Enhancing oxygen reduction reaction performance through eco-friendly chitosan gel-assisted molten salt strategy: Small NiCo alloy nanoparticles decorated with high-loading single Fe-NX.

We developed an effective and eco-friendly strategy using chitosan gel-molten salt to achieve high loading (2.23 At. %) of single Fe-NX as assistive active sites. These sites were combined with small NiCo alloy NPs distributed on porous carbon aerogels to boost the ORR performance. The FeSAs-NiCo alloy@N-C sphere exhibits exceptional mass activity and specific activity of 3.705 A.mg-1 and 8.79 mA.cm-2(ECSA), respectively, at 0.85 V versus RHE. It has a superior onset potential of 1.08 V versus RHE, surpassing that of its nanoparticle Fe counterpart and NiCo alloy@N-C sphere. The significant improvement in ORR performance of the FeSAs-NiCo alloy@N-C sphere could be attributed to the positive effects of increased lattice strain due to the single atoms of Fe-NX hybridized with small NiCo alloy NPs. The chitosan gel-assisted molten salt strategy and assistive active sites of Fe-NX hybridized with NiCo alloy NPs regulate the electronic properties of the FeSAs-NiCo alloy@N-C sphere, both geometrically via lattice strain mismatch and electronically through shifting of the d-band center. This could influence the binding energies for oxygen and/or oxygen reduction intermediate adsorption/desorption. The additional improvement in the ORR performance of the FeSAs-NiCo alloy@N-C sphere also benefits from having a lower electrochemical activation energy.

Biological feasibility of discharge a local WTTP sludge to sewer network and centralized WWTP; a case study: Tehran, Iran.

Over the recent years, ever-increasing population growth and higher wastewater production has been a challenge for decentralized wastewater treatment plants (WWTPs). In addition, sludge treatment due to high cost for equipment and place make authorities to find a sustainable approach in both of economical and technical perspectives. One of the proposed solutions is transferring the sludge produced from decentralized WWTP to centralized WWTP. However, the appropriate proportional ratio of raw sludge to raw sewage is a challenge, otherwise, it make anaerobic conditions and sewage rotting along the sewer network based on permissible limit of dihydrogen sulfide (H2S) gas (5 ppm). In the present study, seven reactors with different ratios of sludge to raw sewage (0, 15, 20, 25, 50, 75, 100) were used to stimulate the feasibility of transferring Shahrake Gharb WWTP sludge along the wastewater transfer pipe to the centralized sewage treatment south Tehran WWTP plant in Tehran, Iran. The septic situation and H2S emission of different reactors within 7 h (Time to reach the compound in the south treatment plant) was analyzed by gas meter. The results indicated that the optimum ratio of sludge to raw sewage was 15% without H2S production during 7 h. In addition, due to the high volume of sludge produced by the Shahrake Gharb WWTP, the optimal ratio of lime to total solids (TS) in sludge (gr/gr) (0.6) increased the sludge loading rate from 15 to 30% without any H2S emission during the stimulation study period. Therefore, the lime stabilization and transfer of sludge from a decentralized WWTP to a centralized WWTP is a feasible way to manage the sludge and enhance the treatment capacity in local WWTP.

Enhanced tetracycline degradation with TiO2/natural pyrite S-scheme photocatalyst.

In this study, TiO2 nanoparticles were employed as a photocatalyst for the degradation of tetracycline (TC) under visible light irradiation. The TiO2 nanoparticles were decorated on natural pyrite (TiO2/NP) and characterized using XRD, FTIR, and SEM-EDX methods. This study evaluated the impacts of various operational parameters such as pH, catalyst dosage, initial TC concentration, and light intensity on TC removal. The findings revealed that under optimal conditions (pH 7, catalyst: 2 g/L, TC: 30 mg/L, and light intensity: 60 mW/cm2), 100% of TC and 84% of TOC were removed within 180 min. The kinetics of TC elimination followed a first-order model. The dominant oxidation species involved in the photocatalytic elimination of TC was found to be ·OH radicals in the TiO2/NP system. The reuse experiments showed the high capability of the catalyst after four consecutive cycles. This study confirmed that the TiO2/NP system has high performance in photocatalytic TC removal under optimized experimental conditions.

Evaluating the photocatalytic performance of MOF coated on glass for degradation of gaseous styrene under visible light.

Styrene is a volatile organic compound with various applications, especially in the plastics and paint industries. Exposure to it leads to symptoms such as weakness, suppression of the central nervous system, and nausea, and prolonged exposure to it increases the risk of cancer. Its removal from the air is a topic that researchers have considered. Various methods such as absorption, membrane separation, thermal and catalytic oxidation, biofiltration have been used to remove these compounds. The disadvantages of these compounds include the need for high energy, production of secondary pollutants, large space, providing environmental conditions (temperature and humidity) and long time. The photocatalyst process is considered as an advanced process due to the production of low and safe secondary pollutants. MOFs are nanoparticles with unique photocatalytic properties that convert organic pollutants into water and carbon dioxide under light irradiation and in environmental conditions, which prevent the production of secondary pollutants. The present study aimed to investigate the efficiency of MIL100 (Fe) nanoparticles coated on glass in removing styrene vapor from the air. Surface morphology, crystal structure, pore size, functional groups, and chemical composition of the catalyst were analyzed by SEM, XRD, BET, FTIR, and EDX analysis. The effect of parameters such as initial pollutant concentration, temperature, time, relative humidity, and nanoparticle concentration was evaluated as effective parameters in the removal process. Based on the results, MIL100 (Fe) 0.6 g/l with an 89% removal rate had the best performance for styrene removal. Due to its optimal removal efficiency, it can be used to degrade other air pollutants.

Hydraulic feasibility of discharging sludge from a local WWTP to a centralized WWTP through sewage network lines.

Over the recent years, due to the increase in the population covered by local wastewater treatment plants (WWTP), upgrading the existing treatment plants needs special attention more than ever. One of the suggested solutions removal the existing sludge treatment units in local WWTP and transfer the sludge to a centralized WWTP. The present study was developed to investigate the hydraulic feasibility of sludge transfer from Shahrak-e-GharbWWTP as a local treatment plant to South Tehran sewage treatment plant in Tehran. To this end, at first, a map containing descriptive information and hydraulic characteristics related to the sewage transmission network between local and centralized WWTP was collected from the sewage company. This information was used to calculate the maximum capacity, current flow and draw the hydraulic profile of the sewage transmission line. Then, the transmission line profile was drawn using Manning's hydraulic model and SewerCAD v10.01 software. According to the obtained results, areas 1 and 3 with sewage line diameters of 1000 and 1400 mm did not have any special problem in terms of entering the sludge. Hydraulic analyzes showed that some lines in areas 2, 4, 5, and 6 suffered setbacks and crises after the increase of sludge, which require auxiliary lines. The results indicated that more than 85% of the sewage network lines have the ability to transfer the excess sludge of the local treatment plant, however, in 36 lines, mostly located in zones 2 and 6, with a diameter of 1200 and 2000 mm, there is a crisis of sewage filling and backflow. Therefore, in order to reduce hydraulic stresses in these lines, it was suggested to build an auxiliary line (bypass ring at the beginning and end of these lines).

US-assisted catalytic degradation of paraquat using ZnO/Fe3O4 recoverable composite: Performance, toxicity bioassay test and degradation mechanism.

In this study, the ZnO/Fe3O4 catalyst was used as an active catalyst for the oxidation of Paraquat (PQ) herbicide in aqueous solution under ultrasonic (US) waves. FTIR, XRD, FE-SEM, and VSM analyses were performed to characterize the synthesized catalyst. Studies on the effect of radical scavengers were also carried out and the amount of organic matter degradation was determined by measuring the TOC. Under the optimized conditions (catalyst concentration = 0.75 g/L, herbicide concentration = 10 ppm, US power = 70w), the degradation and mineralization rates of the herbicide were acquired as 96.1% and 68% within 60 min, respectively. The quenching tests showed that the hydroxyl (oOH) radical was the most effective oxidant agent in the degradation process of the PQ under ZnO/Fe3O4/US system. The toxicity of treated effluent assayed by Daphnia Magna was decreased from %73.16 in raw samples to %7.2 in the treated samples, during 96 h. Finally, it can be concluded that ZnO/Fe3O4/US process can be successfully performed as an effective process to herbicides in aqueous solutions, due to the high efficiency and excellent catalytic activity.

Correction to: Environmental impact assessment of a steel industry development plan using combined method involving Leopold matrix and RIAM.

[This corrects the article DOI: 10.1007/s40201-021-00752-4.].

Bio-electrical stimulation process on degradation of Phenanthrene from aqueous solution using a novel anode modified with carbon cloth: Operational performance, microbial activity and energy.

Phenanthrene as the hazardous PAHs-component are extensively detected in industrial wastewater. However, the impacts of bioelectrostimulation process on Phenanthrene degradation in aerobic reactors remained unclear. Here, a novel bioelectrostimulation process equipped with carbon cloth as electrodes was developed to investigate the removal efficiency of Phenanthrene and ATPase enzyme activity in the synthetic wastewater. The results obtained from the present study indicated that a complete Phenanthrene degradation (100%) can be achieved using microbial electrostimulation systems steel mesh coated with carbon cloth (MES-CC) as anode under optimal operational conditions (electrical current: 4 mA, HA concentration: 15 mg L-1) within 18 h. The conductive carbon cloth provides a biofilm carrier to easily transfer the electrons between electrodes and microbial communities. In addition, the highest ATPase enzyme activity (5176 U) was observed when the aerobic MES-CC reactors were operated with electrical current 4 mA. Furthermore, the COD removal efficiency in MES-CC increased from 49% to 96% when the C: N ratio decreased from 20 to 5. The highest value of Vmax in MES-CC for suspended and attached growth were determined to be 2.87 and 0.54 g COD g-1 biomass. Overall, the results demonstrated that MES equipped with carbon cloth and continuous electrical current mode has good potential for efficient Phenanthrene wastewater treatment.

Synthesis of new composite based on TiO2 immobilized in glass fibers for photo-catalytic degradation of chlorobenzene in aqueous solutions.

In this study photo-catalytic degradation of chlorobenzene from aqueous solutions using CQD decorated Fe-doped TiO2 immobilized in Glass Fibers (GF) was investigated. Characteristics of the synthesized photo-catalyst were determined by EF-SEM, EDX, BET, XRD, FTIR, and DRS analysis. Additionally, DRS analysis demonstrated adding CQD to the TiO2-Fe reduced its band gap energy from 2.96 eV to 2.91eV, while that was 3.10 eV for undoped TiO2. Among that three photo-catalysts, GF/CQD(4.5 wt%) decorated Fe-TiO2 composite had performance nearly 100.0%, when pH was 5 and low concentration of chlorobenzene. In addition, GF/CQD(4.5 wt%) decorated Fe-TiO2 composite show it could be well applied for five times and with a little reduction on the performance. Also, no detectable Fe found to be released from the composite. Minimum inhibitory concentration (MIC) for E. coli bacteria was 12.2 mg L-1 of chlorobenzene residual. Our findings show the catalyst was successful for chlorobenzene removal in the wastewater effluent. In conclusion, present hybrid composite could successfully and safely remove chlorobenzene from synthetic aqueous solution.

Environmental impact assessment of a steel industry development plan using combined method involving Leopold matrix and RIAM.

The present study was conducted to determine positive and negative impacts of Sepid-Farab Kavir steel (SKS) complex development plan and to propose suitable managerial strategies by a combined method involving Leopold matrix and Rapid Impact Assessment matrix (RIAM). The SKS complex is located in Aran-Bidgol city, Isfahan, Iran. Two scenarios of project implementation and project cancellation were formulated for SKS complex development plan, which has two sub-phases: construction and operation Using Leopold and RIAM matrices, the direct and indirect impacts of the project on the study area was investigated. The impact analysis for project cancellation scenario showed that the obtained scores of construction and operation phases were -119 and -52, respectively. Also, for project implementation scenario, the obtained scores of construction and operation phases were + 302 and + 382, respectively. The number of positive impacts in the implementation and cancellation scenarios were 354 and 48, respectively, and the number of negative impacts in implementation and cancellation scenarios were 270 and 127, respectively. Also, comparison of positive and negative impacts frequency in the two scenarios, and in the two sub-phases, in RIAM indicated the project implementation will have positive impacts in social-cultural and economic-operational aspects compared to option of prevention, especially in operation phase. The results of environmental impact assessment of the mentioned project indicated the superiority of positive impacts over the negative ones.

Photo-catalytic degradation of bisphenol-a from aqueous solutions using GF/Fe-TiO2-CQD hybrid composite.

In this photocatalytic study, removal of bisphenol-A from aqueous solution was studied using the GF/Fe-TiO2-CQD composite. Due to its health and environmental effects, this compound should be disposed of sources that are mainly industrial wastewater. The phis-chemical properties of the composite were determined by traditional analyzes of EF-SEM, EDX, BET, XRD, FTIR and DRS. In this study, different ratios of CQD in the composite (1.5, 4.5 and 7.5 wt%), pH, and bisphenol-A concentration as variable parameters were investigated. All analyzes, EF-SEM, EDX, BET, XRD, FTIR, show that the GF/Fe-TiO2-CQD composite is well coated on glass fibers (GF) and all the elements in the catalyst are present. On the other hand, DRS analysis showed that CQD reduces the band gap of Fe-TiO2 from 2.96 eV to 2.91 eV, it was 3.10 eV for TiO2. Among different catalysts, GF/Fe-TiO2-CQD4.5wt% has the best performance. The results showed that for GF/Fe-TiO2-CQD4.5wt%, optimum for the process was at pH = 6 in low concentration of bisphenol-A. The first order model for the photocatalytic degradation process were well studied. In addition, GF/Fe-TiO2-CQD4.5wt% showed that it can be used many times with a minimal reduction in performance. As a result, the GF/Fe-TiO2-CQD4.5wt% composite can successfully remove bisphenol-A form in synthetic aqueous solution. However, it is necessary to further studies to applied that for real water source in water and wastewater treatment plants.

Effect of COVID-19 pandemic on medical waste management: a case study.

Covid-19 Pandemic leads to medical services for the society all over the world. The Covid-19 pandemic influence the waste management and specially medical waste management. In this study, the effect of the Covid-19 outbreak on medical waste was evaluated via assessing the solid waste generation, composition, and management status in five hospitals in Iran. The results indicated that the epidemic Covid-19 leads to increased waste generation on average 102.2 % in both private and public hospitals. In addition, the ratio of infectious waste in the studied hospitals increased by an average of 9 % in medical waste composition and 121 % compared with before COVID-19 pandemic. Changes in plans and management measurement such as increasing the frequency of waste collection per week leads to lower the risk of infection transmission from medical waste in the studied hospitals. The results obtained from the present research clearly show the changes in medical waste generation and waste composition within pandemic Covid-19. In addition, established new ward, Covid-19 ward with high-infected waste led to new challenges which should be managed properly by change in routine activities.

Preparation of a thin-film nanocomposite forward osmosis membrane for the removal of organic micro-pollutants from aqueous solutions.

In this study, a thin-film nanocomposite forward osmosis (TFN FO) membrane was synthesized. The properties and structures of membranes were evaluated for the removal of three organic micro-pollutants from synthetic and real industrial wastewater samples. Laboratory scale fabrication thin-film nanocomposite forward osmosis (FO) membranes composed of a support layer and an active layer. The former was constructed by adding different weight ratios of polyethylene glycol 400 (PEG-400) (0-8 wt.%), polysulfone (PSf), and 1-methyl, 2-pyrrolidone via the phase inversion process, while the latter was synthesized by the incorporation of different weight ratios of graphene oxide (GO) (0-0.012 wt.%), M-phenylenediamine, and 1, 3, 5-benzene trichloride into polyamide layer through the interfacial polymerization reaction. In comparison with thin-film composite (TFC) membranes, the TFN membranes revealed higher hydrophilicity, porosity, water permeability, water flux and salt rejection and lower internal concentration polarization (ICP), reverse salt flux and specific reverse salt flux. The TFN membrane containing 0.008% GO in the active layer and 4% PEG 400 in the support layer exhibited maximum water flux (34.3 LMH) and rejection rate of benzene, phenol and toluene (97%, 84%, and 91%, respectively). The results revealed that the TFN-FO membranes possess a promising potential to improve the water flux and wastewater treatment.

Desorption kinetics and isotherms of phenanthrene from contaminated soil.

BACKGROUND: Prediction of polycyclic aromatic hydrocarbons (PAHs) desorption from soil to estimate available fraction regarding to initial concentration of the contaminant is of great important in soil pollution management, which has poorly been understood until now. In the present study estimation of fast desorption fraction which is considered as available fraction was conducted by evaluating desorption kinetics of phenanthrene (a three ring PAH) from artificially contaminated soils through the mathematical models. METHODS: Desorption rate of phenanthrene (PHE) was investigated by using the nonionic surfactant Tween80 in a series of batch experiments. The effects of reaction time from 5 to 1440 min and initial PHE concentration in the range of 100-1600 mg/kg were studied. RESULTS: Available fractions of the contaminant were achieved within the first hour of desorption process as the system reached to equilibrium conditions. Experimental data were examined by using kinetic models including pseudo-first-order, pseudo-second-order in four linearized forms, and fractional power. Among the models tested, experimental data were well described by pseudo-second-order model type (III) and (IV) and fractional power equation. Fast desorption rates, as Available fractions were determined 79%, 46%, 40%, 39%, and 35% for initial PHE concentrations of 100, 400, 800, 1200, and 1600 mg/kg respectively. Among the evaluated isotherm models, including Freundlich, Langmuir in four linearized forms, and Temkin, the equilibrium data were well fitted by the first one. CONCLUSION: Applying the nonionic surfactant Tween80 is a useful method to determine available fraction of the contaminant. This method will provide the management of contaminated sites by choosing a proper technique for remediation and predicting achievable treatment efficiency.

Degradation of dimethyl phthalate using persulfate activated by UV and ferrous ions: optimizing operational parameters mechanism and pathway.

The present study aimed to model and optimize the dimethyl phthalate (DMP) degradation from aqueous solution using UVC/ Na2S2O8/Fe2+ system based on the response surface methodology (RSM). A high removal efficiency (97%) and TOC reduction (64.2%) were obtained under optimum conditions i.e. contact time = 90 min, SPS concentration = 0.601 mM/L, Fe2+ = 0.075 mM/L, pH = 11 and DMP concentration = 5 mg/L. Quenching experiments confirmed that sulfate radicals were predominant radical species for DMP degradation. The effect of CO3 - on DMP degradation was more complicated than other aquatic background anions. The possible pathway for DMP decomposition was proposed according to HPLC and GC-MS analysis. The average oxidation state (AOS) and carbon oxidation state (COS) values as biodegradability indicators demonstrated that the UVC/SPS/Fe2+ system can improve the bioavailability of DMP over the time. Finally, the performance of UVC/SPS/Fe2+ system for DMP treatment in different aquatic solutions: tap water, surface runoff, treated and raw wastewater were found to be 95.7, 88.5, 80.5, and 56.4%, respectively. Graphical abstract.

Data on modeling of UV/Na2S2O8/FeS2 process in amoxicillin removal using Box-Behnken methodology.

Among the pharmaceutical compounds, antibiotics have been paid specific consideration, due to their acute and chronic toxic effects on organisms. Amoxicillin (AMX) is used widely for treatment of bacterial infections. About 80% of amoxicillin excreted unchanged and enters the aquatic environment through different routes including disposal of municipal wastewaters, hospital wastewaters and farm wastewaters. In this study degradation of amoxicillin by UV/Na2S2O8/FeS2 process was evaluated. According to the results, the R-squared and adjusted R-squared were 0.9877 and 0.9828, respectively. The AMX removal efficiency was 93% at optimum conditions. Thus, UV/Na2S2O8/FeS2 process is a useful process for amoxicillin removal.

Biosurfactant production and its effects on solubilization activity of phenanthrene: a longitudinal study.

Pseudomonas facilis and Pseudomonasspp., isolated on the basis of its ability to grow on polycyclic aromatic hydrocarbon, was assayed for biosurfactant production (BP) potentials by measuring the surface tension (ST) of the culture supernatant at different time intervals. The strains in three levels of initial inoculum size (OD600 nm = 0.5, 1, 1.5) were added to medium to determine if bacterial inoculum size affects solubilization of phenanthrene (PHE).The result showed that although the two strains reduced the mean ST to less than 34.12 mN m(-1) at the end of day 6, mean solubilization activity of PHE reached 77.05 mg L(-1) on the sixth day. There was a significant increase in BP over time (P = 0.008); reaching its peak, 157.84 mg L(-1), at the end of the sixth day. Mean solubilization activity of PHE was not significantly different for the two strains (P = 0.216). The time-course study revealed that the ST reduction and BP potential was enhanced as inoculation size increased, leading to higher PHE solubility during the incubation time. However, the trend of increase in PHE solubility was not totally in the same way to cell growth and BP. It may be suggested that more bacterial density needs to be inoculated for practical application of effective bioremediation.

Ozonation optimization and modeling for treating diesel-contaminated water.

The effect of ozonation on treatment of diesel-contaminated water was investigated on a laboratory scale. Factorial design and response surface methodology (RSM) were used to evaluate and optimize the effects of pH, ozone flow rate, and contact time on the treatment process. A Box-Behnken design was successfully applied for modeling and optimizing the removal of total petroleum hydrocarbons (TPHs). The results showed that ozonation is an efficient technique for removing diesel from aqueous solution. The determination coefficient (R(2)) was found to be 0.9437, indicating that the proposed model was capable of predicting the removal of TPHs by ozonation. The optimum values of experimental initial pH, degree of O3, and reaction time were 7.0, 1.5, and 35 min, respectively, which could contribute to approximately 60% of TPH removal. This result is in good agreement with the predicted value of 57.28%.

Enhanced removal of nitrate from water using nZVI@MWCNTs composite: synthesis, kinetics and mechanism of reduction.

Herein, multi-wall carbon nanotubes (MWCNTs) were used as the carrier of nano-zero valent iron (nZVI) particles to fabricate a composite known as nZVI@MWCNTs. The composite was then characterized and applied in the nitrate removal process in a batch system under anoxic conditions. The influential parameters such as pH, various concentrations of nitrate and composite were investigated within 240 min of the reaction. The mechanism, kinetics and end-products of nitrate reduction were also evaluated. Results revealed that the removal nitrate percentage for nZVI@MWCNTs composite was higher than that of nZVI and MWCNTs alone. Experimental data from nitrate reduction were fitted to the Langmuir-Hinshelwood kinetic model. The values of observed rate constant (kobs) decreased with increasing the initial concentration of nitrate. Our experiments proved that the nitrate removal efficiency was favorable once both high amounts of nZVI@MWCNTs and low concentrations of nitrate were applied. The predominant end-products of the nitrate reduction were ammonium (84%) and nitrogen gas (15%). Our findings also revealed that ZVI@MWCNTs is potentially a good composite for removal/reduction of nitrate from aqueous solutions.

Experimental design approach to the optimization of PAHs bioremediation from artificially contaminated soil: application of variables screening development.

BACKGROUND: The effectiveness of bioremediation systems for PAH-contaminated soil may be constrained by physicochemical properties of contaminants and environmental factors. Information on what is the most effective factor in bioremediation process is essential in the decision of what stimulations can be taken to assist the biodegradation efficacy. METHODS: In this study, four factors of surfactant (Tween 80), humic acid (HA), salinity and nutrients in a 2(4) full factorial design were screened in bioremediation of phenanthrene contaminated soil by using a consortium of bacteria. RESULTS: Between the employed levels of the factors only salinity had not significant effect. Optimal concentrations of surfactant, HA and nutrient were obtained by a response surface design. For phenanthrene biodegradation, a central composite face centred design (CCFD) showed that nutrient, surfactant and HA concentrations had highly significant, significant and insignificant effects, respectively. The best conditions with 87.1% phenanthrene biodegradation were 150 mg HA/Kg soil, 12.68 µg/L surfactant, and nutrients as K2HPO4, 0.8; KH2PO4, 0.2 and KNO3, 1 g/L. A high similarity was between the model prediction and experimental results. CONCLUSIONS: This study showed that nutrient with 81.27% efficiency could be considered as the most effective factor for practical implications of bioremediation process for PAHs contaminated soil cleanup strategies.