[http://en.wikipedia.org/wiki/Water_purification]
1. Water purification is a process of removing undesirable chemicals, materials, and biological contaminants from raw water. The goal is to produce water fit for a specific purpose. Most water is purified for human consumption (
Drinking water) but water purification may also be designed for a variety of other purposes, including meeting the requirements of medical, pharmacology, chemical and industrial applications. In general the methods used include physical processes such as
filtration and
sedimentation, biological processes such as
slow sand filters or
activated sludge, chemical processes such as
flocculation and
chlorination and the use of electromagnetic radiation such as
ultraviolet light.
The purification process of water may reduce the concentration of particulate matter including
suspended particles,
parasites,
bacteria,
algae,
viruses,
fungi; and a range of dissolved and particulate material derived from the surfaces that water may have made contact with after falling as
rain.
The standards for drinking
water quality are typically set by governments or by international standards. These standards will typically set minimum and maximum concentrations of contaminants for the use that is to be made of the water.
It is not possible to tell whether water is of an appropriate quality by visual examination. Simple procedures such as
boiling or the use of a household
activated carbon filter are not sufficient for treating all the possible contaminants that may be present in water from an unknown source. Even natural
spring water – considered safe for all practical purposes in the 1800s – must now be tested before determining what kind of treatment, if any, is needed. Chemical analysis, while expensive, is the only way to obtain the information necessary for deciding on the appropriate method of purification.
According to a 2007
World Health Organization report, 1.1 billion people lack access to an improved
drinking water supply, 88% of the 4 billion annual cases of
diarrheal disease are attributed to unsafe water and inadequate
sanitation and hygiene, and 1.8 million people die from diarrheal diseases each year. The WHO estimates that 94% of these diarrheal cases are preventable through modifications to the environment, including access to safe water.
[1] Simple techniques for treating water at home, such as chlorination, filters, and solar disinfection, and storing it in safe containers could save a huge number of lives each year.
[2] Reducing deaths from
waterborne diseases is a major
public health goal in developing countries.
[http://www.montgomerycountymd.gov/dectmpl.asp?url=/Content/dep/water/wasupPub.asp]
2.A typical public sewerage system starts with wastewater (or sewage) generated in a customer's home or business, which flows through a service connection into sewer mains along the street. The sewage flows in the local mains are collected by progressively larger mains and pumping stations until they reach a wastewater treatment plant. The wastewater system is usually constructed to allow sewage flows to travel downhill by gravity through the system. Wastewater pumping stations are needed to pump into pipelines that occasionally go uphill.
Most of the wastewater generated in Montgomery County flows to a large pipeline that runs parallel to the Potomac River until it reaches the pumping station and the
Blue Plains Wastewater Treatment Plant in Washington, D.C. After the wastewater is treated at the
Blue Plains Wastewater Treatment Plant to a very high level of purity, it is discharged to the Potomac River near the southern tip of Washington, D.C.
3.1. How did you get into this career?
2. Is our cities water clean enough?
