Search Results (4)

Blockages in a transfer system are a crucial problem for the wet coals conveying process in thermal power plants. Improving the viscous material flow is a fundamental solution to prevent blockages. A discrete element simulation was employed to investigate the flow characteristics of viscous materials in transfer systems with different structures under vibration-assisted conditions. The results indicate that, near the structure wall, the adhesive force increased, which was the root cause of material blockages. Introducing vibration motions into the chute could break the adhesive forces between the wet particles and the structure wall. Compared with a linear chute, a curved chute was more sensitive to vibration movement and had less leftover viscous materials and a lower output velocity. Compared with a deflector hood, an impact plate had less residual material and a higher particle velocity because of its longer ejection distance and lower adhesive force. Based on the above simulation results, a transfer system with an impact plate and curved chute is proposed. By introducing the critical vibration intensity for the transfer system, the vibration parameters and transfer system structures are optimized. The aforementioned research findings provide guidance for intervention measures aimed at preventing material blockages in industrial bulk material conveying processes. Full article

The alarming rise of food waste all over the world due to population and economic growth must be tackled with better waste management and treatment methods. The current practice of landfilling has been scientifically proven to adversely impact environmental and societal health. A relatively new technology called hydrothermal carbonization (HTC) has the potential to solve this problem. It takes in high-moisture-content material, like food waste, and converts it into bio-coal with a heating value similar to normal coal. The present study explored the feasibility of HTC technology and bio-coal production in Malaysia. An in-depth study via desk research was conducted by implementing Porter’s five forces analysis to evaluate the feasibility of the bio-coal production project. A survey involving 215 respondents from different households that represent the average demography of Malaysia was also conducted to understand the behaviors and attitudes of different households towards food waste. The present study found that a typical Malaysian household disposes mostly of meal leftovers, with an average of 926 g of food waste per day. In addition, the 3 highest food categories that were disposed of were rice or noodles or pasta (13.0%), vegetables (12.2%) and curry and soup (10.1%). Meal leftovers such as curry and soup are high in moisture content, which is suitable for HTC. The survey on household waste provided adequate information to support the availability of a sufficient quantity of food waste in the country to sustain the raw material for the bio-coal project in Malaysia. Furthermore, a consumer survey involving seven industrial firms was conducted to determine the potential buyers of bio-coal. The responses from the industrial firms show that a bio-alternative for coal is important, and they are willing to transition to greener technologies. However, five out of seven firms stated that the main hurdle in adopting bio-coal is the high cost of production and incompatibility with existing industrial processes. Finally, interviews were conducted with key players in the industry to evaluate the adoptability of bio-coal into the wider market. The findings from the desk research and the primary research show that the outlook for bio-coal in the market is quite positive. In the long run, HTC is certainly profitable, but for immediate benefits, adequate government support and policy in favour of the use of HTC bio-coal in power plants are required. Full article

The excessive discharge of phosphate from anthropogenic activities is a primary cause for the eutrophication of aquatic habitats. Several methodologies have been tested for the removal of phosphate from aqueous solutions, and adsorption in a flow-through reactor is an effective mechanism to reduce the nutrient loading of water. This research aimed to investigate the adsorption potential of leftover coal material to remove phosphate from a solution by using continuous flow fixed-bed column, and analyzes the obtained breakthrough curves. A series of column tests were performed to determine the phosphorus breakthrough characteristics by varying operational design parameters such as adsorbent bed height (5 to 8 cm), influent phosphate concentration (10–25 mg/L), and influent flow rate (1–2 mL/min). The amorphous and crystalline property of leftover coal material was studied using XRD technology. The FT-IR spectrum confirmed the interaction of adsorption sites with phosphate ions. Breakthrough time decreased with increasing flow rate and influent phosphate concentration, but increased with increasing adsorbent bed height. Breakthrough-curve analysis showed that phosphate adsorption onto the leftover coal material was most effective at a flow rate of 1 mL/min, influent phosphate concentration of 25 mg/L, and at a bed height of 8 cm. The maximal total phosphate adsorbed onto the coal material’s surface was 243 mg/kg adsorbent. The Adams–Bohart model depicted the experimental breakthrough curve well, and overall performed better than the Thomas and Yoon–Nelson models did, with correlation values (R²) ranging from 0.92 to 0.98. Lastly, leftover coal could be used in the purification of phosphorus-laden water, and the Adams–Bohart model can be employed to design filter units at a technical scale. Full article

High loadings of wastewater with phosphors (P) require purification measures, which can be challenging to realize in regions where the technical and financial frame does not allow sophisticated applications. Simple percolation devices employing various kinds of adsorbents might be an alternative. Here, we investigated the application of leftover coal, which was collected from Ethiopian coal mining areas, as an adsorbent for the removal of phosphate from aqueous solutions in a classical slurry batch set-up. The combined effects of operational parameters such as contact time, initial concentration, and solution pH on P retention efficiency was studied employing the Response Surface Methodology (RSM). The maximum phosphate adsorption (79% removal and 198 mg kg⁻¹ leftover coal) was obtained at a contact time of 200 min, an initial phosphate concentration of 5 mg/L, and a solution pH of 2.3. The Freundlich isotherm was fitted to the experimental data. The pseudo second-order equation describes the experimental data well, with a correlation value of R² = 0.99. The effect of temperature on the adsorption reveals that the process is exothermic. The results demonstrate that leftover coal material could potentially be applied for the removal of phosphate from aqueous media, but additional testing in a flow-through set-up using real wastewater is required to draw definite conclusions. Full article