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<br />~ <br /> <br /> <br />c> <br /> <br /> <br />o <br /> <br />R!:SERVOIR <br /> <br />c:!3(!j)v@w <br /> <br /> <br />In order to have safe and pure drinking water. lhe local water supply must go j <br />through several steps in a treatment process. First Is AERATION In which <br />waler is sprayed inlo the air to release any trapped gases and absorb <br />additional oxygen lor better laste. To remove any possible dirt in the water, <br />three more steps are necessary - COAGULA TION. SEDIMENT A TION and I <br />F1L TRA TlON. Alum, or aluminum sulfate, is added 10 the water which breaks, <br />down inlo tiny, sticky particles called "floc". The dirt then coagulates with <br />the floc and begins to settle to the bottom as the particles become heavier. <br />ALUM <br />4( <br /> <br />.( COt>.GULA nON <br /> <br /> <br /> <br />0.0. <br /> <br />~ <br /> <br />f:J <br /> <br />eAERATlON <br /> <br />o ~ <br /> <br />o <br /> <br />Q <br /> <br />r <br /> <br /> <br />::'\ 1::: F~/:::'::T' i ()r-....~ <br /> <br /> <br />Place a lid on lop of one of the jars and shake it for <br />10 seconds. Next pour the water back and forth <br />into another container. How does this action allow <br />the trapped gases to escape and new oxygen to be <br />added to the water? <br /> <br />Dissolve 10 alum crystals in 1 tablespoon of warm <br />water In a cup. Grind thecrYSlals while mixing <br />them into solution. Pour the contents olthe cup <br />into the Jar of aerated water. rinse the cup and add <br />thIS water to the jar. Slowly stir lor live minutes <br />and observe the formation of "floc". How rapidly <br />did the!toc begin to form? <br /> <br />Increased contact of water surface with a greater <br />volume of air will permit the release of trapped gases <br />and more opportunity for oxygen molecules to be <br />absorbed. <br /> <br />Floc should begin forming within two to three minutes. <br />As the particles become more visible, the warer will <br />become increasmglV clearer. <br /> <br />-16- <br />