Innovative and enhanced nature-based solutions for sustainable urban water cycle, URL10, Cairo, Egypt

The Ahmed Orabi Association is located along the Cairo–Ismailia Desert Road, on the left-hand side between approximately kilometer 28 and kilometer 35.5. The Association covers an estimated area of 12,000 feddans. Irrigation water is supplied primarily from the Ismailia Canal, and a separate potable water network is also available. The land is subdivided into agricultural plots, each provided with a 2-inch irrigation water outlet.

Agriculture is the dominant activity within the Association, particularly the cultivation of mango orchards. In recent years, a significant number of farmers have shifted towards livestock production. However, due to the deterioration of irrigation water quality, 

Challnges of livestock and agriculture in ORABY gardens

1. Farmers have been compelled to rely on potable water for livestock, which is nearly twenty times more expensive than irrigation water.
2. The reliance on drinking water stems from the contamination of irrigation sources, caused by the discharge of drainage water from nearby drains into the canal. 
3. This has resulted in elevated levels of pollutants and pathogenic microorganisms.
4.  Preliminary water analyses detected the presence of Escherichia coli and Salmonella, two of the most hazardous pathogens affecting both animal and human health. Consequently,
5.  farmers were forced to use high-cost potable water to safeguard their livestock.
6. The limited availability and high cost of degraded gravel sizes due to the increasing demand for their use in decorative works.
7. The high costs of drinking water comparing with fresh water.
8. The prevailing mindset of stakeholders and decision-makers often hinders the acceptance of innovative or new approaches.
9. High intial cost of constucting wetland.
10. The extensive land requirements for constructed wetlands restrict their scalability and dissemination.

This situation highlights an urgent environmental, economic, and public health risk. It underscores the need for innovative nature-based solutions capable of removing contaminants and pathogens from irrigation water, to ensure its safe and sustainable use in livestock production.

Technical aims 

1. R&D of innovative Nature based solution, NBS covering the whole urban water cycle and aiming at the improvement of their ecological state and treated water reuse: 

1.1. Selection of indigenous microorganisms from wetlands for applying bioaugmentation strategies to improve the functioning of the Nature based solution, [ NBS] at low and room temperature [T], Selection, culture and lab-scale testing of psychrophilic organic matter & N removal. 1.2. Obtain adsorber-amended and reactive-media wetlands to improve pathogens removal from Grey water, [GW], storm water, [SW] & River basin, [RB]: Selection and characterization of proper sustainable natural adsorber materials and reactive media. Test before, after and inside lab-scale constructed wetlands [CW]. Implementation in hybrid subsurface wetlands.

 1.3. Optimisation of hybrid subsurface wetlands [SSFW] to reuse wastwater [WW] (for irrigation of non-edible crops and tree plantations) in arid, Mediterranean and continental climates, as well as, for RB restoration: Study of at least five combinations of 2 and 3 stage vertical and horizontal subsurface wetlands with different innovative media such as mineral and engineered. Disinfection optimisation using low permeability media and plant able to exudate biocides and perform high oxygen transfer to the water. Optimisation of Hydraulic Retention Time [HRT] to avoid excessive infiltration an evaporation while keeping high removals Energy production through anaerobic co-digestion of harvested plants with other wastes. Nutrients recovery from [WW] through: 

1) organic bio-solids fertilizer produced by anaerobic co-digestion to be used in agriculture

 2) non-edible crops and tree plantations irrigation 

3) Innovative engineered mediaRemovals: 

>2 log E. coli, >75%, Chemical Oxygen Demand  [COD] >80% solids, >55% nitrogen [N]. Energy production & nutrient recovery:

 Biogas 0.5m3CH4/kg dry matter N,P,K recover >80% River basin RB restoration: removal of 65% SS, 50% organics, 50% total nitrogen, [TN] & total phosore [TP], in River basin [RB] 

O2.10. Urban real lab[ URL] 10: Cairo ( Egypt [EG], Mediterranean climate, arid conditions, water scarcity, Nile river overexploitation): Wast water, [WW] and River basin, RB NICE enhanced nature based solution, [NBS] solutions will be validated.  Nature based solution, NBS for Wast water, [WW] will be implemented at New Cairo Wastewater treatment plant, [WWTP]. Irrigation by pottery drippers, reducing reused water salinity, will be also tested. Environmental aims Contribute towards adaptation to climate change, restoration of the natural processes (River Basin), strengthening the resilience and reducing flood risks and heat islands effects. Economic Objectives Reach Nature based solution, NBS with lower cost with respect to the current technologies for wast water,[ WW] treatment Development of new replicable business models for construction, operation & management of urban enhanced-Nature based solution,NBS. Guidelines to boost replicability of NICE solutions.

 Social Objectives Increase participatory processes and stakeholder’s involvement, including citizens in Nature based solution, [NBS] design and implementation. Constitution of Stakeholder and Scientific Advisory Panel (SSAP), Council of Cities (CoC) and collaboration with NatureNetwork. Take into account cultural diversity in the development of  Nature based solution, NBS and engage in international cooperation. Although the primary objective of the intervention is water treatment, the solutions are designed to be nature-based and environmentally friendly. These measures also contribute to strengthening food security by supporting both agricultural and livestock production through the provision of low-cost, safe, and reusable water. Furthermore, the plant biomass generated from the constructed wetlands can be utilized for renewable energy production, particularly for generating biofuel (biogas), thereby adding an additional environmental and economic benefit to the system.

Two vertical subsurface flow constructed wetland models were designed and implemented in accordance with Danish specifications (one without plants and one planted with Phragmites australis). 

The performance evaluation of both systems yielded excellent results. Each unit has a treatment capacity of 15 m³/day, which is sufficient to irrigate one feddan per day. Solar panels were used to power water pumping throughout the wetland treatment cycle and for irrigation. The treated water was free from biological contaminants such as E. coli and Salmonella, making it safe for use in livestock and poultry production while significantly reducing the cost of water required for these activities—without posing any risk of pathogens or pollutants. The planted wetland model (with Phragmites) showed superior efficiency, in addition to the economic benefits derived from the biomass of Phragmites. This allows the wetland surface area to be used simultaneously for agriculture and bioremediation. Although the initial cost of treated water through wetlands is relatively low, operation and management costs remain extremely minimal compared to conventional wastewater treatment systems, which are energy-intensive and contribute to greenhouse gas emissions. 

The aim was to maximize the multifunctional benefits of wetland areas, using them as green landscapes that preserve the environment, reduce heat emissions, and generate economic returns depending on the plant species used—such as Phragmites, which can be utilized in medical products, paper manufacturing, or converted into biomass for biogas production. This reduces dependence on fossil fuels and enhances the Water–Energy–Food–Ecosystem (WEFE) nexus. 

To facilitate the reuse of treated water in irrigation, innovative clay-based porous emitters were utilized (representing new techniques for maximizing irrigation efficiency with treated wastewater and river water): Porous Clay Irrigation Emitters The porous irrigation emitter, manufactured from natural earthen materials, is registered under Patent Application No. (155/2019) at the Academy of Scientific Research. These emitters come in various shapes depending on the purpose of use. Their key advantages include: 

1. Self-regulating discharge rate. 
2. Automatic adaptation to soil moisture levels, especially when emitters are installed below the soil surface. 
3. Desalination and filtration of saline or wastewater to make it suitable for irrigation. 
4. Ease of installation inside drip irrigation pipes within existing irrigation networks. 
5. Energy savings, as the system requires minimal operating power. 
6. Environmental safety, being manufactured from eco-friendly earthen materials.
7.  Low cost compared to other emitters used for the same purpose.
8.  The clay material successfully reduced water salinity by approximately 4,500 ppm, 

Challnges pf pottery drippers performance 

1.  it requires periodic washing. 
2. Development of engineered ecological washing cycles is planned to regenerate the adsorption media, 

collect accumulated salts, separate them, and direct them for beneficial use in other applications. There is an urgent need to support scientific research—particularly applied research—to develop innovative, nature-based solutions capable of addressing the water crisis, conserving water and energy used in agricultural production, and maximizing the safe reuse of contaminated water through environmentally friendly biological treatment. Such approaches also help reduce greenhouse gas emissions and enhance carbon sequestration through the green surfaces of constructed wetlands. After the preliminary design of this pilot, a second stage is ongoing for its on site implementation. 

This system is composed by a hybrid constructed wetland, the design of which follows the recommendations from NICE research partners Aarhus University. Those recommendations included a specific hydraulic loading rate for the contaminant removal target. In addition to the constructed wetland itself, the system included the selection of a specific kind of vegetation (Cyperus papyrus) which is endogenous and has been scientifically proven over the last years to be highly efficient in removing a number of common contaminants that are present in waste water, especially heavy metals. The efficiency of constructed wetland with papyrus is higher than without the plant according to the papyrus root exudes, which reduce the counts of both coli and salmonella, 

where the river Nile water is microbially polluted with coli and salmonella. The stakeholders of Orabi garden depend on drinking water for poultry production, drinking water is so expensive compared with the Nile water. After wetland treatment, they are now able to use the treated water for poultry production and other identified uses. 

Key features of constructed wetland:

1. The entire system helps to remove heavy metals, cations and anions. Pottery drippers reduce the concentration of heavy metals and water salinity. 
2. An important point for the system is that the materials' local substrate were utilized.
3. mitigating the CO2 footprint of material transport.
4.  These local substrates have a low granulometry. 

The water resulting from treatment is valuable due to the arid climate in Cairo, so every drop must be saved!

 The innovative pottery drippers and back-flow valve present the ecosystem a natural automatic system to operate (On-off) pottery drippers' irrigation system, saving 50% of applied water. We think that is a very NICE and NBS solution. Main technological innovation: Use and evaluation of the contaminent removal efficiency from Cyperus papyrus specifically for cation, anion and microbial removal. Evaluating the performance of the system using a low granulometry substrate. We are demonstrating the performance of this system in a real setting, further, of a little explored typology, an off-line wetland that is treating the river water. Pottery drippers save applied irrigation water at an impressive rate of around 50% Synergies: Designed including design recommendations from Aarhus University

Key Achievements 

1. The daily treatment capacity of the constructed wetlands for the pond reached 15 m³/day, sufficient to irrigate one feddan. 
2. Complete removal of E. coli and Salmonella was achieved, rendering the water suitable for agricultural use, particularly livestock production.
3.  Solar energy was employed for water pumping throughout the wetland cycle and for irrigation, thereby reducing greenhouse gas emissions from fossil fuels and supporting the ecosystem.
4.  The overall concentration of pollutants and pathogens in the wetlands was significantly reduced. 
5. Irrigation water savings of 50% were achieved by using the innovative clay-based emitters, reducing surface runoff and deep percolation.
6.  Phragmites biomass was harvested five times per year, generating a total income of EGP 200,000, offsetting the costs of wetland construction.
7.  The land was transformed from a desert area into a green landscape, supporting biodiversity and attracting birds, amphibians, and other wildlife, creating a new natural habitat. 
8. The green wetland surface helped reduce ambient temperature and soil water evaporation, contributing to mitigation of local heat and greenhouse effects. 
9. Crops such as onions, fava beans, garlic, and sesame were successfully irrigated with treated wetland water. 
10. The wetlands strengthened the Water–Energy–Food–Ecosystem (WEFE) nexus, providing benefits across all these sectors. 
11. The impact on decision-makers was limited; more efforts are needed to promote wetlands among farmers, policymakers, and other stakeholders, given their low cost compared to industrial water treatment systems, their environmental friendliness, and their ecosystem-supporting functions.
12.  Most European countries have adopted wetlands as an investment-based natural water treatment system. Wider adoption in the rest of the world, particularly in Arab countries, is still needed.

Key Lessons Learned 

1. Conducting thorough engineering and environmental assessments of constructed wetlands is essential to reduce construction costs. Economical and environmentally friendly alternatives should be explored, such as using silica for soil stabilization and insulation instead of polyethylene liners, concrete ponds, or plastic basins—particularly for large-scale areas. 
2. Plant-based wetlands are preferred, as they allow the area to be utilized for crop production, mitigate the effects of greenhouse gases, and support environmental sustainability. 
3. It is recommended to use plants with natural water-treatment capabilities (e.g., Phragmites, Sasabana, Mambo, etc.), maximizing the economic returns of the wetlands and overcoming one of the main barriers to their adoption. 
4. Constructed wetlands can be replicated at an investment scale, with support from stakeholders such as governments, investors, researchers, farmers, and other interested parties. Notably, such systems have been successfully applied at an investment scale in the United Kingdom.
5.  Further work is needed to develop alternative designs, filtration and adsorption materials, and additional plant species to achieve the optimal constructed wetland model suited to the country’s environmental, climatic, economic, and natural conditions.