Journal articles on the topic 'Bioreactors Bioremediation. Soils'

This work investigated the possibility of using vinasse as an amendment in ex-situ bioremediation processes. Groundwater and soil samples were collected at petrol stations. The soil bioremediation was simulated in Bartha biometer flasks, used to measure the microbial CO2 production, during 48 days, where vinasse was added at a concentration of 33 mL.Kg-1of soil. Biodegradation efficiency was also measured by quantifying the total petroleum hydrocarbons (TPH) by gas chromatography. The groundwater bioremediation was carried out in laboratory experiments simulating aerated (bioreactors) and not aerated (BOD flasks) conditions. In both the cases, the concentration of vinasse was 5 % (v/v) and different physicochemical parameters were evaluated during 20 days. Although an increase in the soil fertility and microbial population were obtained with the vinasse, it demonstrated not to be adequate to enhance the bioremediation efficiency of diesel oil contaminated soils. The addition of the vinasse in the contaminated groundwaters had negative effects on the biodegradation of the hydrocarbons, since vinasse, as a labile carbon source, was preferentially consumed.

Abstract Previous tests using a growth medium and olive mill wastewater (OMWW) have shown that it supplies carbon and electron donors suitable for sulphate reducing bacteria (SRB). We assessed the co-treatment of acid mine drainage (AMD) and OMWW using SRB-enriched bioreactors and identified the most abundant bacterial populations present under optimized conditions. The process requires a neutralizing agent to create optimal pH conditions for successful removal of the AMD’s main contaminants. Concentrations of SO42−, Al, Fe, Cu, Zn, and Mn decreased to below Portugal’s maximum admissible values for irrigation waters, and all but Mn were reduced to less than Portugal’s emission limit values (ELVs) for wastewater discharges. Phenol concentrations—the main pollutants in OMWW—dropped to values between 1/10 and 1/5 their initial concentrations in batch tests using mixtures of AMD and OMWW, and to 1/2 their initial concentrations in flow-through tests. The final total phenol concentrations were still above the ELV for wastewater discharges, but phenols are not regulated in irrigation waters, and OMWW is used by some producers to irrigate soils. Six main SRB groups were identified as likely having a fundamental role in the bioremediation process: the genera Desulfovibrio, Sulfurospirillum, and Acetobacter and the families Sphingomonadaceae, Prevotellaceae, and Deferribacteraceae.

Nitrogen cycle microorganisms are essential in agricultural soils and may be affected by mercury pollution. The aims of this study are to evaluate the bioremediation of mercury-polluted agricultural soil using Cupriavidus metallidurans MSR33 in a rotary drum bioreactor (RDB) and to characterize the effects of mercury pollution and bioremediation on nitrogen cycle microorganisms. An agricultural soil was contaminated with mercury (II) (20–30 ppm) and subjected to bioremediation using strain MSR33 in a custom-made RDB. The effects of mercury and bioremediation on nitrogen cycle microorganisms were studied by qPCR. Bioremediation in the RDB removed 82% mercury. MSR33 cell concentrations, thioglycolate, and mercury concentrations influence mercury removal. Mercury pollution strongly decreased nitrogen-fixing and nitrifying bacterial communities in agricultural soils. Notably, after soil bioremediation process nitrogen-fixing and nitrifying bacteria significantly increased. Diverse mercury-tolerant strains were isolated from the bioremediated soil. The isolates Glutamicibacter sp. SB1a, Brevundimonas sp. SB3b, and Ochrobactrum sp. SB4b possessed the merG gene associated with the plasmid pTP6, suggesting the horizontal transfer of this plasmid to native gram-positive and gram-negative bacteria. Bioremediation by strain MSR33 in an RDB is an attractive and innovative technology for the clean-up of mercury-polluted agricultural soils and the recovery of nitrogen cycle microbial communities.

Field and laboratory studies were used to study the influence of temperature and O2on the bioremediation of diesel-fuel contaminated soil. Field data were obtained from a landfarm located in Northern Ontario, whereas laboratory experiments were conducted using bioreactors containing diesel-spiked soil and contaminated soil from the field site. Laboratory and field degradation rates were quantified based on changes in the total petroleum hydrocarbons concentration and some individual components, as well as by monitoring O2consumption and CO2evolution. A degradation rate correlation was developed from the laboratory data. Based on comparison with the laboratory data, the slow rate observed in the field was likely due to low O2concentrations at the site.Key words: bioremediation, diesel fuel, unsaturated soil, cold climate, degradation rate.

The aim of the present work was to evaluate the biodegradation of petroleum hydrocarbons in clay soil a 45-days experiment. The experiment was conducted using an aerobic fixed bed reactor, containing 300g of contaminated soil at room temperature with an air rate of 6 L/h. The growth medium was supplemented with 2.5% (w/w) (NH4)2SO4 and 0.035% (w/w) KH2PO4. Biodegradation of the crude oil in the contaminated clay soil was monitored by measuring CO2 production and removal of organic matter (OM), oil and grease (OandG), and total petroleum hydrocarbons (TPH), measured before and after the 45-days experiment, together with total heterotrophic and hydrocarbon-degrading bacterial count. The best removals of OM (50%), OandG (37%) and TPH (45%) were obtained in the bioreactors in which the highest CO2 production was achieved.

Central composite design (CCD) and response surface methodology (RSM) were employed to optimize four important variables, i.e. amounts of oil, bacterial inoculum, nitrogen and phosphorus, for the removal of selected n-alkanes during bioremediation of weathered crude oil in coastal sediments using laboratory bioreactors over a 60 day experimentation period. The reactors contained 1 kg soil with different oil, microorganisms and nutrients concentrations. The F Value of 26.89 and the probability value (P < 0.0001) demonstrated significance of the regression model. For crude oil concentration of 2, 16 and 30 g per kg sediments and under optimized conditions, n-alkanes removal was 97.38, 93.14 and 90.21% respectively. Natural attenuation removed 30.07, 25.92 and 23.09% n-alkanes from 2, 16 and 30 g oil/kg sediments respectively. Excessive nutrients addition was found to inhibit bioremediation.

Abstract The environmental release of mercury is continuously increasing with high degree of mobility, transformation and amplified toxicity. Improving remediation strategies is becoming increasingly important to achieve more stringent environmental safety standards. This study develops a laboratory-scale reactor for bioremediation of aqueous mercury using a biofilm-producing bacterial strain, KBH10, isolated from mercury-polluted soil. The strain was found resistant to 80 mg/L of HgCl2 and identified as Bacillus nealsonii via 16S rRNA gene sequence analysis. The strain KBH10 was characterized for optimum growth parameters and its mercury biotransformation potential was validated through mercuric reductase assay. A packed-bed column bioreactor was designed for biofilm-mediated mercury removal from artificially contaminated water and residual mercury was estimated. Strain KBH10 could grow at a range of temperature (20–50 °C) and pH (6.0–9.0) with optimum temperature established at 30 °C and pH 7.0. The optimum mercuric reductase activity (77.8 ± 1.7 U/mg) was reported at 30 °C and was stable at a temperature range of 20–50 °C. The residual mercury analysis of artificially contaminated water indicated 60.6 ± 1.5% reduction in mercury content within 5 h of exposure. This regenerative process of biofilm-mediated mercury removal in a packed-bed column bioreactor can provide new insight into its potential use in mercury bioremediation.

A crude oil spill is a common issue during offshore oil drilling, transport and transfer to onshore. Second, the production of petroleum refinery effluent is known to cause pollution due to its toxic effluent discharge. Sea habitats and onshore soil biota are affected by total petroleum hydrocarbons (TPH) as a pollutant in their natural environment. Crude oil pollution in seawater, estuaries and beaches requires an efficient process of cleaning. To remove crude oil pollutants from seawater, various physicochemical and biological treatment methods have been applied worldwide. A biological treatment method using bacteria, fungi and algae has recently gained a lot of attention due to its efficiency and lower cost. This review introduces various studies related to the bioremediation of crude oil, TPH and related petroleum products by bioaugmentation and biostimulation or both together. Bioremediation studies mentioned in this paper can be used for treatment such as emulsified residual spilled oil in seawater with floating oil spill containment booms as an enclosed basin such as a bioreactor, for petroleum hydrocarbons as a pollutant that will help environmental researchers solve these problems and completely clean-up oil spills in seawater.

In this study, a new formulation of low-cost, biodegradable, and non-toxic biosurfactant by Candida sphaerica UCP 0995 was investigated. The study was conducted in a bioreactor on an industrial waste-based medium, and a central composite rotatable design was used for optimization. The best results, namely a 25.22 mN/m reduction in surface tension, a biosurfactant yield of 10.0 g/L, and a critical micelle concentration of 0.2 g/L, were achieved in 132 h at an agitation speed of 175 rpm and an aeration rate of 1.5 vvm. Compositional and spectroscopic analyses of the purified biosurfactant by chemical methods, Fourier transform infrared spectroscopy, and nuclear magnetic resonance suggested that it is a glycolipid-type biosurfactant, and it showed no cytotoxicity in the MTT assay. The biosurfactant, submitted to different formulation methods as a commercial additive, remained stable for 120 days at room temperature. Tensioactive properties and stability were evaluated at different pH values, temperatures, and salt concentrations. The biosurfactant obtained with all formulation methods demonstrated good stability, with tolerance to wide ranges of pH, temperature and salinity, enabling application under extreme environmental conditions. Bioremediation tests were performed to check the efficacy of the isolated biosurfactant and the selected microbial species in removing oil from soil. The results demonstrated that the biosurfactant produced has promising properties as an agent for the bioremediation of contaminated soil.

Microbial populations within the rhizosphere have been considered as prosperous repositories with respect to bioremediation aptitude. Among various environmental contaminants, effluent from textile industries holds a huge amount of noxious colored materials having high chemical oxygen demand concentrations causing ecological disturbances. The study was aimed to explore the promising mycobiome of rhizospheric soil for the degradation of azo dyes to develop an efficient system for the exclusion of toxic recalcitrants. An effluent sample from the textile industry and soil samples from the rhizospheric region of Musa acuminata and Azadirachta indica were screened for indigenous fungi to decolorize Congo red, a carcinogenic diazo dye, particularly known for its health hazards to the community. To develop a bio-treatment process, Aspergillus terreus QMS-1 was immobilized on pieces of Luffa cylindrica and exploited in stirred tank bioreactor under aerobic and optimized environment. Quantitative estimation of Congo red decolorization was carried out using UV-Visible spectrophotometer. The effects of fungal immobilization and biosorption on the native structure of Luffa cylindrica were evaluated using a scanning electron microscope. A. terreus QMS-1 can remove (92%) of the dye at 100 ppm within 24 h in the presence of 1% glucose and 1% ammonium sulphate at pH 5.0. The operation of the bioreactor in a continuous flow for 12 h with 100 ppm of Congo red dye in simulated textile effluent resulted in 97% decolorization. The stirred tank bioreactor was found to be a dynamic, well maintained, no sludge producing approach for the treatment of textile effluents by A. terreus QMS-1 of the significant potential for decolorization of Congo red.

Objective: Oil spillage has become a global environmental problem as its constituents are toxic, mutagenic and carcinogenic. Natural bioremediation is the only eco-friendly solution to resist its devastating environmental and economic damage. Microbes are used to change harmful substances to non-toxic substances. The current work focuses on the performance of different bacterial species in degrading the oil components like benzene and polycyclic aromatic hydrocarbons (PAH)s.Methods: Sample was collected from different areas affected by the oil spill in Mumbai that is from the shore of Juhu, Dadar and Manori in form of tar balls and was enriched and isolated on Bushnell and Hass's media containing 1% crude oil as a sole source of carbon. The potent isolates were then identified by standard biochemical tests referring to Bergey's Manual.Results: Two partially identified strains were Pseudomonas flavescens and Bacillus sp. biofilms of Pseudomonas spp. was prepared on glass matrix to determine its oil degrading efficiency. An indigenous consortium was developed by the assembly of seven isolates of oil-degrading bacteria.Conclusion: The developed consortium was able to degrade crude oil completely within 4 d. The obtained isolates seemed to have the potential for bioremediation of oil contaminated soil and tar balls which was justified by setting up of a bioreactor.

Bioremediation is an important technology to remediate the chromium (Cr) contaminated soil and water. In this study, Shewanella putrefaciens (MTTC8410) was used to investigate the influence of carbon concentration, pH, and temperature on reduction of hexavalent chromium [Cr(VI)] into trivalent chromium [Cr(III)]. The increased bacterial growth rate was significantly reduced the Cr(VI) concentration. In batch mode experiments, 1% starch recorded the highest reduction of Cr(VI) (90%) followed by 1% glucose (88% reduction) and a reduction of 77% was by 1% cellulose. By using various pH conditions the maximum Cr(VI) reduction was achieved at pH 7.0. In this experiment the maximum Cr(VI) reduction (75%) was observed at 35°C, followed by 30°C with 62% of Cr(VI) reduction. Bioreactor analysis revealed the highest reduction of Cr(VI) (88%) in unsterile tannery effluent. The significant levels of physico- chemical parameters were reduced in unsterile tannery effluent, as compared to the sterile tannery effluent. The experimental results revealed that the S. putrefaciens (MTTC8410) could be used as a potential bacterial strain for reduction of Cr(VI) from contaminated groundwater.

A strain of Pseudomonas sp. CZ1, which was isolated from the rhizosphere of Elsholtzia splendens obtained from the heavy-metal-contaminated soil in the north-central region of the Zhejiang province of China, has been studied for tolerance to copper (Cu) and zinc (Zn) and its capacities for biosorption of these metals. Based on 16S ribosomal DNA sequencing, the microorganism was closely related to Pseudomonas putida. It exhibited high minimal inhibitory concentration values (about 3 mmol Cu·L–1and 5 mmol Zn·L–1) for metals and antibiotic resistance to ampicillin but not to kanamycin. Based on the results of heavy metal toxicity screening, inhibitory concentrations in solid media were lower than those in liquid media. Moreover, it was found that the toxicity of Cu was higher than that of Zn. Pseudomonas putida CZ1 was capable of removing about 87.2% of Cu and 99.8% of Zn during the active growth cycle, with specific biosorption capacities of 24.2 and 26.0 mg·L–1, respectively. Although at low concentrations, Cu and Zn slightly damage the surface of some cells, P. putida demonstrated high capacities for biosorption of Cu and Zn. Since P. putida CZ1 could grow in the presence of significant concentrations of metals and because of its high metal uptake capacity in aerobic conditions, this bacterium may be potentially applicable in bioreactors or in situ bioremediation of heavy-metal-contaminated aqueous or soil systems.Key words: Pseudomonas putida, copper, zinc, tolerance, biosorption.

Microbial fuel cells (MFC) are an emerging technology for waste, wastewater and polluted soil treatment. In this manuscript, pollutants that can be treated using MFC systems producing energy are presented. Furthermore, the applicability of MFC in environmental monitoring is described. Common microbial species used, release of genome sequences, and gene regulation mechanisms, are discussed. However, although scaling-up is the key to improving MFC systems, it is still a difficult challenge. Mathematical models for MFCs are used for their design, control and optimization. Such models representing the system are presented here. In such comprehensive models, microbial growth kinetic approaches are essential to designing and predicting a biosystem. The empirical and unstructured Monod and Monod-type models, which are traditionally used, are also described here. Understanding and modelling of the gene regulatory network could be a solution for enhancing knowledge and designing more efficient MFC processes, useful for scaling it up. An advanced bio-based modelling concept connecting gene regulation modelling of specific metabolic pathways to microbial growth kinetic models is presented here; it enables a more accurate prediction and estimation of substrate biodegradation, microbial growth kinetics, and necessary gene and enzyme expression. The gene and enzyme expression prediction can also be used in synthetic and systems biology for process optimization. Moreover, various MFC applications as a bioreactor and bioremediator, and in soil pollutant removal and monitoring, are explored.

ABSTRACTBioaugmentation has been frequently proposed in wastewater and soil treatment to remove toxic aromatic compounds. The performance of bioaugmentation is affected by a number of biological and environmental factors, including the interaction between the target pollutant and the augmented bacterial cells. In this study, usingComamonas testosteroniand 3-chloroaniline (3-CA) as the model organism and target pollutant, we explored the influence of toxic aromatic pollutants on the biofilm lifestyle of bacteria capable of degrading aromatic compounds toward a better understanding of cell-pollutant interaction in bioaugmentation. Our results showed that the exposure to 3-CA greatly reduced the retention ofC. testosteronicells in packed-bed bioreactors (from 22% to 15% after three pore volumes), which could be attributed to the altered bacterial motility and cell surface hydrophobicity. To further understand the molecular mechanisms, we employed an integrated genomic and transcriptomic analysis to examine the influence of 3-CA on the expression of genes important to the biofilm lifestyle ofC. testosteroni. We found that exposure to 3-CA reduced the intracellular c-di-GMP level by downregulating the expression of genes encoding c-di-GMP synthases and induced massive cell dispersal from the biofilms. Our findings provide novel environmental implications on bioaugmentation, particularly in biofilm reactors, for the treatment of wastewater containing recalcitrant industrial pollutants.IMPORTANCEBioaugmentation is a bioremediation approach that often has been described in the literature but has almost never been successfully applied in practice. Many biological and environmental factors influence the overall performance of bioaugmentation. Among these, the interaction between the target pollutant and the augmented bacterial cells is one of the most important factors. In this study, we revealed the influence of toxic aromatic pollutants on the biofilm lifestyle of bacteria capable of degrading aromatic compounds toward a better understanding of cell-pollutant interaction in bioaugmentation. Our findings provide novel environmental implications on bioaugmentation for the treatment of wastewater containing recalcitrant industrial pollutants; in particular, the exposure to toxic pollutants may reduce the retention of augmented organisms in biofilm reactors by reducing the c-di-GMP level, and approaches to elevating or maintaining a high c-di-GMP level may be promising to establish and maintain sustainable bioaugmentation activity.

Biogas production considered the most encouraging sources of renewable energy in Sudan. Anaerobic process of digestion is considered as efficient techniques of producing biogas. The process also a trustworthy method for treatment of municipal wastes, and the digested discharge could be utilized as soil conditioner to improve the productivity. This research work states at the option of using domestic sludge of the wastewater treatment plant in Soba municipal station (south of Khartoum-Sudan) to produce biological gas (biogas). A laboratory investigation was carried out using five-liter bioreactor to generate biogas for 30 days. The total volume of gas made was 270.25 Nml with a yield of 20 Nml of biogas/mg of COD removed. Chemical oxygen demand, Biological oxygen demand, & total solids drop produced were 89, 91 & 88.23% respectively. Microbial activity was declined from 1.8x107 (before starting the process of digestion) to 1.1x105 germs/mL (after completion of 30 days of digestion). This study offered a significant energetic opportunity by estimated the power production to 35 KWh.Key word: Sludge, municipal plant, organic material, anaerobic process, breakdown, biological gas potentialNTRODUCTIONIncreasing of urban industries style in the world has given rise to the production of effluents in huge amounts with abundant organic materials, which if handled properly, be able to end in a substantial source of energy. Although of a fact that there is an undesirable environmental effect related with industrialization, the influence can be diminished and energy can be tapped by means of anaerobic digestion of the wastewater (Deshpande et al., 2012). Biological wastewater treatment plant (WWTP) is a station for removal of mainly organic pollution from wastewaters. Organic materials are partly transformed into sludge that, with the use of up-to-date technologies, represents an important energy source. Chemical biological, and physical technology applied throughout handling of wastewater produce sludge as a by-product. Recent day-to-day totals, dry solids range from 60–90 g per population equivalent, i.e. EU produces per year 10 million tons of dry sludge (Bodík et al., 2011). Sludge disposal (fertilizers use, incineration, and landfills) is often explored since of increasingly limiting environmental legislation (Fytili and Zabaniotou, 2008). The energy present in sludge is obviously consumed in anaerobic digestion. Anaerobic Process is considering the most appropriate choice for the handling of organic effluents of strong content. This process upgraded in the last few years significantly with the applications of differently configured high rate treatment processes, particularly for the dealing of industrial releases (Bolzonella et al., 2005). Anaerobic process leads to the creation of biological gas with high content of methane, which can be recovered, and used as an energy source, making it a great energy saver. The produced gas volume during the breakdown process can oscillate over a wide range varying from 0.5 – 0.9 m3 kg–1 VS degraded (for waste activated sludge) (Bolzonella et al., 2005). This range rest on the concentration of volatile solids in the sludge nourish and the biological action in the anaerobic breakdown process. The residue after digestion process is stable, odorless, and free from the main portion of the pathogenic microorganism and finally be able to use as an organic nourishment for different application in agriculture. Sludge significant coming out from breakdown which allows to yield a renewable energy, that was cheap, obtainable, & no polluting. Sustainable development considered the production of biogas as environmentally friendly and an economic key (Poh and Chong, 2009).OBJECTIVES Sudan have huge tones of sewage sludge from domestic sewage water is accumulated daily in lagoon of soba sewage treatment plant, so this work, we were carried for energy production and treatment of sludge, which constitutes a plentiful waste which ever know any sort of handling after few years from establishing the station.MATERIALS AND METHODSExperimental apparatus: Anaerobic breakdown was done in five liters fermenter. The fermenter was maintained at 35oC in a thermostatic bath and stirred regularly. U shaped glass tube was connected to the fermenter, allowing the measurement of produced biogas volume and pressure. Water displacement technique was used for determination of the volume of produced biological gas (biogas) at the beginning of each sampling. Testing of the biogas combustibility was determined by connecting one of ends of the tube to a gas collection and storage device (balloon), the other end to a Bunsen burner. In the process of reduction of carbon dioxide (CO2) to maximum dissolution in the tube the liquid must be a salty saturated acid solution (5% citric acid, 20% NaCl, pH ¼ 2) (Connaughton et al., 2006).Substrate: About 5L sludge containing culture medium were taken from the lowest part of the first settling tank in Soba station. The moisture content of initial substrate was 35%. The collected sample was preserved at 4oC prior to loading the biological reactor (Tomei et al., 2008). Table 1 showed the sludge features in the reactor with a loading rate of 16 g TS/L, (Connaughton et al., 2006; Tomei et al., 2008).Analytical Methods: The pH was controlled by using HANNA HI 8314 model as pH meter device. Assay was used for determination of Alkanility & Volatile fatty acids (Kalloum et al., 2011). The standard method of analysis was used for recognized the Chemical Oxygen Demand (COD) (Raposo et al., 2009). Titrimetric method was used for analyzing Volatile fatty acids (VFA). Alkalinity assay was used for determination of Total Alkalinity (TA). Oxitop assay was used for measuring the biological oxygen demand. Ignition method was used for measuring Volatile Solids (VS) by losing weight in dry sample at 550oC in the furnace, & Total solids were done to constant weight at 104oC (Monou et al., 2009). A method of water displacement was used for determination of the total volume of Biological gas produced (Moletta, 2005). Microbial species & analyses were determined by microbial standard assay. Sample analysis was done by explore of three replicates and the outcomes were the middling of these replicates. Startup of experiments continues until a bubble of gas was detected.RESULTS AND DISCUSSIONMeasurement of pH: Figure 2 exhibited pH trends during 30 days with a drop pattern from 7.0 to 6.0 during the first five days; this was mainly because of the breakdown of organic materials and the development of (VFA). Then later, an increasing pattern in pH was noticed to 6.98, for the next week, then Steadying around this pH level was continued till the completion of the breakdown period which taken 30 days. Those out comes were also reported by other researchers (Raposo et al., 2008)Measurement of VFA: Development of VFA throughout 30 days was depicted in figure 3, an increase in volatile fatty acids up to 1400 mill equivalents per liter (meq/L) in the first ten days. This criterion of making of volatile fatty acid is typical to the researcher’s report of identification of hydrolysis in acidogenesis stage (Parawira et al., 2006). The decline in volatile fatty acids after the tenth day was owing to intake by bacteria which would relate to the stage of acetogenesis.Total alkalinity (TA): During the ten days, we observed rise in volatile fatty acids content followed by a drop in a pH in the same time (figures 4 and 5). Encountered to these alterations, an increase in the total alkalinity in the medium for reestablishing situations of alkalinity to the outbreak of methanogens stage (figure 4). Through all the digestion period the ratio of VFA/TA which was equal and lower than 0.6±0.1 were described in figure 6. These ratios designated the achievability of the procedure despite the essential production of volatile fatty acid (Chen and Huang, 2006; Nordberg et al., 2007). The anaerobic digestion process may be hinder by the production of volatile fatty acid.Biogas production: Pressure measurement and biogas volume were used for controlling biogas production. Figure 7 explained the changing in biogas pressure throughout the digestion period. quality of Biogas was obtained with minimum methane of 40% (Bougrier et al., 2005; Lefebvre et al., 2006). Total volume of biological gas production was 270.25 Nml. The yield of biological gas was 20.25 Nml/mg COD removed, which is in range of the others researcher report (Tomei et al., 2008). Biogas production can be calculated from the following formula (Álvarez et al., 2006): Biogas production= (Total quantity of biogas produced)/(Total solid).The COD and BOD removal: Chemical oxygen Demand (COD) and Biological Oxygen Demand (BOD) showed a significant reduction of 89% and 91% respectively (figures 8 and 9). Consequently these reduction in contaminants proved that anaerobic process of digestion was an operational technique for removal of organic pollution. Some researchers reported the same results (Bolzonella et al., 2005; Álvarez et al., 2006; Wang et al., 2006). Another criterion for proving the removal of organic pollutants was reduction of total solids (TS), where the drop approached 88.23% (figure 10). Some researcher’s reports approached the same drop (Hutnan et al., 2006; Linke, 2006; Raposo et al., 2009). Therefore it was possible to conclude that anaerobic digestion necessary showed decrease or reduction of organic pollutants rates because of the transformation of organic substances into biogas and accordingly led to the drop of chemical oxygen demand (COD). This could be explained in figure 11 by the comparison of the two techniques during the anaerobic digestion process. That means the chemical oxygen demand (COD) drop should be tailed essentially by Total solids drop (TS).Microbial activity: Figure 11 showed the microbial variation during anaerobic digestion. The total micro flora (total germs) declined from 1.8x107 (before starting the process of digestion) to1.1x105 germs/mL (after completion of 30 days of digestion). Moreover figure 12 obviously explained what was running during the process of digestion in the reactor, microbial species vanishing after the 30 days such as streptococci and Escherichia coli. Some researchers reports explained that there was some sort of relationship between physicochemical and the biological parameters of micro flora with total solid (TS). figure 13 described obviously this relationship of the drop of micro flora which go along with total solids reduction. This intended that consumption and a declining in the mass residue of organic materials created at the termination of digestion was the outcome of the transformation of organic materials into biological gas and also the sum of microorganism reduction. This attained result proved that the process of anaerobic digestion was a good process for decontamination (Deng et al., 2006; Perez et al., 2006; Davidsson et al., 2007).CONCLUSIONSoba sludge’s municipal station carried in this research paper demonstrated operative for biological gas production (biogas). During the first five days, breakdown of organic materials and the formation of volatile acids were started. Volatile fatty acids increased up to 1400 mill equivalents per liter (meq/L) in the first ten days, then started to decline in after the tenth day this owing to intake by bacteria which would resemble to acetogenesis stage. The biogas production lasted until the 21th day then starting decreasing till the last day (30 day) this due to instability of the culture medium of fermentation which became completely poor. COD and BOD showed a significant reduction of 89% and 91% respectively. 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Transport processes in the soil matrix can control the rates of bioremediation of low-solubility contaminants. In this study, experiments were designed to test the hypothesis that diffusion of contaminants within soil aggregates of diameter 40 - 1000 micron was the limiting factor in bioremediation of creosote-contaminated soil. The concentrations of 6 different PAHs (acenaphthene, anthracene, chrysene, fluoranthene, phenanthrene, and pyrene) were monitored during the course of bioremediation of sonicated and non-sonicated soil by an active mixed culture in slurry bioreactors. Sonication of the soil to disperse soil aggregates increased the rate of microbial degradation up to 5 fold, however, there was no significant difference in the final residual concentrations between the two soil treatments. The aggregate size distribution after three weeks of treatment in a slurry bioreactor was comparable in both the sonicated and non-sonicated soils, which was consistent with the independence of the residual concentrations of PAHs on sonication treatment. The soil aggregates were modelled as porous materials, with pores filled with non-aqueous phase liquid and with films of non-aqueous phase liquid on particle surfaces. As the soil aggregates were dispersed, either by sonication or mixing, then the fraction of contaminants in exposed films increased. A diffusion-controlled mass transfer model was developed to represent release of PAHs from the soil, based on this physical model. The estimated diffusion coefficients of four of the PAHs (acenaphthene, phenanthrene, fluoranthene and pyrene ) in the residual creosote phase were in the range 4.4-4.8 x 10-14 cm2/s, while the diffusion coefficients for anthracene and chrysene were lower by a factor of 2. The similar values of diffusion coefficient between the components was consistent with release by diffusion through a viscous residual creosote. The magnitude of the diffusion coefficients was intermediate between the transport properties in high-viscosity oils, and polymers.

Bioremediation of aged and newly clayey soil contaminated with crude oil was investigated in lab-scale using two different strategies (biostimulation-BIOS and bioaugmentation-BIOA), also simulating two different technological options: dynamic biopile (M) and static biopile with forced aeration (B). The inoculum used for bioaugmentation was obtained from the aged contaminated soil. The treatments were performed in triplicates and included one control (original contaminated soil-CONT). The treatments were monitored with soil sampling obtained after 0, 24, 59 and 121 days when the populations of total heterotrophic microorganism (THM), total fungi (TF), and oil-degrading microorganism (ODM) as well as the extracted total petroleum hydrocarbons (TPH) and the 16 polycyclic aromatic hydrocarbons (PAH) prioritized by U.S. EPA were analyzed by gas chromatography. It was observed a trend for reduction of the microbial population density from 0 to 121 days. As expected, the population densities of THM and ODM were much higher in bio-augmented soils in both technologies (BIOA-m and BIOA-b) at day 0. However, after 121 days, the superiority in THM density was observed only in the bioreactor simulating static biopile with forced aeration (BIOA-b). Regarding treatment efficiency, the static biopile with forced aeration performed better in the removal of TPH when associated with bioaugmentation (BIOA-b), being equivalent to the microcosms (simulating dynamic biopile) for the other treatments (CONT and BIOS). For PAH, the superiority of the bioreactor was less conspicuous but observed in both bioremediation strategies (biostimulation BIOS-b and bioaugmentation BIOA-b). The results suggested that regarding TPH, the strategy of bioaugmentation was superior to biostimulation and that the bioreactor (simulating static biopile with forced aeration) reached better contaminant reductions than the microcosm (simulating dynamic biopile). Clayey soil contaminated with crude oil poses big challenges for the bioremediation, due to the texture of the soil favouring adsorption of organic contaminants and due to the complex crude oil composition. The bioprocesses are slow, cleavage of larger molecules are likely to generate smaller hydrocarbons and therefore the elimination of the toxicity is very slow, which may require longer periods and auxiliary tools, such as surfactants.

Contamination of soil by the activities of exploration, production and disposal of oil waste into the environment causes serious damage to the environmental ecosystem, the target of processing by the activated sludge as a model for remediation of petroleum contaminated site. Optimization of oxygen supply becomes special attention in aerobic bioprocess for optimizing the growth of microorganisms to degrade total petroleum hydrocarbons. Thus, the study was focused on determining the performance of dissolved oxygen in degradation of total petroleum hydrocarbons by ex situ activated sludge. The research used biological methods (bioremediation), with the ratio of contaminated soil to water was 20:80%(w/v) and a soil size 40/50 mesh. The degradation process was carried out with 15% and 20% (v/v) activated sludge put into the bioreactor slurry with a capacity of 4 liters and stirring was 90 rpm at a temperature of 30oC as well as aeration and nutrient injection into the bioreactor. TPH analysis was measured by the gravimetric method. The results obtained showed that the performance of dissolved oxygen increased well in the bioreactor slurry at 15% (v/v) and 20% (v/v) activated sludge concentrations was 3.31–8.57 mg/L and 3.5–8.21 mg/L respectively, which had an impact on the level of TPH degradation, namely from 18,000 µg/g to 2870 µg/g and 18,000 µg/g to 1970 µg/g during the 49 days remediation period. In general, activated sludge shows good performance throughout the remediation period.

This work is aimed at evaluating the potentiality of adding a rhamnolipid biosurfactant in a petroleum-bearing soil. For this purpose, dehydrogenase activity and seed germination (Lactuca sativa) testes were performed before the biodegradation assays with different concentrations of rhamnolipid (1 to 15mg for 1g of soil). The addition of 1 and 15 mg g-1 of rhamnolipid was harmful to the soil environment. The biodegradation assays were carried out at room temperature during 45 days in bioreactors containing 450g of a polluted soil with different rhamnolipid concentrations varying from 1 to 15 mg g-1. The nutrients were corrected through the addition of NH4NO3 and KH2PO4, in a nutritional ratio of C:N:P=100:15:1. The humidity was adjusted to 50% of the liquid retention capacity. Besides these assays, a control test was conducted without adding rhamnolipid. TPH (Total petroleum hydrocarbon) removal and seed germination were evaluated at the end of these experiments. When 4 mg g-1 of rhamnolipid were used a TPH removal of about 60% was observed. The biosurfactant addition improved all treatments, except for the assays with addition of 1 and 15 mg g-1 in which a decrease of the bioremediations rates was observed in the toxicity tests.

This study aimed to isolate a bacterial consortium that capable of decomposing PAHs. Three halo-tolerant bacterial strains of Microbacterium paraoxydans B3F (S1), Stenotrophomonas N3 (S2), and Citrobacter NB2 (S3) were isolated from bovine manure. The isolate Microbacterium paraoxydans B3F showed the least resistance to salinity and growth not observed at 2 and 2.5% of NaCl, while isolate Citrobacter NB2 indicated growth in all salinity levels. The PHE biodegradation was more efficient in bacterial consortium compared to pure culture. At the end of the 35th day, the removal efficiency of PHE with an initial concentration of 100 mg/kg for seed volumes of 2, 10, and 20 mL was 33%, 50%, 52%, respectively. The TPHs biodegradation efficiencies at different soil/water ratios of 25%, 50% and 100% were 12%, 28.7 % and 60.8%, respectively. Three halo-tolerant bacteria were isolated from Bovine manure were efficiently used for bioremediation of phenanthrene.