Due to the significant quantities of waste generated by the Sri Lankan rice industry, circular bioeconomy methodologies were applied to examine value-adding entrepreneurial activities for rice industry by-products (RIB). The study was conceived after scouring the existing literature on agricultural waste management and interviewing experts in the field and the rice industry. In the first phase, the suitability of valorizing alternatives for RIB was considered via a multi-criteria decision-making method. Valorization options, such as biochar production, energy purposes, composting, and other activities, were evaluated using an analytical hierarchy process (AHP) based on four criteria, namely environmental, social, technical, and economic issues. The results indicated that the highest priority should be given to environmental, social, and economic considerations, with local priority vectors of 0.5887, 0.2552, and 0.0955, respectively. It was found that biochar production is the optimal valorization strategy for managing RIB in Sri Lanka. From these findings, the development of a sustainable business model for making biochar out of RIB was done based on commercial motivations and value addition in biochar manufacturing processes. The Business Model Canvas elements played a vital role in categorizing and interpreting the case study data. Though the RIB seems undervalued at present, it was found that as a direct result of environmental concerns, several stakeholders have developed RIB valorization with an emphasis on bioenergy generation and biochar production. Adequate subsidies (technology and knowledge), standard regulations, more collective actions for creating economies of scale, and marketing strategies (consumer awareness) are all necessary for the successful implementation of sustainable circular business models.

This study investigates the design and development of a pyrolysis reactor for batch-type biochar production from rice husks. The main objective is to develop an appropriate technology to regulate pyrolysis temperature and biomass residence time that can be easily operated under field and household conditions with minimal operational and technical requirements. The designed novel dual-chamber reactor comprises two concentrical metal cylinders and a syngas circulation system. The outer cylinder is for energy generation and the inner one is for pyrolysis. Temperature profiles, energy exchanges, syngas production, and the physicochemical characteristics of biochar were obtained to determine the performance of the reactor. Different trials were carried out to obtain different pyrolysis temperatures under constant amounts of feedstock and fuel. The temperature was monitored continuously at three predetermined reactor heights, the temperature profile varied from 380 °C to 1000 °C. The biochar yield was 49% with an average production rate of 1.8 ± 0.2 kg h⁻¹. The reactor consumed 11 ± 0.1 kg of rice husk as feedstock and 6 ± 1 kg h⁻¹ of wood as fuel. The gaseous products from the pyrolysis were CH₄, CO₂, H₂, CO, and C_nH_m, which contributed 23.3 ± 2.3 MJ m⁻³ of energy as fuel for the pyrolysis process. The specific surface area of the biochar was 182 m² g⁻¹. The achieved operational capacity and thermal efficiency of the reactor show biochar production is a suitable option to convert discarded biomass into a value-added product that can potentially be used in several environmental applications.

Background: Paddy cultivation is a major occupation in informal sector in Sri Lanka. In 2014, contribution of the agricultural activities to the country’s annual GDP was 9.9% of which, contribution by paddy was 11.3%. The objective of the current study was to describe the work environment in rice mills with respect to dust, humidity and thermal condition, ventilation and illumination.Methods: A cross sectional study in 107 randomly selected rice mills was carried out in Ampara district in Sri Lanka. Standardized measurements were carried out to assess internal work environment of the mills.Results: Milling activities showed a seasonal variation. The majority of the mills (95.3%) manufactured raw rice only. Other than the basic characteristics, both automated (AMs) and non-automated mills (NAMs) showed common features. All rice mills exceeded the threshold limit values for total (520.04 mg/m3, SD=191.86 mg/m3) and respirable dust (48.14 mg/m3, SD=9.4 mg/m3). Mean daytime indoor relative humidity in the majority of the mills (n=102, 95.3%) was within the accepted upper limit. In most of the mills, ventilation (n=84, 78.5%) and illumination in polishing/packing area (n=60, 56.1%) was satisfactory while in dehusking/paddy inlet area (n=96, 89.7%), illumination was below the limits.Conclusions: Work environment in both the AMs and NAMs in Ampara district presented with poor work standards compared to the required guidelines.

This study investigates scientific insights into the adsorption mechanism of novel engineered biochar derived from coconut s hells via catalytic conversion with FeCl3 for Malachite Green removal. This is a unique research report describing the use of novel engineered biochar derived from waste coconut shells for the removal of the cationic dye “Malachite Green” by understanding the insights into the adsorptive removal mechanism. The engineered biochar was prep ared with different concentrations (5 %, 7 %, and 9 %) of iron catalyst (FeCl3) and at different pyrolysis temperature s: 200 °C, 300 °C, and 400 °C with residence time of 4 hours. An adsorption analysis was planned under the set of experimental conditions: dosage 1g/L; pH 6; rpm 150; holding ti me 72 hours to identify the best-engineered biochar. The adsorptive performance was checked with artificially polluted water. The engineered biochar with the high qe value (amount of adsorbate removed by unit weight of engineer ed biochar) was selected. Detailed isotherm analysis, Kinetics study, thermodynamics analysis, and rate-limiting fac tor analysis were carried out for engineered biochar with higher adsorptive capacity. The biochar treated with 9% F eCl3 and pyrolysed at 400 °C showed the highest adsorption capacity of 50.20 mg/g for Malachite Green due to increased mineral components and a denser carbon network. I sotherm analysis revealed that the Freundlich model fits well, and the adsorption nature of Malachite Green by 9% CSBC 400 is a multilayer. The results of the adsorption kinetic study revealed that the pseudo-second order model fits well, indicating that the chemisorption process play s a significant role in the removal of Malachite Green by 9% CSBC 400. The adsorption process is spontaneous and endothermic. Therefore, the engineered biochar produced by the iron catalyst is a novel adsorbent for Malachite Green removal. This innovative finding of the use of engineered biochar produced from coconut shells for the removal of malachite green opens the door to the development of novel strategies for the effective removal of dye at the commercial level.