Mar 302013
 

Methods for Purification of Water

Purification of water is a process of removing undesirable chemicals, materials and biological contaminants from contaminated 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. 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 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. 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.

a) Storage: The method for purification of water is storage. Water flowing from any source may contain dust, dirty substance and other unwanted wastes. The water coming from the sources like rivers, springs, streams etc. may be collected in reservoirs where the heavy dust and wastes get settled at the bottom and light one remains floating. This helps to purify water in a large scale. During storage exposure of UV rays from sunlight kills the germs. If the water is stored for 5-6 days about 90% of bacteria are destroyed in the lack of food. During storage aeration process also occurs contributing to purify the water.

b) Filtration:


Filtration process is also the method of purification of water. Water can be purified by applying the filtration process in domestic scale or commercial scale. For domestic purpose, we can use traditional filter or modern commercial filter but for large scale we have to apply slow sand filter or rapid sand filter. During filtration, the minute insoluble particles as well as bacteria are also separated and the filtrate water becomes pure, safe for drinking.

c) Boiling: Boiling is the simplest way for purification of water. It disinfects drinking water from the disease-causing microorganisms such as E. coli, Cryptosporidium and Giardia Lamblia, which are mostly present in lakes and rivers. According to the Wilderness Medical Society, water temperatures above 70 degree Celsius kill all pathogens within 30 minutes and above 85 degree Celsius within a few minutes. It is also observed that a water temperature at 100 degree Celsius kills almost all the microbes, including the enteropathogens (pathogens that cause diseases in the intestine). However, some fungal pathogens such as Clostridium botulinum and other their spores get killed only at 118 degree Celsius. To be on the safer side, it is recommended to boil water for a few minutes for drinking. For cooking, cleaning and bathing purposes, we can use water from water heaters.

d) Distillation: Distillation process can also be taken as the method of purification of water. It involves boiling the water to produce water vapour. The vapour contacts a cool surface where it condenses as a liquid. Because the solutes are not normally vaporized, they remain in the boiling solution. Even distillation does not completely purify water, because of contaminants with similar boiling points and droplets of un-vaporized liquid carried with the steam. However, 99.9% pure water can be obtained by distillation.

e) Chemical Method: Purification of water can be done by the use of different chemicals. Chemically treated water is good for drinking as harmful germs/ micro-organisms are killed by the action of chemicals. While purifying water from chemical process, chemicals like chlorine, potassium permanganate, bleaching powder, etc. can be added in the drinking water. But it is difficult to purify if it contains dirt or bad smell. Spring water and well water can be purified by using potassium permanganate but it is not widely used.

f) Ozone: The process of ozonation is also the best way for purification of water. It is a relatively unstable molecule “free radical” of oxygen which readily gives up one atom of oxygen providing a powerful oxidizing agent which is toxic to most waterborne organisms. It is a very strong, broad spectrum disinfectant that is widely used in Europe. It is an effective method to inactivate harmful protozoan that form cysts. It also works well against almost all other pathogens. Ozone is made by passing oxygen through ultraviolet light or a “cold” electrical discharge. To use ozone as a disinfectant, it must be created on-site and added to the water by bubble contact. Some of the advantages of ozone include the production of relatively fewer dangerous by-products (in comparison to chlorination) and the lack of taste and odour produced by ozonation.

g) Reverse Osmosis: Reverse Osmosis is the mechanical method for purification of water. Mechanical pressure is applied to an impure solution to force pure water through a semi-permeable membrane. Reverse osmosis is theoretically the most through method of large scale water purification available, although perfect semi-permeable membranes are difficult to create. Unless membranes are well-maintained, algae and other life forms can colonize the membranes.

h) SODIS: The natural way for purification of water is SODIS method. Solar water disinfection – the SODIS method – is a simple procedure to disinfect drinking water. Contaminated water is filled in a transparent PET – bottle or glass bottle and exposed to the sun for 6 hours. During this time, the UV – radiation of the sun kills diarrhea generating pathogens. The SODIS- method helps to prevent diarrhea and thereby is saving lives of people. This is urgently necessary as still more than 4000 children die every day from the consequences of diarrhea.

Mar 282013
 

Waste Water Management

waste water management

Water management is the field of handling waste water, to make it suitable to either be recycles into a water system or to be disposed of in an environmentally- conscious manner. Waste water management is one of the larger problems facing most major cities in the modern world, with overflow causing severe pollution problems including water pollution and increasing population densities stretching existing infrastructure to the breaking point. Both mechanical and biological processes are utilized in water waste management, to get rid of undesirable particulate matter and to eliminate any potentially harmful pathogens.

Sources of waste water and their management

Cleanliness
We use water for cleaning purposes. In our daily life, water is used for bathing, washing clothes, cleaning utensils, washing fruits, vegetables or other edibles, cleaning floors and many more. The waste water produced after these cleanliness activities is contaminated with dust, germs, soap, detergent etc.


Waste water produced in this way should be collected separately in a pit and should be purified using effective technologies. This waste water can even be utilized for watering the plants in the garden.

Health Centers
Water is used in hospitals, health centers and research centers as a solvent and cleansing agent. Waste water produced from such places get contaminated with different germs, pus, blood, sputum, stool, urine and many chemicals. Waste water produced from such places should not be discharged into the drainage directly. It should be collected separately and treated properly to reduce its hazards on environmental health.

Industries
Water is widely used in industries related to various products. Water is usually used as a solvent, cooling agent or cleansing agent in industries. Waste water from industries contains different chemicals and dissolved or suspended solid particles. Waste water from industries should not be discharged into water bodies or drainage pipes without treating them. The solid wastes are to be filtered and chemicals are to be treated well before discharging.

Agriculture
Water is used for irrigation in agricultural fields. Water runoff from agricultural fields contains soil particles and washed out chemicals which have been used in different forms like insecticides, fertilizers etc. A proper drainage system is to be managed for agricultural runoff. Waste water from agricultural field should be discharged safely far from settlement areas and water resources like well, pond, lakes etc.

Hotel and Lodge
Waste water is also generated in hotels, lodges and restaurants. Waste water from such places mainly contains ash, soap, dust and remains of food beverages. It may lead to unhealthy environment if not managed properly. We need to pass out the waste water from these places to the drain pipers using suitable mechanism.

Residential areas
More amount of waste water is produced from residential areas. Water from kitchen, bathroom, toilet, yard etc. has become a major source of pollution in urban and rural areas. Waste water from residential areas should be properly treated before discharging it. Each and every family must be aware and committed for the collection or discharge or waste water in a fixed place or into the drainage pipes. Provision of reward and punishment also helps in the management of waste water in community.