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PubMed1975

Wound cleansing by high pressure irrigation.

All traumatic wounds are contaminated to some degree by both soil and bacteria. Specific infection potentiating factors in soil impair the defenses of the tissue and invite infection. These factors are small in size and resist removal by low pressure irrigation. The efficiency of wound irrigation is markedly improved by delivering the irrigant to the wound under continuous high pressure. Irrigation of the wound with saline solution delivered at 15 pounds per square inch removed 84.8 per cent of the soil infection potentiating factors from the wound. The residual infection potentiating factors remaining in the wound did not significantly impair tissue defenses. On the basis of these experimental studies, clinical studies are now being initiated to test the therapeutic value of high pressure irrigation in traumatic wounds in humans.

Animals↗
PubMed1998

Floc stability and adhesion of green-fluorescent-protein-marked bacteria to flocs in activated sludge.

Wastewater is often treated using the activated sludge process. Flocculation and subsequent sedimentation of flocs are vital steps in this process that have direct influence on the quality of the effluent water from wastewater treatment plants. Since cells that remain free-living will decrease the quality of the effluent water it is important to understand the mechanisms of bacterial adhesion to flocs. The green fluorescent protein (GFP) was used as a cellular marker to study bacterial adhesion to activated sludge flocs in situ in sludge liquor. Cell surface hydrophobicity (CSH) was shown to be an important factor that determined the relative bacterial adhesion potential. High CSH correlated with high numbers of attached cells. However, the absolute adhesion of two test bacteria to different sludge flocs varied and could not be explained by the floc characteristics. Confocal laser scanning microscopy of GFP-marked cells showed their position in the floc matrix in situ. Hydrophobic cells attached not only on the surface but also within the floc, whereas hydrophilic cells did not. This indicates that cells may penetrate the flocs through channels and pores and increase the effective surface, which in turn makes the clarification of the wastewater effluent more efficient. The addition of polymers is common practice in wastewater treatment and was shown to increase bacterial adhesion to the flocs. A decrease in surface tension caused by addition of DMSO decreased adhesion, indicating the detrimental effect of surfactants on flocculation. An understanding of basic bacterial adhesion and aggregation mechanisms is important for the management and control of biotechnological wastewater treatment.

Bacterial Adhesion↗
PubMed2004

Steady flow and viscoelastic properties of lubricating grease containing various thickener concentrations.

The flow and viscoelastic properties of a lubricating grease formed from a thickener composed of lithium hydroxystearate and a high-boiling-point mineral oil were investigated as a function of thickener concentration. The flow properties of grease were measured using continuous shear rheometry, while the viscoelastic properties were measured using oscillatory shear measurements. The flow properties show that grease is a shear-thinning fluid with a yield stress that increases with thickener concentration. At concentrations of lithium hydroxystearate greater than 5% by volume, the storage modulus, G', was found to be greater than the loss modulus, G", with both moduli increasing with increasing thickener concentration, below this critical concentration G" was greater than G'. Slip at the wall of the measuring platens was a major problem encountered during the rheological measurement of grease, this is hardly surprising, and greases are designed to slip in their lubricating functions. Therefore the measuring platens were roughened by sandblasting and significantly higher yield values were recorded with the roughened geometries. Creep experiments were also performed. In the creep test, yield stresses of greases could be obtained. Zero shear viscosity was also calculated from the creep experiment and as a result viscosities over nine orders of magnitude were obtained. The power law index of the scaling law of the elastic modulus and yield stress with increasing volume fraction was found to be 4.7+/-0.2 suggesting that the flocculation of the particles that compose the grease is likely to be of the chemically limited aggregation variety.

Journal Article↗
PubMed2004

[Pilot test on oil field wastewater biotreatment with thermophilic microorganisms].

The thermophilic microorganisms (50-60 degrees C) are introduced and the contact oxidation technology is adopted to treat with the high temperature effluents from an oil field in this paper, which solves a problem that the effluents need to be cooled in routine biotreatment. The results of the pilot test show that the HRT of the biotreatment system adjusted to 8-18h can make CODCr of the effluents stable at 175-263mg/L and oil content under 10mg/L on condition that the temperature of the influents keeps at 60-65 degrees C, CODCr 300-590mg/L and the quality of the oil wastewater is greatly fluctuant. Flocculating process, then, can effectively flocculate and precipitate the suspending and residual chroma pollutant from the effluents of biotreatment and CODCr in the effluents of flocculating process can reduce to 136-229mg/L. And CODCr even reduces to under 150mg/L after flowing by sand and activated carbon filtration equipments. Under the high temperature condition, furthermore, combined stuffing is an ideal carrier for the thermophilic microorganisms.

Bacteria, Aerobic↗
PubMed2005

Removal of cosmetic ingredients and pharmaceuticals in sewage primary treatment.

Two physico-chemical processes, coagulation-flocculation and flotation, have been assessed for enhancing the removal of some selected pharmaceutical and personal care products (PPCPs) present in sewage. Eight compounds, representative of three main groups of PPCPs according to their physico-chemical properties, have been selected: lipophilic compounds (the synthetic musks Galaxolide and Tonalide), neutral compounds (the tranquillizer Diazepam and the antiepileptic Carbamazepine) and acidic compounds (the anti-inflammatories Ibuprofen, Naproxen and Diclofenac). During the coagulation-flocculation assays, the main parameters considered were the selection of the additives, their doses and the temperature of operation (12 or 25 degrees C). Musks-which are highly lipophilic and Diclofenac-with significant sorption affinity-were removed around 50-70% at both temperatures independently of the dose and type of coagulant used. However, the rest of the compounds, which are more hydrophilic, were affected to a lesser degree (with maximum reductions below 25%). The exceptions to this behavior were Carbamazepine and Ibuprofen, which were not removed under any condition tested. During the flotation assays, the parameters studied were the initial content of fat in wastewaters and temperature. Again, musks were removed to a greater degree (35-60%), followed by Diazepam (40-50%) and Diclofenac (20-45%) and, to a lesser extent, Carbamazepine (20-35%), Ibuprofen (10-25%) and Naproxen (10-30%). The best results were always obtained at 25 degrees C, although in some cases the operation at 12 degrees C gave similar results. The removal of musks and neutral compounds was higher in wastewaters with a high fat content (around 150 mgl(-1)).

Adsorption↗
PubMed2003

Treatment of cotton textile wastewater using lime and ferrous sulfate.

This technical note summarizes the results of a textile wastewater treatment process aiming at the destruction of the wastewater's color by means of coagulation/flocculation techniques using ferrous sulfate and/or lime. All the experiments were run in a pilot plant that simulated an actual industrial wastewater treatment plant. Treatment with lime alone proved to be very effective in removing the color (70-90%) and part of the COD (50-60%) from the textile wastewater. Moreover, the treatment with ferrous sulfate regulating the pH in the range 9.0+/-0.5 using lime was equally effective. Finally, the treatment with lime in the presence of increasing doses of ferrous sulfate was tested successfully, however; it proved to be very costly mainly due to the massive production of solids that precipitated.

Calcium Compounds↗
PubMed2004

Irreversible and reversible adhesion between virus particles and hydrolyzing-precipitating aluminium: a function of coagulation.

The infectivity of viruses (Qbeta, MS2, T4, and P1) after dosing virus-contaminated water with 4 types of aluminium coagulant was investigated. The concentrations of infectious viruses were determined after dissolving aluminium hydroxide flocs in alkaline solution. The concentration of infectious viruses did not recover to the initial value after a short floc-dissolution time (5 s). Although the infectious virus concentration increased as the floc-dissolution time was extended to 5 h, it did not recover fully. Irreversible adhesion between virus particles and aluminium coagulant is responsible for the insufficient recovery. We interpret this phenomenon as a virucidal activity of the aluminium coagulant. All tested aluminium coagulants (PACl, alum, and reagent grade aluminium chloride and aluminium sulfate) inactivated all types of viruses tested. PACl had the highest virucidal activity. The virucidal activity of aluminium coagulants was lower in river water, presumably owing to the presence of natural organic matter.

Adsorption↗
PubMed1991

The response of the three brood Ceriodaphnia test to fifteen formulations and pure compounds in common use.

The three brood Ceriodaphnia dubia test was carried out on fifteen formulations and pure compounds presently in general use in a variety of treatment processes or as reference toxicants. The most toxic substances (LC50 (based on survival/EC50 (based on total progeny) less than 10 mg/L) were metallic Cu, tertiary dodecyl mercaptan, an antioxidant TIA-RCO T-424, Cu(NO3)2.3H2O, K2Cr2O7, NALCO 7139--a flocculent, DOWFAX 2EP--a surfactant, TB-66--an algicide and ammonia. Exposure to these compounds elicited the same response from C. dubia for the two endpoints examined--survival and reproductive success. Two antimicrobials, PROXEL GXL and DOWICIL 75, and the surfactant sodium lauryl sulfate, were slightly toxic (LC50/EC50 less than 100 mg/L) for both endpoints studied. Two coagulants, NALCO 7109 and NALCO 8120 and a flocculent PERCOL 757 were practically nontoxic (LC50 greater than 100 mg/L) to slightly toxic (LC50 less than 100 mg/L) when the survival endpoint was examined, but were moderately toxic (EC50 less than 10 mg/L) to slightly toxic (EC50 less than 100 mg/L) when the endpoint of reproductive success was examined. These formulations and pure compounds had generally a declining effect on mean brood size, though there were exceptions to this observation as the broods progressed in number.

Animals↗
PubMed1951

Preliminary studies of the gastrointestinal tract with colloidal barium.

A stable colloidal suspension of barium sulfate has been developed and tested in roentgen examination of the gastrointestinal tract. The new material is rather distinctive in radiographic appearance and can usually be differentiated from simple barium-water mixtures by inspection of roentgenograms of the opacified stomach and small intestine. It usually affords a satisfactory demonstration of the mucosal folds of the stomach and duodenal bulb and is considerably more resistant to flocculation and precipitation by retained gastric secretions. In the small intestine, it has little tendency to undergo flocculation and fragmentation, and permits visualization of fine mucosal configurations with unusual clarity. Its motility is about the same as that of conventional suspensions. Air contrast colon examinations with the colloidal preparation exhibit a very uniform, opaque, and stable coating of the bowel wall and are more consistently satisfactory than when simple barium-water mixtures are used.

Barium↗
PubMed1987

[Concentration methods for the determination of phages in water].

The object of the present study was to find a suitable method for the concentration of phages, especially from drinking water. Five possible ways have been tested. The technique of centrifugation utilizing a phage pre-adsorption to a particular substance (CaHPO4) yielded recoveries up to 42%, whereas no useful results by filtration through paper and membrane filters were obtained. The application of frits after phage pre-adsorption to CaHPO4 resulted in recoveries up to 80%. The method of choice evidently is that of chemical precipitation (flocculation), which allowed to recover up to 100% of the used phages. It requires the least material and technical expense, too.

Centrifugation↗
PubMed2006

Innovative physico-chemical treatment of wastewater incorporating Moringa oleifera seed coagulant.

Moringa oleifera is a pan tropical, multipurpose tree whose seeds contain a high quality edible oil (up to 40% by weight) and water soluble proteins that act as effective coagulants for water and wastewater treatment. The use of this natural coagulant material has not yet realised its potential. A water extract of M. oleifera seed was applied to a wastewater treatment sequence comprising coagulation-flocculation-sedimentation-sand filtration. The study was laboratory based using an actual wastewater. Overall COD removals of 50% were achieved at both 50 and 100mg/l M. oleifera doses. When 50 and 100mg/l seed doses were applied in combination with 10mg/l of alum, COD removal increased to 58 and 64%, respectively. The majority of COD removal occurred during the filtration process. In the tests incorporating alum, sludge generation and filter head loss increased by factors of 3 and 2, respectively. These encouraging treatment results indicate that this may be the first treatment application that can move to large scale adoption. The simple water extract may be obtained at minimal cost from the presscake residue remaining after oil extraction from the seed. The regulatory compliance issues of adopting 'new materials' for wastewater treatment are significantly less stringent than those applying to the production of potable water.

Environmental Restoration and Remediation↗
PubMedDate not supplied

Capture of bacteria from fermentation broth by body feed filtration: a solved problem?

The direct capture of bacteria produced in high cell density fermentation by filtration is not possible once the milliliter-scale has been surpassed. Filtration in the presence of a filter aid (body feed filtration) constitutes a putative and scalable alternative, but only if conditions proposed by industry for large-scale filtration processes, namely, flow rates (for aqueous solutions) in the range of 500-1,500 L/(m(2) x h) and a filter aid concentration of <or=20 g/L, can be met. To this end several filter aids (grades of cellulose, diatomaceous earth, mixes thereof) were tested, albeit with no success. Capture and retention of bacteria was low (not possible in the case of cellulose), and the produced filter cakes were unstable and of low permeability. In the case of the diatomaceous earth close to 100% bacterial capture was possible, but only with filter aid concentrations that were 1 order of magnitude above the proposed limit. By using flocculating agents (Fe(3+)/Al(3+), PEI) either alone or in combination with diatomaceous earth and also the use of positively charged cellulose, bacteria capture could be achieved from several liters of cell suspension (OD(600) <or= 15) in filtration experiments adhering to the industrial recommendations. However, the bacteria were only weakly retained in such cakes and easily released by sudden pressure pulses. Satisfactory results were only obtained by filtration of the bacteria suspension at slightly alkaline pH (8.0, 50 mM Tris buffer) after treatment with sodium-activated bentonite (5 g/L) and PEI (50 mg/L) in the presence of 250 mM NaCl. In such cases 100% of the bacteria could reproducibly be captured in a filtration using 20 g/L of diatomaceous earth as filter aid. The thus produced filter cakes strongly retained the bacteria and showed good filtration performance. The procedure is at present limited to E. coli culture with biomass contents of OD(600) <or= 15. Cultures with higher OD(600) have to be diluted prior to filtration.

Bentonite↗
PubMed2004

[Removal efficiency of red tide organisms by modified clay and its impacts on cultured organisms].

Removal efficiencies of Prorocentrum donghaiense (Prorocentrum dentatum) by Hexadecyltrimethylammonium (HDTMA) bromide and organo-clay modified by HDTMA were identified. Moreover the toxicity of the unbound HDTMA and HDTMA plus clay to aquacultural organisms, Penaeus japonicus, was also tested. The results suggested that (1) The unbound HDTMA had an excellent ability to remove the red tide organisms. However, its strong toxicity to Penaeus japonicus would restrict its practical use in red tide control. (2) The toxicity of HDTMA could be remarkably decreased by addition of clay and the organo-clay complex had a good ability to removal red tide organisms. At the same time the availability of organo-clay to remove the red tide of P. donghaiense and Heterosigma akashiwo in the lab-imitated cultures were studied. The results indicated that the organo-clay complex could remove 100% P. donghaiense at the dosage of 0.03 g/L and effectively control H. akashiwo at 0.09 g/L while the survival rate of Penaeus japonicus larvae, which were cultured in the red tide seawater, is kept 100%. According to the results in laboratory, the mesocosm tests (CEPEX) in East China Sea were conducted in April and May of 2003. The removal efficiencies of original clay, organic clay and inorganic clay were compared during the CEPEX tests. The results revealed that both inorganic clay and organic clay could remove red tide organisms more effectively than the original clay.

Aluminum Silicates↗
PubMed2005

Bioflocculation of mesophilic and thermophilic activated sludge.

Thermophilic activated sludge treatment is often hampered by a turbid effluent. Reasons for this phenomenon are so far unknown. Here, the hypothesis of the temperature dependency of the hydrophobic interaction as a possible cause for diminished thermophilic activated sludge bioflocculation was tested. Adsorption of wastewater colloidal particles was monitored on different flat surfaces as a function of temperature. Adsorption on a hydrophobic surface varied with temperature between 20 and 60 degrees C and no upward or downward trend could be observed. This makes the hydrophobic interaction hypothesis unlikely in explaining the differences in mesophilic and thermophilic activated sludge bioflocculation. Both mesophilic and thermophilic biomass did not flocculate with wastewater colloidal particles under anaerobic conditions. Only in the presence of oxygen, with biologically active bacteria, the differences in bioflocculation behavior became evident. Bioflocculation was shown only to occur with the combination of wastewater and viable mesophilic biomass at 30 degrees C, in the presence of oxygen. Bioflocculation did not occur in case the biomass was inactivated or when oxygen was absent. Thermophilic activated sludge hardly showed any bioflocculation, also under mesophilic conditions. Despite the differences in bioflocculation behavior, sludge hydrophobicity and sludge zetapotentials were almost similar. Theoretical calculations using the DLVO (Derjaguin, Landau, Verweij and Overbeek) theory showed that flocculation is unlikely in all cases due to long-range electrostatic forces. These calculations, combined with the fact that bioflocculation actually did occur at 30 degrees C and the unlikelyness of the hydrophobic interaction, point in the direction of bacterial exo-polymers governing bridging flocculation. Polymer interactions are not included in the DLVO theory and may vary as a function of temperature.

Adsorption↗
PubMed2001

Surface Chemical Studies on Sphalerite and Galena Using Bacillus polymyxa.

Biodissolution tests reveal the release of lead/zinc species from galena/sphalerite, respectively, while biosorption experiments confirm interaction of cells of Bacillus polymyxa (B. polymyxa) with the metal ions of interest. The amount of exo-polysaccharides is found to be the highest in the case of galena-interacted cells, followed by the Bromfield medium-grown cells while the sphalerite-interacted cells have the least, based on ruthenium red adsorption studies. In contrast, the sphalerite-interacted cells assay the highest amount of protein while the galena-interacted cells have the lowest amount, on a comparative basis. The adsorption of xanthate onto galena is found to be diminished in the presence of the cells whereas the xanthate adsorption density for activated sphalerite is unaffected in the pH range 9-11. Additionally, the cell surface hydrophobicity tests confirm that the sphalerite-interacted cells are more hydrophobic relative to the galena-interacted cells. FTIR spectroscopic data lend support to the higher adsorption density of the cells onto galena vis-à-vis sphalerite. The higher exo-polysaccharide and lower protein contents together with the hydrophilic nature of the galena-interacted cells could be the contributing factors to the selective flocculation and depression of galena. In a similar manner, the higher protein and lower exo-polysaccharide contents as well as the greater hydrophobicity of the sphalerite-interacted cells favor its floatability and dispersion. Copyright 2001 Academic Press.

Journal Article↗
PubMed2003

A new technology for the treatment of mercury contaminated water and soils.

A new technology has been developed for the treatment of contaminated water and soils with lignin derivatives. It has been demonstrated that this technology can be used in the process of removal of high levels of mercury from water, and in the immobilization of leachable mercury in contaminated soils. Lignin derivatives contain an abundance of oxygen-containing functional groups such as phenolic, carboxyl, sulfonyl, alcoholic and enolic structures, which will form lignin-metal macromolecular complexes with high stability through ionic and coordinate covalent bonding. This feature is the basis for the application of lignin derivatives in the removal of metal contaminants from water and in the immobilization of leachable metal in soils or sediments. Tests have confirmed that lignin derivatives are capable of combining with a variety of metal ions including chromium, copper, lead, zinc, mercury, nickel and aluminum. In the new water treatment process, lignin derivatives are dissolved in mercury contaminated water to complex mercury in an exceptionally stable form of a lignin-mercury colloid. The lignin-mercury colloid is then coagulated through the addition of a flocculating agent such as ferric chloride. Under optimized conditions, a dean effluent is produced with a residual mercury level of less than 1 microg l(-1), together with a ferric sludge that is not leachable by TCLP, EPA Method 1311. In the new soil stabilization process, a new solid adsorbent of ferric-lignin is blended with mercury contaminated soil. This solid adsorbent can stabilize the soil by complexing with mercury and, thereby, greatly reduce the TCLP mercury of soil.

Adsorption↗
PubMed1983

New aspects on the 'rodlet cell' in teleosts.

The enigmatic rodlet cells, hitherto interpreted mainly as unidentified parasitic stages ('Rhabdospora thélohani') or as a sort of secretory cell, have been studied with electron microscopical and histochemical methods in three teleost species (Cyprinus carpio L., Tinca tinca L., Salmo gairdneri Rich.). The typical inclusions, the rodlets, consist of a dense core and a less dense cortex, with a coarse flocculent outer zone. The latter shows a positive reaction for neutral polysaccharides respectively glycoproteins (with the silver proteinate method and the equivalent silver methenamine-staining), concurring with some of the light microscopic data. While this suggests the secretion of this material by the Golgi apparatus, the core gives contradictory results, pointing to genetic material instead of a secretory product. Although the Feulgen method (as standard test for DNA with only a few exceptions known) is negative, DNA is indicated by several other methods (light microscopical fluorescence staining with HOECHST 33258, EDTA-method after Bernhard (1969), enzyme digestions positive with DNAse and negative with RNAse). Taken together with some observations on the tissue reaction (phagocytosis of the often discharged rodlets by macrophages and also the more specifically acting heterophilic granulocytes; isolation of the rodlet cells from the adjoining tissue as seen e.g. with the ruthenium red method), an exogenous parasitic nature of these cells seems more plausible, even if the evidence is not sufficient for an exact classification of either the cell or its characteristical inclusions.

Animals↗