Although there is no doubt about the importance of the bacterial activity on the solubilisation and the distribution of heavy metals in aquatic sediments, hydromorphic soils and ground waters; little is known about the involvement of bacterial dissolution in periodically anaerobic environments like that found in dredged sediments and little is known about the processes and the environmental factors controlling this process.The aim of this paper was to study the effect of the autochthonous bacterial activity on the biodegradation of organic matter and the mobilization of heavy metals in the sediments of Al-Ghadir river (Mount Lebanon). Sediments were incubated under standard anaerobic conditions and enriched with glucose to stimulate and accelerate microbial metabolism. The evolution of carbon metabolism (Organic matter evolved, carbon consumed and organic acids produced) and metals released in batch reactors were followed over time. Under the adopted conditions, analysis of the chemical parameters indicated that the incubated sediments showed a significant release of organic carbon corresponding to bacterial development. Mineral analysis showed an important solubilisation of Fe 2+ and Mn 2+ indicating the presence of Fe-and Mn-reducing bacteria in sediments. Pb, Cd and Cr solubilisation profiles were observed and appeared concomitant to the solubilisation profiles of Fe and Mn indicating that the redox cycle has been well installed and that Pb, Cd and Cr were associated to Fe and Mn oxides. The production of Cu appeared in parallel to the mineralization of the organic matter in the sediment indicating that Cu was associated to this fraction. Zn appeared associated to the sulphide fraction than to the Fe and Mn oxides fraction. Microbiological and genetic analysis showed a decrease and the disappearance of some bacterial strains due to the shift in the culture conditions and the toxicity of the released heavy metals but at the same time the development and the growth of many other populations which showed to be tolerant to the same conditions.

Some effluents ((Whey Effluent (WhE); Orange Effluent (OE); Carrot Effluent (CE) and Chocolate Effluent (ChE)) were bioremediated using some allochthonous microorganisms (Lactobacillus delbrueckii subsp. bulgaricus, Saccharomyces cerevisiae Y-1347 and Dekkera bruxellensis). The highest biodegradable efficiency of the Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD) and Total Organic Nitrogen (TON) of the effluents under investigation was noticed when using the allochthonous microorganisms together with the autochthonous one. Saccharomyces cerevisiae Y-1347 proved to be the best utilizer of Whey (WhE) organic and nitrogenous compounds with the reduction of BOD, COD and TON by 12.36, 20.09 and 68.42%, respectively. Dekkera bruxellensis proved to be the organism of choice on using Orange Effluent (OE) where BOD, COD and TON were reduced by 18, 20 and 53.39%, respectively. Lactobacillus delbrueckii subsp. bulgaricus proved to be the best utilizer of the Carrot Effluent (CE) constituents by reducing BOD, COD and TON by 24.27, 19.33 and 63.63%, respectively. Dekkera bruxellensis proved to be the best utilizer of the Chocolate Effluent (ChE) constituents by improving its quality and reducing BOD, COD and TON by 18.36 and 15.86 and 73.07%, respectively. A successful trial was made to use the treated effluents in the irrigation of Lens culinaris and Phaseolus vulgaris seeds for germination.

During the discharge of metals in the aquatic environment, metals are partitioned between the sediment and the water column phases. Further partitioning of metals occurs within the sediment chemical fractions. The present study focuses on one of the middle eat rivers, Al-Ghadir which is the smallest and the most polluted and found in the most populated region in Lebanon. The aim of this study was to integrate hydrochemical and sediment data-in order to evaluate the distribution pattern of the pollution of Al-Ghadir River. Bed sediments and water were collected from five locations in one dry season (Octobre 2010) and analyzed for more than 40 parameters, including (i) those of the chemical and the physico-chemical nature and (ii) those reporting the pollution caused by the heavy metals partitioned between the sediment and the water column phases by applying a sequential chemical fractionation scheme to the <75 µm sieved sediment fraction. The quality of waters for different uses has been tested and the state of sediments pollution was evaluated by comparison with general quality standards. Data showed that the highest percentages of total metal content in sediment are for: Fe and Mn in the residual and in the Fe/Mn oxides fractions, Cu in the oxidizable fraction, Cd and Zn in the carbonate and in the Fe/Mn oxides fractions, Pb and Cr in the Fe/Mn oxides fraction. Based on the geoaccumulation indices (I geo), the river sediments are considered to be moderately polluted with the measured metals.

Abstract:The World Health Organization (WHO), in its Guidelines for Drinking Water Quality, defines domestic water as the "water used for all usual domestic purposes including consumption, bathing and food preparation". Today, securing adequate safe drinking water and proper sanitation became a major challenge facing Lebanon. This work is a case study with objectives the assessment of the domestic water profile of the region surrounding Al-Ghadir River at Kfarshima and Al-Sahra. Samples were collected from 3 types of household water sources (Municipality water, Private wells and Water Vended Gallons) and assessed for their physiochemical and bacteriological profile. Results showed deterioration pattern in domestic water quality profile in the three water sources. The measured physiochemical and bacteriological parameters indicates the degree of deterioration of private well sources by the sea and the wastewater infiltration necessitating the enforcement of legislations associated with the use and the management of private wells, municipality water and private vending water.

The increased deterioration of water resources in Lebanon from progressive urbanization, agricultural activities and development of industries is, according to the natural authorities, a major critical problem by the year 2010. At our study site, at Al-Ghadir River, aqueous solutions containing heavy metals are extensively released from many industries directly to the river. Sediments and soil, at these sites became contaminated with these elements and their potential mobility is of particular concern since downward leaching of the heavy metals may result in the contamination of the groundwater. The objective of the present work was to investigate the bioleaching of heavy metals from the sediments of Al-Ghadir River to underground water using ex-situ column experiments. In order to conciliate the field conditions and the laboratory constraints, we have chosen to experiment the heavy metal leaching from long-term contaminated and non-destructured sediments. Sediments were incubated under anaerobic conditions and enriched with nutrients to stimulate microbial metabolism. The evolution of carbon metabolism and metals leached from the incubated sediment columns were followed over time and the effect of leaching on the distribution of metals as a function of depth was also studied. Results obtained showed that after a phase of mobilization of the heavy metals and which was enhanced by the bacterial activity, the study of the distribution profile of the heavy metals showed that they were highly readsorbed at the surface of the sediment column and their readsorption was found to decrease with depth.