Removal Of Microbial Contaminants Research Articles

A Review of Chitosan as a Coagulant of Health-Related Microorganisms in Water and Wastewater

The coagulation and flocculation properties of chitosan, an organic biopolymer derived from chitin, have been researched as an alternative to synthetic polymers and inorganic metal salt coagulants currently used in water and wastewater treatment. In an effort to encourage further research into the practical uses of chitosan as green chemistry in water and wastewater treatment and to promote the efficacious removal of microbial contaminants in drinking and wastewater, we have summarized the current state of research pertaining to the treatment of microorganisms in water and wastewater. A search of PubMed revealed 720 possible titles and abstracts, of which 44 full-text articles were identified as matching the eligibility criteria for inclusion in this systematic review. Results are presented based on the type of water matrix treated (i.e., drinking water, wastewater, and recreational waters) and a summary table providing details on the types and forms of chitosan utilized and the treatment mechanisms and processes described in the study. We find chitosan to be an effective coagulant, flocculant, and adsorbent for removing microbes from water and wastewater; some modified forms of chitosan can inactivate microbes and achieve disinfection, such as those containing metals like silver and antimicrobial chemicals like quaternary ammonium compounds or other strong oxidants, and use with filtration or electrochemical processes can achieve extensive reductions in microbes to meet performance targets of the World Health Organization.

Potential of selected microalgae in the bioremediation of wastewater impacted dam water: A case of Goreangab Dam in Windhoek, Namibia

The study was aimed at determining the efficacy of freshwater microalgae in the treatment of polluted dam water with respect to the reduction of pathogen loads, as well as heavy metals and nutrients concentrations. Microalgae were collected from the Klein Windhoek River, as well as the Avis and Goreangab Dams in Windhoek, Namibia. Identification of the microalgae species revealed the presence of the Microcystis species in the Goreangab Dam (control), Anabaena species in the Klein Windhoek River (treatment 1) and the Scenesdesmus species as well as the Anabaena species in the Avis Dam (treatment 2). During treatment, the water samples were assessed on day 0, day 6 and day 12 for faecal and total coliform bacteria, heavy metals (Pb and Cd) as well as nutrients (phosphorous and nitrates). A one-way analysis of variance (ANOVA) indicated that there were no statistical differences between the mean values of Pb (p = 0.346) and Cd (p = 0.940) concentrations after treatment with microalgae. The Kruskal Wallis tests indicated statistical differences between the mean values of the nitrate levels (H(3) = 8.597, p = 0.035) before and after treatment with microalgae. However, the ANOVA indicated that there were no significant differences between the mean values of total phosphate uptake (p = 0.052) after treatment with microalgae. The results for pathogen loads in the wastewater samples indicated statistically significant differences between the mean values of total coliforms ((H(3) = 10.352, p = 0.015) as well as faecal coliforms (H(3) = 10.421, p = 0.015) before and after treatment with microalgae. We conclude that while our microalgae species were not effective in the removal of heavy metals from the dam water, they were nonetheless effective in the removal of microbial contaminants as well as excessive nutrients from wastewater.

Chemical Method for Recovery and Regeneration of Graphene Oxide.

Graphene oxide (GO) has been developed as a very effective medium for filtration and removal of microbial contaminants in fuel. GO is capable of filtering out microorganisms without needing micrometer and submicrometer pores for filtration. Our previous studies showed that microorganisms are attracted by GO and bind irreversibly to GO without promoting bacterial growth. Therefore, GO was tested as a filter medium to remove microorganisms in fuel. The characterization results showed that GO removed microbes in diesel fuel with >99% efficiency. However, the synthesis of GO using Hummers' method is labor intensive and a time-consuming. We present in this paper an economical, less labor intensive and a simple chemical approach to recover GO after it has been used as a filtration medium for the removal of microorganisms in fuels. In the GO recovery process, microbial and fuel contaminated GO is washed with hexane to remove any fuel from the GO sample. The hexane-washed GO is further washed with acetone and mixed with ethanol to kill and remove any microorganisms. After washing with ethanol, the GO sample is sonicated in water to remove impurities and re-establish the oxygen functionalities. The final recovered-GO (rec-GO) is obtained after removing water by rotary evaporation. The chemical characterization of rec-GO showed that rec-GO is similar in both chemical and physical properties compared to freshly synthesized-GO (as-syn-GO). Rec-GO was shown to perform similarly to as-syn-GO in filtration of biocontaminated fuel. We estimate that our rec-GO is at least 90% cheaper than high quality commercially available GO.

Algae Cultivation as Measure for the Sanitation of Organic Waste—A Case Study Based on the Alga Galdieria sulphuraria Grown on Food Waste Hydrolysate in a Continuous Flow Culture

Due to its growth under harsh acidic conditions, the microalga Galdieria sulphuraria may offer the opportunity to combine sanitation and the utilization of organic waste streams. To further deepen the knowledge of alternative waste treatment strategies that allow for holistic utilization, the control and removal of microbial contaminants via non-sterile heterotrophic G. sulphuraria on food waste hydrolysate were investigated in a continuous flow bioreactor culture. Furthermore, a substrate reservoir and harvested biomass were stored under non-sterile conditions over a period of 12 days. Despite the non-sterile conditions, the microbial load of the biomass could be kept under control. Neither the pathogen Salmonella sp. nor the coliform bacteria Escherichia coli could be found. Only nine counts per g of biomass were found for species belonging to Enterococcus spp., Enterobacteriacae, and moulds. Aerobic spore formers were counted with 2700 counts per g of biomass. Most of the aerobic mesophilic counts were formed by yeasts (1.5 × 106 vs. 1.3 × 106 counts per g biomass). The results revealed that, when using acidic growth conditions, contamination will not take over the culture; thus, the sterilization of waste materials can be skipped. It is assumed that such an approach can result in efficient processes for future waste-based bioeconomy strategies.

Decreasing hydraulic retention time of anaerobic membrane bioreactor: Effect on core genera and microbial contaminants removal

A pilot-scale (35 L) anaerobic membrane bioreactor (AnMBR) treating municipal wastewater was operated under decreasing hydraulic retention times (HRT) of 12 h, 10 h and 8 h, and evaluated for its performance and removal of bacterial cells. There was an increased variability in COD and bacterial cells removal when HRT was 8 h, and a positive net growth rate of potential pathogen-containing genera Mycobacterium sp. was reported when AnMBR was operated at HRT of 8 h. Specifically, metagenomic assembled genomes of opportunistic pathogenic Mycobacterium franklinii were reconstructed uniquely in the 8 h HRT effluent. In contrast, co-occurrence network results showed when the HRT was 10 h, the microbial interactions were higher and bacterial syntrophs and methanogens had a more prevalent role in the microbial network. Our findings suggest that an optimal HRT (10 h) is required to achieve stable AnMBR performance and removal of microbial contaminants from untreated municipal wastewater, and can facilitate proper sizing of AnMBR.

Nanoporous carbon from waste egg shells modified with copper-nanoparticles – An Efficient material for removal of microbial contaminants from polluted water

The paper examines the efficiency of nanoporous carbon modified with copper nanoparticles (nC@CuNPs) for the removal of microbial contaminants from polluted waters. The modified material was prepared by wet impregnation of the unmodified carbon material in a solution of as-prepared Cu-nanoparticles. The materials were characterized by UV-Visible Spectroscopy, Fourier Transform-Infrared (FTIR) Spectroscopy, and Thermogravimetric Analysis. The materials were then investigated for their ability to remove copper and lead using Atomic Absorption Spectroscopy (AAS), methylene blue using Ultraviolet-Visible (UV-Vis) Spectroscopy and microbial contaminants from simulated polluted water. The results showed that in addition to retaining its heavy metals (Cu and Pb), and methylene blue removal capacity, the modified material, nC@CuNPs was efficient in removing microbial contaminants (E. coli and Salmonella) from the polluted water. The study provides an avenue for the provision of easy access to a range of such water purification materials to the increasing world population and contributes towards meeting the United Nationals Sustainable Development Goals (UN SDGs).

Potential Use of Constructed Wetland Systems for Rural Sanitation and Wastewater Reuse in Agriculture in the Moroccan Context

Located in a semi-arid to arid region, Morocco is confronting increasing water scarcity challenges. In the circular economy paradigm, the reuse of treated wastewater in agriculture is currently considered a possible solution to mitigate water shortage and pollution problems. In recent years, Morocco has made significative progress in urban wastewater treatment under the National Wastewater Program (PNA). However, rural sanitation has undergone significant delays. Therefore, an alternative technology for wastewater treatment and reuse in rural areas is investigated in this review, considering the region’s economic, social, and regulatory characteristics. Constructed wetlands (CWs) are a simple, sustainable, and cost-effective technology that has yet to be fully explored in Morocco. CWs, indeed, appear to be suitable for the treatment and reuse of wastewater in remote rural areas if they can produce effluent that meets the standards of agricultural irrigation. In this review, 29 studies covering 16 countries and different types of wastewater were collected and studied to assess the treatment efficiency of different types of CWs under different design and operational parameters, as well as their potential application in agricultural reuse. The results demonstrated that the removal efficiency of conventional contamination such as organic matter and suspended solids is generally high. CWs also demonstrated a remarkable capacity to remove heavy metals and emerging contaminants such as pharmaceuticals, care products, etc. The removal of microbial contamination, on the other hand, is challenging, and does not satisfy the standards all the time. However, it can be improved using hybrid constructed wetlands or by adding polishing treatment. In addition, several studies reported that CWs managed to produce effluent that met the requirements of wastewater reuse in agriculture of different countries or organisations including Morocco.

Application of the Swimming Pool Backwash Water Recovery System with the Use of Filter Tubes.

During the operation of swimming pools, large losses of water from the backwash of swimming pool filters are observed. This water is often discharged into sewers or used to sprinkle sports grounds. The aim of the research was to design and build an installation for purification and recovery of backwash water (BWW). It consists of flocculation, pre-filtration, and ultrafiltration based on filter tubes and ozone disinfection. Backwash water treatment installation contributes to purification and improvement of water quality. The effectiveness of the removal of microbial contamination with the use of the system was over 99%. The high efficiency of removing physicochemical impurities was also achieved. Water turbidity was reduced from 96.9 NTU to 0.13 NTU. After using the system, the oxidability of water decreased from 6.26 mg O2∙dm−3 to 0.4 mg O2∙dm−3. When using the system, a reduction of total organic carbon by 80% was also noticed. After the treatment process, water meets the strict criteria and can be returned to the pool system of water as fresh water with parameters of supply water—directly to the overflow tank. It has been shown that up to 96% of water can be recovered with the technology. The cost comparison showed annual savings of over EUR 9000.

Evaluation sealing ability of an epoxy resin based sealer

The main aim of root canal therapy is the removal of microbial contaminants in conjunction with the total closure of the root canal system. Root canal sealers along with solid core material plays a major role in achieving the three-dimensional sealing of the root canal system. These sealers are binding agents which are used to adapt the rigid gutta-percha to canal walls and to fill up the voids, accessory canals and irregularities within the canal. Root canal sealers, although used only as adjunctive materials in the obturation of root canals, have been shown to influence the outcome of endodontic treatment. A perfect combination of sealing ability and biocompatibility is what an ideal root canal sealer should possess. This article discusses the current concepts in the usage of different sealers in endodontic therapy and their comparison in order to draw some clinical inferences.

The Possibilities of Using Ultrasonically Activated Streams to Reduce the Risk of Foodborne Infection from Salad

In this study, we investigated the effects of an ultrasonically activated stream (UAS) on the removal of microbial contaminants from spinach leaves. The microbial loads on samples cleaned with and without UAS were enumerated using the cell culture method and compared against unwashed samples on day 0 and day 6 after cleaning. The effects of UAS cleaning on leaf quality were also examined through both macroscopic and microscopic inspection, as well as measurement of the electrolyte leakage rate. Results showed that the microbial load on samples cleaned with UAS for 2 min was significantly lower on day 6 after cleaning than on those treated without ultrasound. Comparison between the cleaning effects of UAS for 40 s versus 2 min indicated that a cleaning duration of 2 min allowed sufficient time for UAS to disaggregate and detach the microbial contamination more effectively. In this case, the induction of bacteria into a viable but non-culturable state does not affect the shelf-life test results as much as it does with a 40 s clean. UAS cleaning for 2 min did not produce significant surface damage, which can affect overall leaf quality. These findings highlight the potential of UAS systems in the salad industry to improve the microbiological quality and shelf life of salads.

Evaluation sealing ability of a new polydimethyl siloxane sealer

The main aim of root canal therapy is the removal of microbial contaminants in conjunction with the total closure of the root canal system. Root canal sealers along with solid core material plays a major role in achieving the three-dimensional sealing of the root canal system. These sealers are binding agents which are used to adapt the rigid gutta-percha to canal walls and to fill up the voids, accessory canals and irregularities within the canal. Root canal sealers, although used only as adjunctive materials in the obturation of root canals, have been shown to influence the outcome of endodontic treatment. A perfect combination of sealing ability and biocompatibility is what an ideal root canal sealer should possess. This article discusses the current concepts in the usage of different sealers in endodontic therapy and their comparison in order to draw some clinical inferences.

Preparation and characterization of PAN nanofibers containing boehmite nanoparticles for the removal of microbial contaminants and cadmium ions from water

Nanofibers of polyacrylonitrile (PAN)/boehmite were prepared by electrospinning a homogeneous solution of PAN/DMF (dimethyl formamide). Enhancing the amount of boehmite nanoparticles (NPs) led to increase in the nanofibers' diameter. Samples had high pure water flux, which did not change significantly with boehmite concentration, but decreased with increasing electrospinning duration. Escherichia coli bacteria removal was remarkably more efficient, as it was enhanced from 72.33% to 97.37% with increase in the boehmite NPs' concentration from 0 to 10% wt. High bacterial removal efficiency could be attained by the large surface area of NPs, as well as the electrostatic force of attraction between NPs and microorganisms. The increase in boehmite concentration from 10 to 30 and 50% did not noticeably affect bacterial removal. Prolonging electrospinning time significantly enhanced bacteria removal. Hence, it was shown that 6-hour electrospinning of PAN/boehmite nanofiber layers composed of 50% boehmite led to 99.7%, 99.39%, 99.8%, and 74% E. coli, Staphylococcus aureus bacteria removal, particles' separation efficiency of 2 μm and cadmium adsorptivity, respectively, which were better than those obtained by using pure PAN nanofibers. E. coli bacterial removal efficiency of the sample was increased to 99.99% by repeating filtering four times. Considering the results, this PAN/boehmite nanofibers' membrane has potential application to purification of drinking water.

Impact of air-conditioning system disinfection on microbial contamination of passenger cars

An automobile air-conditioning (AC) system can be a source of microbiological contamination in a driver’s car. The aim of this study was to assess the level of microbial contamination before and after servicing of the automobile AC system, based on qualitative and quantitative analyses of bacteria and fungi isolated from the air, and to check the efficiency of different AC system cleaning methods in the removal of microbial contaminants. The study was carried out in 35 randomly selected cars, equipped with AC systems. In each car tested, viable bioaerosol samples were taken using a single-stage MAS impactor before and after servicing the AC systems. Four methods were used to disinfect the air-conditioning installations in the vehicles examined: ozonisation, application of chemical disinfectant using ultrasounds, manual application of chemical disinfectant foam and simultaneous ozonisation and application of chemical disinfectant foam. The bacterial and fungal concentrations in air samples before AC servicing in cars were between 7.5 × 101 cfu/m3 and 2.0 × 103 cfu/m3 and 4.0 × 101 cfu/m3 and 5.0 × 102 cfu/m3, respectively. Regardless of the disinfection method, after the AC service, a decrease in microbial concentrations was observed. The highest disinfection efficiency was observed for two methods: ozonisation combined with manual application of the chemical disinfectant into the air-conditioning system and spraying of the chemical disinfectant using ultrasounds.On the basis of the results obtained, it can be concluded that air-conditioning systems in cars should be regularly disinfected to eliminate microbiological contaminants, which may be the cause of adverse health effects on humans.

Bacteria and virus removal in denitrifying bioreactors: Effects of media type and age

Denitrifying bioreactors are simple, low-cost ecotechnologies designed to reduce nitrate (NO3−) present in septic tank effluent and drainage water. Recent studies indicate that, in addition to significant reduction in NO3− loads, these systems are also able to remove microbial contaminants from municipal wastewater. However, the removal of microbial contaminants in denitrifying bioreactors remains poorly characterised and factors that control removal in denitrifying bioreactors remain unexplored. In this study, the removal efficiency of faecal indicator bacteria Escherichia coli (E. coli) and total coliforms (TC) as a model for bacterial pathogens and F-specific RNA bacteriophage (FRNA bacteriophage) as a model for viruses was assessed for mesocosm-scale (∼700 L) bioreactors receiving municipal wastewater. Systems were filled with two different slow-release carbon sources: woodchip and coconut husk. The effect of media age on attenuation of microbial contaminants was assessed by comparing the performance of 8-year old systems with equivalent newly constructed woodchip and coconut husk bioreactors. Additionally, removal performance of these carbon substrates was compared to that of gravel, a non-carbon substrate commonly used in subsurface flow (SSF) constructed wetlands. Substantial reduction of E. coli, TC and FRNA bacteriophage from primary treated municipal wastewater was achieved in all bioreactors. Mean annual log10 removal efficiencies were similar between microbial indicators ranging from 1.4 to 1.9 for TC, 1.3 to 1.8 for E. coli and 1.3 to 2.0 for FRNA bacteriophage. All denitrifying bioreactors showed consistent year-round performance and long-term performance which did not markedly change in the ninth year of operation. The woodchip or coconut husk bioreactors achieved microbial effluent quality within the same range of log10 removal rates achieved in gravel-based systems. This suggests that denitrifying bioreactors, as well as reducing N loads, can effectively reduce microbial contaminants in wastewater, providing a complimentary disinfection role. Further research is needed to increase understanding of factors affecting removal of microbial contaminants in denitrifying bioreactors to support design of these systems for microbial contaminant removal.

Development of sustainable and reusable silver nanoparticle-coated glass for the treatment of contaminated water.

Water contaminants like pathogenic microbes and organic pollutants pose a serious threat to human and aquatic life forms; thus, there is an urgent need to develop a sustainable and affordable water treatment technology. Nanomaterials especially metal nanoparticles have extensive applications in wastewater treatment, but the recovery and aggregation of nanoparticles in solution is a major limitation. In the present work, green synthesized silver nanoparticles were covalently immobilized on a glass surface to prevent aggregation of nanoparticles and to enhance their applicability. Fourier transform infrared (FTIR) of silver nanoparticle (AgNP)-coated glass shows peaks of Si-O-Si, Si-O-C, and Ag-O at 1075 cm-1, 780 cm-1, and 608 cm-1 respectively which confirms the immobilization/conjugation of nanomaterial on glass surface. The surface morphology of immobilized AgNP was studied using scanning electron microscopy (SEM) which reveals nanoparticles are spherical and uniformly distributed on glass surface. The AgNP-coated glass was used for the removal of textile dyes in solution; the result indicates approximately 95% of textile dyes were removed after 5 h of treatment. Removal of microbial contaminants from Yamuna River was studied by optical density analysis and confirmed by fluorescence dye staining. The AgNP-coated glass was also studied for their reusability and the data indicates 50% removal of microbes up to the 5th cycle. To further enhance the applicability, the inhibition of bacterial biofilms were analyzed by dark-field illumination with a fluorescence microscope. Thus AgNP-coated glass can be used in the development of food/water storage containers and in textile industries.

A constructed wetland for treatment of an impacted waterway and the influence of native waterfowl on its perceived effectiveness

A constructed, variable-flow treatment wetland was evaluated for its ability to reduce microbial loads from the Banklick Creek, an impacted recreational waterway in Northern Kentucky. For this study, levels of traditional (Escherichia coli and enterococci measured by culture and molecular techniques) and alternative fecal indicators (infectious somatic and F+ coliphage, Clostridium spp. and Clostridium perfringens by culture), potential pathogens (molecular signal of Campylobacter spp.) as well as various microbial source tracking (MST) markers (human fecal marker HF183 and avian fecal marker GFD) were monitored during the summer and early fall through five treatment stages within the Banklick Creek Wetland. No difference in concentrations of traditional or alternative fecal indicators were observed in any of the sites monitored. Microbial source tracking markers were employed to identify sources of fecal contamination within the wetland. Human marker HF183 concentrations at beginning stages of treatment were found to be significantly higher (P value range: 0.0016–0.0003) than levels at later stages. Conversely, at later stages of treatment where frequent bird activity was observed, Campylobacter and avian marker (GFD) signals were detected at significantly higher frequencies (P value range: 0.024 to <0.0001), and both signals were strongly correlated (P = 0.0001). Our study suggests constructed wetlands are an effective means for removal of microbial contamination in ambient waters, but reliance on general fecal indicators is not ideal for determining system efficacy or assessing appropriate remediation efforts.

Prodigiosin–Iron-Oxide–Carbon Matrix for Efficient Antibiotic-Resistant Bacterial Disinfection of Contaminated Water

Cheap and efficient bioactive materials capable of producing potable water are in high demand. We synthesized bioactive prodigiosin-conjugated iron-oxide-activated carbon composite ([Ac]F@Fe3O4–PG) for the effective removal of microbial contaminants without biofilm formation. The disinfection effect of [Ac]F@Fe3O4–PG was investigated against antibiotic-resistant Escherichia coli and Bacillus cereus. The reactive oxygen species, glutathione concentration, and intracellular leakages assay, zeta potential, atomic force microscopy, scanning electron microscopy, and fluorescence microscopy were performed to understand the mechanistic route of bacterial disinfection. Results demonstrate the bacterial cell membrane damage due to the surface charge neutralization by cationic [Ac]F@Fe3O4–PG, thereby affecting the transport system of the cells. The generation of reactive oxygen species further triggered programmed bacterial cell death with apoptosis-like changes in cellular morphology. We demonstrate that the [Ac]F...

On using clay and nanoclay ceramic granules in reducing lead, arsenic, nitrate, and turbidity from water

New technology has provided a cheap and abundant access to nanoclay which has more prominent and efficient properties than clay. The aim of this research was a performance review of clay and nanoclay granules for the purpose of improving physicochemical as well as biological quality of water. To this end, clay granules and a 50% composition of clay and nanoclay with an average of a 5-mm diameter were made and placed in the 1000 °C furnace for 7 h. 150 g of any kind of granule was put in a closed system with presence of 300 ml of sample of synthesized contaminated water for 24 h. Then, heavy metals (lead and arsenic), anions (nitrate), turbidity, electrical conductivity and microbial contamination (coliforms) were measured. The clay and nanoclay granules had adsorbed the lead, respectively, with 0/4 and /44 mg/l by 80% and 88% yield. They have been almost effective in declining nitrate, arsenic, turbidity, and electrical conductivity, though ineffective in removal of microbial contamination. The results show that the adsorption yield for nanoclay is much higher than that for clay.

Microorganismsare responsible for the progress and persistence of inflammatory response of pulpal and periapical tissues have been well recognized. Endodontic treatment success depends mainly on the removal of microbial contamination from infected root canal. On one hand, bacterial count can be decreased by mechanical instrumentation of root canals, but on the other handcomplete removal of microorganism cannot be obtained without

Microorganismsare responsible for the progress and persistence of inflammatory response of pulpal and periapical tissues have been well recognized. Endodontic treatment success depends mainly on the removal of microbial contamination from infected root canal. On one hand, bacterial count can be decreased by mechanical instrumentation of root canals, but on the other handcomplete removal of microorganism cannot be obtained without

Comparative proteomic analysis of foodborne Salmonella Enteritidis SE86 subjected to cold plasma treatment

The increasing demand for high quality and safe food led to important technological innovations in food processing. Cold plasma appears as an emerging technology that has demonstrated efficiency in the removal of microbial contamination from fresh and minimally processed food. In this study, the proteomic profile of Salmonella Enteritidis SE86 subjected to cold plasma treatment was investigated. The number of viable S. Enteritidis SE86 cells was analyzed at different time intervals upon exposure to cold plasma and approximately 100 μg of S. Enteritidis SE86 protein extracts were analyzed by Multidimensional Protein Identification Technology (MudPIT). The results demonstrated that no significant changes in cell counts were detected for up to 20 min exposure to cold plasma, and 2 log reduction was achieved after 60 min. Overall, 1096 proteins were identified, with 249 detected only in plasma-treated samples, and 9 exclusive in non-treated control samples. The proteins uniquely detected in cold plasma-treated cells that showed higher abundance were glyoxalase I, ABC transporter substrate-binding protein and transcriptional activator OsmE, followed by some oxidoreductases. Proteins related with carbohydrate and nucleotide metabolism were mostly overexpressed in cold plasma treated cells, suggesting energy metabolism was increased.