Lecture 8: Municipal waste collection systems (Ch. 6.1-6.4) Flashcards
How much of the total cost of a waste management system can the collection and transport constitute?
Between 50% and 80%.
Which trends affect the waste collection?
- Increasing waste volumes every year
- Source separation of several fractions, due to an increase in recycling
- Increasing traffic volumes and congestion
- Increasing traffic related emissions of pollutants and noise
- Higher hygienic standards and lower noise levels
- Improved quality of life
- Improved working conditions for the collectors and operators
Explain the differences between kerbside collection (property close) and drop-off system.
Property close collection
• Full service (permanent or requested) -receptacle for the waste is placed at a convenient location on the premises
• Kerbside collection permanent -the receptacle is placed permanently at the curbside and the collection crew has easy access to the receptacle
• Kerbside collection scheduled-the home-owner brings the receptacle or the waste according to a fixed schedule to the kerbside
Public collection/drop-off collection
• Collection points (called collection/recycling islands, drop-off points, local bring systems) -placed at frequently traveled routes such as main roads, bus stops, supermarkets and shopping centers; walking distance 100-150m; mainly used for recyclables;
• Collection centres (called recyclingcentres, civic amenity sites) -large, often manned collection points collecting a wide range of waste types often brought to the center by private car; one site for 10,000 –50,000 resident.
Mention the difference waste collection methods.
- Simple emptying–by far the most used for household waste and small-scale commercial waste, different size containers emptyied mechanically
- Exchange system -mostly used for high density waste such as construction debris and sludge, as well as for low-density waste from facilities that generate large quantities of waste; a full container (large) is exchanged for an empty one.
- One-way system -the one-way method uses bags that are only in use for one collection cycle (bags of plastic or paper); collection staff has to carry and lift the bags; the bags increase waste generation (~3%)
- Other collection methods–central and mobile suction/vacuum systems, hydraulic flushing methods (kitchen grinders)
What are the advantages by having deep/underground containers for MSW?
- 60% of the container lies underground, leaving more space for other purposes.
- The vertical design allows the waste to become compact due to gravity.
- The lid is light and easy to use. Wind or animals are not able to spread the waste around.
- The coolness of the ground slows down bacterial growth and reduces odours
- Self-cleaning because the waste is emptied through the bottom creating friction
What are the benefits of vacuum suction systems
- Can be used for multiple waste streams (max 4 as of now)
- Completely automated
- Transportation distance up to almost 2 km is possible, and installations exist serving 8000 apartments in scattered blocks
- Waste is transported at a velocity of 50-70 km/h to the collection station
- Quiet, clean and hygienic
- Lower operation and maintenance costs compared to traditional collection
- Elimination of more than 70% of the waste collection vehicle driving and emissions
What are the limitations/disadvantages with a vacuum suction system?
- Higher initial investment costs compared to traditional collection.
- Use of plastic bags which increases waste.
- Only applicable in high density areas.
- Implementation not always possible depending on the subsoil (cables, sewage system, underground system etc.).
- Hard to implement in existing buildings, best implemented in new areas – part of the development process.
Explain the traditional fee system for waste collection.
Traditional fee systems
- Property based (floor space, number of apartments)
- Without relation to the actual amount of waste produced by an individual source (household)
Explain the “Pay as you throw” system.
- The fee is, as far as possible, individually calculated according to the individual
property’s use of the service - The pay scheme contains an incentive to source segregation for recycling and
correct handling (e.g. exemption from paying for recyclables collection)
The payment of the PAYT-system can be based on two different methods. Which ones?
o Volume-based payment: The fee is calculated on the basis of the number and size of bins allocated to the individual property or put out for emptying.
o Weight-based payment: This implies both identification and weighing of each individual bin emptied.
During the 1990s, PAYT schemes were introduced in 18 Danish municipalities. The results of the case study showed that…
• The amount of mixed household waste was clearly reduced
• More waste was collected through recycling schemes (especially paper and
cardboard)
• Pay-per-kg fees did not change consumer behavior therefore no reduction
(prevention) in waste generation can be expected
• Administrative work increased, due to writing out the individual accounts for
each household plus making up the account in case of change of addresses
• Despite the fact that ‘pay-per-kg fees involve a great risk of illegal dumping,
there were no signs of large-scale illegal tipping
Organizing or planning of collection systems for household waste is much more
complicated than for waste from other sources. Which data is need as a minimum?
- Quantities of waste generated
- Composition of the various waste streams
- Temporal distribution of generated waste
- Population and housing structure
- Existing collection infrastructure (how much can be still used)
- Existing and planned treatment infrastructure (used for determination of
transport distances) - Service levels (decided/agreed by the political establishment)
What are the main system aspects to be organized in relation to collection of household waste?
i. Collection frequency
ii. The collection materials per generating source (each single-household and
shared materials for multi-family residences)
iii. Route planning for collection vehicles
iv. Crew size and truck capacity
v. Quality management and consumer relations
Which aspects should be considered regarding the collection frquency?
• The cost of collection is greatly influenced by the collection frequency
• The frequency of removal depends on climate and waste composition
• Hygienic issues, such as odor, flies etc.
o Residual waste/biowaste – in south of Europe ––2-3 times per week, while in central and north Europe it can be 1 per week of every 2 weeks.
o Dry recyclables can be removed at with lower frequency
• Frequency can have an impact on household participation in separate collection
• Fine balance between service, costs and efficiency
Which aspects should be considered regarding the collection frquency?
- The cost of collection is greatly influenced by the collection frequency
- The frequency of removal depends on climate and waste composition
• Hygienic issues, such as odor, flies etc.
o Residual waste/biowaste – in south of Europe – 2-3 times per week, while in central and north Europe it can be 1 per week of every 2 weeks.
o Dry recyclables can be removed at with lower frequency
- Frequency can have an impact on household participation in separate collection
- Fine balance between service, costs and efficiency
