Man's Effect On The Enviroment

10 Pages 2555 Words

ly treated wastewater for, irrigation of non-edible crops, industrial processing,
recreation, and other uses. In one such project, the Potable Reuse Demonstration Plant in
Denver, Colorado, the treatment process uses normal primary and secondary treatment followed
by lime clarification to remove suspended organic compounds. During this process, an alkaline
state is created to improve the process. In the next step, re-carbonation is used to bring the pH
level to neutral. Then the water is filtered through several layers of sand and charcoal, and
ammonia is removed by ionization. Pesticides and any other dissolved organic materials still
present are absorbed by a granular, activated-carbon filter. Viruses and bacteria are then killed
by ozonisation. At this stage the water should be cleansed of all contaminants, but, for added
reliability, second-stage carbon absorption and reverse osmosis are used, and chlorine dioxide is
added to obtain the highest possible water standard.

The other main place that effluent is disposed of from is industry. Industrial plants put
their waste into the main drains, because they pump it into the main drains it has to be a
particular pH i.e. neutral (between pH6 and pH10). If the pH fluctuates out of this range, there
are valves along the main pipe line from the industrial works that close to prevent the effluent
leaking into the main sewage system. The pH can then be regulated by either adding caustic soda
(an alkaline) or hydrochloric acid to neutralize it again. If the valves did not close and the
effluent were allowed to travel into the sewage works then it would kill all the nitrifying and
denitrifying bacteria that break down the waste. The bacteria are very sensitive to the chemicals
that are used and if these levels fluctuate too much, it will kill the bacteria and the whole
decomposition process will be affected. The bacteria remove the ammonia in the efflu...