Chapter 18: Wastewater story

Explanation:

(a) Cleaning of water is a process of removing contaminants or pollutants .

Pollutants are substances or materials that are introduced into the environment and cause harm or discomfort to living organisms or the natural environment. They can be in the form of chemicals, particles, gases, or biological agents, and can originate from human activities, natural sources, or a combination of both. Examples of pollutants include carbon monoxide, nitrogen oxides, sulfur dioxide, particulate matter, lead, mercury, pesticides, and plastic waste.

(b) Wastewater released by houses is called domestic wastewater or sewage.

Sewage is the waste and wastewater generated by households, commercial establishments, and industries. It includes human and animal excreta, used water from toilets, kitchens, and laundry, and other liquid and solid wastes.

(c) Dried sludge is used as manure.

Sludge is the semi-solid or solid residue that remains after the treatment of wastewater, sewage, or industrial effluent. It contains a mixture of organic and inorganic materials.

(d) Drains get blocked by fats and cooking oil.

Explanation:

Sewage is a mixture of human and animal excreta, used water from households, commercial establishments, and industries, and other solid and liquid waste. It is conveyed through underground pipes called sewers to treatment plants where it undergoes physical, chemical, and biological processes to remove pollutants and contaminants before it can be safely discharged into the environment.

Untreated sewage contains high levels of organic matter, pathogens, and other harmful contaminants, including nitrogen, phosphorus, and heavy metals. When discharged into rivers or seas without proper treatment, sewage can cause significant harm to the environment and human health. 

The harmful effects of untreated sewage include:

Water pollution: Untreated sewage can contain high levels of nutrients, such as nitrogen and phosphorus, which can cause eutrophication in water bodies. This process leads to excessive growth of algae and other aquatic plants, depleting oxygen levels and harming aquatic life.

Disease transmission: Sewage contains pathogens, including bacteria, viruses, and parasites, that can cause waterborne diseases such as cholera, typhoid fever, and hepatitis A.

Harm to marine life: Untreated sewage can harm marine life by reducing oxygen levels, increasing acidity, and introducing toxic substances that can cause damage to fish and other aquatic organisms.

Explanation:

Oils and fats should not be released in the drain because they can cause blockages, backups, and damage to the sewer system and treatment plants. Here are some reasons why:

Blockages: Oils and fats can solidify and accumulate in the pipes, leading to blockages and backups in the sewer system. This can cause unpleasant odors, overflows, and costly repairs.

Damage to treatment plants: When oils and fats enter the treatment plants, they can coat and damage the equipment, reducing its efficiency and effectiveness. This can lead to increased operational costs and lower quality treated water.

Environmental harm: Oils and fats can harm the environment by forming a layer on the surface of water bodies, reducing oxygen levels, and interfering with the natural habitat of aquatic life.

Health risks: Blockages and backups caused by oils and fats can lead to unsanitary conditions and exposure to harmful pathogens, putting public health at risk.

Explanation:

Getting clarified water from wastewater involves several steps of treatment, which may vary depending on the specific treatment plant and the quality of the incoming wastewater. The following are the basic steps involved in getting clarified water from wastewater:

Screening: The incoming wastewater is passed through a screening process to remove large objects, such as sticks, rags, and plastics, which can damage the equipment and impede the treatment process.

Primary treatment: In this step, the wastewater is allowed to settle in large tanks, called primary clarifiers, where heavy solids and particles settle to the bottom and form a sludge layer. The clarified water is then skimmed from the top and sent to the next stage of treatment.

Secondary treatment: The clarified water is then subjected to biological treatment in aeration tanks, where bacteria and other microorganisms break down and consume organic matter, such as nitrogen and phosphorus. This process reduces the amount of pollutants and contaminants in the water.

Final treatment: The final treatment involves the removal of remaining suspended solids and pathogens from the water. This is done through additional filtration, disinfection, and chlorination, which ensures that the water is safe for discharge into the environment or reuse.

Explanation:

Sludge is a semi-solid byproduct generated during the treatment of wastewater, which consists of organic and inorganic solids, microorganisms, and other materials. It is separated from the wastewater through various treatment processes, including primary and secondary clarifiers, sedimentation tanks, and sludge thickeners.

Sludge treatment is essential to reduce the volume of the material, remove harmful pathogens and contaminants, and make it safe for disposal or reuse.

The following are some common sludge treatment methods:

Thickening: Sludge is typically thickened to reduce its volume and make it easier to handle and transport. This is usually done through gravity thickening or centrifugation, which involves the separation of solids and liquids.

Digestion: Digestion is a biological process that breaks down the organic matter in sludge and stabilizes it. This process is carried out in anaerobic digesters, which are sealed tanks that allow microorganisms to break down the organic matter and produce biogas as a byproduct.

Dewatering: Dewatering is the process of removing water from the sludge to further reduce its volume and make it easier to handle and transport. This is typically done through mechanical methods, such as belt presses, centrifuges, or filter presses.

Stabilization: Stabilization is the process of treating sludge to reduce its pathogens and other harmful contaminants. This can be done through chemical or thermal treatment methods, such as lime stabilization or heat treatment.

Disposal or reuse: Once the sludge has undergone treatment, it can be disposed of in landfills, incinerated, or used for land application or agricultural purposes as a fertilizer or soil amendment.

Explanation:

Untreated human excreta contains harmful pathogens, including viruses, bacteria, and parasites, that can cause a wide range of infectious diseases. These pathogens can be transmitted through direct contact with feces, contaminated water, or food, and can cause illnesses such as diarrhea, cholera, typhoid fever, and hepatitis A.

In addition to the direct health risks associated with untreated human excreta, there are also environmental and public health implications. The release of untreated human excreta into the environment can lead to the contamination of surface and groundwater sources, leading to the spread of waterborne diseases and polluting natural resources.

Explanation:

Two chemicals commonly used to disinfect water are chlorine and ozone.

Chlorine is a strong oxidizing agent that is widely used as a disinfectant for water and wastewater. It works by destroying or inactivating harmful pathogens, such as viruses and bacteria. Chlorine is commonly added to drinking water at a concentration of 0.2 to 2 parts per million (ppm) to ensure that it is safe for human consumption.

Ozone is a powerful oxidizing agent that is used to disinfect water by destroying harmful pathogens, organic matter, and other contaminants. Ozone is generated by passing oxygen through a corona discharge or ultraviolet light, which creates ozone gas that can be dissolved into water to create a disinfectant solution. Ozone is typically used in water treatment plants to treat large volumes of water, but it is not commonly used in small-scale water treatment due to its high cost.

Explanation:

Bar screens are an essential component of wastewater treatment plants that are used to remove large objects, debris, and other solid materials from the incoming wastewater stream. They function by filtering out large materials that could potentially damage or clog downstream equipment, such as pumps and pipes.

The wastewater entering the treatment plant passes through the bar screen, which consists of a series of parallel bars or rods spaced at a specific distance apart. The bars are arranged in a vertical or horizontal orientation, and wastewater flows through them, allowing water to pass through while trapping larger objects and debris.

Explanation:

Sanitation and disease are closely related, as poor sanitation can lead to the spread of infectious diseases. Sanitation refers to the safe disposal of human waste, garbage, and other waste products, as well as the provision of clean drinking water and adequate hygiene facilities.

When sanitation facilities are inadequate or not available, human waste and other waste products can accumulate in the environment, leading to the spread of disease-causing pathogens. These pathogens can be transmitted through contaminated water, food, or direct contact with fecal matter or other waste products.

Explanation:

As an active citizen, there are several personal roles you can play in relation to sanitation. These include:

Properly disposing of waste: This involves disposing of waste materials in appropriate containers and following local waste disposal regulations. This can include properly sorting recyclable materials from non-recyclable materials, composting organic waste, and ensuring that hazardous waste materials are disposed of safely.

Conserving water: Water conservation is an important aspect of sanitation, as it helps to ensure that water resources are used efficiently and sustainably. This can involve fixing leaky faucets, using low-flow showerheads and toilets, and using water-efficient appliances.

Advocating for improved sanitation: As an active citizen, you can advocate for improved sanitation policies and practices in your community. This can include supporting initiatives to improve access to sanitation facilities, promoting safe waste disposal practices, and advocating for the provision of clean drinking water.

Explanation:

Across

3. Sewage

4. Sludge

6. Sanitation

8. Excreta

Down

1. Wastewater

2. Sewer

5. Bacteria

7. Ozone

Explanation:

The correct statements are:

(ii) (b) and (c)

Explanation:

(a) is incorrect as ozone in high concentration is toxic to living organisms, and it can cause respiratory problems.

(b) is correct as ozone is a powerful disinfectant and is used to kill bacteria and viruses in water.

(c) is correct as ozone in the Earth's stratosphere absorbs most of the sun's harmful ultraviolet (UV) radiation.

(d) is incorrect as the proportion of ozone in the Earth's atmosphere is less than 0.01%, not 3%.