Network Forensics and Privacy Enhancing Technologies “living” together in harmony

Privacy Enhancing Technology (PET) is the technology responsible to hide the identification of Internet users, whereas network forensics is a technology responsible to reveal the identification of Internet users who perform illegal actions through the Internet. The paper identifies the collision of these opposite-goal technologies and describes what happens in case they come across. Can a Network Forensics protocol discover the identification of an Internet user who is trying to be anonymous behind a PET? The paper also proposes a way to bridge and eliminate the gap between these two technologies

Uncontrollable Privacy - The right that every attacker desires

The request of the Internet users enjoying privacy during their e-activities enforces the Internet society to develop techniques which offer privacy to the Internet users, known as Privacy Enhancing Technologies (PETs). Among the Internet users, there are attackers who desire more than anything else to enjoy privacy during their malicious actions, and a PET is what they were looking for. Thus, although a PET should offer privacy to the internet users, proper techniques should also be employed in order to help the victims during the investigation procedure and unveil the identification of the attackers. The paper summarizes the current design issues of PETs and introduces additional issues in order to offer forensic investigation services. To the best of our knowledge this is the first attempt which it proves (the obvious) that the existing PETs do not meet accountability requirements. By knowing explicitly the reasons the PETs are inefficient offering accountability, it is the most appropriate way to make PETs offering higher level of accountability without decreasing the level of the privacy offered

Solar disinfection of secondary effluent and the subsequent bacterial regrowth : considerations, limitations and environmental perspectives

The present Thesis deals with the solar disinfection of synthetic secondary effluent under laboratory controlled conditions, focusing on the post-irradiation bacterial regrowth. The influence of various internal and external factors and their effect on solar disinfection, as well as bacterial regrowth kinetics are the subject under question. With the aid of a common fecal indicator microorganism, the effects of light intensity, temperature, initial bacterial concentration, light energy (wavelength), manner of delivery (continuous-intermittent) were investigated. Also, the post-treatment events, such as dark repair, photoreactivation and the survival in natural water matrices were assessed, along with the use of technical means (flow photoreactors with recirculation) and advanced oxidation processes (photo-Fenton and sonication) for regrowth risk minimization. The findings provided valuable output, conclusions on the suitability of solar irradiation as a secondary wastewater disinfection technique, indicating the limitations of its applicability, the considerations on the treatment specifications and its environmental perspectives.Η παρούσα Διδακτορική Διατριβή πραγματεύεται την απολύμανση δευτεροβάθμια επεξεργασμένων τεχνητών λυμάτων υπό ελεγχόμενες συνθήκες, μελετώντας το φαινόμενο της επανανάπτυξης / επανεμφάνισης των μικροοργανισμών μετά την ακτινοβολία των λυμάτων. Αντικείμενό της είναι η μελέτη της επίδρασης μιας ευρείας γκάμας ενδογενών και εξωγενών παραγόντων τόσο κατά την διαδικασία της απολύμανσης, όσο και στην κινητική του βακτηριακού πληθυσμού. Με τη χρήση κοινών οργανισμών δεικτών κοπρανώδους μόλυνσης, μελετήθηκε η επίδραση του αρχικού βακτηριακού πληθυσμού, η ένταση και το μήκος κύματος της ακτινοβολίας, η θερμοκρασία απολύμανσης και ο τρόπος παροχής του φωτός (συνεχής-ασυνεχής) κατά την διαδικασία. Μελετήθηκαν ακόμα τα φαινόμενα που λαμβάνουν χώρα μετά την ακτινοβολία, όπως το φαινόμενο της επανανάπτυξης του βακτηριακού πληθυσμού στο σκοτάδι, η φωτο-επιδιόρθωση και η επιβίωση των μικροοργανισμών σε φυσικά νερά μετά την ακτινοβολία. Διερευνήθηκε τέλος η δυνατότητα χρήσης αντιδραστήρων συνεχούς ροής με επανακυκλοφορία και ο συνδυασμός εφαρμογής προχωρημένων μεθόδων οξείδωσης (αντιδραστήριο photo-Fenton) με υπερήχους, στοχεύοντας στην ελαχιστοποίηση της πιθανότητας επανανάπτυξης των μικροοργανισμών. Τα αποτελέσματα κατέδειξαν ενδεδειγμένες πρακτικές εφαρμογής, συμπεράσματα για την καταλληλότητα της ηλιακής ακτινοβολίας ως μεθόδου απολύμανσης δευτεροβάθμια επεξεργασμένων λυμάτων, προβληματισμούς όσον αφορά τις τεχνικές λεπτομέρειες και περιβαλλοντικές ανησυχίες.Aquesta tesi tracta de la desinfecció d’un efluent secundari sintètic mitjançant llum solar en condicions controlades de laboratori, centrant-se en el recreixement dels bacteris després de la irradiació. La influencia de diversos factors interns i externs i el seu efecte en la desinfecció solar, així com la cinètica del recreixement bacterià són els temes estudiats. Amb l’ajuda d’un microorganisme indicador comú de contaminació fecal, es van investigar els efectes de la intensitat de la llum, de la temperatura, de la concentració inicial de bacteris, de l’energia lluminosa (longitud d’ona) i de la seva forma d’aplicació (contínua o intermitent). També es van estudiar els esdeveniments del posttractament, com son la reparació en foscor, la fotoreactivació i la supervivència en matrius naturals, així com l’ús de recursos tècnics (fotoreactors amb recirculació) i processos avançats d’oxidació (photo-Fenton i sonicació) per minimitzar el risc de recreixement. Els resultats obtinguts han permès formular conclusions valuoses sobre la idoneïtat d’utilitzar la radiació solar com a tècnica secundaria de desinfecció d’aigües residuals, indicant les limitacions de la seva aplicació, les consideracions sobre les especificacions del tractament i les seves perspectives ambientals.En la presente Tesis doctoral se estudia la desinfección solar de un efluente secundario sintético en condiciones controladas de laboratorio, centrándose en el recrecimiento bacteriano después del tratamiento de irradiación. La influencia de diversos factores tanto internos como externos y sus efectos sobre la desinfección solar, así como el recrecimiento bacteriano son el tema principal de esta investigación. Empleando un microorganismo indicador fecal común, se investigaron los efectos de la intensidad de la luz, la temperatura, la concentración bacteriana inicial, la energía de la luz (longitud de onda) y la forma de suministro (continua-intermitente). Asimismo, se evaluaron los eventos posteriores al tratamiento, tales como la reparación oscura, la fotorreactivación y la supervivencia en matrices acuosas naturales, así como el uso de medios técnicos (fotorreactores de flujo con recirculación) y procesos de oxidación avanzada (foto-Fenton y sonicación) para mitigar el riesgo de recrecimiento. Los hallazgos proporcionaron valiosos resultados, conclusiones referentes a las aplicaciones prácticas, conclusiones sobre la adecuación de la irradiación solar como técnica de desinfección de aguas residuales secundarias, con indicaciones a las limitaciones de su aplicabilidad, consideraciones sobre las especificaciones del tratamiento y sus perspectivas ambientale

Ultrasound enhancement of near-neutral photo-Fenton for effective E. coli inactivation in wastewater

In this study, we attempt for the first time to couple sonication and photo-Fenton for bacterial inactivation of secondary treated effluent. Synthetic wastewater was subjected to sequential high-frequency/low power sonication, followed by mild photo-Fenton treatment, under a solar simulator. It was followed by the assessment of the contribution of each component of the process (Fenton, US, hv) towards the removal rate and the long-term survival; sunlight greatly improved the treatment efficiency, with the coupled process being the only one to yield total inactivation within the 4-h period of treatment. The short-term beneficial disinfecting action of US and its detrimental effect on bacterial survival in long term, as well as the impact of light addition were also revealed. Finally, an investigation on the operational parameters of the process was performed, to investigate possible improvement and/or limitations of the coupled treatment; 3 levels of each parameter involved (hydraulic, environmental, US and Fenton) were tested. Only H2O2 increased improved the process significantly, but the action mode of the joint process indicated potential cost-effective solutions towards the implementation of this method. (C) 2014 Elsevier B.V. All rights reserved.Preprin

Detrimental vs. beneficial influence of ions during solar (SODIS) and photo-Fenton disinfection of E. coli in water: (Bi)carbonate, chloride, nitrate and nitrite effects

In this work, we studied the effect of inorganic ions occurring in natural waters on E. coli inactivation by solar and photo-Fenton processes, two crucial methods for drinking water treatment in sunny or developing countries. HCO−, Cl−, SO −, NO−, NO− 3 423 2 and NH+4 were assessed at relevant concentrations for their inhibiting or facilitating role. The inactivation enhancement during solar disinfection (SODIS) was mainly attributed to the generation of HO• radicals produced during by excitation of NO−3 , NO−2 , while the HO• of photo-Fenton may be transformed into other radical species in presence of ions. Natural organic matter (NOM) was found to enhance both processes but also to hinder most of the enhancing ions, except for NO−2 ; modeling with the APEX software unveiled the inter-relations in the presence of NOM, and the possible inactivation activity by NO2 . The photo-Fenton inactivation was more significantly enhanced by ions than SODIS (besides the case of NO−3 , NO−2 ), but both processes were found robust enough

Monitoring the post-irradiation E-coli survival patterns in environmental water matrices: implications in handling solar disinfected wastewater

In this study, simulated solar disinfection of secondary effluent was followed by dark storage at different temperatures or different receiving water matrices. Escherichia coil illumination was followed by 3-day monitoring of the bacterial population and its adaptation in different temperature conditions in the dark. The subsequent survival was linked to the dose received during exposure to light, and results were obtained on the environmentally induced prolongation of survival, maintenance of population or excessive growth, at 4 degrees C, 20 degrees C and 37 degrees C, respectively. An additional set of experiments at 20 degrees C was subjected to dilution in E. coli-free synthetic wastewater, water from Lake Leman, (synthetic) seawater and Mili-Q water. Post-irradiation monitoring was also conducted, studying 50%, 10% and 1% dilution rates, and the results were attributed to the two parameters of dilution medium and dilution ratio. However, different responses were found based on the acquired dose during pre-treatment. This indicates the importance of the illumination prior to storage, and the preference of bacteria in some matrices over the others. Survival was linked to initial population, dose, dilution and medium; shorter illumination times are to be considered according to the receiving water matrix. (C) 2014 Elsevier B.V. All rights reserved.Postprint (published version

Solar disinfection modeling and post-irradiation response of Escherichia coil in wastewater

In this work, an intensive assessment of solar disinfection of secondary wastewater was elaborated in controlled laboratory conditions. Batch tests of Escherichia coil-spiked synthetic secondary effluent, at nine different constant intensity levels, were followed by a 48-h dark storage. Solar disinfection was monitored in half-hourly intervals demonstrating distinct phases of lag followed by sharp inactivation. The results were fit to a shoulder log-linear and a Weibull distribution model. The solar-driven inactivation, the latency period and the effective disinfection time (for 4-log reduction) were correlated properly with the applied irradiance, resulting in a common, standardized dose for all intensities. Evolution of bacterial response in the dark was monitored for 48 h, and was in each case characterized as growth or decay. Also, the energy threshold, which was able to shift post-irradiation behavior from growth to decay, was analytically studied. In all intensity levels, this standard was approximately constant, as an effective bacteriostatic dose (EBD). Finally, similar dose-related disinfection and regrowth effects were observed, suggesting compliance with the reciprocity law, with minor deviations. (C) 2015 Elsevier B.V. All rights reserved

Elucidating bacterial regrowth: Effect of disinfection conditions in dark storage of solar treated secondary effluent

In this study, we systematically investigate solar disinfection of synthetic secondary wastewater, with the effort to decrypt the effects disinfection conditions have on post-irradiation bacterial regrowth in the dark. A full factorial design of 240 experiments was employed to investigate the effects of (i) exposure time (1, 2, 3 and 4 h), (ii) treatment temperature (20, 30, 40, 50 and 60 °C), (iii) initial bacterial concentration (10 3, 104, 105 and 106 CFU/mL) and (iv) sunlight intensity (0, 800 and 1200 W/m2) on Escherichia coli survival for a subsequent 48-h dark control period. The decisive implications treatment temperature inflicted in regrowth were monitored and interpreted within two temperature ranges, from 20 to 40 °C and 40 to 60 °C. In dark tests, bacterial populations presented initial moderate growths at 20-40 °C range, followed by intense regrowth. At 40-60 °C range, acute thermal inactivation without long-term regrowth predominated at 50 °C and was total at 60 °C, within the 4-h treatment period. Introduction of light resulted in higher removal rates or permanent inactivation for 800 and/or 1200 W/m 2, respectively. No post-treatment regrowth in the dark was observed after 24 and 48 h, in completely inactivated samples, and its demonstration, when observed, was well correlated to the bacterial numbers at the end of the disinfection period. Statistical observations on the transferred bacterial populations from day to day are also discussed in this paper

Solar disinfection is an augmentable, in situ-generated photo-Fenton reaction—Part 1: A review of the mechanisms and the fundamental aspects of the process

The present manuscript is a conceptual review concerning the photo-Fenton reaction at near-neutral pH, used for bacterial inactivation. In this first Part, an overview of the mechanisms involved, as well as the fundamental concepts governing the near-neutral photo-Fenton reaction are critically assessed. The two constituents of the process, namely solar light and the Fenton reagents, are dissociated, with their direct and indirect actions thoroughly analyzed. The effects of UVB and UVA on the bacterial cell are firstly discussed, followed by the presentation of the indirect oxidative stress-related inactivation mechanisms initiated into the microorganism, in presence of light. Afterwards, the effect of each Fenton reagent (H2O2, Fe) is analyzed in a step-wise manner, with H2O2 and Fe as enhancements of the solar disinfection mode of action. This approach proves that in fact, the solar photo-Fenton reaction is an enhanced solar disinfection process. Finally, the photo-Fenton reaction is put into context by considering the possible interactions of the separate parts of the combined process with the constituents of the natural environment that can play an important role in the evolution of the bacterial inactivation. (C) 2016 Elsevier B.V. All rights reserved