Potential of constructed wetland treatment systems for agricultural wastewater reuse under the EU framework

One of the solutions for the problems regarding increasing water scarcity and pollution of water resources can be wastewater reuse. Constructed wetlands (CWs) are a sustainable and cost-effective technology for wastewater treatment. If they are able to produce effluent of a needed quality, they can be a valuable addition for wastewater reuse schemes. This review studied 39 treatment systems based on CWs, and it assessed their characteristics and performance on pollutant removal. Moreover, their potential to reach the new European Union standards for agricultural wastewater reuse was evaluated. The results showed that the combination of CWs with additional technologies (e.g. UV treatment, anaerobic reactors) can further increase their performance and provide better removal efficiencies in comparison with conventional horizontal and vertical subsurface flow CWs. Particularly, hybrid systems showed a better removal of organic matter and bacterial indicators than single-stage CWs. For most of the systems considered, the concentrations of biochemical oxygen demand and total suspended solids in treated effluent were below the limits for agricultural reuse. However, that was often not the case with Escherichia coli and therefore it is recommended to add a disinfection unit to the systems in order to achieve the levels required in the case of agricultural reuse

Constructed wetland biomass for compost production: Evaluation of effects on crops and soil

This study investigates the suitability of Phragmites australis (reed) biomass deriving from a surface flow constructed wetland (CW) to produce three compost types: reed (RC), reed mixed + potato cuttings (PC) and reed + liquid anaerobic digestate (DC), to promote both resource circularity and soil carbon sequestration. The composts were tested over 60 days on lettuce at two levels in combination or not with NH4NO3 (at the same kg N ha−1 loading), along with NH4NO3 reference (Chem) and an unamended control (Ctrl). The plant tissue dry weight and N load was determined, and the N relative efficiency (N-RAE %) was calculated. On pot soil, total and labile carbon (TOC, CL), along with the carbon management index (CMI) and δ13C were evaluated. Pot test showed that PC100 yielded the best (g pot−1) lettuce biomass (3.0) > DC100 and RC100 (2.5 and 1.6) ≈ chemical reference (3.8). A similar pattern was detected at 50% (g pot−1): PC50 (2.9) > DC50 (2.7) > RC50 (2.4). N-RAE (%) reflected this pattern: PC100 (60) > DC100 (21) > RC100 (10) and PC50 (76) > DC50 (53) > RC50 (52). Pot soil analyses showed composts well performed in TOC and CMI, in comparison to Ctrl (+42% and +13%), suggesting a positive impact on soil C amelioration. No significant differences were observed for δ13C distribution, suggesting the composts did not influence the microbic metabolism differently. These results indicated that the biomass harvested from the CWs can represent an interesting material for composting, combining carbon sequestration and nutrients recycling potential of these system, in addition to their wastewater treatment capacity

Effects of design and operational conditions on performance of constructed wetlands for agricultural pollution control - critical review

Constructed wetlands (CWs) can be considered as an efficient nature-based solution for treatment of agricultural drainage water (ADW) and consequently for the mitigation of the non-point source pollution. Aiming to provide suggestions for the construction and implementation of CWs, this paper proposes and discusses key parameters of CW design and operation. In order to verify the effect of these features, different case studies were reviewed, focusing on the performance of CWs that are treating agricultural drainage water. The findings showed that design and operational factors (e.g., the application of simple hydraulic structures and vegetation establishment) can improve the pollutant removal efficiencies by increasing hydraulic retention time. Hydraulic efficiency of CWs can also be enhanced through certain shape characteristics (e.g., adoption of a high aspect ratio, creation a long and narrow CW shape). The careful consideration of these parameters before and during CW implementation can therefore help these systems to achieve their full potential. However, further study is recommended to assess effects of some parameters (e.g., flow direction and the application of deep zones)

The Long-Term Effects of Land Use and Climate Changes on the Hydro-Morphology of the Reno River Catchment (Northern Italy)

Anthropogenic activities, and in particular land use/land cover (LULC) changes, have a considerable effect on rivers\u2019 flow rates and their morphologies. A representative example of those changes and resulting impacts on the fluvial environment is the Reno Mountain Basin (RMB), located in Northern Italy. Characterized by forest exploitation and agricultural production until World War II, today the RMB consists predominantly of meadows, forests and uncultivated land, as a result of agricultural land abandonment. This study focuses on the changes of the Reno river\u2019s morphology since the 1950s, with an objective of analyzing the factors that caused and influenced those changes. The factors considered were LULC changes, the Reno river flow rate and suspended sediment yield, and local climate data (precipitation and temperature). It was concluded that LUCL changes caused some important modifications in the riparian corridor, riverbed size, and river flow rate. A 40\u201380% reduction in the river bed area was observed, vegetation developed in the riparian buffer strips, and the river channel changed from braided to a single channel. The main causes identified are reductions in the river flow rate and suspended sediment yield ( 1236% and 1238%, respectively), while climate change did not have a significant effect

A novel smart fertigation system for irrigation with treated wastewater: Effects on nutrient recovery, crop and soil

Both southern and northern regions of Italy are experiencing reduced precipitation and increased heat waves due to climate change, negatively affecting agricultural sector. Urban wastewater could be a solution to this problem, providing a constant source for irrigation and reducing synthetic fertilizer use. This research presents a two-year field study on using tertiary treated wastewater for processing tomato crop irrigation through an innovative smart fertigation system, designed to supply the exact doses of NPK nutrients considering those already delivered to the plants via the irrigation water. With the aim of studying the effects of irrigation with treated wastewater, three water sources were compared: fresh water added with chemical fertilizer, tertiary treated wastewater added with chemical fertilizer and tertiary treated wastewater without addition of fertilizer. The proposed system was efficient and consistent with the design, it saved considerable amounts of fertilizers, handling nutrient fluctuations in wastewater. Of the three irrigation water types that have been tested, only the one that used tertiary treated wastewater alone without additional fertilizers was not capable of meeting tomato nutritional needs, despite the fact that significant macronutrient savings were achieved. No negative effects on soil or plant physiological performances were observed. Plants irrigated with wastewater showed similar growth and productivity to those irrigated with fresh water and no significant differences in fruit quality were found, highlighting the benefits of wastewater reuse for crop irrigation

SARS-CoV-2 from Urban to Rural Water Environment: Occurrence, Persistence, Fate, and Influence on Agriculture Irrigation. A Review

open5noThe novel coronavirus disease (COVID-19), originating from China, has rapidly crossed borders, infecting people worldwide. While its transmission may occur predominantly via aerosolization of virus-laden droplets, the possibility of other routes of contagion via the environment necessitates considerable scientific consideration. SARS-CoV-2 viral RNA has been detected in the feces of infected persons, and studies also have reported its occurrence in wastewater and surface water bodies. Therefore, water may be a possible route of virus outbreaks. Agricultural irrigation is the largest use of water globally, accounting for 70% of water use worldwide. Ensuring adequate water quality within irrigation practices is fundamental to prevent harm to plants and soils, maintain food safety, and protect public health. This review aims to gather information on possible SARSCoV-2 transmission routes within urban and rural water environments, looking into the detection, persistence, and fate of SARS-CoV-2. Based on published literature, the effect of current treatment technologies in wastewater treatment plants (WWTPs) on SARS-CoV-2 inactivation has also been investigated. Preliminary research efforts that concentrated on SARS-CoV-2 indicate that the risk of virus transmission from the aquatic environment may currently be non-existent, although a few studies have reported the presence of SARS-CoV RNA in soils, whereas there are still no studies on the detection of SARS-CoV-2 in crops.This study was carried out within the project “Safe and Sustainable Solutions for theIntegrated Use of Non-Conventional Water Resources in the Mediterranean Agricultural Sector (FIT4REUSE)” which has received funding from the Partnership on Research and Innovation in theMediterranean Area (PRIMA) under grant agreement No 1823 (https://fit4reuse.org/). PRIMA issupported by the European Union’s Horizon 2020 research and innovation programopenMancuso, Giuseppe; Perulli, Giulio Demetrio; Lavrnić, Stevo; Morandi, Brunella; Toscano, AttilioMancuso, Giuseppe; Perulli, Giulio Demetrio; Lavrnić, Stevo; Morandi, Brunella; Toscano, Attili

Demonstration scale treatment of drainage canal water in the Nile Delta through a combination of facultative lagoons and hybrid constructed wetlands

Abstract Drainage canal water (DCW), a mixture of Nile water, drainage water and municipal wastewater, is largely used for irrigation in the Nile Delta. Facultative lagoons (FL) and constructed wetlands (CWs) represent interesting options for DCW treatment before its agricultural re-use, but very few studies investigated their implementation in Egypt. This work aimed at developing at demonstration scale (250 m3 d−1) a FL + CW treatment train capable to turn DCW into an effluent reusable in agriculture. Three types of hybrid CWs were tested in parallel for 530 days. The combination of FL with a cascade hybrid CW, operated at a 200 L d−1 m−2 surface loading rate, led to medium-to-high removal efficiencies (suspended solids 90%, total nitrogen 84%, phosphate 80%, COD 67%, faecal coliforms 2.2 Log) and surface removal rates (COD 47.5 t y−1 ha−1, total nitrogen 10.9 t y−1 ha−1, faecal coliforms 1.5 1011 MPN y−1 ha−1). The effluent, compliant with class C of EU 2020/741 regulation, is potentially reusable to irrigate numerous Egyptian crops. The results show that the combination of FLs with cascade hybrid CWs has a great potential for the treatment of DCW and low-strength municipal wastewater, with near-zero energy consumption, null consumption of chemicals and a land requirement varying between 1.1% and 1.5% of the agricultural land irrigated with the treated DCW

Evaluation of herbaceous crops irrigated with treated wastewater for ethanol production

The competition for freshwater between agricultural, industrial, and civil uses has greatly increased in Mediterranean basin characterized by prolonged dry seasons. The aim of this study was to evaluate biomass production and the potential ethanol production of promising “no-food” herbaceous crops irrigated with low quality water at different ETc restitutions (0%, 50 and 100%). The research was carried out, in 2011 and 2012, in an open field near the full-scale constructed wetland (CW) municipal treatment plant located in the Eastern Sicily (Italy). The CW effluent has been applied in a experimental irrigation field of Vetiveria zizanoides (L.) Nash, Miscanthus x giganteus Greef et Deu. and Arundo donax (L.). Physical, chemical and microbiological analyses were carried out on wastewater samples collected at inlet and outlet of CW and pollutant removal efficiencies were calculated for each parameter. Bio-agronomical analysis on herbaceous species were made with the goal to evaluate the main parameters such as the plant dimension, the growth response and the biomass production. Biomass dry samples were processed with a three-step chemical pretreatment, hydrolysed with a mix of commercial enzymes and next fermented to obtain the yield of ethanol production. Average TSS, COD and TN removal for CW were about 74%, 67% and 68%, respectively. Although the satisfactory Escherichia coli removal, about 3.5 log unit for both beds on average, CW didn’t achieve the restrictive Italian law limits for wastewater reuse. As expected, irrigation was beneficial and the full ET replenishment increase the biomass productivity as compared to the other two treatment. The mean productivity of Vetiveria zizanoides and Myscanthus x giganteus were about 9, 26 and 38 t ha–1 and 3, 7 and 12 t ha–1 respectively in 0%, 50% and 100% ETc restitutions. Arundo donax gave higher values of dry biomass (78 t ha–1 in 100% ETc restitution in 2011 season), and potential ethanol production (about 3,744 kg ha–1). These results suggest the interest in the use of constructed wetland effluents for the irrigation of energy crops to obtain second generation ethanol, particularly in semiarid regions such as the Mediterranean area

Comparison of simple models for total nitrogen removal from agricultural runoff in FWS wetlands

Free water surface (FWS) wetlands can be used to treat agricultural runoff, thereby reducing diffuse pollution. However, as these are highly dynamic systems, their design is still challenging. Complex models tend to require detailed information for calibration, which can only be obtained when the wetland is constructed. Hence simplified models are widely used for FWS wetlands design. The limitations of these models in full-scale FWS wetlands is that these systems often cope with stochastic events with different input concentrations. In our study, we compared different simple transport and degradation models for total nitrogen under steady- and unsteady-state conditions using information collected from a tracer experiment and data from two precipitation events from a full-scale FWS wetland. The tanks-in-series model proved to be robust for simulating solute transport, and the first-order degradation model with non-zero background concentration performed best for total nitrogen concentrations. However, the optimal background concentration changed from event to event. Thus, to use the model as a design tool, it is advisable to include an upper and lower background concentration to determine a range of wetland performance under different events. Models under steady- and unsteady-state conditions with simulated data showed good performance, demonstrating their potential for wetland design

Long-Term Monitoring of a Surface Flow Constructed Wetland Treating Agricultural Drainage Water in Northern Italy

Agricultural drainage water that has seeped into tile drainage systems can cause nitrogen and phosphorus pollution of the surface water bodies. Constructed wetlands (CWs) can help mitigate the effects of agricultural non-point sources of pollution and remove different pollutants from tile drainage water. In this study, hydrological and water quality data of a Northern Italian CW that has been treating agricultural drainage water since 2000 were considered to assess its ability to mitigate nitrogen and phosphorus pollution. The effects of such long-term operation on the nutrients and heavy metals that eventually accumulate in CW plants and sediments were also analysed. Since 2003, the CW has received different inflows with different nutrient loads due to several operation modes. However, on average, the outflow load has been 50% lower than the inflow one; thus, it can be said that the system has proved itself to be a viable option for tile drainage water treatment. It was found that the concentration of nitrogen and phosphorus in the plant tissues varied, whereas the nitrogen content of the soil increased more than 2.5 times. Heavy metals were found accumulated in the plant root systems and uniformly distributed throughout a 60 cm soil profile at levels suitable for private and public green areas, according to the Italian la