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Role of lime treatment in the removal of bacteria, enteric viruses, and coliphages in a wastewater reclamation plant.

Lime flocculation/sedimentation in the first process unit of a 4,500-m3/day wastewater reclamation plant reduced numbers of microorganisms extensively when operated at pH 11.2. The efficiency was much less at lower pH values, and some bacteria even multiplied at pH 9.6. Data on reduction in the number of microorganisms in the lime treatment and subsequent units indicate that inactivation by hydroxide alkalinity plays an important role in the efficiency of lime treatment. Reductions in the numbers of enteric viruses were higher than those of coliphages, enterococci, and total plate and coliform bacteria, which indicate that lime treatment can be monitored by means of coliphage and conventional bacteriological tests. This paper illustrates the valuable role of high-pH lime treatment in reducing the load of pathogenic microorganisms on subsequent units, including ultimate disinfection processes, which is important in the multiple safety barrier concept of wastewater reclamation processes.

Bacteria↗

The effect of coagulation on the toxicity and mutagenicity of reclaimed municipal effluents.

The objectives of this work were the assessment of the effectiveness of coagulation on the reclamation of secondary effluents and the evaluation of the quality of reclaimed waters by the examination of their ecotoxic and mutagenic properties. Aluminum coagulants resulted in higher removal of organic content, than iron coagulant, reaching up to 40%; the removal of heavy metals, such as zinc and copper was enhanced by the addition of a low strength anionic flocculant. The toxicity of pre-concentrated samples to the bacteria Vibrio fischerii was related to the heavy metal content, especially zinc and copper, indicating the significance of the metals bioavailability and their potential interactive effects. The secondary effluents exhibited mutagenic effects on strain TA 98; these effects were increased during coagulation with ferric chloride (both in absence and presence of flocculant). However, the addition of aluminum coagulants resulted in a decrease of mutagenic potential of secondary effluents, due to the extended removal of organic matter.

Aliivibrio fischeri↗

A transcriptional regulator of the LuxR-UhpA family, FlcA, controls flocculation and wheat root surface colonization by Azospirillum brasilense Sp7.

Genetic complementation of a spontaneous mutant, impaired in flocculation, Congo red binding, and colonization of root surface, led to the identification of a new regulatory gene in Azospirillum brasilense Sp7, designated flcA. The deduced amino acid sequence of flcA shared high similarity with a family of transcriptional activators of the LuxR-UphA family. The most significant match was with the AgmR protein, an activator for glycerol metabolism in Pseudomonas aeruginosa. Derivatives of Sp7 resulting from site-directed Tn5 mutagenesis in the flcA coding sequence were constructed by marker exchange. Characterization of the resulting mutant strains showed that flcA controls the production of capsular polysaccharides, the flocculation process in culture, and the colonization of the root surface of wheat. This study provides new information on the genetic control of the mechanism of plant root colonization by Azospirillum.

Amino Acid Sequence↗

Structure-function characterization and optimization of a plant-derived antibacterial peptide.

Crushed seeds of the Moringa oleifera tree have been used traditionally as natural flocculants to clarify drinking water. We previously showed that one of the seed peptides mediates both the sedimentation of suspended particles such as bacterial cells and a direct bactericidal activity, raising the possibility that the two activities might be related. In this study, the conformational modeling of the peptide was coupled to a functional analysis of synthetic derivatives. This indicated that partly overlapping structural determinants mediate the sedimentation and antibacterial activities. Sedimentation requires a positively charged, glutamine-rich portion of the peptide that aggregates bacterial cells. The bactericidal activity was localized to a sequence prone to form a helix-loop-helix structural motif. Amino acid substitution showed that the bactericidal activity requires hydrophobic proline residues within the protruding loop. Vital dye staining indicated that treatment with peptides containing this motif results in bacterial membrane damage. Assembly of multiple copies of this structural motif into a branched peptide enhanced antibacterial activity, since low concentrations effectively kill bacteria such as Pseudomonas aeruginosa and Streptococcus pyogenes without displaying a toxic effect on human red blood cells. This study thus identifies a synthetic peptide with potent antibacterial activity against specific human pathogens. It also suggests partly distinct molecular mechanisms for each activity. Sedimentation may result from coupled flocculation and coagulation effects, while the bactericidal activity would require bacterial membrane destabilization by a hydrophobic loop.

Amino Acid Sequence↗

Effect of chloroquine adsorption on acid reactivity of magnesium trisilicate.

Due to the adsorption of chloroquine by magnesium trisilicate, both the BP acid absorption test and the rate of hydrochloric acid uptake, as monitored by pH measurements, were significantly reduced. This reduction was dependent on the amount of chloroquine adsorbed, since multilayer adsorption produced relatively more suppressive effects than did monolayer adsorption. The presence of adsorbed chloroquine also decreased the amounts of magnesium released in an acid medium. The inhibition of the antacid property due to chloroquine adsorption may be attributed to the occupation of the reactive sites of the antacid surface by chloroquine and to a reduction of the surface of the antacid due to flocculation of the particles.

Adsorption↗

Swimming pool water--fractionation and genotoxicological characterization of organic constituents.

Swimming pool water treatment in general includes flocculation, sand filtration, and subsequent disinfection with chlorine. The continuous chlorination and input of organic material by bathers in combination with recirculation of the pool water leads to an accumulation of disinfection by-products (DBPs) in the water. Several DBPs have been identified as human carcinogens and are thought to cause allergic asthma. Therefore, the elimination of DBPs is one major aim of pool water treatment. Using membrane filtration as an alternative treatment technology, DBPs can be removed more efficiently than with conventional treatment. In this study membrane filtration and genotoxicity testing were applied for the characterization of pool water constituents and for the identification of the necessary molecular weight cut off of the membrane for an efficient elimination. Two-step membrane filtration revealed that most of the DBPs (as adsorbable organically bound halogen, AOX) were present in the molecular weight fraction below 1000 g/mol. The fraction below 200 g/mol contained more than 30% of the AOX. The distribution of the dissolved organic carbon (DOC) across the fractions was similar to that of the AOX. The genotoxicity was found to be strongest in the low-molecular weight fraction. Thus, considerable DBP removal by membrane treatment requires membranes with low-molecular weight cut offs down to 200 g/mol. The comprehensive elimination of the genotoxic compounds requires further treatment steps.

Adsorption↗

Multilaboratory evaluation of methods for detecting enteric viruses in soils.

Two candidate methods for the recovery and detection of viruses in soil were subjected to round robin comparative testing by members of the American Society for Testing and Materials D19:24:04:04 Subcommittee Task Group. Selection of the methods, designated "Berg" and "Goyal," was based on results of an initial screening which indicated that both met basic criteria considered essential by the task group. Both methods utilized beef extract solutions to achieve desorption and recovery of viruses from representative soils: a fine sand soil, an organic muck soil, a sandy loam soil, and a clay loam soil. One of the two methods, Goyal, also used a secondary concentration of resulting soil eluants via low-pH organic flocculation to achieve a smaller final assay volume. Evaluation of the two methods was simultaneously performed in replicate by nine different laboratories. Each of the produced samples was divided into portions, and these were respectively subjected to quantitative viral plaque assay by both the individual, termed independent, laboratory which had done the soil processing and a single common reference laboratory, using a single cell line and passage level. The Berg method seemed to produce slightly higher virus recovery values; however, the differences in virus assay titers for samples produced by the two methods were not statistically significant (P less than or equal to 0.05) for any one of the four soils. Despite this lack of a method effect, there was a statistically significant laboratory effect exhibited by assay titers from the independent versus reference laboratories for two of the soils, sandy loam and clay loam.

Enterovirus↗

Histology, histochemistry and fine structure of the lacrimal and nictitans gland in the South American armadillo Chaetophractus villosus (Xenarthra, Mammalia).

The anatomical, histological, histochemical and ultrastructural characteristics of the lacrimal gland (LG) and nictitans gland (NG) of the armadillo Chaetophractus villosus were described. The histochemical and histological features of both glands in male and female adult animals were compared. The tissues were processed with conventional techniques for light and transmission electron microscopy. Fixed specimens were submitted to a battery of tests for glycans, glycosaminglycans, glycoconjugates, proteins, and lipids. The LG of the armadillo may be considered within the set of glandulae lacrimales superior in which primates, carnivores, perisodactyls and artiodactyls are included. The localization of the NG was similar to that of other mammals. Lacrimal and NG were histologically and histochemically identical. The secretory endpieces consisted of three cell types: (1) Mucous cells (MC) with different types of mucous secretory granules with neutral and sialic acid-containing glycoconjugates (GCs). (2)Seromucous cells (SMC) showing a variety of moderately electron dense secretory granules with flocculent material with carboxylated acidic, neutral, and sialic acid-containing GCs. Intercellular canaliculi with junctional complexes and basolateral intercellular spaces were frequent. (3) Serous cells (SC) with electron dense secretory granules. Histochemically, they showed the strongest reaction for proteins and neutral, weakly acid and carboxylated acidic GCs. The epithelium of the intra- and inter-lobular excretory ducts showed secretory activity, junctional complexes, and wide basolateral intercellular spaces with lateral folds. The endpieces and ducts were surrounded by myoepithelial cells. The stroma was characterized by fenestrated endothelium, unmyelinated axons, and abundant plasma cells. MC, SMC, and the duct system were richly innervated by hypolemmal nerve terminals.

Animals↗

Comparison of dewaterability and floc structure of synthetic sludge with activated sludge.

This work compared the appearance, dewaterability, floc size, fractal dimensions derived from free-settling test and light-scattering test, and detailed structural information of floc interior including porosity, Sierpinski carpet fractal dimension, and the fractal dimension of the pore boundaries of a synthetic sludge and an activated sludge. The present synthetic sludge could probe the change in filterability and in fractal dimensions extracted from small angle light scattering test and from free-settling test after conditioning, however, failed to reproduce the detailed structural information of sludge flocs. The use of specific synthetic sludge depends on the field of interest. For instance, the present synthetic sludge is not appropriate to simulate the intrafloc transport of solute owing to its incapability to reproduce the detailed floc structure or to its change after conditioning.

Flocculation↗

Influence of calcium, magnesium, or potassium ions on the formation and stability of emulsions prepared using highly hydrolyzed whey proteins.

Oil-in-water emulsions (4 wt % soy oil) containing 4 wt % whey protein hydrolysate (WPH) (27% degree of hydrolysis) and different levels of calcium, magnesium, or potassium chloride were prepared in a two-stage homogenizer. Other emulsions containing 4 wt % WPH but including 0.35 wt % hydroxylated lecithin and different levels of the above minerals were similarly prepared. The formation and stability of these emulsions were determined by measuring oil droplet size distributions using laser light scattering and by confocal scanning laser microscopy and a gravity creaming test. Both lecithin-free and lecithin-containing emulsions showed no change in droplet size distributions with increasing concentration of potassium in the range 0-37.5 mM. In contrast, the diameter of emulsion droplets increased with increasing calcium or magnesium concentration >12.5 mM. Emulsions containing hydroxylated lecithin were more sensitive to the addition of calcium or magnesium than the lecithin-free emulsions. Storage of emulsions at 20 degrees C for 24 h further increased the diameter of droplets and resulted in extensive creaming in emulsions containing >25 mM calcium or magnesium. It appears that both flocculation and coalescence processes were involved in the destabilization of emulsions induced by the addition of divalent cations.

Calcium↗

Effect of protection and repair of injury of mitochondrial membrane-phospholipid on prognosis in patients with dilated cardiomyopathy.

We have already proved that the mitochondrial membrane-phospholipid (MMP) injury changes of peripheral lymphocytes in patients with heart failure can be used as an injury indicator of myocardia, and are related to the long-term prognosis. In the present study, MMP localization of the peripheral lymphocytes was performed by modified Demer's tricomplex flocculation method, and we compared the changes, after classification, between the pre-treatment and the 12-week post-treatment, of coenzyme Q10 (Co.Q10) and captopril in 61 hospitalized patients with dilated cardiomyopathy (DCM). They were followed up for 16.1 +/- 7.8 months (mean). The results showed that compared with the placebo, Co.Q10 and captopril could significantly protect against and repair MMP injury and improve the heart function of patients with DCM after 12 weeks, and the 2-year survival rate rose significantly by 72.7% for Co.Q10, and 64.0% for captopril, vs 24.7% for placebo. As for Longrank test, X2 equals 4.660 and 6.318, respectively, with both p < 0.05. The aforementioned results indicate that MMP injury of peripheral lymphocytes can predict the prognosis of the patients with DCM, thus the protection and repairment of MMP injury can improve the life-quality and prolong the life-span of the patients.

Antihypertensive Agents↗

Stimulation of methanogenesis in a laboratory scale UASB reactor treating domestic sewage by Fe(0) application.

The effects of application of zero valence Fe (Fe(0)) on the anaerobic digestion of sewage was investigated using two laboratory scale UASB reactors. One reactor had Fe(0) addition in a container found midway along the recycling loop. The other one was a control reactor. In a test run period of 76 days, the Fe(0) application significantly increased the CH, yield by 8.7% and decreased the effluent COD concentration by 21.0% relative to the control reactor. A decrease of the H, concentration of biogas and the CODs/CODt ratio in effluent by Fe(0) application were observed. The obtained results imply that the methanogenesis and COD removal efficiency of the UASB reactor were stimulated by Fe(0) application. The higher performance of the reactor with Fe(0) application arises from the integrated functions of Fe(0) or its ionic state as donor of H2, macronutrient, and flocculant. This study showed that the supply of Fe(0) to a UASB can improve the methanogenesis and the overall COD removal of a UASB reactor treating low-strength domestic waste water.

Bacteria, Anaerobic↗

Reducing sediment and phosphorus in tributary waters with alum and polyacrylamide.

The Salton Sea is the largest inland water body in California, covering an area of 980 km(2). Inflow to the Salton Sea (1.6 km(3) yr(-1)) is predominately nutrient-rich agricultural wastewater, which has led to eutrophication. Because internal phosphorus release from the bottom sediments is comparatively low and external phosphorus loading to the Salton Sea is high, reduction of tributary phosphorus is expected to reduce algal blooms, increase dissolved oxygen, and reduce odors. Removing both dissolved phosphorus and phosphorus-laden sediment from agricultural drainage water (ADW) should decrease eutrophication. Both alum and polyacrylamide (PAM) are commonly used in wastewater treatment to remove phosphorus and sediment and were tested for use in tributary waters. Laboratory jar tests determined PAM effectiveness (2 mg L(-1)) for turbidity reduction as cationic > anionic = nonionic. Although cationic PAM was the most effective at reducing turbidity at higher speeds, there was no observed difference between the neutral and anionic PAMs at velocity gradients of 18 to 45 s(-1). Alum (4 mg L(-1) Al) reduced turbidity in low energy systems (velocity gradients < 10 s(-1)) by 95% and was necessary to reduce soluble phosphorus, which comprises 47 to 100% of the total P concentration in the tributaries. When PAM was added with alum, the anionic PAM became ineffective in aiding flocculation. The nonionic PAM (2 mg L(-1)) + alum (4 mg L(-1) Al) is recommended to reduce suspended solids in higher energy systems and reduce soluble P by 93%.

Acrylic Resins↗

The subcellular pathology of shock in trauma patients: studies using the immediate autopsy.

In summary, our immediate autopsy program provides a new tool for investigating the pathophysiologic effects of shock and trauma at the cellular and subcellular levels. By minimizing the time delay between death and tissue sampling with this technique, we have demonstrated the feasibility of validly applying the refinements of electron microscopy, histochemistry and analytical biochemistry to human tissue. Qualitative, semi-quantitative and quantitative data with these techniques have been integrated with clinical, physiologic and chemical studies on these patients during life. Cell injury produces an altered steady state of metabolism within the cell, evidence of which is seen in altered ultrastructure. If the injury is too severe, the cell will pass the "point-of-no-return," at which time the changes in the cell are no longer compatible with life and the cell dies and undergoes necrosis. Although the initiating injury and the patterns of the altered steady state may vary, once the cell has passed the "point-of-no-return," the patterns of cell injury regardless of the initial insult, are similar. We believe that the cellular patterns seen in patients dying from shock and trauma are remarkably similar to those produced by hypoxic tissue injury in experimental systems. Tissue from control patients in whom ischemic injury due to episodes of hypotension did not occur show good morphologic preservation with normal mitochondria and other cell organelles. Tissue from patients who have experienced acute shock consisting of a period of hypotensive ischemia show changes in the mitochondria and ER compatible with the experimental picture of hypoxia: i.e., dilated ER, with loss of ribosomes, swelling of mitochondria and the appearance of flocculent densities in the mitochondria. Tissues taken from the patients who had experienced repeated episodes of shock, whom we designated as those in "chronic shock," showed changes paralleling the acute changes, but also showed much evidence of autophagocytosis as a) the cells attempted to achieve a lower metabolic requirement in order to survive, and b) they attempted to "clean-up" and remove altered and damaged organelles and debris from previous bouts with sublethal ischemic injury. We hope that the increased knowledge of tissue and cellular injury obtained by the immediate autopsy will provide a means of integration, hypothesis formation and testing of the vast knowledge of cell biology and pathology, and the opportunity for developing in the human the potential for testing new hypotheses in model systems resulting in immediate and innovative feedback for the patient in terms of diagnosis, functional monitoring and treatment.

Adult↗

Large scale dielectrophoretic construction of biofilms using textile technology.

Arrays of microelectrodes for AC electrokinetic experiments were fabricated by weaving together stainless steel wires (weft) and flexible polyester yarn (warp) in a plain weave pattern. The cloth produced can be used to collect cells in low conductivity media by dielectrophoresis (DEP). The construction of model biofilms consisting of a yeast layer on top of a layer of M. luteus is demonstrated, using polyethylenimine (PEI) as the flocculating agent. This technique offers an alternative to the formation of biofilms at microelectrodes made by photolithography, and would allow the construction of biofilms with defined internal architectures by DEP at much larger scales than was possible previously. Furthermore, the flexibility of the cloth would also allow it to be distorted or folded into various shapes.

Biocompatible Materials↗

Dissimilatory iron reduction and odor indicator abatement by biofilm communities in swine manure microcosms.

Animal waste odors arising from products of anaerobic microbial metabolism create community relations problems for livestock producers. We investigated a novel approach to swine waste odor reduction: the addition of FeCl(3), a commonly used coagulant in municipal wastewater treatment, to stimulate degradation of odorous compounds by dissimilatory iron-reducing bacteria (DIRB). Two hypotheses were tested: (i) FeCl(3) is an effective source of redox-active ferric iron (Fe(3+)) for dissimilatory reduction by bacteria indigenous to swine manure, and (ii) dissimilatory iron reduction results in significant degradation of odorous compounds within 7 days. Our results demonstrated that Fe(3+) from FeCl(3) was reduced biologically as well as chemically in laboratory microcosms prepared with prefiltered swine manure slurry and limestone gravel, which provided pH buffering and a substrate for microbial biofilm development. Addition of a 1-g liter(-1) equivalent concentration of Fe(3+) from FeCl(3), but not from presynthesized ferrihydrite, caused initial, rapid solids flocculation, chemical Fe(3+) reduction, and E(h) increase, followed by a 2-day lag period. Between 2 and 6 days of incubation, increases in Fe(2+) concentrations were accompanied by significant reductions in concentrations of volatile fatty acids used as odor indicators. Increases in Fe(2+) concentrations between 2 and 6 days did not occur in FeCl(3)-treated microcosms that were sterilized by gamma irradiation or amended with NaN(3), a respiratory inhibitor. DNA sequences obtained from rRNA gene amplicons of bacterial communities in FeCl(3)-treated microcosms were closely related to Desulfitobacterium spp., which are known representatives of DIRB. Use of iron respiration to abate wastewater odors warrants further investigation.

Animal Husbandry↗

Influence of anaerobic digestion on particle surface charge and optimal polymer dosage.

Anaerobic digestion leads to significant changes of the sludge structural matrix, affecting particle size distribution and dewaterability. The surface charge, determined by means of streaming current, can be effectively used to monitor the complex phenomena of floc disruption, colloid formation and chemical conditioning. To study the relation between surface charge and optimal dosage, two different cationic polyelectrolytes were used: Praestol 644, polymer with high molecular weight and low charge density, and Poly Dadmac, with relatively low molecular weight but high charge density. The optimal Poly Dadmac dosage strictly met the value required to neutralise particle charge whereas the optimal dosage of Praestol 644 indicated that the relevant charge was considerably lower than the one required for charge neutralisation. Mechanisms of action are therefore clearly different. Another objective was to investigate the changes of dewatering characteristics of secondary sludge during anaerobic digestion tests at different inoculum content by determining charge density, and optimal polymer dosage. The optimal polyelectrolyte dosage remains almost constant during digestion at high inoculum, but a significant increase in the first period is observed at low inoculum, thus suggesting that the release of colloidal and supracolloidal material from sludge affects dewaterability, especially in the first days of digestion.

Anaerobiosis↗

Localization of a phosphoglycolipid in Mycoplasma membranes using specific anti-lipid-antibodies.

A phosphoglycolipid, presumably identical to glyceryl-phosphoryldiglycosyl diglyceride, is the main component of the membrane glycolipids of Mycoplasma mycoides subsp. capri. It is immunologically active. Anti-phosphoglycolipid antibodies were induced in rabbits by intravenous injection of the flocculated complexes of methylated bovine serum albumin with a mixture of the phosphoglycolipid and the auxiliary lipids, phosphatidyl-choline and cholesterol. The specificities of the antibodies directed against the phosphoglycolipid, are due to both the phosphate and carbohydrate moieties of the lipid molecule. Anti-phosphoglycolipid antibodies were detected in the sera of rabbits intravenously immunized with intact M. mycoides subsp. capri. The intravenous method of immunization was chosen in order to select for a response to surface antigenic determinants. Anti-phosphoglycolipid antibodies specifically reacted with intact organisms and isolated membranes of M. mycoides subsp. capri, as shown by complement fixation and agglutination tests. The antigenic determinants of the phosphoglycolipid are mainly located on the outer membrane surface. It is concluded that the antigenic determinants of the phosphoglycolipid in intact M. mycoides subsp. capri significantly contribute to the surface architecture of mycoplasma membranes.

Acholeplasma laidlawii↗