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WATER POLLUTION Cuyahoga River(1970) : water was so polluted that the river caught fire, causing surrounding buildings to catch fire as well. Fish that were placed in that water would die within minutes. Nowadays, its been cleaned SEWAGE CLEANING - Inadequate Sanitation : Affects 40% of world population. 2 million children die/year because of it. WHO estimates that 80% of all sickness is caused by inadequate sanitation. - Kibera, Africa : Basically no sanitation. Use “ flying toilet” = plastic bags used to poop in and then thrown out. - Dharavi, India : 1 toilet per 1500 residants. Portrayed in “Slumdog Millionaire” - November 19 th = World Toilet Day Poop(organic material) + = CO 2 + Water . Substances like these are called Biodegradable. * Biological Oxygen Demand (BOD) = amount of oxygen a biodegradable substance needs in order to decompose. Amount of dissolved oxygen in water is most when it is COLD(inhibits escape of gases because of low kinetic energy) and FAST MOVING (mixing incorporates O 2 ). Fast flowing rivers => high levels of Oxygen=> Greater Biodegrading. (During the summer, there is not enough oxygen for fish. ..) 3 Levels of Treatment: 1) Primary = Removal of debris and suspended solids by screening and settling. 2) Secondary = Use of biological processes(O 2 + bacteria) to break down organic material and remove additional suspended solids 3) Tertiary (most effective) = Advanced treatment that uses additional filtering or chemical or biological processes to remove specific compounds or materials that remain after secondary treatment. *Essentially all municipal sewers received some form of treatment, but mostly primary. Percentage of municipal sewers that are not treated today is very low(3%), but still only about 20% receive only primary treatment. At least secondary is needed! 40% of municipal sewers in Canada get tertiary treatment. In Montreal : At one point, it had the dirtiest water in North America. 30 years ago, there was no sewage treatment(i.e everything was just dumped in the river). In 1976, the Olympic stadium was built, and a sewage treatment plan was only built in 1984. Today, we have a primary with some secondary treatment. Northern and southern interceptors collect water, and bring it all to the far east of the island.
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