Mohammad Mahdi Emamjomeh

Forward osmosis is a water separation process that uses the natural energy of osmotic pressure to separate water from dissolved solutes through a semipermeable membrane. One of the major challenges using this process is the rejection water which contains high content of pollutants, hindering its practical application. Herein, for the first time, this work introduces a coupled electrochemical-physical process including iron-electrocoagulation/filtration/sedimentation as a cost-effective treatment to the forward osmosis reject water containing hexavalent chromium to be reclaimed. The synergistic treatment was optimized through a central composite design and response surface methodology to enhance hexavalent Cr removal and minimize operating costs, electrical energy consumption, and settled sludge volume. A 90.0% chromium removal was achieved under optimized conditions: electrolysis time of 59.7 min and current of 1.24 A (J = 6.32 mA cm⁻²). In addition, operating costs of 0.014 USD m⁻³, electrical energy consumption of 0.005 kWh m⁻³, and settled sludge volume of 445 mL L⁻¹ were obtained. GRAPHICAL ABSTRACT

Considering the adverse effects of polycyclic aromatic hydrocarbons (PAHs) on human health and the complexity of their detection in water resources, this study was developed to assess the performance of a new automated device for the identification of PAHs in water based on the solid-phase extraction and to simulate the cancer risk of 16 priority PAHs by Monte Carlo technique. All operational modes of extraction were automatically performed using the proprietary software program. Three spiked aliquots of PAHs including 100, 500, and 1000 ng/L were used to evaluate the performance of the automated-solid phase extraction (SPE) apparatus. The time of extraction in the automatic-SPE apparatus was 50±4 minutes for simultaneous extraction of 4 water samples, which was four times faster than that of manual-SPE apparatus. The mean recoveries of PAHs were 89.22±4.94, 91.70±4.45, and 94.61±6.28% in spiked samples, with a mean of 91.84±5.22%. Except for naphthalene, all obtained recoveries were in an acceptable range (85-115%). The results of Monte Carlo simulation showed that the cancer risk attributable to eight detected PAHs including naphthalene, fluorene, phenanthrene (Phe), benzoanthracene, chrysene, benzo(k) fluoranthene, indeno(cd)pyrene, and dibenzo(a,h)anthracene ranged from 0.05E-6 to 0.11E-6, with the cancer risk of 0.012E-6 having the highest probability (P=0.82). Additionally, this simulation showed that 99% of the probability density of cancer risk was located within the range lower than 0.05E-6. Our results showed that the novel automated-SPE apparatus could be utilized for the extraction of PAHs from water resources with a good recovery (85%-115%), high operational speed, and potential for separation of solvents from the air in the drying step. Therefore, this device can be used for the extraction of trace PAHs and similar organic compounds from water resources.

Wastewater-based epidemiology (WBE) has a long history of identifying a variety of viruses from poliovirus to coronaviruses, including novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The presence and detection of SARS-CoV-2 in human feces and its passage into the water bodies are significant public health challenges. Hence, the hot issue of WBE of SARS-CoV-2 in the coronavirus respiratory disease (COVID-19) pandemic is a matter of utmost importance (e.g., SARS-CoV-1). The present review discusses the background, state of the art, actual status, and prospects of WBE, as well as the detection and quantification protocols of SARS-CoV-2 in wastewater. The SARS-CoV-2 detection studies have been performed in different water matrixes such as influent and effluent of wastewater treatment plants, suburban pumping stations, hospital wastewater, and sewer networks around the globe except for Antarctica. The findings revealed that all WBE studies were in accordance with clinical and epidemiological data, which correlates the presence of SARS-CoV-2 ribonucleic acid (RNA) with the number of new daily positive cases officially reported. This last was confirmed via Reverse Transcriptase-quantitative Polymerase Chain Reaction (RT-qPCR) testing which unfortunately is not suitable for real-time surveillance. In addition, WBE concept may act as a faster protocol to alert the public health authorities to take administrative orders (possible re-emerging infections) due to the impracticality of testing all citizens in a short time with limited diagnostic facilities. A comprehensive and integrated review covering all steps starting from sampling to molecular detection of SARS-CoV-2 in wastewater has been made to guide for the development well-defined and reliable protocols.

Electrocoagulation (EC) is one of the emerging technologies in groundwater and wastewater treatment as it combines the benefits of coagulation, sedimentation, flotation, and electrochemical oxidation processes. Extensive research efforts implementing EC technology have been executed over the last decade to treat chemical oxygen demand (COD)-rich industrial wastewaters with the aim to protect freshwater streams (e.g., rivers, lakes) from pollution. A comprehensive review of the available recent literature utilizing EC to treat wastewater with high COD levels is presented. In addition, recommendations are provided for future studies to improve the EC technology and broaden its range of application. This review paper introduces some technologies which are often adopted for industrial wastewater treatment. Then, the EC process is compared with those techniques as a treatment for COD-rich wastewater. The EC process is considered as the most privileged technology by different research groups owing to its ability to deal with abundant volumes of wastewater. After, the application of EC as a single and combined treatment for COD-rich wastewaters is thoroughly reviewed. Finally, this review attempts to highlight the potentials and limitations of EC. Related to the EC process in batch operation mode, the best operational conditions are found at 10 V and 60 min of voltage and reaction time, respectively. These last values guarantee high COD removal efficiencies of > 90%. This review also concludes that considerably large operation costs of the EC process appears to be the serious drawback and renders it as an unfeasible approach for handling of COD rich wastewaters. In the end, this review has attempted to highlights the potential and limitation of EC and suggests that vast notably research in the field of continuous flow EC system is essential to introduce this technology as a convincing wastewater technology.

Fluoride ions present in drinking water are beneficial to human health when at proper concentration levels (0.5–1.5 mg L⁻¹), but an excess intake of fluoride (>1.5 mg L⁻¹) may pose several health problems. In this context, reducing high fluoride concentrations in water is a major worldwide challenge. The World Health Organization has recommended setting a permissible limit of 1.5 mg L⁻¹. The application of electrocoagulation (EC) processes has received widespread and increasing attention as a promising treatment technology and a competitive treatment for fluoride control. EC technology has been favourably applied due to its economic effectiveness, environmental versatility, amenability of automation, and low sludge production. This review provides more detailed information on fluoride removal from water by the EC process, including operating parameters, removal mechanisms, energy consumption, and operating costs. Additionally, it also focuses attention on future trends related to improve defluoridation efficiency.

The outbreak of COVID-19 has made a global catastrophic situation that caused 1,039,406 deaths out of 35,347,404 infections, and it will also cause significant socio-economic losses with poverty increasing from 17.1 to 25.9%. Although the spreading rate of COVID-19 is very high on October 6, 2020, the death rate is still less than 2.94%. Nonetheless, this review article shows that the lockdown has induced numerous positive impacts on the environment and on energy consumption. For instance, the lockdown has decreased the electricity demand by 30% in Italy, India, Germany, and the USA, and by 12–20% in France, Germany, Spain, India, and the UK. Additionally, the expenditure of the fuel supply has been decreased by 4% in 2020 as compared to the previous years (2012–2019). In particular, The global demand for coal fuel has been reduced by 8% in March and April 2020 as compared to the same time in 2019. In terms of harmful emissions, the lockdowns reduced the emissions of nitrous oxides by 20–30% in China, Italy, France, Spain, and by 77.3% in São Paulo, Brazil. Similarly, the particulate matter level has been reduced from 5–15% in Western Europe, to 200% in New Delhi, India, which in turn has enhanced the air quality in a never-seen manner in recent times. In some places, such as New York, USA, CO₂ emission was also reduced by 5–10%. The water quality, in several polluted areas, has also been remarkably enhanced, for example, the dissolved oxygen content in the Ganga River, India, has increased by about 80%. Traffic congestion has also been reduced worldwide, and in some areas, it has been reduced by 50%, such as New York and Los Angeles, USA. Overall, while the COVID-19 pandemic has shrinked the global economy by 13–32%, the pandemic has also clearly benefited to other sectors, which must be considered as the spotlight for the permanent revival of the global ecosystem.

Background: Due to the complexity and interdependence of water resources, the evaluation of the efficiency of water resources management is difficult. So, it is necessary to use effective modeling methods to study and recognize the feedback loops available in water resources systems. Regarding the importance of domestic water for the ...