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Bisphenol A (BPA) and its derivatives have extensive applications as lubricants and polymer stabilizers and components of photographic developers. In this study, the photo catalytic degradation of bisphenol A (BPA) was studied on ZnO nanoparticles coated on a fixed bed which was treated in two light sources including ultraviolet-C (UVC-254 nm) and natural solar in compound parabolic concentrators (CPC). Characterization of the ZnO nanoparticles samples was performed by field-emission scanning electron microscope, X-ray diffraction, ultraviolet-visible (UV-VIS) spectrophotometer, and Brunauer–Emmett–Teller measurements. The highest photocatalytic and photolysis activity for the degradation of BPA has been obtained for the ZnO/UVCand UVCwith 99% and 40% efficiencies in 120 min. Also, the highest photocatalytic and photolysis activity for the degradation of BPA has been obtained for the CPC reactor and 97% and 31% efficiency in 120 min. The photocatalytic degradation reaction of BPA was monitored by high-performance liquid chromatography, total organic carbon, and gas chromatography/mass (GC-MASS) analyses. The results of GC-MASS analysis show that the degradation of BPA occurs through the production of glycolic acid, benzoic acid, and vinyl phenol products and its decomposition occurs by ring fission and then subsequent reactions with OH radicals. These results show that the photo catalytic degradation of solar light and UV has high efficiency in BPA removal as well as effluent mineralization.

Preventing the growth of microorganisms in water distribution network (WDN) is an important public health priority. In this study, 98 water samples were collected from the Gorgan City (Iran) water distribution network (WDN) to assess fungal and bacterial contamination in WDN and their association with physicochemical parameters. All microbiological and physicochemical tests were performed as described in the standard method. The results showed that 15.3 %, 12.2 %, and 2 % of the sample had total coliforms, Clostridium perfringensand fecal coliforms, respectively; however, no Escherichia coliand fecal streptococci were found in samples. The average count of heterotrophic bacteria and fungi was 203.45 CFU/mL and 6.83 CFU/100 mL, respectively. Seven genera of fungi were isolated, of which Candida(19.4 %) and Aspergillus(11.2 %) were the most prevalent, followed by Penicillium(5.1 %), Rhodotorula(3.1 %), Cladosporium(2 %), Acremonium(2 %) and Alternaria(1 %). The mean and Standard deviation of free residual chlorine (FRC), pH, turbidity, temperature, total organic carbon and electrical conductivity were 0.22 ± 0.27 mg/l, 7.28 ± 0.22, 0.61 ± 0.68 NTU, 19.27 ± 2.83 °C, 0.45 ± 0.17 mg/l, and 953.49 ± 207.54 (µs/cm), respectively. The presence of pathogens fungus is a major public health concern for people with lowered immunity. The present study indicated that using microorganisms with different features provides a more reliable evaluation to assess the microbial growth in WDN. Amongst physicochemical parameters, FRC above 0.8 mg/l prevented the fungal and bacterial pathogens growth in WDN. However, further research is required to measure the risks of trihalomethane formation.

In the present study, magnetic montmorillonite (MMT/Fe3O4) was prepared using chemical precipitation for adsorption of Pb(II) and was characterized by scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, X-ray diffraction and Fourier-transform infrared spectroscopy (FTIR). The results showed that Fe3O4uniformly occurred on MMT. The maximum adsorption capacity of Pb(II) by MMT/Fe3O4was obtained to be 36.76 mg/g, which was higher than the Fe3O4and MMT alone. The removal efficiency of Pb(II) was strongly dependent on the operating factors, where the maximum efficiency occurred at pH of 5, adsorbent dose of 0.4 g/L, Pb(II) concentration of 30 mg/L, stirring rate of 300 rpm, and contact time of 120 min. The adsorption data followed the Langmuir isotherm, and the kinetic results showed that the chemisorption process is the dominant mechanism for Pb(II) removal. The results of the FTIR analysis explained that the Al–OH and Fe–O functional groups have high participation in pollutant adsorption. The column study emphasized that MMT/Fe3O4nanocomposite has excellent efficiency in the treatment of real wastewater containing Pb(II). In addition, excellent magnetic separation and regeneration performance indicated the applicability of adsorbent for the treatment of synthetic and real solutions. Keywords: MMT/Fe3O4; Pb(II); Column study; Adsorption; Removal mechanism

p-nitroaniline (PNA) is a well-known acute oral, dermal, and inhalation toxin that has been reported as a priority toxic pollutant by the Environmental Protection Agency (EPA). In this study, MgAl-layered double hydroxides (MgAl-LDH) nanoparticles were prepared by a simple and fast co-precipitation method and used as a catalyst in the ozonation process to remove PNA from aqueous solutions. Next, the structure of the synthesized MgAl-LDH was investigated by X-ray diffraction pattern and field emission scanning electron microscopy-energy dispersive spectroscopy. The response surface methodology was used to investigate the effects of different parameters including reaction time, initial PNA concentration, pH, and LDH loading on the removal of PNA by MgAl-LDH catalytic ozonation process (MgAl-LDH COP). The highest removal efficiency of 91.5% was observed in optimum conditions as follows: initial PNA concentration of 162.5 mg/L, pH of 8.25, LDH loading of 750 mg/L, and reaction time of 70 min. The quadratic model was obtained with a high degree of fit. The removal values of COD and TOC were 77% and 68%, respectively. As a result, MgAl-LDH COP, as an excellent practical alternative, has a high performance in removing persistent compounds such as PNA from aqueous solutions.

Humic acid (HA) is a natural organic matter, which is naturally present in raw water sources due to the decomposition of dead animals and plants. Therefore, the catalytic properties of a carbonaceous nanocomposite in the catalytic ozonation process (COP) of HA were investigated, and the results were compared with those obtained from the single ozonation process (SOP). Magnetic carbonaceous nanocomposite, as a novel catalyst, was applied to optimize the conditions for the removal of HA in the COP, and the influential parameters such as pH, retention time, catalyst dosage, and addition of radical scavengers were all evaluated. This is an experimental study in which the removal of HA by a COP was investigated in a cylindrical glass reactor (a useful volume of 250 mL) with a semi-continuous flow. Catalyst raw material was the granular activated carbon (GAC) that has been stabilized on Fe3O4nanoparticles by the calcination method. The results revealed that by increasing the retention time, pH, and catalyst dosage, HA and TOC removal efficiencies by both process (SOP and COP) was increased. The highest removal efficiencies of HA and TOC in the COP process were 95% and 87.67%, respectively while their removal efficiencies in the SOP process were 76.8% and 67.1% under the conditions including pH of 9, contact time of 60 min, and HA concentrations of 15 mg/L. The highest removal of the HA by the SOP and catalyst adsorption was obtained to be 76% and 5.8% after 60 min, respectively; however, it was observed to be 95.7% in the COP, in the same contact time. The presence of tert-butanol alcohol (TBA) did not significantly affect the removal of the HA in the COP. Practically, this study revealed that the magnetically activated carbon catalyst could be potentially employed in the COP for the treatment of the water having average concentrations of HA substances.

Ammonia in the form of ammonium ion is toxic and could decrease the dissolved oxygen in water and endanger the aquatic life. The aim of this study is the removal of ammonium using a new method of oxidation and adsorption by catalytic ozonation and clinoptilolite zeolite, respectively. The research method is an experimental study. First, optimal pH of ammonium adsorption on carbon catalyst (5 g/L), Garmsar and Firoozkooh zeolites and oxidation process were determined. Then, in catalytic ozonation process, the effect of other variables on ammonium removal efficiency such as the concentration of carbonic catalyst (0.5–50 g/L) and the reaction time were investigated. Then, the effect of retention time and adsorbent concentration on adsorption of the remaining ammonium and nitrate production by the oxidation process using zeolites and their modifications were determined. The results showed that optimum pH for the ammonium adsorption process by carbon catalyst, catalytic ozonation and zeolite were 8, 9 and 8, respectively. However, the optimum pH of 4 was determined for nitrate removal. The highest ammonium absorption capacity was related to natural Firoozookh zeolite as 18.5 mg/g, and the effect of ligand and acid modification decreased the absorbed capacity by 12% and 14%, respectively. The highest nitrate removal efficiency was related to Garmsar ligand modified zeolite (98%) and an absorption capacity of 11.2 mg/g. In the catalytic ozonation process/absorption process, the concentration of ammonium was decreased to 0.6 mg/L. This method effectively eliminates ammonium, and the modification of zeolite with cationic surfactant increased the efficiency of nitrate removal and therefore the concentrations of all pollutants were below standards.

Non-degradation compounds are nowadays not being disposed into the environment, or are removed before being disposed into the environment. The aim of this study was to assess the degradation of aniline from aqueous media by electro/Fe2+/peroxydisulphate (PDS) process. The effects of different parameters like pH (3–9), electric current (EC; 10–30 mA/cm2), dose of PDS (10–40 mM), Fe2+dose (5–20 mM) and initial aniline concentration (20–100 mg/L) on the degradation of aniline were investigated in the laboratory reactor in the batch condition. The results showed that the removal efficiency of aniline decreased by increasing the initial pH and pollutant concentration; however, with increasing EC and PDS doses and ferrous concentration, the removal efficiency increased. The maximum of aniline degradation, equalling 83%, was obtained at 60 min of reaction time. Also, for reaction time of 60-min runs, PDS only, EC only, PDS + Fe, PDS + EC and PDS + Fe + Fe, respectively, have 8.9%, 53%, 43%, 65% and 83% of the removal efficiency. The degradation efficiency of aniline from synthetic wastewater was significantly improved when the combined processes PDS/electro-conduction/Fe2+was applied.

AbstractIn this study, the effects of some operational factors, such as pH value, nano-ZnO loading, UV-A irradiation time, and power of radiation on the degradation efficiency of metronidazole (MNZ) in aqueous solution were discussed through photocatalytic experiments using nano-ZnO as the photocatalyst. Results show that removal of metronidazole (MNZ) and COD has a direct correlation with power of UV-A lamp and irradiation time. MNZ solution (80 mg L−1) was rapidly removed by the irradiation of UV lamp OSRAM 125 W high pressure within 180 min. In nano-ZnO/UV photocatalysis reactor, irradiation time and power of UV lamp have a great effect on metronidazole degradation. Statistical analysis (One-way ANOVA) has shown that the pH (in acedic and basic condition) and variation of nano-ZnO concentration has no significant effects on MNZ removal, COD, and BOD5/COD ratio. But the maximum degradation of MNZ occurred at pH 10 and 1.5 gL−1nano-ZnO. Maximum degradation of MNZ and COD was 96.55 and 95.42%, respectively. In addition, biodegradability improved from ∼0 to 0.091 within 180 min.

In this study, the effects of some operational factors, such as pH value, nano-ZnO loading, UV-A irradiation time, and power of radiation on the degradation efficiency of metronidazole (MNZ) in aqueous solution were discussed through photocatalytic experiments using nano-ZnO as the photocatalyst. Results show that removal of metronidazole (MNZ) and COD has a direct correlation with power of UV-A lamp and irradiation time. MNZ solution (80 mg L−1) was rapidly removed by the irradiation of UV lamp OSRAM 125W high pressure within 180 min. In nano-ZnO/UV photocatalysis reactor, irradiation time and power of UV lamp have a great effect on metronidazole degradation. Statistical analysis (One-way ANOVA) has shown that the pH (in acedic and basic condition) and variation of nano-ZnO concentration has no significant effects on MNZ removal, COD, and BOD5/COD ratio. But the maximum degradation of MNZ occurred at pH 10 and 1.5 gL−1nano-ZnO. Maximum degradation of MNZ and COD was 96.55 and 95.42%, respectively. In addition, biodegradability improved from ∼0 to 0.091 within 180 min.

The aim of the research was to investigate the removal of metronidazole from aqueous solutions by Fe/charcoal micro-electrolysis fluidized bed reactor. The effective variables influencing the metronidazole removal including the initial pH of the solution, the initial concentration of metronidazole, contact time, aeration rate and Fe/charcoal ratio were studied. The amount of secondary iron ions pollution in the reactor effluent was investigated by a flame atomic absorption device. Degradation reaction kinetics were studied. The removal efficiency of metronidazole in the actual hospital wastewater sample was investigated under optimal conditions of the reactor. The stability and performance of the reactor was investigated through 4 consecutive cycles. Data analysis was performed by SPSS-16. The maximum removal efficiencies were obtained in optimal conditions including pH: 7, the contact time of 70 min, aeration rate of 6 L/min, charcoal/Fe ratio 1:1 and initial concentration of metronidazole of 10 mg/L as 90 and 78 percent for synthetic solutions and actual wastewater respectively. No secondary pollution of iron ions was detected. In the study of linear kinetic models, the degradation process followed pseudo-first kinetic order. The Fe/charcoal micro-electrolysis system is well-suited for efficient removal of antibiotics from aqueous solutions and applies to industrial scale.