Bari : CIHEAM
Options Méditerranéennes : Série A. Séminaires Méditerranéens; n. 31 1997
pages 337-356
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--- Papadopoulos I. N on con ven tion al water resou rces: presen t situ ation an d perspective u se for irrigation . In : D upuy B. (ed.). Aspects économiques de la gestion de l'eau dans le bassin méditerranéen . Bari : CIHEAM, 1997. p. 337-356 (Options Méditerranéennes : Série A. Séminaires Méditerranéens; n. 31)
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of md
SUMMARY
-
Most countries in the Near East, North Africa and South Europe are arid or semi- arid. They have low rainfall, mostly seasonal and with erratic distribution. Moreover, due to the rapid development of urban and rural domestic water supplies, conventional water resources have been seriously depleted and wastewater reclamation and use for irrigation, among othernon conventional water sources, gained increasing role in the planning and development of
additional water supplies.
In this respect, in most arid and semi-arid countries, wastewater reclamation and reuse is
viewed increasingly as a mean to augment existing and future water resources against the
growing demand for water. Reclaimed water is a reliable source even in drought years, and thus
is capable to replacing potable water from non-potable water uses. Because of this, wastewater
treatment and use for irrigation has been expanded considerably the last few decades.
However, wastewaters are unique in composition, often associated with environmental and
health risk and their acceptability to replace more conventional or other non-conventional water
sources for irrigation is highly dependent whether the health risk and environmental impact are
within acceptable levels.
This paper elaborates the benefits and problems associated with non-conventional water
resources with more emphasis on wastewaters and provide information on present reuse
practices and their future prospective uses for irrigating agricultural crops, within acceptable levels of risk.
Key words: Wastewater, irrigation, environment, health.
RESUME
-
La plupart des pays du Proche Orient, d'Afrique du Nord et du Sud de l'Europe sont arides ou semi-arides. Ils ont une pluviométrie faible, essentiellement saisonnière, avec une distribution aléatoire. En outre, étant donné le développement rapide de la fourniture en eau à usage domestique urbain ou rural, les ressources d'eau conventionnelles ont été sérieusement épuisées, et la récupération d'eaux usées et leur utilisation en irrigation, entre autres res-sources d'eau non conventionnelles, a joué un rôle croissant dans la planification et le dévelop- pement de stocks d'eau complémentaires.
De ce point de vue, dans la plupart des pays arides et semi-arides, la récupération d'eaux usées et leur réutilisation sont considérées, de plus en plus souvent, comme un moyen
d'augmenter les ressources en eau existantes et futures, par rapport à la demande croissante.
L'eau récupérée est une source fiable, même durant les années de sécheresse, et peut ainsi remplacer l'eau potable pour les utilisations en eau nonpotable. Pour cette raison, le traitement des eaux usées et leur utilisation en irrigation ont connu un développement considérable au cours des dernières décennies. Cependant, la composition des eaux usées est unique, souvent lice à des risques écologiques et sanitaires, et leur acceptabilité, en tant que remplacement
pour des sources plus conventionnelles, ou d'autres sources non conventionnelles, dépend étroitement du niveau d'acceptabilité des risques sanitaires et des effets sur l'environnement.
La présente communication examine les avantages et les problèmes liés aux ressources en eau non conventionnelles, en mettant l'accent sur les eaux usées; des informations sur les
pratiques de réutilisation sont données, ainsi que les perspectives d'utilisations pour l'irrigation des cultures agricoles à l'avenir, à des niveaux de risque acceptables.
Mots-clés: Eaux usées, irrigation, environnement, santé.
Land in
was slow until 1950s.
development and most of the
plans, the and
development, top
This development of has
meant that easily accessible' such as and shallow
almost committed. The of
this
with emphasis
on
the East is
than 50% of its
demand food exceeds the in ag-
East
gation of the
in the 30% of the culti-
vated but amounts to about
75% of the total of the
the have less
that the minimum (750 m3/
sustain own of food.
only in the East hav-
than 2,000 all
the is a
The situation in Afiica to
that in East and although all the of
the Afiica have an in
tion, Tunisia has done the a
in national
1991; Asano and 1992).
Utilization of without
planning, has been in
nean has been
that could be a valuable addi- tional to cope with the of
that its use is based on sound
planning taking into the associ-
ated with the use of this
use may also to the
of an pollu-
tion effluent
to sensitive
Non conventional water resources: uresent situation and uersvective use for irripation 339
OF EAST
the
demand the end of the
50%
tional to
meet the de-
mand in the East
in Table 1 1991/1992).
Evidently at in than
20% of the available is used do- mestic and
tion, the main demand of the a significant
in sites
with im-
to
in compliance with the need to con-
Table
-
Water use in three dflerent sectors in (X) 1991/92).Country Domestic Industrial Agriculture
Afghanistan 1 O 99
Algeria 22 4 74
Bahrain 1 O 99
Cyprus 20 2 78
Egypt 7 5 88
ran 4 9 87 Iraq 3 5 92 Jordan 29 6 65 Kuwait 64 32 4
Lebanon 11 14 75
Libya 15 10 75
Malta 78 14
Morocco 6 3 91
Pakistan 1 1 98
Qatar 45 47
Saudi Arabia 45 47
Syria 7 10 83
Turkey 24 19 57 Tunisia 13 7 80 UAE 11 9 80 Yemen 4 2 94
that most of the and
ment as an of
policy.
has been anticipated that the quantities of waste- will double in most of the of the
the next ten 1990).
1991/92) that at the mo-
ment in than 20% of the
is allocated
is that this waste-
be and used
addition such an is the
tally sound way of disposal.
it has been anticipated that all
the main cities, amounted to about 25 million will be collected and following
to be used this
way it is expected that the will
an equivalent amount of will be
to 1982 amounted to about 25%
of the that time
lead to a in
use. 1987
about 0.27 lo6 m3/day of
a population of million people About 92% of the
this 72 %
% of the in but by 2010 it is
that will account about 20%, with about 33%
of the total allocated to
Tunisia the effluent
with a total flow of about 250000 m3/day is used to about 4500 ha of
and lawns. About 70%
of the about 60%
of the available
As a substitute in
i in the
potable supply and uses,
makes a to
takes on an economic dimension.
if planned and managed, can have positive mental impact, besides
as a of
of which
would if the not used
but lakes.
pollution such as dissolved oxygen fish kills
can be avoided. of
such and
the damages which, if quantified, can offset the costs of the
of
usage, is especially in
and of the
in
The plant which may eventually pollute if
and potassium) to
the as plant
when applied as This
with a con-
comitant in and
pollution The
soil
its holding capacity. addition the soil humus build-up
land and soil could be
achieved.
the
and and adjacent to and highways).
Non conventional water resources: present situation andperspective use irrigation 341
on the depend-
ing on the of pu-
and the method and location of
and pollution
among the
of the sound planning
can minimize these disadvantages.
Chemical andphysìcochemical qualì@
characteristics and considerations
the chemical and bio- in the
and use of the et
al., 1984). The magnitude of the
effluent and its acceptability can be if its quantity and quality
viewed as that in-
hu- man health
can limit the input of chemical constituents that affect
on
uses of the ef-
fects of
can be The effect
ents in
if
fiaction to the
health with mi-
difficult to assess.
This is in widely the
in
and in Table 2. The
constituents and the
on the composition of the of the wastes added
the the waste-
is et al, 1984).
an
the effluent the of
and avoidance of often and
and
used evaluating conven-
tional of
may be classified into one of
namely no slight to
use.
Biological quali@ criteria
the use of
on in
to that the use of waste- health
In the 19603, to health
on
and not actual and set
to be used to
eaten of
this was set at the minimum
0
f o d 1 0 0 ml), and was meant to indicate that the fkee (Table 3). The coli-
levels not defintive justi-
fied At the time the
the
ment of that epidemiol-
ogical studies of the exposed population at waste- use sites would be of limited value, and that it
was not possible to estimates
to with
Such an in some
fluence in the of in of the
East.
Table 2
-
Constituents of concern in wastewater treatment and irrigation with reclaimed wastewater and Asano, 1984).Suspended solids
Stable
Suspended solids, including Suspended solids can lead to the development of volatile and fixed solids sludge deposits and conditions when un- is in the aquatic envi-
oxygen demand, Composed of and
Chemical oxygen demand. fats. to the biological
decomposition can lead to the depletion of dissolved
oxygen in and to the development of
septic conditions.
total and Communicable diseases can be by the
faecal pathogens in
essential When to
sium the aquatic and can lead to the
of aquatic life. When in
excessive amounts on land, N can also lead to the pollution of
Specific compounds (e.g., phe- These tend to conventional methods ol
hy- Some compounds
toxic to the
ion activity The affects metal solubility as well as alkalinity ol
soils. in i:
but waste can
in the
Ni, and toxic to plants and animals.
Total dissolved solids,
conductivity, specific elements ions such toxic to some
Na, Cl, pose soil
and combined Excessive amount of hee available (>5 C12) may cause leaf-tip bum and damage some sensi.
tive in is
a combined which does not cause damage
Some as to the toxic effects o:
in to con,
tamination.
Non conventional water resources: present situation andperspective use for irrigation 343
Table 3
-
California treatment and quality criteria for reuse (State California, Health Department, 1978)Type of Use Total colifom
---
2.2/100 ml poundments
Non
fection
fection
Oxidation, Coagula-
fection2
Exceptions may
of 2 any
1973 a set guidelines
eaten the with
that the 1 9 8 9 ' ~ ~ it has
been to be an
to the
epidemiological evidence of 1989, a
guidelines in
in Table 4 on
in 1985 1985).
to the fact that in the actual health associated with
with helminthic diseases and that the safe use of in
high helminth ag-
the need to
of helminth eggs (Ascaris and Trichuris species and in effluent to a level of one less This means that some 99.9%
of helminth eggs must be
with
tain time ,
tive to achieve this quality but technologies the East and Afi-ica
ftom on
1000 faecal
100 ml of all
is tendency is
The guideline values given in Table 4 could be modified based on local epidemiological, sociocul- may be justified
that to infection such
as people lacking immunity to the local endemic infections.
The guidelines have been accepted by intended to adopt these guidelines.
An
which to be the most
and evaluation
well
own
in common sampling in time and
space, so that the quality
and quantity of the as the envi-
in the start of
the quantity and quality of to the objects to which the effluent will
the of
to achieve the
- -
-
as-
toto to
the the given
wocessed and diwatched. This
so with data on public health, when to
the East and
is one of the weak points in the is
with
in in
f i c a
gation. Thus,
irri-
planning and development.
a e c t
this spect, selection of the
of A E c a al-
tion still
This
the level is less than 35%.
Strategy to protect human health and environment
on at
public health and the
an optimum solution set of
mation on effluent supply and its quality to late and adopt an
Y
of
fields, public A likely to be eaten
of and
of the
public does not oc-
C of in cate-
con-
None
mean no. of egg2
I 1
I 1
Not applicable
Faecal colifom mean
no. 100 m l 3 )
1000~
No
ommend ed
Not
expected to achieve the cal quality
A of stabilization ponds designed to
in stabiliza- tion ponds 8-10 helminth and faecal
as the
technology, but not less
sedimentation ological quality indi-
specific cases, local be taken into account, and the
and the
guideline 200 faecal 100 ml) is public lawns, such as hotel lawns, with which the public may come into
the case of should cease two is picked, and no should be picked off the
should not be used.
the has been given on
the waste as the only feasible and fully
effective the of health
in most of the East and
full of wastes is not fea- sible even due mainly to economic
to
ways of human health and envi-
than waste especially
economic and
1987; 1990). To achieve
this and and human health,
of et. al., 1989):
- waste
- of
-
choice of methods of application of the effluent to the- of to the waste, and
hygiene
While full
hom even the field, and
act in the pathway,
hom the
the
An to plan-
ning effluent will allow an optimum to be se- lected, depending on the local insti- tutional and economic conditions.
is a to
tion to the
it does
vide to families
at high since they still exposed to pathogens in the waste on the soil and on the
is, not adequate in its own; it should be complemented by
such as
application, and should
within an system of con- to the helminthic of the quality guideline would be sufficient to
tect field than full
the use of
still in
Afi-ica ceptable.
as a means of health and in
and capacity to
in developing a
of a
evident, that includes
high risk if and legal not existing.
that to health domestic sewage effluent should the biological
to achieve a of pathogens may be
expensive to be an impossible techno-
economic So
sary to be taken to the risk to an acceptable such as the selection of suitable
quality of this
might not be enough because the method,
of such against accidental use etc.,
health The
quality of effluent to be used a
taken setting quality guide-
lines 1994).
affecting health not be
into but as a set of to be followed. Such constitute a code of
which should be followed with the same diligence as the quality
USE
and use may to
the of the but
use affect the and
consequently human to the
involving a
of planned and timely ap-
actions. The specific
with to quality, demand
existing necessitate specific ap- solutions which must be adaptable to the existing situation and the level of technology in the most potential effects on the with
contamination of soils FAO, 1991).
on and groundwater
is likely to contain chemical
pollutants. Of those that
toxic to man, plants and aquatic biota.
fall into this although these contaminants
not most of the of the
metals
ganics of the
due to heavy on
A possible
gation is building of toxic salinity in the soil. As the
pollutants, heavy metals, concen- and solubility in the soil con- ditions, will with time and, many of it is possible that toxic levels
Non conventional water resources: present situation andperspective use irrigation 347
could develop and be taken this line, most of
mum loading by heavy metals
Such in Tunisia
soil salinization is
common in is
this the
land unusable
Soil contamination can due to
if inadequate leaching is
Good essential to avoid ad-
tion is often
at the planning stage. of the
N and
based on than on
aims at alleviating contamination of NO,-N.
on groundwater The susceptibility of the
to low levels of toxic chemicals,
the consumption of which these
is
that only negligible amounts 30 cm beyond the point of appli- cation within the soil.
does to
since it is to slow
of the and
tained in the top few of the soil, and tions less than 20 m.
can and
is al., 1982).
Of the chemical pollutants, the of can is the poten-
tial that in the vicinity
of This
contamination by could be
effluent is used
the the effluent is col-
plies should not be located within, such
ment aims at N03-N in cases
the is used
fields, contamination of
that and
it has been found that no of N03-N in the soil could be expected.
land application of of
also pesticides and that
may be in
to is evidence
that some in the soil
ics with detection of in
the is
that such compounds will
the in
Since the of
the
of pollutants out and, by law, made the
sponsibility of the this as-
pect in Afiica
East no has been yet made.
Control measures
the to health and the envi-
in the past attention has been placed on the only feasible and fully
the of health
such an
achieved pathogen
of excess and at- is
the than
economic and yet the
and human health, the following could be applied:
adoption of
of
systems application
of
of human disposal
health, without
guidelines as well as ment plant
it leaves the facility is also an
facet
tion and to minimize aes-
thetic health tight
imposed on the and use of the any specific gation use should be based on
of contact the intended
use of
and legal
Although sanitation is as
supply, in
Afiica the is behind
the system
could in
the systems mostly not not
in an
this should not since in
some cities of the like in
A m m a n ,
Nicosiaand the of
in even than the
in
this context, in of
ized and lacking in funds.
considerations To
and many include quality
well as
sampling and plant
and Gen-
in
tight on the
of
the guidelines and adopted in intended to the quality of the bodies the
is most of these
been the aspect as an
component of the system.
this, the quality
as in these guidelines S S and
faecal The
have been developed and adopted in (Table 3). These although gent to a level to be the
in most of the
they have been adopted in a of in the East and Afiica as a base
lating national and guidelines.
The U.S. Agency (1992),
own guidelines. The these guidelines is to in- about how to develop effective wastewa- intended U.S.
utilities agencies, that seeking to
establish the
tion of how-
useful although
the developing
and in the of a law had been duced in 1982. 1989, a new of the
tial law could
Non conventional water resources: present situation andperspective use for irrigation 349
-
quality of effluent.
-
it is allowed-
allows the of fields and public law with the guidelines, the adopted guidelines in have also and disadvantages:-
Specifying the to twothe quality of the not a
since two samples could not
the whole month.
- The guidelines not allowing of
gation of an ef-
fluent ml and
nematode eggs at <
Egypt no guidelines yet have been adopted but law
1984) the use of effluent to the in
of vegetables eaten
with any effluent quality. that
at the plants
into the that can pollute
such
ml; S S , 80; 200, NO3 50 mg/l.
and
an old legislation going back
to of waste-
in soil. polluted waste-
is not allowed to to
bodies without obtaining fiom the ap-
guidelines and absent.
than those by with the aim to the specific 5). These guidelines followed by a code of as to
best possible application of the effluent tion
the use local,
Effluent used must
set by the of is
use with
levels of in the This
levels of is being
to high competitive
Tunisia the in
hibits the use
eaten legislation the
in in-
specifies the sibilities of the
the Agency 199 1).
the guidelines.
also
Table 5
-
Wastewater quality standards for irrigation in Cyprusof: mg/l SS mg4 Faecal coli-
Amenity of 10"
unlimited ac- 15""
cess
human A)2 O*
consumption. 30"
Amenity of limited ac- cess
A)20"
30""
70""
10"
15"'"
30"
45""
-
30"
45""
-
- -
50"
100""
200"
1000**
200"
1000"
1000"
5000""
1000"
3000"
10000""
3000"
10000""
Nil
Nil
- Nil
Nil Nil
-
-
-and and dis-
infection
and > l week
and and
disinfect.
Stabilization ponds
total time>30 days and >30 days
and > l week and disinfection
Stabilization ponds
total time >30 days and >30 days and
Stabilization ponds
total time>30 days 01
and >30 days
*
These values must not be exceeded in 80% of samples month**
Note 1. of vegetables is not allowed
Note 2. of is not allowed
Note 3. No substances accumulating in the eatable of and to be toxic to al-
lowed in effluent
General considerations
The main difficulty in evaluating the economics of is the valuation of non fman- cial aspects such as of
pollution nuisances health less
difficult is the allocation of costs
between the the
these the analysis of
out using techniques of economic and so-
cial cost-benefit analysis, which well docu- mented (Shuval, 1990).
The step in the analysis should begin with the
of the estimation of the
least-cost disposal options that meet minimum en- (health, sanitation and pollution) stan-
set of cost the logical
allocation of costs to the of
the above this amount should be
allocated to the system. Then
assuming that is economically viable, in- vestigations should be made to assess the demand
Non conventional water resources: present situation andperspective use for irrigation 351
in the the
-
- Existing schemes -
tion
-
nottified, the cost of to the
should be estimated in addition to
to make the effluent suitable and acceptable
of
in fi-
fiom the accep- tance in
of General approach
Economic justification be
based on the
to be not always be quan-
be con- as of national policy and it is often difficult to include such complex benefits into eco-
et al., 1989).
The costs to -
-
-
Treatment costs
which should meet health and
-
land and site-
civil- technology and equipment, including collection system, pipes and pumps and
-
to the costs of minimum to
the
facilities can be placed at the
location the site of
be studied and to achieve the least-cost solution.
costs including on-farm costs
costs can into two
-
costs of-
The inter alia, on the
location of the
needed to use, and on the size of
the land
costs may include:
- to health
- hygiene facilities field
-
with thespecific application
- institutional build-up, including and facilities
As the
and as supple-
to the costs of if no use of
Operation and maintenance costs
lated all facilities added to
facilities existing to those which would be used if
facilities plant,
facilities, and handling equipment.
-
additional-
- clothing field
-
if is insuf-ficient
-
-
testingcosts as a
centage of the facilities investment costs.
Benefits
When evaluating
initial is to split all benefits into two
-
benefits, and-
benefitsbenefits to the use of
in
potable supply,
the benefits can be di-
-
in and yields-
savings in costs-
savings in-
jobcosthenefit an
disposal option in a situation a high
of to is envi-
This is a kind of
benefit which could be easily estimated, but
benefits
to whichcould be
taken into ac- count, such as:damages to the of soil
of of
of
establishment of
etc.
depends on the kind of
which of the above mentioned benefits should be
the should iden-
tify, analyze and estimate impacts.
Costlbenejit ratio and other economic parameters speaking, the benefits can be divided into
1972):
-
those whose value cannot be meas- in any quantitativeand
- those which can in
in some units.
when in
into the same
Non conventional water resources: present situation andperspective use irrigation 353
is the obvious choice, it has the special advantage that the benefit in
its own in- vestment cost.
sometimes items which no meaning- ful valuation can be
goods, which can jointly benefit many people and it is difficult to exclude people the
costhenefit analysis becomes impossible, since the benefits cannot be valued, it is still useful to the costs of the same benefit in This is called cost- effectiveness analysis and can be used in evaluating a
two possible ways to apply cost/ benefit analysis:
-
is not affected by thenot), the costs and benefits that just those which will be affected by applying one solution that at that point in time. The cost
elements that with
the the choice.
-
often convenient in down allthe each of the to
at the net that a lot of the
than once. The advantage of this
it
is possible to with
The valuations to be made in any cost-benefit analysis fall main heads:
-
andbenefits at the time
- at
in time
- The valuation of outcomes.
of each in the
value" should be obtained by using
in of a time
discount An is the of
is
sets the value of the O. many
cases the two the same
it is unquestionably the case that
the costs. these
cases the be
in is the health
Economic evaluation of a may not be exact
because of the The most
changes in technology, false estimation of the ca- pacities, and the length
can be in the
a sensitivity analysis The best solution should satisfy the
-
should have the-
The benefits should exceed those of the next best-
The benefits should exceed its costs.Cost recovery -pricing
and
not be the benefits of with
ments in
is caused by faulty policies in allocating
Adequate is
to the us-
an adequate policy can the feasibility of the
scheme. This aspect although all wa-
it is of man-
aging pollution expected
will be much
efficiency is low. Even effluents of ac- affect health and the if the application efficiency is low.
the low efficiency could be of the effluent.
Each to pay the actual
cost of and to
et. al., 1989). Within
this should an
equitable of costs and benefits multiple use of the
in cost savings to the
and be the is
cost, to one the then the costs should be
The cost of should be about the
same as fiesh in some cases it
can be than the this
an if the should be established.
offinancial resources
The allocation of to a
constitutes an obvious and not
only
A feasibil- little if it was not
that
available a if the conclusion of the study positive and A feasibility study should only be made if financing
good.
of financing exist, both at the na- can be catego- to the kind of lending
- financing
and which
loans initial expenses, setting-up the
and of the cost goods
-
funding agencies which can co- finance the of goods andand
-
must be emphasized that it is to inte-
and gov-
involved will in
financing an obvious link is established the
Argaman, Y.
Asano, T.
Asano, T., Smith, and G. Tchobanoglous, G.
In
G.S. T.Ayers, J. ASCE. 135-154.
Bahri, A. (1 99 1 j. sewage sludge in
Tunisia.
Basbis, A. (1 992 j.
Bastian, State of knowledge in Land
1 :347-354.
Non conventional wafer resources: present situation andperspective use for irrigation 355
Bauer, J.W. (1978). A Land State
of knowledge in of :3 17-321
and Evaluation. at the
on
Blumenthal, U.J., of the in health associated with
the use of human
S . Cairncross, C. the effect of
in health fiom Sci. Tech., 21 :567-577.
Crook, J. (1985). in J. AWWA, 77:60-71.
Crook, J. (1991). Quality and and
Technology, Vol. 24, No. 9:109-121.
(1972).
in the East and f i c a . Study.
EPA (1992). Guidelines No.81. pp 252.
FAO bigation No. 29.
as No. 5, pl 5.
No. 7, p18.
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