Presence Of Turbidity Research Articles

Inactivation and injury assessment of Escherichia coli during solar and photocatalytic disinfection in LDPE bags

Solar disinfection (SODIS) of Escherichia coli suspensions in low-density polyethylene bag reactors was investigated as a low-cost disinfection method suitable for application in developing countries. The efficiency of a range of SODIS reactor configurations was examined (single skin (SS), double skin, black-backed single skin, silver-backed single skin (SBSS) and composite-backed single skin) using E. coli suspended in model and real surface water. Titanium dioxide was added to the reactors to improve the efficiency of the SODIS process. The effect of turbidity was also assessed. In addition to viable counts, E. coli injury was characterised through spread-plate analysis using selective and non-selective media. The optimal reactor configuration was determined to be the SBSS bag (t 50 = 9.0 min) demonstrating the importance of UVA photons, as opposed to infrared in the SODIS disinfection mechanism. Complete inactivation (6.5-log) was achieved in the presence of turbidity (50 NTU) using the SBSS bag within 180 min simulated solar exposure. The addition of titanium dioxide (0.025 g L −1) significantly enhanced E. coli inactivation in the SS reactor, with 6-log inactivation observed within 90 min simulated solar exposure. During the early stages of both SODIS and photocatalytic disinfection, injured E. coli were detected; however, irreversible injury was caused and re-growth was not observed. Experiments under solar conditions were undertaken with total inactivation (6.5-log) observed in the SS reactor within 240 min, incomplete inactivation (4-log) was observed in SODIS bottles exposed to the same solar conditions.

An in vitro evaluation of antifungal activity of bioaggregate

The aim of this study was to evaluate, in vitro, the antifungal effect of bioaggregate (BA) against Candida albicans by using the direct contact method. BA was tested freshly mixed and after 24-hour set on C. albicans. The tested BA was incubated with C. albicans in plastic tissue clusters for 1 hour, 24 hours, and 3 and 5 days. Aliquots of 0.1 mL were taken from each well at the end of the incubation periods and transfered to tubes containing 5 mL fresh Sabouraud broth. All tubes were vortexed and then incubated at 37°C and observed for the subsequent 5 days. Growth of the fungi was observed daily by the presence of turbidity in the tubes. The results were statistically analyzed by using Kaplan-Meier test. The freshly mixed and set BA had no antifungal effect at 1 and 24 hours of contact. Both mixes demonstrated complete fungicidal activity after 24 hours' contact. Statistical analysis showed a highly significant difference between the negative and positive control groups (P < .001) and a significant difference between the freshly mixed and 24-hour set BA groups (P < .001) at 24 hours. BA (freshly mixed and 24-hour set) was effective against C. albicans after 24 hours.

Compatibilidad visual y física de la furosemida en mezclas intravenosas para perfusión continua

Introduction Patients in the intensive care units simultaneously receive concomitantly many drugs, with limited venous accesses. Thus, several different perfusions must be administered jointly through the same catheter. Furosemide is a solution with no buffer capacity that is easily precipitated. In spite of the recommendation on its data sheet stating that it should not be used with other drugs, studies found in the bibliography suggest that it has physicochemical compatibility with other drugs. However, the concentrations studied do not always coincide with those used in the clinical practice. Objectives To study and verify the physical compatibility of furosemide in intravenous mixture. Material and method An experimental study in vitro, in which furosemide was mixed with 12 drugs at a 1:1 proportion was performed. A total of 40 samples were obtained and the following variables were evaluated at different intervals, 0, 15, 30, 60 and 120 min: ph of mixture, color changes, presence of turbidity and precipitation. To do so, visual observation procedures, ph measurements and spectrophotometer absorption at 450 and 620 nm were used. Results Forty samples, 13 simples, 12 doubles and 15 triples, were obtained. Those mixtures that did not show physical changes, pH variation and absorption variation were considered compatible. Conclusion Furosemide is physically compatible with bicarbonate solution, heparin, insulin, morphine and nitroglycerin and incompatible with amiodarone, cisatracurium, haloperidol, midazolam and urapidil.

Foraging behavior of bay anchovy larvae, Anchoa mitchilli

Foraging behavior of the bay anchovy larvae, Anchoa mitchilli was characterized by silhouette video photography. Swimming speed, pause frequency and duration, burst duration, reactive distance (RD), horizontal and vertical reaction angle (HRA, VRA), and length of the predation cycle were estimated over a range of sizes and stages of development. First feeding larvae displayed a distinct pause-travel search behavior that included horizontal rotation of their body to the right or left to scan a new volume of water. Pause duration was affected by light intensity in small larvae and significantly decreased in length of time as larvae grew (ANOVA, p < 0.01). Duration of swimming bursts between pauses was short (mean = 0.13 ± 0.03 s). Average swimming speeds increased with size from a mean of 0.50 ± 0.39 BL · s - 1 (body lengths) at first feeding to 2.25 ± 1.27 BL · s - 1 at 12 mm SL. Mean RD of bay anchovy larvae at 10 lux and corrected for vertical angle was 0.65 BL and increased to 0.92 and 1.00 BL at 100 and 250 lux, respectively. The average RD increased in the presence of turbidity from 0.65 to 0.83 BL at 10 lux. Reducing light (250, 100, 10 lux) affected the foraging behavior of the largest larvae (14-19 mm SL) especially at 10 lux where only one attack was observed with or without turbidity. The Horizontal attack angles (HRA) of larvae ranged from 0-114° with 78% of attacks taking place at angles between 20 and 70° while vertical reaction angles (VRA) of larvae ranged from 12-90° with 77% of attacks occurring at < 50°. The average length of the predation cycle decreased with increasing larval size from 2.4 s down to 1.34 s for larger larvae. Bay anchovy larvae frequently aborted attacks (33%) after reacting and approaching prey. Attack success was high even for small larvae (mean = 83%) and approached 100% in the largest size class.

The Effect of Bovine Serum Albumin on the Antifungal Activity of Mineral Trioxide Aggregate Cements

The aim of this study was to evaluate the effect of bovine serum albumin (BSA) on the antifungal effect of gray-colored MTA (GMTA) and white-colored MTA (WMTA) using a tube-dilution test. MTA preparations were tested freshly mixed and after 24 h on Candida albicans. The experiment was performed in 24-well culture plates. Fifty wells were used and divided into two experimental groups (freshly-mixed WMTA, freshly-mixed WMTA plus BSA, freshly-mixed GMTA, and freshly-mixed GMTA plus BSA) of 10 wells each and control groups of five wells each. Plates of Sabouraud dextrose agar mixed with C. albicans served as positive control and Sabouraud dextrose agar without C. albicans served as negative control. Fresh inoculate of C. albicans was prepared by growing an overnight culture from a stock culture. Aliquots of C. albicans were then taken from the stock culture and plated on the agar compound of the experimental and positive control group. All plates were incubated at 37°C for1h, 24 h, and 72 h. Growth of fungi was monitored daily by the presence of turbidity. Results showed the inhibitory effect of BSA on the antifungal effect of MTA cements during 24-h and 72-h incubation, whereas, there was no significant difference between 1-h incubation groups. It was concluded that the antifungal effect of freshly mixed MTA cements was decreased in the presence of BSA.

An Evaluation of Dentin's Effect on the Antifungal Activity of MTA Cements.

The aim of this study was to evaluate the effect of dentin on the antifungal activity of gray and white-colored MTA (GMTA, WMTA) using a tube-dilution test. MTA preparations were tested freshly mixed and after 24h on Candida Albicans (CA). The experiment was performed in 24-well culture plates. Fifty wells were used and divided into four experimental groups (freshly-mixed WMTA, freshly-mixed WMTA plus dentin powder, freshly-mixed GMTA, and freshly-mixed GMTA plus dentin powder) of 10 wells each and control groups of five wells each. Plates of Sabouraud dextrose agar mixed with CA served as positive control and Sabouraud dextrose agar without CA served as negative control. Fresh inoculate of CA was prepared by growing an overnight culture from a stock culture. Aliquots of CA were then taken from the stock culture and plated on the agar compound of the experimental and positive control group. All plates were incubated at 37°C for1h, 24h, and 72h. Growth of fungi was monitored daily by the presence of turbidity. Kruskal-Wallis test was used for statistical analysis. Results showed the inhibitory effect of dentin powder on the antifungal effect of MTA cements during 24h and 72h incubation periods, whereas, there was no significant difference between 1h incubation groups. The antifungal effect of freshly mixed MTA cements was decreased in the presence of dentin.

In vitro evaluation of antifungal effects of mineral trioxide aggregate and portland cement on Candida albicans.

Candida Albicans (CA) is by far the most common yeast of oral infections, including endodontic infections. The aim of this study was to evaluate and compare the antifungal effect of white-colored mineral trioxide aggregate (WMTA) and Portland Cement (PC) using a tube-dilution test. WMTA and PC were tested freshly mixed and after 24 h. The experiment was performed in 24-well culture plates. Fifty wells were used and divided into four experimental groups (freshly-mixed WMTA freshly-mixed PC, 24 h-set WMTA, and 24 h-set PC) of 10 wells each and control groups of five wells each. Plates of Sabouraud dextrose agar mixed with CA served as positive control and Sabouraud dextrose agar without CA served as negative control. Fresh inoculate of CA was prepared by growing an overnight culture from a stock culture. Aliquots of CA were then taken from the stock culture and plated on the agar compound of the experimental and control groups. All plates were incubated at 37°C for1h, 24 h, and 72 h. Growth of fungi was monitored daily by the presence of turbidity. Kruskal-Wallis test was used for data analysis. Findings showed that in the freshly mixed as well as 24 h-set WMTA and PC, fungal growth was observed during 1 h incubation; whereas by increasing the incubation time, no fungal growth was observed in 24 h and 72 h. It was concluded that WMTA and PC (freshly mixed and 24-h set) were effective against CA.

Evaluation of the antifungal effects of mineral trioxide aggregate materials

The aim of this study was to evaluate and compare the antifungal effect of white-coloured mineral trioxide aggregate (WMTA) and grey mineral trioxide aggregate (GMTA) using a tube-dilution test. MTA preparations were freshly mixed and tested after 24 h on Candida albicans. The experiment was carried out in 24-well culture plates. Fifty wells were used and divided into four experimental groups (freshly mixed WMTA, freshly mixed GMTA, 24 h-set WMTA and 24 h-set GMTA) of 10 wells each and control groups of five wells each. Plates of Sabouraud dextrose agar mixed with C. albicans served as positive control, and Sabouraud dextrose agar without C. albicans served as negative control. Fresh inoculate of C. albicans was prepared by growing an overnight culture from a stock culture. Aliquots of C. albicans were then taken from the stock culture and plated on the agar compound of the experimental and control groups. All plates were incubated at 37 degrees C for 1, 24 and 72 h. Growth of fungi was monitored daily by the presence of turbidity. Results showed that in the freshly mixed as well as 24 h-set MTA cements fungal growth was observed during 1-h incubation, whereas by increasing the incubation time, no fungal growth was observed in 24 and 72 h. It was concluded that MTA cements (freshly mixed and 24-h set) were effective against C. albicans.

Effect of NOM, turbidity and floc size on the PAC adsorption of MIB during alum coagulation

The effect of natural organic material (NOM) and turbidity on the powdered activated carbon (PAC) adsorption of the odour compound 2-methylisoborneol (MIB) was evaluated during alum coagulation. The character of the flocs, in terms of their size and fractal dimensions ( D f), was used to interpret the observed adsorption behaviour of MIB during the coagulation process. As the alum dose was increased, the adsorption of MIB decreased. This was determined to be due to the size of the flocs, with larger flocs incorporating PAC into their structure, reducing the efficiency of mixing, and the bulk diffusion kinetics for the MIB molecule. The presence of turbidity also reduced MIB adsorption due to the formation of larger flocs. The character of NOM was found to have a greater influence on the adsorption of MIB than the floc structure.

Reduction of Fulvic Acid in Drinking Water by Ferrate

Acting as a powerful oxidant, efficient coagulant, and effective disinfectant, ferrate is a good multifunctional agent for water and wastewater purification. In this study, some of these key aspects were studied for treating water containing fulvic acid, including the reduction efficiency of fulvic acid ~FA! in drinking water and the optimum conditions for reducing FA using ferrate prepared in the laboratory. Jar tests and pilot tests were employed in the studies and the results of FA reduction were analyzed spectrophotometrically. Ferrate in these tests exhibited good oxidation capacity on FA. The ultraviolet absorption ~UVA! of 2 mg/L FA in water can be reduced about 90% when the weight ratio of ferrate to FA was 12:1. Adsorption to and coprecipitation with Fe~OH!3 precipitate produced by ferrate decomposition can also result in additional FA reduction. In the presence of turbidity, ferrate can oxidize and adsorb simultaneously and over 95% of UVA was reduced with the same weight ratio of 12:1. Combining the application of ferrate and polyaluminum chloride ~PAC! or iron chloride (FeCl3) was more effective for FA reduction. The UVA of 2 mg/L FA was reduced 100% in synthetic drinking water by a joint treatment with 8 mg/L ferrate (FeO 42 by weight! and 0.8 mg/L PAC ~Al by weight! or 6 mg/L ferrate (FeO 42 by weight! and 0.8 mg/L Fe 31 ~Fe by weight!. The pilot test performed more effectively for FA reduction than did the jar test.

A comparison of large-scale electron beam and bench-scale 60Co irradiations of simulated aqueous waste streams

The effectiveness of using high energy electron beam irradiation for the removal of toxic organic chemicals from water and wastewater has been demonstrated by commercial-scale experiments conducted at the Electron Beam Research Facility (EBRF) located in Miami, Florida and elsewhere. The EBRF treats various waste and water streams up to 450 l min −1 (120 gal min −1) with doses up to 8 kilogray (kGy). Many experiments have been conducted by injecting toxic organic compounds into various plant feed streams and measuring the concentrations of compound(s) before and after exposure to the electron beam at various doses. Extensive experimentation has also been performed by dissolving selected chemicals in 22,700 l (6000 gal) tank trucks of potable water to simulate contaminated groundwater, and pumping the resulting solutions through the electron beam. These large-scale experiments, although necessary to demonstrate the commercial viability of the process, require a great deal of time and effort. This paper compares the results of large-scale electron beam irradiations to those obtained from bench-scale irradiations using gamma rays generated by a 60Co source. Dose constants from exponential contaminant removal models are found to depend on the source of radiation and initial contaminant concentration. Possible reasons for observed differences such as a dose rate effect are discussed. Models for estimating electron beam dose constants from bench-scale gamma experiments are presented. Data used to compare the removal of organic compounds using gamma irradiation and electron beam irradiation are taken from the literature and a series of experiments designed to examine the effects of pH, the presence of turbidity, and initial concentration on the removal of various organic compounds (benzene, toluene, phenol, PCE, TCE and chloroform) from simulated groundwater.

Behavior of organic polymers in drinking water purification

Synthetic organic polymers used to purify drinking water are severely limited in that their impurities and by-products harm human health. In this study, the undesired effects resulted from chlorination and the enhanced attenuation of toxic organic compounds in drinking water from using synthetic organic polymer cogulants were investigated.In the simulated drinking water purification processes, synthetic organic polymers were used as coagulant aids, reacted with a disinfectant( chlorine) and formed a large number of volatile organic compounds (VOCs).Chloroform and benzene which, are carcinogenic compounds, had the maximum formation potential.Experimental results indicated that the total formation potential of these disinfection by-products significantly increased in the presence of turbidity. On the other hand, adding organic polymers to the coagulation systems resulted in more extensive remove of toxic organic compounds and turbidity. In coagulation and flocculation processes, the formation of clay/polymer complexes can facilitate the removal of toxic organic compounds in contaminated water.

Arsenic removal by RO and NF membranes

RO and tight NF membranes prove equally effective in removing As species over a wide range of operational conditions.Bench‐scale experiments were performed to assess the effectiveness of reverse osmosis (RO) and nanofiltration (NF) membranes in removing arsenic (As) from synthetic freshwater and source water. The authors examined the effects of operational conditions (applied pressure and feedwater temperature) and solution chemical composition (As oxidation state, pH, and presence of co‐occurring inorganic solutes). Both As(V) and As (III) were effectively removed from synthetic freshwater by RO and tight NF membranes over a wide range of operational conditions. The relatively large molecular weight (&gt;125 g/mol) of the As species governed their separation behavior. Applied pressure had little effect on As removal, but an increase in feedwater temperature decreased As removal by a small percentage. Removals of As (III) and As(V) were comparable, with no significant preferential rejection of As(V) over As (III). Variations in solution pH from 4 to 8 also did not affect the removal of As species by the membranes tested, despite changes in the speciation and charge of As(V). Co‐occurring inorganic solutes had only a slight effect on As removal. Removal of As from source water was comparable to that obtained with synthetic freshwater, despite the presence of turbidity, natural organic matter, and a variety of co‐occurring solutes.

Virus removal from water and wastewater using membranes

Membranes are finding increasing application in disinfection processes for raw water and municipal effluent reuse. The efficiency of virus removal is vitally important if membranes are to become widespread in these applications. In particular the ability of microfiltration (MF) to adequately retain viruses is of interest. This paper describes experimental studies of poliovirus transmission through 0.2 μm microfiltration (MF) and 30 kD cut-off ultrafiltration (UF) membranes. Transmission was measured for both dead end and stirred conditions and for transmembrane pressure values of 25, 50, 100 and 200 kPa. Feed solutions containing virus only, virus in the presence of biomass ( E. coli) and virus in the presence of turbidity were used. It was found that UF membranes give complete rejection of virus and that MF membranes gave significant removals under appropriate conditions.

Determination of Total Pigments in Red Meats

ABSTRACTThe presence of turbidity in the aqueous extracts invalidated the results in the spectrophotometric determination of total pigments in meat. The present study showed that the turbidity was caused by certain protein and lipid fractions and was eliminated by the amphiphilic property of these compounds. For that purpose, the aqueous extract was treated with trichloroethylene; after stirring and centrifugation, a thin layer was observed in the interphase, together with a completely unclouded aqueous extract. This layer was formed by proteins, cholesterol, glycerides, and phospholipids. Values of total pigments are reported in different cuts of bovine, ovine and porcine meat.

Methods for testing the efficacy of ultraviolet light disinfection devices for drinking water

Ultraviolet (UV) light devices have been used in the disinfection of raw drinking water at the point of use, but the need for reliable fail‐safe devices has been demonstrated. A study was performed to establish test protocols that could be used to ensure adequate disinfection under adverse conditions, particularly in the presence of turbidity and color in the water. A test protocol was devised for fail‐safe light sensors by using a color or turbidity agent in the feed solution to reduce the UV dosage to the established minimum limit, 16 000 μW·s·cm‐2, in order to determine whether the fail‐safe device was properly calibrated and functional. Three commercial UV devices were tested with this method; one device was satisfactory, the second unit was set too low by a factor of 1.6, and the third unit was set too low by a factor greater than 2.

DIRECT ABSORPTANCE MEASUREMENT OF FLUORESCENT AND TURBID SAMPLES IN A 4 π GEOMETRY

ABSTRACTThe determination of optical absorption in turbid media requires optical integrators to collect all the light scattered by the sample. If under these measurement conditions the sample fluoresces, its emission is collected as scattered light by the integrator and produces a signal of the opposite sign to that of an absorption. The magnitude of this effect is a function of the luminescent quantum efficiency of the sample and the spectral response of the detector. The implications of the effects of fluorescence on the absorption measurements of turbid media are discussed, along with a method for direct measurement of absorptance in a 4 π geometry. In the presence of turbidity, the measurement of regular transmittance is not valid if obtained with very small angles of detection. It is perfectly valid, however, if a detection acceptance angle of 4 π steradians is used.

Determination of calcium in biologic material by the chloranilate method.

SummaryThe Ferro-Ham chloranilate procedure for determination of serum calcium has been investigated. Modifications of this procedure are presented for determination of urine and fecal calcium and ultramicro modification for determination of serum calcium is described. Presence of turbidity, apparently lipid in nature, in final solution constitutes a source of significant positive error in the chloranilate method for determination of calcium in serum. This turbidity can be removed by ether extraction. Results obtained by the chloranilate method have been compared with the Clark-Collip procedure.

Color Methodology in the Presence of Turbidity

Color Methodology in the Presence of Turbidity