STUDIES ON CONTAMINANT BIODEGRADATION IN SLURRY, WAFER, AND COMPACTEDSOIL TUBE REACTORS

A systematic experimental approach is presented to quantitatively eval uate biodegradation rates in intact soil systems. Knowledge of bioreme diation rates in intact soil systems is important for evaluating the e fficacy of in-situ biodegradation and approaches for enhancing degrada tion rates. The approach involves three types of soil bioreactors: slu rry, wafer, and porous tube. In the soil slurry reactor, biodegradatio n occurs in the aqueous phase by suspended and soil-immobilized microo rganisms. In the soil wafer reactor, diffusivity of contaminant in the soil matrix controls the biodegradation rate. In the porous tube reac tor, oxygen limitations occur inside the tube due to diffusional resis tances, and oxygen consumption occurs due to biodegradation. Measureme nt of cumulative oxygen uptake in soil slurry, wafer, and porous tube reactors are used to determine biokinetics and transport parameters. I t is shown that biodegradation rates in intact soil systems are slower than in soil slurry reactors. Furthermore, soil tube reactors in conj unction with respirometry can be used to assess bioremediation rates i n intact soil systems.