Biodegradation systems for petroleum hydrocarbons

November 6, 2006

Biodegradation systems for petroleum hydrocarbons

Abstract: Crude oil is processed into petroleum, plastics, and many other substances. Oil is composed of polycyclic aromatic hydrocarbons (PAH), which, because of their resistance to decomposition, are persistent, as well as toxic. Researchers are studying the capacity of white rot fungi, of co-evolved micro-organisms on natural oil seeps, and of bacteria to decompose hydrocarbons. Looking to scientific research for biophysical guidance, to the sustainability community for ecological models, and to the emerging wisdom of systems theory for design and process considerations, an integrated approach to waste management can be considered. Locally adapted ecosystems cultivated for PAH decomposition could turn a problem into a resource both biologically and socio-economically through job-creation.


Introduction

Modern life uses vast quantities of oil. It is transported, refined, and manufactured into a huge number of products, including plastics. Oil is composed of tightly bonded hydrocarbon chains. Total petroleum hydrocarbons (TPH) are a large family of chemicals derived from crude oil which enter the environment through soil or air, and cause nervous system, lung, kidney, and liver damage (ASTDR, 1999). From the incomplete burning of oil comes polycyclic aromatic hydrocarbons (PAH), which are suspected carcinogens, and are found in medicines, plastics, pesticides, and asphalt ( ATSDR 1995). PAH are persistent toxins that are mainly of anthropogenic origin, and are found to accumulate in areas of exposure (Trapido, 1998). Gaseous and condensed PAH can be carried long distances before being deposited (Wania & MacKay, 1996). Occasionally, crises occur where large quantities oil enter the ecosystem, such as oil spills, or storms, such as Hurricane Katrina. Both in manufacture and in disposal, more and more hydrocarbon compounds are being introduced into the environment.
Research regarding the biodegradation of hydrocarbons has mainly centered around the family of white rot fungi (WRF) because of their lignin-degrading capacity. Tests show greater decompositional efficiency by WRF in a water substrate and less efficiency in soil substrate (Boyle et al., 1998). Research testing a number of varieties of WRF for PAH removal from gas-manufacturing contaminated soil showed an overall average of 30% PAH decrease in the first month (Sasek et al., 2003; Rudd et al., 1996). Growth seems negatively affected by nitrogen additions, and additions of alfalfa or sawdust also impede remediation slightly (Boyle et al., 1998). Of note, WRF that had been previously exposed to PAH exhibited faster decomposition, inferring induciblity (Boyle et al., 1998).

Another area of research regarding hydrocarbon biodegradation is observing the co-evolved ecosystems of natural oil seeps. At an active natural oil seep along the Dorset Coast, UK, researchers analyzed acidophilic microbial communities, and recorded complete degradation of PAH as well as other compounds by both bacterial and fungi (Roling et al., 2005).
Operating in parallel to the academic community is what I will refer to as the sustainability community, by which I mean the movements and institutes of permaculture and sustainable design. Combining science, ancient wisdoms, traditional knowledge, ecology, and system theory, this community has created a large body of knowledge on low-technology, low-impact, ways of living in a relationship of mutual enhancement with the earth. The ability of fungi to bioremediate has been of much interest here for while, with Paul Stamets leading the research. Recently, Battelle, a global (Ohio-based) science and technology enterprise, performed tests involving a number of strategies to bioremediate crude-oil saturated soil: while the conventional chemical and bacterial attempts revealed little noticeable change four weeks after treatment, the area that was inoculated by Stamets with a diversity of fungi, including the common and delicious Oyster mushroom, showed not only rapid decomposition, but a much accelerated succession to a vegetated state (Stamets, 1999). Analyses showed PAH degradation to be 95%, and constituents reduced to non-toxic components; the mushrooms even tested free of toxins (Stamets, 1999).

Bridging the gap between these communities is systems theory. System theory/thinking/dynamics has given us whole new ways of looking at how everything works in relationship. From this exciting, emergent body of knowledge, we better understand how ecological systems and social processes function and evolve. This gives us tools for designing and altering physical systems, as well as tools for creating change in existing social systems. Through observant design that mimic natural systems, incorporating feedback and meta-feedback loops, we can support the forces and processes that help a system to run itself (Meadows, 2001). Biological systems are multi-functional, self-producing, self-cleaning, co-evolving processes, making them viable options if a strict definition of sustainable is adopted and aspired to (Capra, 1996).

A system is truly sustainable if it is: mutually enhancing to the human and non-human communities; provides habitat for biodiversity; is economically viable to create and maintain by both wealthy and poor communities; and is designed for flexibility in its long term functioning. Using this definition, this paper will examine what systems are creatable at a local level to deal with the plethora of hydrocarbons, and what some strategies to create change may be.


Methods
The main method used was research through both the academic and sustainability cannons, supported by observation of natural systems. This paper combines both scientific, peer-reviewed journal articles, and case studies performed by players in the sustainability arena. Three years of soil observations in a variety of ecosystems and while provides my framework for understanding.
I will focus mainly on the praxis of addressing the problem in the bulk of this paper, rather than the socio-political systems that function to create, propagate, and exacerbate the problem. My biases towards decentralization and a devotion to an environmental ethic are visible within my definition of sustainable.

Discussion
Analysis
Current oil production is around 83.3 million barrels a day (Worldwatch, 2006). Crude oil is a persistent toxin. It is made of a tightly-bonded structure of hydrocarbon chains, and comes mainly from anthropogenic sources; these hydrocarbons are resistant to decomposition. Polycyclic aromatic hydrocarbons (PAH) are of particular concern as they are potentially carcinogenic, according to the US EPA (ASTDR, 1995). PAH can be found in medicines, plastics, dyes, asphalt, oil, smoke, charcoal, and tar (ASTDR, 1995). They are beginning to be found globally in increasing amounts in the humus layers of soil (Roling et al., 2005).
In 2000, Ontario produced 67,916 tonnes of plastic garbage, 22, 040 tonnes of which were recovered (Envirosis, 2001). Current waste management involves the conventional practices of creating landfills, incineration, and recycling. These practices do not involve the direct and efficient decomposition of persistent toxins, but rather only function to contain or proliferate them. The production and externality costs of landfilling are high (Miranda and Hale, 2004), as landfills are filling up, and governments are facing an inability to site new waste disposal locations (Hostovsky, 2006). In exacerbation, the predicted energy crisis will negatively affect our current centralized waste management system. High production of TPH and PAH are coinciding with problematic waste management strategies. As well, crises such as spills and storms, can contribute to TPH and PAH to the environment in a disastrously abrupt way. New Orleans, after Hurricane Katrina, is an example of a post-crisis site with heavy terrestrial and aquatic contamination; clean-up efforts are still underway.

Conventional methods for treatment of TPH and PAH contaminated sites often involve a pump-and-treat strategy, involving excavation before treatment, but excavation demands a high cost in energy, footprint and finance, limiting the possibility of its application. Treatment can also occur in situ: these include incineration, containment, oxidation, and biological means. Incineration offers the potential to harvest energy through waste-to-energy (WTE) technologies, and could potentially be economically viable (Miranda and Hale, 2004), but it creates more PAH, making it a much less efficient option in the long term. Containment creates anaerobic environments, slowing decomposition; oxidation is used to accelerate decomposition. Oxidation and aeration can occur through physical or chemical processes; hydrogen peroxide and ozone oxides can be used; increased levels of oxygen work to increase microbial metabolism as well as accelerate chemical reactions (Wikipedia, 2006a).

Current biological methods involve the metabolism of microbial populations, including bacteria, fungi and enzymes, as well as the possible use of plants, to convert problematic hydrocarbons to bio-available components (Wikipedia, 2006a). Biostimulation, through enhancing conditions for native populations, and bioaugmentation, by the addition of suitable but non-native species, are used depending on the situational context. Biostimulation generally involves the addition of nutrients, such as potassium, nitrogen, calcium and molasses (Wikipedia, 2006b); the environmental affects of such inputs must be monitored for tertiary impact, as some research suggest that nitrogen inputs may actually act to reduce fungal activity (Boyle et al,1998).

Scientific study around the biological degradation of problematic hydrocarbons has primarily explored the capacity for white rot fungi (WRF) to decompose PAH. WRF are a large family with the unique capacity to biodegrade lignin completely down to carbon dioxide; lignin is a natural polymer of cell walls in trees which give strength and contains the cellulose molecule that WRF can use as an energy source (Aust & Bensen, 1993). The fungi uses an extra-cellular and non-specific system of chemical production to decompose the tight carbon bonds, which also explains their resistance to toxic or mutagenic chemicals (Aust & Bensen, 1993). Results reveal faster decomposition in water substrates, and slower decompositional processes in soil (Boyle et al.,1998). Research testing PAH removal from gas-manufacturing contaminated soil by WRF Irpex lacteus and Pleurotus ostreatus, with bacterium Psuedomonas putida, showed, though all to be capable at decomposition, I.lactues to be most efficient, alone or in co-culture with bacteria (Sasek et al., 2003). The fungi to be capable of decomposing PAH and TPH down to bioavailable carbon dioxide and water (Sasek et al., 2003). Decreases in mutagenicity of crude oil have also been observed by decomposition by Cunninghammella elegans and Penicillium zonatum (Rudd et al., 1996).The growth of WRF, in this case Trametes versicolor Pilat strain 52P, was negatively affected by nitrogen inputs (Boyle et al., 1998), an observation supported by the decrease in agricultural mycorrhizae with increase in soluble potassium fertilizers (Kramer & Morely, 1990). Of note, it has been observed that WRF previously exposed to PAH exhibited faster decomposition, inferring the capacity for fungi to be cultivated for greater efficiency (Boyle et al., 1998).

Another area of research regarding hydrocarbon biodegradation is observing the co-evolved ecosystems of natural oil seeps. At an active natural oil seep along the Dorset Coast, UK, researchers analyzed acidophilic microbial communities, and recorded complete degradation of PAH as well as other compounds by both bacterial and fungi (Roling et al., 2005). This knowledge can aid bioremediation design to create optimal conditions, and asses measurement parameters (Roling et al., 2005).

The sustainability community has been looking at biological methods of pollution clean-up for the past 30 years from more of a low-tech, low-cost perspective. Working between this group and the scientific community, Paul Stamets has helped fungi reveal its potential to render hydrocarbons bioavailable; the difference is that Stamets is not using only WRF, but a broad variety of fungal species, including the delicious edible ‘oyster’ mushroom. In 1999, Battelle, a science and technology enterprise based in Ohio, conducted an experiment; they invited leading groups with the leading bioremediation technologies together to conduct a simultaneous test on crude oil saturated soil: while chemical, and bacterial strategies showed little improvement, the fungi inoculated pile by Stamets not only showed PAH reduction of 95%, but the fungi acted as a keystone species in accelerating succession: by attracting insects, birds came, bringing seeds, an accelerated succession to vibrant vegetation occurred, without intervention (Stamets, 1999). The mushrooms were even tested free of toxicity (Stamets, 1999). Battelle concluded that mycoremediation is safe, economical, fast, does not generate any toxic side-effects, and in fact, produces a useful end-product, turning a liability into an opportunity (Thomas, 2000).

Assessment
It is known that PAH and TPH are persistent toxins increasing in our environment from primarily anthropogenic sources, and that conventional methods do not sufficiently remediate these compounds. High technology solutions requiring high energy inputs are not available in many situations for economic reasons, nor are they sustainable. Definitions of ‘sustainable’ are subjective, resulting in a high variability of ‘sustainable’ practices. To be clear, a system is only truly sustainable if it is: mutually enhancing to the human and non-human communities; provides habitat for biodiversity; is economically viable to create and maintain by both wealthy and poor communities; and is designed for flexibility in its long term functioning. Using this definition, this paper will examine what systems are creatable at a local level to deal with the plethora of hydrocarbons, and what some implications of such a system may be.
Scientific research enhances our understanding of specific, detailed processes, such as rates of decomposition by various species of fungi, as well as helps us understand the environment as a co-evolving ecosystem. The sustainability community has been working to integrate science and ancient wisdoms to design ways of living with low impact on the planet. While these movements are parallel, they also often diverge. Systems dynamics is scientific theory that can ecosystems in a holistic way shared by the sustainability community. It gives us scientific language and theory through which to frame our strategies.

System thinking is an emergent body of knowledge about living, moving, dynamic processes and patterns. Life is change and movement; everything is interdependent; the ancients knew this; systems dynamics give us scientific language to speak of these complexities. Systems thinking is, in a way, a whole new ontological Story that can completely shift one’s view on life, from seeing a collection of atoms and chemical processes, to seeing the planet as an organism, including everything upon and within the planet. This ontological shift is necessary in reducing the toxicity of the environment, and in shifting the strategy we use to address existing toxins (Berry, 1999). Systems theory is language we can use to bridge the connections between science, spirituality, ecology, and society, as it is the language of connection. Some specific tools from systems dynamics include Donella Meadows’ “Leverage Points; places to intervene a system” (1999). Here she lists twelve such ‘locations’ in order of increasing effectiveness; within stocks and flows ratios, delay to change ratios, in feedback mechanisms, in information flows, rules, and goals of the system, are leverage points (Meadows, 1999). Another tool from the systems thinkers comes in the form of “Action to Outcome Mapping” (Jones & Seville, 2003). This is a strategy-testing tool for groups trying to achieve a broad, long-term outcome. By mapping out 1) existing causal theories, 2) adding feedback, 3) mapping critical mindsets, 4) accounting for external forces, and 5) identifying opportunities for learning, a strategy can be designed to be flexible, sustainable, and successful (Jones & Seville, 2003).
This gives us tools for designing and altering physical systems, as well as tools for creating change in existing social systems. Through observant design, feedback and meta-feedback loops, we can support the forces and processes that help a system to run itself (Meadows, 2001). Biological systems are multi-functional, self-producing, self-cleaning, co-evolving processes, making them viable options for the definition of sustainable aspired to.

Action
Goal
Sustainable waste management for TPH and PAH can occur through cultivating biological processes. Bioregionally adapted microbial species, both fungal and bacterial, capable of metabolizing hydrocarbons completely, should be cultivated at every waste management site. Through local development and sharing, microbial populations that are increasingly effective at metabolizing hydrocarbons can be cultivated with the wisdom of what functions efficiently at the local level. These sites can serve as nurseries for innoculant distribution, with the goal of increasing small systems that responsibly deal with waste. A network of systems within systems, integrating waste decomposition, resource creation, food production, and human habitation, can be created by the community, for the community, consciously using the wisdom of science, ancient knowing, and systems theory.

Tactics
The deeper goal of systemic change must accompany the discussion of waste management strategies. I stress the word discussion as it will also take much community dialogue, education, and planning to create the taking and sharing of responsibility that this
vision entails. Community design charrettes, designed and subsidized by CMHC, are a valuable method of bringing together the scientific community, the sustainability communities, planners, builders, specialists, government officials, and citizens. A community design charrette gives a format for a meaningful and constructive discussion to occur which produces a workable body of knowledge.

Preceding and concurrent to the community design charrette, effort would be necessary to educate the public, lobby government and industry, and create community support for a shift to biological methods of waste management. Media plays a key role in public awareness and opinion, and should be innovatively used. Ultimately, a closer intimacy with natural systems must be fostered so that people can better understand the planet as an organism, made of interdependent systems within complex system, with every action having affect. Becoming intimate with natural systems will help us integrate the many available knowledge sets into a well-designed strategy for sustainable waste management.

Conclusions
It is known that PAH and TPH are persistent toxins increasing in our environment from primarily anthropogenic sources, and that conventional methods are not able to completely remediate these compounds. Sufficient research exists in the scientific community, as well as in the sustainability community, to deem biological remediation safe, effective, and affordable. Certainly, case studies show that bioremediation using a diverse range of fungi species can biodegrade PAH to benign bio-available substances, and accelerates succession; in a mutually beneficial way they can turn a liability into a resource. Biological methods of waste management should be incorporated into every municipal waste management site. These sites can function as research stations and nurseries to support a multiplicity of responsible small systems. Decentralization of the system will reduce transportation and energy expenditures, and will distribute resources more widely. Using community design charrettes and action-to-outcome mapping, a locally viable system of multiple systems that work in a mutually enhancing way can be designed.



Literature Cited

ATSDR: Agency for Toxic Substances and Disease Registry. U.S. Department of Health and
Human Services. 1999. ToxFAQs for Total Petroleum Hydrocarbons. http://www.atsdr.cdc.gov/tfacts123.html

ATSDR: Agency for Toxic Substances and Disease Registry. U.S. Department of Health and
Human Services. 1995. ToxFAQs for Polycyclic Aromatic Hydrocarbons.
http://www.atsdr.cdc.gov/toxprofiles/phs69.html

Aust, S; Benson, J. 1993. The fungus among us: the use of white rot fungus to
biodegrade environmental pollutants. Environmental Health Perspectives, Vol
101(3): 232-233.

Berry, T. 1999 The Great Work: Our way into the future. Bell Tower, New York.

Boyle, D; Wiesner, C; Richardson, A. 1998. Factors Affecting the Degradation of
Polyaromatic Hydrocarbons in Soil by White Rot Fungi. Soil Biol. Biochem. Vol 30, No 7: 873-882.

Capra, F. 1996. The Web Of Life: A New Scientific Understanding of Living Systems. Anchor
Books, New York.

Envirosris. Plastic Waste Management Strategy for Ontario. 2001.

Hostovsky, C.2006. The paradox of ration comprehensive model of planning: tales
from waste management planning in Ontario, Canada. Journal of Planning,
Education and Research 25: 382-395.

Jones, A; Seville, D. 2003. Action to Outcome Mapping: testing strategy with systems thinking.
Systems Thinker Vol. 14 (2): 9-11.

Kramer, D; Morely, P. 1990. “The Hidden World of Mycorrhizae”. Gleanings from
Canadian Organic Growers. Canadian Organic Growers, Ottawa, Ontario; 59-61.

Meadows, D. 1999. Leverage Points: places to intervene in a system. Sustainability Institute.
http://www.sustainer.org/tools_resources/papers.html

Meadows, D, 2001. Dancing with Systems. Whole Earth, Winter: 27 –234.

Miranda, M; Hale, B. 2004. Paradise recovered: energy production and waste
management in island environments. Energy Policy 33: 1691-1702.

Roling, W; Ortega-Lucach, S; Larter, S; Head, I. 2006. Acidophilic microbial
communities associated with a natural, biodegraded hydrocarbon seepage.
Journal of Applied Microbiology 101:290 - 299.

Rudd, L; Perry, J; Houk, V; Williams, R; Claxton, L. 1996. Changes in mutagenicity
during crude oil degradation by fungi. Biodegradation 7: 335 – 343.

Sasek, V; Cajthaml, T; Bhatt, M. 2003. Use of Fungal Technology in Soil Remediation:
A Case Study. Water, Air and Soil Pollution; Focus 3: 5-14.

Stamets, P. 1999. Helping the ecosystem through mushroom cultivation. Whole Earth,
Fall. http://www.fungi.com/mycotech/mycova.html.

Thomas, S. 2000. Mushrooms: higher macrofungi to clean up the environment. Battelle
Environmental Updates, Fall. http://www.battelle.org/Environment/
publications/EnvUpdates/Fall00/article4.html

Trapido, M. 1998. Polycyclic aromatic hydrocarbons in Estonian Soil: contaminations
and profiles. Environmental Pollution 105: 67 –74.

Wania, F., MacKay, D. 1996. Tracking the distribution of persistent organic pollutants.
Environmental Science and Technology 30: 390A-396A.

Wikipedia, 2006a. Bioremediation. http://en.wikipedia.org/wiki/Bioremediation

Wikipedia, 2006b. Biostimulation. http://en.wikipedia.org/wiki/Biostimulation

Worldwatch Institute, 2006. Fossil Fuel Use Continues to Rise.
http://www.worldwatch.org/node/4243.