Treating wastewater for agricultural use is desirable, but the devil is in the details
Growing water crises have drawn attention to the promise of water reuse. When safely treated and well-integrated in water planning, treated effluents are a reliable water resource that can alleviate water shortages and offer a source of nutrients to agricultural lands (Sadoff and Jagerskog, 2017). However, while undoubtedly desirable, implementing reuse policies and projects comes with tremendous governance challenges.
Lebanon illustrates this well. It is plagued by water shortages resulting from a policy focused on full cost recovery and commercialisation and privatisation of services (see Alles, 2019; Eid-Sabbagh, 2015; Riachi, 2014). After 30 years of reconstruction and institutional reforms, public supply of municipal or agricultural use does not approach meeting the demand and remains unreliable, while private supply, coupled with the state's inability to regulate, has led to degradation of the resource, falling groundwater levels and social conflict.
Notwithstanding some USD 1.5 billion investments in the wastewater sector over the last 30 years, only 25-30% of wastewater is actually treated. Of this, only around 10% (or about 80,000 m3/day), receives secondary or tertiary treatment. In this context, safe water reuse in agriculture is presented as an opportunity to increase water for irrigation, as well as providing additional revenue for water utilities.
A recent IWMI study conservatively estimated that some 2200 ha could "potentially" be irrigated safely with treated wastewater in Lebanon (Eid-Sabbagh et al., 2021). It identified wastewater treatment sites that have "technical" characteristics that are conductive for the implementation of reuse systems. Most (61) are small plants with design capacities below 1500 m3/day managed by municipalities, half of which (30) are out of operation. The five largest wastewater treatment plants (WWTPs) have a combined design capacity of 400,000 m3/day of which only 35,000 m3/day are situated inland. The others are situated along the coast and have little agricultural area nearby.
The defined " potential" is an abstract measure. If it remains divorced from social and political reality, it is little more than an estimate of available wastewater related to estimated irrigation requirements.
The implementation of a policy for water reuse in irrigation is hampered by institutional overlaps and inter-agency competition that finds its roots in a sectarian political system premised on the need for consensus among parties. Chronic political gridlock is the result. This underlies the difficulties involved in producing and implementing a coherent national master plan and allocate the necessary budget, and the dynamics of competition over resources and administrative territories. For example, the Litani River Authority felt threatened by the possibility of the reallocation of freshwater resources under its purview and rejected any cooperation on wastewater reuse within irrigation networks under its management (Nassif, 2019).
Furthermore, planning is largely focused on infrastructure construction while management issues are largely neglected. Regional Water Authorities (RWEs) are legally charged with management of wastewater and irrigation in addition to water supply. But their human resources and organisational capacities are limited. Only one out of four RWEs has an organisational chart with provision for wastewater management; irrigation management is absent in all of them. All RWEs are seriously understaffed.
All RWEs are chronically underfunded as a result of an approach that unrealistically targets full cost recovery for services based on users' fees. RWE collection rates range from 30% to 78% and averaged just 50% of expected revenue in the years until 2019. RWEs have also been unable to take over the responsibilities of managing WWTPs because of their inability to carry the financial burden of these energy-intensive, complex-to-monitor infrastructures.
The recent financial, economic, and political crisis has compounded these challenges. RWE revenues have almost completely collapsed with the rapid impoverishment of the population while the costs of imported materials needed for operation and maintenance have risen in proportion to hyperinflation, making spare parts and fuel unaffordable.
Beyond the technical necessities, water reuse itself faces water allocation challenges at the local level. These are related to interpretations of water rights, the organisation of irrigation management, and the definition and perception of socially just distributive mechanisms. Since most treated wastewater produced inland and discharged into rivers is already reused further downstream, reallocating treated wastewater is problematic. Analysis of seven case studies shows that both raw and treated wastewater are claimed based on specific interpretations of customary or legal rights. In one case, farmers broke collector pipes of a newly built WWTP to reclaim their original source of irrigation water. In another, an interruption of treatment maintenance reasons led to complaints against the managing municipality because it interrupted treated water flows downstream in an adjacent municipality. Finally, social conflict may emerge over who gets access to reused water by the irrigation network water guardian or at an earlier stage at the conception of water reuse projects. These difficulties remain formidable for RWEs and the Ministry, which is susceptible to the influence of local notables and large landowners.
Depicting water reuse as a massive opportunity appears to be overly optimistic. Both the untreated and treated wastewater disposed in rivers is mostly used downstream indirectly – it is not "new" water. Lebanon's water reuse potential measured in ha remains an abstraction as its materialization would require in-depth policy and institutional transformation. Unfortunately, the Lebanese state seems to be poorly equipped to do so.
The complex politics of water reuse are not unique to Lebanon. In Egypt, the formal and informal reuse sectors exist side by side; much water is already reused. More importantly, efforts to move reuse "into the formal sphere" carries the danger of neglecting potentials and solutions to promote and improve reuse (Tawfik et al., 2020). A case study in Jericho (Palestine) identified unclear water rights among local communities as a major obstacle for the reuse of wastewater (Al-Khatib et al., 2017).In Hyderabad, India, the Musi river running through Hyderabad consists only of raw and partially treated wastewater outside the monsoon season. It is used for irrigation through various socio-technical arrangements that are vulnerable to conflict (Keremane, 2017).
A realistic understanding of potential can only emerge from an analysis of institutional capacity to implement concrete projects (Beveridge et al., 2017) that does not consider wastewater reuse as a depoliticised technical issue and takes full account of the institutional and political context.
Karim Eid-Sabbagh and Marie-Hélène Nassif
Dr Karim Eid-Sabbagh is an independent researcher and documentary filmmaker based in Lebanon. His research focuses on political ecology, imperialism and sovereign development, water resource management, and agrarian transformation in social formations of the Global South.
Dr. Marie-Helene Nassif is a Lebanese researcher in the fields of water and irrigation governance. She is interested in multi-disciplinary and systemic approaches of water management and policy analysis. She privileges and enjoys empirical research methods and has extensive experience about the Bekaa plain agrarian and hydraulic history. She currently works as a consultant with IWMI as the national coordinator of the regional ReWater MENA project.
The views expressed here are solely those of the authors and do no represent any organization.
Al-Khatib, N.; Shoqeir, J. and Ozerol, G. 2017. Governing the reuse of treated wastewater in irrigation: the case study of Jericho, Palestine. Int. J. Global Environmental Issues, Vol. 16, Nos. 1/2/3, pp.135–148.
Allès, C. 2019. La dimension spatiale de l'État au Liban. Une analyse à partir des politiques publiques de l'eau potable et de l'assainissement (Doctoral dissertation, Université de Nantes).
Beveridge, R., Moss, T. and Naumann, M. 2017. Sociospatial understanding of water politics: Tracing the multidimensionality of water reuse. Water Alternatives, 10(1), 22-40.
Eid-Sabbagh, K.P. 2015. A political economy of water in Lebanon: water resource management, infrastructure production, and the International Development Complex (Doctoral dissertation, SOAS, University of London).
Eid-Sabbagh, K.P., Roukos, S., Nassif, M.-H., Velpuri, N. and Mateo-Sagasta, J., (Forthcoming). Analysis of Water Reuse Potential for Irrigation in Lebanon. International Water Management Institute, Colombo, Sri Lanka.
Keremane, G. 2017. Governance of urban wastewater reuse for agriculture: a framework for understanding and action in metropolitan regions. Springer.
Nassif, M-H. 2019. Analyse multi-scalaire des politiques et de la gouvernance de l'eau dans le bassin du Litani, Liban (Doctoral dissertation, Université Montpellier 3.
Riachi, R. 2013. Institutions et régulation d'une ressource naturelle dans une société fragmentée: Théorie et applications à une gestion durable de l'eau au Liban (Doctoral dissertation, Université de Grenoble).
Sadoff, C. and Jagerskog, A. 2017. Game-changing water solutions for the Middle East and North Africa. Water blogs- World Bank. https://blogs.worldbank.org/water/game-changing-water-solutions-middle-east-and-north-africa.
Tawfik, M. H., Hoogesteger, J., Elmahdi, A. and Hellegers, P. 2021. Unpacking wastewater reuse arrangements through a new framework: insights from the analysis of Egypt. Water International, 1-21.
Wastewater treatment is harmful because most experts are unfamiliar with new, existing technologies. Thanks to thermal desalination, considered a tertiary treatment but too expensive, it is possible to obtain desalinated water of very good quality. The question of costs must be taken into account. However, with Concentrating Solar Power technology, this cost is halved since there will be no phase change from the solar thermal station to the thermal desalination station.
Dear Mr. Daghari,
Thank you for addressing the question of treatment technologies and their cost. From your experience, are wastewater treatment authorities in your country (please specify) working towards this goal of adapting technologies and reducing costs? What are the constraints of doing so?
Thank you for your interest and time!
Not sure why you are saying that treatment is harmful? You cannot mean that it is more harmful than no treatment.
It is important to issue new code for water reuse. The new technologies can treat the wastewater to be used safely in unrestricted irrigation. The new code should have different grades of water treatment, each grade can be appropriate for certain type of usage. Thanks for great efforts. Prof. Kamal Ghodeif - Egypt
Dear Prof Ghodeif. Thank you for your interesting comment on the reuse standards. Can you elaborate a bit on that? Are you mentioning new standards/ code for Lebanon or Egypt?
From your experience, can the treated effluents in Egypt be used in unrestricted irrigation and why the current standards do prevent irrigating vegetables that can be eaten raw?
Also, could you provide examples on the new technologies you mention?
Thank you for your interest and time!
In as much as wastewater reuse can ameliorate the high demand for irrigation, however, much still needs to be done, especially in developing countries to convince some traditional farmers on the need to reuse treated wastewater for irrigation purposes. The social acceptance of the use of treated wastewater for irrigation is very important, because without it, the acceptance of the produce obtained from such venture may not enjoy wide patronage in some localities.
Dear Dr. Ohwo,
Would you have specific examples for this say? From my field experience in Lebanon and litterature review in MENA, many farmers practice informal reuse and even irrigate with almost raw sewage in regions where freshwater is not available or expensive to pump/buy. How would you then explain the problem of social acceptance?
From your response, you didn't say every farmer and consumers of farm produce embrace the use of wastewater for irrigation purposes. This is a confirmation of the fact that there are exceptional cases. Studies have also indicated that irrigation with treated wastewater poses some potential risks to human health through the consumption or exposure to pathogenic microorganisms, heavy metals and harmful organic chemicals. These potential risks have led to the resistance by some persons on the use of wastewater for irrigation. A good example are some localities in southern part of Nigeria.
The post by Karim Eid-Sabbagh and Marie-Helene Nassif offers important cautions for the growing enthusiasm for treating urban wastewater and using the treated result for irrigation. There is no question but that the potential is large, but so too are concerns, and they are not only about the institutional ways that make the steps for gaining permission and establishing operations. They also stem from concerns related to the quality of the treated wastewater. Israel has long experience in treating and even desalinating treated wastewater, yet is still finding problems, as indicated by a recent article that found pharmaceuticals in edible crops irrigated with well-treated wastewater. (Ben Morechay et al. 2021, Pharmaceuticals in Edible Crops: Results of a Survey, J of Hazardous Materials, vol 416, 15 August 2021).
Well before this information, researchers had identified that soils irrigated repeatedly with treated waste wastewater became friable with lower and lower productivity per unit of water applied. The immediate approach was to desalinate the treated wastewater, which resolved the problem but at significant higher cost.(Shafran et al. 2004, Effects of Surfactants Originating from Reuse of Greywater, Proceedings of the IWA biannual meeting", Marrakech, Morocco).
Use of urban wastewater for irrigation has to be adopted if the world is to feed its increasing population, but the devil is in more than the details; it is also in the quality of the water applied in the irrigation of crops, and especially edible crops.
Hello I though I'd do a quick review to stimulate some more discussion. ...
In 2010, Drechsel Pay et al published a manual covering experience in Wastewater treatment and management. This made passing reference to a concern over antibiotic resistant genes/ (ARG) organisms. But more recently Zhao Yi et (2021) have said, in the context of waster treatment, "Although wastewater treatment is shown to be a promising technology for removing ARGs, developing countries are often lack of sufficient waste-water treatment or management for animal industries, thus the wastewater may directly be discharged to surrounding waterbodies (Gros et al., 2019). Moreover, the removal of ARGs can largely depending on the treatment technology. For example, in general farms, livestock wastewater is treated in a bioreactor through a constructed wetland without a full scale waste-water treatment. In contrast, ARGs are more efficiently removed in full scale wastewater treatment plants; and the inflow volume, the type of bio-logical treatments and the hydraulic residence time are all linked to the treatment efficiency, therefore influencing on the bacteria and ARG removal (Novo & Manaia, 2010). So a review is necessary.
In 2013, Liu Wei et al reported a High Rate of New Delhi Metallo-β-Lactamase 1–Producing Bacterial Infection in China.Then the New Delhi metallo-b-lactamase-1 gene was reported in Indonesia in 2015. Also in 2015, Mills et al. reported that "Intended water quality standards for 17α-ethinylestradiol (EE2), a synthetic oestrogen in oral contraceptives, set a much needed global precedent. Ozone and activated carbon provide effective wastewater treatments, but their energy intensities and capital/operating costs are formidable barriers to adoption. In tracing the fate of antibiotic resistance genes Zhai WC et al (2016) said "The total loads of ARGs discharged through dewatered sludge plus effluent was 1.01–14.09-fold higher than that in the raw influents, suggesting the proliferation of ARGs occurred in the waste-water treatment. The proliferation of ARGs mainly occurs in biological treatment process, such as aeration tank, an-oxic tank, sequencing batch reactor (SBR), and bio-contact oxidation, facilitates the proliferation of various ARGs, implying significant replication of certain ARG subtypes may be attributable to microbial growth. Chemical oxidation seems promising to remove ARGs,..."
In 2020, Ghernaout & Elboughdiri concluded that "Techniques have to be developed for cheap and reliable: first, bacterial clones and resistance genes origin tracking; second, detection of antibiotics in water mediums; third, disinfection of water from antibiotic-resistant populations and the resistance gene pool, and elimination of antibiotics from wastewater; and fourth, prevention policies for mixing human–animal-originated and soil–water bacteria. Lira et al (2020) reported on "Metagenomic analysis of an urban resistome before and after wastewater treatment" finding that "More recently, non-clinical environments (natural and man-made ecosystems) have been proposed to play a major role in the dissemination of AR. In particular man-made environments such as wastewater treatment plants (WWTPs) have received special attention. Within these ecosystems bacterial pathogens (several of them already carrying acquired ARGs), released within stools, coexist with different types of pollutants, including antibiotics and other selectors of AR 20 . This might make these environments highly relevant for the spread of AR. In allocations in which water is not usually treated, antibiotic resistant bacteria (ARB) can easily disseminate (for example through re-used water)"
In 2021, Kim et al "evaluated the efficacy of quantitative polymerase chain reaction (qPCR) to monitor several pertinent bacterial populations in 25 different full-scale wastewater treatment bioreactors across 9 different system designs. All the bioreactors contained a substantial quantity of total bacterial biomass and denitrifying bacteria, independent of system design. In contrast, the quantities of ammonia oxidizing bacteria (AOB) and phosphate accumulating organisms (PAOs) measured by qPCR targeting the amoA gene and the 16S rRNA genes, respectively, from the Candidatus Accumulibacter lineage significantly correlated with system design". However, previously mentioned biological contaminants were not reported on.
In reporting on "Egypt’s formal wastewater reuse sector" Tawfik et al. (2021) don't appear to recognize a need for monitoring the biological contaminants identified earlier.
I can send a zipped file with the references if you wish. best regards..