The pharmaceuticals are emergent contaminants, which can create potential threats for human health and the environment. All the pharmaceutical contaminants are becoming enormous in the environment as ...conventional wastewater treatment cannot be effectively implemented due to toxic and intractable action of pharmaceuticals. For this reason, the existence of pharmaceutical contaminants has brought great awareness, causing significant concern on their transformation, occurrence, risk, and fate in the environments. Electrocoagulation (EC) treatment process is effectively applied for the removal of contaminants, radionuclides, pesticides, and also harmful microorganisms. During the EC process, an electric current is employed directly, and both electrodes are dissoluted partially in the reactor under the special conditions. This electrode dissolution produces the increased concentration of cation, which is finally precipitated as hydroxides and oxides. Different anode materials usage like aluminum, stainless steel, iron, etc. are found more effective in EC operation for efficient removal of pharmaceutical contaminants. Due to the simple procedure and less costly material, EC method is extensively recognized for pharmaceutical wastewater treatment over further conventional treatment methods. The EC process has more usefulness to destabilize the pharmaceutical contaminants with the neutralization of charge and after that coagulating those contaminants to produce flocs. Thus, the review places particular emphasis on the application of EC process to remove pharmaceutical contaminants. First, the operational parameters influencing EC efficiency with the electroanalysis techniques are described. Second, in this review emerging challenges, current developments and techno-economic concerns of EC are highlighted. Finally, future recommendations and prospective on EC are envisioned.
Conceptual flow diagram for pharmaceutical wastewater treatment by electrocoagulation. Display omitted
•Pharmaceuticals contaminants in the aquatic environment cause eco-toxicity.•The conventional process is not so useful in removing pharmaceutical contaminants.•The review offers deep insight of the EC in removing the pharmaceutical contaminant.•EC process is quick coagulation by the assistance of electricity application.•EC endure lack of scale-up systems and the developments techniques are reviewed.
Over the past few decades, removal and recovery of Lanthanum (La) have received great attention due to its significance in different industrial processes. In this review, the application of various ...adsorbents viz. biosorbents, commercial and hybrid materials, nanoparticles, nanocomposites etc. have been summarized in terms of the removal and recovery of La. The influence of various operating parameters including pH, dosage, contact time, temperature, coexisting ions, adsorption kinetics, isotherm and thermodynamics were investigated. Statistical analysis of the obtained data revealed that 60% and 70% of the authors reported an optimum pH of 4–6 and a dose of 1–2 g/L, respectively. It can be concluded on the basis of an extensive literature survey that the adsorbent materials (especially hybrids nanocomposites) containing carboxyl, hydroxyl and amine groups offered efficient La removal over a wide range of pH with higher adsorption capacity as compared to other adsorbents (e.g., biosorbents and magnetic adsorbents). Also, in most cases, equilibrium and kinetics were followed by Langmuir and pseudo second-order model and adsorption was endothermic in nature. To evaluate the adsorption efficiency of several adsorbents towards La, desorption and regeneration of adsorbents should be given due consideration. The main objective of the review is to provide an insight into the important factors that may affect the recovery of La using various adsorbents.
•Highlights of process parameters using conventional batch assays for La.•Statistical analysis of process parameters for La adsorption by various adsorbents.•Knowledge of adsorption isotherm, kinetics and thermodynamics and desorption for La.•Mechanism for hydroxyl, carboxyl, amine and phosphoryl groups was proposed.
Display omitted
•Critical operational parameters influencing the SNAD process are analyzed.•Performance of different reactor configurations for SNAD application is evaluated.•Research gaps for full ...scale applications of SNAD is discussed.
Nitrogen removal is an important aspect of wastewater treatment. Conventional biological nitrogen removal process is widely adopted for its reliable and effective nitrogen removal. However, its high operational and capital costs have led to the development of more cost-effective solutions. The discovery of Anaerobic ammonium oxidation (ANAMMOX) bacteria and its integration with shortcut nitrogen removal processes has proved to be a sustainable solution. However, the requirement of carbon-free feed and discharge of high nitrate concentration in the effluent limit their practical applications. To overcome these challenges, an innovative nitrogen removal process, the simultaneous partial nitrification, anammox and denitrification (SNAD) process, has been studied. SNAD involves a synergistic relationship among Ammonia oxidizing bacteria (AOB), ANAMMOX and denitrifers for high nitrogen removal efficiency. This study provides a focused review of the recent developments in SNAD process, specifically covering the critical process parameters for efficient operation and different reactor configurations. A detailed assessment of the process parameters such as carbon/nitrogen ratio, substrate type, free ammonia, free nitrous acid and hydraulic retention time is provided to identify the factors affecting the SNAD efficiency and required control measures. A comparison of different suspended and attached growth reactor configurations is also provided to understand the process reliability and potential for full-scale operation. This review will provide guidance for future engineering applications for high efficiency and cost-effective nitrogen removal via SNAD process.
Electrochemical degradation of hexazinone in aqueous solution using Bi-doped PbO2 electrodes as anodes was investigated. The main influencing parameters on the electrocatalytic degradation of ...hexazinone were analyzed as function of initial hexazinone concentration, current density, initial pH value and Na2SO4 concentration. The experiment results showed that the electrochemical oxidization reaction of hexazinone fitted pseudo-first-order kinetics model. 99.9% of hexazinone can be decontaminated using Bi-doped PbO2 electrode as anode for 120 min. Comparing with pure PbO2 electrode, the Bi-doped PbO2 electrodes possess higher hexazinone and COD removal ratio, higher ICE and lower energy consumption in the electrocatalytic degradation process. The results revealed that electrochemical oxidation using Bi-doped PbO2 anodes was an efficient method for the elimination of hexazinone in aqueous solution. The electrocatalytic oxidization mechanism of hexazinone with Bi-doped PbO2 anode was discussed, then the possible degradation pathway of hexazinone with two parallel sub-routes was elucidated according to 15 intermediates identified using HPLC-MS.
•Bi-doped PbO2 electrode was adopted to eliminate hexazinone in water.•Operating parameters of hexazinone degradation were optimized.•99.94% of hexazinone was electrochemically decontaminated by BiPbO2 electrode.•Bi-doped PbO2 electrode exhibits high hexazinone degradation capability.•The degradation intermediates of hexazinone were identified and pathway was proposed.
Display omitted
•Science history and progress in the application of AI in MBRs are identified.•The advances in AI techniques for MBRs are reviewed and critically discussed.•Artificial neural network ...is the most implemented AI techniques in MBR.•Future outlook of the implementation of AI in MBRs are discussed.•Recommendation for future studies in this field are presented and discussed.
Efforts are currently in progress to commercialize membrane bioreactor (MBR) technologies already developed at laboratory and pilot scale. To attain this goal, the efficiency of MBRs needs to be high, and they should be sustainable, reliable and cost-effective. Adoption of artificial intelligence (AI) is anticipated to have a positive impact on these criteria. This paper covers the AI-based models used in the treatment of wastewater from various sources, and discusses the advantages and disadvantages of each model. The existing gaps to push for the commercialization of MBR technologies are discussed to provide state-of-the-art insights for future research. The conclusions and discussions presented in this review show that AI models are useful to predict the performance of MBR technologies to recover clean water from polluted sources. However, further efforts are still needed to reach an excellent match between the predictions made by the AI-based techniques and the experimental results to deal with high strength and highly polluted effluents. This can be achieved through modification and/or integration of the existing AI-based methods. Also, the development of appropriate variables to optimize the performance of MBRs, and improving their efficiency to deal with recalcitrant pollutants such as contaminants of emerging concern(CECs) are among the priorities to promote the application of MBR technologies in real-scale applications.
•A mathematic algorithm to analyze exergy balance of dual fuel engine was built.•Dual fuel engine has low heat transfer and exhaust exergy losses at high load.•The quantity of exergy loss items are ...great affected by the intake air temperature.•Higher temperature parameters reduce exergy loss in diesel methanol dual fuel engine.
In order to reveal the mechanism of high thermal efficiency of diesel methanol dual fuel (DMDF) engine, the exergy loss of DMDF engine under different operating parameters is investigated by using experimental and calculative methods based on the second law of thermodynamics. It has been found that DMDF has lower heat transfer exergy loss under all engine loads due to the high latent heat of vaporization of methanol which reduces the temperature in-cylinder. The exhaust exergy loss of DMDF under high load is relatively low compared with that of pure diesel fuel, while it is opposite to that under medium-low load. This is due to the influence of different temperatures on the incomplete combustion of methanol, which also indicates the main cause for the high thermal efficiency of DMDF under high load. Then studies on exergy analysis of DMDF under different temperatures were carried out. The studies covers the effect of intake air temperature on exergy efficiency, the heat transfer exergy loss and the exhaust physical exergy loss increase with rising intake air temperature as well. The results shows that the exhaust chemical exergy loss decreases significantly with the increase of intake air temperature and higher intake air temperature helps to improve exergy efficiency. Additionally, it is concluded that higher methanol temperature and cooling water temperature can improve exergy efficiency by decreasing exhaust exergy loss and combustion irreversible exergy loss. Finally, some feasible measures are proposed to further improve DMDF engine’s performance.
Municipal solid waste (MSW) management is becoming a serious issue in all over the world. Anaerobic digestion (AD) is one of the technologies to convert that waste into useful form of energy. But ...megacities like Singapore having limited resources, cannot fulfill the cow dung or other animal manure requirements in AD. Therefore there is a need to study critically the operating parameters and also the pretreatment technologies available for treating the substrate so that one can get the maximum output with limited input. To fulfill the need, the present paper deals with the review of various operating parameters and their effects on AD. This paper also reviews different pretreatment methods including mechanical, thermal, chemical and biological methods to improve the effectiveness of AD of MSW.
•Review of engineering aspects related to intensification using ultrasound.•Analysis of governing mechanisms and kinetic models.•Guidelines about optimum parameters for maximizing the ...intensification.•Analysis of various reactor configurations for large scale operation.•Application of ultrasound results in significant intensification.
Cavitation generated using ultrasound can enhance the rates of several chemical reactions giving better selectivity based on the physical and chemical effects. The present review focuses on overview of the different reactions that can be intensified using ultrasound followed by the discussion on the chemical kinetics for ultrasound assisted reactions, engineering aspects related to reactor designs and effect of operating parameters on the degree of intensification obtained for chemical synthesis. The cavitational effects in terms of magnitudes of collapse temperatures and collapse pressure, number of free radicals generated and extent of turbulence are strongly dependent on the operating parameters such as ultrasonic power, frequency, duty cycle, temperature as well as physicochemical parameters of liquid medium which controls the inception of cavitation. Guidelines have been presented for the optimum selection based on the critical analysis of the existing literature so that maximum process intensification benefits can be obtained. Different reactor designs have also been analyzed with guidelines for efficient scale up of the sonochemical reactor, which would be dependent on the type of reaction, controlling mechanism of reaction, catalyst and activation energy requirements. Overall, it has been established that sonochemistry offers considerable potential for green and sustainable processing and efficient scale up procedures are required so as to harness the effects at actual commercial level.
Magnetron sputtering deposition has become the most widely used technique for deposition of both metallic and compound thin films and is utilized in numerous industrial applications. There has been a ...continuous development of the magnetron sputtering technology to improve target utilization, increase ionization of the sputtered species, increase deposition rates, and to minimize electrical instabilities such as arcs, as well as to reduce operating cost. The development from the direct current (dc) diode sputter tool to the magnetron sputtering discharge is discussed as well as the various magnetron sputtering discharge configurations. The magnetron sputtering discharge is either operated as a dc or radio frequency discharge, or it is driven by some other periodic waveforms depending on the application. This includes reactive magnetron sputtering which exhibits hysteresis and is often operated with an asymmetric bipolar mid-frequency pulsed waveform. Due to target poisoning the reactive sputter process is inherently unstable and exhibits a strongly non-linear response to variations in operating parameters. Ionized physical vapor deposition was initially achieved by adding a secondary discharge between the cathode target and the substrate and later by applying high power pulses to the cathode target. An overview is given of the operating parameters, the discharge properties and the plasma parameters including particle densities, discharge current composition, electron and ion energy distributions, deposition rate, and ionized flux fraction. The discharge maintenance is discussed including the electron heating processes, the creation and role of secondary electrons and Ohmic heating, and the sputter processes. Furthermore, the role and appearance of instabilities in the discharge operation is discussed.
Display omitted
•High phenolic compound removal efficiency is achieved in DBD.•All possible reactive species in DBD were explored.•Influence of the organic structure in pollutants removal in DBD were ...founded.•EPR was applied to detect Hydroxyl radical in the system.•A plasma-catalyst combination technique is proposed.
The degradation of a series of phenolic compounds in a novel dielectric barrier discharge (DBD) plasma reactor was studied in this paper. The effect of various parameters, such as applied voltage, water flowrate, initial concentrations of organics, solution conductivity and pH, was investigated to achieve a high removal efficiency for phenolic compounds. The complete degradation of p-CH3 could be achieved within 32 min, and the highest energy yield was about 3.5 g/kWh. Electron paramagnetic resonance analysis and radical quenching experiment indicated that OH played an important role in phenols degradation, along with ozone molecules. O2− and 1O2 also possibly contributed to phenols degradation. Substituted phenols were more easily degraded, especially nitrophenol with strong electron withdrawing groups, originating from OH and O2− attack. The intermediates of different phenolic compound generated in the degradation process were identified by Mass spectroscopy (MS) and the corresponding mechanism were proposed to strengthen the understanding of mechanism. A DBD plasma and activated carbon combined technique is further proposed to promote the conversion of oxygen into ROS (reactive oxygen species) and enhance the mineralization rate of substituted phenols.
PDF
