Date of Award
Dissertation - Restricted
Doctor of Philosophy (PhD)
Civil, Construction, and Environmental Engineering
Onsite wastewater treatment and disposal systems are used by approximately 25% of all housing units in the United States, with septic tank systems being most common. One of the environmental concerns associated with the use of septic tank systems is the potential for local and regional groundwater contamination. Nitrogen, which is typically not removed in conventional septic tank systems, is one of the most important contaminants associated with septic tank systems. Studies have directly linked nitrate-nitrogen with methemoglobinemia, a disease of concern to infants, and it may also be a carcinogen. In Wisconsin, the first statewide nitrate standard for discharge from private treatment systems was proposed in February of 1995. This research project was initiated to examine a modified septic tank system for nitrogen removal. The modified septic tank design used for this research utilized an attached growth column for nitrification and an anoxic reactor for denitrification. This septic tank design represents a relatively simple and potentially economic modification to traditional septic tank designs, yet has the potential to reduce nitrogen discharge to the levels proposed in Wisconsin.