Peat dewatering

Geladi P, Bergner H, Ringqvist L, From experimental design to images to particle size histograms to multiway analysis. An example of peat dewatering, Journal of Chemometrics, 2000, 14, 197-211. 

The use of polymer combinations for the improvement of flocculation efficiency is not new and was described earlier [1-24]. Two or even more components, added in sequence as flocculant systems, produce synergistic effects on the flocculation. Many different systems have been applied in the paper industry, and also in other fields like peat dewatering [1], flocculation of harbor sediments [2], wastewater [3], or sugar beet washings [4]. 

Ringqvist L, Igsell P (1994) Dual polymer system in peat dewatering. Energy Fuel 8 953... 

In a study on dewatering methods for peat, displacement dewatering was done using acetone, a polar solvent having a lower heat of vapori2ation than water. Dewatering was improved in terms of both the pressure filtering step and the quantity of heat required. Less heat was required to dry the cake and recover the acetone from the filtrate by distillation (31). 

Hatcher P. G., Spiker E. C., and Orem W. H. (1986) Organic geochemical studies of the humification process in low-moor peat. In Peat and Water, Aspects of Water Retention and Dewatering in Peat (ed. C. H. Euchsman). Elsevier, London, pp. 195-213. 

Another feature of salt-marsh peat restricting its buoyant response is the interconnectedness of the bulk material Peat near the surface is not isolated, but is enmeshed by its roots into a semiinfinite layer of peat some tens of centimeters thick. The buoyant-peat model predicts that if periodic recharge of this perched-water table was prevented, then substantial dewatering and compression would occur. As it turns out, this experiment has already taken place Diking of salt marshes was one of the means used in the past to reclaim them for agricultural purposes, and following that treatment the marshes were reported to have shrunk considerably, in some cases as much as 3 feet (Smith, 1907). 

Rather few papers deal with the kinetics of biofuel drying and most designs seem to be experience-based. Bagasse is reported to be easily dewatered with exit temperatures for commercial rotary dryers approaching the wet bulb temperature [7]. A study of drying rates of milled peats [21] in a fluid-bed bench-scale dryer showed no influence on the origin of the peat. On the other hand, different size fractions of the same peat gave quite different results. The intraparticular resistance is pronounced and, of course, controlled by the particle size. 

Hydrothermal treatment of Hokkaido cold climate peat has also been investigated. However, it is still necessary to evaluate the liquid and gas products formed during the process to facilitate its energy and chemical utilization. The aim of this chapter is to characterize and determine the effectiveness of hydrothermal treatment for upgrading and dewatering processes on the solid products of Hokkaido cold climate peat as well as to determine its artificial coalification process by applying of FTIR and i C NMR spectroscopy. A fundamental study of the effects of processed temperature on the products of hydrothermal treatment of cold climate peat is also described in this Chapter. 

The liquid content of the raw peat was 86.9 wt.%, which corresponded to the moisture content, and the products increased from 87.3 wt.% to 89.4 wt.% as the temperature increased. As the temperature increased, the gas products content increased from 1.6 wt.% to 4.8 wt.%. The increase in the liquid and gas products in response to increasing temperature suggest that dewatering and decomposition occurred during the process. Takahashi peat that contained most of the organic constituents of the original plant materials were least decomposed and peatification occurred shortly. The amounts and concentration of plant constituents, peat bitumen (benzene/ethanol soluble) and humic substances in Takahashi moss peat are described in Table 2. 

Mursito, AT. Hirajima, T. Sasaki, K. (2010). Upgrading and dewatering of raw tropical peat by hydrothermal treatment. Fuel, Vol.89, pp. 635-41. 

Coal metamorphism is the consequence of burial, particularly in the dewatering from peat to lignite to subbituminous coal, and enhanced temperatures. Temperature ino-ease can be the result of burial at varying geothermal gradients, influx of thermal waters or brines through the coal, or, in rare cases, contact metamorphism in the vicinity of igneous intrusions. 

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