Dalel Belhaj

Fate of selected estrogenic hormones in an urban sewage treatment plant in Tunisia (North Africa)

Estrogenic compounds have been monitored for one year at an urban sewage treatment plant (STP) located in Tunisia, to evaluate their fate and seasonal variations. The concentrations of these compounds were determined in both wastewater and sludge phases by gas chromatography coupled with mass spectrometry (GC-MS). Results showed that the highest removal of all estrogens (≥80%) was observed in summer. Mass balance analysis revealed that biodegradation was the predominant removal mechanism. Moreover, the results showed that the removal efficiency of the studied emerging micropollutants and their concentrations in the solid phase of return sludge were much higher in winter and spring than in summer and autumn. These findings were closely related to microbial activity and the concentration of mixed liquor suspended solids (MLSSs). Finally, the findings can be used to help with the modifications that could be implemented in that STP for the improved removal of estrogenic contaminants.

Competitive sorption affinity of sulfonamides and chloramphenicol antibiotics toward functionalized biochar for water and wastewater treatment

Competitive sorption of sulfamethazine (SMT), sulfamethoxazole (SMX), sulfathiazole (STZ) and chloramphenicol (CP) toward functionalized biochar (fBC) was highly pH dependent with maximum sorption at pH ∼4.0-4.25. Equilibrium data were well represented by the Langmuir and Freundlich models in the order STZ>SMX>CP>SMT. Kinetics data were slightly better fitted by the pseudo second-order model than pseudo first-order and intra-particle-diffusion models. Maximum sorptive interactions occurred at pH 4.0-4.25 through H-bonds formations for neutral sulfonamides species and through negative charge assisted H-bond (CAHB) formation for CP, in addition to π-π electron-donor-acceptor (EDA) interactions. EDA was the main mechanism for the sorption of positive sulfonamides species and CP at pH<2.0. Sorption of negative sulfonamides species and CP at pH>7.0 was regulated by H-bond formation and proton exchange with water by forming CAHB, respectively. The results suggested fBC to be highly efficient in removing antibiotics mixture.

Box-Behnken design for extraction optimization of crude polysaccharides from Tunisian Phormidium versicolor cyanobacteria (NCC 466): Partial characterization, in vitro antioxidant and antimicrobial activities

In this study, response surface methodology (RSM) based on Box-Behnken design (BBD) was employed to optimize the aqueous extraction of crude polysaccharides from Tunisian cyanobacteria Phormidium versicolor (NCC 466). The optimal extraction conditions with an extraction yield of 21.56±0.92% were as follows: extraction temperature at 81.05°C, extraction time of 3.99h, and water to raw material ratio of 21.52mLg-1. Crude Phormidium versicolor polysaccharides (CPv-PS) are found to be a hetero-sulfated-anionic polysaccharides that contained carbohydrate (79.37±1.58%), protein (0.45±0.11%), uronic acids (4.37±0.19%) and sulfate (6.83±0.28%). The carbohydrate fraction was composed of arabinose, xylose, ribose, rhamnose, N-acetyl glucosamine, galactose, glucose, mannose, glucuronic acid and saccharose with corresponding mole percentages of 2.41, 14.58, 2.18, 6.23, 7.04, 28.21, 26.04, 3.02, 0.86 and 5.07, respectively. Evaluation of the antioxidant activity in vitro suggested that CPv-PS strongly scavenged radicals, prevented bleaching of β-carotene and reduced activity. Furthermore, the CPv-PS exhibited effective antimicrobial properties.

Occurrence and removal of steroidal estrogens in Centre Eastern Tunisia municipal sewage treatment plant

AbstractOccurrence and removal efficiencies of both natural estrogens, estrone (E1), 17β-estradiol (E2) and estriol (E3), and a synthetic estrogen, 17α-ethinylestradiol (EE2), were investigated in sewage treatment plant in Centre Eastern Tunisia employing simple activated sludge process. Concentrations of target estrogens were determined in both wastewater and sludge phases by gas chromatography coupled with mass spectrometer. Among the estrogens studied, E3 was found as the dominant compound detected in wastewater samples with average concentration up to 300 ± 4 ng/L in influent and up to 36 ± 2 in effluent. High aqueous phase removals (>85%) were achieved for E3, while only low to moderate removals for E1, E2, and EE2 (<75%). Based on the mass balance analysis, sorption onto sludge played a dominant role in the removal of estrogens in warm season, especially for E1 and E2 (69.5 and 66.3%, respectively), while biological degradation played a significant role in hot season (61%).

Performance evaluation of an industrial wastewater treatment plant in South-Eastern Tunisia

Heavy metal pollution has become one of the most serious environmental problems today. Heavy metals treatment is of the special concern due to their recalcitrance and persistence in the environment. In this study, four metals (Cr, Cu, Ni, and Zn) found in an industrial wastewater treatment plant in Sfax (South-Eastern Tunisia) were monitored for 10months in 2012. Metal influent and effluent concentrations of wastewater flocculation process measured via 24-h composite samples were used to determine removal efficiencies. Average influent concentrations varied between 16±13.03mg/L (Zn) and 167.21±120.06mg/L (Cr). The flocculation process yielded high removal efficiencies of the studied metals (P93%). Treated wastewaters quality was evaluated according to Tunisian standards for emission into the sewerage system. It was determined that effluent quality in terms of biological oxygen demand, suspending solid, chemical oxygen demand, pH, Cu, and Zn levels were in agreement with standards, but Cr and Ni residual loads were still above the values required by quality criteria.

Determination of Organic Compounds in Landfill Leachates Treated by Coagulation-Flocculation and Fenton-Adsorption

1173 CP 3038. Abstract: The objective of this study was to identify the organic compounds removed from the leachates when treated with coagulation-flocculation and Fenton-Adsorption by gas chromatography coupled to mass spectrometry (GC-MS) in order to identify toxic compounds that could be harmful for the environment or human health. Physico-chemical characterization of the raw leachates (RL) was carried out before and after the aforementioned combined treatment process. The effluent from each stage of this process was characterized: pH, Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), turbidity and Total Suspended Solids (TSS). The organic compounds were determined by GC-MS. The removal of COD and BOD5 reached over 91% in compliance with the Tunisian Standards (NT 106.002-1989), which establishes the maximum permissible limits for contaminants present in wastewater discharges to urbanized streams. The chromatographic analysis from the Adsorption effluent proved that this treatment removed more than 99% of the organic compounds present in the initial sample. The phytotoxicity test showed that combined treatment process allowed a significant toxicity removed (92.2%). The mono (2- ethylhexyl) ester 1,2-benzenedicarboxylic acid persisted, although it is not considered as toxic compound by the NT 106.002-1989) Therefore, the treated effluent can be safely disposed of into the urbanized streams.

Estrogenic compounds in Tunisian urban sewage treatment plant: occurrence, removal and ecotoxicological impact of sewage discharge and sludge disposal

The occurrence, fate and ecotoxicological assessment of selected estrogenic compounds were investigated at Tunisian urban sewage treatment plant. The influents, effluents, as well as primary, secondary and dehydrated sludge, were sampled and analyzed for the target estrogens to evaluate their fate. All target compounds were detected in both sewage and sludge with mean concentrations from 0.062 to 0.993 μg L−1 and from 11.8 to 792.9 μg kg−1dry weight, respectively. A wide range of removal efficiencies during the treatment processes were observed, from 6.3 % for estrone to 76.8 % for estriol. Ecotoxicological risk assessment revealed that the highest ecotoxicological risk in sewage effluent and dehydrated sludge was due to 17β-estradiol with a risk quotient (RQ) of 4.6 and 181.9, respectively, and 17α-ethinylestradiol with RQ of 9.8 and 14.85, respectively. Ecotoxicological risk after sewage discharge and sludge disposal was limited to the presence of 17β-estradiol in dehydrated-sludge amended soil with RQ of 1.38. Further control of estrogenic hormones in sewage effluent and sludge is essential before their discharge and application in order to prevent their introduction into the natural environment.

Effective degradation and detoxification of landfill leachates using a new combination process of coagulation/flocculation-Fenton and powder zeolite adsorption

AbstractThe aim of this work was to examine the application of an integrated technique that consisted of coagulation/flocculation-Fenton-powder zeolite adsorption methods for the treatment of raw leachates from a landfill site of Bizerte (Northern Tunisia). The coagulation–flocculation process showed a moderate chemical oxygen demand (COD) removal efficiency (RE) (54%) and high turbidity RE (94%). The Fenton experiments suggested that the dosage of 1.2 g L−1 of Fe2+ and 2.8 g L−1 of H2O2 at pH 3 were the appropriate working conditions. Under these conditions, COD value was higher than the legal limits for discharge throughout the local municipal sewage. To achieve a satisfactory removal of pollutants, adsorption experiments were also carried out using 30 g L−1 of powder zeolite. The removal efficiencies of COD, ammonia, iron, and aluminum were 97, 91, 99, and 97%, respectively. The phytotoxicity test showed that combined treatment process allowed a significant toxicity removal up to 90%.

Descriptive and multivariable analysis of the water parameters quality of Sfax sewage treatment plant after rehabilitation

This study detailed the effect of simultaneous multiple intrinsic and extrinsic factors on the characteristics of Sfax activated sludge wastewater treatment plant (WWTP), located in Southern East Tunisia. The plant performance was evaluated through descriptive and statistical analysis of quantity and quality data of both raw wastewaters and treated effluent over a period of three years (2008 - 2010). Despite the rehabilitation, poor performance was shown to be attributed to raw wastewaters quality, civilization populations, bad functioning of the aerators and the industrial fallouts and deposits. Therefore, the downstream values of BOD5, COD, SS, FC, FS, TKN and TP are enough to achieve a final effluent that would meet the Tunisian standards limit. Multiple regression analysis showed that removal efficiencies of BOD5, COD and SS can be predicted to reasonable accuracy (R 2 = 0.973, 0.946 and 0.925, respectively). Goodness of the model fit

Phenolic compounds analysis, antioxidant, and hepatoprotective effects of Periploca angustifolia extract on cadmium-induced oxidative damage in HepG2 cell line and rats

Abstract A total of five components (Catechin, Caffeic acid, Ferulic acid, Rosmarinic acid, and Amentoflavone) were identified in Periploca angustifolia leaf methanolic extract. This extract did not cause any cytotoxic effect on HepG2 cell line within the range of concentrations tested (0–400 µg mL−1). Thus, pre-treatment with 100 µg mL−1 of P. angustifolia leaf methanolic extract (PAE) significantly (p < .05) protective HepG2 cells against cytotoxicity induced by cadmium exposure. However, Cd-intoxication significantly (p < .05) increased alanine and aspartate amino transferases serum activities (ALT and AST) and bilirubin content by 1.85-, 1.13-, and 3.55-fold, respectively. The levels of hepatic antioxidant parameters including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were significantly (p < .05) decreased in Cd-intoxicated rats with concomitant enhancement of lipid peroxidation. Our results showed that P. angustifolia leaf methanolic extract can induce antioxidant effects and also exerts beneficial effects for the treatment of Cd-induced hepatotoxicity.