•Fungal enzyme could degrade TrOC that are resistant to bacterial degradation.•Some TrOC well removed by bacteria were poorly removed by fungal enzyme.•Bacterial complemented well the degradation of ...TrOC by fungal MBR.•Biodegradation was a major TrOC removal mechanism by fungi-bacteria (F-B) MBR.•Redox-mediator dosing improved removal of resistant TrOC diclofenac by F-B MBR.
The degradation of 30 trace organic contaminants (TrOC) by a white-rot fungus-augmented membrane bioreactor (MBR) was investigated. The results show that white-rot fungal enzyme (laccase), coupled with a redox mediator (1-hydroxy benzotriazole, HBT), could degrade TrOC that are resistant to bacterial degradation (e.g. diclofenac, triclosan, naproxen and atrazine) but achieved low removal of compounds (e.g. ibuprofen, gemfibrozil and amitriptyline) that are well removed by conventional activated sludge treatment. Overall, the fungus-augmented MBR showed better TrOC removal compared to a system containing conventional activated sludge. The major role of biodegradation in removal by the MBR was noted. Continuous mediator dosing to MBR may potentially enhance its performance, although not as effectively as for mediator-enhanced batch laccase systems. A ToxScreen3 assay revealed no significant increase in the toxicity of the effluent during MBR treatment of the synthetic wastewater comprising TrOC, confirming that no toxic by-products were produced.
Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are contaminants of great concern due to their wide-spread occurrence and persistence in the environments (i.e., in water, soil and sediment) and ...potential toxicology even at very low concentration. The main focus of this review is on the PFASs in soil and sediments. More specifically, this review systematically examines the occurrence and toxicological effects with associated risks, fate (i.e., PFASs adsorption by soil and sediment, transportation and transformation, and bioaccumulation), and remediation practices of PFASs in soil and sediment. Various models and equations such as fugacity-based multimedia fate and hydrodynamic models are used to study the fate, transport, and transformation of PFASs. Among different remediation practices, sorption is the dominant process for the removal of PFASs from soil and sediments. Results also indicate that PFASs adsorption onto activated carbon decrease with the increase of carbon chain length in the PFASs. The longer-chain PFASs have larger partition coefficient values than shorter-chained PFASs. Sorption of PFASs to soil and sediments are mainly governed by different electrostatic interactions, hydrogen bonds formation, hydrophobic interactions, organic content in soil and sediments, and ligand exchange. Other technology such as thermal treatment might be potential in the removal of PAFSs, but need further study to elucidate a conclusion. Finally, the associated challenges and future outlook have been included.
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•Occurrence and toxicity of PFASs were explored in soil and sediment.•The organic content of soil and sediment impacts PFASs sorption.•Removal processes and mechanism of PFASs from soil and sediment were reviewed.•Sorption is the dominant process for the removal of PFASs.•Thermal destruction is an emerging method for PFASs removal from soil and sediment.
Multi-User Regularized Zero-Forcing Beamforming Nguyen, Long D.; Hoang Duong Tuan; Duong, Trung Q. ...
IEEE transactions on signal processing,
06/2019, Letnik:
67, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Regularized zero-forcing beamforming (RZFB) is an interesting class of linear signal processing problems, which is very attractive for use in large-scale communication networks due its simple ...visualization as a straightforward extension of the well-accepted zero-forcing beamforming (ZFB). However, unlike ZFB, which is multi-user interference free, RZFB must manage multi-user interference to achieve its high throughput performance. Most existing works focus on the performance analysis of particular RZBF schemes such as the equip-power allocated RZBF under a fixed regularization parameter. This paper is the first work to consider the joint design of power allocation and regularization parameter for RZFB to maximize the worst users' throughput or the quality-of-service awarded energy efficiency under a fixed transmit power constraint. Such designs pose very computationally challenging optimization problems, for which the paper proposes two-stage optimization algorithms of low computational complexity. Their computational and performance efficiencies are substantiated through numerical examples.
Underwater Wireless Sensor Networks (UWSNs) are an enabling technology for many applications in commercial, military, and scientific domains. In some emergency response applications of UWSN, data ...dissemination is more important, therefore these applications are handled differently as compared to energy-focused approaches, which is only possible when propagation delay is minimized and packet delivery at surface sinks is assured. Packet delivery underwater is a serious concern because of harsh underwater environments and the dense deployment of nodes, which causes collisions and packet loss. Resultantly, re-transmission causes energy loss and increases end-to-end delay ( D E 2 E ). In this work, we devise a framework for the joint optimization of sink mobility, hold and forward mechanisms, adoptive depth threshold ( d t h ) and data aggregation with pattern matching for reducing nodal propagation delay, maximizing throughput, improving network lifetime, and minimizing energy consumption. To evaluate our technique, we simulate the three-dimensional (3-D) underwater network environment with mobile sink and dense deployments of sensor nodes with varying communication radii. We carry out scalability analysis of the proposed framework in terms of network lifetime, throughput, and packet drop. We also compare our framework to existing techniques, i.e., Mobicast and iAMCTD protocols. We note that adapting varying d t h based on node density in a range of network deployment scenarios results in a reduced number of re-transmissions, good energy conservation, and enhanced throughput. Furthermore, results from extensive simulations show that our proposed framework achieves better performance over existing approaches for real-time delay-intolerant applications.
Project complexity is a contributing factor to project performance. Understanding how project complexity interacts with management actions and project performance is imperative. This study fills this ...knowledge gap by empirically exploring the relationship between construction project complexity and project performance and their interaction with resource allocation. Empirical data were collected from 79 transportation projects. Due to its capability to build several regression models by adding independent variables to previous models, moderated hierarchical regression analyses were conducted to identify the underlying effect of resource allocation on the project complexity and performance relationship. The results show that: (i) project complexity was significantly correlated with schedule growth (positive correlation) but not significantly correlated with cost growth; (ii) resource allocation was significantly correlated with schedule growth (negative correlation) but not with cost growth; and (iii) resource allocation had a buffering effect where increasing resource allocation significantly decreases the effect of project complexity on schedule growth. The findings from this study contribute to the extant literature on construction project complexity by empirically showing that the impact of project complexity on schedule performance interacts with the level of resource allocation. This understanding of the role of resource allocation may help construction managers and engineers to better administer and manage their complex transportation projects. The findings also imply that organizations should appropriately evaluate project complexity to allocate necessary resources to achieve project success.
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•Phthalates have been globally detected in the environment matrices.•Phthalates can cause human health risks via exposure pathways.•Aerobic biodegradation of phthalates is higher ...efficiency than anaerobic.•Heterotrophic and ammonia-oxidizing bacteria plays a major role in biodegradation.•Membrane bioreactor is robust to remove phthalates with high efficiency.
Phthalates are well-known emerging contaminants that harm human health and the environment. Therefore, this review aims to discuss about the occurrence, fate, and phthalates concentration in the various environmental matrices (e.g., aquatic, sediment, soil, and sewage sludge). Hence, it is necessary to treat sources containing phthalates before discharging them to aqueous environment. Various advanced wastewater treatments including adsorption process (e.g., biochar, activated carbon), advanced oxidation processes (e.g., photo-fenton, ozonation, photocatalysis), and biological treatment (membrane bioreactor) have been successfully to address this issue with high removal efficiencies (70–95%). Also, the degradation mechanism was discussed to provide a comprehensive understanding of the phthalate removal for the reader. Additionally, key factors that influenced the phthalates removal efficiency of these technologies were identified and summarized with a view towards pilot-scale and industrial applications.
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•Factors governing flocculation efficiency at different growth phases were unravelled.•Flocculation efficiency was dependent on the growth phase of C. vulgaris culture.•Greater ...reduction in cell surface charge resulted in better flocculation efficiency.•Phosphorous residue did not affect microalgae flocculation.•Growth-phase dependency of algae flocculation was governed by cell EPS content.
This study aims to elucidate the mechanisms governing the harvesting efficiency of Chlorella vulgaris by flocculation using a cationic polymer. Flocculation efficiency increased as microalgae culture matured (i.e. 35–45, 75, and > 97% efficiency at early, late exponential, and stationary phase, respectively. Unlike the negative impact of phosphate on flocculation in traditional wastewater treatment; here, phosphorous residue did not influence the flocculation efficiency of C. vulgaris. The observed dependency of flocculation efficiency on growth phase was driven by changes in microalgal cell properties. Microalgal extracellular polymeric substances (EPS) in both bound and free forms at stationary phase were two and three times higher than those at late and early exponential phase, respectively. Microalgae cells also became more negatively charged as they matured. Negatively charged and high EPS content together with the addition of high molecular weight and positively charged polymer could facilitate effective flocculation via charge neutralisation and bridging.
Previous studies have confirmed significant removal of various trace organic contaminants (TrOCs) by white-rot fungal cultures under sterile batch test conditions. However, little is known about TrOC ...removal in continuous flow fungal reactors in a non-sterile environment. This study reports the removal of two TrOCs, namely, bisphenol A and diclofenac, by a fungal membrane bioreactor (MBR). Sterile batch tests with “active” (biosorption and biodegradation) and “chemically inactivated” (biosorption only) Trametes versicolor (ATCC 7731) confirmed biodegradation as the main mechanism for the removal of both compounds. An MBR inoculated with T. versicolor was operated in non-sterile conditions for a period of three months during which diclofenac and bisphenol A were continuously added to the synthetic wastewater. Relatively stable removal of bisphenol A (80–90%) and diclofenac (∼55%) was achieved by applying a hydraulic retention time of two days, at the bisphenol A and diclofenac loadings of 475 ± 25 and 345 ± 112 μg/L.d, respectively.
•Pure fungal culture could completely remove bisphenol A (BPA) and diclofenac (DCF).•Reduced DCF removal was observed during non-sterile operation of the fungal MBR.•Fungal MBR performance was dependent on BPA/DCF loading.•At BPA/DCF loading <500 μg/L.d, DCF and BPA removal was 55% and 80–90%.•Biodegradation was a major mechanism of BPA and DCF removal by the fungal MBR.
Numerous ports worldwide are adopting automation to boost productivity and modernize their operations. At this point, smart ports become a more important paradigm for handling increasing cargo ...volumes and increasing operational efficiency. In fact, as ports become more congested and cargo volumes increase, the need for accurate navigation through seaports is more pronounced to avoid collisions and the resulting consequences. To this end, digital twin (DT) technology in the fifth-generation (5G) networks and drone-assisted data collection can be combined to provide precise ship maneuvering. In this paper, we propose a DT model using drone-assisted data collection architecture, called TwinPort, to offer a comprehensive port management system for smart seaports. We also present a recommendation engine to ensure accurate ship navigation within a smart port during the docking process. The experimental results reveal that our solution improves the trajectory performance by approaching the desired shortest path. Moreover, our solution supports significantly reducing financial costs and protecting the environment by reducing fuel consumption.
Mg/Al layered double hydroxides-mordenite nanocomposite (LDH@mordenite) was prepared via the in-situ method to enhance the Cr(VI) and Pb(II) removal efficiency. The results showed that the Cr(VI) and ...Pb(II) removal efficiency was enhanced by the formation of core-shell structure (mordenite core-LDH shell). The synthesized material with an LDH content of 30% had the highest removal efficiency for both metals at the pH of 5.0. The pseudo-second-order model was the best model for describing the adsorption kinetics of Cr(VI) and Pb(II) on LDH@mordenite. The calculation from the intra-particle diffusion model suggested that the adsorption processes included several steps. Fitting experimental data to the Langmuir, Freundlich, and Temkin models revealed that the Langmuir model was the best model for predicting the isotherms of the adsorption processes. The calculated maximum adsorption capacity at 25 ℃ was 54.80 mg/g for Cr(VI) and 67.91 mg/g for Pb(II). Based on the thermodynamic study, the Cr(VI) and Pb(II) adsorption on LDH@mordenite was endothermic and spontaneous. The adsorption mechanisms were studied using the statistical physics model and the calculated parameters indicated that Cr(VI) and Pb(II) ions could interact via one and two adsorption sites of the adsorbent.
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