Bioremediation — Water Treatment Tool to Fix Pollution Problems

by Joe Gelt

Bioremediation is putting microorganisms to work. “Bio” refers to the biological organisms and “remediation” refers to the job to be done: remediating or resolving an environmental problem caused by toxic chemicals and other hazardous wastes in soil and groundwater.

Biodegradation is a natural process. In a non-polluted environment microorganisms or microbes, including bacteria, algae and fungi, are hard at work breaking down organic matter. Enter an organic pollutant such as gasoline or oil. The result: some of the microbes die while others capable of eating the organic pollutant survive.

Bioremediation speeds the process and increases efficiency by providing pollution-eating organisms with fertilizer, oxygen, and other conditions that encourage their rapid growth. The feeding of the microbes, sometimes whimsically called “bugs,” causes more chemicals to be digested and converted into water and harmless gases such as carbon dioxide. The field of bioremediation encompasses numerous strategies to clean up pollution by enhancing the same biodegradation processes that occur in nature.

In exceptional cases, specialized, non-indigenous microbes might be introduced to help degrade the contaminants. This, however, is rarely done as University of Arizona microbiologist Jim Field explains, “That is a misnomer about bioremediation that we use super bugs from the lab, but that is not true. ... Most of the time in bioremediation we provide the conditions that are optimal for degradation rather than providing the microorganisms.”

Establishing a bioremediation system is a complicated task requiring an interdisciplinary approach. Hydro Geo Chem’s Principal Scientist Harold Bentley explains: “It requires knowledge of chemistry, biology, and hydrology and the flow system, all of those things integrated together. It requires a significant understanding of the site and the ability to use knowledge gained about the site to tune your system.”

Bentley says, “There usually is a biological solution to most pollution problems. ... It is finding the right microbe to work against a particular pollutant, with something added to encourage the reaction.”
Essential to establishing a bioremediation system is a knowledge and understanding of microbes and their pollution-fighting potential. Northern Arizona University’s Bioremediation Initiative or BIORIN is a resource in this area. To promote a better understanding for the potential of bioremediation and to encourage its greater use, BIORIN researchers are identifying microbial processes that actively biodegrade contaminants.
Such basic information is very much needed. Maribeth Watwood, chair of NAU’s Department of Biological Sciences, says, “When you want to consider bioremediation as a remediation option at a site, EPA and other agencies require that the best available technology be used. Without having a strong literature base, it is very difficult, no matter how great the idea is, to claim it is the best demonstrated technology.”

BIORIN is compiling a database to provide credible documentation work in support of considering bioremediation at contaminated sites with certain characteristics. Bruce Hungate and Egbert Schwartz, both NAU professors, work with Watwood on the BIORIN team. Watwood says, “There is a big push to understand biodegradation processes; we know astonishingly little about the range of capabilities of bacteria. Subsurface microbiology is a new field, relative to other branches of environmental science.”

Field also acknowledges the need for much more research. He says, “Of all the microbes that we know exist based on DNA we have only been able to culture about one or two percent of them.” Microbes are best studied by culturing.

BIORIN was also established to promote bioremediation in Arizona by providing information about the technique and demonstrating their efficacy. Watwood says Arizona has lagged somewhat in adopting bioremediation technology. “ADEQ is receptive, but they need to see data, to see this actually works before implementing it full-scale.” She hopes that such work as is being done at an Arizona Water Quality Assurance Revolving Fund site in Tucson will demonstrate the effectiveness of the biological approaches.
Along with University of Arizona researcher Mark Brusseau, BIORIN researchers are studying the Tucson WQARF site located near Park and Euclid avenues. The site was once the location of railroad yard and dry cleaning operations. Work at the site includes determining what kinds of microbes are in the subsurface, including those within the contaminated plume. Further, tests are being conducted to determine not only what kinds of contaminants the bugs can degrade but whether they are in fact doing it. The researchers are using techniques developed at BIORIN to obtain the information.

Techniques being applied to the site include molecular procedures that identify specific microbes, and enzyme probes and stable isotope approaches that identify specific degradation reactions taking place in the contaminated zone.

Watwood says BIORIN has been able to demonstrate the occurrence of plentiful natural microbial activity that is degrading some of the main contaminants at the site. This will be an important factor to consider when designing a cleanup strategy.

Bioremediation has wide and varied application. Watwood says, “There is very likely a biological approach that can be the solution or part of the solution for many different contaminated sites. In cases where it is very difficult to stimulate the natural community we look to more heavily engineered systems, possibly relying on the activity of added organisms or systems using genetically modified organisms”

She notes, however, that genetic engineering raises other kinds of problems. Strict federal regulations have to be met when a genetically modified organism is considered. Also genetically engineered organisms are often very fragile and unable to live and function in a natural community.

Bioremediation is a relatively new field, with the first patent issued in the 1970s to stimulate subsurface microbial activity to cleanup gas pollution. The field greatly expanded with the advancement of molecular technologies during the 1980s and 1990s. Scientists were then better able to study the kinds of microbes that existed in the environment.

Many microorganisms remain to be discovered. Field says, “Microorganisms are like stars. ... Microbiologists know of the existence of many microorganisms because of DNA sequences. ... There are probably millions more yet to be discovered. There is a endless capacity of different microorganisms; there is going to be new ones discovered all the time.”

For example, University of California, Davis, researchers have recently discovered an organism that eats MTBE. Once added to gasoline to improve air quality, MTBE has contaminated groundwater throughout the country, with no way known to treat groundwater to remove the contaminant. Nicknamed PM1, the newly discovered MTBE-eating organism is present in groundwater but has to be pumped to the surface to multiply and eat MTBE.

Watwood says a great growth potential exists in the bioremediation field, that there are many polluted sites in need of clean up. She also expects bioremediation will be increasingly used for pollution prevention, with waste streams treated before they cause environmental problems. The idea is to eliminate environmental pollution, not just treat it once it occurs.

She says. “That is how I hope the field will evolve.”

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