Abstract: Biotreatment of Produced Water Using Green Plants and Hydroponics

Ray R. Hinchman, M. Christine Negri, Donald O. Johnson

Produced water is a usually saline wastewater that is brought to the surface along with the gas from natural gas wells. Its constituents, although acquired naturally, are considered to be contaminants. This project investigated simple, low-cost biological systems using green plants to clean wastewater through biological filtering and sequestration (phytoremediation), and reduce its volume through enhanced evapotranspiration. These plant bioreactors incorporate hydroponic techniques and use natural saline wetland ecosystems as a model. A literature survey was conducted to develop an extensive database of candidate species having attributes appropriate for use in plant bioreactors (salt tolerance and high transpiration rates). In greenhouse studies, detailed experimental data on transpi ation rates, salt tolerance, nutrient requirements, and maximum salt concentration at which effective transpiration occurs has been generated for 6 candidate species. For all species tested, the mean evapotranspiration rates were consistently above the open-water evaporation rates at least up to a concentration of 2% salt in the nutrient solution, and for several species this higher rate was maintained to salinities above 6%. These data indicate that the ideal bioreactor plant will be a large, vigorous salt tolerant species with a large surface area of transpiring tissue and a dense, fibrous root system that can function as a biological filter. Ongoing experiments are evaluating promising component processes and plant species. A model batch processing bioreactor has been developed that s mulates field installations. This research is funded by The Gas Research Institute, Chicago, IL.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994