Chapter 2 Social Pharmacy Notes 2.1 Demography and Family Planning, 2.2 Mother and child health, 2.3 Importance of breastfeeding, 2.4 Ill effects of infant milk substitutes and bottle feeding 2.5 Overview of Vaccines, 2.6 Types of immunity 2.7 Immunization 2.8 Effect of Environment on Health 2.8.1 Water pollution 22.214.171.124 Importance of safe drinking water, waterborne diseases 2.8.2 Air pollution 2.8.3 Noise pollution 2.8.4 Sewage and solid waste disposal 2.8.5 Occupational illnesses 2.8.6 Environmental pollution due to pharmaceuticals 2.8.7 Psychosocial Pharmacy: Drugs of misuse and abuse – psychotropics, narcotics, alcohol, tobacco products.
Table of contents
Water pollution is defined as the contamination of water resources such as lakes, rivers, groundwater, ocean etc.
It is the water with altered taste, or water having smell or colour.
Sources of water pollution
- Sewage- its waste water which contains decomposable organic matter and pathogenic microorganisms.
2. Industrial and trade waste which contains toxic chemicals
3. Agricultural pollutants which contain pesticides and fertilizers
4. Physical pollutants like radioactive substances
5. Usage by human beings for animal washings, bath, washing of cloth etc
Prevention and control of water pollution
- Purification of water. On a small scale, purification methods are boiling, use of filters, use of chlorine tablets/solution etc. and large scale purification is either Slow (Biological) Sand filtration or Rapid (Mechanical) sand filtration methods.
- Avoiding water pollution by protecting water sources from industrial and trade waste, agricultural pollutants, physical pollutants and from washing of animals, bath by humans etc.
Purification of water on a small scale
Small scale purification of water:
Four different methods are generally available. These methods can be used alone or in combinations.
a) Boiling: – Boiling the water for 5 to 10 minutes is a satisfactory method of purifying water for household purposes. It kills bacteria, spores, cysts, ova and yields sterilized water. It also removes temporary hardness. Water should be boiled preferably in the same container, in which it is to be stored to avoid contamination during storage.
b) Chemical Disinfection:-Various chemical disinfectants are used. Bleaching powder OR Chlorinated lime:-It has 33 percent of available chlorine. It is used to disinfect water. The principle of chlorination is to ensure“free” residual chlorine of 0.5mg/litre at the end of one hour of contact. Other agents used: chlorinated solution, chlorine tablets (halo zone), high test hypochlorite (HTH) which is a calcium compound called as perchloron, containing 60-70% available chlorine, Iodine. Potassium permanganate
- Filtration: – Household water can be purified with the help of ceramic filters like Pasteur Chamber land filter, Berkefeld filter and Katedyn filter. These filter candles usually remove bacteria found in drinking water but not filter passing viruses. Apart from candle filters, on-line filters with bacteria retentive capacity are available which may be incorporated in the water line or fitted to the tap.
d) Disinfection of wells: – Wells are the main source of water supply in rural areas. The most effective and cheapest way of disinfecting wells is by bleaching powder or chlorinating the wells by shock chlorination.
Methods of Large Scale Purification of Water
1. Biological or Slow Sand filtration
2. Mechanical or Rapid Sand Filtration
“Slow Sand Filtration” :
Slow sand filtration is a method that uses supernatant raw water, a bed of graded sand, and under drainage system and filter control valves. Under ideal conditions, the filter reduces the bacterial count by 99.9 %. The steps of a slow sand filter are as follows:
1. Supernatant raw water: The supernatant water above the sand bed measures in-depth 1-1.5 meters. It provides an opportunity for natural purification by oxidation and sedimentation; secondly, water is forced by gravity downwards to facilitate filtration.
2. Graded sand bed: The sand bed is the most important component as this is filtering the water. This consists of sand of different particle sizes and thicknesses.The finest sand is on the top and comparatively coarse sand is below that. Water percolates through the beds very slowly and during this is subjected to mechanical straining, sedimentation, adsorption, oxidation and bacterial action. This filter is called a biological filter because the surface of the sand gets covered with slimy growth called as (vital layer/ schmutzdecke layer/ zoogleal layer/biological layer), which consists of thread-like algae and numerous forms of life including plankton, diatoms and bacteria. This vital layer removes organic matter, holds back bacteria and oxidizes ammoniacal nitrogen into nitrogen and helps in yielding bacteria-free water
3. Gravel support: Below the sand bed is the layer of gravel that supports the sand bed. The upper part consists of fine gravel and the lower part is coarse gravel.
4. Under drainage system: Just below the coarse gravel there is a network of porous or perforated pipes.
5. A system of filter control valves: All the above components are placed inside a box called a filter box. The walls of the box are made of stones, bricks or cement. The whole filtration process is controlled by filter control valves so that filtered water is available at a desirable rate.
Rapid sand filtration :
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