The Glendale Water Treatment Plant Fieldtrip

In our fieldtrip to the Glendale Water Treatment Plant we learned how the water gets from the Truckee River to your home here in the Reno Sparks area.  When water is taken from the Truckee River there is a variety of things in the water such as trash, organics, dirt, and viruses that need to be gotten rid of.  The process in which the Glendale Plant takes all this unwanted junk out of our water is a very simple one.  When the water is first taken from the river it goes through a trash screen that filters out the big debris such as logs and trash. The water is then sent to a 2 million gallon settling pool where the larger particles of dirt can precipitate to the bottom.  The water then passes through another filter to get the lager particles out leaving only micro-particles.  A coagulant is added to the water at the rapid mix stage.  The purpose of a coagulant is it causes the micro-particles that are negatively and neutrally charged to stick together with the positively charged coagulant.  The coagulant that the Glendale Plant uses is Alum.  They chose to use Alum because it is tried and true.  This is a very well known coagulant and has been used for many years so there is a lot of information known about it.   They have also found that Alum works well at high temperatures.  At the rapid mix stage paddles are moving at high speeds to make sure all of the particles come in contact with the Alum.  This is the beginning of the flocculation stage.  Flocculation is a slow mixing process where the micro-floc particles collide with each other and form larger floc particles. There are three paddles used in the flocculation process.  The first paddle rotates the fastest, the second paddle is slower and the third paddle even slower. The paddles turn at slow speeds so the particles will clump together and not break apart if they hit each other. The entire process last for about 15 to 20 minutes. If the paddles mix to fast or too long than the floc particles collide too often and get torn apart, defeating the purpose of the process.  After the flocculation process the newly formed particles hit these parallel walls that are set at a 55-degree angle to separate the particles from the water.  At this point the water is about 99.5% free of contaminants.  The water is then filtered one last time to remove the smaller particles missed in the flocculation process. Next the water is sent to be chlorinated to kill viruses that could be in the water.  Chlorine is added at 1 ppm  in the form of Sodium Hypoclorite. The water has to be in contact with the chlorine for about two hours to give the chlorine adequate time to kill the viruses.  Next soda ash is added to the water before it is distributed.  After this process of filtering, precipitating, and killing the water is distributed to your house for you to enjoy.                                            

Michael Fears

Brian Hopkins