Advanced processes for remediation of contaminated sediments

2016 - 2017Sediments play a fundamental role in the aquatic environment, especially for their interaction with the aquatic life. However, in the last decades, due to the increasing anthropic activities, a large amount of contaminants were released into the environment, as well as in the water bodies. The sediments, due to their characteristics, tend to adsorb the polluting compounds becoming a potential sink of contaminants. Among the several hazardous compounds, polycyclic aromatic hydrocarbon (PAHs) and heavy metals represent the contaminants most frequently detected onto sediments. These compounds are classified as “known” or “probable” human carcinogen by U.S. Environmental Protection Agency (US EPA) and the International Agency for Research on Cancer (IARC). The presence of hazardous compounds in the sediments constitutes a concern, not only for the possible negative effects on the environment and human health, but also for the technical-economical aspects related to their management. Indeed, contaminated sediments need a proper management and their free disposal in the aquatic system is not allowed. It was estimated that in Europe about 200 million cubic meters of sediments are dredged every year. These dredging activities are necessary not only for remediation purposes, but also to maintain adequate depth of navigation in the water bodies. Once removed, the traditional management options for the sediments include landfill and confined aquatic disposal, which are among the most used solutions. Nevertheless, these options are not sustainable under both an economic and an environmental point of view. The sediment reuse could be an effective alternative, but their adequate treatment is fundamental in order to avoid the possible release of hazardous compounds into the environment and the resulting adverse effects. In scientific literature different remediation technologies were proposed for treatment of contaminated soil. Few attempts have been also provide to adapt some of these techniques to polluted sediments. However, due to the specific characteristics of the sediments, including the prevalent fine grain size fraction, the technologies used for soil remediation are not always suitable for sediment treatment. Advanced Oxidation Processes (AOPs), which are widely used for the wastewater treatment, were also applied for the treatment of other environmental matrices thanks to their technology flexibility. Among AOPs, ultrasound (US) has raised growing interest in the scientific community, as an environmental friendly technology holding several advantages over conventional treatment solutions. In the field of wastewater treatment, US has been studied in order to promote either the partial degradation of organic compounds before biological process or the mineralization of the same kind of contaminants. Few research experiences also focused on US application to solid matrices, with the main aim of desorbing inorganic compounds. In polluted sediments, both organic and inorganic contaminants are simultaneously present and this aspect represents a major challenge in the choice of a remediation technology that could be effective for each kind of polluting compound. In this regard, the application of US can promote both the contaminant desorption from the solid particles and the degradation of the dissolved organic compounds. Therefore, aim of this work was in the study of the advanced technology effectiveness for the remediation of contaminated sediments. For this purpose, the experimental activity was divided in two main parts: - the first one focused on the study of US treatment effectiveness in promoting the reduction of both organic and inorganic contamination in a single stage; - the second part, performed on the basis of the results of the previous phase, was devoted to the assessment of the US effectiveness as treatment prior to another main remediation technique. In particular, US was implemented as pretreatment for electrokinetic (EK) processes. The first step was conducted at the laboratory of the Sanitary Environmental Engineering Division (SEED) of Salerno University. During this step both sonication frequency and treatment time were varied to investigate their effect on the removal yields of organic (B[]A and B[]P) as well as inorganic (Cd, Pb and Zn) contaminants. Experimental results demonstrated that the application of ultrasonic waves led to an overall reduction of the contaminant concentration. The best performances were achieved for the organic compounds, with high removal efficiencies reached after few minutes of treatment. Heavy metals showed removal yields almost constant in all experiments, despite the sonication frequency as well as the treatment time. The desorption of inorganic compounds was variable for each compound and the best results were obtained for Cd and Zn compared to Pb. In order to improve the heavy metal desorption by US, two different processing solutions, namely citric acid and ethylenediaminetetraacetic acid (EDTA), were tested as sonication medium. Both solutions determined an improvement in the desorption yields. However, the best performances were achieved with the citric acid, at a sonication frequency of 130 kHz. As previously noted, the variation of the treatment time was observed to be not significant, thus a long US treatment is not justified. In this regard, the process optimisation was pursued by reducing the treatment time. To this end, further tests were performed using a citric acid solution at 130 kHz and 2,5 min of sonication. An slight decrease in desorption percentage, was observed for each metal. Nevertheless, the desorption yields were satisfactory, with percentages always more than 75%. The second part of the work was performed at the laboratory of the Bioengineering and Sustainable Processes (BIOSUV) group at the University of Vigo (Spain). In order to evaluate the effectiveness of US as pre-treatment, this technology was applied before the electrokinetic process (EK). To this end, the combined process (US+EK) was compared with the remediation performances provided by the EK alone. Referring to the Cd and Zn, the results demonstrated a comparable desorption efficiency, close to the complete removal, for both EK process alone and US+EK. For Pb, instead, the use of US pre-treatment was able to improve the its desorption promoted a synergetic effect. The results obtained from the experimental activity proved that US technology could be a promising alternative for the reduction of both organic compounds and heavy metals from contaminated sediments. The studied process was observed to be very versatile, providing interesting performances as either stand-alone treatment or in combination with other remediation technologies. [edited by author]XXX cicl

Ultrasonic processes for the advanced remediation of contaminated sediments.

Sediments play a fundamental role in the aquatic environment, so that the presence of contaminants poses severe concern for the possible negative effects on both environmental and human health. Sediment remediation is thus necessary to reduce pollutant concentrations and several techniques have been studied so far. A novel approach for sediment remediation is the use of Advanced Oxidation Processes, which include ultrasound (US). This paper focuses on the study of the ultrasonic effects for the simultaneous reduction of both organic and inorganic contaminants from sediments. To this end, the US technology was investigated as a stand-alone treatment as well as in combination with an electro-kinetic (EK) process, known to be effective in the removal of heavy metals from soil and sediments. The US remediation resulted in higher organic compound degradation, with an average 88% removal, but promising desorption yields (47-84%) were achieved for heavy metals as well. The combined EK/US process was found to be particularly effective for lead. Experimental outcomes highlighted the potential of the ultrasonic technology for the remediation of contaminated sediments and addressed some considerations for the possible scale-up

Coronary Collateral Circulation: A New Predictor of Mortality in Heart Transplant Recipients With Allograft Vasculopathy

Background: Coronary collateral arteries (CCAs) are anastomotic channels between vessels; although beneficial in atherosclerosis, their role in heart transplantation (HT) recipients is underinvestigated. CCAs initially develop as microcirculation and cardiac allograft vasculopathy (CAV), promoting immune-dependent proliferative angiogenic response, and play a role in their development. In our hypothesis, ischemia induced by coronary microvascular dysfunction (CMD) triggers the development of CCAs, which are, in turn, less functional as affected by CAV themselves. Methods: One hundred twenty-one patients receiving HT at our institution were retrospectively evaluated and were included if transthoracic echocardiography with coronary flow velocity reserve (CFVR) assessment and coronary angiography were performed. CMD was defined as CFVR of ≤2.5. Patients with CAV were enrolled, and their angiograms were reviewed to evaluate the presence of CCAs. Cardiovascular mortality was assessed as the main clinical outcome. Results: Forty patients were found to have CCAs. Patients with CCAs have lower CFVR than those without CCAs (2.22 ± 0.72 versus 2.69 ± 0.92;P = 0.003), reflecting in different rates of CMD in the 2 groups (72.5% versus 37%; P < 0.001). CMD is associated with higher CAV grades (P < 0.001), which are also associated with CCAs (P < 0.001). Patients with poorly developed CCAs have lower CFVR (P < 0.001). At multivariable analysis, CMD (P = 0.008) and higher CAV grades (P = 0.005) are independent predictors of CCAs. During the median follow-up time of 10.2 (6.6-13.3) y, patients with CCAs have been found to have higher mortality than those without CCAs (57.5% versus 32.1%; P = 0.007). CCAs are associated with a lower probability of survival also in patients with CMD (P < 0.001) and are independent predictors of mortality (P < 0.001). Conclusions: Our results demonstrate an interplay between CAV, CMD, and CCAs. We confirm that CAV is associated with CMD, and we show, for the first time, that CMD is associated with CCAs. CCAs are pathophysiologically associated with more severe graft vasculopathy and independently predict mortality after HT

Treatment of contaminated marine sediments by sonolysis

The sediments of the port areas are often affected by the presence of several contaminants, which are generated from anthropic activities. These compounds can be toxic for the human health, thus, also to ensure a correct management and avoid the disposal in landfills, the sediments need to be treated. A novel approach proposal by international literature for sediments remediation is the use of advanced oxidation processes, which include ultrasonic technologies. Ultrasounds could be applied mainly to mineralize organic compounds and to desorb inorganic compounds through chemical and mechanical effects, respectively. The present paper is focused on the effectiveness of sonication to abate organic contaminants. The tests were carried out by ultrasound bath at different times of the treatment and sonication frequencies. The treatment efficiency was evaluated in terms of removal percentage. High percentages of degradation were achieved during the treatments in all the tests. The results demonstrated that ultrasound technology is a possible alternative technology for the treatment of contaminated sediment

SITI CONTAMINATI ESPERIENZE NEGLI INTERVENTI DI RISANAMENTO

I sedimenti delle aree portuali sono spesso interessati dalla presenza di contaminanti di natura organica ed inorganica, originati da fonti antropiche. Per un’adeguata gestione dei sedimenti contaminati indirizzata a promuoverne il riutilizzo, possono essere impiegate diverse tecnologie di trattamento. Scopo del presente lavoro è la verifica dell’applicabilità dei processi ad ultrasuoni per la decontaminazione di sedimenti marini contaminati da idrocarburi policiclici aromatici e metalli pesanti. Campioni rappresentativi di sedimenti sono stati contaminati artificialmente con benzo()antracene, benzo()pirene, piombo, zinco e cadmio e sono stati trattati mediante un bagno ad ultrasuoni. L’efficienza di trattamento, indagata al variare di tempo e frequenza di sonicazione, è stata valutata in termini di degradazione dei composti organici e desorbimento dei composti inorganici. I risultati hanno mostrato una buona efficienza di degradazione dei contaminanti organici, con percentuali superiori al 90%. Per i metalli pesanti, i risultati ottenuti relativi alla determinazione delle percentuali di desorbimento, hanno mostrato significativa variabilità. I primi test eseguiti hanno, dunque, evidenziato che gli ultrasuoni sono potenzialmente efficaci per il trattamento di sedimenti marini caratterizzati da contaminazioni complesse

Removal of Emerging Contaminants in Wastewater by Sonolysis, Photocatalysis and Ozonation

Three different advanced oxidation processes (AOPs) were applied to investigate the removal of emerging contaminants (ECs) i.e. sulfamethoxazole (SMX), diclofenac (DCF) and carbamazepine (CBZ) in synthetically prepared aqueous solutions. The degradation of these substances was carried out by ozonation, sonolysis and photocatalytic oxidation, as well as by different combinations of these processes. The objectives of this work were to evaluate the removal efficiency of each method and to assess the performance variation of sonolysis in combination with other AOPs. The best performances were achieved by sonocatalysis, which resulted in the removal of the selected pharmaceuticals in the range between 37% and 47%. Under similar experimental conditions, the removal of the selected ECs by single compounds by ozonation was slightly lower than the removal of respective compounds in the mixture. Moreover, pseudo first-order removal rate constants of photocatalytic mineralization were determined as 9.33×10-2, 4.90×10-3, 1.06×10-2 min-1 for SMX, DCF and CBZ, respectively

Interventricular conduction disorders after orthotopic heart transplantation: risk factors and clinical relevance

Causes and significance of interventricular conduction disorders (IVCDs) after orthotopic heart transplantation (OHT) are still unknown

A comparison of quality of life and psychological distress in heart transplantation patients at adult and pediatric ages

the aim of the current study was to evaluate and compare the quality of life (QOL) and psychological status of adult patients who underwent heart transplant (HTx) at pediatric or adult ages

Coronavirus disease 2019 (COVID-19) in the heart transplant population: a single-centre experience

OBJECTIVES: Few anecdotal cases have been reported in the literature regarding heart transplant recipients and infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We report our experience with 6 patients hospitalized in Northern Italy during the outbreak.METHODS: Of the 396 living heart transplant recipients from 1985 to 2020 included in the study, 6 patients developed the novel 2019 coronavirus disease. Risk factors, last follow-up characteristics, onset presentation, in-hospital course of disease and blood examinations data were collected for these patients.RESULTS: All patients were symptomatic and had positive results from a nasopharyngeal swab test for SARS-CoV-2. Of the 6 patients, 5 were hospitalized and 1 remained self-quarantined at home. Two patients died and 3 were discharged home. Two patients were admittted to the intensive care unit. Immunosuppressive therapy was modified with a median reduction comprising doses that were 50% cyclosporine and 50% mycophenolate. All patients received a medium-dose of corticosteroids as a bolus medication in addition to their therapy. All hospitalized patients received hydroxychloroquine; 2 patients received ritonavir/lopinavir. Broad-spectrum antibiotics for prophylaxis were administered to all. One patient had an ischaemic stroke and died of sepsis.CONCLUSIONS: In the absence of any strong evidence regarding the treatment of heart transplant recipients infected with SARS-CoV-2, we faced a new challenge in managing viral infection in an immunosuppressed population. Because immunomodulation interaction with the infection seems to be crucial for developing severe forms of the disease, we managed to reduce immunosuppressive therapy by adding medium doses of corticosteroids. Despite the limited number of affected patients, this report suggests that special considerations should be given to treating coronavirus disease in the heart transplant recipient population