Technology at Water Treatment Facility is Astounding

Have you ever wondered how our drinking water stays drinkable? Millions of Americans go on with their daily lives and never think about how it is that we are able to drink water that is safe for us. Cities and towns go through a daunting process to keep water safe for everyone. Since I went to school for Environmental and Resource Science, it was definitely a good idea for me to tour a water treatment facility and learn about the water treatment process. The following is an article based on the interview and tour given by the staff at the River Mountains Water Treatment Facility in Henderson, Nevada. This facility treats water that comes from Lake Mead, Southern Nevada's main source of drinking water. I wrote this article using the notes that I took while touring the facility.

The River Mountains Water Treatment Facility is located in Henderson close to the River Mountains on Burkholder Avenue. At approximately 8:00 am my class and I were granted access to the facility by security. We waited in the lobby until the tour started. In the lobby were signs which provided a general overview of what the people at the water treatment facility are responsible for.

A general overview of how the water is treated was provided:

Flow split structure: After being pumped through to the River Mountains from Lake Mead, water enters here at the water treatment facility.

Oxygen and ozone production: Ozone is then used to destroy microorganisms found in most surface water supplies produced on-site in the building. The source materials for ozone generation are the atmosphere and electricity.

Ozone contactors: Ozone is introduced into the water. Water that is flowing through the contactor chamber is disinfected by millions of fine bubbles of ozone.

Flash mixing: Coagulant ferric chloride and other similar chemicals are added to the water to help bring small, suspended particles together so that they can be captured by filters.

Flocculation basins: The water is stirred gently by large, slowly rotating paddles. This causes suspended particles in water to bump into each other, forming larger clumps called floc. This is sent through dual media filters. The water flows in the filters through a 72 inch layer of and to remove foreign particles. Zinc orthophosphate is added to the water to prevent pipe corrosion; sodium hypochlorite is added for additional disinfecting and to prevent the regrowth of microorganisms in the distribution system.

Clearwell: Water is stored here before being distributed to local water purveyors.

Rebecca Colgate and Alan Sims were the tour facilitators. Rebecca works in the chemistry department and Alan works in the microbiology section. They told us that approximately 500,000 analyses of drinking water were done last year alone! Approximately forty people work in the laboratory and sixteen different analyses are done in microbiology. As far as measuring the amount of chemicals in the water, they usually measure by parts per million or parts per trillion. They told us that the important thing was to stay below the maximum contaminant level (MCL) for all substances. Even if the federal regulations are not as high as the EPA regulations, they still have to follow the EPA regulations. They are the water wholesaler for Las Vegas, Henderson, Boulder City, and a number of other locations.

First Stop: Inorganic Analysis Lab

The first lab we went into was the Inorganic Analysis lab s.p. They refer to this place as the workroom. This is the room that contains the chemicals that are used for treatment at the plant. There was a waste collection area. This area is carefully monitored and they have to make sure that the pH is neutral. There were yellow cabinets which were labeled flammable. Also in the room was a machine known as a Millipore. This machine ionizes the water and makes it the purest water possible. As a matter of fact, Rebecca said that the conductivity at the time was only 0.53. This meant that there was very little in the way of cations or anions (positive and negative charges).

General Inorganic Lab

The next lab we were taken to was the general inorganic lab. There were four chemists working in there at the time. In this room was a liquid chromatograph attached to a mass spectrometer. Liquid chromatography is used to test for perchlorate. The liquid chromatograph and mass spectrometer work together to get the amount of perchlorate down to the parts per trillion levels. It separates samples into their various components. Other substances involved in this are fluoride, bromide, nitrate, and orthophosphate. There were also five dual chromatograms. Rebecca said that is takes approximately twenty minutes to get a perchlorate sample out of them. Also in the lab was an autosampler. They tell the autosampler where to look for a particular sample. Of course it is all computerized. The autosampler contains a chromatography oven. Another machine in the lab was a discrete analyzer which is used to analyze for ammonias, phosphates, nitrates, and other different nutrients. In the lab was a chemist named Johnny who was running the autosample analyzer. One machine known as the TOC (Total Organic Carbon) was also in the lab. In this machine, sulfate oxidation occurs. The temperature shoots up to 720 degrees C so that nitrogen can be found. Inside the TOC is a column. The salt layer that forms on the inside of the column is calcium residue. Approximately 80 micro liters of water is inserted into the TOC. Complete combustion leads to formation of carbon dioxide. One can then look for gasoline constituents or signs of an algae bloom.

Organic Analysis Lab

After the Inorganic Lab, we were led into the Organic Analysis lab (GC). Inside this lab was a Triple Quadrupole Mass Spectrometer. Rebecca told us that it can run about a half a milliliter of injection. It is the energy inside the machine that breaks up the elements. This machine is different from the autosampler because of the fact that the autosampler can be injected with only one hundred micro liters of injection. The GC can run the injection in about thirty minutes. Fifteen chemists do about 300,000 samples a year!

Metal Analysis Lab

The next lab we went to was the Metal Analysis lab. In this lab were three instruments of particular importance. The first was a CCD Simultaneous ICP (Inductively Coupled Plasma). This machine has plasma inside it which is heated to approximately 5000 degrees Celsius. It ionizes everything and it checks wavelengths that come out from the plasma. It is these wavelengths that identify the different metals. Another machine, known as the ICPMS (Inductively Coupled Plasma Mass Spectrometry), is good in that the results that come out of it are legally defensible. It looks at trace metals- sodium, calcium, magnesium, potassium, etc. The detection limits are in parts per billion. The metal analysis lab contained a Eureka which is a machine that checks conductivity, turbidity, etc. This lab, like all of the other labs, contained a water polisher (Milli-Q). Also in the lab was a barometer. While it is rather simple device, it is important for taking pressure measurements at the lake. Alan Sims showed everyone a device known as the Beta bottle. It is used for taking discrete samples in a water column at a particular level. It can take samples from up to ten different depths.

Pathogen Monitoring Hall and Virus Extraction Lab

The last stop of the tour was the Pathogen Monitoring Hall. Every lab in this hall was labeled with an orange BIOHAZARD sign. This area is the microbiology section. One of the biggest things this area works with is the Cryptosporidium. Alan told us that it can be killed with chlorine and ozone. A bacteriologist and toxicologist work in the Pathogen Lab. They deal with things such as salmonella, E. Coli, hysteria, microbacterium, etc. The lab we saw in this section was the Virus Extraction Lab. We met Sal who works in the Virus Extraction Lab. He told us that samples are usually done in one day. He told us he was currently looking at the adenovirus, norovirus, etc. He showed us a machine known as a PCR which extracts the nucleic acids from the viruses. He told us that he works mostly with RNA viruses.

The ins and outs of a water treatment facility are truly amazing. Many facilities provide tours of their labs to the public. It is a great way to learn how our water stays clean enough for us to drink. Consider visiting a water treatment facility in your area. Anyone who is interested can learn about the Southern Nevada Water Authority at http://www.snwa.com/html/wq_treatment_facilities.html.