Monem Kallel

Olive mill wastewater degradation by Fenton oxidation with zero-valent iron and hydrogen peroxide.

The degradation of olive mill wastewater (OMW) with hydroxyl radicals generated from zero-valent iron and hydrogen peroxide has been investigated by means of chemical oxygen demand (COD) and phenolic compounds analyses. The effects of the H2O2 dose, the pH and the organic matter concentration have been studied. The optimal experimental conditions were found to have continuous presence of iron metal, acid pH (2.0-4.0), and relatively concentrated hydrogen peroxide (9.5M). Coloration of OMW disappeared and phenolic compound decreased to 50% of initial concentration after 3h reaction time. The application of zero-valent Fe/H2O2 procedure permitted high removal efficiencies of pollutants from olive mill wastewater. The results show that zero-valent Fe/H2O2 could be considered as an effective alternative solution for the treatment of OMW or may be combined with a classical biological process to achieve high quality of effluent water.

Hydrocarbon Contamination of Coastal Sediments from the Sfax Area (Tunisia), Mediterranean Sea

The coastal area off the city of Sfax (730,000 inhabitants), well-known for fisheries and industrial activities, receives high inputs of organic matter mostly anthropogenic. Eighteen stations were selected in the vicinity of the direct discharge of industrial sewage effluents in the sea in order to study the spatial distribution of the organic contamination. Surface sediments sampled in the shallow shelf were analysed for hydrocarbons by Fourier transform infrared spectroscopy, gas chromatography and gas chromatography/mass spectrometry. Total hydrocarbon distributions revealed high contamination as compared to other coastal Mediterranean sites, with an average concentration of 1865 ppm/dry weight sediment. Gas chromatographic distribution patterns, values of unresolved mixture/n-alkane ratio and distributions of steranes and hopanes confirmed a petroleum contamination of the Arabian light crude oil type. Biogenic compounds were also identified with a series of short-chain carbon-numbered n-alkenes in the carbon range 16-24.

Electrochemical treatment of olive mill wastewater: Treatment extent and effluent phenolic compounds monitoring using some uncommon analytical tools

Problems related with industrials effluents can be divided in two parts: (1) their toxicity associated to their chemical content which should be removed before discharging the wastewater into the receptor media; (2) and the second part is linked to the difficulties of pollution characterisation and monitoring caused by the complexity of these matrixes. This investigation deals with these two aspects, an electrochemical treatment method of an olive mill wastewater (OMW) under platinized expanded titanium electrodes using a modified Grignard reactor for toxicity removal as well as the exploration of the use of some specific analytical tools to monitor effluent phenolic compounds elimination. The results showed that electrochemical oxidation is able to remove/mitigate the OMW pollution. Indeed, 87% of OMW color was removed and all aromatic compounds were disappeared from the solution by anodic oxidation. Moreover, 55% of the chemical oxygen demand (COD) and the total organic carbon (TOC) were reduced. On the other hand, UV-Visible spectrophotometry, Gaz chromatography/mass spectrometry, cyclic voltammetry and 13C Nuclear Magnetic Resonance (NMR) showed that the used treatment seems efficaciously to eliminate phenolic compounds from OMW. It was concluded that electrochemical oxidation in a modified Grignard reactor is a promising process for the destruction of all phenolic compounds present in OMW. Among the monitoring analytical tools applied, cyclic voltammetry and 13C NMR a re among th e techniques that are introduced for thefirst time to control the advancement of the OMW treatment and gave a close insight on polyphenols disappearance.

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.

Evolution of several soil properties following amendment with olive mill wastewater

AbstractOlive mill wastewater (OMW) is the main waste product of the olive oil industry and is characterized by high salinity and high organic matter content. Until today, in several olive oil-producing countries, untreated OMW is pumped into agricultural land with potential adverse effects on soil properties. The main objective of this study was to investigate the effects of OMW application on soil physicochemical proprieties. Three OMW levels (50, 100 and 200 m3 ha−1 year−1) were applied over eight successive years. Electrical conductivity, pH, total phosphorus and total nitrogen were studied at different soil depths. Results showed that OMW infiltration caused a modification of soil physicochemical characteristics. The most important effects on soil composition included a significant increase in P and N availability, which enhanced soil fertility in the OMW-treated soil.

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%).

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.

Adaptive biochemical and physiological responses of Eriobotrya japonica to fluoride air pollution

The biochemical and physiological effects of fluoride were investigated in loquat trees (Eriobotrya japonica) grown in the vicinity of a phosphate fertilizer plant in Tunisia. Photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities were assessed; along with photosynthetic pigments, lipid peroxidation, electrolytic leakage (EL) and total phenolic contents in foliage and roots of trees at different distances from the phosphate fertilizer plant. All assessed parameters showed significant discrepancies in comparison with unpolluted sites. Obtained results showed high oxidative stress indices including H2O2, lipid peroxidation, and EL, SOD, CAT and GPx activities and proline contents in leaves and roots at the polluted sites as compared to control. In contrast, leaf Pn, Gs, E and photosynthetic pigment contents were low as compared to the control. These results indicate that even though antioxidant responses increased near the factory, adverse effects on physiology were pronounced.

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