Waste Management & Bioremediation

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What is Bioremediation?
Bioremediation is the controlled use of biologically active systems to bring about desired chemical and /or physical changes in a confined and regulated environment. These desired changes include:

  • The accelerated decomposition of many hazardous organic compounds;
  • The improvement in environmental quality; and
  • The reduction of human health risks.
  • The process is biological, nature’s method of dealing with wastes which can be eliminated from the environment through natural decomposition. It is Nature’s “Technology of Choice”. Bioremediation through bio-enhancement accelerates the process, and in most cases, is clearly superior and less costly than conventional methods.

    How Does It Work?
    Bioremediation consists of using techniques for enhancing naturally occurring microorganisms that can biologically transform and/or eliminate the pollutants, and bringing these microorganisms into intimate contact with the pollutants. Microorganisms such as bacteria and fungi have been shown to be effective and important in bioremediation processes. Most research has to date centered on the use of bacteria, but fungi can play an important role in bioremediation processes, especially with halogenated compounds. In almost all cases, the bioremediation process relies on diverse populations of microorganism species, rather than on one or a few species.

    Bioremediation vs. Conventional Methods
    Normal practice prior to the availability of efficient bioremediation processes has been to excavate contaminated soils or sludges and haul them away to some landfill or incinerator facility. Landfills are becoming more restrictive and incineration costs are high and expected to increase. To the cost of landfilling and expenses that must be added for excavation, loading, transportation and replacement with clean fill. Moving contaminants also involves risks.
    Bioremediation – accelerating the natural on-site biological cleanup processes offers a safer and less expensive alternative in most cases.

    The Bioremediation Process
    Bioremediation is achieved through bio-enhancement, the addition of large numbers of selected naturally occurring microorganisms. With bio-enhancement, a sufficient amount of selected microorganisms are applied to the soil to give an initial population of approximately one million per gram of soil. Studies have shown that this concentration insures that an efficient population of organisms will increase up to one thousand fold as they digest the contaminates. Bio-enhancement greatly increases the rate of degradation compared with the natural process because of the low numbers of naturally occurring microorganisms present in the soil.
    Generally a contaminant must move through the waste/soil matrix and pass through a microorganism’s cell membrane in order for the microorganism to transform the contaminant, although, in some cases, contaminants can be transformed by extracellular enzymes without entering into the microorganism. Several physical and chemical parameters must be controlled in order to obtain optimum biological activity and maximum degradation of contaminants. These parameters include soil, oxygen and nutrient concentrations, as well as temperature and moisture conditions.

    Operating Conditions

  • Soil – Types of soil and conditions play an important role in the bioremediation process because they can limit the interaction between contaminant compounds and microorganisms. Waste compounds which have low solubility in water are slow in moving from soil adsorption sites or free phase droplets into the soil water and from there into the microorganisms.
  • Wastes in solid matrices (soil) have less solvent (water) in which to be dissolved for mobility, are more likely to have highly variable concentrations throughout the matrix and are harder to mix thoroughly. To insure optimum penetration and coverage, contaminated soils must be treated appropriately.
  • Nutrients – In most soil treatment, bioremediation will be accelerated when certain nutrient levels are present and can be maintained. In most cases, constant addition is necessary to insure the continuance of the bioremediation process.
  • Oxygen – Many contaminants can be biologically degraded aerobically which requires oxygen. The oxygen concentration is the rate limiting factor in the biodegradation of many contaminants such as petroleum products. Microbial activity is most frequently limited by insufficient oxygen due to slow rates of diffusion into the interior of the soil layers. Generally, the greater the mass of oxygen that can be distributed, the more rapid and complete the cleanup.
  • Temperature & Moisture – Studies have shown 28 degrees centigrade to be the optimum temperature for growth of soil derived microorganisms. Growth rates will slow as the temperature decreases. Similar studies have shown that soil moisture should be maintained at 20 – 30%.

  • Project Evaluation
    Any on-site bioremediation process utilizing microorganisms requires an in-depth knowledge of site conditions in order to be effective. Projects should begin by analyzing soil samples from a given site to determine both indigenous microorganism populations and contaminant constituents. This information is required to determine biodegradability and the proper types of microorganisms, nutrients and conditions needed. Mixtures of site specific microorganisms are then prepared and quantities grown for inclusion in the site treatment. At the same time, site conditions are prepared for eventual application. Once field applications begin, process development is monitored through regular on-site tests. This measures remediation progress and indicates if any adjustments are needed. When testing shows that the required level of cleanup has been achieved, a final test audit is performed.

    Areas of Application
    Bioremediation has been successfully used in a variety of applications to date. The methods of application vary depending on specific site conditions.

  • Surface Soil Contamination: Where the contaminated soils are limited to the upper two feet, rot tilling or dicing the soil to provide even distribution of the microorganisms and other components has proven effective. The finer the soil, the more surface area available to the microorganisms to get access to the contaminants. Repeated tilling provides aeration to further accelerate the process.
  • Sub-Surface Soil Contamination: the type and compactness of soil will determine the method of application needed to deliver the microorganisms into the contaminated zone, pressure jetting or ponding.
  • Lagoon Contamination: Hazardous waste lagoons usually require treatment of both liquid and sludge build-up. Special application systems have been developed for this purpose.
  • Water Contamination: Ground or stored water containing contaminants can be treated by establishing a means of circulating the water through a bioreactor where it is acted upon by a combination of microorganisms and then returned to the source when cleaned.
  • Water Body Contamination: Water bodies such as ponds, small lakes, canals and aquaculture farms can suffer from the build-up of sludge and high mineral concentrations. Special bioremediation systems have been developed by JPS for reducing these types of contaminants.

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