A simple elemental continuity based model application to study the anaerobic microbial activity for the treatment of dairy manure

A simple anaerobic digestion (AD) model was formulated with emphasis on understanding the microbial activity during AD. The model was formulated according to two main rules that regulate the microbial growth. The first rule was maintaining the elemental continuity of macronutrients C, H, N, O, P, and S. The second rule satisfied the thermodynamics of the main AD catabolic reactions: acidogenesis and both acetotrophic and hydrogenotrophic methanogenesis. Accordingly, the stoichiometric parameters were evaluated as functions of the bacterial yield. The model also considered the enzymatic hydrolysis of solid waste. For a known solid waste composition, experimental data was utilized to estimate microbial initial concentrations, yields and kinetics, i.e., to achieve better understanding of the main AD microbial activity. The model was applied to three sets of batch experiments focusing on anaerobic dairy manure degradation. The model predicted the degradation dynamics, estimated the bacterial concentration in different inoculums, and evaluated the effect of inoculum ratios in speeding up the degradation. Elemental continuity based formulation of the model evaluated additional components that are necessary for future studies of macronutrients recovery, limitation/toxic effects, and chemical equilibrium

Automatic initialisation of buffer composition estimation for on-line analysis of unknown buffer solutions

An automatic initialisation procedure for extracting useful information about buffer composition from a titration experiment is presented in this paper. The initialisation procedure identifies which buffering components are present in the sample from a relatively long list of buffers expected in the system monitored. The procedure determines approximate pK(a) values of the buffers and evaluates their maximum and minimum concentrations. This information is then used to start an optimisation procedure to fit the model of the buffer components to the titration data and to accurately determine buffer concentrations and pKa values. The procedure has been integrated as a software layer around the buffer capacity optimum model builder (BOMB) that fits a buffer-capacity model to a measured buffer-capacity curve to estimate model properties (pKa values and concentrations). The reliability and robustness of the resulting buffer capacity software (BCS) were tested using a titrimetric analyser simulator (TAS). The BCS was then validated off-line and on-line

Titrimetric monitoring of anaerobic digestion: VFA, alkalinities and more

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Implementation of anaerobic digestion models for plant wide modelling and performance benchmarking

Abstract Integration of Anaerobic Digestion Model (ADM) with the standard Activated Sludge Models (ASMs) is introduced for plant wide application. A flexible methodology is presented through an example in which the standard benchmark model of activated sludge systems is extended with an anaerobic digestion unit. To simulate the practice of sludge treatment in this example, two process units are added and configured to act as thickener and centrifuge before and after digestion respectively. To increase flexibility for further application two interfaces between activated sludge and digester model components are created. The structure of the transformers is briefly described. Results of the benchmark simulation are shown to highlight the effect of supernatant recycling

DYNAMIC MODELING OF THE ACTIVATED SLUDGE PROCESS FOR REAL TIME MONITORING AND CONTROL

In this paper, a dynamic model of the activated sludge process is formulated. The model is implemented in a modular hierarchical structure. Different biological reactions for COD removal, nitrification and denitrification are arranged in cascade and are active depending on the operation conditions. The implementation suits real time monitoring and control of the process. The implementation is configured to a very large plant to study its possible control strategies

Implementation Of Anaerobic Digestion Models For Plant Wide Modeling And Performance . . .

Integration of Anaerobic Digestion Model (ADM) with the standard Activated Sludge Models (ASMs) is introduced for plant wide application. A flexible methodology is presented through an example in which the standard benchmark model of activated sludge systems is extended with an anaerobic digestion unit. To simulate the practice of sludge treatment in this example, two process units are added and configured to act as thickener and centrifuge before and after digestion respectively. To increase flexibility for further application two interfaces between activated sludge and digester model components are created. The structure of the transformers is briefly described. Results of the benchmark simulation are shown to highlight the effect of supernatant recycling

Titrimetric monitoring of a completely autotrophic nitrogen removal process

Fully autotrophic nitrogen removal processes, such as the combined SHARON-Anammox process, help to improve the sustainability of wastewater treatment. Successful operation of such a completely autotrophic system is, among others, based on the strict control of the SHARON reactor in order to produce an Anammox-suited influent with a 1:1 ammonium:nitrite ratio. The high quality and high frequency measurements provided by a titrimetric set-up measuring the total ammonium (TAN) and total nitrite (TNO2) concentrations facilitate this control considerably. In this study, the use of a titrimetric set-up for monitoring the combined SHARON-Anammox process is investigated. The technique that interprets on-line collected titration curves was applied to a lab-scale system. Comparison with classic colorimetric results gave statistically indistinguishable results for TAN and TNO2 concentrations in the SHARON reactor. In the Anammox reactor, only TAN could be determined by the investigated method due to the very low TNO2 concentrations. Phosphate, a potential inhibitor of the Anammox process, is available as an additional measurement in the effluent of the SHARON reactor. Three measurements are thus combined in one single instrument. The proposed measuring technique holds different advantages over the other TAN and TNO2 measurement techniques such as on-site availability, easy automation, the absence of the need for high dilutions and cost reduction