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The widespread use of synthetic herbicides has resulted in herbicide-resistant weeds, disturbed ecological balance and negative effects on human health. Due to this fact, it is necessary to rely on alternative weed control strategies using natural compounds released by plants, as essential oils (EOs), since they have a short half-life as they are biodegradable, and safer than synthetic compounds, with little damage to the environment, without even contaminating ground water (Topal and Kocaçalıskan 2006). Essential oils from different species contain allelochemical compounds that possess significant phytotoxic activity. Azizi and Fuji (2006) demonstrated that Eucalyptus (family Myrtaceae) EOs showed strong inhibitory effects on germination of seeds of many crops and weeds. The aim of this work is to evaluate the phytotoxic potential of four Eucalyptus species (E. camaldulensis, E. lesouefi, E.occidentalis, E. torquata) EOs, on weed seed germination of two dicotyledons (Amaranthus retroflexus and Portulaca oleracea) and two monocotyledons (Avena fatua and Echinochloa crus-galli) which are considered among the most serious weeds for the Mediterranean crops. Fresh leaves of E. camaldulensis and E. occidentalis were collected in afforested area near Piazza Armerina, in province of Enna (Sicily, Italy) during November and December of 2017. The leaves of E. lesouefi and E. torquata were collected during March, April and May from Gabes, located in the South of Tunisia on 2015. The four EOs were extracted by steam distillation with a Clevenger apparatus according to the standard procedure described in the European Pharmacopoeia (1975), and stored at 4 °C until they were use. Weed seeds of A. retroflexus, P. oleracea, A. fatua and E. crus-galli were purchased from Herbiseed ( England) To test the phytotoxicity activity of the EOs, different concentrations were prepared: 0.125; 0.25; 0.5; 1; 2; 4 µl/ml for dicotyledons and 0.5; 1; 2; 4; 8 µl/ml for monocotyledons. The oils were loaded on the inner side of two layer of filter paper (73 g/m2) in Petri dishes (9 cm diameter), after sowing twenty seeds of each weed type (10 in case of monocotyledons) on the base of the Petri dishes, in two other layers of filter paper wetted with 5ml of distilled water, in case of the dicotyledons, and 6 ml for the monocotyledons. The controls were prepared with the same quantities of distilled water. For each concentration, five replications were maintained. All the Petri dishes were kept in a growth chamber maintained alternating 30.0 +/- 0.1 °C, 16 h in light and 20.0 +/- 0.1 °C, 8 h in dark. To register germination and seedling length data, photos were taken after 3, 5, 7, 10 and 14 days, and they will be processed with Digimizer.

The widespread use of synthetic herbicides has resulted in herbicide-resistant weeds, altered ecological balance and negative effects on human health. To overcome these problems, efforts are being made to reduce the reliance on synthetic herbicides and shift to natural products. Essential oils (EOs) extracted from plants have been demonstrated to have potential herbicide activity. EOs, composed by volatile organic compounds and characterized by a strong odor, are used in the cosmetic, pharmaceutical and food industries as they are thought to be safe compounds for humans, animals, and the environment. EOs extracted from Eucalyptus leaves have antimicrobial, antiviral, fungicidal, insecticidal, anti-inflammatory, anti-nociceptive and anti-oxidant effects. Moreover, in vitro studies have demonstrated that they have inhibitory effects on germination of seeds of many crops and weeds. The aim of this work was to evaluate the in vivo effects of EOs extracted from Eucalyptus leaves on both weed emergence and biochemical soil properties. Furthermore, since the diverse species of Eucalyptus have shown to have different biological activities, EOs were extracted from three Eucalyptus species (E. camaldulensis, E. globulus, E. occidentalis). Fresh leaves were collected from an afforested area near Piazza Armerina (province of Enna, Italy) and their EOs extracted by hydrodistillation. Soil samples were collected from the topsoil (

L'uso diffuso di erbicidi sintetici ha un impatto negativo sulla salute umana e sull’ecosistema. Per il superamento di questi problemi, si stanno valutando soluzioni alternative per ridurre l’utilizzo di erbicidi sintetici. Molti studi hanno dimostrato che gli oli essenziali (EO) estratti da alcune piante hanno un'attività erbicida. Gli EO, sono costituiti da composti organici volatili e caratterizzati da un forte odore; vengono utilizzati dalle industrie cosmetiche, farmaceutiche e alimentari in quanto sono considerati composti sicuri per l’uomo, gli animali e l'ambiente. Diversi studi hanno dimostrato che gli EO estratti dalle foglie di eucalipto hanno effetti antimicrobici, antivirali, fungicidi, insetticidi, antinfiammatori e antiossidanti. Inoltre, studi in vitro hanno comprovato che essi possono inibire la germinazione di alcune specie vegetali. Lo scopo di questo lavoro è stato quello di valutare gli effetti in vivo degli EO estratti dalle foglie di Eucalipto sul controllo post emergenza delle infestanti, sul carbonio della biomassa microbica, sulla respirazione del suolo e sui principali gruppi microbici (batteri e funghi). Gli EO utilizzati sono stati estratti tramite idrodistillazione da foglie di Eucalyptus camalsulensis, E. occidentalis ed E. globulus. Tre diverse specie di eucalipto sono state utilizzate perché, come riportato in letteratura, ciascuna di esse è caratterizzata da una diversa attività biologica. Il suolo utilizzato per la prova è stato prelevato all’interno del campus dell'Università degli Studi di Palermo. Dopo il prelievo, il suolo è stato essiccato all'aria e setacciato ad un centimetro. Successivamente, 500 grammi di suolo sono stati posti in 20 vaschette di alluminio (10 × 20 cm) ed incubati in condizioni naturali. Durante l’incubazione il suolo è stato mantenuto al 50% della sua capacità idrica di campo. Dopo l’emergenza delle piantine, ovvero alla comparsa della terza foglia (ventesimo giorno dall’inizio dell’incubazione), ciascun olio essenziale è stato applicato nebulizzandolo sulle piantine, a giorni alterni per una settimana (tre applicazioni in totale). Per ogni vaso e per ogni trattamento, sono stati applicati 5 mL di una soluzione contenente 1 L di acqua, 10 mL di olio essenziale e 1 mL di emulsionante. Nel suolo di controllo la soluzione applicata alle piantine non conteneva olio essenziale. Dopo 15 giorni dall’ultima applicazione dei trattamenti, i suoli sono stati campionati in modo totale, setacciati ed analizzati per la determinazione del carbonio della biomassa microbica (metodo fumigazione-estrazione), respirazione basale (emissione di CO2) e struttura della comunità microbica (analisi degli acidi grassi dei fosfolipidi). Inoltre, per ogni trattamento sono stati determinati alcuni parametri delle piante come peso secco e fresco totale, numero di specie e numero di piante per specie. In questo lavoro vengono riportati e discussi i principali risultati.

Fire-induced soil heating deeply affects soil organic C pools and their dynamics. The objective of this study was to investigate, in a soil covered with different forest tree species (Eucalyptus camaldulensis, E. occidentalis, Pinus halepensis, and Cupressus sempervirens), the effect of controlled heating on C pools and C mineralization dynamics. Soil samples were heated under controlled condition in laboratory (160 and 380°C) and then wetted with distilled or sea water to simulate the extinction of wildfires. Soil organic C pools react to heating in different way depending on forest tree species. Total organic C was almost halved following the heating of soils at 380°C. Soil covered with Pinus halepensis showed the greater decrease in organic C. Heating increased the amount of the labile C pool, promoted a direct emission of CO2 from soil during the combustion phase and an indirect emission by increasing the substrates readily available for microbial respiration. Sea water applied after heating has generally reduced CO2 emission.

The hydrolates result from the industrial extraction process of the essential oils through cold pressing of the citrus peels. Today, they are considered a waste to be disposed of. However, due to the presence of water soluble compounds (sugars, polyphenols, acids), hydrolates could be reused instead of being, due to the high economic burden, a problem in the disposal of the same, charged to the company.The aim of this work was to evaluate the effects of citrus hydrolate when directly applied as irrigation water on soil microbial biomass, activity and structure community. The soil used for the experiment was collected from the topsoil (0-10 cm) of a citrus orchard, air-dried and sieved at 2 mm. Then, 450 g of soil were placed in 1L plastic bottles and moistened up to 50% of the water holding capacity (WHC) by applying hydrolates and/or water. The tested hydrolates were obtained from three citrus species: Citrus Sinensis, Citrus Limon and Citrus Reticulata. The hydrolates were applied at three different doses to reach 1/3, 2/3 and 3/3 of the 50% of soil WHC. Respectively, 35, 70 and 105 mL of hydrolate were added to 450 g of air-dried soil. Distilled water was added when necessary to complement the 50% of WHC. Control soil was moistened up to 50% of its WHC with distilled water only. At the same time, 20 g of soil per each treatment were similarly incubated in 200 mL jars, sealed with rubber stopper holding silicon septa to monitor the emission of CO2. Four replicates per treatment were run. Soil samples were incubated in the dark at constant temperature (23.0 ± 0.5°C) and their humidity weekly adjusted up to 50% of WHC by adding distilled water. Microbial biomass C was determined according to the fumigation-extraction method after 1, 4, 8, 12 and 16 weeks of incubation. At the same time, soil fatty acid methyl esters were determined and used as indicators of the main microbial groups. The CO2 accumulated in the headspace of the jars was measured at days 2, 5, 7 during the first week, then weekly for the following month and finally bi-weekly until day 112. The preliminary results provided evidence that the three hydrolates, at different extent, stimulated the activity of soil microorganisms and affected soil microbial biomass and community structure.

Citrus wastewaters (CWWs) are by-products of the citrus fruit transformation process. Currently, more than 700 million of m³ of CWWs per year are produced worldwide. Until nowadays, the management of CWWs is based on a take-make-use-dispose model. Indeed, after being produced within a citrus processing industry, CWWs are subjected to treatment and then discharged into the environment. Now, the European Union is pushing towards a take-make-use-reuse management model, which suggests to provide for the minimization of residual pollutants simultaneously with their exploitation through a biorefinery concept. Indeed, the recovery of energy nutrients and other value-added products held by CWWs may promote environmental sustainability and close the nutrient cycles in line with the circular bio-economy perspective. Unfortunately, knowledge about the benefits and disadvantages of available technologies for the management and valorisation of CWWs are very fragmentary, thus not providing to the scientific community and stakeholders an appropriate approach. Moreover, available studies focus on a specific treatment/valorisation pathway of CWWs and an overall vision is still missing. This review aims to provide an integrated approach for the sustainable management of CWWs to be proposed to company managers and other stakeholders within the legislative boundaries and in line with the circular bio-economy perspective. To this aim, firstly, a concise analysis of citrus wastewater characteristics and the main current regulations on CWWs are reported and discussed. Then, the main technologies with a general comparison of their pros and cons, and alternative pathways for CWWs utilization are presented and discussed. Finally, a focus was paid to the economic feasibility of the solutions proposed to date relating to the recovery of the CWWs for the production of both value-added compounds and agricultural reuse. Based on literature analysis an integrated approach for a sustainable CWWs management is proposed. Such an approach suggests that after chemicals recovery by biorefinery, wastewaters should be directly used for crop irrigation if allowed by regulations or addressed to treatment plant. The latter way should be preferred when CWWs cannot be directly applied to soil due to lack of concomitance between CWWs production and crop needs. In such a way, treated wastewater should be reused after tertiary treatments for crop irrigation, whereas produced sludges should be undergone to dewatering treatment before being reused as organic amendment to improve soil fertility. Finally, this review invite European institutions and each Member State to promote common and specific legislations to overcome the fragmentation of the regulatory framework regarding CWWs reuse.

The current exploitation of freshwater, as well as the significant increase in sewage sludge production from wastewater treatment plants (WWTPs), represent nowadays a critical issue for the implementation of sustainable development consistent with the circular economy concept. There is an urgent need to rethink the concept of WWTPs from the conventional approach consisting in pollutant removal plants to water resource recovery facilities (WRRFs). The aim of this paper is to provide an overview of the demonstration case studies at the Marineo and Corleone WRRFs in Sicily (IT), with the final aim showing the effectiveness of the resources recovery systems, as well as the importance of plant optimization to reduce greenhouse gas (GHG) emissions from WRRFs. This study is part of the H2020 European Project “Achieving wider uptake of water-smart solutions—Wider-Uptake”, which final aim is to demonstrate the water-smart solution feasibility in the wastewater sector. The main project goal is to overcome the existing barriers that hamper the transition to circularity through the implementation of a governance analysis tool. The preliminary actions in the two demonstration cases are first presented, while, subsequently, the water-smart solutions to be implemented are thoroughly described, highlighting their roles in the transition process. The achieved preliminary results underlined the significant potential of WRRF application, a great chance to demonstrate the feasibility of innovative solutions in the wastewater sector to overcome the existing social, administrative and technical barriers.

The wastewater sector paradigm is shifting from wastewater treatment to resource recovery. In addition, concerns regarding sustainability during the operation have increased. In this sense, there is a need to break barriers (i.e., social, economic, technological, legal, etc.) for moving forward towards water resource recovery facilities and demonstration case studies can be very effective and insightful. This paper presents a new water resource recovery case study which is part of the Horizon 2020 EU Project “Achieving wider uptake of water-smart solutions—Wider Uptake”. The final aim is to demonstrate the importance of a resource recovery system based on the circular economy concept. The recovery facilities at Palermo University (Italy) are first presented. Afterwards, the resource recovery pilot plants are described. Preliminary results have underlined the great potential of the wastewater treatment plant in terms of resources recovery and the central role of the University in fostering the transition towards circular economy. The fermentation batch test highlighted a volatile fatty acids (VFAs) accumulation suitable for polyhydroxyalkanoates (PHAs) production. The results of static adsorption and desorption tests showed that the highest amount of adsorbed NH4+ was recorded for untreated and HCl-Na treated clinoptilolite.

In this study, the suitability of zeolite as a possible medium for ammonium adsorption, desorption and recovery from wastewater was investigated. Specifically, batch adsorption and desorption studies with solutions enriched in NH$_4^+$ were conducted employing zeolite to evaluate how the chemical treatment and contact time affect adsorption and desorption. Several experimental tests were carried out considering both untreated and treated zeolite. Untreated and HCl-Na treated zeolite adsorbed up to 11.8 mg NH$_4^+$ g$^{-1}$ and showed the highest efficiency in recovering NH$_4^+$ from aqueous solution. Regardless of pre-treatment, treatments with NaCl resulted in higher and faster adsorption of NH$_4^+$ than treatments with CaCl$_2$ and MgCl$_2$., 15 pages, 2 figures

Citrus fruit processing wastewaters (CWWs), being rich in organic matter, may be a valuable resource for agricultural irrigation and, possibly, for the improvement of soil organic carbon (TOC). This issue is becoming crucial for soils of arid and semiarid environments increasingly experiencing water scarcity and continuous decline of TOC towards levels insufficient to sustain crop production. However, before using CWWs in agriculture their effects on the soil living component have to be clarified. Therefore, in this study we assessed the impact of CWWs on soil chemical and biochemical properties. Under laboratory conditions, lemon, orange and tangerine wastewaters were separately added to a sandy clay soil reaching 1/3, 2/3 and 3/3 of its 50% water holding capacity. Then soils were incubated for 56 days at 22–24 °C in the dark and analyzed for total and extractable organic C, microbial biomass C and N, and the main microbial groups at days 7, 28 and 56, while microbial respiration kinetics was fitted to a first-order decay model by nine distinct daily rates measurements throughout incubation. During the first 3 days following the addition of CWWs, soil pH decreased by 2–3 units; however, afterwards the soil recovered its initial pH values. Total and extractable C pools, as well as microbial biomass C and N, were stimulated by CWWS with such a stimulation depending on CWWs type and added dose. Also microbial respiration kinetics was greatly affected by CWWs, although the effects were generally ephemeral at the lowest two doses, whereas at the highest dose still persisted up to day 56, especially in orange and lemon wastewaters. The concomitant general increase of both microbial and metabolic quotients after the addition of CWWs suggested that also under stress conditions, soil microorganisms were able to immobilize C. Both bacteria and fungi were stimulated by CWWs but the latter, at the beginning of incubation, were more favored probably due to a transient soil acidification by CWWs. In conclusion, CWWs when added to a sandy-clay soil increased total and labile C pools, stimulated soil microbial activity and biomass, i.e. improved the overall biological soil fertility, thus suggesting a possible role of CWWs in sustainable agriculture. However, soil electrical conductivity has to be monitored when CWWs are applied recurrently.