Investigation of Dust Chemical Compounds Emitted by Electric Arc Furnace (EAF) with a reuse perspective

In the process of steel production by electric arc furnace (EAF), it is found that 10 to 20 kg of dust was emitted per every ton of produced steel. Concerning the pollution potential of emitted dust and its reuse ability, the present study was aimed to determine the chemical composition of the electric arc furnace dust with a reuse perspective. This study was done in a steel factory equipped with EAF. Local exhaust ventilation system is installed on the furnace and equipped with cyclone and venturi scrubber. To analysis of dust compounds were gathered in a cyclone and those left the system, the samples were taken from the cyclone hopper and exhaust fan outlet. Finally, the samples were analyzed by X-ray diffraction (XRD). According to the results, the trapped dust in the cyclone and scrubber were 226.86 and 44.81 kg/hr, respectively. The results obtained from XRD analysis also showed that about 50% of the dust was formed by Fe2O3. The quotient of other compounds such as CaO, MgO, SiO2, and Zn was more than 30%. Conclusion: the results of this study showed that EAF dust composed of a range of elements with different concentrations. Given the high weight of these compounds, reusing some of these elements can be having a positive impact on health and the economy

A Systematic Review and Meta-analysis to Investigate the Correlation Vegetable Irrigation with Wastewater and Concentration of Potentially Toxic Elements (PTES): a Case Study of Spinach (Spinacia oleracea) and Radish (Raphanus raphanistrum subsp. sativus)

Water shortage and stress around the world lead to the reuse of wastewater in many sectors while the recycling of water in agriculture as one of the most consumed sectors can boost the contamination of crops by potentially toxic elements (PTEs). Therefore, this study was aimed to investigate the correlation between the accumulation of PTEs (Fe, Zn, Cr, Ni, Cu, Pb, As, Cd, and Se) in edible parts of spinach and radish plants and sewage irrigation by the aid of a meta-analysis. Moreover, the non-carcinogenic risk (N-CR) and carcinogenic risk (CR) for health risk assessment of consumers were assessed through actual total target hazard quotient (TTHQact) and carcinogenic risk (CRact). After the screening process, 51 articles with 75 studies were included. According to findings, the rank order of PTEs in spinach and radish were Fe > Zn > Cr > Cu > Ni > Pb > Cd > As > Se and Fe > Zn > Cr > Ni > Cu > Pb > As > Cd > Se, respectively. PTE adsorption by edible parts of spinach (leafy vegetable) was higher than radish. The health risk assessment shows that residents in Iran, India, and China are at N-CR while the population of Iran, India, and Pakistan are facing CR. © 2020, Springer Science+Business Media, LLC, part of Springer Nature

Effect of coagulation and sonication on the dissolved air flotation (DAF) process for thickening of biological sludge in wastewater treatment

Background: Dissolved air floatation (DAF) is one of the methods has been used for the sludge thickening in wastewater treatment plants. This study aimed to investigate the effects of coagulation and sonication processes as additional configurations on the efficiency of a lab-scale DAF process for thickening of the biological sludge of an industrial wastewater treatment plant in Kashan, Iran. Methods: The required amounts of sludge samples were collected from a wastewater treatment plant and kept at temperature of 4°C. Variables, such as pressure (3, 5, and 7 atm), flotation time (5 and 10 minutes), ultrasonic irradiation power (0, 75, and 150 W), and presence/absence of Fe-based coagulant were considered on a sequencing batch reactor (SBR) included coagulation, flotation, and sonication processes, respectively. Results: The use of ultrasonic waves led to an insignificant increase in the DAF efficiency (P > 0.05), however, the application of coagulant significantly increased the thickening efficiency (P < 0.05). The maximum efficiency of the process was achieved at flotation time of 5 min, pressure of 3 atm, and sonication power of 75 W. Conclusion: According to the results, DAF has a proper efficiency for thickening of biological sludge. Coagulation compared to sonication has a greater effect on the efficiency of the process. Keywords: Ultrasonic waves, Industrial effluent, Dissolved air flotation, Sonicatio

Investigation of nitrate and nitrite concentration and other physicochemical parameters of drinking water sources in Saveh city during the year of 2018

Abstract   Background and Purpose:Qualitative parameters of drinking water such as concentration of nitrate, nitrite, sulfate, total soluble solids, sodium, magnesium, fluoride, total hardness and electrical conductivity can play an important role in groundwater resources and are mainly related to agriculture, waste disposal areas and sewage. The aim of this study was to determine these parameters in drinking groundwater resource of Saveh city using Geographic Information System during the year of 2018 and investigation of contaminant’s in the region’s aquifer. Materials and Methods:This research is a descriptive-analytic study. 120 samples of water from 12 drinking water wells were prepared in spring and two times in the morning and afternoon in different parts of the city of Saveh. The quality parameters of drinking water, including concentration of nitrate, nitrite, sulfate, total soluble solids, sodium, magnesium, fluoride, total hardness and electrical conductivity were entered into the GIS software and stored in a database and then processed by the information system software, color mapping was prepared and geographical maps (GIS) were mapped to qualitative status. Also, reverse interpolation was used to estimate the conditions of the whole region. Findings:The average concentration of chlorine, sulfate, electrical conductivity, total soluble solids, total hardness and sodium exceeds the permissible limits, and the non-qualitative water conditions are quite evident. Also, the amount of two magnesium and sulfate ions was above the standard 1053. It should be kept in mind that the high levels of these two ions can interfere with the digestive system. Fluoride and nitrate levels were also acceptable range in all areas. Conclusion:The highest deviation level from 1053 standard was for total soluble solids, sodium, magnesium, and sulfate. It is better to consider a comprehensive program to solve the problem, including use of nanotechnology, filtering or ion exchange

The concentration of potentially toxic elements (PTEs) in human milk: A systematic review, meta-analysis, and health risk assessment

Human milk has an important role in infants' psychological and immunological development. In addition to providing vital substances, some environmental contaminants, such as potentially toxic elements (PTEs), can be transmitted by human breast milk to infants. However, some studies monitored PTEs concentration in human breast milk; no metanalysis was conducted to estimate the concentration of PTEs in human breast milk. Therefore, this review aimed to determine PTEs concentrations in human breast milk and consumption-related health effects worldwide via meta-analysis and health risk assessment. After searching among Scopus, Web of Science, and PubMed databases, 32 studies were included in this work. Based on the results, the rank order of PTEs was Fe (258.44 µg/kg) > Zn (205.16 µg/kg) > Cu (32.29 µg/kg) > Mn (4.30 µg/kg) > Cr (2.62 µg/kg) > Hg (0.44 µg/kg) > As (0.21 µg/kg) > Cd (0.16 µg/kg) > Pb (0.03 µg/kg). Moreover, Egypt, Pakistan, Brazil, Jordan, and Turkey for non-carcinogenic risk (n-CR) and Egypt, Jordan, Brazil, and Romania for carcinogenic risk (CR) have shown unsafe levels, respectively. Since the lactating mothers’ diet can directly affect their milk’s content, monitoring the feeding behavior (especially supplements taken during pregnancy) and the quality of foods is recommended

Bioaccumulation of potentially toxic elements (PTEs) in muscle Tilapia spp fish: a systematic review, meta-analysis, and non-carcinogenic risk assessment

The consumption of marine foods such as Tilapia spp fish offers several beneficial nutrition effects, however, it can endanger the health of humans while contains a high concentration of potentially toxic elements (PTEs). In this work, the related studies regarding the concentration of PTEs in Tilapia fish were collected by searching among some databases such as the Web of Science, Scopus, PubMed, and Embase. Furthermore, the concentration of PTEs in Tilapia spp fish was meta-analyzed by the aid of the random effect model (REM). Additionally, the non-carcinogenic risk in both adults and children due to the ingestion of PTEs via consumption of Tilapia spp fish was estimated by calculating target hazard quotient (THQ) and total target hazard quotient (TTHQ). Meta-analysis of 79 articles (87 data) showed that rank order of PTEs (mg/kg) in Tilapia spp fish was Fe (9.925)>Zn (1.556)>Mn (1.065)>Cr (0.627)>Cu (0.485)>Pb (0.218)>Ni (0.217)>As (0.140)>Hg (0.113)>Cd (0.107). The rank order of PTEs based on their quota in TTHQ was As (86.21%)>Hg (4.01%)>Ni (2.96%)>Pb (2.32%)>Zn (1.38%)>Fe (1.21%)>Cu (0.95%)>Cd (0.80%)>Cr (0.10%)>Mn (0.06%). Also, the non-carcinogenic risk assessment shows that TTHQ for both adults and children consumers was lower than 1, demonstrating no considerable non-carcinogenic risk in all countriessem informaçã

Global evaluation of potentially harmful elements (PHEs) in potato and carrot irrigated by wastewater: A systematic review, meta-analysis, and health risk assessment

Background: We aimed to conduct a meta-analysis on the concentration of potentially harmful elements (PHEs) in carrots and potatoes irrigated by wastewater and estimate non-carcinogenic health risks among adult and children consumers. Methods: The health risk of PHEs concentration, including Pb, Cd, total Cr, Ni, Zn, Cu, and Fe, in the edible parts of carrot and potato irrigated by wastewater was investigated by a meta-analysis using a random-effects model (REM). Accordingly, the related articles were screened from international databases such as Scopus, Medline, and Embase. Results: The meta-analysis of 32 papers (38 studies) revealed that the rank order of the most accumulated PHEs in potato was Fe (86.54 mg/kg wet weight) > Zn (30.9 mg/kg wet weight) > Cu (13.7 mg/kg wet weight) > Ni (8.42 mg/kg wet weight) > Pb (5.56 mg/kg wet weight) > Cr (3.45 mg/kg wet weight) > Cd (0.58 mg/kg wet weight). This ranking for carrot was Fe (43.36 mg/kg wet weight) > Zn (36.29 mg/kg wet weight) > Ni (13.49 mg/kg wet weight) > Cu (9.79 mg/kg wet weight) > Pb (1.84 mg/kg wet weight) > Cr (1.05 mg/kg wet weight) > Cd (0.28 mg/kg wet weight). Total hazard quotient (THQ) of PHEs was higher than 1 for potato and carrot; its rank order for potato and carrot was Cu > Pb > Cd > Ni > Fe > Zn > Cr and Cd > Pb > Cu > Ni > Fe > Zn > Cr, respectively. The Cd, Pb, and Cu had also a considerable role for consumer health risk. Conclusion: According to the results, continuous monitor and control of wastewater treatment plants are necessary. Keywords: Wastewater, Food chain, Cadmium, Lead, Risk assessmen

Accumulation of potentially harmful elements (PHEs) in lettuce (Lactuca sativa L.) and coriander (Coriandrum sativum L.) irrigated with wastewater: a systematic review and meta-analysis and probabilistic health risk assessment

Water shortage and stress around the world lead to increasing wastewater reuse for the agricultural sector. In addition to its benefits, it can be a way to transfer pollutants such as potentially harmful elements (PHEs) to the human food chain. Many studies have been conducted for this purpose on various vegetables; however, no comprehensive study has been performed on lettuce (Lactuca sativa L.) and coriander (Coriandrum sativum L.). In this respect, the study was aimed to meta-analyze the PHEs concentration in the edible part of lettuce and coriander vegetables irrigated by wastewater. Carcinogenic risk (CR) and noncarcinogenic risk (non-CR) assessments were also done for consumers. After reviewing 32 included articles (41 studies), the rank order of the PHEs in lettuce was obtained as Fe (194.76 mg/kg) > Zn (133.47 mg/kg) > Cu (55.70 mg/kg) > Ni (26.96 mg/kg) > Pb (12.80 mg/kg) > Cr (9.68 mg/kg) Cd (8.24 mg/kg) > As (1.13 mg/kg) and for coriander Fe (1056 mg/kg) > Zn (79.80 mg/kg) > Cr (28.34 mg/kg) > Ni (24.71 mg/kg) > Cu (17.46 mg/kg) > Pb (13.23 mg/kg) > Cd (2.23 mg/kg). Total target hazard quotient (TTHQ) for adults in all countries except UAE, France, and Kenya and for children all countries except Kenya was more than 1 value. The carcinogenic risk for adult groups in Nigeria, France, China, and Iran countries was not acceptable (CR > 1E-4). As a consequence, it can be noted that wastewater reuse in the agriculture sector can endanger the health of consumers. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature

Application of dissolved air flotation process for industrial sludge thickening: A laboratory-scale study

Aims: Increasing population density in cities has led to an increase in industrial and municipal wastewater sludge generation volume. Dissolved air flotation (DAF) can widely be used for water and wastewater treatment. The aim of our study is to evaluate some DAF design parameters on biological sludge thickening which generated from an industrial wastewater treatment plant. Materials and Methods: This experimental research had been carried out as a laboratory-scale study on DAF process to thickening of the biological sludge. The required amount of sludge was taken once from the Amikabir industrial town wastewater treatment plant in Kashan, Iran. After determination of optimal recycling rate, pH, and coagulant dose, effects of pressure (3, 5, and 7 atm), flotation time (5 and 10 min), and coagulant addition were evaluated on DAF process efficiency. Results: According to this investigation results, the optimal pH and dose of coagulant were obtained 7.5 and 200 mg/L, respectively. Maximum process efficiency for the reduction of total dissolved solids (TDSs), total solids (TSs), and turbidity parameters was 61.01%, 84.02%, and 97%, respectively. Furthermore, the results showed that in contrast to time, coagulant addition and pressure have significant effect on DAF process. Conclusion: DAF process had suitable thickening efficiency to removal of TDS, TS, and turbidity on biological activated sludge

Effect of Dissolved Air Flotation Process on Thickening of Activated Sludge

Abstract Aims: Sludge is an inescapable component of all wastewaters that originated from their treatment. dissolved air flotation (DAF) process as an alternative clarifier is used in treatment of drinking water, pretreatment of wastewater, and as a phase separator in sludge activation processes. This study aimed to calibrated the usage of DAF process in a laboratory scale and under various conditions, to achieve the optimum efficiency in recycling the activated sludge. Instrument & Methods: In this experimental study, of Kashan's Shahid Beheshti hospital and immediately transported to the laboratory. The optimal dose of polyaluminum chloride coagulant and pH was determined and then applied in DAF process. Finally turbidity, electrical conductivity (EC) and total solids (TS) parameters were measured and compared with control sample. Findings: The optimal pH and optimal dose of coagulant were 6.5 and 25mg/l, respectively. Also Optimal process efficiency to reduce EC, TS and turbidity parameters were 23.4, 44.5 and 88%, respectively. Conclusion: Dissolved air flotation process removes the turbidity, EC and TS effectively; however, it has minimal impact on EC and TS