Dr. Eko Mahrous, PhD, a detail-oriented Agricultural Engineering Professional with 13 years of experience, assists with thesis fieldwork for irrigation automation, soil moisture sensing, and drone phenotyping. He uses SWAT hydraulic models, Arduino field controllers, and DSSAT for crop simulations. His publications on water-use efficiency are found in Agricultural Water Management. Dr. Mahrous describes modern brackish-water technology for Al Khoud and low-cost treatment technologies in practical terms, helping researchers understand water-limited farming systems.
Al Khoud’s agricultural sector must operate under severe freshwater scarcity. Inland basins and coastal aquifers have varying salt concentrations that adversely impact crop productivity. There are large quantities of brackish water, but direct use of it causes physiological stress to plants and adversely affects the soil structure and long-term productivity of the field. Therefore, low-cost treatment technologies are of high importance in such situations, as they are in harmony with the prevailing regional hydrological conditions and the available resources.
Brackish Water Treatment in the Agricultural Zones of Al Khoud
Brackish water in Al Khoud can be derived from deep aquifers, groundwater from fossil water pockets, coastal seawater intrusion, and over concentration from arid recharge zones. Its characteristic water quality and seasonal changes determine the required treatment. A water treatment system considers the hydraulic structure, water mineral and chemical balance, surface recharge cycle, and crop sensitivity.
The choice of treatment is coupled with the agro-hydrological situation of the country. Farming communities, inland of Al-Dhahiri and Al-Dakhil Iyah, rely on groundwater, on average, high in sulphates and chloride. In coastal areas, the groundwater is high in sodium, boron, and magnesium. These situations call for multi-stage treatment systems and the engineering of systems to sustain the amount of water to be treated for irrigation while managing cost on the engineering works.
Engineering Design of Brackish Water Treatment Systems
Pre-Screening and Filtration Systems
The first treatment system module in low-cost agriculture consists of a drum or gravel bed pre-filter,which is used to conduct pre-screening. These systems work on physical separation of suspended solids using a granular medium composed of different size classes of aggregates. The medium bed configuration is generally made up of several layers, which include a coarse aggregate layer at the inlet, followed by medium sand layers, and a final residual polishing layer.
The design of these filters is based on a flow model that uses the Darcy-Weisbach equation to estimate the pressure loss and considers the filter porosity and the local head loss.
Dr. Mahrous's field logs indicate that optimising bed depth improves pollutant retention and does not sacrifice flow continuity during peak irrigation cycles.
Solar-Powered Membrane Treatment Units
In Al Khoud, many low-cost systems utilise membrane modules as the backbone. The most used configurations include low-pressure reverse osmosis (LP-RO) and nanofiltration. These systems are particularly suited for Al Khoud as they can operate on DC pumps through photovoltaic arrays due to the country’s high solar irradiance.
The membrane configurations may be spiral-wound or hollow-fibre membrane cartridges, are integrated with a three-stage pump manifold. To avoid membrane fouling, flow distribution manifolds are used for uniform pressure and balanced inlet velocities.
Performance models are based on the salt rejection coefficient, hydraulic resistance, and permeate recovery. In the interior regions with high TDS levels, longer system lifetimes are expected with surface area adjustments for membrane alignment based on feed salinity.
Ion-Exchange and Adsorptive Media Columns
Farmers utilising groundwater with elevated sodium adsorption ratios utilise ion-exchange columns filled with resin beads or zeolite media. These columns exchange sodium with calcium and magnesium, which helps to mitigate soil sodicity.
Resin models are constructed with intraparticle diffusion coefficient and mass transfer rate breakthrough analytics. Dr. Mahrous’s calibration data indicate that there is column stable performance when there are controlled flow velocities to avoid the premature channelling and compaction of resin.
Constructed Wetland Bio-Systems for Rural Farms
In Al Khoud, certain designed wetlands are built for low-income rural farmers because they are inexpensive and easy to maintain. They are planted in sedimentation, channels, and subsurface flow gravel with drain collectors.
While gravel surfaces with microbial biofilms govern and metabolise organic loads, the retention time controls the purification capacity. Wetland functional modelling employs the use of plant uptake rates, evapotranspiration coefficients, and first-order decay kinetics.
These systems fit well in small-scale farming configurations because of their ability to integrate natural slopes and their low need for industrial components.
Capacitive Deionization Systems for Moderate Salinity Water
Capacitive deionisation is a method that uses electrically charged carbon to draw in salt ions. Water with a concentration of salt can be used with CDI, which is less expensive than reverse osmosis and provides the right water quality for crops in the CDI system.
It is also possible to predict the adsorption based on the area of electrodes, the voltage applied, and the concentration of salt in the solution. Because of the remote location and low salinity discharge, CDI is becoming popular in Al Khoud.
Algorithmic Tools and Optimisation Frameworks for Treatment Operations
Salinity Distribution Modelling and Predictive Analytics
At the basin level, salinity, recharge cycles, and seasonal changes in groundwater for Dr. Mahrous, the SWAT models are used to integrate the basin model outline. These models incorporate land use and cover, evapotranspiration, and infiltration to construct the salinity drift.
Predictive modelling aids in determining the timing of treatment scale adjustments by predicting when feed water reaches threshold levels that require desalination.
Flow-Control Algorithms in Solar-Driven Pump Systems
Low-pressure solar-driven pumps incorporate embedded microcontrollers that execute flow-balancing algorithms. The control logic modifies pump speeds depending on the level of solar irradiance, the height of the storage tank, and the back pressure of the membranes.
These algorithms are developed from empirical pump curve-based lookup tables. During periods of cloud cover, a flow calibration that is voltage-to-flow based reduces the amount of permeate produced.
Multi-Stage Optimisation in Treatment Chain Systems
Treatment chains that include filtration, membrane separation, and mineral rebalancing, for example, are optimised in multiple stages. These frameworks evaluate net costs against sets of operational parameters that include ionic removal efficiency, recovery rate, and disposal requirements for the reject stream.
Involved mathematical models may include a set of constrained nonlinear optimisations in which the parameters of interest are membrane surface area, inlet pressure, and flow split ratios.
These models are utilised by local farms to achieve sustainable operating cost levels and crop-safe water profiles.
Evaluating Systems for the Treatment of Brackish Water
Hydraulic Efficiency and Permeate Yield
The parameters that affect the hydraulic efficiency of a system are the pump curves, the fouling susceptibility of the membranes, and the permeability of the media. The measures of performance include permeate flow rate, recovery ratio, and specific energy consumption (SEC) of the system.
Some systems in Al Khoud that have undergone field testing have solar-coupled and pressure-managed optimised range SEC values.
Soil and Ionic Concentration Removal
From an agricultural standpoint, it is accepted that total dissolved solids (TDS) in the water and TDS specific to the ions present (e.g., sodium, boron, and chloride) that negatively affect the soil and consequently the crops are of foremost concern.
DSSAT crop modelling conducted by Dr. Mahrous shows varying yields based on different compositions of irrigation water, emphasising the need for specific, measured ion removal.
Operational Resilience
Treatment systems in Al Khoud face extreme heat, dust, and intermittent power. Evaluations in these environments include:
- thermal degradation of the seal in pumps
- membrane fouling
- solar panel degradation
- wetland system microbial die-off
These parameters guide design specifications that affect performance in extreme environments.
Practical Applications and Operational Models in Al Khoud
Horticulture near the Coast
Solar-powered LP-RO units in the coastal farms of the Batinah convert saline groundwater to irrigation water for crops such as tomatoes, cucumbers, and leafy greens. While recovery ratios are low due to the salinity of the feed water, simulations of the crops indicate that the stability of the yield of the crops was enhanced.
Date Palm Cultivation in the Desert
In the interior regions, the adoption of ion-exchange and partial desalination for the management of moderately saline aquifers is underway. Dr. Mahrous’s field evaluations indicate that resin columns and gravel filtration are successful at stabilising sodium levels, thus protecting date palm root zones from sonication.
Rural Mixed Crop Farming and Constructed Wetlands
In remote, off-grid farms, the use of constructed wetlands for the treatment of water before use on fodder crops is beneficial. These systems are compatible with gravity systems and require little operational management.
