Vecka 1 + 2 Flashcards
Describe the role of landfills in the waste management system?
In either step of the waste hierarchy, waste will be produced somehow and that can’t be disposed in the following steps. This means that in every step, some waste must go to landfills. So, their purpose is to detox and manage residue.
Gives a flexibility in the waste management. Good backup if the previous steps fail
What is the alternative to landfilling (in terms of waste disposal)?
The alternative is incineration. If the materials can be used again or in some way use the energy, so material reuse or biological treatment is also an option, but looking at disposal, it is just incineration that is an option. But there is still residue from incineration that needs to be landfilled or treated in some way.
Uncontrolled landfilling. Dispersion. Landfill is the final destination.
From Examination questions and example of answers:
- Dispersion. Landfills are the fundament of the waste hierarchy. All steps (apart from reuse) cause residuals that either have to be landfilled or are spread to the environment as diffuse emissions.
Which purposes do landfills serve in waste management?
If either process in the steps before landfilling in the waste hierarchy does not work properly, the landfill is always there, either for short term storage or for long term storage. The only step in the hierarchy that we can’t take away.
To store material temporarily or permanently. Space for several (kolla föreläsning om “modern landfill”)
From Examination questions and example of answers:
Three obvious uses for landfills are:
- To store material temporarily or permanent
- To be the back-up option to other facilities
- Location for various sorting, recycling and treatment activities.
The waste hierarchy aims at reducing the amount of wastes being landfilled. Name ans explain three advantages and disadvantages with this strategy.
Landfilling is the only step that you cannot do without. Sometimes it is the best alternative. Landfills represent flexibility and durability.
More costs involved if you must send to different places. More sorting which takes more time. Energy consumption.
Usage of the resources are better now, and it is the point of the waste hierarchy. Use the energy that is in the waste.
From Examination questions and example of answers:
Advantages:
- Better environmental control; decreasing of contaminants discharge in the surrounding (air, ground and water)
- Fewer and larger landfills that ca be operated more efficiently and at high standards (BAT)
- Increased recycling and reuse of products and materials, nutrients or the energy content of waste
- Development of knowledge about waste and treatment opportunities; improvement of treatment processes, recycling
Disadvantages:
- Higher treatment costs because it’s more expensive to treat each kind of waste separately
- More diffusion (emissions) from more treatment
- Risk of accumulation of contaminants within the society/circular economy due to increased reuse of waste
- More transport (waste to and from treatment facilities, to adapted landfills, …)
- More complicated administration with specific protocols for disposal of waste at different landfills, control (the identity of the waste producer, the source process, the waste composition … must be noted), and so on.
Briefly describe the different degradation phases occuring in a landfill containing biodegradable waste.
Aerobic
Acidogenic
Methanogenic
Oxidation
Weathering
What are the three landfill classes from a legal point of view, how do the landfills differ and why are different materials destined to different facilities?
Hazardous, non-hazardous, and inert. The definitions are mainly based on leaching properties. The inert waste does not react at all, “waste that does not undergo significant physical, chemical or biological transformation”. Non-hazardous can be municipal waste and it is waste that is not covered by paragraph c in the directive 1999/31. Hazardous waste is covered by article 1(4) of the directive 91/689/EEC on hazardous waste. If hazardous waste is landfilled, the covers at the bottom at the top of the landfill must be thicker and denser than if the landfill was for non-hazardous waste. There are less regulations on the cover for a landfill with inert waste, liner, and no gas collection (can produce leachate). Hazardous waste now is mainly contaminated soil. Leachate treatment is different. Dividing them because of costs.
From Examination questions and example answers:
Three landfill classes- hazardous, non-hazardous and inert
Difference-
- The landfills differ in their capacity to handle waste and emissions, e.g., with regard to facilities, supervision and design. For example; a landfill for inert waste has no leachate collection. Bottom liner (thickness, permeability) and leachate generation after covering.
- Different wastes are steered to different landfills presumed to be equipped to deal with them properly, e.g., based on leaching properties.
There are different goals for the characterization of waste. What is the general goal for waste characterization? Name and explain three goals from the perspective of a landfill operator.
One goal is to know how to manage the waste.
A basis for: waste management decision making; technology development (of e.g. waste treatment); environmental impact and risk assessment; legal requirements; communication and co-operation
Providing information for the questions answered.
From examination questions and example answers:
The general aim of waste characterization is to understand and be able to predict the behaviour of a waste. A landfill operator may need to identify wastes as being the same as declared by the generator (classification). The characterization is then made in order to avoid erroneous placement of wastes and to charge and to charge the correct fee for disposal or treatment. An operator may also need to characterize a waste in order to:
- Control the waste streams (amount of waste and flow)
- Choose a proper place for a new landfill/new part of a landfill (siting) and design the landfill facilities (barriers, treatment systems, ..)
- Select the appropriate landfill technology and treatment of the waste (filling techniques, gas extraction, leachate treatment etc)
- Assess the costs for handling & treatment (economy)
- Develop more effective recycling and/or treatment methods (R&D)
- Predict the long-term behaviour and emissions from the landfilled waste
- Assess the impact on the recipient and surrounding
What kind of knowledge of the waste is required to accept waste at landfills (that is what kind of information must be included in the waste characterization documents)?
- Identify of the waste producer
- What kind of process the waste come from
- Description of the waste treatment prior to landfilling (in compliance with the Landfill Directive), or a statement of reasons why pre-treatment is not considered necessary
- Data of the composition of the waste and the leaching behaviour
- Appearance of the waste (smell, colour, and physical form)
- Waste Code according to waste categories in the European List of Waste
- The landfill class at which the waste may be accepted
- If necessary, additional information about precautions to be taken at the landfill
- Comment why the waste could not be recycled
From Examination questions and example answers:
I’ve done it correctly.
Note: The answer must not include all nine points, but should at least mention a summary of the meaning of the nine points like this:
- The waste must be clearly identified, including information about the waste source and waste characteristics like for example leaching behaviour
- The waste must have been classified with a waste code in the European List of Wastes
- Pre-treatment must be declared or explained and argued why it was done
Why is waste characterization important in landfill technology?
To understand and to be able to predict the physical, chemical, and biological behaviour of the waste. For a basis as a waste management decision making, technology development, environmental impact and risk assessment, legal requirements and communication and co-operation.
From examination questions and example answers:
Because the properties of the waste will determine how it can be handled and what measures must be taken to prevent emissions (should be developed by a number of concretisations)
What factors affect the leaching of contaminants?
Physical: particle properties, internal pore structure, temperature, time of contact between phases, L/S ratio
Chemical: pH, redox potential, availability of complex formers, availability of sorption surfaces
The L/S ratio is the liquid to solid ratio a waste has been exposed to. Estimated in-situ L/S ratios can be used to develop bench-scale leaching tests for simulating landfill leaching processes over time. Sometimes the L/S is translated into a time scale by the use if infiltration rates and leaching predictions are made. Explain why there is a risk for such leaching tests giving misleading results and give examples for over/underestimations of concentrations and/or time frames. Consider your knowledge about (a) the factors controlling leaching as well as (b) in-situ waste conversion processes.
Lab-tests are simplified, with time, temperature, pH, redox etc. Biology factor is not accounted to in the lab. Factors affecting landfills are physical: particle properties, internal pore structure, temperature, time of contact between phases, L/S ratio; and chemical: pH, redox potential, availability of complex formers, availability of sorption surfaces. Degree of contaminant mobilisation: surface accessibility (surface enrichment, particle size) and surface solubility (surface speciation and leaching conditions). Degradation in landfill, conditions change over time in a landfill which is not happening in the lab.
Salts are the most representative in the leaching test as well as in the landfill. L/S ratio in test is transferred to years instead. Lower than L/S of 0.1 in a landfill.
Mineral transformation in the waste, precipitation of ex. sulphides which you don’t have in the lab since you have an oxidising environment in the lab.
Limitations of leaching tests: simplified/generalised systems, time aspect, mainly performed at room temperature, difficult to control microbial activity and redox, poor correlation with bioavailability. Solutions for the limitations: larger and more complex tests that are operated under longer time, combination with field tests under real conditions.
Examination questions and example answers:
a) The L/S ratio is just one out of many possible factors that can affect leaching, eg. pH, redox potential, complexing agents and more. The effect of the L/S ratio is often linear (e.g. for solubility controlled leaching) while the impact of factors such as redox potential and pH may be even logarithmic, i.e. much more pronounced. Also, the way how the water moves through the landfill affects the leaching.
Factors affecting leaching can be assorted into 1: surface accessibility (surface enrichment, particle size), and 2: surface solubility (surface speciation; oxides, carbonates, sulfides, adsorption, complex-bound etc.) and leaching conditions (L/S, pH, temperature, ionic strength etc.). Describe how these factors can affect concentrations and estimated time frames.
For highly soluble components such as some salts (sodium, potassium and chloride ions), the L/S ratio has a minor impact on the leaching as already small amounts of water are sufficient to cause a complete dissolution. Therefore, the L/S ratio can be used to roughly predict the leaching of such conservative substances.
b) In-situ waste conversion processes include e.g. changes in the waste mineralogy. The latter may increase as well as decrease leaching.
Why is landfill siting a process that often takes decades to complete?
There are many aspects to take in. Such as geographical, NIMBY, physical, landscaping, selecting procedures, public involvement for potential sites and then there are a lot of permits and investigations needed.
From Examination questions and example answers:
It is a complex procedure that is controlled by democratic processes that should be allowed to take time
What are the principal aspects to consider in a landfill siting process? Give one example for each category.
- The need – waste level, technical and economic aspects: amounts of waste, quality of waste, management options, distribution of waste generation in time and space
- The impact – ecological level, environmental aspects: emissions and other impacts, suitable geological setting, availability of cover materials, duration, and end use
- The interests – social level, social and political aspects: conflict of interests, legal procedures, urban planning
From examination questions and example answers: - Techno-economic aspects: waste fluxes and character, geographic distribution, alternative management options
- Environmental aspects: natural environment- character of the recipient, available resources (ex. Clays), ecological impact
- Social and political aspects: what are the competing land uses, who is affected and how to communicate during the process, permissions, cultural and historical resources
Describe important steps of the procedure for landfill siting. Which step usually takes most time and why?
- Identify potential sites within the region based on:
- Geographical, geological and hydrogeological considerations physical stability, flooding risks, ecological habitats, hydrological barriers, vulnerability of local surface and groundwater bodies
- Physical planning (conflicting interests, distances, accessibility)
- Landscaping and capacity estimates – Is there enough space?
- Selection procedures (graphical or ranking procedures)
- Public involvement - Select the most promising candidate sites and evaluate in detail
- Final selection of the best site for development
- Acquisition and legal approval of the site
OR:
Place?- Site investigation
Permit?- Technical description and environmental impact assessment
Applications?- Licence for operation, building permit
Examinations by the authorities
Approval- Licence/permit with terms and conditions
Establishment of the landfill
When siting a new landfill in Sweden, there is a legal requirement to invite and listen to the public in the planning process. Discuss how, in practice, the consultation of the public can be done. What purpose should such consultations serve?
Common concerns:
Proximity- the relative distance between the site or access route and the human populations near the proposed site
Economic- the concern of those living near the proposed landfill that property values will decline
Leisure use- the view that the presence of the proposed landfill will negatively impact leisure activities, example fishing and hiking
Social/aesthetical- the perception that the presence of a landfill diminishes the quality of life of those living or working near the site
Health- the presence of the waste will influence air quality and potentially affect people living in the neighbourhood
Environmental- worry about crucial disturbances in ecosystems
Samråd med allmänheten.
Through meetings, flyers etc
From examination questions and example answers:
- Meetings, publications, interviews and questionnaires (media could be printed, either media or the web)
- Retrieve knowledge e.g. about alternative sites, from the public, inform the public, understand the concern of the public, making people realize the need and use of a landfill, get feedback for the development of solutions. Develop a political support.
Describe how one could integrate landfills with natural retention and adsorption systems.
- Immobilisation in sediments is a naturally occurring detoxification system for heavy metals that frees the biosphere from these substances (it is from old sediments that many metals are extracted)
- Sediments at e.g. the bottom of seas, lakes and swamps have functioned as metal traps for millions of years which makes it reasonable to hope that they will continue to do so
- Metals, nutrients and other potentially polluting substances that slowly leak from closed landfills will be delayed and partly transformed or decomposed by their passage through the unsaturated zone.
- Similar processes also happen after the leached substances have reached the saturated zone, yet the transport will be faster there, and a certain dilution occurs. When the diluted leachate reaches the outflow zone, e.g., in a swamp, leached nutrients will contribute to a primary production there and indirectly strengthen the already existing anaerobic environment of the deeper parts of the swamp
- A reduced environment in the form of a growing organic soil (peat bog) can serve as a final trap for metals and other contaminants
- This way, the separation of several hazardous components in enhanced through natural precipitation and adsorption processes
