Waste Disposal & Sustainable Energy最新文献

Hydrothermal carbonization (HTC) technologies for producing value-added carbonaceous material (hydrochar) from coal waste and sewage sludge (SS) waste might be a long-term recycling strategy for hydrogen storage applications, cutting disposal costs and solving waste disposal difficulties. In this study, hydrochars (HC) with high carbon content were produced using a combination of optimal HTC (HTC and Co-HTC) and chemical activation of coal tailings (CT), coal slurry (CS), and a mixture of coal discard and sewage sludge (CB). At 850 °C and 800 °C, respectively, with a KOH/HC ratio of 4:1 and a residence time of 135 min, activated carbons (ACs) with the highest Brunauer–Emmett–Teller specific surface (S_BET) of 2299.25 m²g^{− 1} and 2243.57 m²g^{− 1} were obtained. The hydrogen adsorption capability of the produced ACs was further studied using gas adsorption isotherms at 77 K. At 35 bars, the values of hydrogen adsorbed onto AC-HCT (AC obtained from HTC  of CT), AC-HCS (AC obtained from HTC of CS), and AC-HCB (AC obtained from HTC of the blending of coal discard (CD) and SS) were approximately 6.12%, 6.8%, and 6.57% in weight, respectively. Furthermore, the cost of producing synthetic ACs for hydrogen storage is equivalent to the cost of commercial carbons. Furthermore, the high proportion of carbon retained (>70%) in ACs synthesized by HTC from CD and SS precursors should restrict their potential carbon emissions.

The thermal treatment of waste using grate-based systems has gained global acceptance as the preferred method for sustainable management of residual waste. This is because the energy content of the waste is utilized and quality products and residues are produced. Modern Waste-to-Energy (WtE) plants are extremely complex. Sound knowledge of “fuel” waste and its effects on the design and operation of WtE plants is crucial for the successful planning and operation of these plants. To respond to new challenges and/or priorities, developing and implementing innovative technologies is necessary. With long-term global partnerships and innovative grate and combustion technologies, Martin guarantees that in future, residual waste will be treated following ecological and economic constraints and in compliance with international legal requirements.

Plastic has caused serious "white pollution" to the environment, and the highly inert characteristics of plastic bring a major challenge for degradation. Supercritical fluids have unique physical properties and have been widely used in various fields. In this work, supercritical CO₂ (Sc-CO₂) with mild conditions was selected and assisted by NaOH/HCl solution to degrade polystyrene (PS) plastic, and the reaction model was designed using response surface methodology (RSM). It was found that, regardless of the types of assistance solutions, the factors affecting PS degradation efficiencies were reaction temperature, reaction time, and NaOH/HCl concentration. At the temperature of 400 °C, time of 120 min, and base/acid concentration of 5% (in weight), 0.15 g PS produced 126.88/116.99±5 mL of gases with 74.18/62.78±5 mL of H₂, and consumed 81.2/71.5±5 mL of CO₂. Sc-CO₂ created a homogeneous environment, which made PS highly dispersed and uniformly heated, thus promoting the degradation of PS. Moreover, Sc-CO₂ also reacted with the degradation products to produce new CO and more CH₄ and C₂H_x (x=4, 6). Adding NaOH/HCl solution not only improved the solubility of PS in Sc-CO₂, but also provided a base/acid environment that reduced the activation energy of the reaction, and effectively improved the degradation efficiencies of PS. In short, degrading PS in Sc-CO₂ is feasible, and better results are obtained with the assistance of base/acid solution, which can provide a reference for the disposal of waste plastics in the future.