Journal of Water Resource and Protection, 2011, 3, 300-310
doi:10.4236/jwarp.2011.35038 Published Online May 2011 (http://www.SciRP.org/journal/jwarp)
An Examination of the Factors Involved in Agricultural
Reuse: Technologies, Regulatory and Social Aspects
Ezio Ranieri1, Harold Leverenz2, George Tchobanoglous2
1Engineering Faculty of Taranto, Polytechnic University of Bari, Bari, Italy
2Department of Civil and Environmen tal Engineering, University of California, Davis, USA
Received December 16, 2010; revised February 9, 2011; a ccepted Ma r ch 19, 201 1
Abstract
Factors that impacts agricultural reuse are examined in the paper. The objective of this work is to assess the
factors involved in agriculture reuse by presenting a comparison of three wastewater treatment plants used
for food crop irrigation: Adelaide, South Australia; Foggia, South Italy and Monterey, California. An analy-
sis of the driving forces for reuse, regulatory requirements, and other factors affecting the water reuse sys-
tems are described. A comparison of treatment technologies and costs is also performed including pretreat-
ments, biological steps, filtration, sedimentation and disinfection options. As a consequence of global warm-
ing that has increased the frequency and severity of natural disasters like the drought, the impacts of climate
change and seasonality is discussed in the paper. A possible scenario of the future trend for agriculture reuse
including the influence of the increase in urban water use, the increase in salinity and the acceptability of
products is lastly considered.
Keywords: Climate Change, Groundwater, Regulatory Settings, Salinity, Treatment Processes
1. Introduction
The importance of wastewater reuse is increasing as a
result of growing water demands in semi-arid areas all
over the world. Wastewater reuse in agriculture is a cost-
-benefit operation from both an economic and environ-
mental point of view; the implementation of which is a
balance of opport uni t y and necessity [1,2].
In the past two decades, there has been a notable in-
crease in the use of treated wastewater for crop irrigation,
especially in arid and seasonally arid areas of both indu-
strialized and developing countries. Recent effect of world
climate change imposes a new attention towards water
savings and the development of new and affordable tech-
nologies for wastewater reuse.
The impact of drought can be greatly exacerbated by
the inefficient use of water, inadequacies in infrastruc-
ture, water use, demand management and in legislative
frameworks and regulatory mechanisms. The economic
impact of droughts has been approximately 25 billion €
over the last 30 years and was nearly 12 billion € in 2003
[3]. This study has shown that the worst drought in the
USA was more than twice the cost of the worst flood.
Wastewater reuse has developed from a basic method
of disposing of wastewater without any treatment to an
often highly engineered technique of wastewater up-
grading and water resources augmentation in water-
scarce regions throughout the world. Due to limited wa-
ter resources, typically water-stressed countries in dry
climates like South Australia, South Italy and the State of
California, have developed wastewater reuse strategies
and programme acknowledging the beneficial role waste-
water reuse can play in integrated water management,
[1,4,5].
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 irriga-
tion amounting to 68% of the total recycled water used
[1].
While most of waste reuse systems have a number of
driving forces in common, the individual circumstances
and specifications for each system is subject to site spe-
cific circumstances. Given the similarity in the case stu-
dies, it is of interest to investigate the factors that contri-
bute to the water reuse scheme developed for each situa-
tion.
The objective of the paper is to examine the factors

E. RANIERI ET AL.
301
involved in ag riculture reuse by presenting a comparison
of three systems used for food crop irrigation in Monte-
rey California (USA), Adelaide (Australia), and Apulia
(Italy). An analysis of the driving forces for reuse, regu-
latory requirements, treatment processes employed, and
other factors affecting the water reuse systems is pre-
sented.
2. Background
2.1. Water Reuse in Agriculture
The interest and the increase in water reuse for crop irri-
gation has occurred as a result of other several factors:
 Increasing scarcity of alternative waters for irriga-
tion, exacerbated by increasing urban demand for
potable water supp lies;
 Increasing salinity of groundwater in coastal areas
where excessive groundwater withdrawals are faci-
litating sea water intrusion into fresh water aquifers;
 Growing recognition by water resource planners of
the importance and value of wastewater reuse;
 Increasing cost of fresh water and the need for reli-
able, drought proof water supplies;
 High cost of artificial fertilizers and the recognition
of the value of nutrients in wastewater, which sig-
nificantly increase crop yield;
 Millenium Development Goals (MDGs) especially
the goals for ensuring environmental sustainability
[6,7];
 Increasing regulations related to effluent quality
discharged to the environment.
While secondary effluent quality is adequate for direct
agriculture reuse on certain crops, the addition of ad-
vanced tertiary treatment (e.g., filtration and disinfection
steps) typically results in water that is suitable for most
unrestricted irrigation purposes [8].
Regardless of the agricultural water quality issues,
important criteria that drive water reuse for irrigation
purposes are:
 Large nearby important agricultural region;
 Concerns about degradation of marine environments
from untreated wastewaters;
 Sea water intrusion from excessive pumping of
groundwater for agriculture;
 Low precipitation.
2.2. Factors That Impacts Agricultural Reuse
The use of reclaimed water for irrigation is subject to
factors such as the availability and cost of alternative
water sources, the variability in irrigation demand due to
seasonal uses, and the suitability of the water quality for
the crops under consideration. As a consequence of the
recent observed climatologic data in all area of the world
and particularly in the semi-arid regions [9] and as a
consequence of the lower water availability for agricul-
ture lower income from agricultural sector we can affirm
that climate change has a considerable impact on waste-
water reuse . Other impact to be considered are seasonal-
ity, acceptability of the product, increase in urban and
ecological water use, increase in salinity, op erational and
capital costs.
2.3. Regulatory Issues
The regulatory requirements for the use of reclaimed
water for unrestricted irrigation is based on the need to
protect public health in the event of a cross connection
with a potable water system or contact with water during
irrigation events. Irrigation of food crops generally re-
quires a high level of water quality to ensure that the
agricultural workers and consumers of the agricultural
products are protected from disease causing microorgan-
isms [10].
There a large number of potential legal and regulatory
instruments which are available for pollution prevention
and control, and examples of which can be found in op-
eration in many industrialized countries. Developing
countries need to examine these in the context of their
capability to deliver the end result without over-stretch-
ing their resources.
Risk avoidance or risk minimization certainly should
be principal elements in the determination of wastewater
reuse and recharge water standards and guidelines in
relation to their end uses. However, technological and
economic factors also enter into the ultimate quality pa-
rameters. Aesthetic factors of taste, odor, and appearance
must be important considerations for water even if they
do not directly relate to the safety of the water, because
consumer acceptance and confidence in the quality and
safety are essential [2].
3. Case Study 1 Monterey, California
3.1. The Physical Setting
The area around Castroville near Monterey, CA, is a na-
tional center for production of various food crops, gene-
rating almost $3 billion/yr as of year 2004. Until the
1980s, groundwater was the primary source of irrigation
water in Monterey County. Intensive groundwater with-
drawal resulted in depletion of groundwater level and
seawater intrusion, rendering some well water unsuitable
for irrigation. Meanwhile, expansion of wastewater
treatment facilities was required because the existing
wastewater treatment facilities in the region were reach-

E. RANIERI ET AL.
302
ing full capacity. Following the decision to pursu e irriga-
tion of these food crops with reclaimed water, a 10-year
study was conducted to assess the safety and feasibility
of agricultural irrigation with reclaimed water [11].
3.2. The Regulatory Setting
The California Department of Health services (DHS) has
established the wastewater reclamation criteria (State of
California, 1978) known as title 22. The current Water
Recycling Criteria were adopted by DHS in 2000 [12].
This water recycling criteria include water quality stan-
dards.
3.3. Treatment Processes
The wastewater reclamation plant was established in the
early 1920s and subsequently modified and upgraded to
include Title 22 process: coagulation, flocculation, sedi-
mentation, filtration and chlorination. The process is
shown on Figure 1.
4. Case Study 2 Adelaide, Australia
4.1. The Physical Setting
In this dry agricultural coastal region (rainfall 600 mm/yr,
evaporation 2 000 mm/yr), water availability is a li mi ting
factor to crop production, and groundwater resources
have been overdrawn for irrigation needs [13]. Consis-
tent with a South Australia policy issued in 1993 to en-
courage sustainable water reuse, and the 1995 Environ-
mental Protection Act, further promoting and regulating
water reuse, the City of Adelaide began considering rec-
lamation and reuse of the Bolivar WWTP effluent to
satisfy some seasonal irrigation demands, and reduce
adverse ecological effects caused by nutrients discharged
in the marine environment. Adelaide is perhaps the only
industrialized city in the world to have constant problems
of water shortage, b ecaus e its water supply depends up to
90% on Murray river. Beside aiming at providing rec-
laimed water for agricultural use during peak demand in
the summer time, and minimizing year-round nutrient
loads to Gulf St Vincent, water reuse project also pre-
sented an opportunity for generating economic benefits
in the region, using taxpayer funds to both improve
coastal water quality and promote agricultural production,
rather than simply building a non-revenue generating
nutrient removal upgrade to the Bolivar plant. To max-
imize the economic goals, planners determined that rec-
laimed water shou ld be stored during low demand season,
thus increasing availability for summertime peak irriga-
tion season. A multi-year research project was imple-
mented to ensure that the treatment technology selected
for production of the reclaimed water could be used to
recharge the aquifer sustainably.
4.2. The Regulatory Setting
The regulatory requirements are similar to the standards
set in California for food crop irrigation and are also
based on suitability to conduct ASR during the winter
storage pe riod.
4.3. Treatment Processes
The Bolivar Wastewater treatment plant treats 40 × 106 m3/yr
and consists of primary sedimentation, secondary treat-
ment using biological trickling filters and stabilization
ponds prior the discharge in Gulf of St. Vincent, South
Australia. In a second moment others treatments were
added with the goal of recycling the treated water: dis-
solved air flotation with filtration (DAFF) disinfection
contact tank, balancing storage reservoir, as shown in
Figure 2.
Figure 1. Process flow diagram for Monterey regional water pollution control facility for production of water for unrestricted
irrigation reuse.

E. RANIERI ET AL. 303
5. Case Study 3 Apulia, Italy
5.1. The Physical Setting
The Apulian Region, characterized by average rainfalls
of less than 600 mm is histo rically a water-deficient area
with supplies heavily depending on importations from
neighboring areas to meet domestic, agricultural, and
industrial needs [14]. The impact of wastewater on the
quality of deep ground water resources for drinking wa-
ter and the quality of seawater for recreational purposes
(i.e., tourism) is a major consideration. The total Apulian
area is approx. 1 900 000 hectars; the agriculture area
represents 66%, approx. 1 250 000 hectars. In recent
years the irrigated agricultural area has grown so that
now it represents approx. 30% ot the total agricultural
area. In particular flower and vineyard have been ex-
panded while cereal and olive colture have decreased. In
Apulia operate six “Agricultural Consortium” Gargano,
Capitanata; Terre d’Apulia, Stornara e Tara; Arneo e
Ugento Li Foggi that manage a total irrigated area of
approx. 360 000 hectars. Private area is largely predo-
minant area for irrigat i on repres en ting 285 000 hectars.
5.2. The Regulatory Setting
Existing Italian legislation (Decree 185/03, Table 2) sets
the limits very low and depending mainly on chemical
parameters and not on microbial parameters.
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.
5.3. Treatment Processes
Wastewater treatment for agriculture reuse is performed
by two plants in series. The first one a conventional me-
chanical biological treatment plant, the next one is a
physic-chemical plant treating approx. 12 × 106 m
3/yr.
The process flow diagram is shown on Figure 3.
Because of secondary wastewater may contain some
synthetic organic chemicals even at low concentrations
ozone pre-oxidation process has been used to destroy
trace constituents, including pesticides and herbicides.
The choice of inserting a pre oxidation is explained also
with: 1) the need to ensure a pre-disinfection step to
avoid biofilm in the subsequent steps; 2) to facilitate the
GAC adsorption in the subsequent phase. Clarification
should be optional. If TSS concentration is lower than
80 mg/l no chemicals were added. This implies a lower
sludge fo rmation.
6. Discussion
The three selected agricultural reuse case studies Monte-
rey, California, Adelaide, Australia, and Foggia, Italy
were analyzed because of their similar conditions related
to climate and water scarcity. Their average annual tem-
perature is compared on Figure 4.
Background information for each of the case studies is
described in Table 1.
6.1. Comparison of Regulations
Water quality criteria for irrigation with recycled munic-
ipal wastewater applicable for each of the case studies
are given in Table 2.
As shown in Table 2 the constituents for whom the
respect of the limits are mandatory are for Italy in num-
ber much higher than in other two countries. Based on
the data presented above, it is clear that the requirements
set for the Italian case study for food crop irrigation with
reclaimed water are more stringent than the standards
established in other countries, such as the California and
Figure 2. Process flow diagram for Bolivar sewage treatment facility for production of water for unrestricted irrigation reuse.

E. RANIERI ET AL.
304
Figure 3. Process flow diagram for the Foggia wastewater reclamation facility for production of water for unrestricted irriga-
tion reuse.
Figure 4. Average temperature in Foggia, Adelaide, Monterey during the year.
Table 1. Summary of irrigated area and water use.
Region Volume of recycled water
used for irrig a tion, m3/yr
Percent of flow
treated used for
irrigation
Irrigated area
with recycled
water, ha
Management of
non-irrigat ion water Typical Irrigated crops
Monterey 25 000 000 85 4 700 Discharge to Pacific
Ocean
artichokes,
brassicas,
strawberries,
salad crops
Adelaide 280 000 000 100 20 000 Discharge to sea and/or aquifer sto-
rage and recovery
vineyards,
olive trees,
salad crops,
brassicas
Apulia 12 000 000 20 4 000 Discharge to canals leading to Adriatic
Sea
vineyards,
olive & peach trees,
artichokes
Australia. In California more importance is given to the-microbiology of the water and it should be noted that

E. RANIERI ET AL.
305
also Italy regulation should be performed in that way,
because of E.coli is the unique microbiological parame-
ter and should not perform the total microbiological
quality of water.
The surface water supplies currently used for the w ater
supply of Southern Italy would not be able to meet the
standards established for the reclaimed water. Thus, the
standard may be considered overly restrictive for the
water reuse application in question.
In California and Australia, standards for many con-
stituents are provided as a guideline, not as a set limit
and, therefore, not limiting the implementation of water
reuse projects unnecessarily. Several factors or percep-
tions that may have contributed to the development of
these standards include:
Table 2. Selected water quality for food crop irrigation.
Parameter Unit California Apulia, Italy Southern Australia
pH 6 – 9.5 4.5 – 9.0
SAR 10 2 - 102a
TSS mg/L NS 10
Turbidity NTU < 2 < 2
BOD5 mg/L NS 20
COD mg/L 100
Phosphorus, tota l mg/L 2
Nitrogen, total mg/L 15
Nitrogen, ammonium mg/L 2
Conductivity mg/L 3000
Metals mg/L
Aluminum mg/L 1 5
Arsenic mg/L 0.1 0.02 0.1
Cadmium mg/L 0.01 0.005 0.01
Chromium mg/L 0.1 0.1 1
Iron mg/L 2 1
Lead mg/L 5 0.1 0.2
Mercury mg/L 0.01 0.001 0.002
Selenium mg/L 0.02 0.01 0.02
Zinc mg/L 2 0.5 2
Mineral oils mg/L 0.5
Total phenols mg/L 0.1
Total surfactants mg/L 0.5
THMs (sum) mg/L 0.03
Total chlorinated solvents mg/L 0.04
Benzo (a) pyrene mg/L 0.00001
Total pesticides mg/L 0.5
Aromatic Nitrogen S o l v e n t s mg/L 0.01
Benzene mg/L 0.001
Pentachlorophenol mg/L 0.003
Total coliform No./100 mL 2.2 (7 d med)
23 (30 d max)
Fecal coliform (or E. coli) No./100 mL < 10
E. coli No./100 mL 10 (80%)
100 (max)
Specific pathogens May be required
aGuideline depending on crop sensitivity; bPhysical or chemical processing sufficient to destroy pathogenic microorganisms. Less restrictive requirements
may apply wh ere there is no direct contact bet ween recl aimed wat er and t he edibl e portion of the crop ; c Food cr ops eaten raw where t here is di rect contact
between reclaimed water and the edible portion of the crop.

E. RANIERI ET AL. 306
 Trace constituents in the wastewater from Apulia
that would create a health hazard if the water was
used for irrigation directly. As stated previously, in
other countries, the primary health hazard that is
addressed is pathogenic microorganisms, thus the
requirement for filtration and disinfection. Where
the primary risk is due to short term exposure, mi-
crobial pathogens are more relevant constituents. It
should also be noted that in California and Australia,
microbial risk is managed, in part, through specifi-
cation of the treatment process and reasonable lim-
its for indicator organisms.
 Other countries developed their water quality stan-
dards for reclaimed water irrigation in the 1970s,
prior to awareness of trace chemicals that are now
well documented in water. Similarly, the analytical
capabilities to measure these constituents have made
it more feasible to screen for these chemicals in
water. However, there does not seem to be suffi-
cient evidence to support the belief that the pres-
ence of these chemicals in water will create a health
hazard due to deposition on the crop or through
bioaccumulation. Thus, the basis for the standards
should be reviewed to confirm that it is consistent
with modern scientific understanding.
6.2. Comparison of Treatment Technologies and
Costs
Treatment technologies and then the design of the water
reuse treatment plant depend on the specific regulatory,
so the design and the operational cost are quite different.
As evidenced in Table 3 though in Apulia standards
are so restrictive no specific treatment is required neither
suggested. The selection of a treatment process depends
on site constrains, local expertise, and reliability in meet-
ing regulatory goals. In general, the treatment process
used most commonly for production of reclaimed water
for unrestricted irrigation consist of a conventional acti-
vated sludge process followed by coagulation, floccula-
tion, filtration, and disinfection.
In Ta ble 4 are reported the operational costs based on
the average flow in terms of cent US $ per cubic meters
of treated water as reported in the wwtp monthly fact-
sheets.
The cost for Foggia wastewater treatment plant, al-
though not high in ab solute, are the highest in evaluation
comparison, due to the more technologies applied. There-
fore if there is no documented need as a consequence of
chemical micropollutant in reclamation plant influent
those technologies should be avoided, bypassing them,
for containing costs.
Due to the difficulty of reaching so low standards a
full physical-chemical is necessary in Italian case.
Pre-ozonation has the function of breaking the organic
complexes molecules and to transform them in a more
absorbable composts. In the following GAC treatment
the very low concentrations of chemicals are ensured. It
is important to note that the existing treatment facilities
of most large cities are located inappropriately with re-
spect to water reuse, the use of all types of satellite and
decentralized systems will become critical in the future
[15], especially where no complex treatments were re-
quired.
6.3. Impacts of Seasonality
Seasonality is important either for the different water
crops demand either for the different water characteris-
tics entering in reclamation plant.
In both Monterey and Adelaide, there was a relatively
urgent need to provide supplemental irrigation water to
Table 3. Summary of treatment requirements for unrestricted irrigation with reclaimed water.
Region Treatment required
California Oxidation, coagulation, filtration, disinfection
Southern Australia Oxidation, coagulation, filtration, disinfection
Southern Italy Not specified
Table 4. Operational costs for three analyzed plants in US cent$/m3.
Operational cost Approximate unit cost, cent$/m3
Monterey Adelaide Foggia
Electricity 1.8 1.7 3.7
Chemicals 3.0 2.9 0.4
Maintenance-replace 2.3 2.2 4.5
Labour 1.2 1.1 1.3
Total 8.3 7.9 9.9

E. RANIERI ET AL. 307
support the existing agricultural industry. The quality of
the water that was available for irrigation had been com-
promised due to long term over extraction followed by
sea water intrusion. Interestingly, Apulia is also subject
to periodic drought conditions that are anticipated to
worsen in the future. During drought events, farmers in
the Apulia region rely on groundwater to make up the
required irrigation water, but the amount of available
groundwater is limited and the quality is marginal. While
there are plans to import additional water from the sur-
rounding countries, this approach is subject to many
conditions. The implementation of a water reuse scheme
seems to be suitable for supplying some of the irrigation
water demand in Southern Italy, yet in this region only
two treatment facilities have the capacity to produce rec-
laimed water that can meet the applicable water quality
standards. Thus, the regulatory requirements are inhibit-
ing the use of reclaimed water for food crop irrigation.
6.4. Acceptability of Product
A pilot study [16] revealed that the public presents a
strong hesitation towards any wastewater reuse applica-
tion schemes related to food production, partially due to
lack of adequate information as well as trust towards
ruling and monitoring bodies. Their greatest fears are
related to inappropriate food production and dangerous
consumption, and as a result when reuse suggested ap-
plications became increasingly related to food they were
presenting an increasingly negative approach. This, in
correlation to their fear of a chemical toxic substance in
the wastewater (primary reason of hesitation according to
their responses), which can not be removed with existing
technology (71% believe that) and by authorities (private
or public) that can not be trusted (more than 60% of
those answered feel this way) explain their hesitations.
Concern that irrigation with reclaimed water would
harm the image of crops produced in Italy and, therefore,
impact the marketability of Italian agricultural products.
In both Monterey and Adelaide, these concerns also ex-
isted initially, but later proved not to be an issue. Thus,
the lack of experience with water reuse programs could
be a major factor contributing to the highly restrictive
water quality standards.
7. The Future for Agricultural Reuse
7.1. Increase in Urban and Ecological Water Use
Freshwater demand is more and more increasing not only
in more industrialized country but also in areas characte-
rized by water scarcity. The economic and social devel-
opment caused an increase in the demand of freshwater
for domestic, industrial and agricultural sectors. Water
resources management clearly impacts on many other
policy areas (e.g., energy projections, land use, food se-
curity and nature conservation). Adequate tools are not
available to facilitate the appraisal of adaptation and mi-
tigation options across multiple water-dependent sectors,
including the adoption of water-efficient technologies
and practices. In the absence of reliable projections of
future changes in hydrological variables, adaptation pro-
cesses and methods which can be usefully implemented
in the absence of accurate projections, such as improved
water-use efficiency and water-demand management, of-
fer no-regrets options to cope with climate change [17].
It should be added that water stress is also increasing
due to population density, diffused pollution and short-
-term seasonal population increases due to tourism and
increased demand for irrigation to improve agricultural
productivity. At the same time, the EU Water Frame Di-
rective requests an analysis of water use, which in some
regions or basins could lead to a reduction of 15 – 20%
of abstraction licenses, in order to protect surface and
groundwater quality and quantity [18].
7.2. Increase in Salinity
Many areas of South West of Australia, California and
Apulia are seriously affected by the increase of salinity
problem due to the excessive use of groundwater and to
the higher level of the sea-water interface.
For example, salinity levels in the headwaters of the
Murray-Darling Basin in Australia are expected to in-
crease by 13% - 19% by 2050 [19]. In general, decreased
groundwater recharge, which reduces mobilization of
underground salt, may balance the effect of decreased
dilution of salts in rivers and estuaries. Recent analyses
of climate change over California have provided projec-
tions of the range of warming and other changes that the
region may face by the end of the 21st century. The pro-
jected reduction in surface water availability and poten-
tially increased water requirements is expected to cause
California's far mers to respond b y supplementing availa-
ble irrigation wate rs by incre a si ng gr o un d w at er pumping.
However, increased pumping will increase energy costs,
and diminishing quality of groundwater ap plied as irriga-
tion water will generally increase soil salinity [20].
The Apulian (Southern Italy) karstic coastal aquifers
consist of three types of aquifer zones: 1) areas with low
vulnerability to seawater intrusion, 2) areas with high
vulnerability and 3) areas with variable vulnerability in
which the salt degradation largely depends on the ability
to manage the well discharge. The water quality degra-
dation caused by seawater intrusion appears to be a com-
bined effect of an anomalous succession of drought pe-

E. RANIERI ET AL.
308
riods observed from about 1980 onwards and increased
groundwater pumping, particularly during drought pe-
riods [21].
An important issue should regard the salinity: due to
the high level of salinity content in the influent, limit
should not be mandatory about this and it should based
on the characteristic of the crops and of the source water
[22].
Moreover artificial recharge of groundwater basins
with treated wastewater should be recommended when
the water is not used for agricultural purposes particular-
ly where conjunctive use of surface water and ground-
water resources is considered in th e context of integrated
water resource s m a nagement [1,23].
7.3. Impacts of Climate Change
Agriculture is not only a fundamental human activity at
risk from climate change. About 1.4 billion ha of arable
land (10 percent of total ice-free land) are used for crop
cultivation and an additional 2.5 billion ha are used for
pasture. In addition to land resources, agriculture is a
major user of water. Over 200 million ha of arable land
is under irrigation, utilizing 2 500 billion m3 of water
annually, representing 75% of fresh water resources
withdrawn from aquifers, lakes and rivers by human ac-
tivity [24].
It is projected that climate change will have a range of
impacts on water resources and then in cropwater de-
mand. In general, while moderate warming in high-
latitude regions would benefit crop and pasture yields,
even slight warming in low-latitude areas, or areas that
are seasonally dry, would have a detrimental effect on
yields. Regions where agriculture is currently a marginal
enterprise, largely due to a combination of poor soils,
water scarcity and rural poverty, may suffer increasingly
as a result of climate change impacts on water [25].
Global warming has increased the frequency and se-
verity of natural disasters like the drought. 0.75°C is the
increase of the temperature over the past 15 years and
this result in a lot more of evap oration.
Warm air holds more moisture, carrying it away from
dry areas and towards wetter ones. Thus as global tem-
perature rise, dry areas will likely get drier an d wet areas
wetter. Seasonal extremes will l ikewise inten sify, as mois -
ture accumulated in the dry season is shed in downpours
in cooler times, leading to seasonal floods in regions
otherwise prone to drought.
Atmospheric warming is also predicted to affect rain-
fall by altering global air circulation. At present, warm
air carried from the topics by circulation loops called
Hadley cells meets cool polar air carried by Ferrel cells
in zones around 30° no rth and south, creating arid zones.
As the planet warms, these zones are expected to expand
and shift towards the Poles [9].
So while annual runoff increases are projected in At-
lantic- and northern Europe [26], and decreases in central,
Mediterranean and Eastern Europe [27- 30].
This event brought farmers to an unsustainable situa-
tion. So water consumption crops as rice and cotton have
been removed and substituted with grapes and fruits that
needs less water; but farmers are seriously worry on what
to do for living in the next future.
There is a consensus [30] that Mediterranean Basin
(South Italy), South Western USA, Southern Australia
will become more arid. This poses a particular risk for
regions that already subsist on minimal rainfall or that
depend on rain-fed agriculture. Meanwhile an hotter cli-
mate contains more moisture, this will not necessarily
translate into more rain but it is likely to translate into
changes in where the rain falls; and when the rain does
come, it will likely arrive in more intense bursts, in-
creasing the risk of flooding even in areas that are drying
out. In fact IPCC notes that heavy precipitation events
are projected to become more frequent and that an in-
crease in such events is probably already contributing to
disaster.
8. Conclusions
In the drought-stricken regions such as Southern Italy,
Australia, and Southern California, where the additional
resources brought by wastewater reuse can bring signifi-
cant advantages to agriculture (e.g. crop irrigation) and
tourism (e.g. golf course irrigation).
A comparison between three wastewater reclamation
plant has been carried out. Differences in the complexity
of the technological treatments are due to different regu-
lations, so a standardization of the regulation is recom-
mended around the world where standards should be
addressed more to microbial community and pathogenic
than to chemical constituents.
The most technological treatment plant (Foggia) re-
sults in a 30% higher operational costs as average. The re-
fore these treatments should be justified only with a
heavy industrial contaminated wastewater influent.
The impact of climate change on water resources
strongly suggests the improvement of wastewater reuse
all the world.
It is also suggested the improvement of the artificial
groundwater recharge because this is becoming increa-
singly important in groundwater management and partic-
ularly where the conjunctive use of surface water and
groundwater resources is planned.
About salinity, this limit should be based on the cha-
racteristic of the crops and of the source water and

E. RANIERI ET AL.
309
should not be ma ndat o ry abo ut thi s.
However wastewater reuse should be encouraged by
government financial aid so that costs of wastewater
should be comparab le with that of fresh water supply and
that should b e adopted not only when is a need in period
of for water shortage all the year round and year by year.
9. Acknowledgements
The authors would like to thank all the personnel of De-
partment of Environmental Engineering and Sustainable
Development of Technical Unversity of Bari and, in par-
ticular Prof. Edward Schroeder, University of California
at Davis for his help and assistance. Special thanks to the
Dean of Faculty of Engineering of Taranto.
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