretreatment starts by using large screens to catch the large solid debris. • They also use a process called aeration which uses air to remove undesired gases, minerals or chemical solvents.
Coagulation and Flocculation • Coagulation and Flocculation is an old chemical process in which a coagulating agent, alum, is put into the water. • This method helps remove metals, dirt and microbes. • The alum causes particles to clump together forming “floc” which sinks to the bottom leaving the water clean.
Sedimentation • In sedimentation the water is left undisturbed for a few hours so the floc can settle at the bottom. • On average 85% of the floc settles at the bottom.
Filtration • Water is run through filters to clean the water. • The filtered water is then stored for the next step.
Disinfection • At this step the water may look clean but it may still contain harmful microbes. • So it has to be disinfected so its safe to drink. • The most common disinfectants are chlorine and ammonia. • The water is then tested to make sure the harmful microbes are gone.
Distribution and Storage • Next the water is pumped into distribution pipes or stored. • The distribution pipes consist of fire hydrants, booster pumps, pipes, meters and service lines. • The rest of the water is stored in case of emergencies.