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The effects of two solid-based hydrogen peroxides sodium percarbonate (SPC) and calcium peroxide (CP) on waste activated sludge (WAS) disintegration were investigated. Both oxidants achieved efficient WAS disintegration for the synergistic effect of alkaline and oxidation. The strong alkaline condition led to the leakage of ammonia and the existence of abundant calcium ions accelerated the fixation of phosphorus via precipitation in CP WAS disintegration process. However, the spongy-like layer and low pH condition retarded the release of gaseous ammonia in SPC group. Hydroxyl radical was the main oxygen reactive species in SPC approaches which were more intense than CP by electron spin resonance (ESR) analysis. CP treated WAS contented more small particle size matter and total suspended solids (TSS) increased dramatically. In conclusion, CP pretreated sludge was more suitable for fertilization, while SPC was in favor of anaerobic digestion. This study clarified the differences between these two oxidants and their intermediates on nutrients release in sludge disintegration.

Herein, we report that Co(II)-doped g-C3N4 can efficiently trigger peracetic acid (PAA) oxidation of various sulfonamides (SAs) in a wide pH range. Quite different from the traditional radical-generating or typical nonradical-involved (i.e., singlet oxygenation and mediated electron transfer) catalytic systems, the PAA activation follows a novel nonradical pathway with unprecedented high-valent cobalt-oxo species [Co(IV)] as the dominant reactive species. Our experiments and density functional theory calculations indicate that the Co atom fixated into the nitrogen pots of g-C3N4 serves as the main active site, enabling dissociation of the adsorbed PAA and conversion of the coordinated Co(II) to Co(IV) via a unique two-electron transfer mechanism. Considering Co(IV) to be highly electrophilic in nature, different substituents (i.e., five-membered and six-membered heterocyclic moieties) on the SAs could affect their nucleophilicity, thus leading to the differences in degradation efficiency and transformation pathway. Also, benefiting from the selective oxidation of Co(IV), the established oxidative system exhibits excellent anti-interference capacity and achieves satisfactory decontamination performance under actual water conditions. This study provides a new nonradical approach to degrade SAs by efficiently activating PAA via heterogeneous cobalt-complexed catalysts.

In order to promote low-carbon sustainable operational management of the wastewater treatment plants (WWTPs), automatic control and optimal operation technologies, which devote to improving effluent quality, operational costs and greenhouse gas (GHG) emissions, have flourished in recent years. There is no consensus on the design procedure for optimal control/operation of sustainable WWTPs. In this review, we summarize recent researches on developing control and optimization strategies for GHG mitigation in WWTPs. Faced with the fact that direct carbon dioxide (CO

There is an increasing trend that enterprises outsource their middlebox processing to a cloud for lower cost and easier management. However, outsourcing middleboxes brings threats to the enterprise’s private information, including the traffic and rules of middleboxes, all of which are visible within the cloud. Existing solutions for secure middlebox outsourcing either incur significant performance overhead or do not support incremental updates. In this article, we present a secure and dynamic middlebox outsourcing framework, SICS, short for Secure In-Cloud Service. SICS encrypts each packet header and uses a label for in-cloud rule matching, which enables the cloud to perform its functionalities correctly with minimum header information leakage. Evaluation results show that SICS achieves higher throughput, faster construction and update speed, and lower resource overhead at the enterprise and in the cloud when compared with existing solutions.

Photocatalyst is the most widespread method in advanced oxidation technologies, but due to the photo-induced electron combine easily with hole and the wavelength of adsorption is limited which will affect some practical applications. Carbon quantum dots (CQDs) is non-toxic and harmless green materials, it has the ability to improve the photocatalytic effect which is attributed to its good electrical and optical properties. Their up-conversion effect, photosensitization and electrical conductivity are assistants which help promote the photocatalytic effect in environmental applications. The key mechanisms of CQDs to improve photocatalysis can be roughly divided into three categories: 1) Up-conversion effect converts the incident light into the emitted light with high energy to solve the problem which is the light absorption range. 2) CQDs act as a photosensitizer instead of valence band to provide electrons to the conduction band of semiconductor. 3) CQDs can be used as the internal or external electronic conductor in materials to alleviate the trend of electron and hole separation. However, CQDs and CQDs-based photocatalysts have different views to solve environmental problems, so it is necessary to integrate different views. Therefore, this review is mainly aimed at the recent researches about the preparation processes of CQD, CQDs-based photocatalysts, and their ability to remove environmental pollutants, with a special emphasis on the mechanism for depredating pollutants. Furthermore, this paper analyzes and discusses the prospects and challenges of CQDs in the environmental field.

Herein, we report that Co(II)-doped g-C

Supplying conductive materials (CMs) into anaerobic bioreactors is considered as a promising technology for antibiotic wastewater treatment. However, whether and how CMs influence antibiotic resistance genes (ARGs) spread remains poorly known. Here, we investigated the effects of three CMs, i.e., magnetite, activated carbon (AC), and zero valent iron (ZVI), on ARGs dissemination during treating sulfamethoxazole wastewater, by dissecting the shifts of physiological features and microbial community. With the addition of magnetite, AC, and ZVI, the SMX removal was improved from 49.05 to 71.56-92.27 %, while the absolute abundance of ARGs reducing by 26.48 %, 61.95 %, 48.45 %, respectively. The reduced mobile genetic elements and antibiotic resistant bacteria suggested the inhibition of horizontal and vertical transfer of ARGs. The physiological features, including oxidative stress response, quorum sensing, and secretion system may regulate horizontal transfer of ARGs. The addition of all CMs relieved oxidative stress compared with no CMs, but ZVI may cause additional free radicals that needs to be concerned. Further, ZVI and AC also interfered with cell communication and secretion system. This research deepens the insights about the underlying mechanisms of CMs in regulating ARGs, and is expected to propose practical ways for mitigating ARGs proliferation.

The fate of antibiotics in activated sludge has attracted increasing interests. However, the focus needs to shift from concerning removal efficiencies to understanding mechanisms and sludge responding to antibiotic toxicity. Herein, we operated two anaerobic sequencing batch reactors (ASBRs) for 200 days with sulfadiazine (SDZ) and sulfamethoxazole (SMX) added. The removal efficiency of SMX was higher than that of SDZ. SDZ was removed via adsorption (9.91-21.18%) and biodegradation (10.20-16.00%), while biodegradation (65.44-86.26%) was dominant for SMX removal. The mechanisms involved in adsorption and biodegradation were investigated, including adsorption strength, adsorption sites and the roles of enzymes. Protein-like substance (tryptophan) functioned vitally in adsorption by forming complexes with sulfonamides. P450 enzymes may catalyze sulfonamides degradation via hydroxylation and desulfurization. Activated sludge showed distinct responses to different sulfonamides, reflected in the changes of microbial communities and functions. These responses were related to sulfonamides removal, corresponding to the stronger adsorption capacity of activated sludge in ASBR-SDZ and degradation capacity in ASBR-SMX. Furthermore, the reasons for different removal efficiencies of sulfonamides were analyzed according to steric and electronic effects. These findings propose insights into antibiotic removal and broaden the knowledge for self-protection mechanisms of activated sludge under chronic toxicities of antibiotics.

Intent-Based Networking (IBN) has been increasingly deployed in production enterprise networks. Automated network configuration in IBN lets operators focus on intents- i.e., the end to end business objectives-rather than spelling out details of the configurations that implement these objectives. Automation brings its own concerns as the administrators cannot rely on traditional network troubleshooting tools. This situation is further exacerbated in the case of stateful Network Functions (NFs) whose packet processing behavior depends on previously observed traffic patterns. To ensure that the network configuration and state derived from network automation matches the administrator’s specified intent, we propose, Epinoia, a network intent checker for stateful networks. Epinoia relies on a unified model for NFs by leveraging the causal precedence relationships that exist between NF packet I/Os and states. Scalability of Epinoia is achieved by decomposing intents into sub-checking tasks and maintaining a causality graph between checked invariants. Epinoia checks for network-wide intent violations incrementally to reduce overhead in the event of network changes. Our evaluation results using real-world network topologies show that Epinoia can perform comprehensive checking within a few seconds per network with intent updates.

In this study, the biochar (BC)-induced Fe(III) reduction for persulfate (PS) activation system was used for the first time in sulfamethoxazole (SMX) degradation. The apparent rate constant of the BC/Fe(III)/PS system was 31.3 and 8.2 times that of BC/PS system and Fe(III)/PS system, respectively. The carbon-centered persistent free radicals contained in BC acted as electron donors. Electron transfer occurred between the BC surface and Fe(III) successfully. Fe(II) was thus generated and played a key role for the subsequent PS activation. Scavenger quenching experiments and electron spin resonance spectrometry confirmed the presence of sulfate ( SO 4 · - ) and hydroxyl radicals ( HO · ), which brought about the efficient SMX degradation in the BC/Fe(III)/PS system. Furthermore, the frontier molecular orbital (FMO) theory and dual descriptor (DD) method were employed in predicting radical attacking sites of SMX. According to the results of theoretical computations and the experimental detection, degradation pathways of SMX in the BC/Fe(III)/PS system were deduced accurately. This study gives new insight into the possible mediatory roles of biochar in PS activation by transition metal ions. The BC/Fe(III)/PS system is a promising process for groundwater and soil remediation.

Internet of Things has been widely applied in everyday life, ranging from transportation and healthcare to smart homes. As most IoT devices carry constrained resources and limited storage capacity, sensing data need to be transmitted to and stored at resource-rich platforms, such as a cloud. IoT applications need to retrieve sensing data from the cloud for analysis and decision-making purposes. Ensuring the authenticity and integrity of the sensing data is essential for the correctness and safety of IoT applications. We summarize the new challenges of the IoT data communication with authenticity and integrity and argue that existing solutions cannot be easily adopted to resource-constraint IoT devices. We present two solutions called dynamic tree chaining and geometric star chaining that provide efficient and secure communication for the Internet of Things. Extensive simulations and prototype emulation experiments driven by real IoT data show that the proposed system is more efficient than alternative solutions in terms of time and space.

In this study, sludge-derived biochar (SDBC) was prepared and applied in peroxydisulfate (PDS) activation for sulfamethoxazole (SMX) degradation. Compared to the slight adsorption (16.5%) by SDBC alone and low direct oxidation (10.1%) by PDS alone, the SMX degradation rate was drastically increased to 94.6% in the combined SDBC/PDS system, suggesting that SDBC can successfully and efficiently activate PDS. The observed rate constant of the combined SDBC/PDS system was 48.3 times those of both PDS alone and SDBC alone processes. Material characterization and comparative experiments showed nitrogen doping and iron loading into the carbon layer might be the important active sites of the graphene-like SDBC material in PDS activation for SMX degradation. More importantly, singlet oxygen (1O2), instead of traditional sulfate radicals or hydroxyl radicals, was the predominant reactive species of the SDBC/PDS system, which involved a new nonradical oxidation method for PDS activation by SDBC. The SMX degradation pathways by the nonradical 1O2 oxidation were first studied by combining density functional theory (DFT) calculations with experimental results. Different from the well-known pathways of SMX through the cleavage of the sulfanilamide bond by the attack of radicals, the 1O2 was likely to attack the aniline ring of SMX to initiate and accelerate the decomposition process. Finally, the energy cost analysis of the SDBC/PDS system further demonstrated the possible and economic application of the SDBC/PDS technique for SMX degradation. Thus, this study proposed a novel and economic method for PDS activation through a new nonradical oxidation pathway predominated by 1O2, which also promoted the safe and efficient transformation of antibiotics or other contaminants by PDS activation processes.

Antibiotics can exert selective pressures on sludge as well as affect the emergence and spread of antibiotic resistance genes (ARGs). However, the underlying mechanisms of ARGs transfers are still controversial and not fully understood in sludge system. In present study, two anaerobic sequence batch reactors (ASBR) were constructed to investigate the development of ARGs exposed to two sulfonamide antibiotics (SMs, sulfadiazine SDZ and sulfamethoxazole SMX) with increasing concentrations. The abundance of corresponding ARGs and total ARGs obviously increased with presence of SMs. Functional analyses indicated that oxidative stress response, signal transduction and type IV secretion systems were triggered by SMs, which would promote ARGs transfers. Network analysis revealed 18 genera were possible hosts of ARGs, and their abundances increased with SMs. Partial least-squares path modeling suggested functional modules directly influenced mobile genetic elements (MGEs) as well as the ARGs might be driven by both functional modules and bacteria community, while bacteria community composition played a more key role. Sludge with refractory antibiotics (SDZ) may stimulate the relevant functions and shift the microbial composition to a greater extent, causing more ARGs to emerge and spread. The mechanisms of ARGs transfers are revealed from the perspective of functional modules and bacterial community in sludge system for the first time, and it could provide beneficial directions, such as oxidative stress reduction, cellular communication control, bacterial composition directional regulation, for ARGs spread controlling in the future.

Carbon quantum dots (CQDs) doping semiconductors can boost solar-to-hydrogen conversion and the photodegradation in VIS-NIR light, therefore attract great attention, but the perspective of CQDs role is seldom explored. Here, a biomass-CQDs was assembled with BiOCl (CQDs/BiOCl), then served as the visible-photodegradation model for a mechanistic investigation. Furthermore, CQDs/BiOCl removed 90% bisphenol A (BPA) within 2 h under visible light. It was attributed to the C-localized state (CLS) produced by CQDs, which transfers forceless photo-electrons (e−) to generate holes (h+) in the CQDs/BiOCl valence band (VB) under visible light, the h+ mainly involved in the BPA degradation process. Then, the electrochemical experiments and theoretical calculations further proved that the efficiencies of charge separation (ηCS) and injection (ηCI) were proved by CQDs. Meanwhile, the possible BPA degradation pathways were accordingly proposed, and the ecotoxicity evaluation of the intermediates was also conducted by ECOSAR. The transformation pathways of BPA were divided into five orientations, and the toxicity of intermediates was decreased for Fish (LC50, ChV), Daphnid (LC50, ChV), Algae (EC50, ChV) except for P10 and P12. As the result, this study confirmed the feasibility of bio-CQDs/BiOCl preparation and it could be a photocatalyst to remove and detoxify BPA under visible light.

Polymeric carbon nitride (PCN) has become a star material either in photocatalysis or in persulfate (PS) activation. In this work, we synthesized bifunctional biochar (BC)-doped PCN through a facile one-pot thermal treatment process. The PCN/BC hybrid (CNBC) with an optimized proportion could not only activate PS directly, but also possessed improved optical properties. Amorphous BC domains generated from the carbonization of external corncob provided attachments for the in-situ growth of PCN and upgraded its catalytic ability including electron transport property, visible light (VIS) utilization, and oxidation power. Mechanism studies demonstrated that in the CNBC/PS system without VIS, a nonradical electron transfer route was responsible for the degradation of bisphenol A (BPA), while in the CNBC/PS/VIS system, radical/nonradical mixing mechanisms including mediated electron transfer, radical oxidation, and hole oxidation were unveiled. Degradation pathways of BPA were deduced including direct oxidation at the aromatic ring, β-scission of isopropyl, and ring cleavage. Most of the intermediates were less toxic than BPA as assessed by the ECOSAR software. The CNBC/PS/VIS system showed satisfactory resistance to environmental interferences except for HCO3-. This work provides a simple but effective strategy for the synthesis of PCN-based bifunctional catalysts and deepens mechanistic insights into hybrid advanced oxidation technologies.

The reaction between Co(II) and PMS is an appealing advanced oxidation process (AOP), where multiple reactive oxidizing species (ROS) including high-valent cobalt-oxo [Co(IV)], sulfate radical (SO4•-), and hydroxy radical (•OH) are intertwined together for degrading pollutants. However, the relative contribution of various ROS and the influences of nontarget matrix constituents, on the degradation process are still unclear and yet to be answered. In this study, we confirmed the generation Co(IV) as dominant intermediate oxidant at acid medium by using methyl phenyl sulfoxide (PMSO) as a probe compound. Using chemical scavenging methods, the role of SO4•- and •OH was also identified, and the major ROS were converted from Co(IV) to radical species with the increase of PMS/Co(II) molar ratio as well as pH value. In addition, we found that their contributions to the abatement of organic contaminants are highly dependent on both their available amount and substrate-specific reactivity. Generally, organic substrates with low ionization potential (IP) are prone to react with Co(IV). More interestingly, in contrast to radical-based oxidation, Co(IV) exhibited the great resistance to humic acid (HA) and background ions. This study might shed new light on the PMS activation by cobalt(II) for degradation of organic contaminants.

In this study, batch experiments were carried out to investigate the key factors on sulfamethoxazole (SMX) removal kinetics in a new AOPs based on the combination of zero valent iron (Fe 0 ) and bisulfite (S(IV)). With the increase of Fe 0 from 0.25 mM to 5 mM, the removal rate of SMX was linearly increased in the Fe 0 /S(IV)/O 2 system by accelerating the activation of S(IV) and Fe 0 corrosion to accelerate. In the first 10 min of reaction, the increasing concentration of S(IV) inhibited SMX removal after since the high S(IV) concentration quenched reactive oxidative species (ROS). Then SMX removal rate was accelerated with the increase of S(IV) concentration after S(IV) were consumed up. The optimal ratio of S(IV) concentrations to Fe 0 concentration for SMX removal in the Fe 0 /S(IV)/O 2 system was 1:1. With SMX concentrations increasing from 1 to 50 μM, SMX removal rate was inhibited for the limitation of ROS yields. Although the presence of SO 4 − and OH was confirmed by electron paramagnetic resonance (EPR) spectrum, OH was identified as the dominant ROS in the Fe 0 /S(IV)/O 2 system by chemical quenching experiments. Besides, strong inhibitive effects of 1,10-phenanthroline on SMX degradation kinetics by Fe 0 /S(IV)/O 2 proved that the generation of ROS was rely on the release of Fe(II) and Fe(III). The generation of SO 4 − was ascribed to the activation of S(IV) by Fe(II)/Fe(III) recycling and the activation of HSO 5 − by Fe(II). And OH was simultaneously transformed from SO 4 − and generated by Fe 0 /O 2 . Density functional theory (DFT) calculation was conducted to reveal special reactive sites on SMX for radicals attacking and predicted intermediates. Finally, four possible SMX degradation pathways were accordingly proposed in the Fe 0 /S(IV)/O 2 system based on experimental methods and DFT calculation.

In this study, ultrasound (US) technology was adopted for peroxymonosulfate (PMS) activation, and it increased the efficiency of sulfamethazine (SMT) antibiotic degradation. US can considerably activate PMS, increasing the SMT degradation rate by the US/PMS process up to 6.4 and 86 times that of PMS alone and US alone processes, respectively. The scavenger quenching experiments and electron paramagnetic resonance (EPR) spectrometry proved that US can activate PMS to generate sulfate radicals (SO 4 − ) and hydroxyl radicals ( OH), which contributed to efficient SMT degradation in the US/PMS system. Furthermore, density functional theory (DFT) calculations and dual descriptor were used to provide insights into SMT degradation. The calculation results offered good agreement with the experimental detection, which indicated that the central cleavages of SMT such as S–N, S–C, and N–C bonds or adducts on the rings would easily occur to degrade SMT in the US/PMS system. Based on these results, SMT degradation pathways were deduced, and the overall performance of the US/PMS process and its underlying mechanism for SMT degradation were proposed. This study offers theoretical and practical directions for removal of other antibiotics or pollutants using the US/PMS process.

The combination of Co(II) and peracetic acid (PAA) is a promising advanced oxidation process for the abatement of refractory organic contaminants, and acetylperoxy (CH3CO3•) and acetoxyl (CH3CO2•) radicals are generally recognized as the dominant and selective intermediate oxidants. However, the role of high-valent cobalt-oxo species [Co(IV)] have been overlooked. Herein, we confirmed that Co(II)/PAA reaction enables the generation of Co(IV) at acidic conditions based on multiple lines of evidences, including methyl phenyl sulfoxide (PMSO)-based probe experiments, 18O isotope-labeling technique, and in situ Raman spectroscopy. In-depth investigation reveals that the PAA oxidation mechanism is strongly pH dependent. The elevation of solution pH could induce major oxidants converting from Co(IV) to oxygen-centered radicals (i.e., CH3CO3• and CH3CO2•). The presence of H2O2 competitively consumes both Co(IV) and reactive radicals generated from Co(II)/PAA process, and thus, leading to an undesirably decline in catalytic performance. Additionally, as a highly reactive and selective oxidant, Co(IV) reacts readily with organic substances bearing electron-rich groups, and efficiently attenuating their biological toxicity. Our findings enrich the fundamental understanding of Co(II) and PAA reaction and will be useful for the application of Co(IV)-mediated processes.

A noncovalent functionalization approach was implemented using graphitic biochar (BC) as dopant to manipulate electronic properties of polymeric carbon nitride (PCN) while preserving its robust geometric skeleton. By fine-tuning the mass proportions of precursors during copolymerization, the carbonization of corncob was successfully confined in the PCN interlayers. An electron transport highway from PCN to BC was built owing to the π-electron delocalization. As a result, the non-covalent assembled PCN/BC composite rivaled popular nitrogen-doped carbon materials in activating peroxymonosulfate (PMS), and meanwhile exhibited superior durability. Singlet oxygen (1O2) was identified as the primary reactive oxygen species. Combining theoretical calculations and in-situ detections, a novel 1O2 evolution route with respect to the dissociation of PMS at the S/O site and the formation of superoxide radical was decoded. This work offers a new idea for the synthesis of durable PMS activators and enriches mechanistic understanding of PMS decomposition over metal-free catalysts.

N-doped biochars (NBCs) were prepared by pyrolyzing corncob biomass and urea in different proportion which manifested superior catalytic performance of peroxydisulfate (PDS) activation for sulfadiazine (SDZ) degradation. Through both dynamic fitting and density functional theory (DFT) calculations, the critical role of edge nitrogenation in biochar (BC) structure was revealed for the first time. The incorporation of edge nitrogen configurations (pyridinic N and pyrrolic N rather than graphitic N) generated reactive sites for the PDS activation. Additionally, a thorough investigation was conducted to explicate the PDS activation mechanism by NBC through chemical quenching experiments, electron spin resonance (ESR) detection, oxidant consumption monitoring and electrochemical analysis. Different from the well-reported singlet oxygen (1O2) dominated nonradical mechanism, an electron transfer pathway involving surface-bound reactive complexes was proved to play a major role in the NBC/PDS system. Benefit from the electron transfer mechanism, the NBC/PDS system not only has wide pH adaptation for real application, but also shows high resistance to the inorganic anions in aquatic environment. We believe this study will deepen the understanding of the carbon-driven persulfate activation mechanism and provide strong technical support for the BC-mediated persulfate activation in practical applications.

Sulfurized biochar derived from sewage sludge (SSB) was facilely synthesized and manifested upgraded performance in activation of peroxymonosulfate (PMS) and peroxydisulfate (PDS) for bisphenol A (BPA) elimination. The incorporated zigzag-edge sulfur effectively activated the sp2-hybridized graphene lattice, leading to the creation of more Lewis acid and basic sites in SSB. Singlet oxygen (1O2) generated from PMS oxidation at the Lewis acid sites was confirmed to be the dominated reactive species for BPA removal in the SSB/PMS system, whereas electron-transfer reactions comprising surface-confined complexes originated from the intimate contact between PDS and Lewis basic sites played the decisive role in the SSB/PDS system. Nineteen intermediates were identified in the two systems and degradation pathways of BPA were deduced accurately as well. This work not only provides a novel modification strategy for the cost-effective and environment friendly biochar-based catalysts but also deepen the insight into mechanisms of persulfate activation with carbonaceous materials.

Cobalt-mediated activation of peroxymonosulfate (PMS) has been extensively investigated for the degradation of emerging organic pollutants. In this study, PMS activation via cobalt-impregnated biochar towards atrazine (ATZ) degradation was systematically examined, and the underlying reaction mechanism was explicated. It was found that persistent free radicals (PFRs) contained in biochar play a pivotal role in PMS activation process. The PFRs enabled an efficient transfer electron to both cobalt atom and O2, facilitating the recycle of Co(III)/Co(II), and thereby leaded to an excellent catalytic performance. In contrast to oxic condition, the elimination of dissolved oxygen significantly retarded the ATZ degradation efficiency from 0.76 to 0.36 min-1. Radical scavenging experiments and electron paramagnetic resonance (EPR) analysis confirmed that the ATZ degradation was primarily due to SO4·- and, to a lesser extent, ·OH. In addition, dual descriptor (DD) method was carried out to reveal reactive sites on ATZ for radicals attacking and predicted derivatives. Meanwhile, the possible ATZ degradation pathways were accordingly proposed, and the ecotoxicity evaluation of the oxidation intermediates was also conducted by ECOSAR. Consequently, the cobalt-impregnated biochar could be an efficient and environmentally friendly catalyst to activate PMS for abatement and detoxication of ATZ.

In this study, B-doped graphitic porous biochar (B-KBC) was prepared and used to activate peroxydisulfate (PDS) for the removal of sulfamethoxazole (SMX). Experimental and theoretical results revealed that the introduction of boron species not only act as Lewis acid sites enhanced the surface affinity towards PDS but also modulate the electronic structure of carbon matrix evidently increase the electron transfer rate, and thus result in an excellent catalytic capacity. More importantly, owing to the high stability boron sites, B-KBC endows a superior long-term durability in comparison with popular N-doped carbon catalysts. Given the uncertainty of quenching experiments, the electron paramagnetic resonance, materials balance calculation combined with electrochemical measures confirmed the biochar mediated electron transfer mechanism, rather than 1O2, was primarily responsible for the nonradical route. This study is expected to pave a new avenue to develop cost-effective and eco-friendliness metal-free carbon catalyst with adequate activity and reuse stability.

Sulfidation treatment has been considered as an effective method to improve the activity of zero valent iron (ZVI) for reductive removal of contaminants. However, the role and mechanism of sulfide-modified zero valent iron (S-ZVI) in advanced oxidation reaction were worth further exploration. In this study, influences of different reaction conditions, including initial pH, iron dosage, persulfate (PDS) dosage and inorganic ions on sulfadiazine (SDZ) removal by mechanical ball-milling sulfidated microscale zero valent iron (S-ZVIbm)/PDS process and mechanical ball-milling microscale zero valent iron (ZVIbm)/PDS were comparatively investigated. By contrastive analyses, S-ZVIbm exhibited more excellent performance on activation of PDS. Meanwhile, SO42−, Cl−, and NO3− showed different effects on SDZ degradation by ZVIbm/PDS and S-ZVIbm/PDS. The potential mechanisms that S-ZVIbm exceeding ZVIbm in activating PDS were clarified from two aspects, which were better iron dissolution and iron circulation caused by iron sulfides generated during sulfidation treatment. Besides, chemical quenching experiments and electron paramagnetic resonance (EPR) studies identified that both SO 4 · - and OH were generated in ZVIbm/PDS and S-ZVIbm/PDS, and SO 4 · - was the dominant one. Two different degradation pathways of SDZ in the S-ZVIbm/PDS process were proposed based on the experimental intermediates identification and density functional theory (DFT) calculation. According to the results obtained in this study, the S-ZVIbm/PDS process was recommended as an effective method to degrade contaminants.

Alternative chemicals to diverse fossil-fuel-based products is urgently needed to mitigate the adverse impacts of fossil fuel depletion on human development. To this end, researchers have focused on the production of biochemical from readily available and affordable waste biomass. This is consistent with current guidelines for sustainable development and provides great advantages related to economy and environment. The search for suitable biochemical products is in progress worldwide. Therefore, this review recommends a biochemical (i.e., medium chain carboxylic acids (MCCAs)) utilizing an emerging biotechnological production platform called the chain elongation (CE) process. This work covers comprehensive introduction of the CE mechanism, functional microbes, available feedstock types and corresponding utilization strategies, major methods to enhance the performance of MCCAs production, and the challenges that need to be addressed for practical application. This work is expected to provide a thorough understanding of the CE technology, to guide and inspire researchers to solve existing problems in depth, and motivate large-scale MCCAs production.

Outsourcing middleboxes brings threats to the enterprise's private information including the trafflc and rules of middleboxes. We present a secure and dynamic middlebox outsourcing framework SICS, short for Secure In-Cloud Service. SICS encrypts each packet header and uses a label for in-cloud rule matching, which enables the cloud to perform its functionalities correctly with minimum header information leakage.

In this study, batch experiments were carried out to investigate the key factors on sulfamethoxazole (SMX) removal kinetics in a new AOPs based on the combination of zero valent iron (Fe

Computer networks are becoming increasingly complex today and thus prone to various network faults. Traditional testing tools (e.g., ping, traceroute) that often involve substantial manual effort to uncover faults are inefficient. This paper focuses on fault detection of the network data plane using test packets. Existing solutions of test packet generation either take very long time (e.g., more than one hour) to complete or generate too many test packets that may hurt regular traffic. In this paper, we present Pronto, an automated test packet generation tool that generates test packets to exercise data plane rules in the entire network in a short time (e.g., several seconds) and can quickly react to rule changes due to network dynamics. In addition, Pronto minimizes the number of test packets by allowing a packet to test multiple rules at different switches. The performance evaluation using two real network data plane rule sets shows that Pronto is faster than a recently developed tool by more than two orders of magnitude. Pronto can update the probes for rule changes using less than 1ms while existing methods have no such update function.

Internet of Things has been widely applied in everyday life, ranging from transportation, healthcare, to smart homes. As most IoT devices carry constrained resources and limited storage capacity, sensing data need to be transmitted to and stored at resource-rich platforms, such as a cloud. IoT applications retrieve sensing data from the cloud for analysis and decision-making purposes. Ensuring the authenticity and integrity of the sensing data is essential for the correctness and safety of IoT applications. We summarize the new challenges of the IoT data communication framework with authenticity and integrity and argue that existing solutions cannot be easily adopted. We present two solutions, called Dynamic Tree Chaining (DTC) and Geometric Star Chaining (GSC) that provide authenticity, integrity, sampling uniformity, system efficiency, and application flexibility to IoT data communication. Extensive simulations and prototype emulation experiments driven by real IoT data show that the proposed system is more efficient than alternative solutions in terms of time and space.

Upgrading lactate/carbohydrate-rich waste biomass into medium-chain carboxylic acids (MCCAs) by chain elongation (CE) technology exhibits economic and environmental benefits. However, the largely dispersive lactate-carbon-flow decreases MCCAs yield. This work discovered appropriate H2 supply could significantly reduce lactate-carbon-flow loss and improve MCCAs production (∼1.65 times) when the system is not operated according to well-defined operating conditions, and revealed corresponding mechanism. Hydrogen (H2) supply largely enhanced electron efficiency and electron transfer capacity, and H2 could reduce propionate (from competing acrylate pathway, which should be prevented, but when not possible, the carbon recovery from propionate is possible) to propanol, which was used as electron donor to elongate acetate and propionate. Moreover, H2 could react with CO2 (from CE process) to sequentially generate acetate and ethanol, which further contributed to caproate/caprylate generation. Comparing with non-H2-supplemented test, the lactate-carbon-flow used for MCCAs production was enhanced by ∼28.4% after H2 supply, and Clostridium spp. were the key discriminative microorganisms.

Identifying the network-wide forwarding behaviors of a packet is essential for many network management applications, including rule verification, policy enforcement, attack detection, traffic engineering, and fault localization. Current tools that can perform packet behavior identification either incur large time and memory costs or do not support real-time updates. In this paper, we present AP Classifier, a control plane tool for packet behavior identification. AP Classifier is developed based on the concept of atomic predicates, which can be used to characterize the forwarding behaviors of packets. Experiments using the data plane network state of two real networks show that the processing speed of AP Classifier is faster than existing tools by at least an order of magnitude. Furthermore, AP Classifier uses very small memory and is able to support real-time updates.

We consider the problem of distributing "live" streaming media content to a potentially large and highly dynamic population of hosts. Peer-to-peer content distribution is attractive in this setting because the bandwidth available to serve content scales with demand. A key challenge, however, is making content distribution robust to peer transience. Our approach to providing robustness is to introduce redundance; both in network paths and in data. We use multiple, diverse distribution trees to provide redundancy in network paths and multiple description coding (MDC) to provide redundancy in data. We present a simple tree management algorithm that provides the necessary path diversity and describe an adaptation framework for MDC based on scalable receiver feedback. We evaluate these using MDC applied to real video data coupled with real usage traces from a major news site that experienced a large flash crowd for live streaming content. Our results show very significant benefits in using multiple distribution trees and MDC, with a 22 dB improvement in PSNR in some cases.