This paper reports on the performance of using a multistage constructed wetland (CW) to treat municipal raw wastewater and an analysis of its suitability for agricultural irrigation. The pilot plant consists of two stages of vertical flow CWs plus one stage of a horizontal CW built in 2018 with different local materials at the Gaston Berger University Campus, Saint Louis (Senegal). Each CW stage is composed of several filters with different type of media (silex, granite, or river gravel), filtering media depths, and macrophytes (Phragmites and Typha). The physicochemical and microbiological indicators were monitored over six months at each bed inlet and outlet to evaluate the efficiency and achievements of the Senegalese, European, and WHO regulations/recommendations for disposal or reuse in irrigation. This study demonstrates the viability of this new multistage CW design to treat raw municipal wastewater and produce an effluent of good quality suitable for reuse in agriculture. The removal of organic matter, suspended solids, and nutrients was very high (>95% for SS, BOD₅ and N-NH₄⁺, >90% for COD and P-PO₄³⁻), as was the reduction of microbiological indicators (fecal coliform reduction >5 log units and helminth egg removal of 100%). First, trends related to the influence of design (the type of gravel, filter depth, and type of macrophyte), operational modes, and the CW treatment efficiency were determined. The use of non-crushed gravel and Typha spp. seemed to provide better removal rates. On the contrary, no differences were found between the use of silex or granite gravel. For the studied Senegalese conditions under dry and hot climates, the preliminary results indicate that no resting periods are necessary for vertical flow CWs (VFCWs), thus resulting in a reduction in construction and operation costs. The main outcome of our study is evidence that multistage CWs can provide robust, cost-effective treatments, as well as allow for safe water reuse, which is imperative in areas with severe water scarcity and endemic microbiological waterborne diseases.

Controversy regarding the amount of water consumed or saved as a result of human activity is currently paramount in water-scarce areas. In recent decades, golf—a land and water consuming activity—has been implanted in several areas of the Mediterranean basin, where the scarcity of water resources is well-known. As a result, the use of conventional water resources for golf course irrigation is increasingly contested and its replacement by reclaimed water has become essential. This paper examines the wide range of issues involved in its use on golf courses, including hazards—due to the presence of microorganisms and pollutants—and the corresponding risks that can appear. The resulting biological, chemical and physical water quality concerns are analyzed. Legal aspects related to the use of reclaimed water are also discussed and good reuse practices are suggested, including a detailed examination of risk assessment procedures and tools through observation or chemical, physical and microbiological analysis. The HACCP system—which focuses on quality determination in water samples from relevant control points—is described in detail, as it is generally accepted as one of the most scientific ways to detect health problems on a golf course. The paper concludes that, given the increasing availability of treated and reclaimed water and the water needs of golf courses, the future development of the sport in areas without surplus water resources—such as the Mediterranean basin—will predictably depend upon the use of reclaimed water. In recent years, risk assessment or analysis has emerged as an essential tool to guarantee the application of reclaimed water at an acceptable risk level. There certainly have been considerable advances and improvements in the tools that guarantee the safe use of reclaimed water, although current methods available require simplification for their practical application. Nevertheless, protocols applied at present seem to be adequate in order to address the key issue of enhancing the development of reclaimed water use on golf courses.

Vehicle washing facilities (VWFs) consume substantial amounts of potable water and produce wastewater containing pollutants such as hydrocarbons, detergents, and pathogens, presenting significant environmental and operational challenges. This study evaluates Nature-based Solutions (NbS) for wastewater treatment and recycling at a pilot facility in Girona, Spain, aiming to reduce potable water consumption and ensure safe reuse while minimizing environmental impact. Over a two-year period, three systems—a Vertical Flow Treatment Wetland (VFTW), Horizontal Flow Treatment Wetland (HFTW), and Infiltration-Percolation (IP) filter—were tested. Thirty-two parameters, including physicochemical (e.g., turbidity, nutrients, heavy metals, detergents) and microbiological indicators (e.g., E. coli, Legionella spp.), were monitored. VFTW and IP systems were the most effective, reducing turbidity below 5 NTU, COD to under 20 mg/L, and E. coli below 10 CFU/100 mL, meeting Spanish reuse standards. The HFTW effectively removed organic matter and nutrients but faced challenges such as clogging and reduced hydraulic performance, making it less suitable for carwash wastewater. Together, these systems enabled up to 60% water reuse, with final chlorination ensuring microbial safety, particularly against Legionella, while meeting Spanish reuse standards. This study highlights the potential of NbS as sustainable, low-energy solutions for wastewater recycling and pollution control in vehicle washing facilities.

Infiltration percolation (IP) is an extensive technology to treat primary or secondary effluents of small and middle size communities before reuse or disposal to sensitive receiving bodies. Thirteen years of implementation of IP in Spain has highlighted the necessity to abide by defined design and construction rules and operation conditions in order to achieve consistently the treatment objectives and guarantee a long lasting treatment capacity. From this experience, high care should be taken of (i) the characteristics of the sand constituting the filter, (ii) the drainage conditions, (iii) the influent spreading over the infiltration surface and (iv) the risks related to recurrent overloading. Simple monitoring measures are suggested in order to improve the reliability of IP plants.

The decision on technologies used for reclaiming wastewater appears as important as a consequence of the implications on the economic, environmental and health conditions of societies. The problem arises when deciding how to deal with wastewater in small communities, because the costs of implementing and operating small, intensive wastewater treatment plants are unacceptable and can lead to financing and operation problems. Extensive treatment systems can be a good solution, where space is available. This paper presents the combination of two soft technologies (infiltration–percolation and constructed wetlands) to treat and reclaim wastewater. The obtained results show that the infiltration–percolation effluent presents a quality enough to be reused for irrigation of industrial crops, nurseries, fodder, cereals and oleaginous seeds, ornamental flower production; industrial cooling; impoundments, water bodies, and streams for recreational use in which the public's contact with the water is not permitted; and irrigation of forested areas, landscape areas and restricted access areas. Moreover, the combination of infiltration–percolation and constructed wetlands increases the list of final reclamation to the following: irrigation of pasture for milk or meat animals, crops for canning industry, crops not raw-consumed, fruit trees except by sprinkling, aquaculture; and aquifer recharge by localised percolation through the soil.