Removal of Toxic Elements and Microbial Contaminants from Groundwater Using Low-Cost Treatment Options

Purpose of Review This paper reviews various low-cost treatment techniques such as adsorption, permeable reactive barrier, and biological techniques for the simultaneous removal of chemical and microbial contaminants from groundwater and discusses treatment mechanisms of different treatment techniques. This paper also discusses the challenges of groundwater treatment, how to choose the appropriate treatment technique, and cost analysis of groundwater treatment. Recent Findings Various treatment technologies have been used for the treatment of groundwater: physical, chemical, and biological technologies with different success rates. In the literature, various adsorbents have been successfully synthesized from low-cost and environmentally friendly materials. Adsorption is considered an efficient treatment technique for the removal of both toxic elements and pathogens by utilizing different adsorbents. For example, the nanostructures of MgO with a BET surface area of up to 171 m2/g obtained a very high adsorption capacity of 29,131 mg/g for fluoride ions in water, while the incorporation of iron in activated carbon has improved its adsorption capacity to 51.3 mg/g for arsenic. Moreover, certain adsorbents have shown the capability to remove 99% of the rotavirus and adenovirus from groundwater. Summary Groundwater resources are contaminated with toxic metals and pathogens. Therefore, water treatment technologies should be evaluated for their efficiency to remove such contaminants. Determination of the most cost-effective and efficient treatment technique is not an easy task and requires the understanding of various aspects such as the contaminants present in water, the reuse options considered, and cost analysis of the treatment technique.Other Information Published in: Current Pollution Reports License: https://creativecommons.org/licenses/by/4.0See article on publisher's website: http://dx.doi.org/10.1007/s40726-021-00187-3</p

Sex-stratified analysis of national trends and outcomes in isolated tricuspid valve surgery.

OBJECTIVE: Female sex is a known risk factor for cardiac surgery, and tricuspid valve (TV) disease is more common in women. There are few data on sex-stratified surgical outcomes for isolated TV surgery. An administrative database was used to compare acute in-hospital outcomes between men and women undergoing isolated TV surgery. METHODS: Patients aged \u3e18 who underwent TV repair or replacement from 2004 to 2013 were identified using the National Inpatient Sample. Patients were excluded if they had congenital heart disease, endocarditis, or were undergoing concomitant cardiac surgeries except coronary bypass. Results were weighted to represent national averages. Sex-stratified analysis was performed using propensity score matching to compare in-hospital mortality, postoperative complications and hospital costs. RESULTS: Over 10 years, women represented 58% of the 5005 TV surgeries performed. With propensity matching, hospital mortality (7.9% vs 7.7%; P=0.99) and median length of stay (11 vs 11 days; P=0.99) were similar between men and women. However, median hospital charges were higher for men ($166 000 vs$155 000; P=0.04). CONCLUSION: Isolated TV surgery is rare, but women more commonly undergo the procedure. In-hospital mortality was similar between men and women after propensity matching, but remains markedly high for both men and women in comparison to that reported for left-sided isolated valve surgery

Recellularization of a novel off-the-shelf valve following xenogenic implantation into the right ventricular outflow tract.

Current research on valvular heart repair has focused on tissue-engineered heart valves (TEHV) because of its potential to grow similarly to native heart valves. Decellularized xenografts are a promising solution; however, host recellularization remains challenging. In this study, decellularized porcine aortic valves were implanted into the right ventricular outflow tract (RVOT) of sheep to investigate recellularization potential. Porcine aortic valves, decellularized with sodium dodecyl sulfate (SDS), were sterilized by supercritical carbon dioxide (scCO2) and implanted into the RVOT of five juvenile polypay sheep for 5 months (n = 5). During implantation, functionality of the valves was assessed by serial echocardiography, blood tests, and right heart pulmonary artery catheterization measurements. The explanted valves were characterized through gross examination, mechanical characterization, and immunohistochemical analysis including cell viability, phenotype, proliferation, and extracellular matrix generation. Gross examination of the valve cusps demonstrated the absence of thrombosis. Bacterial and fungal stains were negative for pathogenic microbes. Immunohistochemical analysis showed the presence of myofibroblast-like cell infiltration with formation of new collagen fibrils and the existence of an endothelial layer at the surface of the explant. Analysis of cell phenotype and morphology showed no lymphoplasmacytic infiltration. Tensile mechanical testing of valve cusps revealed an increase in stiffness while strength was maintained during implantation. The increased tensile stiffness confirms the recellularization of the cusps by collagen synthesizing cells. The current study demonstrated the feasibility of the trans-species implantation of a non-fixed decellularized porcine aortic valve into the RVOT of sheep. The implantation resulted in recellularization of the valve with sufficient hemodynamic function for the 5-month study. Thus, the study supports a potential role for use of a TEHV for the treatment of valve disease in humans

Mechanical properties.

<p>(A.) Stiffness comparison of native porcine, decellularized porcine with sterilization, and recellularized porcine explant after 5 months in vivo. (B.) Ultimate tensile strength comparison of native porcine, decellularized porcine implant with sterilization, and recellularized porcine explant after 5-months in vivo.</p

Gross examination.

<p>Explanted aortic valves showing aortic cusp without evidence of thrombosis, increased thickness, or calcification. Explant taken immediately after 5-month sacrifice and cross-sectioned to show anatomical features.</p