Browsing by Author "Pidou, Marc"
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Item Open Access Ammonia recovery and utilisation for biogas upgrading in membrane contactors.(Cranfield University, 2023-07) Luqmani, Benjamin A.; McAdam, Ewan; Pidou, MarcThis thesis has developed an innovative system for biogas upgrading using hollow fibre membrane contactors (HFMC) whilst recovering ammonia from wastewater as a reactive solvent to intensify CO₂ absorption. An expanded two- phase region for ammonia-water separation was identified and exploited to foster selective, low energy recovery of concentrated gas-phase ammonia from wastewater by vacuum thermal stripping. Selective stripping was translated to a gas-liquid contacting column which demonstrated mass transfer rates analogous to commercially established stripping processes. Investment in selective ammonia recovery from anaerobic digester centrate represents a cost saving over a 20-year economic lifetime relative to biological nitrogen removal. During physical CO₂ absorption in HFMC, solvent chilling and gas pressurisation were observed to increase flux and selectivity, thereby reducing membrane area and path length for biogas upgrading. Chilled conditions will promote wetting resilience to favour the application of microporous membranes, which are low- cost and technologically mature. Translation to recovered ammonia solvents will further intensify CO₂ absorption, but can result in gas-side reactions within the ternary CO₂-NH₃-H₂O system which reduce process stability. In a positive synergy, chilled, pressurised conditions could limit ammonia ‘slip’ and maintain the system below a critical threshold to prevent gas-side reactions and improve process resilience. Pressurised, reactive crystallisation in HFMC during CO₂ absorption by ammonia solvents was demonstrated for the first time, and observed to occur at a consistent supersaturation level. Consequently, ammonium bicarbonate crystals exhibited consistent characteristics independent of pressure which supports simplified online control and solids recovery for scale- up. The integrated system proposed in this thesis presents a cost effective, circular economy solution for ammonia recovery and biogas upgrading which is closely aligned to net zero ambitions within the water sector and wider society.Item Open Access Anaerobic co-digestion of sewage sludge and trade wastes: beneficial and inhibitory effects of individual constituents(MDPI, 2023-02-08) Berzal de Frutos, Olivia; Götze, Martin; Pidou, Marc; Bajón Fernández, YadiraAnaerobic digestion (AD) of sewage sludge can be optimised by adding trade wastes (TWs) because of their nutrient content and boost in biogas formation if non-inhibitory. However, some components in TWs might have an inhibitory impact, such as nitrogen compounds, sulphate, heavy metals, metalloids, halogens and organic pollutants (e.g., phenol). This study aimed to understand the impact of TWs on the co-digestion with sewage sludge to identify appropriate TW loads for sustainable AD operation. The composition of 160 TWs was evaluated and the constituents with potential to cause inhibition or toxicity were tested in bio-methane potential (BMP) tests. The compounds studied in BMP tests included ammonia, zinc, copper, aluminium, mercury, arsenic, chloride, sulphate and nitrate. An improvement was observed at concentrations 2–746 mg Zn/L, 1066–2821 mg Cl/L as zinc sulphate and sodium chloride in biogas production, and 2–746 mg Zn/L, 162 mg SO4/L, 25 mg Hg/L as zinc sulphate, sodium chloride and mercury sulphate in methane production, respectively. Considering the TWs characterised and the results of the BMP tests, a volumetric ratio of 10/90 of TWs and sewage sludge is proposed as a suitable feedstock for co-digestion.Item Open Access Anaerobic Membrane Bioreactors for water reuse using municipal wastewater: the role of post-treatment(Cranfield University, 2022-07) Huang, Yu; Pidou, Marc; Jeffrey, PaulAnaerobic Membrane Bioreactors (AnMBRs) are seen as a promising alternative to Aerobic Membrane Bioreactor (AeMBR) based water reuse schemes as they better support a circular economy paradigm with the potential for recovery of energy and nutrients. However, evidence of their application for water reuse is very limited which significantly restricts their potential deployment. This research aimed to identify the current challenges of using AnMBRs for water reuse with respect to their ability to achieve the quality requirements in state of the art national and regional standards. The work investigates the performance and feasibility of technologies commonly applied as a post-treatment stage for AeMBRs and ultimately to provide references for possible treatment trains for future water reuse implementations. A critical review and controlled pilot scale AnMBR and AeMBR operations followed by lab-scale post-treatment trials were conducted to understand the performance of the investigated post-MBR processes and their potential role in AnMBR based water reuse applications. The distinctive matrices of AnMBR and AeMBR effluents, in particular the different nitrogen species as ammonia in the AnMBR effluent and nitrate in the AeMBR effluent, were found to influence different performance across the investigated post-MBR technologies. The presence of ammonia caused a higher membrane fouling and a potential failure to meet the standard for potable reuse during the RO filtration of the AnMBR effluent. When chlorinated, the AnMBR effluent provided a controllable residual ammonia and chlorine concentration while exhibiting lower disinfection by-products formation potential compared to the AeMBR effluent. UV/TiO₂ delivered a selective removal of organic and nutrient compounds as a function of varying the UV intensity and TiO₂ dose from the AnMBR effluent. These findings highlight the potential to combine these processes to achieve more sustainable treatment trains producing high quality effluents for various water reuse applications. In particular, the combination of AnMBR-Chlorination shows promise as a circular economy approach to municipal wastewater treatment for agriculture irrigation.Item Open Access Biofouling and scaling control of reverse osmosis membrane using one-step cleaning - potential of acidified nitrite solution as an agent(Elsevier, 2015-08-17) Filloux, Emmanuelle; Wang, Jingshi; Pidou, Marc; Gernjak, Wolfgang; Yuan, ZhiguoBiofouling is generally regarded as a major issue in reverse osmosis (RO) membrane filtration. Two-step chemical cleanings with alkaline and acidic agents are typically applied to restore the treatment capacity. In this study, the feasibility of one-step cleaning using free nitrous acid (FNA) was investigated as a novel low cost cleaning agent. The FNA cleaning solution was prepared by acidification of a sodium nitrite solution with hydrochloric acid. Seven fouled RO membranes collected from full-scale wastewater recycling and desalination plants were used to perform lab-scale cleaning trials. Membrane fouling characterisation revealed six of out of seven membranes were mainly bio-fouled, while one membrane was severely fouled by calcium carbonate. This study showed the feasibility of using FNA at pH 3.0 for biomass removal as well as for calcium carbonate scaling removal. The results from the lab-scale cleaning tests suggested that FNA can be used as a single cleaning agent for both biofouling and scaling removal. Cost analysis showed that FNA is a cost-effective solution for biofouling and scaling removal in RO filtration applications.Item Open Access Characterisation of blackwater from human transportation systems equipped with vacuum toilets and controlled emissions tanks and its impact on solid/liquid separation technologies(Elsevier, 2024-09) Jadhav, N.; Brown, Tim; Williams, Leon; Pidou, MarcThe first ever detailed characterisation of blackwater from human transportation systems equipped with vacuum toilets and Controlled Emissions Tanks (CET) revealed a stream that is very concentrated in salts and nutrients when compared to other blackwater sources. Escherichia Coli (E. coli) levels in the blackwater characterised were comparatively lower than the range reported for septic tanks, for example. Suspended solids were significantly lower than the levels found in pit latrines, but closely comparable to those reported for gravity toilets. The average COD of 3566 ± 2049 mg/L was typically lower than in pit latrines and gravity flush toilets. These findings then show that the characteristics of the blackwater from human transportation systems are directly impacted by a combination of the low flush vacuum toilets, storage in the CET, and different behaviour for passengers with increased usage for urination over defecation when compared to common uses of toilets. Such factors collectively dictate the nature of the blackwater and require that a solid/liquid separation technology for further processing is fundamentally robust in operation. The greater solids pulverisation, largely resulting from vacuum flushing combined with the storage environment, reduces the suitability of centrifugal and settling technologies whilst making filtration the most suitable option.Item Open Access Chemically reactive membrane crystallisation reactor for CO2–NH3 absorption and ammonium bicarbonate crystallisation: Kinetics of heterogeneous crystal growth(Elsevier, 2019-11-22) Bavarella, Salvatore; Brookes, Adam; Moore, Andrew; Vale, Peter C. J.; Di Profio, Gianluca; Curcio, Efrem; Hart, Phil; Pidou, Marc; McAdam, Ewan J.The feasibility of gas-liquid hollow fibre membrane contactors for the chemical absorption of carbon dioxide (CO2) into ammonia (NH3), coupled with the crystallisation of ammonium bicarbonate has been demonstrated. In this study, the mechanism of chemically facilitated heterogeneous membrane crystallisation is described, and the solution chemistry required to initiate nucleation elucidated. Induction time for nucleation was dependent on the rate of CO2 absorption, as this governed solution bicarbonate concentration. However, for low NH3 solution concentrations, a reduction in pH was observed with progressive CO2 absorption which shifted equilibria toward ammonium and carbonic acid, inhibiting both absorption and nucleation. An excess of free NH3 buffered pH suitably to balance equilibria to the onset of supersaturation, which ensured sufficient bicarbonate availability to initiate nucleation. Following induction at a supersaturation level of 1.7 (3.3 M NH3), an increase in crystal population density and crystal size was observed at progressive levels of supersaturation which contradicts the trend ordinarily observed for homogeneous nucleation in classical crystallisation technology, and demonstrates the role of the membrane as a physical substrate for heterogeneous nucleation during chemically reactive crystallisation. Both nucleation rate and crystal growth rate increased with increasing levels of supersaturation. This can be ascribed to the relatively low chemical driving force imposed by the shift in equilibrium toward ammonium which suppressed solution reactivity, together with the role of the membrane in promoting counter-current diffusion of CO2 and NH3 into the concentration boundary layer developed at the membrane wall, which permitted replenishment of reactants at the site of nucleation, and is a unique facet specific to this method of membrane facilitated crystallisation. Free ammonia concentration was shown to govern nucleation rate where a limiting NH3 concentration was identified above which crystallisation induced membrane scaling was observed. Provided the chemically reactive membrane crystallisation reactor was operated below this threshold, a consistent (size and number) and reproducible crystallised reaction product was collected downstream of the membrane, which evidenced that sustained membrane operation should be achievable with minimum reactive maintenance intervention.Item Open Access Chemically reactive membrane crystallisation reactor for CO₂ separation and ammonia recovery.(2018-10) Bavarella, Salvatore; McAdam, Ewan; Pidou, MarcThis thesis introduces an integrated system comprised of a thermal stripper and a hollow fibre membrane contactor (HFMC) for concentration of ammonia (NH₃ ) from wastewater and control of chemically mediated membrane crystallisation of ammonium bicarbonate (NH₄HCO₃ ) to enable simultaneous ammonia removal, biogas upgrading (through carbon dioxide, CO₂, separation), fertilizer production and harvesting within a single and economical process. In particular, recirculation of a refrigerated aqueous ammonia absorbent within the chemically reactive membrane crystallisation reactor (CR-MCr), demonstrated to reduce free ammonia introduction into the gas phase and convert NH₃ into non-volatile ammonium (NH₄+), thus preventing gas side crystallisation, which leads to process blockage, and promoting liquid side crystallisation of NH₄HCO₃ . The thermodynamic and kinetics of the CO₂-NH₃ -H₂O system have also been investigated to facilitate shell-side (liquid side) crystallisation of the ammonium salt within the CR-MCr. A transition from large (PTFE) to tight (PP) membrane pore size material obviated wetting and enabled consistent and reproducible NH₄HCO₃ crystallisation on the membrane-liquid interface. The X-ray diffraction analysis of the crystals produced with the absorbent recovered from return liquor, indicated the products to be reasonably pure ammonium bicarbonate, which evidenced the reduction in cationic competition through application of pre-treatment. A comparison between batch and membrane crystallisation kinetics demonstrated the hydrophobic fibre to underpin primary heterogeneous nucleation in an unseeded supersaturated solution and laminar regime, decoupled from secondary nucleation and growth, which mainly occur in the bulk downstream, contrarily to batch crystallisation where primary and secondary homogeneous nucleation are followed by growth and agglomeration, promoted by enhanced mixing and CO₂ bubbling, within the same environment. As a result, an increasing population density at raising levels of supersaturation has been observed in the first case, against a declining population density vs. supersaturation in the latter. A slower pH transient in membrane crystallisation, compared with conventional batch operation, could be balanced by raising the membrane-liquid interfacial surface area, which would increase the nucleation rate, whilst the yield of ammonia removal could be maximised up to 99% (ammonium bicarbonate solubility limit) through an increase in absorbent pH, which would eliminate the partial conversion of solute (bicarbonate) into carbonic acid, caused by a dynamic reaction zone, therefore closing the gap to control nucleation and growth in membrane crystallisation of ammonium bicarbonate.Item Open Access CO2 absorption into aqueous ammonia using membrane contactors: Role of solvent chemistry and pore size on solids formation for low energy solvent regeneration(Elsevier, 2022-03-16) Bavarella, Salvatore; Luqmani, Benjamin A. ; Thomas, Navya; Brookes, Adam; Moore, Andrew; Vale, Peter C. J.; Pidou, Marc; McAdam, Ewan J.Solids formation can substanitally reduce the energy penalty for ammonia solvent regeneration in carbon capture and storage (CCS), but has been demonstrated in the literature to be difficult to control. This study examines the use of hollow fibre membrane contactors, as this indirect contact mediated between liquid and gas phases in this geometry could improve the regulation of solids formation. Under conditions comparable to existing literature, NH4HCO3 was evidenced to primarily crystallise in the gas-phase (lumen-side of the membrane) due to the high vapour pressure of ammonia, which promotes gaseous transmission from the solvent. Investigation of solvent reactivity demonstrated how equilibria dependent reactions controlled the onset of NH4HCO3 nucleation in the solvent, and limited ‘slip’ through transfomation of ammonia into its protonated form which occurs prior to the phase change. Crystallisation in the solvent was also dependent upon ammonia concentration, where sufficient supersaturation must develop to overcome the activation energy for nucleation. However, this has to be complemented with a reduction in solvent temperature to offset vapour pressure and limit the risk of gas-phase crystallisation. While changes to the solvent chemistry were sufficient to shift from gas-phase to liquid phase crystallisation, wetting was observed immediately after nucleation in the solvent. This was explained by a local region of supersaturation within the coarse membrane pores that promoted a high nucleation rate, altering the material contact angle of the membrane sufficient for solvent to breakthrough into the gas phase. Adoption of a narrower pore size membrane was shown to dissipate wetting after crystallisation in the solvent, illustrating membrane contactors as a stable platform for the sustained separation of CO2 coupled with its simultaneous transformation into a solid. Through resolving previous challenges experienced with solids formation in multiple reactor configurations, the cost benefit of using ammonia as a solvent can be realised, which is critical to enabling economically viable CCS for the transition to net zero, and can be exploited within hollow fibre membrane contactors, eliciting considerable process intensification over existing reactor designs for CCS.Item Open Access A comparative evaluation of reverse osmosis membrane performance when combined with anaerobic or aerobic membrane bioreactors for indirect potable reuse applications(Elsevier, 2022-11-18) Huang, Yu; Jeffrey, Paul; Pidou, MarcThe filtration performance and fouling behaviour of reverse osmosis (RO) membranes was investigated for the post-treatment of aerobic (Ae) and anaerobic (An) MBR effluents treating municipal wastewater for potable reuse. Both MBR effluents followed by RO can produce a water quality sufficient for indirect potable water reuse, while fluorescence excitation-emission scan suggests RO can effectively remove disinfection by-products precursors, ensuring the safety for chlorine based reuse water distribution by rejecting the dissolved organic matters in MBR effluents. AnMBR effluent leads to more fouling when compared to the AeMBR effluent with an average membrane fouling resistance of 12.35 × 1013 m−1 and 8.97 × 1013 m−1. Elemental analysis and membrane surface imaging results demonstrate that the foulant deposition sequence is organic and colloidal at first, followed by inorganic substances, while TOC and Ca are the most deposited foulants from both effluents. The unremoved ammonia in the AnMBR effluent may partially go through in the RO permeate and exceed the threshold in Singapore's PUB NEWater standard, while experiencing a significantly higher deposition rate of 13.8 % than the nitrate (0.02 %) from the AeMBR effluent. The findings suggest that the combination of AnMBR with RO offers a more sustainable approach than with the AeMBR but nutrients removal, with the potential of recovery, is recommended before the RO membranes to limit the fouling propensity and achieve a permeate of sufficient quality.Item Open Access Comparison of coagulation performance and floc properties using a novel zirconium coagulant against traditional ferric and alum coagulants(Elsevier Science B.V., Amsterdam., 2012-09-03T00:00:00Z) Jarvis, Peter; Sharp, Emma; Pidou, Marc; Molinder, Roger; Parsons, Simon A.; Jefferson, BruceCoagulation in drinking water treatment has relied upon iron (Fe) and aluminium (Al) salts throughout the last century to provide the bulk removal of contaminants from source waters containing natural organic matter (NOM). However, there is now a need for improved treatment of these waters as their quality deteriorates and water quality standards become more difficult to achieve. Alternative coagulant chemicals offer a simple and inexpensive way of doing this. In this work a novel zirconium (Zr) coagulant was compared against traditional Fe and Al coagulants. The Zr coagulant was able to provide between 46 and 150% lower dissolved organic carbon (DOC) residual in comparison to the best traditional coagulant (Fe). In addition floc properties were significantly improved with larger and stronger flocs forming when the Zr coagulant was used with the median floc sizes being 930 υm for Zr; 710 υm for Fe and 450 υm for Al. In pilot scale experiments, a similar improved NOM and particle removal was observed. The results show that when optimised for combined DOC removal and low residual turbidity, the Zr coagulant out-performed the other coagulants tested at both bench and pilot scaItem Open Access Consequences of pH change on wastewater depth filtration using a multimedia filter(Elsevier, 2017-10-21) Ncube, Philani; Pidou, Marc; Stephenson, Tom; Jefferson, Bruce; Jarvis, PeterDifferent media materials in a multimedia filter have the potential to trap particles of different characteristics dependent on the media-suspension particle interactions. However, the removal of particles from wastewater secondary effluent using granular media filtration is relatively poorly understood because of the complexity of the wastewater matrix. Often the wastewater treatment process is liable to undergo pH changes due to removal or addition of chemicals in the treatment chain or from biological instability which in turn may alter the wastewater characteristics. Wastewater contains a mixture of organic and inorganic components, dissolved or particulate which may influence the aggregation and deposition of suspension solids during depth filtration. Changes in wastewater pH has the potential to change the wastewater matrix and media surface properties hence affecting aggregation and deposition in wastewater filtration. This study investigated how pH change affects wastewater filtration by monitoring zeta potential, aggregation and deposition of solids. The wastewater and filter media were also characterised over a range of pH from 1 to 13. Aggregation and deposition of wastewater solids was found to be most efficient near neutral pH. This was not concurrent with the conditions of lowest net charge in the system.Item Open Access Data for the paper "Influence of light regime on the performance of an immobilised microalgae reactor for wastewater nutrient removal"(Cranfield University, 2019-10-31 18:14) Whitton, Rachel; Ometto, Francesco; Villa, Raffaella; Pidou, Marc; Jefferson, BruceWastewater nutrient remediation data using immobilised microalgae under differing light regimes including wavelength (nm), duty cycles and photoperiods (on:off cycles), light transmittance and attenuation depths.Item Open Access Data for the paper "What is the impact of personal care products selection on grey water characteristics and reuse?"(Cranfield University, 2020-05-27 19:59) Le Corre Pidou, Kristell; Jeffrey, Paul; Jefferson, Bruce; Pidou, MarcThis unique study explores the question as to whether consumers’ product selection could affect the treatability and reuse of bathroom greywater. Fifty five personal care and household products (PCHP) were analysed for their effects on a range of water quality parameters including their aquatic and soil toxicity using Microtox® and MicroRespTM. Data used in the manuscript are compiled in the attached data file. Material and methods used to generate the data can be found in the manuscriptItem Open Access Data related to "Examining disruptive gas-phase reactions during CO2 capture in membrane contactors: CO2-NH3-H2O as a model ternary system"(Cranfield University, 2024-05-23 17:10) Luqmani, Benjamin A. ; Pidou, Marc; McAdam, EwanData related to figures for "Examining disruptive gas-phase reactions during CO2 capture in membrane contactors: CO2-NH3-H2O as a model ternary system"Item Open Access Data related to "The role of solvent temperature and gas pressure on CO2 mass transfer during biogas upgrading within porous and dense-skin hollow fibre membrane contactors"(Cranfield University, 2023-04-14 14:37) Luqmani, Benjamin A. ; McAdam, Ewan; Pidou, MarcSource data for published works: 'The role of solvent temperature and gas pressure on CO2 mass transfer during biogas upgrading within porous and dense-skin hollow fibre membrane contactors'.Item Open Access Data related to figures from "Transitioning through the vapour-liquid equilibrium for low energy thermal stripping of ammonia from wastewater..."(Cranfield University, 2023-04-21 14:29) Luqmani, Benjamin A. ; Pidou, Marc; McAdam, EwanSupporting dataset related to figures in the following work : "Transitioning through the vapour-liquid equilibrium for low energy thermal stripping of ammonia from wastewater...".Item Open Access Data supporting: 'CO2 absorption into aqueous ammonia using membrane contactors: Role of solvent chemistry and pore size on solids formation for low energy solvent regeneration'(Cranfield University, 2022-10-13 16:42) Bavarella, Salvatore; Luqmani, Benjamin A.; Thomas, Navya; Brookes, Adam; Moore, Andrew; Vale, Peter C. J.; Pidou, Marc; McAdam, EwanSolids formation can substantially reduce the energy penalty for ammonia solvent regeneration in carbon capture and storage (CCS), but has been demonstrated in the literature to be difficult to control. This study examines the use of hollow fibre membrane contactors, as this indirect contact mediated between liquid and gas phases in this geometry could improve the regulation of solids formation. Adoption of a narrower pore size membrane was shown to dissipate wetting after crystallisation in the solvent, illustrating membrane contactors as a stable platform for the sustained separation of CO2 coupled with its simultaneous transformation into a solid. Through resolving previous challenges experienced with solids formation in multiple reactor configurations, the cost benefit of using ammonia as a solvent can be realised, which is critical to enabling economically viable CCS for the transition to net zero, and can be exploited within hollow fibre membrane contactors, eliciting considerable process intensification over existing reactor designs for CCS.Item Open Access Demonstrating commercial hollow fibre membrane contactor performance at industrial scale for biogas upgrading at a sewage treatment works(MDPI, 2021-01-13) Houlker, Sam; Rutherford, Tony; Herron, Daniel; Brookes, Adam; Moore, Andrew; Vale, Peter C. J.; Pidou, Marc; McAdam, Ewan J.Hollow fibre membrane contactor (HFMC) technology has been developed for CO2 absorption primarily using synthetic gas, which neglects the critical impact that trace contaminants might have on separation efficiency and robustness in industrial gases. This study, therefore, commissioned a demonstration-scale HFMC for CO2 separation at a full-scale anaerobic digester facility to evaluate membrane integrity over six months of operation on real biogas. The CO2 capture efficiency identified using real biogas was benchmarked at comparable conditions on synthetic gas of an equivalent partial pressure, and an equivalent performance identified. Two HFMC were subsequently compared, one with and one without a pre-treatment stage that targeted particulates, volatile organic compounds (VOCs) and humidity. Similar CO2 separation efficiency was again demonstrated, indicating limited impact within the timescale evaluated. However, gas phase pre-treatment is advised in order to ensure robustness in the long term. Over longer-term operation, a decline in CO2 separation efficiency was observed. Membrane autopsy identified shell-side deposition, where the structural morphology and confirmation of amide I and II groups, indicated biofouling. Separation efficiency was reinstated via chemical cleaning, which demonstrated that proactive maintenance could minimise process risk.Item Open Access The effect of high hydraulic loading rate on the removal efficiency of a quadruple media filter for tertiary wastewater treatment(IWA Publishing, 2016-10-24) Ncube, Philani; Pidou, Marc; Stephenson, Tom; Jefferson, Bruce; Jarvis, PeterIt is well known that filtration removal efficiency falls with an increase in flow rate; however, there is limited supporting experimental data on how removal efficiency changes for filters with multiple layers of media and for wastewater filtration, a practice that is becoming more common. Furthermore, information is not available on the characteristics of particles that are removed at different flow rates. Here, a quadruple media filter was operated at hydraulic loading rates (HLRs) between 5 and 60 mh−1 with subsequent measurement of total suspended solids, turbidity and particle size distribution (PSD). Samples were collected from the filter influent, effluent and also from between media layers. Pressure changes across the filter layers were also measured. The solids removal efficiency of the filter varied inversely with the increase in filtration rate. However, the multiple media layers reduced the negative impact of increased HLR in comparison to a single media filter. High filtration rates were shown to transport solids, such that particle retention and headloss development was distributed across the entire depth of the multi-media filter. There was also a progressive decrease in the suspension particle size leaving each of the filter layers. The particle hydrodynamic force simulation was consistent with the changes in measured PSD through the filter layers.Item Open Access Energy recovery from immobilised cells of Scenedesmus obliquus after wastewater treatment(Springer, 2017-05-05) Gomez San Juan, Marta; Ometto, F.; Whitton, Rachel; Pidou, Marc; Jefferson, Bruce; Villa, RaffaellaBiomethane batch test of alginate beads and beads with algae at different stages of utilisation in the wastewater treatment plants showed that immobilised S. obliquus yield similar biogas and biomethane than freely suspended algae (between 60.51 ± 4.19 and 82.32 ± 2.17 mL g-1 VSadd) and that a pre-treatment stage was not necessary for the digestion process.