GOALI: WERF: Bioaugmentation of activated sludge with high activity nitrifying granules/flocs: population selection, survival, biokinetics

University Of Washington, Seattle WA

Investigators

Abstract

1603707 Stensel Municipal wastewater treatment plants are faced with new goals for nitrogen removal that are difficult to meet with limited space in urban areas. In cooperation with the DC Water (Washington DC), as well as King County (KC, Seattle) and Los Angeles County (LAC) water treatment facilities, the PIs intend to demonstrate and develop fundamental design information for an innovative bioaugmentation technology that meets high nitrogen removal standards and greatly reduces space, capital cost, energy, and chemical requirements. The proposed project examines ways to reduce operating costs for nitrogen removal using both pilot plant (at the participating plants) and lab-scale testing. Two systems are proposed. System I (operated at KC and LAC) develops nitritation granular sludge from sidestream centrate treatment that is added to the mainstream process. Granular sludge is a new type of round shaped dense rapid settling biomass of 1.0 to 3.0 mm diameter, resulting in bioreactors with greatly reduced area in contrast to conventional processes with lighter, less dense flocculent sludge, process intensification. The ability to uncouple the sludge retention time of the granules and flocculent sludge (selective retention) provides a long sludge retention time to increase the volumetric nitrification capacity of the mainstream significantly due to the high solids concentration of dense granules. Granular sludge bioreactors have contributed to a wastewater treatment revolution in Europe but are not yet implemented in the US, partly because aerobic granular sludge technology cannot be readily adapted to most existing activated sludge process reactor geometries. System II (operated at DC water) provides an enriched high activity nitritation floc from the cyclone separation overflow from a sidestream anammox process, which is fed to the mainstream to also intensify the volumetric nitrification capacity and promote a nitrite shunt in the main plant. Bioaugmentation of nitritation flocs and granules will enable the PIs to intensify existing infrastructure and achieve higher efficiency in given space, while reducing oxygen and carbon demands. The granular and flocculent biomass microbial populations and their survival and fate will be followed by molecular tools, fundamental biokinetic tests and process simulation models. The proposed work advances transformational innovative biological treatment methods and a deeper understanding of the microbial selection principles of ammonium and nitrite oxidizing bacteria in bioaugmented systems. It will be unique in combining population dynamics, identity, and kinetic parameters of granules and flocs with the ultimate goal to engineer an effective compact short cut nitrogen removal process. An innovative feature is increasing the volumetric nitrification capacity without increasing tank volume by growing high activity nitrifiers (granules/flocs) in a side reactor and to then seed the mainstream treatment to increase the nitrifying biomass density and volumetric capacity. This project enhances infrastructure for research and education in environmental engineering by exposing students to granular sludge technology. The results will be broadly disseminated by presentations at conferences. The PIs will reach underrepresented groups at the K-12 and undergraduate level through the minority science and engineering program, and the mathematics, science, engineering achievement program. This program has a strong history of bringing minority students on campus for extended program for faculty lectures and laboratory visits in which the PIs have participated.