Biomedical subjects

M Baudu

Publications and source records attributed to M Baudu.

15 recordsLinked to original sources

PubMed2006

Improvement of paint effluents coagulation using natural and synthetic coagulant aids.

The coagulant iron chloride and the flocculants Polysep 3000 (PO), Superfloc A-1820 (SU) and Praestol 2515 TR (PR) have been used in this study to show the efficiency of coagulation flocculation process in the chemical precipitation method for the removal of organic and colouring matters from the paint industry wastewater. This study also includes the amount of produced sludge. The results indicate that FeCl(3) is efficient at pH range 8-9 and at optimal dose of 650 mgl(-1). Iron chloride allows the removal of 82% of chemical oxygen demand (COD) and 94% of colour. However, sequential addition of coagulant and polymeric additives enhance clearly pollutant removal and produces less decanted sludge compared to the results obtained when the coagulant is used alone. The removal efficiency of COD reaches 91% and that of colour 99%. Coagulation-biflocculation process is more effective than the coagulation-monoflocculation one. The sequential addition of iron chloride, Polysep 3000 (cationic flocculant) and Praestol 2515 TR (anionic flocculant) seems to be the most suitable combination for the treatment of the paint industry wastewaters.

Chlorides↗

PubMed2005

Treatment of textile wastewater using a natural flocculant.

The physicochemical treatment of wastewater is of substantial interest, especially when conventional treatments by biological processes are not amenable. Among the current chemical processes used for industrial wastewater treatment, coagulation-flocculation has received a large attention for high pollutant removal efficiency. This paper summarizes the results of a textile wastewater treatment process aimed at the destruction of colour by coagulation-flocculation process and using an organic natural flocculant: tannic substances. Jar-test experiments were carried out in order to determine the optimum conditions for the removal of organic matter and color. Treatment with studied flocculent (Polysep3000) proved to be effective in a wide pH range (pH < or = 10), very effective in removing the color (96 %) and a fraction of the COD (40-50 %) from the textile wastewater. Polysep3000 is compared to Al2 (SO4)3 and FeCl3 for sludge production. Polysep3000 seems to be suitable for yielding a high removal of color (> 90%) and corresponding low volume of settled sludge.

Flocculation↗

PubMed2005

Effect of inoculum and sludge concentration on viscosity evolution of anaerobic granular sludges.

The rheological behaviour of granular sludges (diameter 20-315 microm) originating from different anaerobic reactors was carried out using rotation tests. The sieved granular sludges suspensions display a non-Newtonian rheological behaviour and the limit viscosity was therefore used as a rheological parameter. The values obtained, which depend on the shear rate used, were strongly influenced by the total suspended solids (TSS) content of granular sludge and an exponential relation was found between the TSS and the rheological parameter limit viscosity. The increase of viscosity as a function of TSS content of the granular sludge as well as the increase of granule size underlines the importance of the interaction between granules in the evolution of this rheological parameter. Significant differences in granular sludge limit viscosity were found for granular sludge of different origins. All measurements performed with 10 g.l(-1) TSS granular sludge indicate the ability of the chosen rheological parameter to describe different granular sludge quality.

Bacteria, Anaerobic↗

PubMed2004

[Rheological measurement used as a tool to assess sludges settleability].

The activated sludge process is the most widely used biological wastewater treatment method. The measurement of some physico-chemical parameters in aeration tanks do not still allow to avoid clarification operation failure. This study focus on the ability to apply rheological measurements on activated sludge at standard concentrations in order to assess sludge settleability. Measurements in shear flow show a pseudonewtonian region which corresponds to the maximum dispersion of the suspensions that can be detected with the rotational system used. The Bingham's viscosity and shear stress are used to characterise activated sludge. Different shear sensitivities of flocs seem to result from various operational conditions of activated sludge process. Significant relationships with different parameters of settleability point out the ability of Bingham's shear stress to express the compressibility of the activated sludge. According to the protocol of measurement of the study, Bingham's shear stress may influence the nature of the sludge on its settleability.

Bioreactors↗

PubMed2004

Application of the IAS theory combining to a three compartments description of natural organic matter to the adsorption of atrazine or diuron on activated carbon.

The study of natural organic matter (NOM) adsorption on an activated carbon showed that equilibrium cannot be described according to a simple model such as a Freundlich isotherm and confirms the need for a closer description of the organic matter to simulate the competitive adsorption with micropollutants. A representation of the organic matter in three fractions is chosen: non-adsorbable, weak and strong adsorbable. The Ideal Adsorbed Solution Theory (IAST) can, under restrictive conditions, be used to effectively predict the competition between the pesticides and the organic matter. Therefore, it was noted that the model simulated with good precision the competition between atrazine or diuron and natural organic matter in aqueous solution for two activated carbons (A and B). The same parameters for the modeling of organic matter adsorption (Freudlich constants for two absorbable fractions) are used with the two pesticides. However, IAST does not allow correct modeling of pesticide adsorption onto two other (C and D) activated carbons in solution in natural water to be described. IAS theory does not reveal competition between diuron and NOM and pore blockage mechanism by the NOM is proposed as the major effect for the adsorption capacity reduction. However, the difference observed between the two pesticides could be due to in addition to the pore blockage effect, a particular phenomenon with the diuron, especially with D activated carbon. We can suppose specific interactions between the diuron and the adsorbed organic matter and a competition between adsorption sites of NOM and activated carbon surface.

Adsorption↗

PubMed2004

Rheology measurement for on-line monitoring of filaments proliferation in activated sludge tanks.

Rheological behaviour of filamentous sludges originated from activated sludge reactors was studied. Filamentous bulking was detected via a hysteresis loop developed from rheograms resulting from increasing-decreasing shear rates. The rheological parameter reduced hysteresis area (rHa), corresponding to the loop area developed by rheograms was used to quantify filamentous bulking. Application to the evolution of several bulkings was carried out and it was shown that filaments proliferation and disappearance were correlated with, respectively, the increasing and decreasing of the value of the parameter rHa. In parallel with rheological measurement, parameters used for the study of sludge quality, such as sludge volume index (SVI) and settling initial flow (F0), were determined for comparison during the evolution of several bulkings. It was shown that rHa was more sensitive to the appearance of filamentous bulking than SVI and F0, therefore it was concluded that detection of filamentous bulking can be shown from rHa.

Biofilms↗

PubMed2003

Relation between extracellular polymers' composition and its ability to complex Cd, Cu and Pb.

Activated sludges originated from wastewater treatment plants (WWTPs) play an important role in heavy metal removal from effluents. Extracellular polymers (ECP) form a major part of the activated sludge and are heavily involved in biosorption of heavy metals. The complexation of three heavy metals (Cd, Cu and Pb) with ECP extracted from six activated sludges, originated from different WWTPs, was investigated at pH 7. ECP in the study were shown to be mainly composed of proteins, humic acids, uronic acids and polysaccharides along with smaller amounts of lipids and nucleic acids. IR spectra confirmed the presence of the functional groups usually found in the ECP and the content in each fraction was determined using colorimetric methods. The determination of surface charge was carried out on each ECP sample and allowed two pK(a) values characteristic of two distinctive functional groups to be determined. At the pH used in the study, the value of these constants indicates that only one functional group is under protonated form. A polarographic method was used to determine the complexation parameters (number of binding sites and complexation constant) of ECP solutions towards metals. The following orders were established for the number of binding sites: Cu > Pb > or = Cd and for the stability of the ECP-metal complex: Cd > Pb approximately = Cu. A matrix of correlation between the composition of the polymers and the complexation parameters showed that the number of binding sites and the complexation constant were strongly linked to proteins, polysaccharides and humic substances content.

Binding Sites↗

PubMed2003

Determination of some rheological parameters for the characterization of activated sludge.

The rheological characterization of activated sludge originating from different aeration tanks and from a lab-scale plant was carried out using rotation tests. Two rheological parameters were used: limit viscosity (mu(infinity)) and reduced hysteresis area (rHa). Mu(infinity) was strongly influenced by the total suspended solids (TSS) content of sludge and an exponential relation was found between TSS and the rheological parameter mu(infinity). Significant differences in sludge viscosity were found for sludge of different origins, but all of 10 g/l TSS content, indicating ability of viscosity to show different sludge qualities. Marked changes in activated sludge microorganisms communities were shown to have an influence on rheological parameters. During aerobic digestion of sludge, variations in mu(infinity) were noticed, indicating change of sludge quality. An over-growth of filamentous bacteria species was shown to induce a particular rheological behavior which could be characterized by rHa. This parameter was proposed as an index of filamentous bacteria proliferation in activated sludge aeration tanks.

Bacterial Physiological Phenomena↗

PubMed2003

Role of organic matter in copper mobility in a polymictic lake following copper sulfate treatment (Courtille Lake, France).

Lake Courtille is a shallow eutrophic polymictic lake treated with copper sulphate for four years. Water column monitoring and laboratory experiments have shown that dissolved copper (CuD) behaviour correlates well with Dissolved Organic Carbon (DOC). Sequential extraction indicates that a significant fraction of the sediment-borne Cu is associated with the organic fraction (50% to 88% of total copper). This fraction of copper could be released into the water column depending on environmental conditions. Laboratory resuspension experiments have shown that significant short term release of Cu was not possible under circumneutral pH and the oxygenated conditions of the lake (less than 3% of the total copper sediment was released). Nevertheless over the long term, a fraction of the copper bound to the sediment could be released depending on the organic matter mineralization which could explain the presence of copper in the water column one year after the last copper addition.

Biological Availability↗

PubMed2003

Effect of pH and ionic environment changes on interparticle interactions affecting activated sludge flocs: a rheological approach.

The rheological behaviour of activated sludge was investigated through the determination of sludge suspension equilibrium viscosity (micro(eq)) while varying the pH, sodium chloride and calcium chloride concentrations over a wide range. Micro(eq) was used to investigate the influence of environmental changes on the rheological behaviour of activated sludges, on the basis that it is representative of interparticle interactions affecting sludge flocs. Micro(eq) was shown to increase with increasing pH and to decrease with cation addition. The surface charge presented by sludge flocs was shown to be a factor that greatly affects micro(eq), as demonstrated by the linear correlation with zeta-potential (zeta-potential). A decrease in electrostatic charge was supposed to decrease repulsive effect between particles that facilitate flow and to promote a compaction of flocs that lower viscosity. Cation addition was shown to generate a viscosity decrease, in the same proportion, independent of the valency of the cation. The decrease in the particles double layer thickness coupled to the decrease in surface charge were supposed to induce a decrease in interparticle interactions which leads to lower viscosity values.

Flocculation↗

PubMed2003

Setting-up a control simulation strategy for a sequencing batch reactor (SBR): application to municipal wastewater.

The use of a simulation model for setting up a control strategy for a sequencing batch reactor necessary for treating municipal wastewater is described. The model used is the ASM no 1 model. The objective of the pollution control treatment is the removal of carbon and nitrogen; the optimisation is concerned with the improvement in the biological removal of nitrogen. After experimental identification of the initialisation variables, the model enables different SBR control scenarios to be tested (time variation for each process) leading to the total elimination of nitrogen. The best simulation was tested in a laboratory reactor. On that scale, it was noted that denitrification is an endogenous process. Lastly, the control strategy was tested on a semi-industrial pilot working in a pollution control plant. Other control scenarios can be devised and tested by simulation, in order to improve the productivity of the reactor.

Bioreactors↗

PubMed2002

Determination of chlorinated pesticides in water by SPME/GC.

Solid-phase microextraction (SPME) followed by gas chromatography (GC) coupled with an electron capture detector has been applied for the analysis of chlorinated pesticides in water. Molecule adsorption on 100 microm polydimethylsiloxane (PDMS) fibers was activated by immersion of the whole fiber-sample system in an ultrasonic bath. The good reproducibility, low detection limits and wide linear ranges obtained encourage the use of this technique in water control.

Adsorption↗

PubMed2002

Removal of sulfacid brilliant pink from an aqueous stream by adsorption onto surfactant-modified Ti-pillared montmorillonite.

A modified hydrophobic and organophilic pillared clay (CTAC-TiH-montm) was prepared by exchanging some Ti polymeric cations into the interlamellar space of one Algerian montmorillonite (montm) and then by co-adsorption of some surfactant molecules such as cetyltrimethylammonium chloride (CTAC). These new materials were used in adsorption of an anionic textile dye: Sulfacid brilliant pink (SAP). According to adsorption isotherms, the organic modification of Ti-montmorillonite clay by CTAC surfactant increases the amount of textile dye fixed to more than 1000 mg g(-1). The adsorption experiments showed that a ratio of 3 mmol of CTAC per g of clay and an acidic medium (pH = 4) were the optimal parameters necessary to obtain good adsorption uptake and colourless treated solutions. A comparative study proved the high adsorption capacity of the synthesised adsorbents; they can thus be considered as powerful competitors to activated carbon in the treatment of aqueous textile plants and industry effluents.

Adsorption↗

PubMed2001

[Performance and simulation of intermittent decanted extended aeration treatment plants in a tropical climate].

The paper discusses the design and performance of package sewage treatment plants using the Intermittently Decanted Extended Aeration Process (IDEA-Process) in a tropical climate. This hybrid SBR process has been developed overcome traditional drawbacks associated with the SBR process, such as high Sludge Volume Index, high weir loading rate for decanting, and the need to achieve a better effluent quality, especially in terms of nutrient removal. Three domestic sewage plants in Thailand has been selected for field-testing and results of analyses are presented. The average measured biological removal efficiencies in terms of BOD removal and COD removal are about 95.5% and 90% respectively, and the average total nitrogen removal efficiency is about 90%. A computer model is used to study the performance of IDEA-processes compared to results from laboratory tests. The model experience gained through this research are discussed regarding the limitations of computer models such as ASM 1 (Activated Sludge Model n degrees 1) applied to the IDEA-Process in order to develop a new computer model suitable for design and operation of package treatment plant using IDEA-Process Technology in the future.

Bioreactors↗

PubMed2001

Use of image analysis and rheological studies for the control of settleability of filamentous bacteria: application in SBR reactor.

To monitor the ability of flocs to settle in Sequencing Batch Reactor sludge, two methods were tested during two operation cycles. Firstly, an automated image analysis procedure has been tested to quantify the floc size and the length and number of filaments. Secondly, rheological measurements (Bingham viscosity and shear stress) have been used to characterise the dispersion of the sludge which can reflect the cohesive strength of aggregates and so the influence of filamentous bacteria on rheological properties. These results were compared with settling parameters such as Sludge Volume Index or settling velocity. Correlations between the measured parameters with image analysis and parameters such as Sludge Volume Index have been obtained. If it is more difficult to analyze rheological results, it seems however that the thixotropy and the Bingham viscosity distinguish poor settlement owing to some filamentous bulking. The first results are promising, although they require confirmation in the long term.

Bacterial Physiological Phenomena↗