Antibacterial effect of TiO2 modified with poly-amidoamine dendrimer - G3 on S. aureus and E. coli in aqueous solutions.

This study investigated bacterial removal using TiO2 nanoparticles (NPs) modified with poly-amidoamine dendrimer macromolecule (PAMAM, G3). The PAMAM G3/TiO2 (nanohybrid) was used to specify antibacterial properties via broth microdilution (MBC-Minimum Bactericidal Concentration and MIC-Minimum Inhibitory Concentration-determination), paper disc diffusion, and surface plate count methods. The nanohybrid was characterized via the different techniques. The effects of different factors including initial bacteria count, run time, solution pH, and the nanohybrid concentration were studied. The nanohybrid cytotoxicity was studied on AGS and MKN45 cells line by MTT assay. It was revealed that the nanohybrid was effective in intercepting both bacterial strains growth. The MIC value for S. aureus and E. coli were determined to be 4 and 2 µg/mL, respectively. The MBC value for both strains were calculated to be 32 µg/mL. The results showed removal efficiency of 100% for S. aureus and E. coli bacteria in optimum situation. The decrease in cell viability in the dosage of 32 µg/mL after 72 h treatment for AGS and MKN45 cells line were shown to be 6.2 and 4.6%, respectively. The nanohybrid was able to decrease the S. aureus and E. coli count in solution, which meets the drinking water criterions aligned with WHO guidelines.

Kinetic studies on the removal of phenol by MBBR from saline wastewater.

BACKGROUND: Phenols are chemical compounds which are included in the high priority of pollutants by environmental protection agency (USEPA). The presence of high concentrations of phenols in wastewaters like oil refineries, petrochemical plants, olive oil, pesticide production and oil field operations contain high soluble solids (TDS) and in an olive oil plant, wastewater is acidic, high salty and phenol concentrations are in the range of 0.1- 1%. METHODS: Kinetic parameters were calculated according to Monod, Modified Stover- Kincannon, Hamoda and Haldane models. The influence of different initial phenol concentrations on the biodegradation rate was performed. The concentrations of phenol varied from 0 to 500 mg/l. RESULTS: The value of Ki in saline phenolic wastewater in attached growth systems was higher than suspended growth systems that represented a higher phenol inhibition in suspended growth systems. It was obvious that the best model fitting the obtained data are Hamoda model and the Modified Stover-Kincannon model, having highest R2 values of 0.991 and 1, respectively. The value of Ki in saline phenolic wastewater in attached growth system was higher than suspended growth systems which represented a higher phenol inhibition in suspended growth systems. CONCLUSIONS: Hamoda model and the Modified Stover-Kincannon model having highest R2 value of 0.991 and 1, respectively, and also predicting reasonable kinetic coefficient values.

Cardiovascular and respiratory mortality attributed to ground-level ozone in Ahvaz, Iran.

Ahvaz, the capital city of Khuzestan Province, which produces Iran's most oil, is on the rolls of fame in view of air pollution. It has also suffered from dust storm during the recent two decades. So, emissions from transportation systems, steel, oil, black carbon, and other industries as anthropogenic sources and dust storm as a new phenomenon are two major concerns of air pollution in Ahvaz. Without any doubt, they can cause many serious problems for the environment and humans in this megacity. The main objective of the present study was to estimate the impact of ground-level ozone (GLO) as a secondary pollutant on human heath. Data of GLO in four monitoring stations were collected at the first step and they were processed and at the final step they were inserted to a health effect model. Findings showed that cumulative cases of cardiovascular and respiratory deaths which attributed to GLO were 43 and 173 persons, respectively. Corresponding RR for these two events were 1.008 (95% CI) and 1.004 (95% CI), respectively. Although we did not provide a distinction between winter and summer in case of mentioned mortalities attributed to GLO, ozone concentrations in winter due to more fuel consumption and sub adiabatic condition in tropospheric atmospherewere higher than those GLO in summer.

Removal of natural organic matter (NOM) from an aqueous solution by NaCl and surfactant-modified clinoptilolite.

Zeolitic tuffs are found in different parts of the world. Iranian zeolite is a low-cost material that can be frequently found in nature. Surfactant-modified zeolite (SMZ) can be used for the adsorption of natural organic matter (NOM) from aqueous solutions. The adsorption study was conducted to evaluate the adsorption capacity of SMZ; furthermore, the effects of contact time, initial pH, and the initial adsorbent dose on the adsorption process were investigated in a batch system. The kinetic studies showed that the adsorption of NOM on SMZ was a gradual process. The optimum initial pH values for the adsorption of NOM on SMZ were in the acidic ranges. The batch kinetic experiments showed that the adsorption followed the pseudo-second-order kinetic model with good correlation coefficients. The equilibrium data were well described by the Langmuir isotherm model. The results show that the natural zeolite being modified with NaCl and hexadecyltrimethylammonium bromide as a cationic surfactant was an appropriate adsorbent for the removal of NOM.