Waste Management & Water Pollution

A circular economy focuses on minimizing waste, reusing resources, and improving efficiency, all of which help lower greenhouse gas emissions and conserve raw materials. ✅ Statement I: Correct By reducing waste and energy use, the circular economy helps cut greenhouse gas emissions. ✅ Statement II: Correct It reduces the need for raw materials through reuse, recycling, and product life extension. ✅ Statement III: Correct It also lowers production waste using efficient and sustainable design and processes.

Many everyday items contain hidden plastics, even if they don’t look like typical plastic products. * ✅I. Cigarette butts – Filters are made of cellulose acetate, a form of plastic. * ✅II. Eyeglass lenses – Usually made from polycarbonate or CR-39 plastic, not glass. * ✅III. Car tyres – Contain synthetic rubber, which includes plastic-based polymers. All three items contain plastic.

Activated carbon is widely used to clean pollutants because of its unique properties and sustainable production methods. ✅ Statement I: Correct. Activated carbon effectively removes pollutants from industrial effluents due to its high adsorption capacity. It’s commonly used in water treatment and pollution control. ✅Statement II: Correct. This is because activated carbon has an extremely large surface area, created by its porous structure, allowing it to trap heavy metals and other contaminants efficiently. ✅ Statement III: Correct. Moreover, activated carbon can be produced easily and cost-effectively from carbon-rich wastes like coconut shells, rice husks, and other agricultural residues, making it an eco-friendly option. Thus, both Statement II and Statement III are correct, and together they explain why Statement I is true.

* Membrane Bioreactors are often discussed in the context of: D. Wastewater treatment technologies. * Membrane Bioreactors (MBRs) combine a membrane process like microfiltration or ultrafiltration with a biological wastewater treatment process. * They are used to improve the quality of treated wastewater and are known for their efficiency in removing contaminants.

* Agricultural residues: These include materials like crop stalks, husks, and leaves. They are a viable source of biomass that can be converted into biofuels, including Sustainable Aviation Fuel (SAF). * Corn grain: Corn grain is a source of sugars that can be fermented to produce ethanol, a biofuel. While ethanol is primarily used in gasoline blends, it can also be further processed into SAF. * Wastewater treatment sludge: This sludge is rich in organic matter. Through processes like anaerobic digestion, it can produce biogas, which can be further converted into SAF. * Wood mill waste: This includes sawdust, wood chips, and bark. These lignocellulosic materials can be converted into biofuels through various thermochemical or biochemical processes, ultimately leading to SAF production. Therefore, all four materials can be used as feedstock for producing Sustainable Aviation Fuel.

* Statement 1 is Correct. PFAS are used in a wide range of consumer products, and due to their persistence, they can leach into the environment and contaminate water sources, food, and packaging materials. * Statement 2 is Correct. PFAS are known as 'forever chemicals' because the strong carbon-fluorine bond makes them highly resistant to natural degradation processes. This persistence leads to their accumulation in the environment. * Statement 3 is Correct. Because PFAS don't break down easily, they can build up in the tissues of animals and humans over time, leading to potential health concerns. _Therefore, all three statements are correct._

Statement-I: Correct. Chewing gums are a source of environmental pollution due to several factors: * Non-biodegradable gum base: Traditional chewing gums often contain polymers like polyisobutylene, polyvinyl acetate, or polyethylene, which do not decompose easily in the environment. * Littering: Discarded chewing gum remains on sidewalks, streets, and other public spaces, creating an eyesore and requiring significant resources for removal. Statement-II: Correct and explains Statement-I * The plastic-like polymers used as gum bases in many chewing gums are the primary reason they are difficult to biodegrade. These polymers contribute significantly to the environmental persistence of chewing gum litter. Therefore, the correct option is (A): Both Statement-I and Statement-II are correct and Statement-II explains Statement-I.

* Statement 1 is correct: Role of Biofilters in Recirculating Aquaculture System (RAS): Biofilters provide waste treatment by removing uneaten fish feed. Biofilters in a RAS help in waste treatment by removing uneaten fish feed and other organic matter from the water. The biofilter media provide a surface for beneficial bacteria to grow, which help in breaking down and removing these wastes. * Statement 2 is correct: Biofilters convert ammonia present in fish waste to nitrate. One of the primary functions of biofilters in a RAS is to convert toxic ammonia (produced from fish waste) into less harmful nitrate. Beneficial bacteria in the biofilter media perform nitrification, a process where ammonia is first converted to nitrite and then further converted to nitrate. * Statement 3 is incorrect: Biofilters do not increase phosphorus as a nutrient for fish in the water. Their primary role is to remove wastes and convert ammonia to nitrate. Phosphorus levels in the water are managed through other means, such as fish feed formulation and water quality management. Therefore, option (B) is the correct answer.

* Statement 1 is correct: Gold mining is poisoning Amazon forests with mercury. To separate the gold, miners mix liquid mercury into the sediment, which forms a coating around the gold. * Statement 2 is correct: Fly ash generated by TPPs is one of the ways mercury is released into the environment. Fly ash is usually disposed of in ash ponds in the form of ash slurry, forming an aquatic ecosystem of its own. Coal-based TPPs are the major source of mercury – the ninth most toxic element found on earth — emissions into the environment. Mercury contributed over 80 percent of emissions released by the TPPs, according to 2016 estimates by the Delhi-based think-tank Centre for Science and Environment. * Statement 3 is incorrect: While mercury is unquestionably toxic, toxicology works on the principle of dose: “The dose makes the poison.” Hence, scientific bodies define reference doses (RfD) or tolerable intake levels, not zero exposure. WHO's Provisional Tolerable Weekly Intake (PTWI) for methylmercury (from fish) → 1.6 µg/kg body weight/week and 1 µg/litre for total mercury in drinking water. If no safe level truly existed: Mercury would be completely banned, not regulated. NOTE: UPSC usually considers extreme statement to be wrong.

* Carbon fibres are highly valued for their unique properties like strength, lightness, and stiffness. They are widely used in the manufacturing of various components in automobiles and aircraft to reduce weight and improve performance.  * Carbon Fiber Recycling: While traditional carbon fibre recycling methods were limited, advancements are being made in this field. Here are some possibilities  1. Mechanical recycling - This process breaks down carbon fibres into smaller pieces for use in applications where their original form is not necessary.  2. Chemical recycling -This method dissolves the resin holding the fibres together, potentially allowing the extraction of reusable carbon fibres.  3. Thermal recycling - High temperatures are used to convert the resin into usable materials while recovering the carbon fibres.  * These recycling technologies are still evolving, but they offer a more sustainable approach to using carbon fibres. Hence, statement 2 is incorrect.