Agricultural water reuse: review - WIT Press · Agricultural water reuse: a review C. Lubello & R. Gori Civil Engineering Department, University of Florence, Italy. Abstract In this

Agricultural water reuse: a review

C. Lubello & R. Gori Civil Engineering Department, University of Florence, Italy.

Abstract

In this work we present an analysis of the state of water reuse in agriculture throughout the world. We have tried to show all the different aspects in the development of water reuse: the regulations, national and international guidelines, technological and planning issues, major full-scale applications, and, lastly, recent findings in research. There are many countries interested in reuse practice and significant efforts are being made to demonstrate the utility of wastewater reuse, hence, a process to harmonise the qualitative standards is required by a highly integrated economic market of agricultural products. T h s need is deeply felt in the Mediterranean area where an invaluable experience has been attained, able to guide the systematic development of wastewater reuse in agriculture.

1 Introduction

Reclaimed wastewater is becoming an important element in the water cycle (for example U.S.G.S. [l] , Angelakis et al. [2]), due to different factors and above all: limited traditional sources, a growth of domestic consumption, population increase and, consequently, of irrigation. As far as the increase of consumption is concerned, the trends in developed and developing countries will lead to an increase in global water withdrawals from 3,800 ICrn3 in 1995 to 4,300-5,200 Km3 in 2025 (World Water Council 131). The difference will largely depend on how much irrigated agriculture does or does not expand. According to Shiklomanov [4], on the grounds of optimistic assumptions concerning yield and efficiency improvements, by 2025 water use for agriculture will have to increase

Transactions on Ecology and the Environment vol 49, © 2001 WIT Press, www.witpress.com, ISSN 1743-3541

388 Water Pollution 17

at least 17% from 1995. Another factor that can stimulate the reuse of reclaimed water is the cost of supplies when exploiting both existing and new conventional water resources. The costs of reclaimed wastewater, in many cases, are low also if compared with those of other unconventional water resources. The problem connected to water supplies could depend more on the difficulty of obtaining it at reasonable costs in the right place, at the right time and with specific quality requisites, rather than on its scarcity in terms of per capita requirements. According to Alcamo et al. [5] and IWMI [6], many countries which have sufficient water resources to meet their needs, will have to increase water supplies by 25% or more to meet their needs within 2025. It means that in many cases increasing the exploitation of existing water resources (for example through additional storage, conveyance, and regulation systems) or starting the exploitation of new water resources could be necessary. In this scenario reclaimed wastewater may be a low-cost alternative (for example GiuffrC [7], Wilf [S], A1-A Ama [9], Al-Zubari [10]).

2 Development of agricultural water reuse

The use of reclaimed or raw wastewater is a very ancient practice that already existed in 3000 BC in the Minoan civilisation whereas in modem times, the first examples applied were the "sewage farms" which originated in Germany in 1550 and in Britain in 1700 (Asano and Levine [l l]). The main developments in wastewater reuse began in the 60s: indeed, the Californian legislation stimulated wastewater reclamation as well as reuse practices and in Israel, the employment of secondary effluent for crop irrigation was begun. During the 70s and SOS, important research projects on wastewater treatment systems and the effects of reclaimed wastewater reuse were carried out and demonstrated the possibility to produce irrigation water and ensure production of agricultural crops in consort with protection of public health. Special mention should be made of the 'Pomona Virus Study' and the 'Monterey Wastewater Reclamation Study for Agriculture' (Asano and Levine [12]). Reuse for irrigation purposes in agriculture is still the most commonly practised throughout the world. On the ground of the available information the reuse of reclaimed wastewater can be roughly subdivided as shown in Figure 1.


mother uses

Figure 1: Volume percentage subdivision of reclaimed wastewater utilisation.

The main reason is due to the fact that agriculture world-wide is the field that requires the highest water consumption and there are therefore vast possibilities for the reuse and preservation of primary resources. In agriculture, 67% of the world water consumption is employed (Asano and Levine [ l l]), and 62% on average, in the countries of southern Europe (Italy, Spain, Greece, Portugal) (EEA [13]), from 70% (Israel) to 93% (Morocco) in the other Mediterranean countries (Angelakis et al. [ 2 ] ) and 40% in the USA (U.S.G.S. [l]).

3 Reuse Standards and Guidelines

The possibility of wastewater reuse in agriculture depends on a number of regulations and guidelines aimed at reducing possible adverse health effects (consumers and operators), on the environment and irrigated products. Generally speaking, the parameters subject to complete guidelines can be subdivided into four categories as shown in Table 1.

Table 1. Water quality parameters involved in reclaimed wastewater reuse (Adapted from EPA [14]).

Protozoa, Helmints, Total Coliform, Faecal C o l i f o q Micro-organisms

Bacteria, Virus Helmints egg, Salmonella

Categories

General I Suspended solids, I Total suspended solids, nitrogen,

Class Examples

Parameters

Inorganic parameters

Organic parameters

nutrients, pH

Dissolved inorganic compounds, heavy metals

Phosphorous, pH

Total dissolved solids, Conductivity, specific ions

Organic compounds BOD, COD, TOC, specific

compounds (pesticides, IPA,. . .)


Microbiological quality is the most contentious issue linked to wastewater reuse in irrigation. In Table 2 is shown a classification of the microbiological limits introduced by the main regulations and guidelines of the countries where they have been applied. The WHO guidelines represent the minimum below which everybody agrees that public health protection is not guaranteed. Since these guidelines have a world-wide scope, they were also designed to stand realistic chances of being applied in developing countries, where an unnecessarily rigid stance would most probably result in them being ignored (Mara and Cairncross [15]). The only specific criteria the WHO is proposing are microbiological. Work has now started on chemical guidelines (Chang et al. [16]). On the other hand, the Californian standard, the first in chronological order, is very stringent with extremely limited values on the bacterial load, the achievement of which necessarily requires the introduction of special treatments. At European level, the only reference to wastewater reuse is article 12 of the European Wastewater Directive (9 1/27 1iEEC) (European Commission [l 71) stating: "Treated wastewater shall be reused whenever appropriate". The absence of a standard at a European Community level determines the presence of considerable confusion among Mediterranean countries concerning health standards for wastewater reuse.

Most countries (for example Spain, Portugal, Greece) have no guidelines at all. Others have adopted the up-to-date World Health Organisation Guidelines, while others, fearing that the importing countries may ban the import of their agricultural products, have established extremely strict standards for wastewater irrigation, approaching those of drinking water, following the lead of California. There is now an urgent need to develop uniform hygienic wastewater reuse guidelines and standards for all the countries of the Mediterranean basin. Uniform guidelines and standards are vital in the Mediterranean area in the light of the high level of interaction and contact between these countries, both in the fields of food imports and exports as well as tourism. There are two aspects that actually unite the regulations: the existence of a difference between unrestricted irrigation (water used for all crops) and restricted irrigation (water used for plants which cannot be eaten raw) and the explicit requirement of a minimum standard for the reclamation of wastewater reuse. Moreover, it should be observed that some regulations (e.g. in several States of the USA, in Cyprus, in Tunisia) prohibit the irrigation of edible products to be eaten raw while in other cases there are rules on the irrigation methods to be adopted, the selection of crops for irrigation and on the periods between irrigation and harvesting.


Table 2. Summary of law or guidelines concerning water reuse in agriculture. TC (Total Colifonns), FC (Faecal Coliforms), SF (Fecal Streptococci) and Ecoli (Escherichia Coli) referred to 100 ml; Ne (Nematode eggs), Sal. (Salmonella) and Te (Taenia eggs) referred to 1 liter.

WHO (GD) F C < 1000/Ne< l

California 'Title 22' (L) TC < 2.2

USEPA (GD) 1C: No detectable

Italy (L) TC < 2 I

I Ecoli < 1000 1 France (proposed)

Sal. and Te: No detectable

Spain (proposed) FC< 1 0 / S F < IO/Ne< l 4

Israel (L) I Ecoli < l0

Cwms (L) I FC < 50. Ne : No detectable

Tunisia (I.) I Saudi Arabia (L) F C < 2 . 2 / N e < l

China (L) TC 100

Japan (GD) I TC: No dctectable

Aust~alian EPA (GD) I FC < 300

Mexico (L) F C < 2 0 0 0 / N e < l

Main physical-chemical

TSS, BODj

Note and (References)

Turbidity

Turbidity, BOD5, pH, chlorine

pH, TSS, SAR, BODj, chloride ,...

(CSHPF, not published)

(WHO [181)

(EPA [141)

(EPA [l411 Presence of regional standards (D-Lgs. 152199)

-

TSS, BOD5, pH, chlonne Presence of reg~onal standards (Bontoux [20]) I

'TSS. B O D ~ I Irrigation of vegetables is not allowed (Angelakis et al. 121)

TSS, BODj

i Irrigation of vegetables consumed raw is not allowed pH, EC, BODs, TSS ,...

(Angelakis et al. 121)

(Israeli ministry of Health, not published)

1 Some States have adopted local guidelines (Levine et al. 1241)

Turbidity, pH, TSS, BODs,.. .

pH, salinity, chloride,. . .

pII, chlorine

1 (Blurnenthal et al. 1251)

(Abu-Rizaiza [2 l ] )

Irrigation of vegetables is not allowed (Pinjing et al. [22])

Absence of uniform standards; applicable criteria have been

established by various ministries (Ogoshi et al. [23])


4 Water reuse and agricultural water reuse world-wide

Reliable estimates of the current extent of water reclamation activity are limited and often contradictory.

4.1 The United States

The USA has the world's largest formalised water reclamation market. In the United States as a whole, four states dominate reuse activity: Florida with 1.855 Mm3/d, California with 1.21 1 Mm3/d, Arizona with 0.795 ~ r n ~ / d and Texas with 0.832 ~ m ~ / d (Hoffman [26]). This accounts for 87% of all reuse in the USA (see Figure 2) which totals approximately 5.3 Mm31d.

Others (1 3%) 1 n Florida

California (35%) (22%)

g Texas Arizona

(15%) (1 5%)

Figure 2: Volume percentage of reclaimed wastewater reused in the USA.

The current experiences are numerous: in 1999, 431 water reuse systems were activated in Florida (Florida Department of Environmental Protection Division [27]) and 190 in Texas (Hoffman [26]). Most of the experiences deal with wastewater reuse for irrigation but there are several examples of vast scale experiences in other fields. Every day in the USA (1995) 2.73 Mm3 of reclaimed water is reused in agriculture and the sites of reuse are mainly located in California (0.97 Mm3/d), Florida (0.84 Mm3/d) and Arizona (0.47 Mm3/d) (U.S.G.S. [l]). The State of California is recognised all over the world as the leading country in the development of wastewater reuse in agriculture. In 1918, the State of California developed the first water reuse regulations. In this State important experiences were carried out leading to a significant technical and scientific impact in this field (for example 'The Monterey Wastewater Reclamation Study for Agriculture'). Among the more recent implemented Californian plants, two should be mentioned. The first is used for the irrigation of 4,000 ha of farmland in Northern Monterey County from 1998, where crops including lettuce, broccoli, cauliflower, celery, artichokes and spring onions are grown. This facility supplies 27 Mm31y of municipal recycled water (DPI [28]).


Water Pollution 1.7 393

The second, the Castroville Seawater Intrusion Project, delivers 80 Mm31y of reclaimed water to irrigate crops, including vegetables (DPI [28]). The reclaimed water is subject to secondary treatment, filtration and disinfection to meet Californian standards. The irrigated crops include lettuce, broccoli, celery, cauliflower, artichokes and others. The State of Florida has 23 plants that irrigate edible crops with secondary treated, filtered and disinfected recycled water (DPI [28]). One of the main reuse projects is 'Water Conserv 11' which supplies 18.5 Mm31y of reclaimed water to agriculture (mainly for citrus growers and nurseries) and 20 Mm31y to aquifer recharge (DPI [28]).

4.2 Latin America

Reuse of reclaimed water, except for Mexico, is a still rarely applied practice and the first installations in Chile and Argentina have only recently been opened (FAO [29]). Instead, according to FAO [29] in Mexico 1,600 Mm31y of treated and untreated water is consumed for irrigation. Mexico City is the largest single user of wastewater in the world (Khouri et al. [30]).

4.3 GCC countries

At the present time, the six GCC (Gulf Cooperation Council) States (Bahrain, Oman, Qatar, Kuwait, and Saudi Arabia) recycle 403.5 (about 35% of their total treated wastewater), mainly for landscaping, fodder crop irrigation and industrial uses (Al-Zubari [IO]).

4.4 Asia and the Far East

The reuse of wastewater as an alternative water resource has not yet been sufficiently developed. Exceptions can be found in China and Japan. In Chma, 13,390 ~m~ of recycled water is used every year and represents almost 30% of the total volume of reclaimed water and 25% of the total withdrawal in China (FAO [3 l]). Water reclamation activities in Japan are primarily directed towards non-potable urban applications. In 1997 in Japan, 206 ~m~ of water was reclaimed, 8% of which only in agriculture (Ogoshi et al. [23]).

4.5 Australia

This country has a small but growing water reuse market. Approximately 90 of Australia's urban wastewater was recycled in 1997 for industrial and

irrigation purposes, projected to be increased to 200 ~ m ~ / ~ by the year 2000.


394 Water Pollution I.'!

Water reclamation experiences are practised in all the most important States in Queensland, North South Wales and South Australia (DPI [28]).

4.6 Europe

Generally speaking, recycling is less commonly practised than in the USA. However, in many countries several reclamation facilities have been implemented. Furthermore, the existence of numerous pilot plants reveal growing interest and research in this field. At present, the most important use of reclaimed water in Europe is for different irrigation purposes (e.g. crop cultivation, public gardens, parks and golf courses), especially in Southern Europe, followed by industrial use. In France, there now exist 19 recycling plants, mainly for the irrigation of golf courses (7), maize (4), nurseries (3), but also orchards, parks and sports facilities. The water undergoes at least secondary treatment and frequently even a tertiary process, usually obtained with lagooning (Faby J.A. et al. [32]). Reclamation experiences in Spain are less frequent, but this practice, especially in the case of irrigation, is increasing rapidly. The experiences of the Canary Islands are particularly interesting. In Gran Canary around 25 million m31y of treated water is used, mainly for irrigation purposes of tomato and potato fields, and in Tenerife around 430 ha of bananas, tomatoes and other tropical h i t s are irrigated with reclaimed water (EEA [33]). In Portugal, there are few cases of planned irrigation with treated wastewater, especially orchards and vineyards, and also golf courses. Research has been carried out and the use of the effluent of a large wastewater treatment plant has been planned near Lisbon to irrigate 1,000 ha of various crops (Angelahs et al. [2]). Although the potential for the irrigation of agricultural land is high, at present only 1.4% of recyclable municipal water is used for agriculture (Angelakis, unpublished). Nevertheless, some important research projects have been carried out at Chalkida, Creta and Thessaloniki (Angelakis et al. [2]).

4.7 Other Mediterranean countries

Recycling is an established practice which is rapidly increasing. In many cases reclaimed water is the only option to expand the potentiality of water supplies (Angelakis et al. [2]). As many Mediterranean countries are typically agricultural, especially North Africa and the Middle East, and owing to the limited use of industrial activities in these countries, reuse water plants are almost entirely dedicated to agricultural purposes. In this area, Israel was a pioneer in the development of wastewater reuse practices. As early as 1987, there were more than 200 reclamation plants. About


92% of wastewater is channelled to wastewater plants and 72% of the effluents is subsequently recycled for irrigation (42%) (Juanico and Friedler [34). The aim is to make all the effluents suitable for an unlimited irrigation use. 'The Jeezrael Valley project' (6 ~ m ~ / ~ ) and 'The Dan Region project' (7900 m3/h) are the principal reuse projects implemented in Israel. As far as the other countries are concerned, the practice for recycling water for agricultural purposes seems to be absolutely indispensable. This is the case of Cyprus where tertiary wastewater is required for the development both of the agricultural and industrial sector (EEA [33]). Important experiences have been carried out and have been planned in Malta (EEA [33]) and in Tunisia, malnly located around Tunis (Bahri and Brissaud [35]).

5 Research development

In order to single out present research trends, a consultation was made of some databanks (COMPENDEX, BEILSTEIN ABSTRACT, BIOBASE, GEOBASE) connected to numerous important scientific reviews in the field of environmental sciences, engineering and agriculture. The research concerned the period fiom January 1995 to December 2000. In Table 3 the selected works were classified according to the countries of origin of the researchers (wherever there were several countries of origin, the country of the first author mentioned was chosen) and according to the subject of the research. The Mediterranean area produces the lughest number of works, followed by Europe and the United States. Most of the publications deal with the treatment and possible effects on health and plants due to reclaimed water. There are very few works on the development of guidelines, a subject which has gave rise to much scientific debate in the past. In Table 4 the classification was made of works dealing with water treatment. It is interesting to note how many of the works are dedicated to natural treatments (waste stabilisation ponds and wetlands). These efforts reveal the necessity of finding economic treatment systems to make a practice, highly influenced by the low added value of production, sustainable. However, the works dealing with membrane treatments appear to be extremely interesting. Although these processes are very expensive, they draw the attention of researchers because of the hlgh water quality standards that can be achieved.


396 Water Pollution W

Table 3. Classification of publications on water reuse in agriculture. (*) The figure may vary from the sum on each line as in some publications the two most important themes have been considered.

Environmental impact 1 1 Water resource management 1 4

Economics Health 4

Wastewater management 2 Case studies 4

Other 1 6

Table 4. Classification of publications on wastewater treatment for water reuse in agriculture

l Disinfection Particle removal Biologic treatment Waste stabilisation ponds and wetlands Infiltration-percolation Membrane

l Other


6 Conclusions

Wastewater reuse in agriculture is one of the most interesting topics, both in the field of environmental research and in water conservation planning. The result of this work shows the need of more uniformity in the qualitative standards of treated waters, especially in the field of hlghly integrated agricultural markets. The attention of research is dedicated to technological aspects as well as management and health problems. The examples of full-scale application are numerous and widespread in many parts of the world. Thls undoubtedly reveals the technological and economic sustainability of wastewater reuse in agriculture.

References

U.S.G.S. (US. Geological Survey). Estimated Use of Water in the United States in 1995, Circular 1200, 1998. Angelakis, A.N., Marecos Do Monte, M.H.F., Bontoux, L., & Asano, T. The status of wastewater reuse practice in the mediterranean basin: need for guidelines. Water Research, 33(10), pp. 220 1-22 17, 1999. World Water Council. A Water Secure World, World Water Commission Report, 2000. Shlklornanov, I.A. World water resources and water use: present assessment and outlook for 2025, State Hydrological Institute, St. Petersburg, 1999. Alcamo, J., Henrichs, T., & Roesch T. World Water in 2025: global modelling and scenario analysis for the World Commission on water for the 21'' century, University of Kassel, Center for environmental system research, 1999. IWMI (International Water Management Institute). Water supply and demand in 2025, Colombo, 2000. Giuffre G. The British experience of wastewater reclamation and reuse, Proc. Of the Int. Con$ On Advanced Wastewater Treatment, Recycling and Reuse, eds. L. Bonomo, & C. Nurizzo, pp. 859-861, 1998. Wilf, M. Reverse osmosis membrane for wastewater reclamation (Chapter 7). Wastewater reclamation and reuse. ed. T. Asano, Technomic Publishmg Company: Lancaster, pp. 263-344, 199 - A1-A Arna M.S. Wastewater reuse in J~.~-ail , Saudi Arabia. Water Research 29(6), pp. 1579-1584, 1995.

[l01 Al-Zubari, W.K. Towards the establishment of a total water cycle management and re-use program in the GCC countries. Desalination 120 (1-2), pp. 3-14, 1998.


Water- Pollutiorl C'I

Asano, T., & Levine, A.D. Wastewater reclamation recycling and reuse: an introduction (Chapter 1). Wastewater reclamation and reuse, ed. T. Asano, Technomic Publishing Company: Lancaster, pp. 1-56, 1998. Asano, T., & Levine, A.D. Wastewater reclamation recycling and reuse: past present and future. Water Science and Technology 33(10-ll), pp. 1-14, 1996. E.E.A. (European Environment Agency). Sustainable water use in Europe: Sectoral use of water, Environmemtal asseessmenrt report No. 1, Copenhagen, 1999. EPA. Guidelines for Water Reuse: Manual, Report No. EPA-625lR-92-004, Cincinnati, 1992. Mara, D.D., & Caimcross, S. Guidelines for the safe use of wastewater and excreta in agriculture and aquaculture, WHO, Geneva, 1989. Chang, A.C., Page, A.L., & Asano, T. Developing human health-related chemical guidelines for reclaimed wastewater and sewage sludge applications in agriculture, WHO, Geneva, 1995. European Commission Council. Directive concerning urban wastewater treatment 911271lEEC of May 21, 1991, OJ No L 135140 of May 30, 1991. WHO, Health guidelines for the use of wastewater in agriculture and aquaculture, WHO Report No. 778, Geneva, 1989. Ministero dell'Ambiente. Disposizioni sulla tutela delle acque all'inquinamento e recepimento della direttiva 9 1127 1lCEE concernente il trattamento delle acque reflue urbane e della direttiva 911676lCEE relativa alla protezione delle acque dall'inquinamento provocato dai nitrati provenienti da fonti agricole, Gazzetta Ufficiale no 177 del 3017199 - Suppl. Ord. no 146, 1999. Bontoux, L. Municipal Wastewater: Public Health and The Environment, IPTS (Institute for Prospective Technological Studies) Report, Vol. 18, 1997. Abu-Rizaiza, O.S. Modification of the standards of wastewater reuse in Saudi Arabia. Water Research 33(11), pp. 2601-2608, 1999. Pinjing, H., Phgan, L., Gowei, G., & Hervouet, G. Reclaimed municipal wastewater - a potential water resource in China, Proc. of the I" World Water Congress of the International Water Association, Vol. 8, pp. , 2000. Ogoshi, M., Suzuki, Y., & Asano, T. Water reuse in Japan, Proc. of the Is' World Water Congress of the International Water Association, Vol. 8, pp. , 2000. Levine, B., Lazarova, V., Manem, J., & Suffet, I.H. Wastewater reuse standards: goals, status and guidelines. Proc. of the Con$ On BeneJicial Reuse of water and biosolids, pp. 13160-1 317 1, 1997.


Water- Polluriot~ 1.7 399

[25] Blumenthal, U.J., Peasey, A., Ruiz-Palacios, G., & Mara, D.D. Guidelines for wastewater reuse in agriculture and aquaculture: recommended revisions based on new research evidence, WELL (Water and Environmental health at London and Loughborough) Task No. 68, Part 1,2000.

[26] Hoffman, H.W. Texas Water Reuse Update, Texas Water Development Board, 1998.

[27] Florida Dept. of Environmental Protection Division of Water Resource Management. 1999 Reuse Inventory Report, The State Of Florida, 2000.

[28] DPI (Department of Primary Industries). Agricultural Water Recycling Background Study, State of Queensland (Dept. of Natural Resources), Report No. BR2-QDNRO1002,2000.

[29] FAO. Irrigation in Latin America and the Caribbean in figures, Water Report No. 20,2000.

[30] Khouri, N., Kalbermatten, J.M., & Bartone, C.R. Reuse of wastewater in agriculture: A guide for planners, UNDP-World Bank Water and Sanitation, Report No. 6., Washington D.C., 1994.

[31] FAO. Irrigation in Asia in figure, Water Report No. 18, 1999. [32] Faby, J.A., Brissaud, F., & Bontoux, J. Wastewater reuse in France: water

quality standards and wastewater treatment technologies. Proc. Of the Int. Con$ On Advanced Wastewater Treatment, Recycling and Reuse, eds. L. Bonomo, & C. Nurizzo, pp. 51-58, 1998.

[33] E.E.A. (European Environment Agency). Sustainable water use in Europe: Demand management, Environmerntal issue report No. 19, Copenhagen, 2001.

[34] Juanico, M., & Friedler, E. Wastewater Reuse for River Recovery in Serni- Arid Israel. Water Science and Technology 40(4-S), pp. 43-50, 1999.

[35] Bahri, A., & Brissaud, F. Wastewater reuse in Tunisia: assessing a national policy. Water Science and Technology 33(10-ll), pp. 87-94, 1996.


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Agricultural water reuse: review - WIT Press · Agricultural water reuse: a review C. Lubello & R. Gori Civil Engineering Department, University of Florence, Italy. Abstract In this