Benammar, Leyla2024-02-112024-02-112012http://dspace.univ-khenchela.dz:4000/handle/123456789/396This study comes within the framework of a PNR project for the development of new sensors applied to the control and analysis of chemical pollutants in water, allowed to evaluate the removal of phosphate from wastewater by a mixed culture isolated from activated sludge of sewage wastewater from the City of Khenchela. The isolation and identification of dominant strains responsible for phosphate removal are performed in parallel. We are also interested in studying and comparing the ability of different isolates strains to remove phosphate. Evaluation of phosphate removal is achieved by the determination of phosphate by colorimetric method with ascorbic acid. The isolation of dominant strains is performed on a minimal medium agar. Identification of bacterial strains was performed using the system API20 NE-bioMérieux. This work shows the ability of the microbiota of activated sludge to remove phosphate, with rates proportional to the initial concentration of carbon source. It was found that a concentration of 5000 mg.L -1 of sodium acetate gave a better yield of phosphate removal reaches 99.23%, with an average speed of accumulation of 0.19 mg.L .The concentration of phosphate obtained after treatment is 0.13 mg.L -1 , reflecting a satisfactory treatment sight that the phosphate concentration is known as polluting beyond 1 mg.L The study of the influence of various sources of carbon on the biological phosphorus removal by mixed culture shows that the volatile fatty-acids with short chains such as acetate and lactate are the substrates most favorable to the process. The research of the dominant micro-organisms implied in this process allowed the isolation of eight bacterial species identified as being Pseudomonas aeruginosa, Moraxella lacunata, Acinetobacter junii, Alcaligenes denitrificans, Sphingobacterium spiritivorum Aeromonas hydrophila, Acinetobacter calcoaceticus, and Sphingomonas paucimobilis. It emerges that the best rate of phosphate removal by pure culture is observed with Acinetobater junii with a rate of 76.72%, followed by Alcaligenes denitrificans with 70.42% and Pseudomonas aeruginosa with a rate of about 61.78 %, followed finally by Moraxella lacunata with 50.6%.frThesis