Effect of pretreatment and biomass blending on bio-oil and biochar quality from two-step slow pyrolysis of rice straw.

This study investigated biomass blending and water washing to improve product quality from two-step pyrolysis of rice straw. Rice straw (RS) was mixed with groundnut shells (GNS) and wheat straw (WS) in different weight ratios. Blending RS with GNS/WS in a 1:1 ratio increased the total bio-oil yields by 7-9% and reduced the pyrolysis gas and char yields by 5-7% and < 2%, respectively. RS was washed with water separately to examine the effect of removing water-soluble ash elements. The optimum washing duration was 60 min; the ash removal efficiency was then 26%. The bio-oil yields from washed straw increased by 4% over unwashed straw, and pyrolysis gas yields decreased. Combining the washing and blending processes increased the levoglucosan yield by 1.6-2.1 times compared to unwashed RS, and the water content in bio-oil was reduced by âˆ¼ 10%. Moreover, the biochar samples obtained after pyrolysis of washed biomass blends had potential fuel applications owing to low fouling or slagging propensity. They also had possible use in the soil for adsorption of soil contaminants and increasing acidic soil pH, with likely stability of âˆ¼ 1000 years in the ground. These results provide a promising alternative for efficiently converting rice straw to multiple value-added products.

Effect of basic washing parameters on the chemical composition of empty fruit bunches during washing pretreatment: A detailed experimental, pilot, and kinetic study.

The present study aimed to evaluate the effect of basic washing parameters on the chemical composition of empty fruit bunches of oil palm (EFB) and to determine the optimal parameters for large-scale applications of washing pre-treatment. Three basic washing parameters were studied in detail: washing duration, temperature, and solid/liquid (S:L) ratio. The leaching kinetics of ash and troubling elements such as K, Cl, N, and S were also evaluated with respect to washing time. About 82-98% Cl, 64-80% S, 38-77% K, 34-67% ash, and 24-63% N removal was noted after washing EFB, which follows a second-order leaching kinetics on increasing washing duration. Two pilot washing tests were also conducted to evaluate the effectiveness of the pre-treatment on a large scale, which showed similar trends as the laboratory results. The recommended EFB washing conditions for large-scale applications are 10 min washing with a 1:15 S:L ratio at 50 °C.

Step washing: A modified pretreatment approach for industrial applications to improve chemical composition of agricultural residues.

To improve the efficiency and applicability of the washing pre-treatment for combustion, pyrolysis and gasification, a modified approach was developed in the present study. Two novel washing approaches were tested using wheat straw and empty fruit bunches of oil palm: multiple-step washing with fresh water (SWFW) and wastewater recirculation (SWWR). SWFW showed the high removal of K (<68%), Cl (<99%), S (<80%), N (<58%), and ash (<52%) reducing fouling, slagging, and corrosion propensity of the biomass. Furthermore, with one-third the amount of water used in SWFW, SWWR showed similar to higher efficiency than SWFW with relatively better energy (98%) yields. Industrial-scale pilot testing was also conducted for the validation of the SWWR approach, which showed similar findings as the lab-scale results. The effect of a high washing temperature and pressing on washing efficiency and characterisation of wastewater was also determined. Overall, SWWR with pressing is recommended for industrial applications.