IB Environmental Chemistry: Water Treatment

Created by mbavlsik 

Upgrade to
remove ads

pollutants in waste water

heavy metals (mining and industrial processes), pesticides (farming), dioxins (waste incineration w/Cl), polychlorinated bipheryls (PCBs) (capacitors, transformers), organic matter (farming), nitrates (intensive animal farming, fertilizers), phosphates (detergents)

primary treatment

filtration, sedimentation, flocculation, skimming

primary treatment: filtration

removes large objects

primary treatment: sedimentation

removes sand and small objects

primary treatment: flocculation

removes suspended solids during precipiation (Al2(SO4)3 + 3Ca(OH)2 --> 2Al(O)3 (s) + 3CaSO4

primary treatment: skimming

removes grease from surface

secondary treatment

activated sludge process (removes most of O2-demanding wastes): 1. sewage treated w/O2 in sedimentation tank; 2.sludge containing bacteria, microbes settles out; 3. discharged water is disinfected w/chlorine or ozone

tertiary treatment

removal of heavy metals, removal of phosphates, removal of remaining organic matter, removal of nitrates

removal of heavy metals

precipitation with hydroxides or carbonates (Pb(2+) + 2OH(-) --> Pb(OH)2)

removal of phosphates

w/CaO or Al(SO4)3 --> Al(3+) + PO4(3-) --> AlPO4

removal of remaining organic matter

activated carbon beds, oxidize absorbed organic matter when heated to CO2 and H2O

removal of nitrates

ion exchange: passed through resins with silicates/zealites, Na(+) replaced by H(+), Cl(-) by OH(-) (H(+) + OH(-) -->H2O), requires no heating or fuel, but resins need to be replaced/regenerated

obtaining freshwater

multistage distillation, reverse osmosis

multistage distillation

1. seawater heated; 2. in another container, pressure is lowered and seawater boils rapidly; 3. remaining seawater sent through additional stages, each w/ lower pressure

reverse osmosis

1. semipermeable membrane; 2.seawater subjected to high pressure; 3. water passes through membrane

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set