Potable Water + Global Reserves

What do humans use Earth’s natural resources for?

Energy / fuel for warmth and transport, building materials and food.

What is a finite resource?

A resource that will eventually run out.

What is a renewable resource?

A resource that won’t run out or will be replenished quicker before it’s used up.

What are natural polymers?

They can be supplemented or replaced by agricultural and synthetic products.

What is potable water?

Water safe for human usage and consumption.

What makes water potable?

Having sufficiently low levels of dissolved salt and microbes.

Why is fresh water easier to use than sea water?

Seawater contains large amounts of salts which require more energy and money to clean.

Where is rainwater collected in?

Rivers, lakes and aquifers.

How is most of the UKs portable water naturally produced?

Passing the water through filter beds to remove insoluble particles and sterilising the water to kill microbes.

What can you use for sterilising?

Ozone, UV and Chlorine

What is distillation?

The process of hating water until it boils, the salt remains in the liquid and the stream is pure water which is condensed. The waste water is salty and hard to sustainably dispose of.

How does desalination happen?

Reverse osmosis or distillation.

What is reverse osmosis?

Water is put under high pressure and passed through a membrane which prevents ion and molecules passing through. It’s expensive and produces a large volume of waste water.

What does waste water contain?

Harmful bacteria, high levels of nitrogen compounds which can harm ecosystems.

What can industrial waste contain?

Harmful chemicals and organic matter.

What can agricultural waste contain?

Pesticides and organic matter

What is the process of sewage treatment?

Screening and grit removal removes large particles, sedimentation allows tiny particles to settle out from still water to produce sludge and effluent. The sewage sludge is digested anaerobically by bacteria. The effluent is treated with aerobic bacteria to reduce the volume of solid waste.

What is the method for the required practical of purifying water. (without distillation)

1. For each water sample test the pH using a pH meter or universal indicator.

2. Pour 50cm of each sample into a clean, pre-weighed evaporating basin.

3. Heat gently over a Bunsen burner until no liquid left.

4. Allow to cool then weigh the evaporating basin gain and calculate mass of remaining liquid.

What sample would have the highest amount of solids?

Sea water

What could cause a sample to be acidic?

It could be affected by acid rain.

What is the method for distillation?

1. Set up distillation apparatus

2. Heat sea water solution until it boils gently

3. Distilled water will be produced.

What are the hazards of the required practical?

Acidic/ alkaline water samples can irritate eyes so wear goggles, hot apparatus can cause burns so allow apparatus to cool before touching.