Decontamination Of Drinking Water Research Articles

A Review on Development of Ceramic-Graphene Based Nanohybrid Composite Systems in Biological Applications.

Graphene-based nanocomposites constitute an interesting and promising material for various applications. Intensive progress in the development of this group of materials offers an opportunity to create new systems useful for drinking water decontamination or other biotechnological applications. Nanohybrid structures of graphene-ceramic systems can be obtained using covalent graphene surface modification with nanoparticles (NPs) of ceramic and/or co-deposition of metals with selected morphology and chemistry. The present paper systematizes the associated bio-related knowledge and inspires future development of graphene/NPs systems. Emerging knowledge and unique research techniques are reviewed within designing the required nanocomposite structure and chemical composition, development and optimization of new methods of covalent surface modification of graphene with NPs as well as analysis of mechanisms governing the formation of covalent bonding. Further, innovative research tools and methodologies are presented regarding the adjustment of functionalities of materials used for the application in drinking water decontamination or biocidal composites. This study provides a comprehensive base for rational development of more complex, hybrid graphene-based nanomaterials with various bio-functionalities that can be further applied in industrial practice.

Multifunctional carbon-supported bioactive hybrid nanocomposite (C/GO/NCP) bed for superior water decontamination from waterborne microorganisms.

Achieving both effective and sustainable water decontamination technology requires development of a universal filtration solution. However, effective removal of natural waterborne microorganisms still remains a challenge. The use of nanoparticles in water filters is promising but also leads to problems with their efficiency and safety. To cross these bottlenecks, we have designed a novel multifunctional carbon-supported bioactive hybrid nanocomposite filtration bed. For this purpose, we took advantage of granular activated carbon (C), graphene oxide (GO) and bioactive Al2O3/Ag nanocomposite particles (NCP). These components were assembled into a hybrid nanocomposite structure using facile in situ surface decoration via a sol–gel approach. This obtained C/GO/NCP filtration bed was thoroughly characterized in terms of morphology, structure and surface properties as well as further evaluated for tap water filtration efficiency. Analysis of the preferential sites for bacteria adsorption and biological tests under close-to-real static and dynamic filtration conditions has proved C/GO/NCP's efficiency in eliminating model and natural strains of waterborne microorganisms. At the same time, nanoparticles were not released into the filtrate, which confirmed material stability and safety. We have also revealed that C/GO/NCP nanofiltration bed was self-sterilizing which means that it entirely eliminated up to 100% of the filtered bacteria cells within short periods of contact time. What is more, the low-temperature thermal regeneration allowed recovering the assumed properties. In general, the obtained results indicate a breakthrough in designing hybrid-structured filtration beds that can be easily synthesized and safely used for drinking water decontamination.

Analysis of Biofilm-Resistance Factors in Singapore Drinking Water Distribution System

In drinking water distribution system (DWDS), biofilm offers protection of bacterial community within the extracellular polymeric substance (EPS) from outside stressors, including surrounding environment, predatory microorganisms and antibiotics. The growth of biofilm may increase cleaning and maintenance cost for the drinking water decontamination and expose high risk to human immune system. This article critically reviews current Singapore DWDS by analysing the leading and lagging performance of two stages, granulated active carbon (GAC) filtering and secondary disinfection by chloramine, which are highly relevant with the biofilm resistance. Furthermore, other extrinsic factors, such as pipe age and material, hydraulic retention time, seasonal change, primary ultraviolet disinfection, etc. are also reviewed. Finally, top-down approach to address the growth and biofilm resistance are proposed. Practices and technology methodology, e.g. good consumers’ hygiene, nutrient removal, chlorine disinfection, probiotic approach, anti-biofouling coatings are discussed with their associated challenges and opportunities.

A technology of drinking water decontamination from radon and its decay products

Abstract Underground water is one of the main sources of radon for households. This article focuses on the estimation and removal of radon from underground water using the technology and inorganic sorbents developed by EKSORB Ltd., Russia for liquid radioactive waste treatment in the nuclear power industry. The article presents the results of tests of a system for the removal of radon and radon daughters from water patented by EKSORB. This is achieved by filtering water through RATZIR sorbent, followed by periodic load regeneration. Over a period of three years, the plant is successful in removing radon from the water that had an initial radon content of approximately 1500 Bq/L to less than 60 Bq/L, without releasing radon to indoor/outdoor air.

Drinking water decontamination by biological denitrification using fresh bamboo as inoculum source

Groundwater contamination is becoming a serious problem in many Brazilian regions. European countries started to deal with this issue in the 1980s, mainly caused by the extensive usage of nitrogenous fertilizers and the absence of domestic wastewater treatment. Due to its high solubility, nitrate readily passes through the soil and reaches the aquifer. Thereafter, this ion moves, following groundwater flow, and can be found several kilometers from the area where the pollution occurred. Concern about nitrate contamination is due to the link found between this contaminant and various human health diseases, such as methemoglobin and cancer. Studies carried out in France enabled the design and implementation of several biological denitrification plants throughout the country, in order to remove nitrate from its contaminated groundwater. Heterotrophic denitrification facilities shown to be adequate to treat high water flows with satisfactory nitrate removal efficiency, especially when static media supports are employed. The objective of this research was to evaluate the existence of denitrifying microorganisms in bamboo (Bambusa tuldóides) and verify the feasibility of their use to inoculate a pilot-scale fixed-bed bioreactor. The support material selected to fill the bioreactor bed was commercial polypropylene Pall rings, since such support has a high porosity associated with a wide superficial area. The bioreactor was able to produce and retain a large amount of cells. Using ethanol as carbon source, nitrate (N-NO3(-)) removal efficiency of the bioreactor stood around 80 % for a maximum nitrogen loading rate of approximately 6.5 mg N-NO3 (-) L(-1) h(-1).

Accumulation of zirconium phosphate by a Serratia sp.: a benign system for the removal of radionuclides from aqueous flows

Metal phosphate deposited enzymatically on Serratia sp. has been used successfully for the removal of radionuclides from aqueous flows. Previous studies using biogenic hydrogen uranyl phosphate (HUP) on Serratia sp. biofilm showed removal of 100% of (90)Sr, (137)Cs, and (60)Co via their intercalation into biogenic HUP crystals. Zirconium phosphates (ZrP) offer a potential non-toxic and non-radioactive alternative to HUP for water decontamination. A method was developed for biomanufacturing ZrP. Biogenic ZrP removed ca. 100% of Sr(2+) and Co(2+) (0.5 mM) from solutions to a molar ratio at saturation of ca. 1:0.6 for both Zr:Sr and Zr:Co. The potential for drinking water decontamination via bio-ZrP is discussed with respect to bio-HUP and also other commercially available materials.

Bactericidal behaviour of Ti6Al4V surfaces after exposure to UV-C light

TiO 2-coated biomaterials that have been excited with UV irradiation have demonstrated biocidal properties in environmental applications, including drinking water decontamination. However, this procedure has not been successfully applied towards the killing of pathogens on medical titanium-based implants, mainly because of practical concerns related to irradiating the inserted biomaterial in situ. Previous researchers assumed that the photocatalysis on the TiO 2 surface during UV application causes the bactericidal effects. However, we show that a residual post-irradiation bactericidal effect exists on the surface of Ti6Al4V, not related with photocatalysis. Using a combination of staining, serial dilutions, and a biofilm assay, we show a significant and time-dependent loss in viability of different bacterial strains of Staphylococcus epidermidis and Staphylococcus aureus on the post-irradiated surface. Although the duration of this antimicrobial effect depends on the strains selected, our experiments suggest that the effect lasts at least 60 min after surface irradiation. The origin of such phenomena is discussed in terms of the physical properties of the irradiated surfaces, which include the emission of energy and changes in surfaces charge occurring during electron-hole recombination processes. The method here proposed for the preparation of antimicrobial titanium surfaces could become especially useful in total implant surgery for which the antimicrobial challenge is mainly during or shortly after surgery.