Resource utilization of MSWI fly ash supporting TiO2/BiOCl nanocomposite for enhanced photocatalytic degradation of sodium isopropyl xanthate: Mechanism and performance evaluation.

The removal of organic pollutants in water environments and the resource utilization of solid waste are two pressing issues around the world. Facing the increasing pollution induced by discharge of mining effluents containing sodium isopropyl xanthate (SIPX), in this work, municipal solid waste incineration fly ash (MSWI FA) was pretreated by hydrothermal method to produce stabilized FA, which was then innovatively used as support for the construction of FA/TiO2/BiOCl nanocomposite (FTB) with promoted photocatalytic activity under visible light and natural sunlight. When the content of FA was 20 wt% and the mass ratio of TiO2 to BiOCl was 4:6, a remarkable performance for the optimal FTB (20-FTB-2) was achieved. Characterizations demonstrated that TiO2 and BiOCl uniformly dispersed on FA contributing to high surface area and broad light adsorption of FTB, which exhibits excellent adsorption capacity and light response ability. Build in electric field formed in the interface of TiO2/BiOCl heterojunction revealed by density functional theory calculations accelerated the separation of photoinduced e- and h+, leading to high efficiency for SIPX degradation. The synergetic effect combined with adsorption and photocatalytic degradation endowed 20-FTB-2 superior SIPX removal efficiency over 99% within 30 min under visible light and natural sunlight irradiation. The photocatalytic degradation pathways of SIPX were determined through theoretical calculations and characterizations, and the toxic byproduct CS2 was effectively eliminated through oxidation of •O2-. For 20-FTB-2, reusability of photocatalyst was showed by cycle tests, also the concentrations of main heavy metals (Pb, Zn, Cu, Cr, and Cd) in the liquid phases released during photocatalyst preparation process (< 1 mg/L) and photodegradation process (< 8.5 µg/L) proved the satisfactory stability with low toxicity. This work proposed a novel strategy to develop efficient and stable support-based photocatalysts by utilizing MSWI FA and realize its resource utilization.

A new pattern of the partial nitrification and Anammox immobilized gel beads: core-shell embedded carrier.

Single-stage partial nitrification and Anammox (PN/A) is an efficient and energy-saving denitrification process for wastewater. However, its application is limited by the growth conditions of microorganisms. Therefore, we improved the PN/A by developing a novel core-shell embedded carrier. With Anammox gel as the core and Ammonia-oxidizing bacteria gel as the shell, these beads can achieve dissolved oxygen partitioning and provide a suitable environment for the growth of different bacteria. On this basis, the influence of the shape of core-shell embedded gel on nitrogen removal performance was systematically studied, and the internal morphology and pore size of gel beads were characterized. The results showed that the nitrogen removal efficiency of spherical and square gels was increased by 33.70% and 13.47%, respectively, in the batch test. Fluorescence in situ hybridization confirmed the stratified growth of ammonia-oxidizing bacteria and Anammox in carriers, and the relative abundance value of the two bacteria were 1.25:1 and 1.43:1, respectively. Although the mechanical strength of square gel beads is slightly higher than that of spherical, spherical gel is considered the most suitable gel shape due to its small pore size and poor pore connectivity, which ensures the matching of internal Anammox and external PN reaction. In the long-term experiment, the core-shell embedded beads still had the design characteristics, and the TN removal efficiency was increased by 36.25% despite occasional oxygen excess.

Effect of magnetite on the catalytic oxidation of polycyclic aromatic hydrocarbons in fly ash from MSW incineration: A comparative study of one-step and two-step hydrothermal processes.

Polycyclic aromatic hydrocarbons (PAHs), many of which are carcinogenic, teratogenic, and mutagenic, exist in fly ash (FA) produced from municipal solid waste incineration (MSWI). Hydrothermal treatment (HT) is an efficient approach to remove PAHs from MSWI FA. Here, magnetite (Fe3O4) was used as the catalyst and hydrogen peroxide (H2O2) as the oxidant for one-step and two-step catalytic hydrothermal methods. When the magnetite dosage increased to 15 wt%, the maximum degradation rates of PAHs were 84.36% and 92.51%, respectively; however, the toxicity equivalent quantity (TEQ) degradation rates of the PAHs both increased upon increasing the magnetite dose. At 20 wt% Fe3O4, the maximum TEQ degradation rates of the PAHs were 93.29% and 97.76%, respectively. The reaction between OH and PAHs is non-selective, which means that LMW, MMW, and HMW PAHs were all degraded. The decrease in TEQ was mainly due to the degradation of HMW PAHs, i.e., those with five rings. Under the same Fe3O4 dose, oxidant dose, and reaction time, the detoxification of PAHs by the two-step method was significantly better than that of the one-step method, possibly because the two-step method more effectively produced OH. The first step degraded more than 90% of PAHs, and the residual PAHs in the HT products of the first step limited the utilization of the oxidant during the second step. The minerals in the HT products implied that the two-step hydrothermal method not only produced more OH, which reacted with PAHs, but also generated metal-magnetite substitution, which affected its surface reactivity during heavy metal adsorption and catalysis. These results revealed that both magnetite and the two-step hydrothermal treatment degraded PAHs. 20 wt% magnetite was the optimal amount during the two-step hydrothermal catalytic oxidation of MSWI FA.

Enhancement of catalytic detoxification of polycyclic aromatic hydrocarbons in fly ash from municipal solid waste incineration via magnetic hydroxyapatite-assisted hydrothermal treatment.

The emission of carcinogenic, teratogenic, and mutagenic polycyclic aromatic hydrocarbons (PAHs) during municipal solid waste incineration (MSWI) of fly ash (FA) has attracted significant attention. Hydrothermal treatment (HT) has emerged as a practical approach for degrading PAHs during MSWI of FA by utilizing magnetite (Fe3O4) as a catalyst and hydrogen peroxide (H2O2) as an oxidizing agent. In this study, as an alternative to traditional hydroxyapatite (HAP), eggshell-derived magnetic hydroxyapatite (MHAP) was synthesized and applied in the hydrothermal catalytic degradation of PAHs in MSWI FA in an H2O2 system for the first time. The degradation efficiency of the PAHs is influenced not only by H2O2 but also by the choice of hydroxyapatite. Adding HAP or MHAP during hydrothermal treatment with H2O2 substantially reduced the overall PAH concentration and toxicity equivalent quantity (TEQ), superior to that without H2O2. MHAP demonstrated superior catalytic activity compared to HAP in the presence of H2O2 in the hydrothermal system. The hydrothermal detoxification of the PAHs increased with increasing MHAP dosage. By employing 0.5 mol/L H2O2 as the oxidant and 15 wt% MHAP as the catalyst, a total PAH degradation rate of 88.9 % was achieved, with a remarkable TEQ degradation rate of 98.3 %. Notably, the level of 4-6-ring PAHs, particularly benzo(a) pyrene (BaP) and dibenz(a,h)anthracene (DahA), with a TEQ of 1.0, was significantly reduced (by 69.4 % and 46.0 %, respectively). MHAP remained stable during the hydrothermal catalytic process, whereas H2O2 was effectively activated by MHAP and decomposed to produce strongly oxidizing hydroxyl (•OH) under hydrothermal conditions. •OH produced from the decomposition of H2O2 and metals on the surface of MHAP act as catalytically active centers, efficiently converting high-ring PAHs to low-ring PAHs. These findings provide valuable insights and a technological foundation for PAH detoxification in MSWI FA via hydrothermal catalytic oxidation.

Hybrid Optimization Algorithm Based on Double Particle Swarm in 3D NoC Mapping.

Increasing the number of cores on a chip is one way to solve the bottleneck of exponential growth but an excessive number of cores can lead to problems such as communication blockage and overheating of the chip. Currently, networks-on-chip (NoC) can offer an effective solution to the problem of the communication bottleneck within the chip. With current advancements in IC manufacturing technology, chips can now be 3D-stacked in order to increase chip throughput as well as reduce power consumption while reducing the area of the chip. Automating the mapping of applications into 3D NoC topologies is an important new direction for research in the field of 3D NoC. In this paper, a 3D NoC partitioning algorithm is proposed, which can delineate the 3D NoC region to be mapped. Additionally, a double particle swarm optimization (DPSO) based heuristic algorithm is proposed, which can integrate the characteristics of neighborhood search and genetic algorithms, and thus solve the problem of a particle swarm algorithm falling into local optimal solutions. It is experimentally demonstrated that this DPSO-based hybrid optimization algorithm has a higher throughput rate and lower energy loss than the traditional heuristic algorithm.