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16 Cards in this Set

  • Front
  • Back
State the average mass of solid waste produced per capita per day in USA
about 2kg / capita / day
Differentiate b/w garbage, rubbish, refuse, and trash, based on their composition and source.
Garbage: animal/vegetable waste from the handling, preparation, cooking and serving of food, largely rotten organic matter and moisture
Rubbish: combustible solid wastes (paper, boxes, wood, cartons), noncombustible solid wastes (metals, tin cans, metal, furniture)
Garbage and rubbish are from households, restaurants, or stores.
Refuse: sweepings, dirt, leaves from streets, sidewalks, alleys
Trash: subcomponent of rubbish (paper, rags, cartons, boxes, tree branches)
Compare the advantages and disadvantages of public and private solid waste collection systems.
Public: advantages: frequency of collection, types of waste collected, method of disposal, location of disposal site, environmental concern can be considered for the benefit of citizens and community environments.
Disadvantages: performance is less measurable with quantitative ways and institutional factors such as political feasibility or legislations could complicate the system and slows down the operation.
Private: advantage: performance can be measured by cost-effectiveness.
Disadvantage: system's sustainability or sanitary level might not be concerned.
List the three pickup methods (backyard, set-out/set-back, and curbside) and explain the advantages/disadvantages of each.
Backyard: the crew enters resident's property, dumps the container into a barrel, carries it to the truck and dumps it.
+: convenient for residents
-: high cost, entering property is annoying for the residents

Set-out/set-back: set-out crew carries the full containers from the resident's storage to alley, and collection vehicle arrives and collection crew collects the loads and set-back crew returns with the empty cans.
+: wastes are not be seen on the streets
-: costly than curbside method

Curbside: the crew empties the container into the collection vehicles.
+: less costly than the other two methods
-: citizens have to set their solid wastes out at certain times
Explain the function and use of the crew-machine chart in analyzing solid waste collection.
Crew-machine chart shows how much time is spent on each task by each crew measured by stopwatch. After the data are collected, they are converted into histogram format that shows the percent of time spent on a given task.
Comapre the advantages and disadvantages of the four methods of collection truck routing.
Daily route method:
+: homeowner can know when the refuse is picked up.
-: extra cost if workers haven't finished the route.

Large route method:
+: route sizes are adjustable for the load to maximize crew and truck utilization.
-: extra cost for overtime.

Single load method:
+: minimize travel time
-: hard to predict the number of homes that can be serviced before the truck is filled.

Definite working day method:
+: crew and equipment get maximum utilization.
-: work can be over before finishing the loads and residents don't know when the pick-up comes.
Explain the four methods of integrating several crews.
Swing crew method: uses extra crew as standby for heavy pickups, breakdown or illness.
Variable crew method: crew sizes are adjusted according to heavy loads, rain, different route sizes.
Interroute relay method: when a crew finishes one job, the person is put on another unfinished route.
Reservoir route method: when they have finished the route, the crew goes to the core and begins picking up there.
Explain what a transfer station is and what purpose it serves.
Transfer station is the place where waste is transferred from several collection vehicles to a larger vehicle that carries the waste to the disposal site. It's more economical.
List and discuss the factors appropriate to the selection of a landfill site.
public opposition
connection to main roadways
underpass limitations
speed limits
load limits
bridge capacity
traffic patterns and traffic jam
haul distance
detours
hydrology
availability of cover material
climate
zoning requirements
buffer areas around the site
historic buildings, endangered species, other environmental concerns
Describe the two methods of constructing a sanitary landfill.
Area method: solid waste is deposited on the surface, compacted, then covered with a layer of compacted soil at the end of the working day
Trench method: trench is excavated, and the waste is placed in it and compacted. The soil taken from a trench is laid on the waste and compacted.
Explain the purpose of daily cover in a sanitary landfill and state the minimum desirable depth of daily cover.
Daily cover is done for insect and rodent control. Minimum desirable depth of daily cover is 0.15m.
Define leachate and explain why it occurs.
Leachate is water that passes through landfill and that has extracted dissolved and suspended matter. It occurs because of aerobic/anaerobic decomposition of OMs in the waste or chemical / physical changes.
List four common measures to minimize groundwater pollution from leachate.
- Locating the site at a safe distance from streams, lakes, and wells.
- Avoiding site locations above porous soil
- Using an earth cover that is not permeable
- providing suitable drainage
Sketch a sanitary landfill that includes proper cover and a leachate collection system.
impermeable cover (0.6 m) on top, daily cover, 0.3 m of sand with leachate collection, and then 3 m natural clay, then reaching aquifer.
List two higly feasible methods of resource conservation and/or recovery in each of the following categories: low technology, medium technology, and high technology.
Low technology: beverage collection, recycling
Medium technology: product design, shredding and waste separation, composting, methane recovery
High technology: refuse-derived fuel (RDF), water wall combustion
Describe and explain, in a basic manner, each of the two methods listed in 15 above such that the average citizen could understand the method.
Beverage collection: return beverage containers to a collection site or shop and these containers are reused 10-20 times.
Recycling: collection of newspaper, cardboard, paper, glasses, aluminium cans at collection sites and reprocessed to obtain original raw material
Product design: changing a product design or composition so that raw material for the product can be reduced.
Composting: biological decomposition of organic wastes so that the soil waste becomes stable and conditioned.
RDF: to obtain combustible portion of the waste and to use it as fuel.
Water wall combustion: to generate steam and electricity from burning solid wastes.