Remedies for water pollution
Aftab Chowdhury
Water is another name for life, on which every physiological process depends. If we discuss the smallest unit of a living organism, the cell, we can easily understand that water plays a major role in the lives of plants, animals and birds. But when its concentration and normal physical or chemical properties change due to natural or human causes, it is no longer usable or fit for drinking and becomes polluted. This means drinking water is free from germs and chemical substances harmful to human health. Although, in the true chemical sense, it is not completely pure, various types of gases or minerals are naturally mixed with it in some form. However, these substances are present in such small quantities that they do not cause any deviation from its normal properties and do not cause harm when the water is used for drinking. On the other hand, when the amount of such pollutants increases, water becomes polluted and unfit for use, exerting harmful effects on the entire living world.
From another perspective, it can be seen that in urban and suburban areas, drinking water is collected directly from rivers, lakes, seas and oceans after various filtration processes. These sources are often polluted for various reasons. Microbial contamination is a major cause. Such contamination of drinking water can occur through microorganisms living in soil, microorganisms present in the air, as well as waste discharged from various health services. The first of these is one of the major causes, and germs responsible for various infectious diseases enter drinking water in one way or another. Among the human disease-causing germs that frequently contaminate water, typhoid, paratyphoid, jaundice, poliomyelitis and viral hepatitis are prominent. In addition, several types of microorganisms are found in soil and air, particularly those that cause various diseases in plants and animals.
The condition of disease-causing microorganisms in water mainly depends on dissolved nutrients, the aquatic environment, and the number and nature of other microorganisms. Different types of microorganisms are found in shallow water bodies because of the abundance of nutrients. The nature of microbial problems also varies in different parts of flowing rivers and other water bodies. Drains containing various dirty materials have a high number of infectious microorganisms, which cause various diseases.
The question, therefore, is how safe this water is for human use. This is measured by biological oxygen demand, or BOD. In other words, when the amount of dissolved oxygen required by aerobic microorganisms to decompose and break down various waste materials is relatively low, the water is considered polluted. BOD levels therefore depend on the amount of waste materials. The greater the amount of waste, the higher the BOD level and the lower the level of dissolved oxygen.
The major groups of microorganisms found in polluted water are algae, fungi, bacteria and protozoa. They cause decomposition in various ways. Among them, bacteria can multiply even in the presence of very small amounts of nutrients and decompose organic matter, ultimately causing changes involving various gases such as carbon dioxide and altering various physiological processes of microorganisms, making the water unfit for use. Other microorganisms such as algae, protozoa and fungi change the taste and odour of water in various ways and make it unsuitable for use. Among the serious disease-causing germs transmitted through water are Shigella dysentery, Salmonella typhimurium causing gastroenteritis, Vibrio cholerae causing cholera, Salmonella paratyphi causing paratyphoid, and E. coli causing infantile diarrhoea. If we discuss drinking-water pollution and the spread of disease-causing microorganisms in this region in detail, we will see that a large number of infectious diseases are transmitted through polluted water. These include typhoid, bacillary dysentery, amoebic dysentery, giardiasis, cholera and gastroenteritis.
A major cause of drinking-water pollution is the excretory matter of living organisms, which causes various microbial diseases. Bacteria such as coliform bacteria, streptococci and clostridia enter water in various ways. The presence of any such microorganisms makes water unfit for use. Therefore, such microorganisms must be removed from or destroyed in water by any means possible. Various methods are currently used to purify drinking water. Among the purification processes, copper sulphate can be used to prevent algae-related pollution. Sometimes sodium or calcium chloride can be mixed with water for purification. Although this is somewhat more expensive, it does not alter the taste.
During the rainy season, water is usually somewhat turbid, and alum or aluminium sulphate should then be used. The Department of Public Health Engineering mainly uses three stages for purification: sedimentation, filtration and chlorination. Since infectious disease-causing microorganisms are present in the environment in daily life and water acts as a carrier, some improvements to these methods are necessary. For example, various new filters have been developed for filtration and can be used at water-supply centres in urban and suburban areas to protect people from the risk of various life-threatening microbial diseases. Chlorination should also be carried out properly so that no microorganisms remain alive.
Various surveys have shown that the country’s most polluted rivers include the Buriganga, Shitalakshya, Karnaphuli and Surma. They contain various chemical substances such as cadmium, chromium, lead, mercury and arsenic, as well as small amounts of radioactive substances. These chemical or radioactive substances cause various serious diseases and can even cause life-threatening diseases such as cancer.
Water pollution can be prevented in various ways. First, wastewater from laundries, toilets and bathrooms should be scientifically disinfected before it mixes with various sources such as rivers, canals, ponds and springs. Second, since the number of various microorganisms may increase during the rainy season due to higher concentration levels, an appropriate amount of bleaching powder should be used. Third, various types of urban waste and industrial waste should not be allowed to mix directly with water and should be treated scientifically. Fourth, wastewater from various sewerage systems should be treated through cycling and recycling methods. Fifth, various infectious microorganisms such as Clostridium, Micrococcus, Lactobacillus, Streptococcus and various Enterobacteria enter water in different ways.
Therefore, scientific waste-disposal systems are necessary for treating waste and keeping water clean. Sixth, the use of harmful metals and chemicals by factories and industrial establishments should be reduced, and the government should impose various restrictions where necessary. Seventh, urban drainage systems should be extensively reconstructed scientifically, and toilets and washing facilities should be established at designated locations. Eighth, since rivers are the main source of drinking water in this region, their pollution must be strictly prevented through various measures.
It is essential to cut off the connection of any drains carrying dirty waste or tributaries with the river for several kilometres upstream from the point where water is collected for drinking-water supply. At the same time, nearby residents and city dwellers should be made aware of drinking-water pollution. Finally, people should be made aware of any form of drinking-water pollution. Because, many times, we ourselves unknowingly act as major polluters.
Author: Journalist and columnist
