No abstract

Currently no one universal method exists for processing FTIR data for polyhydroxyalkanoates (PHA) quantification. This study compares three different methods of analysing FTIR data for quantification of PHAs in biomass. A new data-processing approach was proposed and the results were compared against existing literature methods. Most publications report PHA quantification of medium range in pure culture. However, in our study we encompassed both mixed and pure culture biomass containing a broader range of PHA in the calibration curve. The resulting prediction model is useful for rapid quantification of a wider range of PHA content in biomass.

Thermomechanical pulps (TMPs) were prepared from Pinus radiata D. Don wood chips at pilot scale with application of different preheating severities. The hydrolysis products were separated at the compression screw feeding of the prehydrolysed chips into the refiner. Prehydrolysis of chips with steam at severity factor (SF) 3.5 reduced the refining energy (at 200 CSF freeness) by 36% when compared with the TMP control; however, the pulp quality was unacceptable. In contrast, pulps produced by SF 3.1 at 155°C have physical properties similar to the TMP control, but the energy saving is only 12%. Prehydrolysis darkens wood fibres making pulps unsuitable for printing and writing papers. However, it was demonstrated that the brightness may be recovered via conventional alkaline peroxide brightening. Pulp yield is lower but this disadvantage is offset by the availability of a pressate flow rich in hemicelluloses and hemicelluloses derived sugars in high concentrations that has good potential for conversion to new products. Impregnation of chips with citric acid (CA) during normal TMP processing was also investigated. Although refining energy was lower with CA treatment, the amount of extracted hemicelluloses was too small to be commercially useful. The prehydrolysis-TMP process may be of interest to financially constrained TMP mills provided that: (1) the process configuration is suitable for retrofitting an extended preheating stage with compression screw and (2) the extracted hemicelluloses can be converted to products of higher value than TMP.