Reclamation of treated wastewater is considered a viable option for reducing the agricultural and national water deficit, especially in Mediterranean-type and arid climatic conditions. Given that Chile is a country around 40% of whose territory is classified as semi-arid and desert and 20% as Mediterranean, with serious water scarcity problems, and which uses a great deal of the resource in agricultural irrigation, the present paper offers perspectives on the current state of treated wastewater reuse and considers challenges to improving the development of water reclamation for irrigation in Chile as a case study. The methods followed included a systematic literature review to answer two important questions: (a) What is the state of reclamation of treated wastewater for irrigation in Chile? and (b) What criteria/parameters determine the feasibility of reclaiming treated wastewater for irrigation in Chile? The results showed that Chile has been affected by climate change in a short time: a megadrought has occurred over the last ten years, increasing the necessity for the country to secure alternative water sources for irrigation. The country has advanced greatly in wastewater treatment coverage, achieving almost 100% in urban areas, with technologies that can produce quality water as a new water source for irrigation. However, the lack of regulations and limited frameworks could explain the low direct reuse at present—below 1% of total flow. Regarding challenges, the necessity of updates to Chile’s institutional and legal frameworks, besides the inclusion of rural communities and the study of emerging contaminants, will be discussed. By these means, it will be possible to more efficiently utilize recycled wastewater as a new source for irrigation in this country.

This study aims to evaluate the sorption characteristics of ${\mathrm{NH}}_4^{+}$ -N and ${\mathrm{PO}}_4^{3-}$ -P onto the surface of natural zeolites coming from Chile and their potential application in the subsurface-flow treatment wetlands for wastewater treatment in rural areas. For this purpose, adsorption experiments onto the zeolite were developed in batch assays. The effects of the adsorbent quantity (20 g and 50 g) and particle size (0.2–1.0 mm; 1.5–3.0 mm, and 5.0–8.0 mm) were evaluated in terms of adsorption capacity at different NH₄⁺-N and PO₄⁻³-P concentrations. Then, the obtained laboratory results were adjusted to theoretical models: Saturation-growth-rate and Langmuir. The saturation adsorption of NH₄⁺-N on the zeolite increases at the same time that the initial concentration increases for the same zeolite quantity; however, the saturation values were similar between the different zeolite sizes tested. For PO₄⁻³-P, the adsorption did not have a direct relationship with the initial concentration nor zeolite quantity and better results were only achieved for zeolite sizes of 1.5–3.0 mm. Regarding the Langmuir model, sizes of 1.5–3.0 mm had the best adsorption characteristics, with the maximum adsorption capacity of up to 1.58 mg/g for NH₄⁺-N and up to 0.08 mg/g for PO₄⁻³-P. Therefore, a new material—a natural zeolite from the Maule Region of Chile—is described as a potential support medium for treatment wetlands.

This work compares the performance of vertical subsurface flow treatment wetlands (VSSF TWs) for wastewater treatment, planted with Zantedeschia aethiopica (Za), here operated simultaneously under two different climate conditions, arid and Mediterranean. The experimental setup was divided into two treatment lines for each climate condition: three VSSF TWs planted with Schoenplectus californicus (Sc) (VSSF-S), as the control, and three VSSF TWs planted with Zantedeschia aethiopica (Za) (VSSF-Z), as the experimental unit. The four treatment systems were operated at a hydraulic loading rate of 120 mm/d during spring and summer seasons, in two locations, Iquique (Atacama Desert, Chile) and Talca (Central Valley, Chile). The water quality in effluents, plant development, and water balance were used as performance measures. In terms of the water quality, the influents’ characteristics were similar in both climates and classified as “diluted”. For the effluents, in both climate conditions, average COD and TSS effluent concentrations were below 50 mg/L and 15 mg/L, respectively. In both climate conditions, average TN and TP effluent concentrations were below 40 mg/L and 2 mg/L, respectively. Furthermore, only total nitrogen (TN) and total phosphorus (TP) in effluents to VSSF-Z had a significant effect (p < 0.05) in relation to the climate condition. Regarding plant development, Za showed a lower height growth in both climate conditions, with arid consistently 0.3 m and Mediterranean decreasing from 0.6 m to 0.2 m. However, the physiological conditions of the leaves (measured by chlorophyll content) were not affected during operation time in both climates. Water balance showed that it was not influenced by the climate conditions or plant, with water loss differences below 5%. Therefore, taking into account the water quality and water balance results, Zantedeschia aethiopica can be used in VSSF TWs in a way similar to traditional plants under arid and Mediterranean climates. However, its use has to be carefully considered because lower height could affect the esthetics for its implementation in the VSSF TWs.

The aim of this work is to evaluate the reuse of municipal wastewaters treated through subsurface constructed wetlands (SS-CWs) as irrigation water in cut flower aeroponic cultivation under arid conditions. For this purpose, two experimental aeroponic cultivation systems were installed with the cut flower Lilium ‘Tresor’ planted and irrigated with SS-CWs treated water. The results showed that the quality of the SS-CWs wastewater has to be improved to be used in irrigation. Despite that, Lilium ‘Tresor’ grew under arid conditions with normal stem diameters and number of flowers but with heights under 0.65 m, which would restrict their commercialization to local markets. Water electrical conductivity (> 2300 µs/cm) and luminosity (> 120 klux) were factors that affected plant height. When compared to other cultivation systems, the aeroponic cultivation system used between 10 % and 20 % of the amount of water needed to produce Lilium ‘Tresor.’ Thus, this work showed the feasibility to produce cut flowers using an aeroponic cultivation system under arid conditions and irrigated with SS-CWs effluents. Likewise, it was detected that improvements to water quality and luminosity must be made for industrial scaling.

This work aimed to evaluate the performance of modified vertical flow treatment wetlands (VF-TWs) in terms of depth and medium to assess the effect of the feeding/resting periods and footprint (FP). The modifications were proposed for treating domestic wastewater in rural areas with flow variations such as tourist sites. The experimental setup included six laboratory-scale VF-TWs: (a) normal (VF-N), bed depth 1.0 m, filled with sand and (b) modified (VF-M), bed depth 0.5 m, filled with sand (upper) and zeolite (bottom, saturated). The operation was divided into three phases (3 months each), varying the feeding/resting period and FP: phase I, 5 d/10 d, 2.6 m2/person-equivalent (PE); phase II, 3.5 d/3.5 d, 1.7 m2/PE; and phase III, only feeding no resting, 0.85 m2/PE. Influent and effluent grab samples were taken every 2 weeks. The results showed effective removal (above 60%) of total solids, organic matter, and pathogens for both VF-N and VF-M. Regarding nutrients, VF-M showed a phosphate removal below 60%, but no consistent removal (15–60%) of total nitrogen. Thus, the results suggest that proposed modifications can be an option to be established in tourist sites, but further work should be conducted to improve and optimize total nitrogen removal.

This study evaluates the impact of different irrigation scenarios on the yield of quinoa (Chenopodium quinoa) in the Chilean Altiplano. The research was conducted in Ancovinto, Tarapacá, Chile, using “Pandela” quinoa seeds. Four irrigation treatments were implemented: rainfed (T0) and irrigation at 100% ETc (T1), 66% ETc (T2), and 33% ETc (T3). Various climatic variables, the soil moisture content, and agromorphological parameters were measured. The results indicated that rainfed conditions (T0) led to higher dry matter production in roots, stems, leaves, and panicles at the end of the growth cycle compared to irrigated treatments. The Leaf Area Index (LAI) was also higher in rainfed conditions during the flowering stage, demonstrating the crop’s adaptability to adverse water conditions. Additionally, the ability of quinoa plants under rainfed conditions to tolerate frost during critical growth stages was a key factor in their superior performance, contributing to a higher grain yield and harvest indices. Plants under rainfed conditions reached greater heights and showed higher harvest indices (HI) and grain yield than those under irrigation. The Water Use Efficiency (WUE) was significantly higher in rainfed conditions, suggesting more effective water utilization under water scarcity. This research represents a one-year study that provides orientations for future research, considering the interannual variability of precipitation in the region. The results obtained show that quinoa plants under traditional management (rainfed) exhibited the best response in the measured growth, development, and production variables, leading to higher production and harvest rates. Additionally, there was greater efficiency in water use, equivalent to 15.87 and 12.7 times that of the 100% and 33% ETc treatments, respectively. These findings highlight quinoa’s remarkable adaptability to harsh hydric conditions and the efficiency of traditional rainfed farming practices in the Altiplano.