The effectiveness of hydrocarbon bioremediation strategies approaches is depending on various issues such as type and volume of pollution, nutrient accessibility in the target ecosystem, time, biodiversity of microorganisms, pollutant bioavailability and many others. In the present research, laboratory studies were carried out on the bioremediation of coastal sediment samples artificially contaminated with weathered crude oil. The efficiency of natural attenuation, bioaugmentation and Biostimulation for removal of Total Petroleum hydrocarbons (TPH) were compared in 90 days experiments. Three oil concentrations of 3, 30, 60 g oil/kg soil were studied to investigate the effect of oil concentration on the bioremediation process. The average degradation, in Biostimulation tests were 52. 11, 58. 36 and 43. 02% whereas in bioaugmentation tests were 73. 89, 73. 76 and 58. 31% for 3, 30 and 60 g oil respectively. The results indicated that excessive crude oil (more than 30 g/kg in this case) is not suitable for bioremediation presumably duo to inhibitory or toxicity to the microorganisms. By supplementation of acclimatized microorganism as well as nitrogen and phosphorus, a satisfactory amount of biodegradation is reachable in two months.

The efficiency of inorganic fertilizers as stimulating agents for the bioremediation of oil-polluted environments can be increased with the addition of selected biostimulating compounds. In this study, the efficacy of different Biostimulation treatments in the remediation of diesel-polluted soil in purpose-built microcosms has been evaluated. The treatments involved combinations of inorganic fertilizer with (a) Ivey surfactant, (b) Biorem organic fertilizer and (c) ethanol. Microbial activity was evaluated by monitoring the growth of heterotrophic and degrading bacteria and their dehydrogenase activity and carbon dioxide production. Hydrocarbon degradation was monitored by gas chromatography/mass spectrometry. The results showed that all treatments enhanced microbial activity in comparison with natural attenuation and also that the combined treatments generally enhanced hydrocarbon biodegradation in comparison to both natural attenuation and the single inorganic fertilizer treatment. The inorganic fertilizer plus Ivey Ò surfactant was the most efficient treatment in terms of Total Petroleum Hydrocarbon and light and heavy n-alkanes, showing an index of degradation of 1.4 and 1.3, respectively. Furthermore, biodegradation of heavy and branched n-alkanes was higher in microcosms treated with inorganic fertilizer plus ethanol (Index of degradation values of 1.6 and 1.5, respectively) indicating that combined treatments can be very effective in restoration of contaminated soil.

In this work, biodegradation of organic pollutants by activated sludge (AS) in the presence of glu-cose (2 g/L) as an additional carbon source was studied. The AS (without pre-acclimation) was freely suspended under aerobic conditions. Three organic dyes representative of the Algerian textile industry were selected: Cibanon Navy (CN), Solophenyl Scarlet (SS) and Cibacron Green (CG). The results showed that after 10 days of incubation, AS displayed good biodegradation capabilities achieving removal percentages ranging from 50.3% to 89.4% and reduction in COD ranging from 93.1% to 98.3%. Particularly, the textile dye CN was removed up to 89% with high reduction in COD (94.7%). The microbial development stimulated by glucose achieved therefore efficiently the discoloration of contaminated solutions and pollutant degradation. Although it is assumed that dyes can be degraded only under anaerobic conditions, the wastewater treatment using AS appears therefore suitable to the removal of different types of textile dyes before final discharge.

Aerobic fixed bed bioreactors were used to study and compare Biostimulation and bioaugmentation for remediation of soil contaminated with spent motor oil. Bioaugmentation using consortium of bacteria and Biostimulation using inorganic fertilizer and potassium dihydrogen orthophosphate were investigated. The bioremediation indicators used were the oil and grease content removals, total heterotrophic bacteria counts and carbon dioxide respiration rates. Results showed that biodegradations were very effective with 50, 66 and 75 % oil and grease content removal efficiencies for control, bioaugmentation and Biostimulation respectively after ten weeks. Carbon dioxide respiration followed similar pattern as the oil and grease content removals. Biostimulation option has the highest carbon dioxide generation (6 249 mg/kg) and the control with the least (4 276 mg/kg). Therefore, the Biostimulation option can be used to develop a realistic treatment technology for soils contaminated with spent motor oil.