Contamination of ecosystems by xenobiotic compounds (including various organic petroleum hydrocarbons, pesticides and other agrochemicals, pharmaceutical products and heavy metals) causes ecological problems leading to serious environmental problems [1
]. Attempts at remediating contaminated sites have used conventional but often costly approaches, such as ‘pump and treat’, excavation and removal, soil vapour extraction, and other chemical treatments [6
]. These methods are time consuming, invasive, disruptive to natural habitats and usually result in a rearrangement of the problem [3
]. Using these methods, it is estimated that the cost of reinstatement of all contaminated sites in the United States alone is approximately US$1.7 trillion [7
]. Lately however, bioremediation has proven to be a safe, effective, low-cost and environmentally friendly alternative for sustainable remediation of environments contaminated by hazardous and recalcitrant pollutants [3
]. Bioremediation uses biological processes and naturally occurring microbial catabolic activity to eliminate, attenuate or transform contaminants to less hazardous products such as carbon dioxide, water, inorganic salts, and microbial biomass [10
Bioremediation generally has high public acceptance and can be carried out in various environmental media for a wide variety of organic and inorganic compounds [14
]. However, bioremediation research and practice are currently still hampered by an incomplete understanding of the genetics and genome-level characteristics of the organisms used, the metabolic pathways involved, and their kinetics. The result of this is an inability to model and predict the behaviour of these processes, and hence a difficulty in developing natural bioremediation processes in the field [15
Bioremediation techniques can take place in situ
and ex situ
, and have been widely characterized [3
]. While the former may lead to minimal disruption of sites and elimination of handling costs, they usually require longer periods of treatment and extended monitoring. They can also be constrained by geological, hydro-geological and other environmental factors, resulting in a low efficiency of contaminant removal [3
]. The latter (such as land farming, biopiling, composting and bioreactor treatment) involve the removal of materials by excavation, pumping or dredging, which allows greater process control though there will be some disruption to the site. They are also more thorough and enable environmental conditions of contaminated material to be easily modified and monitored, leading to greater efficiency of treatment. However excavation and transport of materials add significantly to remediation costs, leading to a preference for in situ
There have been various reports of biodegradation and bioremediation activities utilizing particular bacteria or plant species, with various degrees of success [16
]. However, no investigations have been found relating to trends and possible drivers in the global use of these techniques. Kinya and Kimberly [18
] surveyed the extent to which remediation firms and research centers have implemented strategies for clean-up of soils and groundwater, comparing clean-up costs, and related opinions on the use of non-indigenous microorganisms for bioremediation. However the survey, which was quite detailed, focused on one country and one compound-the USA and Tricholoroethylene (TCE) respectively.
Therefore, information on the following is not well known: (1) the demography of the relative acceptance and global use of bioremediation, (2) the factors driving such usage, (3) the barriers limiting its implementation, and (4) the extent of application of current biotechnological advances within the sector. Lekakis [26
] used Greece as a case study to explore the relationship between economic indices (Gross Domestic Product, and per capita income) and public spending on Research and Development (R&D) for environmental protection and conservation. Summersgill [27
] provided information on costs and market conditions and use of remediation technologies across Europe. The study which covered a three-year period (2001-2003), elaborated on the prominence of particular remediation technologies in member states and the reasons behind such prominence. It highlighted market changes that have occurred during that period in five European countries, and showed that the primary driving force was cost. Jalal and Rogers [28
] carried out a similar study among Asian countries and showed marked variability between rich and poorer countries in the perception and approach to remediation issues. These reflected their relative abilities to invest in R & D for novel techniques such as bioremediation. Rivett, Petts et al. [29
] also observed marked contrasts in levels of importance accorded to process-based remediation techniques versus physical methods like land filling. There was a lack of centralized information on remediation activity, even in some first-world countries, and differences in levels of funding for the development and provision of remediation information. Thus, economic barriers may limit certain countries’ access to the growing body of information on degradation of xenobiotics by micro-organisms.
Available historical data on the usage of bioremediation technologies for decontamination of polluted sites are somewhat uninspiring. The UK Environment Agency [30
] reported that of the 391 contaminated land sites addressed during the 2000-2007 period, in situ
bioremediation was used on only 4. Ex situ
bioremediation was proposed, but not actually used, on only 2 sites. Phytoremediation - the use of plants for land remediation - was not even mentioned. Relatively higher figures have been reported for the United States. According to the US-EPA [31
], of the 997 source-control-treatment projects carried out during the 1982-2005 period, 240 were classified as ‘innovative technologies’, of which there were 60 ex situ
and 53 in situ
bioremediation projects-a small percentage (~12%) overall. These two reports indicate that the contribution of bioremediation to environmental site clean-up has been very small. Information on researchers’ preferences has also not been found.
Molecular tools, other ‘omics
’ technologies, and decision-support software for selection of ‘gentle’ remediation approaches have been documented [8
]. A number of software tools for modelling environmental perturbations have also been developed [36
]. However, information on the extent of use of such tools and technologies is restricted to certain countries. Therefore, in order to get a coherent picture of the status of bioremediation activities, a global survey was conducted to investigate drivers and barriers to the use of bioremediation, evaluate global differences in priority areas and identify specific needs of the bioremediation sector.