Study on diazinon toxicity reduction by electro-Fenton process: A bioassay using daphnia magna

The realm of diazinon reduction from polluted water has witnessed a surge in the significance of advanced oxidation processes (AOPs) in recent times. However, there is a dearth of research focusing on the mitigation of its toxicity through AOPs. Thus, the primary objective of this study was to evaluate the effectiveness of the Electro-Fenton process (EFP) in the eradication and detoxification of diazinon in aqueous solutions. Synthetic wastewater samples with concentrations of 2, 2.5 and 3 mg/L were prepared. A total of 27 samples were determined using Box Behnken Design. Reaction time, pH and iron to hydrogen peroxide ratio (Fe2+/H2O2) were examined as operational parameters under a constant current of 5.4 amps. The quantification of diazinon concentration was performed using High-Performance Liquid Chromatography (HPLC). To evaluate the detoxification of diazinon, the Daphnia magna bioassay was employed as a methodology in this study. According to the results, the EFP could reduce the diazinon to zero and the LC50 values are increased by applying the process. The LC50 values for diazinon were determined using the Daphnia magna bioassay, considering initial concentrations of 2, 2.5, and 3 mg/L at a pH of 5, a reaction time of 15 min, and an iron to hydrogen peroxide molar ratio of 2. The recorded LC50 values were 3.039, 3.076, and 3.106, respectively, indicating the lowest frequency of cumulative death in Daphnia magna. In this case, after 96 h, only 3 cases (30%) of Daphnia magna death were observed. However, for all the mentioned concentrations of diazinon, after 96 h of exposure to samples without applying the Daphnia Magna death process, it was observed between 60 and 100%. Reducing the diazinon concentration and increasing the 96-h LC50 showed that the EFP can reduce the toxicity of diazinon on Daphnia Magna at the same time. Therefore, EFP can be considered a superior method with low ecotoxicity.

Effect of salinity on the potential cadmium phytoremediation from the polluted soil by carpobrotus rossii

Nowadays, toxic metals accumulation in soil texture due to anthropogenic activities is a major form of pollution, which can lead to worldwide concerns; however, there are many treatment methods to remove them from soil such as phytoremediation. The carpobrotus rossii, has shown great potential to tolerate high salinity and accumulate Cd from contaminated soils. The experiments, in this study, are analyzed and optimized by Central Composite Design (CCD) as method and using Response Surface Methodology (RSM) package in R software. The Cd removal by root and the whole plant followed the quadratic model and the R² values were 94.95 and 94.81, respectively. The results showed that a decrease in NaCl concentration in Cd-containing solution can increase the phytoremediation process of Cd by carpobrotus rossii, significantly. The optimum conditions for 58% Cd removal by the whole plant, predicted through a CCD response surface methodology model were as follows: initial Cd concentration of 49 mgKg^-1,NaCl concentration of 16 dSm^-1, time of 17 days, and pH of 6.5. C. rossii's potential in removing 58% of Cd under the obtained optimum condition from the modelling was evaluated in real condition in the laboratory. The results revealed that around 56% of the initial added Cd concentration was removed by carpobrotus rossii. As a take home message, carpobrotus rossii can be recommended as an efficient plant to remove heavy metals especially cadmium from soil and sediments in arid area which have a salty soil.

Occurrence of enteric and non-enteric microorganisms in coastal waters impacted by anthropogenic activities: A multi-route QMRA for swimmers

The purpose of this study was to evaluate the microbial characteristics of coastal waters which are impacted by anthropogenic pollution as well as estimate the health risks associated with exposure to enteric and non-enteric microorganisms during swimming. Fecal indicator bacteria were highly detected in samples. Moreover, pathogenic and opportunistic microorganisms were found, with the highest frequency for Pseudomonas aeruginosa followed by Adenovirus 40/41, Acanthamoeba spp., Salmonella enterica, and Cryptosporidium parvum. The median risk of gastrointestinal illness through ingestion of water was estimated to be above the benchmark value of 0.05 per event recommended by WHO. Cryptosporidium followed by Adenovirus, showed higher illness risks than Salmonella. The potential risks of Acanthamoeba and P. aeruginosa were estimated to be low for both dermal and ocular exposure routes. However, there are uncertainties about the infectious fraction of pathogens existing in coastal waters and the delivered dose of microorganisms from dermal/ocular exposure during recreational activities.

Occurrence of viruses in sewage sludge: A systematic review

Enteric viruses are of great importance in wastewater due to their high excretion from infected individuals, low removal in wastewater treatment processes, long-time survival in the environment, and low infectious dose. Among the other viruses, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) surveillance in wastewater systems has received particular attention as a result of the current COVID-19 epidemic. Viruses adhering to solid particles in wastewater treatment processes will end up as sewage sludge, and therefore insufficient sludge treatment may result in viral particles dissemination into the environment. Here, we review data on viruses' presence in sewage sludge, their detection and concentration methods, and information on human health issues associated with sewage sludge land application. We used combinations of the following keywords in the Scopus, Web of Science (WOS), and PubMed databases, which were published between 2010 and January 21th, 2022: sludge (sewage sludge, biosolids, sewage solids, wastewater solids) and virus (enteric virus, viral particles, viral contamination, SARS-CoV-2, coronavirus). The sources were searched twice, once with and then without the common enteric virus names (adenovirus, rotavirus, norovirus, enterovirus, hepatitis A virus). Studies suggest adenovirus and norovirus as the most prevalent enteric viruses in sewage sludge. Indeed, other viruses include rotavirus, hepatitis A virus, and enterovirus were frequently found in sewage sludge samples. Untreated biological sludge and thickened sludge showed more viral contamination level than digested sludge and the lowest prevalence of viruses was reported in lime stabilized sludge. The review reveals that land application of sewage sludge may pose viral infection risks to people due to accidently ingestion of sludge or intake of crops grown in biosolids amended soil. Moreover, contamination of groundwater and/or surface water may occur due to land application of sewage sludge.

A Green Approach to Safe Domestic Drinking Water Supply by Using Solar Geyser

Introduction: Accessibility to safe drinking water is an important human health issue, so water reuse and water resources management are critical in arid parts of developing  regions. This study aimed to investigate the use of a combined simple designed solar geyser/photocell for drinking water disinfection. Materials and Methods: In this study, a solar geyser with a simple design was combined with a solar cell and its efficiency on the disinfection of contaminated water was investigated. This study was carried out with artificially polluted tap water by a solar geyser joined with a solar photovoltaic cell. The heated water (55°C) was kept for 2 hours using a solenoid valve. The pilot plant was operated and monitored for one year. The volume of the collected effluent was measured every 24 h. The most probably number (MPN) of total coliforms and fecal coliforms in 100 mL of 24-hour composed samples were measured. Results: The mean volume of disinfected water production was calculated as 2095.74 ± 270.28 mL/day. The strongest correlation was found between disinfected water and the maximum daily ambient air temperature with a linear model (R2 = 0.9937). The results showed that by increasing the sunny time, the volume of water outlet increased. Therefore, sunny time and UV radiation have direct effect on volume of disinfected water. Conclusion: The simple designed solar geyser for drinking water disinfection was efficient and recommended for tropical areas, emergency conditions, and farms for agricultural activities.

Long-term trends of Nitrogen oxides and surface ozone concentrations in Tehran city, 2002-2011

BACKGROUND AND AIM

Tropospheric ozone is a problem with multi aspects - hazard to human health, plant, and welfare and a key factor to climate change, air pollution and atmosphere chemistry, as well. Behavior of ozone and nitrogen oxides (NO, and NO2) concentration is highly complex and variable; therefore, their trends as short and long-term were significantly attended. Most of the studies were carried out on the behavior of pollutant concentrations in North America, Europe, and East Asia, but few studies have been conducted in west Asia. The aim of this study was to assess daily changes and long-term trend of ozone and nitrogen oxides concentrations in Tehran city, Iran from March 2002 to September 2011.

MATERIAL AND METHODS

Data were collected from 18 air quality monitoring stations. The data were sorted as daily mean of 10 years (daily changes) and annual mean for each year (long-term trend). One-sample test was used to assess the statistical significance.

RESULTS

Current findings indicated that changes of ozone, NO, and NO2 concentrations are dependent from job shifts and photochemical reactions. Annual mean concentrations of ozone and NO2 were gradually increased, long-term trend of ozone and NO2 concentration indicated. The correlation between long term trend of ozone and NO2 was significant (p < 0.05).

CONCLUSION

The controlling program was the most important factor in long-term concentration of ozone, and nitrogen oxides, but some problems and difficulties were accounted to perform controlling program.

Study for determination of industrial water corrosivity in Kashan Fajre Sepahan Galvanizing Mills during 2005-2006 Iran

This research was carried out in Kashan Fajre Sepahan Galvanizing mills (KFSGM) for evaluation of water corrosivity during 2005-2006. A total of 18 samples were taken from various points of the water supply system for testing the specific parameters and calculation Langelier Index (LI), Ryznar Index (RI) and Pukorious Index (PI). This research showed that in raw water (sand filter effluent) LI were positive as well as RI and PI were lower than 7 which means that mentioned water is not corrosive. Also LI in treated water by reverse osmosis process was negative and RI and PI were higher than 7, so, this water has corrosive properties. Finally, calculated indexes indicate that according to LI, conditioned water is not corrosive but based on RI and P. this water tend to corrosivity which this findings is compatible with literature review statement. So it is recommended that, for water conditioning addition of preservative chemicals to be continued but at the same time another alternatives such as pH adjustment, air stripping and deoxygenating, control of carbonate concentration and split flow treatment should be studied.