Biohydrogen production is a green method that utilizes organic materials in activated sludge as a substrate. The process involves microorganisms contracting the volume of the sludge content to produce hydrogen, CO2, CH4, and etc. However, the efficiency of this process is low. In this study, Bioaugmentation was carried out by inoculating a 10% Escherichia coli suspension adapted in whey and activated sludge medium. The effects of parameters such as pH, temperature, and stirring, the concentration of whey as carbon source and nitrate as nitrogen source on hydrogen production were screened using the Plackett-Burman method with Minitab 21 software. Among the selected parameters, pH, temperature, concentration of whey and nitrate were found to be the most effective parameters in hydrogen production and were further optimized using Response surface methodology. Stirring wasn’t statistically significant. The optimum conditions for hydrogen production were pH=5.4, temperature=39 ˚C, whey concentration=30 g/L, and nitrate concentration=3.6 g/L. Under these conditions with a 10% inoculation, the total volume of gas production was extended to 1.61 L per liters of activated sludge with 0.046 mole H2 per liters of activated sludge. Comparing the Bioaugmentation method with other method showed that the total time of the process decreased by 8 hours. Additionally, hydrogen production started after 10 hours of incubation and reached its maximum value in 16 hours, resulting in a 59% increase in productivity in less than 16 hours.

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 aim of this work was to investigate the effect of autochthonous Bioaugmentation (ABA) in phenanthrene-contaminated Patagonian soil microcosms, maintained under arid conditions, on phenanthrene elimination and soil microbial community. The polycyclic aromatic hydrocarbon (PAH)-degrading strain Sphingobium sp. 22B previously isolated from the Patagonian soil and selected by its resistance to drying conditions was used as inoculant. The phenanthrene concentration, dehydrogenase activity and denaturing gradient electrophoresis of 16S rRNA gene were monitored during 230 days. The results showed that when the microcosms were maintained at 20% of soil water-holding capacity (WHC), the phenanthrene biodegradation was drastically inhibited and changes in the genetic diversity of soil microbial community were not detected, and neither the ABA nor the biostimulation managed to overcome the inhibitory effects. When the moisture was slightly increased, reached 25% WHC, the ABA showed a significant initial stimulatory effect on phenanthrene biodegradation, demonstrating the potential of ABA in PAH bioremediation process in semiarid Patagonia.

Polycyclic Aromatic Hydrocarbons (PAHS) are important pollutants which have toxic, carcinogenic and mutagenic properties and are considered as a serious hazard to human health and environment. Bioremediation of PAHs contaminated soil was studied in the soil slurry phase bioreactor. For enhancement of biodegradation, Bioaugmentation (which is the process of adding microorganisms with the potential of pollution biodegradation to the bio-slurry reactor) was applied. Phenanthrene (C14H10), a three-benzene ring PAHs, was added in concentration of 100mg/kg soil. Two isolated species and consortium of bacteria were inoculated to the medium in density of 7×107 CFU/mL. The analysis of variance (ANOVA) was used for finding of optimum levels of type of bacterial culture and presence effect of endogenous factors. The base of the bacteria was petroleum-contaminated soil from around Tehran petroleum Refinery. Control reactor (killed bacteria) showed 5% loss of phenanthrene and biodegradation in the non-augmented reactor (endogenous microorganisms) in a slurry bioreactor was about 17%. In the case of Bioaugmentation with Pseudomonas.spp, Pseudomonas aeruginosa and consortium, phenanthrene degradation efficiency were 87.8%, 85.5% and 92.8% ,respectively, presenting the positive effect of biodegradation in consortium augmented compared to the isolated one. Colony forming units (CFUs) variation showed good conformity and agreement with the performance of the reactors with respect to phenanthrene degradation. Hence, the results of this experiment show that Bioaugmentation may be considered as an effective method to enhance the bioremediation in removal of PAHs from contaminated soils.