7.1.2. WATER POLLUTION

Hydrosphere in the universe contains water in the form of oceans, rivers, lakes, tanks and many other water sources.

Water sources in the world are of two types. They are (1) Marine water bodies and (2) Fresh Water bodies.

The hydrosphere encompasses all the water found on Earth. It includes vast bodies of water such as oceans, rivers, lakes, and tanks. These sources can be classified into two main types: marine water bodies, which include oceans and seas, and fresh water bodies, which consist of rivers, lakes, and other sources that do not have significant salt content. Understanding these types helps us recognize where water pollution can happen, as different bodies of water may experience unique sources and types of pollution.

Imagine a community located near a lake (a freshwater source) that relies on it for drinking water and recreational activities. If this lake is polluted by runoff from nearby agricultural fields (which can introduce pesticides and fertilizers), it directly affects the health of the community and the ecosystem around the lake.

Chemical examination of water (tests): pH; Biological Oxygen Demand (BOD), Dissolved Oxygen (DO), etc are some of the chemical tests to find the stage of pollution of water.

1. pH: The value of pH gives the degree of acidity or alkalinity of polluted water. Determination of pH is important in calculating the coagulant (thick or thin) dose.

2. Biological Oxygen Demand (BOD): It is defined as the quantity of oxygen utilized by micro organisms at a temperature of 200C, generally measured for 5 days. When water is polluted by unwanted materials, naturally the O content gets reduced and that water becomes not fit for consumption either by human beings or animals or plants.

To assess water quality and pollution levels, specific tests are conducted. The pH test measures how acidic or alkaline the water is, which is critical for determining water treatment methods. BOD, or Biological Oxygen Demand, indicates the amount of oxygen that microorganisms will consume when decomposing organic matter in water over a period (usually 5 days). A high BOD typically means the water has a lot of organic waste, which can lead to low levels of dissolved oxygen (DO), making it unsuitable for aquatic life and drinking purposes.

Consider a pond where leaves and organic matter accumulate. If we measure the BOD, we might find it's very high because all that decomposing material is using up oxygen and making it harder for fish and other aquatic life to survive. It’s like having too many guests at a party; eventually, there isn’t enough food for everyone.

A) Based on sources B) Based on natures A) Based on sources: a) Disease causing agents: Bacteria, viruses, protozoan that enter water from domestic sewage and animal wastes. b) Water soluble inorganic chemicals: Acids, salts and compounds of toxic metals such as Lead, Mercury can make water unfit to drink, harm fishes and other aquatic life. c) Water Soluble Organic chemicals: Oil, gasoline (a type of oil is obtained from petroleum), pesticides, detergents and many other water soluble chemicals that threaten human health and harm fish. d) Heat: Large quantity of water is heated when it is used in the cooling towers of thermal power plants. When this hot water is discharged into the nearby water bodies, it causes an increase in its temperature. e) Sewage: sewage is waste water from municipal area where there is human habitation. Sewage which comes from homes is called domestic sewage.

Water pollutants can be categorized based on their sources and natures. From the source perspective, we have disease-causing agents like bacteria and viruses entering water due to sewage and animal waste, which can lead to illness when consumed. Additionally, inorganic chemicals like heavy metals (lead, mercury) and organic chemicals (like oil and pesticides) pose threats to both human and aquatic life as they contaminate water sources. Heat pollution from industries can also raise water temperatures, harming organisms adapted to specific thermal conditions.

Imagine a river that runs through a city. When it rains, pollution from the streets (like oil and waste) gets washed into the river. If a factory nearby releases hot water from its cooling system into the river, it’s like taking a hot bath in a cold swimming pool—it disrupts the ecosystem, putting fish and other wildlife at risk.

Domestic water pollution leads to Diarrhea, Cholera and Typhoid in human beings.

Polluted water can lead to severe health problems for humans and animals. For instance, drinking water contaminated with pathogenic bacteria or viruses can cause diseases like diarrhea, cholera, and typhoid fever. These illnesses often stem from unsanitary conditions where human waste contaminates drinking water supplies.

In some regions, after heavy flooding, the sanitation systems can break down, allowing sewage to mix with drinking water. This situation is similar to trying to use a dirty sponge to wipe your kitchen table—harmful bacteria can spread, leading to sickness and health crises.

Many industries discharge waste materials containing harmful chemicals. Such Industrial wastes are called effluents. The river Godavari is polluted because of effluents released by the paper industry. It affects the entire water ecosystem causing enormous damage to fishes, prawns and fresh water animals.

Industrial water pollution occurs when factories discharge waste products (effluents) directly into water bodies. This contamination can introduce toxic substances that not only affect aquatic life but can also disrupt entire ecosystems. The example of the Godavari River illustrates how discharges from industries can have far-reaching effects, harming not just fish but the entire food chain dependent on that water body.

Think of a factory that improperly disposes of chemicals into a nearby river. It’s like spilling paint in a swimming pool; it not only pollutes the pool but also makes it unsafe for everyone who wants to swim or fish there. Over time, this can lead to a significant decline in the fish population and alter the balance of the ecosystem.

1. Drinking water should be boiled, cooled and then used.
2. Disinfection of drinking water should be done by using chemicals like bleaching powder.
3. Pesticides and insecticides should be prevented from nearby use of water lakes, ponds and pools.
4. Drainage water should not be allowed to mix with drinking water.
5. Drainage system should be maintained properly.
6. Chlorination process is to be adopted for drinking water. For 1 litre of water 30 - 40 mg of chlorine is to be added to get perfect disinfection.

To combat water pollution and protect public health, several control measures can be implemented. Boiling drinking water eliminates pathogens, making it safer. The use of disinfectants like chlorine helps in killing harmful microbes in water supplies. Keeping pesticides away from water bodies, maintaining drainage systems, and ensuring proper waste disposal are crucial to prevent contamination at the source.

Imagine living in a household where everyone makes sure the kitchen is clean and the food is stored properly to prevent spoilage. Similarly, in communities, taking steps to clean and protect water sources can ensure everyone has access to safe and healthy water. Just like you wouldn’t serve a meal with expired ingredients, we must ensure our water is clean and free from harmful substances.

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