The potential of the raw cuttlebone nano-powder (CBNP), a biomass waste, as a novel and nontoxic adsorbent for the adsorption of Alizarin Red S (ARS) from water solutions was investigated. To achieve the highest efficiency for the removal of ARS, some affecting factors were optimized. Common techniques (FTIR, FESEM, EDX and XRF) were used to characterize the physicochemical features of the adsorbent. Various kinetic and isotherm models were used to obtain the useful information about the adsorption mechanism of the dye onto the adsorbent. The maximum dye removal efficiency was obtained with the adsorbent amount of 500 mg (in 50 mL) and initial pH of 2 in 10 min for 20 mg/L ARS solution. Under these optimum conditions the complete removal of ARS was obtained while the maximum adsorption capacity was 38.51 mg/g. The well fitness of pseudo-second order kinetic model in the adsorption process was proved by kinetic studies. According to the obtained results, Freundlich isotherm model can suitably describe the adsorption of ARS on the sorbent. The achieved results from this study showed the excellent capability of CBNP for the adsorption of ARS.

Heavy metal and antibiotic co-resistance is a global issue. The goal of this research was to explore the heavy metal, also antibiotic resistance patterns of effluent bacterial isolates. Heavy metal resistant bacteria were isolated from effluents and their Minimum Inhibitory Concentration (MIC) was determined. The Multi-Metal resistance (MMR) pattern and antibiotic resistance trait of isolates were defined. The MIC of Cu2+, Pb2+, Cd2+ and Zn2+ was 4, 8, 12 and 24 mM/L, respectively. Most of the isolates indicated the Cd2+, Pb2+ and Zn2+ resistance and high resistance to the most tested antibiotics. The 16S rDNA gene sequences of resistant isolates were handed over to NCBI-GenBank as Staphylococcus sp. ATHA2(JX120151) and Klebsiella oxytoca ATHA1(JQ928574). Correlation was found between metal tolerances, heavy metal concentration, also antibiotic resistance in bacteria. Thus, it is important to not only be aware of antibiotics misapplication, but also respond to excessive discharge of effluent containing heavy metals to the environment.

Water is one of the basic needs of individuals and communities. In a way, without it, the growth and sustainability of societies is not possible. In recent decades, due to the effects of climate change and human activities, many parts of the world have faced water-related crises. Hence, this issue has jeopardized the sustainability of villages, especially in developing countries. Therefore, the purpose of this study is to quantify drinking water security in rural areas of Iran during the years 2013-2019. For this purpose, this paper has developed a rural water security assessment framework with four dimensions and ten indicators. The scale of the rural water security index is between 1 and 5. Based on findings, three dimensions: “availability”, “accessibility” and “water health and sanitation”, all show an upward trend, reflecting an overall improvement of water-related infrastructure in rural areas. Whereas the “economic value of water” dimension depicts a steady trend. Also, for the period of 2013-2019, the results show the improvement of rural drinking water security in Iran.

The need for water reuse application in Mashhad which is the second largest city of Iran has been recognized in recent years. This need has forced local authorities to pursue upgrading the existing or installing the more advanced wastewater treatment plants for potential water reuse applications. However, the selection of suitable wastewater treatment train technologies is complex and may require a user-friendly tool to facilitate decision-making process for authorities, which is the focus of this paper. To advance the main focus of the study, this paper is prepared to develop and simulate various treatment train technologies based on multiple criteria analysis considering technical, social, economic, and environmental issues. The treatment technologies considered for simulations in this study include Moving Bed Bio Reactor, Integrated Fixed Film Activated Sludge, Sequencing Batch Reactor, Anaerobic/Anoxic/Oxic, and Modified Ludzack-Ettinger. At first, multiple simulations were performed and then a multi-criteria analysis was performed in order to select the most appropriate treatment technology. As part of this study, additional simulations were performed with respect to different sludge management alternatives including the utilization of energy produced from biogas. The overall results showed that A2/O treatment technology is the most suitable treatment for producing a highly reliable effluent quality for sustainable use of water reuse. With additional local data collection, the methods and the preliminary simulations performed in this study can further be improved to enhance the current decision-making tool for possible future practical use in Mashhad and other cities in Iran.

In recent years, old urban sewage networks have encountered numerous flaws, leading to several important problems in the environment, such as groundwater pollution, excessive growth of tree roots inside sewer pipes, etc. To tackle such problems, innovative approaches must be practiced in urban sewage networks operations. To this aim, a spatial model based on "predictive analysis" and smart technology in the sewage network operation management is needed. Our proposed model was firstly applied for the city of Isfahan to evaluate and predict possible accidents in the urban sewage network. Our model is based on DRASTIC model and Geographic information system. The sewage accidents were assessed by combining the results of DRASTIC model and Getis-Ord Gi* index. This model could assess the previous sewage accidents and predict the probability of future accidents in cities, as well as their environmental risks. In this study, the intention was to identify the hot spots of accidents in the sewage network using GIS; then by studying the factors affecting the accidents, and geological and environmental parameters, a spatial model was designed. Combination of the Getis-Ord Gi* index and DRASTIC model is the main innovation of this research. In the study area, the following items were determined as the most important factors in the sewage accidents: 1- soil type, 2-inappropriate infrastructure, 3-inappropriate pipes with older age, 4-lower diameter. Finally, this model showed that there was a significant relationship between spatial and environmental indices in the study area. Also, the significance value obtained from the statistical analysis of the relationship between pipe diameters and sewer network accidents was equal to 0.004 and the significance value obtained from the statistical analysis of the relationship between pipe life and such events based on Kendall and Spearman tests were calculated as 0.05 and 0.37, respectively.

There is an urgent need for the removal of arsenic (As) from groundwater and wastewater as it is a very hazardous heavy metal for human and environmental health. In this research, As-resistant and oxidizing bacteria were isolated from the Maharloo Lake (27 km southeast of Shiraz city) and identified to a great extent. Three isolated bacillus-shaped strains (called F5, F6 and F7) tolerated up to 1 M AsNaO2, grew up to 3.5 M NaCl and pH 12, and consumed NaSCN and Na2S2O3. The molecular analysis confirmed the originality of the strains to a high extent. The As absorption rate by these bacteria was measured by the atomic absorption method, and their effect was examined on a water sample from the south of Kerman city (Iran) and a synthetic wastewater sample with a chemical oxygen demand (COD) of about 180,000 kg/m3 that was able to absorb high levels of arsenic.