Publication | Closed Access
Nitrogen Transformations During Subsurface Disposal of Septic Tank Effluent in Sands: I. Soil Transformations
70
Citations
0
References
1973
Year
EngineeringWaste TreatmentSeepage BedsSubsurface DisposalWastewater TreatmentSoil BiochemistryOrganic GeochemistryEnvironmental ChemistryBioremediationEnvironmental MicrobiologyOrganic NSoil TransformationsNitrogen TransformationsSoil GasBiogeochemistryAmmoniaWaste ManagementEstuarine GeochemistryEffluent DisposalEnvironmental EngineeringEnvironmental RemediationInfiltration RatesGroundwater Remediation
Abstract Soil physical and chemical studies of five subsurface septic tank seepage beds were conducted to determine the biochemical transformations of N and thereby its potential for ground‐water pollution. Effluent was found to be ponded in all the seepage beds examined due to the presence of an impeding layer, a “crust”, at the boundary between the gravel bed and adjacent soil. The crust reduced infiltration rates approximately from 500 to 8 cm/day. Soil atmospheric composition 5 cm below the crust averaged 19.6% O 2 and 0.66% CO 2 . Nitrogen in the septic tank effluent occurred as NH 4 ‐N (80%) and organic N (20%) with virtually no NO 3 ‐N. Organic‐N was largely concentrated in the crust zone. Nitrification of NH 4 ‐N to NO 3 ‐N was essentially complete and commenced in the unsaturated subcrust soil within about 2 cm of the crust. Nitrification did not occur and NH 4 ‐N was absorbed by the soil below a seepage bed that was submerged in the ground water.