Solid Waste Management Exam Questions 2023-2024 PDF

Solid Waste Management Exam Preparation Questions WS23/24 1. What is waste? What are the primary drivers for municipal solid waste management? Waste (or wastes) are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-prod...

Solid Waste Management Exam Preparation Questions WS23/24 1. What is waste? What are the primary drivers for municipal solid waste management? Waste (or wastes) are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor economic value. A waste product may become a by-product, joint product or resource through an invention that raises a waste product's value above zero. Examples include municipal solid waste (household trash/refuse), hazardous waste, wastewater (such as sewage, which contains bodily wastes (feces and urine) and surface runoff), radioactive waste, and others. Source: Wikipedia. UN definition: materials that are not prime products (that is, products produced for the market) for which the generator has no further use in terms of his/her own purposes of production, transformation or consumption, and of which he/she wants to dispose. Wastes may be generated during the extraction of raw materials, the processing of raw materials into intermediate and final products, the consumption of final products, and other human activities. Residuals recycled or reused at the place of generation are excluded. Primary drivers of solid waste management in the developed countries are: 1. Environment Protection: To mitigate the effects of climate change. Local environment: To solve the issues of disposal and treatment of the waste generated in the city. 2. Public health: Accumulation of waste at places creates hazardous environments and spreads diseases. 3. Resource value of the waste: Waste can be recycled or reused to generate useful outputs. Efficient waste management conserves natural resources by reducing the need for raw materials. 4. Institutional drivers: Regulations and legislation, infrastructure development, international agreements, capacity building and education. 2. Draw the waste management hierarchy pyramid. 3. Name the three solid waste types, at least 5 of solid waste sources, the generator and composition from at least 3 solid waste sources. Which source and which region is the biggest waste generator worldwide? 3 types of solid wastes are: Industrial, Municipal Solid Waste and Hazardous Solid Waste. 5 solid waste sources are: residential, industrial, commercial, medical waste, institutional, construction and demolition, agriculture, etc. For residential: the generators are Single and multifamily dwellings, and it is composed of food waste, paper, textiles, plastics, e-waste. For construction and demolition: the generators are new construction sites, as well as repair/renovation/demolition sites. And it is composed of wood, concrete, steel, brick, tiles, etc. For medical waste: the generator is mainly hospitals. And the waste is composed of infectious waste, hazardous waste, even radioactive waste. For industrial: the generators are light and heavy manufacturing, fabrication, construction sites, power and chemical plants. And it is composed of housekeeping waste, packaging, food waste, construction and demolition materials, hazardous waste, ash, special waste. For Commercial / Institutional: the generators are com: stores hotels, restaurants, markets / inst: schools, hospitals, prisons, government buildings, airports. And it is composed of paper, cardboard, plastics, wood, food waste, glass, metal, special waste, hazardous waste, e-waste. The biggest waste generator region is “East Asia and the Pacific”. The biggest source of waste is food and green waste (44%). 4. Name 4 types of hazardous waste and 4 types of non-hazardous waste. Hazardous: radioactive waste, electronic waste, medical waste, industrial waste. Non-hazardous: organic waste, packaging waste, other materials (glass, plastic, metal), other non-hazardous industrial waste. 5. What does municipal solid waste include and what is excluded? It includes organic waste, bulky waste, packaging waste and other materials such as glass, plastic, metal etc. In general, municipal waste is composed of waste from household and waste similar in nature and composition to household waste. However, it excludes municipal sewage waste, hazardous waste and municipal construction and demolition waste. 6. What are the 3 main elements of waste management? Name three waste management challenges. 3 main elements: collection (from households and street cleaning), transportation, and treatment + disposal. 3 challenges: Financial Constrains Public awareness Technical Constrains Economic Constrains 7. What factors influence waste management? Accessibility for Waste Collection Public Awareness  Legislation and Regulation Composition and Amount of Waste 8. Describe the advantages and disadvantages of decentralized and centralized solid waste management institutions. Local/ decentralized Macro/ centralized Advantages Disadvantages Adv Disad Common practice Better coordination Efficient resource usage Redundancy in In most cases functions Dedicated Coordination across managed by Minimization and government units to multiple institutions with comprehensive combat illegal departments broader addressing of gaps dumping or littering responsibilities in service Enforcement of policies and regulations 9. What are the different administrative model systems for solid waste management? List and define the types of contractual arrangements for solid waste management. Why is it beneficial to form partnerships with the private sector? The different administrative models for solid waste management are: 1. Decentralized 2. Intermunicipal 3. Municipal 4. Mixed Public Private 5. Other (Private, Non-Governmental, or no formal administration) The types of contractual arrangements are: 1. Municipal Service: a private operator will provide municipal solid waste management services. 2. Concession: the Government grants a private firm the right to provide waste management services in exchange for profits. 3. Franchise: governments outsource waste collection and disposal services to a private player for a long-term. A large portion of the waste management assets are owned by the private player in this arrangement. 4. Lease: The public assets for waste management are leased to a private firm by the municipality. 5. Management: Municipality hires a private operator to oversee the public waste management facilities. 6. Other Public-Private Partnerships. Technical expertise, efficiency, financial investment: Private sector can invest their capital and manpower to carry out the respective waste management activities with motivation to earn profits. This provides efficient operation and fast decision making. It also partly relieves the pressure of finance supply on the municipalities. The municipalities can then focus on the enforcement of regulations and laws for waste management in a better manner and without any conflict of interest. The private sector also brings in technical expertise for better waste management. 10. Name five challenges in waste management financing. 1. Collection/Transport: Low collection rate, inefficiency 2. Generation: High growth rate of waste generated 3. Energy recovery: Landfill gas to energy systems non-existent or in poor conditions 4. Disposal: Large use of insanitary dumpsites and open burning 5. Recycling/organic diversion: lack of integration of the informal sector 11. What is the extended producer responsibility program? EPR: “Polluter pays principle” – shifting the responsibility and financial cost of the negative environmental impacts to producers. 12. What is “Results-based financing” in solid waste management? It is a financial mechanism through which the payment for solid waste services is conditioned to the achievement and verification of pre-agreed targets. 13. Describe the pickup system and the drop-off system. Pick up: the containers are placed near households. Street collection: This is used for bulky and bundle waste collection, etc. Central collection point for paper, glass, light packaging waste, organic waste, multiple chamber-depot-container. Drop-off: the containers are placed at central locations. This uses bulky refuse containers for glass paper, light packaging, waste organic waste, etc. Additional containers for recyclable materials and presorting containers or bags. 14. Why is it necessary to have pretreatment? What are the main differences in pre- treatment for the types of collected waste? Chat GPT: Pretreatment of solid waste refers to the processes applied to waste materials before they undergo final disposal, recycling, or treatment. The goal of pretreatment is to modify the physical, chemical, or biological characteristics of waste to make it safer, more manageable, or more suitable for further processing. Pre-treatment is essential in solid waste management because it helps:  Reduce Environmental Impact. Enhance Recycling & Resource Recovery. Improve Waste Disposal Efficiency. Preventing Hazardous Contamination. Main differences in pretreatment for the types of collected waste: Waste Composition: The type and proportion of materials in the waste determine the appropriate pretreatment methods. End-Use or Disposal Method: Pretreatment is tailored to the final treatment or disposal method (e.g., recycling, incineration, landfilling). Regulatory Requirements: Compliance with local and international regulations influences pretreatment practices. 15. What is a waste transfer station? What is the purpose of a waste transfer station? It is a technical facility used for accumulating and reloading the waste from collection trucks, onto larger container and long-distance transport vehicles for shipment (by road, railroad or ship transportation) to landfills or other treatment plants. Purposes: 1. Save money on the labor and operating costs of transporting the waste to a distant disposal site. 2. Recovering recyclable items and taking them out of the waste stream. 3. Preventing hazardous waste from ending up in a landfill, which limits chemical pollution and future soil contamination. 4. Doubling as a drop-off center for residents to take bulk items or recycle. 5. Delivering fuel savings and reducing road wear since garbage trucks run shorter routes with lighter loads. 16. What are three benefits of recycled materials? What is a big threat for the secondary materials market? Benefits: 1. Competing with and displaces the use of primary materials. 2. Helps reduce the extraction of virgin material resources. 3. Reduce greenhouse gas emissions. The biggest threat of the secondary materials market is the price volatility. 17. List the seven steps of the scrap metal recycling process. Name the seven steps of paper recycling. Scrap metal recycling process Paper recycling Step 1. Collection of materials Collection Step 2. Sorting Sorting and Screening Step 3. Crushing and shredding Shredding and pulping Step 4. Melting De-inking Step 5. Purification Drying Step 6. Solidifying Rolling Step 7. Reuse Recycled paper to market 18. What are four technologies for plastics recycling? Describe two of them. Name two types of plastic that are problematic and/or not commonly recycled and their problematic. Technologies: 1. Mechanical: transforms materials into “new” secondary raw materials without changing the base molecular structure of the material. Collection + Sorting + Washing + Shredding + Identification and Separation + Extruding and Compounding 2. Chemical recycling: breaks down polymers into their building blocks, it also allows the production of recycled plastic (recyclate) with virgin plastic properties that can be used in demanding applications, such as food contact. 3. Dissolution: is based on using a solvent that dissolves one polymer and not another or additives. By means of dissolution, we separate different polymers and carry out one or more purification steps. 4. Organic recycling: aerobic treatment (industrial composting) or anaerobic treatment (biogasification) of packaging waste. 2 types of plastic not commonly recycled: PS Polystyrene: rarely recycled due to it not being cost-effective. PP Polypropylene: is often rejected by processing centers due to the problems it poses, making the rate at which it is recycled far lower than other plastics. 19. Name the steps of the glass recycling process. Name 3 glass recycling challenges. Step 1: Collection and transportation Step 2: Sorting Step 3: Breaking Step 4: Screening Step 5: Bed drier fluidization Step 6: Primary screening and pulverization Step 7: Secondary screening Step 8: Glass Cullet Step 9: New products Challenges in glass recycling, mainly relates to raw material substitution: 1. To produce white container glass, a color purity of 99.7% is required with an addition of 50% waste glass cullet. 8% of off-colors for amber glass and 15% for green glass are allowed. 2. For flat glass industry, special quality requirements such as color purity and freedom from bubbles. 3. For the flat glass industry, used glass that does not meet the specified purity requirements must be processed. 20. Why is E-waste potentially hazardous? Because of lead-containing glass, plastics treated with brominated flame retardants or ozone- depleting substances such as CFCs. 21. How is waste separated and recycled in Germany? (max. 5 sentences) Glass recycling: white glass, brown glass, and green glass. Packaging (Yellow bin): plastic, tetra packs, Styrofoam, aluminum, and packaging. Refundable “Pfand” recycling. Biodegradable (brown or green bin): Raw food scraps and peels, cooked food leftovers, tea bags, coffee, eggshells, and garden waste. Paper (blue bin): clean paper products, newspapers, magazines, paper and card packaging, books, and notebooks. Hard Rubbish: Furniture, wood beams or boards, kitchen sinks, toilets, beds and mattresses. Hazardous Waste Recycling: Batteries, chemicals, and paint. Recycle Used Clothing and Shoes. 22. Sketch the waste management hierarchy pyramid, explain each step, and indicate which are the most and least desirable options Solid Waste Management 23. What are at least two must haves for a landfill? What are the aftercare measures of a landfill? What are the 2 main emissions of a landfill? Must-haves: 1. an underground that should have a maximum permeability of 10-6 cm/s in an undisturbed state (underground protection) 2. adequate distance to the groundwater table 3. a basis with a sealing and drainage layer according to the type of waste Aftercare measures: 1. Securing the area 2. Regular inspections (in annual and six months-intervals) 3. Monitoring of the wells and other control systems. Two main emissions from a landfill are leachate and landfill gas. 24. What should the dimensions of the operated deposit area of a landfill be? How many years of control and aftercare does a sanitary landfill need? Give three examples of materials that go to a hazardous waste landfill. Operated deposit: depending on the overall size and the daily input, the operated deposit area should not exceed 2000m2 for a small to medium sized landfill and 8000m2 for large landfills. Control and aftercare: unpredictable behavior of the deposit requires a long and permanent control for at least 20-30 years after closure of the landfill and aftercare about 80-100 years after closure of the landfill. Materials that go to hazardous waste landfill: contaminated industrial material (ashes, sludge, etc), waste oil, old paint and lacquer, or organic waste. 25. What are the four thermal waste treatment processes? What are the 3 pyrolysis products and operation temperature? Thermal waste treatment processes: 1. Co-incineration: conversion to ash and gas emissions. 2. Stabilization by drying processes: reduction of water content and pathogens. 3. Gasification: products syngas, slag, and metals. 4. Pyrolysis: at low temperature and absence of oxygen. Products syngas, tar, and coke. Temperatures: from 150-900 degree Celsius. 26. Give 5 comparisons between combustion, gasification and pyrolysis. Combustion Gasification Pyrolysis Volume reduction 75-90% 90% 50-90% Sophistication of High Medium Medium pollution control Products Heat only, electricity Syngas Liquid Fuel only, or both (CHP). Application in Recovering the costs India has one of the Low - not developing countries of an MSW EfW world’s largest established yet, plant in low- to programs for small even in developed medium- income gasification. countries countries is difficult. Appropriate scale of Centralized large Small, medium, and large scale plants scale is the more configurations are available. common and preferred option. Economies of scale allow for higher standards of emissions control and higher energy efficiency. 27. What are the two types of biological treatment? Mention the benefits of composting. What’s the appropriate C:N ratio for compost? Types of biological treatment: 1. Composting (aerobic conditions) 2. Anaerobic digestion and composting Benefits of composting: 1. Adresses organic fraction, which is a large percentage of MSW 2. Produces compost with value as soil improver and fertilizer. Completes biological material cycle 3. Compost serves as soil conditioner, mitigates erosion and is used in land reclamation and as a final cover for landfills 4. Low costs per tonne For compost, C:N ratio= 3:1 28. What is compost like output? Can it be used for food production? What feedstocks can be used for anaerobic digestion? What are some uses for the anaerobic digestate? Compost-Like Output (CLO): (CLO) refers to the material produced from composting processes when mixed waste (such as waste from a Mechanical Biological Treatment (MBT) plant) is used as the feedstock. Unlike high-quality compost derived from clean, source- separated organic waste, CLO is considered a lower-grade product due to potential contamination and is subject to stricter regulations. It is typically restricted to non-food applications. Feedstocks for anaerobic digestion: manure (e.g. dairy, swine, beef, poultry), Wastewater Biosolids (e.g. municipal sewage sludge), food waste, other organics (e.g. energy crops, fats, oils, grease, crop residue, winery/brewery waste). Digestate: Digestate is the residual material left after the digestion process. It is composed of liquid and solid portions. These are often separated and handled independently, as each have value that can be realized with varying degrees of post-processing. Uses: animal bedding (solids), nutrient-rich fertilizer (liquids and solids), a foundation material for bio-based products (e.g., bioplastics), organic-rich compost (solids), and/or simply as a soil amendment (solids) 29. What are the main stages of anaerobic digestion? Describe each. Anaerobic digestion (AD) is a process where microorganisms break down organic matter (like food waste, manure, or sewage) without oxygen, producing biogas and digestate. It happens in four main stages: 1. Hydrolysis: complex feedstocks are broken into simpler compounds so bacteria can digest it more easily. 2. Acidification: Bacteria consume the small molecules from hydrolysis and produce organic acids, alcohols, and gases (like CO₂ and hydrogen - H₂). 3. Acetogenesis: The acidic compounds from the previous step are converted into acetic acid, CO₂, and hydrogen (H₂). 4. Methanogenesis: acetate and some alcohols are converted to methane and carbon dioxide. 30. What are the components of biogas? What is digestate? What are the challenges in applying anaerobic digestion to treat municipal solid waste? Composed: methane (CH4), carbon dioxide (CO2), hydrogen sulfide (H2S), water vapor, and trace amounts of other gases. Digestate: Digestate is the solid and liquid material left after anaerobic digestion. It is rich in nutrients and can be used as fertilizer or soil conditioner. Challenges: The high solid content, large particle size and inhomogeneous nature of the waste makes process control difficult. It is particularly difficult to apply AD to lignin-rich, woody waste. The remaining digestate can in principle be used as a soil conditioner. This usually requires a relatively long maturation (composting) stage before application to land 31. What are the 3 steps in mechanical treatment? Describe them. Describe clean and mixed MRF (Material Recovery Facilities). Steps in mechanical treatment- 1. Component separation: Manual and or mechanical process, necessary for the recovery of reusable/recyclable materials. 2. Mechanical volume reduction or densification: Process for reducing the initial volume by force or pressure. 3. Mechanical size reduction: Reduction of the size not necessarily volume reduction. i.e. grinding, shredding, milling. Clean MRF (Material Recovery Facilities): ‘Clean’ material recovery facilities further separate clean, source segregated dry materials for recycling and/or produce a prepared fuel. They may use either hand or automated sorting systems, or some combination of the two. They are used extensively in developed countries alongside source separation of mixed recyclables. Mixed MRF: Dirty’ material recovery facilities accept mixed waste (MSW or from other sources), from which dry recyclable materials are separated out from the organic fraction. These can be like the mechanical part of an MBT plant. Cross-contamination results in lower- quality outputs. These are more common than clean MRFs in developing countries. 32. Mention 5 key characteristics of an MBT (Mechanical Biological Treatment) SELLING POINT: - Advanced management of material flows, versatility, and modularity. - The actual benefits depend on the type of MBT (Mechanical Biological Treatment) and the main outputs of the plant. INPUT WASTE: - Mixed MSW (Municipal Solid Waste) or after source separation of dry recyclables (‘residual MSW’). OUTPUTS AND MARKETS: - Depending on plant type: SRF (Solid Recovered Fuel), RDF (Refuse-Derived Fuel), compost-like output (CLO), biogas, reduced biodegradability output for landfill (‘stabilized biowaste’). - SRF can be used in cement kilns, industrial boilers, and power plants. - Also dry recyclables. VOLUME REDUCTION: - Depends on plant configuration. SOPHISTICATION OF POLLUTION CONTROL MEASURES: - Low-medium (depending on legislative requirements).