ne of the greatest problems facing most African countries is the inability to grow enough food for her ever-increasing population. One of the constraints is the inherent low fertility of the soils. Research also indicates that a considerable part of the required nitrogen and potassium for intensive cropping could be met by including legumes in crop rotation and by recycling nutrients through the application of good quality compost (John et al. 2013).

Widespread pollution of terrestrial ecosystems with petroleum hydrocarbons (PHCs) has generated a need for remediation and, given that many PHCs are biodegradable, bio- and phyto-remediation are often viable approaches for active and passive remediation. This review focuses on phytoremediation with particular interest on the interactions between and use of plant-associated bacteria to restore PHC polluted sites. Plant-associated bacteria include endophytic, phyllospheric, and rhizospheric bacteria, and cooperation between these bacteria and their host plants allows for greater plant survivability and treatment outcomes in contaminated sites. Bacterially driven PHC bioremediation is attributed to the presence of diverse suites of metabolic genes for aliphatic and aromatic hydrocarbons, along with a broader suite of physiological properties including biosurfactant production, biofilm formation, chemotaxis to hydrocarbons, and flexibility in cell-surface hydrophobicity. In soils impacted by PHC contamination, microbial bioremediation generally relies on the addition of high-energy electron acceptors (e.g., oxygen) and fertilization to supply limiting nutrients (e.g., nitrogen, phosphorous, potassium) in the face of excess PHC carbon. As an alternative, the addition of plants can greatly improve bioremediation rates and outcomes as plants provide microbial habitats, improve soil porosity (thereby increasing mass transfer of substrates and electron acceptors), and exchange limiting nutrients with their microbial counterparts. In return, plant-associated microorganisms improve plant growth by reducing soil toxicity through contaminant removal, producing plant growth promoting metabolites, liberating sequestered plant nutrients from soil, fixing nitrogen, and more generally establishing the foundations of soil nutrient cycling. In a practical and applied sense, the collective action of plants and their associated microorganisms is advantageous for remediation of PHC contaminated soil in terms of overall cost and success rates for in situ implementation in a diversity of environments. Mechanistically, there remain biological unknowns that present challenges for applying bio- and phyto-remediation technologies without having a deep prior understanding of individual target sites. In this review, evidence from traditional and modern omics technologies is discussed to provide a framework for plant–microbe interactions during PHC remediation. The potential for integrating multiple molecular and computational techniques to evaluate linkages between microbial communities, plant communities and ecosystem processes is explored with an eye on improving phytoremediation of PHC contaminated sites.

To reveal the mechanisms of autochthonous bioaugmentation (ABA) in wastewater contaminated with polycyclic aromatic hydrocarbons (PAHs), DNA-stable-isotope-probing (SIP) was used in the present study with the addition of an autochthonous microorganism Acinetobacter tandoii LJ-5. We found LJ-5 inoculum produced a significant increase in phenanthrene (PHE) mineralization, but LJ-5 surprisingly did not participate in indigenous PHE degradation from the SIP results. The improvement of PHE biodegradation was not explained by the engagement of LJ-5 but attributed to the remarkably altered diversity of PHE degraders. Of the major PHE degraders present in ambient wastewater ( Rhodoplanes sp., Mycobacterium sp., Xanthomonadaceae sp. and Enterobacteriaceae sp.), only Mycobacterium sp. and Enterobacteriaceae sp. remained functional in the presence of strain LJ-5, but five new taxa Bacillus, Paenibacillus, Ammoniphilus, Sporosarcina, and Hyphomicrobium were favored. Rhodoplanes, Ammoniphilus, Sporosarcina, and Hyphomicrobium were directly linked to, for the first time, indigenous PHE biodegradation. Sequences of functional PAH-RHDα genes from heavy fractions further proved the change in PHE degraders by identifying distinct PAH-ring hydroxylating dioxygenases between ambient degradation and ABA. Our findings indicate a new mechanism of ABA, provide new insights into the diversity of PHE-degrading communities, and suggest ABA as a promising in situ bioremediation strategy for PAH-contaminated wastewater.

This paper presents the implementation of polynomial vector back propagation algorithm (PVBPA) for estimating the power, torque, specific fuel consumption and presence of carbon monoxide, hydrocarbons in the emission of a direct injection diesel engine. Experimental readings were obtained using the biodiesel prepared form the waste low quality cooking oil collected from the canteen of Sri Sairam Engineering College, India.. This waste cooking oil was due to the preparation of varieties of food (vegetables fried and non vegetarian). Over more than a week, trans esterification was done in chemical lab and the biodiesel was obtained. The biodiesel was mixed in proportions of 10%, 20%, 30%, 40%, 50% with remaining combinations of the diesel supplied by the Indian government. Variable compression ratio (VCR) diesel engine with single cylinder, four stroke diesel type was used. The outputs of the engine as power, torque and specific fuel consumption were obtained from the computational facility attached to the engine. The data collected for different input conditions of the engine was further used to train (PVBPA). The trained PVBPA network was further used to predict the power, torque and brake specific fuel consumption (SFC) for different speed, biodiesel and diesel combinations and full load condition. The estimation performance of the PVBPA network is discussed.

The remediation of mangrove sediment contaminated with mixed polycyclic aromatic hydrocarbons (PAHs) having 3-, 4- and 5-rings by natural attenuation, bioaugmentation, phytoremediation and its combination was compared by greenhouse microcosm studies. At Days 90 and 154, the decreases of PAHs in contaminated mangrove sediment by phytoremediation, planted with one-year old Aegiceras corniculatum, and bioaugmentation, the inoculation of PAH-degrading bacterial strains isolated from mangrove sediment, either SCSH (Mycobacterium parafortuitum) or SAFY (Sphingobium yanoikuyae), were not better than that by natural attenuation (the non-vegetated and un-inoculated microcosms). The populations of SCSH and SAFY in sediment could not be maintained even with repeated inoculation, suggesting that the two isolates were not able to compete with the indigenous microbes and had little enhancement effect. Although some PAHs were accumulated in roots, root uptake only accounted for <15% of the spiked PAHs and the effect of plants on remediation were also insignificant. At the end of the 154-day experiment, the mass balance calculation revealed that the overall losses of PAHs by phytoremediation were comparable to that by bioaugmentation but were lower than that by natural attenuation, especially for the high molecular weight PAHs. Under natural attenuation, around 90% fluorene, 80% phenanthrene, 70% fluoranthene, 68% pyrene and 32% benzo[a]pyrene in contaminated sediment were removed. These results demonstrated that the mangrove sediment itself had sufficient indigenous microorganisms capable of naturally remedying PAH contamination.

The potential for soil contamination by oil spills is growing, due to heavy industrialization and economic development of countries. Due to this fact, the bioremediation has become an alternative to remediate areas through the use of biological agents. Two microorganisms, isolated from a lipid-rich effluent, were used in the bioaugmentation of soils contaminated with diesel oil, lubricating oil and soybean oil. Natural attenuation tests were conducted as controls. The removal of diesel fuel at the time of 21 d were of 18.5%, 7.30% and 11.38%, respectively, for the bioaugmentation with isolated I1 and I2 and natural attenuation. The removal of lubricating oil were 41.6%, 14.16% and 6.91% respectively for the DOI: 10.5433/1679-0375.2012v33n1p73 1 Acadêmicas do Curso de Engenharia Ambiental, Universidade de Passo Fundo; maitcarla@gmail.com, 2 Acadêmicas do Curso de Engenharia Ambiental, Universidade de Passo Fundo; deia_derossi@hotmail.com 3 Mestrando do Programa de Pós-Graduação em Engenharia, Universidade de Passo Fundo; clineidalmagro@gmail.com 4 Docente do Curso de Engenharia Ambiental, Universidade de Passo Fundo; reinehr@upf.br 5 Docente do Programa de Pós-Graduação em Engenharia, Universidade de Passo Fundo; *lmcolla@upf.br

The possibility of enhancing the denitrification of a newly established LECA-based horizontal subsurface flow (HSSF) soil filter receiving pretreated wastewater from a vertical flow filter was studied. The pilot-scale experiment offers evidence regarding the survival and reproduction of introduced microbes taken from an LECA-based HSSF constructed wetland (CW) that has similar internal conditions, after bioaugmentation into newly established LECA-based HSSF CW mesocosms. Bioaugmentation resulted in a trend towards higher and more stable denitrification in the supplemented mesocosms during the nearly half-year study period.

The origin of oil and gas industry in India can be traced back to 1867 when oil was struck at Makum near Margherita in Assam. Since then the consumption and demand of different petroleum products has been increasing steadily. As the usage of these products has increased, it has also given rise to certain problems in the environment such as soil contamination, health risks to the habitual organisms etc. some petroleum products have been found to exert carcinogenic and neurotoxic effects. Though several mechanical and chemical methods are followed for the degradation of these products the rate of contamination is quite high and that makes these methods very expensive. In view of this situation bioremediation gives a better solution compared to the currently existing methods. It provides efficacy, safety on long term use, cost and simplicity of administration with promising opportunity for creating better environment.

The growth population and anthropogenic activity are constantly threatening the environment caused by the accumulation of different kinds of pollutants in the biosphere, especially in soils and sediments. Co-contaminated of environment with toxic organic and inorganic substance is often actually. For the remediation of soils contaminated with mainly petroleum, pesticide and heavy metals, several physical or chemical techniques have been developed inadequately. Inside the technologies “eco-friendly remediation,” the bioremediation have emerged as an option using natural biological activity. Bioremediation are methods where microorganisms degrade one or various pollutants to nontoxic compounds, so working individually or coordinately inside a microbial consortium. A microbial consortium is the natural association of two or more microbial populations of different species, which act together in a complex system. The success of a bioremediation process with pure cultures is very low and restricted. Therefore, use of a microbial consortium appears to be more feasible and reliable.

The abilities of diesel-degrading Bacillus pumilus JLB and Acinetobacter calcoaceticus LT1 were tested in contaminated soils. The effect of nutrient supplementation on bioaugmented samples was also examined. The results show that bio-augmentation and biostimulation accelerated significantly (p < 0.05) the diesel  degradation in the contaminated loam soil and sea sand. Supplementing fertilizers to the augmented loam samples did not result in a significantly higher degradation rate. Furthermore, A. calcoaceticus LT1 alone failed to stimulate higher degradation rates in sea sand unless further supplementation of fertilizer. The results from environmental scanning electron microscopy demonstrate the population increases, then decreases in  augmented samples corresponding to the level of diesel degradation. Fungi-like microorganisms became dominant in contaminated loam soil at the end of the study but not in sea sand. The study shows that it is critical not only to understand the physiology of the inoculum but also how it affects microbial community structure and function before the microorganism being introduced in the contaminated soil. Key words : Diesel, bioremediation, bioattenuation, bioaugmentation, biostimulation

Soil contamination by used lubricating oil from automobiles is a growing concern in many countries, especially in Asian and African continents. Phytoremediation of this polluted soil with non-edible plant like Jatropha curcas offers an environmental friendly and cost-effective method for remediating the polluted soil. In this study, phytoremediation of soil contaminated with 2.5 and 1% (w/w) waste lubricating oil using J. curcas and enhancement with organic wastes [Banana skin (BS), brewery spent grain (BSG) and spent mushroom compost (SMC)] was undertaken for a period of 180 days under room condition. 56.6% and 67.3% loss of waste lubricating oil was recorded in Jatropha remediated soil without organic amendment for 2.5% and 1% contamination, respectively. However addition of organic waste (BSG) to Jatropha remediation rapidly increases the removal of waste lubricating oil to 89.6% and 96.6% in soil contaminated with 2.5% and 1% oil, respectively. Jatropha root did not accumulate hydrocarbons from the soil, but the number of hydrocarbon utilizing bacteria was high in the rhizosphere of the Jatropha plant, thus suggesting that the mechanism of the oil degradation was via rhizodegradation. These studies have proven that J. curcas with organic amendment has a potential in reclaiming hydrocarbon-contaminated soil.

Ship breaking activities along some coastal areas of Bangladesh by traditional beaching method release a huge amount of petroleum hydrocarbons, for example, diesel, petrol, anthracene, phenanthrene cause severe environmental pollution and endanger the entire ecosystem. As an attempt to clean up such petroleum hydrocarbons, a well-timed process bioremediation that involves microbes and plants, offers an efficient, cost-effective, easy-to-use and eco-friendly alternative over physical and chemical treatment approaches. The involvement of naturally-occurring or indigenous fungi has been reported to grow on diverse organic pollutants, and their survival in even extreme environmental conditions make them promising bioremediating agent. The present study aims to isolate and identify petroleum hydrocarbon degrading indigenous fungi from ship breaking yards in order to facilitate the candidacy of the fungi as bioremediating agents. Five out of 14 indigenous fungal isolates were initially screened as petroleum hydrocarbon degraders, which exhibited utilization of petroleum hydrocarbon-rich crude oil in mineral salt medium. The concerned 5 isolates were subsequently validated as the degraders of the same of crude oil in Bushnell Hass medium, exhibiting decolorization of a redox indicator 2,4-dichlorophenol indophenol. The degrader isolates were identified as Cladosporium tenuissium, Fusarium moniliforme, Penicillium corylophilum, Trichoderma koningii and Aspergillus niger after critical analysis of their morphological and cultural characteristics on Potato Dextrose Agar and Czapek Dox Agar media. However, the candidacy of the fungi as bioremediating agent was evaluated by estimating the rate of degradation of common petroleum fuels, kerosene, diesel and octane. All the species degraded octane the most efficiently, followed by diesel and kerosene. Though Fusarium moniliforme caused the maximum degradation of octane (58%) and diesel (56%), Penicillium corylophilum caused the same of kerosene (40%). Hence, this study reveals that the indigenous fungi of the yards spontaneously play a pivotal in restoring a petroleum hydrocarbon-free ecosystem through bioremediation.

Response surface analysis was conducted to optimize the concentrations of Tapis crude oil and duration of incubation in order to achieve optimal microbial growth and crude oil biodegradation. Central Composite Rotatable Design (CCRD) was employed, where the design contained 13 experimental runs with different combinations of incubation time and crude oil concentration. The cultures containing mineral salt medium (MSM) with varying crude oil concentrations were incubated at 30°C, pH6.5 with 150 rpm agitation for 120-336 h. The inoculum contained a consortium of previously identified as oil degrading bacteria and fungi, namely Pseudomonas aeruginosa UKMP-14T, Acinetobacter baumannii UKMP-12T and Trichoderma sp. UKMP-1M and UKMP-2M. The analysis showed the duration of incubation plays a significant role (p<0.05) in affecting the bacterial growth and percentage of total petroleum hydrocarbon (TPH) biodegradation, meanwhile concentrations of Tapis crude oil has insignificant effect on the responses. Interaction of the two variables was found to be significant in affecting all the three responses, namely bacterial population, fungal biomass and percentage of TPH biodegradation. It was predicted through the CCRD that the percentage of biodegradation can be optimized to reach 86% on the 270th h when 5% (v/v) crude oil was used. This predicted value was verified to be achievable and reproducible through validation experiments.

PurposeDiesel fuel represents a permanent source of soil pollution, and its removal is a key factor for human health. To address the limitations of conventional remediation techniques, microwave (MW) heating could be employed due to its great potentiality. This work presents the lab-scale experiments performed to study the potential of MW processing for diesel-polluted soils treatment and related modeling for the optimization of MW systems operating conditions.Materials and methodsA sandy soil was artificially contaminated with diesel fuel, moisturized with different amounts of water content, and thermally treated by MW radiation using a lab-scale apparatus to investigate the effect of soil moisture on soil temperature profiles and contaminant removal kinetics. An operating power, ranging from 100 to 1,000 W, and treatment times of 5, 10, 18, 30, and 60 min were investigated. Contaminant residual concentration values were fitted using the first order kinetic model, and desorption parameters were calculated for each soil at different operating powers.Results and discussionMain results show that the operating power applied significantly influences the contaminant removal kinetics, and the moisture content in soil has a major effect on the final temperature reachable during MW heating. Minimal contaminant concentrations were achievable by applying powers higher than 600 W for a treatment time longer than 60 min. For remediation times shorter than 10 min, which result in a soil temperature of about 100 °C, the effect of the distillation process increases the contaminant removal, whereas for longer times, soil temperature is the main key factor in the remedial treatment.ConclusionsMW thermal desorption of diesel-polluted soil was shown to be governed by pseudo-first-order kinetics, and it could be a better choice for remediation of diesel-polluted soils, compared to several biological, chemical–physical, or conventional thermal treatments, due to its excellent removal efficiency. The results obtained are of scientific and practical interest and represent a suitable tool to optimize the treatment operating conditions and to guide the design and the scale-up of MW treatments for full-scale remediation activities of diesel-polluted soils.

Petroleum products which are used in a wide variety of industries as energy sources and raw materials have become a major concern in pollution of terrestrial and marine environments. The purpose of this study was to assess the potential of indigenous microbial isolates for degradation of diesel fuel. Two most proficient bacterial strains among five isolated strains from polluted soil of an industrial refinery were studied. The isolates then were identified as Pseudomonas aeruginosa and Bacillus subtilis using biochemical tests and 16S rRNA gene sequence analyses. P. aeruginosa showed higher biodegradation efficiency than B. subtilis in shaking flask containing diesel-contaminated water. P. aeruginosa and B. subtilis degraded about 87 and 75% of total hydrocarbons, respectively, in flasks containing 2% diesel and 98% water. The biodegradation efficiency of the isolates decreased as diesel contamination increased from 2 to 5%. The isolates showed significantly higher efficiency on degradation of short-chain hydrocarbons in 20 days, i.e., by using P. aeruginosa, removal efficiency of C10 hydrocarbons was near 90%, while about 69% of C20+ hydrocarbons and 47% of aromatic hydrocarbons were removed. Therefore, the isolates showed high capability in biodegradation of diesel contamination of the refinery.

Petroleum pollution has become a serious environmental problem, which can cause harmful damage to the environment and human health. This pollutant is introduced into the environment from both natural and anthropogenic sources. Various physicochemical and biological treatments were developed for the cleanup of contaminated environments. However, bioremediation is based on the metabolic capabilities of microorganisms, and it is considered as the most basic and reliable way to eliminate contaminants, particularly petroleum and its recalcitrant compounds. It is more effective alternative comparing to classical remediation techniques. A high diversity of potential hydrocarbon degrader’s microorganisms was reported, and bacteria constitute the most abundant group, which has been well studied for hydrocarbon degradation. Several bioremediation approaches through bioaugmentation or/and biostimulation have been successfully applied. The interest on the optimizing of different parameters to achieve successful bioremediation technologies has been increased. In this chapter, we summarize the diversity and the hydrocarbon degradation potential of microorganism involved in the remediation of contaminated environments. We also present an overview of the efficient bioremediation strategies used for the decontamination of polluted marine environments.

Petroleum derivatives are the main energy sources and a potentially pollution source. The increasing use of automobiles generated a proportional increase in gas stations number. With the introduction of the diesel / biodiesel mixture in the Brazilian energy matrix, resulted in increased bioremediation studies of this contaminated soil. Bioreactors are closed systems for variables and treatment control. In addition, it has the possibility to collect the gases produced during the contaminants degradation and treat it. This study aimed to design bioreactors bench and evaluate remediation ability of different experimental conditions of soil contaminated with diesel B5. The bioreactors were constructed using a bottle, provided with bottom drain, air inlet pipe, crushed stone layer to scattering inlet air, thin nylon screen and silicone for sealing. The air flow injected into the system was controlled by rotameters, with flow injection controlled during continuous time intervals. The soil was artificially contaminated with 5% B5 diesel and the humidity was controlled at 50% of the estimated field capacity (30.5%). The nutrients were added to establish nutritional relation C: N: P for 100: 10: 1 and the microorganism received microbial consortium. The tested treatment were monitored Natural Attenuation (no nutrients); biostimulation (with nutrients); biostimulation with bioaugmentation (with nutrients and consortium) with and without air flow. Considering the results found, it was concluded that the projected bioreactors can be used in soil bioremediation studies. It has been demonstrated that naturally soil decontamination presented low level of remediation, proving the need for soil bioremediation methodologies with greater yield. Asystem was a primary factor to remediation contribution of the contaminated soil. It can be concluded that the system with nutritional adjustment, with bioaumento and with aeration system provided the bioremediation more than 80% during 120 days, being the best bioremediation system.

Oil spills to natural environment, either accidental or instinctive seepage, pose a long term threat to all kind of life. Efficient remediation techniques are still on the way of development. In the present study, phytoremediation process in combination with introduction of bacterial consortium in a diesel oil-contaminated soil was investigated in terms of removal of total petroleum hydrocarbons (TPH). A model soil spiked with 50 g diesel oil kg -1 was incubated over a 90-day period at ambient condition in combination with perennial ryegrass (Lolium perenne L.) and with hydrocarbon (HC)-degrading bacterial consortium consisting ten strains isolated from petroleum contaminated soils. The average TPH removal efficiency of the bioaugmented phytoremedation was 57.3%, which was 7.3% more efficient than the phytoremediation alone and 5.3% more than the bioaugmentation alone. Mutual interactive effect of the perennial ryegrass and the inoculated bacterial consortium was expalined in terms of alteration in soil conditions, plant growth, bacterial population and diesel oil degradation in the soil. © 2014 Friends Science Publishers

Microbiological and physicochemical studies of spent lubricating oil contaminated soil amended with wood ash (10% amendment level) were carried out for a period of 56 days. The aim of this study was to evaluate the effect of wood ash in conditioning spent lubricating oil contaminated soil. Serial dilution and pour plate methods were used in enumerating microbial growth. The pH, nitrate, moisture, phosphorus, organic matter content were also determined. The heterotrophic bacteria count ranged from 1.0×104 to 2.1×104 cfu/g for the oil free soil (OFS), 1.3×104 to 2.7×104 cfu/g for the polluted control soil (PCS) and 2.1×104 to 2.3×104 cfu/g for the amended soil (AS) while the fungal count ranged from 4.0×103 to 4.7×104 cfu/g for OFS, 4.0×103 to 8.2×104 cfu/g for PCS and 4.0×103 to 10.8×104 cfu/g for AS. Higher microbial counts were found on the PCS and AS compared to the OFS. There were no significant differences at 5% probability level between the treatments. The organisms isolated were species of Bacillus, Staphylococcus, Micrococcus, Aspergillus, Mucor, Penicillium and Saccharomyces. There were no significant differences (p>0.05) in the moisture content, nitrate, organic matter content and electrical conductivity. However, there were significant differences in the pH, organic carbon and phosphorus contents of the soil samples at 5% probability level. The results obtained in this study demonstrate the potential of wood ash to considerably increase the organic carbon, phosphorus and pH of the soil to slightly alkaline condition which favours the biodegradation of the spent lubricating oil contaminated soil.

Increasing soil pollution problems have caused world-wide concerns. Large numbers of contaminants such as polycyclic aromatic hydrocarbons (PAHs), petroleum and related products, pesticides, chlorophenols and heavy metals enter the soil, posing a huge threat to human health and natural ecosystem. Chemical and physical technologies for soil remediation are either incompetent or too costly. Composting or compost addition can simultaneously increase soil organic matter content and soil fertility besides bioremediation, and thus is believed to be one of the most cost-effective methods for soil remediation. This paper reviews the application of composting/compost for soil bioremediation, and further provides a critical view on the effects of this technology on microbial aspects in contaminated soils. This review also discusses the future research needs for contaminated soils.