Integration of aquatic chemistry with bio-process models

Project code: K5/2125

April 2012 – June 2014

Lead Organisation: WASH R&D Centre (as the PRG)

Partner organisations: eThekwini Water and Sanitation; University of Cape Town (Department of Civil Engineering); University of Queensland; Umgeni Water; University Laval (Dept of Water and Wastewater Engineering); Sasol Technologies; CEIT - Centro de Estudios e Investigaciones Técnicas de Gipuzko, Spain; Paper Manufacturers of South Africa

Project webpage: N/A

Project summary

In April 2012, the WRC awarded the WASH R&D Centre (as the Pollution Research Group) to lead a multi-partner investigation and development project into The Integration of Aquatic Chemistry with Bio-process Models. This project derives from a special task-force put together by the International Water Association (IWA) for developing a physicochemical framework for modelling water and wastewater processes. Wastewater treatment models are increasingly being used for the design and improvement of public facilities as well as industrial installations, which affect the water environment. However, there is a significant shortage of researchers who understand aquatic chemistry in water and wastewater systems, and therefore demonstrate limited capacity in using these treatment models. The overall objective of this project is to develop learning and training materials on aquatic chemistry and physicochemical aquatic and bio-process wastewater treatment models. 

A substantial part of the project involves the transfer of technology already developed by previous projects and which incorporate the principles of the IWA task group. Case studies are being undertaken to demonstrate the application of the models to local wastewater treatment systems, including: 

  1. An application of the UCTADM2 anaerobic digestion model, developed by University of Cape Town under WRC K5/1822, to predict the impact of high strength industrial waste on the methane production, effluent COD and digester stability, in connection with WRC K5/2001 “Co-digestion of sewage sludge and industrial concentrates.” 
  2. An existing project on the optimisation of paper mill water circuits, supported by PAMSA, will provide local data for testing the application of paper mill water circuits model developed by CEIT. 
  3. An existing project on the modelling of anaerobic digestion of Sasol effluent will provide data on a system which is very different from standard municipal treatment conditions. This will use a modified version of the UCTADM2 model. 
  4. A further investigation of novel processes being developed by Professor Ekama of UCT, for treating highly saline sewage resulting from using seawater as sewage carriers.
  5. An investigation into the capacity of biomass for proton exchange and metal complexation, as part of a programme to establish titration methods to characterise anaerobic digestion streams being undertaken as part of the WRC K5/2001 co-digestion project.

 

In addition to the case studies, course material on aquatic chemistry and physicochemical processes is amassed below and expanded upon for the purposes of establishing a training workshop and post-graduate level course.

Publications and Media

Published papers

Conference papers and presentations

Van Zyl, P.J., Lees, C.M., Brouckaert, C.J., Ekama, G.A., and Foxon, K.M., 2012. Dynamic Modelling of Anaerobic Digestion of Fischer-Tropsch Reaction Water: Different Approaches to Physico-chemical Modelling. Paper presented at the 3rd IWA/WEF Wastewater Treatment Modelling Seminar. Mont-Sainte-Anne, Quebec, Canada. February 26-28 2012

Course Material

Motivation

At both the global and the national scale, as the population grows and becomes increasingly urbanized, and as the demand for natural resources to meet the needs of the population increases, efficient waste management is essential to protect both the environment and public health, and as a potential alternate energy source.

Advanced process modelling is increasingly being used to design and optimize the operation of wastewater treatment plants. Both bio-process modelling and aquatic chemistry modelling are mature technologies, however up to now they have not been well integrated with each other. A number of physico-chemical processes, specifically acid base reactions, gas transfer and precipitation, are known to play an important role in biological wastewater treatment processes, but are not always adequately represented in current wastewater treatment models, in particular the International Water Association (IWA) ASM (activated sludge) and ADM (anaerobic digestion) models series. There is furthermore a shortage of researchers with a deep understanding of aquatic chemistry in the context of water and wastewater treatment.

The course materials and models provided here were developed by the University of KwaZulu-Natal’s Pollution Research Group in collaboration with the University of Cape Town’s Water Research Group and the IWA Task Group on a Generalised Physico-chemical Modelling Framework for Water and Wastewater Treatment Processes. Funding was provided by the South African Water Research Commission (WRC) under WRC Project K5/2125 Integration of Aquatic Chemistry with Bio-Process Models.

Target Audience

Researchers, modelling practitioners, lecturers and post-graduate students in bio-process modelling.

Aims of the course

  1. Provide bio-process modelers with a basic understanding of speciation chemistry and its relevance to bio-process models
  2. Provide a general framework for the integration of physico-chemical processes into bio-process models
  3. Provide practical examples of the application of the integrated modeling approach in the form of case studies
  4. Provide worked examples and exercises which allow the students to explore and develop a better understanding of the important underlying issues.
  5. Provide a set of modeling tools which researchers can adapt to their own particular models.

Material

Learning Objectives

On completion of the course, students should:

  1. Have developed a sound understanding of speciation chemistry, non-ideal solution effects and concepts such as total and speciated alkalinity.
  2. Understand the various weak acid base systems which are important in wastewater treatment modelling.
  3. Understand the role of CO2 gas evolution in regulating the pH of anaerobic digesters.
  4. Be able to select an appropriate set of model components for their system and to add new components and species to the speciation sub-routine if necessary.
  5. Be able to formulate the stoichiometric equations, the coefficients of which appear in the Gujer matrix, in terms of the speciation model components.
  6. Be able to correctly link the algebraic equilibrium speciation sub-routine to a differential material balance or steady state rate controlled process model.
  7. Be able to add a gas phase to a process model with the appropriate kinetic and equilibrium relationships for each gas species.

Terms of use

The materials provided on this group space may be freely downloaded for teaching, self-study and research purposes provided that all copyright and other proprietary notices displayed in the materials are retained. They may be presented in whole or part in any course or workshop or integrated into other courses on bio-process modelling. All materials remain copyright to the South African Water Research Commission unless otherwise stated and may not be used for any commercial purpose Documents are provided as secure pdfs which cannot be edited.

Browsing and downloading materials from this group space is undertaken entirely at your own risk. The authors, the South African Water Research Commission, University of KwaZulu-Natal and University of Cape Town assume no responsibility or liability for errors or omissions in the material provided or for, any damages to, or viruses that may infect, your computer equipment or other property on account of your access to, use of, or browsing in the Site or your downloading of any materials, data, text, images, video, or audio from the Site. For more details see the WRC Terms and Conditions web page.

Contact us

Comments, questions and suggestions are welcome.

Chris Brouckaert, Senior Research Fellow [BROUCKAE@ukzn.ac.za]

Bio

Barbara Brouckaert, Researcher