Developing an appropriate disinfection strategy for post-anaerobic membrane bioreactor effluent

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Project Description

The current approach to treat our wastewater relies heavily on aerobic-based treatment technologies and chlorination, both of which are energy intensive, costly and unintentionally introduce chemical contaminants to the final treated wastewater. Instead, we aim to implement anaerobic membrane bioreactor (AnMBR) to clean the municipal wastewater due to the various advantages associated with anaerobic processes (e.g. low energy demand, low sludge production and generates methane as an energy source). However, ammonia are not removed by anaerobic microorganisms and are typically retained after AnMBR treatment in the range of 20 to 50 mg/L. The presence of ammonia in the post-AnMBR effluent can be a double-edged sword. On one hand, it makes the effluent advantageous for direct use in agricultural irrigation since ammonia can be taken up by plants for growth. On the other hand, the water cannot be disinfected with chlorine to prevent microbial regrowth as the direct use of chlorine on such ammonia-rich waters will produce nitrogenous disinfection byproducts (e.g. N-nitroso NDMA), which have been shown to be carcinogenic and mutagenic. Considering the problems associated with chlorine, we therefore propose that post-AnMBR effluent be treated with UV/H2O2 (a form of advanced disinfection process) as a final disinfection. This study aims to optimize a UV/H2O2 plug flow reactor to disinfect post-AnMBR effluent. To achieve this, parameters such as reactor configuration, UV intensity, concentrations of hydrogen peroxide and contact time will be optimized. Turbidity of the post-AnMBR effluent will be monitored as increase in turbidity will result in poor UV efficacy due to light scattering and limited light penetration. pH will also be monitored as it affects the formation of nitrate and reactive oxygen species from H2O2. All parameters will be correlated with the log removal values of an appropriate tracer compound. This will allow one to determine the range of acceptable operating conditions and water quality permissible in a continuous UV/H2O2 system. Energy costs associated with the disinfection will be collated for techno-economic analysis of the system​​​​​​
Program - Environmental Science and Engineering
Division - Biological and Environmental Sciences and Engineering
Center Affiliation - Water Desalination and Reuse Center
Field of Study - ​Disinfection processes

About the
Researcher

Peiying Hong

Associate Professor, Environmental Science and Engineering

Peiying Hong
Professor Hong’s research interests include molecular microbiology and microbial aspects in water and wastewater ecosystems. Her research aims to understand the roles and interactions of microorganisms in these ecosystems, and to utilize the insights to solve issues related to water quality and water reuse. Professor Hong’s research also looks at the biotic contaminants (e.g. antibiotic resistance genes, mobile genetic elements, pathogens) that are present in the natural and engineered environments.

Desired Project Deliverables

​An optimized disinfection process for post-anaerobic membrane bioreactor effluent​