Science 2 Marks Questions

Untreated human excretions are a health hazard. It causes pollution of soil and water including the underground water. Thus, it contaminates the sources of water from which people collect water for drinking and household purposes. When this contaminated water is used for drinking, it can cause diseases such as cholera, typhoid, hepatitis, dysentery, etc., which may even lead to death.

Semi-solids such as faeces that settle down during wastewater treatment are called sludge. This sludge is removed using a scraper and then transferred to a tank where it is decomposed by anaerobic bacteria to produce biogas. This biogas is used as a low-cost fuel for heating, cooking, etc. It is also used to produce electricity.

Oils and fats harden and block the sewage pipes. In an open drain also, fats block porosity of soil which affects its water filtering efficiency. That is why oils and fats should not be released in the drain.

Water is used for:

1. Drinking.
2. Cooking.
3. Washing clothes, utensils.
4. Generating electricity.
5. Bathing.

No, one must always put the waste in a nearby dustbin or carry it home and dispose it in dustbins there. Waste, not properly disposed may enter into the drains and choke them, it also makes public places dirty and unhygienic.

Untreated human excreta is a health hazard because as this will result in poor sanitation. A very large fraction of our people defecates in the open, on dry riverbeds, on railway tracks, near fields and many a time directly in water. It may cause water pollution and soil pollution. Both the surface water and groundwater get polluted. Groundwater is a source of water for wells, tube-wells, springs and many rivers due to this, it becomes the most common carriers for water borne diseases. They include cholera, typhoid, polio, meningitis, hepatitis and dysentery.

Aeroplanes have their closed waste sewage tanks in them, which suck the wastewater and collect it in their tanks.
Once the aeroplane lands on the ground, the crew disposed of the sewage properly into airport sewage facility.

The dirty water which contains various impurities like dust, polythene bags, Vegetable peels, kitchen waste, oil & water that goes down the drains from sinks, showers, toilets, laundries etc. is waste water. Waste water cannot be used further.

Sewage is a complex mixture which contains suspended solids, organic and inorganic impurities, nutrients, saprotrophic and disease causing bacteria and other microbes. The nutrients present in sewage are phosphorus and nitrogen.

Open drain system creates the most unhygienic and unsanitary conditions in its neighborhood. Open dirty water drains are breeding places for flies, mosquitoes and other disease causing organism.

In aeration tanks clarified water is acted upon by aerobic bacteria which remove the suspended solids and dissolved substances, leaving fairly pure water.

The two alternative arrangements for sewage disposal, where there is no sewerage are as below:

1. Septic tanks.
2. Composting pits.

We can minimise waste and pollutants entering the water and create less wastewater by taking following few steps at home:

1. By not throwing used tea leaves, solid food remains, etc., in the drain. We should throw it in the dustbin.
2. By not throwing chemicals like medicines, paints, insecticides, etc., in the drain as they increase the pollution load of the sewage.

The two alternative arrangements for sewage disposal, where there is no sewerage system are as below.

1. Septic tanks.
2. Composting pits.

The Eucalyptus trees are planted along sewage ponds because these trees absorb all surplus wastewater rapidly and release pure water vapour into the atmosphere.

Everyone must know about the adverse effects of poor sanitation. The problem is at its worst in villages, where proper sanitation is not available. Villagers defecate in the open, on dry river beds, railway tracks, fields and even directly in water. This cause’s water and soil pollution. Moreover, it contaminates and affects ground water as well as surface water, resulting in diseases such as cholera, typhoid, polio, meningitis, hepatitis and dysentery.

Yes, we all have a role to play in keeping our environment clean and healthy. All of us can contribute in maintaining sanitation at public places. We should not scatter litter anywhere. If there is no dustbin in sight, we should carry the litter home and throw it in the dustbin.

Accumulation of sewerage leads to:

1. Spread of various diseases.
2. Water pollution.
3. Discharge of sewerage in water bodies leads to excessive growth of algae.

It is a design of toilet in which human excreta is treated by earthworms to be converted into vermicakes which are good for the soil.It is a novel, low water-use toilet for safe processing of human waste.

The waste water that is being generated at homes, industries, agricultural activities, human activities etc. is called sewage. And sewage treatment is a process of removing pollutants before it enters a water body or is refused.

The bacteria decompose the suspended waste that includes domestic wastes & other undesirable organic substances present in the clarified water. The activity of bacteria produces decomposed organic material from which solid waste is separated. This solid waste is used as manure.

Solid Faecal matter which is generated after the water treatment plant is known as sludge. The sludge is transferred to a separate tank where it is decomposed by anaerobic bacteria. The biogas produced can be used as a fuel & the dried sludge is used as manure for replenishing the nutrients of the soil.

Some organisations offer hygienic onsite human waste disposal technology. These toilets do not require scavenging. Excreta from the toilet seats flow through covered drains into a biogas plant. The biogas produced is used as a source of energy.

The terms like ‘sewage’, ’sewers’ and ‘sewerage’ are interlinked with each other because sewage is a mixture of wastewater coming out of homes and other places. Sewers are pipes which carry sewage and sewerage is a network of sewage carrying pipes.

Septic tanks are suitable for places such as hospitals, isolated buildings and clusters of houses where there is no sewage. Local governments or private corporations usually provide septic tanks in areas that have no direct connection to main sewage pipes. The septic tank system consists of a small sewage treatment system. Aeroplanes and trains usually have chemical toilets. A chemical toilet uses chemicals to disinfect human waste and remove its bad odour. That is why trains and aeroplanes do not have elaborate plumbs and sewage.

Open drain is a big concern for the society because they create unhygienic conditions and flies, mosquitoes and other insects breed can spread a number of diseases.

The excreta of animals and humans is collected in a separate tank in a biogas plant. Here it is acted upon by the anaerobic bacteria which produce biogas in the process.

It is an alternative arrangement for sewage disposal to improve sanitation in places where there is no sewage system like in rural areas or in isolated buildings.

1. Bar screen, grit and sand removal tank, first sedimentation tank, aeration tank, second sedimentation tank.
2. First sedimentation tank.

There is a direct relationship between sanitation and disease. Poor sanitation and contaminated drinking water is the cause of a large number of diseases. Under poor sanitation people may resort to defecate in the open, on dry riverbeds, on railway tracks, near fields and many a time directly in water. It may cause water pollution and soil pollution. Both the surface water and groundwater get polluted. Groundwater is a source of water for wells, tube-wells, springs and many rivers due to this, it becomes the most common carriers for water borne diseases. They include cholera, typhoid, polio, meningitis, hepatitis and dysentery.

Fruits and vegetable wastes, pesticides and herbicides are organic impurities present in sewage other than animal wastes, oil and urea.

We can contribute in maintaining sanitation at public places. We should not scatter litter anywhere. If there is no dustbin in sight, we should carry the litter home and throw it in the dustbin. We must realize our responsibility in maintaining the water sources in a healthy state. We should adopt good sanitation practices as way of life. A small initiative as an agent of change on our part will make a great difference.

Cooking oil and fats should not be thrown down the drain. They can harden and block the pipes. In an open drain the fats clog the soil pores reducing its effectiveness in filtering water. Also they may kill microbes that help purify water. Therefore oil and fats should be always discharged after taking due care in the dustbin or if possible in some suitable dumping place.

A manhole is a covered vertical hole in the ground, pavement or road above the underground sewer pipeline. If there is any leakage or blockage in the underground sewer pipeline, the sanitary worker can go down, up to these sewer pipelines for cleaning or any repair.

It is harmful to discharge the untreated sewage into the water bodies as it contains harmful substances. Most of it is water which has dissolved & suspended impurities which may pollute the water bodies & also harm the aquatic plants & animals.

In the last stage of "wastewater Treatment", the treated water has a very low level of organic material and suspended matter. It is discharged into a sea, a river or into the ground. Nature cleans it up further. Sometimes it may be necessary to disinfect water with chemicals like chlorine and ozone before releasing it into the distribution system.

An untreated human excreta is a health hazard as it may cause water pollution. It pollutes both Surface water as well as ground water. Since ground water is a source of water for wells, tube wells etc. therefore it leads to waterborne diseases like cholera, jaundice, typhoid etc.

Sewers are the pipes acting as a transport system that carries sewage from point of origin to the point of disposal. The wastewater released from homes, industries, hospitals, offices and other uses is called sewage.