The environmental releases associated with collection and separation are local issues, whereas releases associated with transport to remanufacturing facilities (which might even be outside the United States) and emissions from remanufacture are distant effects. Local and distant emissions are covered separately in this subsection.
Community Environmental Releases
Releases associated with recycling include the greater emissions that result from multiple pickups in both packer trucks and multi-compartment trucks instead of a single collection of MSW, as discussed under "Energy Requirements." In the estimates given in Exhibit II, the packer truck emissions have been adjusted downward to reflect the results of collecting smaller quantities of MSW at each stop.
Other environmental releases result from operating the MRF; they include truck traffic, noise, dust, and odors. When the recycled materials are diverted from a landfill, however, emissions from the landfill may decrease, and less land space will be required. If the recyclables are diverted from combustion, emissions and ash from the MSW combustor may be reduced. The data base takes these potential reductions into account.
Emissions from Remanufacture
The environmental releases that are eliminated by avoiding mining, harvesting, and extracting raw materials and the impact of recycling on land use are typically included in analyses of recycling. Those issues are beyond the scope of this project, but results of past "cradle-to-grave analyses" are presented in Table 7.4. The bases from which these reductions were estimated are unclear; the reductions may well assume emission levels that are higher than current standards or practice. New analyses of newsprint and glass now under way at Argonne National Laboratories should update and expand the data presented here.
Table 7.4
BENEFITS FROM USING RECYCLED MATERIALS IN PLACE OF VIRGIN MATERIALS(a)
Benefit
(% reduction)
Aluminum Steel Paper Glass
Energy 90 47-74 23-74 4-32
Air pollution 95 85 74 20
Water pollution 97 76 35 -
Solid waste(b) 90 - - 80
Sources: All except solid waste--Appendix E, page E-55; Robinson
(1986), cited in Thurner and Ashley (1990).
(a) These data are old and fragmentary, and they may refer to in-plant
savings alone.
(b) Source: Sellers and Sellers, 1989.
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Table 7.5 shows the energy and emissions over a 20-year period from adding MRF operations and recycling to a strategy that involves landfilling alone. The estimates in the table include energy and emissions for normal collection of MSW, energy recovered from the landfill gas, and landfill emissions and leachate along with the energy and emissions associated with the curbside collection and MRF processing of recyclables. Credits for energy savings that result from actually recycling the separated materials through remanufacture are also included. The results are given separately for transportation, processing (MRF operations), and disposal (landfilling the nonrecyclable materials). Table 7.6 presents the same data for the landfill strategy.
Energy requirements and air emissions for curbside collection depend on the efficiency of truck use. In the example considered here, separate collection of recyclables required a few smaller trucks, and the net result was an increase of 20% in the collection energy requirement. In the community used as the model for this integrated strategy example, the small recycling trucks used for curbside collection were repeatedly filled to capacity before they returned to the dropoff point.
Although the total energy saved by adding curbside collection and recycling was less than the energy recovered from the landfill, it was 10-20 times as great as the quantity of energy required by the community for collection and processing. Unless the collected materials are recycled in the community, the energy savings will benefit other areas (or the U.S. economy as a whole) rather than the jurisdiction that is conducting the program.
Table 7.5
ENERGY AND EMISSIONS FOR STRATEGY 6: CURBSIDE COLLECTION WITH MRF AND LANDFILL
Total Collection Process(a) Disposal
Landfill space (assuming a depth
of 50 feet), 10(-5)acres 1.82 1.82
Energy Required (million Btu) 0.116 0.094 0.02 0.002
Energy Produced(million Btu) 2.80 0.00 0.80 2.00
Net Energy (million Btu) 2.68 -0.094 0.08 2.00
Air Emissions
Particulates (lb) 0.02 0.02
Carbon Monoxide (lb) 0.94 0.94
Hydrocarbons(lb) 0.09 0.09
Nitrogen oxides (lb) 0.38 0.38
Carbon dioxide (lb) 397 397
Water (lb) 171 171
Methane (lb) 13.05 13.05
NMOC (lb) 0.68 0.68
Dioxin/furan {10(-6)lb}(2)
SO(2) {10(-3)lb}
HCI {10(-3)lb}
Antimony {10(-6)lb}
Arsenic {10(-6)lb}
Cadmium {10(-6)lb}
Chromium {10(-6)lb}
Lead {10(-6)lb}
Mercury {10(-6)lb}
Nickel {10(-6)lb}
Zinc {10(-6)lb}
Total Heavy Metals {10(-6)lb} NA NA
Effluent
Leachate (gal) 72.80 72.80
Leachate (lb) 607 607
Chloride(lb) 1.03 1.03
Sodium (lb) 0.66 0.66
Potassium (lb) 0.56 0.56
COD (lb) 0.15 0.15
Arsenic {10(-6)lb} 78 78
Cadmium {10(-6)lb} 2.7 2.7
Chromium {10(-6)lb} 148 148
Copper {10(-6)lb} 39 39
Nickel {10(-6)lb} 98 98
Lead {10(-6)lb} 44 44
Mercury {10(-6)lb} 5.4 5.4
Zinc {10(-6)lb} NA NA
Total Heavy Metals {10(-6)lb} 416 416
AOX 0.98 0.98
(a) Curbside MRF and recycling.
(b) This is total dioxin/furan as specified by EPA in CFR, 1991a.
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Table 7.6
ENERGY AND EMISSIONS FOR STRATEGY 1: LANDFILL WITH GAS RECOVERY
Total Collection Process Disposal
Landfill space (assuming a depth
of 50 ft), 10(-5) acres 2.00 2.00
Solid waste (lb) 2000 2000
Energy Required (million Btu) 0.081 0.079 0.002
Energy Produced (million Btu) 2.20 0 2.20
Net Energy (million Btu) 2.12 -0.079 2.20
Air Emissions
Particulates (lb) 0.02 0.02
Carbon Monoxide (lb) 0.79 0.79
Hydrocarbons (lb) 0.08 0.08
Nitrogen oxides (lb) 0.32 0.32 NA
Carbon dioxide (lb) 225 225
Carbon dioxideÑcombustion (lb) 212 212
Water (lb) 188 188
Methane (lb) 14.34 14.34
NMOC (lb) 0.75 0.75
Dioxin/furan {10(-6)lb}(a)
S0(2) {10(-3)lb}
HCI {10(-3)lb}
Antimony {10(-6)lb}
Arsenic {10(-6)lb}
Cadmium {10(-6)lb}
Chromium {10(-6)lb}
Lead {10(-6)lb}
Mercury {10(-6)lb}
Nickel {10(-6)lb}
Zinc{10(-6)lb}
Total Heavy Metals {10(-6)lb} NA NA
Effluent
Leachate (gal) 80 80
Leachate (lb) 667 667
Chloride (lb) 1.13 1.13
Sodium (lb) 0.73 0.73
Potassium (lb) 0.60 0.60
COD (lb) 0.16 0.16
Arsenic {10(-3)lb} 86 86
Cadmium {10(-3)lb} 3 3
Chromium {10(-3)lb} 163 163
Copper {10(-3)lb} 43 43
Nickel {10(-3)lb} 108 108
Lead {10(-3)lb} 48 48
Mercury {10(-3)lb} 6 6
Zinc {10(-3)lb} NA NA
Total Heavy Metals {10(-3)lb} 457 457
AOX (lb) 1.08 1.08
(a) This is total dioxin/furan as specified by EPA in CFR, 1991a.
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In comparison with landfilling alone, the strategy that includes recycling increases air emissions for the collection step, but decreases the emissions from the landfill. Water emissions from the landfill also decrease by about 10%, for a net reduction in water emissions.
Few data on collection distances and loadings per trip have been published. The data used in this example were collected by SRI International from community officials of an affluent residential/ commercial community in California that has had an active program for curbside collection of recyclables for more than 12 years (City of Palo Alto, 1991). The data should be considered illustrative only; additional examples are needed to draw reliable conclusions.
Details of the calculations used to obtain estimates of emissions and energy consumption are presented in Exhibit II. The computerized version of the data base allows a user to change the collection amounts and mix of collected materials, to substitute other measures of collection efficiency for those used in this report, and to enter the actual miles traveled.
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