ACS ES&T engineering最新文献

Sulfides generated from sulfate reduction commonly act as inhibitors in anaerobic digestion (AD). This study examined the performance of three configurations of microbial electrolysis cell-assisted anaerobic digestion (MEC-AD) systems: single-chamber, dual-chamber with an anion exchange membrane (AEM), and dual-chamber with a cation exchange membrane (CEM), operated under sulfate-reducing conditions. In general, the single-chamber MEC-AD reactors exhibited significantly higher methane yields (74.5–75.0%) than the control (64.4%). Upon converting a single-chamber MEC-AD to a dual-chamber configuration using an AEM, methane yield further increased up to 80.6%. The membrane facilitated the transfer of buffer anions to the anode and sulfate to the cathode, which substantially reduced un-ionized sulfide concentrations in the anode chamber. The MEC-AD with an AEM also demonstrated increased specific methanogenic activities, current densities, and microbial diversity with the enrichment of electroactive bacteria (e.g., Geobacter, Aeromonas) and hydrogenotrophic Methanobacterium. However, the MEC-AD reactor with a CEM experienced a significant reduction in methane yield (63.2%), mainly due to anolyte acidification, which increased the un-ionized sulfide concentrations.

The synergistic effect of multiple reactive oxygen species (ROS) facilitates the degradation and mineralization of recalcitrant contaminants. However, bottlenecks include the rational design of single-atom catalysts with multiple active sites to produce multiple ROS in heterogeneous catalytic ozonation (HCO) processes and the detailed interpretation of the generation mechanisms. In this study, we prepared a dual single-atom Mn–(N_x–C)–Ce catalyst with dual active sites via a simple and scalable one-pot method in which atomically dispersed active Mn–N₄ and Ce–N₄ sites synergistically promoted the generation of ^•OH. Moreover, density functional theory calculations and molecular dynamics simulations elucidated that Mn–N₄ sites on the catalyst surface preferred to generate ^•OH and ^•OH_ad, while Ce–N₄ sites preferred to generate other ROS (O₂^•–, ¹O₂, and *O_ad). The three main degradation pathways of N,N-diethyl-3-methylbenzamide (DEET) further revealed the synergistic effects of multiple ROS. Due to the ability for generation of multiple ROS, the Mn–(N_x–C)–Ce catalyst exhibited superior activity and excellent stability for the degradation of DEET and bezafibrate as well as advanced treatments of municipal sewage and coking wastewater. This study paves a new avenue for rationally designing a highly efficient and stabilized catalyst for ozone and provides an insight into the synergistic effect of Mn–Ce dual active sites in the HCO process.

This study assesses the potential of electrodialysis (ED), traditionally applied to demineralize brackish waters, for the emergent challenge of hypersaline desalination. The analysis reveals that the desalination performance of hypersaline ED is determined by two intrinsic membrane trade-offs─ion conductivity–charge selectivity and ion conductivity–water resistivity─and a process trade-off between energy consumption and concentrate volume reduction. The charge selectivity and ion–water selectivity of ion-exchange membranes (IEMs), which are both influenced by the structural property of water uptake, are principal factors affecting membrane-level performance, whereas the operating current density simultaneously impacts the module-level metrics of specific energy consumption and water recovery yield. With current commercial IEMs, the energy costs of ED can be competitive with prevailing thermally driven evaporative processes for the desalination of hypersaline streams < ≈100,000 ppm TDS (equivalent to ≈1.5 M NaCl). To enable energy-efficient ED for higher salinities, membranes capable of suppressing the detrimental effect of water permeation need to be developed. This can be attained by polymeric IEMs with low water per fixed charge site or through material innovation beyond the charged polymers of conventional IEMs.

Low-temperature thermal degradation of PCDD/Fs in incineration fly ash (IFA) has attracted widespread attention with the advantages of low energy consumption and high efficiency. However, in the process of industrialization, the inevitable O₂ leakage in the system has always been a technical bottleneck. Based on the characteristics of IFA and the mechanism of PCDD/F regeneration, this study first proposes a dual-strategy LTTD of predechlorination and reduction atmosphere-keeping. Predechlorination removes soluble chlorine and soluble metals while hydrolyzing CaClOH in IFA into Ca(OH)₂ to accelerate the detoxication of PCDD/Fs, and deep reduction atmosphere-keeping is created by introducing activated carbon to inhibit the possible PCDD/F regeneration. Compared with typical LTTD, synergistic application of dual-strategy LTTD can obtain 99.4 and 97.4% detoxification efficiencies of PCDD/Fs in the presence of 1 and 2% O₂, respectively. Based on the identification of congener distribution and density functional theory calculations, the dechlorination mechanism of acid chloride group-containing PCDD/F intermediates with the participation of CO and Ca(OH)₂ was proposed. Finally, the reproducibility of dual-strategy LTTD after optimization of working parameters was well verified and the proposed dual strategies are expected to provide a new direction for the industrialization of LTTD.