22 research outputs found
Phosphate recovery from aerobic wastewater Bio-P Sludge through precipitation process: understanding, experimentation and optimization.
No full textStruvite precipitation process is one the most effective approaches for recovery of phosphorus in the form of a valuable product, which could be used as a fertilizer. Despite struvite added value as a product, its application at full scale is not very common worldwide due to its economic concern of requiring the addition of Mg and NaOH to the system. The process of struvite precipitation is generally applied to the dewatered sludge after anaerobic digestion where the concentration of phosphorus is sufficiently high. Although it could be possible to use the aerobic sludge taken from the activated sludge process in which phosphorus release is happening in the anaerobic stage and a luxury uptake occurs in the aerobic zone.
Lab-scale experimentation was carried out in this thesis on the process of struvite precipitation using the aerobic sludge taken from Nosedo WRRF, Milan, Italy. The impact of different reaction parameters has been studied on the process of struvite precipitation. Particular attention was paid to the effect of pH, Mg:NH4:P molar ratio and presence of calcium. The results showed that abundant amount of Mg and NH4 are required for significant struvite precipitation. The analysis of precipitates using FTIR, XRD, TGA-MS, ICP-AES and Elemental analysis showed the presence of struvite in notable amounts for the experiments with 5:5:1 molar ratio at pH=8.5 and 9.0. in addition, the use of Ca(OH)2 as an economic pH adjustment reagent showed a decent potential for obtaining an amorphous calcium phosphate (ACP) precipitates alternatively to the pure struvite.
Chemical equilibrium modeling and statistical optimization of the process of struvite precipitation were conducted using PHREEQC software and Response Surface Methodology (RSM) respectively with Saturation Index and P removal % as response variables. The results showed that struvite, ACP and calcite are three main solid phases that could precipitate in operating conditions of the experiments. It is also noted that the only parameter affecting significantly on the P removal was the pH while Ca:Mg and NH4:P were also significantly important for the struvite SI. It can be concluded that as the pH increases the P removal also increases but the possibility of struvite precipitation diminishes since the struvite SI is decreasing.
Pilot-scale study of the phosphate precipitation process was implemented using synthetic solution with the characteristics of aerobic sludge. The effect of pH and retention time of the reaction were studied. The pH of the reactor was controlled at two points using PID-Time Proportional control system. The result of the pH control was very satisfactory and kept the pH level sufficiently stable during the entire experimentation. The results demonstrated that P removal is not much dependent on the retention time and is decreasing rapidly with the start of the reaction and then reaches at the stable level where it does not improve anymore. It was also observed that RT of 60 minutes is enough for reaction completion but not for substantial crystal growth. The FTIR results showed the possibility of having a ACP-rich product. In addition, using sodium alginate demonstrated a potential for increasing struvite precipitation possibility by reducing calcium concentration by 20% and improving the Mg:Ca ratio
Phosphate recovery from aerobic wastewater Bio-P Sludge through precipitation process: understanding, experimentation and optimization.
No full textStruvite precipitation process is one the most effective approaches for recovery of phosphorus in the form of a valuable product, which could be used as a fertilizer. Despite struvite added value as a product, its application at full scale is not very common worldwide due to its economic concern of requiring the addition of Mg and NaOH to the system. The process of struvite precipitation is generally applied to the dewatered sludge after anaerobic digestion where the concentration of phosphorus is sufficiently high. Although it could be possible to use the aerobic sludge taken from the activated sludge process in which phosphorus release is happening in the anaerobic stage and a luxury uptake occurs in the aerobic zone.
Lab-scale experimentation was carried out in this thesis on the process of struvite precipitation using the aerobic sludge taken from Nosedo WRRF, Milan, Italy. The impact of different reaction parameters has been studied on the process of struvite precipitation. Particular attention was paid to the effect of pH, Mg:NH4:P molar ratio and presence of calcium. The results showed that abundant amount of Mg and NH4 are required for significant struvite precipitation. The analysis of precipitates using FTIR, XRD, TGA-MS, ICP-AES and Elemental analysis showed the presence of struvite in notable amounts for the experiments with 5:5:1 molar ratio at pH=8.5 and 9.0. in addition, the use of Ca(OH)2 as an economic pH adjustment reagent showed a decent potential for obtaining an amorphous calcium phosphate (ACP) precipitates alternatively to the pure struvite.
Chemical equilibrium modeling and statistical optimization of the process of struvite precipitation were conducted using PHREEQC software and Response Surface Methodology (RSM) respectively with Saturation Index and P removal % as response variables. The results showed that struvite, ACP and calcite are three main solid phases that could precipitate in operating conditions of the experiments. It is also noted that the only parameter affecting significantly on the P removal was the pH while Ca:Mg and NH4:P were also significantly important for the struvite SI. It can be concluded that as the pH increases the P removal also increases but the possibility of struvite precipitation diminishes since the struvite SI is decreasing.
Pilot-scale study of the phosphate precipitation process was implemented using synthetic solution with the characteristics of aerobic sludge. The effect of pH and retention time of the reaction were studied. The pH of the reactor was controlled at two points using PID-Time Proportional control system. The result of the pH control was very satisfactory and kept the pH level sufficiently stable during the entire experimentation. The results demonstrated that P removal is not much dependent on the retention time and is decreasing rapidly with the start of the reaction and then reaches at the stable level where it does not improve anymore. It was also observed that RT of 60 minutes is enough for reaction completion but not for substantial crystal growth. The FTIR results showed the possibility of having a ACP-rich product. In addition, using sodium alginate demonstrated a potential for increasing struvite precipitation possibility by reducing calcium concentration by 20% and improving the Mg:Ca ratio
Side-Stream Phosphorus Recovery in Activated Sludge Processes
No full textPrecipitation of mineral phosphates from wastewater treatment processes is an excellent method for phosphorus recovery, leading to the formation of compounds with high fertilizing value. Conventionally, P-precipitation processes are mostly applied to supernatant of anaerobic sludge digestates, due to their high P and N residual contents. This study concerns P-recovery in a pilot-scale side-stream reactor from aerobic (activated sludge) wastewater liquor. The effect of process retention time and pH was determined using sodium hydroxide and calcium hydroxide as alternative pH buffer reagents, in both synthetic and real wastewater. Equilibrium mass balance calculations were first applied to estimate the theoretical final composition of P-precipitates under different process conditions; then, actual precipitation experiments were carried out with synthetic wastewater to define optimal process operating parameters in controlled conditions. Results showed that phosphorus precipitation was affected mainly by solution pH and did not significantly depend on the reactor’s retention time. These findings were validated by operating the process with real wastewater: on average, 61.2% and 90.4% phosphorus precipitation (recovery) were achieved at pH = 8.5 and 9.0 under a controlled Mg:NH4:P molar ratio of 5:5:1, using sodium hydroxide as acidity buffer. The main fraction of final precipitates consisted of calcium phosphate compounds, while struvite, bobierrite and calcite showed up in smaller proportions. It was also shown that dosage of calcium hydroxide for pH adjustment, without any other chemicals for molar ratios adjustment of the solution, has great potential for P recovery in the form of a calcium phosphate-rich precipitate, usable for fertilizer, with 75.6% phosphorus removal in mineral form at pH = 8.5. The process is much less costly to operate than struvite precipitation, and more energetically sustainable. This scheme could be ideally suited for application in facilities operating under an enhanced phosphorus removal process scheme
Osservazione delle zone marine costiere da dati ottici multi-sensore: il caso studio della foce del Volturno
No full textQuesto lavoro s’inserisce nell’ambito del progetto bandiera RITMARE (Ricerca ITaliana per il MARE, 2012-2016, MIUR-CNR) che ha lo scopo di studiare, monitorare, gestire e valorizzare la risorsa marina in Italia. A tale fine il telerilevamento è parte integrante al progetto che, in questo studio, viene applicato alla fascia costiera della foce del Volturno. Lo studio si avvale dell’utilizzo di immagini satellitari (RapidEye (2013) e Landsat-8 OLI (2014)) e aviotrasportate (MIVIS (2011)). A supporto dell’analisi delle immagini sono state acquisite misure in-situ di riflettanza e di concentrazione dei seguenti parametri: clorofilla-a (Chl-a), sedimenti totali sospesi (TSM) e sostanza organica colorata disciolta (CDOM) durante una campagna svoltasi in agosto 2014. I dati telerilevati, geocodificati e co-registrati, sono stati pre-elaborati per correggere gli effetti radiometrici ed atmosferici. Le immagini sono state successivamente elaborate per classificare le acque marino-costiere secondo diversi gradi di complessità ottica e per produrre mappe di concentrazione di Chl-a, TSM e CDOM. In particolare, per la generazione delle mappe è stato applicato un approccio semi-empirico basato su analisi di correlazione dei dati in-situ; in particolare tra valori spettrali di riflettanza (es. rapporti di banda) e le corrispondenti misure di concentrazione di Chl-a, TSM e CDOM. I risultati mostrano un gradiente crescente di complessità ottica delle acque spostandosi dalle zone pelagiche verso le aree costiere. In queste aree l’analisi del dato OLI ha mostrato una variabilità spaziale di Chl-a, TSM e CDOM imputabile ai regimi idrologici del fiume Volturno
Potret Islamic Studies dan Islam Apologetics (Telaah atas Pandangan Majid Daneshgar tentang Islamic Apologetics)
No full textIn the academic environment, learning Islamic Studies gives rise to various polemics and debates. This research will discuss the thoughts of contemporary Muslim figure about Islamic Studies, Majid Daneshgar in his book "Studying the Qur\u27an in the Muslim Academy." By using descriptive-analytical research methods, the author attempts to explain descriptively what is behind Majid Daneshgar\u27s thoughts on Islamic studies, then the author critically analyzes whether his thoughts are in accordance with the culture of Muslim academic Islamic studies in Indonesia? This research consists of primary and secondary data. Primary data was obtained from the opinions expressed by Daneshgar in his book "Studying the Qur\u27an in the Muslim Academy," while secondary data was obtained by looking at literature that discussed Majid Daneshgar\u27s thoughts and Islamic Studies. From this research, the author concludes that the tradition of Islamic studies in the academic environment (especially in Indonesia) is not entirely Islamic Apologetics as stated by Majid Daneshgar
The Potential Phosphorus Crisis: Resource Conservation and Possible Escape Technologies: A Review
No full textPhosphorus is an essential nutrient for every organism on the Earth, yet it is also a potential environmental pollutant, which may cause eutrophication of water bodies. Wastewater treatment plants worldwide are struggling to eliminate phosphorus from effluents, at great cost, yet current research suggests that the world may deplete the more available phosphorus reserves by around 2300. This, in addition to environmental concerns, evokes the need for new phosphorus recovery techniques to be developed, to meet future generations needs for renewable phosphorus supply. Many studies have been, and are, carried out on phosphorus recovery from wastewater and its sludge, due to their high phosphorus content. Chemical precipitation is the main process for achieving a phosphorus-containing mineral suitable for reuse as a fertilizer, such as struvite. This paper reviews the current status and future trends of phosphorus production and consumption, and summarizes current recovery technologies, discussing their possible integration into wastewater treatment processes, according to a more sustainable water-energy-nutrient nexus
Remote sensing observations for monitoring coastal zones : Volturno river mouth case study
No full textLAUREA MAGISTRALEL’obiettivo di questa tesi è lo studio delle acque costiere antistanti la foce del fiume Volturno (Italia meridionale) tramite l’utilizzo di tecniche di telerilevamento. A tale scopo, sono state considerate cinque immagini remote durante il periodo compreso tra il 2011 e il 2014. Le immagini sono state acquisite sia da sensori satellitari che aerei: le acquisizioni satellitari comprendono un’immagine Hyperion (01/07/2012), un’immagine RapidEye (11/08/2013) ed un’immagine LANDSAT OLI (09/09/2014), mentre per le acquisizioni aeree sono state scelte un’immagine MIVIS (26/06/2011) ed un’immagine Daedalus ATM (01/08/2012). A supporto dell’elaborazione delle immagini è stata condotta una campagna di misura in Agosto 2014 con lo scopo di caratterizzare otticamente le acque dell’area di studio tramite misure radiometriche e misure di concentrazione dei parametri otticamente attivi delle acque (Clorofilla-a (Chl-a), Sedimenti Totali Sospesi (TSM) e Sostanza Organica Colorata Disciolta (CDOM)). Le immagini remote sono state prima di tutto pre-processate applicando procedure di geocodifica, co-registrazione, correzione radiometrica ed atmosferica. Le successive fasi di elaborazione delle immagini hanno permesso di estrarre la linea di costa per le diverse date di acquisizione, di caratterizzare le acque marino-costiere in diversi gradi di complessità ottica e di derivare mappe di concentrazione relative a Chl-a, TSM e CDOM tramite l’applicazione di un approccio empirico. Tale approccio si basa sull’analisi della correlazione tra valori spettrali di riflettanza dell’acqua (es. rapporti tra valori di riflettanza in diverse regioni spettrali) e corrispondenti misure di concentrazione di Chl-a, TSM e CDOM. Le relazioni che meglio descrivono il comportamento dei dati misurati in campo sono state utilizzate per mappare la concentrazione delle tre componenti acquatiche lungo la fascia di acque otticamente complesse individuata nell’immagine OLI. I risultati mostrano un gradiente crescente di complessità ottica delle acque passando da acque pelagiche ad acque costiere. Nelle acque costiere otticamente complesse è stata osservata una variabilità spaziale della concentrazione di Chl-a, TSM e CDOM. Inoltre, dall’applicazione degli algoritmi empirici si nota come la concentrazione di TSM sembra essere più rilevante rispetto alla concentrazione delle altre due componenti acquatiche. Tramite il confronto delle linee di costa estratte dalle immagini a più alta risoluzione spaziale (Daedalus ATM, MIVIS e RapidEye) è stato possibile riscontrare alcuni cambiamenti nella forma della linea costiera nel tempo. Sono state osservate sia progressioni che regressioni della costa, probabilmente legate sia a processi naturali (es. erosione costiera) che antropici (es. realizzazione di nuove opere di mantenimento della costa).The aim of this thesis was to study coastal waters around the Volturno River mouth (southern Italy) by means of remote sensing techniques. For the purpose of the project five images were acquired between 2011 and 2014 from sensors mounted on both spaceborne and airborne platforms: MIVIS (26/07/2011), Hyperion (01/07/2012), Daedalus ATM (01/08/2012), RapidEye (11/08/2013) and Landsat OLI (09/09/2014). One fieldwork was organized in summer 2014 in order to optically characterize coastal waters using both radiometric measurements and measuring the concentration of optically active water components (i.e. Total Suspended Matter (TSM), Chlorophyll-a (Chl-a) and Colored Dissolved Organic Matter (CDOM)). Images were pre-processed in terms of geo-codification, co-registration, radiometric calibration and atmospheric correction. The elaboration of remotely sensed images included coastline extraction, image classification for the production of water complexity classes and the application of one empirical approach in order to derive maps of Chl-a, TSM and CDOM concentration along coastal waters. The empirical approach was based on finding the best correlation between spectral band ratios and in-situ measured Chl-a, TSM and CDOM concentrations. Through the application of the selected empirical algorithms, maps of Chl-a, TSM and CDOM concentration were obtained for coastal waters from the OLI image. The results showed an increasing gradient of water complexity from pelagic waters toward the coast, as well as a spatial variation in Chl-a, TSM and CDOM concentrations in complex waters near the coast. Generally, TSM concentration gathered from the application of empirical algorithm, is high compared to Chl-a and CDOM concentrations along coastal complex waters. Coastlines extracted from the higher spatial resolution images (Daedalus ATM, MIVIS and RapidEye) were compared, highlighting some changes in the shape of the coast and coastal surface area during time. Both progressions and regressions were observed, which are supposed to be related to both artificial and natural processes such as, man-made constructions and deconstructions, sea level changes and shoreline erosion
Erratum: Daneshgar, S., et al. Simulations and Laboratory Tests for Assessing Phosphorus Recovery Efficiency from Sewage Sludge, <em>Resources</em> 2018, <em>7</em>, 54
No full textThe authors wish to make the following corrections to this paper [...
Impact of pH and Ionic Molar Ratios on Phosphorous Forms Precipitation and Recovery from Different Wastewater Sludges
No full textPhosphorus is an essential nutrient for plants, which use it as a basic fertilizer component and is expected to increase significantly in the coming years due to higher food crops demand. Unfortunately, the available phosphorus natural reserves are not renewable, and estimates indicate their rapid decline in the future. Urban wastewater, due to its abundance and relatively high phosphorus content, is an excellent candidate for phosphorus recovery, while the element’s removal from urban effluents was introduced in the 1970′s to limit the undesired effects of eutrophication. In this study, the process of struvite (and related phosphorous compounds) crystallization was investigated for three different sludge types, and the results were compared. While most studies focus strictly on anaerobically digested sludge for high struvite precipitation efficiency, this study investigated the possibility of inducing precipitation on both aerobic (extended aeration) and anaerobic sludges produced by two wastewater treatment plants in northern Italy. Analysis of precipitates from sludge samples was compared, where the focus was on the aerobic sludge, and its potential for struvite recovery. The effect of different reaction parameters was studied under different operating conditions, and the use and effects of Ca(OH)2 addition as an inexpensive potential pH adjustment reagent was investigated
Holistic Approach to Phosphorus Recovery from Urban Wastewater: Enhanced Biological Removal Combined with Precipitation
No full textCombined phosphorus (P) removal and recovery from wastewater is a sensible and sustainable choice in view of potential future P-resource scarcity, due to dwindling primary global reserves. P-recovery from wastewater, notwithstanding the relatively small fraction of total global amounts involved (less than 1/5 of total global use ends up in wastewater) could extend the lifespan of available reserves and improve wastewater cycle sustainability. The recovery of the resource, rather than its mere removal as ferric or aluminum salt, will still allow to achieve protection of receiving waters quality, while saving on P-sludge disposal costs. To demonstrate the possibility of such a recovery, a strategy combining enhanced biological phosphorus removal and mineral P-precipitation was studied, by considering possible process modifications of a large treatment facility. Process simulation, a pilot study, and precipitation tests were conducted. The results demonstrated that it would be possible to convert this facility from chemical -precipitation to its biological removal followed by mineral precipitation, with minimal structural intervention. Considerable P-recovery could be obtained, either in form of struvite or, more sustainably, as calcium phosphate, a mineral that also has possible fertilizing applications. The latter would present a cost about one order of magnitude lower than the former
