LC Chem 9.3 Water Treatment and Analysis
Terms in this set (20)
Sedimentation, Flocculation, Filtration, Chlorination, Fluoridation, pH adjustment
Water is pumped into the bottom of tanks and rises up towards the surface very slowly to allow particles to settle at the bottom of the tank.
Very small suspended solids in the water are removed by being made to form larger particles by adding flocculating agents (aluminium sulfate) to the water.
The water from the top of the settlement tanks is passed through large beds of graded sand and gravel to remove any remaining suspended solids.
Chlorine is added to the water in order to sterilise it (to get rid of any harmful micro-organisms).
Fluorine is added to water because it has been shown that the presence of fluoride ions in water helps to reduce dental decay by strengthening the enamel of teeth.
This is raised by adding calcium hydroxide (lime) or lowered using dilute sulfuric acid or carbon dioxide to reach a value of 7-8.
Effect on the solubility of gases in water with an increase in temperature
What happens when so much organic waste is present that it reduces the dissolved oxygen level in the water
The release of substances into the environment that damage the environment
A high B.O.D. indicates that this is the condition of the water
The enrichment of water with nutrients such as phosphates and nitrates, which leads to excessive growth of algae.
Nutrients in fertilisers which pollute waterways when the run-off of from farmland leaks into rivers or lakes
Metals such as lead, mercury and cadmium which are cumulative poisons and can cause water pollution
Term used to describe the material delivered to waste treatment plants of towns and cities
Physical Process involving screening and settlement. Removes about one half of the suspended solids and removes about one third of the B.O.D. in the sewage.
Biological Process which reduces the levels of suspended and dissolved organic materials by bacterial breakdown using the Activated Sludge Method. Removes about 95% of the B.O.D. of the original sewage.
Chemical Process which removes phosphorus compounds (by precipitation with aluminium sulfate) and nitrogen compounds (by biological nitrification) from sewage
A technique whereby white light is passed through a coloured solution and the colour of the solution is then compared with the colour of solutions of known concentrations of that substance
Uses of Colorimetry
Analysing water for presence of chlorine, lead, nitrates and phosphates