Purpose To ensure the sustainability of rice husk recycling schemes, there are essential conditions that should be considered. In this study, a system in which a fertilizer was obtained after rice husk heat treatment, which also produces hot water as a heat recovery strategy, was considered, and its financial sustainability, based on different conditions in place, was then evaluated. Method Based on a previous study, three essential conditions that are necessary for the sustainability of the system were identified (i. e., free or low-cost rice husk collection and hauling, production of silica in the amorphous state, and complete recycling of rice husk ash). The necessity of these conditions was confirmed based on the sustainability of the financial balance of the system. Results A 24-h d-1 operated system is more profitable than one that is operated at 6-h d-1. The pelletizing process is costly; however, the fertilizer in the pellet form can be sold at a relatively higher price. The system was unsustainable when rice husk collection and hauling as well as ash disposal fees were charged. Conclusion Therefore, the cost of rice husk collection, hauling, and ash disposal as well as the amorphous state of the ash were confirmed as conditions that are necessary to ensure the sustainability of a rice husk recycling scheme.

This research introduces a novel biomass-catalyst interaction approach in the catalytic pyrolysis process. The use of in-situ catalytic pyrolysis, where the catalyst is directly added to biomass followed by pelletization to enhance the quality of gas and bio-oils, remains underexplored. This method facilitates better contact between the biomass and the catalyst, leading to altered decomposition mechanisms and selective product formation. The study focused on the pyrolysis of rice husk pellets, using rice husk ash as a catalyst. Catalytic slow pyrolysis was analyzed in terms of apparent kinetics and product characterization through a self-designed macro-thermogravimetric analysis. The pellets were heated from 303 to 873 K at a rate of 10 K/min in an N2 atmosphere. Gas was collected and analyzed using the GC-TCD method at various temperature intervals during pyrolysis. Additionally, bio-oil and char were analyzed with GC-MS and FT-IR methods. The findings revealed that a single-stage multi-component kinetic model effectively described the pyrolysis reaction. The ash slightly accelerated the decomposition rates of hemicellulose and lignin but inhibited cellulose decomposition. The catalytic effect of the ash was more pronounced at higher temperatures. The gas composition was predominantly CO and CO2, with CH4 and H2 becoming detectable at temperatures above 723 K. The addition of ash increased the concentrations of H2, CH4, and CO2, while reducing CO levels. Furthermore, the ash reduced the corrosiveness of bio-oil by decreasing oxygenates and acids, thereby enhancing its energy density due to an increase in light phenolics and monocyclic aromatic hydrocarbons. Future research should focus on improving the catalytic activity of husk ash to further optimize its role in pyrolysis processes.

Purpose: Rice husk is one of the most widely available agricultural wastes in many rice producing countries of the world. Here, we evaluated carrot production under different rice husk-amended media aimed at providing alternative use for rice husk. Methods: The experimental design was 2 × 5 × 4 factorial in completely randomized design with six replications. Factor A consist of two production environments— high tunnel and open field while factor B was five growth media— 5: 0: 0, 4: 0: 1, 3: 1: 1, 2: 2: 1 and 1: 3: 1 (topsoil: rice husk: poultry manure). Factor C was four carrot varieties; ‘ Touchon’ , ‘ Amazonia’ , ‘ Carrot New Kuroda’ and ‘ Touchon Mega’ . Data were collected on seedling emergence and yield parameters. The analysed means were separated using FLSD( 0. 05). Results: The biomass yield from plants grown in high tunnel was significantly higher than plants in the open field. Highest root weight, wet and dry biomass yield were obtained from medium 4: 0: 1 followed by 3: 1: 1. Harvest index ranged from 32. 3% in medium 1: 3: 1 to 62% in 3: 1: 1. Days to seedling emergence among varieties ranged from 8. 5 to 11. 3. ‘ Amazonia’ variety produced the highest root weight, wet and dry biomass yield and was followed by ‘ Touchon Mega’ . Conclusion: Carrot seedling emergence and yield differed in rice husk-amended media under high tunnel and open field environments. ‘ Amazonia’ variety grown in media 4: 0: 1 or 3: 1: 1 gave the best yield. Inclusion of rice husk in media formulation beyond an optimum rate resulted in yield reduction in carrot. Carrot is sensitive to the physio-chemical properties of its growth medium.