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This study was conducted to characterize Marrakech City (Morocco) tanneries effluents. The analysis of 5 different tanneries recipes revealed identical temperatures (25°C), acidic pH ranging from 2.69 to 3.65, electrical conductivity ranging from 40.33 ± 1.21 to 90.43 ± 2.40 mS/cm, high chemical oxygen demand (COD: 939.33 ± 26.46 - 7,739.55 ± 297.68 mgO2/L), biological oxygen demand (BOD: 24-42 mgO2/L). In addition, there were high quantities of total suspended solids of about 6,400 ± 100 - 15,700 ± 200 mg/L, total dissolved solids (TDS: 22,566.67 ± 57.74 - 50,900 ± 100 mg/L), total solids (TS: 28,966.67 ± 57.74 - 66,600 ± 264.58 mg/L), sulfate (SO4 2-: 1,021.43 ± 61.86 - 2,9 50 ± 35.71 mg/L). High concentrations of total chromium ranging from 200 to 500 mg/L and Cr6+ from 117.22 ± 20.19 to 393.37 ± 42.74 mg/L were recorded. Different size and shape of effluents particles and filaments influence the sedimentation speed and scour velocity, as well as the pollutants adsorption. These results indicate that tanneries effluents are polluted, and the physico-chemical characteristics vary from one to another one. This approach could be useful as a decision-making tool for the implementation of a depollution process adapted to the local socio-economic context. [ABSTRACT FROM AUTHOR]

Olive mill wastewater (OMWW) poses serious environmental problems due to the presence of high phenolic compounds (PC) content. The search for new strains able to degrade pollutants in OMWW and withstand the toxic effects of the high PC concentrations is of great scientific and industrial interest. In this study, an isolated bacterium identified as Bacillus subtilis was selected based on its ability to grow on minimum synthetic medium based media using PC as sole sources of carbon and energy and to degrade the OMWW. The treatment conditions were optimized and included the following parameters: OMWW dilution with the addition of different nitrogen sources, shaking and incubation temperatures. The maximum abatement rate of PC and chemical oxygen demand was 98% and 97%, respectively. This result was obtained at 25% dilution of OMWW with 1 mL inoculums size in a bioreactor with150 rpm, at 37°C with the addition of the degradation media with 1 g/L yeast extract and 3 g/L urea. High-performance liquid chromatography analysis of extracts from treated OMWW showed the evolution of PC content during the degradation process and indicated the high reduction in phenolic compound concentrations. [ABSTRACT FROM AUTHOR]

The present work aims to evaluate the capacity of a yeast strain to degrade the olive mill wastewater (OMWW) and to obtain a stabilized product that can be disposed without any environmental impact on the water–soil–plant system. The pollutant load, expressed by the chemical oxygen demand (COD) and the phenolic compounds (PC), are 187.63 and 4.30 g/L, respectively. The evaluation of the yeast strain capacity to develop on liquid and solid culture media based on the OMWW at different dilutions of 25%, 50%, 75%, raw matter, allowed us to optimize the abatement of the pollutant load, particularly, PC. The results show a significant reduction of 98% for the COD and 97% for the PC, after 1 month of treatment at a dilution of 25%. The PC extracts were characterized by high-performance liquid chromatography, the main identified PC are hydroxytyrosol, tyrosol, caffeic acid, p-coumaric acid and oleuropein. Most of which had disappeared after the treatment. The selected yeast strain was identified by 26S rDNA sequencing and shows that belongs to the species of Rhodotorula mucilaginosa. [ABSTRACT FROM AUTHOR]