Nutrient and Pathogen Removal with an Innovative Passive Underground Drainfield for On-site Wastewater Treatment

When urban regions gradually expand due to regional development, centralized sewage collection, treatment, and disposal is often unavailable for both geographic and economic reasons. As a consequence, about a quarter of the residences in the United States relied on decentralized treatment of wastewater. Household wastewater contains high concentration of nutrients (mainly nitrogen and phosphorus), disease-causing organisms and viruses, and some toxic chemicals. Nation wide, wastewater effluent from on-site wastewater treatment (OWTS) can represent a large fraction of nutrient loads to groundwater aquifers. Phosphorus and nitrogen compounds are the most frequent measurements to indicate nutrient loadings. Some aquifers may discharge into springs or other surface waters adversely affecting public health. Hence, on-site wastewater effluent disposal has contributed significant adverse impacts to the dynamics of the natural environment. Nowadays, due to widespread septic tank failure, scientists, engineers, and manufacturers in the wastewater treatment industry have developed a wide range of alternative passive technologies designed to address increasing hydraulic loads, energy saving requirement, and water contamination by nutrients and pathogens in OWTS. This paper aims to present an innovative design of the underground drainfield with soil amendments (sorption media) in a pilot septic tank system. The new system located at the OWTS test center, University of Central Florida (UCF) was tested and proved costeffective in the initial test run in fall 2008.