This research study explored the efficacy of leaf litter compost as a sustainable soil amendment with the objective of promoting soil health and mitigating the accumulation of potentially toxic elements. The investiga...This research study explored the efficacy of leaf litter compost as a sustainable soil amendment with the objective of promoting soil health and mitigating the accumulation of potentially toxic elements. The investigation encompassed the impact of various organic compost amendments, including leaf compost, cow dung manure, kitchen waste compost, municipal organic waste compost, and vermicompost. The study employed Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to evaluate soil nutrient levels and concentrations of Potentially Toxic Elements (PTEs) such as arsenic, chromium, cadmium, mercury, lead, nickel, and lithium. The fertilization and bioremediation potential of these compost amendments are quantified using an indexing method. Results indicated a substantial increase in overall nutrient levels (carbon, nitrogen, phosphorus, potassium, and sulfur) in soils treated with leaf compost and other organic composts. Fertility indices (FI) are notably higher in compost-amended soils (ranging from 2.667 to 3.938) compared to those amended with chemical fertilizers (ranging from 2.250 to 2.813) across all soil samples. Furthermore, the mean concentrations of PTEs were significantly lower in soils treated with leaf compost and other organic compost amendments compared to those treated with chemical fertilizers amendments. The assessment through the indexing method revealed a high clean index (CI) for leaf compost amendment (ranging from 3.407 to 3.58), whereas the chemical fertilizer amendment exhibits a relatively lower CI (ranging from 2.78 to 3.20). Consequently, leaf compost and other organic composts exhibit the potential to enhance sustainable productivity, promoting soil health and environmental safety by improving nutrient levels and remediating potentially toxic elements in the soil.展开更多
The pollution of ecosystems as a result of urbanization, industrialization and poor agricultural practices is becoming increasingly alarming. This has a major impact on health and the economy. This pollution causes il...The pollution of ecosystems as a result of urbanization, industrialization and poor agricultural practices is becoming increasingly alarming. This has a major impact on health and the economy. This pollution causes illness in humans and animals, even at low levels of exposure, leading to endocrine disorders, congenital malformations, cardiovascular disease, nervous system damage and cancer. They are a brake on redevelopment because of the threats they pose, generally causing an anaerobic environment by blocking the diffusion of air into the soil pores, thus affecting the microbial communities living there and preventing the infiltration of water necessary for plant growth. In an ecosystem subjected to various disturbances, changes can be observed in ecosystem structure and function, including loss of aesthetic values, changes in biomass or productivity, and changes in species composition. These include loss of aesthetic values, changes in biomass or productivity, and altered species composition, as a result of habitat loss, disruption of food webs and variations in macro- and micro-climatic environmental conditions. Respect for the environment is becoming a major concern in today’s society. To remedy this, the concept of biological control was used as an alternative, with the selection of microorganisms of bioremediator interest. Twenty (20) isolates, including 10 (50%) from the Pseudomonas genus and 10 (50%) from the Bacillus genus, were isolated from landfills, identified and tested to assess their biofertilization (phosphate solubilization) and depollution (hydrocarbon degradation) potential, and to inhibit the growth of certain microorganisms. The results showed that all Pseudomonas and Bacillus isolates solubilized inorganic phosphate, although this activity was higher in Bacillus. All Bacillus inhibited the growth of all the pathogens included in this study, while Pseudomonas only inhibited the growth of E. coli. With regard to their ability to degrade hydrocarbons, these bacteria all showed exponential growth kinetics in the presence of gasoline. These kinetics evolved as a function of the number of days. The results obtained from this work leave no doubt as to the capacity of microorganisms to be used on a large scale as soil biofertilizers to restore soil integrity and promote sustainable agriculture, but also as biodepollutants to purify ecosystems.展开更多
The comparative effectiveness of remediating water polluted with crude oil, using environment-friendly bacteria (Pseudomonas aeruginosa) and fungi (Aspergillus niger) were investigated. The samples were separately tre...The comparative effectiveness of remediating water polluted with crude oil, using environment-friendly bacteria (Pseudomonas aeruginosa) and fungi (Aspergillus niger) were investigated. The samples were separately treated with Aspergillus niger and Pseudomonas aeruginosa. The bioremediation kinetic efficiency for these systems was studied. At the end of the bioremediation periods, the oil and grease content of the samples decreased from 47.0 mg/L in the untreated sample to 7.0 mg/L after 20 days when inoculated with bacteria while the sample inoculated with fungi decreased to 10.0 mg/L. Post analysis when inoculated with bacteria showed a fall in the value of the biological oxygen demand (BOD) from 73.84 mg/L to 33.28 mg/L after 20 days, while, the fungi inoculated sample showed a reduction from 73.84 mg/L to 38.48 mg/L. The biodegradation process with the bacteria was consistent with the pseudo-first-order model with a rate constant of 0.0891 day<sup>-1</sup>, while the biodegradation process with the fungi was consistent with the first order reaction model with a rate constant of 0.422 day<sup>-1</sup>. The degree of degradation after the 20<sup>th</sup> day of inoculation with Pseudomonas aeruginosa was 85.11%, while with Aspergillus niger was 78.72%. Thus, the results obtained showed that, Pseudomonas aeruginosa performed better than Aspergillus niger. The bioremediation data with fungi fitted the first-order model, while that of the bacteria fitted the pseudo-first-order model. Therefore, the data obtained in this study could be applied in the design of a bioremediation system for potential application to remediation of crude oil polluted water.展开更多
The remediation of crude oil-impacted soil has always been a challenge in different soil environments and climatic conditions. Bioremediation technology has offered a breakthrough in restoring crude oil-impacted soil/...The remediation of crude oil-impacted soil has always been a challenge in different soil environments and climatic conditions. Bioremediation technology has offered a breakthrough in restoring crude oil-impacted soil/sediment in muddy, dry soil and wetlands. Though, there have been varied environmental conditions that have hampered the success of the bioremediation process. This study has evaluated the effectiveness of a biostimulated bioremediation of crude oil-impacted soil using some design criteria—nutrient amendment (NPK fertilizer) and moisture content. Soil sample sets—A, B, C, D, E, F, and G were impacted with crude oil at a ratio of 10 g/kg and amended with varying amounts of nutrient 30, 60, and 80 g of N.P.K fertilizer. The medium for the inoculation of the nutrient was water and the volume of water applied varied from 30% to 80% saturation. The soil sample sets were harvested at an interval of 3 months for 180 days to determine the concentration of total petroleum hydrocarbon left in the soil. The analysis of the total petroleum hydrocarbon was achieved using a GC-FID with a capillary column and autosampler. Soil samples were extracted with mixed solvent dichloromethane and acetone at a 1:1 ratio. The total petroleum hydrocarbon results show that biostimulated bioremediation achieved better results in soil sample sets with low moisture content (30% water saturation) and moderate nutrient amendment. The biodegradation of the sample sets with high water saturation and a high nutrient amendment was slow with a higher amount of total hydrocarbon content at the end of the 180 days. The variability in the hydrocarbon degradation pattern of contaminated soil shows that biostimulated bioremediation achieved better results in soils with low moisture content than in soil environments with high water content (saturation). More so, nutrient overdosing of the substrate hampered the effectiveness of the remediation process.展开更多
A bacterial strain (AD26) capable of utilizing atrazine as a sole nitrogen source for growth was isolated from an industrial wastewater sample by enrichment culture. The 16S rRNA gene sequencing identified AD26 as an ...A bacterial strain (AD26) capable of utilizing atrazine as a sole nitrogen source for growth was isolated from an industrial wastewater sample by enrichment culture. The 16S rRNA gene sequencing identified AD26 as an Arthrobacter sp. PCR assays indicated that AD26 contained atrazine-degrading genes trzN and atzBC. The trzN gene of AD26 only differs from the trzN of Arthrobacter aurescens TC1 by one base (A→T at 907) and one amino acid (Met→Leu at 303). The specific activity of trzN of AD26 in crude cell extract was 0.28 U/mg, which was 1.2 times that of TC1. This strain has shown faster growth and atrazine-degradation rates in atrazine-containing minimal media than two well characterized atrazine-degrading bacteria, Pseudomonas sp. ADP and Arthrobacter aurescens TC1. After incubating for 48 h at 30°C, the OD600 of AD26 reached 2.6 compared with 1.33 of ADP. AD26 was capable of degrading 500 mg/L of atrazine in minimal medium at 95% in 72 h, while the degradative rates by TC1 and ADP were only 90% and 86%, respectively. A bioremediation trial of contaminated soil has indicated that AD26 can degrade as high as 98% of atrazine contained in soil (300 mg/kg) after incubating for 20 d at 26°C, nominating this strain as a good candidate for use in bioremediation programs.展开更多
Lead contamination in water is a widespread problem throughout the world and results from industrial use and processing of lead ore. Bio-availability of lead can be hazardous for children and causes mental retardation...Lead contamination in water is a widespread problem throughout the world and results from industrial use and processing of lead ore. Bio-availability of lead can be hazardous for children and causes mental retardation. The use of lead free petrol is one measure to check this pollution, but this heavy metal is also present in industrial effluents and need to be removed before these effluents are discharged to natural land or water and as well as to the environment. Using bioremediation, bacteria could render lead non-bioavailable would provide an alternative option for detoxifying this contaminant in the environment. The property of some species of bacteria and algae, to extract metals from their surroundings, has been utilized to purify industrial effluents. The first step in devising a bioremediation strategy is to identify candidate bacterial strains capable of modifying the contaminant. Biotechnological approaches are recommended for extraction of metal forms can be grown in ponds where effluents (rich in heavy metals) are discharged. The microbes will extract the heavy metals and sequester them inside their cell membranes. The goal of the present study was to examine the capacity of lead resistant bacteria and bioremediation of lead contaminated water.展开更多
With the rapid development of mining,the soil heavy metal contamination is increasingly serious in Shaoguan,directly affecting the production of crops. This paper analyzes the farmland soil heavy metal contamination i...With the rapid development of mining,the soil heavy metal contamination is increasingly serious in Shaoguan,directly affecting the production of crops. This paper analyzes the farmland soil heavy metal contamination in the mining area of Shaoguan and the causes of heavy metal contamination in recent years,brings forward the bioremediation measures to control soil heavy metal contamination,and points out the development direction of bioremediation in farmland soil heavy metal contamination in the mining area.展开更多
With increasing demands of fossil fuel energy, extensive exploration of natural sources has caused a number of large scale accidental spills of crude oil and resulted in some significantly environmental disasters. The...With increasing demands of fossil fuel energy, extensive exploration of natural sources has caused a number of large scale accidental spills of crude oil and resulted in some significantly environmental disasters. The consequence of oil pollution to environment and human health has brought a serious challenge to environmental scientists. Physical and chemical approaches to cleanup oil spills are too expensive and create adverse effects. Bioremediation has shown a great potential and competitive privilege because of environment friendly and cost effective. A number of efficient microbial strains have been identified and isolated, which can effectively degrade various components of petroleum oil. However, the biodegradation efficiency is usually limited by abiotic factors, such as temperature and pH, which are hardly to be controlled in the in situ condition but adequate oxygen supply and nutrient balancing are of importance to impact microbial functions. Therefore, this review especially addresses potential approaches to improving bioremediation of crude oil by supplying solid oxygen and adjusting C: N: P ratio to optimize microbial activities in order to improve the effectiveness and efficacy of bioremediation of crude oil pollutants. In addition, it also elucidates advantages of bioremediation, isolation of selective microbial strains, and evaluation of the biodegradation rates.展开更多
Leakage of oil and its derivatives into the soil can change the engineering behavior of soil as well as cause environmental disasters.Also,recovering the contaminated sites into their natural condition and making cont...Leakage of oil and its derivatives into the soil can change the engineering behavior of soil as well as cause environmental disasters.Also,recovering the contaminated sites into their natural condition and making contaminated materials as both environmentally and geotechnically suitable construction materials need the employment of remediation techniques.Bioremediation,as an efficient,low cost and environmentalfriendly approach,was used in the case of highly plastic clayey soils.To better understand the change in geotechnical properties of highly plastic fine-grained soil due to crude oil contamination and bioremediation,Atterberg limits,compaction,unconfined compression,direct shear,and consolidation tests were conducted on natural,contaminated,and bioremediated soil samples to investigate the effects of contamination and remediation on fine-grained soil properties.Oil contamination reduced maximum dry density(MDD),optimum moisture content(OMC),unconfined compressive strength(UCS),shear strength,swelling pressure,and coefficient of consolidation of soil.In addition,contamination increased the compression and swelling indices and compressibility of soil.Bioremediation reduced soil contamination by about 50%.Moreover,in comparison with contaminated soil,bioremediation reduced the MDD,UCS,swelling index,free swelling and swelling pressure of soil,and also increased OMC,shear strength,cohesion,internal friction angle,failure strain,porosity,compression index,and settlement.Microstructural analyses showed that oil contamination does not alter the soil structure in terms of chemical compounds,elements,and constituent minerals.While it decreased the specific surface area of the soil,and the bioremediation significantly increased the mentioned parameters.Bioremediation resulted in the formation of quasi-fibrous textures and porous and agglomerated structures.As a result,oil contamination affected the mechanical properties of soil negatively,but bioremediation improved these properties.展开更多
The relationships between nutrient dynamics,microbial community,and macrofauna are important in bioremediation systems.In this study,we examined the effects of marine clam Scapharca subcrenata sedimentary activities o...The relationships between nutrient dynamics,microbial community,and macrofauna are important in bioremediation systems.In this study,we examined the effects of marine clam Scapharca subcrenata sedimentary activities on the microbial assemblages,benthic nutrient chemistry,and its subsequent remediation impacts on organic effluent in the sediment of an aquaculture wastewater bioremediation system.The results showed that microbial community composition differed significantly in the clam area(ANOSIM,R=0.707,P=0.037).Pyrosequencing of bacterial 16S rRNA gene revealed a total of 48 unique phyla,79 classes,107 orders,197 families,and 321 genera amongst all samples.The most dominant bacterial assemblages were Proteobacteria,Bacteroidetes,Acidobacteria,Firmicutes,Verrucomicrobia,and Actinobacteria,with Bacteroidetes and Firmicutes significantly higher in all treatment samples than control(P<0.001).All dominant phyla in the list were shared across all samples and accounted for 89%(control)and 97%(treatment)of the total 16S rRNA.The nutrient flux rates from the sediments into the water(treatment group)were 51%(ammonium),88%(nitrate),77%(nitrite)and 45%(phosphate)higher,relative to the control implying increased mineralization,degradability,and mobility of the benthic nutrients.Similarly,significantly increased oxygen consumption rates were evident in the clam area signifying improved oxygen distribution within the sediment.The organic effluent contents associated with total-organic matter,carbon,nitrogen,and,phosphate were lower among the clam treatments relative to the control.Our results describe the potential roles and mechanisms contributed by marine bivalve S.subcrenata on benthic-bacterial-community assembly,nutrient balance,and effluent reduction in the sediments of aquaculture wastewaters bioremediation system.展开更多
Present study was conducted to clarify soil pH and temperature influence on different atrazine bioremediation techniques. For this purpose, sodium citrate, Arthrobactor sp. strain DNS10, sawdust and animal manure were...Present study was conducted to clarify soil pH and temperature influence on different atrazine bioremediation techniques. For this purpose, sodium citrate, Arthrobactor sp. strain DNS10, sawdust and animal manure were selected to clarify their atrazine remediation efficiency under pH 5, 7 and 9 and temperatures 20, 30 and 40℃, respectively. Results showed that atrazine remediation was generally optimized at pH 7 and 30℃ for all the treatments except sodium citrate as soil treated with sawdust was not temperature dependant, but at pH 5 remediation process was determined slower. Atrazine remediation in soil with no additional amendment was only 34%, while in soil treated with sawdust, DNS10, sodium citrate and animal manure were 75.17%, 89%, 74.17% and 76.83% at optimized pH and temperature. Overall atazine removal rate was significantly(≥0.01) higher with increasing in temperature at all the selected pH.展开更多
To study the control effect of algicidal bacteria on blue-green algal blooms in natural conditions,three algicidal bacterial strains were used to make a compound algal inhibiting agent,and the removal effects of the a...To study the control effect of algicidal bacteria on blue-green algal blooms in natural conditions,three algicidal bacterial strains were used to make a compound algal inhibiting agent,and the removal effects of the algal inhibiting agent on algae,nitrogen,phosphorus,organic matter,and chlorophyll a in Chendian pool and Qiangwei pool of Quancheng Park in Jinan City were analyzed. The results show that the algal inhibiting agent could eliminate the blue-green algal blooms. 54 days later,chlorophyll a content in the water bodies reduced to below 0. 06 mg/L,and both COD_(Cr)and BOD_5 decreased significantly. NH_4^+-N and TP content were lower than 2 and 0. 05 mg/L respectively. The removal rate of COD_(Cr)was slightly low( 33%-48%),and the removal rates of other indicators were higher than 60%. It is clearly seen that the algal inhibiting agent could quickly eliminate the algal blooms and had a notable effect on the recovery of the eutrophic water bodies.展开更多
The objective of this study was designed to evaluate the effects of biostimulation and bioaugmentation amendment agents (NPK fertilizer, Tween 80 and mixed culture) on the bioremediation of tropical soil samples artif...The objective of this study was designed to evaluate the effects of biostimulation and bioaugmentation amendment agents (NPK fertilizer, Tween 80 and mixed culture) on the bioremediation of tropical soil samples artificially contaminated with Weathered Bonny Light Crude Oil (WBLCO). Response Surface Methodology (RSM) with Box Behnken Design (BBD) was used with three levels and three factors of NPK fertilizer (2 - 6 g), Tween 80 (5 - 15 mg/l) and mixed culture (0.5 - 1.5 g/l) as independent variables and WBLCO removal as dependent variable (response) in a six weeks remediation period. The results showed that the rate of WBLCO removal generally increased with increase in the amount of NPK fertilizer, Tween 80 and mixed culture (biomass), respectively. A statistically significant (P < 0.0001) second-order quadratic regression model for WBLCO removal (using design-expert statistical program (v. 6.0.8)) with a coefficient of determination, R (=0.9996) was obtained. Numerical optimization technique based on desirability function was carried out to optimize the bioremediation process. The optimum values for biostimulation and bioaugmentation amendment agents to achieve a predicted maximum WBLCO removal of 84.88 percent were found to be: NPK fertilizer, 4.25 g;Tween 80, 10.22 mg/l and mixed culture, 0.46 g/l. At this optimum point, the observed WBLCO removal was found to be 83.79 percent. The statistical analyses and the closeness of the experimental results and model predictions show the reliability of the regression model and thus, biostimulation and bioaugmentation of indigenous microbial density and activity can reduce remediation period of petroleum hydrocarbon contaminated environment and subsequently the cost of remediation.展开更多
The long-term oil exploitation in oil fields has led to pollution of surrounding soil, creating a serious ecological problem. In order to promote and improve the application of microbial remediation in oil contaminate...The long-term oil exploitation in oil fields has led to pollution of surrounding soil, creating a serious ecological problem. In order to promote and improve the application of microbial remediation in oil contaminated soil, experiment is carried out in polluted area in Zhongyuan Oilfield. In the experiment, indigenous microorganisms and other physical and chemical methods are employed, ryegrass is grown, and environmental factors in soil are regulated to degrade the oil and treat the polluted soil. Results show that when the average oil content in the soil is about 523.08 mg/kg, 65 days' remediation through plants and microorganisms could help bring the oil content down to 74.61 mg/kg, achieving a degradation rate of 85.74%; through salinity treatment, salt content in soil is reduced by 62.93-82.03% to 399-823 mg/kg from previous 2.22 g/kg. Through this experiment, the bioremediation method is improved and its effectiveness and feasibility are testified. The result has been applied in Zhongyuan Oilfield and has brought fair ecological and economic benefits, providing technical support to the treatment of contaminated soil of the same kind, and offering some insights to the treatment of soil contaminated by other organic pollutants.展开更多
Oil exploitation in many African countries is associated with litigation and conflicts to water and soil pollution. It is because of inadequate planning for management of oil spills and industrial effluents in environ...Oil exploitation in many African countries is associated with litigation and conflicts to water and soil pollution. It is because of inadequate planning for management of oil spills and industrial effluents in environmentally sustainable manner. Uganda’s natural resources such as soils and water bodies are threatened by contamination due to rapid industrialization and rural-urban migration in established Industrial Business Parks and planned oil and gas production at Albertine Graben Region. The low level of compliance to industrial effluents discharge standards relevant to specific environmental receptors and activities within oil and gas sector development pose a big question of how to sustain the biodiversity and natural resource management. Experiences from elsewhere have shown bioremediation as a viable and proven option to provide potentially manageable solutions to resulting pollution as a substitute to modern well-known remediation methods, for it is relatively cheaper, more efficient and minimal toxic byproducts after treatment. The most used bioremediation agents in different studies reviewed are bacterial species especially Pseudomonas and Bacillus, followed by Aspergillus a fungi species, microalgae and aquatic plants such as duckweed, macrophytes and pteridophytes. Regardless of the waste produced in either oil and gas sector or industries, these agents have shown greater biodegradation rates. Pseudomonas sp. has a degradation efficiency of oil compounds ranging from 90% - 100%, and Aspergillus sp. 75% - 95%. Some aquatic plants can thrive in created wetlands with relatively still water such as Phragmites australis which can degrade hydrocarbons especially Aromatic compounds with benzene ring up to 95%. It can thrive in salty water with high pH range of 4.8 - 8.2. With industrial wastewater, algae is the most dominant with the degradation rates varying from 65% -100% and bacteria at 70% - 90%. Most of the reported results are in the developed country context. In developing countries, duckweed is reported as the commonest aquatic plant in wastewater treatment for removal of heavy metals because it is more tolerant to a wide range of environmental conditions and produce biomass faster. It has a removal rate of heavy metals between 90% and 100%. Basing on literature data analysis, bacteria are more suitable for treating water from oil pollution using Pseudomonas sp. Phragmites australis is suited for cleaning up oil in both water and soil. Duckweed is the best in treating water polluted with industrial effluents. This paper presents the different bioremediation methods that Uganda can potentially apply to mitigate the increased risk of environmental pollutions from planned industrialization and oil and gas development in the Albertine Graben Region.展开更多
Heavy metal contamination of the biosphere has increased sharply over the last century. Anthropogenic activities such as industrialisation and demographic growth can be considered as the main causes of it. Soil contam...Heavy metal contamination of the biosphere has increased sharply over the last century. Anthropogenic activities such as industrialisation and demographic growth can be considered as the main causes of it. Soil contamination affects every organism and poses major environmental and human health problems worldwide. The issue has been addressed in the past and a few methodologies have been developed in order to effectively clean up the contaminated areas. However, many of these remedies are very aggressive and can damage the soil. This paper focuses on the use of gentler techniques, which take advantage of the properties of several plants and wildflowers that absorb heavy metals and polycyclic aromatic hydrocarbons, and their potential application in megacities such as Hong Kong.展开更多
This study discusses factors affecting various processes involved in bioremediation coupled with electrokinetics. The study presents innovative solutions, and proposes new directions. Environmental conditions that hav...This study discusses factors affecting various processes involved in bioremediation coupled with electrokinetics. The study presents innovative solutions, and proposes new directions. Environmental conditions that have an influence on the characteristics, behavior, and metabolism of indigenous microorganisms are presented. The discussion focuses on overcoming the unfavorable conditions created by electrolysis reactions, prolongation the survival of the microbes at contaminated sites, increase of microbial enzyme secretion, improvement of the indigenous bacteria metabolic pathways, and exploration of metagenomics resources from soil biota. The challenge facing the implementation of conventional bioremediation techniques in precisely and effectively delivering nutrients to indigenous bacteria, particularly in soils with tortuous paths and low hydraulic conductivity is discussed. Current knowledge in application of enhanced biostimulation using electrokinetics is reviewed. The implementation of bioaugmentation in bioremediation coupled with electrokinetics to enhance the outcome of bioremediation is presented. Effects of phenomena associated with electrokinetics in the hybrid remediation approach are discussed.展开更多
Palm oil mill effluent (POME) is liquid waste produced from palm oil extraction process. Discharging it to the river without treatment is violation according to Malaysia Environment of Quality Act (EQA) 1974. In Malay...Palm oil mill effluent (POME) is liquid waste produced from palm oil extraction process. Discharging it to the river without treatment is violation according to Malaysia Environment of Quality Act (EQA) 1974. In Malaysia, ponding system is a conventional treatment method for POME due to its economical and simple process. The treatment process mainly involves two main treatment phases;anaerobic and aerobic degradation. Anaerobic degradation has a proven track record in reducing pollutant properties in POME up to 85%. The real challenge is to increase the efficiency of aerobic process as the biological oxygen demand (BOD) discharge limit has been further reduced from 100 mg·L<sup>-1</sup> to less than 20 mg·L<sup>-1</sup>. One of economical and feasible approach to increase the efficiency of aerobic phase is via bioremediation. This paper describes the limitation of aerobic degradation in ponding system, besides discussed on the important aspects that need to be optimized for a success implementation of bioremediation and its challenges.展开更多
This review describes a new means of control and stimulation of microorganisms involved in the bioremediation of sediments and waterlogged soils. This emerging technology is derived from sedimentary microbial fuel cel...This review describes a new means of control and stimulation of microorganisms involved in the bioremediation of sediments and waterlogged soils. This emerging technology is derived from sedimentary microbial fuel cells, and consists in ensuring aerobic respiration of aerobic microbial populations in anaerobic conditions by means of a fixed potential anode in order to evacuate the electrons coming from the microbial respiratory chains. This review describes the conceptual basis of the electro-bioremediation, the material devices used (electrode set-ups and spacing), and finally studies the various devices published since the bench tests until the scarce in-field implementations.展开更多
There is a worldwide distribution of heavy metal pollution that can be managed with a bioremediation approach using microorganisms. Several bacterial species belonging to the Proteobacteria have been shown to tolerate...There is a worldwide distribution of heavy metal pollution that can be managed with a bioremediation approach using microorganisms. Several bacterial species belonging to the Proteobacteria have been shown to tolerate heavy metal stress, including toxic salts of noblemetals. Rhodobacter sphaeroides, a model bacterium has previously been utilized for bioremediation studies. A bioinformatics approach was employed here to identify the distribution of genes associated with heavy metal tolerance among the sequenced bacterial genomes currently available on the NCBI database. The distribution of these genes among different groups of bacteria and the Cluster of Orthologous Groups (COGs) were further characterized. A total of 170,000 heavy metal related genes were identified across all bacterial species, with a majority of the genes found in Proteobacteria (46%) and Terrabacteria (39%). Analysis of COGs revealed that the majority of heavy metal related genes belong to metabolism (COG 3), including ionic transport, amino acid biosynthesis, and energy production.展开更多
文摘This research study explored the efficacy of leaf litter compost as a sustainable soil amendment with the objective of promoting soil health and mitigating the accumulation of potentially toxic elements. The investigation encompassed the impact of various organic compost amendments, including leaf compost, cow dung manure, kitchen waste compost, municipal organic waste compost, and vermicompost. The study employed Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to evaluate soil nutrient levels and concentrations of Potentially Toxic Elements (PTEs) such as arsenic, chromium, cadmium, mercury, lead, nickel, and lithium. The fertilization and bioremediation potential of these compost amendments are quantified using an indexing method. Results indicated a substantial increase in overall nutrient levels (carbon, nitrogen, phosphorus, potassium, and sulfur) in soils treated with leaf compost and other organic composts. Fertility indices (FI) are notably higher in compost-amended soils (ranging from 2.667 to 3.938) compared to those amended with chemical fertilizers (ranging from 2.250 to 2.813) across all soil samples. Furthermore, the mean concentrations of PTEs were significantly lower in soils treated with leaf compost and other organic compost amendments compared to those treated with chemical fertilizers amendments. The assessment through the indexing method revealed a high clean index (CI) for leaf compost amendment (ranging from 3.407 to 3.58), whereas the chemical fertilizer amendment exhibits a relatively lower CI (ranging from 2.78 to 3.20). Consequently, leaf compost and other organic composts exhibit the potential to enhance sustainable productivity, promoting soil health and environmental safety by improving nutrient levels and remediating potentially toxic elements in the soil.
文摘The pollution of ecosystems as a result of urbanization, industrialization and poor agricultural practices is becoming increasingly alarming. This has a major impact on health and the economy. This pollution causes illness in humans and animals, even at low levels of exposure, leading to endocrine disorders, congenital malformations, cardiovascular disease, nervous system damage and cancer. They are a brake on redevelopment because of the threats they pose, generally causing an anaerobic environment by blocking the diffusion of air into the soil pores, thus affecting the microbial communities living there and preventing the infiltration of water necessary for plant growth. In an ecosystem subjected to various disturbances, changes can be observed in ecosystem structure and function, including loss of aesthetic values, changes in biomass or productivity, and changes in species composition. These include loss of aesthetic values, changes in biomass or productivity, and altered species composition, as a result of habitat loss, disruption of food webs and variations in macro- and micro-climatic environmental conditions. Respect for the environment is becoming a major concern in today’s society. To remedy this, the concept of biological control was used as an alternative, with the selection of microorganisms of bioremediator interest. Twenty (20) isolates, including 10 (50%) from the Pseudomonas genus and 10 (50%) from the Bacillus genus, were isolated from landfills, identified and tested to assess their biofertilization (phosphate solubilization) and depollution (hydrocarbon degradation) potential, and to inhibit the growth of certain microorganisms. The results showed that all Pseudomonas and Bacillus isolates solubilized inorganic phosphate, although this activity was higher in Bacillus. All Bacillus inhibited the growth of all the pathogens included in this study, while Pseudomonas only inhibited the growth of E. coli. With regard to their ability to degrade hydrocarbons, these bacteria all showed exponential growth kinetics in the presence of gasoline. These kinetics evolved as a function of the number of days. The results obtained from this work leave no doubt as to the capacity of microorganisms to be used on a large scale as soil biofertilizers to restore soil integrity and promote sustainable agriculture, but also as biodepollutants to purify ecosystems.
文摘The comparative effectiveness of remediating water polluted with crude oil, using environment-friendly bacteria (Pseudomonas aeruginosa) and fungi (Aspergillus niger) were investigated. The samples were separately treated with Aspergillus niger and Pseudomonas aeruginosa. The bioremediation kinetic efficiency for these systems was studied. At the end of the bioremediation periods, the oil and grease content of the samples decreased from 47.0 mg/L in the untreated sample to 7.0 mg/L after 20 days when inoculated with bacteria while the sample inoculated with fungi decreased to 10.0 mg/L. Post analysis when inoculated with bacteria showed a fall in the value of the biological oxygen demand (BOD) from 73.84 mg/L to 33.28 mg/L after 20 days, while, the fungi inoculated sample showed a reduction from 73.84 mg/L to 38.48 mg/L. The biodegradation process with the bacteria was consistent with the pseudo-first-order model with a rate constant of 0.0891 day<sup>-1</sup>, while the biodegradation process with the fungi was consistent with the first order reaction model with a rate constant of 0.422 day<sup>-1</sup>. The degree of degradation after the 20<sup>th</sup> day of inoculation with Pseudomonas aeruginosa was 85.11%, while with Aspergillus niger was 78.72%. Thus, the results obtained showed that, Pseudomonas aeruginosa performed better than Aspergillus niger. The bioremediation data with fungi fitted the first-order model, while that of the bacteria fitted the pseudo-first-order model. Therefore, the data obtained in this study could be applied in the design of a bioremediation system for potential application to remediation of crude oil polluted water.
文摘The remediation of crude oil-impacted soil has always been a challenge in different soil environments and climatic conditions. Bioremediation technology has offered a breakthrough in restoring crude oil-impacted soil/sediment in muddy, dry soil and wetlands. Though, there have been varied environmental conditions that have hampered the success of the bioremediation process. This study has evaluated the effectiveness of a biostimulated bioremediation of crude oil-impacted soil using some design criteria—nutrient amendment (NPK fertilizer) and moisture content. Soil sample sets—A, B, C, D, E, F, and G were impacted with crude oil at a ratio of 10 g/kg and amended with varying amounts of nutrient 30, 60, and 80 g of N.P.K fertilizer. The medium for the inoculation of the nutrient was water and the volume of water applied varied from 30% to 80% saturation. The soil sample sets were harvested at an interval of 3 months for 180 days to determine the concentration of total petroleum hydrocarbon left in the soil. The analysis of the total petroleum hydrocarbon was achieved using a GC-FID with a capillary column and autosampler. Soil samples were extracted with mixed solvent dichloromethane and acetone at a 1:1 ratio. The total petroleum hydrocarbon results show that biostimulated bioremediation achieved better results in soil sample sets with low moisture content (30% water saturation) and moderate nutrient amendment. The biodegradation of the sample sets with high water saturation and a high nutrient amendment was slow with a higher amount of total hydrocarbon content at the end of the 180 days. The variability in the hydrocarbon degradation pattern of contaminated soil shows that biostimulated bioremediation achieved better results in soils with low moisture content than in soil environments with high water content (saturation). More so, nutrient overdosing of the substrate hampered the effectiveness of the remediation process.
文摘A bacterial strain (AD26) capable of utilizing atrazine as a sole nitrogen source for growth was isolated from an industrial wastewater sample by enrichment culture. The 16S rRNA gene sequencing identified AD26 as an Arthrobacter sp. PCR assays indicated that AD26 contained atrazine-degrading genes trzN and atzBC. The trzN gene of AD26 only differs from the trzN of Arthrobacter aurescens TC1 by one base (A→T at 907) and one amino acid (Met→Leu at 303). The specific activity of trzN of AD26 in crude cell extract was 0.28 U/mg, which was 1.2 times that of TC1. This strain has shown faster growth and atrazine-degradation rates in atrazine-containing minimal media than two well characterized atrazine-degrading bacteria, Pseudomonas sp. ADP and Arthrobacter aurescens TC1. After incubating for 48 h at 30°C, the OD600 of AD26 reached 2.6 compared with 1.33 of ADP. AD26 was capable of degrading 500 mg/L of atrazine in minimal medium at 95% in 72 h, while the degradative rates by TC1 and ADP were only 90% and 86%, respectively. A bioremediation trial of contaminated soil has indicated that AD26 can degrade as high as 98% of atrazine contained in soil (300 mg/kg) after incubating for 20 d at 26°C, nominating this strain as a good candidate for use in bioremediation programs.
文摘Lead contamination in water is a widespread problem throughout the world and results from industrial use and processing of lead ore. Bio-availability of lead can be hazardous for children and causes mental retardation. The use of lead free petrol is one measure to check this pollution, but this heavy metal is also present in industrial effluents and need to be removed before these effluents are discharged to natural land or water and as well as to the environment. Using bioremediation, bacteria could render lead non-bioavailable would provide an alternative option for detoxifying this contaminant in the environment. The property of some species of bacteria and algae, to extract metals from their surroundings, has been utilized to purify industrial effluents. The first step in devising a bioremediation strategy is to identify candidate bacterial strains capable of modifying the contaminant. Biotechnological approaches are recommended for extraction of metal forms can be grown in ponds where effluents (rich in heavy metals) are discharged. The microbes will extract the heavy metals and sequester them inside their cell membranes. The goal of the present study was to examine the capacity of lead resistant bacteria and bioremediation of lead contaminated water.
基金Supported by National Natural Science Foundation of China(U1033004-06)Guangxi Key Agricultural Science Planning Project(201528)
文摘With the rapid development of mining,the soil heavy metal contamination is increasingly serious in Shaoguan,directly affecting the production of crops. This paper analyzes the farmland soil heavy metal contamination in the mining area of Shaoguan and the causes of heavy metal contamination in recent years,brings forward the bioremediation measures to control soil heavy metal contamination,and points out the development direction of bioremediation in farmland soil heavy metal contamination in the mining area.
文摘With increasing demands of fossil fuel energy, extensive exploration of natural sources has caused a number of large scale accidental spills of crude oil and resulted in some significantly environmental disasters. The consequence of oil pollution to environment and human health has brought a serious challenge to environmental scientists. Physical and chemical approaches to cleanup oil spills are too expensive and create adverse effects. Bioremediation has shown a great potential and competitive privilege because of environment friendly and cost effective. A number of efficient microbial strains have been identified and isolated, which can effectively degrade various components of petroleum oil. However, the biodegradation efficiency is usually limited by abiotic factors, such as temperature and pH, which are hardly to be controlled in the in situ condition but adequate oxygen supply and nutrient balancing are of importance to impact microbial functions. Therefore, this review especially addresses potential approaches to improving bioremediation of crude oil by supplying solid oxygen and adjusting C: N: P ratio to optimize microbial activities in order to improve the effectiveness and efficacy of bioremediation of crude oil pollutants. In addition, it also elucidates advantages of bioremediation, isolation of selective microbial strains, and evaluation of the biodegradation rates.
文摘Leakage of oil and its derivatives into the soil can change the engineering behavior of soil as well as cause environmental disasters.Also,recovering the contaminated sites into their natural condition and making contaminated materials as both environmentally and geotechnically suitable construction materials need the employment of remediation techniques.Bioremediation,as an efficient,low cost and environmentalfriendly approach,was used in the case of highly plastic clayey soils.To better understand the change in geotechnical properties of highly plastic fine-grained soil due to crude oil contamination and bioremediation,Atterberg limits,compaction,unconfined compression,direct shear,and consolidation tests were conducted on natural,contaminated,and bioremediated soil samples to investigate the effects of contamination and remediation on fine-grained soil properties.Oil contamination reduced maximum dry density(MDD),optimum moisture content(OMC),unconfined compressive strength(UCS),shear strength,swelling pressure,and coefficient of consolidation of soil.In addition,contamination increased the compression and swelling indices and compressibility of soil.Bioremediation reduced soil contamination by about 50%.Moreover,in comparison with contaminated soil,bioremediation reduced the MDD,UCS,swelling index,free swelling and swelling pressure of soil,and also increased OMC,shear strength,cohesion,internal friction angle,failure strain,porosity,compression index,and settlement.Microstructural analyses showed that oil contamination does not alter the soil structure in terms of chemical compounds,elements,and constituent minerals.While it decreased the specific surface area of the soil,and the bioremediation significantly increased the mentioned parameters.Bioremediation resulted in the formation of quasi-fibrous textures and porous and agglomerated structures.As a result,oil contamination affected the mechanical properties of soil negatively,but bioremediation improved these properties.
基金This study was supported by the Zhejiang Public Welfare Technology Research Program of China(ZPWTP)(No.LGN18C190008)the Zhejiang Provincial Natural Science Foundation of China(No.LQ20C190003)the Ningbo Municipal Natural Science Foundation(Nos.2019A610421,2019A610443),and the K.C.Wong Magna Fund in Ningbo University.
文摘The relationships between nutrient dynamics,microbial community,and macrofauna are important in bioremediation systems.In this study,we examined the effects of marine clam Scapharca subcrenata sedimentary activities on the microbial assemblages,benthic nutrient chemistry,and its subsequent remediation impacts on organic effluent in the sediment of an aquaculture wastewater bioremediation system.The results showed that microbial community composition differed significantly in the clam area(ANOSIM,R=0.707,P=0.037).Pyrosequencing of bacterial 16S rRNA gene revealed a total of 48 unique phyla,79 classes,107 orders,197 families,and 321 genera amongst all samples.The most dominant bacterial assemblages were Proteobacteria,Bacteroidetes,Acidobacteria,Firmicutes,Verrucomicrobia,and Actinobacteria,with Bacteroidetes and Firmicutes significantly higher in all treatment samples than control(P<0.001).All dominant phyla in the list were shared across all samples and accounted for 89%(control)and 97%(treatment)of the total 16S rRNA.The nutrient flux rates from the sediments into the water(treatment group)were 51%(ammonium),88%(nitrate),77%(nitrite)and 45%(phosphate)higher,relative to the control implying increased mineralization,degradability,and mobility of the benthic nutrients.Similarly,significantly increased oxygen consumption rates were evident in the clam area signifying improved oxygen distribution within the sediment.The organic effluent contents associated with total-organic matter,carbon,nitrogen,and,phosphate were lower among the clam treatments relative to the control.Our results describe the potential roles and mechanisms contributed by marine bivalve S.subcrenata on benthic-bacterial-community assembly,nutrient balance,and effluent reduction in the sediments of aquaculture wastewaters bioremediation system.
基金Supported by the University Science and Technology Innovation Team Construction Projects of Heilongjiang Province(2013 TD003)
文摘Present study was conducted to clarify soil pH and temperature influence on different atrazine bioremediation techniques. For this purpose, sodium citrate, Arthrobactor sp. strain DNS10, sawdust and animal manure were selected to clarify their atrazine remediation efficiency under pH 5, 7 and 9 and temperatures 20, 30 and 40℃, respectively. Results showed that atrazine remediation was generally optimized at pH 7 and 30℃ for all the treatments except sodium citrate as soil treated with sawdust was not temperature dependant, but at pH 5 remediation process was determined slower. Atrazine remediation in soil with no additional amendment was only 34%, while in soil treated with sawdust, DNS10, sodium citrate and animal manure were 75.17%, 89%, 74.17% and 76.83% at optimized pH and temperature. Overall atazine removal rate was significantly(≥0.01) higher with increasing in temperature at all the selected pH.
基金Supported by Science and Technology Planning Project of Higher Education of Shandong Province(J16LD03)Natural Science Foundation of Shandong Province,China(ZR2010CL01)+1 种基金Doctoral Scientific Research Foundation of Binzhou University(2014Y17)SRTP Project of Binzhou University
文摘To study the control effect of algicidal bacteria on blue-green algal blooms in natural conditions,three algicidal bacterial strains were used to make a compound algal inhibiting agent,and the removal effects of the algal inhibiting agent on algae,nitrogen,phosphorus,organic matter,and chlorophyll a in Chendian pool and Qiangwei pool of Quancheng Park in Jinan City were analyzed. The results show that the algal inhibiting agent could eliminate the blue-green algal blooms. 54 days later,chlorophyll a content in the water bodies reduced to below 0. 06 mg/L,and both COD_(Cr)and BOD_5 decreased significantly. NH_4^+-N and TP content were lower than 2 and 0. 05 mg/L respectively. The removal rate of COD_(Cr)was slightly low( 33%-48%),and the removal rates of other indicators were higher than 60%. It is clearly seen that the algal inhibiting agent could quickly eliminate the algal blooms and had a notable effect on the recovery of the eutrophic water bodies.
文摘The objective of this study was designed to evaluate the effects of biostimulation and bioaugmentation amendment agents (NPK fertilizer, Tween 80 and mixed culture) on the bioremediation of tropical soil samples artificially contaminated with Weathered Bonny Light Crude Oil (WBLCO). Response Surface Methodology (RSM) with Box Behnken Design (BBD) was used with three levels and three factors of NPK fertilizer (2 - 6 g), Tween 80 (5 - 15 mg/l) and mixed culture (0.5 - 1.5 g/l) as independent variables and WBLCO removal as dependent variable (response) in a six weeks remediation period. The results showed that the rate of WBLCO removal generally increased with increase in the amount of NPK fertilizer, Tween 80 and mixed culture (biomass), respectively. A statistically significant (P < 0.0001) second-order quadratic regression model for WBLCO removal (using design-expert statistical program (v. 6.0.8)) with a coefficient of determination, R (=0.9996) was obtained. Numerical optimization technique based on desirability function was carried out to optimize the bioremediation process. The optimum values for biostimulation and bioaugmentation amendment agents to achieve a predicted maximum WBLCO removal of 84.88 percent were found to be: NPK fertilizer, 4.25 g;Tween 80, 10.22 mg/l and mixed culture, 0.46 g/l. At this optimum point, the observed WBLCO removal was found to be 83.79 percent. The statistical analyses and the closeness of the experimental results and model predictions show the reliability of the regression model and thus, biostimulation and bioaugmentation of indigenous microbial density and activity can reduce remediation period of petroleum hydrocarbon contaminated environment and subsequently the cost of remediation.
基金funded by The basic scientific research project fund of Chinese Academy of Geological Sciences (Code: YYWF201519)China Geology Survey Work Program (Code: 121201106000150006)+1 种基金The international cooperation project of Ministry of Science and Technology (Code: 2005DFA90200)Mine environment management project of Henan Provincial Department of Land and Resources
文摘The long-term oil exploitation in oil fields has led to pollution of surrounding soil, creating a serious ecological problem. In order to promote and improve the application of microbial remediation in oil contaminated soil, experiment is carried out in polluted area in Zhongyuan Oilfield. In the experiment, indigenous microorganisms and other physical and chemical methods are employed, ryegrass is grown, and environmental factors in soil are regulated to degrade the oil and treat the polluted soil. Results show that when the average oil content in the soil is about 523.08 mg/kg, 65 days' remediation through plants and microorganisms could help bring the oil content down to 74.61 mg/kg, achieving a degradation rate of 85.74%; through salinity treatment, salt content in soil is reduced by 62.93-82.03% to 399-823 mg/kg from previous 2.22 g/kg. Through this experiment, the bioremediation method is improved and its effectiveness and feasibility are testified. The result has been applied in Zhongyuan Oilfield and has brought fair ecological and economic benefits, providing technical support to the treatment of contaminated soil of the same kind, and offering some insights to the treatment of soil contaminated by other organic pollutants.
文摘Oil exploitation in many African countries is associated with litigation and conflicts to water and soil pollution. It is because of inadequate planning for management of oil spills and industrial effluents in environmentally sustainable manner. Uganda’s natural resources such as soils and water bodies are threatened by contamination due to rapid industrialization and rural-urban migration in established Industrial Business Parks and planned oil and gas production at Albertine Graben Region. The low level of compliance to industrial effluents discharge standards relevant to specific environmental receptors and activities within oil and gas sector development pose a big question of how to sustain the biodiversity and natural resource management. Experiences from elsewhere have shown bioremediation as a viable and proven option to provide potentially manageable solutions to resulting pollution as a substitute to modern well-known remediation methods, for it is relatively cheaper, more efficient and minimal toxic byproducts after treatment. The most used bioremediation agents in different studies reviewed are bacterial species especially Pseudomonas and Bacillus, followed by Aspergillus a fungi species, microalgae and aquatic plants such as duckweed, macrophytes and pteridophytes. Regardless of the waste produced in either oil and gas sector or industries, these agents have shown greater biodegradation rates. Pseudomonas sp. has a degradation efficiency of oil compounds ranging from 90% - 100%, and Aspergillus sp. 75% - 95%. Some aquatic plants can thrive in created wetlands with relatively still water such as Phragmites australis which can degrade hydrocarbons especially Aromatic compounds with benzene ring up to 95%. It can thrive in salty water with high pH range of 4.8 - 8.2. With industrial wastewater, algae is the most dominant with the degradation rates varying from 65% -100% and bacteria at 70% - 90%. Most of the reported results are in the developed country context. In developing countries, duckweed is reported as the commonest aquatic plant in wastewater treatment for removal of heavy metals because it is more tolerant to a wide range of environmental conditions and produce biomass faster. It has a removal rate of heavy metals between 90% and 100%. Basing on literature data analysis, bacteria are more suitable for treating water from oil pollution using Pseudomonas sp. Phragmites australis is suited for cleaning up oil in both water and soil. Duckweed is the best in treating water polluted with industrial effluents. This paper presents the different bioremediation methods that Uganda can potentially apply to mitigate the increased risk of environmental pollutions from planned industrialization and oil and gas development in the Albertine Graben Region.
文摘Heavy metal contamination of the biosphere has increased sharply over the last century. Anthropogenic activities such as industrialisation and demographic growth can be considered as the main causes of it. Soil contamination affects every organism and poses major environmental and human health problems worldwide. The issue has been addressed in the past and a few methodologies have been developed in order to effectively clean up the contaminated areas. However, many of these remedies are very aggressive and can damage the soil. This paper focuses on the use of gentler techniques, which take advantage of the properties of several plants and wildflowers that absorb heavy metals and polycyclic aromatic hydrocarbons, and their potential application in megacities such as Hong Kong.
文摘This study discusses factors affecting various processes involved in bioremediation coupled with electrokinetics. The study presents innovative solutions, and proposes new directions. Environmental conditions that have an influence on the characteristics, behavior, and metabolism of indigenous microorganisms are presented. The discussion focuses on overcoming the unfavorable conditions created by electrolysis reactions, prolongation the survival of the microbes at contaminated sites, increase of microbial enzyme secretion, improvement of the indigenous bacteria metabolic pathways, and exploration of metagenomics resources from soil biota. The challenge facing the implementation of conventional bioremediation techniques in precisely and effectively delivering nutrients to indigenous bacteria, particularly in soils with tortuous paths and low hydraulic conductivity is discussed. Current knowledge in application of enhanced biostimulation using electrokinetics is reviewed. The implementation of bioaugmentation in bioremediation coupled with electrokinetics to enhance the outcome of bioremediation is presented. Effects of phenomena associated with electrokinetics in the hybrid remediation approach are discussed.
文摘Palm oil mill effluent (POME) is liquid waste produced from palm oil extraction process. Discharging it to the river without treatment is violation according to Malaysia Environment of Quality Act (EQA) 1974. In Malaysia, ponding system is a conventional treatment method for POME due to its economical and simple process. The treatment process mainly involves two main treatment phases;anaerobic and aerobic degradation. Anaerobic degradation has a proven track record in reducing pollutant properties in POME up to 85%. The real challenge is to increase the efficiency of aerobic process as the biological oxygen demand (BOD) discharge limit has been further reduced from 100 mg·L<sup>-1</sup> to less than 20 mg·L<sup>-1</sup>. One of economical and feasible approach to increase the efficiency of aerobic phase is via bioremediation. This paper describes the limitation of aerobic degradation in ponding system, besides discussed on the important aspects that need to be optimized for a success implementation of bioremediation and its challenges.
文摘This review describes a new means of control and stimulation of microorganisms involved in the bioremediation of sediments and waterlogged soils. This emerging technology is derived from sedimentary microbial fuel cells, and consists in ensuring aerobic respiration of aerobic microbial populations in anaerobic conditions by means of a fixed potential anode in order to evacuate the electrons coming from the microbial respiratory chains. This review describes the conceptual basis of the electro-bioremediation, the material devices used (electrode set-ups and spacing), and finally studies the various devices published since the bench tests until the scarce in-field implementations.
文摘There is a worldwide distribution of heavy metal pollution that can be managed with a bioremediation approach using microorganisms. Several bacterial species belonging to the Proteobacteria have been shown to tolerate heavy metal stress, including toxic salts of noblemetals. Rhodobacter sphaeroides, a model bacterium has previously been utilized for bioremediation studies. A bioinformatics approach was employed here to identify the distribution of genes associated with heavy metal tolerance among the sequenced bacterial genomes currently available on the NCBI database. The distribution of these genes among different groups of bacteria and the Cluster of Orthologous Groups (COGs) were further characterized. A total of 170,000 heavy metal related genes were identified across all bacterial species, with a majority of the genes found in Proteobacteria (46%) and Terrabacteria (39%). Analysis of COGs revealed that the majority of heavy metal related genes belong to metabolism (COG 3), including ionic transport, amino acid biosynthesis, and energy production.
