Evaluation of water quality of Chahnimeh as natural reservoirs from Sistan region in southwestern Iran: a Monte Carlo simulation and Sobol sensitivity assessment.

Maintaining the water quality is essential because of the limitation of drinking water bodies and their significant effects on life. Recently, much scientific interest has been attracted to the ecological condition assessment of water resources. Because of numerous health issues connected to water quality, the present work aimed to define the water quality status of Chahnimeh reservoirs, Sistan and Baluchistan province, Iran via the Iran Water Quality Index (IRWQISC), the National Sanitation Foundation Water Quality Index (NSFWQI), and human risk assessment. This cross-sectional descriptive work was accomplished in 4 seasons in 2020. The samples were gathered from 5 various points of Chahnimeh reservoirs. This study led to the results that the NSFWQI index was between 29.4 to 49.32, which showed "bad" quality, and the IRWQI index was between 19.27 and 39.23, which indicated "bad" and "relatively bad" quality. The best water quality based on both indexes was observed in the spring, and the worst was in the fall and summer. The highest value of HQ related to nitrate in drinking water was 1.60 in the group of children. However, according to the Monte Carlo simulation, HQ95% was estimated as 1.29. The Sobol sensitivity analysis of the first-order effect showed that daily water's daily ingestion rate (IR) was the most sensitive input. In addition, the value of the second-order effect indicated that the interaction effect of concentration-ingestion rate was the most sensitive input parameter for HQ. Therefore, regular monitoring is necessary to ensure water safety for human consumption.

Activated carbon derived from Azolla filiculoides fern: a high-adsorption-capacity adsorbent for residual ampicillin in pharmaceutical wastewater.

In this study, the effectiveness of activated carbon prepared from the Azolla filiculoides fern (ACAF) in order to remove ampicillin from aqueous solution was examined. The preparation of the ACAF was performed through chemical and physical activation processes with the presence of ZnCl2 and at a temperature of 450 °C. The ACAF yield was 44.7% of the fresh Azolla filiculoides. The results obtained from the characterization study indicate that the prepared ACAF has excellent surface and internal properties to be used as an adsorbent. The surface area, porosity, and pore volume were estimated to be 716.4 m2/g, 51.2%, and 0.621 cm3/g, respectively. The functional groups in ACAF that were responsible for the adsorption of ampicillin molecules were detected using FTIR analyses. The maximum efficiency (96.84%) and uptake (114.3 mg/g) of ACAF to remove ampicillin were achieved under the following conditions: ACAF dose = 0.8 g/L, pH = 7, concentration of ampicillin = 100 mg/L, contact time = 60 min, and temperature = 45 °C. It was found that the kinetic and isotherm data matched the pseudo-second-order and Langmuir models with high precision values, respectively. Considering the thermodynamics of the adsorption, the endothermic and spontaneous nature of the ampicillin adsorption onto ACAF was approved. The ampicillin adsorption capacity by ACAF was not significantly affected by the presence of different concentrations of NaNO3 competitor ion. The considerably higher adsorption capacity of the ACAF for ampicillin (114.3 mg/g) than other previously used adsorbents with excellent regeneration level (five cycles) depicts the superior performance of ACAF in the adsorption systems. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13399-021-01962-4.