Environmental Engineering
M. Samimi
Abstract
BACKGROUND AND OBJECTIVES: Industrial wastewater usually contains metal ions which are hazardous to human and aquatic organisms. Nowadays, the application of inexpensive biomaterials in adsorptive removal of metal ions, such as plant biomass, has been widely considered. In this study, the efficiency ...
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BACKGROUND AND OBJECTIVES: Industrial wastewater usually contains metal ions which are hazardous to human and aquatic organisms. Nowadays, the application of inexpensive biomaterials in adsorptive removal of metal ions, such as plant biomass, has been widely considered. In this study, the efficiency of Eucalyptus globulus fruit biomass for biological adsorption of cadmium ions from aquatic environments has been evaluated.METHODS: After drying, the collected biosorbent was ground and powdered. The dried biomass, after screening with particle size of less than 45 micrometers, was used in all experiments. The effects of operating factors, such as biosorbent to cadmium ratio, pH value of the solution and residence time of biomass and metal, on the amount of analyte adsorption were evaluated by response surface methodology. The optimum conditions for maximum metal uptake by Eucalyptus globulus fruit biomass were also evaluated using the Box-Behnken Design model. Kinetic studies were statistically described to investigate the metal adsorption process.FINDINGS: Validation experiments showed the accuracy of the model proposed for determining the optimum conditions for the cadmium biosorption process. Based on the experimental data, the values of coefficient of determination, adjusted coefficient and predicted coefficient used in the model were determined as 0.9948, 0.9855 and 0.9245, respectively. Using the model, the maximum cadmium ion adsorption by biomass was obtained at 93.65 percent, biosorbent-to-metal ratio of 9:1, pH value of 6, and contact time of 80 minutes.CONCLUSION: In the present study, the Eucalyptus globulus fruit biomass, under optimal operating conditions, proved to be an efficient sorbent for cadmium uptake from aqueous environments. The results from the experimental data of the adsorption studies were consistent with pseudo-second-order kinetics (maximum capacity of 128.2 milligram per gram), indicating that the chemical adsorption of cadmium on the used biomass occurring in monolayers.
Environmental Science
M. Samimi; M. Shahriari Moghadam
Abstract
phenol and phenolic compounds are among the most recognized environmental pollutants which exist in industrial wastewater and enter the biological cycles due to the solubility in water. Bioremediation is one of the cost-effective and Eco-friendly methods for phenol removal. In this study, the most effective ...
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phenol and phenolic compounds are among the most recognized environmental pollutants which exist in industrial wastewater and enter the biological cycles due to the solubility in water. Bioremediation is one of the cost-effective and Eco-friendly methods for phenol removal. In this study, the most effective phenol-degrading bacterial strain was isolated and identified from the shores of the Oman Sea by 16S rDNA. The optimal conditions of various factors, such as pH, temperature, carbon to nitrogen ratio and salinity for the phenol biodegradation, were determined using the experimental design based on Taguchi method with L9 array (34). Ability of the isolated strain (Halomonas elongata strain O-CH1) in degradation of different phenol concentrations was analyzed. The optimum operating conditions for phenol removal were determined in pH value of 8, temperature of 35 ˚C, carbon to nitrogen ratio of 100:30 (g/L) and salinity of 35 (g/L). In these conditions, 97% of the phenol was removed from the mediums. According to the optimization results, salinity and pH were the most influential factors in the biodegradation of phenol. The O-CH1 was able to grow and degrade phenol at concentrations of 250 mg/L to 1500 mg/L. Considering the high potential of this strain for phenol degradation, determining the optimal conditions for the biodegradation and its efficacy at high concentrations of phenol, the findings in this study can be used in the biological treatment of phenolic wastewater.
M. Samimi; M. Shahriari Moghadam
Abstract
High concentrations of nitrogen compounds, such as ammonia observed in the petrochemical industry, are the major environmental pollutants. Therefore, effective and inexpensive methods are needed for its treatment. Biological treatment of various pollutants is a low cost and biocompatible replacement ...
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High concentrations of nitrogen compounds, such as ammonia observed in the petrochemical industry, are the major environmental pollutants. Therefore, effective and inexpensive methods are needed for its treatment. Biological treatment of various pollutants is a low cost and biocompatible replacement for current physico-chemical systems. The use of aquatic plants is an effective way to absorb the nutrient pollutants. In this study, the optimal operating conditions in the biological removal of ammonia from the urea-ammonia wastewater of Kermanshah Petrochemical Company by Lemna gibba were determined using the response surface methodology. Lemna gibba was collected from the ponds around Kermanshah and maintained in a nutrient medium. Effect of the main operational variables such as ammonia concentration, residence time and Lemna gibba to surface ratio on optimal conditions of ammonia removal from wastewater has been analyzed using the Box-Behnken model design of experiments. Model numerical optimization was performed to achieve the maximum amount of ammonia removal from wastewater. The ammonia removal percentage varied from 13% to 88%, but the maximum amount of ammonia removal was determined at ammonia concentration of 5 ppm and Lemna gibba residence time of 11 days in wastewater based on the quadratic model. Lemna gibba to surface ratio of 2:5 was measured at 96.449%. After optimization, validation of ammonia removal was performed under optimum conditions and measured at 92.07%. Based on the experimental design and the predicted under model conditions, the maximum amounts of ammonia removal percentage in the experiments were 82.84% and 88.33% respectively, indicating the high accuracy of the model to determine the optimum conditions for the ammonia removal from wastewater.
