Why this work matters for PRIMA-SAFE

Water scarcity is pushing Mediterranean and semi-arid regions to adopt alternative irrigation sources that reduce dependence on freshwater while keeping horticultural production stable. Within PRIMA-SAFE, safe treated wastewater reuse is not only about having enough water, but also about ensuring that agronomic performance, environmental compatibility, and safety criteria can be met in real farming contexts. This new peer-reviewed study contributes to that goal by testing whether treated wastewater (as an irrigation source and partial nutrient input) can be combined with a biological “biostimulant” strategy to improve plant performance under controlled conditions.

What the researchers tested

The authors evaluated the interactive effects of treated wastewater (TWW) irrigation and inoculation with the beneficial fungus Trichoderma harzianum on two tomato cultivars (Bobcat and Galilea) grown in a controlled greenhouse environment in Morocco. The experiment applied five irrigation mixtures ranging from 0% to 100% treated wastewater and compared plants with and without fungal inoculation, assessing a broad set of agro-morphological traits covering shoot development, leaf traits, root system responses, and yield components. Importantly, no additional fertilizers were applied during the trial, so the observed responses reflect the combined contribution of TWW (water plus nutrients) and the fungal biostimulant treatment.

Main results

Across both cultivars, increasing the proportion of treated wastewater generally improved vegetative growth and yield, and these benefits were amplified when plants were inoculated with T. harzianum. The strongest overall performance occurred with the highest wastewater level combined with inoculation, where the authors report clear increases in plant height, leaf number, root volume, and fruit production metrics. The two cultivars responded differently in how growth translated into yield: under the highest TWW plus inoculation condition, Galilea achieved higher shoot development indicators (e.g., height and leaf number), while Bobcat delivered higher yield performance through a greater number of fruits, larger average fruit weight, and a substantially higher total yield per plant. Multivariate analyses (PCA and clustering) supported the interpretation of a synergistic interaction between treated wastewater and fungal inoculation across most measured traits.

What the water quality data add to the message

The paper also provides context on the treated wastewater used, showing that it had higher electrical conductivity and sodium-related indicators than groundwater, which signals a potential salinity-management challenge, but it was also enriched in macronutrients such as potassium and calcium. The authors compare measured microbiological parameters and heavy metals against Moroccan irrigation standards and report they were below permissible limits for irrigation of food crops in their dataset, reinforcing PRIMA-SAFE’s central theme that reuse performance must be discussed alongside water quality compliance and monitoring requirements. At the same time, the authors note that nutrient inputs from TWW can contribute to fertilization but are not necessarily sufficient to fully replace conventional fertilisers, which is relevant when designing realistic reuse strategies for growers.

Why this is relevant to PRIMA-SAFE’s mission

From a PRIMA-SAFE perspective, this publication is valuable because it frames treated wastewater reuse as a combined agronomic and management strategy rather than a single-variable substitution of freshwater. The results support the idea that coupling reuse water with microbial biostimulants can enhance resource-use efficiency and productivity, potentially reducing reliance on freshwater and lowering synthetic fertilizer demand, while still emphasizing the need for consistent monitoring of key parameters such as salinity and compliance indicators over time. The study also clearly states the next steps needed for practical deployment, including field validation across seasons and zones, broader food-quality assessments, and economic evaluation to understand adoption feasibility beyond greenhouse conditions.

What this new paper is about

PRIMA-SAFE has a new open-access publication that addresses a very practical question for Mediterranean and water-scarce regions: when treated wastewater is reused for irrigation, how can we keep soils productive while reducing long-term concerns related to heavy metals and potential exposure risks? The study, published in Environments, explores an integrated “myco–phyto” concept that combines a beneficial soil fungus, Trichoderma harzianum, with faba bean (Vicia faba) cultivation under wastewater irrigation conditions, focusing on how this pairing influences soil metal behavior and overall safety assessment

The headline takeaways

The main message is that biological management at the soil–crop interface can be a meaningful part of safe reuse strategies. In the tested setup, introducing Trichoderma harzianum alongside faba bean cultivation improved soil outcomes by reducing the overall metal burden compared with comparable scenarios without fungal inoculation, reinforcing the idea that soil microbiology can act as a “buffer” in reuse contexts. A second, equally important point is that crop genetics matter: the paper compares different faba bean varieties and shows they do not behave identically in the soil–plant system, meaning variety selection can influence whether the system leans more toward soil decontamination performance or toward minimizing metal accumulation in plant tissues. This “systems view” fits PRIMA-SAFE’s goal of supporting reuse that is not only technically feasible, but demonstrably safe and context-appropriate.

Why this matters for PRIMA-SAFE

PRIMA-SAFE is about improving safety in agricultural water reuse by combining treatment options with monitoring and risk assessment, and this publication contributes a field-relevant mitigation lever that is low-cost in principle and compatible with agronomic practice. Rather than relying only on upgrading treatment trains, the work supports complementary approaches that manage risk where exposure actually happens: in the soil–plant interface. The study also frames outcomes using standard human-health risk assessment logic (including indicators used to evaluate carcinogenic and non-carcinogenic risk), which is essential because it translates measurements into the language used by regulators and stakeholders when judging whether a reuse scenario remains within an acceptable safety envelope.

As part of the research developed under the PRIMA-SAFE project, a new peer-reviewed article has been published in the high-impact journal Separation and Purification Technology (Impact Factor: 9). The paper, titled:

“Biochar-based Downflow Fixed-Bed Adsorption Systems for Water Treatment: Process Optimization, Reusability, and Techno-Economic Evaluation”,

offers fresh insight into sustainable, low-cost technologies for addressing one of today’s most pressing environmental challenges: the treatment of contaminated water.

A Practical and Scalable Approach to Water Purification

The study focuses on the use of biochar, a porous, carbon-rich material derived from biomass, as a core component in down flow fixed-bed adsorption systems—a configuration widely considered suitable for both centralized and decentralized water treatment applications.

Through a combination of experimental optimization, real-water testing, and techno-economic evaluation, the research offers compelling evidence that biochar-based systems can provide an efficient, eco-friendly, and affordable solution for removing contaminants from water supplies. This makes them particularly well-suited for resource-limited or climate-stressed regions, such as those targeted by the PRIMA-SAFE initiative in the Mediterranean.

Key Highlights from the Study

• Process Optimization: The team identified optimal operational conditions for column design and flow rate to maximize removal efficiency of sulfamethoxazole, a common pharmaceutical pollutant found in surface waters and wastewater effluents. The study demonstrated that under optimized conditions, high removal rates could be achieved, even at elevated contaminant concentrations.
• Reusability & Regeneration: A major strength of the system lies in its regeneration capability. The study showed that biochar columns could be reused through multiple adsorption-desorption cycles without significant loss of performance, reducing material consumption and waste generation over time.
• Real Water Testing: Beyond laboratory conditions, the system was successfully validated on real water samples, where it showed excellent results in reducing turbidity and removing trace pollutants. This proves the system’s relevance for practical field applications.
• Techno-Economic Assessment: A detailed evaluation of operational costs confirmed that the proposed setup offers a very low treatment cost per cubic meter, making it not only technically effective but also economically feasible for large-scale implementation.

Towards Circular, Low-Impact Water Solutions

The publication underlines PRIMA-SAFE’s commitment to developing technologies that balance scientific rigor, affordability, and environmental responsibility. In particular, this study contributes to the project’s broader goals of supporting circular economy models, where waste biomass is upcycled into functional materials—like biochar—that can close resource loops in water treatment.

It also reinforces the role of adsorption technologies as a competitive option alongside more established methods like membrane filtration or advanced oxidation, especially where energy consumption or cost presents a barrier.

Acknowledgements

This achievement would not have been possible without the collaboration of an interdisciplinary team of researchers and engineers working under the PRIMA-SAFE umbrella. Their collective expertise in environmental engineering, material science, and process optimisation continues to drive forward innovation in the field of water reuse and treatment.

Access the full publication here
Journal: Separation and Purification Technology

Stay tuned as PRIMA-SAFE continues to deliver impactful results at the intersection of science, sustainability, and practical implementation.