Explain the term Ceramics ?
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and
subsequent cooling. Ceramic
materials may have a crystalline or partly crystalline structure, or may be amorphous (e.g., a glass). Because most common ceramics are
crystalline, the definition of ceramic is often restricted to inorganic
crystalline materials, as opposed to the non crystalline glasses, a distinction
followed here.
The earliest ceramics made by
humans were pottery objects, including 27,000
year old figurines, made
from clay, either by itself or mixed with other
materials, hardened in fire. Later ceramics were glazed and fired to create a
colored, smooth surface. Ceramics now include domestic, industrial and building
products and a wide range of ceramic art. In the
20th century, new ceramic materials were developed for use in advanced ceramic engineering; for
example, in semiconductors.
Write short note on Water purification ?
Water purification is the removal of contaminants from raw
water to produce drinking water that is pure enough for human consumption or
for industrial use.
Substances that are removed during the process include
parasites (such as Giardia or Cryptosporidium) , bacteria, algae, viruses,
fungi, minerals (including toxic metals such as Lead, Copper etc.), and
man-made chemical pollutants.
Many contaminants can be dangerous—but depending on the
quality standards, others are removed to improve the water's smell, taste, and
appearance.
A small amount of disinfectant is usually intentionally left
in the water at the end of the treatment process to reduce the risk of
re-contamination in the distribution system.
Many environmental and cost considerations affect the
location and design of water purification plants.
Groundwater is cheaper to treat, but aquifers usually have
limited output and can take thousands of years to recharge.
Surface water sources should be carefully monitored for the
presence of unusual types or levels of microbial/disease causing contaminants.
The treatment plant itself must be kept secure from
vandalism and terrorism.
It is not possible to tell whether water is safe to drink
just by looking at it.
Simple procedures such as boiling or the use of a household
charcoal filter are not sufficient for treating 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 is needed.