جستجوی مقالات مرتبط با کلیدواژه « پساب شهری » در نشریات گروه « مهندسی آب »

Municipal wastewater treatment and algal biomass production are simultaneously new and efficient methods in the treatment industry. Using artificial culture medium, urban wastewater is used as a food source for microalgae. Cultivation of microalgae in wastewater is an important step in wastewater treatment that, in addition to wastewater treatment, simultaneous production of biomass is done which can be used for many purposes and is of great value. in the present study, the effect of initial pH on the performance of membrane photobioreactor in biomass growth and nutrient removal from municipal wastewater was investigated. In this study, first Chlorella vulgaris microalgae in a membrane optical bioreactor with a light intensity of 300 μmol photons m-2. s-1 in the 24-hour light cycle and an initial concentration of 1 g/L dry weight of microalgae in the initial three pH (4, 7 and 10) were cultivated. Then, due to the direct relationship between microalgae growth and nutrient removal, the best initial pH in nitrate and phosphate removal from municipal wastewater was investigated. According to the results, microalgae were adapted to municipal effluent after 9 days and at the initial pH of 7, the highest growth rate of microalgae equal to 2.37 g dry weight per liter, and removal of nitrate and phosphate were 88 and 87%, respectively. Also, on the 15th day at the same initial pH, the highest amount of nitrate and phosphate removal from municipal effluent was 92% and 91%, respectively. The results show that the regulation of the initial pH of microalgae can have an undeniable effect on the growth of microalgae. It also has a significant effect on the removal of nitrate and phosphate from municipal wastewater through the cultivation of microalgae. By optimizing the initial pH, this removal percentage has increased.

Due to the water shortage crisis, the reuse of municipal wastewater is essential. Planting plants in the wastewater treatment process is appropriate and can help to reduce and eliminate pollution in urban and rural wastewater. This study aimed to determine the phytoremediation of lead and nickel from Ahwaz wastewater treatment plant. In this study, a completely randomized design with 4 treatments and 3 replications was used, and the laboratory activities were performed in the soil laboratory of Islamic Azad University, Ahvaz Branch. Heavy metals were measured by atomic absorption method and PG Instruments Ltd. The average amount of lead and nickel in the effluent of Ahvaz was 96.35 and 102.57 μg/kg. The amount of lead metal in the studied treatments was 17.85-96.86 ppb, and nickel content was 18.91- 102.87 ppb. In this study, the percentage of the Lewis plant's removal of lead and nickel was 62.66% and 70.18%, respectively. Also, the removal efficiency of the studied parameters by the seven herbaceous plants was 29.26% and 44.22%, respectively. The amount of nickel adsorbed by plants was higher than that of lead metal. The removal efficiency of lead and nickel metals from municipal effluent obtained by Typha Latifolica was higher than Polygonum aviculare. In total, Typha Latifolica and Polygonum aviculare plants had the ability to purify lead and nickel metals from urban effluents so that the amounts of these metals were reduced in the second and fourth treatments within 90 days.

Urban treated wastewater is a useful resource for allocation to various non-potable reuses because its quantity and quality can be controlled and managed by humans, but it has its limitations. Improper use of these resources without treatment can lead to environmental and health risks and, as a result, can cause social dissatisfaction and sometimes economic problems. This paper examines the risks of limitations associated with the use of treated wastewater. Qualitative information of 26 wastewater treatment plants in the country was collected to create a proper database for risk assessment of using treated wastewater for agricultural and industrial application by taking into account the major factors such as environmental, socio-cultural, economic, and technical. For risks calculation, multiple risks associated with the use of treated wastewater were identified by reviewing various available publications and categorizing them according to the above four risk factors. Hierarchical networks were prepared to calculate the main and the overall risk. Bayesian networks were used to model risk-based structures. Bayesian relationships are causal and helpful in expressing the links of the nodes in a probabilistic way. Research results show that the risk of using treated urban wastewater in agricultural sector is generally higher than its application in industrial use, and hence it will make it more suitable and more acceptable for industrial use under current treatment. Bayesian risk-based agricultural and industrial structures were suitably modeled according to R2, RMSE, and MAPE indicators. The average values of the above indicators for the calibration of Bayesian model using treated wastewater in agricultural and industrial risked-based structure were 0.993, 0.202 and 0.637; 0.988, 0.980 and 2.731, respectively. From this study it can be concluded that Bayesian networks have a modeling capability in assessing the risk associated with the use of treated wastewater in agricultural and industrial sectors. The method presented in this paper can be used by the wastewater treatment plant managers and end users when assessing the potential risk of using treated effluent for agricultural and industrial applications.

Municipal and industrial effluents continually release into the environment heavy metals of a variety of physical and chemical forms and at various concentrations. Biological treatment processes have attracted a growing attention for the removal of heavy metals from these effluents. For the purposes of the present study, bacteria that are relatively resistant to heavy metals, such as cadmium and lead, were isolated from municipal waste and purified. They were then subjected to biochemical tests for identification and their minimum inhibitory concentrations were determined. Bacterial minimum inhibitory concentrations were initially measured in flasks containing 25, 50, 75, 100, 150, 300, 500, and 700 ppm of lead and cadmium before superior bacteria at populations of 108 CFU/ml were evaluated in terms of their ability to remove lead and cadmium at concentrations of 50, 100, 150, and 300 ppm from enriched municipal wastewater. Base on the results, Bacillus laterosporous and Yersinia pseudotuberculosis were identified as the resistant bacteria and the minimum lead and cadmium inhibitory concentrations for these bacteria were determined to be 300 and 500 ppm, respectively. Moreover, Bacillus laterosporous and Yersinia pseudotuberculosis recorded maximum removal efficiencies of around 50.6% and 45.7%, respectively, with wastewater containing 100 mg/l of lead and 36.18% and 21.41% in the case of cadmium from wastewater enriched with 100 mg/l of lead and 150 mg/l of cadmium.