A presentation which explains the chemistry behind thermal pollution . Key topics of chemistry explained in this presentation includes " Variation of solubility of gases in water with temperature " , " Variation of density of water with temperature " etc.

1. Chemistry behind thermal
pollution
Anand R
Founder, Evolvingminds
&
Utkarsh Sethia
Intern, Evolvingminds
14th Jan , 2017

2. A picture is worth a thousand words
Reference - http://www.crystal-lagoons.com/

3. Hot water is less dense than cold
water
Reference - http://www.learnz.org.nz/

4. Saltwater is more dense than
freshwater
Reference - www.science-sparks.com , http://bucketlistjourney.net/ ,
https://www.zigzagonearth.com/

5. Reference - http://www.evolvingminds.org/ ,
https://www.youtube.com/user/FlinnScientific
Gases are less soluble in hot water

6. Reference - http://fphoto.photoshelter.com/
https://basofscience.files.wordpress.com
Book – Introductory Chemistry, 4th edition by Nivaldo J. Tro
Warm soda pop fizzes more than cold soda pop because
the solubility of the dissolved carbon dioxide decreases
with increasing temperature

7. Reference - http://straighttothehipsbaby.blogspot.in/
Book – Introductory Chemistry, 4th edition by Nivaldo J. Tro
Sometimes bubbles begin to form in hot water below
100 degree Celsius. These bubbles are dissolved air – not
gaseous water – leaving the liquid

8. Reference - https://commons.wikimedia.org
http://www.poolspas.ca/ , www.chemtreat.com
Book – Chemistry, 7th edition by Zumdahl
 Boiler scale is a deposit that forms directly on heat
transfer surfaces.
 Bicarbonate ion is formed when carbon dioxide is
dissolved in water containing the carbonate ion

9.  Hard water contains calcium ion
 Calcium bicarbonate is soluble in water, but calcium
carbonate is insoluble.
 When the water is heated, the carbon dioxide is driven off.
For the system to replace the lost carbon dioxide, the
reverse reaction must occur
 This reaction, however, also increases the carbonate ions,
causing solid calcium carbonate to form.
 This solid is the boiler scale that coats the walls of
containers such as industrial boilers and tea kettles.
 Boiler scale reduces the efficiency of heat transfer and can
lead to blockage of pipes.
Reference – Book (Chemistry, 7th edition by Zumdahl)

10. Thermal imagery
Reference - http://www.eurosense.com/

11. Thermal pollution explained
• Water from lakes and rivers is used for industrial cooling.
• After being used, the water is returned to its natural source
at a higher than ambient temperature.
• Because it is warmer, this water contains less concentration
of oxygen and is also less dense.
• It tends to float on the colder water below, thus blocking
normal oxygen absorption.
• This effect can be especially important in deep lakes.
• The warm upper layer can seriously decrease the amount
of oxygen available to aquatic life in the deeper layers of
the lake.
Reference – Book (Chemistry, 7th edition by Zumdahl)

12. Reference - https://www.satelytics.com/

13.  The metabolic rates of fish and other aquatic animals
increase in the warmer water released near the plant
outlet; thus, their need for oxygen increases.
 But the concentration of dissolved oxygen is lower at the
higher temperature.
 This oxygen depletion can harm these aquatic populations.
Reference – Book (Chemistry , The molecular nature of matter and
change by Martin S. Silberberg)

14. Sustainable industrial cooling
Reference - http://www.crystal-lagoons.com/

15. Thank you
Evolvingminds – anand@evolvingminds.org , +91 99452 75572
Utkarsh Sethia – sethiautkarsh@gmail.com , +91 80562 70110