Search

Water scarcity will be one of the most challenging topics to cope with in the following years, especially in the regions most affected by climate change such as the Mediterranean basin. The implementation of water reuse practices thus appears essential to satisfy future water demands in a sustainable way, helping to reduce hydric stress in water-unbalanced regions. However, it remains as an underused practice. To change this situation, the wastewater sector needs to develop some structural changes that include not only the transformation of conventional wastewater treatment plants (WWTPs) into novel reclaimed water facilities (RWF), but also some paradigm shifts regarding social, political and legal factors. The goal of this manuscript is to provide a systemic, novel and updated vision of the wastewater treatment sector and to give some recommendations for the implementation of wastewater reuse in agriculture, with a special focus on the Italian case. Extensive data regarding water reuse technologies for the refining, disinfection and advanced oxidation of wastewater is also provided. This comprehensive analysis could help to align the objectives to be achieved from all the perspectives (technical, economic, legal and socio-political), thus helping to fill current gaps and overcome barriers that hinder water reuse development.

Reuse of treated wastewater for irrigation purposes is a measure to reduce water stress and overexploitation of freshwater resources. This study aims to investigate the environmental and economic impacts of a current conventional wastewater treatment plant (WWTP) in Peschiera Borromeo (Milan, Italy), and compare possible scenarios to enable reclaimed water reuse for agriculture. Accordingly, we propose alternative disinfection methods (i.e. enhanced UV, peracetic acid) and replace conventional activated sludge (CAS) with upflow anaerobic sludge blanket (UASB) for biological treatment and use anaerobic membrane bioreactor (AnMBR) as the tertiary treatment. Life cycle assessment (LCA) and life cycle costing (LCC) were implemented on the existing full-scale wastewater treatment line and the hypothetical scenarios. In most cases, the impact categories are primarily influenced by fertilizer application and direct emissions to water (i.e. nutrients and heavy metals). The baseline scenario appears to have the largest environmental impact, except for freshwater eutrophication, human ecotoxicity and terrestrial ecotoxicity. As expected, water depletion is the most apparent impact category between the baseline and proposed scenarios. The UASB + AnMBR scenario gives relatively higher environmental benefits than the other proposed scenarios in climate change (−28%), fossil fuel depletion (−31%), mineral resource depletion (−52%), and terrestrial ecotoxicity compared to the baseline. On the other hand, the highest impact on freshwater eutrophication is also obtained by this scenario since the effluent from the anaerobic processes is rich in nutrients. Moreover, investment and operational costs vary remarkably between the scenarios, and the highest overall costs are obtained for the UASB + AnMBR line mostly due to the replacement of membrane modules (24% of the total cost). The results highlighted the importance of the life cycle approach to support decision making when considering possible upgrading scenarios in WWTPs for water reuse.

Cables and wires are widely used in electronic equipment and power industry for transmission of both data and electricity, where the rapid development of power lines and constant update of electronic devices have resulted in an increase of waste cables. However, recycling of cables and wires is mainly focused on the recovery of metallic fraction due to their higher market value, rather than other plastics used in insulation. Polymeric materials from the scrap cables are often disposed in landfills or incinerated, which results significant risks to health and the environment due to the release of hazardous substances. Among different recycling techniques, the pyrolysis process is a promising alternative for waste recycling, where plastics are trasformed into light gases and oils which can be useful raw materials for fuels and/or chemical/polymer production. This study aimed to analyze the problems related to cable waste recycling in detail, especially to the chemical recycling of the main polymers, which is an alternative route to incineration and landfill. An extensive literature search has therefore been carried out on the pyrolysis of the main polymeric materials used in cables, such as polyethylene, cross-linked polyethylene, and polyvinyl chloride. Finally, a method was proposed to analyse different polymers from cables in a pyrolysis reactor on a laboratory scale.

Long term operation of an anaerobic membrane bioreactor (AnMBR) treating municipal wastewater was investigated in a real seawater intrusion spot in Falconara Marittima (Central Italy) on the Adriatic coastline. Changes in biological conversion and system stability were determined with respect to varying organic loading rate (OLR) and high salinity conditions. At an OLR of 1 kgCOD.m3-1d-1, biogas production was around 0.39 ± 0.2 L.d-1. The increase of the OLR to 2 kgCOD.m3-1d-1 resulted in the increase of biogas production to 2.8 ± 1.5 L.d-1 (with 33.6% ± 10.5% of CH4) with methanol addition and to 4.11 ± 3.1 L.d-1 (with 29.7% ± 11.8% of CH4) with fermented cellulosic sludge addition. COD removal by the AnMBR was 83% ± 1% when the effluent COD concentration was below 100 mg O2.L-1. The addition of the fermented sludge affected the membrane operation; significant fouling occurred after long-term filtration, where the trans-membrane pressure (TMP) reached up to 500 mbar. Citric acid solution was applied to remove scalants and the TMP reached the initial value. High saline conditions of 1500 mgCl-.L-1 adversely affected the biogas production without deteriorating the membrane operation. The treated effluent met the EU quality standards of the D.M. 185/2003 and the new European Commission Resolution for reuse in agriculture., This study was carried out within the framework of the "SMART-Plant" Innovation Action which has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 690323. This study was carried out within "Safe and Sustainable Solutions for the Integrated Use of Non-Conventional Water Resources in the Mediterranean Agricultural Sector (FIT4REUSE)" which has received funding from the Partnership on Research and Innovation in the Mediterranean Area (PRIMA) under grant agreement number 1823 (Call 2018 Section 1 Water). The authors kindly acknowledge Diego Cingolani, Gianluigi Buttiglieri and VivaServizi.

Reuse of treated wastewater for irrigation purposes is a measure to reduce water stress and overexploitation of freshwater resources. This study aims to investigate the environmental and economic impacts of a current conventional wastewater treatment plant (WWTP) in Peschiera Borromeo (Milan, Italy), and compare possible scenarios to enable reclaimed water reuse for agriculture. Accordingly, we propose alternative disinfection methods (i.e. enhanced UV, peracetic acid) and replace conventional activated sludge (CAS) with upflow anaerobic sludge blanket (UASB) for biological treatment and use anaerobic membrane bioreactor (AnMBR) as the tertiary treatment. Life cycle assessment (LCA) and life cycle costing (LCC) were implemented on the existing full-scale wastewater treatment line and the hypothetical scenarios. In most cases, the impact categories are primarily influenced by fertilizer application and direct emissions to water (i.e. nutrients and heavy metals). The baseline scenario appears to have the largest environmental impact, except for freshwater eutrophication, human ecotoxicity and terrestrial ecotoxicity. As expected, water depletion is the most apparent impact category between the baseline and proposed scenarios. The UASB+AnMBR scenario gives relatively higher environmental benefits than the other proposed scenarios in climate change (−28%), fossil fuel depletion (−31%), mineral resource depletion (−52%), and terrestrial ecotoxicity compared to the baseline. On the other hand, the highest impact on freshwater eutrophication is also obtained by this scenario since the effluent from the anaerobic processes is rich in nutrients. Moreover, investment and operational costs vary remarkably between the scenarios, and the highest overall costs are obtained for the UASB+AnMBR line mostly due to the replacement of membrane modules (24% of the total cost). The results highlighted the importance of the life cycle approach to support decision making when considering possible upgrading scenarios in WWTPs for water reuse.

The lack scale-up and long-term demonstration in real environment of eco-innovative resource recovery and reuse solutions is one of the main barriers for circular economy principles in wastewater systems management. Within this context, since 2016 the Horizon2020 SMART-Plant Innovation Action (www.smart-plant.eu) is delivering scaled-up solutions in n.6 existing wastewater treatment plants (WWTPs) with the aim to recover and recycle chemicals and nutrients in an energy- and carbon efficient way. In those Water Resource Recovery Facility (WRRFs), besides CaPO4 and struvite, more than 400 kg per week of clean cellulose fibres or cellulosic sludge (Crutchik et al., 2018), more than 1 kg polyhydroxyalkanoates (PHA) per day are to produce sludge-wood-plastic bio-composites, fertilizer and biofertilizers, biomass fuel, sludge-added mortars and cement.

Reuse of treated wastewater for irrigation purposes is a measure to reduce water stress and overexploitation of freshwater resources. This study aims to investigate the environmental and economic impacts of a current conventional wastewater treatment plant (WWTP) in Peschiera Borromeo (Milan, Italy), and compare possible scenarios to enable reclaimed water reuse for agriculture. Accordingly, we propose alternative disinfection methods (i.e. enhanced UV, peracetic acid) and replace conventional activated sludge (CAS) with upflow anaerobic sludge blanket (UASB) for biological treatment and use anaerobic membrane bioreactor (AnMBR) as the tertiary treatment. Life cycle assessment (LCA) and life cycle costing (LCC) were implemented on the existing full-scale wastewater treatment line and the hypothetical scenarios. In most cases, the impact categories are primarily influenced by fertilizer application and direct emissions to water (i.e. nutrients and heavy metals). The baseline scenario appears to have the largest environmental impact, except for freshwater eutrophication, human ecotoxicity and terrestrial ecotoxicity. As expected, water depletion is the most apparent impact category between the baseline and proposed scenarios. The UASB + AnMBR scenario gives relatively higher environmental benefits than the other proposed scenarios in climate change (−28%), fossil fuel depletion (−31%), mineral resource depletion (−52%), and terrestrial ecotoxicity compared to the baseline. On the other hand, the highest impact on freshwater eutrophication is also obtained by this scenario since the effluent from the anaerobic processes is rich in nutrients. Moreover, investment and operational costs vary remarkably between the scenarios, and the highest overall costs are obtained for the UASB + AnMBR line mostly due to the replacement of membrane modules (24% of the total cost). The results highlighted the importance of the life cycle approach to support decision making when considering possible upgrading scenarios in WWTPs for water reuse.

Long term operation of an anaerobic membrane bioreactor (AnMBR) treating municipal wastewater was investigated in a real seawater intrusion spot in Falconara Marittima (Central Italy) on the Adriatic coastline. Changes in biological conversion and system stability were determined with respect to varying organic loading rate (OLR) and high salinity conditions. At an OLR of 1 kgCOD.m3-1d-1, biogas production was around 0.39 ± 0.2 L.d-1. The increase of the OLR to 2 kgCOD.m3-1d-1 resulted in the increase of biogas production to 2.8 ± 1.5 L.d-1 (with 33.6% ± 10.5% of CH4) with methanol addition and to 4.11 ± 3.1 L.d-1 (with 29.7% ± 11.8% of CH4) with fermented cellulosic sludge addition. COD removal by the AnMBR was 83% ± 1% when the effluent COD concentration was below 100 mg O2.L-1. The addition of the fermented sludge affected the membrane operation; significant fouling occurred after long-term filtration, where the trans-membrane pressure (TMP) reached up to 500 mbar. Citric acid solution was applied to remove scalants and the TMP reached the initial value. High saline conditions of 1500 mgCl-.L-1 adversely affected the biogas production without deteriorating the membrane operation. The treated effluent met the EU quality standards of the D.M. 185/2003 and the new European Commission Resolution for reuse in agriculture.

Combined sewer overflows (CSOs) are of major environmental concern for impacted surface waterbodies. In the last decades, major storm events have become increasingly regular in some areas, and meteorological scenarios predict a further rise in their frequency. Consequently, control and treatment of CSOs with respect to best practice examples, innovative treatment solutions and management of sewer systems is an inevitable necessity. As a result, the number of publications concerning quality, quantity and type of treatments has recently increased. This review therefore aims to provide a critical overview on the effects, control and treatment of CSOs in terms of impact on the environment and public health, strict measures addressed by regulations, and the various treatment alternatives including natural and compact treatments. Drawing together the previous studies, an innovative treatment and control guideline is also proposed for the better management practices., The authors acknowledge the European Union's Horizon2020 research and innovation programme for co-funding INTCATCH innovation action under grant agreement No.689341.

This prospective study was critically assessed the EU directives, regulations and standards to reveal the barriers, pros and cons for integration of nature-based solutions within the concept of closed water loops approach developed by HYDROUSA project. The project aim to solve issues related to the water supply, the wastewater problem, the biodiversity and nutrient loss, by means of the implementation of six innovative technology solutions. In this work, proposed technologies were assessed to evaluate how their implementation is supported by the European Legislative Framework and if constrains or obstacles are detected for the replicability of the technologies. Main results of the Legislative analysis highlighted that no relevant barriers prevent the implementation of the HYDROUSA technologies in the European context and thus the replicability can be studied at further national level.

The development of innovative technologies in wastewater treatment create the concept of biorefinery in wastewater treatment plants (WWTPs), placing anaerobic processes in the highlight. Starting from the conventional anaerobic treatment processes to “closing the loop” scheme, next generation WWTPs are ready to serve for water, energy and materials mining. While bioenergy is still dominating the resource recovery, recovery of value-added materials (i.e. struvite, biopolymers, cellulose) are receiving significant attention in recent years. So, what are the state-of-the-art approaches for energy-efficient resource recovery and re-use from municipal wastewater? This paper follows a critical review on the validated technologies in operational environment available and further suggests possible market routes for the recovered materials in WWTPs. Considering the development and verification of a novel technology together with the valorisation of the obtained products, biorefinery and resource recovery approaches were gathered in this review paper from a circular economy point of view. General currently-faced barriers were briefly addressed to pave the way to a create to-the-point establishments of resource recovery facilities in the future., This study was carried out within the framework of the "SMART-Plant" Innovation Action which has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 690323.

The development of innovative technologies in wastewater treatment create the concept of biorefinery in wastewater treatment plants (WWTPs), placing anaerobic processes in the highlight. Starting from the conventional anaerobic treatment processes to “closing the loop” scheme, next generation WWTPs are ready to serve for water, energy and materials mining. While bioenergy is still dominating the resource recovery, recovery of value-added materials (i.e. struvite, biopolymers, cellulose) are receiving significant attention in recent years. So, what are the state-of-the-art approaches for energy-efficient resource recovery and re-use from municipal wastewater? This paper follows a critical review on the validated technologies in operational environment available and further suggests possible market routes for the recovered materials in WWTPs. Considering the development and verification of a novel technology together with the valorisation of the obtained products, biorefinery and resource recovery approaches were gathered in this review paper from a circular economy point of view. General currently-faced barriers were briefly addressed to pave the way to a create to-the-point establishments of resource recovery facilities in the future.

Ion exchange represents one of the most promising processes for ammonium recovery from municipal wastewater (MWW). However, most previous studies on ammonium ion exchange did not optimize the process or evaluate its robustness under real operational conditions. This experimental study aimed at (i) developing a procedure for the selection of a sorbent for selective ammonium removal/recovery from MWW, (ii) validating the procedure by applying it to several sorbents, (iii) performing a preliminary optimization and robustness assessment of ammonium removal/recovery with the selected sorbent. The application of the procedure to natural and synthetic zeolites and a cation exchange resin confirmed that batch isotherm tests need to be integrated by continuous-flow tests. The selected sorbent, a natural mixture of Chabazite and Phillipsite, resulted in high performances in terms of cation exchange capacity (33 mgN gdry resin-1), ammonium operating capacity (5.2 mgN gdry resin-1), ammonium recovery yield (78-91%) and selectivity towards ammonium. The process performances resulted stable during 7 adsorption/desorption cycles conducted with MWW treatment plant effluents in a 60-cm column. The switch to a highly saline effluent produced in a hotspot of seawater intrusion did not determine significant changes in performances. Contact time was reduced to 6 min without any decrease in performances. Potassium – well tolerated by crops – was selected as the regenerating agent, in the perspective to produce a desorbed product to be re-used as fertilizer. The study shows that Chabazite/Phillipsite has a high capacity to recover ammonium from MWW in a circular economy approach.