NSCA reports study impact of recycling and waste emissions
NSCA has produced two reports on the impact of emissions on the environment, one on transport related to recycling, the other providing a comparison of emissions for waste management options. LAWE looks at key indicators from the research.
Glass reprocessors are concentrated in the north of England, and, until it becomes attractive to open new plant in other areas, substantial transport emissions are likely to continue. The report concludes that there remains an excess of green glass entering the UK waste stream and there is a limit to the demand for glass containers. If recycling rates are to grow, new outlets for glass will have to be found.
The study investigated the economics of small scale crushing operations to produce recycled aggregates and found that a plant dealing with 10,000 tonnes per year or more, or a mobile system used to process stockpiles in excess of 500 tonnes per site visit, could be economically viable.
Such small-scale plants should be encouraged as they are not colour sensitive and would allow the recycling of glass without incurring the significant emissions from the transport of glass.
There was not sufficient data readily available to carry out a similar assessment of the viability of small-scale recycling plants for plastics. However, for local small-scale recycling to be viable new uses for post-consumer plastic will need to be found. The results of the recycling study suggest that “there is a total dependence on road transport to move glass and plastics from the kerbside/bring bank to the repressors.” The greatest mileage occurs taking glass to the bring bank/recycling pavilion. Despite assuming that only 1% of the total estimated trips to these facilities are dedicated, this part of the transport chain accounts for approximately 95% of the kilometres per tonne of glass moved.
For kerbside collections, the mileage from kerb to stockpile/materials reclamation facility, dominates the transport chain, and in rural areas is, in general, about eight times the average mileage to the reprocessor, per tonne of glass.
The distance travelled collecting and delivering plastic for recycling ranged from 120 to 272 km per tonne of plastics. The equivalent figures for glass were 240 to 1,270km per tonne of glass.
The range reflects the density of households and the distances to the nearest reprocessor, as well as whether the transport chain includes household trips to bring banks and recycling pavilions.
Dealing with transport the study says: “The CO2 emissions from transporting glass and plastics for recycling can be significant, varying from 56 to 429 kg/tonne. Emissions are greatest from pre-sort kerbside collections for glass and post-sorted kerbside collections for plastics.”
Emissions of NOx and PM10 are greatest from bring bank collections for glass and post-sorted kerbside collections for plastics. The high emissions for the latter transport chain are likely to be a result of the small sample size for plastic recycling, the study says. Looking at the results for total emissions the study says that, in general, most of the emission occur during the transportation and reprocessing of the glass and plastics. The balance between transport and reprocessing emissions depends on the scenario. For NOx, the contributions vary from 98% from transport to 56% from reprocessing. Energy use at the materials reclamation facility and during glass crushing is modest, and the emissions reflect this.
The study anticipates that emissions from road transport will decline over the period 2000 to 2010 with the introduction of cleaner vehicles and fuels. This is particularly important for heavy duty vehicles.
Waste management emissions
The second report on emissions from waste management options compares air pollution created by the treatment of municipal waste in different ways, including incineration, pyrolysis, gasification, landfill, composting and anaerobic digestion. Comparative data for these technologies is given, and areas where further research is needed are identified.
The study suggests that emissions of dioxins and furans from landfill gas flaring may be more serious than from other disposal options. By contrast, dioxin emissions are lower from anaerobic digestion and small-scale incineration with presorting of waste.
There are significant differences between the emissions estimates in this study and the forecasts provided by the Environment Agency’s WISARD model. The study consultant, Enviros Aspinwall, suggests that this may be because more emissions data has become available since the WISARD model was compiled.