Monitoring of slaughterhouse wastewater biodegradation in a SBR using fluorescence and UV–Visible absorbance

in Chemosphere (2013)

The aim of this study was to demonstrate that the effectiveness of slaughterhouse wastewater treatment by activated sludge could be enhanced through the use of optical techniques, such as UV–Visible ... [more ▼]

The aim of this study was to demonstrate that the effectiveness of slaughterhouse wastewater treatment by activated sludge could be enhanced through the use of optical techniques, such as UV–Visible absorbance and fluorescence spectroscopy, to estimate the hydraulic retention time necessary to remove the biodegradable chemical oxygen demand (COD). Two experiments were conducted. First, a batch aerobic degradation was performed on four wastewater samples collected from four different cattle processing sites in order to study the changes in the spectroscopic properties of wastewater during biodegradation. Second, a sequencing batch reactor was used in order to confirm that the wastewater fluorescence could be successfully used to monitor wastewater biodegradation in a pilot-scale experiment. Residual blood was the main source of organic matter in the wastewater samples. The absorbance at 416 nm, related to porphyrins, was correlated to the COD during wastewater biodegradation. The tryptophan-like/fulvic-like fluorescence intensity ratio was related to the extent of biodegradation. The COD removal efficiency ranged from 74% to 94% with an hydraulic retention time (HRT) of 23 h. A ratio of tryptophan-like/fulvic-like fluorescence intensities higher than 1.2 indicated incomplete biodegradation of the wastewater and the need to increase the HRT. [less ▲]

Effet des antibiotiques sur le procédé de traitement des eaux par boues activées ; étude à l’échelle du pilote et du floc par microscopie 3D

Conference (2012, February 02)

Effet de l'érythromycine sur le traitement par boues activées

Poster (2012)

Estimation en temps réel de la fraction biodégradable d’un effluent d’abattoir lors d’un traitement aérobie par mesure de sa fluorescence.

Conference (2011, May 30)

Electrocoagulation as a tertiary treatment for paper mill wastewater: Removal of non-biodegradable organic pollution and arsenic

in Separation & Purification Technology (2011), 81

The tertiary treatment of paper mill wastewaters was investigated by testing the effect of batch electrocoagulation for 90 min with two parallel iron or aluminum plates at two values of the current ... [more ▼]

The tertiary treatment of paper mill wastewaters was investigated by testing the effect of batch electrocoagulation for 90 min with two parallel iron or aluminum plates at two values of the current density (100 and 150 A/m 2 ). Dissolved organic carbon removal ranged between 24% and 46%, and chemical oxygen demand removal ranged between 32% and 68%. UV–visible spectroscopy showed a reduction of aromaticity of the treated effluent. The process was also very efficient for the removal of lignin-based pollution, characterized by the fluorescence of humic substances. Arsenic was selected as an example non-organic micropollutant and was also satisfactorily removed (from 4 to 0.5 lg/L). The settling characteristics of the sludge obtained after the electrocoagulation treatment were also evaluated. The sludge aptitude to settling is better with Fe electrodes than with Al electrodes. The experimental results obtained in the present study indicate that electrocoagulation treatment can be very effective and capable of improving the paper mill wastewaters’ quality downstream of the biological treatment. [less ▲]

Effets des antibiotiques sur le procédé d'épuration par boues activées. Etude du cas de l'érythromycine, du floc bactérien au réacteur biologique

Doctoral thesis (2010)

This study examines the effect of erythromycin on activated sludge bacteria and the inhibition of the pollution removal in batch reactors treating urban wastewater. Results showed the importance of ... [more ▼]

This study examines the effect of erythromycin on activated sludge bacteria and the inhibition of the pollution removal in batch reactors treating urban wastewater. Results showed the importance of exposure time to erythromycin. Inhibition of nitrification and COD removal was measured during a 4 h period for erythromytcin concentrations higher than 1 mg/L. A 4 µg/L erythromycin concentration inhibited COD removal during a 20 h exposure time. The effect of erythromycin on nitrification was variable depending on the sludge origin. Erythromycin inhibited the specific nitrification rate with sludge from Nancy WWTP, but increased the nitrification rate at the other facility (Epinal WWTP). The cell lysis resulted in destruction of activated sludge flocs. Microscopic techniques (epifluorescence and confocal laser scanning microscopy (CLSM)), combined with a fluorescent viability indicator, allowed us to study erythromycin time-kill activity.Viability staining results showed a latency time before the lower antibiotic concentrations began to kill bacteria. This latency time could be related to antibiotic adsorption and diffusion into activated sludge flocs as well as the rate of bateria death. The effect of erythromycin according to the bacterial Gram type was investigated with 3-dimensional Confocal Laser Scanning Microscopy (CLSM) time-lapse imaging combined with a Gram and Viability staining. Gram+ bacteria had a higher mortality rate than the Gram- bacteria. This result suggests that antibiotic in wastewater could change the activated sludge bacteria composition according to their Gram type by selecting bacteria the less sensitive to the antibiotics. [less ▲]

Effect of antibiotics on the activated sludge process; 3D visualization of physical disintegration and bacterial mortality kinetics

Conference (2010)

Implementation of micropollutant fate in wastewater treatment plant benchmark simulation models

Conference (2010)

Assessment of erythromycin toxicity on activated sludge via batch experiments and microscopic techniques (epifluorescence and CLSM)

in Process Biochemistry (2010), 45

This study investigates erythromycin toxicity toward activated sludge as a function of exposure time and antibiotic concentration. Batch experiments were conducted and microscopic techniques ranging from ... [more ▼]

This study investigates erythromycin toxicity toward activated sludge as a function of exposure time and antibiotic concentration. Batch experiments were conducted and microscopic techniques ranging from bright-field microscopy to epifluorescence and confocal laser scanning microscopy (CLSM), combined with a fluorescent viability indicator (BacLight ® Bacterial Viability Kit, Molecular Probes), allowed us to study erythromycin time-kill activity. The erythromycin toxicity was observed at lower concentration when exposure time increased. A 4 .g/L erythromycin concentration was toxic to heterotrophic bacteria on a 5-day time exposure, and a 5 mg/L concentration inhibited nitrification. These findings are in agreement with the microscopic studies, which showed a latency time before the lower antibiotic concentrations began to kill bacteria. Microscope slide wells were used as micro-reactors in which erythromycin concentration ranged from 0.1 to 1 mg/L. After 45 min there were 94% (SD 3.8) of living bacteria in control micro-reactors, 67% (SD 3.1) in micro-reactors that contained 0.1 mg/L erythromycin and 37% (SD 18.6) in micro-reactors that contained 1 mg/L erythromycin. CLSM allowed visualization of isolated stained cells in the three-dimensional structure of damaged flocs [less ▲]

Adverse effects of erythromycin on the structure and chemistry of activated sludge

in Environmental Pollution (2010), 158

This study examines the effects of erythromycin on activated sludge from two French urban wastewater treatment plants (WWTPs). Wastewater spiked with 10 mg/L erythromycin inhibited the specific evolution ... [more ▼]

This study examines the effects of erythromycin on activated sludge from two French urban wastewater treatment plants (WWTPs). Wastewater spiked with 10 mg/L erythromycin inhibited the specific evolution rate of chemical oxygen demand (COD) by 79% (standard deviation 34%) and the specific N–NH 4 þ evolution rate by 41% (standard deviation 25%). A temporary increase in COD and tryptophan-like fluorescence, as well as a decrease in suspended solids, were observed in reactors with wastewater containing erythromycin. The destruction of activated sludge flocs was monitored by automated image analysis. The effect of erythromycin on nitrification was variable depending on the sludge origin. Erythromycin inhibited the specific nitrification rate in sludge from one WWTP, but increased the nitrification rate at the other facility. [less ▲]