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Health Risk Assessment Associated with the Reuse of
Compost, Urine and Greywater in Agricultural Field in Sahelian
Climate
DISSERTATION FOR THE
MASTER OF ENGINEERING IN WATER
AND ENVIRONMENT
MAJOR:WATER AND SANITATION
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Written and Defended on [June 24, 2014]
by
Alexis Loukou BROU
Under the Supervision of: Dr. Nowaki
HIJIKATA/Researcher/2iE Foundation
Dr. Mariam SOU/Lecturer/2iE Foundation
Mr. Seyram SOSSOU/Research Engineer/2iE
Foundation
Panel Members:
President: Pr. Rabah LAMAR
Members and correctors: Dr. MariamSOU
Dr. Lynda SAWADOGO
Dr. Nowaki HIJIKATA
Batch [2012/2014]
Dedication
For my Only Lord JESUS CHRIST
For my beloved wife Anne Aurélie N'Goné CISSE
In memory of my dear late father KOUAME Brou Paul and my dear
motherKOFFI Affoué who diedon August 15, 2012 before I started this
course
Acknowledgements
I would like to express our deep gratitude to the people whose
support, availability and advice contributed to the development of this
dissertation.
I am thankful for the scholarship that the government of the
Republic of Côte d'Ivoire granted me to enroll for the Master's
program.
I would like to thank all the supervising team for their
support, relevant criticism, remarks and suggestions in order to improve this
work particularly Dr. Mariam SOU, Dr. Nowaki HIJIKATA and Mr. Seyram SOSSOU.
I am thankful to Madam Aminata N'Diaye for her help to improve
quality of this dissertation.
I am grateful to the Laboratory assistants Mr. Noel
TINDOUREand Mr. Sohamaï HEMAfor their availability at the time of ours
analysis for this study.
I have appreciated the precious support I was provided with by
all the team of Ameli-EAUR project during the field study,and especially, that
ofMr.Innocent ZERBO, Mr. Koualè IDO and Mr. Bernard ZONGO.
Thank to my colleague trainees Yves Rodrigue KABORE; Danielle
Miranise OUEDRAOGO and Florence GAJU KAGABIGA for their support and their team
spirit
I would like to praise the support and advice I have had from
my great brothers Pierre BROU and Toussaint BROU and I thank all my relatives
for their prayers
Thank to my brothers and friends Richard EBA, Yves Oscar
BROUand Jean-Michel KOFFI for their support and advice.
My bath of master (2012-2014) for happy and difficult moments
which were overcome.
Finally, I highly-appreciate the support provided by all those
people that have contributed to the development of this dissertation and which
have not been listed.
Abstract
The aim of this study is to assess the health risks associated
with the reuse of human excreta (compost and urine) and greywater in the
agricultural field. It will firstly have to assess the health risk from farmers
associated with the reuse of human excreta and greywater in agriculture field;
and secondary to assess the health risk from consumers associated with the
reuse of human excreta and greywater in agriculture field. To achieve these
objectives, some hypotheses were considered as for the different exposed
groups. For farmers, we assume that they handle compost and urine in fields,
and they irrigate crops with greywater without adequate equipment protection
(gloves, clothing and shoes). For consumers, we assume that they eat lettuce
without washing it thoroughly. Different onsite experimentations havebeen
carried out. It is about combiningCompost and Top Water (C+TW), Urine and Top
Water (U+TW), Compost, Urine and Greywater (C+U+GW) and Non fertilizer (NoF)
which is used as a like controlling tool. An initial number of indicators and
pathogens cited above were determined in irrigation greywater, compost and
urine before applicationin the field. Microbiological quality of soil in
different combinations was monitored weekly from E.coli, Faecal
coliform, Faecal Enterococci, and Salmonella, and helminthes
eggs over two months. Quantitative microbial risk assessment was subsequently
evaluated for Salmonella and Ascarison these
combinations.Results vary from different treatments: For C+TW treatment, there
areannual risks of Salmonella infection in scenarios where it is
assumed that farmersmay ingest accidentally 10 to 100 mg of soil which
is3.87x10-3 pppy. Concerning Ascaris infection, annual risk
is4.67x10-2. From lettuce consumption, Salmonella annual
risk infection is 1.54x10-1. For U+TW treatment, Salmonella
annual risk infection in scenario where it is assumed that farmers can ingest
accidentally soil spread with urine is 9.55x10-1. For lettuce
consumption, annual risk is 1.30x10-7. From GW treatment,
Salmonella annual risk infection in scenario which assumes that
farmers ingest accidentally 10 to 100 mg of soil irrigated with greywater is
8.89x10-6. From ingestion of irrigation greywater, annual risk
infection is 1.02x10-4. Concerning lettuce consumption,
Salmonella risk infection is 9.42x10-4.
From C+U+GW treatment, in case of soil ingestion,
Salmonella annual risk infection is 1.44x10-4. For Ascaris
infection, risk is 4.67x10-2. From ingestion of irrigation
greywater, Salmonella annual risk infection is 1.53x10-3.
For Ascaris infection, risk is 3.97x10-1. From lettuce
consumption, Salmonella annual risk infection is 5.00x10-7.
For Ascaris infection, risk is 2.41x10-2.
Keywords: Health Risk Assessment, Compost,
Urine, Greywater, Quantitative Microbial Risk Analysis, Ascaris,
Salmonella, Reuse and Agriculture.
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