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In the present research, insights about the mechanisms of excess sludge minimization occurring in an oxic-settling-anaerobic (OSA) were provided. The investigation involved two systems operating in parallel. In particular, a conventional activated sludge (CAS) system as control and a system implementing the OSA process both having a pre-denitrification scheme were considered. Five periods (P1-P5) were studied, during which several operating conditions and configurations were tested. Specifically, the hydraulic retention time (HRT) in the anaerobic reactor of the OSA system (P1 8 h, P2-P3 12 h, P4 8 h, P5 12 h) and the return sludge from the anaerobic to the anoxic (scheme A) (P1-P2) or aerobic (scheme B) mainstream reactors (P3-P5) were investi-gated. The results highlighted that the excess sludge production in the OSA was lower in all the configurations (12-41%). In more detail, the observed yield (Yobs) was reduced from 0.50-0.89 gTSS gCOD-1 (control) to 0.22-0.34 gTSS gCOD-1 in the OSA process. The highest excess sludge reduction (40%) was achieved when the OSA was operated according to scheme B and HRT of 12 h in the anaerobic reactor (P3). Generally, scheme A enabled the establishment of cell lysis and extracellular polymeric substances (EPS) destructuration, leading to a wors-ening of process performances when high anaerobic HRT (>8 h) was imposed. In contrast, scheme B enabled the establishment of maintenance metabolism in addition to the uncoupling metabolism, while cell lysis and EPS destruction were minimized. This allowed obtaining higher sludge reduction yield without compromising the effluent quality

Negli ultimi anni, a causa dell’incremento dei costi di smaltimento dei fanghi prodotti nel corso dei processi depurativi basati su metodi biologici, si va diffondendo sempre più la tendenza e la necessità di ridurne la produzione direttamente alla fonte, ovvero nel corso dello stesso processo che li genera. Diversi metodi sono proposti in letteratura e molti di essi sono già coperti da brevetto (OSA®, Cannibal®, Biminnex®), applicati ai processi biologici a fanghi attivi convenzionali (CAS). Il limite di questi processi è che una riduzione molto spinta della produzione di fango di supero, ottenuta sottoponendo la biomassa a stress biologico, comporta significativi peggioramenti della qualità dell’effluente, compromettendo, di fatto, l’efficacia del processo depurativo. Parallelamente alla problematica dei fanghi di depurazione, oggi gli impianti di trattamento delle acque reflue sono chiamati a rispettare standard di qualità, per quanto concerne l’effluente depurato, sempre più stringenti, tali da richiedere l’implementazione di processi avanzati e di ottimizzare le performance di processo. L’oggetto del brevetto è uno schema di un impianto per la rimozione biologica dei nutrienti (carbonio, azoto e fosforo) dalle acque reflue, da applicare in sistemi di trattamento biologico avanzato con filtrazione su membrana, del tipo MBR (BioReattori a Membrana – Membrane BioReactor). Esso consente di minimizzare la produzione di fango di supero e di ottimizzare, contemporaneamente, sia le performance depurative del processo biologico che quelle idrauliche di filtrazione della membrana. Il brevetto consiste nell’inserimento di un reattore anaerobico all’interno di uno schema di processo di pre-denitrificazione, tra il reattore anossico e quello aerobico, nella linea di flusso principale del sistema (mainstream). Il reattore anaerobico, avente un tempo di detenzione idraulica di 8 ore, riferito alla portata di alimentazione, opera in parallelo rispetto alla preesistente linea di processo e riceve un flusso influente, pari al 100% della portata alimentata all’impianto, proveniente dal reattore anossico. Dal reattore anaerobico, la miscela liquame-fango procede verso il reattore aerobico, nel quale la membrana opera la separazione solido (fanghi) – liquido (permeato). Il fango viene quindi ricircolato in testa al reattore anossico, mentre il permeato viene allontanato come effluente depurato del sistema. Dal punto di vista del processo, lo stress metabolico nel reattore anaerobico, imposto dalle condizioni di anaerobiosi e carenza di substrato organico (condizioni endogene), quest’ultimo in gran parte rimosso nel reattore di monte (anossico) per il processo di denitrificazione, favorisce il fenomeno della lisi cellulare. Da questo processo si genera un substrato organico secondario (substrato endogeno), costituito dalle cellule batteriche stesse e dal contenuto intracellulare, che viene utilizzato dai batteri stessi come fonte di nutrimento (fenomeno della crescita criptica). In condizioni anaerobiche, questo substrato viene utilizzato da specifici ceppi batterici (batteri fosforo-accumulanti, Phopshorous Accumulating Organisms, PAO) per poter operare la rimozione biologica del fosforo. Il processo consente, quindi, di poter ottenere simultaneamente la rimozione biologica del fosforo, con fonti di carbonio endogeno, con rendimenti di rimozione superiori al 95%, e la riduzione della produzione di fango di supero del 65% operando a temperatura ambiente. Inoltre, la lunga permanenza del fango in condizioni anaerobiche ed endogene, spinge la biomassa ad una più efficace degradazione della sostanza organica derivante dalla lisi cellulare (proteine, carboidrati), che riduce in maniera sensibile lo sporcamento della membrana (fouling) (>200%), diminuendo la frequenza di lavaggi fisici e chimici e preservandone la vita utile. Il brevetto proposto può trovare applicazione in tutti gli impianti per il trattamento di reflui municipali del tipo MBR che operano la rimozione biologica dell’azoto, nell’ottica di interventi di adeguamento alle normative ambientali per la rimozione del fosforo e di riduzione dei costi di gestione legati allo smaltimento dei fanghi e di manutenzione delle membrane.

The present study reports the results on the comparison between the oxygen transfer efficiency in a conventional activated sludge (CAS) and membrane bioreactor (MBR) system. The oxygen transfer was evaluated by means of the oxygen transfer coefficient (kLa)20 and α-factor calculation, under different operating conditions and with different activated sludge features, including total suspended solids (TSS) concentration, extracellular polymeric substances (EPS) content and composition, sludge viscosity and size of the flocs. The (kLa)20 and α-factor showed an exponential decreasing trends with TSS in the CAS and MBR, even if it was noted that the (kLa)20 dependence on TSS was stronger in the CAS than the MBR. Under the typical operating TSS concentration for CAS (3 gTSS L-1) and MBR (8 gTSS L-1), the obtained results indicated that oxygen transfer coefficient was lower in the MBR (3.6 h-1 vs 20 h-1). Nevertheless, it was noted that the (kLa)20 in the CAS become comparable to that in MBR when the TSS concentration in the CAS was higher than 5 gTSS L-1, which is typical of plants operating under extended aeration. Within a range of TSS between 4 gTSS L-1 and 6 gTSS L-1 the (kLa)20 value resulted significantly higher in the MBR, thereby suggesting that under similar operating conditions the features of the activated sludge flocs in the MBR were more favorable to oxygen diffusion. Operating under high C/N, as a result of nutrients unbalance, the (kLa)20 increased in both the CAS and MBR because of the sludge deflocculation and, overall, a weaker dependence of (kLa)20 with TSS in both the systems was noted. The obtained results indicated that the most important investigated parameters on the oxygen transfer efficiency were in order: the TSS concentration, flocs size, sludge viscosity, PN/PS and EPS content. More precisely, the TSS, the EPS, the viscosity and the flocs size had a negative influence, meaning that an increase in these parameter led to a decrease of the (kLa)20, whereas the only parameter having a positive influence was the PN/PS. The TSS concentration had a greater influence on (kLa)20 in the CAS than the MBR, as well as the EPS. In contrast, the activated sludge viscosity, the flocs size and the PN/PS had a greater influence in the MBR. Based on the influence of the main biomass features affecting the (kLa)20 and considering the typical operating conditions in both systems, those of the MBR appeared to be more favorable to oxygen transfer efficiency compared to CAS.

The aim of this work was to investigate the effects of moderate and drastic long-termincrease of salinity.Particularly, the study was aimed at assessing the shock effecton nitritationand denitritation kineticsof halophilic biomass inboth forms:flocculent activated sludge and granular sludge.

Introduction. A wastewater-based epidemiology approach was performed to estimate the drug consumption in Palermo city, the fifth largest city of Italy with a population of 671 696 inhabitants, and to investigate the monthly variability of drug loads in wastewater from different areas of the city. A seven-months detection campaign was conducted at the two wastewater treatment plants of the city. Methods. Following a pre-treatment, 32 samples of wastewater were analyzed by liquid chromatography-tandem mass spectrometry. Results. We estimated a mean cocaine use in Palermo of 0.19 g/day/1000 people, corresponding to 1.90 doses/1000 people and cannabinoids use of 2.85 g/day/1000 people, corresponding to 35.62 doses/1000 people. Amphetamines residues in wastewater were always recovered in concentrations lower than the limit of quantification. Conclusion. Our findings showed that drugs consumption in Palermo is in line with those of other Italian cities and that no significant differences on prevalence on cocaine and cannabinoids consumption were recorded in the different months of the survey, except for the summer period in a wastewater treatment plant of the city.

La problematica dell’inquinamento prodotta dai microinquinanti, cioè da sostanze presenti in tracce nei corpi ricettori, ma aventi caratteristiche tali da comportare possibili danni per l’ambiente e per l’uomo, ha assunto un’importanza sempre crescente nell’ultimo ventennio. Infatti essa è ormai oggetto di diversi interventi normativi a livello comunitario e nazionale, che hanno individuato un elenco di sostanze definire “prioritarie” e “pericolose prioritarie”, di cui sono state fissate le concentrazioni massime per i corpi ricettori al fine di garantire voluti livelli di qualità ambientale; a queste si aggiunge un elenco molto numeroso di “contaminanti emergenti”, non ancora oggetto di normazione e le cui caratteristiche spesso non sono del tutto note, ma di cui si sospettano effetti tossici o persino cancerogeni per l’ambiente e l’uomo. In ogni caso, tali sostanze sono largamente usate nell’ambito di attività domestiche e/o produttive, risultando persino di uso comune per scopo terapeutico, per l’igiene personale, etc. La loro frequente scarsa o nulla biodegradabilità li rende persistenti nell’ambiente e tali da comportare effetti di accumulo o di bioaccumulo. Esse possono raggiungere i corpi idrici ricettori in forma concentrata, attraverso i sistemi fognari e gli emissari degli impianti di depurazione, o diffusa, per dilavamento dei suoli coltivati e non. In particolare, numerosi studi hanno evidenziato il contributo dato dagli effluenti degli impianti di depurazione in termini di concentrazioni e carichi di tali inquinanti sversati nell’ambiente; ciò a causa della frequente modesta capacità di rimozione che gli impianti hanno nei confronti dei microinquinanti, in quanto concepiti e progettati per la rimozione di macroinquinanti organici. Nella nota, dopo un inquadramento normativo della problematica dei microinquinanti, sono riportate le principali categorie di essi, su cui la ricerca scientifica sta rivolgendo l’attenzione. Sono quindi riportati i risultati di alcune ricerche di campo specificatamente condotte con riferimento a particolari categorie di inquinanti e di alcuni studi mirati alla messa a punto di modelli matematici di simulazione del destino e trasporto di essi all’interno di sistemi fognari, impianti di depurazione e corpi idrici.

In order to prevent hydrocarbon discharge at sea from ships, the International Maritime Organization (IMO) enacted the MARPOL 73/78 convention in which any oil and oil residue discharged in wastewater streams must contain less than 5 ppm hydrocarbons. Effective treatment of this petroleum-contaminated water is essential prior to its release into the environment, in order to prevent pollution problem for marine ecosystems as well as for human health. The present paper reports the first results of a field gathering campaign aimed at gaining insight about the treatment of real shipboard slops with a MBR pilot plant, in terms of pilot performance and biomass biokinetic activity. The achieved results highlighted a very high removal of total organic carbon, with biological removal efficiencies (evaluated inside the bioreactor) almost equal to the total removal efficiency (after the membrane filtration), thus suggesting a satisfactory level of biomass activity, also confirmed by the respirometric batch tests.

The paper presents the sensitivity analysis of an integrated urban water quality system by means of the global sensitivity analysis (GSA). Specifically, an home-made integrated model developed in previous studies has been modified in order to include the micropollutant assessment (namely, sulfamethoxazole - SMX). The model takes into account also the interactions between the three components of the system: sewer system (SS), wastewater treatment plant (WWTP) and the receiving water body (RWB). The analysis has been applied to an experimental catchment nearby Palermo (Italy): the Nocella catchment. Five scenarios each characterized by different combinations of sub-systems (i.e., SS, WWTP and RWB) have been considered applying the Extended-FAST method in order to select the key factors affecting the RWB quality and to design a reliable/useful experimental campaign. Results demonstrated that GSA is a powerful tool for increasing operator confidence in the modelling results; the approach can be used for blocking some non-identifiable parameters thus wisely modifying the structure of the model and reducing the related uncertainty. The model factors related to the SS have been found to be the most relevant factors affecting the SMX modeling

Sanitary landfills for municipal solid wastes can be considered as large biological reactors where the organic fraction of municipal solid waste undergoes anaerobic digestion producing gas and liquid emissions. Leachate production from municipal sanitary landfills is currently recognized as a major environmental burden associated with municipal solid waste management and it may be responsible for local pollution of groundwater and soil. Moreover, the fate of the organic compounds within the landfill body is of primary importance since it directly influences the production of landfill gas. The aim of the paper is to propose an integrated mathematical model able to simulate, on one hand, the vertical leachate fluxes throughout a municipal solid waste landfill (considering the fate of both inorganic and organic contaminants within the landfill leachate pathway), while, on the other hand, the production of landfill gas by means of two different approaches. In detail, the mathematical model was based on mass balance equations and was composed by two sub-models: one for the simulation of moisture distribution, whilst the other one for the simulation of the organic/inorganic contaminant concentrations. The simulation of landfill gas production was based on two different approaches. The integrated model has been applied to a real landfill considered as a case study, the landfill of Pescantina (Italy), with the landfill body divided into N horizontal layers. The results confirmed that the proposed integrated model can be a useful tool for the landfill operator in order to analyze the physical, chemical and biological phenomena occurring within the landfill body.

The United Nations Environment Program defines as waste all the persistent marine debris deposited or abandoned in the sea (marine litter) and beach (beach litter) environment. Thus including all substances or products abandoned or involuntarily dispersed into the sea or on the coastline. It has been estimated that, all around the world, about 10 million tons of waste coming from domestic, commercial and industrial activities reach the seas every year. Moreover, waste floating adrift in the seas and oceans can be carried very far away, reaching different places from the ones they were originated. Further, damage may result to various human activities and equipment, such as navigation, energy production, aquaculture, tourism. In order to identify interventions aimed at reducing the effects of waste inside the sea, an accurate waste characterization both in terms of quantity and quality (composition) is required. The paper reports the results of a study that aimed at characterize the beach litter in the coast of Cadiz, a city in the south-western of Spain. A multivariate cluster analysis was performed to group observed items in dendrograms - obtained on the basis of the frequency on which each type of litter items was found on the beaches in different periods of the year. Results obtained in this study could be adopted as a support to optimize the solid waste collection services and to identify their appropriate fate (recovery and/or disposal). Furthermore, the prevention of waste production, by means of a better organization of the involved activities, can also be obtained.

INTRODUZIONE Le istituzioni europee e la comunità scientifica hanno, recentemente, definito un nuovo modello di sorveglianza attiva della potenziale diffusione delle droghe nella collettività, la Wastewater Based Epidemiology (WBE), attraverso la ricerca analitica delle molecole e dei loro metaboliti nelle acque reflue cittadine. Lo scopo di questo lavoro è stato la valutazione di una preliminare applicazione di METODIca WBE nella città di Palermo, poco studiata in precedenti analisi a livello nazionale e internazionale. METODI Sono stati prelevati 28 campioni (2 litri cad) di refluo medio delle 24 ore in ingresso ai due depuratori di Palermo (WP1=45.000 ab. eq.; WP2=330.000 ab. eq.) in un periodo compreso tra giugno e novembre 2015. I campioni sono stati prefiltrati, concentrati ed infine analizzati (200 mml) mediante tecnica di spettrometria di massa LC-MS/MS. Gli analiti ricercati sono stati Cocaina, Benzoilecgonina (BEG), THC-COOH e Amfetamine (MDA, MDE, MDMA, Metamfetamine). È stato effettuato, inoltre, il calcolo della quantità di sostanza stupefacente consumata nella popolazione (gr/die/1.000 abitanti e dosi/die/1.000 abitanti). RISULTATI I RISULTATI ottenuti sono illustrati nella tabella 1. I consumi di sostanze stupefacenti registrati nella città di Palermo (gr/die/1000 ab) sono RISULTATI i seguenti = Cocaina=0,145 (1,45 dosi/1000 ab); THC=4,37 (35,00 dosi/1000 ab), Amfetamine=Non quantificabili. CONCLUSIONI L’applicazione della metodologia WBE può essere considerata uno strumento aggiuntivo ai classici indicatori indiretti del consumo di droghe nella collettività a disposizione delle istituzioni per comprendere meglio il fenomeno delle tossicodipendenze e per attuare azioni di contrasto e politiche di educazione sanitaria più efficaci finalizzate alla prevenzione.

A mathematical model to quantify the nitrogen removal for a membrane bioreactor (MBR) has been presented in this study. The model has been applied to a pilot plant having a pre-denitrification MBR scheme. The pilot plant was cyclically filled with real saline wastewater according to the fill-draw-batch operation. The model was calibrated by adopting a specific protocol based on extensive field dataset. The Standardized Regression Coefficient (SRC) method was adopted to select the most influential model factors to be calibrated. Results related to the SRC method have shown that model factors of the efficiency of backwashing and the biological factors affecting the soluble microbial products (utilization-associated products) (namely, fUAP and KH,UAP) strongly affects the membrane resistance. In terms of model calibration excellent results in terms of model efficiency were found for the total membrane resistance model output (efficiency equal to 0.79). Regarding the biological model outputs acceptable were found in the case an high number of measured data was available. In terms of uncertainty, it was found that for the great part of the analyzed model outputs the measured data lay inside the uncertainty bands.

Tra le varie possibilità di intervento per la rimozione dei nitrati dalle acque di falda, notevole interesse suscita il trattamento in situ dei plume contaminati mediante la realizzazione di biotrincee denitrificanti scavate in situ e naturalmente attraversate dalle acque di falda. Tra i materiali di origine organica che sono stati testati per tali applicazioni, il nocciolino di olive è risultato uno dei più idonei alle potenziali applicazioni di pieno campo. Tale tipo di materiale possiede un elevato contenuto di carbonio organico totale, prossimo al 50%, e una percentuale di lignina prossima al 45% in peso. Il lavoro proposto riporta i risultati di una campagna sperimentale eseguita mediante impianto a scala di laboratorio alimentato in continuo con una soluzione artificialmente contaminata da nitrati (fino a 35 mgNO3-L-1). I rendimenti di denitrificazione ottenuti sono stati elevati (fino al 99%), a fronte di tempi di detenzione idraulica relativamente bassi. Durante l’attività sperimentale è stata monitorata anche la produzione di protossido di azoto, ai fini di valutare il contributo di tali sistemi di trattamento all’emissione di gas climalteranti. In-situ treatment of nitrates contaminated plumes by means of biotrench, filled with materials able to promote the biological denitrification, is nowadays considered as an affordable alternative among the possible applicable technologies. Previous studies highlighted that olive nut, due to its high content of organic carbon as well as of lignin, resulted capable to promote significant removal efficiency. The paper reports the results of an experimental lab scale study carried out with a column filled with a blend of olive nut, sand and soil and feed in continuous with water artificially spiked with nitrates concentration up to 35 mgNO3-N L-1. Despite the low hydraulic retention time the denitrification efficiency resulted very high (up to 99%). Furthermore, the nitrous oxide production was investigated during the experimentation in order to assess the contribution of a such technology to the production of greenhouse gas.

La corretta gestione delle discariche controllate, destinate allo smaltimento dei rifiuti urbani, in fase operativa e post‐operativa, richiede il controllo dei potenziali impatti che esse possono determinare nei vari comparti ambientali interessati. Fra questi, la produzione di biogas derivante dai processi metabolici di trasformazione della frazione organica dei rifiuti, richiede, da un lato, la realizzazione di efficaci sistemi di estrazione, mediante i quali è pure possibile produrre energia termica e/o elettrica, dall’altro, il controllo delle emissioni diffuse in atmosfera, che contribuiscono al peggioramento delle caratteristiche dell’aria ambiente circostante il sito della discarica, oltre che all’aumento dei gas climalteranti. Inoltre, la misura di tali emissioni consente di eseguire un corretto bilancio del biogas prodotto in discarica e di ottimizzare la quantità recuperata in forma convogliata. Differenti modalità possono essere adottate per la stima delle emissioni diffuse; in particolare, quelle dirette con camera di flusso si presentano di particolare interesse, sia per la rapidità e semplicità di esecuzione, sia per il livello di precisione della misura, che consente di evidenziare anche la presenza di eventuali fughe attraverso la copertura superficiale della discarica. Nella nota, dopo una presentazione dei metodi utilizzabili per la valutazione, diretta e indiretta del biogas prodotto in discariche finalizzate allo smaltimento di rifiuti urbani, vengono presentati i principali risultati di alcune ricerche mirate alla stima diretta delle emissioni diffuse con camera di flusso statica e alle possibili correlazioni tra queste e le misure indirette eseguite con tecniche di telerilevamento

• Monitoraggio di droghe in quattro impianti di depurazione siciliani e in un corpo idrico ricettore. • Elevata presenza nei reflui influenti a tutti gli impianti monitorati di THC-COOH e BEG, metaboliti rispettivamente della cannabis e della cocaina. • Fenomeni di degradazione naturale ad opera del biota e/o di accumulo nei sedimenti del corpo idrico ricettore comportano la riduzione delle concentrazione di THC-COOH.

Municipal solid waste management significantly contributes to the emission in the atmosphere of greenhouse gases (e.g. CO2, CH4, N2O) and therefore the management process from collection to treatment and disposal has to be optimized in order to reduce these emissions. Many literature models developed for the evaluation of greenhouses gases emissions from the waste management system are based on the analysis of the life cycle. These models are not optimized for evaluation of emissions. The aim of this study is to overcome these limitations by proposing a mathematical model to estimate greenhouse gas emissions resulting from the integrated waste management. The model is aimed to be a verification tool for assessing the optimum system management in terms of greenhouse gas emissions. The model quantify the emissions associated with: heat treatment, landfill disposal, anaerobic digestion plants, recycling, composting. Different combinations of collection scenarios and disposal options have been considered in the Municipal Solid Waste management of the Province of Palermo. The obtained results applying the model show that limits to solid waste management must be clearly defined. In fact changing the limits, the emissions vary. The lower emissions are due to the use of different energy sources.

MSW sanitary landfills represent nowadays one of the most important issue related to the waste management cycle. In particular, knowledge about biogas production is a key aspect for a proper exploitation of this energy source, even in the after-care phase. In the present study, a simple mathematical model was proposed for the simulation of biogas production. The model is based on 1st order biodegradation kinetic and takes also into account the temperature variation in time and depth and the landfill settlement. The model was applied to a real landfill located in Sicily (ITALY) and its simulation result was compared with experimental data (volumes of biogas collected by the recovery system and diffuse emissions directly measured by authors). The obtained result showed a good fitting between simulation results and methane production evaluated with experimental data, suggesting that the model can be the proposed model can be applied for reliable estimates of landfill gas production, thus representing a useful tool for landfill operators also for a reliable estimate of the after-care phase duration.

La denitrificazione biologica come trattamento in situ delle falde contaminate ha riscosso grande interesse negli ultimi decenni; coniuga l’efficacia di rimozione ai costi relativamente contenuti se , confrontati con altre metodiche di intervento. La resa di tale tecnologia di trattamento è fortemente condizionata dalla scelta del materiale reattivo che fornisce il carbonio organico necessario a sostenere il processo. Diversi studi hanno evidenziato la possibilità di operare la denitrificazione biologica a partire da substrati di natura legnosa (segatura, corteccia, etc.). In tale ottica, la nota presenta i risultati preliminari ottenuti utilizzando come substrato il nocciolino di olive triturato. Lo studio ha avuto l'obiettivo di valutare sia la capacità di rilascio di carbonio organico, che le prestazioni del processo di denitrificazione biologica. I test di rilascio hanno evidenziato un lento rilascio di carbonio organico (misurato come TOC); invece nei test di microcosmo è stata valutata la performance del processo biologico condotto da biomassa eterotrofa inoculata con terreno agrario, con rendimenti così raggiunti di circa il 90% .

L’uso massiccio di fertilizzanti contenenti azoto è causa dei fenomeni di inquinamento diffuso delle acque di falda. In tale ottica, notevole interesse hanno recentemente riscosso i trattamenti biologici in situ, in grado di promuovere la denitrificazione delle acque di falda mediante la realizzazione di interventi che coniugano efficacia di rimozione e costi relativamente contenuti. Nella nota si riportano i risultati di una ricerca sul processo di denitrificazione eterotrofa, condotta utilizzando come fonte di carbonio tre materiali convenzionalmente considerati di scarto: corteccia di pino, sughero e sansa di olive. Lo studio è stato suddiviso in due fasi: la prima condotta in modalità batch, che ha consentito di valutare le caratteristiche dei substrati utilizzati e l’effettiva capacità di biodegradazione; la seconda condotta su impianti lab-scale in colonna, funzionanti in continuo, che ha consentito di verificare l’effettiva resa degli interventi proposti. Sono state comparate le differenti capacità di rilascio di carbonio organico e le efficienze di denitrificazione conseguibili coi materiali utilizzati. I risultati ottenuti hanno mostrato buoni rendimenti di rimozione, evidenziando sostanziali differenze delle cinetiche di processo tra i vari substrati; in particolare, è risultato che la sansa di olive è il materiale che garantisce le migliori performance di denitrificazione. The intensive use of nitrogen based fertilizers represents the main cause of diffused pollution in groundwater. For this reason, in situ biological groundwater denitrification, coupling good removal efficiency and low operational cost, have obtained up to nowadays an increasing interest from researchers communities. The paper reports the results of a lab-scale investigation, concerning the heterotrophic biological denitrification, sustained by three different carbon source: pine bark, cork and olive pomace. The experimentation has been divided into two phases: the former, focused to investigates the carbon sources features as well as the effective biodegradation capability, carried up in batch; the second carried out by means of lab-scale column continuously fed by water artificially contaminated with nitrates. The achieved results have shown good removal efficiency and also significant differences in kinetics have been highlighted. Particularly, olive pomace was the organic substrate capable to promote the best denitrification performances.

The paper reports the main results from an experimental gathering campaign carried out on a bench scale plant for the evaluation of hydrocarbon effect on the system performance. In particular, a membrane bioreactor (MBR) under submerged configuration was analysed. The MBR plant was fed with synthetic wastewater containing hydrocarbons. Organic carbon, hydrocarbons and ammonium removal, kinetic constants, extracellular polymeric substances (EPSs) production and membranes fouling rates have been assessed. The observed results highlighted good system performance in terms of both COD removal and nitrification, thus showing a sort of biomass adaptation to hydrocarbon. Such a result has been also confirmed by the biomass respirometric tests. Moreover, membrane fouling analysis showed an increase of the total resistance in the last period of the experiments. Such a result was most likely due to the hydrocarbon which caused an irreversible fouling due to oil deposition onto the membrane surface.

Sono state investigate le performance di due impianti SBR (Sequencing Batch Reactor), alimentati con refluo sintetico a base di acetato di sodio e funzionanti con due differenti tipi di fango aerobico granulare, in termini di dimensione media dei granuli. In particolare, è stato analizzato l’impatto della differente dimensione dei granuli sul processo di nitrificazione e denitrificazione simultanea (Simultaneous Nitrification Denitrification, SND) e sulla rimozione biologica del fosforo. Allo scopo di valutare l’efficienza di tale tipo di processo, sono state applicate differenti strategie di coltivazione e condizioni operative, in termini di carico organico (COD 600-1200 mg/L) e azoto (60-120 mg/L) e di concentrazioni di ossigeno. I risultati ottenuti hanno evidenziato una soddisfacente resa di rimozione dei nutrienti e delle sostanze organiche, anche in condizioni di elevate concentrazioni di ossigeno disciolto. Inoltre, sono state rilevate differenti condizioni metaboliche (anossiche, anaerobiche e aerobiche) all’interno dei granuli, durante le fasi di inedia e abbondanza.

The paper presents the sensitivity analysis of an integrated urban water quality system by means of the global sensitivity analysis (GSA). Specifically, an home-made integrated model developed in previous studies has been modified in order to include the micropollutant assessment (namely, sulfamethoxazole - SMX). The model is able to estimate also the interactions between the three components of the system: sewer system (SS), wastewater treatment plant (WWTP) and the receiving water body (RWB). The analysis has been applied to an experimental catchment nearby Palermo (Italy): the Nocella catchment. Five scenarios each characterized by different combinations of sub-systems (i.e., SS, WWTP and RWB) have been considered applying the Extended-FAST method. Results demonstrated that GSA is a powerful tool for increasing operator confidence in the modelling results; the approach can be used for blocking some non-identifiable parameters thus wisely modifying the structure of the model and reducing the related uncertainty. The model factors related to the SS have been found to be the most relevant factors affecting the SMX modeling.

SUMMARY: Landfill leachate represents nowadays one of the most controversial topics in the waste management cycle. A possible alternative for treating aged landfill leachate is represented by the co-treatment with municipal wastewater (MWW) that provides the necessary amount of biodegradable substances to enhance the development of bacteria metabolism. The correct tradeoff between landfill leachate and MWW represent a key factor in order to avoid inhibition of biomass activity. The paper reports the results of an experimental research carried out on two lab-scale Sequencing Batch Reactors (SBRs) fed with synthetic wastewater and landfill leachate in different percentages (SBR1 fed with 20% v/v and SBR2 fed with 40% v/v of landfill leachate, respectively). The experimental campaign lasted almost 200 days and was divided into two phases (named phase I and II, respectively) characterized by different operational parameters of the SBRs cycle with the aim to investigate the influence of aeration phase duration on the biological removal of organic carbon and ammonium. Periodical sampling of inlet, mixed liquor, supernatant and effluent allowed investigating the biological process involved by measuring process parameters such as COD, TOC, NH4-N, NO3-N, NO2-N, TN, pH, salinity and electrical conductivity. Moreover, particle size distribution (PSD), extracellular polymeric substances (EPSs) and soluble microbial products (SMPs) of mixed liquor were also measured. Finally, respirometric techniques allowed the assessment of heterotrophic and autotrophic biomass viability. Achieved results allowed to notice a significant influence of landfill leachate in carbon removal (mean efficiency close to 60 % and 40% for SBR1 and SBR2 respectively). With reference to ammonium nitrogen oxidation, SBR1 was not affected by the leachate whereas in SBR2 significant inhibition phenomena occurred during the whole experimentation with temporary accumulation of NO2-N (due to nitrobacter inhibition). Moreover, during the last days of phase I, an aerobic granulation process occurred in SBR2, with a mean diameter of granules close to 0.2 mm.

Landfill leachate represents nowadays one of the most important issue related to the waste management cycle. Knowledge about leachate distribution and transport as well as fate of pollutants is fundamental for understanding the behavior of the landfill reactor. In the present study, a simple 1-D mathematical model was developed for the simulation of the vertical leachate fluxes throughout a landfill for MSW as well as the fate of inorganic pollutants within the landfill leachate pathway. The model was based on mass balance equations, which allowed to evaluate the moisture accumulation inside the landfill body as well as contaminant transport processes. The model enables to calculate the moisture content and the simulation of continuous moisture distribution was carried out on the basis of the theory of the vertically distributed unsaturated flow. The model has been applied to a real landfill considered as a case study. The observed results highlight that the proposed simple 1-D model can be a useful tool to analyze the landfill body as an unsaturated porous medium. The simulation results were in good agreement with the real leachate data provided by the landfill operator.

The paper reports the main results of an experimental campaign carried out on two bench scale pilot plants for treatment of synthetic shipboard slops. In particular, two membrane bioreactors (MBRs) with submerged configuration were analyzed. One MBR pilot plant (namely, Line A) was fed with synthetic shipboard slop and was subjected to a gradual increase of salinity. Conversely, the second MBR pilot plant (namely, Line B) was fed with the same synthetic shipboard slop but without salt addition, therefore operating as a “control” unit. Organic carbon, hydrocarbons and ammonium removal, kinetic constants, extracellular polymeric substances (EPSs) production and membranes fouling rates have been assessed. The observed results highlighted a stress effect exerted by salinity on the biological performances, with lower removal efficiencies in the Line A compared to Line B. Significant releases of soluble EPS in Line A promoted an increase of the resistance related to particle deposition into membrane pores (pore fouling tendency), likely due to a worsening of the mixed liquor features. Such a condition enhanced the reduction of the “pre-filter” effect of the cake layer.

COD AND TPH ANALYSIS IN SLOPS EXPERIMENTAL TREATMENT PLANTS: ANALYTICAL PROBLEMS. In the last years, the persistence and accumulation of xenobiotic compounds in the environment created many disposal problems of oily wastewater generated by ships, mainly in engine-rooms (bilge waters) and by cleaning of tanker (slops). The high salinity levels (up to 25.000 mgL-1) and the pollutants concentration, both limit the chances of discharge into the sewer systems and address the disposal of these wastewaters to the sea. For these reasons it is necessary to treat such wastewater efficiently before discharging [1]. As a part of a broader project concerning slops treatments, this work addresses issues related to the analytical methods of the COD and TPH parameters, chosen under the provisions of Italian Legislative Decree 152/06, that implements the European directives on environmental protection. In the COD analysis the greatest difficulty was the high salinity levels corresponding to high chlorides levels. Chlorides cause a positive interference in the measurement, and this interference during the analysis of COD was investigated at various concentrations of mercury in order to try to minimize the use of this reagent that causes many problems of safety and disposal, and at different times reaction [2][3][4]. The major problems in TPH analysis concerned correct setup of the gas chromatographic separation, high variability in sample composition and the high capacity of the sample to form emulsions during the liquid-liquid extraction procedure. This paper reports the results of the analysis of COD and TPH and the problems related to the development of a suitable analytical method for the analysis of these specimens. This study is part of STITAM European project, created with the aim to develop innovative technologies for the treatment of liquid wastes of navigation, in order to better safeguard marine environment. [1] G. Mancini, S. Cappello, M.M. Yakimov, A. Polizzi, M. Torregrossa, Chemical Engineering Transactions 27 (2012) 37-42. [2] I. Vyrides, D.C. Stuckey, Bioresource Technology 100 (2009) 979–982 [3] Alexandra M.E. Viana da Silva, Ricardo J.N. Bettencourt da Silva , M. Filomena G.F.C. Camoes, Analytica Chimica Acta 699 (2011) 161– 169 [4] D.D.C. Freire, G.L. Sant’anna jr, Environmental Technology 19 (1998) 1243- 1247

The paper focused on the evolution of extracellular polymeric substances (EPSs) content during the granulation process in two Granular Sequencing Batch Airlift Reactors (GSBAR) (3,5 L) fed with synthetic and industrial wastewater. Results showed that EPSs, in particular proteins (PN) were mainly produced during the feast phase because of high substrate availability, especially under conditions of metabolic stress. Than EPSs content reduced during the famine period. More in detail, during the granulation process, a greater polysaccharides (PS) consumption occurred in both reactors, while PN content reduced significantly only in R2. As a result PN/PS ratio increased significantly during granules formation, confirming the key role of proteins on granules formation. R2 granules exhibited a greater amount of PN on average, and this resulted in a more rapid granulation. However, due to the several consumption of PN during the famine period, R2 granules resulted weaker an less dense than R1 ones, hence more susceptible to breakdown. When EPSs consumption during the famine phase reduced, granules reached their maturation.

SUMMARY: the waste disposal in sanitary landfills generates landfill gas (LFG), mainly constituted by methane (CH4) and carbon dioxide (CO2), because of the anaerobic degradation of the organic matter contained in the disposed waste. It is worth mentioning that CH4 is recognized as one of the most important contributor to global warming and sanitary landfills for Municipal Solid Waste (MSW) have been found to be a significant source of CH4 generation and emission. The main aim of the present work was the evaluation of methane emissions from a Sicilian landfill site by coupling of direct field measurements and ground temperature data acquired through remote sensing techniques. It is worth mentioning that both acquisition methodologies were performed almost simultaneously. The investigated landfill cell was in a post-operation phase and with permanent final cap. The obtained results revealed a correlation between methane flux and surface ground temperature in the investigated area. However, further studies are required to fully explain the mechanisms of this relationship, also referring to the distribution of the specific heat of ground surface.

La quantizzazione delle emissioni di CH4 da discariche rappresenta un tema di rilievo nella gestione dei rifiuti. La capacità emissiva delle discariche, direttamente correlata alla decomposizione anaerobica della sostanza organica in esse smaltita, può durare per decine di anni sebbene la massima produzione di biogas si registra nei primi anni seguenti l’abbancamento dei rifiuti. Nella nota si riferisce dei risultati di alcune campagne di misura eseguite su discariche controllate per rifiuti urbani, dotate di differente tipo di copertura; in particolare, la prima discarica è dotata di capping definitivo, la seconda di capping temporaneo. I risultati ottenuti hanno evidenziato una significativa influenza del sistema di copertura sul valore delle emissioni, con flussi di un ordine di grandezza inferiore nel caso della discarica dotata di capping definitivo

The paper presents the results of a field gathering campaign carried out on two different pilot scale membrane bioreactor (MBR) systems, treating synthetic wastewater subject to a gradual increase of salinity. One was a conventional MBR system, while the other was a moving bed biofilm membrane bioreactor (MB-MBR), which combines suspended biomass and biofilm. Indeed, the presence of suspended carriers inside the bioreactor seems to give benefits due to the collisions between the circulating media and the membrane. The aim of the study was the comparison of two configurations in terms of biomass activity characterization and performance (pollutants removal and hydraulic behaviour). The results highlighted a significant biomass activity for both heterotrophic and autotrophic populations. Such behaviour was emphasized in MB-MBR system, likely due to the presence of biofilm attached on suspended sponge carriers, which is characterized by high retention times, thus improving through the “seeding” effect the nitrification ability of the whole system.

Nitrates pollution represents nowadays a serious issue related to the quality of groundwater; continuous growth of industrial-scale agricultures lead to an increase of nitrates content in groundwater in the last years. Several technologies have been validated as capable to promote in situ biological nitrates remediation, such as permeable reactive barriers (PRB), biotrench, biobarriers etc. These technologies are all characterised by the use of organic substrate that act as a slow release carbon source. In free dissolved oxygen absence, such organic carbon is further oxidised, by heterotrophic bacteria naturally present in soil, in compliance to anoxic metabolism by using nitrates bound oxygen. Such dissimilatory reaction converts nitrates in elemental nitrogen. Organic substrates capable to sustain this reaction are various and easily recoverable (e.g. sawdust, cotton, woodchips etc.); thus, several carbon source has been already tested. The present paper reports the results of batch test carried out on four organic substrates used to promote biological denitrification; in details the organic matters tested were: sawdust, pine bark, cork and olive pomace. The first step of experimental study was focused to evaluate the organic carbon release capability of each substrate; particularly, organic matter has been keep in contact with tap water for almost 10 days; thus, samples of water has been periodically collected to measure Total Organic Carbon (TOC). Further, microcosm batch test has been carried out to reproduce in situ biological groundwater denitrification. In details, each batch reactor was prepared with a mixture of organic matter and agricultural soil, used to provide heterotrophic bacteria capable to promote biological denitrification, kept in contact with tap water artificially spiked at 60 mg NO3-N L-1. Batch test were realized in slow agitation condition, by using a vibratory plate, and were carried out for 12 days. All organic matters tested provided good results, in terms of removal efficiency; further, specific denitrification rate has been computed and ranged from 0.06 (olive pomace) to 0.51 (sawdust) mg NO3-N L-1 d-1g-1sub. Column test are actually in progress to evaluate the biological denitrification in continuous.

Il crescente impiego di fertilizzanti contenenti azoto ha avuto come effetto l'accumulo di nitrati nelle acque di falda. A causa della natura diffusa delle sorgenti di contaminazione, la necessità di individuare interventi di risanamento a basso costo e che richiedano attività gestionali ridotte è diventata prioritaria. In tale ottica, notevole interesse hanno recentemente riscosso i trattamenti biologici in situ, in grado di promuovere le denitrificazione delle acque di falda mediante la realizzazione di biobarriere. Nella nota vengono riportati i risultati di una ricerca sul processo di denitrificazione eterotrofa promosso utilizzando come fonte di carbonio tre materiali convenzionalmente considerati di scarto: corteccia di pino, sughero e sansa di olive. Test in colonna sono stati effettuati per un periodo di 200 giorni, al fine di osservare il processo di denitrificazione stimolato dai substrati prescelti; i risultati ottenuti alimentando acqua artificialmente contaminata di nitrati hanno mostrato buoni rendimenti di rimozione, evidenziando sostanziali differenze delle cinetiche di processo tra i vari substrati.

The paper reports the main results of an experimental study carried out on a Membrane Biological Reactor (MBR) pilot plant characterized by intermittent aeration. The effect of different aeration/non aeration ratio (TA/TNA) on biomass behavior, in terms of heterotrophic and autotrophic kinetic parameters and active biomass fraction, was studied. Moreover was proposed a method to evaluate the autotrophic active fraction, derived by a combination of the ASM1 model and biokinetic parameters directly evaluated by means of respirometry. The experimental observation outlined that TA/TNA in the cycle didn’t affect heterotrophic biomass kinetic and active fraction. This one instead, resulted strongly depended from the soluble substrate present in the influent wastewater. Furthermore, it was observed that a higher aerated phase within the cycle, may lead to a higher autotrophic biomass active fraction.

Two pilot plants were investigated for the treatment of wastewater subject to a gradual increase of salinity. In particular, a membrane bioreactor (MBR) and a moving bed biofilm membrane bioreactor (MB-MBR) were studied. Carbon and ammonium removal, kinetic constants and membranes fouling rates have been assessed. Both plants showed very high efficiency in terms of carbon and ammonium removal and the gradual salinity increase led to a good acclimation of the biomass, as confirmed by the respirometric tests. Significant biofilm detachments from carriers were experienced, which contributed to increase the irreversible superficial cake deposition. However, this aspect prevented the pore fouling tendency in the membrane module of MB-MBR system. On the contrary, the MBR pilot, even showing a lower irreversible cake deposition, was characterized by a higher pore fouling tendency.

In the last decades landfilling has been the main method of municipal solid waste (MSW) disposal in many countries. MSW landfills are usually considered as a large biological reactor where the MSWs undergo anaerobic digestion producing gas and liquid emissions. Aged, or mature leachate, which is produced by older landfills, can be very refractory; for this reason mature leachate is difficult to treat alone, but it can be co-treated with sewage or domestic wastewater. The aim of the study was to investigate the feasibility of co-treatment of landfill leachate and synthetic wastewater in different percentages, in terms of process performance and biomass activity, by means of respirometric techniques. Two sequencing batch reactors (SBR) were fed with synthetic wastewater and different percentages of landfill leachate (respectively 10% and 50% V/V in SBR1 and SBR2). The obtained results showed a good organic carbon removal efficiency for both reactors; ammonia removal efficiency showed different trends between SBR1 and SBR2, probably due to inhibition factors exerted by high landfill leachate percentage present in SBR2.

Lo studio presentato in questo lavoro ha avuto come obiettivo il monitoraggio e l’analisi del destino dei radionuclidi negli impianti di depurazione ed è stato condotto in collaborazione tra l’Università di Palermo e ARPA Sicilia. Esso ha previsto lo svolgimento di due fasi sperimentali. Nel corso della prima sono stati monitorati gli impianti di depurazione a servizio dei Comuni di Palermo (in località Acqua dei Corsari e Fondo Verde), Bagheria e Cefalù; nella seconda fase l’indagine è stata limitata al solo impianto di Acqua dei Corsari, nel quale si erano riscontrati in precedenza i maggiori spunti di interesse. In entrambe le fasi sono stati prelevati campioni istantanei in diverse sezioni degli impianti oggetto del monitoraggio: influente, vasca a fanghi attivi, ricircolo di fango, effluente del sedimentatore secondario e fango disidratato. I campioni sono stati analizzati con l’obiettivo di determinare l’attività dei principali radioisotopi di origine antropica, per via del loro uso medicale, o presenti nell’ambiente. L’identificazione e la quantificazione dell’attività dei radioisotopi nei campioni prelevati sono state condotte mediante tecniche di spettrometria gamma, utilizzando le strumentazioni disponibili presso l’Università di Palermo e il Laboratorio di radioattività della Struttura Territoriale di Palermo di ARPA Sicilia. Le attività dei radionuclidi rilevate nei vari punti di campionamento sono state utilizzate per la valutazione del rischio radiologico dei lavoratori e verificare il rispetto dei limiti di esposizione. I risultati ottenuti hanno generalmente evidenziato che il radiosotopo maggiormente presente nei campioni analizzati è risultato lo 131I, verosimilmente a causa del suo elevato tempo di dimezzamento. Inoltre è stata riscontrata una maggiore affinità dei radionuclidi nei confronti della componente solida presente nelle acque reflue, circostanza questa che comporta il loro progressivo trasferimento nei fanghi di depurazione, con particolare riferimento, per lo 131I alla frazione organica in essi presente. Tuttavia le attività di 131I rilevate nei fanghi depurazione sono risultate inferiori ai valori limite imposti dalla normativa vigente (D.Lgs. 230/95, D.Lgs. 241/00), per il loro smaltimento.

Membrane bioreactors (MBRs) have been widely used for the treatment of various wastewater, including municipal, industrial, landfill leachate (Wintgens et al., 2005). Such systems generally provide decisive advantages compared to conventional activated sludge (CAS) processes: in particular, they feature high quality effluent, small footprint and low sludge production rates (Stephenson et al., 2000). In recent years MBRs have also been used for the treatment of specific saline water, such as wastewater produced from shipboard activities, aquaculture wastewater or wastewater deriving by sediment washing treatment, as an example. However, when subject to salinity, a modification of biomass characteristics may occur. This circumstance is of importance, since it can have a significant impact in terms of biokinetic as well as fouling behaviour. The aim of the study was to evaluate the performance of a pilot plant MBR (fed with synthetic wastewater) in terms of performance, biomass activity and membrane fouling, when subject to a gradual salinity increase. In detail, the experimental campaign was divided in five different phases, each characterized by a different NaCl dosage (1st phase: no salt addition, 2nd phase: 1 g NaCl L-1; 3rd phase: 2.5 g NaCl L-1; 4th phase: 5 g NaCl L-1; 5th phase: 10 g NaCl L-1). The lab scale MBR was built at the Laboratory of Sanitary and Environmental Engineering of Palermo University and consisted in a 17 L bioreactor coupled to a 7 L compartment where a hollow fibre ultrafiltration (UF) module in a submerged configuration was inserted (ZeeWeedTM 01 module; porosity: 0.04 m; surface area: 0.1 m2). Specific respirometric batch tests were conducted in order to characterize the biokinetic behaviour of the MBR pilot plant, using a “flowing-gas/static-liquid” type as batch respirometer (Spanjers et al., 1996). The total Extracellular Polymeric Substances (EPST) concentration was periodically measured by means of the Heating method (Zhang et al., 1999), described in detail in Di Bella et al. (2011). The Soluble Microbial Products (SMPs), that represent the soluble portion of EPST, as well as the bound EPS (EPSbound) were measured through this protocol. The pilot plant showed very high COD removal efficiencies throughout the experimental campaign, with an average value close to 94%, as reported in Figure 1a. As the salinity of the inlet wastewater was increased, it was observed a slight decrease of COD removal efficiency which, however, was always higher than 88%, thus confirming the system robustness. Concerning the nitrification process, the average value was equal to 99% (Figure 1b), highlighting that a gradual salinity increase exert only a moderate influence on nitrifying population.Referring to membrane fouling, the salinity increase exerted a significant effect on the total resistance, in particular starting from the 3rd phase (Figure 2a). Cake resistance represented the majority of total hydraulic resistance; in particular, the irreversible cake deposition was recognised as the predominant fouling mechanism (Figure 2b), likely due to EPS release by the biomass

The aim of this study is to detect a possible relationship between EPS and fouling and EPS and foaming in a University Cape Town (UCT) membrane bioreactor (MBR) pilot plant. The UCT-MBR pilot plant was fed with 40 L/h of real wastewater and monitored for 165 days. Specifically physical/chemical features of influent, permeate and mixed liquor in different sections were analyzed. The fouling phenomenon was studied monitoring the hydraulic resistances of the membrane. The extracellular polymeric substances (EPSs) concentration inside the aerobic tank were also measured. The foaming phenomenon was monitored by performing the Foam Power and Scum Index testes. Results have shown a high correlation between fouling and EPS distribution and foaming and bound EPSs concentration. None correlation was found comparing foaming and fouling indicating that further studies have to be performed in order to deep this issue

Nowadays, due to the increasing awareness about environmental impact of discharges, it is necessary to realize biological processes that allow complete treatment of wastewater, able to produce high quality effluents that could be used for recycling and reuse purpose. A possible solution to cope with this issue is represented by membrane bioreactors (MBRs), which are combined systems including a bioreactor and a filtration unit. However, in presence of high strenght domestic or industrial wastewater, a modification in biomass kinetics as well as in sludge characteristics may occur. This situation is of importance, since microbial community characteristics can play an important role in membrane fouling, which still represents the major drawback of MBRs. The aim of the paper was to evaluate the performance of a laboratory scale MBR system treating high strength synthetic wastewater, in terms of biomass activity and fouling behaviour. The pilot plant showed high removal efficiencies, and high respiration rates, in terms of oxygen uptake rate values, especially for heterotrophic population, coupled to a storage phenomenon, typical of dynamic conditions occurring in the process. On the other hand, the batch tests carried out on the autotrophic population suggested a good development of nitrification activity.

Membrane fouling represents one of the major limiting issue for membrane bioreactor (MBR) in the wastewater treatment field. Membrane fouling and high aeration requirement (for inducing shear stress to limit fouling) in MBR systems make the operation of such systems economically demanding due to high energetic costs. Despite several studies on MBR fouling have been performed a comprehensive knowledge on how to reduce membrane fouling and consequently energy saving is still lacking and controversial. The aim of this study is to gain insights on the optimization of the operating conditions in an MBR system. In particular, the influence of the aeration intensity and the durations of filtration and backwashing phase were analyzed in order to optimize the energy saving and effluent quality. To accomplish such goals an integrated MBR model developed and calibrated in previous studies was employed. Monte Carlo simulations were performed for different scenarios each implementing different operating conditions. The results demonstrated that the air flow rate is a key parameter for controlling and reducing the energetic demand and for maintaining a high quality effluent.

This paper reports on some results of two surveys at sea carried out in the surroundings of a urban wastewater discharge on the coast of the Golfo di Palermo, western Sicily (Italy). At the time of the surveys (year 2005) the stretch of water lying before the central part of the capital town received the untreated wastewater originating from about 200 000 inhabitants, which was discharged on-shore without any prior treatment by the free-surface outfall of “Porta Felice main sewer”. This outfall has crucial importance in the water quality; indeed, the Municipality is steadily implementing a plan featuring an intercepting main sewer along the coast and some pumping stations to connect all the main sewers to the main wastewater treatment plant, located in the SE boundary area of the town. At the moment of the surveys, however, no mitigation measure had been applied yet and the quality of the Gulf was still largely affected by it. Part of the Sanitation Plan was the characterization of the seawater; to this aim, in August and November, 2005, the Università degli Studi di Palermo - on behalf of the Municipality’s Ufficio del Centro Storico - carried out two survey cruises in which the most important seawater quality features were investigated. What will be reported on herein is the part dealing with microbiological indicators, taking the salinity field as background.

Climate is one of the most important factors leading to changes in the hydrologic and environmental characteristics of river basins. When considering water quality, the natural factors should be weighed against anthropogenic factors (such as urbanization, increased population, and higher water demand) that may increase or decrease the effect of climatic modifications. Any prediction of future climatic and anthropogenic scenarios is affected by uncertainty and the modelling tools that are used for evaluating their impact on receiving water bodies. The present paper is aimed at investigating the complexity of such analyses and the uncertainty related to future impact predictions based on limited databases. Specifically, the study is focused on quantifying the impact of urbanization and social changes coupled with climate on river water quality under uncertainty. The study was carried out at a small catchment scale (less than 100 km2), an analysis that has been lacking from the field so far. The analysis took into account both anthropogenic change and climate determined from observed data. Because of inherent uncertainty in the model caused by the complexity of the model and its calibration, the analysis was performed considering the effect of such uncertainty on reliability by means of Monte Carlo simulations. This analysis has been applied to a monitored semiurbanized basin in Sicily (Italy). The study showed that the proposed analyses can useful for planners and urban managers; however, the uncertainty connected with mathematical modeling and small available databases has to be taken into account because it can affect decision making. The impacts of anthropogenic changes and climate can interact, thus requiring that such factors be jointly analyzed. A larger effort in monitoring and characterization of natural and urban water systems is needed to increase the reliability of models and to improve the effectiveness of decision making based on such models

During the last decades, the largest part of municipal solid waste (MSW) generated world wide has been disposed of in landfills without any pre-treatment. The main environmental impacts of such landfills, containing high amounts of biodegradable organic matter, are caused by emissions of liq-uid effluents and landfill gas. With no collection and treatment, leachates from landfills pollute groundwater and soils locally. Furthermore, besides the biological processes, many physical phe-nomena occur inside the landfill body which negatively affect landfill management. Indeed, the waste settlement inside the landfill body, with a consequent increase of its density, corresponds to a proportional decrease of waste permeability; such aspect may cause serious problems to leachate drainage through the waste body, with the possible formation of the so-called suspended “perched leachate zone”. The perched leachate zone is a temporary phenomenon, which evolves downwards, reaching the bottom of the MSW landfill and producing a leachate head above the leachate collec-tion system. Such phenomenon is strongly influenced by many factors and, among others, the rain infiltration rate, waste moisture content and landfill height are of great concern. Bearing in mind such considerations, the main aim of the paper is to present a mathematical modelling survey to gain insights about the role played by the landfill height and the initial MSW moisture content. To accomplish such a goal, a previously developed 1D mathematical model was employed. The math-ematical model allows the simulation of the percolation fluxes throughout a MSW landfill. Specifi-cally, the model is based on mass balance equations and considers the landfill divided in several layers evaluating the inflow to and outflow from each layer as well as the continuous moisture dis-tribution. Several model simulations were performed considering different landfill heights and MSW initial moisture. The model results showed a different response of the landfill in terms of flow rates throughout the landfill. Indeed, the landfill height content drastically influenced not only the formation of perched leachate zones but also their extension. In particular, the model results showed that there is a sort of landfill threshold height, below which, the perched leachate zone does not appear.

The occurrence of nitrates in groundwater is steadily raising concern due to possible health consequences of nitrate ingestion. Biological denitrification in BIO-PRB is the enhancement of a natural process that occurs naturally when bacteria live in an environment void of oxygen with carbon availability. Bio-PRB represent a perspective of development for PRB technique but, despite the fact that this technology has already been widely used for chlorinated solvents, data on denitrification PRBs are still scarce. This paper reports on the results of an experimental study carried out for 214 days on a bench-scale pilot column (10 cm in internal diameter and 100 cm in length with sampling ports at different heights). The column was filled with a mixture of sand, agricultural soil and sawdust (30%, 20% and 50% v/v respectively) and was fed in continuous with a solution maintained at constant concentration of 25 mg/dm3 NO3-N for early 110 days and then gradually increased to 50 mg/dm3 NO3-N. Good nitrate removal performance (up to 99%) were observed with a direct correlation between nitrates removal rate and carbon availability in column.

The paper presents a mathematical model for the simulation of the ecological status of a wastewater stabilization reservoir (WSR). WSRs are hypertrophic aquatic systems devoted to storage of water resources in warm countries where shortage conditions have quite often to be faced. Several factors that affect the stabilization reservoir effluent quality were taken into account: hydraulics and hydrology, solar radiation, atmospheric reaeration, algae, zooplankton, organic matter, pathogen bacteria, and sediment-water interaction. The model quantifies the specific influence of each factor on effluent quality, evaluating the correlation between the different considered factors. State variables included in the model were: algae, dissolved oxygen, organic matter, zooplankton and indicator bacteria. The model was applied to an Italian stabilization reservoir located in the south part of Sardinia: the Simbirizzi’s lag. The model showed satisfactory results and can be employed as an useful tool for environmental water quality management of stabilization reservoirs.

Municipal Solid Waste (MSW) landfills have been identified as one of the most important sources of methane (CH4) emission. MSW contains a certain amount of biodegradable organic matter which undergoes anaerobic degradation resulting in the production of the landfill gas (LFG), which main component is tipically represented by CH4. In order to minimise its negative effects on the envi-ronment, LFG recovery is a suitable tool to control CH4 emissions from a landfill site and the measurement of CH4 emissions represents a good way to evaluate the effectiveness of LFG recover-ing system in reducing biogas emission to the atmosphere. However, up to now few measurements of landfill CH4 emissions have been reported, due to the heterogeneity of waste composition and temporarily landfill surface covering which give as a result high spatial variability of the LFG emis-sion from the landfill surface. The main aim of the present study was to evaluate CH4 diffuse emis-sions, based on direct measurements carried out at Palermo (IT) landfill by means of a flux accumu-lation chamber coupled with a flame ionization detector (FID). The field campaign was carried out over a period of two years, and it was split into several experimental phases, performed in different seasons, in order to evaluate the influence that specific landfill features have on CH4 emissions, as well as to understand the influence exterted by meteorological conditions during the field cam-paigns. Through the use of a geostatistic methodology, the instantaneous CH4 fluxes from the land-fill surface have been used to obtain the total amount of methane emitted from the investigated area as well as the methane flux maps. Such emissions were further compared with the estimate achieved by means of CH4 mass balance equations. The obtained results showed that a relationship between the local CH4 emissions and some specific features of landfill can be established, and that the emis-sions obtained by applying the flux accumulation chamber method are in good agreement with the ones derived by the application of mass balance equations, also suggesting that the contoured flux maps represent a reliable tool to locate areas with abnormal emission in order to improve the gas re-covery system efficiency.