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PubMed2004

Physical and chemical processes for removing suspended solids and phosphorus from liquid swine manure.

A physical/chemical treatment train, that included 24-hour preliminary settling followed by coagulation/flocculation and sedimentation, was tested at a laboratory bench scale to treat liquid swine manure for the removal of total suspended solids (TSS) and total phosphorus (TP). Preliminary (i.e., natural) settling time had an effect on TSS removal within only the first 24 hours. TSS removal efficiency reached 75% (TSS concentration was reduced from 5,800 to 1,450 mg 1(-1)) after 24 hours of preliminary settling. Also, as a result of the 24-hour preliminary settling, TP concentration was reduced from 533 to 318 mg 1(-1), thus leading to a TP removal efficiency of 40%. When compared to ferric chloride, alum was more effective in reducing both TSS and TP. At a 95% confidence interval, alum dose, coagulation Gt (coagulation velocity gradient * rapid-mixing time), and flocculation Gt (flocculation velocity gradient * slow-mixing time) were not significant for TSS removal while alum dose was the only significant factor for TP removal. For the 24-hour settled liquid manure that had a TP concentration in the range of 362 to 401 mg l(-1)and as alum dose increased up to 1,600 mg 1(-1), TP removal efficiency increased up to 70%. Then, the rate of increase in TP removal efficiency per increase in alum dose started to decrease and TP removal efficiency reached about 93% at an alum dose of 3,000 mg 1(-1). Sequential alum dosing improved the TSS removal efficiency while it had no effect on TP removal efficiency. The mass ratio of removed TSS/applied alum increased from about 0.38, during a one-step dosing of alum at a concentration of 1,600 mg l(-1), to about 0.58 during a two-step dosing of alum at a concentration of 1,600 mg l(-1) (i.e., 800 mg l(-1) followed by another 800 mg l(-1)).

Alum Compounds↗
PubMed2004

The role of carbohydrate and protein parts of extracellular polymeric substances on the dewaterability of biological sludges.

There are many factors affecting the biological sludge dewaterability such as particle size distribution, floc structure, extracellular polymeric substances (EPS), etc. In this research, the role of the protein and carbohydrate parts of EPS (EPS(carbohydrate), and EPS(protein)) on the dewaterability of biological sludges was investigated. The sludge EPS composition was altered by feeding the sludges of same origin, in different reactors, with synthetic media having carbon to nitrogen (C/N) ratios of 8, 19 and 30 (in terms of COD/NH3-N), respectively. EPS in sludge samples were extracted by a cation exchange resin (CER). The characteristics of EPS were investigated by analytical methods and by using FT-IR spectroscopy. The dewaterability of the sludges was determined in terms of filterability and compactibility. Filterability, as filterability constant (X), and compactibility, as cake solids concentration, of sludges were determined by using the capillary suction time (CST) test and the centrifugation, respectively. The floc structure of sludge samples was also observed microscopically. Filterability and compactibility of the sludge samples were improved considerably with the increasing carbohydrate part and the decreasing protein part of the sludge EPS. EPS(protein) was inversely related to the cake solids concentration, which might be explained by the water holding capacity of EPS(protein). Filterability and compactibility of sludges improved by the increase of the size and strength of the flocs.

Carbohydrates↗
PubMed2005

Re-use of water treatment works sludge to enhance particulate pollutant removal from sewage.

This paper attempted to study the feasibility of reusing water treatment works sludge ("alum sludge") to improve particulate pollutant removal from sewage. The main issues focused upon were: (1) the appropriate dosage of the alum sludge, (2) the appropriate operating conditions, and (3) the possible mechanisms for enhancement by adding alum sludge. Actual alum sludge and sewage were applied to a series of jar tests conducted under various conditions. It has been found that both the SS and COD removal efficiencies could be improved by the addition of the alum sludge, which was mainly attributed to the removal of relatively fine particles with a size of 48-200 microm. The appropriate dosage of the alum sludge was determined to be 18-20 mg of Al/L. Increasing the mixing speed or reducing the floc size of the alum sludge enhanced the SS and COD removal and the dispersed alum sludge could remove particulate contaminants with smaller size than the raw sewage. ToF-SIMS evidence revealed that the aluminum species at the surface of the alum sludge were effectively utilized for improving the SS and COD removal. It was postulated that the sweep flocculation and/or the physical adsorption might play key roles in the enhancement of particulate pollutant removal from sewage.

Adsorption↗
PubMed2003

Coagulation of humic-kaolin-PACI aggregates.

Water treatment residual flocs are fractal-like aggregates made of many initial aggregates. We investigated in this study the coagulation dynamics for the humic-mineral-polyaluminium chloride (PACI) aggregates using small-angle light scattering techniques and the free-settling test. In contrast to reports in the literature, the presence of humic acid did not lead to a loose floc. Not only the time evolution of the coagulation dynamics, but also the final floc characteristics are only mildly affected by the humic acid. However, the strength of the formed floc does decline with humic acid, which leads to a turbid supernatant with high level of organics.

Aluminum Hydroxide↗
PubMed2005

Physicochemical properties and stability of activated sludge flocs under temperature upshifts from 30 to 45 degrees C.

The impacts of temperature shifts from 30 to 45 degrees C on the structural stability and surface charge of activated sludge flocs were assessed in four sequencing batch reactors (SBRs) treating pulp and paper mill effluent. The improvement in floc stability was tested by sludge magnesium enrichment in one SBR and by operating another reactor at a high sludge retention time (SRT) of 33 days. Floc stability was characterized by dissociation constants with solutions of CaCl(2), KCl, urea, and ethylenediamine tetraacetate (EDTA). Surface charge was assessed by cationic-anionic titration and metals concentrations were also determined. The temperature shift consistently caused an increase in the negative sludge surface charge from approximately -0.180 to -0.300 meq/g MLSS. Magnesium enrichment and a high SRT of 33 days promoted less negatively charged sludge, dampened the increase in negative sludge surface charge, and yielded structurally stronger flocs; however, sludge deflocculation still occurred. Manganese and iron appeared to be released by sludge under the temperature shift. It was concluded that the temperature shift deteriorates the flocculating physicochemical properties of the sludge and that better floc stability achieved by magnesium enrichment and a high SRT is not enough to stop deflocculation. Further research is required to clarify the origin of the increase in negative sludge surface charge, the role of metals, and the governing factors in sludge deflocculation under such temperature shifts.

Journal Article↗
PubMed1999

Determination of carboplatinum and cisplatinum by interfacing HPLC with ICP-MS using ultrasonic nebulisation.

A novel HPLC technique has been developed for the determination of carboplatinum(II) and cisplatinum(II) which are used for chemotherapy. The compounds were separated by a HPLC column. The eluent was on-line nebulized into the nebuliser gas flow using ultrasonic nebulisation. The resulting aerosol was driven by the nebuliser gas stream through a 30-cm heating path, a 60-cm cooling path for desolvatisation and into the plasma of the ICP-MS. The detection was carried out on platinum mass 195Pt. Different RP C18 techniques were tested to obtain the best separation and detection results of the two platinum compounds. The solvent-generated anion exchanger method was selected as the method with the best handling and sensitivity. This technique allows a good separation of the two compounds within 3 min. The detection limits for carboplatinum and cisplatinum were 130 and 80 pg, respectively. The newly developed system has been applied to study the behaviour of the platinum species under different anion influences in aqueous solutions. These investigations are necessary for the future development of an extraction from environmental samples for the two compounds. In further experiments the distribution of the two platinum species, Na2Pt(II)Cl4 and the palladium species. Na2Pd(II)Cl4 between water/sediment, water/charcoal, sewage sludge/water and the distribution in the solution after iron flocculation were investigated to plan an extraction method for the platinum species from environmental matrices.

Antineoplastic Agents↗
PubMed1986

Ultrastructural and biochemical studies of two dynamically expressed cell surface determinants on Candida albicans.

Variability in the expression of two different cell surface carbohydrate determinants was examined with two agglutinating immunoglobulin M monoclonal antibodies (H9 and C6) and immunoelectron microscopy during growth of three strains of Candida albicans. A single strain of Candida parapsilosis did not express either antigen at any time during growth. Antigens were detected on the surface of C. albicans by agglutination tests with either H9 or C6 over a 48-h growth period. The difference in specificities of the monoclonal antibodies was demonstrated by Ouchterlony double-diffusion tests with solubilized antigens and by variabilities in the reactivity of the agglutinins among yeast strains. The antigenic determinants were isolated by specific immunoprecipitation and protease digestion and characterized by methods including high-pressure liquid chromatography, gas-liquid chromatography, and mass spectroscopy with both chemical and electron ionization. These determinants both contain mannose and glucose. In the case of antigen H9, an additional carbohydrate was detected with gas chromatography and mass spectroscopy. The location of antigens on individual cells was determined by indirect labeling of the determinants, first reacting cells with H9 or C6 followed by goat anti-mouse antibody conjugated with 20-nm colloidal gold particles. Transmission electron microscopy was used to examine cells. The antigens that were reactive with the monoclonal antibodies were associated with a flocculent surface layer. Expression of this layer and expression of the antigens is a dynamic process which is growth phase and strain dependent. The antigens were not expressed on very young cells and disappeared from the cell surface of most C. albicans strains with age. The use of monoclonal antibody to cell surface determinants may allow characterization of cell surface antigens of C. albicans and be helpful in establishing receptors which mediate adherence.

Agglutination↗
PubMed2005

Method for monitoring the fate of green fluorescent protein added to aerobic and anaerobic wastewater sludge.

The fate of active proteins in environmental matrices such as wastewater sludge, soil, and organic amendments is not well understood . In the present paper, we report the use of green fluorescent protein (GFP) as a probe protein to investigate the behaviour of proteins in wastewater sludge. We developed a procedure to quantitatively detect the active form of this protein in such a matrix. The procedure is based on the fluorimetric analysis of GFP in the separated liquid and solid fractions of sludge. We then tested the suitability of the approach by monitoring GFP added to aerobic and anaerobic sludge. Under aerobic conditions at 20 degrees C, most GFP immediately associated with the sludge solid fraction. About 20% of the fluorescence due to solid fraction associated GFP was still present after 72 h, which suggests a relative persistence of proteins in this system. Under anaerobic conditions at 35 degrees C, fluorescence signal due to GFP was reduced by 90% after only 6 h.

Bacteria, Aerobic↗
PubMed2006

Particle tracking using confocal microscopy to probe the microrheology in a phase-separating emulsion containing nonadsorbing polysaccharide.

Brownian diffusion of fluorescent microspheres (0.21, 0.5, and 0.89 microm diameter) in conjunction with confocal microscopy has been used to monitor the microrheology of phase-separated regions in a protein-stabilized oil-in-water emulsion containing various low concentrations of a nonadsorbing polysaccharide, xanthan gum. The sensitivity and reliability of the technique has been demonstrated in test experiments on (i) aqueous glycerol solutions and (ii) concentrated surfactant-stabilized emulsions (30-60 vol % oil, 1-2 wt % Tween 20). From particle tracking measurements on the caseinate-stabilized emulsions (30 vol % oil, 1.4 wt % sodium caseinate, pH 7) containing xanthan (0.03-0.07 wt %), the apparent viscosity in the oil-droplet-rich regions has been estimated to be up to 10(3) times higher than that in the phase-separated xanthan-rich regions. This means that our previously determined shape relaxation times for xanthan-containing blobs in the same systems can be attributed to the dominant viscoelasticity of the surrounding regions of concentrated oil droplets and not to the rheology of the xanthan-rich blobs themselves. These data provide clear and unequivocal evidence for the dominant role of the interconnected depletion-flocculated network of oil droplets in the physicochemical mechanism by which hydrocolloid thickeners control the creaming instability of concentrated oil-in-water emulsions.

Adsorption↗
PubMed2006

Application of adaptive heuristic criticism control (AHCC) to dye wastewater.

This paper presents an experimental application of AHCC to study the coagulation process of wastewater treatment in a dye plant. Also this study includes a series of tests in which an AHCC control was used for pH control. The performance results of the AHCC controller are compared with the results obtained by using a conventional proportional-integral-derivative (PID) algorithm. It is useful to compare PID with AHCC to illustrate the extreme range of the nonlinearity of the dye wastewater treatment process. Although the removal of pollutants from wastewater is similar with AHCC and PID, our results show excellent AHCC performance in the region where conventional PID control fails.

Coloring Agents↗
PubMed1996

Isolation of an ovine pulmonary surfactant-associated anionic peptide bactericidal for Pasteurella haemolytica.

Ovine pulmonary surfactant is bactericidal for Pasteurella haemolytica when surfactant and bacteria mixtures are incubated with normal ovine serum. To isolate this component, surfactant (1 mg/ml) was centrifuged at 100,000 x gav, and the supernatant was fractionated by HPLC. Fractions were eluted with acetonitrile (10-100%)/0.1% trifluoracetic acid and tested for bactericidal activity. Amino acid and sequence analysis of three bactericidal fractions showed that fraction 2 contained H-GDDDDDD-OH, fraction 3 contained H-DDDDDDD-OH, and fraction 6 contained H-GADDDDD-OH. Peptides in 0.14 M NaCl/10 microM ZnCl2 (zinc saline solution) induced killing of P. haemolytica and other bacteria comparable to defensins and beta-defensins [minimal bactericidal concentration (MBC)50 range, 0.01-0.06 mM] but not in 0.14 M NaCl/10 mM sodium phosphate buffer, pH 7.2/0.5 mM CaCl2/0.15 mM MgCl2 (MBC50 range, 2.8-11.5 mM). Bactericidal activity resided in the core aspartate hexapeptide homopolymeric region, and MBC50 values of aspartate dipeptide-to-heptapeptide homopolymers were inversely proportional to the number of aspartate residues in the peptide. P. haemolytica incubated with H-DDDDDD-OH in zinc saline solution was killed within 30 min. Ultrastructurally, cells contained flocculated intracellular constituents. In contrast to cationic defensins and beta-defensins, surfactant-associated anionic peptides are smaller in size, opposite in charge, and are bactericidal in zinc saline solution. They are members of another class of peptide antibiotics containing aspartate, which when present in pulmonary secretions may help clear bacteria as a part of the innate pulmonary defense system.

Amino Acid Sequence↗
PubMedDate not supplied

Pilot-scale treatment of RDX-contaminated soil with zerovalent iron.

Soils in Technical Area 16 at Los Alamos National Laboratory (LANL) are severely contaminated from past explosives testing and research. Our objective was to conduct laboratory and pilot-scale experiments to determine if zerovalent iron (Fe(0)) could effectively transform RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) in two LANL soils that differed in physicochemical properties (Soils A and B). Laboratory tests indicated that Soil A was highly alkaline and needed to be acidified [with H2SO4, Al2(SO4)3, or CH3COOH] before Fe(0) could transform RDX. Pilot-scale experiments were performed by mixing Fe(0) and contaminated soil (70 kg), and acidifying amendments with a high-speed mixer that was a one-sixth replica of a field-scale unit. Soils were kept unsaturated (soil water content = 0.30-0.34 kg kg(-1)) and sampled with time (0-120 d). While adding CH3COOH improved the effectiveness of Fe(0) to remove RDX in Soil A (98% destruction), CH3COOH had a negative effect in Soil B. We believe that this difference is a result of high concentrations of organic matter and Ba. Adding CH3COOH to Soil B lowered pH and facilitated Ba release from BaSO4 or BaCO3, which decreased Fe(0) performance by promoting flocculation of humic material on the iron. Despite problems encountered with CH3COOH, pilot-scale treatment of Soil B (12 100 mg RDX kg(-1)) with Fe(0) or Fe(0) + Al2(SO4)3 showed high RDX destruction (96-98%). This indicates that RDX-contaminated soil can be remediated at the field scale with Fe(0) and soil-specific problems (i.e., alkalinity, high organic matter or Ba) can be overcome by adjustments to the Fe(0) treatment.

Environmental Pollution↗
PubMed2004

Preparation of fluorescent particles with long excitation and emission wavelengths dispersible in organic solvents.

We introduce a fast and simple one-step method, a variation of the methods of Barrett and Campbell and Bartlett, to synthesize monodisperse fluorescent particles that can be dispersed in organic solvents and have long excitation (649 nm) and emission wavelengths (679 nm). A lipophilic fluorescent dye, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbocyanine perchlorate, is directly incorporated into PMMA particles through dispersion polymerization. A poly(hydroxystearic acid) graft (poly) methyl methacrylate (MM) and methacrylic acid (MA) copolymer is used as a stabilizer to prevent the particles from aggregating and flocculating in the nonaqueous solvents. The fluorescent PMMA particles are very uniform in size, bleach at very low rate, and behave like hard spheres in their ordering on substrates. One important achievement in our synthesis protocol is that we are able to produce particles of a desired size by choosing the composition of the reactants according to a predetermined relationship between particle size and composition of reactants. In addition, the effects of fluorescent dye and polar solvent (ethanol) on the formation and size of particles are discussed.

Biocompatible Materials↗
PubMed2006

The role of ozonation and activated carbon filtration in the natural organic matter removal from drinking water.

Aquatic natural organic matter is one of the most important problems in the drinking water treatment process design and development. In this study, the removal of the natural organic matter was followed both in the full-scale drinking water treatment process and in the pilot-scale studies. The full-scale process consisted of coagulation, flocculation and flotation, sand filtration, ozonation, activated carbon filtration and disinfection. The aim of the pilot study was to investigate the influence of the dose and contact time of ozonation, and also the impact of activated carbon filtration, on the removal efficiency of organic matter. Several methods, including high-performance size-exclusion chromatography, total organic carbon content and assimilable organic carbon content measurements were used to characterize the behaviour of organic matter and its removal efficiency. On the full-scale process, total organic carbon was removed by over 90 %. According to size-exclusion measurements, chemical coagulation removed the high molar mass organic matter with an efficiency of 98%. The ozonation further removed the smaller molar mass fraction compounds by about 27%, while residual higher molar mass matter remained quite unaltered. Activated carbon filtration removed primarily intermediate and low molar mass organic matter. In the pilot-tests, conducted with sand filtered water from the full-scale process, it was noticed, that the ozonation removed primarily smaller organic compounds. The amount of assimilable organic carbon increased with increasing ozone dose, up to 0.4 mg l(-1) with the highest ozone dose of 4.0 mg 1(-1). The activated carbon filtration removed the assimilable organic carbon. Total organic carbon content was not reduced in ozonation.

Carbon↗
PubMedDate not supplied

Case study II: application of the divalent cation bridging theory to improve biofloc properties and industrial activated sludge system performance-using alternatives to sodium-based chemicals.

The objective of this study was to investigate the application of the divalent cation bridging theory (DCBT) as a tool in the chemical selection process at an activated sludge plant to improve settling, dewatering, and effluent quality. According to the DCBT, to achieve improvements, the goal of chemical selection should be to reduce the ratio of monovalent-to-divalent (M/D) cations. A study was conducted to determine the effect of using magnesium hydroxide [Mg(OH)2] as an alternative to sodium hydroxide (NaOH) at a full-scale industrial wastewater treatment plant. Floc properties and treatment plant performance were measured for approximately one year during two periods of NaOH addition and Mg(OH)2 addition. A cost analysis of plant operation during NaOH and Mg(OH)2 use was also performed. During NaOH addition, the M/D ratio was 48, while, during Mg(OH)2 addition, this ratio was reduced to an average of approximately 0.1. During the Mg(OH)2 addition period, the sludge volume index, effluent total suspended solids, and effluent chemical oxygen demand were reduced by approximately 63, 31, and 50%, respectively, compared to the NaOH addition period. The alum and polymer dose used for clarification was reduced by approximately 50 and 60%, respectively, during Mg(OH)2 addition. The dewatering properties of the activated sludge improved dewatering as measured by decreased capillary suction time and specific resistance to filtration (SRF), along with an increase in cake solids from the SRF test. This corresponded to a reduction in the volume of solids thickened by centrifuges at the treatment plant, which reduced the disposal costs of solids. Considering the costs for chemicals and solids disposal, the annual cost of using Mg(OH)2 was approximately 30,000 dollars to 115,000 dollars less than using NaOH, depending on the pricing of NaOH. The results of this study confirm that the DCBT is a useful tool for assessing chemical-addition strategies and their potential effect on activated sludge performance.

Bacteria↗
PubMed2004

Deflocculation effects due to chemical perturbations in sequencing batch reactors.

Toxic shock-induced deflocculation was examined for activated sludge exposed to six different classes of industrially relevant chemical toxins: an electrophilic solvent (1-chloro-2,4-dinitrobenzene, CDNB), a heavy metal (cadmium), a hydrophobic chemical (1-octanol), an uncoupling agent (2,4-dinitrophenol, DNP), alkaline pH, and weakly complexed cyanide. The concentrations required to inhibit respiration by 50% were used to shock sequencing batch reactors (SBRs) containing a nitrifying (10-day solids retention time (SRT)) and a non-nitrifying (2-day SRT) biomass. Effluent total suspended solids (TSS) and soluble potassium were monitored to examine deflocculation caused by a bacterial stress response mechanism called glutathione-gated potassium efflux (GGKE). Reactors were monitored for recovery over a period of 3 SRTs or less. At the concentrations tested, CDNB, cadmium and pH 11 were found to cause significant increases in effluent TSS concentrations and showed elevated levels of potassium. In contrast, octanol, DNP and cyanide did not induce severe deflocculation and showed moderate increases in effluent potassium levels. Recovery of effluent TSS and potassium concentrations to control levels generally did not correlate, supporting the hypothesis that reflocculation requires regrowth of biomass. These results suggest that different chemicals induce deflocculation in SBRs, but deflocculation is not necessarily caused by the GGKE mechanism in all cases.

1-Octanol↗
PubMed2005

Increased biological hydrogen production with reduced organic loading.

An experimental matrix consisting of reactor hydraulic retention time (HRT) and glucose loading rate was tested to understand the effect of organic loading on H2 production in chemostat reactors. In order to vary the glucose loading rate over a range of 0.5-18.9 g/h, the glucose concentration in the feed was varied from 2.5 to 10 gCOD/L under conditions where the HRT varied from 1 to 10 h (30 degrees C, pH=5.5). Decreasing the glucose loading rate over this range increased the hydrogen yield from 1.7 to 2.8 mol-H2/mol-glucose. High yields of hydrogen were consistent with a high molar acetate:butyrate ratio of 1.08:1 as more hydrogen is produced with acetate as a product (4 mol-H2/mol-acetate) than with butyrate (2 mol-H2/mol-butyrate). It was thought that the decrease in yield with organic loading rate resulted from an overall decreased rate of hydrogen production. As the rate of gas production is reduced, H2 supersaturation in the liquid phase is likely reduced, relieving inhibition due to H2. Flocculation was also an important factor in the performance of the reactor. At the 5-10 gCOD/L influent glucose concentrations, substantial flocculation was observed particularly as the feeding rate was increased due to a reduction in the HRT from 10 to 2.5 h. At the HRT of 2.5 h, biomass concentrations reached as much as 25 g/L. The flocculant nature of the biomass allowed reactor operation at low HRTs with steady H2 production and >90% glucose removal. However, when the HRT was reduced to 1 h at a glucose feed concentration of 2.5 gCOD/L, there was little flocculation evident resulting in wash-out of the culture. These results suggest that hydrogen yields will be optimized for more dilute feeds and lower organic loading rates than have typically been used in biohydrogen reactor studies.

Biomass↗
PubMedDate not supplied

Integrating decay, storage, kinetic selection, and filamentous backbone factors in a bacterial competition model.

Filamentous bulking in activated sludge systems occurs when filamentous organisms outgrow floc-forming bacteria and interfere with sludge settling. The competition between filaments and floc formers has been described previously using the kinetic selection and filamentous backbone theories. We hypothesized that differences in decay rates and storage abilities also affect this competition. We tested this hypothesis by integrating these four factors into a substrate-utilization model to predict and explain coexistence in a completely mixed reactor. In addition, filamentous and nonfilamentous sludges were developed in laboratory-scale reactors and analyzed to determine decay rates. The modeling results showed coexistence of the two organism types, and sensitivity analysis showed that the kinetic parameters, storage rate constants, and backbone coefficient had the greatest effect on the simulation results. Monte Carlo simulation showed the effect of storage, and the ranges of dilution rates wherein one group outcompeted the other were delineated.

Bacteria↗