Dehydration of paddy rice in a chitosan membrane drier

A chitosan membrane was used to separate water vapor evaporated from moist paddy rice out of the apparatus, called the “membrane drier”. It was aimed as an alternative method to dry harvested paddy instead of the traditional open air technique that can encounter rain or flooding problems. The prototype membrane drier was designed from a mathematical air flow pattern analysis, where it was found that a horizontal flow mode with a baffle plate and triangle air flow path (HFwBF&TFP) was the most appropriate feature. The chitosan membranes studied in this research were uncrosslinked dense (UCD), crosslinked dense (CD), uncrosslinked composite-on-spunbond (UCC) and crosslinked composite-on-spunbond (CC) membranes. The highest drying rate of the membrane drier equipped with UCD, CD, UCC and CC membranes occurred in the first hour of operation at 46.4 ± 0.4, 51.7 ± 6.7, 57.8 ± 0.9 and 71.5 ± 4.9 g-water/kg-moist-paddy/h, respectively. Compared to the drying rate by the open air technique and a hot air oven at 40 °C (52.7 ± 0.7 and 40.2 ± 0.7 g-water/kg-moist-paddy/h, respectively), the chitosan membrane drier could be used as an alternative method for drying biomass, such as paddy rice. The CC chitosan membrane drier could reduce the moisture content of harvested paddy rice from 22.8 ± 0.4 to 15.7 ± 0.9% within 1 h.