Currently there are no simple methods of removing pollutants from agricultural drainage water or fracking water. Wastewater from other sources is typically treated by expensive biological and/or chemical methods that also may have high energy requirements. SDSU anticipates that this invention will solve currently un-addressed problems with agricultural drainage water and fracking water in a low cost and low energy input process.
This method is simple, easily scalable, readily deployable and will use a widely available, biodegradable raw material as the substrate. These same advantages should allow this technology to compete with currently used methods of treating agricultural, municipal and industrial wastewater. For cleanup of sub-surface agricultural drainage water a box containing biochar (BC) or biochar based activated biochar (BAC) could be placed on the end of the drainage lines so that as the drainage water passes through the BC or BAC the chemicals in the water would be trapped. A simple companion test could be developed to determine when the BC or BAC was saturated with chemicals and needed to be changed out, such as a simple colorimetric nitrogen test. The biochar could then be placed into the soil to slowly release the nutrients for plant growth. The biochar itself would aid in building soil carbon. For treatment of fracking water, a similar type of system could be developed. The ultimate use of the fully adsorbed biochar would likely be different. Due to the petrochemicals adsorbed, it would be more environmentally sound to combust the used biochar to recover energy, while releasing CO2 and water vapor.
A broad range of applications could be exploited by this technology for the purpose of cleansing water of pollutants.
- Agricultural drainage water from tiling is known to contain nutrients and in some cases herbicides and pesticides. This agricultural runoff is known to cause the "dead zone" in the Gulf of Mexico, and a solution to cleanse this drainage water before it enters streams would be valuable.
- Fracking is a process in which water mixed with certain chemicals is pumped underground under high pressures to fracture the oil-bearing substratum and push out the oil. Fracking water thus contains both the chemicals added to is, along with components from the oil and substratum. Use of fracking is rapidly expanding, but adverse effects are now being noted. In fact, many localities are now considering regulation of this industry, as it pollutes surface and ground waters. Biochar may also find application of cleanup of other types of agricultural, municipal or industrial wastewaters.