A considerable mass fraction of combustibles (especially paper and cardboard and wood) of their input mass was found in the reject stream. The components of paper and cardboard and wood found in the reject stream were either large in particle size (>250 mm), irregular in shape (e.g. paper in rolled form) or highly moist (heavy in weight) [21], [23] and [26]. These components of paper and cardboard and wood were not supposed to be in the reject stream but in the SRF stream. Based on the observations, heavy weight (due to high moisture content) and irregular shape (due to large particle size and bundle form) of components (paper and cardboard and wood) and high/sudden mass flow (due to sometimes non-steady/sudden feeding of input waste material by excavator i.e. material loader at the start of process) affected the function of unit operation (air classifier and NIR sorting units) and therefore, these combustible were not got sorted out properly into the SRF stream but rather ended up in reject stream. The chlorine content of paper and cardboard and wood were measured as 0.2 wt.% (dry) and 0.075 wt.% (dry) (see Table 1) respectively which means that presence of these component in the SRF stream would have effectively reduced the chlorine content of SRF. Paper/card is reported to lower the chlorine content in the fuel i.e. RDF/SRF[16] and [27]. In the composition of SRF [21], mass fraction of plastic (hard) and textile was 16.5 wt.% and 8.5 wt.% respectively. The chlorine content measured in plastic (hard) and textile was 3.0 wt.% (dry) and 1.0 wt.% (dry) respectively. The high mass flow of chlorine into the SRF stream could be due to the high mass fraction of plastic (hard) and to some extent textile (synthetic type) components. There might be some light weight components (plastic, textile or some other) carrying pollutant or potentially toxic elements (chlorine, lead and cadmium) could have been taken away by air classifier and put into the SRF stream. Plastics are reported [29] to carry chlorine load in fuel product (SRF).The second higher mass flow of input chlorine was found in the reject stream i.e. 35%. This was due to the mass fraction of rubber and PVC-plastic in the reject stream [21]. Chlorine content of rubber was measured as 8.0 wt.% (dry). This rubber material also contained rubber shoes in it.
Mass flow of arsenic (As) was found higher in reject stream as compared with the other streams of process. The content of arsenic measured in fines i.e. 5.5 mg/kg (dry) was higher than measured in other components of input waste stream. Other than fines the content of arsenic measured in textile, foam and rubber was 2.0 mg/kg (dry), 1.6 mg/kg (dry) and 1.2 mg/kg (dry) respectively. In the composition of reject stream [21] the mass fraction of fines, textile and rubber was 17 wt.%, 9.2 wt.% and 6.8 wt.% respectively. The mass flow of cadmium (Cd) calculated in the SRF and reject stream was 46% and 40% respectively of its input concentration to the process. The content of cadmium measured in rubber was higher than that of measured in other waste components. Major mass fraction of rubber was found in the