Traditional engineering models known as Activated Sludge Model (ASM) are commonly used for operation, design, and optimization of wastewater treatment plants. ASM is implemented in simulation platforms and predicts microbial growth with simulation and calibration of many model parameters which are bound to a range of experimental conditions. The model calibration values have been backed up by decades of expertise through experiments, observations, and applications.
Recently, a statistical physics-based theory, Microbial Transition State (MTS), was proposed to predict microbial growth which relies on fully elemental stoichiometry of biochemical reactions. ASM and MTS models has been tested for different scenarios and comparisons of key features. Basically, ASM predictions are based on empirical formula of Monod and requires calibrating a high number of parameters while MTS requires a smaller number of parameters. However, MTS has not been fully verified with proper experimental data on mixed microbial cultures such as those sustained in wastewater treatment systems. Additionally, conditions such as inhibition of growth by any pollutant compound originated from industrial processes has not been considered for validation of MTS theory yet.
Nitrification is one of the essential processes which takes place in aerobic treatment of wastewater. In this process, ammonia from domestic or industrial activities is converted to nitrite and nitrate by nitrifying bacteria. Nitrification process covers oxidation of ammonia to nitrite by Ammonia Oxidizing Bacteria (AOB). Nitrite is further utilized by Nitrite Oxidizing Bacteria (NOB) and converted to nitrate.
Heavy metal and pharmaceutical pollution have been emerging issues in recent years originating from industrial/domestic/hospital wastewater discharges, landfill leachates and agricultural applications. They threaten marine ecosystems and human health through food chain, bioaccumulation, and biomagnification.
This project is an intersection of environmental engineering, molecular biology and modeling where the main objective was to expand the use of energy-based MTS theory on design and control of wastewater treatment systems. For this purpose, nitrification process was focused. MTS was used for estimating microbial growth kinetics in before and after addition of pollutants from industrial wastewater. Metagenomic and metatranscriptomic tools were utilized for proper estimation of nitrification bacteria abundance and functional activity of microbial community.
