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COMPOSTING STUDIES USING SEPARATED FRACTION OF URBAN WASTE FROM THE BYKER RECLAMATION PLANT, NEW CASTLE, UNITED KINGDOM
The fines are produced by screening incoming refuse through a 50 mm trommel, and account for approximately 35% of refuse input to the plant by fresh mass.
The oversize is further processed for energy recovery.
The fines fraction typically contains (by mass 40% putrescible matter (excluding paper and card) 20–30% glass and 10–30% matter with particle size less than 10 mm, on an as received basis.
Battery removal prior to composting using an overband magnet has been evaluated.
The battery content of input fines is at least 0.1 to 0.2% by mass, as received.
Bulk reduction over composting amounts to 30–40% of input mass on a fresh mass basis.
Moisture content has been found to decrease from 30–40% to 20–30% whether the pile is watered prior to composting or not.
Both aeration with and without temperature control to achieve a process temperature ceiling of 55°C have been tested.
Post-processing trials included use of flat bed and trommel screens air tabling and air classification.
The effects of these processes on glass contents has been evaluated.
Glass content can be reduced to less than 1% but only at the expense of low yields of product.
Pelleting through a 5 mm die masks residual glass, improves ease of handling and increases bulk density.