Wastewater Story Class 7 explains that the provision of safe drinking water is the most fundamental right of any human being. Water covers 71% of the earth's surface, yet only 0.3 per cent of that water is suitable for human use, limiting this vital natural resource.

Water that is unclean and unsafe for drinking causes a variety of water-borne ailments, some of which are fatal. As a result, it is vital to clean wastewater before releasing it into natural water bodies by eliminating impurities and pollutants. This entire process of purifying wastewater is called wastewater treatment, and it occurs in numerous phases.

Sewage means wastewater generated by houses, industries, and enterprises that contains vegetable waste, chemicals, and other potentially dangerous substances. Sewage water is a liquid waste with a high concentration of pollutants and toxins. These pollutants might be both organic and inorganic in nature.

According to Chapter 18 Wastewater Story, there are two types of pipelines in a building or infrastructure. One supplies clean and fresh water to the building and the other gathers wastewater from the building and discharges it into a well-maintained sewage system. It is a collection system that transports wastewater from the site of origin to the point of disposal. A well-maintained sewage network will result in proper sanitation.

According to Chapter 18, a wastewater treatment plant is a facility where polluted wastewater is treated and made fit for use. It cleans wastewater through biological, chemical, and physical process. 

The following procedures are carried out in wastewater treatment plants:

• Water collection
• Medical care (screening)
• Wastewater primary treatment
• Secondary wastewater treatment
• The ultimate treatment of wastewater

The first stage of wastewater treatment plants is collecting wastewater from various sources such as residences, industries, factories, and so on. Wastewater from these sources is collected to treat at a wastewater treatment plant via a network of pipes.

The actual treatment of wastewater begins at this stage. As a result, screening is the initial stage of treatment that removes the large impurities or pollutants. After collecting the wastewater in the previous process, it is then directed to sand and grit removal tanks for treatment.

Some of the better housekeeping practises are discussed below:

1. Chemicals and goods such as paints, pharmaceuticals, and other household items should not be disposed of in drains since they kill bacteria that decompose organic garbage.
2. Household used lard, oils, and toys should not be disposed of in drains since they clog water pipelines.

An alternative arrangement of sewage disposal

The following are some sewage disposal methods:

Septic tanks: They are waterproof concrete containers in which sewage water is collected and allowed to degrade naturally through bacterial activity before being released into the sewers.

Composting toilets for vermin: These are structures where waste such as faeces and other organic waste can degrade utilising earthworms. It is a sanitary, low-cost method of waste treatment.

Sanitation means the proper disposal of human waste, critical in public locations such as trains, bus stops, and hospitals. Severe illnesses generate and spread due to poor sanitation. The government has published some cleanliness regulations in public spaces that everyone must obey.

• Why should oils and fats be not released in the drain? Explain.

Answer: Oils, paints or any fats should not be poured down drains since they harden the soil and cause them to clog. Fats get stuck in the drain's dirt openings and block them. It prevents the flow of water.

• Fill in the blanks

(a) Cleaning of water is a process of removing ____________.

(b) Wastewater released by houses is called ____________.

(c) Dried ____________ is used as manure.

(d) Drains get blocked by ____________ and ____________.

Answer:

1. pollutants
2. sewage
   
   

(c) sludge

(d) Oils, paints, fats

• Untreated human excreta is a health hazard. Explain.

Answer: Human excreta that is untreated poses a health risk because it contains disease-causing germs and contaminants that pollute the land and water resources from which people draw water for drinking and domestic purposes. Cholera, Typhoid, Dysentry, and Hepatitis are illnesses spread by drinking water polluted with human excrement.

• Explain the relationship between sanitation and disease.

Answer: Sanitation and disease are linked because poor sanitation causes sickness while excellent sanitation practises prevent disease.

• Outline your role as an active citizen in relation to sanitation.

Answer: As responsible citizens, we must ensure that our own environmental cleanliness is maintained. People should be made aware of the advantages of sanitation. We should assist local governments in covering any open drains and removing disease-causing material that have been put in them.

Miscellaneous Practice Questions

• What is the story behind the wastewater?

Answer: The term 'wastewater story' refers to the entire process of collecting wastewater and treating it in wastewater treatment facilities to make it fit for human use.

• What are the consequences of wastewater?

Answer: Wastewater comprises vegetable waste, pollutants, and other dangerous substances that, when released, damage our natural water supplies. It can potentially cause severe water-borne infections.

• What exactly is wastewater?

Answer: Wastewater is the liquid waste produced by families, companies, and enterprises, and it contains vegetable waste, chemicals, and other potentially dangerous matter.

• What is the meaning of sewage?

Answer: Sewage is a phrase used to describe liquid waste generated by families and enterprises that contains vegetable waste, chemicals, and other potentially dangerous things.

• What are the three different phases in wastewater treatment?

Answer: The following are the three most important stages of wastewater treatment:

1. Primary treatment
2. Secondary treatment
3. Final treatment

• Explain Sewage and discuss why dumping untreated sewage into rivers or seas is harmful.

Answer: Sewage is used water or wastewater emitted by homes, factories, hospitals, workplaces, and other users. It includes harmful chemicals and organisms that jeopardize human life.

Sewage includes a variety of pollutants, including pathogenic bacteria and other microorganisms. If this polluted water is consumed, it can cause diseases such as cholera, typhoid, dysentery, and others, which can lead to death. That is why dumping untreated sewage into rivers or seas is hazardous.

• Describe the procedures for obtaining clean water from wastewater.

Answer: In wastewater treatment, the wastewater is clarified for further use by going through a number of procedures.

a. To eliminate large particles such as hazardous plastics, bags, clothing, pieces of metal, and so on, wastewater is filtered using bar screens.

b. Water is further filtered using stones, gravel, and sand.

c. The water is then allowed to settle in a big settling tank, where solid excrement known as sludge is scraped away using a scraper.

d. Air is pumped into the cleansed water to aid aerobic bacteria in their growth and waste consumption.

e. This water is then discharged into rivers or ponds.

We examined Wastewater Story in Chapter 18 of Class 7 science, one of the essential topics in science. To summarise, the wastewater story is an important science chapter and a life lesson about the importance of water in our lives and wastewater treatment using various methods.

Students will benefit from the NCERT solutions of this chapter that can be found on the MSVGo app.

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