Anaerobic Nitrogen Removal

89 Pages·2017·1.95 MB·English

Tiago Emanuel do Espírito Santo Bernardo

Bachelor of Science in Chemical and Biochemical Engineering

Anaerobic Nitrogen Removal: The
start-up of an Anammox Reactor with
pre-treated Real wastewater from the
Anaerobic Digestion of municipal solid
waste.

Dissertation to obtain the degree of Masters in Chemical and
Biochemical Engineering

Supervisor: Alessandra Carucci, Full professor,
Università di Cagliari
Co-supervisor: Stefano Milia, Researcher, Institute of
Environmental Geology and Geoengineering, National
Research Council (IGAG-CNR)

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Science is about knowing; engineering about doing
Henry Petroski

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September 2017
Acknowlegments

This research work was developed at the Department of Civil-Environment Engineering
and Architecture (DICAAR) at University of Cagliari from March 2017 until July 2017.

First I would like to thank the Department and specially Professor Alessandra Carucci
and Stefano Milia for the help and support during my stay in Cagliari.

To Giaime Tocco, my supervisor, who was the most important person during my thesis
work, a special thanks for all the help, patience and comprehension. For all the
knowledge shared, I truly learned a lot.

To the wonderful people I met during my stay, specially Abdel, Nasrat, Mohammed,
Adrian, Anna and Gabi, thank you for the friendship, the wise words and the amazing
moments that we shared during this 5 months, you will be forever in my heart.
A special thanks for Alessandro Secci, my flatmate, thank so much for everything, you
are one of those you made this possible.

I also appreciate the opportunity given by professor Maria Ascensão Reis to develop my
thesis in such interesting university and group.

I big thank you to my family, specially my mother, who allow me to go on this amazing
experience. Thanks for the support and care.

To my friends in Portugal, a special thanks for João Mendes, João Carmo, Guilherme,
Margarida, Francisco, Jessica, Diogo, Rafael and Gonçalo for this amazing 5 years, I
have to share this success with you, because without you I probably wouldn’t do it. A
friendship for life.

My oldest friends, Miguel, Ricardo Gomes, Ricardo Carvalho and Tiago Domingos, thank
you for staying with me even when we took different paths.

A big thank you to all for never letting me give up on my dreams.

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Abstract

In this study, wastewater produced by the Anaerobic Digestion of municipal solid waste
and pre-treated by partial-nitrification was fed to a granular Anammox reactor. A
conservative exponential Law was used to slowly replace the synthetic wastewater for
the pre-treated wastewater, starting at 10%.
This strategy was adopted in order to avoid stressful conditions to bacteria, which
could thus acclimate to the reactor conditions.
The experiment was divided in two phases, the first one with increasing real
wastewater ratio and a second phase totally fed with real wastewater.

The influent is characterized by a nitrogen loading rate of 1.5gNL-1d-1, with a NO2-
N/NH4-N ratio of 1.20.
Removal efficiencies were stable during all experiment, around 90%.

The Anammox activity also increased during the experimentation. The Volatile
suspended solids grown during phase 1 of experiment, with an initial value of 4,2
gVSSL-1.

The kinetics assay results also helped checking out the removal rates for ammonium
and nitrite, and production rates for nitrate. On the average the specific nitrate and
ammonium removal rate, with continues NLR was 0,370,07 g NO -N gVSS-1d-1 and
2
0,270,07 gNH -N/gVSS-1d-1, respectively. For nitrate production was 0,0550,030
4
gNO -NgVSS-1d-1,
3

The organic carbon removal was also tested. The effluent values were variable, and
real wastewater had no direct effect on the capability of the Anammox process to
remove organic carbon. This is due to a perfect partial-nitrification, who allowed the
real effluent to have low organic carbon, which not developed inhibition effect to the
Anammox bacteria.

During phase 2, the reactor was fed with real wastewater without any pre-treatment.
This experiment wasn’t very successful, and Anammox system failed.
After, was again fed with synthetic wastewater and the bacteria could recover.

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Results showed that the process can work with this type of wastewater, if a
conservative start-up strategy is adopted and a partial-nitrification step is used to
remove organic carbon.

Keywords: Anaerobic digestion, Anammox, partial-nitrification, ammonium, nitrite, real
wastewater, Nitrogen removal

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Resumo

Durante este estudo, água residual proveniente da Digestão Anaeróbica de resíduo
solido municipal foi pré-tratada e posteriormente alimentada a um reator Anammox
granular. O reator foi iniciado com um rácio sintético:real de 90%:10%
Uma estratégia de alimentação foi adotada de maneira a substituir gradualmente o
influente sintético pelo real, de maneira a não colocar a bactéria sobre condições de
stress químico.
A experiencia foi dividida em duas fases, uma primeira com um crescimento gradual do
rácio de influente real e uma segunda fase com 100% influente real.
O influente é caracterizado por um Nitrogen Loading Rate de 1. 5gN L-1 d-1, com um
rácio NO2-N/NH4-N de 1.20 (818 mg/L e 682 mg/L, respetivamente.
.
As eficiências de remoção foram estáveis durante toda a experiencia, por volta dos 90%

A atividade da bactéria aumentou durante o período experimental. Foi observado um
crescimento de sólidos suspensos voláteis durante a primeira fase. O valor inicial foi de
4,2 g VSS L-1.

De maneira a avaliar a atividade do processo, ensaios cinéticos foram realizados. Foi
então possível observar e calcular as velocidades de remoção de amónia e nitrito e
produção de nitrato. Em media, taxa de remoção especifica de amónia e nitrito foram
0,370,07 g NO -N gVSS-1d-1 e 0,270,07 g NH -N /gVSS-1d-1, respetivamente, com NRL
2 4
continuo.
Já a taxa de produção de nitrato foi 0,0550,030 g NO -N gVSS-1d-1.
3

A capacidade de remoção do processo foi também testada. A concentração de TOC no
efluente foi variável durante todo o processo, as dentro de valores que não causaram
inibição do processo.
Por trás disto, estará a elevada eficácia do processo de pré-tratamento em remover,
permitindo o influente do processo Anammox ter uma concentração baixa de TOC.

Durante a segunda fase, o reator foi alimentado com agua residual não tratada. A
experiencia não foi bem-sucedida, e o Sistema falhou durante uns dias.
De maneira a resolver este problema, foi novamente alimentado a 100% com influente
sintético e o Sistema voltou ao normal.

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Os resultados obtidos mostram que o sistema e capaz de trabalhar com este tipo de
agua residual, se uma estratégia de alimentação conservativa for adotada e um pré-
tratamento for usado para remover carbono orgânico.

Keywords: Anaerobic digestion, Anammox, partial-nitrification, ammonium, nitrite, real
wastewater, Nitrogen removal.

September 2017