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PubMed2004

Investigation of natural biofilms formed during the production of drinking water from surface water embankment filtration.

Populations of bacteria in biofilms from different sites of a drinking water production system were analysed. Polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) analyses revealed changing DNA band patterns, suggesting a population shift during bank filtration and processing at the waterworks. In addition, common DNA bands that were attributed to ubiquitous bacteria were found. Biofilms even developed directly after UV disinfection (1-2m distance). Their DNA band patterns only partly agreed with those of the biofilms from the downstream distribution system. Opportunistic pathogenic bacteria in biofilms were analysed using PCR and Southern blot hybridisation (SBH). Surface water appeared to have a direct influence on the composition of biofilms in the drinking water distribution system. In spite of preceding filtration and UV disinfection, opportunistic pathogens such as atypical mycobacteria and Legionella spp. were found in biofilms of drinking water, and Pseudomonas aeruginosa was detected sporadically. Enterococci were not found in any biofilm. Bacterial cell counts in the biofilms from surface water to drinking water dropped significantly, and esterase and alanine-aminopeptidase activity decreased. beta-glucosidase activity was not found in the biofilms. Contrary to the results for planktonic bacteria, inhibitory effects were not observed in biofilms. This suggested an increased tolerance of biofilm bacteria against toxic compounds.

Anti-Bacterial Agents↗
PubMed2004

Advanced phosphorus removal from membrane filtrates by adsorption on activated aluminium oxide and granulated ferric hydroxide.

The advanced phosphorus (P) removal by adsorption was studied for its suitability as a post-treatment step for membrane bioreactor (MBR) effluents low in P concentration and particle content. Two commercial adsorbents, granulated ferric hydroxide (GFH) and activated aluminium oxide (AA), were studied in batch tests and lab-scale filter tests for P adsorption in MBR filtrates. GFH showed a higher maximum capacity for phosphate and a higher affinity at low P concentrations compared to AA. Competition by inorganic ions was negligible for both adsorbents at the original pH (8.2). When equilibrium P concentrations exceeded 2 mg L(-1) in the spiked MBR filtrates, a precipitation of calcium phosphates occurred additionally to adsorption. During column studies the effluent criteria of 50 microgL(-1) P was reached after a throughput of 8000 bed volumes for GFH and 4000 for AA. Dissolved organic carbon appears to be the strongest competitor for adsorption sites. A partial regeneration and reloading of both adsorbents could be achieved by the use of sodium hydroxide.

Adsorption↗
PubMed2004

In-line coagulation with low-pressure membrane filtration.

The objectives were to investigate the effects of in-line coagulation on removal of natural organic matter (NOM) and turbidity and on fouling of membranes during ultrafiltration (UF). Coagulants were added prior to UF, without intermediate use of conventional processes for removal of particles. Synthetic and natural raw waters were examined. Charge neutralization, sweep floc, and under-dose conditions (with respect to conventional treatment) were all effective for removal of NOM and turbidity by UF. Most coagulation conditions resulted in decreased resistance to filtration and improved hydraulic removal of filter cake, including conditions that would be ineffective prior to conventional settling and rapid-filtration. Flocs that were produced under charge neutralization conditions and acidic under-dose conditions produced lower hydraulic resistance and were less compressible than for sweep floc conditions.

Filtration↗
PubMed2004

Identification and understanding of fouling in low-pressure membrane (MF/UF) filtration by natural organic matter (NOM).

An understanding of natural organic matter (NOM) as a membrane foulant and the behavior of NOM components in low-pressure membrane fouling are needed to provide a basis for appropriate selection and operation of membrane technology for drinking water treatment. Fouling by NOM was investigated by employing several innovative chemical and morphological analyses. Source (feed) waters with a high hydrophilic (HPI) fraction content of NOM resulted in significant flux decline. Macromolecules of a relatively hydrophilic character (e.g. polysaccharides) were effectively rejected by low-pressure membranes, suggesting that macromolecular compounds and/or colloidal organic matter in the hydrophilic NOM fraction may be a problematic foulant of low-pressure membranes. Moreover, the significant organic fouling that is contributed by polysaccharides and/or proteins in macromolecular and/or colloidal forms depends on molecular shape (structure) as well as size (i.e. molecular weight). More significant flux decline was observed in microfiltration (MF) compared to ultrafiltration (UF) membrane filtration. MF membrane fouling may be caused by pore blockage associated with large (macromolecular) hydrophilic molecules and/or organic colloids. In the case of UF membranes, the flux decline may be caused by sequential or simultaneous processes of surface (gel layer) coverage during filtration. Morphological analyses support the notion that membrane roughness may be considered as a more important factor in membrane fouling by controlling interaction between molecules and the membrane surface, compared to the hydrophobic/hydrophilic character of membranes. Membrane fouling mechanisms are not only a function of membrane type (MF versus UF) but also depend on source (feed) water characteristics.

Colloids↗
PubMed2005

Removal of iron and manganese using biological roughing up flow filtration technology.

The removal of iron and manganese from groundwater using biological treatment methods is almost unknown in Latin America. Biological systems used in Europe are based on the process of double rapid biofiltration during which dissolved oxygen and pH need to be strictly controlled in order to limit abiotic iron oxidation. The performance of roughing filter technology in a biological treatment process for the removal of iron and manganese, without the use of chemical agents and under natural pH conditions was studied. Two pilot plants, using two different natural groundwaters, were operated with the following treatment line: aeration, up flow roughing filtration and final filtration (either slow or rapid). Iron and manganese removal efficiencies were found to be between 85% and 95%. The high solid retention capability of the roughing filter means that it is possible to remove iron and manganese simultaneously by biotic and abiotic mechanisms. This system combines simple, low-cost operation and maintenance with high iron and manganese removal efficiencies, thus constituting a technology which is particularly suited to small waterworks.

Biodegradation, Environmental↗
PubMed2005

Filtration methods for recovery of Bacillus anthracis spores spiked into source and finished water.

Spores of Bacillus anthracis Sterne strain were recovered from 100ml and 1L volumes of tap and source waters using filtration through a 0.45um filter, followed by overnight culture on agar plates. In a set of experiments comparing sheep red blood cell (SRBC) plates with a chromogenic agar formulation designed by R & F Laboratories, with a spiking dose of 47 plate-enumerated spores in 100 ml tap water, the mean spore recoveries were 34.0 and 30.8 spores, respectively. When a spiking dose of 100 fluorescence activated cell sorter(FACS)-enumerated spores was used in 100 ml potable water, the average recovery with SRBC plates was 48 spores. Detection efforts with spiking doses of 35 and 10 spores in 1 L tap water were successful, but recovery efforts from spiked 1 L volumes of source water were problematic due to the concomitant growth of normal spore-forming flora. Recoveries were also attempted on 10 L volumes of tap water. For a spiking dose of 100 spores, mean recovery from six replicates was 11 spores (+/- 6.8, range 2-20), and for a spiking dose of 10 spores, mean recovery from six replicates was 2.3 spores (+/- 3.5, range 0-9). Efforts were also made to "direct detect" spores via polymerase chain reaction (PCR) on washes from filters. When spiking 534 spores in 100 ml, 9/9 replicates of spiked tap water, 6/6 source water replicates, and 0/3 unspiked controls were positive by lef PCR. When 534 spores were spiked into 1 L tap water, the lef PCR was unsuccessful; however, using the nested vrrA PCR resulted in 4/9 spiked samples, and 0/3 unspiked controls, testing positive. Our results indicate that an inexpensive and user-friendly method, utilizing filtration apparatus commonly present in many water quality testing labs, can readily be adapted for use in detecting this potential threat agent.

Bacillus anthracis↗
PubMed2006

Removal of some divalent cations from water by membrane-filtration assisted with alginate.

The removal of divalent metal ions from hard waters or galvanic wastewater by polymer-assisted membrane filtration using alginate was investigated. The ability of this natural polymer to form aggregates and gels in presence of metal ions was studied, in order to carry out metal removal by ultra or micro-filtration. Alginate titrations have shown the presence of amine groups in addition to carboxylates onto the polymer backbone. The binding properties of alginate with divalent cations have been studied, showing an increasing affinity for Ca2+ over Mg2+ as polymer concentration increases, and the relative affinity Pb2+ > or = Cu2+ > Zn2+ > Ni2+. The softening of hard natural waters was achieved successfully and easily, but needs an optimal alginate concentration approximately 4 x 10(-2) M. The alginate powder can be directly added to hard waters. Except for Ni2+, metal-removal was efficient. Polymer regeneration has shown that Cu2+-complexes are labiles.

Alginates↗
PubMed2002

Lamotrigine plus leukocyte filtration as a neuroprotective strategy in experimental hypothermic circulatory arrest.

BACKGROUND: Lamotrigine and leukocyte filtration seem to improve cerebral protection during experimental hypothermic circulatory arrest (HCA). This study was performed to evaluate whether their combined use may further improve cerebral protection. METHODS: Twenty-four pigs undergoing 75-minute period of HCA at 20 degrees C were randomly assigned to receive saline; lamotrigine (20 mg/kg) before HCA (L); or lamotrigine (20 mg/kg) before HCA plus leukocyte filtration before and after HCA (L + LF). RESULTS: Seven animals (87%) in the L + LF group, 4 (50%) in the L group, and 3 (37%) in the control group were alive on the seventh postoperative day. The median electroencephalogram burst recovery was 94% in the L + LF group (p = 0.024 versus control group), 81% in the L group, and 64% in the control group. Among the surviving animals, the median behavioral scores were 9, 9, and 6 at the seventh day, respectively (p = 0.005 between the L + LF group and the control group). The median histopathologic score was 14 in the L + LF group (p = 0.046 versus control group), 14.5 in the L group (p = 0.062 versus control group), and 21 in the control group. CONCLUSIONS: Lamotrigine has neuroprotective effect during HCA. The combined use of lamotrigine and LF may further improve the survival outcome.

Animals↗
PubMed1986

Compensation filtration in paediatric double contrast barium enema examinations.

A prospective study of double contrast barium enema examinations performed on 42 children aged 2.5-19 years (mean age 12.3 years) showed that compensation filtration improved the radiographic quality in 32 (76%) of the examinations; it also reduced radiation dosage in all patients. In no examination was the use of a filter deleterious. Compensation filtration is recommended for all paediatric double contrast barium enema examinations to improve radiographic quality and reduce radiation dosage.

Adolescent↗
PubMed1981

Effect of glass wool filtration on ultrastructure of human spermatozoa.

The results of this study strongly suggest that filtration by glass wool can induce damage to the membrane and acrosome of the heads of some spermatozoa in a population. It is possible that the potential fertilizing capacity of a population of human spermatozoa may be reduced as a consequence of these alterations, especially those to the acrosome. The results suggest that sufficient clinical applications of glass wool filtration in artificial insemination is the only way to evaluate both the potential benefits of this process and the potential drawbacks to efficiency that may be caused by a degree of ultrastructural damage.

Acrosome↗
PubMed1996

Glass wool column filtration versus mini-Percoll gradient for processing poor quality semen samples.

OBJECTIVE: To compare the quality and number of spermatozoa recovered from laboratory-induced severe oligozoospermic specimens processed by mini-Percoll gradient and glass wool column filtration. DESIGN: Both sperm-processing procedures were compared in similar sperm samples adjusted to contain equal low numbers of motile spermatozoa using either dilution (oligozoospermia) or with the addition of killed sperm (oligoasthenozoospermia). The spermatozoa processed by both procedures samples were evaluated for motility, response to hypo-osmotic swelling test, and the hemizona assay. PATIENTS: Five healthy fertile sperm donors. SETTING: Private Andrology Laboratory and University Hospital. MAIN OUTCOME MEASURE: Sperm motility, hypo-osmotic swelling test, and hemizona assay results determined the efficacy of the sperm-processing procedures. RESULTS: The concentration of sperm recovered after both procedures was not affected by either preparation or processing methods. Glass wool-processed sperm had higher motility in oligoasthenozoospermic samples, bound tightly to hemizonae in higher mean numbers, and demonstrated a higher percentage of membrane-intact spermatozoa in oligozoospermic samples. CONCLUSION: Laboratory-prepared oligozoospermic samples subjected to glass wool filtration yielded more functionally intact spermatozoa than mini-Percoll gradient processing.

Cell Separation↗
PubMed1993

Effect of atrial natriuretic peptide on urine flow and glomerular filtration during acute renal allograft rejection.

The effect of exogenous atrial natriuretic peptide (ANP) on urine excretion and glomerular filtration rate (GFR) during acute renal allograft rejection was evaluated in a canine model. Eight animals underwent simultaneous allotransplantation and unilateral native nephrectomy. No preoperative or postoperative immunosuppressive therapy was given. Acute renal function studies were performed on the allografts and companion, native kidneys following surgical exposure and mobilization on the third postoperative day. At reexploration, the allografts were found to be grossly enlarged (138 +/- 10 gm.) and contained moderate-to-marked perivascular interstitial infiltration. Glomerular filtration rate, determined by measurement of urinary inulin clearance, was significantly reduced from prenephrectomy baseline values (19 +/- 4 ml. per minute versus 32 +/- 5 ml. per minute, p < .05). During a 30 minute, intravenous ANP infusion, allograft urine flow rates increased from 1.4 +/- 0.5 ml. per minute to 3.3 +/- 0.4 ml. per minute (p < .01), and GFR increased from 19 +/- 4 ml. per minute to 24 +/- 4 ml. per minute (p < .05). During ANP infusion, mean arterial pressure declined from 136 +/- 7 mm. Hg to 116 +/- 7 mm. Hg (p < .05), and the hematocrit remained unchanged. These observations are consistent with previously described, ameliorative effects of ANP in other models of acute ischemic renal injury and provide an experimental basis for more extended studies examining the potential usefulness of ANP as adjunctive therapy in the treatment of acute renal allograft rejection.

Acute Disease↗
PubMed1988

The effect of intravesical pressure on glomerular filtration rate in patients with myelomeningocele.

Numerous investigators have demonstrated the development of hydronephrosis and renal deterioration in patients with myelomeningocele who have high pressure bladders. By drawing blood at sequential intervals during 99mtechnetium-diethylenetriaminepentaacetic acid renal scanning we are able to generate nuclide clearance curves that correlate well with glomerular filtration rate. Renal scanning is done most frequently with the bladder catheterized and left to gravity drainage. By filling the bladder under manometric control to a pressure of 35 to 40 cm. water we have followed routine scanning with continued blood sampling to generate nuclide clearance at low and high bladder pressures. In 5 myelomeningocele patients so studied we found consistent and significant decreases in glomerular filtration rate at high bladder pressures.

Adolescent↗
PubMed1988

Measurement of the plasma clearance of urographic contrast media for the determination of glomerular filtration rate.

Further experience with a new method to determine glomerular filtration rate is presented. The method depends on measurement by an x-ray fluorescence technique of the plasma disappearance of the injected iodine in standard nonionic radiographic contrast media used during excretory urography. The results of comparison of contrast clearance with 99m technetium-diethylenetriaminepentaacetic acid clearance in 33 cases showed excellent agreement with a correlation coefficient of 0.95. Reproducibility of the contrast clearance method was confirmed by repeated examination of 10 plasma samples at weekly intervals for 6 weeks, the results of which showed no significant differences. The contrast clearance technique for the measurement of glomerular filtration rate during excretory urography is simple, quick and accurate, and merits further development.

Adult↗
PubMed1986

Extreme unilateral hydronephrosis with normal glomerular filtration rate: physiological studies in a case of obstructive uropathy.

A 30-year-old man presented with massive left hydronephrosis caused by congenital stricture of the ureteropelvic junction. Glomerular filtration rate of the post-released kidney (inulin clearance and creatinine clearance) was preserved completely. Simultaneous individual kidney function tests showed the following values expressed as the ratio of post-obstructed to normal kidney: inulin clearance 142 per cent, urine flow rate 475 per cent, sodium clearance 221 per cent and urinary excretion of prostaglandin E2 617 per cent. Urinary osmolality was 257 and 791 mOsm./kg. in the obstructed and normal kidneys, respectively. Administration of indomethacin, a cyclo-oxygenase inhibitor, caused decreased urinary excretion of prostaglandin E2 in both kidneys, with drastic antinatriuresis manifested predominantly in the normal kidney. We conclude that the glomerular filtration rate may be preserved despite huge hydronephrosis, which suggests that the human kidney is salvageable even after a prolonged period of unilateral ureteral obstruction, and the contralateral normal kidney mitigates the volume losses from the obstructed kidney.

Adult↗
PubMed1985

Glomerular filtration response to acute ureteral obstruction in the dog.

In order to assess the glomerular filtration responses to acute ureteral obstruction in the dog we employed an established method that does not require timed urine collections. Our results show a 57 per cent increase in renal blood flow (baseline: 203.8 +/- 50.9 vs. 319 +/- 69.4 ml./min. at 105 minutes; no. = 7) that was associated with a monophasic decrease in filtration fraction to -70 per cent at 120 minutes (0.26 +/- 0.025 vs. 0.08 +/- 0.007) and an increase in ureteral pressure to 63.1 +/- 6.1 mm. Hg at 120 minutes. A biphasic GFR response was noted with an initial small increase (baseline: 32.5 +/- 7.5 vs. 36.3 +/- 11.0 ml./min. at 2 minutes) followed by a continual decline to -55 per cent at 120 minutes (to 14.5 +/- 2.6 ml./min.). This investigation has confirmed the results of micropuncture studies showing maintenance of GFR early after complete ureteral ligation.

Animals↗
PubMed2001

Extracellular enzyme activities during slow sand filtration in a water recharge plant.

Activities of the extracellular enzymes beta-glucosidase and phosphatase and bacterial densities were investigated during the filtration process at several sites in a groundwater recharge plant at the Ruhr river (Hengsen recharge plant in Schwerte. Germany). Low numbers of microorganisms and low levels of activity in this type of habitat, compared to most surface waters, caused methodological problems when determining microbial activity. In this study, fluorigenic model substrates, which enable hydrolytic rates as low as 1 nmol (L x h)(-1) to be measured, were used to determine extracellular enzyme activities. Highest activities were determined in surface water (107 nmol (L x h)(-1) for beta-glucosidase and 252 nmol (L x h)(-1) for phosphatase). which decreased during the filtration process in the gravel prefilter and the main sand filter until the end of subsurface flow (1.6 nmol (L x h)(-1) and 6.8 nmol (L x h)(-1), respectively). Similarly, bacterial numbers decreased from 3.4 x 10(6) to 0.29 x 10(6) cells mL(-1). These data showed that microbial activity within the prefilter and the shallow layers of the sand filter had the greatest impact on water quality. In addition to its involvement in the continuous purification of surface water, the microbial community in the sand filter probably acts as a biological buffer against ephemeral increases in the loads of organic matter and nutrients in the recharge plant.

Colony Count, Microbial↗
PubMed2001

Hydraulic effects on sludge accumulation on membrane surface in crossflow filtration.

Membrane filtration technology for application of wastewater treatment has been developing recently. In the application to wastewater treatment, it is major concern to remove cake layer on membrane surface effectively with crossflow shear stress. Hydraulic effect of sludge accumulation process on membrane surface in bubble and non-bubble driven crossflow filtration was studied. Maximum sludge accumulation. sludge accumulation rate, and lag phase were introduced to describe sludge accumulation process, and the effects of hydraulic conditions were clarified experimentally. Maximum sludge accumulation and sludge accumulation rate were dependent on aeration intensity, and were less depend on flow channel width and MLSS concentration. Their tendencies were explained by shear stress. Shear stress was thought to be the major hydraulic factor that influences them. Lag phase was dependent on aeration intensity, flow channel width, and MLSS concentration. A non-dimensional equation was proposed to explain dependencies of flow channel width based on consideration of hydraulic behavior of MLSS particles and shear stress.

Filtration↗