Journal of Environmental Health Science and Engineering最新文献

Emerging contaminants are posing a new water quality challenge, worldwide. The majority of pharmaceutical and personal care products used by us have been regarded as emerging contaminants. Benzophenone is one such chemical found in personal care products, specially in sunscreen creams as an UV-filter. Copper tungstate/nickel oxide (CuWO₄/NiO) nanocomposite with visible (LED) light irradiation has been investigated in degradation of benzophenone, in the present study. The co-precipitation approach was used to produce the aforementioned nanocomposite. XRD, FTIR, FESEM, EDX, Zeta potential, and UV–Vis spectroscopy illustrated the structure, morphology, and other catalytic features. Response surface methodology (RSM) was used to optimize and simulate the photodegradation of benzophenone. Herein, catalyst dose, pH, initial pollutant concentration, and contact time were considered as the independent factor in the design of experiment (DoE) using RSM with percentage degradation as the dependent factor or as a response. The CuWO₄/NiO nanocomposite demonstrated high photocatalytic performance of 91.93% at pH = 11 with a pollutant concentration of 0.5 mg/L and a catalyst dose of 5 mg within 8 h under ideal circumstances. The RSM model was determined to be the most convincible with an R² value of 0.99 and a probability value (P-value) of 0.0033, respectively, with a agreeable projected and actual values. As a result, it is envisioned that this study may provide new avenue for developing a strategy to target such emerging contaminants.

In the present study, ZnO nanoparticles doped with 3%, 5% and 7% of cobalt have been synthesized by green method using Annona muricata leaf extract. The obtained nanopowder was characterised by XRD, FTIR, XPS, HRTEM, SAED, SEM, EDAX and UV–Visible spectroscopy techniques. XRD patterns confirm the formation of pure and Co doped ZnO nanoparticles with a hexagonal wurtzite structure with high phase purity. FTIR spectra indicate the stretching vibration of Zn–O at 495 cm⁻¹. The incorporation of Co²⁺ ions into the ZnO lattice was identified by XPS analysis. EDX spectra confirm the existence of Co, Zn and O elements. The SEM and HRTEM micrographs show morphology of nanoparticles. The optical study specifies a decrease in energy band gap with an increase in Co-doping concentration. The photocatalytic performance of ZnO and Zn_0.93Co_0.07O has been examined for the degradation of methylene blue (MB) under sunlight irradiation. The antimicrobial activity of synthesized nanoparticles against s.aureus, p.aeruginosa, b.subtilis bacterial strains c.albicans and a.niger fungal strains as investigated. The Zn_0.93Co_0.07O nanoparticles exhibit good antioxidant properties. Moreover, the cytotoxicity of ZnO nanoparticles was evaluated against L929 normal fibroblast cells. So, this work suggests that Annona muricata leaf extract mediated pure and Co-doped ZnO nanoparticles are a potential candidate for biomedical and photocatalytic applications.

Systems capable of disinfecting air and surfaces could reduce the risk of infectious diseases transmission. Aim: to evaluate the effectiveness of near-UV LED ceiling lamps, with a wavelength of 405 nm, in improving environmental hygiene. Between November and December 2020, we conducted an experimental study having a pre-post design in a kindergarten room in Siena where 4 ceiling lamps with 405 nm LED technology were installed. Twice per day, sampling was performed before (T0) and after treatment with near-UV (T1). We used between 8 and 12 pairs of contact plates to sample at various random spots each day. Air samplings were also performed. The plates were incubated at 22 and 36 °C. Significance was set at 95% (p < 0.05). The mean level of Colony Forming Unit (CFU) at T(0) was 249 (95% CI 193.1 – 305.0) at 36 °C and 535.2 (374.3 – 696.1) at 22 °C. The reduction was significant at T(1): by 65% at 36 °C and, 72% at 22 °C. Also, for air contamination: 95.3% (98.4—92.3). A dose threshold of about 5 J/cm² was identified to have an 80% CFU abatement and remains nearly constant. The advantage of being able to use this technology in the presence of people is very important in the context of controlling environmental contamination.

Graphical abstract

Abstract

Abstract

Objective

This research is based on the treatment of petroleum wastewater (PWW) with pretreated activated sludge for the production of electricity and removal of chemical oxygen demand (COD) using microbial fuel cell (MFC).

Methods

The application of the MFC system which uses activated sludge biomass (ASB) as a substrate resulted in the reduction of COD by 89.5% of the original value. It generated electricity equivalent to 8.18 mA/m² which can be reused again. This would solve the majority of environmental crises which we are facing today.

Results

This study discusses the application of ASB to enhance the degradation of PWW for the production of a power density of 1012.95 mW/m² when a voltage of 0.75 V (voltage) is applied at 30:70% of ASB when MFC is operated in a continuous mode. Microbial biomass growth was catalyzed using activated sludge biomass. The growth of microbes was observed by scanning through an electron microscope. Through oxidation in the MFC system, bioelectricity is generated which is used in the cathode chamber. Furthermore, the MFC operated using ASB in a ratio of 35 with the current density, which decreased to 494.76 mW/m² at 10% ASB.

Application

Our experiments demonstrate that the efficiency of the MFC system can generate bioelectricity and treat petroleum wastewater by using activated sludge biomass.

Fractionation of active biomass in a five-stage Bardenpho process was accomplished using an MS Excel wastewater treatment plant modeling tool based on Activated Sludge Model No. 3 extended with a bio-P module. The biomass fractions within the treatment system were predicted as autotrophs, ordinary heterotrophs, and phosphorus accumulating organisms (PAOs). Several simulations were performed in a Bardenpho process using various C/N/P ratios in primary effluent. Biomass fractionation was obtained from steady-state simulation results. The results suggest that the mass percentage of autotrophs, heterotrophs, and PAOs in active biomass range from 1.7 to 7.8%, 5.7–69.0%, and 23.2–92.6%, respectively, depending on characteristics of primary effluent. Results of principal component analysis showed that TKN/COD ratio in primary effluent determines the population of autotrophs and ordinary heterotrophs whereas PAO population is mainly a function of TP/COD ratio.

Purpose

Lead, a known toxic metal, causes several adverse reproductive effects, including low birth weight. Fortunately, the exposure level has sharply decreased during the recent decades, but a definitive safe level did not introduce for pregnant women yet. The current meta-analysis study aimed to conduct a quantitative estimation of maternal and umbilical cord blood lead effects on birth weight.

Methods

Two researchers have independently searched the scientific literature for retrieving related studies using the PRISMA criteria for data extraction. Twenty-one full-text articles were selected from primary 5006 titles, limited by the English language and published between 1991 and 2020 on humans.

Results

The pooled mean of maternal and umbilical cord blood lead levels were 6.85 µg/dL (95% CI: 3.36–10.34) and 5.41 µg/dL (95%CI: 3.43–7.40), respectively. The correlation coefficient analysis showed a significant inverse association between the mean maternal blood lead level and birth weight, which was confirmed by Fisher Z-Transformation analysis (-0.374, 95% CI: -0.382, -0.365, p < 0.01). In addition, a significantly lower birth weight (∆: 229 gr, p < 0.05) was found in the relatively high level of maternal blood lead than in low-level exposure (> 5 µg/dL vs. ≤ 5 µg/dL, respectively).

Conclusion

In short, the present study findings suggest an increasing maternal blood lead levels could be a potential risk factor for reducing birth weight. Thus, pregnant women should avoid lead exposure, as much as possible.

Groundwater is one of the major sources of exploitation in arid and semiarid regions. Spatial and temporal quality distribution is an important factor in groundwater management. Thus for protecting groundwater quality, data production on spatial and temporal distribution is essential. The present study has applied multiple linear regression (MLR) techniques to predict the fitness of groundwater quality in Kermanshah province, west of Iran. The parameters examined were Total dissolved solids (TDS), Total hardness (TH), Sodium adsorption ratio (SAR). the quality variables were modelled by MLR. Finally, the performance of the models was assessed using the coefficient of determination (R²). The relationship between parameters by MLR showed that TDS and water quality parameters in semi-deep wells and aquifers had a strong positive correlation (r = 0.94, r = 0.98) and there was a strong positive significant correlation between SAR and water quality parameters in deep wells and aquifers (r = 0.98, r = 0.99). Also, TH and water quality parameters in all water sources had a strong positive correlation (r = 1). The MLR model could serve as an alternative and cost-effective tool for groundwater quality prediction where there is limitation in laboratory facilities, trained expertise or time. Consequently, the usefulness of these linear regression equations in predicting the groundwater quality is an approach, which can be applied in any other locations.