Ammonia Sanitisation of Human Excreta. Treatment Technology
for Production of Fertiliser
Annika Nordin
Akademisk avhandling som för vinnande av filosofie doktorsexamen kommer att
offentligt försvaras i Föreläsningssalen, Institutionen för Energi och Teknik, Ultuna,
fredagen den 29 oktober 2010 klockan 13.00.
Opponent: Professor Chris Buckley, Pollution Research Group, University of
KwaZulu-Natal, South Africa.
Betygsnämnd: Professor Per Arne Malmquist, Bygg- och miljöteknik, Chalmers
Tekniska Högskola, 412 96 Göteborg.
Professor Anders Dalsgaard, Department of Veterinary Disease/Section for
Microbiology, University of Copenhagen, Frederiksberg C, Denmark.
Docent Kara Nelson, Department of Civil and Environmental Engineering,
University of California, Berkeley, USA.
Dr Tove Larsen, EAWAG, Swiss Federal Institute for Aquatic Science and
Technology, Dübendorf, Switzerland.
Professor Johan Schnürer, Institutionen för Mikrobiologi, SLU, Uppsala.
Handledare: Docent Björn Vinnerås, Institutionen för Energi och Teknik, SLU, Box
7032, 750 07 Uppsala. E-post: Bjorn.Vinneras@et.slu.se
Biträdande handledare: Professor Håkan Jönsson, Institutionen för Energi och Teknik,
SLU, 7032, 750 07 Uppsala. E-post: Hakan.Jonsson@et.slu.se
Docent Ann Albihn, Avdelningen för Kemi, Miljö och Foderhygien, Statens
Veterinärmedicinska Anstalt, 751 89 Uppsala. E-post: Ann.Albihn@sva.se
Docent Christine Moe, Hubert Department of Global Health, Rollins School of
Public Health at Emory University, Atlanta, USA. E-post: clmoe@emory.edu
Distribution:
SLU, Department of Energy and Technology,
P.O. Box 7032, SE-750 07 Uppsala, Sweden
Uppsala 2010
ISSN 1652-6880
ISBN 978-91-576-7512-5
Ammonia Sanitisation of Human Excreta. Treatment Technology
for Production of Fertiliser
Abstract
Safe reuse of plant nutrients from human excreta increases the sustainability of
society and promotes health, both by decreasing disease transmission and by
increasing agricultural production. This thesis examined ammonia sanitisation as a
treatment method to produce a hygienically safe fertiliser from source-separated
urine and faeces.
Salmonella spp. and E. coli O157:H7 were inactivated to a high degree even at
low NH3 concentrations and temperatures. It was possible to model Salmonella spp.
inactivation using these two parameters. Salmonella spp. inactivation is suggested to
be verified by determining inactivation of faecal coliforms. At NH3 concentrations
between 20 and 60 mM, a sharp decrease in inactivation was observed at 24 ºC or
below for Enterococcus spp., bacteriophages and Ascaris eggs, with insignificant
inactivation of the latter during 6 months.
Urine contains sufficiently high total ammonia concentration and pH for selfsanitisation. Keeping the urine as concentrated as possible proved critical in
achieving NH3 concentrations that inactivated Ascaris eggs. Sun exposure increased
urine temperature and NH3 and shortened treatment time, and is feasible when
urine containers are small.
Urea treatment of faeces increased pH and total ammonia concentrations, both
contributing to formation of NH3. The final value and stability of the pH achieved
depended on initial pH and other material properties, but increased with increasing
urea addition. At high pH caused by ash addition, urea was not degraded. When
urea was added alone, it could not be confirmed that it was fully degraded.
Organism inactivation was always faster in urea-treated faeces compared with
untreated faeces. Urea treatment substantially shortened treatment time compared
with storage, especially at the higher temperatures studied (24 and 34 ºC).
Sanitation systems that collect urine and faeces separate and sanitise them by
ammonia permit a high degree of hygienically safe plant nutrient reuse.
Keywords: Ammonia, Ascaris, faeces, fertiliser, inactivation model, pathogen,
Salmonella, sanitisation technology, sustainable sanitation, urine
Author’s address: Annika Nordin, SLU, Department of Energy and Technology,
P.O. Box 7032, SE 750 07 Uppsala, Sweden
E-mail: Annika.Nordin@et.slu.se