Avicenna Journal of Environmental Health Engineering
Volume:9 Issue: 1, Jun 2022

Given the variable nature of industrial wastewaters, the appropriate operation of an industrial wastewater treatment plant (WWTP) is a prerequisite for keeping process stability at ideal conditions. In this respect, an artificial neural network (ANN) can be a powerful device for the prediction of treatment performance. This study assessed some qualitative parameters of industrial wastewater (Amol Industrial Estate) during a one-year operating period. The wastewater treatment process consisted of an equalization tank, up-flow anaerobic fixed bed (UAFB) bioreactor, activated sludge tank, sedimentation tank, and chlorination basin. The ANN was utilized to estimate the system efficiency of the UAFB process. The outcomes demonstrated an extraordinary arrangement between the real and simulated data (R2>0.8). This model supplied a proper device for forecasting the implementation of WWTPs. Continuous checking elements could be used for the simulation of wastewater specifications.

Metallic coagulants have been used for more coagulation and flocculation of flocs in many wastewater treatment plants (WWTPs) in all parts of the world. The integration of different methods to improve the wastewater treatment process has been considered in recent years. In this case-control study, the effects of four main coagulants (ferric chloride, ferric sulfide, alum, and poly-aluminum chloride) on sludge volume index (SVI) with and without exposure of static magnetic fields (SMFs) have been investigated. Both methods significantly reduced SVI (mL/g), but the combination of SMFs and coagulants was more effective. Ferric chloride could control bulking or reduce SVI to less than 150 mL/g at concentrations of 0.0625 to 2 g/L when the SMFs intensity of 15 mT was used. The control of bulking in other coagulants happened when SMFs were added to coagulants at 0.0625-0.125 g/L concentration of coagulants (P<0.05). With the application of SMFs, the highest reduction of SVI belonged to ferric sulfide (43.60%), followed by ferric chloride (18.40%), poly-aluminum chloride (PACl) (20.19%), and alum (19.80%). Without the application of SMFs, the highest reduction of SVI belonged to ferric chloride (38.36%), followed by alum (34.94%), PACl (25.43%), and ferric sulfide (6.69%).

The present study aimed to investigate the effects of zinc exposure (0, 1, 5, 15, 30 mg/L zinc) on the biochemical and physiological parameters of Peganum harmala seedlings. Two populations (metallicolous and non-metallicolous) were compared in Zn tolerance, Zn accumulation, photosynthetic pigments, and enzymatic antioxidant activities. Plants were treated with Zn at concentrations of 0, 1, 5, 15, and 30 mg/L for 14 days. The study results showed that the increase of Zn concentration in the nutrient solution reduced shoot length, root length, root dry weight, shoot dry weight, chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid in both populations; however, the accumulation was more pronounced in metallicolous populations (M) than in non-metallicolous (NM) ones. In response, the activities of antioxidant enzymes such as guaiacol peroxidase, lipoxygenase, superoxide dismutase, catalase, and ascorbate peroxidase were enhanced Zn exposure in both populations. Moreover, it was found that the metallicolous population of P. harmala had a greater capacity to adapt to oxidative stress caused by Zn than the non-metallicolous population, and antioxidative defense in the metallicolous population of P. harmala might have played an essential role in Zn tolerance. Therefore, P. harmala seemed to be a suitable candidate for accumulation; however, it was recommended that further investigations be carried out to explore its metal remediation ability. It is concluded that P. harmala can be a potential candidate for bioremediation of Zn contaminated soils.

Transmission of leachate from municipal solid waste landfills can potentially threaten ecosystems and human societies when the landfill has no system for collecting and treating leachate. Leachate produced from landfills finds its way through the soil to groundwater and surrounding surface waters, leading to pollution of water resources. This study aimed to investigate the effects of leachate from Khalkhal landfill (a city in Ardabil province, northwestern Iran) on the quality of groundwater and surrounding surface water. During 2019-2020, 4 wells (one control well located upstream of the landfill and three wells located downstream of the landfill) and two stations of the surface water resource of the Herochai river were spots for sampling. First, we did sampling during high and low rainfall seasons in accordance with the standards. Second, we analyzed the values of some physical, chemical, and biological quality parameters according to standard methods. The sampling of the soil texture was conducted following ASTM D 422 standards. Then, the soil was analyzed at Reference Laboratory of Water, Soil, and Plant in Ardabil province. The value of most parameters measured in the water of downstream wells was lower than the limit recommended by the Iranian and World Health Organization, indicating no limitation for drinking and agricultural uses. The quality of the Herochai river water was also relatively undesirable in terms of turbidity and total coliform in some samples. Additionally, consistent with the study results, no difference was observed between high and low rainfall seasons. According to the results obtained from different parameters, Schuler and Wilcox diagrams, and landfill water pollution index (LWPI), the quality of upstream and downstream water resources of Khalkhal municipal solid waste landfill was not much different. In other words, the landfill did not affect water.

Currently, UVC radiation is used in hospitals to eliminate microorganisms and reduce adverse health effects in operating rooms (ORs) and protective environment rooms (PERs). The purpose of this study was to investigate the effect of UVC irradiation on bioaerosols in ORs and PERs. This experimental study was performed in ORs and PERs in a hospital. Bioaerosols were evaluated according to the National Institute for Occupational Safety and Health (NIOSH) standard (No. 0800). The samples were collected from indoor air of rooms before irradiation and after UVC(254 nm) irradiation for 20 and 480 minutes. The sample size of the study was determined to be 432 (216 fungi and 216 bacteria). The difference between the mean concentration of bioaerosols in the UVC radiation at two intervals (20 and 480 minutes) was significant, which indicates a decrease in the concentration of bioaerosols by increasing the duration of UVC radiation. Some bacteria, such as group B Streptococcus, Lactobacillus, and Listeria, were entirely killed after 20 minutes of irradiation; however, complete removal of the bacteria such as Staphylococcus pneumoniae and Staphylococcus saprophyticus was observed after 480 minutes of UVC irradiation. Fungi, such as Alternaria, Stofelim, and Mucor had a 100% reduction after 20 minutes of UVC irradiation, and Rhizopus and Aspergillus fumigatus showed a 100% decrease after 480 minutes of UVC irradiation. Other isolated fungi such as Cladosporium, Penicillium, Aspergillus niger, Rhodotorula, and Alternaria showed a decrease of 75%-98.78%. The ultraviolet (UV) sensitivity of bacterial and fungal bioaerosols depends strongly on their type. The results from this study may offer an important understanding of the control of indoor bioaerosols using UVC irradiation and help abate the environmental impacts of airborne microbes.

The removal of formaldehyde as a toxic substance from aqueous solutions is of particular importance. In this research, a sequencing batch rotating-bed bioreactor (SBRB) was used on a laboratory scale for biodegradation of formaldehyde from synthetic wastewater. The reactor was made of plexiglas with a cylindrical shape. Kaldnes media were placed in a rotating cylindrical basket in the reactor. The effects of formaldehyde concentration (500–1500 mg/L), hydraulic retention time (HRT) (8, 15, 24 hours), and injection of hydrogen peroxide (0.1-0.5 mM) on the performance of the reactor were investigated. The results showed that in the SBRB, at an HRT of 24 hours and an inlet formaldehyde concentration of 1000 mg/L, the removal efficiencies of formaldehyde and chemical oxygen demand (COD) were 99.2% and 92%, respectively, while without rotating the bed, the removal efficiency of formaldehyde and COD was found to be 95% and 83%, respectively. By adding hydrogen peroxide at a concentration of 0.3 mM and operation of the SBRB with an HRT of 8 hours and an inlet formaldehyde concentration of 1000 mg/L, an improvement in the removal efficiency of formaldehyde and COD (4% and 22%, respectively) was observed. Accordingly, SBRB stimulation with hydrogen peroxide could be considered as a high-performance process for the removal of formaldehyde and corresponding COD at a short HRT.

Water safety plan (WSP) is a new way to ensure the safety of drinking water by risk assessment and systematic prevention approach. The purpose of this study was to assess the risk and identify hazards from the production source to the point of use and plan to reduce or eliminate these hazards to provide safe drinking water. This study was conducted on the water supply system of Talesh city in 2021. The WSP has 12 stages and the third stage is risk assessment and hazard identification. This stage scored 69 points out of a total of 100 raw points, which indicates 69% coordination with the WSP. Based on the analysis, 47 hazards were identified in production sources, transmission lines, distribution network, and point of use. The presence of domestic sewage wells near the source of supply, undesirable chlorine concentration, and old pipes in the distribution network, as well as the failure of the check valve at the point of consumption are the most important risks. With the implementation of different phases of WSP, especially the stage of identification and assessment of microbial contamination risk in the distribution network, has been decreased to 0% and the desired residual chlorine concentration has been increased to 100%. Currently, water supply system of Talesh has a moderate level of safety.

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.