Feed Spacer Research Articles

Steady-state NH3-SCR global model and kinetic parameter estimation for NOx removal in diesel engine exhaust aftertreatment with Cu/chabazite

A steady-state global kinetic model for the NOx NH3-SCR reaction system, including NH3 oxidation, NO oxidation, standard SCR reaction, fast SCR reaction, NO2 SCR reaction, and N2O formation and decomposition is proposed, based on the Eley-Rideal formalism in which only ammonia is adsorbed and NO reacts directly from the gas phase. The experimental runs were designed under operational conditions simulating NO, NH3, NO2 feed stream composition near to the real application for NOx removal from diesel engine automobile exhaust aftertreatment. An initial set of 62 experiments, with only NO2 and NH3 in the feed stream allows a preliminary estimation of some kinetic parameters. Additional extensive experimentation up to 176 runs under a wide range of feed stream composition, temperature and space time was carried out. The experimental outlet NO, NH3, NO2 and N2O concentrations are analyzed for kinetic parameter estimation of seven reactions included in the proposed global NOx NH3-SCR system, resulting in activation energy values for standard SCR reaction, fast SCR reaction and NO2 SCR reaction of 91.5, 42.0, and 118kJmol−1, respectively. The proposed model resulted of high statistical significance deduced from the analysis of variance, with a determination coefficient of 0.952, and excellent F-test for a probability superior to 99%.

Determination of body width in brown and white layer pullets by image analyses

ABSTRACT1. Specific legal requirements for keeping pullets are not available in the European Union. However, two of the most important rearing factors for pullets are sufficient perching and feeder space. Both factors represent horizontal space dimensions which derive from the body width of the birds.2. The body width of two strains of layer pullets (brown (BL) and white (WL) layer pullets) based on the measurement of distances in digital images was conducted on front-view digital photographs of BL and WL pullets taken at 8, 12 and 19 weeks of life.3. Depending on live weight, age and body position, BL pullets measured an average body width between 10.70 ± 1.10 and 13.96 ± 1.11 cm. The width of WL pullets ranged from 10.30 ± 0.86 to 13.00 ± 1.14 cm.4. Compared with WL, BL pullets occupied more horizontal space during rearing. Age influenced the body width of BL and WL pullets at the end of rearing. The tested body positions of the pullets did not affect the measured body width.5. The biometric data obtained in this study are a useful basis for developing legal requirements for pullets, especially for defining minimum perch width and feeder space allowances.

Microalgal biomass dewatering using forward osmosis membrane: Influence of microalgae species and carbohydrates composition

The potential application of forward osmosis (FO) in microalgae dewatering requires an improved understanding of the factors that control membrane fouling which can reduce dewatering performance in terms of water flux through membrane and algae recovery. The aim of this study was to elucidate the influence of algae cell wall carbohydrate composition on the FO dewatering performance using three types of draw solutions (sea salts, MgCl2 and CaCl2). Experimental results suggest that the interaction between microalgae and back diffused draw solutes plays a key role. Scenedesmus obliquus with fructose and abundant glucose and mannose in its cell wall showed strong response to the back diffusion of calcium ions which encouraged S. obliquus to produce more extracellular carbohydrates and formed a stable gel network between algal biomass and extracellular carbohydrates, leading to algae aggregation and severe loss in both water flux and algae biomass during FO dewatering with Ca2+-containing draw solution. Chlamydomonas reinhardtii without fructose but great galactose showed a similar response to the calcium back diffusion but to a lower extent. Both S. obliquus and C. reinhardtii did not cause obvious membrane fouling but dramatic algae biomass loss at the end of FO filtration with MgCl2 draw solution due to their interaction with back diffused Mg2+ ions which led to the deposition of algae flocs onto membrane surface and/or feed spacer. Chlorella vulgaris without fructose was the most suitable microalgae species to be dewatered by FO with algae recovery over 81% and negligible flux decline regardless of which draw solution was applied. The findings improve mechanical understanding of FO membrane fouling by microalgae; have significant implications for the algae species selection; and are critical for the development and optimization of FO dewatering processes.

A review of heavy weight market pigs: status of knowledge and future needs assessment.

Marketing weight is an important economic variable that impacts the productivity and profitability of finishing pig production. Marketing weight has been increasing worldwide over the past decades driven by the dilution of fixed production cost over more weight per pig and the improvement of genetic selection of lean-type pigs. This review was aimed to summarize current knowledge and assess the future research needs on producing finishing pigs with marketing weight greater than 130 kg. Based on a thorough literature review, increasing marketing weight affected overall pig growth; in particular, cumulative average daily gain (ADG) decreased by 4.0 g, average daily feed intake (ADFI) increased by 78.1 g, and gain-to-feed ratio (G:F) decreased by 0.011 for every 10 kg increase of marketing weight. Increasing marketing weight by 10 kg increased carcass yield by 0.41% units, backfat by 1.8 mm, longissimus muscle (LM) area by 1.9 cm2, carcass length by 2.2 cm, and belly yield by 0.32% units, but decreased percentage of fat-free-lean by 0.78 units and decreased loin, shoulder, and ham yields by 0.13, 0.16, and 0.17% units, respectively. Studies that investigated the effects of marketing weight on pork quality observed decreased pH by 0.02 and 0.01 at 45 min and 24 h postmortem, respectively, and increased a* value by 0.28 per 10 kg marketing weight increase. Heavier market pigs had increased concentrations of saturated fatty acids and intramuscular fat. However, studies reported conflicting results for L* and b* values, drip loss, Warner-Bratzler shear force, and sensory properties of pigs in response to increasing marketing weight. A limited amount of research has been conducted to estimate nutrient requirements for pigs greater than 140 kg. Increased weight and size of heavy pigs can create challenges to farm and packer facilities and equipment. Discussions and recommendations are provided concerning the adjustments for floor and feeder space, barn design, ventilation, disease control, transportation, and carcass processing needed for increasing marketing weight. In conclusion, increasing marketing weight creates both opportunities and challenges to current finishing pig production, and future research is needed to provide nutritional and management guidelines and improve feed efficiency and meat quality of heavy weight market pigs.

Effect of floor on lameness in crossbred dairy Cow: a Review

Most walkways, milking parlor and feeding space in cattle houses are presently made up of concrete because it is durable, cheap and resistant to wear and hygienic. However, hard floor surface negatively affect hoof health and comfort, predisposes animal to pain and lameness and ultimately affect productivity. Lameness is world-widely reported as economically important disease. With the increased awareness for animal welfare provision of cushioned flooring in the animal house is gaining popularity. Providing soft rubber floor and sand bedding may be favorable for cow comfort, health, hygiene, and milk production. It probably reduces occurrence of lameness and mastitis in organized dairy farm. In this review attempt has been made to discuss dairy housing system in India, floors being used and problems associated with them. Further possibilities of alternative flooring have been explored.

Effect of ultrafiltration membranes properties and channel configuration on membrane fouling and performance

The work describes the existing views on colloidal, suspended and organic fouling in ultrafiltration (UF) membrane modules using for natural water treatment. The paper presents the results of the experimental research allowing for a quantitative determination of sorption and plugging rates, and for evaluation of their effect on membrane performance loss over time. Small colloidal particles pose a risk to UF unit due pore plugging; especially when membranes treat water with a very low content of suspended solids. This effect often cannot be detected during short-time pilot tests, but it can have a decisive influence on the operation of a membrane unit. Study of the filterability characteristic of water contaminants enables us to forecast the filtration type on UF membranes and to evaluate their performance losses. The paper also describes the effect of a feed channel structure – in particular, a presence of a feed spacer in spiral wound membrane modules – on channel hydraulic resistance growth. The technique of channel resistance estimation, depending on suspended particles concentration in the source water, is presented.

The effect of feed spacer geometry on membrane performance and concentration polarisation based on 3D CFD simulations

Feed spacers are used in spiral wound reverse osmosis (RO) membrane modules to keep the membrane sheets apart as well as to enhance mixing. They are beneficial to membrane performance but at the expense of additional pressure loss. In this study, four types of feed spacer configurations are investigated, with a total of 20 geometric variations based on commercially available spacers and selected filament angles. The impact of feed spacer design on membrane performance is investigated by means of three-dimensional (3D) computational fluid dynamics (CFD) simulations, where the solution-diffusion model is employed for water and solute transport through RO membranes. Numerical simulation results show that, for the operating and geometric conditions examined, fully woven spacers outperform other spacer configurations in mitigating concentration polarisation (CP). When designed with a mesh angle of 60°, fully woven spacers also deliver the highest water flux, although the associated pressure drops are slightly higher than their nonwoven counterparts. Middle layer geometries with a mesh angle of 30° produce the lowest water flux. On the other hand, spacers with a mesh angle of 90° show the lowest pressure drop among all the filament arrangements examined. Furthermore, the computational model presented here can also be used to predict membrane performance for a given feed spacer type and geometry.

Predicting the impact of feed spacer modification on biofouling by hydraulic characterization and biofouling studies in membrane fouling simulators

Feed spacers are an essential part of spiral-wound reverse osmosis (RO) and nanofiltration (NF) membrane modules. Geometric modification of feed spacers is a potential option to reduce the impact of biofouling on the performance of membrane systems. The objective of this study was to evaluate the biofouling potential of two commercially available reference feed spacers and four modified feed spacers. The spacers were compared on hydraulic characterization and in biofouling studies with membrane fouling simulators (MFSs). The virgin feed spacer was characterized hydraulically by their resistance, measured in terms of feed channel pressure drop, performed by operating MFSs at varying feed water flow rates. Short-term (9 days) biofouling studies were carried out with nutrient dosage to the MFS feed water to accelerate the biofouling rate. Long-term (96 days) biofouling studies were done without nutrient dosage to the MFS feed water. Feed channel pressure drop was monitored and accumulation of active biomass was quantified by adenosine tri phosphate (ATP) determination. The six feed spacers were ranked on pressure drop (hydraulic characterization) and on biofouling impact (biofouling studies). Significantly different trends in hydraulic resistance and biofouling impact for the six feed spacers were observed. The same ranking for biofouling impact on the feed spacers was found for the (i) short-term biofouling study with nutrient dosage and the (ii) long-term biofouling study without nutrient dosage. The ranking for hydraulic resistance for six virgin feed spacers differed significantly from the ranking of the biofouling impact, indicating that hydraulic resistance of clean feed spacers does not predict the hydraulic resistance of biofouled feed spacers. Better geometric design of feed spacers can be a suitable approach to minimize impact of biofouling in spiral wound membrane systems.

Investigation into the effectiveness of feed spacer configurations for reverse osmosis membrane modules using Computational Fluid Dynamics

Reverse osmosis operations for water treatment are usually energy intensive and responsible for most of the product price. Several studies used flow characteristics to compare different geometries of feed spacers, but these cannot completely explain the effectiveness of feed spacers for promoting mass transfer near membranes. A few recent studies introduced a concept (Spacer Configuration Efficacy, SCE) combining mass transfer and energy consumption, but SCE has been applied only to a limited extent.The present study uses 3-dimensional steady state Computational Fluid Dynamics with mass transfer to compare four channels with feed spacer configurations (Ladder-type, Triple, Wavy and Submerged) and an empty plain channel using SCE and other performance measures. In contrast to previous studies, a saturated concentration boundary condition is employed at the membrane surface and optimised meshing of the domain is discussed. Power law correlations for SCE and other performance measures developed from the simulation results enable quick evaluation of the spacers.Results indicated that the assumed saturated solute concentration at the membrane strongly affects the mass transfer coefficient. Based on SCE, the Wavy spacer configuration showed the highest performance for Re>120 among the obstructed geometries considered, while Ladder-type was better for Re<120.

The study of the effect of the concentration of propylene in the PPF to the liquid yield of the reaction

The results of the study of the effect of the concentration of propylene to propane-propylene fraction to a liquid yield of the reaction depending on the feed space velocity are presented.The results in the presence of a chromia-alumina catalyst in oxides of Ni, Co, Cr are examined.The optimal reaction conditions (Т-2800С, Voverall velocity 50-200 h-1), in which the liquid yield of the reaction was determined depending on the concentration of С3Н8 and С3Н6 in the raw feedstock, were set.

Effect of polyaromatic tars on the activity for methane steam reforming of nickel particles embedded in silicalite-1

The steam reforming of methane was studied over Rh and Ni-based catalysts exposed to naphthalene, which was used as a representative of polyaromatic tars found in biomass-derived biogas. In particular, two Ni-based samples in which part of the metal was encapsulated within silicalite-1 nanoboxes were tested. The reforming reaction was carried at 700, 800 and 900°C using a model feed and high space velocities to limit methane full conversion and better evidence any deactivation. A strong decrease of methane conversion was observed in the presence of 1400ppm of naphthalene, stressing the marked deleterious effect of this molecule in the present conditions. The effect of naphthalene was partly reversible, especially at higher temperatures. The silicalite-1 membrane could not prevent the deactivation of embedded nickel particles, probably because naphthalene (kinetic diameter=0.62nm) could diffuse throughout the MFI-type (pore diameter ca. 0.56nm) porous layer at the high reaction temperatures used. The effect of 5ppm of the bulkier pyrene (kinetic diameter=0.74nm) was investigated at 700°C and also led to a rapid deactivation of the Ni@silicalite-1, likely because pyrene was cracked into naphthalene, which could then enter the silicalite-1 nanoboxes. The poisoning effect of toluene on the Ni-based catalysts was minor in comparison to that induced by the polyaromatics. A marked sintering of the embedded Ni was also observed.

Spatially-resolved in-situ quantification of biofouling using optical coherence tomography (OCT) and 3D image analysis in a spacer filled channel

The use of optical coherence tomography (OCT) to investigate biomass in membrane systems has increased with time. OCT is able to characterize the biomass in-situ and non-destructively. In this study, a novel approach to process three-dimensional (3D) OCT scans is proposed. The approach allows obtaining spatially-resolved detailed structural biomass information. The 3D biomass reconstruction enables analysis of the biomass only, obtained by subtracting the time zero scan to all images. A 3D time series analysis of biomass development in a spacer filled channel under representative conditions (cross flow velocity) for a spiral wound membrane element was performed. The flow cell was operated for five days with monitoring of ultrafiltration membrane performance: feed channel pressure drop and permeate flux. The biomass development in the flow cell was detected by OCT before a performance decline was observed. Feed channel pressure drop continuously increased with increasing biomass volume, while flux decline was mainly affected in the initial phase of biomass accumulation.The novel OCT imaging approach enabled the assessment of spatial biomass distribution in the flow cell, discriminating the total biomass volume between the membrane, feed spacer and glass window. Biomass accumulation was stronger on the feed spacer during the early stage of biofouling, impacting the feed channel pressure drop stronger than permeate flux.

The effect of trough space and floor space on feeding and welfare of lambs in an intensive finishing system

This study examined the effects of floor space and feeder space on the feeding behaviour, growth and stress physiology of lambs, at different times, over a 6-week period in a finishing feedlot. A total of 640 lambs in four time replicates (160 lambs per replicate) were studied in four 40-lamb intensive finishing systems (feedlots) for 6 weeks over a 16-month period. The lambs were Merino wethers with live weight at the commencement of the experiment of 28.3 (s.d.=2.4)kg. The effects of two factors, pen floor space (2 and 5m2/lamb) and feed trough space (4 and 10cm/lamb) were examined in a factorial arrangement. Measurements taken on individual lambs during the experimental period included: feeding behaviour and displacements at the feeder in the feedlot during weeks 1, 2 and 6, lying behaviour during week 3, weekly live weights and cortisol concentrations in weeks 1 and 6. Weekly feed intake for each group of lambs was also record. Trough space of 4cm compared to 10cm per lamb reduced average lamb feed intake in all weeks of the 6-week period (a reduction of 1.2 (s.e.=0.53) kg/hd in week 1, 1.3 (s.e.=0.62)kg/hd in week 2, weekly average of 0.9 (s.e.=0.17)kg/hd over weeks 3–6; P=0.05, P=0.06 and P=0.0004, respectively). However, weight gain only differed significantly during the first week in the feedlot (average of 0.2 vs 1.1 (s.e.d.=0.35)kg for 4cm vs 10cm/lamb of provided trough space, P=0.03). At all observed times within the 6-week period, lambs with the reduced feed trough space spent less total time feeding (P<0.05) with less feeding bouts (P<0.05). There was no effect of feed trough space on lying time or cortisol concentrations. Floor space did not affect feeding and lying behaviour, feed intake, weight gain or cortisol concentrations. In conclusion, increasing feed trough space from 4 to 10cm/lamb increased feed intake and live weight gain through an increase in the number of feeding bouts and the total time feeding. This indicates that the trough space recommendations in the Australian Model Code of Practice (sheep) of 2cm/lamb are too low for maximum lamb feed intake and live weight. No effects of increasing floor space from 2 to 5m2/lamb were found, however the growth rates in general were low suggesting that the environment in the feedlot may have been sub-optimal.

Visualization of hydraulic conditions inside the feed channel of Reverse Osmosis: A practical comparison of velocity between empty and spacer-filled channel

It is widely accepted that our understanding about the membrane process increases by investigation of the hydraulic conditions of membranes. While numerical studies have been broadly used for this purpose, the experimental studies of a comparable resolution are scarce. In this study, we compared the pressure drop, the temporal and the spatial velocity maps of a spacer-filled channel and an empty channel of the same size to determine the effect of presence of the feeds spacer on hydraulic conditions. The velocity maps are obtained experimentally by using of the Particle Image Velocimetry (PIV) technique. Application of the feed spacer caused 2–8.5 higher pressure drop increase in the experimental conditions in this research. The flow had a spatial distribution in the form of a unimodal symmetric curve of normal distribution in the empty channel and a bimodal asymmetric curve in the spacer-filled channel. The bimodal curve indicates the presence of high- and low-velocity zones. Additionally, the low-velocity zones showed also a lower variation of velocity in time, which indicates the high fouling potential of these locations. The results from this study may be uses for validation of numerical studies.

Characterization of feed channel spacer performance using geometries obtained by X-ray computed tomography

Spiral-wound membrane modules used in water treatment for water reuse and desalination make use of spacer meshes for keeping the membrane leaves apart and for enhancing the mass transfer. Computational fluid dynamics (CFD) has gained importance in the design of new spacers with optimized hydrodynamic characteristics, but this requires a precise description of the spacer geometry. This study developed a method to obtain accurate three-dimensional (3-D) geometry representations for any given spacer design from X-ray computed tomography (CT) scans. The method revealed that the filaments of industrial spacers have a highly variable cross-section size and shape, which impact the flow characteristics in the feed channel. The pressure drop and friction factors were calculated from numerical simulations on five commercially available feed spacers used in practice. Model solutions compared well to experimental data measured using a flow cell for average velocities up to 0.2m/s, as used in industrial reverse osmosis and nanofiltration membrane operations. A newly-proposed spacer geometry with alternating strand thickness was tested, which was found to yield a lower pressure drop while being highly efficient in converting the pumping power into membrane shear. Numerical model solutions using CFD with geometries from CT scans were closer to measurements than those obtained using the traditional circular cross-section strand simplification, indicating that CT scans are very well suitable to approximate real feed spacer geometries. By providing detailed insight on the spacer filament shape, CT scans allow better quantification of local distribution of velocity and shear, possibly leading to more accurate estimations of fouling and concentration polarization.

Silica is preferred over various single and mixed oxides as support for CO2-assisted cobalt-catalyzed oxidative dehydrogenation of ethane

Catalysts containing 4.5wt% cobalt supported on single oxides of SiO2, Al2O3, TiO2 and ZrO2 and on mixed ones of SiO2-Al2O3, SiO2-TiO2, SiO2-ZrO2 and TiO2-ZrO2 were produced in a single step by flame spray pyrolysis and tested in the CO2-assisted oxidative dehydrogenation of ethane in a continuous fixed-bed microreactor. Structural and chemical properties of the nonporous catalysts were characterized by nitrogen adsorption, XRD, HR-TEM, EDXS, NH3-TPD, H2-TPR, TGA, DRIFTS, XPS and Raman and UV–vis spectroscopy. Depending on the supporting oxides the reducibility of the cobalt species varied in a broad range, indicating vastly different interaction of the cobalt species with the oxidic support. For catalysts supported on Al2O3 and SiO2-Al2O3 no significant H2 consumption was observed up to 840°C, while ZrO2-supported CoOx was already reduced at T <500°C. The silica-supported catalysts showed a broad reduction peak at ∼780°C attributed to well dispersed CoOx embedded in the SiO2 matrix forming cobalt silicate, consistent with HR-TEM, XPS and UV–vis analyses. Among all catalysts, silica-supported cobalt showed the best catalytic performance under the test conditions used (700°C with CO2/C2H6=2.5). Admixing Al2O3, TiO2 and ZrO2 to SiO2 did not result in improved catalytic performance. Reducibility of the CoOx species as well as the strength and surface density of acidic sites were identified as crucial catalyst properties for optimal ethene yield. Control of the surface acidity seems particularly important to avoid undesired side reactions (cracking, coking) impairing activity and selectivity. Parametric sensitivity studies of the silica supported cobalt catalyst, including reaction temperature, CO2/C2H6 feed ratio and space velocity, revealed the important role of CO2. In the absence of CO2, only low C2H6 conversion was observed and change of the oxidant to O2 resulted in poorer catalytic performance.

Features of non-oxidative conversion of methane into aromatic hydrocarbons over Mo-containing zeolite catalysts

The results of study of methane conversion under non-oxidative conditions over molybdenum containing zeolite catalysts prepared by solid-phase synthesis using nanosized molybdenum powder are presented. The kinetic mechanisms of the process behavior under different conditions of methane dehydroaromatization are determined. It is shown that nonoxidative conversion of methane can occur both in the external diffusion and kinetic regions, depending on the methane flow rate. It is found out, that the optimum temperature of the methane conversion is 750 °C. It is shown that increased methane conversion is observed at the feed space velocity of methane decreasing from 1500 to 500 h-1.

Spatial heterogeneity of biofouling under different cross-flow velocities in reverse osmosis membrane systems

The spatially heterogeneous distribution of biofouling in spiral wound membrane systems restricts (i) the water distribution over the membrane surface and therefore (ii) the membrane-based water treatment. The objective of the study was to assess the spatial heterogeneity of biofilm development over the membrane fouling simulator (MFS) length (inlet and outlet part) at three different cross-flow velocities (0.08, 0.12 and 0.16m/s). The MFS contained sheets of membrane and feed spacer and simulated the first 0.20m of spiral-wound membrane modules where biofouling accumulates the most in practice. In-situ non-destructive oxygen imaging using planar optodes was applied to determine the biofilm spatially resolved activity and heterogeneity.Comparison of the inlet and outlet position of the MFS showed a more (i) heterogeneous biofilm distribution and a (ii) higher biological activity at the inlet side (first 2.5cm) for all cross-flow velocities. The lowest cross-flow velocity had the highest biomass activity particularly at the inlet side. A better characterization of biofilm development, including the factors that influence the biofilm spatial heterogeneity in membrane systems with time, may help to develop effective strategies for biofouling control in membrane systems.

3D printing by selective laser sintering of polypropylene feed channel spacers for spiral wound membrane modules for the water industry

ABSTRACTFeed spacers are net-like structures present in spiral wound membrane modules (SWM) used for treatment of water and wastewater. Feed spacers require appropriate stiffness to support the membrane sheets without damaging and puncturing the membrane surfaces. They also need to be flexible enough to be rolled up around the central permeate tube forming the SWM. Polypropylene (PP) is the commercially used material for feed spacers due to its flexibility and excellent chemical resistance properties. In this paper, selective laser sintering (SLS) is used to investigate the printability of net-typed structures using PP materials to represent feed spacers. SLS processing parameters such as layer thickness, part bed temperature, energy density and scan pattern were studied and net-typed PP spacers were successfully fabricated. However, an analysis on tensile test and dimensional accuracy shows that Young’s modulus of the PP material tends to be correlated to the accuracy of the dimensions of the net-typed spacer prototypes.

Mini-review: novel non-destructive in situ biofilm characterization techniques in membrane systems

Membrane systems are commonly used in the water industry to produce potable water and for advanced wastewater treatment. One of the major drawbacks of membrane systems is biofilm formation (biofouling), which results in an unacceptable decline in membrane performance. Three novel in situ biofouling characterization techniques were assessed: (i) optical coherence tomography (OCT), (ii) planar optodes, and (iii) nuclear magnetic resonance (NMR). The first two techniques were assessed using a biofilm grown on the surface of nanofiltration (NF) membranes using a transparent membrane fouling simulator that accurately simulates spiral wound modules, modified for in situ biofilm imaging. For the NMR study, a spiral wound reverse osmosis membrane module was used. Results show that these techniques can provide information to reconstruct the biofilm accurately, either with 2-D (OCT, planar optodes and NMR), or 3-D (OCT and NMR) scans. These non-destructive tools can elucidate the interaction of hydrodynamics and mass transport on biofilm accumulation in membrane systems. Oxygen distribution in the biofilm can be mapped and linked to water flow and substrate characteristics; insights on the effect of crossflow velocity, flow stagnation, and feed spacer presence can be obtained, and in situ information on biofilm structure, thickness, and spatial distribution can be quantitatively assessed. The combination of these novel non-destructive in situ biofilm characterization techniques can provide real-time observation of biofilm formation at the mesoscale. The information obtained with these tools could potentially be used for further improvement in the design of membrane systems and operational parameters to reduce impact of biofouling on membrane performance.