Background: Dyes are one of the most important industrial pollutants, especially in textile industries. Many methods have been proposed in order to remove color from wastewater among which, adsorption is more acceptable due to the ability for its use in the large scale. Objectives: The objective of this study was to investigate pumice as an inexpensive adsorbent for removal of Methylene Blue from aqueous solutions. Materials and Methods:In this work the Modified Pumice Stone has been applied for removal of the Methylene Blue dye from aqueous environments. The effect of pH, contact time, initial concentration and amount of adsorbent were considered. In order to investigate the mechanism of the adsorption process, several kinetic models including pseudo-first order, pseudo-second order and intra-particle diffusion were used. In addition, equilibrium data was fitted on to Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models. Results: Results showed that the adsorption of the Methylene Blue was enhanced with increasing initial dye concentration, pH and contact time. The optimum pH was 10. The q max for adsorption of methylene blue dye from the Langmuir model was 15.87 mg/g. Considering the values of R 2 (0.999) and χ 2 , Freundlich isotherm model and pseudo-second order kinetic model had the best fitness. Conclusions:This study has demonstrated that the modified Pumice stone with HCl can be employed as effective and inexpensive adsorbent for the removal of Methylene Blue from aqueous environments.

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 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⁻¹ nano-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. © 2013 Balaban Desalination Publications. All rights reserved

BackgroundExtensive human activities and unplanned land uses have put groundwater resources of Shiraz plain at a high risk of nitrate pollution, causing several environmental and human health issues. To address these issues, water resources managers utilize groundwater vulnerability assessment and determination of protection. This study aimed to prepare the vulnerability maps of Shiraz aquifer by using Composite DRASTIC index, Nitrate Vulnerability index, and artificial neural network and also to compare their efficiency.MethodsThe parameters of the indexes that were employed in this study are: depth to water table, net recharge, aquifer media, soil media, topography, impact of the vadose zone, hydraulic conductivity, and land use. These parameters were rated, weighted, and integrated using GIS, and then, used to develop the risk maps of Shiraz aquifer.ResultsThe results indicated that the southeastern part of the aquifer was at the highest potential risk. Given the distribution of groundwater nitrate concentrations from the wells in the underlying aquifer, the artificial neural network model offered greater accuracy compared to the other two indexes. The study concluded that the artificial neural network model is an effective model to improve the DRASTIC index and provides a confident estimate of the pollution risk.ConclusionsAs intensive agricultural activities are the dominant land use and water table is shallow in the vulnerable zones, optimized irrigation techniques and a lower rate of fertilizers are suggested. The findings of our study could be used as a scientific basis in future for sustainable groundwater management in Shiraz plain.

Atrazine is widely used in the agriculture as an herbicide. Due to its high mobility, Atrazine leaks into the groundwaters, surface waters, and drinking water wells. Many physical and chemical methods have been suggested for removing Atrazine from aquatic environments. However, these methods are very costly, have many performance problems, produce a lot of toxic intermediates which are very harmful and dangerous, and cannot completely mineralize Atrazine. In this study, biodegradation of Atrazine by microbial consortium was evaluated in the aquatic environment. In order to assess the Atrazine removal from the aquatic environment, submerged biological aerated filter (SBAF) was fed with synthetic wastewater based on sucrose and Atrazine at different hydraulic retention times (HRTs). The maximum efficiencies for Atrazine and Soluble Chemical Oxygen Demand (SCOD) removal were 97.9% and 98.9%, respectively. The study findings showed that Stover-Kincannon model had very good fitness (R2 > 99%) in loading Atrazine in the biofilter and by increasing the initial concentration of Atrazine, the removal efficiency increased. Aerobic mixed biofilm culture was observed to be suitable for the treatment of Atrazine from aquatic environment. There was no significant inhibition effect on mixed aerobic microbial consortia. Atrazine degradation depended on the strength of wastewater and the amount of Atrazine in the influent.

People's attitudes are a key issue in the use of reclaimed wastewater. Unfortunately, there is not enough research on the use of reclaimed wastewater in developing countries such as Iran. The present study aimed to investigate public acceptance and citizens' attitudes toward reclaimed wastewater in Shiraz, Iran. A two-part questionnaire, designed to collect demographic data and information about people's willingness to reuse wastewater, was distributed among 562 citizens of Shiraz. The results showed that most respondents knew nothing about the chemical quality (67.4%) or microbiological quality (81.5%) of the wastewater treatment plant effluent. The maximum acceptance of treated wastewater use was related to public consumption (87%), car washing (85%) and flush tank (80%), respectively. The minimum acceptance was related to cooking and drinking (8%). Also, a significant correlation was observed between citizens' willingness to use reclaimed wastewater and variables such as level of education, gender, awareness of wastewater treatment process and awareness of quality of reclaimed wastewater. Shiraz citizens, like other people in the world, were less willing to use reclaimed wastewater for cooking, drinking, laundry and bathing, but their willingness was obviously greater in applications with less skin contact.