Environmental Health Engineering and Management Journal
Volume:7 Issue: 4, Autumn 2020

The effect of confinement due to the coronavirus disease 2019 (COVID-19) pandemic on air pollution has been investigated in several cities. Indeed, the concentration of the main air pollutants have decreased significantly due to the decline in activities consuming fossil fuels. However, it was
found that the concentration of ozone (O3) has increased in Nice, Rome, Valence, Barcelona, Turin, and Wuhan. The main objective of this study was to assess the impact of the COVID-19 pandemic on photochemical pollution in Oran, Algeria.

In Oran, a port city in the north-west of Algeria, the level of tropospheric ozone pollution was measured automatically every 15 min for 10 days at the same location before and after the confinement period, using an electronic nose, called APOMOS (air pollution monitoring system). This electronic circuit is equipped with an electrochemical sensor (MQ131) as well as a temperature and humidity sensor. Sampling was carried out in the central part of the Oran agglomeration from May to June 2020. The data related to the direction and intensity of the wind were processed to find a correlation between these parameters and the concentration of ozone in the studied area.

The impact of confinement on the increase of the ozone pollution levels in Oran, was estimated to be 52%. On the other hand, the statistical study of the pollution levels, the intensity and direction of the wind indicates that the important part of the downtown is involved in the generation of tropospheric
ozone.

The confinement due to the COVID-19 pandemic in Oran led to the reduction of the road traffic and pollutants emissions and the increase of ozone levels in urban area. Thus, ozone was less degraded because there were low levels of nitrogen oxides (NOx) in the atmosphere of this city during the confinement period.

Contamination by heavy metals has been a major threat locally, regionally, and globally because it affects the structural and functional properties of an environment. The aim of the study was to assess the concentration of heavy metals (Pb, Cd, Cr, and Mn) in the feathers of bird species sampled from three areas in Kano metropolis, Nigeria.

Fifteen samples of birds’ feathers were collected from industrial, residential, and commercial areas using mist-nets which were randomly placed to catch passerine birds, early in the morning from 6a.m. to 8a.m. The collected samples were then digested and subjected to atomic absorption spectrophotometry to determine Pb, Cd, Cr, and Mn.

The highest concentrations of heavy metals in the birds’ feathers were observed in site A (Sharada) followed by site B (Kurmi market) and site C (Rijiyar Lemo), however, the difference in the concentrations of heavy metals between the study areas was not statistically significant (P > 0.05). Pb had the highest concentration followed by Cd, Cr, and Mn. The highest concentrations of metals were found in the feathers of cattle egret (Pb=89 ppm, Cd=45 ppm, Mn=0.022 ppm), mallard drake (Pb=78 ppm), hen (Cd =41 ppm), duck (Cr =2.75 ppm), rooster (Mn =0.024 ppm), and guinea fowl (Cd =41 ppm), respectively.

The birds’ feathers contained various levels of heavy metals which greatly reflect the nature of the sites. Sharada industrial area (site A) recorded the highest concentrations of metals indicating slight metal contamination in the birds’ feathers especially in site A.

Microcystin (MC) is a hepatotoxic and carcinogenic toxin that is generated by cyanotoxins which can have adverse effects on the human health. Therefore, it is very important to remove it from the environment. This study was performed to investigate the efficiency of titanium dioxide (TiO2)/NaY zeolite (T/N-Z) nanocomposite for removal of MC-LR under ultraviolet light.

In the present study, T/N-Z nanocomposite was synthesized using the hydrothermal method. Specification of the photocatalysts was determined by the field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) spectra. The response surface methodology (RSM) was used to survey the effects of operating variables such as pH, contact time, and catalyst dose on the removal of MC-LR. The MC-LR concentration was measured by high-performance liquid chromatography (HPLC).

It was revealed that the increase of contact time and catalyst dose had a positive effect on enhancing the removal efficiency of MC-LR, but pH had a negative effect. Finally, the maximum MCLR removal efficiency was 97.63%, which occurred at pH = 5, contact time = 120 min, and catalyst dose = 1.2 g/L.

In general, T/N-Z composite in aqueous solutions under the UV light can easily decompose MC-LR and it can also be proposed as an efficient composite for removal of MC-LR from contaminated water.

Chlorination of wastewater effluent with high levels of residual organic matter has been suspected to the production of toxic and hazardous disinfection by-products (DBPs) including trihalomethane (THM) compounds.

In this study, two rapid techniques including dissolved oxygen depletion (DOD) and optical density (OD) bioassays were used to evaluate the chloroform toxicity of aqueous solution. The activated sludge was collected from aeration tank of a full-scale municipal wastewater treatment plant and used as a biological inoculum. In order to achieve an active and stabilized mixed culture of bacteria, the test cultures were transferred to a fresh nutrient broth culture media every day. The influence of chloroform on DOD and OD bioassays was examined at chloroform initial concentrations of 10-1000 μg/L.

It was revealed that the application of chloroform at concentrations of 100 and 1000 μg/L showed moderate and extreme toxicity, respectively, and reduced bacterial activity. The estimated chemical concentration with 50% inhibition of bacterial activity for DOD and OD bioassays was 457 and 961 μg/L, respectively.

According to the results, the wastewater effluent should use bioassays in order to evaluate the effects of DBPs where the wastewater effluent is disinfected by chlorine compounds.

The sterilization cycle is one of the most important parts of infection control. Accordingly, the present study was conducted to assess the quality of steam sterilization and compare the knowledge, attitude, and practice of clinical directors in dental clinics, based on the experimental work in one of the most important and famous dental departments and clinics in the Northeast of Iran.

This cross-sectional study was conducted from June to September 2017 in 84 dental outpatient clinics of Mashhad, Iran. The status of sterilization quality was evaluated using biological (BI) and chemical indicators (CI) and the results of a questionnaire. The participants include the technical manager and operator of the Autoclave, who were included in this study according to the inclusion criteria by stratified cluster sampling. Information on their knowledge, practices, and attitudes were evaluated. Also, BI and CI were used to evaluate the autoclave accuracy. The data were analyzed by Mann Whitney U, Wilcoxon signed-rank, and Fisher’s exact tests using SPSS (Version 19, SPSS Inc., Chicago, IL, USA).

In this study, the results of 69 (82.1%) biological test were negative. Based on the questionnaire results, 64 (76%) clinics used CI, and only 4 (5%) clinics used CI and BI to evaluate the sterilization quality. The mean scores of attitude (P = 0.001), knowledge (P = 0.001), and practice (P < 0.001) of the technical manager in dental clinics were significantly higher than those in outpatient clinics. Also, there was a significant association between the knowledge and practice of the clinics’ technical managers (P < 0.001).

According to the results, 93.3% of the clinics that had a positive biological test were outpatient clinics. Also, it was revealed that insufficient knowledge, attitude, and practice lead to imperfect sterilization. Also, the mean score of dentists was higher than that of general practitioners, therefore, in addition to suggesting training programs for managers, it is recommended that employ a dental practitioner as the technical manager of outpatient clinics. In order to control infection in clinics, it is recommended to monitor the sterilization process in clinics according to the instructions of the monitoring units.

Natural organic matters such as humic acid react with chlorine and produce disinfection by products such as trihalomethanes that are carcinogenic. In this study, shellfish ash was used as a novel adsorbent for removal of humic acid.

The present study was performed under various laboratory conditions including pH, adsorbent dose, contact time, and initial concentration of humic acid. Residual concentrations of humic acid in the samples were determined by a UV-Vis spectrophotometer at 254 nm wavelength. Artificial neural network (ANN) modeling studies were also performed.

Elemental analysis showed that the shellfish ash was 98% pure calcium. It was indicated that the maximum adsorption capacity was achieved in acidic conditions (pH = 3) and pHzpc was found to be 10.3. The adsorption data followed the Langmuir model (R2 > 0.9). The adsorption of humic acid followed the pseudo-second-order kinetic (R2 = 0.999). ANN modeling also provided the accurate prediction of humic acid adsorption for testing data (R2 = 0.989).

According to the results, shellfish ash is recommended as an effective biosorbent for removal of organic pollutants such as humic acid.

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 human health, the aim of this study was to develop a dynamic model with focusing on domestic water management.

This study was performed using a system dynamics approach. The strategies used in this study include population scenarios (ps), water use education scenarios (wu education), and agricultural water management scenarios (Agriwm).

There was a significant relationship between education on water saving in domestic sector and water use per capita. In various scenarios of population growth, domestic water use was declined rapidly with education. According to the obtained results, under “ps3-wu education” scenario, lower population growth, and higher water use education, domestic water use will reach the minimum level, by 2041. The results showed that the proposed scenarios can lead to 60% reduction in domestic water use.

With education strategy, water use per capita up to 2024 can reach the optimum level of 100 liters per person per day. However, without education even by 2041, this goal is unattainable. So, sustainable goals can be achieved by adopting education strategy. The developed systematic model can be applied in various conditions. In each study area, the regional water and population data should be provided.

One of the most important problems of dams is thermal layering which directly affects the water quality. This study was performed to propose a solution to increase the water quality of the Esteghlal Dam reservoir in Minab, Hormozgan.

The water quality of Esteghlal Dam was evaluated from 2016 to 2018. During this period, 18 samples were collected from three different points of the dam. The parameters of water temperature, electrical conductivity, total dissolved solids, total suspended solids, dissolved oxygen (DO), pH, nitrate, phosphate, turbidity, biochemical oxygen demand, chemical oxygen demand, total hardness, anions and cations, total phosphorus, physicochemical, and microbial parameters were measured according to the method recommended in the standard method book. The obtained data were used as the input for the model of reservoir water quality (CE-QUAL-W2) to simulate reservoir water quality and predict the thermocline cycle. Finally, by plotting hypolimnion oxygen content against time and finding the slope of regression line using the data, the hypolimnetic oxygen demand (HOD) was obtained.

The findings showed that the anaerobic condition occurred in the hypolimnion layer during summer. Furthermore, it was revealed that the HOD of Esteghlal Dam is about 6 g of oxygen per square meter per day in the current situation.

Considering the dam’s conditions and its anaerobic problems, a hypolimnetic oxygenation system is proposed as a structural solution for this reservoir. Then, conductivity-temperature-depth (CTD) profiles and monitoring data were used for the oxygen supply model of plume. The reservoir was predicted after calculating the amount of oxygen required using the equations governing linear oxygen supply systems and the plume model.