9 urine treatment methods (maurer water research paper, 2006)
DESCRIPTION
Urine Treatment MethodsTRANSCRIPT
-
Available at www.sciencedirect.com
Review
M. Maurer , W. Pronk, T.A. Larsen
8600 Dubendorf, Switzerland
Article history:
3152
3153
3155
3.2.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3156
ARTICLE IN PRESS
WAT E R R E S E A R C H 40 ( 2006 ) 3151 3166Corresponding author. Tel.: +41 1 8235386.3.2.2. Evaporation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3156
3.2.3. Freeze-thaw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3157
3.2.4. Reverse osmosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3157
0043-1354/$ - see front matter & 2006 Elsevier Ltd. All rights reserved.doi:10.1016/j.watres.2006.07.012
E-mail address: [email protected] (M. Maurer).3.1.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3155
3.1.2. Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3155
3.2. Volume reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31562. Composition of urine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3. Treatment units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1. Hygienisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3152Received 20 December 2005
Received in revised form
7 July 2006
Accepted 11 July 2006
Available online 1 September 2006
Keywords:
Urine treatment
Process engineering
Wastewater
Source separation
Sustainable wastewater treatment
Struvite
P-recovery
N-recoveryThe separate collection and treatment of urine has attracted considerable attention in the
engineering community in the last few years and is seen as a viable option for enhancing
the flexibility of wastewater treatment systems. This comprehensive review focuses on the
status of current urine treatment processes and summarises the properties of collected
urine. We distinguish between seven main purposes of urine-treatment processes:
hygienisation (storage), volume reduction (evaporation, freeze-thaw, reverse osmosis),
stabilisation (acidification, nitrification), P-recovery (struvite formation), N-recovery (ion-
exchange, ammonia stripping, isobutylaldehyde-diurea (IBDU) precipitation), nutrient
removal (anammox) and handling of micropollutants (electrodialysis, nanofiltration,
ozonation). The review shows clearly that a wide range of technical options is available
to treat collected urine effectively, but that none of these single options can accomplish all
seven purposes. Depending on the overall goal of the treatment process, a specific technical
solution or a combination of solutions can be found to meet the requirements. Such
combinations are not discussed in this paper unless they are explicitly presented in the
literature. Except for evaporation and storage, none of the processes described have so
far advanced beyond the laboratory stage. Considerable development work remains to be
done to optimise urine-processing techniques in order to create marketable products.
& 2006 Elsevier Ltd. All rights reserved.a r t i c l e i n f o A B S T R A C TSwiss Federal Institute for Aquatic Science and Technology (Eawag),Treatment processes for source-separated urine
journal homepage: www.elsevier.com/locate/watres
-
. . .
. . .
. . .
. . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3158
. . .
. . .
. . .
. . .
. . .
. . .
ion
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. . .
. .
. .
. .
less than one percent of the total wastewater volume.
(Wilsenach
Urine-sou
leaves many
me
org
lism (Esche
wa
ing
2006; Medila
flexibility a
prototypic w
du
illu
in this pap
rec
wa
household t
with todays
lon
pro
T
sep
and Gujer (1996) suggested local storage and transport in
ARTICLE IN PRESS
( 2g it would take a market economy to develop smart mass-
duced technology to do exactly that at competitive costs.
A large amount of data for urine is available in the medical
literature. Urine from collection systems differs from thesehere are
aration otreatment is seldom discussed. As an example,
reatment of urine seems inefficient and expensive
technology, but nobody has really examined how
2. Composition of urineycling, but the potential of mass-producing goods for
stewatery the many different treatment options discussed
er, ranging from nutrient removal to nutrienttions (e.g. manned space flights) as well as on experience in
the treatment of other high-strength liquid waste products.ced market goods (Larsen and Gujer, 2001). Flexibility is well
strated bexperience gained with urine treatment in different situa-r-scarce cities in emerging countries (Huang et al.,
nski et al., 2006). Furthermore, it offers increased
nd a possible shift away from investments in
astewater treatment plants towards mass-pro-
in agriculture is the most obvious application, but industrial
usage or simple nutrient removal are other possible options.
In this paper, we give an overview of the available technol-
ogies for treating source-separated urine, drawing on thestewater management when applied in the rapidly expand-
andwateand van Wijk-Sijbesma, 2005), the use of urine as a fertilizerropollutants originating from the human metabo-
r et al., 2006) and new ways of more efficientBecause the composition of urine reflects the average
requirement of nutrients for plant growth (Heinonen-Tanskintioned above, it also promises better ways of removing
anic micengineering options.tion, denitrification and phosphorus elimination
and Van Loosdrecht, 2004).
rce separation presents many advantages, but also
open questions. Besides the obvious advantages
Frohlich, 2002) and finally, on-site treatment may be possible
in the future, provided that the technical difficulties can be
overcome (Wilsenach et al., subm.). In the present paper, we
concentrate on the possibilities and difficulties of the processSubstantial separation of urine at source would thus allow
nutrient recycling from a concentrated nutrient solution and
at the same time obviate advanced nutrient removal, includ-
ing nitrifica
sewers over night; the concept developed in Sweden is long-
term local storage followed by truck transport (Hanaeus et al.,
1997); in some pilot projects, multiple piping is tested (Peter-3.3. Stabilisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . .
3.3.2. Acidification . . . . . . . . . . . . . . . . . . . . . . .
3.3.3. Partial nutrification . . . . . . . . . . . . . . . . .
3.4. P-recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . .
3.4.2. Struvite (MgNH4PO4) . . . . . . . . . . . . . . . . .
3.5. N-recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . .
3.5.2. Ion exchange . . . . . . . . . . . . . . . . . . . . . .
3.5.3. Ammonia stripping . . . . . . . . . . . . . . . . .
3.5.4. Isobutylaldehyde-diurea (IBDU) precipitat
3.6. Nutrient removal (P and N) . . . . . . . . . . . . . . . . .
3.6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . .
3.6.2. Anammox Process . . . . . . . . . . . . . . . . . .
3.7. Removal of micropollutants . . . . . . . . . . . . . . . . .
3.7.1. Introduction . . . . . . . . . . . . . . . . . . . . . . .
3.7.2. Electrodialysis. . . . . . . . . . . . . . . . . . . . . .
3.7.3. Nanofiltration . . . . . . . . . . . . . . . . . . . . . .
3.7.4. Ozonation and advanced oxidation . . . . .
4. Conclusions and outlook. . . . . . . . . . . . . . . . . . . . . . . . .
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1. Introduction
In the 1990s, various European groups began working on the
same basic idea that separating urine at source could
promote the sustainability of wastewater management
(Kirchmann and Pettersson, 1995; Larsen and Gujer, 1996).
All these approaches are based on the fact that urine contains
most of the nutrients in domestic wastewater but makes up
WAT E R R E S E A R C H 403152also many challenges in connection with source
f urine. Once urine has left the body it becomes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3158
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3159
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3159
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3159
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3159
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3160
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3160
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3160
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3160
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3160
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3161
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3161
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3161
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3161
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3162
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3162
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3163
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3163
an unpleasant, smelly and unstable solution. It is locally
produced and the present practise of dilution with large
amounts of water is actually a perfect way of neutralising
many of the more unpleasant aspects of urine. Furthermore,
centralized wastewater management is a system with inter-
dependent actors, and changing even a small part of it is
extremely difficult (Larsen and Lienert, 2003). Finally, the
question of transportation has not yet been solved. Larsen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3157
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3157
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3157
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3158
006 ) 3151 3166data, because (a) the composition is averaged over time and
user group, (b) chemical alteration occurs in a non-sterile
-
ARTICLE IN PRESS
ste
kpl
H [2 CH S CH urine
.26
9.0
793
720
76
650
770
98
837
400
28
1.0
ted
mn
ita
), [6
(2environment, and (c) dilution with flushing water adds
elements such as calcium and magnesium that can further
alter the composition.
The composition of stored urine from different collection
Table 1 Concentration of urine from different collection sy
Parameter Unit
Source Household
S [1]School S [1] Wor
C
Dilution[a] () 0.33 0.33 0
pH () 9.0 8.9
Ntot (gNm3) 1795 2610 1
NH4++NH3 (gNm
3) 1691 2499 1
NO3+NO2
(gNm3) 0.06 0.07
Ptot (gPm3) 210 200
COD gO2 m3 1
K (gKm3) 875 1150
S (gSm3) 225 175
Na (gNam3) 982 938
Cl (gClm3) 2500 2235 1
Ca (gCam3) 15.75 13.34
Mg (gMgm3) 1.63 1.50
Mn (gMnm3) 0 0
B (gBm3) 0.435 0.440
The dilution[a] by the flushing water of the collection systems is extrac
urine composition of fresh urine (non hydrolysed) is listed in colu
(SO42S), [c]: value measured in undiluted, fresh urine, without precip
Ronteltap et al. (2003), [4]: Jonsson et al. (1997), [5]: Udert et al. (2005a
WATER RESEARCH 40systems is listed in Table 1. Data from a medical source (Ciba-
Geigy, 1977; last column) is given as a comparison for fresh
urine. During storage under non-sterile conditions, the urea
present in urine is hydrolysed to ammonia/ammonium and
carbonate due to microbial activity. This causes a pH increase
from around 6 to around 9 and triggers the precipitation of
calcium and magnesium in form of carbonates and phos-
phates (Udert et al., 2003a/b). This is clearly visible in the low
Ca and Mg concentrations in the stored urine. Depending on
the urine collection system, more or less flushing water is
present in the collected liquid. This water dilutes the overall
concentration of the substances and is considered in Table 1
with a dilution factor that expresses the fraction of undiluted
urine in the collection tank. Only the composition from
reference [5] in Table 1 presents concentrations from un-
diluted urine and therefore deviates substantially from all the
other concentrations.
The heavy metal content in urine is generally low (Kirch-
mann and Pettersson, 1995; Jonsson et al., 1997; Ciba-Geigy,
1977). Specific concentrations, i.e. relative to phosphorus or
nitrogen, are relevant if we want to use urine or products
derived from it as fertiliser. The comparison with commercial
fertilizer shows clearly that urine is always at the low or very
low end compared to commercially available fertilizer or
manure. Phosphate fertiliser in particular can have a high
heavy-metal content depending on the rock phosphate used.
Thus, analyses performed by Rogowski et al. (1999) and
McBride and Spiers (2001) show that agricultural bulk
fertilizers can have cadmium concentrations of up to36gCd kgP1, which are several magnitudes higher than those
of typical urine.
An important excretion pathway for hormones and many
pharmaceuticals is via urine. This is actively prepared in the
? 0.75 1 1
9.0 9.1 9.1 6.2
3631 9200 8830
4347 3576 8100 463
o0.1 0 154 313 540 8002000
6000 10000
3284 1000 2200 2737
273[b] 331 505[b] 1315
1495 1210 2600 3450
2112 1768 3800 4970
18 0 233
11.1 0 119
0.037 0.019
0.97
from the information given by the publications. For comparison, the
[6].Legend: [a]: defined as Vurine/(Vurine+Vwater), [b]: only sulfateStion, [1]: Kirchmann and Pettersson (1995), [2]: Udert et al. (2003a), [3]:
]: Ciba-Geigy (1977).ms
Concentration
ace]
Workplace[3]
Household[4]
Workplace[5]
Fresh[6],[c]
006) 3151 3166 3153liver by enhancing the water solubility of organic substances
adsorbed, so that they can be removed in the kidneys and
excreted via the urine (e.g. Ritschel and Kearns, 1999). Urine
might therefore contain a majority of the dissolved micro-
pollutants excreted by humans and due to their mobility also
the one most prone to transport and relevant for aquatic
ecosystems. However, it has to be emphasised that so far
there are no systematic evaluation of the medical literature
published that would back up this point statistically. Excep-
tions are estrogens, where 80% of the natural estrogens and
67% of the artificial hormone 17a-ethinyl estradiol areexcreted via urine (review in Christiansen et al., 2002).
Recent research indicates that the toxic effects of pharma-
ceuticals are additive. Silva et al. (2002) made it very clear that
in complex mixtures, such as wastewater or urine, threshold
values are very difficult to set. Escher et al. (2002 & 2005)
showed that the toxic effect of a mix of pharmaceuticals,
each without any specific mode of toxicity (baseline toxicity),
can be estimated by adding up the toxic effects of the single
substances.
3. Treatment units
The unique properties of urine mean that a wide variety of
technologies may be used to treat it. We defined seven main
purposes of a treatment unit: volume reduction, P-recovery,
N-recovery, stabilisation, hygienisation, removal of micropol-
lutants and biological nutrient removal. For practical
-
ARTICLE IN PRESS
Ta
ble
2
Overv
iew
of
the
treatm
en
tm
eth
od
sd
iscu
ssed
inth
ep
ap
er
Hygiene
Vol.
reduction
Stabilisation
P-recovery
N-
recovery
MP
elimination
NutrientMP
separation
Nutrient
elimination
Solidification
Needofpre/post-
treatm
ent
Info
literature
Hygienisation
Storage
+o
oo
oo
oo
(+)
-+
Volumereduction
Evaporation
+++
+++
++
oo
o++
+o
Freeze-thaw
?+
o++
++
oo
oo
o+
Reverseosm
osis
?+
o++
++
oo
oo
++
Stabilisation
Acidification
+o
++
oo
?o
oo
o+
Microfiltration
+o
++
oo
oo
oo
o+
Nitrification
+o
++
oo
?o
o(+)
o+
P-recovery
Struvite
o++
+++
+o
++
o++
o++
N-recovery
Ionexch
ange
o+
oo
++
o+
o++
o+
Struvite
o++
+++
++
o++
o++
o++
NH3stripping
o+
oo
++
o++
oo
o+
Isobutylaldehyde-
diurea
o+
oo
++
o+
o+
o+
Nutrientremoval
Anammox
+o
++
oo
?+
++
(+)
+++
Others
+o
+(+)
o?
o+
(+)
(+)
+
Micropollutionremoval
Electrodialysis
++
++
++
o+
oo
o+
Nanofiltration
++
o+
oo
o++
oo
++
Ozo
nation
+o
+o
o++
oo
oo
+
Thecolumnsrepresentthegoals
thatcanbeach
ievedwithasp
ecificprocess;therowslist
thetech
nologicalprocess.Legend:o:noeffect,+:positiveeffect,++:strongeffect,:
notapplicable.
WAT E R R E S E A R C H 40 ( 2006 ) 3151 31663154
-
ARTICLE IN PRESS
cri
Fig
(2Fig. 1 General template for the des
Fig. 2 Storage (seeWATER RESEARCH 40purposes, each treatment unit is assigned one of these seven
main purposes and is discussed under the corresponding
section. The assignment is somewhat arbitrary, because most
treatments attain several goals and other purposes might
have prevailed depending on the priorities set by the
evaluator. Table 2 gives an overview of the treatment methods
discussed in the paper. The efficiencies for specific goals
(columns) are roughly characterised. In order to achieve a
specific treatment target, it may be necessary to combine
several unit operations. For reasons of brevity, such combina-
tions are not discussed here unless they are explicitly
presented in the literature.
Each urine treatment process is roughly summarized in a
little scheme (Figs. 214). A general explanation of these
schemes is given in Fig. 1.
3.1. Hygienisation
3.1.1. IntroductionUrine from unhealthy humans may contain pathogenic
organisms (Santos et al., 2004; Vanchiere et al., 2005) as well
as prions (Reichl, 2002). Furthermore, faecal contamination
can result in high counts of faecal indicator organisms
(Hoglund et al., 2002b). Schonning et al. (2002) estimated a
faecal contamination of 9.175.6mg lurine1 in the urine collec-
tion system that they investigated. Although the exposition
pathways and effects associated with these pathogens have
not been investigated in detail, hygienic risks associated with
source-separated urine have to be avoided.. 1 for explanation).ption of urine treatment processes.
006) 3151 3166 3155Technically, there are many ways of pasteurising or
sterilising any solution (heat, pressure, UV, etc.), but none of
these methods have been tested for urine. Only storage has
been explicitly investigated for its ability to reduce the
amount of pathogens in source-separated urine, although
many of the treatment steps discussed in this paper are
expected to have an influence on its hygienic properties
(see Table 2).
3.1.2. StorageStorage (Fig. 2) offers a possible way of reducing the potential
health risks from faecal pathogens (See Fig. 1 for explana-
tion). Three storage parameters influence this process:
storage time, temperature and pH. Hoglund et al. (1998,
1999, 2000, 2002a/b) investigated the decay rates of bacterial
and viral indicator organisms in stored urine collected from
households. From the inactivation curves for rhesus rota-
virus, Campylobacter jejuni and Cryptosporidium parvum, the
authors concluded that if stored at 20 1C for at least 6
months, urine may be considered safe to use as a fertilizer for
any crop (Hoglund et al., 2002b). Their experiments showed
that temperature was the most crucial parameter influencing
the inactivation rates. Without pH control (pH49), 90% of the
rhesus rotavirus were inactivated after 35 days at 20 1C, but no
significant decrease could be detected at 4 1C. Combined with
pH control (see Fig. 3), pH values below 4 seem to result in
additional reduction in the number of pathogens (Hellstrom,
1999). Important side-effects of storing raw source-separated
urine are the precipitation of phosphorus compounds (Udert
-
ARTICLE IN PRESS
e F
e Fig.
( 231Fig. 3 Evaporation (se
Fig. 4 Freeze-thaw (seet
tha
3.2
3.2Fro
con
wo
tio
ha
spa
3.2Ev
rem
the
Th
ap
su
WAT E R R E S E A R C H 4056al., 2003b) and possible evaporation of ammonia from tanks
t are not sufficiently sealed (Udert et al., 2005a).
. Volume reduction
.1. Introductionm the perspective of commercial fertilisers, the nutrient
tent in urine is small: N: 0.9%, P: 0.06%, K: 0.3% (Table 1). It
uld be beneficial to concentrate the nutrients for transporta-
n and storage purposes. Various water extraction techniques
ve been investigated and developed for long-term manned
ce flights (seeWieland, 1994 for an overview and references).
.2. Evaporationaporation is the most straightforward technology for
oving water from urine (Fig. 3). For space applications,
focus is on recycling water of the best possible quality.
e following list gives a condensed overview of the
proaches reported in the literature. Most of them are
mmarised and referenced in Wieland (1994):
Vapour compression distillation (VCD) recovers more than
96% of the water content and the energy requirement for a
T
los
can
tio
by
us
sp
Fig. 5 Reverse osmosis (see F1 for explanation).1 for explanation).ig.006 ) 3151 3166small-scale unit is 277396MJm3. NASA plans to install
this unit for processing urine in the international space
station in 2005.
Thermoelectric integrated membrane evaporation sys-
tems (TIMES). The urine is pre-treated with ozone (or
ideally UV) and sulphuric acid. It is then heated, pumped
through hollow fibre membranes and exposed to reduced
pressure so that it evaporates.
Air evaporation systems (AES). Pre-treated urine is
pumped through a particulate filter to a wick package.
Heated air is used to evaporate the water from the wick,
leaving the solids.
Lyophilization (Holland et al., 1992). Frozen urine sub-
limates under vacuum and is recovered at 90 1C toproduce ice with a total solid content of 51mgTSl
1.
he evaporation of urine presents two major challenges: (i)
s of ammonia and (ii) energy consumption. Ammonia loss
be avoided by using non-hydrolysed urine or by acidifica-
n (see below). The energy consumption can be minimised
energy recovery. Large-scale thermal desalination plants
e vapour compression distillation (VCD) and can reach
ecific energy requirements of 150180MJm3 distiled water
ig. 1 for explanation).
-
(Wood, 1982) compared to 2600MJm3 without any energy
recovery. The small-scale space VCD system for about four
adults requires less than 400MJm3, which is equivalent to an
energy recovery of 85%.
In our own laboratory-scale experiments (Mayer, 2002),
non-hydrolysed urine was evaporated at 200mbar and 78 1C.
A tenfold volume reduction was possible without any crystal-
lisation problems, producing a viscous liquid that contained
2000). The required dosages of these agents must be
determined experimentally as a function of the concentration
factor.
3.3. Stabilisation
3.3.1. Introduction
3.3.2. Acidification
ARTICLE IN PRESS
WATER RESEARCH 40 (2006) 3151 3166 31579.7% nitrogen by weight.
3.2.3. Freeze-thawLind et al. (2001) showed that by freezing urine at a
temperature of 14 1C, approximately 80% of the nutrientscan be concentrated in 25% of the original volume (Fig. 4).
Gulyas et al. (2004) confirmed these results by using falling-
film and stirred-vessel freeze concentrators. Using data from
commercial freeze concentrators, they calculated an energy
consumption of 1100MJm3 for a fivefold volume reduction.
These data indicate that evaporation is more efficient with
respect to energy efficiency and that the freeze-thaw process
will be an option only in places with cheap freezing energy
(a cold climate).
3.2.4. Reverse osmosisIn reverse osmosis membranes, the retention of ammonium
is better than its uncharged form (ammonia) and therefore
the retention performance depends strongly on the pH (Fig. 5).
Dalhammar (1997) acidified stored urine to pH 7.1 in order to
prevent permeation of ammonia. At a pressure of 50bar, a
maximum concentration factor of 5 could be achieved,
resulting in the following recoveries of nutrients in the
retentate: ammonium: 70%; phosphate: 73%; potassium:
71%. Similar results were achieved by Thorneby et al. (1999)
in reducing the volume of manure with reverse osmosis.
Fluxes in the range of 2025 lm2h1 could be obtained at
30bar (25 1C). The retention was greater than 98%, except for
ammonia, which was between 93% and 97%. Reverse osmosis
membranes have a high retention for micropollutants (Hof-
man et al., 1997) so that no separation between nutrients and
micropollutants can be expected in this process. The energy
consumption depends on operational and technical para-
meters and energy recovery systems can be installed in large-
scale applications (Avlonitis et al., 2003).
A limiting factor for the application may be the precipita-
tion of salts on or in the membrane, a phenomenon known as
scaling (Migliorini and Luzzo, 2004). In order to control
scaling, chemical formulations based on acids, surfactants or
combinations of both can be added (Jaffer, 1994; Al-Rammah,Fig. 6 Acidification (see FA way of preventing urea hydrolysis is to keep the pH in the
collection tank below 4 (Hellstrom, 1999). Experiments
showed that 60mmolH l1urine of a strong acid (e.g. 2:9g l
1urine
of concentrated sulphuric acid) successfully keeps the pH
below 4 for more then 250 days and prevents hydrolysis of
urea (Fig. 6).
The side effects of acidification are positive with respect to
hygiene due to detrimental effects on pathogenic organisms
at pH values below 4 (Hellstrom, 1999). Low pH values can also
have an impact on pharmaceuticals present in the urine. At
pH 2, an inactivation level of between 50% and 95% could be
found for antibiotics (sulfamethazin, sulfamethoxazol, tetra-
cyclin) and the anti-inflammatory drug diclofenac (Butzen et
al., 2005).
The prevention of urine hydrolysis is muchmore economic-
al than subsequent neutralisation. The neutralisation of
already hydrolysed urine requires 230mmolH l1urine (e.g.11:3g l1urine of concentrated sulphuric acid), approximatelyfour times more than preventive acid addition.Fresh urine contains salts, soluble organic matter and
ammonia bound in urea (Table 1). After microbial contamina-
tion, organic matter is degraded and urea hydrolysed.
Hydrolysis of urea releases ammonia and causes a pH
increase to about 9.2, resulting in more volatile NH3 and
precipitation of compounds with low solubility. True stabili-
sation of urine would thus prevent (i) degradation of organic
matter (causing odour), (ii) precipitation processes (clogging
pipes) and (iii) volatilisation of NH3 (with a number of
negative effects on air quality during storage, transport and
application of liquid fertilizer). Since microbial activity
triggers all these processes, prevention of microbial growth
would be the ultimate stabilisation process. Acidification,
microfiltration and ultrafiltration have been suggested to
achieve this, but only acidification has been studied in detail.
Information is available from the literature on urease
inhibitors to prevent urea hydrolysis, but Benini et al. (1999)
found that the reported efficiencies are low and negative side
effects have to be considered.ig. 1 for explanation).
-
ARTICLE IN PRESS
4) (s
(s
( 23.3.3. Partial nutrificationNitrification is a suitable method for lowering the pH. Since
no other relevant buffers are present in urine in significant
concentrations, nitrification of urine can only oxidise half the
available ammonium until nitrification stops due to low pH
conditions. High nitrite concentrations and low pH have a
specific detrimental effect on nitrite oxidisers, due to their
sensitivity to nitrous oxide (e.g. Hunik et al., 1993). Complete
Fig. 8 Struvite (MgNH4PO
Fig. 7 Partial nitrification
WAT E R R E S E A R C H 403158conversion of ammonia to nitrite is therefore often inhibited,
depending on the operational conditions. Experimental
results by Johansson and Hellstrom (1999) and Udert et al.
(2003c) confirm that the product of urine nitrification is either
an ammonium-nitrate or ammonium-nitrite solution with an
approximate 1:1 composition (Fig. 7).
Due to high concentrations in urine (mainly of salt,
ammonia and nitrous acid, see Udert et al., 2003c for a
detailed discussion), inhibition affects nitrification andmakes
a continuously operated technical process sensitive to
instabilities. A more detailed overview of the nitrifier kinetics
can be found in Hellinga et al. (1999) and Van Hulle (2005). An
attractive alternative for converting nitrite to nitrate is by
chemical oxidation with oxygen at low pH values (Udert et al.,
2005b).
Udert et al. (2003c) operated three continuous laboratory
systems: A moving-bed biological reactor (MBBR), a sequen-
cing batch reactor (SBR) and a continuously stirred reactor
(CSTR). Only the MBBR system was capable of producing
ammonium nitrate as a final product. The measured conver-
sion rates were 380gNm3 d1 (25.3 1C) at steady state. The
other two systems produced stable ammonium nitrite even at
high sludge ages or hydraulic residence times respectively.
The measured nitrite formation rates were 790gNm3 d1
(30 1C; HRT 4.8d) for the CSTR and 280gNm3 d1 (24.5 1C;HRT 4d; SRT430d) for the SBR. Because the inhibitionkinetics are not yet fully understood, it is important forpractical purposes to monitor the nitrification process care-
fully. This can easily be done in technical systems by feeding
the system in such a way that the pH does not get too high or
too low. The product of these efforts is a stable solution
without the typical urine smell and with no easily degradable
substances.
3.4. P-recovery
ee Fig. 1 for explanation).
ee Fig. 1 for explanation).
006 ) 3151 31663.4.1. IntroductionPhosphate is produced from phosphate rock, a limited
resource. The estimated worldwide reserves range from 1.2
to 5 1010 tons, which would suffice for 50300 years (Steenand Steen, 1998; results also in Driver et al., 1999; Zapata and
Roy, 2005), depending on the assumed consumption scenario.
At the moment, the depletion of phosphorus reserves is less
of a concern than the decrease in their quality (and therefore
increase in price) and the strategic considerations of the
worlds phosphorus producers. If no new sources of high-
quality phosphate are identified, future phosphorus reserves
will contain less phosphate and higher levels of enrichment
by heavy metals, principally cadmium (Driver et al., 1999;
Smil, 2000; Isherwood, 2000).
Extensive reviews of phosphorus removal and recovery
technologies from liquid wastes are given in Brett et al. (1997),
Wilsenach and Van Loosdrecht (2002), Valsami-Jones (2004),
and De-Bashan and Bashan (2004). Many of the processes
described, especially those for the treatment of digester
supernatant, are also applicable to urine.
In the literature on phosphate recovery, precipitation of
struvite seems to be the predominant product, followed by
calcium phosphate. Udert et al. (2003b) investigated scales in
urine collection systems and reported struvite, calcium
phosphate (hydroxyapatite) and calcite as the predominant
forms of precipitation. Despite the many P-recovery options,
-
known as struvite, MAP or AMP, is an attractive precipitate
ARTICLE IN PRESS
ee
g (
(2because it conveys two dominant wastewater nutrients in
solid form (Fig. 8). Additionally, the product can be used as a
slow-release fertiliser (Bridger et al., 1961; Johnston andonly struvite precipitation can be found in the literature on
P-recovery from urine.
3.4.2. Struvite (MgNH4PO4)Magnesium ammonium phosphate (MgNH4PO4 6H2O), also
Fig. 9 Ion exchange (s
Fig. 10 Ammonia strippin
WATER RESEARCH 40Richards, 2003). Gaterell et al. (2000) suggest the conversion
of struvite into an enhanced struvite that contains two parts
of a slow-release fertiliser (magnesium phosphate, MgHPO4)
and one part of the easily soluble ammonium phosphate
((NH4)2HPO4): this product is claimed to have good market
potential. Technical struvite precipitation was extensively
investigated for the removal of N and P from digester
supernatant (e.g. Wu and Bishop, 2005), animal waste slurries
(e.g. Suzuki et al., 2002) and for the treatment of wastewater,
landfill leachate and abattoir effluent.
The pH of hydrolysed urine is optimal for struvite pre-
cipitation (Buchanan et al., 1994) and therefore no pH
adjustment is required. The precipitation is triggered by the
addition of magnesium, usually in the form of MgO, Mg(OH)2,
MgCl2 or bittern (the magnesium-rich brine from table-salt
production). As shown in Table 1, there is much more
ammonium than phosphate present in urine on a molar
basis. As a consequence, about 3% of the nitrogen can be
eliminated by magnesium addition only so that the effect on
the pH value is small. Ronteltap et al. (2006) investigated the
conditional solubility product and the equilibrium reactions
for urine. The simplified solubility product was determined
with [Mg] [NH4++NH3] [Portho] 107.6 M3 (pH 9 and a ionicstrength 0.68), where [Mg] is the concentration of dissolvedmagnesium, [NH4
++NH3] the measured ammonium+ammo-
nia, and [Portho] the dissolved ortho-phosphate. See alsoRonteltap et al. (2003) for an overview of the published
solubility products for struvite.
No relevant information is given about the kinetics of
struvite precipitation in urine. From the fact that stored urine
contains a plethora of fine particles such as micro-organisms
and precipitation products (Hoglund et al., 1998; Udert et al.,
2003b), it can be concluded that heterogeneous nucleation
could play a dominant role in the formation of struvite
crystals. Our own experience with urine shows that pre-
cipitation in batch experiments is fast and without any
Fig. 1 for explanation).
see Fig. 1 for explanation).
006) 3151 3166 3159perceivable lag.
3.5. N-recovery
3.5.1. IntroductionProcesses for the production of nitrogen fertiliser are based
on the fixation of atmospheric nitrogen in the Haber-Bosch
process. Depletion of resources does not therefore play a
major role in evaluating the environmental benefits of
nitrogen recovery processes, energy consumption being the
main parameter. An overview of current nitrogen recycling
technologies in general wastewater treatment is given in
Rulkens et al. (1998) and Maurer et al. (2002); corresponding
energy consumptions are summarised in Maurer et al. (2003).
3.5.2. Ion exchangeAn ion exchanger with a high affinity for ammonium is
clinoptilolite, a naturally occurring zeolite, and polymeric
macronet exchangers have recently also become available
which are suitable for this purpose (Jorgensen and Weath-
erley, 2003) (Fig. 9). Both materials as well as other zeolites
have been tested for the treatment of waste water effluents
(Liberti et al., 1981), and zeolites have been tested for the
removal of ammonia from urine, also combined with the
addition of MgO for recovering phosphate in the form of
struvite (Lind et al., 2000; Ban and Dave, 2004). The highest
-
If the aim of urine treatment is improved control of water
ARTICLE IN PRESS
see
s (s
( 23.5.3. Ammonia strippingStored urine was stripped under vacuum (0.4 bar, 40 1C) and
the gas stream was adsorbed in water at a pressure of 5 bar
and 20 1C (Behrendt et al., 2001). The resulting productrecovery rates were obtained at an MgO dosage of 0.5mg/l and
a zeolite dosage of 15g/l. The remaining supernatant
concentrations for P and N were 10gPm3 and 1000gNm
3,
respectively.
Fig. 12 Electrodialysis (Fig. 11 Anammox proces
WAT E R R E S E A R C H 403160contains 10% ammonia and is unstable at normal pressure.
No information is provided on the concentration of ammonia
remaining in the urine solution after stripping (Fig. 10).
Energy consumptions can be estimated from experiments
with digester supernatant (Siegrist, 1996). At 20 1C and 95%
ammonia removal, the energy consumption was reported to
be around 7kWhm3treated liquid. Vapour Phase Catalytic Am-
monia Removal (VAPCAR) combines vaporisation with high-
temperature catalytic oxidation of ammonia and other
volatile compounds. A two-step catalytic process is used to
produce nitrogen gas, carbon dioxide and water (Slavin and
Oleson, 1991).
3.5.4. Isobutylaldehyde-diurea (IBDU) precipitationIn fresh, non-hydrolysed urine, nitrogen is mainly present in
the form of urea. Urea forms a complex with isobutyralde-
hyde (IBU), resulting in the precipitation of isobutylaldehyde-
diurea (IBDU), a commercially available slow-release fertilizer.
Its industrial production requires a high urea concentration
(Behrendt et al. 2001, Reinhart, 2002) and even at these
concentrations an excess of urea or IBU results only in partial
complexation, so that relatively high fractions of urea remain
in the liquid phase after treatment. Production at the urea
concentration of approximately 1% present in urine is there-
fore not feasible (Reinhart, 2002). Experimental results with
urine confirm this statement (Behrendt et al. 2001). At a five-pollution, it may be desirable to remove N and P without
recovering them. Whereas biological P-removal has neverfold stoichiometric excess of IBU, about 75% conversion of
urea was obtained.
3.6. Nutrient removal (P and N)
3.6.1. Introduction
Fig. 1 for explanation).ee Fig. 1 for explanation).
006 ) 3151 3166been considered for the treatment of source-separated urine,
full nitrification can easily be achieved with an extension to
partial nitrification (see above). Denitrification (resulting in
N2) may be achieved in a number of ways: biological reduction
of nitrate with organic matter as the electron donor; biological
oxidation of ammonia with nitrite as the electron acceptor
(the anammox process) or electrochemical oxidation of
ammonia (NASA 1977). Of these technologies, the anammox
process has been studied in detail for urine.
3.6.2. Anammox ProcessAnaerobic ammonium oxidation (Anammox) is a biological
process designed to eliminate nitrogen independently of a
carbon source (Strous et al., 1998) (Fig. 11). Under anaerobic
conditions, ammonium and nitrite are converted mainly to
nitrogen gas. As reported in Fig. 7, the formation of nitrite
stops halfway through the process, producing a 1:1 ammo-
nium/nitrite solution. Udert et al. (2003c) added this solution
to anammox sludge from a pilot plant treating digester
supernatant. At 30 1C they measured a denitrification rate of
1000gNm3d1 and the ratio of total ammonia to nitrite
elimination was 1:1.1870.07. The results of these experi-
ments show that nitrogen can be removed from source-
separated urine with anammox. A combination of nitrifica-
tion and anammox reactors could eliminate 7585% of the
nitrogen, leaving an ammonium nitrate solution.
-
3.7. Removal of micropollutants
3.7.1. IntroductionIncreasingly powerful analytical methods mean that a large
number of pharmaceuticals and natural hormones from the
human metabolism are now detected in the aquatic environ-
ment, but their environmental relevance is currently unclear.
Most of the effects that can be observed, e.g. the formation of
vitellogenin (a precursor of egg yolk proteins) in male trout
(Harries et al., 1997), are chronic effects without clear
consequences for the affected organism. It is generally
recognised that urine contains a significant amount of
excreted micropollutants. In general, a distinction must be
made between separation and elimination processes. The
separation of nutrients and micropollutants is relevant to the
production of a urine-based fertilizer, whereas the micro-
pollutants must be eliminated for water-pollution control.
Separation processes are primarily based on membranes or
precipitation whereas removal processes are based on oxida-
tion or adsorption (Larsen et al., 2004).
out (Pronk et al. 2006b) in order to manipulate the pH.
Ammonia was transferred across a hydrophobic membrane
from the basic into the acid concentrate. Batch experiments
confirmed that a pH decrease occurred in the acid concen-
trate, also known as the product compartment. However, at
higher conversions the pH rose again to its original value.
This pH increase can be attributed to carbon dioxide
transported from the basic concentrate across the gas-filled
membrane into the acid concentrate (Pronk et al. 2006b). The
use of an ammonium-selective gas-transfer membrane
instead of a hydrophobic gas-transfer membrane should in
principle solve this problem, but this has not yet been
investigated.
3.7.3. NanofiltrationNanofiltration (Fig. 13) has been tested for the retention of a
range of environmentally relevant compounds such as
pesticides (Van der Bruggen et al., 2001), disinfection by-
products and pharmaceutical compounds (Kimura et al.,
2004), phthalates (Kiso et al. 2001) and natural steroid
ARTICLE IN PRESS
see
WATER RESEARCH 40 (2006) 3151 3166 3161In addition to the processes presented here, it is possible in
principle to remove micropollutants by adsorption to active
carbon or other adsorbents. It can be expected that the
presence of high amounts of COD in urine strongly interfere
with the adsorption process (Quinlivan et al., 2005).
3.7.2. ElectrodialysisElectrodialysis membranes are ion-exchange membranes
made of functionalised polymers with a dense structure
(Strathmann 1992) enabling salts to be extracted and con-
centrated (Fig. 12). The apparent pore size is typically around
200Da (Kim et al. 2003) so that these membranes can
potentially retain micropollutants. Investigations showed
that electrodialysis may be used to selectively extract the
nutrients into a concentrated product stream while retaining
the micropollutants (pharmaceuticals) in the diluate (Pronk et
al., 2006a). Experiments with bipolar membranes were carried
Fig. 13 Nanofiltration (Fig. 14 Ozonation andhormones (Nghiem et al. 2004). For production of a urine-
based fertilizer, it is important for the micropollutants to be
retained and for mineral salts to be permeated in order to
obtain a product free of micropollutants. The removal of
micropollutants was tested with different nanofiltration
membranes (Pronk et al. 2006c). The efficiency of the
separation process depends strongly on the pH, demonstrat-
ing that electrostatic interactions with the membrane play
an important role in the separation of micropollutants.
Under optimised conditions, the removal rate of a set of
hormones and pharmaceutical compounds in urine exceeds
92% (Pronk et al. 2006c). Furthermore, it was shown that the
permeation of urea is almost complete, while 5080% of
the ammonia was retained, depending on the pH (Fig. 13). In
order to obtain high nitrogen recoveries, therefore, it is
important to use non-hydrolysed urine (see also Section
Urine Stabilisation).
Fig. 1 for explanation).advanced oxidation.
-
micropollutants from urine.
ARTICLE IN PRESS
( 24. Conclusions and outlook
In this paper, we have reviewed a number of unit processes
for treating human urine with respect to seven different
purposes: hygienisation, volume reduction, stabilisation, P-
recovery, N-recovery, nutrient removal and handling of
micropollutants. The review concentrates on processes that
have actually been tested with human urine at least on a
laboratory scale. Most of the urine treatment options found in
the literature are adapted from existing technologies and
have also been applied to other waste streams. However, the
unique chemical properties of urine make adaptation of
existing processes almost always inevitable. An example is
nitrification, where the conversion of nitrite to nitrate is
mostly inhibited and therefore makes the application of the
anammox process relatively simple.
Our evaluation made clear that a very large number of
technical options are available, with different strengths and
weaknesses. However, all seven purposes cannot be achieved
with a single unit process. Whether the aim is to concentrate
on a specific purpose such as nutrient removal or to combine
different process units to achieve a more comprehensive goal
depends on the circumstances and is not discussed in this
paper.
Hygienisation: Since actual effectiveness has only been
shown for storage, it is difficult to draw any final conclusions.
However, other processes will also be effective: membrane3.7.4. Ozonation and advanced oxidationMicropollutants can be oxidised with chlorine, chlorine
dioxide, ozone (O3), or OH radicals (advanced oxidation
processes, AOPs, see Prousek, 1996). In the case of ozone,
the reaction can take place directly with ozone or with the
secondary oxidants (e.g. OH-radicals) formed during ozona-
tion (Von Gunten 2003a; Von Gunten 2003b). In view of the
high COD content of urine (210g/l, see Table 1), oxidants
reacting specifically with micropollutants are preferred. As
most of the compounds tested show enhanced reactivity
towards ozone (Huber et al. 2003), use of ozone seems to be
preferable to advanced oxidation processes because a larger
fraction of the oxidant (OH radical) is lost to the matrix in the
latter (Fig. 14). From recent investigations with urine, it was
concluded that complete oxidation of a representative set of
micropollutants including pharmaceuticals and synthetic
hormones may be achieved (Pronk et al., 2006d). Despite the
quenching of oxidants by the organic matrix in urine, it was
shown that all the tested compounds could be transformed
completely. At an ozone dose of 1.1 g/l, fast-reacting com-
pounds such as ethinylestradiol were completely removed,
while removal of more recalcitrant compound such as
ibuprofen was 80% (Pronk et al, 2006d). Analysis of the results
showed that oxidation took place directly by ozone as well as
by OH radicals. Considering the high reactivity of the OH
radicals with most organic micropollutants, ozonation can be
regarded as a suitable method for removing a wide range of
WAT E R R E S E A R C H 403162processes (except for reverse osmosis), evaporation at high
temperature, acidification and biological processes all havethe potential to produce a hygienic product, but further
studies are required.
Volume reduction: Precipitation processes obviously repre-
sent the most efficient measures of volume reduction,
reducing the water content to a few percent. Evaporation is
almost as effective, resulting in a water content of 510%,
whereas freeze-thaw, electrodialysis and reverse osmosis are
considerably less effective.
Stabilisation: The most effective stabilisation processes are
acidification and biological processes: they prevent not only
ammonia evaporation but also the typical urine odour.
Struvite precipitation is quite efficient because it produces a
mineral product with little water and a low content of organic
material. Membrane processes (micro and nanofiltration plus
electrodialysis) are effective in preventing further microbial
growth, but require additional measures to prevent odour and
urea hydrolysis by the hydrolysing enzymes already present
in the dissolved urea.
P-recovery: We define a process as a P-recovery technique if
(a) a volume reduction has taken place and (b) the phos-
phorus is concentrated in a small volume. Consequently, the
relevant processes are struvite precipitation, the processes
recorded under volume reduction and electrodialysis, all of
them with a phosphorus recovery rate of between 90% and
100%.
N-recovery: We define N-recovery in an equivalent way to P-
recovery. N-recovery actually takes place in a large number of
processes, but with different yields. At least 90% recovery is
achieved with evaporation, electrodialysis, reverse osmosis
and struvite precipitation (with stoichiometric phosphate
addition). Between 80% and 90% recovery is achieved with
the freeze-thaw process and most likely with ammonia
stripping. An N-recovery of between 60% and 80% is achieved
with reverse osmosis, ion exchange with zeolite and IBDU
precipitation with a five-fold excess of IBU.
Nutrient removal: Only biological processes have been tested
for nutrient elimination. A nitrogen removal efficiency of
7580% is obtained with a combination of partial nitrification
and the annamox process.
Handling of micropollutants: separation from nutrients and
removal: Only chemical oxidation has so far proved effective
for the actual removal of micropollutants from urine, and this
is not entirely beyond doubt. Much work remains to be done.
Results from biological oxidation are still outstanding.
Struvite precipitation, ammonia stripping and nanofiltration
have proved to be highly effective for the separation of
micropollutants and nutrients. IBDU precipitation and elec-
trodialysis are only partially effective; electrodialysis optimi-
sation is proceeding.
Energy consumption: Besides the technical description of the
various options, we also estimated the effectiveness and
energy consumption of these processes. It is obvious that we
had to make a number of assumptions because very few of
these processes have actually been optimised for full-scale
application. As an example, we assumed realistic but
challenging energy recovery schemes resulting in estimated
energy requirements mostly in the order of 20100MJm3
(without the energy used to construct the treatment device),
006 ) 3151 3166with a few exceptions. If we assume a production of 2 l
urine per day and person (including flushing water), this
-
the job in a realistic urine source-separation scenario. Many
of the techniques described in this paper need some sort of
pre-treatment (e.g. evaporation) or only deal with a specific
for substituting phosphorus recovered from wastewater
ARTICLE IN PRESS
(2problematic fraction in the urine (e.g. struvite precipitation).
Urine treatment solutions will most probably consist of a
combination of treatment processes. An example is the
recovery of phosphate by struvite precipitation followed by
a biological process designed to eliminate the organic
pollutants and nitrogen. This enhanced flexibility for urban
wastewater treatment is one of the great benefits of urine
source separation and makes the development of processes
for urine treatment attractive. However, it is impossible to
discuss process combinations without a scenario as context
and since an explicit discussion of scenarios would go way
beyond the scope of this review, a second publication dealing
with this issue is in preparation.
A general assessment of NoMix technology is not possible
on the basis of process engineering technology alone.
However, as we have shown in this paper, the limitations
for NoMix technology will not be found in a lack of NoMix
process engineering options. In most cases, our expectation
that such technologies might be too energy intensive has not
come true either. Although other problems connected to
NoMix technology may be more difficult to solve, one should
not underestimate the efforts of research and development of
NoMix process engineering technologies. Except for evapora-
tion and storage, none of the processes described have yet
advanced beyond the laboratory stage. Considerable develop-
ment work remains to be done in order to enhance urine-
processing techniques into marketable products.
Acknowledgements
The authors wish to thank Urs von Gunten and Detleff
Knappe for their input with respect to the unit operations of
oxidation and activated carbon.
R E F E R E N C E S
Al-Rammah, A., 2000. The application of acid-free antiscalant tomitigate scaling in reverse osmosis membranes. Desalination132, 8387.
Avlonitis, S.A., Kouroumbas, K., Vlachakis, N., 2003. Energycorresponds to approximately 0.52.5W per person. This is
within a reasonable range compared to the approximately
4W per person that we currently apply for nitrification in an
ordinary wastewater treatment plant. A number of other
relevant aspects such as cost and robustness were not
discussed.
The review shows clearly that a wide range of technical
options is available for the effective treatment of collected
urine. Depending on the overall goal of the treatment process,
a specific technical solution or a combination of solutions can
be found to meet the requirements. Additional research is
needed to find promising process combinations that can do
WATER RESEARCH 40consumption and membrane replacement cost for seawaterRO desalination plants. Desalination 157, 151158.Ban, Z.S., Dave, G., 2004. Laboratory studies on recovery of N and P
from human urine through struvite crystallisation and zeolite
adsorption. Environ. Technol. 25 (1), 111121.Behrendt, J., Arevalo, E., Gulyas, H., Niederste-Hollenberg, J.,
Niemiec, A., Zhou, J., Otterpohl, R., 2001. Production of value
added products from separately collected urine. IWAWorldWater Congress, Berlin.
Benini, S., Rypniewski, W.R., Wilson, K.S., Miletti, S., Ciurli, S.,
Mangani, S., 1999. A new proposal for urease mechanismbased on the crystal structures of the native and inhibited
enzyme from bacillus pasteurii: Why hydrolysis costs twonickels. Structure 7 (2), 205216.
Brett, S., Guy, J., Morse, G.K., Lester, J.N., 1997. Phosphorus
Removal and Recovery Technologies. Selper Publication,London, ISBN: 0 94841 110 0.
Bridger, G.L., Salutsky, M.L., Starostka, R.W., 1961. Metal ammo-
nium phosphates as fertilisers. In: Proceedings of the 140thMeeting of the American Chemical Society, Chicago, IL.
Buchanan, J.R., Mote, C.R., Robinson, R.B., 1994. Thermodynamics
of struvite formation. Trans. ASAE 37 (2), 617621.Butzen, A., Werres, F., Balsaa, P., 2005. Aufbau und Einsatz einer
problemorientierten Analytik mit dem Ziel eines Monitorings
ausgewahlter Pharmaka in Boden und Urin (Implementationand application of problem oriented analytical methods with
the goal of monitoring selected pharmaceuticals in soil and
urine, in German). in: Nahrstofftrennung und verwertung inder Abwassertechnik am Beispiel der ,,Lambertsmuhle,
Bonner Agrikulturchemische Reihe, Band 21, p. 2554, Bonn,
Germany, ISBN 3-937941-02-9. Source: Verein zur Forderungder Agrikulturchemie e.V., c/o Institut fur Planzenernahrung,
Karlobert-Kreiten-Strasse 13, 53115 Bonn, Germany.
Christiansen, L.B., Winther-Nielsen, M., Helweg, C., 2002. Femin-isation of fishthe effect of estrogenic compounds and their
fate in sewage treatment plants and nature. Environmental
Project no. 729, Danish Environmental Protection Agency, ISBN87-7972-306-3, download on the internet: http://www.mst.dk/
udgiv/publications/2002/87-7972-305-5/html/default_eng.htm.
Ciba-Geigy, 1977. Wissenschaftliche Tabellen Geigy, TeilbandKorperflussigkeiten (Scientific Tables Geigy. Volume: Body
Fluids), 8th ed. Basel. In German.Dalhammar, G., 1997. Behandling och koncentrering av huma-
nurin (Royal Institute of Technology, Stockholm, Department
of Biochemistry and Biochemical technology), Report, perso-nal communication.
De-Bashan, L.E., Bashan, Y., 2004. Recent advances in removing
phosphorus from wastewater and its future use as fertilizer(19972003). Water Res. 38 (19), 42224246.
Driver, J., Lijmbach, D., Steen, I., 1999. Why recover phosphorus
for recycling, and how? Environ. Technol. 20 (7), 651662.Escher, B.I., Eggen, R.I.L., Schreiber, U., Schreiber, Z., Vye, E.,
Wisner, B., Schwarzenbach, R.P., 2002. Baseline toxicity
(narcosis) of organic chemicals determined by in vitromembrane potential measurements in energy-transducing
membranes. Environ. Sci. Technol. 36, 19711979.
Escher, B.I., Bramaz, N., Maurer, M., Richter, M., Sutter, D., vonKanel, C., Zschokke, M., 2005. Screening test battery for
pharmaceuticals in urine and wastewater. Environ. Toxicol.
Chem. 24, 750758.Escher, B.I., Pronk, W., Suter, M.J.-F., Maurer, M., 2006. Monitoring
the removal efficiency of pharmaceuticals and hormones in
different treatment processes of source-separated urine withbioassays. Environ. Sci. Technol., in press.
Gaterell, M.R., Gay, R., Wilson, R., Gochin, R.J., Lester, J.N., 2000. An
economic and environmental evaluation of the opportunities
006) 3151 3166 3163treatment works in existing UK fertiliser markets. Environ.
Technol. 21 (9), 10671084.
-
ARTICLE IN PRESS
( 2Gulyas, H., Bruhn, P., Furmanska, M., Hartrampf, K., Kot, K.,Luttenberg, B., Mahmood, Z., 2004. Freeze concentration forenrichment of nutrients in yellow water from no-mix toilets.Water Sci. Technol. 50 (6), 6168.
Hanaeus, J., Hellstrom, D., Johansson, E., 1997. A study of a urineseparation in an ecological village in northern Sweden. WaterSci. Technol. 35 (9), 153160.
Harries, J.E., Sheahan, D.A., Jobling, S., Matthiessen, P., Neall, P.,Sumpter, J.P., Tylor, T., Zaman, N., 1997. Estrogenic activity infive United Kingdom rivers detected by measurement ofvitellogenesis in caged male trout. Environ. Toxicol. Chem. 16,534542.
Heinonen-Tanski, H., vanWijk-Sijbesma, C., 2005. Human excretafor plant production. Bioresource Technol. 96 (4), 403411.
Hellinga, C., van Loosdrecht, M.C.M., Heijnen, J.J., 1999. Modelbased design of a novel process for nitrogen removal fromconcentrated flows. Math. Comput. Model. Dyn. Syst. 5 (4),351371.
Hellstrom, D., Johannson, E., Grennberg, K., 1999. Storage ofhuman urine: acidification as a method to inhibit decom-position of urea. Ecol. Eng. 12, 253269.
Hofman, J., Beerendonk, E.F., Folmer, H.C., Kruithof, J.C., 1997.Removal of pesticides and other micropollutants with cellu-lose-acetate, polyamide and ultra-low pressure reverse os-mosis membranes. Desalination 113, 209214.
Hoglund, C.E., Stenstrom, T.A.B., 1999. Survival of cryptospor-idium parvum oocysts in source separated human urine. Can.J. Microbiol. 45, 740746.
Hoglund, C., Stenstrom, T.A., Jonsson, H., Sundin, A., 1998.Evaluation of faecal contamination and microbial die-off inurine separating sewage systems. Water Sci. Technol. 38 (6),1725.
Hoglund, C., Vinneras, B., Stenstrom, T.A., Jonsson, H., 2000.Variation of chemical and microbial parameters in collectionand storage tanks for source separated human urine. J.Environ. Sci. Health Part A-Toxic/Hazard. Substances Environ.Eng. 35, 14631475.
Hoglund, C., Ashbolt, N., Stenstrom, T.A., Svensson, L., 2002a.Viral persistence in source-separated human urine. Adv.Environ. Res. 6, 265275.
Hoglund, C., Stenstrom, T.A., Ashbolt, N., 2002b. Microbial riskassessment of source-separated urine used in agriculture.Waste Manage. Res. 20, 150161.
Holland, P.J., Bird, D.M., Miller, C.L., 1992. Extraction of potablewater from urine for space applications. In: Sadeh, W.Z., Sture,S., Miller, R.J. (Eds.), Engineering, construction, and operationsin space III: Space 92; Third International Conference, vol. 2.American Society of Civil Engineers (ASCE), Denver, CO andNew York, USA, pp. 16801689.
Huang, D., Bader, H., Scheidegger, R., Schertenleib, R., Gujer, W.,(2006). Confronting limitations: new solutions required inurban water management of a Chinese mega-city. J. Environ.Manage, in press.
Huber, M.M., Canonica, S., Park, G.Y., Von Gunten, U., 2003.Oxidation of pharmaceuticals during ozonation and advancedoxidation processes. Environ. Sci. Technol. 37, 10161024.
Hunik, J.H., Meijer, H.J.G., Tramper, J., 1993. Kinetics of nitrobacteragilis at extreme substrate, product and salt concentrations.Appl. Environ. Microbiol. 40 (23), 442.
Isherwood, K.F., 2000. Mineral fertilizer use and the environment.International Fertilizer Industry Association/United NationsEnvironment Programme, Paris, 106 pp.
Jaffer, A.E., 1994. The application of a novel chemical treatmentprogram to mitigate scaling and fouling in reverse-osmosisunits. Desalination 96, 7179.
WAT E R R E S E A R C H 403164Johansson, E., Hellstrom, D., 1999. Nitrification in combinationwith drying as a method for treatment and volume reductionof stored human urine. In: Johansson, E. (Ed.), Urine separatingwastewater systems: design experiences and nitrogen con-servation. Licentiate Thesis. Lulea University of Technology,Lulea, Sweden.
Johnston, A.E., Richards, I.R., 2003. Effectiveness of differentprecipitated phosphates as phosphorus sources for plants.Soil Use Manage. 19 (1), 4549.
Jonsson, H., Stenstrom, T.A., Svensson, J., Sundin, A., 1997. Sourceseparated urine-nutrient and heavy metal content, watersaving and faecal contamination. Water Sci. Technol. 35 (9),145152.
Jorgensen, T.C., Weatherley, L.R., 2003. Ammonia removal fromwastewater by ion exchange in the presence of organiccontaminants. Water Res. 37 (8), 17231728.
Kim, D.H., Moon, S.-H., Cho, J., 2003. Investigation of theadsorption and transport of natural organic matter (NOM) inion-exchange membranes. Desalination 151, 1120.
Kimura, K., Toshima, S., Amy, G., Watanabe, Y., 2004. Rejection ofneutral endocrine disrupting compounds (EDCs) and phar-maceutical active compounds (PhACs) by RO membranes. J.Membrane Sci. 245, 7178.
Kirchmann, H., Pettersson, S., 1995. Human urinechemicalcomposition and fertilizer use efficiency. Fertilizer Res. 40,149154.
Kiso, Y., Kon, T., Kitao, T., Nishimura, K., 2001. Rejection propertiesof alkyl phthalates with nanofiltration membranes. J. Mem-brane Sci. 182, 205214.
Larsen, T.A., Gujer, W., 1996. Separate management of anthro-pogenic nutrient solutions (human urine). Water Sci. Technol.34 (34), 8794.
Larsen, T.A., Gujer, W., 2001. Waste design and source control leadto flexibility in wastewater management. Water Sci. Technol.43 (5), 309318.
Larsen, T.A., Lienert, J., 2003. Societal implications of re-engineer-ing the toilet. Water Intelligence Online. UNIQUE ID:200303006. http://www.iwaponline.com/wio/2003/03/de-fault001.htm.
Larsen, T.A., Lienert, J., Joss, A., Siegrist, H., 2004. How to avoidpharmaceuticals in the aquatic environment. J. Biotechnol.113 (13), 295304.
Liberti, L., Boari, G., Petruzzelli, D., Passino, R., 1981. Nutrientremoval and recovery from wastewater by ion exchange.Water Res. 15, 337342.
Lind, B.B., Ban, Z., Byden, S., 2000. Nutrient recovery from humanurine by struvite crystallization with ammonia adsorption onzeolite and wollastonite. Bioresource Technol. 73 (2), 169174.
Lind, B.B., Ban, Z., Byden, S., 2001. Volume reduction andconcentration of nutrients in human urine. Ecol. Eng. 16 (4),561566.
Maurer, M., Muncke, J., Larsen, T.A., 2002. Technologies fornitrogen recovery and reuse. In: Lens, P., Pol, L.H., Wilderer,P., Asano, T. (Eds.), Water Recycling and Resource Recovery inIndustry. IWA Publishing, London, pp. 491510.
Maurer, M., Schwegler, P., Larsen, T.A., 2003. Nutrients in urine:energetic aspects of removal and recovery. Water Sci. Technol.48 (1), 3746.
Mayer, M., 2002. Thermische Hygienisierung und Eindampfungvon Humanurin. Diplomarbeit des Institut fur Umweltechnikder Fachhochschule beider Basel, Muttenz, Schweiz (Thermaldisinfection and evaporation of human urine. Diploma workof the Institute for Environmental Technology, Fach-hochschule beider Basel, Muttenz, Switzerland).
McBride, M.B., Spiers, G., 2001. Trace element content of selectedfertilizers and dairy manures as determined by ICP-MS.Commun. Soil Sci. Plant Anal. 32 (1&2), 139156.
Medilanski, E., Chuan, L., Mosler, H., Schertenleib, R., Larsen, T.A.,
006 ) 3151 3166(2006). Wastewater Management in Kunming, China: Feasi-bility and Perspectives of Measures at the Source from aStakeholder Point of View. Environ. Urban., 18(2), in press.
-
ARTICLE IN PRESS
(2Migliorini, G., Luzzo, E., 2004. Seawater reverse osmosis plant
using the pressure exchanger for energy recovery: a calcula-
tion model. Desalination 165, 289298.NASA, 1977. Electrolytic pretreatment of urine. Prepared by
Lockheed Missiles & Space Co., NASA Report no. NASA-CR-
151566, Johnson Space Center, USA.Nghiem, L.D., Schafer, A.I., Elimelech, M., 2004. Removal of
natural hormones by nanofiltration membranes: measure-
ment, modeling, and mechanisms. Environ. Sci. Technol. 38,18881896.
Peter-Frohlich, A., 2002. Sanitation concept for separatetreatment (SCST), [email protected], http://
www.kompetenz-wasser.de/dt/projekte/proj_scst.html.
Pronk, W., Biebow, M., Boller, M., 2006a. The application ofelectrodialysis for the recovery of salts from a micropollu-
tant-containing urine solution. Environ. Sci. Technol., in press.
Pronk, W., Biebow, M., Boller, M., 2006b. Treatment of source-separated urine by a combination of bipolar electrodialysis
and a gas transfer membrane. Water Sci. Technol. 53 (3),
139146.Pronk, W., Palmquist, H., Biebow, M., Boller, M., 2006c. Nanofiltra-
tion for the separation of pharmaceuticals from nutrients in
source-separated urine. Water Res. 40 (7), 14051412.Pronk, W., Dodd, M., Zuleeg, S., Escher, B., Von Gunten, U., 2006d.
The ozonation of micropollutants in source-separated urine,
in preparation.Prousek, J., 1996. Advanced oxidation processes for water treat-
ment. Photochemical processes. Chem. Listy 90, 307315.
Quinlivan, P.A., Li, L., Knappe, D.R.U., 2005. Effects of activatedcarbon characteristics on the simultaneous adsorption of
aqueous organic micropollutants and natural organic matter.
Water Res. 39, 16631673.Reichl, H., 2002. Prion transmission in blood and urine: what are
the implications for recombinant and urinary-derived gona-
dotrophins? Fertil. Steril. 78 (Suppl. 1), 179.Reinhart, 2002. BASF Agricultural Products, Germany, Personal
communication.
Ritschel, W.A., Kearns, G.L., 1999. Handbook of basic pharmaco-kinetics. American Pharmaceutical Association, Washington,
DC.Rogowski, D., Golding, S., Bowhay, D. and Singleton, S., 1999.
Screening survey for metals and dioxins in fertilizer products
and soils in Washington StateFinal report. Washington StateDepartment of Ecology, Ecology Publication no. 99309,
Olympia, Washington, USA., Internet: http://www.ecy.wa.gov/
biblio/99309.html, last updated 11 May 2004)Ronteltap, M., Biebow, M., Maurer, M., Gujer, W., 2003. Thermo-
dynamics of struvite precipitation in source separated urine.
In: Second International Symposium on Ecological Sanitation,IWA, gtz, Lubeck, Baltic Sea, Germany, pp. 463470.
Ronteltap, M., Maurer, M., Gujer, W., 2006. Struvite precipitation
thermodynamics in source-separated urine. Submitted toWater Res.
Rulkens, W.H., Klapwijk, A., Willers, H.C., 1998. Recovery of
valuable nitrogen compounds from agricultural liquidwastes: potential possibilities, bottlenecks and future tech-
nological challenges. Environ. Pollut. 102 (Suppl. 1), 727735.
Santos, R.L.S., Manfrinatto, J.A., Cia, E.M.M., Carvalho, R.B.,Quadros, K.R.S., Alves-Filho, G., Mazzali, M., 2004. Urine
cytology as a screening method for polyoma virus active
infection. Transplant. Proc. 36 (4), 899901.Schonning, C., Leeming, R., Stenstrom, T.A., 2002. Faecal con-
tamination of source-separated human urine based on the
content of faecal sterols. Water Res. 36, 19651972.
WATER RESEARCH 40Siegrist, H., 1996. Nitrogen removal from digester supernatant
comparison of chemical and biological methods. Water Sci.
Technol. 34, 399406.Silva, E., Rajapakse, N., Kortenkamp, A., 2002. Something fromnothingeight weak estrogenic chemicals combined atconcentrations below NOECs produce significant mixtureeffects. Environ. Sci. Technol. 36, 17511756.
Slavin, T.J., Oleson, M.W., 1991. Technology tradeoffs related toadvanced mission waste processing. Waste Manage. Res. 9 (5),401414.
Smil, V., 2000. Phosphorus in the environment: natural flowsand human interferences. Annu. Rev. Energy Environ. 25,5388.
Steen, I., Steen, P., 1998. Phosphorus availability in the 21stcentury: management of a nonrenewable resource. Phos-phorus Potassium 217, 2531.
Strathmann, H., 1992. Ion-exchange membranes. In: Winston,W.S.S., Ho, K.K. (Eds.), Membrane Handbook. Chapman & Hall,New York, London, pp. 230245.
Strous, M., Heijnen, J.J., Kuenen, J.G., Jetten, M.S.M., 1998. Thesequencing batch rector as a powerful tool for the study ofslowly growing anaerobic ammonium-oxidizing microorgan-isms. Appl. Microbiol. Biotechnol. 50 (5), 589596.
Suzuki, K., Tanaka, Y., Osada, T., Waki, M., 2002. Removal ofphosphate, magnesium and calcium from swine wastewaterthrough crystallization enhanced by aeration. Water Res. 36(12), 29912998.
Thorneby, L., Persson, K., Tragardh, G., 1999. Treatment of liquideffluents from dairy cattle and pigs using reverse osmosis.J. Agric. Eng. Res. 73 (2), 159170.
Udert, K.M., Larsen, T.A., Biebow, M., Gujer, W., 2003a. Ureahydrolysis and precipitation dynamics in a urine-collectingsystem. Water Res. 37 (11), 25712582.
Udert, K.M., Larsen, T.A., Gujer, W., 2003b. Biologically inducedprecipitation in urine-collecting systems. Water Sci. Technol.:Water Supply 3, 7178.
Udert, K.M., Fux, C., Munster, M., Larsen, T.A., Siegrist, H.,Gujer, W., 2003c. Nitrification and autotrophic denitri-fication of source-separated urine. Water Sci. Technol. 48 (1),119130.
Udert, K.M., Larsen, T.A., Gujer, W., 2005a. Fate of majorcompounds in source-separated urine. Presented and pub-lished in the Proceedings of the Fourth World Water Congress,Marrakech, Morocco, September 2004; accepted for publica-tion in Water Sci. Technol.
Udert, K.M., Larsen, T.A., Gujer, W., 2005b. Chemical nitriteoxidation in acid solutions as a consequence of microbialammonium oxidation. Environ. Sci. Technol. 39, 40664075.
Valsami-Jones, E. (Ed.), 2004. Phosphorus in EnvironmentalTechnologyPrinciples and Applications. IWA Publishing,London, UK.
Vanchiere, J.A., White, Z.S., Butel, J.S., 2005. Detection of BK virusand simian virus 40 in the urine of healthy children.J. Med.Virol. 75 (3), 447454.
Van der Bruggen, B., Everaert, K., Wilms, D., Vandecasteele, C.,2001. Application of nanofiltration for removal of pesticides,nitrate and hardness from ground water: rejection propertiesand economic evaluation. J. Membrane Sci. 193, 239248.
Van Hulle, S., 2005. Modelling, simulation and optimization ofautotrophic nitrogen removal processes. Ph.D. Thesis, Facultyof Bioengineering Sciences, Ghent University, pp. 228. Down-load on the Internet: http://biomath.rug.ac.be/publications/download/vanhullestijn_phd.pdf.
von Gunten, U., 2003a. Ozonation of drinking water: part I.Oxidation kinetics and product formation. Water Res. 37,14431467.
von Gunten, U., 2003b. Ozonation of drinking water: part II.Disinfection and by-product formation in presence of bro-
006) 3151 3166 3165mide, iodide or chlorine. Water Res. 37, 14691487.Wieland, P.O., 1994. Designing for human presence in spacean
introduction to environmental control and life support
-
systems. NASA RP-1324, Appendix E/F, 227-251. Download onthe web: http://trs.nis.nasa.gov/archive/00000204/01/rp1324.pdf, e-mail author: [email protected].
Wilsenach, J. A., Schuurbiers, C. A. H., van Loosdrecht, M. C. M.,(submitted) Phosphate and potassium recovery from sourceseparated urine through struvite precipitation. Submitted toWater Res.
Wilsenach, J., Van Loosdrecht, M., 2002. Separate urine collectionand treatmentoptions for sustainable wastewater systemsand mineral recovery. STOWA Report no. 2001-39, STOWA,Utrecht, ISBN 90-5773-197-5
Wilsenach, J.A., Van Loosdrecht, M.C.M., 2004. Effects of separateurine collection on advanced nutrient removal processes.Environ. Sci. Technol. 38 (4), 12081215.
Wood, F.C., 1982. The changing face of desalinationa consultingengineers viewpoint. Desalination 42, 1725.
Wu, Q.Z., Bishop, P.L., 2005. Enhancing struvite crystallizationfrom anaerobic supernatant. J. Environ. Eng. Sci. 3 (1), 2129.
Zapata, F., Roy R.N., 2004. Use of phosphate rocks for sustainableagriculture. FAO of the United Nations, Rome, p. 172, ISBN 92-5-105030-9. On the Internet: http://www.fao.org/documents/show_cdr.asp?url_file=/docrep/007/y5053e/y5053e00.htm.
ARTICLE IN PRESS
WAT E R R E S E A R C H 40 ( 2006 ) 3151 31663166
Treatment processes for source-separated urineIntroductionComposition of urineTreatment unitsHygienisationIntroductionStorage
Volume reductionIntroductionEvaporationFreeze-thawReverse osmosis
StabilisationIntroductionAcidificationPartial nutrification
P-recoveryIntroductionStruvite (MgNH4PO4)
N-recoveryIntroductionIon exchangeAmmonia strippingIsobutylaldehyde-diurea (IBDU) precipitation
Nutrient removal (P and N)IntroductionAnammox Process
Removal of micropollutantsIntroductionElectrodialysisNanofiltrationOzonation and advanced oxidation
Conclusions and outlookAcknowledgementsReferences