Greywater Reuse Towards Sustainable Water Management
Content
DESALINATION
ELSEVIER
Desalination I56 (2003) 18 l-l 92
www.elsevier.comAocate/desal
Greywater reuse: towards sustainable water management
Odeh R. Al-Jayyousi
Civil Engineering Department, College of Engineering, Applied Science University, Amman I1 931 Jordan
Fax: +962 (6) 523-2899; email: [email protected]/[email protected]
Received 2 January 2003; accepted 15 January 2003
Abstract
The aim of this paper is to assess the role of greywaterreuse in sustainablewater management in arid regions.
Moreover,it intendsto documentthe experienceof greywaterreuse in Jordan.Creywater(GW) is the water collected
separatelyfrom sewageflow that originatesfrom clotheswashers,bathtubs,showersand sinks, but does not include
wastewatertirn kitchen sinks, dishwashers,or toilets. Dish, shower, sink, and laundry water comprise 5040% of
residentialwastewater.GW is used in groundwaterrecharge,landscaping,and plant growth.A case study on GW reuse
in Jordan is presentedto shed some lightson its role in sustainablewatermanagement.To operationalizethis concept,
wateris viewedas an economicgood and a finiteresourcethat shouldbe valuedand managedin a rationalmanner.The
studyconcluded that currentenvironmentalpoliciesshouldaimto controlpollutionandto maximizerecyclingandreuse
of GW withinhouseholdsand communities.DecentralizedGW/wastewatermanagementoffersmore opportunitiesfor
maximizingrecyclingopportunities.
Keyworak
Greywaterreuse; Sustainablewater management;Watermanagement;Jordan
1. Introduction
Historically, domestic greywater reuse was
practiced to conserve water. However, social and
economic constraints prevented its further
development and integration in the urban water
systems [ 11. It is likely that new innovations in
water management will eventually lead to
substantial changes in lifestyle, particularly if the
use of water as a transport medium for our
domestic waste is reduced or eliminated [2].
The conventional paradigm of water/wastewater management was characterized as supplydriven, centralized and large-scale development.
This approach led to over-exploitation or
depletion of renewable water resources, mining
of non-renewable groundwater resources and
deterioration of water quality. The collection and
disposal mind-set prevailed because of concerns
over public health protection. Water-intensive
and centralized sewer systems were built to
Presented at the European Conference on Desalination and the Environment: Fresh Waterfor All, Malta, 4-8 May 2003.
European Desalination Society International Water Association.
001 l-9164/03/$-
See front matter 0 2003 Elsevier Science B.V. All rights reserved
PII: SO01 1-9164(03)00340-O
182
O.R. Al-Jayyousi / Desalination 156 (2003) 181-192
remove wastewater from immediate environment
of the communities using water as a transport
medium. This paradigm is inadequate for sustainable water management. A need for a paradigm shift is necessary to ensure optimum
utilization of resources [3-51.
Wastewater and greywater (GW) recycling are
emerging as integral parts of water demand
management, promoting the preservation of highquality fresh water as well as reducing pollutants
in the environment and reducing overall supply
costs. Recent developments in technology and
changes in attitudes towards water reuse suggest
that there is potential for GW reuse in the
developing world.
GW represents the largest potential source of
water savings in domestic residence. For example, the reuse of domestic GW for landscape
irrigation makes a significant contribution
towards the reduction of potable water use. In
Arizona, for example, it is documented that an
average household can generate about 30,000 to
40,000 gallons of GW per year [6]. This illustrates the immense potential amounts of water
that may be reutilized, especially in arid regions
like the Middle East.
Domestic G reuse offers an attractive option
in arid and semi-arid regions due to severe water
scarcity, rainfall fluctuation, and the rise in water
pollution. To ensure sustainable water management, it is crucial to move towards the goal of
efficient and appropriate water use. GW reuse
contributes to promoting the preservation of
high-quality fresh water as well as reducing
pollutants in the environment. Meeting different
needs with the appropriate quality of water may
prove to be economically beneficial and at the
same time reduce the need for new supplies at a
higher marginal cost. Mixing GW with rainwater
is a viable practice; however, since rainwater is
generally of high quality (COD<200 mg/l), the
stochastic nature of rainfall events implies a large
storage capacity is necessary for its optimum use
[7]. Conversely, domestic GW often has a higher
pollutant load (up to 5000 mg/l COD) but is
produced according to more regular patterns,
which are simpler to exploit for the purposes of
domestic reuse [8]. GW reuse can result in cost
savings (to both the consumer and state water
authority), reduced sewage flows and potable
water savings of up to 3 8% when combined with
sensible garden design [9].
The aim of this paper is to assess the role of
RW reuse in sustainable water management in
arid regions, particularly documenting Jordan’s
experience in GW reuse.
2. Characterization of greywater
GW is the wastewater collected separately
from sewage flow from clothes washers, bathtubs, showers and sinks, but does not include
wastewater from kitchen sinks, dishwashers, or
toilets. Dish, shower, sink, and laundry water
comprise 50--80% ofresidential wastewater. GW
may be used in groundwater recharge, landscaping, and plant growth.
Due to the fact that GW is usually generated
by the use of soap or soap products for body
washing, its quality varies according to source,
geographical location, demographics and level of
occupancy, as shown in Table 1. GW is relatively
low in suspended solids and turbidity, indicating
that a greater proportion of the contaminants are
dissolved. Moreover, although the concentration
of organics is somewhat similar to domestic
wastewater, their chemical nature is quite different. The COD:BOD ratio may be as high as
4: 1 (very much greater than values reported for
sewage). This is coupled with a deficiency of
macro-nutrients such as nitrogen and phosphorus.
The COD:NH,:P of GW has been measured at
1030:2.7:1, and this compares with 1OO:S:l for
domestic wastewater. Hence, both the relatively
low values of biodegradable organic matter and
the nutrient imbalance limit the effectiveness of
biological treatment [ 131.
183
0.R Al-Jayyousi 1 Desalination 156 (2003) 181-192
Table 1
Typical composition of greywater from various sources
Source
Hand basin
Combined
Synthetic greywater
Single personb
Single family’
Block of flatsb
Collegeb
Large colleged
“Total nitrogen.
COD (mg/l)
Turbidity (NTU)
109
121
181
110
-
263
371
-
-
33
80
96
40
146
168
_ Bob
(w4
256
-
69
25
14
76.5
20
59
57
bHolden and Ward [lo]. ‘Sayers [ll].
In sum, GW reuse helps to conserve and
optimize the use of water resources. However,
GW treatment and reuse are to be assessed in
terms of technical feasibility, public health,
social acceptability and sustainability.
NH3(mg/l) P (m.0
Total coliforms
9.6”
1
0.9
2.58
0.36
-
1.5x106
-
0.74
10
10
0.8
9.3
0.4
-
1x106
-
2.4
5.2x106
-
dSurendan and Wheatley [ 121.
r .-.
3. Conceptual framework for greywater reuse
It is interesting to look at the dynamics of
water/wastewater allocations and their uses.
Governments allocate substantial amounts of
money to develop, treat and transport water
resources. On the other hand, more money is
spent to collect wastewater, treat it and then
transport it to distant places for potential uses. To
address the externalities of this paradigm, attention is to be focused on small-scale and on-site
treatment of waste/GW [ 141.
The following conceptual framework for GW
reuse is based on the closed-loop concept. This
implies that GW is being managed and reused in
a decentralized manner within the household,
neighborhood, and/or community.
The concept of closed loop in water demand
management was documented by Bakir [ 15J. The
main idea is to match water quality with appropriate water uses as shown in Fig. 1. In other
words, GW may be allocated for appropriate uses
Fig. 1. Schematic diagram for a closed water loop for a
residential building [ 151.
such as, irrigation, landscaping, toilet flushing,
and groundwater recharge.
4. Treatment of greywater
Based on the work of Nolde and Dott [ 161,
GW from recycling systems should fulfill four
criteria: hygienic safety, aesthetics, environmental tolerance, and technical and economical
feasibility. In most countries, guidelines and
standards for water reuse in buildings either do
not exist or are being revised or expanded. In
1992 the US Environmental Protection Agency
(EPA) published “Guidelines for Water Quality”
that describes the treatment stages, water quality
184
O.R. Al-Jayyousi / Desalination 156 (2003) 181-192
requirements and monitoring tools [ 171.According to the EPA, reclaimed water used for toilet
flushing should undergo eventual filtration and
disinfection. The effluent should have no detectable fecal coliforms in 100 ml of the treated
water, a BOD of <IO mgll’ and a residual Cl, of
>l mgl-’ whereby Cl, should be continuously
monitored.
Options for making safe use of GW as a
source for irrigation are many and diverse. A key
to successful GW treatment lies in its immediate
processing and reuse before it has reached the
anaerobic state. The simplest GW treatment
consists of directly introducing freshly generated
GW into an active, live topsoil environment.
Many new technologies have been developed to
treat GW. Some of these technologies include
Planter soilbox design and pressure leach
chambers.
The major difficulty presented for treatment
of GW is the large variation in its composition.
Reported mean COD values vary from 40 to
371 mg/l between sites, with similar variations
arising at an individual site. This has been
attributed to changes arising in the quantity and
type of detergent products employed during
washing. GW quality is also subjected to
dynamic variation. Significant chemical changes
may take place over time periods of only a few
hours. Table 2 shows a summary of water quality
standards for domestic water recycling.
The rationale for treating GW is based on
biological characterization of GW. It has been
documented that GW can contain at least 10’1
100 ml of potentially pathogenic microorganisms
[ 18-201. It is also accepted that stored GW
undergoes changes in quality which include
growth in numbers ofmicro-organisms according
to the limiting factors for each particular microorganism. Research has shown that counts of
total coliform and faecal coliforms increased
from 1O”-lo’/1 00 ml to above 1OS/100 ml within
48 h in stored GW from various sources. Of more
concern is the potential infection route that GW
provides for viral infections. Viruses comprise a
serious risk to health, which is amplified by the
relatively low dose required to cause infection.
In light of the amounts of GW that are
possible for reuse and the viability of its application, many technologies have been developed.
Processes range from simple systems in single
houses to very advanced treatment schemes for
large-scale reuse. Work conducted by the
National Aeronautics and Space Administration
demonstrated how bath and laundry water could
be reused by passing the water through diatomaceous earth filters followed by activated
carbon [21,22].
Model guidelines for domestic GW reuse in
Australia have been prepared [22]. These cover
hand basin toilets, primary GW systems (direct
subsurface application) and secondary GW
systems (mesh, membrane or sand filtration).
The following is a description of the most
common GW treatment technologies.
4.1. Basic two-stage systems
Coarse filtration plus disinfection represents
the most common technology used for domestic
reuse in the UK. The generic process employs a
short residence time so that the chemical nature
of the GW remains unaltered and only minimal
treatment is required. The coarse filter usually
comprises a metal strainer. Disinfection is
achieved using either chlorine or bromine, dispensed in slow release blocks or by dosing a
liquid solution. Systems recently tested [ 111have
shown a variety of water saving levels ranging
from 3.4% to 33.4%.
The basic two-stage system was designed to
meet the less stringent reuse standards akin to
those for bathing water, rather than the more
conservative standards. The water thus remains
high in organic load and turbidity, thereby
limiting the effectiveness of the chemical disinfection process for two reasons. Firstly, GW
contains flocculent particles above 40 mm in
0. R. Al-Jayyousi / Desalination 156 (2003) 181-l 92
185
Table 2
Summary of water quality standards and criteria suitable for domestic water recycling (adapted from [ 121)
Bathing water
Standards”
USA, NSF
USA, EPA
Australia
UK (BSIRA)
Japan
WHO
Germany
Total coliform count/
100 ml
Faecal
coliforms
BOD,
(mg/J)
Turbidity
(NTU)
Cl, residual
(mg/l)
pH
10,000(“~
5000
-
2000’”
loo@’
~240
<4
<lo
-
-
-
-
6-9
45
10
20
-
90
2
2
-
1
-
-
10
-
5
-
-
6-9
-
500
20
l-2
-
6-9
Non-detectable
<l
Non-detectable
<lo
1000’“’
200’”
100
6-9
-
“Bathing water standards suggested as appropriate for domestic water recycling.
(g), guideline, (m), mandatory.
and these are known to reduce chemical disinfection capability because the disinfection cannot diffuse far enough into the floes to
provide complete killing of pathogens. Secondly,
organic matter in the water requires a disinfectant. In the case of chlorine, disinfectant byproducts such as chloramines and trihalomethanes are generated, which have a lower
disinfectant capability and adversely affect
human health. Additional problems occur due to
the presence of detergents that are known to
produce an odor in water at concentrations above
3 mg.
Since physical processes achieve substantial
clarification of water, they are reasonably effective in decreasing the organic pollutant load of
GW prior to reuse, since this is to some extent
associated with turbidity. The aesthetic quality of
the product water is thus increased and problems
associated with downstream disinfection encountered in the coarse filtration systems substantially
ameliorated. On the other hand, simple filtration
based on fibrous (cloth) of granular depth filter
presents no absolute barrier to suspended matter,
resulting in coliform breakthrough and a propen-
diameter,
sity for solids unloading whenever hydraulic
shocks occur.
Membrane systems offer a permanent barrier
to suspended particles greater than the size of
membrane material, which can range from
0.5 mm of microfiltration membranes down to
molecular dimensions for reverse osmosis. The
treated water is thus generally extremely low in
turbidity below the limit of detection for coliforms, as shown in Table 3. On the other hand,
the energy demand for membrane systems is
substantially higher than that for depth filters: the
data shown in Table 3 refer to tubular MFAJF
systems, the most commonly used, which are
operated at pressures up to 2.0 bar.
Problems of poorly treated water quality have
been reported with membrane systems treating
GW water, as well as difficulties in effectively
cleaning membranes. The residence time of the
system has been identified as being a major cause
for concern. Over extended time periods, the GW
can become anaerobic, resulting in the generation
of organic components which are less readily
rejected by the membrane [lo].
186
0. R. Al-Jayyousi / Desalination I56 (2003) 181-l 92
Table 3
Performance of sand filter and membrane filtration processes for greywater treatment
~.~_.~-___~~_._._~
~__~__~__._~__~_~.
~ .~~~._. ~~~.~ ~_ ~
Influent”
Post-sand filter
Post-membrane
Influent
Post-membrane
Pre-advanced oxidationb
Post-advanced oxidationb
Pre-coagulationd
Post-coagulationd
-
BOD, Ow4
COD (mg/l)
33.3
12.3
4.7
25-185
l-19
41 (TOC)
25 (TOC)
____
143
35.7
22.2
86-410
21-l 12
100
30
Turbidity
__44.5
32.3
0.34
12-100
Cl
29.4
2.41
TC (cfu/lOO ml)
_._.._.__.~~~_____~.._~
0 E. Coli
2-310~10~
ND-2419
9x105
ND’
-
“Holden and Ward [lo].
bBasedon a 2 g/I concentration of Tio2 activated by an UV irradiation source.
“Non-detectable.
dBased on a ferric chloride dose of 30 mg/l.
The key factor constraining the economic
viability of membrane systems is the fouling of
the membrane surface by pollutants species. This
increases the hydraulic resistance of the membrane, thereby commensurately increasing the
energy demanded for membrane permeation
and/or decreasing the permeate flux.
4.2. Biological systems
Biological treatment is required to remove
biodegradable material, especially for systems
that include large distribution networks such as
hotels or community-based recycling schemes.
The benefits of biological and physical treatments are combined in processes such as membrane bioreactors (MBR) and biologically aerated
filters (BAF), which are small footprint processes
capable of producing high-quality effluents.
BAFs combine depth filtration with a fixed film
biological reactor. As such, they present no absolute barrier to suspended materials and thus do
not substantially disinfect the water. MBRs
combine an activated sludge reactor with a
microfiltration membrane, and have been successfully employed in Japan for GW recycling in
office blocks and residential buildings [23].
The MBR process can be configured with the
membrane placed within the reactor (submerged
MBR) or by externally to it (sidestream MBR).
The two systems show similar biological performance but membrane permeation differs between
them. The external systems are run at higher
transmembrane pressures, producing higher flow
rates that exacerbate fouling problems and thus
necessitate regular cleaning. The internal systems
are operated hydraulically, generating much
lower flow rates which are, however, stable,
thereby reducing membrane cleaning requirements to once in every 6 months as opposed to
monthly, weekly or even daily for the side steam
configuration operating in cross-flow mode.
The complexity of the technology applied is
generally commensurate with the scale of the
recycling scheme. Cost implications have meant
that single-house systems are largely restricted to
coarse filtration devices with downstream disinfection. The current emphasis is on simple and
0. R. Al-Jayyousi/Desalination156 (2003) 181-l 92
reliable systems. Installations in colleges and
small offices have focused on physical or simple
biological systems, and these have been shown to
be far more economically viable than singlehouse systems. The scheme in Lt.&borough, for
example, has reported a payback time between 5
and 10 years [12].
More than 20 units have been tested in Jordan,
Tafileh Governorate. Two types of GW systems
were installed and are being monitored [24], and
a preliminary environmental assessment of GW
in Jordan was conducted [4].
5. International
experience of greywater reuse
On the global scene, Japan, the US and
Australia maintain the highest profile in GW
reuse [8]. Other countries involved in active GW
research and applications include Canada, the
UK, Germany and Sweden [14,25-271. On the
regulatory and legal arena, GW reuse has gained
a degree of acceptance in the US and Australia.
This is evident in the California Pumping Code
and in the Australian general guidelines for
domestic GW reuse [8]. At the regional level,
Saudi Arabia, Cyprus, and Jordan have introduced GW systems to optimize water use. However, guidelines and technical specifications are
still underway.
It should be noted that each country has a
different reason for the adoption of GW reuse.
For example, the Japanese reuse initiative is
driven by the demands of a high population
density and small land space, while the US,
Australian, Saudi Arabian and Jordanian initiatives are a direct response to drought conditions
and the unregulated uptake of domestic GW
reuse for garden irrigation. However, it seems
that certain GW reuse initiatives are not focused
directly upon attaining a more sustainable future;
rather they are short-term reactions to water
scarcity.
The main use for GW in Germany is for toilet
flushing, irrigation and garden plants. In terms of
187
treatment of GW, some manufacturers of GW
systems assume a mechanical treatment of the
GW to be satisfactory [28], whereas others claim
a more advanced treatment technology to be
necessary. GW recycling plants have proved their
efficiency and applicability in practice for almost
10 years.
Current on-site treatment systems have generally adopted the technology of conventional
activated sludge plants for large treatment systems. This is understandable because the effluent
standard for garden surface irrigation is a
chlorinated effluent containing not more than
20 BOD130SS. Differences that can be observed
are the insertion of a trickling filter in the aeration chamber to cope with variable flows and the
infrequent removal of sludge. The anaerobic
decomposition of sludge takes place in the first
settling chamber. Hyper-chlorination of ammonium in secondary effluent theoretically removes
N by oxidation to nitrogen gas.
Following successful operation of these
systems and achievement of the set criteria,
guidelines for service water reuse were then first
introduced in Germany in 1995 on a local level
by the Berlin Senate Department for Building and
Housing. Parameters were defined among others
for BOD, <5 mg/l’, total coliforms ~100 ml-‘,
faecal coliforms ~10 ml-’ and Pseudomonas
ueruginosa <l ml-‘.
In Tokyo, Japan, the reuse of treated wastewater has been highly promoted. A typical use of
the reclaimed water is for toilet flushing with
about 970,000 m’/y-‘. Reclaimed water criteria
for use in toilet flushing were defined in the
“Report on reuse of treated wastewater” among
others for total coliforms (Cl000 ml-‘) and BOD
(a0 mgl--I). However, in arid regions, the
extent of GW treatment and the technologies to
be used should be matched with intended water
uses. In industrial countries like Germany and
Japan, GW is used for toilet flushing. This is
justified based on the fact that the cumulative
flow balance between the GW generated and
188
O.R. AI-Jayyousi /Desalination
toilet flushing requirements shows a natural
affinity at about 30% of the total water use
[13,29-3 11.The viability of internal recycling is
to some extent contingent upon there being
substantial differences in water quality and
quantities demanded for different operations
[1 I]. On the other hand, in Western Australia,
five particular methods were being tested by the
Institute for Environmental Science at Murdoch
University to achieve fully integrated permaculture development [32].
Model guidelines for domestic GW reuse in
Australia have also been prepared [22,33]. These
covered hand basin toilets, primary GW systems
(direct subsurface application) and secondary
GW systems (mesh, membrane or sand filtration).
For primary systems the guidelines adopted the
Californian approach of requiring the use of a
surge tank with a screen to remove lint and hair.
6. Greywater ewe: Jordan’s experience
Jordan’s water resources are characterized by
vulnerability and variability. Due to its uneven
topographic features, the distribution of rainfall
in Jordan varies considerably with location.
Rainfall quantities vary from 600 mm in the
northwest to less than 200 mm in the eastern and
southern deserts, which form about 91% of the
surface area. The average total quantity of
rainfall is approximately 7200 MCM/y, and it
varies between 6000 and 11,500 MC&I/y.
Approximately 85% ofthe rainfall evaporates,
and the rest flows into rivers and wadis as floods
flow and recharge groundwater. Groundwater
recharge amounts to approximately 4% of the
total rainfall volume, and surface water amounts
to approximately 11% of total rainfall volume
[3,41.
Jordan is facing a chronic imbalance in the
population-water resources equation. The total
renewable freshwater resources of the country
amount to an average of 750 MCM/y. The
population in 1997 was estimated at 4.6 million,
156 (2003) 181-192
and growing at an annual rate of 3.5%. The per
capita of water was 160 m’/y in 1997. The renewable water resources falls short of meeting actual
demand, which translates into an increase of food
imports where the deficit in food balance reached
$110 per capita in 1996.
Despite the huge investment in the water
sector, a considerable water deficit still faces
Jordan. The water deficit for all uses is projected
at 408 MCM/y in the year 2020 [34].
The long-term safe yield of renewable groundwater resources has been estimated at 275 MCM
per year. Some of the renewable groundwater
resources are presently exploited to their maximum capacity and in some cases beyond safe
yield. The average resident of the capital city of
the Kingdom of Jordan currently receives less
than 100 led, all delivered only 1 or 2 days a
week.
Since 1993, Jordan has put forth substantial
efforts towards the remedy of the water situation
in the country. As a result, water policy reform
was initiated. It aimed to restructure institutional
frameworks, strengthen capacities, rationalize
strategies, improve financial viability and widen
public awareness and participation. Moreemphasis was put on increasing the commercial focus of
operations. The concept of separating national
infrastructure from service delivery has also
become an acceptable option, and the need to
mobilize all available resources, including an
increased role of the private sector in systems
operation, was recognized [3,4].
A pilot project for GW reuse was implemented in Ain Al-Baida, Tafileh Governorate
[24,35]. The main use for GW in the project area
is for garden farming in rural areas. The technology used ranges from direct use of GW at its
original state to adopting a preliminary (separation of fat and grease) and secondary automated
treatment system, as shown in Fig 2.
Faruqui and Al-Jayyousi [35] documented the
findings of GW reuse in Tafileh, Jordan. The
study revealed the following:
0. R. Al-Jayyousi / Desalination 156 (2003) 181-l 92
189
Portable
water
backup w ith
air gap
I
Automatic
1
To subsurface
dr io irr iaation
fieid
’
back-
Electronic
controller
Gravity
tank
Can be located under house,
outside, or underground
1. The organic content of the GW samples,
measured by biological oxygen demand (BOD,),
ranged from 275 mg/l to 2287 mg/l. This is a
little higher than typical BOD, values for GW,
but not surprising given the low water consumption in Ain El Baida.
2. The detergent concentration, measured by
the methylene blue alkyl sulfonate (MBAS),
ranges from 45 mg/l to 170 mg/l, consistent with
the use of sulfonate based dishwashing detergent.
3. The pH of the baseline tap water was 8.3 5.
Three of the GW samples had a pH higher than
8.35, likely due to the presence of dishwashing
detergent or hand soap containing caustic soda,
which is a strong base. The other three samples
had a pH lower than 6.7, which may have
resulted from the presence of foods high in acid
such as tomatoes and cooking oil. This is a
positive effect because the higher the pH, the
higher the alkalinity.
4. The average EC of the GW samples was
818 deciSemens/m (ds/m), and varied from
457 ds/m to 1135 ds/m. The salinity of the tap
water is 594 ds/m. The salinity of the samples
was a little higher than the medium salinity in the
Fig. 2. Automated greywater system.
baseline tap water because of the addition of salts
contained in food particles. Where the GW salinity was lower than that of the tap water, the
households diluted the GW with rainwater.
5. The average sample SAR was about 3 and
ranged from 1.0 to 6.8. The tap water SAR was
only 0.83. Higher detergent content corresponds
with higher SAR values, indicating the detergent
and soap contains sodium that is increasing the
alkalinity of the water.
6. The average EC of soil irrigated with GW
was 2.76 ds/m, varying from 1.01 ds/m to
6.78 ds/m. The average salinity of the baseline
soil was 2.57 ds/m, with a range from 0.93 ds/m
to 4.2 1 ds/m.
7. The average SAR of the samples was 3.7
and varied between 1.71 and 5.59. The average
SAR of the baseline soil was 2.84 and ranged
from 1.54 to 4.14. The SAR of alkaline soils
generally exceeded 6, meaning the soil irrigated
with GW is good for the cultivation of most
crops.
To follow up, a GW reuse and treatment
project in Tafileh, Jordan, was implemented by
the Islamic Network for Water Development and
190
O.R. Al-Jayyousi / Desalination 156 (2003) 181-192
Table 4
Greywater quality parameters before and after treatment
Sample type
PH
TSS
O&G
BOD
ABS
(FC/lOOml)*10
Raw greywate?
TGW samplelb
TGW sample 2
TGW sample 3
TGW sample4
TGW sample 5”
Average TGW
Percent reductiond
6
7
6
6
316
42
158
517
141
20
13
50
1500
106
680
1011
3
56
5
99
8
6
0
171
189
0.40
8
19
0.86
66
392
0.74
101
20
89
99
21
3
46
0.54
7
5
6
6
2
4
5
0.34
“These values represent weighted means of raw greywater from households.
bTGW: Samples 1 through 4 represent treated greywater (TGW) for households.
“Sample 5 represents treated greywater from an institutional building.
dThese values represent the rate of change between two means (raw and TGW).
Management and was funded by the International
Development Research Center. GW quality
parameters are shown in Table 4.
The above parameters for 25 users in the
project area, Tafileh, Jordan, show the degree of
effectiveness of the treatment of GW. It is
evident from Table 4 that the reduction rates (for
raw GW vs. treated greywater) for TSS, oil and
grease, and BOD were 0.4, 0.86, and 0.74,
respectively. However, the variations in GW
characteristics are substantial due to different
social habits with respect to dish washing and use
of detergents.
7. Conclusions
and recommendations
Greywater reuse presents a potential option
for water demand management and also contributes to reducing fresh water use for irrigation.
To ensure water sustainability, GW reuse needs
to be coincidental with water-sensitive garden
design and growing food at home and public
open spaces. When GW is to be used for irrigation, there may be an imbalance between plant
requirements for the nutrients and the seasons,
with a higher requirement in the warmer months
than the colder ones. Rather than removing the
nutrients, an alternative is to store the nutrients in
the soil.
GW reuse needs to be seen in terms of its
contribution to sustainable water development
and resource conservation without compromising
public health or environmental quality. The
following conclusions can be drawn:
GW guality varies considerably and thus
appropriate technology is to be selected to suit
the users’ needs and utilize local knowledge.
Residence time in systems dramatically
affects the characteristics of GW.
Simple two-stage filtration and chemical disinfection systems remove coliforms but remain high in turbidity and organic pollution.
Advanced filtration systems reduce all components of GW but do not reliably meet all the
water recycling standards.
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International,27(3) (2003) 387-394.
ELSEVIER
Desalination I56 (2003) 18 l-l 92
www.elsevier.comAocate/desal
Greywater reuse: towards sustainable water management
Odeh R. Al-Jayyousi
Civil Engineering Department, College of Engineering, Applied Science University, Amman I1 931 Jordan
Fax: +962 (6) 523-2899; email: [email protected]/[email protected]
Received 2 January 2003; accepted 15 January 2003
Abstract
The aim of this paper is to assess the role of greywaterreuse in sustainablewater management in arid regions.
Moreover,it intendsto documentthe experienceof greywaterreuse in Jordan.Creywater(GW) is the water collected
separatelyfrom sewageflow that originatesfrom clotheswashers,bathtubs,showersand sinks, but does not include
wastewatertirn kitchen sinks, dishwashers,or toilets. Dish, shower, sink, and laundry water comprise 5040% of
residentialwastewater.GW is used in groundwaterrecharge,landscaping,and plant growth.A case study on GW reuse
in Jordan is presentedto shed some lightson its role in sustainablewatermanagement.To operationalizethis concept,
wateris viewedas an economicgood and a finiteresourcethat shouldbe valuedand managedin a rationalmanner.The
studyconcluded that currentenvironmentalpoliciesshouldaimto controlpollutionandto maximizerecyclingandreuse
of GW withinhouseholdsand communities.DecentralizedGW/wastewatermanagementoffersmore opportunitiesfor
maximizingrecyclingopportunities.
Keyworak
Greywaterreuse; Sustainablewater management;Watermanagement;Jordan
1. Introduction
Historically, domestic greywater reuse was
practiced to conserve water. However, social and
economic constraints prevented its further
development and integration in the urban water
systems [ 11. It is likely that new innovations in
water management will eventually lead to
substantial changes in lifestyle, particularly if the
use of water as a transport medium for our
domestic waste is reduced or eliminated [2].
The conventional paradigm of water/wastewater management was characterized as supplydriven, centralized and large-scale development.
This approach led to over-exploitation or
depletion of renewable water resources, mining
of non-renewable groundwater resources and
deterioration of water quality. The collection and
disposal mind-set prevailed because of concerns
over public health protection. Water-intensive
and centralized sewer systems were built to
Presented at the European Conference on Desalination and the Environment: Fresh Waterfor All, Malta, 4-8 May 2003.
European Desalination Society International Water Association.
001 l-9164/03/$-
See front matter 0 2003 Elsevier Science B.V. All rights reserved
PII: SO01 1-9164(03)00340-O
182
O.R. Al-Jayyousi / Desalination 156 (2003) 181-192
remove wastewater from immediate environment
of the communities using water as a transport
medium. This paradigm is inadequate for sustainable water management. A need for a paradigm shift is necessary to ensure optimum
utilization of resources [3-51.
Wastewater and greywater (GW) recycling are
emerging as integral parts of water demand
management, promoting the preservation of highquality fresh water as well as reducing pollutants
in the environment and reducing overall supply
costs. Recent developments in technology and
changes in attitudes towards water reuse suggest
that there is potential for GW reuse in the
developing world.
GW represents the largest potential source of
water savings in domestic residence. For example, the reuse of domestic GW for landscape
irrigation makes a significant contribution
towards the reduction of potable water use. In
Arizona, for example, it is documented that an
average household can generate about 30,000 to
40,000 gallons of GW per year [6]. This illustrates the immense potential amounts of water
that may be reutilized, especially in arid regions
like the Middle East.
Domestic G reuse offers an attractive option
in arid and semi-arid regions due to severe water
scarcity, rainfall fluctuation, and the rise in water
pollution. To ensure sustainable water management, it is crucial to move towards the goal of
efficient and appropriate water use. GW reuse
contributes to promoting the preservation of
high-quality fresh water as well as reducing
pollutants in the environment. Meeting different
needs with the appropriate quality of water may
prove to be economically beneficial and at the
same time reduce the need for new supplies at a
higher marginal cost. Mixing GW with rainwater
is a viable practice; however, since rainwater is
generally of high quality (COD<200 mg/l), the
stochastic nature of rainfall events implies a large
storage capacity is necessary for its optimum use
[7]. Conversely, domestic GW often has a higher
pollutant load (up to 5000 mg/l COD) but is
produced according to more regular patterns,
which are simpler to exploit for the purposes of
domestic reuse [8]. GW reuse can result in cost
savings (to both the consumer and state water
authority), reduced sewage flows and potable
water savings of up to 3 8% when combined with
sensible garden design [9].
The aim of this paper is to assess the role of
RW reuse in sustainable water management in
arid regions, particularly documenting Jordan’s
experience in GW reuse.
2. Characterization of greywater
GW is the wastewater collected separately
from sewage flow from clothes washers, bathtubs, showers and sinks, but does not include
wastewater from kitchen sinks, dishwashers, or
toilets. Dish, shower, sink, and laundry water
comprise 50--80% ofresidential wastewater. GW
may be used in groundwater recharge, landscaping, and plant growth.
Due to the fact that GW is usually generated
by the use of soap or soap products for body
washing, its quality varies according to source,
geographical location, demographics and level of
occupancy, as shown in Table 1. GW is relatively
low in suspended solids and turbidity, indicating
that a greater proportion of the contaminants are
dissolved. Moreover, although the concentration
of organics is somewhat similar to domestic
wastewater, their chemical nature is quite different. The COD:BOD ratio may be as high as
4: 1 (very much greater than values reported for
sewage). This is coupled with a deficiency of
macro-nutrients such as nitrogen and phosphorus.
The COD:NH,:P of GW has been measured at
1030:2.7:1, and this compares with 1OO:S:l for
domestic wastewater. Hence, both the relatively
low values of biodegradable organic matter and
the nutrient imbalance limit the effectiveness of
biological treatment [ 131.
183
0.R Al-Jayyousi 1 Desalination 156 (2003) 181-192
Table 1
Typical composition of greywater from various sources
Source
Hand basin
Combined
Synthetic greywater
Single personb
Single family’
Block of flatsb
Collegeb
Large colleged
“Total nitrogen.
COD (mg/l)
Turbidity (NTU)
109
121
181
110
-
263
371
-
-
33
80
96
40
146
168
_ Bob
(w4
256
-
69
25
14
76.5
20
59
57
bHolden and Ward [lo]. ‘Sayers [ll].
In sum, GW reuse helps to conserve and
optimize the use of water resources. However,
GW treatment and reuse are to be assessed in
terms of technical feasibility, public health,
social acceptability and sustainability.
NH3(mg/l) P (m.0
Total coliforms
9.6”
1
0.9
2.58
0.36
-
1.5x106
-
0.74
10
10
0.8
9.3
0.4
-
1x106
-
2.4
5.2x106
-
dSurendan and Wheatley [ 121.
r .-.
3. Conceptual framework for greywater reuse
It is interesting to look at the dynamics of
water/wastewater allocations and their uses.
Governments allocate substantial amounts of
money to develop, treat and transport water
resources. On the other hand, more money is
spent to collect wastewater, treat it and then
transport it to distant places for potential uses. To
address the externalities of this paradigm, attention is to be focused on small-scale and on-site
treatment of waste/GW [ 141.
The following conceptual framework for GW
reuse is based on the closed-loop concept. This
implies that GW is being managed and reused in
a decentralized manner within the household,
neighborhood, and/or community.
The concept of closed loop in water demand
management was documented by Bakir [ 15J. The
main idea is to match water quality with appropriate water uses as shown in Fig. 1. In other
words, GW may be allocated for appropriate uses
Fig. 1. Schematic diagram for a closed water loop for a
residential building [ 151.
such as, irrigation, landscaping, toilet flushing,
and groundwater recharge.
4. Treatment of greywater
Based on the work of Nolde and Dott [ 161,
GW from recycling systems should fulfill four
criteria: hygienic safety, aesthetics, environmental tolerance, and technical and economical
feasibility. In most countries, guidelines and
standards for water reuse in buildings either do
not exist or are being revised or expanded. In
1992 the US Environmental Protection Agency
(EPA) published “Guidelines for Water Quality”
that describes the treatment stages, water quality
184
O.R. Al-Jayyousi / Desalination 156 (2003) 181-192
requirements and monitoring tools [ 171.According to the EPA, reclaimed water used for toilet
flushing should undergo eventual filtration and
disinfection. The effluent should have no detectable fecal coliforms in 100 ml of the treated
water, a BOD of <IO mgll’ and a residual Cl, of
>l mgl-’ whereby Cl, should be continuously
monitored.
Options for making safe use of GW as a
source for irrigation are many and diverse. A key
to successful GW treatment lies in its immediate
processing and reuse before it has reached the
anaerobic state. The simplest GW treatment
consists of directly introducing freshly generated
GW into an active, live topsoil environment.
Many new technologies have been developed to
treat GW. Some of these technologies include
Planter soilbox design and pressure leach
chambers.
The major difficulty presented for treatment
of GW is the large variation in its composition.
Reported mean COD values vary from 40 to
371 mg/l between sites, with similar variations
arising at an individual site. This has been
attributed to changes arising in the quantity and
type of detergent products employed during
washing. GW quality is also subjected to
dynamic variation. Significant chemical changes
may take place over time periods of only a few
hours. Table 2 shows a summary of water quality
standards for domestic water recycling.
The rationale for treating GW is based on
biological characterization of GW. It has been
documented that GW can contain at least 10’1
100 ml of potentially pathogenic microorganisms
[ 18-201. It is also accepted that stored GW
undergoes changes in quality which include
growth in numbers ofmicro-organisms according
to the limiting factors for each particular microorganism. Research has shown that counts of
total coliform and faecal coliforms increased
from 1O”-lo’/1 00 ml to above 1OS/100 ml within
48 h in stored GW from various sources. Of more
concern is the potential infection route that GW
provides for viral infections. Viruses comprise a
serious risk to health, which is amplified by the
relatively low dose required to cause infection.
In light of the amounts of GW that are
possible for reuse and the viability of its application, many technologies have been developed.
Processes range from simple systems in single
houses to very advanced treatment schemes for
large-scale reuse. Work conducted by the
National Aeronautics and Space Administration
demonstrated how bath and laundry water could
be reused by passing the water through diatomaceous earth filters followed by activated
carbon [21,22].
Model guidelines for domestic GW reuse in
Australia have been prepared [22]. These cover
hand basin toilets, primary GW systems (direct
subsurface application) and secondary GW
systems (mesh, membrane or sand filtration).
The following is a description of the most
common GW treatment technologies.
4.1. Basic two-stage systems
Coarse filtration plus disinfection represents
the most common technology used for domestic
reuse in the UK. The generic process employs a
short residence time so that the chemical nature
of the GW remains unaltered and only minimal
treatment is required. The coarse filter usually
comprises a metal strainer. Disinfection is
achieved using either chlorine or bromine, dispensed in slow release blocks or by dosing a
liquid solution. Systems recently tested [ 111have
shown a variety of water saving levels ranging
from 3.4% to 33.4%.
The basic two-stage system was designed to
meet the less stringent reuse standards akin to
those for bathing water, rather than the more
conservative standards. The water thus remains
high in organic load and turbidity, thereby
limiting the effectiveness of the chemical disinfection process for two reasons. Firstly, GW
contains flocculent particles above 40 mm in
0. R. Al-Jayyousi / Desalination 156 (2003) 181-l 92
185
Table 2
Summary of water quality standards and criteria suitable for domestic water recycling (adapted from [ 121)
Bathing water
Standards”
USA, NSF
USA, EPA
Australia
UK (BSIRA)
Japan
WHO
Germany
Total coliform count/
100 ml
Faecal
coliforms
BOD,
(mg/J)
Turbidity
(NTU)
Cl, residual
(mg/l)
pH
10,000(“~
5000
-
2000’”
loo@’
~240
<4
<lo
-
-
-
-
6-9
45
10
20
-
90
2
2
-
1
-
-
10
-
5
-
-
6-9
-
500
20
l-2
-
6-9
Non-detectable
<l
Non-detectable
<lo
1000’“’
200’”
100
6-9
-
“Bathing water standards suggested as appropriate for domestic water recycling.
(g), guideline, (m), mandatory.
and these are known to reduce chemical disinfection capability because the disinfection cannot diffuse far enough into the floes to
provide complete killing of pathogens. Secondly,
organic matter in the water requires a disinfectant. In the case of chlorine, disinfectant byproducts such as chloramines and trihalomethanes are generated, which have a lower
disinfectant capability and adversely affect
human health. Additional problems occur due to
the presence of detergents that are known to
produce an odor in water at concentrations above
3 mg.
Since physical processes achieve substantial
clarification of water, they are reasonably effective in decreasing the organic pollutant load of
GW prior to reuse, since this is to some extent
associated with turbidity. The aesthetic quality of
the product water is thus increased and problems
associated with downstream disinfection encountered in the coarse filtration systems substantially
ameliorated. On the other hand, simple filtration
based on fibrous (cloth) of granular depth filter
presents no absolute barrier to suspended matter,
resulting in coliform breakthrough and a propen-
diameter,
sity for solids unloading whenever hydraulic
shocks occur.
Membrane systems offer a permanent barrier
to suspended particles greater than the size of
membrane material, which can range from
0.5 mm of microfiltration membranes down to
molecular dimensions for reverse osmosis. The
treated water is thus generally extremely low in
turbidity below the limit of detection for coliforms, as shown in Table 3. On the other hand,
the energy demand for membrane systems is
substantially higher than that for depth filters: the
data shown in Table 3 refer to tubular MFAJF
systems, the most commonly used, which are
operated at pressures up to 2.0 bar.
Problems of poorly treated water quality have
been reported with membrane systems treating
GW water, as well as difficulties in effectively
cleaning membranes. The residence time of the
system has been identified as being a major cause
for concern. Over extended time periods, the GW
can become anaerobic, resulting in the generation
of organic components which are less readily
rejected by the membrane [lo].
186
0. R. Al-Jayyousi / Desalination I56 (2003) 181-l 92
Table 3
Performance of sand filter and membrane filtration processes for greywater treatment
~.~_.~-___~~_._._~
~__~__~__._~__~_~.
~ .~~~._. ~~~.~ ~_ ~
Influent”
Post-sand filter
Post-membrane
Influent
Post-membrane
Pre-advanced oxidationb
Post-advanced oxidationb
Pre-coagulationd
Post-coagulationd
-
BOD, Ow4
COD (mg/l)
33.3
12.3
4.7
25-185
l-19
41 (TOC)
25 (TOC)
____
143
35.7
22.2
86-410
21-l 12
100
30
Turbidity
__44.5
32.3
0.34
12-100
Cl
29.4
2.41
TC (cfu/lOO ml)
_._.._.__.~~~_____~.._~
0 E. Coli
2-310~10~
ND-2419
9x105
ND’
-
“Holden and Ward [lo].
bBasedon a 2 g/I concentration of Tio2 activated by an UV irradiation source.
“Non-detectable.
dBased on a ferric chloride dose of 30 mg/l.
The key factor constraining the economic
viability of membrane systems is the fouling of
the membrane surface by pollutants species. This
increases the hydraulic resistance of the membrane, thereby commensurately increasing the
energy demanded for membrane permeation
and/or decreasing the permeate flux.
4.2. Biological systems
Biological treatment is required to remove
biodegradable material, especially for systems
that include large distribution networks such as
hotels or community-based recycling schemes.
The benefits of biological and physical treatments are combined in processes such as membrane bioreactors (MBR) and biologically aerated
filters (BAF), which are small footprint processes
capable of producing high-quality effluents.
BAFs combine depth filtration with a fixed film
biological reactor. As such, they present no absolute barrier to suspended materials and thus do
not substantially disinfect the water. MBRs
combine an activated sludge reactor with a
microfiltration membrane, and have been successfully employed in Japan for GW recycling in
office blocks and residential buildings [23].
The MBR process can be configured with the
membrane placed within the reactor (submerged
MBR) or by externally to it (sidestream MBR).
The two systems show similar biological performance but membrane permeation differs between
them. The external systems are run at higher
transmembrane pressures, producing higher flow
rates that exacerbate fouling problems and thus
necessitate regular cleaning. The internal systems
are operated hydraulically, generating much
lower flow rates which are, however, stable,
thereby reducing membrane cleaning requirements to once in every 6 months as opposed to
monthly, weekly or even daily for the side steam
configuration operating in cross-flow mode.
The complexity of the technology applied is
generally commensurate with the scale of the
recycling scheme. Cost implications have meant
that single-house systems are largely restricted to
coarse filtration devices with downstream disinfection. The current emphasis is on simple and
0. R. Al-Jayyousi/Desalination156 (2003) 181-l 92
reliable systems. Installations in colleges and
small offices have focused on physical or simple
biological systems, and these have been shown to
be far more economically viable than singlehouse systems. The scheme in Lt.&borough, for
example, has reported a payback time between 5
and 10 years [12].
More than 20 units have been tested in Jordan,
Tafileh Governorate. Two types of GW systems
were installed and are being monitored [24], and
a preliminary environmental assessment of GW
in Jordan was conducted [4].
5. International
experience of greywater reuse
On the global scene, Japan, the US and
Australia maintain the highest profile in GW
reuse [8]. Other countries involved in active GW
research and applications include Canada, the
UK, Germany and Sweden [14,25-271. On the
regulatory and legal arena, GW reuse has gained
a degree of acceptance in the US and Australia.
This is evident in the California Pumping Code
and in the Australian general guidelines for
domestic GW reuse [8]. At the regional level,
Saudi Arabia, Cyprus, and Jordan have introduced GW systems to optimize water use. However, guidelines and technical specifications are
still underway.
It should be noted that each country has a
different reason for the adoption of GW reuse.
For example, the Japanese reuse initiative is
driven by the demands of a high population
density and small land space, while the US,
Australian, Saudi Arabian and Jordanian initiatives are a direct response to drought conditions
and the unregulated uptake of domestic GW
reuse for garden irrigation. However, it seems
that certain GW reuse initiatives are not focused
directly upon attaining a more sustainable future;
rather they are short-term reactions to water
scarcity.
The main use for GW in Germany is for toilet
flushing, irrigation and garden plants. In terms of
187
treatment of GW, some manufacturers of GW
systems assume a mechanical treatment of the
GW to be satisfactory [28], whereas others claim
a more advanced treatment technology to be
necessary. GW recycling plants have proved their
efficiency and applicability in practice for almost
10 years.
Current on-site treatment systems have generally adopted the technology of conventional
activated sludge plants for large treatment systems. This is understandable because the effluent
standard for garden surface irrigation is a
chlorinated effluent containing not more than
20 BOD130SS. Differences that can be observed
are the insertion of a trickling filter in the aeration chamber to cope with variable flows and the
infrequent removal of sludge. The anaerobic
decomposition of sludge takes place in the first
settling chamber. Hyper-chlorination of ammonium in secondary effluent theoretically removes
N by oxidation to nitrogen gas.
Following successful operation of these
systems and achievement of the set criteria,
guidelines for service water reuse were then first
introduced in Germany in 1995 on a local level
by the Berlin Senate Department for Building and
Housing. Parameters were defined among others
for BOD, <5 mg/l’, total coliforms ~100 ml-‘,
faecal coliforms ~10 ml-’ and Pseudomonas
ueruginosa <l ml-‘.
In Tokyo, Japan, the reuse of treated wastewater has been highly promoted. A typical use of
the reclaimed water is for toilet flushing with
about 970,000 m’/y-‘. Reclaimed water criteria
for use in toilet flushing were defined in the
“Report on reuse of treated wastewater” among
others for total coliforms (Cl000 ml-‘) and BOD
(a0 mgl--I). However, in arid regions, the
extent of GW treatment and the technologies to
be used should be matched with intended water
uses. In industrial countries like Germany and
Japan, GW is used for toilet flushing. This is
justified based on the fact that the cumulative
flow balance between the GW generated and
188
O.R. AI-Jayyousi /Desalination
toilet flushing requirements shows a natural
affinity at about 30% of the total water use
[13,29-3 11.The viability of internal recycling is
to some extent contingent upon there being
substantial differences in water quality and
quantities demanded for different operations
[1 I]. On the other hand, in Western Australia,
five particular methods were being tested by the
Institute for Environmental Science at Murdoch
University to achieve fully integrated permaculture development [32].
Model guidelines for domestic GW reuse in
Australia have also been prepared [22,33]. These
covered hand basin toilets, primary GW systems
(direct subsurface application) and secondary
GW systems (mesh, membrane or sand filtration).
For primary systems the guidelines adopted the
Californian approach of requiring the use of a
surge tank with a screen to remove lint and hair.
6. Greywater ewe: Jordan’s experience
Jordan’s water resources are characterized by
vulnerability and variability. Due to its uneven
topographic features, the distribution of rainfall
in Jordan varies considerably with location.
Rainfall quantities vary from 600 mm in the
northwest to less than 200 mm in the eastern and
southern deserts, which form about 91% of the
surface area. The average total quantity of
rainfall is approximately 7200 MCM/y, and it
varies between 6000 and 11,500 MC&I/y.
Approximately 85% ofthe rainfall evaporates,
and the rest flows into rivers and wadis as floods
flow and recharge groundwater. Groundwater
recharge amounts to approximately 4% of the
total rainfall volume, and surface water amounts
to approximately 11% of total rainfall volume
[3,41.
Jordan is facing a chronic imbalance in the
population-water resources equation. The total
renewable freshwater resources of the country
amount to an average of 750 MCM/y. The
population in 1997 was estimated at 4.6 million,
156 (2003) 181-192
and growing at an annual rate of 3.5%. The per
capita of water was 160 m’/y in 1997. The renewable water resources falls short of meeting actual
demand, which translates into an increase of food
imports where the deficit in food balance reached
$110 per capita in 1996.
Despite the huge investment in the water
sector, a considerable water deficit still faces
Jordan. The water deficit for all uses is projected
at 408 MCM/y in the year 2020 [34].
The long-term safe yield of renewable groundwater resources has been estimated at 275 MCM
per year. Some of the renewable groundwater
resources are presently exploited to their maximum capacity and in some cases beyond safe
yield. The average resident of the capital city of
the Kingdom of Jordan currently receives less
than 100 led, all delivered only 1 or 2 days a
week.
Since 1993, Jordan has put forth substantial
efforts towards the remedy of the water situation
in the country. As a result, water policy reform
was initiated. It aimed to restructure institutional
frameworks, strengthen capacities, rationalize
strategies, improve financial viability and widen
public awareness and participation. Moreemphasis was put on increasing the commercial focus of
operations. The concept of separating national
infrastructure from service delivery has also
become an acceptable option, and the need to
mobilize all available resources, including an
increased role of the private sector in systems
operation, was recognized [3,4].
A pilot project for GW reuse was implemented in Ain Al-Baida, Tafileh Governorate
[24,35]. The main use for GW in the project area
is for garden farming in rural areas. The technology used ranges from direct use of GW at its
original state to adopting a preliminary (separation of fat and grease) and secondary automated
treatment system, as shown in Fig 2.
Faruqui and Al-Jayyousi [35] documented the
findings of GW reuse in Tafileh, Jordan. The
study revealed the following:
0. R. Al-Jayyousi / Desalination 156 (2003) 181-l 92
189
Portable
water
backup w ith
air gap
I
Automatic
1
To subsurface
dr io irr iaation
fieid
’
back-
Electronic
controller
Gravity
tank
Can be located under house,
outside, or underground
1. The organic content of the GW samples,
measured by biological oxygen demand (BOD,),
ranged from 275 mg/l to 2287 mg/l. This is a
little higher than typical BOD, values for GW,
but not surprising given the low water consumption in Ain El Baida.
2. The detergent concentration, measured by
the methylene blue alkyl sulfonate (MBAS),
ranges from 45 mg/l to 170 mg/l, consistent with
the use of sulfonate based dishwashing detergent.
3. The pH of the baseline tap water was 8.3 5.
Three of the GW samples had a pH higher than
8.35, likely due to the presence of dishwashing
detergent or hand soap containing caustic soda,
which is a strong base. The other three samples
had a pH lower than 6.7, which may have
resulted from the presence of foods high in acid
such as tomatoes and cooking oil. This is a
positive effect because the higher the pH, the
higher the alkalinity.
4. The average EC of the GW samples was
818 deciSemens/m (ds/m), and varied from
457 ds/m to 1135 ds/m. The salinity of the tap
water is 594 ds/m. The salinity of the samples
was a little higher than the medium salinity in the
Fig. 2. Automated greywater system.
baseline tap water because of the addition of salts
contained in food particles. Where the GW salinity was lower than that of the tap water, the
households diluted the GW with rainwater.
5. The average sample SAR was about 3 and
ranged from 1.0 to 6.8. The tap water SAR was
only 0.83. Higher detergent content corresponds
with higher SAR values, indicating the detergent
and soap contains sodium that is increasing the
alkalinity of the water.
6. The average EC of soil irrigated with GW
was 2.76 ds/m, varying from 1.01 ds/m to
6.78 ds/m. The average salinity of the baseline
soil was 2.57 ds/m, with a range from 0.93 ds/m
to 4.2 1 ds/m.
7. The average SAR of the samples was 3.7
and varied between 1.71 and 5.59. The average
SAR of the baseline soil was 2.84 and ranged
from 1.54 to 4.14. The SAR of alkaline soils
generally exceeded 6, meaning the soil irrigated
with GW is good for the cultivation of most
crops.
To follow up, a GW reuse and treatment
project in Tafileh, Jordan, was implemented by
the Islamic Network for Water Development and
190
O.R. Al-Jayyousi / Desalination 156 (2003) 181-192
Table 4
Greywater quality parameters before and after treatment
Sample type
PH
TSS
O&G
BOD
ABS
(FC/lOOml)*10
Raw greywate?
TGW samplelb
TGW sample 2
TGW sample 3
TGW sample4
TGW sample 5”
Average TGW
Percent reductiond
6
7
6
6
316
42
158
517
141
20
13
50
1500
106
680
1011
3
56
5
99
8
6
0
171
189
0.40
8
19
0.86
66
392
0.74
101
20
89
99
21
3
46
0.54
7
5
6
6
2
4
5
0.34
“These values represent weighted means of raw greywater from households.
bTGW: Samples 1 through 4 represent treated greywater (TGW) for households.
“Sample 5 represents treated greywater from an institutional building.
dThese values represent the rate of change between two means (raw and TGW).
Management and was funded by the International
Development Research Center. GW quality
parameters are shown in Table 4.
The above parameters for 25 users in the
project area, Tafileh, Jordan, show the degree of
effectiveness of the treatment of GW. It is
evident from Table 4 that the reduction rates (for
raw GW vs. treated greywater) for TSS, oil and
grease, and BOD were 0.4, 0.86, and 0.74,
respectively. However, the variations in GW
characteristics are substantial due to different
social habits with respect to dish washing and use
of detergents.
7. Conclusions
and recommendations
Greywater reuse presents a potential option
for water demand management and also contributes to reducing fresh water use for irrigation.
To ensure water sustainability, GW reuse needs
to be coincidental with water-sensitive garden
design and growing food at home and public
open spaces. When GW is to be used for irrigation, there may be an imbalance between plant
requirements for the nutrients and the seasons,
with a higher requirement in the warmer months
than the colder ones. Rather than removing the
nutrients, an alternative is to store the nutrients in
the soil.
GW reuse needs to be seen in terms of its
contribution to sustainable water development
and resource conservation without compromising
public health or environmental quality. The
following conclusions can be drawn:
GW guality varies considerably and thus
appropriate technology is to be selected to suit
the users’ needs and utilize local knowledge.
Residence time in systems dramatically
affects the characteristics of GW.
Simple two-stage filtration and chemical disinfection systems remove coliforms but remain high in turbidity and organic pollution.
Advanced filtration systems reduce all components of GW but do not reliably meet all the
water recycling standards.
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