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Class 7 Science Notes Chapter 18 Waste Water Story

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Water is a life-giving elixir. We all consume water, and in the process, we pollute it. The lather-rich water, mingled with oil and other impurities, that drains from sinks, showers, toilets, and laundries is filthy. It's known as wastewater.
Every day, we use water for drinking, bathing, washing clothing, cooking food, washing utensils, flushing toilets, mopping floors, and so on. We cannot imagine our lives without water. Every day, we use a lot of water, which is then discharged into the drainage system.

Wastewater

Wastewater refers to any water that has been used and then discharged from homes, businesses, industries, or other sources. This water may contain a variety of pollutants, including organic and inorganic substances, nutrients, pathogens, and other contaminants.

Wastewater can be classified into different types depending on its source and characteristics. For example, domestic wastewater comes from households and typically contains organic matter and nutrients, while industrial wastewater comes from factories and can contain a wide range of pollutants depending on the type of industry.

Wastewater treatment is the process of removing contaminants from wastewater to make it safe for discharge back into the environment or for reuse. This process typically involves physical, chemical, and biological processes to remove solids, nutrients, and other contaminants from the water. After treatment, the wastewater can be discharged into rivers, lakes, or oceans, or it can be reused for purposes such as irrigation, industrial processes, or even drinking water in some cases.

Contaminants

A contaminant is something that contaminates a substance such as water or food.

Organic impurities

Organic impurities refer to any organic substances that are present in a material or a mixture and can have a negative impact on the quality or performance of that material or mixture.
In the context of wastewater, organic impurities typically refer to organic compounds that are present in the water and can cause environmental and health problems if left untreated.
Some common sources of organic impurities in wastewater include human and animal waste, food processing plants, and industrial processes that produce organic compounds.
To remove organic impurities from wastewater, various treatment methods can be used, such as biological treatment, chemical treatment, and physical treatment.

Inorganic impurities

Inorganic impurities include phosphates, nitrates and metals. Inorganic impurities generally do not contain any carbon, but there are certain inorganic impurities, which contain carbon like carbon dioxide.

These methods work by breaking down or removing the organic compounds from the water to make it safe for discharge or reuse.

Bacteria

Bacteria are a type of single-celled microorganisms that are found almost everywhere on Earth.
They can exist in a wide range of environments, from soil and water to the human body and other organisms.
While some bacteria are harmless or even beneficial, others can cause illness and disease.
In wastewater treatment, bacteria play an important role in the biological treatment process.
Additionally, some types of bacteria are used in industrial processes, such as fermentation in the production of foods and beverages.

Sewage: Who’s That?

Sewage

It is wastewater released by homes, industries agricultural fields and other human activities.
Most of its water has dissolved and suspended impurities called contaminants.
Composition of Sewage The following components make the sewage:The organic impurities present in sewage are human faeces, animal wastes (like animal dung), urea (as urine), oil, fruits and vegetable wastes, pesticides, herbicides, etc.
The inorganic impurities present in sewage are nitrates, phosphates and metals.
The bacteria present in sewage include those bacteria which cause water-borne diseases such as cholera and typhoid.

Saprophytes

Saprophytes are organisms that obtain their nutrients from dead or decaying organic matter.
In wastewater treatment, saprophytes can be important for the decomposition of organic matter.
In the process of biological wastewater treatment, certain types of bacteria and fungi act as saprophytes, breaking down and consuming organic matter in the water.
Saprophytes are also important in agriculture, where they play a crucial role in the decomposition of plant material and the cycling of nutrients.
They can help to improve soil quality by breaking down organic matter and releasing nutrients that can be used by plants.

Wastewater Management

Wastewater management

Wastewater management is the process of collecting, treating, and disposing of wastewater to protect public health and the environment.
It involves a range of activities, including the collection and transportation of wastewater, treatment to remove contaminants, and safe disposal or reuse of treated wastewater.
Effective wastewater management is critical for protecting public health, preventing water pollution, and preserving water resources.
Poorly managed wastewater can contaminate drinking water sources, harm aquatic ecosystems, and spread disease.
The process of wastewater management typically involves several steps, including: Collection: Wastewater is collected from homes, businesses, and other sources through a network of pipes and pumping stations.

Screening

Screening is one of the first stages in the process of treating wastewater.
In this process, the larger objects are removed from wastewater and then moved into the grit and sand removal tank.

Primary treatment is the initial stage in water waste management, also known as wastewater treatment or sewage treatment.
It involves the removal of large solids and suspended materials from the wastewater to make it suitable for further treatment and safe disposal.
The primary treatment process typically consists of the following steps:Screening: The wastewater passes through screens or grates to remove large objects such as sticks, rags, plastics, and other debris.
These materials are often collected and sent to landfills for proper disposal.

Sludge

Sludge Removal: The settled sludge at the bottom of the sedimentation tanks is periodically pumped out and sent for further treatment or disposal. Sludge can be treated through processes such as anaerobic digestion, composting, or incineration, depending on local regulations and available facilities.

Secondary treatment

Water is carried via an aeration lane after basic treatment, when air is tapped into the water to stimulate the growth of aerobic microorganisms.
Bacteria degrade tiny sludge particles that escaped after first treatment.

Sludge that has been activated

The broken down sludge sinks at the bottom of the massive tank known as 'active sludge' after subsequent treatment. It is filled with air.

The final treatment

The activated sludge is processed through a sand drying machine, where it is dried and water is filtered away.
The water is directed to flow over a wall where it is filtered through a sand bed to remove any remaining particles.
This purified water is subsequently discharged into the river.

Sewage Systems

Sewage systems

Sewage systems, also known as wastewater collection systems or sewer systems, are infrastructure networks designed to transport and manage sewage and wastewater from homes, businesses, and industries.
These systems are essential for maintaining public health and protecting the environment by preventing the contamination of water bodies and ensuring proper wastewater treatment.

Better housekeeping practices

Better housekeeping practices refer to adopting habits and routines that promote cleanliness, organization, and safety in residential settings. Implementing better housekeeping practices can help maintain a clean and healthy living environment, prevent accidents, and improve overall well-being. Here are some tips for better housekeeping:

Regular Cleaning: Establish a cleaning routine that includes regular tasks such as sweeping or vacuuming floors, dusting surfaces, and cleaning bathrooms and kitchen areas. Clean up spills promptly to prevent stains and odors. Decluttering: Get rid of unnecessary items and organize belongings to reduce clutter. Donate or discard items that are no longer needed. Use storage solutions such as bins, baskets, and shelves to keep items organized and easily accessible. Proper Waste Management: Dispose of waste properly by using trash bins with lids and recycling bins for recyclable materials. Separate and recycle items such as paper, plastic, glass, and metal whenever possible. Kitchen Hygiene: Maintain a clean and sanitary kitchen by regularly washing dishes, cleaning countertops, and sanitizing kitchen utensils and appliances. Properly store food items to prevent contamination and regularly clean out the refrigerator. Laundry Practices: Establish a routine for washing and folding laundry. Clean dirty clothes regularly, and follow the manufacturer's instructions for washing different types of fabrics. Keep laundry areas clean and well

Septic tanks

Septic tanks are underground structures designed to treat and dispose of wastewater from homes and buildings that are not connected to a centralized sewer system. They are commonly used in rural areas or locations where it is not feasible to connect to a municipal sewer system. Septic tanks provide an on-site wastewater treatment solution.

Class 7 Science Notes Chapter 18 Waste Water Story