Algal-bacterial consortia for nitrogen removal from wastewater

93 Pages·2015·3.05 MB·English

Master’s dissertation submitted in partial fulfilment of the requirements for the joint degree of

International Master of Science
in Environmental Technology and Engineering

an Erasmus+: Erasmus Mundus Master Course jointly organized by
Ghent University, Belgium
University of Chemistry and Technology, Prague, Czech Republic
UNESCO-IHE Institute for Water Education, Delft, the Netherlands

Academic year 2013 – 2015

Algal-bacterial consortia for nitrogen removal from
wastewater: Experimental and modeling studies

Host University:
UNESCO-IHE Institute for Water Education, Delft, The Netherlands
University of South Florida, USA

Larissa Terumi Arashiro
Promoter: Prof. Dr. Piet Lens
Co-promoter: Prof. Dr. Sarina Ergas

This thesis was elaborated at UNESCO-IHE Institute for Water Education and University of South
Florida and defended at UNESCO-IHE Institute for Water Education within the framework of the
European Erasmus Mundus Programme “Erasmus Mundus International Master of Science in
Environmental Technology and Engineering " (Course N° 2011-0172)

© 2015 Delft, Larissa Terumi Arashiro, Ghent University, all rights reserved.
Algal-bacterial consortia for
nitrogen removal from wastewater:
Experimental and modeling studies

Larissa Terumi Arashiro

MSc Thesis

August 2015

Algal-bacterial consortia for nitrogen removal from
wastewater: Experimental and modeling studies

Master of Science Thesis
by

Larissa Terumi Arashiro

Supervisors
Prof. Dr. Piet Lens
Prof. Dr. Sarina J. Ergas

Mentors
Dr. Peter van der Steen
Dr. Meng Wang
Angelica Rada Ariza (MSc)
Examination committee
Prof. Dr. Piet Lens
Prof. Dr. Sarina J. Ergas
Dr. Peter van der Steen
Dr. Carlos M. Lopez Vazquez
Dr. Marcel Janssen
Angelica Rada Ariza (MSc)

Delft, NL and Tampa-FL, USA
August 2015

Although the author and UNESCO-IHE Institute for Water Education have made every effort to ensure that
the information in this thesis was correct at press time, the author and UNESCO-IHE do not assume and
hereby disclaim any liability to any party for any loss, damage, or disruption caused by errors or omissions,
whether such errors or omissions result from negligence, accident, or any other cause.

©2015 by Larissa Terumi Arashiro.
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Abstract
In the past decades, several models have been developed to describe nitrogen removal from wastewater.
Most of these models are based on activated sludge systems or photosynthetic organisms, such as algae and
plants, which are known to be efficient in nutrients uptake. However, there is a lack of models describing
the interactions in combined algal-bacterial systems. This research proposes a model to describe the
nitrogen removal processes in photobioreactors (PBRs) treating wastewater with an algal-bacterial
consortium.
The Activated Sludge Model no. 3 (ASM3) was used as base model to represent the bacterial activity.
Additionally, algae growth processes based on the ammonium as nitrogen source and light intensity were
incorporated into the proposed model.
Experimental studies were carried out to obtain data for the model calibration. The laboratory research was
focused on the nitrogen removal processes from an anaerobically digested swine manure wastewater with
high ammonium concentration (264 mgNH +-N/L). The influence of biomass density, as measured by the
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total suspended solids (TSS) concentration on the light attenuation in completely mixed PBRs was
observed by comparing the performance of two reactors operated with different TSS concentrations. Thus,
the applicability of the light intensity factor incorporated in the algae growth process could be also
evaluated.
The completed forms of mathematical equations were implemented into the software AQUASIM, which is
a computer program for the identification and simulation of aquatic systems. The model calibration was
done with the experimental data from this work. Further calibrations were performed with data obtained
from previous studies using algal-bacterial consortia for nitrogen removal under different conditions. The
model simulations mostly followed similar pattern as the empirical data. The model presented relatively
good fit for nitrogen removal from both real and artificial wastewater. The light attenuation influence was
also accounted for the model and indicated effective influence in the processes inside the PBRs. However,
there are still some improvements needed on the model structure in order to make it more accurate and
realistic.
The proposed model can help in the evaluation of nitrogen removal dynamics and promote a better
understanding regarding the interactions between algae and bacteria. This tool can be potentially useful to
predict the most relevant conditions that enrich or restrict processes, as well as to design and optimize the
operations in nitrogen removal from wastewater using algal-bacterial consortia.

Keywords: model; nitrogen removal; light attenuation; swine manure; algae; bacteria.
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Acknowledgements
Firstly, I would like to express my special appreciation to my supervisors Prof. Dr. Piet Lens and Prof. Dr.
Sarina J. Ergas. It was a pleasure to learn from and cooperate with two experts in their respective fields. I
am extremely grateful for your trust in me by giving me the opportunity to carry out my research under
your guidance in Unesco-IHE and USF. I really appreciate your advices, suggestions and support during
my thesis period.
This paper could not have been written to its fullest without my mentors in Unesco-IHE, Dr. Peter van der
Steen and Angelica Rada, who challenged and inspired me throughout my entire thesis time. You both have
been essential for the development of this research. I am eternally thankful for all the effort and patience
during your guidance and for encouraging my work.
I would also like to express my gratitude to my mentor in USF, Dr. Meng Wang, who guided me during my
laboratory experiments and supported my journey in Florida. Without your precious help, I would not have
been able to successfully complete my experiments.
A special thanks to my family. Words cannot express how grateful I am to always have you by my side
regardless of everything else. I deeply appreciate your belief in me and this is what has sustained me thus
far.
Last but not least, I would like to express my warm thanks to all my friends. Your support and care helped
me to overcome setbacks and keep strong to strive towards my goal.

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Table of Contents

Abstract vii
Acknowledgements viii
List of Figures xii
List of Tables xiv
List of Symbols xv
1. Introduction 1
1.1. Background 1
1.2. Problem statement 1
1.3. Research questions 2
1.4. Objectives 3
2. Literature Review 4
2.1. Microalgae 4
2.1.1. Characteristics of microalgae 4
2.1.2. Factors affecting microalgae growth 4
2.2. Biological nitrogen removal 7
2.2.1. Microalgal and bacterial nitrogen uptake for biosynthesis 7
2.2.2. Nitrification-denitrification process 7
2.2.3. Nitritation-denitritation process 8
2.3. Microalgal-bacterial consortia 9
2.3.1. Interaction between algae and bacteria 9
2.3.2. Practical research 10
2.4. Modeling bioreactor processes 10
2.4.1. Activated sludge models (ASM) 10
2.4.2. Algae systems models 12
2.4.3. Algae-bacteria systems models 13
3. Methodology 15
3.1. Algal-bacterial modeling 15
3.1.1. Model structure 15
3.1.2. Elaboration of phototrophic processes 16
3.1.3. Model variables, coefficients and parameters 18
3.1.4. Determination of model component values 18
3.1.5. Assumptions considered in the model 18
3.2. Experimental studies 19
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