Modeling of extracellular polymeric substances and soluble microbial products production in a submerged membrane bioreactor at various SRTs

Abstract

Extracelluar polymeric substances (EPSs) and soluble microbial products (SMPs) produced by microbial cultures involved in membrane biofouling have been widely investigated. A mathematical model of EPS and SMP formation and degradation was established based on the activated sludge model no. 1 (ASM1) and was applied to the membrane bioreactor sludge with different sludge retention times (SRTs). The unified theory that the distinct products from the EPS and SMP overlapped each other was integrated into the ASM1. Two components, five processes and eight parameters were newly added to set up the model. To increase the accuracy of model simulation, microbial kinetic parameters were determined by respirometry method and applied to the model instead of microbial kinetic constant offered in ASM1. From the respirometry result, both of heterotroph and autotroph showed different yield value, growth rate and decay rate from activated sludge. There was no significant effect of SRT on SMP production and the experimental results showed good agreement with the predicted values by the model simulation. With the developed unified EPS and SMP model, EPS and SMP production could be simulated so well that it can be applied for the membrane biofouling control.

Development of a Comprehensive Fouling Model for a Rotating Membrane Bioreactor System Treating Wastewater

“…The true origin of fouling has yet to be fully defined, although many researchers widely acknowledge that SMP (soluble microbial products) and EPS (extracellular polymeric substances) are the most likely fouling agents [12]. This is since the build-up of SMP and EPS can cause reduction in membrane permeability [13,14]. Additional factors affecting fouling mechanisms include; Scaling, biofilm formation, operating conditions such as pH, temperature and flow rates, solution properties such as particle size distribution [12].…”

High Mineral Content of Biomass: Implications for Advanced Wastewater Treatment Through Hydrogen-Driven Denitrification

“…The biomass characteristics have been recently studied at high sludge retention times (SRT) (Masse 2006, Pollice et al2004, Rosenberg et al2002 with the aim of maintaining high MLSS concentration and low sludge production. Some researchers state that EPS concentration decreases when SRT increases (Chang et al, 1998, Cho et al,2004, whereas other studies show exactly reverse trend (Ng and Hermanowicz 2005,Ahn et al, 2006, Murthy et all., 1998 or no significant change in EPS (Liao et al, 2001.The lysis constituents and most of the components of EPS matrix is negatively charged , contributing to the negative charge of the activated sludge. As the result, among others potential functions such as nutrient accumulation, water retention, EPS are responsible for accumulation of metal ions (Moran and Ljung, 2003).…”

Soluble microbial products (SMPs) release in activated sludge systems: a review

“…Many researchers tried to improve the activated sludge models by adding SMPs components into ASM1 and ASM3, and also by integrating the extracellular polymeric substances (EPSs) into ASM1 model [7-10]. …”

“…[4] extended ASM3 model to ASM3-SMP with taking into account the concept of simultaneous storage and growth of SMPs by considering two components: Utilization associated product (S UAP ) and Biomass associated products (S BAP ). However, all of them (except [4,7]) used parameters directly taken from literature derived from activated sludge systems or even biofilm systems.…”