Rehab Cell

Physical Medicine and Rehabilitation

Tour of your local water treatment plant with Waikato District Council water sources.

Tour of your local water treatment plant with Waikato District Council water sources.

Hi, and welcome to your water treatment plant. My name is Christa and I’m going to be showing
you around. Lets go! Today we’re going to have a look around and
find out how water is collected from a natural source and made safe for us to drink. I know all about Smart Water Starts With You
and I hope you learn more about that too and start to think about how water is an amazing
resource that we have to look after. Here in the Waikato, each person uses around
250 liters every day. That’s ‘this’ many milk bottles. Look around your group. Can you guess how many bottles of water you
would all use each day? Now imagine how much water your whole school
uses. How much your town uses. Water starts to be a very big deal. Water is a limited resource that we often
take for granted here in New Zealand. You turn on the tap and clean, healthy water
comes out every time. Because we’re so used to water on tap, we
often don’t think about water as a valuable resource that needs treatment before it’s
safe to drink and use. Waikato District Council has 12 different schemes to supply communities and the district. The main one is the same as Hamilton, the Waikato River. This is where we get 3 quarters of the water for the Waikato District. The remaining quarter comes from springs at Raglan and Onewhero. A bore for the few houses at Te Akau. Maraetai stream supplies Port Waikato township. Pokeno and Tuakau use a piped connection to Auckland’s southern water supply. Some of you might get our water from a different
source. Some people collect water from the roof of
their houses and store it in tanks. Some families use a pump system in a stream
to transport water to their house. It’s quite common for farms and rural properties
to use an underground bore or well to get water from. Most of us are connected to the piped network
provided by your local council. That’s a system we’re going to learn more
about today. We’re going to check out the process that water takes from the source and makes it ready for us to drink. This is where the water is taken from the
river. It’s called the intake. The water comes through the metal grates,
their job is to stop large items like logs, branches, and rubbish from getting in with the water and wrecking the treatment plants machinery. This is the first part of screening. The water flows from here to the pump house. The water from the intake goes through a band
screen next. The water is pushed through the vertical band
screens that are 20 meters tall. The band screen takes out river weed, twigs,
leaves, and other small items. All that stuff is collected at the top and
washed right back into the river. This is one of the ways to minimise our impact
on the water source. After the water has been screened 2 times,
it comes in to the water treatment plant. Come see. Large pumps move the water from the intake
into the water treatment plant and these pipes. This is what the water looks like at this
point. It’s not quite ready for drinking at this stage, it still needs to have all the little microscopic bits taken out. That’s what happens here, at the sedimentation
tanks. The first part of the process is called sedimentation. That means letting all the tiny bits of dirt fall to the bottom, but some of them don’t want to do that. They’re too small and stay suspended in the
water. So to help get them to settle out we add two
chemicals called aluminium sulphate and polymer. Aluminium works by breaking weak bonds that
hold small bits of dirt in suspension. The polymer also helps small suspended bits
to clump together to form bigger, heavier particles called floculant or floc. The water then comes to these hopper tanks. These are shaped like a V, pointy at the bottom. The floc in this tank looks like a murky,
woolly blanket, you can see it floating in the tank. The water comes into this tank from the bottom,
so as the water rises through the blanket, more floc joins the blanket. This is a way to filter the water. This floc is sucked out of the tanks all the
time and goes into the waste water system. The water treatment plant operators can tell
a lot about the quality of the water by looking at the floc, what colour it is, how tight
it is formed, and how the blanket looks. This helps them make sure the water treatment
plant is operating well. These hopper tanks and the floc blanket have
removed nearly all of the small, tiny bits of dirt. The next stage filters out the rest. These are the gravity-fed sand filters, which
means the water comes in the top of the pool and slowly passes through the sand filters
at the bottom. The sand filters get cleaned every 70 to 100
hours, it’s cleaned by blasting air through the sand filters, followed by clean water
to wash out the dirt. The sand filters take out any floc that’s
left and also gets the larger micro-organisms found in the river water. The main organisms are crypto, and giardia. Both these micro-organisms can make you sick,
so it’s best to get rid of these. This water looks pretty good. We now know that as we screened a couple of
times, had chemicals added to remove all the dirt, and filtered out the large microscopic
bugs. What else could be in there? This is the granular activated carbon room. Granular
activated carbon is this stuff here. Have you ever had a tropical fish and used
this in the filter? How it works is the granular activated carbon
has a huge surface area, with each grain of carbon covered with tiny gaps and holes. This helps the carbon to absorb any particles
not able to be removed in earlier steps of the treatment process we have seen. It helps if there are taste and smell problems
caused by algal blooms in the water source. These tanks have heaps of these cone shaped
filters that let the water pass through, but trap the tiny carbon particles so that they
stay in the tank and keep working. Man, I’ve been walking all over this water
treatment plant, where can I get a drink around here? Surely the water’s clean by now. We’ve dealt with the larger micro-organisms,
but are there any micro micro-organisms? This is the U.V. area. These are here to zap any remaining micro-organisms, even protozoa which are single celled microscopic organisms. The U.V. light deactivates these organisms
by permanently altering their DNA structure so they are unable to infect or reproduce. Water is passed through these large cylinders,
which are filled with heaps of these U.V. tubes, and that’s where the zapping happens. Just before it heads off to your house, the
water needs some chlorine to kill any remaining bacteria and viruses that have escaped all
our other screens, filters, chemicals, and U.V. traps. There’s a large tank where all the water waits
for an hour to maximise the effect of the chlorine. A small amount of chlorine is left in the
water, leaving the treatment plant to provide some protection in the pipes, so the water
remains safe between leaving the plant and coming out of your tap. Now that you know the process that it takes
to get clean water to your tap, would you agree that it’s a valuable resource? Can you think of ways to reuse water at home? The easiest way you can take action is by sharing what you’ve learnt today with your family and friends. We all need to work together to be smart with
our water. Smart Water starts with you.

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