Solid Waste and Soil Science Flashcards
Americans dump how many pounds of refuse into landfills every year?
12-15 billion pounds
The average American produces __ lbs of refuse a day
6 lbs
Domestic solid waste is made up of organic and inorganic materials. What are the terms used for these categories and how are they different?
Organics - garbage - material decomposes
Inorganics - Rubbish - Material does not break down by decomposition
In the solid waste field, garbage and rubbish combined is referred to as _________________
Refuse
One of the biggest problems with refuse is ___________ because while it is organic it does not break down easily due to cellulose
Paper
Decomposition in landfills is primarily a (aerobic or anaerobic) process
anaerobic process primarily
Carbohydrates in the landfill are broken down into ________ and ___________ and odor is typically (present or absent
alcohol and organic acids
odors are absent
_________ containing compounds produce strong odors when decomposing
nitrogen
The key to a successful landfill is to control the _______________ because when they decompose their products can support insect, rodent, and bird populations
organic wastes
What are the three methods in which refuse can be buried or placed on the surface
Trench method
Area method
Valley or Ravine method
What is the trench method
aka: cut and fill method
Typically used on level terrain. Trenches are dug, solid waste fills trenches and dirt is placed on top. The trench is then compacted.
What is the area method
Refuse is dumped on the side of a slope and then covered with dirt. Continues into the slope is leveled.
Most common in the united states.
What is the valley or ravine method?
Refuse is dumped in the depression of a valley or ravine. Fill dirt is added and the area is compacted and built up.
Often used in large cities.
Can later be built upon as a golf course or park. No buildings due to settling 10-30%
What are Class I - 3 landfill types
class 1 - hazmat accepted class 2 - low level hazmat accepted class 3 - no hazmat accepted
What is the soil of choice for landfills and why?
Sandy loam - a mixture of compactible soil and sand which allows for good compacting characteristics but also good seepage for filtration.
What are 4 factors to consider when evaluating a potential site for a landfill?
- factors of ground water contamination
- location and accessibility. type of terrain (level of sloped)
- soil availability for cover and compaction.
- average direction of prevailing winds (must not affect nearby communities)
What is a daily cover?
6’’ of material, typically earthen material such as soil which is compacted to help prevent fly larvae and other reactions between the waste and the air.
Laid over the deposited waste everyday.
What is an alternative daily cover? ADC
A material other than earthen material used as a daily cover.
Typically waste derived materials such as mixed paper sludge or tire derived aggregate.
What is the final cover?
24’’ - a multilayered system of various materials which are primarily used to reduce the amount of storm water that will enter a landfill after closing.
Proper final cover systems will also minimize the surface water on the liner system, resist erosion due to wind or runoff, control the migrations of landfill gases, and improve aesthetics
Name 5 layers that are part of the final cover layer
top soil layer composed of nutrient rich soil
protective layer to reduce the effects of freeze/thaw
drainage layer which moves storm water
barrier layer
grading layer.
What is the ideal slope/percent/degrees for a landfill?
1:2, 50%, 26degrees (33’ 54’’)
What is the ideal slope/percent/degrees for the final closing of a landfill?
1:3, 33%, 18degrees (26’ 06’’)
The first 4 to 60 days a landfill is in (aerobic or anaerobic) state?
aerobic state
After 60 days a landfill is in what state?
anaerobic state
How often do landfills get inspected?
Once a month typically
What is containerization
An old technique no longer used where toxic chemicals were buried over absorptive materials (paper, rags etc.)
Define leachate
Any liquid waste that comes out of a landfill.
What are the various sources of leachate?
Rain water seepage
Liquid intentionally dumped at the landfill
What is the paint filter test?
Tests liquids for their viscosity and will dictate if the liquid waste can be accepted by the landfill for disposal
Define composting
Natural process of plant nutrient recycling. Plant materials such as grass and leaves are broken down by bacterial decay (saprophytic bacteria) in the compost resulting in nutrients being deposited back into the soil for use by other plants.
Name what happens in the 3 cycles of the decaying process in composting
first stage - bacteria degrade compost
second stage - fungus, mold, protozoans further break down plant life
third stage - insects such as millipedes, beetles and earthworms complete the cycle.
What can the end product of composting be used for?
It can be mixed with soil to yield more fertile soil for growing plants
Currently, 40-50% of waste to the landfills is ___________
yard waste
In the beginning of composting the heaps have temperatures between _____ and ______ which benefit the process how?
Between 140F and 160F
Help keep fly breeding to a minimum by killing off fly larvae
Is it advised to add foods grains and animal waste to a compost? why or why not?
No. Stick to yard waste only, green plants such as grass and leaves. Foods and grains hinder bacterial action, attract rodents, flies, and cause bad odors.
Why should the compost heap be turned frequently?
To promote aeration. Anaerobic composting should be avoided because it requires a longer time and has more odors.
Sufficient ________ should be maintained while composting. Also, adding new _________ helps keep the bacterial action going.
sufficient moistures
new plant materials
What is humus?
The end product of composting. It’s a “soil conditioner” not a fertilizer.
How does humus work as a soil conditioner?
By keeping the soil oxygenated and loose for water flow and absorption.
How much of a reduction in volume can be achieved by composting?
40 to 60%
What are windrows?
The term used for rows of compost piles that are positioned to allow air to flow through and promote the aerobic decomposition
Which method of waste disposal has been around the longest?
incineration.
In a hospital, biohazards should be incinerated at what temperature?
1500F
After proper incineration what percent of solid residual ash can be expected?
25%
What can solid ash from incineration be used for?
To enrich soil
What are two advantages to incineration?
Does not require a large space like a landfill does
Large volume reduction of waste
Why are most backyard incinerators banned?
Because they emit a lot of smoke and pollution into the atmosphere. They are hard to control and maintain the optimal burning temperature.
What are the three elements that must be provided for smokeless incineration and describe each element.
Time - need enough to drive out moisture
Temperature - must be high enough (1500 to 1800F) to maintain ignition and burning of the waste
Turbulence - Proper mixing of combustible gases and oxygen is needed for even and hot incineration.
What is a the batch process?
A process in smokeless incineration where waste is burned in batches rather than as a continuous operation.
Why must the batch process be used in smokeless incineration?
So that high temperatures are maintained and smoke is prevented.
What are liequid chemical scrubbers used for?
In smokeless incineration they are used to control the quality of exhaust. They filter the exhaust air. The problem is disposing of the liquid because it is hazardous.
Name the 6 soil types from sand to clay
sand sandy loam loam silt loam clay loam clay
What kind of feel does silt have?
floury or talcum powder feel when dry
sticky when wet
soil that “slicks out” when rubbed between your fingers probably has a fair amount of __________
clay
What kind of particles are said to be gritty?
sand
Sand characteristics
individual grains seen and felt readily
squeezed when dry - falls apart
squeezed when moist - forms a cast that crumbles when handled
Sandy loam characteristics
mostly sand with a little silt and clay
squeezed when dry - falls apart
squeezed when moist - forms a cast that holds with careful handling
Loam characteristics
even mixture of different sizes of sand silt and clay
squeezed when dry - forms a cast that can be carefully handled
squeezed when moist - forms a cast that can be freely handled
slightly plastic
slightly gritty yet smooth
Silt loam characteristics
large quantities of silt, moderate amount of sand, small amount of clay
squeezed when dry or moist - forms a cast that can be handled freely
when dry appears cloddy but lumps are easily broken
will not press out into a smooth ribbon
Clay loam characteristics
a fine textured soil
squeezed when wet and moist - forms a cast that can be handled very freely
will form a ribbon that breaks easily
breaks into clods or clumps that are hard when dry
Clay characteristics
fine textured soil.
breaks into very hard clods or clumps when dry.
very plastic and sticky when wet.
forms a smooth ribbon
What does a red/brown soil color indicate
good water absorption (good perc test results)
What does a blue or black soil color indicate
slower water absorption (poor perc test results)
What is mottled soil and what does it indicate
blotchy colors - indicates not very good water absorption
What are the 6 types of soil structures and how do they filter water?
granular and single grain - filter water quickly
prismatic and blocky - filter moderately
massive and platy - do not filter well
Landfills must be ______ft from lakes and streams
200
Landfills must be _____ft from human habitation (communities)
500
Citing landfill sites should be for a duration of at least ___ to ___ years
30 to 40 years
Waste hauling times and route are (more/less) important than community location
more important
Refuse pick up is usually ___ per week in temperate climates and is based on what?
once per week.
based on fly breeding cycle and climate
What are transfer stations?
Stations where hauled waste is unloaded and temporarily stored until another vehicle takes it to the landfill. Use when distances for individual haulers is too far.
Are open dumps legal in the united states?
NO
What is source reduction?
Preventing waste at the source
What is recycling?
collection, processing, or remanufacturing of materials for reuse.
more broadly referred to as “resource recovery”
What does the “in-vessel process” refer to
a method of composting that is highly sophisticated.
What are waste-to-energy plants
plants that capture the heat of combustion in the form of electricity or steam
What are two types of waste-to-energy plants
mass burn facilities
refuse-derived fuel plants
What are mass burn facilities
unsegregated wastes feed the furnace to harvest energy from combustion
What is refuse-derived fuel plants
non-combustibles are first removed and remaining wastes are shredded to produced pelletized fuel that can be used in boilers.
What are cells in landfills?
They are the basic building blocks of sanitary landfills. Each day a cell is created.
The formation of a cell is the equivalent one rise to two runs resulting in a 50% grade
What is a lift in a landfill?
Adjacent cells are called a lift. The entire landfill is a series of lifts
landfill gases, CH4, CO2 and H2S are produced as (aerobic/anaerobic) byproducts?
What should their percentages be?
anaerobic byproducts
CH4 65%
CO2 35%
H2S less than 1%
Liner systems of landfills are usually what material?
typically clay or synthetic
An oxygen concentration meter has a typical detection range of ____%
0-25 %
Combustible gas indicators measure the ____________ and will alarm at _____%
LEL (lower explosive limit)
Will alarm at 20% of the LEL
The grinding of garbage is an acceptable method of______
garbage disposal
volume reduction
wet oxidation
energy recover
garbage disposal
A solid waste manager is trying to reduce lead in the solid waste stream. What should be targeted in the municipal waste stream as a major contributor of lead to the environment?
fluorescent light tubes
lead acid batteries
household batteries
rechargeable batteries
lead acid batteries
All of the following are considered advantages of using the “shredded solid waste” landfill method except which?
it does not cause odors
it may require daily earth cover
it will readily absorb precipitation
it reduces insect breeding
it will readily absorb precipitation
The best sanitary landfill method for a location with rolling terrain would be:
low-area method
valley or ravine area method
trench method
area or ramp method
area or ramp method
