Microbial solutions for the cleanup of contaminated land
Bioremediation has been used to clean up contaminants for several decades (Philip et al. 2005) and microbial action is often a part of this process. In this review, the methods of microbial remediation for major contaminants shall be discussed before a consideration of methodology. Microorganisms have learnt to use organic substances as food sources through millions of years of evolution. Non-organic or anthropogenic compounds tend to be more recalcitrant.
Organic Contaminants
Petroleum products can be divided into Aliphatic and Carbocyclic hydrocarbons or 5 groups: normal paraffins; iso-paraffins; aromatics, NSO (nitrogen, sulphur, oxygen compounds (NSO) and Napthenes (Farrell-Jones 2003). Saturated hydrocarbons are generally easier to biodegrade than Aromatic compounds, while resins and Asphaltenes tend to be resistant (Venosa & Zhu 2003). Rates of degradation improve with increasing contact surface area between oil and water. Ideal conditions for microbial oil breakdown are aerobic, >15ºC (except psychrophilic microbes e.g. Delille et al. 2004), high Nitrogen (N)/Phosphorous (P) levels and slightly alkaline pH (Venosa & Zhu 2003). There are at least 70 genera of known oil degrading microorganisms (Joo et al. 2008). Environments with recent or chronic oil pollution will have a much high % of oil degraders (Venosa & Zhu 2003).
Bewlay et al. (2001) reported a land farming case study to bioremediate a former oil storage area. The land farming method involved ploughing a yeast food powder into the site to encourage microbial degradation. After several weeks the Total Petroleum Hydrocarbon (TPH) on site had reduced from 2300 mg/kg to 706 mg/kg and the leachable TPH was reduced to <1mg/L. The 2nd case study involved ex–situ soil treatment in artificial nutrient rich wetland beds. 11500m³ of soils was regularly turned within the beds, TPH levels fell to 60%≥ the initial concentration. Remediation also involved cleaning groundwater using hydrogen peroxide, nutrients and fertilisers, the resulting aerobic conditions caused TPH levels to reduce by c. 99%. A similar approach was taken by Kuyukina et al. (2003), soil was initially loaded into a bioslurry reactor before land farming. The reactor reduced total recoverable petroleum hydrocarbons (TRPH) from 200g/kg to 25g/kg and land farming reduced the concentration to 1g/kg. Biopiling is used to degrade a variety of contaminants including oil, Rojas-Avelizapa et al. (2006) used biopiles, straw and fertilisers to reduce TPH by 4-5 orders of magnitude. Mills et al. (2004) evaluated 3 methods of biostimulation in a wetland environment and concluded that inorganic nutrients caused the highest rates of oil degradation. Biosurfactants can be used to increase oil degradation but have been dismissed in the past as expensive or counterproductive (Benincasa 2007). Both Benincasa (2007) and Cameotra & Singh (2008) used the organism Pseudomonas aeruginosa which produces a biosurfactant. In both lab based studies, the biosurfactant producing microorganism increased the rate of degradation and did not interfere with existing oil degraders. Miguel et al. (2009) found that synthetic Polycaprolacton biosurfactants aided oil degradation. However Fernandez et al. (2007) found negligible increased degradation with the addition of biodiesel to oil contaminated shorelines. Rosa & Triguis (2007) found that fertiliser added to a small oil contaminated tropical field plot reduced the % of saturated hydrocarbons. Other work focused on different types of microorganisms, Amoeba population size in a marsh community increased after oil was added (Anderson et al. 2001). Lab experiments in Egypt suggested micro-fungi A. Flavus degraded diesel oil by c. 20% more than other microorganisms (El Morsay 2005). Many authors experiment with agricultural or industrial waste as an alternative to fertilisers. Abioye et al. (2009) trialled banana skins, spent brewery grain and spent mushroom compost to enhance biodegradation of engine oil. Spent brewery grain caused the highest reduction in TPH. Joo et al. (2008) found that food waste substrate and the microorganism Candida catenulata doubled the amount of oil degradation. Nikolopoulou & Kalogerakis (2008) used a mixture of lipophilic organic fertilisers, biosurfactants and molasses in a laboratory to demonstrate increased rates of degradation. The initial lag phase was considerably reduced. Cunningham et al. (2004) froze soil with PVA and indigenous microbial additions, the PVA protected the microorganism and the freezing caused fracturing within the soil matrix. There was however concerns about long term durability within biopiles.
Tars & other heavy hydrocarbons can be degraded by aerobic and methanogenic bacteria (Bakersmans et al. 2002). Laboratory experiments tend to represent optimum conditions; often the same methods take c. 3 times longer in field conditions (Diplock et al. 2009). Commercial microorganisms are available but Mohammed et al. (2007) found that in a tropical environment autochthonous microbes had a similar rate of oil degradation to local microorganisms. Philip & Atlas (2005) claim engineers often feel compelled to buy commercial food sources or allochthonous microorganisms. Bioaugmentation should be limited solely to recalcitrant compounds.
Other Aliphatic Hydrocarbons
Flanagan (1998) used a laboratory based carbon fluid bioreactor to degrade 80-90% of Dichloromethane (DCM). However Dyer et al (2003) found that that during the initial Pump & Treat (P&T) of 1,2-dichloroethane (1,2-DCA) microorganisms hindered the process by biofouling and blocking the recharge wells. Krausova (2006) found that methylotrophic bacteria from a US harbour could degrade DCM. While they established cometabolism was important they did not make any detailed cleaning recommendations. Several chlorinated aliphatic hydrocarbons (CAH) were degraded using allochthonous microorganisms bioaugmented with butane in both laboratory and field.
Carbocyclic Hydrocarbons
Dioxins are very toxic to humans and bioaccumulate but can be used a food source by many microbes (Philip et al 2005). Narihiro et al. 2009 used the biostimulated microorganism; Dehalococcoides, within a composting reactor to degrade polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs). Wood chips and a dog food substrate caused a 3-fold decrease in dioxins compared to laboratory microcosms. Kelly et al 2001 used a mixture of phytoremediation and bioaugmentation of an Actinomycete. They found that tetrahydrofuran (THF) and butanol increased rates of 1,4 Dioxane degradation.
PAH
Polycyclic Aromatic Hydrocarbons (PAH) are widespread in the environment and regarded as potential carcinogens (Philip et al. 2005). Higher molecular weight PAH are harder for microorganisms to degrade (Juhasz & Naidu 2000). Benzo[a]pyrene has a relatively high molecular weight and numerous bacteria, fungi and algae appear able to metabolise Benzo[a]pyrene (Juhasz & Naidu 2000). Many of these microorganisms produce polar metabolites which may have a higher toxicity (Juhasz & Naidu 2000). Cometabolism (bacteria and fungi) and biosurfactants may prevent toxic metabolites (Juhasz & Naidu 2000). Wenderoth et al. (2003) found that Pseudomonas putida helped degrade Chlorobenzene, they even found evidence that the microorganism persisted after Chlorobenzene had been fully degraded. However, Bott & Kaplan (2002) found that P. putida and a genetically modified P. putida did not persist in a streambed environment and that Alcaligenes sp. BR60 was more effective in 3-chlorobenzoate degradation. Somtrakoon et al. (2008) found that the biostimulation of indigenous microbes and the allochthonous Burkholderia sp. VUN10013 helped increase the rate of Anthracene degradation in field samples. Zhao et al. (2009) used a halophilic bacterial consortium to degrade phenanthrene.
Arthrobacter Chlorophenolicus A6 was used by Backman & Jansson (2003) to degrade 4-Chlorophenol. Holden et al. (2001) noted that the addition of water is required for biodegradation within an arid environment. Ramirez et al. (2008) also found that a higher water amount encouraged degradation. Gemende et al. (2006) like Diplock et al. (2009) found that field tests showed much lower % of degradation compared to microcosms, especially for high molecular weight PAH. Toxic intermediates may reduce long term degradation.
Landfarming can be used to degrade PAH; Seech (2006) used a commercially controlled landfarming method called DARAMEND. DARAMEND treatment used fertilisers and controlled gas/aqueous conditions to reduce total PAH concentrations from 659mg/kg to 106mg/kg. Thomas et al. 2006 reported a site where a slurry phase bioreactor reduced lower density lighter PAH by 95% and benzo(a)pyrene by 68%. The project was funded by a research grant but proved the process was commercially viable and could be run remotely for 24hr, see figure 1. Narasimhan et al. (2003) showed that plants exuding Phenylpropanoids, favour microbes that degrade polychlorinated biphenyls (PCB). By adding plants or Phenylpropanoids directly the authors suggest Rhizoengineering could be used in PCB remediation. Ang et al. (2005) suggest that genetically engineered microorganisms (GEM) might finally be able to
Figure 1. Slurry reactor used to treat PAH (Thomas et al. 2006).
remediate recalcitrant persistent organic pollutants (POP) such as PAH, PCB and Organophosphates (agrochemicals). However there is a risk that GEMs may swap genetic material such as recombinant plasmids with other indigenous microorganisms (Ang et al. 2005).
Chlorinated ethanes and ethenes are common industrial contaminants, examples include
Tetrachloroethene (PCE), trichloroethene (TCE) and 1,1,1-trichloroethane(TCA) (Gossett 2002). Gosset (2002) states; there is ongoing work to identify existing microorganisms and their enzymes which can degrade PCE, TCE and TCA. In the future microbial communities may be analysed quickly using a probe to find specific degradation biomarkers rather than having to test every single community or microorganism (Gosset 2002). Friis et al. (2006) used a lactate substrate and Electrical Resistance Heating (ERH) to remediate TCE. After ERH some of the TCE was degraded to cDCE, bioaugmentation with KB-1™ and nutrients converted cDCE to Ethene
Gan et al. 2009 summarised methods of PAH degradation. They state that bioremediation tends to be long, may form toxic byproducts and can be of a low efficiency. They accept it may be a cost effective method and that electroremediation requires further large scale field studies.
Biocides
Biocides include a mixture of organic and non-organic constituents, this include pesticides, biocides, insecticides and fungicides. It has been estimated that <5% of pesticides reach the target organisms (Pimental & Levitan 1986). Microbes use hydrolysis, conjugation, oxidases, perioxidases, nitroaromatic compounds and reductive halogenation to degrade biocides (Van Eerd et al. 2003). Sette et al. (2004) found Streptomyces sp. LS166, LS177, and LS182 was able to degrade 60-70% of herbicide Alachlor (C14H20ClNO2) within the laboratory. Chirnside et al. 2009 extracted a microbial community from soil and found it was able to degrade Alachlor and Atrazine (C8H14ClN5) with the addition of nutrients. Kadian et al. 2008 found that biostimulation of indigenous microorganisms with biogas slurry appeared to double the amount of Atrazine compared to the control. Sette et al. 2004 found that 3 strains of streptomycetes degraded 60-75% of Alachlor in the laboratory. He et al. 2004 identified a penicillium sp. Fungi bioaugmented with compost was capable degrading 50% of herbicide metsulfuron-methyl (MSM) in 6 days. Li-Feng et al. (2007) showed the laboratory biostimulation (glucose) of an autochthonous Pseudomonas sp. bacterium from a contaminated site could cause high rates of MSM degradation. The pesticide Chlorpyrifos can also be degraded by bacteria, c. 84% was removed in laboratory based tests (Laksmi et al. 2009). Mohan et al. (2007) optimized Chlorpyrifos degradation within a bioreactor using the Taguchi Design of Experimental methodology (DOE). They identified the optimum pH, DO, %OM, temp ºC, substrate, soil water ratio and microorganism which increased bioreactor degradation by nearly 40%. By reducing the % of DO and inoculum added they further reduced the cost. Other authors have experimented with microbial mats, Grötzschel et al. (2004) found that a non indigenous microbial mat could be used to degrade 2,4-Dichlorophenoxyacetic Acid (2,4-D) in a hypersaline laboratory experiment. Some insecticides such as Lindane (HCH) appear to degrade in aerobic conditions but few field experiments exist (Philips et al. 2005). Benimeli et al. (2008) found that lab maize plants inoculated with Streptomyces sp. M7 were more vigorous. After 14 days 68% of Lindane was removed compared to negligible amounts in the indigenous control sample.
Anaerobic microorganisms are capable of degrading organochlorine insecticides such as Eldrin and Diedldrin but failed when used in the field (Matsumoto et al. 2009). Hussain et al. (2007) used 3 bacterial strains to degrade Endosulfan but the only possible field method appears to be via bioreactor (Kumar & Philip 2006). Getenga et al. (2004a) attempted to evaluate composting to degrade metribuzin (C8H14N4OS) and 2,4-D (2,4-Dichlorophenoxyacetic acid), they found that only 2,4 D was receptive to biostimulation. Pentachlorophenol (PCP) has been used as a biocide for agriculture and as a preservative (Miller et al. 2004). Miller et al. (2004) found that a water content 50-70% of soil field capacity and aerobic conditions produce optimum PCP degradation within biopiles. Walter et al. (2004) found that the white fungi T. versicolor bioaugmented with straw, starch and sawdust was capable of degrading low levels of PCP. In 2005 Walter et al. published a 2.5 year biopile field study where PCP levels had reduced from 800 to <50mg/kg after 74 weeks. The authors also claimed the soil cells required little maintenance or irrigation. Zuzana et al. (2009) concluded lignite and a humic acid complex may sorb PCP but they had difficulties with secondary metabolites.
A more problematic biocide has been DDT (dichlorodiphenyltrichloroethane). DDT can be converted to DDE or DDD altering the conditions from anaerobic to aerobic (Philip et al. 2005, p.41). Several authors have noted that fungi can tolerate low-medium levels of DDT and certain types can degrade DDT (Megharaj 2000, Huang et al. 2007). Huang et al. (2007) found that during laboratory experiments ectomycorrhizal fungi converted 45-55% of DDT to DDD and the rest was bioaccumulated within the Mycelia. Kantachote et al. (2004) found that seaweed helped break down DDT (80% reduction in 6 weeks) into less persistent DBP. However, generally microbial degradation of DDT is limited, since other treatments exist.
Biocides can also inhibit degradation of other products. Galiluin et al. (2007) found that Calcium carbonate, Sodium nitrate and Zeolite bioaugmented the break-down of cellulose despite the presence of fungicide copper sulphate.
Nitroaromatics
Nitroaromatic contaminants are mainly from industrial processes and military sources (Philip et al. 2005). Nitroaromatic degradability is usually greatest under reducing conditions (Philip et al. 2005). Boopathy & Manning (1998) used a laboratory bioreactor mixed with molasses and bacteria to reduce Tetryl (2,4,6-trinitrophenylmethylnitramine) levels to 0.1mg/kg within 3 months. During the process several metabolites were produced but these eventually degraded. Brenner et al. (2000) used a series of aerobic and anaerobic reactors to biodegrade NOx (nitrite and nitrate) and RDX (hexahydro-l,3,5-trinitro-1,3,5 triazine). Pre-treatment involved denitrification of NOx and any other organic material, the subsequent nitrogen deficient system was then ideal for aerobic RDX bacterial degradation. Bacteria YH1 used RDX as its sole nitrogen source. Clark and Boopathy (2007) concluded that a bioreactor with molasses substrate was more effective at removing TNT (2,4,6-trinitrotoluene) than landfarming but only by 99% and 82% respectively. They only degraded c. 80% of RDX and HMX (Octogen) possibly they should have used the denitrification treatment as used by Brenner et al (2000). The degradation of nitroaromatic CL-20 (C6H6N12O12) was limited by N content, lab based tests showed that Succinate and Pyruvate substrates aided CL 20 bacterial degradation through cometabolism (panikov et al. 2007). Rosser et al. (2001) decided to use PETN (Pentaerythritol Tetranitrate) reductase (identified from bacteria Enterobacter cloacae PB2) to degrade nitroaromatic compounds. The enzyme gene was then added to tobacco plants to produce denitrating transgenic plants.
In 2001 over 600 active wetland cells within the US (Rodgers & Bunce 2001), all rely on a % of microbial degradation. Rodgers & Bunce (2001) estimated that windrow composting was the cheapest bioremediation method.
Metals
Microbes cannot destroy metals but may be able to alter the redox state. Several metals have useful biological functions, while some are solely toxic (Philip et al. 2005). Certain microorganisms e.g. ATh-14 (Unramnia 2005) can sorb several heavy metals in extreme conditions. Arsenic can originate from slag, coal, mine tailings, pigment production and wood treatment or older pesticides (Oremland & Stolz 2003). Dissimilatory arsenate-reducing prokaryotes (DARPs) can process As (V) to As (III) whereas arsenic-metabolizing prokaryotes reverse the process (Oremland & Stolz 2003). Figure 2 shows how toxic As (III) can cycle into drinking water wells, a major problem in Bangladesh. As (V) in conjunction with a strong adsorbent can be microbially sorbed into the solid phase (Oremland & Stolz 2003). Huq et al. (2007) suggested algal growth reduces arsenic concentrations in rice. Wang & Mulligan (2006) suggests phytoremediation is a more practical bioremediation technique since the plants can be processed more easily. Biosparging or altering the pH may enhance Arsenic oxidation, alternatively Arsenic oxidation could be used as a Natural Attenuation technique (Wang & Mulligan 2006)
Figure 2. The As(V) becomes adsorbed and DARPs respire forcing As(III) into the aqueous phase (from Oremland & Stolz 2003).
Chromium is used in various industrial processes and has a wide range of valency states each with different properties and toxicities (Cheung & Gu 2006). Several techniques rely on biodegradation and reduction-precipitation but these can be expensive (Beleza et al. 2001). Several strains of Pseudomonas and bacteria derived reductases have been shown to degrade Cr6+ (Cheung & Gu 2006). Using manufactured enzymes that derive from microorganisms can be expensive (Cheung & Gu 2006). Biofilms may become ineffective with thickness and various enzymes might not tolerate field conditions (Cheung & Gu 2006).
Cadmium has a relatively high vapour pressure and is present in the atmosphere (Kurek & Bollag 2004). If Cd is within the aqueous phase it can be absorbed by plants into the food chain, Kurek & Bollag (2004) suggested microorganisms can immobilise Cd within the soil. Importantly dead microorganisms were still able to sorb Cd into the biomass. Jézéquel & Lebeau (2008) also had some limited results that showed concentration, phytoavailable and immobilised Cd varied depending on the microorganism type rather than solely the parameters used. Juwarkar et al. (2007) found that a biosurfactant produced by Pseudomonas aeruginosa strain BS2 was capable of leaching cadmium and lead. Mulligan and Wang (2006) also found that the same biosurfactant enhanced leaching in the laboratory. Generally bioremediation is not used for cadmium remediation.
Mercury (Hg) is very toxic to the nervous system and is lipophilic (Philip et al. 2005). Pseudomonas putida and other bacterial strains were used to degrade mercury in Chloralkali wastewater (Wagner-Döbler et al 2000). Wastewater was fed into a bioreactor where it was buffered, mixed with yeast extract and sucrose before passing though a carbon filter. Barkay et al. (20030 stated that in-situ remediation is difficult and only groundwater bioreactors are in use. Ruiz et al (2003) inserted an indigenous bacterial DNA sequence that made the transgenic tobacco plant chloroplasts tolerant to higher levels of Hg. This indirect microbial degradation allowed plants to absorb more mercury, potentially aiding phytoremediation, legal concerns withstanding. See appendix 1 for further examples of symbiotic plant-microbe relationships.
Selenium is toxic in high doses but humans require 30-85 ìg per day (Thomson in 2004 cited in Lenz & Lens 2009). Selenium can exist in several forms; Selenate & Selenite can bioaccumulate (Lenz & Lens 2009). Selenium is used within the glass, electrical and metal processing (Lenz & Lens 2009). However no permanent solution has been found for Selenium contamination in US agricultural areas. See appendix 2 for a summary of Selenium treatment options.
Radionuclides are formed naturally via cosmic rays, geology and humans. They can be difficult to degrade and many have long half lives. Uranium comes in 3 forms: natural, enriched and depleted (Gavrilescu et al. 2008). Anthropogenic sources include mining (including non-uranium mines), enrichment for power stations and coal waste. There are several mechanical methods of treatment such as soil washing or bioreactors. Microorganisms can participate in redox, adsorption, methylation, bioleaching, phytoextraction and phytostablistabilisation reactions (Gavrilescu et al 2008). Goho (2004) reported on a method using microorganisms to aid electrokinetic remediation. In the laboratory autochthonous microorganisms added electrons to the Uranium reducing its lability or increasing its sorption to sediment. In a field test they injected Acetate to encourage Uranium immobilisation via microorganisms. They surmised that in-situ electrokinetic remediation could be more cost effective than existing methods. Kalin et al. (2004) reviewed a 3 algal cell method to remediate uranium. Cell walls of algae absorb the U (VI) from wastewater; the cell material then collects in sediments where it is reduced into the stable precipitate U (IV) in anaerobic conditions. The cells are fed nutrients to ensure continuous algal growth, algal are used due to their ubiquitous nature rather than their superior U biosorption/sequestration. They envisage that an industrial process would then involve passing the precipitate through a low pH (<2.0) environment.
Detergents
The Alkylbenzyl (ABS compounds) are widely used as detergents. The detergent industry switched to linear ABSs as the non linear form was resistance to biodegradation. Johnson et al. (2001) used mesocosm experiments to show that anaerobic degradation was sufficiently high to allow monitored natural attenuation (MNA). Johnson et al. (2007) further stated that LAB degradation was possible under aerobic and nitrate reducing conditions. They calculated that the ratio of different C12 LAB isomers could be used to infer the amount of biodegradation within a contaminated site. Duarte et al. (2010) used a bioreactor to get 35-68% linear alkylbenzene sulfonate (LAS) removal and was enhanced by a meat-carbohydrate-sodium bicarbonate mixture.
Microorganisms can also be used to improve the clarity of water. Pandey et al. (2007) suggest that specialised substrates and a suitable microbial consortium may be used to degrade Azo dyes within wastewater.
METHODS
Remediation methods can be divided into in-situ and ex-situ methods. The figure from Khan et al. (2009) in appendix 3 illustrates microbial degradation. There are several limitations with laboratory based studies. Sampling of agricultural land can be problematic. Zhang et al. (2006) found that char formed from incomplete burning of crops can influence measured pesticide concentrations. The biochar absorbed organic compounds and the pesticides. Vieublé-Gonod et al. (2009) found that “interfurrows” with ploughed soil had higher levels of biomass and a higher % of pesticide mineralisation. The spatial differences in pesticide concentration persisted for several months. Several authors noted that lab experiments are usually less successful in a field setting e.g. Diplock et al. (2009). Getenga (2004b) suggested that non-sterile experiments are rarely sterile throughout the duration of the experiment due to the ubiquitous nature of microorganisms. Chiellini et al. (2007) found that different substrates partition and these different phases are not always considered in laboratory based studies. Microbes can also create toxic secondary byproducts via activation or when they degrade toxic substances. Microorganisms can also help catalyse metal-sulphide degradation which severely affects mining effluents (Laine & Jarvis 2003). It is rare for any treatment to be 100% effective and the long term stability, sorption or secondary products may be difficult to predict. It is difficult to model every single microbial action but appendix 4 from Sturman et al. (1995) lists the micro, meso and macro microbial variance.
Microbial degradation is a part of almost every land remediation technique. Treatment trains of several processes can be used, such as: flotation, membrane osmosis, filtration, steam stripping, slurry walls, liners, geotextiles, and organophilic clay. Other methods such as ground fracturing (water, steam, air, blast) increase the contaminant or microbe exposure. Bioreactors, Windrows, Biopiles, Biofilms, Biomats, Rhizoremediation and MNA rely on microbial action. Rainwater et al. (1993) found that simply varying the height of the water table compared to stagnant water increased degradation. This process is enhanced by using flushing or Pump & Treat. Electroremediation partially relies on microbial degradation, such as in Goho (2004). Stabilisation and Solidification usually excludes microbes but Adams (2004) managed all 3 using lime and cacao husks. Other authors have used “carriers” (Cunningham et al. 2004). Wetland cells have often been used for bioremediation particularly for wastewater and mine tailings. Wetland cells use phytoremediation, microbial degradation and chemical conversion to clean wastewater. Imfeld et al. (2009) found over 18000 reports which studied natural or constructed wetlands, see appendix 5 for a table of degradation pathways for a number of selected contaminants.
Genetically Engineered Microorganisms (GEM) come with legal and ethical concerns (Ang 2005, Tamis et al. 2009). Pepper et al. (2002) found that a 2,4-D plasmid transferred to an indigenous microbial population from a GEM variety. GEM Biosensors have been created for a wide range of metal and oil derived contaminants and future use may include long term in situ monitoring (Stenuit et al. 2008). See appendix 6 for a diagram of how a biosensor is used. Another approach is the use of chemical markers of degradation, such as secondary metabolites. The % of degradation products can be used to predict the extent or rate of degradation (Young et al. 2005). In the future microbial communities may be analysed quickly using a probe to find specific degradation biomarkers rather than having to test every single community or microorganism (Gosset 2002).
It was predicted that by 2009 7% of the UK remediation market would be bioremediation techniques (Hough 2005). There are many microbial solutions and they are complimentary to existing mechanical, physical or chemical techniques.
Word Count: 10 sides of A4 excluding, bibliography figures and appendices.
Appendix 1. Examples of symbiotic relationships, from Khan et al. (2009)
Appendix 2. Selenium treatment options, from Lenz & Lens (2009)
Appendix 3. Microbial degradation, from Khan et al. (2009)
Appendix 4. Factors affecting bioremediation, from Sturman et al. (1995)
Appendix 5. Degradation pathways in wetland cells, from Infeld et al. (2009)
Appendix 6. How Biosensors can be used. (From H.J. Purohit 2003)
Bibliography
Abioye, P. O., Aziz, A. A and Agamuthu, P. (2009) Enhanced Biodegradation of Used Engine Oil in Soil Amended with Organic Wastes. Water, Air & Soil Pollution [online], DOI 10.1007. Available from http://www.springerlink.com/content/u6h4873607v26k02/?p=0daaf087ff0848619e78e1aed9ff0d5f&pi=0 (accessed 10 January 2010)
Adams, R. H. (2004) Chemical–biological stabilisation of hydrocarbon-contaminated soil and drilling cuttings in tropical Mexico. Land Contamination & Reclamation, 12(4), pp.349-361
Anderson, O. R., Gorrell, T., Bergen, A., Kruzansky, M and Levandowsky, M. (2001) Naked Amoebas and Bacteria in an Oil-Impacted Salt Marsh Community. Microbial Ecology, 42(3), pp. 474-481
Ang, E. L., Zhao, H and Obbard, J. P. (2005) Recent advances in the bioremediation of persistent organic pollutants via biomolecular engineering. Enzyme and Microbial Technology, 37, pp. 487-496
Backman, A and Jansson, J. K. (2004) Degradation of 4-Chlorophenol at Low Temperature and during Extreme Temperature Fluctuations by Arthrobacter chlorophenolicus A6. Microbial Ecology, 48(2), pp. 246-253
Bakermans, C., Hohnstock-Ashe, A. M., Padmanabhan, S., Padmanabhan,P and Madsen, E. L. (2002) Geochemical and Physiological Evidence for Mixed Aerobic and Anaerobic Field Biodegradation of Coal Tar Waste by Subsurface Microbial Communities. Microbial Ecology, 44(2), pp. 107-117
Barkay, T., Miller, S. M and Summers, A. O. (2003) Bacterial mercury resistance from atoms to ecosystems. FEMS Microbiology Reviews 27, pp. 355-384
Beleza, V. M., Boaventura, R. A. R and Almeida, M. F. (2001) Kinetics of chromium removal from spent tanning liquors using acetylene production sludge. Environmental Science and Technology 35, pp. 4379–4383.
Benimeli, C. S., Fuentes, M. S., Abate, C. M. and Amoroso, M. J. (2008) Bioremediation of lindane-contaminated soil by Streptomyces sp. M7 and its effects on Zea mays growth. International Biodeterioration & Biodegradation, 61, pp. 233–239
Benincasa, M. (2007) Rhamnolipid Produced from Agroindustrial Wastes Enhances Hydrocarbon Biodegradation in Contaminated Soil. Current Microbiology, 54, pp. 445-449
Bewley, R. J. F and Webb, G. (2001) In situ bioremediation of groundwater contaminated with phenols, BTEX and PAHs using nitrate as electron acceptor. Land Contamination & Remediation 9(4), pp. 335-347
Boopathy, R. and Manning, J. (1998) Biodegradation of Tetryl (2,4,6-Trinitrophenylmethylnitramine) in a Soil-Slurry Reactor. Water Environment Research, 70(5), pp. 1049-1055
Bott, T. L and Kaplan, L. A. (2002) Autecological Properties of 3-Chlorobenzoate-Degrading Bacteria and Their Population Dynamics When Introduced into Sediments. Microbial Ecology, 43(2), pp. 199-216
Brenner, A., Ronen, Z., Harel, Y and Abeliovich, A. (2000) Use of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine as a Nitrogen Source in Biological Treatment of Munitions Wastes. Water Environment Research, 72(4), pp. 469-
Cameotra, S. S. and Singh, P. (2008) Bioremediation of oil sludge using crude biosurfactants. International Biodeterioration & Degradation, 62, pp. 274-280
Cheung, K. H. and Gu, J-D. (2007) Mechanism of hexavalent chromium detoxification by microorganisms and bioremediation application potential: A review. International Biodeterioration & Biodegradation, 59, pp. 8–15
Chiellini, E., Corti, A., D’Antone, S and Billingham, N. C. (2007) Microbial biomass yield and turnover in soil biodegradation tests: carbon substrate effects. Journal of Polymers and the Environment, 15, pp. 169-178
Chirnside, A. E. M., Ritter, W. F and Radosevich, M. (2009) Biodegradation of aged residues of atrazine and alachlor in a mix-load site soil. Soil Biology & Biochemistry, 41, pp. 2484-2492
Clark, B. and Boopathy, R. (2007) Evaluation of bioremediation methods for the treatment of soil contaminated with explosives in Louisiana Army Ammunition Plant, Minden, Louisiana. Journal of Hazardous Materials, 143, pp. 643-648
Davis, G. B., Patterson, B. M. and Johnston, C. D. (2009) Aerobic bioremediation of 1,2 dichloroethane and vinyl chloride at field scale. Journal of Contaminant Hydrology, 107, pp. 91-100
Delille, D., Coulon, F. and Pelletier, E. (2003) Biostimulation of Natural Microbial Assemblages in Oil-Amended Vegetated and Desert Sub-Antarctic Soils. Microbial Ecology, 47(4), pp. 407-415
Devlin, J. F., Katic, D. and Barker, J. F. (2004) In situ sequenced bioremediation of mixed contaminants in groundwater. Journal of Contaminant Hydrology, 69, pp. 233-261
Diplock, E. E., Mardlin, D. P., Killham, K. S. and Paton, G. I. (2009) Predicting bioremediation of hydrocarbons: Laboratory to field scale. Environmental Pollution, 157, pp. 1831-1840
Duarte, I. C. S., Oliveira, L. L., Saavedra, N, K., Fantinatti-Garboggini, F., Menezes, C. B. A.,
Oliveira, V. M. and Varesche, M. B. A. (2010) Treatment of linear alkylbenzene sulfonate in a horizontal anaerobic immobilized biomass reactor. Bioresource Technology, 101, 606-612
Dyer, M., van Heiningen, E. and Gerritse, J (2003) A field trial for in-situ bioremediation of 1,2-DCA. Engineering Geology, 70(3-4), pp. 315-320
Edwards, R., Lepp, N. W., Cook, J. D., Routledge, P. and Routledge, R. (2001) A case study of the bioremediation of a former industrial site: the Lanstar Tar Distillery. Land Contamination & Reclamation, 9(3), pp.269-277
El-Morsy, E-S. M. (2005) Evaluation of microfungi for thebioremediation of diesel oil in Egypt. Land Contamination & Reclamation, 13(2), pp.147-159
Fernández-Álvarez, P., Vila, J., Garrido, J. M., Grifoll, M., Feijoo, G. and Lema, J. M. (2007) Evaluation of biodiesel as bioremediation agent for the treatment of the shore affected by the heavy oil spill of the Prestige. Journal of Hazardous Materials 147, pp. 914-922
Flanagan, W. P. (1998) Biodegradation of Dichloromethane in a Granular Activated Carbon Fluidized-Bed Reactor. Water Environment Research, 70(1), pp. 60-66
Friis, A. K., Heron, G., Albrechtsen, H. J-., Udell K. S. and Bjerg, P. L. (2006) Anaerobic dechlorination and redox activities after full-scale Electrical Resistance Heating (ERH) of a TCE-contaminated aquifer. Jouurnal of Contaminant Hydrology 88, pp. 219-23
Galiulin, R. V., Bashkin, V. N. and Galiulina, R. A. (2007) Cellulase activity of soil polluted with fungicide copper sulphate after the application of various ameliorants. Land Contamination & Reclamation, 15(3), pp. 353-358
Gan, S., Lau, E. V. and Ng, H. K. (2009) Remediation of soils contaminated with polycyclic aromatic hydrocarbons (PAHs). Journal of Hazardous Materials, 172, pp. 532-549
Gavrilescu, M., Pavel, L. V. and Cretescu, I. (2008) Characterization and remediation of soils contaminated with uranium. Journal of Hazardous Materials, 163, pp. 475-510
Gemende, B., Gerbeth, A., Müller, G., Höse, C., Seidel, J., Lange, R. and Müller, R. H. (2006) Comparison of pilot-scale bioremediation of PAH contaminated construction rubble with laboratory tests. Land Contamination & Reclamation 14(2), pp. 252-257
Getenga, Z. M., Madadi, V. and Wandiga, S. O. (2004a) Studies on Biodegradation of 2,4-D and Metribuzin in Soil under Controlled Conditions. Bulletin of Environmental Contamination and Toxicology, 72, pp. 504-513
Getenga, Z. M., Dorfler, U., Reiner, S. and Sabine, K. (2004). Determination of a Suitable Sterilization Method for Soil in Isoproturon Biodegradation Studies. . Bulletin of Environmental Contamination and Toxicology, 72, pp. 415-421
Goho, A. (2004) Electrifying Toxic Cleanup. Science News, 166(10), pp. 147-148
Gossett, J. M. (2002) Fishing for Microbes Science, New Series, 298(5595), pp. 974-975
He, Y. H., Shen, D. S., Fang, C. R. and Zhu, Y. M. (2006) Rapid biodegradation of metsulfuron-methyl by a soil fungus in pure cultures and soil. World Journal of Microbiology and Biotechnology, 22, pp. 1095-1104
Holden, P. A., Hersman, L. E. Firestone, M. K. (2001) Water Content Mediated Microaerophilic Toluene Biodegradation in Arid Vadose Zone Materials. Microbial Ecology, 42(3), pp.256-266
Hough, R. eds. (2005) Clean-up & regeneration bulletin, 13(2), p. 194
Huang, Y., Zhao, X. and Luan, S. (2007) Uptake and biodegradation of DDT by 4 ectomycorrhizal fungi. Science of the Total Environment, 385(1-3), pp. 235-241
Huq, S. M. I., Abdullah, M. B. and Joardar, J. C. (2007) Bioremediation of arsenic toxicity by algae in rice culture. Land Contamination & Reclamation, 15(3), 327-334
Jézéquel, K. and Lebeau, T. (2008) Soil bioaugmentation by free and immobilized bacteria to reduce potentially phytoavailable cadmium. Bioresource Technology, 99, pp. 690-698
Joo, H-S., Ndegwa, P. M., Shoda, M. and Phae, C-G. (2008) Bioremediation of oil-contaminated soil using Candida catenulata and food waste. Environmental Pollution, 156, pp. 891-896
Johnson, S. J., Barry, D. A., Christofi, N. and Patel, D. (2001) Potential for anaerobic biodegradation of linear alkylbenzene cable oils: literature review and preliminary investigation. Land Contamination & Reclamation, 9(3), pp. 279-291
Johnson, S. J., Barry, D. A. and Christofi, N. (2007) Anaerobic biodegradation of linear alkylbenzene: isomeric ratio as a monitoring tool Land. Contamination & Reclamation, 15(2), pp. 235-241
Juhasz, A. L. and Naidu, R. (2000) Bioremediation of high molecular weight polycyclic aromatic hydrocarbons: a review of the microbial degradation of benzo[a]pyrene. International Biodeterioration & Biodegradation, 45, pp. 57-88
Juwarkar, A. A., Nair, A., Dubey, K. V., Singh, S. K. and Devotta, S. (2007) Biosurfactant technology for remediation of cadmium and lead contaminated soils. Chemosphere, 68(10), pp. 1996-2002
Kadian, N., Gupta, A., Satya, S., Mehta, R. K., Malik, A. (2008) Biodegradation of herbicide (atrazine) in contaminated soil using various bioprocessed materials. Bioresource Technoogy, 99, pp. 4642-4647.
Kelley, S. L., Aitchison, E. W., Deshpande, M., Schnoor, J. L. and Alvarez, P. J. J. (2001) Biodegrdadtion of 1,4-Dioxane in planted and unplanted soil: effect of Bioaugmentation with Amycolata sp. CB1190. Water Research, 35(16), pp. 3791-3800
Khan, M. S., Zaidi, A., Wani, P, A. and Oves, M. (2009) Role of plant growth promoting rhizobacteria in the remediation of metal contaminated soils. Environmental Chemical Letters, 7, pp.1-19
Krausova, V. I., Robb, F. T. and Gonzalez, J. M. (2006) Biodegradation of dichloromethane in an estuarine environment. Hydrobiologica, 559, pp. 77-83
Kumar, M. and Philip, L. (2006) Bioremediation of endosulfan contaminated soil and water—Optimization of operating conditions in laboratory scale reactors. Journal of Hazardous Materials, 136(2), pp. 354-364
Kuyukina, M. S., Ivshina, I. B., Ritchkova, M. I., Philp, C., Cunningham, C. J. and and Christofi , N. (2003) Bioremediation of Crude Oil-Contaminated Soil Using Slurry-Phase Biological Treatment and Land Farming Techniques. Soil and Sediment Contamination, 12(1), pp. 85-99.
Laine, D, M. and Jarvis, A. P. (2003) Engineering design aspects of passive in situ remediation of mining effluents. Land Contamination & Reclamation, 11(2), pp. 113-125
Lakshmi, C. V., Kumar, M. and Khanna, S. (2009) Biodegradation of Chlorpyrifos in Soil by Enriched Cultures. Current Microbiology, 58, pp. 35-38
Li-feng, G., Jian-dong, J., Xiao-hui, L., Ali, S. and Shun-Peng, L. (2007) Biodegradation of Ethametsulfuron-Methyl by Pseudomonas sp. SW4 Isolated from Contaminated Soil. Current Microbiology, 55(5), pp. 420-426
San Miguel, V., Peinado, C., Catalina, F. and Abrusci, C. (2009) Bioremediation of naphthalene in water by Sphingomonas paucimobilis using new biodegradable surfactants based on poly (3-caprolactone). International Biodeterioration & Biodegradation, 63, pp.217-233
Matsumoto, E., Kawanaka, Y., Yun, S-J. and Oyaizu, H. (2009) Bioremediation of the organochlorine pesticides, dieldrin and endrin, and their occurrence in the environment. Applied Microbiology and Biotechnology, 84, pp.205-216
Miller, M, N., Stratton, G, W. and Murray, G. (2004) Effects of Soil Moisture and Aeration on the Biodegradation of Pentachlorophenol Contaminated Soil. Bulletin of Environmental Contamination and Toxicology, 72, pp. 101-108
Mills, M, A., Bonner, J, S., Page, C. A. and Auternrieth, R. L. (2004) Evaluation of bioremediation strategies of a controlled oil release in a wetland. Marine Pollution Bulletin, 49, pp. 425-435
Mohammed, D., Ramsubhag, A. and Beckles, D. M. (2007) An Assessment of the Biodegradation of Petroleum Hydrocarbons in Contaminated Soil Using Non-indigenous, Commercial Microbes. Water, Air and Soil Pollution, 182, pp. 349-356
Mohan, S. V., Sirisha, K., Rao, R. S. and Sarma, P. N. (2007) Bioslurry phase remediation of chlorpyrifos contaminated soil: Process evaluation and optimization by Taguchi design of experimental (DOE) methodology. Ecotoxicology and Environmental Safety, 68, pp. 252-262
Mueller, J., Moreno, J. and Dmitrovic, E. (2006) In situ biogeochemical stabilization of creosote/pentachlorophenol NAPLs using catalysed and buffered permanganenate: pilot and full scale applications. Contaminated Land and Remediation, 5, pp. 625-629
Mulligan, C. N. and Wang, S. (2006) Remediation of a heavy metal- contaminated soil by a rhamnolipid foam Ls using catalyzed and buffered permanganate: pilotand full scale-applications. Engineering Geology, 85(1-2), pp. 75-81
Narihiro, T., Kaiya, S., Futamata, H. and Hiraishi. (2009) Removal of polychlorinated dioxins by semi-aerobic fed-batch composting with biostimulation of “Dehalococcoides”. Journal of Bioscience and Bioengineering. Available from: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VSD-4X8BV4T-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_acct=C000050221&_vers ion=1&_urlVersion=0&_userid=10&md5=ed95d2e98532b419e84d370405201759 [accessed 8th Jan 2010)
Narasimhan, K., Basheer, C., Bajic, V. B. and Swarup, S. Enhancement of Plant-Microbe Interactions Using a Rhizosphere Metabolomics-Driven Approach and Its Application in the Removal of Polychlorinated Biphenyls. Plant Physiology, 132(1), pp. 146-153
Nikolopoulou, M. and Kalogerakis, N. (2008) Enhanced bioremediation of crude oil utilizing lipophilic fertilizers combined with biosurfactants and molasses. Marine Pollution Bulletin, 56, pp. 1855-1861
Oremland, R. S. and Stolz, J. F. (2003) The Ecology of Arsenic. New Series, 300(5621) pp. 939-944
Panikov, N. S., Sizova, M. V., Ros, D., Christodoulatos, C., Balas, W. and Nicolich, S. (2007) Biodegradation kinetics of the nitramine explosive CL-20 in soil and microbial cultures. Biodegradation, 18, pp. 317-332
Pepper, I. L., Gentry, T. J., Newby, D. T., Roane, T.M. and Josephson, K. L. (2002) The Role of Cell Bioaugmentation and Gene Bioaugmentation in the Remediation of Co- Contaminated Soils. Environmental Health Perspectives, 110 (6) pp. 943-946
Philip, J. C., Bamforth, S. M., Singleton, I. and Atlas, R. M. (2005). Environmental Pollution and Restoration: A Role for Bioremediation. In: Atlas, R. M. and Philips, J. eds. (2005) bioremediation: applied microbial solutions for real world environmental cleanup. Washington: ASM press
Phillips, T. M., Seech, A. G., Lee, H. and & Trevors, J. T. (2005) Biodegradation of hexachlorocyclohexane (HCH) by microorganisms. Biodegradation, 16, pp. 363-392
Philip, J. C. and Atlas, R. M. (2005). Bioremdiation of contaminated soils and aquifers. In: Atlas, R. M. and Philips, J. eds. (2005) bioremediation: applied microbial solutions for real world environmental cleanup. Washington: ASM press
Pimental, D. and L. Levitan. 1986. Pesticides: amounts applied and amounts reaching pests. Biosciences 36:86-91. In: Pesticide Metabolism in Plants and Microorganisms. Van Eerd, L. L., Hoagland, R. E., Zablotowicz, R. M. and Hall, J. C. Weed Science, 51(4) pp. 472-495
Polsenberg, J. (2004) Seaweed Found to Break down DDT. Frontiers in Ecology and the Environment, 2(5), p. 233
Purohit, H.J. (2003) Biosensors as molecular tools for use in bioremediation. Journal of Cleaner Production, 11, pp. 293–301
Rainwater, K., Mayfield, M. P. Heintz, C. and Claborn, B. J. (1993) Enhanced in situ Biodegradation of Diesel Fuel by Cyclic Vertical Water Table Movement: Preliminary Studies. Water Environment Research, 65(6) pp. 717-725
Ramírez, L. C., Iturbe, R. and Torres, L. G. (2008) Effect of nutrient and surfactant addition on polyaromatic hydrocarbon (PAH) biodegradation in contaminated soils. Land Contamination & Reclamation, 16(1), pp. 1-12
Rodgers, J. D. and Bunce, N. J. (2001) Treatment methods for the remediation of nitroaromatic explosives. Water Research, 35(9), pp. 2101-2111
Rojas-Avelizapa, N. G., Rolda´n-Carrillo, T., Zegarra-Martinez., Munoz-Colunga, A. M. and Fernández-Linares, L. C. (2007) A field trial for an ex-situ bioremediation of a drilling mud-polluted site. Chemosphere, 66, pp. 1595-1600
Rosa A. P. and Triguis J. A. (2007): Bioremediation Process on Brazil Shorline. Laboratory Experiments. Environmental Science & Pollution Research, 14(7), pp. 470-477
Rosser, S. J., French, C. E. and Bruce, N. C. (2001) Engineering Plants for the Phytodetoxification of Explosives. In Vitro Cellular & Developmental Biology. Plant, 37(3) pp. 330-333
Ruiz, O. S., Hussein, H. S., Terry, H. and Daniell, H. (2003) Phytoremediation of Organomercurial Compounds via Chloroplast Genetic Engineering. Plant Physiology, 132(3) pp. 1344-1352
Seech, A., Raymond, D. and Moreno, J. (2006) DARAMEND bioremediation for the treatment of PAH impacted soils and sediments. Land Contamination & Reclamation, 14(2), pp. 340-345
Sette, L. D., Mendonça, L. A., Costa, A., Marsaioli, A. J. and Manfio, G. P. (2004) Biodegradation of alachlor by soil streptomycetes. Applied Microbiology and Technology, 64, pp. 712-717
Somtrakoon, K., Suanjit, S., Pokethitiyook, P., Kruatrachue, M., Lee, H. and Upatham, S. (2008) Enhanced Biodegradation of Anthracene in Acidic Soil by Inoculated Burkholderia sp. VUN10013. Current Microbiology, 57, pp. 102-106
Stenuit, B., Eyers, L., Schuler, L., Agathos, S. N. and George, I. (2008) Emerging high-throughput approaches to analyze bioremediation of sites contaminated with hazardous and/or recalcitrant wastes. Biotechnology Advances, 26, pp. 561-575
Sturman, P. J., Stewart, P.S., Cunningham. A. B., Bouwer , E. J. and Wolfram, J. H. (1995) Engineering scale-up of in situ bioremediation processes: a review. Journal of Contaminant Hydrology, 19, pp. 171-203
Thomas, R. A. P., Hughes, D. E. and and Dal, P. (2006) The use of slurry phase bioreactor technology for the remediation of coal tars. Land Contamination & Reclamation, 14(2), pp. 235-241
Tamis, W. L. M., van Dommelen, A. and de Snoo, G. R. (2009) Lack of transparency on environmental risks of genetically modified micro-organisms in industrial biotechnology. Jourmal of Cleaner Production, 17, pp. 581-592
Thomson C D. (2004) Assessment of requirements for selenium and adequacy of selenium status: a review. European Journal Clinical Nutrition, 58, pp. 391–402.
Umrania, V. V. (2006) Bioremediation of toxic heavy metals using acidothermophilic autotrophes. Bioresource, 97, pp. 1237-1242
Venosa, A. D. and Zhu, X. (2003) Biodegradation of Crude Oil Contaminating Marine Shorelines and Freshwater Wetlands. Spill Science & Technology Bulletin, 8(2), pp. 163-178
Wenderoth, W. F. and Rosenbrock, P., Abraham, W. –R., Pieper, D. H. and Hofle, M. G. (2003) Department for Environmental Microbiology, GBF-German Research Centre for Biotechnology, Bacterial Community Dynamics during Biostimulation and Bioaugmentation Experiments Aiming at Chlorobenzene Degradation in Groundwater. Microbial Ecology, 46(2), pp. 161-176
Wagner-Döbler, I., von Canstein, H., Li, Y., Timmis, K. N. and Deckwer, W-D. (2000) Removal of mercury from chemical wastewater by microorganisms in technical scale. Environmental Science and Technology, 34(21), pp. 4628-4634
Walter, M., Boul, L., Chong, R. and Forda, C. (2004) Growth substrate selection and biodegradation of PCP by New Zealand white-rot fungi. Journal of Environmental Management 71, pp. 361-369
Walter, M., Boyd-Wilson, K., Boul, L., Ford, C., McFadden, D., Chong, B. and Pinfold, J. (2005) Field-scale bioremediation of pentachlorophenol by Trametes versicolor. International Biodeterioration & Biodegradation, 56, pp. 51-57.
Wang, S. and Mulligan, C. N. (2006) Natural attenuation processes for remediation of arsenic contaminated soils and groundwater. Journal of Hazardous Materials, B138, pp. 459–470
Young, L. Y. and Phelps, C. D. (2005) Metabolic Biomarkers for Monitoring in Situ Anaerobic Hydrocarbon Degradation. Environmental Health Perspective, 113(1), pp. 62-67
Zhang, P., Sheng, G., Feng, Y and Miller. D. M. (2006) Predominance of char sorption over substrate concentration and soil pH in influencing biodegradation of benzonitrile. Biodegradation, 17(1-8), pp. 1-8
Zhao, B., Wang, H., Mao, X. and Li, R. (2008) Biodegradation of Phenanthrene by a Halophilic Bacterial Consortium Under Aerobic Conditions. Current Microbiology, 58, pp. 205-210
Zuzana, S., Katarína, D. and Lívia, T. (2009) Biodegradation and ecotoxicity of soil contaminated by pentachlorophenol applying bioaugmentation and addition of sorbents. World Journal of Biotechnology, 25, pp. 243-252
