Aim: In this study, the decolorization of methylene blue (MB) by the electro-Fenton process using stainless steel (SS) mesh electrodes was examined. Materials and Methods: The effects of initial dye concentration, pH, and ratio of Fe: H₂O₂, current density, and type of electrode were studied. The kinetics of the reactions was also studied. Results: The highest removal rate 99%was obtained at pH 3 within 20 min. Kinetics experiment studies showed that removal of dye was faster at lower initial dye concentrations. The results revealed that color removal was highest at a Fe²⁺:H₂O₂ ratio of 1:4. An increase in current density resulted in an increase in oxidation rate and faster removal of color. The results demonstrated that increasing the size of the mesh pores led to an increase in the percentage of dye removal. The highest removal percentage (94.5%) was observed in 25 min with a mesh 2 electrode. The constant rate of dye removal on steel mesh 2 was 6.6 times higher than a steel plate. Energy consumed in this state was = 1.6 kWh/m³, compared to 2.6 kWh/m³ under other conditions. Conclusion: Using SS mesh electrodes was very effective in color removal for MB under optimal conditions. The present study showed that increasing the steel mesh size improved the conditions for color removal and reduced the energy consumption. Therefore, it is suggested that steel mesh be used as an electrode for electrochemical processes.

Aim: The aim of this study was to investigate the degradation of an azo dye, reactive red 198 (RR198), by ozone, H₂O₂/O₃, and persulfate from aqueous solutions. Materials and Methods: The application of several advanced oxidation processes including single ozonation, O₃/H₂O₂, and persulfate for degradation of RR198 at concentration of 200 mg/L was investigated. The effect of various parameters including pH, H2O2, persulfate doses, and temperature was studied on the degradation of RR198 from aqueous solutions. In addition, the effects of these processes on biodegradability of RR198 were evaluated. Results: The results showed that the degradation rate was increased by increasing H₂O₂ concentration. The optimum H₂O₂ concentration was obtained in the range of 0.03 mol/L at dye concentration of 200 mg/L. Alkaline pH, higher temperature, and persulfate dose (12 mM) were favored in dye and COD removal. Moreover, compared with ozone and peroxone, the persulfate oxidation could achieve a higher color and COD removal at the same reaction time. Persulfate has greater potential to improve the biodegradability of RR198 solution than ozone and ozone/H₂O₂ process. Biochemical oxygen demand/COD ratio of the dye solution treated by persulfate, ozone/H₂O₂, and ozone at reaction time 40 min was 0.73, 0.63, and 0.59, respectively. Conclusion: These findings show that oxidation by persulfate is a promising alternative for the treatment of RR198 containing solution as a recalcitrant pollutant.

Aims: The purpose of this study was to investigate adsorption isotherms of removing bisphenol A (BPA) from aqueous solutions using magnetic nanoparticles Fe₃O₄ and SiO₂. BPA is an endocrine disrupting chemical that has caused great concern because of its potential risk to human health. Materials and Methods: The combined of magnetic nanoparticles Fe₃O₄ and SiO₂ were applied to remove BPA from aqueous solution at a dose of 2 g/L. Isotherm Fitting Tool software was used for isotherm study in contact time 20 min, the initial concentration of BPA 0–10 (interval 1 mg/L), and pH 5. Results: The maximum adsorption efficiency was found to be 55%. The results of our experiments showed that maximum adsorption efficiency was achieved at t = 20 min and pH 5. Conclusion: The isotherm study showed that Langmuir isotherm described the equilibrium adsorption data better than other isotherms alternative.

Gordonia terrae is the aerobic actinomycete that is microflora in soil. This study is the first report of Gordonia species from Iran soil and accurate identification in level species was obtained with conventional tests and 16S rRNA gene sequencing.

Aims: In this work, activated carbon, magnesium oxide (MgO), and MgO stabilized on activated carbon derived from sweet corn were applied as catalysts for oxalic acid degradation from aqueous. Materials and Methods: Sweet corn pile was used for the production of activated carbon, and magnesium nitrate applied for the production of MgO. Ozone concentration determined using iodometry method, and oxalic acid concentration was determined by a spectrophotometer at 210 nm. Moreover, the effect of MgO, activated carbon and oxalic acid concentration, pH, contact time, and oxalic acid mineralization were investigated. Results: The results showed that ozonation in the presence of activated carbon or MgO and/or MgO stabilized on activated carbon, increased the decomposition rate of oxalic acid. Removal efficiency of oxalic acid with increasing catalysts dose of 0.05–1 g, pH of 3–11, and time of 1–30 min have increased from 72% to 85%, 72% to 85%, and 92% to 95% respectively. Furthermore with increasing of oxalic acid from 40 to 100 mg/L, the removal efficiency decreased from 96% to 88%. Conclusion: According to this study, catalytic ozonation processes have shorter time and more removal efficiently than the single ozonation process. Moreover, the results showed that oxalic acid was mineralized significantly and interfering factors have negligible effect on the catalytic ozonation process than the single ozonation.

Aims: Present study was done by using upflow anaerobic sludge blanket (UASB) reactor to investigate the effect of influent chemical oxygen demand (COD) and organic load rate on the formation of anaerobic granules in wastewater treatment. Martials and Methods: Upflow anaerobic sludge blanket reactor with working volume 30 L was studied using actual slaughterhouse wastewater at a hydraulic retention time of 1.24 d and at temperatures in the range of 35°C ± 0.5°C for 320 days. The inoculum was extracted from the anaerobic digester of municipal sewage treatment plant, and the UASB reactor was filled with 8 L of sludge. Results: The results indicated that under the optimal conditions, about 94.6% of COD could be effectively removed from slaughterhouse wastewater with the UASB. The highest and lowest COD removal efficiency was 40.5 and 94.6% corresponding to influent COD of 1266.8 and 1222.2 mg/L, respectively. The fluctuation of solution pH in UASB operation was in the range of 6.68-8.03. The average of solution pH was 7.46 ± 0.36. The solution pH was gradually improved with UASB operation. Different granule sizes coexisted in the UASB reactor, but granules with the size of 1-3 mm were predominant. The maximum observed size of anaerobic granule was 7 mm. Conclusion: Application of slaughterhouse wastewater as feed wastewater demonstrated that the slaughterhouse wastewater to be more effective in promoting the formation of anaerobic granules and granule size in UASB reactor.

Aims: The quantity, composition and physiochemical characteristics of wastes are important factors in selecting an appropriate treatment method. Having knowledge about the current status of medical wastes in any region is necessary for the establishment of effective medical waste management. Martials and Methods: In this field study, official data obtained from the national statistical center were used. The statistical population for sampling and physical analysis includes two hospitals and five health-care centers, selected randomly, and WHO standard procedures were followed for wastes segregation. Results: Based on data obtained, 1335 kg of medical wastes is daily generated in Gachsaran County of which 563 kg are infected and 772 kg are noninfected. A minor part of medical wastes are incinerated or delivered to the municipality untreated. However, the major part is hydroclaved. The largest medical center in the region is Shahid Rajaei Hospital located in Dogonbadan city and infected wastes from the whole region are sent to this center to be hydroclaved. Conclusion: In conclusion, the quantity of infected wastes in the region is higher when compared to other cities in Iran. The high quantity of infected wastes may be a result of poor separation of infected and noninfected wastes by personnel due to lack of required knowledge.

Aims: In the present study, a risk assessment for growth of Clostridium botulinum in model seafood deli salads was performed along with the effect of growth of resident microbes on the intrinsic and extrinsic properties of the product. Furthermore, high hydrostatic pressure (HHP) was applied to induce the germination of the surrogate spores. Materials and Methods: Five batches of seafood deli salads were stored at 4°C for up to 42 days, with samples being withdrawn periodically for microbial and chemical analysis. The extrinsic (oxygen content of the headspace) and intrinsic (redox potential, pH, and water activity) properties were determined along with microbial counts (total viable counts [TVCs], yeast and mold, lactic acid bacteria) over the product shelf-life. The data generated were then uploaded into a predictive model, and the potential growth of C. botulinum was assessed under different storage conditions. Furthermore, product inoculated with Bacillus atrophaeus was pressure treated at 400, 500, and 600 MPa for 1, 2, and 3 min at 20°C. Results: From analysis of the deli salads during storage at 4°C, the TVC remained below 2 log colony forming unit (CFU)/g with no lactic acid bacteria being detected. The yeast and mold count progressively increased during the storage period attaining 6 log CFU/g at the end of the 45-day storage period. There was no change in the pH and oxidation-reduction potential of the deli salads during storage. Predictive model indicated that in storage at 4°C and pH 5.1 and a water activity of 0.974, the generation time was 561.37 h. Only one log spore germination induction was observed when HHP treatment was performed at 600 MPa for 3 min. Conclusions: From predictive modeling, it was determined that based on the intrinsic and extrinsic factors of stored deli salad, the growth of C. botulinum was unlikely. In addition, the application of HHP did not significantly induce germination of the surrogate spores.