2. Methods
2.1. Processing
The industrial process was run at full capacity utilising local
authority derived MSW for 10 consecutive days. Successive nonsorted
batches of the MSW (12 20 tonne batches in a 24 h period)
were treated by roto-autoclaving, at 140 C for 45 min at a
maximum pressure of 3 bar before depressurisation and cooling
(20 min). This process was followed by extensive semicontinuous
mechanical separation which included an initial finger
screen which removed large items (>200 mm), followed by; air
separation, magnets, eddy current separators, optical sorters, glass
separators, and a manual picking station (to remove further textiles,
and large items). This produced 6 distinct waste streams –
glass, plastic, ferrous metals, non-ferrous metals, textiles, and a
fibrous material (diameter 6 12 mm). A waste stream mass balance
was not conducted during this trial as the focus was exclusively
on the fibre output.
A composite sampling protocol was carried out based on ASTM
D5956-96 (2006) and ASTM D6051-96 (2015) for fibre analysis
(rather than using sorting based methods usually applicable to
MSW e.g. ASTM D5231-92 (2008)). Samples were obtained at the
final point of mechanical separation whereby 8.5 kg of the fibrous
material (612 mm) was collected at intervals of 2 h for 24 h (in a
large covered receptacle). Each 24 h period was classified as 1 sampling
day (there were 10 consecutive sampling days). After the
24 h period, the resulting material (102 kg) was thoroughly mixed
and divided using coning and quartering (ISO 23909, 2008) and
25 kg of the resultant homogenised bulk sample was divided into
distinct aliquots which were either refrigerated (4 C), frozen
(80 C), or dried (at 105 C) for down-stream analysis (outlined
in Sections 2.2–2.6). The storage, preservation and processing
times of samples was dictated by the downstream methods used
(Sections 2.2–2.6).
2.