Removal Of Microorganisms Research Articles

Metals, heavy metals and microorganism removal from spent filter backwash water by hybrid coagulation-UF processes

Abstract Spent filter backwash water (SFBW) reuse has attracted particular attention, especially in countries that experience water scarcity. It can act as a permanent water source until the water treatment plant is working. In this study, the concentrations of Fe, Al, Pb, As, and Cd with total and fecal coliform (TC/FC) were investigated in raw and treated SFBW by hybrid coagulation-UF processes. The pilot plant consisted of pre-sedimentation, coagulation, flocculation, clarification, and ultrafiltration (UF) units. Poly-aluminum ferric chloride (PAFCL) and ferric chloride (FeCl3) were used as pretreatment. The results showed that, at the optimum dose of PAFCl, the average removal of TC and FC was 88 and 79% and with PAFCl-UF process, it reached 100 and 100%, respectively. For FeCl3, removal efficiency of TC and FC were 81 and 72% and by applying FeCl3-UF process, it reached 100 and 100%, respectively. In comparison with FeCl3, PAFCl showed better removal efficiency for Fe, Pb, As, and Cd, except residual Al concentration. Coagulation-UF process could treat SFBW efficiently and treated SFBW could meet the US-EPA drinking water standard. Health risk index values of Fe, AL, Pb, AS, and Cd in treated SFBW indicate no risk of exposure to the use of this water.

Electro-coagulation treatment of raw and autoclaved landfill leachate with aluminum electrodes: case study of Djebel Chakir (Tunisia)

Landfilling is a common practice worldwide for solid waste management. The leachate generated at landfill sites contains various organic and inorganic pollutants while it should be treated properly. In this study, the electrocoagulation (EC) process was recognized for its simplicity and effectiveness which was used for the treatment of leachate from the Djebel Chakir landfill site in northern Tunisia. In addition, we investigated the effect of microorganisms (e.g., bacteria, fungi, spore) on sludge production by the application of autoclaving treatment on raw leachate. The application of low current density (15 mA/cm2) within 2 h of treatment and using Al-Al electrodes revealed significant improvement of performance when autoclaving was applied. The chemical oxygen demand (COD) and nitrogen removal increased from 39 to 64% and from 13 to 30%, respectively. The sludge volume was reduced from 40 to 10%, and thus, its handling and disposal costs would be significantly decreased. The energy consumption rate was stable after 40 min of treatment at about 0.8 kWh/kg COD removed. Our study shows that removal of microorganisms by autoclaving prior to the EC process is promising for landfill leachate treatment. However, since autoclaving is far from being practical and cost-effective at full-scale plant, research on coupling EC with an alternative disinfecting process might be of great interest.

Protective function of interleukin 27 in colitis-associated cancer via suppression of inflammatory cytokines in intestinal epithelial cells

ABSTRACTNumerous studies have demonstrated that inflammation contributes to a variety of cancer formation, among them, colitis-associated cancer (CAC) represents a typical inflammation-related cancer. Interleukin 27 (IL-27) has been demonstrated to play an important role in inflammation-related disease. The effect of IL-27 in intestinal inflammation is controversial and its role in CAC is not elucidated yet. In our present study, we found that IL-27 has protective function in murine model of CAC through suppression of inflammatory cytokines in intestinal epithelial cells (IECs). IL-27Rα (WSX-1) deficiency promotes the CAC development in mice, which is driven by enhanced tumor cell proliferation, more intensive myeloid-derived suppressor cells (MDSC) accumulation in colon lamina propria and higher level of inflammatory cytokines and chemokines in IECs. The levels of IL-6, TNF-α, GM-CSF and CXCL1 triggered in vitro by toll-like receptor ligands are significantly upregulated in IECs from WSX-1 KO mice. Removal of commensal microorganism through antibiotic treatment in mice to eliminate TLR ligands deprives the protective function of IL-27 on CAC tumor growth. Thus, IL-27 suppresses CAC formation through an anti-inflammation mechanism targeting IECs and in turn resists the tumorigenesis. Hence, our study explained how IL-27 exerts its anti-inflammatory function on epithelial cells to fight against chronic-inflammation-associated cancer, which might provide new insights on the potential therapeutic strategies for cancer.

Multifunctional hybrid porous filters with hierarchical structures for simultaneous removal of indoor VOCs, dusts and microorganisms.

Air purification often requires multiple layers of filters with different functions to remove various air pollutants, which lead to high pressure drop, high air flow path and frequent filter replacement. In this work, a novel multifunctional Ag@MWCNTs/Al2O3 hybrid filter with a depth-type hierarchical structure for simultaneous removal of fine particles, microorganisms and VOCs was designed and fabricated. The novel hybrid air filter showed leading air purification performances to date, achieving 82.24% degradation of formaldehyde at room temperature, 99.99% formaldehyde degradation at 55 °C and complete retention of indoor airborne microorganisms. The complete particle retention rate (100% retention) based on the most penetrating particle size (MPPS, aerodynamic diameter ≦300 nm) of Ag@MWCNTs/Al2O3 was achieved at an only 35.60% pressure drop compared with the pristine Al2O3 filter, leading to the highest quality factor (Qf) ever reported. Furthermore, the Ag@MWCNTs/Al2O3 hybrid filter showed excellent water repellency (water contact angle of 139.6 ± 2.9°), prolonging the service life of the filters and improving the air purification efficiency. The novel Ag@MWCNTs/Al2O3 hybrid filter exhibits remarkable air purification performance in both laboratory synthetic conditions as well as in the "real world" and shows great promise as an effective single replacement for multiple layers of air purifying filters.

Electro coagulation for the pathogenic and microorganism removal from Oued El-Harrach, Algeria wastewater

Electro coagulation for the pathogenic and microorganism removal from Oued El-Harrach, Algeria wastewater

Fabrication of nickel nanoparticles-embedded carbon particles by solution plasma in waste vegetable oil

Solution plasma is a unique method which provides a direct discharge in solutions. It is one of the promising techniques for various applications including the synthesis of metallic/non-metallic nanomaterials, decomposition of organic compounds, and the removal of microorganism. In the context of nanomaterial syntheses, solution plasma has been utilized to produce carbon nanoparticles and metallic-carbon nanoparticle systems. The main purpose of this study was to synthesize nickel nanoparticles embedded in a matrix of carbon particles by solution plasma in one-step using waste vegetable oil as the carbon source. The experimental setup was done by simply connecting a bipolar pulsed power generator to nickel electrodes, which were submerged in the waste vegetable oil. Black powders of the nickel nanoparticles-embedded carbon (NiNPs/Carbon) particles were successfully obtained after discharging for 90 min. The morphology of the synthesized NiNPs/Carbon was investigated by a scanning electron microscope, which revealed a good dispersion of NiNPs in the carbon-particle matrix. The X-ray diffraction of NiNPs/Carbon clearly showed the co-existence of crystalline Ni nanostructures and amorphous carbon. The crystallite size of NiNPs (through the Ni (111) diffraction plane), as calculated by the Scherrer equation was found to be 64 nm. In addition, the catalytic activity of NiNPs/Carbon was evaluated by cyclic voltammetry in an acid solution. It was found that NiNPs/Carbon did not show a significant catalytic activity in the acid solution. Although this work might not be helpful in enhancing the activity of the fuel cell catalysts, it is expected to find application in other processes such as the CO conversion (by oxidation) and cyclization of organic compounds.

The mechanism for bacteriophage f2 removal by nanoscale zero-valent iron

Nanoscale zero-valent iron (NZVI) has shown excellent performance for pathogenic microorganism removal but the inactivation mechanism has not been understood clearly enough. In this study, the bacteriophage f2 removal by NZVI under aerobic and anaerobic conditions was investigated, and various factors involved in f2 removal were analyzed in detail, including the ion products of NZVI (Fe(II), Fe(III)), solid phase products, the reactive oxygen species (ROS), O2 and H+. In addition, the morphologies of bacteriophage f2 during reaction were observed. The results showed that the removal efficiency of bacteriophage f2 was much higher under aerobic conditions than that in anaerobic systems, and oxygen and pH were determinants for f2 removal. The oxidation of Fe(II) was a fundamental step and played a significant role in bacteriophage f2 removal, especially in the aerobic systems. In the presence of oxygen, the virus removal was attributed to the generation of ROS (namely ·OH and ·O2-) and the oxidized iron, in which the ROS (·OH and ·O2-) made a predominant contribution. And the adsorption of iron oxide was responsible for the removal in oxygen depleted circumstance. In the anaerobic system, the virus removal was mainly attributed to the interaction between NZVI and bacteriophage f2. Besides, from the perspective of TEM images, the virus removal was mainly attributed to the damage of infective ability by NZVI at the initial stage of reaction, and later the virus was inactivated by the ROS generated.

A silica/polyvinyl alcohol membrane suitable for separating proteins

Membrane separation at low temperatures is a favorable method for concentrating and purifying heat-sensitive biological molecules, for example, proteins. This results in that the production of an ultrafiltration membrane with long-term durability and low cost is receiving extensive attention. A new type of ultrafiltration membrane suitable for concentrating or separating proteins or macromolecules from small molecules such as salts or organic compounds is obtainable by directly mixing water glass solution with polyvinyl alcohol solution followed by soaking in aqueous H2SO4 solution. The molecular weight cut off of the ultrafiltration membrane was estimated to be >36,000 and <45,000 Da while its water permeability is reasonably high. The measured results of the critical mechanical properties, including tensile force, strength, length and elongation of the membrane indicated that its long-term durability should be good. Soaking the silica/polyvinyl alcohol membranes in 2 mol/L aqueous H2SO4 solution is very vital to improve the rejection rate of proteins investigated. The new and advanced preparation method of the membrane has a short, efficient and low cost operating process. The silica/polyvinyl alcohol membrane may also be applicable to the removal of microorganisms in water.

Large scale tertiary filtration – results and experiences from the discfilter plant at the Rya WWTP in Sweden

This paper summarizes the results and experiences from the full-scale discfilter plant at the Rya WWTP. In 2010 the WWTP was extended with post-denitrification and a discfilter plant for tertiary filtration of the effluent in order to meet the new discharge limits of 10 mg total nitrogen and 0.3 mg/l of total phosphorus. The disc filters receive effluent from both the moving bed biofilm reactor (MBBR) and the secondary settlers. The disc filters are equipped with filter cloths with 15 µm pore openings. The concentration of suspended solids was generally kept below 5 mg/l and total phosphorus was &amp;lt;0.2 mg/l for approximately 60% of the days during the experimental period, with generally lower concentration of particles in the effluent from the disc filters during the summer. The mass load of suspended solids from the MBBR was higher compared to the load from the secondary settlers but this did not influence the concentration of suspended solids in the effluent from the disc filters. The particles in the MBBR effluent are larger and easier to filter compared to the secondary settler effluent which contain a larger number of small particles. During passage through the disc filters, some particles break-up leaving a larger number of particles (1–5 µm) in the effluent. Due to their small mass, this does not affect the effluent suspended solids concentration significantly. The removal of indicator and pathogenic microorganisms was only marginal. Since the discfilter plant has been placed in operation, the operational strategies have improved (e.g. more frequent cleaning of the filter cloths) which has increased the treatment capacity. The study demonstrates successful operation of a large discfilter plant with large variation in flow and particle loading.

Pollutant and Microorganism Removal From Water by Hydrodynamic Cavitation

Hydrodynamic cavitation can effectively remove organic pollutants and microorganisms from water. Organic compound degradation and water disinfection removal rate is related to reaction time and operating temperature. Removal rate can be improved by increasing the reaction time or raising the operating temperature. Under our experimental conditions, the removal rate of colority, COD and petroleum pollutants was 80.0%, 72.13% and 70.00%, respectively. In addition, Escherichia coli removal rate was higher than 99.99%. As a new water treatment process, hydrodynamic cavitation can be utilized alone or in combination with other water treatment processes, showing broad application prospects.

Use of DiaCell modules for the electro-disinfection of secondary-treated wastewater with diamond anodes

Abstract In this work, the disinfection of the effluent of the secondary treatment of a municipal wastewater treatment plant is studied using two stacks of commercial electrochemical cells powered with very low current densities (0.14–10 A m−2), in order to prevent the formation of chlorates and perchlorates during the electrolysis. Results demonstrate that this technology is robust and efficient and it can attain the complete disinfection of wastewater even at very low current densities. These low current densities are high enough to produce hypochlorite and chloramines (when ammonium is present in solution), being the disinfection process more efficient when the concentration of chloramines is higher. Therefore, the presence of hypochlorite together with higher concentrations of chloramines significantly improve the removal of microorganisms. In comparing the two stacks studied in this work, it was obtained that commercial DiaCell stacks containing bipolar connected electrodes are more efficient than those containing monopolar-connected electrodes for the disinfection. Differences are explained in terms of the higher cell voltage applied in that stack (higher current density in bipolar stack) that results in (1) an improved reduction of nitrates to ammonium (BDD cathode in bipolar stack) with the latter formation of chloramines as the main positive effect and (2) in the increase in the power consumed as the primary negative consequence.

Consider Microfiltration and Ultrafiltration Membranes for Water Treatment

Microfiltration and ultrafiltration have gained rapid acceptance as processes that provide reliable and high‐level particle, turbidity, and microorganism removal.

Adhesion resistant chitosan coated iron oxide polyacrylonitrile mixed matrix membrane for disinfection of surface water

AbstractBACKGROUNDSurface water possesses numerous microbial pathogens due to domestic disposal and poor sanitation. Most of the available conventional disinfection techniques are cost intensive and energy consuming. Being cost effective and environmentally friendly, membrane separation proves to be a better disinfection technology. However, fouling is the major challenge of this technology reducing its throughput. This study highlights preparation of fouling resistant chitosan coated iron oxide polyacrylonitrile (PAN) mixed matrix membrane (MMM) for disinfection of surface water.RESULTSIn this work, antimicrobial and anti‐adhesive properties of MMM are explored for disinfection of pond water with high organic load. Significance of incorporating nanoparticles and a coating of chitosan on removal of microorganisms was investigated. Adsorption of Escherichia coli on MMM was quantified and confirmed by FTIR. Improved antimicrobial properties of MMM against Escherichia coli was evident by a wider halo zone (7 cm). Up to 99.9% removal efficiency of microorganisms was attained. The membrane permeability was restored by simple cleaning with distilled water.CONCLUSIONThe MMM developed not only exhibited strong antimicrobial efficiency but also showed significant anti‐adhesive property making it a suitable candidate for purification of surface water. © 2016 Society of Chemical Industry

Bacterial inactivation and degradation of organic molecules by titanium dioxide supported on porous stainless steel photocatalytic membranes

Abstract A novel integrated photocatalysis/microfiltration hybrid system based on the use of TiO2 immobilized by filtration on porous stainless steel supports has been demonstrated to provide a good efficiency in the removal of bacteria for water disinfection applications. A synergistic effect derived of the physical removal of microorganisms coupled to its photocatalytic inactivation was proved to be achieved. The membrane pore size and the TiO2 loading were found to play a significant role on the efficiency of the process and the value of the transmembrane pressure. An optimal value of 8.5 g·m−2 TiO2 supported over the membranes provides good photocatalytic activity keeping the transmembrane pressures in the range of 1.5–2 bar. Moreover the photocatalytic activity of the membrane was proved to have as an additional advantage the possibility of the simultaneous oxidation of the chemical pollutants present in the feed water. Continuous operation of the photocatalytic membrane reactor in dead-end configuration confirms the accumulation of bacteria on the membrane leading to an increase in the transmembrane pressure, whereas the photocatalytic functionality demonstrated a significant inactivation of the retained cells, confirming the feasibility of the hybrid process for biofouling control.

Life cycle assessment comparison of photocatalytic coating and air purifier.

This article presents a comparison of 2 very different options for removal of undesirable microorganisms and airborne pollutants from the indoor environment of hospitals, schools, homes, and other enclosed spaces using air purifiers and photocatalytic coatings based on nano titanium dioxide (TiO2 ). Both products were assessed by life cycle assessment (LCA) methodology from cradle-to-grave. The assessment also includes comparison of 2 different nano TiO2 production technologies, one by continuous hydrothermal synthesis and the other by a sulfate process. Results of the study showed a relatively large contribution of photocatalytic coatings to reducing the effects of selected indices in comparison with an air purifier, regardless of which nano TiO2 production method is used. Although the impacts of the sulfate process are significantly lower compared to those of hydrothermal synthesis when viewed in terms of production alone, taken in the context of the entire product life cycle, the net difference becomes less significant. The study has been elaborated within the Sustainable Hydrothermal Manufacturing of Nanomaterials (SHYMAN) project, which aims to develop competitive and sustainable continuous nanoparticle (NP) production technology based on supercritical hydrothermal synthesis. Integr Environ Assess Manag 2016;12:478-485. © 2016 SETAC.

Ozonation and UV254 nm radiation for the removal of microorganisms and antibiotic resistance genes from urban wastewater

Conventional wastewater treatment has a limited capacity to reduce antibiotic resistant bacteria and genes (ARB&ARG). Tertiary treatment processes are promising solutions, although the transitory inactivation of bacteria may select ARB&ARG. This study aimed at assessing the potential of ozonation and UV254nm radiation to inactivate cultivable fungal and bacterial populations, and the selected genes 16S rRNA (common to all bacteria), intI1 (common in Gram-negative bacteria) and the ARG vanA, blaTEM, sul1 and qnrS. The abundance of the different microbiological parameters per volume of wastewater was reduced by ∼2 log units for cultivable fungi and 16S rRNA and intI1 genes, by∼3-4 log units, for total heterotrophs, enterobacteria and enterococci, and to values close or below the limits of quantification for ARG, for both processes, after a contact time of 30min. Yet, most of the cultivable populations, the 16S rRNA and intI1 genes as well as the ARG, except qnrS after ozonation, reached pre-treatment levels after 3days storage, suggesting a transitory rather than permanent microbial inactivation. Noticeably, normalization per 16S rRNA gene evidenced an increase of the ARG and intI1 prevalence, mainly after UV254nm treatment. The results suggest that these tertiary treatments may be selecting for ARB&ARG populations.

Biofiltration for stormwater harvesting: Comparison of Campylobacter spp. and Escherichia coli removal under normal and challenging operational conditions

Knowledge of pathogen removal in stormwater biofilters (also known as stormwater bioretention systems or rain gardens) has predominately been determined using bacterial indicators, and the removal of reference pathogens in these systems has rarely been investigated. Furthermore, current understanding of indicator bacteria removal in these systems is largely built upon laboratory-scale work. This paper examines whether indicator organism removal from urban stormwater using biofilters in laboratory settings are representative of the removal of pathogens in field conditions, by studying the removal of Escherichia coli (a typical indicator microorganism) and Campylobacter spp. (a typical reference pathogen) from urban stormwater by two established field-scale biofilters. It was found that E. coli log reduction was higher than that of Campylobacter spp. in both biofilters, and that there was no correlation between E. coli and Campylobacter spp. log removal performance. This confirms that E. coli behaves significantly differently to this reference pathogen, reinforcing that single organisms should not be employed to understand faecal microorganism removal in urban stormwater treatment systems. The average reduction in E. coli from only one of the tested biofilters was able to meet the log reduction targets suggested in the current Australian stormwater harvesting guidelines for irrigating sports fields and golf courses. The difference in the performance of the two biofilters is likely a result of a number of design and operational factors; the most important being that the biofilter that did not meet the guidelines was tested using extremely high influent volumes and microbial concentrations, and long antecedent dry weather periods. As such, the E. coli removal performances identified in this study confirmed laboratory findings that inflow concentration and antecedent dry period impact overall microbial removal. In general, this paper emphasizes the need for the validation of stormwater harvesting systems, namely, the testing of treatment systems under challenging operational conditions using multiple indicators and reference pathogens.

IMMUNITY TO RHODOCOCUS EQUI INFECTION IN HORSES

Rhodococcus equi is an opportunistic bacterium that commonly infects foals and immunocompromised patients. Due to the large economic lossesthat it can cause in the fi eld of horse breeding, the microorganism has been studied in details, including its immunological aspect. Within the humoral immunity, the most important immunoglobulins are those of the class G (IgG), produced as a response to the surface antigen associated with virulence (virulence associated protein A, VapA). IgG antibodies provide resistance to pneumonia in foals and have a dose dependent protective effect. In addition to them, the protective role of plasma is achieved through various cytokines. Cellular mechanisms are important for killing bacteria within the macrophage. Virulent strains which carry a plasmid with the gene for VapA stimulate the production of interferon gamma (IFN-γ), a key cytokine to kill these bacteria. Th e presence of IFN-γ is crucial for the removal of microorganisms from the lungs and prevention of formation of pulmonary granulomas. For the complete removal of bacteria cooperation of the humoral and cellular immunity is necessary. Particularly signifi cant is opsonization, which increases phagolysosomal fusion. Vaccination and application of hyperimmune plasma play a vital role in the treatment of disease. Only alive and virulent bacterium is capable of producing protective immunity in horses. Th e use of hyperimmune plasma in foals results in a lower percentage of sick animals and less severe clinical progression of the disease. Further research is needed in order to create a safe and effective vaccine.

Assessment of hardness, microorganism and organic matter removal from seawater by electrocoagulation as a pretreatment of desalination by reverse osmosis

Electrocoagulation (EC) process was used as an alternative pretreatment in order to assess its applicability to replace the conventional pretreatments used to mitigate membrane fouling prior to seawater desalination by reverse osmosis process, such as chemical coagulation, chlorination and scale inhibitors. Electrocoagulation was conducted in a batch cell using aluminum electrodes driven in the galvanostatic mode. Absorbance (UV254nm) and DOC were measured to follow the effectiveness of EC process for removing organic matter from seawater. Likewise, cultivable heterotrophic bacteria were enumerated to assess the disinfection ability of the process and total hardness was monitored. The influence of various operating parameters, namely mixing speed, current density, initial pH and inter-electrode distance, was investigated. The removal of organic matter from seawater by electrocoagulation was improved with higher current density and lower pH. Electrocoagulation removed 70.8% DOC, while absorbance abatement was 89.7% with a complete removal of microorganisms at high current density. Conversely, the abatement of total hardness was weak, about 10%, so that electrocoagulation could not be used as a softening process. Finally, experimental results showed the high potential of electrocoagulation as a pretreatment method to mitigate potential organic fouling and biofouling of reverse osmosis membrane owing to its ability to remove effectively dissolved organic matter and microorganisms from seawater.

Microorganism Removal from Ballast Water using UV Irradiation

Staphylococcus aureus (S. aureus) and Chlorella were selected as two differentreference microorganisms in ballast water. Water treatment static- and dynamicexperimentswere conducted for microorganism removal via a UV process. The purposewas to better understand UV irradiation technology potential for microorganism removal.Static results showed UV irradiation is better for S. aureus and Chlorella removal anda UV dosage of 36mJ/cm2 can achieve removal rates as high as 97.6% and 73.1%,respectively. Differences in microbial ecological characteristics and species created differentremoval curves. A higher UV dose for Chlorella removal was needed compared toS. aureus removal. Turbidity of the raw water also had great influence on UV irradiation.When turbidity was raised from 1–108NTU the removal effect of UV is reduced significantlyto approximately 32.2% and 44.2%, respectively. Dynamic experiments suggestedthe microbial removal rate could reach more than 90% at a low flow rate (15L/h).