Solid Wastes
A. Solid discarded material (EPA definition)
waste:
includes: solids, liquids, contained gases
excludes: agricultural wastes returned to soil
mining and milling wastes returned to mine
domestic sewage, and nuclear materials (!)
1. garbage: relatively decomposable wastes
(kitchen, food wastes)
2. rubbish: relatively non-decomposable wastes
(paper,cloth, glass, metal)
B. phases: input process output outcome
generation --> transfer --> disposal --> effects
| | | |
source resource remediation |
reduction recovery compensation
3. collection: greatest cost of solid waste management
4. transfer: temporary holding facilities
(for collection, storage, some treatment)
5. treatment: to reduce volume, mass, or risk
6. incineration: controlled combustion of waste
7. RDF: refuse derived fuel (waste is incinerated)
8. mass burn: nothing is sorted
9. controls: temperature (1400-1800 degrees F.)
turbulence (oxygen) -- grates:
rectangular, vertical circular,
rotary kiln, others
time (continuous preferred over batch)
10.ash: solid residue that remains after burning
(bottom ash = at bottom of incinerator)
(fly ash = smaller airborne particles)
11.pyrolysis: burn wastes with no added oxygen ("roasting")
Solid Waste (continued)
12. composting: controlled biodegradation of
plant and animal matter
13. humus: decomposed plant and animal matter
soil conditioner (poor fertilizer)
14. windrows: long rows of compost
15. procedure: shred (allows faster decomposition)
spread in thin layers (2"-6"):
carbon layers: paper, leaves, sawdust
nitrogen layers: grass, kitchen scraps, fruit
activator layers: manure (dog droppings, etc.)
soil
fertilizer
sprinkle with water to maintain moistness
ventilate
16. problems: AVOID: meat, grease, bones, and weeds
odor: if ammonia smell, add carbon
if rotting smell, add carbon,
ventilate,
stop watering
if too slow: add nitrogen, activator
maintain water and oxygen
17. resource any process where materials are recovered
recovery: rather than discarded
18. reuse: use again in same way
19. reclamation: (utilization) use in new ways
20. recycling: use raw material in various ways
(e.g., cullet = ground glass)
21. source to re-evaluate and eliminate waste generation
reduction:
22. tipping fees: charge to dump garbage at a
disposal site ($/ton)
A. Features:
1. protective clay soils or
lining: synthetic liners (PVC, PE)
2. layers 8-10 ft. deep (after compaction)
(lifts): intermediate settling (prefer 1 year)
before next lift
3. cover daily: 6 inches
material: intermediate: 12 inches
final cover: 24 inches
2-4 % grade (for proper drainage)
less than 30 degrees on side slopes
B. Methods:
4. area: uses natural slope: valley or ravine methods
low area method
ramp method
5. trench: man-made
C. Processes:
6. LFG: landfill gas
aerobic: a. lasts several days to several months
anaerobic: b. mostly CO2 formation (acid formers)
c. increased methane formation (methane producers)
d. stabilized (roughly equal % of methane and CO2)
(lesser levels of NH3 and H2S)
rates: depend on temperature, pH (acid inhibits growth),
moisture, type of wastes
methane: explosive limit of 5%
7. Leachate: from waste itself, or water entering landfill
high in organics, heavy metals
D. Daily concerns:
8. records: type and amount of waste received
(measure by weight, because volume changes),
# and type of personnel, equipment
monitoring leachate and gas production
9. procedures: standby equipment
exposed waste area is minimized
work with prevailing wind
portable fencing (prevent wind blown waste)
compact to 12-18 inch layers (4-5 passes of tractor)
E. Long-term concerns:
10. space: land area needed
11. access: fences, signs
12. time: 20-40 years operation
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