title: Enhanced nitrogen removal with an onsite aerobic cyclic biological treatment unit.
abstract: Coastal Zone Act Reauthorization Amendments (CZARA, Section 6217) necessitate the requirement that onsite wastewater disposal units located near impaired surface waters or groundwater to provide at least 50% nitrogen removal. Approximately 38% of Hawaii households use onsite systems including septic tanks and cesspools that cannot meet this requirement. Upgrades to aerobic treatment units (ATUs) are a possible compliance solution. In Hawaii, ATUs must meet National Sanitation Foundation Standard 40 (NSF40) Class I effluent criteria. Previously, a multi-chamber, flow-through, combined attached/suspended growth type ATU (OESIS-750) and presently, a sequencing batch type ATU (CBT 0.8KF-210) were evaluated for NSF40 compliance, nutrient removal capability (NSF245), and adaptability for water reuse (NSF350). Both units easily achieved the NSF40 Class I effluent criteria. While the OESIS-750 achieved only 19% nitrogen removal, the CBT unit achieved 81% nitrogen removal, meeting the NSF245 criteria and CZARA requirements for applications in critical wastewater disposal areas. In addition, the CBT consistently produced effluent with turbidity less than 2 NTU (NSF350) and UVT254 greater than 70%, facilitating the production of unrestricted-use recycled water.
authors.affiliation: Department of Civil and Environmental Engineering, University of Hawaii at Manoa, 2540 Dole Street, Holmes # 383, Honolulu, HI 96822, USA E-mail: rbabcock@hawaii.edu.
authors.forename: Roger W
authors.initials: RW
authors.lastname: Babcock
authors.affiliation: US Navy, Department of the Navy, Washington, DC, USA.
authors.forename: Atiim
authors.initials: A
authors.lastname: Senthill
authors.affiliation: Hawaii Natural Energy Institute, University of Hawaii, 1680 East West Road, POST 109, Honolulu, Hawaii 96822, USA.
authors.forename: Krishna M
authors.initials: KM
authors.lastname: Lamichhane
authors.affiliation: Austin Tsutsumi & Associates, 501 Sumner St, Honolulu, HI 96817, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Agsalda
authors.affiliation: International Wastewater Technologies, 94-009 Waipahu Depot St # B, Waipahu, HI 96789, USA.
authors.forename: Glen D
authors.initials: GD
authors.lastname: Lindbo
mesh_terms: D000332:Aerobiosis; D019149:Bioreactors; D058440:Denitrification; D060587:Groundwater; D006254:Hawaii; D009584:Nitrogen / Q000737:chemistry*; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater
chemical_list: D009584:Nitrogen; D012722:Sewage; D062065:Wastewater