Characterizing the Performance and Operational Characteristics of the Bioreactors at the Detroit, Michigan, Water Resource Recovery Facility
Faculty advisor: Glen T. Daigger
PhD student: Cheng Yang
Master’s students: Ross Vander Meulen, Tong Yu, Yuewei Liu, Zheyi Tian, Jin Yan
The Great Lakes Water Authority (GLWA) Water Resource Recovery Facility (WRRF) is one of the largest in the world. Serving 2.4 million residents in Southeast Michigan, the facility provides primary and secondary treatment with phosphorus removal for sanitary and combined sewage up to 3,560,000 m3/day (940 mgd). The liquid process treatment train consists of influent pumping and preliminary treatment (screening and grit removal), conventional primary treatment with ferric chloride addition, a high purity oxygen (HPO) activated sludge process, and effluent disinfection.
Excessive phosphorus in waterways causes harmful algae blooms, a side effect of eutrophication, and water quality deterioration. Thus, the control of phosphorus in WRRF effluents is essential to both environmental and human health. Phosphorus removal by WRRFs is accomplished by converting soluble phosphorus to particulate phosphorus and subsequent removal of that particulate matter. This can be accomplished by both chemical and biological means. Chemical precipitation is used to remove the inorganic forms of phosphate by the addition of a metal salt (iron or aluminum), while the configuration of an activated sludge system can lead to conditions where a biological population develops that is capable of removing phosphate to levels beyond that simply required for biomass synthesis.
The objective of this project is to characterize and better understand the chemical and biological phosphorus removal occurring at the GLWA WRRF. Chemical addition for phosphorus removal results in costs for chemical purchase and additional sludge that must be processed, while operation of the bioreactors represents a significant cost for electricity and pure oxygen purchase. Better understanding the interaction between biological and chemical phosphorus removal can, thus, provide the basis for improved plant performance and cost reduction.
Biological Phosphorus Removal Bench-Scale Testing at the Great Lakes Water Authority (GLWA) Water Resource Recovery Facility (WRRF), Detroit, Michigan
Faculty advisor: Glen T. Daigger
Master’s students: Ross Vander Meulen, Chaoqun Cheng
Following on initial work at the Great Lakes Water Authority (GLWA) Water Resource Recovery Facility (WRRF), bench-scale testing is being conducted using GLWA primary effluent without ferric chloride added to assess the full bio-P capacity potentially available for the existing secondary treatment system. GLWA is also running pilot tests on anaerobic digestion of waste sludges (primary, WAS, and imported organic matter), and conversion to full bio-P would significantly affect such a system. A process model of the GLWA liquid treatment process as part of the previous U-M research can be extended to include solids processing options, including the current system and various anaerobic digestion options including phosphorus recovery, to assist GLWA to understand the impacts of potential process modifications. Thus, the objectives of this research are to:
- 1. Determine the bio-P capacity of a biological process representing conversion of the existing HPO activated sludge process to bio-P and receiving primary effluent without upstream ferric chloride addition.
- 2. In collaboration with on-going anaerobic digestion research on-going at the GLWA WRRF, characterize the anaerobic digestability of the produced bio-P WAS using bio-methane formation potential (BMP) techniques.
- 3. Update the existing GLWA WRRF process model to incorporate bio-P with and without ferric chloride addition and solids processing options, including anaerobic digestion, and including impacts of solids handling recycle streams on plant performance.