Dairy and livestock farms produce considerable amounts of wastewater, which could pose an environmental risk if not properly treated and discharged. Conventional treatment plants can represent an inadequate and costly solution in terms of operation and maintenance, especially for small and medium-sized farms. Thus, a valid and sustainable alternative can be provided by constructed wetland (CW). This paper analyzed the use of CW systems at different scales to treat dairy wastewater (DWW) and livestock wastewater (LWW) all around the world over the last thirty years. This systematic review identified 50 case studies reported in 50 publications from 22 countries: 20 CW for LWW and 30 for DWW. Per each type of WW, the analysis reported and compared the following: CW layout, type of substrates, vegetations planted, design parameters, removal efficiencies and management aspects. Gravel and sand are the most common substrates used in CW to treat both types of WW. Regarding vegetation, Phragmites australis is the most commonly used species in CWs treating LWW, whereas Typha spp. are the most frequently used in CWs treating DWW. Hybrid CW showed the highest removal performance for all parameters reported. This review can improve knowledge on CW, offering a technical and practical overview of the status of CW for treating LWW and DWW.

Groundwater is one of the major sources of water supply for human needs. But anthropic activities such as agriculture are causing significant volume depletion and quality deterioration, favoring microbial contamination that has a negative impact on human health. The geological characteristics of the ground can influence the transport of microorganisms, especially if made of permeable rock. Furthermore, irrigation with untreated or partially treated wastewater can represent an additional health risk due to the potential transmission of pathogens to food. The aim of our research is to provide an interdisciplinary perspective on this issue by integrating hygienic, geological, and agronomic skills. Water samplings are scheduled seasonally by four monitoring campaigns in five sampling points placed in two Southern Italy regions, Apulia (one point at the outlet and two wells near the wastewater plant at Carpignano Salentino, Lecce province, Italy) and Sicily (two wells at Scicli and Pozzallo, Ragusa province, Italy) Laboratory experiments of microorganism transport in permeable rocks will be carried out under saturated and unsaturated conditions. A mathematical model of transport through porous media will be implemented and validated with laboratory measurements. The model will be used to develop a monitoring tool to control sites in Apulia and Sicily where periodic cultural and molecular detection of pathogenic bacteria, viruses, and protozoa will also be taken. In addition, an analysis of the microbiological contamination of herbaceous crops due to the use of low-quality water will be conducted to assess the Quantitative Microbial Risk Assessment (QMRA). The project will provide methodological tools to evaluate anthropogenic pressures and their impact on environmental matrices. The results will allow these pressures to be modulated to minimize environmental and agri-food microbiological contamination and protect public health.

Constructed wetlands (CWs) are recognized as effective nature-based solutions for wastewater treatment. Conventional substrates used in CWs, such as sand and gravel, are associated with high ecological footprint and susceptibility to clogging. This study investigated the hydraulic and removal performance of four waste-derived substrates: volcanic ash and lapilli of Mt. Etna volcano collected through urban and road cleaning operations, recycled construction and demolition wastes and a synthetic substrate based on powdered volcanic ash and biochar. These materials were tested as innovative substrates in a lab-scale vertical-flow constructed wetland (VF-CWs) operated as tertiary treatment for 18 months. A limited reduction in porosity and saturated hydraulic conductivity was observed across all substrates, but no clogging was observed during operation. All substrates presented consistent removal of TSS, COD, TN, TP, and microbial contaminants. Demolition waste showed the highest TP removal (45.4%), which was attributed to its heterogeneous composition as well as Ca and Fe contents. The best COD removal efficiency was reached by the synthetic material (61%). All substrates reduced E. coli concentrations by up to 3 log units, and treated effluents achieve the Class B of EU Regulation 2020/741 to guarantee the safety reuse of treated wastewater in agriculture. The results reveal that the use of synthetic and waste‑derived substrates as filter media in VF‑CWs can contribute urban wastes reuse, support the circular economy, and enhance the sustainability of wastewater treatment.