1 1 WASTEWATER RECYCLING AND REUSE PRACTICES IN MEDITERRANEAN REGION: Recommended Guidelines G. Kamizoulis 1 , A. Bahri 2 , F. Brissaud 3 , and A.N. Angelakis 4 1 WHO, European Project Office, Mediterranean Action Plan, Athens, Greece 2 National Research Institute for Agricultural Engineering, Water, and Forestry B.P. 10, Ariana 2080, Tunisia 3 Hydrosciences, Maison des Sciences de l'Eau, University of Montpellier II, 34095 Montpellier Cedex 05, France 4 N.AG.RE.F., Institute of Iraklio, P.O.Box 2229, 71307 Iraklio, [email protected]Abstract Recycled water is a reliable source of water that must be taken into account in formulating a sustainable water policy. Water reuse is increasingly been integrated in the planning and development of water resources in Mediterranean region, particularly for agricultural and landscape irrigation. Important projects are being developed and wastewater recycling and reuse facilities have been built. These projects have followed local or national guidelines where available such as for example in Israel, France, Tunisia or Cyprus. Regulations on wastewater recycling and reuse are essential. They help protect public health, increase water availability, prevent coastal pollution and enhance water resources and nature conservation policies. Unifying wastewater recycling and reuse regulations around the Mediterranean basin would contribute to secure economic and touristic exchanges in the region. However, there is still a controversy between the defenders of strict water quality criteria for an absolute protection of public health and the defenders of a pragmatic stance promoting non-potable water uses with less restrictive water quality criteria. Despite the high potential for wastewater recycling and reuse in the Mediterranean countries, only a few have systematically exploited this resource and have a well-established national policy. This paper presents the status of wastewater recycling and reuse and proposes common criteria for Mediterranean region. 1. INTRODUCTION In the Mediterranean basin, wastewater recycling and reuse are practiced since the Ancient Greek and Roman civilizations (Angelakis and Spyridakis, 1996). Land application of recycled water is an old and common practice, which has gone through different development stages with time, knowledge of the processes, treatment technology, and regulation evolution. Wastewater has also been used by the Mediterranean civilizations (wastewater was reused in the 14 th and 15 th centuries in the Milanese Marcites and in the Valencian huertas and the European (Great Britain, Germany, France, Poland, etc.), respectively (Soulié and Tréméa, 1992)). Raw or partially treated wastewater has been applied in many locations all over the world not without causing serious public health consequences and negative environmental impacts. This generated the existence of endemic, and quite epidemic diseases. In the Mediterranean region, the volume of wastewater is increasing. Large areas may be supplied with recycled water which may also be used for different other purposes depending on the demand, the water characteristics, its suitability, etc. Consequently, there is a major potential use of recycled water in the region. It is, however, essential that the development of water reuse in agriculture and other sectors be based on scientific evidences of its effects on
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WASTEWATER RECYCLING AND REUSE PRACTICES
IN MEDITERRANEAN REGION:
Recommended Guidelines
G. Kamizoulis1, A. Bahri
2, F. Brissaud
3, and A.N. Angelakis
4
1 WHO, European Project Office, Mediterranean Action Plan, Athens, Greece
2 National Research Institute for Agricultural Engineering, Water, and Forestry B.P. 10,
Ariana 2080, Tunisia 3 Hydrosciences, Maison des Sciences de l'Eau, University of Montpellier II, 34095
Montpellier Cedex 05, France 4 N.AG.RE.F., Institute of Iraklio, P.O.Box 2229, 71307 Iraklio, [email protected]
Abstract
Recycled water is a reliable source of water that must be taken into account in formulating a
sustainable water policy. Water reuse is increasingly been integrated in the planning and development
of water resources in Mediterranean region, particularly for agricultural and landscape irrigation.
Important projects are being developed and wastewater recycling and reuse facilities have been built.
These projects have followed local or national guidelines where available such as for example in
Israel, France, Tunisia or Cyprus. Regulations on wastewater recycling and reuse are essential. They
help protect public health, increase water availability, prevent coastal pollution and enhance water
resources and nature conservation policies. Unifying wastewater recycling and reuse regulations
around the Mediterranean basin would contribute to secure economic and touristic exchanges in the
region. However, there is still a controversy between the defenders of strict water quality criteria for an
absolute protection of public health and the defenders of a pragmatic stance promoting non-potable
water uses with less restrictive water quality criteria. Despite the high potential for wastewater
recycling and reuse in the Mediterranean countries, only a few have systematically exploited this
resource and have a well-established national policy. This paper presents the status of wastewater
recycling and reuse and proposes common criteria for Mediterranean region.
1. INTRODUCTION
In the Mediterranean basin, wastewater recycling and reuse are practiced since the Ancient
Greek and Roman civilizations (Angelakis and Spyridakis, 1996). Land application of
recycled water is an old and common practice, which has gone through different development
stages with time, knowledge of the processes, treatment technology, and regulation evolution.
Wastewater has also been used by the Mediterranean civilizations (wastewater was reused in
the 14th
and 15th
centuries in the Milanese Marcites and in the Valencian huertas and the
European (Great Britain, Germany, France, Poland, etc.), respectively (Soulié and Tréméa,
1992)).
Raw or partially treated wastewater has been applied in many locations all over the world not
without causing serious public health consequences and negative environmental impacts. This
generated the existence of endemic, and quite epidemic diseases.
In the Mediterranean region, the volume of wastewater is increasing. Large areas may be
supplied with recycled water which may also be used for different other purposes depending
on the demand, the water characteristics, its suitability, etc. Consequently, there is a major
potential use of recycled water in the region. It is, however, essential that the development of
water reuse in agriculture and other sectors be based on scientific evidences of its effects on
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2
environment and public health. Although several studies have been conducted on wastewater
quality and for different purposes, at this time, there are no regulations of water reuse at a
Mediterranean level. With the development of tourism and Mediterranean food market, there
is a need for sharing a common rationale for developing water reuse criteria on both sides of
the Mediterranean.
1.1. Background
The Mediterranean region is characterized by common issues related to environmental and
development problems, in particular, concerning water resources management, their
development and pollution control. However, the two shores (North/East and South) of the
basin are strongly contrasted and face differently the arising issues.
Hot and dry summers and mild winters receiving the major part of the annual precipitation
characterize the «Mediterranean» climate. Rainfall is unevenly distributed (in space and time).
Moreover, the whole basin or parts of it are experiencing drought episodes in a more or less
regular pattern with unpredictable successions of dry years which may seriously worsen the
situation.
According to the Blue Plan (Margeta and Vallée, 2000), renewable water resources are very
unequally shared across the Mediterranean basin with around 72% located in the North (Spain,
France and Monaco, Italy, Malta, Bosnia-Herzegovina, Croatia, Slovenia, R.F. of Yugoslavia,
Albania, and Greece), 23% in the East (Turkey, Cyprus, Syria, Lebanon, Israel, Palestinian
Territories of Gaza and the West Bank, and Jordan), and 5% in the South (Egypt, Libya,
Tunisia, Algeria, and Morocco). Besides, available water resources are becoming increasingly
scarce, vulnerable and threatened by over-exploitation and different pollution sources (Table
1). Countries of the Southern Mediterranean and Middle East region are facing increasingly
more serious water shortage problems. Some of them have few naturally available fresh water
resources and rely mainly on groundwater. Surface waters are already in most cases utilized to
their maximum capacity. Groundwater aquifers are often over-drafted and sea and brackish water
intrusion in coastal areas has reached threshold limits in some locations. Non-renewable deep or
fossil aquifers are being tapped to varying degrees. Exploitation of non-renewable resources of
Saharan aquifers is intensive in Libya, Egypt, Tunisia and Algeria. Desalination of brackish
and seawater is already under implementation or planned in some countries despite its high cost.
National exploitation ratios over 50%, or even nearing 100% in several Mediterranean
countries (Egypt, Gaza, Israel, Libya, Malta, Tunisia) show that actual water consumption
already exceeds the renewable conventional water resources. As a consequence, several
problems appear all around the basin such as water and soil salinization, desertification,
increasing water pollution, and unsustainable land and water use.
Total population of the region is actually around 427 million inhabitants with 145 million
living near the sea and an additional 180 million tourists each year. By 2025, the population is
expected to increase by 17-19% and the tourist population by 40%. The demographic
evolution of population is fundamentally different in Eastern and Southern countries
(intensively growing) compared to the Northern ones (stabilizing or decreasing). It is
aggravated by a very intensive urbanization often along the coastal areas.
Due to rapid population growth, the average annual per capita renewable water is rapidly
decreasing since 1950. It varies across a wide range – from a little over 100 to more than 1000
cubic meters per year (Margeta and Vallée, 2000). All the Mediterranean countries of the EU
are expected to maintain themselves at or above 3000 m3/inh.yr when in the major part of the
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3
other Mediterranean countries, the projected water availability is below the level of “chronic
water scarcity” (< 1000 m3/inh.yr), due mainly to very high population growth. Some
countries, such as Israel, Jordan, Tunisia, and Malta, experience “absolute water stress” with
per capita water availability of less than 500 m3/inh./yr. In Malta, domestic water
consumption exceeds 50% of the available water resources. In such places, the conventional
water resources will be insufficient to even meet the domestic water demand.
Table 1. Current pressures on water resources in Mediterranean countries (after Margat and
Vallée, 2000).
Countries and
territories
Date
of
value
Indexes of quantitative
pressure on natural resources
%
Resources
available in
average year
km3/year
Urban and industrial waste
water discharged and
returned to continental water
km3/year (
1)
Index of
potential
depletion
% (2)
Exploitation
index (3)
Final
consumption
index (4)
(5) (
6)
PORTUGAL 1995 15,0 ~ 10 62 ~ 0,5 -
SPAIN 1997 31,4 20,6 89,0 3,22 3,6
FRANCE 1994 22,5 4,9 172,0 5.3 3,1
ITALY 1993 26,7 14,5 143,0 7,7 5,4
MALTA 1995 167,0 (7) 27 (
8) G 0,007 -
SLOVENIA
CROATIA
BOSNIA-
HERZEGOVINA
1990 6,5 ~ 1 262,0 ~ 7 2,3
F.R. of.
YUGOSLAVIA
F.Y.R MACEDONIA
ALBANIA 1995 3,3 2,1 41,7 ~ 0,3 0,7
GREECE
1990 10,2 8,6 63,0 ~ 0,1 ~ 0,2
TURKEY 1997 18,1 12,6 171,0 5,5 3,2
CYPRUS 1994 27,2 24,0 0,6
SYRIA 1993 39,1 (9) 31,6 24,5 0,35 1,4
LEBANON 1994 25,2 21,2 3,9 0,0 0,4
ISRAEL 1996 94,0 87,5 0,17
GAZA 1994 234,0 132,0 -0,018 0,06
THE WEST BANK 1994 27,0 14,3 0,52 0,05 ~ 9
JORDAN 1994 99,0 90,0 0,10 ~ 98
EGYPT 1993 93,4 71,2 ~16,0 6,5 39
LIBYA 1995 477,0 475,0 -3 -
TUNISIA 1995 73,7 59,9 1,5 0,05 3,2
ALGERIA 1990 31,2 21,5 11,3 0,8 ~ 7,0
MOROCCO 1991 39,3 31,7 20,5 0,3 ~ 1,5
1 Cooling waters discharged from thermal-electric power plants not included.
2 Ratio : return flows from urban and industrial wastewaters to continental waters / natural renewable water resources flows minus final
consumptions (= available water), expressed in percent. These use indexes are often much higher when compared to low water flows. 3 Exploitation indexes : annual water withdrawals / annual average flows of renewable natural water resources, expressed in percent.
4 Consumption indexes : final annual consumptions of withdrawn waters (= net water usage consumptions + wastewaters not returned to
continental waters, discharged into the sea) compared to the annual average flow of total natural renewable water resources, expressed in
percent. 5 Balance : annual average flow of total natural renewable water resources– final consumptions (this balance includes returned
wastewaters). 6 Balance : annual average flow of total natural renewable water resources– final consumptions (this balance includes returned
wastewaters). 7 Compared to exploitable water resources without saltwater intrusion.
8 Malta : taking into account return flows from water losses and non conventional wastewater (desalination).
9 Syria : the exploitation index, compared to the real water resources (25.11) with reduced external water resources, would be 55%, the final
consumption index 45% and the available water resources around 13.8 km3/year.
4
These problems of water scarcity will intensify because of population growth, rise in living criteria, and
accelerated urbanization which threaten the water supply in general and agriculture in particular and lead
to both an increase in water consumption and pollution of water resources. Continuing increase in
demand by the urban sector has led to increased utilization of fresh water for domestic, industrial and
tourism purposes, on the one hand, and generation of greater volumes of wastewater, on the other.
The Mediterranean basin is nowadays depending for its’ economic and social development on the
agriculture (largest water use share reaching 61% on average, 42% to 84% of total demands) and
tourism and, secondarily, on industry and other economic activities. Irrigated agriculture in competition
with other sectors will face increasing problems of water quantity and quality considering increasingly
limited conventional water resources and growing future requirements and a decrease in the volume of
fresh water available for agriculture. Around the cities of the region, competition with other sectors often
makes water the main factor that limits agricultural development. Policy makers have then been compelled
to develop additional water resources as well as to preserve the existing ones. Reclaiming and recycling
water is, among various measures, designed to encourage integrated and efficient management and use
of water resources and is therefore becoming an important component of the national resources policy.
The agricultural sector is influenced in the northern part by the common agricultural policy and in the
Southern and Eastern parts by the agreements of agricultural exchange, and the future free trade area.
Expansion of the irrigated area will continue in the southern and eastern countries with increasing
demand for food and from the development of agricultural production for export markets. On the other
hand, the irrigated sector will have to face major challenges with the future scenario of agricultural trade
liberalization; a part of the water resources may be reallocated to high added-value export products
instead of basic production or to industrial activities, tourism, and domestic water supply. Providing
water quantities and qualities in compliance with the needs is one of the challenges facing the region.
1.2. Water recycling and reuse in the Mediterranean region
Significance of water reuse. The significance of water reuse may be evaluated through the comparison
of water reuse potential with total water use. Water recycling and reuse is generally small compared with
total water use but it is expected to increase significantly. It is and will become more significant in water
scarce regions. In the United States, it was estimated that municipal water reuse accounted for 1.5% of
total freshwater withdrawals in the year 2000. In Tunisia, recycled water accounted for 4.3% of available
water resources in the year 1996, and may reach 11% in the year 2030. In Israel, it accounted for 15% of
available water resources in the year 2000, and may reach 20% in the year 2010. The volume of treated
wastewater compared to the irrigation water resources is actually about 7% in Tunisia, 8% in Jordan,
24% in Israel, and 32% in Kuwait. Approximately 10% of the treated effluent is being reused in Kuwait,
20-30% in Tunisia, 85% in Jordan, and 92% in Israel. In California, where the largest number of water
reuse facilities existing in the United States is found, there is around 434 million m³ of municipal
wastewater currently reused with, in 1999, water reuse for agricultural irrigation amounting to 68% of
the total recycled water used (Asano et al., 2000). In Japan, water reuse is mainly directed toward non-
potable urban applications such as toilet flushing, urban environmental water, and industrial reuse
(Asano et al., 2000). In Tunisia, the expected amount of recycled water in the year 2020 is expected to
be approximately 18% of the available groundwater resources and could be used to replace groundwater
currently used for irrigation in areas where excessive groundwater mining is causing salt water intrusion
in coastal aquifers.
Driving forces, benefits and concerns of water reuse. The driving forces for water reuse development
in the Mediterranean region are related to different issues such as water resources (water scarce
5
environment threatened by pollution), economical (cost-effectiveness of use recycled water), or
environmental issues (gradually more stringent water quality discharge regulations).
The benefits, potential health risks and environmental impacts resulting from water reuse and the
management measures aimed at using wastewater within acceptable levels of risk for the public health and
the environment are acknowledged in several documents (Shuval et al., 1986; Mara and Cairncross, 1989;
Asano, 1998; Crites and Tchobanoglous, 1998; Angelakis et al., 1999; Blumenthal et al., 2000; Angelakis
and Bontoux, 2001).
Water recycling and reuse is meant to help close the water cycle and therefore enable sustainable reuse
of available water resources. When integrated to water resources management, water reuse may be
considered as an integral part of the environmental pollution control and water management strategy. It
may present benefits to public health, the environment, and economic development. Recycled water may
provide significant additional renewable, reliable amounts of water and contribute to the conservation of
fresh water resources. It may be considered as a valuable source of water and nutrients in agriculture
schemes and therefore contributes to reducing chemical fertilizers’ utilization and to increasing
agricultural productivity. Reuse of recycled water, if properly managed, may alleviate pollution of water
resources and sensitive receiving bodies. It may also contribute to desertification control and desert
recycling. Saline water intrusion may be controlled in coastal aquifers through groundwater recharge
operations. Other social and economic benefits may result from such schemes such as employment and
products for export markets. It is, however, essential that the development of reuse prevents negative
effects on environment and public health since wastewater content in mineral and organic trace
substances and pathogens represents a risk for human health. Adequate treatment has therefore to be
provided for the intended reuse.
2. BRIEF OVERVIEW OF WASTEWATER RECYCLING AND REUSE IN MEDITERRANEAN
COUNTRIES
In most of the countries of the Mediterranean region, wastewater is widely reused at different extents
within planned or unplanned systems. In many cases, raw or insufficiently treated wastewater is applied.
In other cases, wastewater treatment plants are often not functioning or overloaded and thus discharge
effluents not suitable for reuse applications. This leads to the existence of health risks and environment
impacts and to the prevalence of water-related diseases. In some other situations where conditions for
reuse are met, wastewater is then submitted to adequate recycling systems and treated effluents are being
reused for different purposes without presenting any risk for human health. In these cases, recycled
water is an important alternative resource for sustainable development and food production.
However, only few Mediterranean countries (such as Cyprus, Israel, Jordan, and Tunisia) have included
water reuse in their water resources planning and have official policies calling for water reuse. A wide
variety of approaches to water reuse policy may be found because of the difference in the capacity to
implement such policies and depending on the socio-economic, institutional, and technological
conditions. Differences between countries occur in their environmental and public health policies. They
also occur in existing wastewater collection, treatment and disposal facilities, in human capacities, and
in equipment, material, and financial resources (US.EPA, 1992).
A large range of situations may also be found with different treatment levels and reuse operations. In
most of the cases, conventional technology has been adopted for treating wastewater independently of
the type of reuse. The general approach adopted up to now is based on producing an effluent in
compliance with water quality discharge requirements.
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The main reuse operations in the region are for agricultural and landscape irrigation, and groundwater
recharge. Industrial reuse is very seldom practiced. It should also be noticed that several research and
pilot studies have been conducted in the region. The information gained from such studies has allowed
the development of treatment and reuse for the specific conditions of the region. The implementation of
large-scale reuse schemes has resulted in significant technical and operational experience in recycled
water reuse. However, up to now, there are no specific Mediterranean guidelines regulating water reuse.
The EU-Mediterranean countries have to comply with the European Directive (91/271/EEC), which
specifies that "treated wastewater shall be reused whenever appropriate" (EU, 1991).
In this section we review the current practices and the potential of wastewater recycling and reuse in various Mediterranean countries under three headings depending on the status of wastewater reuse (Angelakis, 2002). 2.1. Countries with Regulations and/or Guidelines Concerning Wastewater Recycling and Reuse Cyprus. In Cyprus the wastewater generated by the main cities, about 25 Mm
3/yr, is planned to be
collected and used for irrigation after tertiary treatment. Because of the high transportation cost, it is
anticipated that most of the recycled water, about 55 to 60%, will be used for amenity purposes used as
hotel gardens, parks, golf courses etc. A net of about 10 Mm3 is conservatively estimated to be available
for agricultural irrigation. The cost of recycled water is low, about 7.5 cents/m3. This will reportedly
allow irrigated agriculture to be expanded by 8-10% while conserving an equivalent amount of water for
other sectors (Papadopoulos, 1995).
The provisional criteria related to the use of treated wastewater effluent for irrigation purposes in Cyprus
are presented in Table 2. They are stricter than the WHO guidelines and take the specific conditions of
Cyprus into account. These criteria are followed by a code of practice to ensure the best possible
application of the effluent for irrigation (Kypris, 1989). However, these criteria are someway apart from
California regulations philosophy.
France. France has irrigated crops with wastewater for years (close to a century), in particular around
Paris because, until 1940, it was the only method of treating and disposing of the wastewater of the
Greater Paris conurbation. This practice is still going on in the Achères region, where some of the
wastewater is used after screening and settling, but is likely to be discontinued soon. Interest in
wastewater reuse rose again in the early 1990s for two main reasons: (a) the development of intensive
irrigated farming (such as maize), in particular South-western France and the Paris region, and (b) the
fall of water tables after several recent severe droughts which have paradoxically affected the regions
traditionally considered to be the wettest (Western and North-western France).
Because of this new interest for wastewater reuse, the Health Authorities issued in 1991 the “Health
guidelines for reuse, after treatment, of wastewater for crop and green spaces irrigation” (CSHPF, 1991).
These guidelines essentially follow the WHO guidelines, but also add restrictions for irrigation
techniques and set back distances between irrigation sites and residential areas and roadways. In
February 1996, the Association of Water Supply and Sewerage Practitioners (AGHTM) published
technical recommendations about the wastewater treatments necessary to ensure compliance with the
French guidelines. Furthermore, recent French regulations make it compulsory for the departmental
administration to apply for authorisation for any wastewater reuse project (Bontoux and Courtois, 1996).
A review of these guidelines is being considered (Angelakis et al., 2003).
7
Table 2. Provisional quality criteria for irrigation with recycled wastewater in Cyprus (Angelakis et al.,
1999)
Irrigation of: BOD5 (mg/L)
SS (mg/L
)
Fecal coliforms (MPN/100mL)
Intestinal nematodes
(No/L) Treatment required
All cropsc A) 10a 10a
5a
15b
Nil Secondary, tertiary, and disinfection
Amenity areas of unlimited public access -Vegetables eaten cooked
A) 10a 15b
10a
15b
50a
100b
Nil Secondary, tertiary and disinfection
Crops for human consumption - Amenity areas of limited public access
A) 20a 30b
30a
45b
200a
1000b
Nil Secondary, storage >1 week and disinfection
or tertiary and disinfection. Stabilization maturation ponds total retention time >30 d or secondary and storage >30 d B) - - 200a
1000b
Nil
Fodder crops A) 20a 30b
30a
45b
1000a
5000b
Nil Secondary and storage >1 week or tertiary and disinfection. Stabilization maturation ponds total retention time >30 d or secondary and storage >30 d or secondary and storage > 30 d
B) - - 1000a Nil
Industrial crops A) 50a 70b
-
-
3000a
10000b
-
-
Secondary and disinfection. Stabilization maturation ponds with total retention time >30 d or secondary and storage >30 d
B) - - 3000a 10000b
- -
a These values must not be exceeded in 80% of samples per month. b Maximum value allowed. c Irrigation of leaved vegetables, bulbs, and corns eaten uncooked is not allowed. Note: The irrigation of vegetables is not allowed. The irrigation of ornamental plants for trade purposes is not allowed. No substances accumulating in the edible parts of crops and proved to be toxic to humans or animals are allowed in the effluent.
Few projects have in fact been carried out up to now, mainly because of problems relating to the cost of
tertiary treatments. The projects implemented cover more than 3000 ha of land, and quite a wide variety
of applications: market gardening crops, orchard fruit, cereals, tree plantations and forests, grasslands,
gardens and golf courses. The Clermont-Ferrand recycling scheme for irrigation of over 700 ha of maize
is today considered to be one of the largest projects in Europe. The recent development of new treatment
processes, such as membrane bioreactors (ultrafiltration, microfiltration), to obtain very high quality
purified water, disinfected and with no suspended solids, could change the approach to the problem. and
could open the door to recycling for domestic purposes (cleaning, toilet flushing, etc.). The reuse of
industrial wastewater after purification to supply cooling water, wash water or even process water after
sophisticated complementary treatment is widely developed in France. Israel. In Israel about 92% of the wastewater is collected by municipal sewers. Subsequently, 72% is
used for irrigation (42%) or groundwater recharge (30%). The use of recycled wastewater must be
approved by local, regional and national authorities. Effluent used for irrigation must meet water quality
criteria set by the Ministry of Health. The trend is towards bringing all effluents to a quality suitable for
unrestricted irrigation with wider crop rotation, which will require more storage and higher levels of
treatment in the future.
Cost-benefit analysis indicates that recycled wastewater is a very low cost source of water in Israel. As a
result, treated wastewater within the overall water supply, particularly for irrigation, has risen to 24.4.%
of the allocations. The water crisis in Israel and the relatively low cost of treated wastewater, rather than
pure environmental considerations, are the main driving forces behind the high percentage of reuse. Italy. A first survey of Italian treatment plants estimated the total treated effluent flow at 2,400 Mm
3/yr
of usable water. This gives an estimate of the potential resource available for reuse. In view of the
8
regulatory obligation to achieve a high level of treatment, the medium to large-sized plants (>100,000
inh. served), accounting for approximately 60% of urban wastewater flow can provide re-usable
effluents with a favorable cost/benefit ratio. The use of untreated wastewater has been practiced in Italy
at least since the beginning of this century, especially on the outskirts of small towns and near Milan.
Among the oldest cases of irrigation with wastewater is the “Marcite” where water from the Vettabia
river, which receives most of the industrial and urban untreated wastewater, is used. Nowadays, treated
wastewater is used mainly for agricultural irrigation covering over 4,000 ha. However, the controlled
reuse of municipal wastewater in agriculture is not yet developed in most Italian regions because of a
stringent normative which ignores the findings of recent research work and experiences of uncontrolled
reuse so common in Southern Italy. One of the largest projects was implemented in Emilia Romagna
where over 450,000 m3/yr of treated effluents are used for irrigation of more than 250 ha. The real costs
for the distribution of recycled wastewater (power, labor, network maintenance) are covered by the
users. New wastewater reuse systems have been recentely completed in Sicily and Sardinia for
agricultural irrigation (Angelakis et al., 2003). Existing Italian legislation (General Technical Standards - G.U. 21.2.77) sets the limits depending on the
type of vegetables and grazing crops to 2 and 20 colibacteria per 100 cm3, respectively (Angelakis et al.,
2002). Microbial criteria for irrigation with recycled municipal wastewater in Italy are given in Table 3.
Moreover, the law prescribes that in the presence of unconfined aquifers in direct contact with surface
waters, adequate preventive measures must be used to avoid any deterioration of their quality. A new
law relative to municipal wastewater is being prepared that gives better attention to the management of
water resources and in particular to the reuse of treated wastewater. Industry will be encouraged to use
treated wastewater. Municipal wastewater treatment companies have already planned to build a separate
supply network for wastewater reuse by industries. In the metropolitan area of Turin, for example, the
two main companies (Azienda Po Sangone (APS) and CIDIU) have already done so. Table 3. Microbiological standards for irrigation with reclaimed municipal wastewater in Italy;
comparison of regional guidelines with national and WHO standards (Angelakis et al., 2003)
Organisation or
Region
TC
(MPN/100 mL)a
FC
(MPN/100 mL)
Faecal Streptococci
(MPN/100 mL)
Nematode eggs
(no/L)
WHO Not set 1000b not set 1
Italy 2b, 20c not set not set not set
Sicily 3000b 1000b not set 1
Emilia Romagna 2b, 20c not set not set not set
Puglia 2b, 10c not set not set absent
a mean value of 7 consecutive sampling days; b unrestricted irrigation. c restricted irrigation.
Monacco. There is more or less the existing situation in France.
Spain. A new National Hydrological Plan has been recently published which is favorable to the reuse of
treated wastewater for irrigation. In any case, the reuse of treated wastewater is already a reality in
several Spanish regions for four main applications: golf course irrigation, agricultural irrigation,
groundwater recharge (in particular to stop saltwater intrusion in coastal aquifers) and river flow
augmentation. Commercial interest exists and some private water companies invest in Research and
Development activities, in collaboration with the Universities (e.g. AGBAR and Canal de Isabel II).
While there is no national legislation in Spain, at least three autonomous regions (Andalucia, Catalunia
and Baleares) have either legal prescriptions or recommendations concerning wastewater recycling and
reuse.
9
Tunisia. Irrigation with recycled wastewater is well established in Tunisia. Wastewater from la
Cherguia treatment plant, in Tunis, has been used since 1965 to irrigate the 1200 ha of la Soukra (8 km
North East of Tunis) and save citrus fruit orchards as aquifers had become overdrawn and suffered from
saline intrusion. The effluents from the treatment plant were used, mainly during spring and summer,
either exclusively or as a complement to groundwater.
Water from la Cherguia’s secondary sewage treatment plant is pumped and discharged into a 5800 m3
pond before storage in a 3800 m3
reservoir. The water is then delivered by gravity to farming plots through
an underground pipe system. A Regional Department for Agricultural Development (CRDA) supervises
the operation and maintenance of the water distribution system and controls the application of the Water
Code.
After this experience, a wastewater reuse policy was launched at the beginning of the eighties. The 6,366
ha involved in 1996 will be expanded to 8,700 ha in 1998 and ultimately to 20,000 ha. Wastewater reuse in
agriculture is regulated by the 1975 Water Code (law No. 75-16 of 31 March 1975), by the 1989 Decree
No. 89-1047 (28 July 1989), by the Tunisian standard for the use of treated wastewater in agriculture (NT
106-003 of 18 May 1989), by the list of crops than can be irrigated with treated wastewater (Decision of
the Minister of Agriculture of 21 June 1994) and by the list of requirements for agricultural wastewater
reuse projects (Decision of 28 September 1995). They prohibit the irrigation of vegetables that might be
consumed raw. Therefore, most of the recycled wastewater is used to irrigate vineyards, citrus and other
(except micro-sprinklers) using practices (such as
plastic mulching, support, etc.) guaranteeing
absence of contact between reclaimed water and
edible part of vegetables.
None required None required
Pretreatment as required by the
irrigation technology, but not less than
primary sedimentation
b) Irrigation of crops in category III with trickle
irrigation systems (such as drip, bubbler, micro-
sprinkler and subsurface).
c) Irrigation with surface trickle irrigation
systems of greenbelts and green areas with no
access to the public.
d) Irrigation of parks, golf courses, sport fields
with sub-surface irrigation systems. (a) Ascaris and Trichuris species and hookworms; the guideline limit is also intended to protect against risks from parasitic protozoa.
(b) FC or E. coli (cfu/100mL): faecal coliforms or Escherichia coli (cfu: colony forming unit/100 mL). (c) SS: Suspended solids. (d) Values must be conformed at the 80% of the samples per month, minimum number of samples 5. (e) In the case of fruit trees, irrigation should stop two weeks before fruit is picked, and no fruit should be picked off the ground. Sprinkler
irrigation should not be used. (f) Stabilization ponds. (g) such as advanced primary treatment (APT) (Jimenez et al., 1999 and 2001). (h) As very few investigations, if any, have been carried out on how to reach < 0.1 nematode egg /L, this criterion is considered a medium
term objective and is provisionally replaced by <1 nematode egg /L.
19
4. CONCLUSIONS
Most of the northern European countries have abundant water resources and they all give priority to the
protection of water quality. In these countries, the need for extra supply through the reuse of treated
wastewater is not considered as a major issue, but on the other hand, the protection of the receiving
environment is considered important. However, industry is generally encouraged to recycle water and to
reuse recycled wastewater. The situation is different in the southern European countries, where the
additional resources brought by wastewater reuse can bring significant advantages to agriculture (e.g.
crop irrigation) and tourism (e.g. golf course irrigation). Applications of treated wastewater reuse
practices are shown in Table 5. Some of water recycling and reuse technologies have been practiced in
Mediterranean region since ancient civilizations. Also, in most Mediterranean countries, wastewater
recycling and reuse is increasingly integrated in the planning and development of water resources.
Cyprus, France, Israel, Italy, Tunisia, and Turkey are the only Mediterranean countries to have
established national regulation or guidelines. Regional guidelines exist also in Spain. Other countries
such as Algeria, Egypt, Greece, Lebanon, Libya, Malta, Morocco, and Syria are contemplating
guidelines and/or regulations concerning wastewater recycling and reuse. The existing guidelines are
necessary for the planning and safe implementation of water recycling and reuse projects (Table 6).
Table 5. Application of wastewater use practices
COUNTRY
Practices
Urban and
Residential
Uses
Unrestricted
irrigation
industrial
reuse
Restricted
agricultural
irrigation No reuse
Albania
Algeria a
Bosnia and
Herzegovina
Croatia Cyprus
Egypt
France
Greece
Israel
Italy
Lebanon
Libya
Malta
Monaco Morocco
Slovenia Spain
Syria
Tunisia
Turkey
a Only for production of fodder crops, pasture and trees
Establishing Mediterranean guidelines for municipal water reuse is a challenge because of the absence of
comprehensive international guidelines, and of a scientific consensus on the approach that should be
adopted to issue such guidelines. This has led to inconsistencies between the guidelines that are already
implemented in Mediterranean countries. However, a number of potential benefits may be gained in
providing minimum requirements, which should constitute the basis of water, reuse regulations in every
country of this region threatened by water scarcity and where food exchanges and tourism are
increasingly developing.
20
Table 6. Legislation for treated wastewater reuse
COUNTRY
Existence of
legislation
Contemplating
legislation
No
legislation
at all
Albania
Algeria a
Bosnia and
Herzegovina
Croatia
Cyprus
Egypt a
France
Greece b
Israel
Italy
Lebanon
Libya
Malta
Monaco
Morocco
Slovenia
Spain c
Syria
Tunisia
Turkey
a programme - strategy b under the form of sanitary regulation c in some regions of Spain (Balearic, Andalucia)
These guidelines have been prepared making a large use of the results of the recent assessment of the
WHO guidelines by Blumenthal et al., (2000). Their work was based on risk assessment using
epidemiological studies supplemented by microbiological investigations and model based QMRA. We
have add some QMRA (Quick Method of Risk Assessment). Some QMRA data were added and taken
the acceptable annual risks related to bathing and potable water drinking as benchmarks.
Four water categories based on comparable levels of risk have been distinguished. Water reuse cost-
effectiveness was also taken into account in the sense that a recycled water supply network must serve as
many reuse applications as possible in the same area. The following recycled water uses were
considered: agriculture, landscape irrigation, urban and residential reuse, landscape and recreational
impoundments-excepting those where bathing is allowed-, groundwater recharge and industrial uses.
Wastewater treatments expected to meet the criteria were defined for each water category. In the case of
agricultural reuse, the capacity of the recycled water application system or method to reduce health risks
was taken into account.
Mediterranean countries are unequally developed, several being already equipped with wastewater
treatment plants while others have virtually no equipment. Therefore, all countries can not be expected
to be able to meet the reuse guidelines in the same time. However, an implementation time frame can be
set and agreed by all Mediterranean countries, each country committing itself to enforce the guidelines
within an approved delay, set according to its particular situation.
A regional committee should be established with internationally-recognized water reuse experts,
practitioners and regulators from Mediterranean countries to periodically re-evaluate and update the
21
guidelines in order to ensure that they are supported by the best available scientific data and risk-
assessment methods, and to validate the effectiveness of recycled water management practices.
International organizations should foster efforts for more consistency between the different regulations
and guidelines related to water quality. For the sake of integrated water management and to gain public
understanding and acceptance, water reuse regulations should be part of a set of consistent water
regulations applying to drinking water, bathing water, irrigation water, discharge, etc.
ACKNOWLEDGEMENTS
Thanks are due to Mr. I.E. Kapellakis for his help in reviewing existing information.
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