Final Report: An Innovative System for Bioremediation of Agricultural Chemicals for Environmental SustainabilityEPA Grant Number: SU833682
Title: An Innovative System for Bioremediation of Agricultural Chemicals for Environmental Sustainability
Investigators: Kalita, P. , Davidson, Paul C.
Institution: University of Illinois at Urbana-Champaign
EPA Project Officer: Nolt-Helms, Cynthia
Project Period: July 7, 2007 through July 6, 2009
Project Amount: $75,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2007) Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Agriculture , P3 Awards , Sustainability
This research has been conducted based on the hypothesis that a properly designed, naturally available biofilter system can significantly reduce the amount of chemicals entering surface water sources. The hypothesis is based on preliminary results from Davidson (2005), which showed a woodchip biofilter to effectively reduce nitrogen, atrazine, and alachlor from groundwater when used as a layer within the soil.
The specific research objectives were to:
- Evaluate the efficiency of a variety of biomaterials for bioremediation of agricultural chemicals;
- Based on the results obtained from objective (1), develop design criteria for an efficient system for bioremediation of agricultural chemicals; and
- Provide recommendations for field application of the bioremediation technology.
Agricultural chemicals (both inorganic and organic) in drainage discharge from watersheds have raised concerns about the quality of surface water resources. For example, hypoxia in the Gulf of Mexico has been related to the nutrients discharging from agricultural watersheds in the Mississippi River Valley. Finding an efficient and cost effective solution to the nutrient problem is of utmost importance. Experiments were conducted during September 2006 – April 2007 at the University of Illinois to determine the efficiency of various biomaterials for removing agricultural chemicals from drainage discharge. Soil columns were used to investigate the chemical reduction in water when it passes through biological filters; beaker experiments were conducted to investigate if biological activities would enhance chemical reduction. The results from both the soil column and beaker experiments support the hypothesis that a properly designed, naturally available biofilter can significantly reduce the amount of chemicals leaving agricultural fields. It has been determined that hardwoods (in general), cocoa bean shells, and granular activated carbon materials perform exceptionally well for the reduction of nitrate, atrazine, and alachlor. Granular activated carbon was expected to perform well, being a component of many conventional drinking water filtration systems. What was unexpected was the discovery that biomaterials such as hardwood chips and cocoa bean shells can perform as well, or better than, granular activated carbon, which could revolutionize water treatment technologies. From the soil column experiments, it also was determined that retention time does have a positive effect on the amount of nitrate that can be reduced by various filter media. Therefore, a material with a porosity that optimizes filtration rate and nitrate reduction ultimately will be the most useful material for this sort of application. Furthermore, the benefit of extended retention time could promote the implementation of conservation practices such as controlled drainage in tile-drained watersheds.
The beaker experiments proved that biological activity is at least partially responsible for nitrate reduction. The possibility of other factors (soil organic matter, moisture content, etc.) contributing to nitrate reduction cannot be ruled out at this point, but it is clear that there is some biological degradation occurring. This was discovered when the materials that were re-inoculated with indigenous soil bacteria showed a much greater reduction in nitrate than the materials that had been sterilized of all microorganisms.
Additionally, the beaker experiments confirmed the findings of Davidson (2005), showing that nitrate is significantly reduced in the presence of atrazine and alachlor. This finding could have serious implications for agricultural producers, considering that atrazine and alachlor could potentially render fertilizers useless if applied in close time proximity of these pesticides.
The qualitative benefits to society, economic prosperity, and environmental sustainability are significant and numerous if one carefully looks at the results of this research. Our research is important because it helps improve the sustainability of current farming practices without reducing much-needed agricultural production. The results show that naturally available, renewable resources, namely woodchips, are capable of reducing contaminants in subsurface drainage.
The outcomes of this research have obvious benefits and implications for society. Regardless of location, water quality is critical to the survival of all people on this planet. By reducing nitrogen, ammonia, alachlor, and atrazine concentrations, the health risks associated with ingesting these contaminants are reduced. Biofiltration also has great economic advantages. Providing agricultural producers with a tool to remove contaminants from discharge from their fields will reduce future regulatory cost. More importantly, the cost of the biofilter is relatively inexpensive and gives an alternative to much more expensive treatment systems that currently are being used.
The environmental benefits and implications of our findings are enormous. The biofilter is a naturally available resource that eliminates chemicals from water without introducing additional chemicals to the system. Furthermore, the biofilter is composed of biological material, typically waste products, which would need to be disposed of otherwise. The removal of agricultural chemicals from ground and surface water could help reduce excessive algal growth and oxygen depletion in surface waters. The increased oxygen levels and improved water quality would provide a much better habitat for aquatic life. Improved water quality also would improve the aesthetics of natural waters by reducing the odor and improving the appearance of the water due to less algae decay.