WRRCTR No.7 Infiltration and Percolation Studies of Sulfides and Sewage Carbonaceous Matter

Abstract

The laboratory study of the infiltration and percolation of sulfides and sewage carbonaceous matter was conducted in two phases: Phase I utilized simulated cesspool lysimeters and Phase II considered the generation of sulfides and the infiltration and percolation of sulfides through soil and sand columns. Results from Phase I dictated a need for further study owing to free percolation of certain odorous compounds and excellent COD removals under presumably anaerobic conditions contrary to findings of similar studies in the literature. In Phase II the soil column was more effective for sulfide removal than the sand column which allowed continuous breakthrough of an odorous percolate. Organic removal indicated by TOC, COD, and BOD under anaerobic conditions was insignificant with BOD data indicating an increase in organics during percolation. The progressive movement of a black precipitate through the sand bed indicated that the filtering action of the sand was not as effective as the soil column. Under acid conditions, sulfide breakthrough was clearly demonstrated in both the sand and soil columns. The flow rate significantly improved in both columns after percolation of acidified fluids. All columns exhibited the characteristic non-linear relationship between filtration and percolation rates and the hydraulic gradient. The results of the flow study can be described by the relationship of Hansbo (1960): V = λi^n where V = velocity, i = hydraulic gradient, n = constant and λ = constant describing permeability.