Contaminant containment for sustainable remediation of persistent contaminants in soil and groundwater

Contaminant containment measures are often necessary to prevent or minimize offsite movement of contaminated materials for disposal or other purposes when they can be buried or left in place due to extensive subsurface contamination. These measures can include physical, chemical, and biological technologies such as impermeable and permeable barriers, stabilization and solidification, and phytostabilization. Contaminant containment is advantageous because it can stop contaminant plumes from migrating further and allow for pollutant reduction at sites where the source is inaccessible or cannot be removed. Moreover, unlike other options, contaminant containment measures do not require the excavation of contaminated substrates. However, contaminant containment measures require regular inspections to monitor for contaminant mobilization and migration. This review critically evaluates the sources of persistent contaminants, the different approaches to contaminant remediation, and the various physical-chemical-biological processes of contaminant containment. Additionally, the review provides case studies of contaminant containment operations under real or simulated field conditions. In summary, contaminant containment measures are essential for preventing further contamination and reducing risks to public health and the environment. While periodic monitoring is necessary, the benefits of contaminant containment make it a valuable remediation option when other methods are not feasible

The Effect of Nitrate as a Radical Scavenger for the Removal of Humic Acid from Aqueous Solutions by Electron Beam Irradiation

Introduction: Humic acids have adverse effects on the water quality, then should be removed from water resources. The aim of this study was to evaluate the effect of nitrate as a radical scavenger for removal of humic acid from aqueous solutions by electron beam irradiation. Materials and Methods: In this study, after preparation of stock humic acid solution in alkaline condition, different concentrations of humic acid (10, 25 and 50 mg/l) were prepared. Different concentrations of nitrate (25, 50 and 100 mg/l) added to humic acid samples and then absorption of samples was measured at 254 nm by using UV-Vis spectrophotometer before and after the electron beam irradiation. This study has done at pH= 8 and at different electron beam adsorbed dose of 1, 3, 6, 9 and 15 kGy. Results: The results of this study showed that the increasing of adsorbed dose from 1 to 15 kGy, the removal efficiency of humic acid also increased. By increasing of nitrate concentration from 25 to 100 mg/l, the removal efficiency of humic acid has decreased from 43.8% to 36.6% and nitrate acts as a radical scavenger. By increasing of humic acid concentration from 10 to 50mg/l, removal efficiency decreased in all adsorbed doses. Kinetic analysis of our results showed that the results well fitted with the second - order reaction. Conclusion: We can conclude from this study that electron beam irradiation could be a useful process for the treatment of natural organic matter (humic acid) from surface waters

Evaluation of Efficacy of the Current Disinfectants on Gram-negative Bacteria Isolated from Hospital in Yazd in 2014

as Pseudomonas, Acinetobacter, and Staphylococcus that appropriate disinfection can reduce these pathogens. The aim of this study was to evaluate the effect of different disinfectants on Gram-negative bacteria isolated from the surface of accidents and burn hospital in Yazd. Materials and Methods: In this study, 240 samples were randomly collected from different parts of accidents and burn hospital before and after disinfection. The samples were cultured on blood agar and Eusion-Metilen-Blue agar media in the Microbiology Laboratory of Medicine School of Shahid Sadoughi University in Yazd and Colony counting were determined. Identification was done by biochemical tests after incubation at 37° C for 48 hours. The studied disinfectants were Deconex 50AF, Descoscid, Epimax SC, and Silvosept. At last, data were analyzed with using paired t-test. Results: The Gram-negative bacteria were isolated from burn unit before disinfection included Pseudomonas aeruginosa, Escherichia coli, Proteus spp., Klebsiella spp., Acinetobacter spp., and Enterobacter spp. According to the results, all disinfectants reduced the pollution before and after disinfection; nevertheless, this reduction at the time of using Epimax SC and Silvosept only showed a significant difference for P. aeruginosa (P = 0.001 and 0.003) and for E. coli (P = 0.020 and 0.005), respectively. Conclusion: All disinfectants were effective on Gram-negative bacteria isolated from surfaces and had shown a significant difference only between P. aeruginosa and E. coli number before and after disinfection by Epimax SC and Silvosept. The most effective disinfectant on P. aeruginosa and E. coli was Epimax SC and Silvosept, respectively

The Effectiveness Evaluation of Current Disinfectants on Pathogens Isolated from Surface of Different Parts of Shahid Sadughi Accidents Burns Hospital in City of Yazd

Background: The burn unit is a suitable environment for the growth of pathogenic bacteria that can reduce these pathogens by appropriate disinfection methods. So, choosing an appropriate disinfectant and applying standard methods of disinfection can be effective in reducing nosocomial infections. The aim of this study is evaluation of efficacy of current disinfectants on pathogens isolated from surface of different parts of Shahid Sadughi accidents burns hospital in city of Yazd. Methods: In this study, the sampling method has done simple randomly and 240 samples were collected from 30 different parts of hospital surfaces (for every disinfectant 30 samples before and 30 samples after disinfection). The samples in the Microbiology laboratory of Medical Sciences University were cultured on blood agar and EMB agar culture. Colonies that were suspected to pathogens were identified by biochemical tests and their colony count was determined. Data were analyzed using Paired T-test. Results: The average of isolated bacteria at 4 parts of burn unit of hospital before disinfecting by Deconex 50 AF, Descoscid, Epimax SC and Silvosept was 58.02, 18897.28, 30989.05 and 38.52 respectively and after disinfecting was 12.8, 0.62, 1.65 and 5.09 respectively. Reducing of contamination in all disinfectants shown a significant difference (p<0.05). The most common isolated pathogens were Pseudomonas aeruginosa, Klebsiella, staphylococcus aureus, Enterobacter and Escherichia coli. Conclusion: The results showed that all disinfectants was effective on isolated pathogens and also have shown a significant difference (p<0.05) between the average of bacteria count before and after disinfection

Sustainable management of hazardous asbestos-containing materials: Containment, stabilization and inertization

Asbestos is a group of six major silicate minerals that belong to the serpentine and amphibole families, and include chrysotile, amosite, crocidolite, anthophyllite, tremolite and actinolite. Weathering and human disturbance of asbestos-containing materials (ACMs) can lead to the emission of asbestos dust, and the inhalation of respirable asbestos fibrous dust can lead to ‘mesothelioma’ cancer and other diseases, including the progressive lung disease called ‘asbestosis’. There is a considerable legacy of in-situ ACMs in the built environment, and it is not practically or economically possible to safely remove ACMs from the built environment. The aim of the review is to examine the three approaches used for the sustainable management of hazardous ACMs in the built environment: containment, stabilization, and inertization or destruction. Most of the asbestos remaining in the built environment can be contained in a physically secured form so that it does not present a significant health risk of emitting toxic airborne fibres. In settings where safe removal is not practically feasible, stabilization and encapsulation can provide a promising solution, especially in areas where ACMs are exposed to weathering or disturbance. Complete destruction and inertization of asbestos can be achieved by thermal decomposition using plasma and microwave radiation. Bioremediation and chemical treatment (e.g., ultrasound with oxalic acid) have been found to be effective in the inertization of ACMs. Technologies that achieve complete destruction of ACMs are found to be attractive because the treated products can be recycled or safely disposed of in landfills

Recovery, regeneration and sustainable management of spent adsorbents from wastewater treatment streams:A review

Adsorption is the most widely adopted, effective, and reliable treatment process for the removal of inorganic and organic contaminants from wastewater. One of the major issues with the adsorption-treatment process for the removal of contaminants from wastewater streams is the recovery and sustainable management of spent adsorbents. This review focuses on the effectiveness of emerging adsorbents and how the spent adsorbents could be recovered, regenerated, and further managed through reuse or safe disposal. The critical analysis of both conventional and emerging adsorbents on organic and inorganic contaminants in wastewater systems are evaluated. The various recovery and regeneration techniques of spent adsorbents including magnetic separation, filtration, thermal desorption and decomposition, chemical desorption, supercritical fluid desorption, advanced oxidation process and microbial assisted adsorbent regeneration are discussed in detail. The current challenges for the recovery and regeneration of adsorbents and the methodologies used for solving those problems are covered. The spent adsorbents are managed through regeneration for reuse (such as soil amendment, capacitor, catalyst/catalyst support) or safe disposal involving incineration and landfilling. Sustainable management of spent adsorbents, including processes involved in the recovery and regeneration of adsorbents for reuse, is examined in the context of resource recovery and circular economy. Finally, the review ends with the current drawbacks in the recovery and management of the spent adsorbents and the future directions for the economic and environmental feasibility of the system for industrial-scale application