Browsing by Author "Paissoni, Eleonora"

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    Anaerobic microbial core for municipal wastewater treatment — the sustainable platform for resource recovery
    (Elsevier, 2025-08-01) Conall Holohan, B.; Trego, Anna; Keating, Ciara; Bressani-Ribeiro, Thiago; Chernicharo, Carlos L.; Daigger, Glen; Galdi, Stephen M.; Knörle, Ulrich; Paissoni, Eleonora; Robles, Angel; Rogalla, Frank; Shin, Chungheon; Soares, Ana; Smith, Adam L.; Szczuka, Aleksandra; Hughes, Dermot; O’Flaherty, Vincent
    The requirement for carbon neutrality and bioresource recovery has shifted our views on water treatment from health and pollution avoidance to one of sustainability with water and nutrient circularity. Despite progress, the current process of wastewater treatment is linear, based on core aerobic microbiology, which is unlikely to be carbon neutral due to its large use of energy and production of waste sludge. Here, we outline a shift from aerobic to anaerobic microbiology at the core of wastewater treatment and resource recovery, illustrating the state-of-the-art technologies available for this paradigm shift. Anaerobic metabolism primarily offers the benefit of minimal energy input (up to 50% reduction) and minimal biomass production, resulting in up to 95% less waste sludge compared with aerobic treatment, which is increasingly attractive, given dialogue surrounding emerging contaminants in biosolids. Recent innovative research solutions have made ambient (mainstream) anaerobic treatment a ready substitute for the aerobic processes for municipal wastewater in temperate regions. Moreover, utilising anaerobic treatment as the core carbon removal step allows for more biological downstream resource recovery with several opportunities to couple the process with (anaerobic) nitrogen and phosphorus recovery, namely, potential mainstream anaerobic ammonium oxidation (anammox) and methane oxidation (N-DAMO). Furthermore, these technologies can be mixed and matched with membranes and ion-exchange systems, high-value biochemical production, and/or water reuse installations. As such, we propose the reconfiguration of the wastewater treatment plant of the futurewith anaerobic microbiology. Mainstream anaerobic treatment at the core of a truly sustainable platform for modern municipal wastewater treatment, facilitating circular economy and net-zero carbon goals.
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    Demonstration of anaerobic membrane bioreactors for resource recovery in wastewater treatment applications.
    (Cranfield University, 2023-08) Paissoni, Eleonora; Soares, Ana; Jefferson, Bruce
    Pilot-scale studies on anaerobic membrane bioreactors (AnMBRs) for municipal wastewater treatment at low temperature (<20°C) showed promising results, however, their application at larger scale is still relatively unknown. This study investigated the scalability of an AnMBR, comprising an upflow anaerobic sludge blanket (UASB) reactor and an external ultrafiltration membrane tank, operating AnMBRs both at pilot- and demonstration-scale and identifying how sludge physical and microbiological properties, membrane design and variations in influent temperature, chemical oxygen demand (COD) and sulphate (SO₄) influence the successful scale-up of the technology. At pilot-scale, the source and adaptation of the inoculum and the orientation and arrangement of the membrane fibres did not affect the performance of the reactors. However, the use of horizontal hollow fibres led to lower gas sparging energy consumption compared to a vertical module. The membrane improved removal efficiencies (from 49-57% to 88-92% COD removal), solids hydrolysed (from 0.82-0.86 g/(L∙d) to 1.57-1.87 g/(L∙d)) and methane production (from 2.3-2.7 L/d to 5.3-5.7 L/d). Methanogenesis percentages were linearly correlated to hydrolysis, which in turn was affected by temperature and inversely correlated to the Sauter mean diameter of the sludge particles. Higher substrate affinities were found at the operational temperature of the reactors (15-20°C), while hydrolytic enzyme activities in UASB reactors and AnMBRs were higher at 37°C. Methane was mainly dissolved in the effluent (70-90%), implying the need for a recovery process to improve the net energy balance. At demonstration-scale, low COD:SO4 ratio caused competition between sulphate-reducing bacteria and methanogens, leading to a decrease in methane yield. This study proved that AnMBRs are a suitable technology to treat municipal wastewater, however site- specific control strategies to manage fouling and sulphate and appropriate post- treatments are necessary to ensure the successful application of the process at full-scale in temperate climates and the recovery of useful resources from wastewater.
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    Dynamics of bubbles under stochastic pressure forcing
    (American Physical Society, 2021-02-23) Vesipa, Riccardo; Paissoni, Eleonora; Manes, Costantino; Ridolfi, Luca
    Several studies have investigated the dynamics of a single spherical bubble at rest under a nonstationary pressure forcing. However, attention has almost always been focused on periodic pressure oscillations, neglecting the case of stochastic forcing. This fact is quite surprising, as random pressure fluctuations are widespread in many applications involving bubbles (e.g., hydrodynamic cavitation in turbulent flows or bubble dynamics in acoustic cavitation), and noise, in general, is known to induce a variety of counterintuitive phenomena in nonlinear dynamical systems such as bubble oscillators. To shed light on this unexplored topic, here we study bubble dynamics as described by the Keller-Miksis equation, under a pressure forcing described by a Gaussian colored noise modeled as an Ornstein-Uhlenbeck process. Results indicate that, depending on noise intensity, bubbles display two peculiar behaviors: when intensity is low, the fluctuating pressure forcing mainly excites the free oscillations of the bubble, and the bubble's radius undergoes small amplitude oscillations with a rather regular periodicity. Differently, high noise intensity induces chaotic bubble dynamics, whereby nonlinear effects are exacerbated and the bubble behaves as an amplifier of the external random forcing
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    Hydrolytic enzyme activity in high-rate anaerobic reactors treating municipal wastewater in temperate climates
    (Elsevier, 2024-08-01) Paissoni, Eleonora; Jefferson, Bruce; Soares, Ana
    Particulate matter hydrolysis is the bottleneck in anaerobic treatment of municipal wastewater in temperate climates. Low temperatures theoretically slow enzyme-substrate interactions, hindering utilization kinetics, but this remains poorly understood. β-glucosidase, protease, and lipase activities were evaluated in two pilot-scale upflow anaerobic sludge blanket (UASB) reactors, inoculated with different sludges and later converted to anaerobic membrane bioreactors (AnMBRs). Despite similar methane production and solids hydrolysis rates, significant differences emerged. Specific activity peaked at 37 °C, excluding the predominance of psychrophilic enzymes. Nevertheless, the Michaelis-Menten constant (Km) indicated high enzyme-substrate affinity at the operational temperature of 15–20 °C, notably greater in AnMBRs. It is shown, for the first time, that different seed sludges can equally adapt, as hydrolytic enzymatic affinity to the substrate reached similar values in the two reactors at the operational temperature and identified that membrane ultrafiltration impacted hydrolysis by a favourable enzyme Michaelis-Menten constant.