Removal of 1,2-dichloroethane from industrial wastewater with membrane filtration

Background and Aims: 1,2-dichloroetane [ethylene dichloride (EDC)] is a chlorinated hydrocarbon which is widely used to produce vinyl chloride. The later is the major precursor to PVC production. Wastewater originating from EDC production is characterized by high turbidity and contains ethylene dichloride and FeCl3 particles. The aim of the present study was to investigate the treatability of EDC effluent using membrane filtration.Materials and Methods: Laboratory scale experiments were carried out on Abadan petrochemical complex wastewater (EDC unit) with various membrane filtration processes that combine microfiltration with nanofiltration. Microfiltration membrane was used as a pretreatment to remove turbidity as well as FeCl3 fine particles, which may subsequently damage nanofiltration system. The microfiltration effluent was thereafter fed to a nanofiltration membrane cell. The filtration performance was assessed through turbidity, TDS, COD and 1,2-dichloroetane removals. pH, temperature and system pressure were also controlled during the study.Results: Successful removal of turbidity (97.5%) and FeCl3 particles (98%) was achieved by microfiltration. EDC concentration in raw effluent was ranged between 2,000 to 3,000 ppm. The nanofiltration membrane cell followed by microfiltration achieved a very high 1,2-dichloroetane removal (96.7) from water. The experimental results indeed showed that the permeate was consisted mainly of water, which asserts that 1,2-dichloroetane was separated in waste phase.Conclusion: The results obtained provide further support for previous researches into this brain area and support the application of membrane technology to remove and recovery of soluble organic compounds from petrochemical wastewater.Key words: Petrochemical wastewater, 1,2-dichloroetane, Membrane filtration, Nanofiltration, Microfiltratio

Removal of Estrogen Hormones (17-Estradiol and Estrone) from Aqueous Solutions Using Rice Husk Silica

The aim of this study was to investigate the removal of estrogen hormones (17β-estradiol and estrone) from aqueous solutions using rice husk extracted silica. Rice husk was collected from rice factories in Mazandaran province (Iran) and the adsorbent was prepared in a furnace at 800 °C for 4 h, after acid leaching with hydrochloric and sulfuric acid mixture. Optimal operating parameters for estrogen removal were determined, including initial pH values (4–9), adsorbent dosages (0.5, 1, 1.5, and 2 g L–1), contact times (30, 60, 90, and 120 min), and initial concentrations of 17β-estradiol and estrone (10, 40, 70 and 100 ng L–1); one-factor-at-a-time method was used. The method of electrochemiluminescence was used to measure the concentration of hormones. Kinetic adsorption models and adsorption isotherms were also studied. The maximum removal efficiency (%) of 17β-estradiol (E2) and estrone (E1) hormones of 95.5 and 93.1 %, respectively, was obtained at optimal conditions of pH 4, 1.5 g L–1 of adsorbent dosage, 60 min of contact time and 10 ng L–1 initial concentrations of E2 and E1. Pseudo first-order kinetic model and Langmuir adsorption isotherm had the best fit with experimental data for both estrogen hormones, following nonlinear regression procedure. Rice husk silica could be considered as effective and accessible adsorbent for removal of estrogenic hormones. This work is licensed under a Creative Commons Attribution 4.0 International License

Powder activated carbon/Fe3O4 hybrid composite as a highly efficient heterogeneous catalyst for Fenton oxidation of tetracycline: Degradation mechanism and kinetic

In this work, we prepared and used a composite of powder activate carbon/Fe3O4 magnetic nanoparticles (PAC/Fe3O4 MNPs) as a heterogeneous catalyst to remove tetracycline (TC) from aqueous solution. By using XRD, BET, VSM, SEM, TEM and EDX techniques, also, we tried to characterize the catalyst. The effects of pH, H2O2, catalyst dosages and also initial TC concentration on the degradation process were assessed. Based on the results, it was indicated that at low pH values and initial TC concentrations, the efficiency of the process is higher than the other values and concentrations studied in this work. Under the ambient conditions and setting the initial pH value and TC concentration at respectively 3.0 ± 0.2 and 10 mg L-1, the optimal dosage of reagents were recorded to be 0.3 g L-1 catalyst and 80.0 mM H2O2. The values of observed rate constants, kobs, increased by increasing the catalyst loading in the system; however, these values decreases when the initial TC concentration was increased. Our findings indicated that all of TC concentration was nearly degraded during the 180 min reaction. Regarding the reusability of PAC/Fe3O4 MNPs, the results showed that TC and TOC removal efficiencies of 94.5 and 32.3, respectively, can be achieved after four consecutive runs. By conducting the stability experiments, it was confirmed that PAC/Fe3O4 MNPs is a promising and effective catalyst in Fenton reactions and can be used to treat TC-contaminated water with very low loss of catalytic activity. © 2015 The Royal Society of Chemistry

Environmental damage of different waste treatment scenarios by considering avoided emissions based on system dynamics modeling

This study aims to develop a comprehensive model for life cycle assessment and environmental damage cost calculations considering avoided emissions in different waste management scenarios using the system dynamics (SD) approach. Our analysis reveals that under the business-as-usual (BAU) scenario for the period 2020–2050, the total net greenhouse gas (GHG) emissions reach 12.5 Mt, with the highest environmental damage cost being USD 689 million. In contrast, an integrated management strategy encompassing recycling, composting, anaerobic digestion, and incineration results in a 195% reduction in net GHG emissions compared to the BAU Scenario. Concurrently, the environmental damage cost drops to USD 277 million, incorporating USD 347 million in savings, leading to a net environmental damage cost of USD −71 million. The findings affirm that accounting for emissions avoided across various treatment methods offers a more accurate estimate of environmental damage costs. Additionally, policies centered on integrated waste management are more likely to achieve sustainability. The study also demonstrates the utility of the SD approach in providing a holistic view of waste management systems and in evaluating the effectiveness of various policy strategies for sustainable waste management

A systematic review and meta-analysis of human biomonitoring studies on exposure to environmental pollutants in Iran

Population exposure to environmental contaminants can be precisely observed through human biomonitoring studies. The present study aimed to systematically review all the biomonitoring studies conducted in Iran on some selected carcinogen environmental pollutants. In this systematic review study, 11 carcinogen agents were selected including arsenic, cadmium, chromium, nickel, lindane, benzene, trichloroethylene (TCE), pentachlorophenol (PCP), radon-222, radium-224, � 226, � 228, and tobacco smoke. The Web of Science, PubMed, and Scopus databases were searched for peer-reviewed articles published in English. After several screening steps, data were extracted from the studies. Meta-analyses (a random-effect model using the DerSimonian-Laired method) were performed only for the biomarkers with more than three eligible articles, including cadmium in blood and breast milk, and arsenic in breast milk. Methodological quality of the studies was assessed using the Newcastle-Ottawa Quality Assessment Scale adapted for cross-sectional studies. Of the 610 articles found in the database search, 30 studies were eligible for qualitative review, and 13 were included in the meta-analysis (cadmium in blood (n = 3), cadmium in breast milk (n = 6), and arsenic in breast milk (n = 4)). The overall pooled average concentrations (95 CI) of cadmium in blood, cadmium in breast milk, and arsenic in breast milk were 0.11 (95 CI: 0.08, 0.14), 5.38 (95 CI: 3.60, 6.96), and 1.42 (95 CI: 1.02, 1.81) µg/L, respectively. These values were compared with the biomarker concentrations in other countries and health-based guideline values. This study showed that there is a need for comprehensive action plans to reduce the exposure of general population to these environmental contaminants. © 202

Enhancement the conditioning of waste activated sludge through a sequence of freeze/thaw-electro-Fenton process

Sludge conditioning is an important stage in sludge management. In the present study, a sequence of freeze/thaw-electro-Fenton process was designed and specific resistance filtration (SRF) was monitored during sludge conditioning as an important factor in sludge dewaterability. Furthermore, protein and polysaccharide concentrations were measured during the experiments. Results showed that the lowest SRF value contributed to −10°C in freezing process which showed a reducing trend by decreasing solution pH. In addition, results revealed that solution pH less than 3 caused a significant improvement in sludge dewatering; so the lowest SRF has been registered at pH = 2. By increasing current intensity from 0.5 to 1A, SRF values were reduced and then followed by an enhancement with increasing current intensity to 3.2 A. The lowest SRF value (6.1 × 104 m/kg) was obtained at H2O2 = 30 mg/L which was the best conditions for sludge dewatering

A systematic review of possible airborne transmission of the COVID-19 virus (SARS-CoV-2) in the indoor air environment

At the end of December 2019, the rapid spread of the COVID-19 (SARS-CoV-2) disease and, subsequently, deaths around the world, lead to the declaration of the pandemic situation in the world. At the beginning of the epidemic, much attention is paid to person-to-person transmission, disinfection of virus-contaminated surfaces, and social distancing. However, there is much debate about the routes of disease transmission, including airborne transmission, so it is important to elucidate the exact route of transmission of the COVID-19 disease. To this end, the first systematic review study was conducted to comprehensively search all databases to collect studies on airborne transmission of SARS-CoV-2 in indoor air environments. In total, 14 relevant and eligible studies were included. Based on the findings, there is a great possibility of airborne transmission of SARS-CoV-2 in indoor air environments. Therefore, some procedures are presented such as improving ventilation, especially in hospitals and crowded places, and observing the interpersonal distance of more than 2 m so that experts in indoor air quality consider them to improve the indoor air environments. Finally, in addition to the recommendations of the centers and official authorities such as hand washing and observing social distancing, the route of air transmission should also be considered to further protect health personnel, patients in hospitals, and the public in other Public Buildings