WATER AND WASTEWATER
Year:2016 | Volume:27 | Issue:1 (101)|Papers Count:12

Since a major portion of the food we use is provided by corps irrigated with water that is supplied from groundwater resources, remediation of contaminated groundwater using in-situ methods like permeable reactive barriers (PRBs) seems to be a top priority. Given the need to reduce Cd contamination in southern Tehran, the present study was designed to compare the rate of Cd absorption by nZVI with that by Zeolite and Calcite. The results of the study revealed a higher Cd adsorption by nZVI as compared to that by Calcite and Zeolite. Also, when nZVI concentration was raised from 1 to 2 g/l, enhancements were observed after two hours in Cd adsorption by up to 5.5%, 3.4%, and 11.5% in solutions containing 0.2, 0.5, and 4 ppm of Cd, respectively.Moreover, for a contact time of 24 hours and when the initial concentration of the contaminant was raised from 0.2 to 0.5 ppm, the adsorption rate declined to 5.45% and 7.75% for nZVI injections of 1 and 2 g/l, respectively. In a second part of the study, such environmental conditions as changes in pH and temperature were investigated for their effects on Cd adsorption. Compared to the initial concentration of 4 ppm, Cd adsorption reduced by 37.15% under acidic conditions (pH=3.7) and by 92.75% under alkaline conditions (pH=13.1) after a contact time of 3 hours. Similarly, a reduction equal to 38.5% was observed in Cd adsorption after 6 hours when temperature was raised from 20oC to 75oC. In order to explore the bioenvironmental impacts of injecting nanoparticles aimed at adsorption and precipitation of Cd, the concentration of iron nanoparticles present in the environment was measured. As a result of the reaction between the solutions containing 0.5 ppm of Cd with the absorbent solution containing 2 g/l iron, the iron nanoparticle concentration in the solution was observed to decline to 0.0041% of its initial concentration after 24 hours. In the experiments conducted in a vertical saturated porous and homogeneous medium, injection of 3 g/l of nZVI, as the absorbent, into water containing 2.92 ppm of the contaminant reduced the contaminant concentration to levels below the limits recommended for drinking water. The reaction between nZVI and Cd dissolved in the medium revealed that the nanoparticles served as an efficient absorbent as they not only adsorbed Cd over time, but also removed it from the medium through precipitation.

Increasing nutrients such as nitrates and phosphates in water resources lead to the growth of various algal species, causing undesirable odors and taste in the water. This study investigated the identification and removal of harmful algal growths by Zinc oxide nanoparticles (using Ardabil Yamichi Dam reservoir as a case study). Samples were initially collected from the Yamichi Dam reservoir and the algae in the water samples were cultivated. Enough time was allowed for the algae to grow before they were identified under the microscope. The results showed that most of the algal species grown in the culture medium belonged to the species Cladophora and Euglena. Zinc oxide nanoparticles were then synthesized to be used in the removal and/or inhibition of algal growths. ZnO nanoparticles were subsequently characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) methods which revealed that the size of the ZnO nanoparticles was in the range of 10@30 nanometers and further that the nanoparticles were pure and of a hexagonal phase. In continuation, the capability of ZnO nanoparticles with concentrations in the range of 0-3 ppm to inhibit algal growth was investigated. Results showed that no reduction was observed in algal growth for Zinc oxide nanoparticle concentrations below 1 mg/lit. At concentrations between 1 to 2 mg/lit, however, a significant reduction was observed in algal growth. Finally, it was found that algal growths completely stopped at ZnO concentrations beyond 2 mg/lit.

Many organic dyes such as Methylene Blue are toxic, carcinogenic, and non-biodegradable due to their aromatic complex structure and high solubility in water. It is, therefore, essential to remove them from effluents discharged into the environment. In this study, SBA-15 mesoporous silica was synthesized by the hydrothermal method and later functionalized with mono- amine (NH2-SBA-15) and dendrimer amine (MDA-SBA-15). Then, the effect of surface modification on adsorption efficiency of Methylene Blue was examined in a batch system. The prepared materials were characterized by XRD, FT-IR, SEM, and BET analyses. The results showed that, under identical conditions, removal efficiency with MDA-SBA-15 was 2.6 and 3.3 times higher than those achieved with NH2-SBA-15 and SBA-15, respectively. Equilibrium isotherms were analyzed by Langmuir, Freundlich, Tempkin, and Dubnin–Radushkevich isotherms. Equilibrium data was best described by the Langmuir isotherm models, indicating a monolayer adsorption process. Tempkin isotherm parameters indicated that the adsorption process by MDA-SBA-15 was exothermic. The removal efficiency of Methylene Blue from aqueous solutions by MDA-SBA-15 was more than 90%, which was higher than the efficiency achieved by other nano-sorbents. This showed that MDA-SBA-15 could be used as an effective adsorbent in wastewater treatment.

In this study, bimetallic iron–nickel nanoparticles were obtained by chemical co-deposition of iron chloride with sodium boron hydride used as a strong reducing agent. The bimetallic nanoparticles thus obtained were then used to remove acid red 14 in a slurry system.Experiments were conducted to investigate such parameters as initial dye concentration, nano-particle dosage, pH, the time required for the nano-particles to be used after they are formed, the stirring speed, and the temperature required to reach optimum reaction conditions.Control experiments were subsequently performed under the optimum conditions thus determined to identify any other remaining factors involved. The optimum conditions included a temperature of 25±2oC, a newly synthesized nano-particle concentration of 0.05 g/L, an initial dye concentration of 200 mg/L, a pH level of 7.5, and a mixing duration of two minutes. The results indicated the high activity of the nanoparticles such that removal efficiencies equal to 79.39, 90.52, and 94.42 percent were achieved after 2, 30, and 240 minutes, respectively. Moreover, a COD removal of 72.61 percent was achieved after 4 hours of reaction.

A newly emerging environmental problem is the discharge of pharmaceutical effluents containing antibiotic compounds. Compared to common methods, the ozone/persulfate process is a novel measure for treating persistent pollutants. This process is highly efficient in removing pollutants by using the free radicals of sulfates as powerful oxidants. In this study, a semi-continuous reactor with a useful volume of 1 L was used to evaluate the performance of the ozone/persulfate process in treating the ciprofloxacin antibiotic at concentrations from 10 to 100 mg/L in the presence of 0 to 15 mM of persulfate in 30 min. The results showed that under the optimized operating conditions of pH=3, persulfate dose=10 mM, ozone dose=1 g/h, and an initial antibiotic concentration of 10 mg/L, this method was capable of removing 96% of the contaminant. Moreover, the efficiency of the process was found to be a function of experimental conditions. Based on the results of this study, it may be concluded that the ozone/persulfate process can be considered as an appropriate process for treating persistent and non-biodegradable pollutants.

Phenol and phenolic compounds are highly toxic substances that are found as monoaromatic compounds in various industrial effluents from oil refineries, petrochemical plants, (coal) mines, and phenol resin plants. Their discharge into the environment, especially in water resources, causes serious toxicity. Traditionally, physicochemical methods have been used for the removal of phenol and phenolic compounds. Nowadays, bioremediation is known to be the best method for phenol removal from wastewater. The objective of the present study was twofold: isolation and identification of phenol degrading bacteria in the effluent from Golgohar Mine in Sirjan. For this purpose, samples were collected from different sections at Golgohar Mine and its effluent. Phenol degrading bacteria were isolated via enrichment of the samples in the Bushnell Hass medium with phenol used as the only source of carbon and energy. The predominant phenol degrader bacteria were selected by measuring turbidity at 600 nm. The bacteria were subsequently identified by amplification of 16S rRNA withspecific primers and PCR sequencing. In this study, 17 strains of phenol degrader bacteria were isolated in soil and wastewater samples collected from different zones of the mine.Screening methods confirmed that 4 strains exhibit a better capability for phenol degradation as evidenced by their capability to degrade 0.4 g/l of phenol. Molecular identification showed that these bacteria belong to the species Pesudomonas sp, Nitrratireductor sp., and Salegentibacter sp. The results also show that the effluent from Golgohar Mine in Sirjan contains many phenol degrading bacteria. The use of these bacteria in the treatment process may lead to a significant reduction in phenol pollution in the mineral effluent.

Hospital effluent is one type of urban wastewater that, due to its special source, may contain different pathogens and microorganisms, various intestinal disease agents, bacteria, viruses, sycophants, and toxic substances present in hospital wastewater latex including heavy metals. In this study, efforts have been made to evaluate the absorption of Cd, Zn, Cu, Ni, Fe, and Pb present in hospital wastewater by phytoremidiation. For the purposes of this study, the vetiver grass was cultivated in 8 treatments with 4 replications based on a completely randomized design and irrigated for 75 days with various combinations of normal water and hospital wastewater. Results showed that more of the Pb, Cu, Zn, Fe, and Ni (9.243, 2.313, 2.3188, 2625.3, and 27.638 mg of dry matter, respectively) was absorbed and collected in the root while Cd (3.45 mg of dry matter) accumulated in the soil, and only trace amounts of heavy metals accumulated in the branches and leaves. The reason for the greater accumulation of Pb, Cu, Ni, and Zn in the root rather than in the aerial parts is the high tolerance of the vetiver grass to high heavy metal concentrations in soil. Based on the results of this study, the use of vetiver may be recommended for the removal of contaminants in hospital effluents.

In this research, the capability of a charged system search algorithm (CSS) in handling water management optimization problems is investigated. First, two complex mathematical problems are solved by CSS and the results are compared with those obtained from other metaheuristic algorithms. In the last step, the optimization model developed by the CSS algorithm is applied to the waste load allocation in rivers based on the total maximum daily load (TMDL) concept. The results are presented in Tables and Figures for easy comparison. The study indicates the superiority of the CSS algorithm in terms of its speed and performance over the other metaheuristic algorithms while its precision in water management optimization problems is verified.

Landscape indices can be used as an approach for predicting water quality changes to monitor non-point source pollution. In the present study, the data collected over the period from 2012 to 2013 from 81 water quality stations along the rivers flowing in Mazandaran Province were analyzed. Upstream boundries were drawn and landscape metrics were extracted for each of the sub-watersheds at class and landscape levels. Principal component analysis was used to single out the relevant water quality parameters and forward linear regression was employed to determine the optimal metrics for the description of each parameter. The first five components were able to describe 96.61% of the variation in water quality in Mazandaran Province.Adaptive Neuro-fuzzy Inference System (ANFIS) and multiple linear regression were used to model the relationship between landscape metrics and water quality parameters. The results indicate that multiple regression was able to predict SAR, TDS, pH, NO3-, and PO43- in the test step, with R2 values equal to 0.81, 0.56, 0.73, 0.44. and 0.63, respectively. The corresponding R2 value of ANFIS in the test step were 0.82, 0.79, 0.82, 0.31, and 0.36, respectively. Clearly, ANFIS exhibited a better performance in each case than did the linear regression model. This indicates a nonlinear relationship between the water quality parameters and landscape metrics.Since different land cover/uses have considerable impacts on both the outflow water quality and the available and dissolved pollutants in rivers, the method can be reasonably used for regional planning and environmental impact assessment in development projects in the region.

This Study explores the influence of CaCO3 sedimentation in the Qanat system of Esfezar area in Southern Khorasan Province. Experiments were conducted to evaluate the decrease in transient water hardness in the drinking water supply network in the areas neighboring the Esferaz Qanat. The significance of the study lies in the fact that the Qanat under study is the only source of drinking water in the region. For the purposes of this study, experiments were carried out using a reservoir in which water pH was increased by adding lime to form sediments. Chemical coagulants were also added to accelerate the sedimentation process. From among the coagulants of FeSO4, Fe2 (SO4) 3, and CuSO4 used, optimizations revlead that Fe2 (SO4) 3 yielded the best results at pH=9.5 in drinking water given the quality parameters of EC: 440dS and pH=7.7. Dimension analysis using the Reynolds Number was also conducted to simulate the qanat discharge, which was further calibrated against experimental results. The results obtained from the model showed that using a spiral pipe and Fe2 (SO4) 3 as the coagulant led to reduced transient hardness of water. The results also revealed that CaCO3 sedimentation reduced in the local water supply network.