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Den här undersökningen är den första i sitt slag där prestandanför använda luftare från svenska avloppsreningsverk har testats.Resultaten visar att både igensättning och åldrande av luftaresker på svenska reningsverk och resulterar i ökad elanvändningför luftning. Samtidigt finns det möjligheter med tillståndsbaseratunderhåll som kan minska den onödiga elanvändningen.Med ökande koldioxidutsläpp och ökande elpriser har energieffektivisering blivit viktigt,inte minst för att uppnå målet om en klimatneutral VA-bransch. I de kommunalaavloppsreningsverken kan luftning av de biologiska bassängerna stå för hälften avreningsverkets totala elanvändning. Internationella studier indikerar att upp till 40 % avdenna elanvändning är onödig och beror på igensättning och åldrande membran. Mende svenska erfarenheterna är begränsade. Att kunskapen är begränsad beror troligenpå att det inte är allmänt känt i VA-Sverige hur prestandan i luftningsanläggningar kanövervakas på bästa sätt, hur rengöring av luftare utförs och hur stor potentialen förbesparingar är. Projektet har undersökt olika membranluftare från sex svenska reningsverk i enspecialbyggd försöksanläggning med renvatten och analyserat deras syreöverföringseffektivitet(SOTE) och tryckfallet över luftarna (DWP).Till skillnad från tidigare studier skilde det här projektet på effekter av åldrande avmembranmaterialet och igensättning av membranen, vilket är avgörande för att kunnavälja rätt underhållsåtgärd. Två metoder för att övervaka luftarnas tillstånd implementeradespå projektdeltagarnas reningsverk. Även om det fanns vissa praktiska utmaningarmed implementeringen så visar resultaten att det är fullt möjligt att övervakaförändringar i SOTE och DWP, antingen genom direkta mätningar eller med beräkningarutifrån befintliga data.Resultaten från renvattenförsöken visade att igensättning framför allt påverkadeDWP (upp till 40 mbar ökning) som därför är en lämplig parameter att övervaka föratt optimera rengöringsintervallet. Åldran, In this study, the performance of aeration diffusers from Swedish wastewater treatmentplants were tested for the first time. The results showed that fouling as well asageing of diffusers occur at Swedish treatment plants which leads to increased electricityusage for aeration. At the same time, there are opportunities with condition-basedmaintenance that can reduce unnecessary electricity use.With increasing CO2 emissions and electricity prices, energy efficiency has becomeimportant, not least to achieve the goal of a climate-neutral VA industry. At the municipalwastewater treatment plants, aeration of the biological treatment basins typicallyaccounts for half of the treatment plant’s total electricity usage, and internationalstudies indicate that up to 40 % of this electricity is wastage due to fouling and ageingof membranes. But the Swedish experiences are limited. The limited knowledge islikely related to that it is not commonly known in the Swedish water sector how theperformance of aeration systems can best be monitored, how maintenance cleaningcan be done and how large the potential savings are. In the project, membrane diffusersfrom six Swedish treatment plants were tested in a purposely built test facilitywith clean water and analysed with respect to oxygen transfer efficiency (SOTE) anddynamic wet pressure (DWP). Unlike previous studies, the effects of ageing of themembrane material and fouling of the membranes were assessed separately, whichis crucial to choose the right mitigation action.Two methods for diffuser condition monitoring were implemented at treatmentplants within the participating organisations. Although there were some practicalchallenges with implementation, the results show that it is feasible to monitor changesin SOTE and DWP, either with direct measurements or calculations based on availabledata.The results from the clean water tests showed that fouling primarily affected DWP(up to 40 mbar increase) which is therefore a suitable parameter

A large decrease in permeability is often observed during the filtration of nano-sized colloids, while fouling is widely regarded as the main explanation for this phenomenon. The osmotic pressure or concentration polarization (CP) of colloids can also contribute to the flux decline. However, the contribution of CP to flux loss cannot be determined by the traditional CP model. In this study, the effect of fouling and CP/osmotic pressure on flux was distinguished. The CP values of polyethylene glycol (PEG) and silica-colloids were determined by the osmotic pressures near the membrane surface and in the feed. The CP induced by colloids accounted for 43–95% of the flux loss in our experiments. Silica exhibited higher CP values (127–460), compared to 7–71 for PEG. This was attributed to the slower back diffusion caused by the larger colloids, as evidenced by the diffusion coefficients of 4.30 × 10−11 m2/s for silica (10 nm) and 1.45 × 10−10 m2/s for PEG (2.9 nm). Although the CP was mitigated by increasing the cross-flow velocity, CP values of 31 and 250 were observed for PEG and silica at high Reynolds number of 7317, respectively. The experimentally obtained CP values were also compared with those calculated by the film diffusion model.

Forward osmosis (FO) membranes have potential for the efficient water and wastewater treatment applications. However, their development has faced significant challenges due to their fouling propensity. In this study, FO membranes modified with sulfobetaine zwitterions (i.e., [2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide) were fabricated and used for the first time to address microplastic (MP) fouling issue. Water flux, reverse salt flux (RSF), fouling, and flux recovery were evaluated for the membranes loaded with different quantities of the zwitterions ranging from 0.25 % to 2 %. The developed membranes were tested over 49 h with feed solutions containing polyethylene MPs and bovine serum albumin (BSA) to evaluate their fouling resistance. The synergistic effects of the two foulants indicated that the MPs were the primary cause of fouling. The presence of BSA effectively reduced the blocking effect of MPs and therefore lowers overall fouling. Additionally, improved water flux, structural parameter (S), and RSF were reported for the modified membranes. The zwitterion's unique structure with hydrophilic groups (C[dbnd]O and O[dbnd]S[dbnd]O) resulted in high flux recovery rates of over 90 % for all modified membranes within only 30 min of physical cleaning upon fouling tests. The results demonstrate the high potential of the modification method for targeting the removal of MPs in TFC-based membranes.

Marinas contribute to the degradation of coastal ecosystems, constitute non-indigenous species (NIS) hotspots and function as steppingstones in invasion processes. These often enclose highly modified water bodies that promote the concentration of pollutants and propagules, favoring NIS abundance. In these habitats, floating structures are often the most invaded by fouling NIS. This study aims to address the effect of floating substrate (buoys vs pontoons) on fouling assemblages, with special focus on NIS, in 6 marinas of Cadiz Bay during summer and winter seasons. Since the effect substrate type can depend on the water physicochemical conditions and environmental state and pressures of marinas, an environmental assessment was carried out for each marina using literature, physicochemical water measurements and environmental risk assessments. Despite the registered seasonal variation in fouling assemblages and the environmental variability among the studied marinas, the type of substrate played a key role in fouling assemblages' structure and abundance. The higher abundance of fouling assemblages in buoys than pontoons favor NIS prevalence in marinas and increase the risk of NIS dispersal, particularly considering that buoys are more likely to detach and drift at sea than pontoons. The results indicate that high-risk consideration should be given to this substrate type and that the potential environmental effects of biological pollution must be considered in risk assessments

Coral gardening is a reef restoration technique in which corals are first grown in nurseries and then outplanted onto degraded reefs. However, coral gardening does not yet achieve restoration at ecologically-relevant scales due to associated high costs. Coral nurseries are often manually cleaned to remove biofouling and improve coral performance, although putative benefits of this costly activity remain unconfirmed. We quantified the benefits and costs of various cleaning frequencies to identify the most cost-effective coral nursery approach at a study site with low herbivorous fish biomass. During this one-year study, nurseries were either cleaned weekly, monthly, quarter-yearly or never. Nurseries contained four coral species in three fragment sizes to examine species- and size-specific effects. Coral production (combined coral growth and fraction live coral tissue) and associated costs were quantified. No significant differences in coral production were found across cleaning frequencies and this result was consistent among coral species and fragment sizes. Therefore, no cleaning was clearly identified as the most cost-effective option. Costs could be further reduced by selecting fast-growing corals (e.g. Acropora) and stocking nurseries with large fragments, as these contributed most to coral production. The resulting minimum production cost is then US$0.26 per fragment including dive, wage and material costs for the building, deployment and filling of nurseries and sourcing of corals. For this study location and potentially many others with a similar or higher fish biomass, less frequent cleaning can substantially reduce reef restoration costs without having negative impacts on coral nursery production.

Desalination processes have the potential to significantly address the global water scarcity crisis. This is primarily because approximately 97% of water sources are saline or brackish, underscoring the importance of these processes. Solar-driven membrane distillation (MD) has garnered considerable attention in recent years among various solar-powered water treatment/desalination methods. This attention is due to its distinct advantages, such as operating at low temperatures, having a simple and compact design, the ability to treat highly saline water, requiring minimal membrane mechanical properties, and producing high-purity water. However, solar-driven MD systems face several significant challenges, including low gained-output-ratio (GOR), limited freshwater production, and relatively high water costs. Addressing these challenges requires a precise analysis of individual MD modules and solardriven MD systems. Among MD configurations, the direct contact membrane distillation module (DCMD) features as the most suitable for integration with solar energy. As the core component of solar-driven DCMD systems, analysing the performance of DCMD modules under various operational conditions can provide valuable insights to enhance system performance. Moreover, conducting accurate performance analyses of solar-driven DCMD systems and proposing strategies to improve their efficiency from both an energetic and economic perspective are essential tasks that must be undertaken. To achieve these objectives, this study leverages both experimental and machine learning methods. In terms of analysing the performance of DCMD modules, novel performance modelling tools were introduced to accurately diagnose their behaviour under various operational conditions. Machine learning models, including artificial neural network (ANN), support vector regression (SVR), and Random Forest (RF), were utilized to predict permeate flux with high accuracy. Comparative analysis demonstrated the superiori

In the present work, whey protein fouling phenomenon was studied, when fowed in the inner tube of a double tube heated by hot water which fows in the ring space between them. The fouling kinetics depends on the mass transfer effects, which is a function of protein solubility. To describe the fouling kinetics a calculus algorithm was developed, having as subsidy the protein solubility itself. The proteins solubility were determined in a separate investigation. Results showed that the time necessary for the tube´s inner radius to decrease in 30% of the original radius was smaller for high temperatures. Besides, whey protein deposition was greater at the tube´s entrance than in its exit. Therefore, the rate of radius reduction was faster in that area. The experimental check for the algorithm was conducted in a pilot plant., El presente trabajo es un estudio del fenómeno de incrustación de la proteína del suero de leche al interior de un intercambiador de calor por donde fuye agua caliente por entre los dos tubos. La cinética de incrustación depende de los efectos de la transferencia de masa, que es una función de la solubilidad de las proteínas. Para describir la cinética de incrustación de las proteínas se desarrolló un algoritmo de cálculo dependiente de la solubilidad. La solubilidad de la proteína fue determinada en una investigación por separado. Los resultados mostraron que el tiempo necesario para que el tubo de radio interior disminuyera en un 30% de la radio original fue menor para altas temperaturas. Además, la deposición de las proteínas de suero de leche fue más intensa en la entrada que en la salida. Por lo tanto, la tasa de reducción de radio fue más rápido en esa zona. El experimento para comprobar el algoritmo se llevó a cabo en una planta piloto.

The effect of chemical cleaning and regular backwashing on the efficiency of an ultrafiltration membrane fouled during stormwater treatment was studied. Increasing backwash time from 30 to 60 s resulted in an increase in productivity by 20%. However, the productivity was highest when a backwash time of 45 s was used (3% higher than using 60 s). Chemical cleaning was carried out using an alkaline solution (NaOH with or without NaOCl) followed by acid washing with HCl. The addition of NaOCl to the cleaning chemical did not significantly increase the efficiency of chemical cleaning, and the average pure water permeability increase was 97 ± 13 LMH bar−1 after chemical cleaning with NaOH followed by HCl and 117 ± 15 LMH bar−1 after chemical cleaning with NaOH + NaOCl followed by HCl, on average. In addition, reversibility after chemical cleaning was 96 ± 67%, on average. The result from scanning electron microscopy showed that at the end of the experiments, inorganic foulants existed in both the inner layer (feed side) and the outer layer (permeate side) of the membrane., Validerad;2024;Nivå 2;2024-03-15 (hanlid);Funder: DRIZZLE Center for Stormwater Management (2016-05176);License full text: CC BY 4.0

Reducing energy costs in Europe is more challenging than before due to extreme price increases. The use of local renewable energy sources is one way to contribute to this effort. In the case of spa resorts, the use of heat from hot springs for therapeutic baths is an option. It is necessary to cool down this thermal mineral water to a temperature acceptable to the human body. However, due to the high mineral content of this water, heavy fouling can be a problem for conventional heat exchangers. The purpose of this study is to identify the suitable cooling technology in terms of required cooling capacity and waste heat recovery capability. The cooling technology was selected on the basis of a literature search. A pilot cooling unit consisting of vacuum cooler and plate heat exchanger was designed and tested in a real spa resort for six months. Both selected technologies have demonstrated the ability to cool thermal mineral water in long-term operation, as well as the possibility to utilize waste heat for domestic hot water heating. However, fouling problems occur in the plate heat exchanger. The vacuum cooler demonstrated greater operational robustness and resistance to encrustation.

Reducing energy costs in Europe is more challenging than before due to extreme price increases. The use of local renewable energy sources is one way to contribute to this effort. In the case of spa resorts, the use of heat from hot springs for therapeutic baths is an option. It is necessary to cool down this thermal mineral water to a temperature acceptable to the human body. However, due to the high mineral content of this water, heavy fouling can be a problem for conventional heat exchangers. The purpose of this study is to identify the suitable cooling technology in terms of required cooling capacity and waste heat recovery capability. The cooling technology was selected on the basis of a literature search. A pilot cooling unit consisting of vacuum cooler and plate heat exchanger was designed and tested in a real spa resort for six months. Both selected technologies have demonstrated the ability to cool thermal mineral water in long-term operation, as well as the possibility to utilize waste heat for domestic hot water heating. However, fouling problems occur in the plate heat exchanger. The vacuum cooler demonstrated greater operational robustness and resistance to encrustation.

A polymeric ultrafiltration (UF) membrane was used for stormwater treatment, with the focus on evaluating the increase in the membrane process productivity by adding pulsatile fluid flow to UF membrane treatment. Sedimentation and sieving were used as pre-treatment. The result showed that increasing the pulse frequency from 0 to 4 Hz increased productivity from -6.6 to 82 LMH. UF membrane removed suspended solids, oil and turbidity below detection limit. The UF membrane also separated total coliforms, E. coli and P. aeruginosa below detection limit. Total organic carbon (TOC) was reduced by between 70 and 91%. In addition, the UF membrane was able to reduce BOD7 and COD to below 7 mg/L in the permeate. According to the US EPA, WHO, and national regulations in Canada, Japan, and South Korea, treated stormwater can be used for flushing toilets and streets irrigation and agricultural use.

Reducing energy costs in Europe is more challenging than before due to extreme price increases. The use of local renewable energy sources is one way to contribute to this effort. In the case of spa resorts, the use of heat from hot springs for therapeutic baths is an option. It is necessary to cool down this thermal mineral water to a temperature acceptable to the human body. However, due to the high mineral content of this water, heavy fouling can be a problem for conventional heat exchangers. The purpose of this study is to identify the suitable cooling technology in terms of required cooling capacity and waste heat recovery capability. The cooling technology was selected on the basis of a literature search. A pilot cooling unit consisting of vacuum cooler and plate heat exchanger was designed and tested in a real spa resort for six months. Both selected technologies have demonstrated the ability to cool thermal mineral water in long-term operation, as well as the possibility to utilize waste heat for domestic hot water heating. However, fouling problems occur in the plate heat exchanger. The vacuum cooler demonstrated greater operational robustness and resistance to encrustation.

Marinas are hubs for non-indigenous species (NIS) and constitute the nodes of a network of highly modified water bodies (HMWB) connected by recreational maritime traffic. Floating structures, such as pontoons, are often the surfaces with higher NIS abundance inside marinas and lead the risk for NIS introduction, establishment and spread. However, there is still little information on how the location within the marina and the substratum type can influence the recruitment of fouling assemblages depending on water parameters and substratum chemical composition. In this study, fouling recruitment was studied using an experimental approach with three materials (basalt, concrete and HDPE plastic) in two sites (close and far to the entrance) in two marinas of Madeira Island (NE Atlantic, Portugal). The structure of benthic assemblages after 6- and 12-months colonization, as well as biotic abundance, NIS abundance, richness, diversity, assemblages' volume, biomass and assemblages' morphology were explored. Differences between marinas were the main source of variation for both 6- and 12-month assemblages, with both marinas having different species composition and biomass. The inner and outer sites of both marinas varied in terms of structure and heterogeneity of assemblages and heterogeneity of morphological traits, but assemblages did not differ among substrata. However, basalt had a higher species richness and diversity while concrete showed a higher bioreceptivity in terms of total biotic coverage than the rest of materials. Overall, differences between and within marinas could be related to their structural morphology. This study can be valuable for management of urban ecosystems, towards an increase in the environmental and ecological status of existing marinas and their HMWB and mitigation coastal ecosystems degradation.

Ecosystem engineers are organisms that cause changes in the physical state of biotic and abiotic structures that modulate the availability of resources to other species, thus affecting biochemical cycles. Molluscs, especially bivalves such as mussels, are widespread in coastal environments and they are excellent ecosystem engineers because of the durability of their shells, which add complexity and heterogeneity to benthic environments. The presence of mussel farms favours the accumulation of shells in benthic environments and may influence surrounding bare sediments, with potential legacy effects on benthic communities. We studied the effects of the accumulation of mussel shells at finfish farms and mussel farms by experimentally comparing bare sediment and sediment with fragmented shells in terms of the abundance of the most relevant faunal groups, specifically polychaete families as well as physical–chemical variables in sediment water samples, specifically organic matter (OM), redox potential, and acid-volatile sulphides (AVS) NH4+ and PO43−. The experiment was replicated under two environmental conditions over a period of 35 days: eutrophic muddy sediments and oligotrophic sandy sediments. The OM and AVS values were significantly higher in the eutrophic sediment with mussel shells. Only NH4+ was positively affected by the mussel shells in the oligotrophic conditions. Differences between the two environments were observed, and the effect of the mussel shells on the polychaete assemblages was more significant in the oligotrophic conditions. Mussel shell accumulations affected the structure of benthic assemblages by modifying their heterogeneity and complexity, which suggests that the presence of mussel farms above bare sediment may affect ecosystem functioning. Aquaculture has potentially negative or positive effects that must be addressed on a large scale, considering the increased input of organic matter and also the simultaneous presence of mussel shell waste

The main bottleneck in the treatment and reuse of effluents from deinking paper mills that employ reverse osmosis (RO) is the high silica content, which causes membrane fouling that limits the recovery of the treatment. Silica removal with magnesium compounds enables to treat large volumes of water with high removal efficiencies at low cost. Although soluble magnesium compounds are efficient, their use is limited since they increase the conductivity in the treated waters. Therefore the use of sparingly soluble magnesium compounds might be a promising alternative. Three sparingly soluble magnesium compounds (MgO, Mg(OH)2 and (MgCO3)4•Mg(OH)2•5H2O) were studied in this paper at three pHs (10.5, 11.0 and 11.5) and five dosages (250-1500 mg/L) at ambient temperature (~20ºC). Only 40% silica removal was obtained, which is not high enough to work at regular RO recoveries without scaling problems. To increase silica removal, the slurries of sparingly soluble compounds were pre-acidified with concentrated sulphuric acid and tested at the same conditions. In this case, high removal rates were obtained (80-86%) at high pH (11.5), even at ambient temperature. These removal rates would allow working at 75-80% recovery in RO units without scaling problems. This pre-acidification, together with the use of Ca(OH)2 as pH regulator limited the increase of the conductivity of the treated waters to only 0.2 mS/cm. Additionally, the use of Ca(OH)2 instead of NaOH as pH regulator increased the chemical oxygen demand removal from 15% to 25%., Comunidad de Madrid, Ministerio de Educación, Unión Europea. FP7, Depto. de Ingeniería Química y de Materiales, Fac. de Ciencias Químicas, TRUE, pub

This study investigates experimental temperature data with particular attention to (i) uncertainty (between different test runs) and the (ii) time-resolved variability (in the transient start-up and steady state operation phase) in a fixed bed, laboratory-scale (biomass) combustors with secondary air staging at different. Temperatures measured from up to four zones are analysed: the packed fuel bed, freeboard (primary LI, secondary LII) and/or exhaust stack (fouling module). The study finds that peak bed temperatures have relatively low experimental uncertainty, while uncertainty in freeboard temperatures varies more widely. Additionally, experimental uncertainty (across all conditions) is notably low, does not exceed 5.00%, and does not appear to be zone specific (packed bed to exhaust stack). In comparison, time-resolved temperature variability can be zone specific at some conditions even within steady-state operation phase. The paper offers valuable insights for biomass combustion testing particularly when multiple runs are needed to collect fouling deposits over different air staging ratios.

Heat pump systems are a key technology towards the decarbonisation of district heating systems as they can leverage renewable energy sources and industrial excess heat. Large-scale heat pumps are prone to a variety of faults related to the heat source. Heat exchanger fouling is one of the most common types of faults, which corresponds to the undesired deposition of material on heat transfer surfaces. This fault can be mitigated by the use of different cleaning procedures such as cleaning-in-place. The optimization of the time interval between cleaning periods requires the estimation of the effects of fouling on the heat pump performance, which are often difficult to determine. The present study proposes a framework for online monitoring of a large-scale heat pump affected by evaporator fouling based on a quasi-steady-state simulation model. Model parameters related to the heat transfer coefficients and fouling were repeatedly adjusted by means of a dynamic calibration approach. The framework retrieved operational data from a cloud-based data management system and leveraged existing sensors and controllers in the heat pump. The results indicated that fouling had a larger effect on the thermal resistance than on the pressure drop in the evaporator. The framework also allowed to identify the extent to which a cleaning-in-place system enabled to reduce the evaporator thermal resistance caused by fouling. Overall, the results from the proposed framework showed its potential to describe the operation of the heat pump and to determine the effects of fouling on a real-time basis.

Early fouling warning is important for the economical operation of membrane separation systems. In parallel multi-channel flow systems, flow re-distribution between channels due to fouling is often associated with maloperation. In the current research we use low magnetic field NMR to monitor multi-fiber hollow fiber membrane modules undergoing a fouling-cleaning cycle and show that rapid detection of fouling is possible by detecting the loss of signal coherence associated with flow re-distribution within the 401 hollow fiber membrane module. This effect is demonstrated to be both reproducible, and reversible via membrane cleaning. The results demonstrate a strong correlation between the coherence signal magnitude and the number of fibers fouled. This may be used in practice for high sensitivity early warning, and to monitor the efficiency of cleaning. This approach may also be particularly useful in the case of detecting residual fouling after cleaning, evidenced in this research by significant flow re-distribution between the before fouling and after cleaning signal coherence., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., BT/Environmental Biotechnology

Increasingly, ecological rehabilitation is envisioned to mitigate and revert impacts of ocean sprawl on coastal marine biodiversity. While in the past studies have demonstrated the positive effects of artificial fish habitats in port areas on fish abundance and diversity, benthic colonization of these structures has not yet been taken into consideration. This could be problematic as they may provide suitable habitat for Non-Indigenous Species (NIS) and hence facilitate their spreading. The present study aimed to examine communities developing on artificial fish habitats and to observe if the number of NIS was higher than in surrounding equivalent habitats. The structures were colonized by communities that were significantly different compared to those surrounding the control habitat, and they were home to a greater number of NIS. As NIS can cause severe ecological and economical damages, our results imply that in conjunction with the ecosystem services provided by artificial fish habitats, an ecosystem disservice in the form of facilitated NIS colonization may be present. These effects have not been shown before and need to be considered to effectively decide in which situations artificial structures may be used for fish rehabilitation.

Dataset used in the publication "Evaluation of chemical free cleaning techniques for RED fed with natural waters and stacks with profiled membranes". This dataset contains data collected during experiment for cleaning techniques in reverse electrodialysis (RED) using natural waters. For explanation of the experimental setup we refer you to the published paper. It is being made public both to act as supplementary data for publication and in order for other researchers to use this data in their own work.

During the processing of insects for food and feed applications, thermal treatments are often used for decontamination purposes. However, these treatments denature proteins comprising their functional properties. Milder methods for microbiological decontamination can be used, such as microfiltration. Therefore, in this study dead-end microfiltration (0.2 µm polyethersulphone membrane) was tested for decontamination of soluble fractions of lesser mealworms and house crickets obtained at pH values of 3 and 8. The results showed that dead-end microfiltration was successful in the removal of microorganisms (total viable count), removing the need for thermal treatments for the permeates. Protein recovery in the permeate was relatively low (14–43 %). Lesser mealworms at pH 3 gave the highest protein recovery in the permeate (43 %), as explained by the activity of endogenous proteases producing soluble peptides during microfiltration. Confocal imaging showed that the efficiency of microfiltration was reduced by membrane fouling caused by protein aggregation. The presence of lipids in the pre-filtrate does not hamper the permeate protein recovery. In conclusion, dead-end microfiltration with a 0.2 µm membrane is successful in achieving microbial stability. A pH of 3 is recommended during the extraction process to obtain a higher protein recovery.

Given the potential hazards of microplastics (MPs), it is desirable to efficiently remove them during wastewater treatment processes. To this end, ultrafiltration (UF) membranes can significantly increase the removal of MPs, however the fouling of such membrane modules can also be impacted by the presence of MPs. Magnetic Resonance Imaging (MRI) was used here to non-invasively quantify the effect of polyethylene (PE) MPs accumulation in a 3D UF hollow fiber (HF) membrane module containing 400 fibers, via direct non-invasive velocity imaging of the flow distribution between individual fibers during module operation. The co-effect of MPs and alginate (a common organic model foulant mimicking extracellular polymeric substances (EPS)) on fouling of the HF module was then explored. Flow was initially equally distributed with fouling causing flow in particular fibers to be significantly reduced. Fouling with MPs resulted in minimal flow distribution disruption and was easily remediated hydraulically, in contrast alginate fouling required chemical cleaning in order to fully restore homogeneous flow distribution between the fibers. The presence of both MPs and alginate resulted in a more heterogeneous disruption of the fibre flow distribution due to fouling and resulted in much more effective hydraulic cleaning of the module.

Green infrastructure drainage systems are innovative treatment units that capture and treat stormwater. Unfortunately, highly polar contaminants remain challenging to remove in conventional biofilters. To overcome treatment limitations, we assessed the transport and removal of stormwater vehicle-related organic contaminants with persistent, mobile, and toxic (in short: PMTs) properties, such as 1H-benzotriazole, NN'-diphenylguanidine, and hexamethoxymethylmelamine (PMT precursor), using batch experiments and continuous-flow sand columns amended with pyrogenic carbonaceous materials, like granulated activated carbon (GAC) or wheat-straw derived biochar. Our results indicated that all investigated contaminants were subjected to nonequilibrium interactions in sand-only and geomedia-amended columns, with kinetic effects upon transport. Experimental breakthrough curves could be well described by a one-site kinetic transport model assuming saturation of sorption sites, which we inferred could occur due to dissolved organic matter fouling. Furthermore, from both batch and column experiments, we found that GAC could remove contaminants significantly better than biochar with higher sorption capacity and faster sorption kinetics. Hexamethoxymethylmelamine, with the lowest organic carbon-water partition coefficient (KOC) and largest molecular volume among target chemicals, exhibited the lowest affinity in both carbonaceous adsorbents based on estimated sorption parameters. Results suggest that sorption of investigated PMTs was likely driven by steric and hydrophobic effects, and coulombic and other weak intermolecular forces (e.g., London–van der Waals, H-bonding). Results from extrapolating our data to a 1-m depth geomedia-amended sand filter suggested that GAC and biochar could enhance the removal of organic contaminants in biofilters and last for more than one decade. Overall, our work is the first to study treatment alternatives for NN'-diphenylguanidine and, Water Resources

Computational Fluid Dynamics (CFD) is a powerful tool which can help with the geometry optimization of continuous milli-scale reactors, which often are highly complex devices. Attempting to perform this optimization by manually modifying and testing geometry configurations can however be tedious and computationally inefficient. Addressing this problem, we present a framework in which the CFD software COMSOL Multiphysics is coupled with the multi-objective Bayesian Optimization algorithm TSEMO (Thompson sampling efficient multiobjective optimization), implemented in MATLAB. The mixing element geometry of a Miprowa Lab millireactor is parameterized, and the framework automatically executes CFD simulations to minimize areas of stagnating flow and maximize the mixing performance. The framework is able to find Pareto-optimal reactor variations, and can easily be adapted for other devices and objectives., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., ChemE/Product and Process Engineering

With the gradual increase of microplastics (MPs) in water and wastewater streams, it is imperative to investigate their removal using tertiary treatment systems to minimize and preferably prevent their entrance into aquatic environments. Forward osmosis (FO) is a non-pressurized membrane process with potential applications in MPs removal from wastewater. However, efficient application of FO systems relies on developing high-performance FO membranes with low fouling tendency. MPs are proven as emerging foulants in membrane systems, diminishing their performance and lifetime and this highlights the need to consider MP fouling in developing sustainable membranes. The current study focuses on a novel modification of thin film composite (TFC) FO membranes by MIL-53(Fe) as a water-stable and hydrophilic metal-organic framework. Experimental results demonstrated that the optimized FO membrane (0.2 wt% MIL-53(Fe)) achieved a significantly higher water flux (90% increase) with a 23% less reverse salt flux. The modified membrane also had significantly less flux decline in fouling experiments and higher flux recovery after physical cleaning compared to the control membrane affirming its higher antifouling efficiency. MIL-53(Fe) integration in the FO substrate proved to be a practical method for developing high-performance TFC FO membranes with improved antifouling properties against MPs and organic foulants.

Green infrastructure drainage systems are innovative treatment units that capture and treat stormwater. Unfortunately, highly polar contaminants remain challenging to remove in conventional biofilters. To overcome treatment limitations, we assessed the transport and removal of stormwater vehicle-related organic contaminants with persistent, mobile, and toxic (in short: PMTs) properties, such as 1H-benzotriazole, NN'-diphenylguanidine, and hexamethoxymethylmelamine (PMT precursor), using batch experiments and continuous-flow sand columns amended with pyrogenic carbonaceous materials, like granulated activated carbon (GAC) or wheat-straw derived biochar. Our results indicated that all investigated contaminants were subjected to nonequilibrium interactions in sand-only and geomedia-amended columns, with kinetic effects upon transport. Experimental breakthrough curves could be well described by a one-site kinetic transport model assuming saturation of sorption sites, which we inferred could occur due to dissolved organic matter fouling. Furthermore, from both batch and column experiments, we found that GAC could remove contaminants significantly better than biochar with higher sorption capacity and faster sorption kinetics. Hexamethoxymethylmelamine, with the lowest organic carbon-water partition coefficient (KOC) and largest molecular volume among target chemicals, exhibited the lowest affinity in both carbonaceous adsorbents based on estimated sorption parameters. Results suggest that sorption of investigated PMTs was likely driven by steric and hydrophobic effects, and coulombic and other weak intermolecular forces (e.g., London-van der Waals, H-bonding). Results from extrapolating our data to a 1-m depth geomedia-amended sand filter suggested that GAC and biochar could enhance the removal of organic contaminants in biofilters and last for more than one decade. Overall, our work is the first to study treatment alternatives for NN'-diphenylguanidine and hexamethoxymet

The zooxanthellate coral Oculina patagonica (Scleractinia, Oculinidae) is an invasive species that was first recorded in the Mediterranean Sea in 1966 and currently has expanded its distribution across both the western and eastern Atlantic. Here, we reviewed data from multiple databases to compile historical distribution records of O. patagonica and analyze its spread. The chronological review highlights the unique spread of this zooxanthellate coral during the last two decades, expanding its distribution in multiple directions and establishing populations in disjunct regions separated by ~12,000 km, including most biogeographic regions within the temperate Mediterranean, the subtropical eastern Atlantic and the tropical Gulf of Mexico. The biogeographic distribution discontinuities documented in O. patagonica are difficult to explain by larval dispersion alone; therefore, other mechanisms may contribute to its large-scale spread pattern. This study provides the first observation of several O. patagonica colonies fouling the hull and metal crevices of a recreational boat in the western Mediterranean (37°N, 1°W). The presence of several mature O. patagonica colonies on a single ship, rather than a single coral colony rafting on natural or artificial floating substrates, could greatly increase its potential for spread, coupled with its ecological and biological traits adapted to rafting. We hypothesized that the travel of coral populations by shipping may act as a dispersal vector contributing to explaining the long-distance dispersal events and secondary introductions experienced by this invasive species. The broad spread of O. patagonica, which is able to drive phase shifts from macroalgae dominance to coral dominance, is consistent with the ongoing process of coral-mediated tropicalization of high-latitude shallow rocky reefs under current global change

Acid whey (AW), a by-product from the production of acidified dairy products, contains high amounts of lactic acid and minerals that can be recovered by electrodialysis (ED). To better understand the process and improve its efficiency, the objective of this study was to investigate fouling of ion-exchange membranes (IEMs) during ED of AW and concentrated AW by reverse osmosis (ROAW), underlimiting (ULCD), limiting (LCD) and overlimiting current density operating conditions (OLCD). The structure, hydrophobicity, and chemical composition of membranes showed differences regarding fouling on anion- (AEM) and cation- (CEM) exchange membranes facing the diluate and the concentrate, both for AW and ROAW. Furthermore, operating at OLCD tends to reduce fouling compared to ULCD, due to the expected generation of electroconvective vortices. 2D fluorescence spectroscopy and Fourier-transform infrared spectroscopy (FTIR) provided complementary and more detailed information regarding the fouling and efficiency of the cleaning procedure. The 2D fluorescence spectra showed that the AEM surfaces in contact with the diluate change more than those in contact with the concentrate. The FTIR analyses showed the presence of lactose and lactic acid on the AEM surfaces in contact with the concentrate, which could not be detected by fluorescence.

The power demand from gas turbines in electrical grids is becoming more dynamic due to the rising demand for power generation from renewable energy sources. Therefore, including the transient data in the fault diagnostic process is important when the steady-state data are limited and if some component faults are more observable in the transient condition than in the steady-state condition. This study analyses the transient behaviour of a three-shaft industrial gas turbine engine in clean and degraded conditions with consideration of the secondary air system and variable inlet guide vane effects. Different gas path faults are simulated to demonstrate how magnified the transient measurement deviations are compared with the steady-state measurement deviations. The results show that some of the key measurement deviations are considerably higher in the transient mode than in the steady state. This confirms the importance of considering transient measurements for early fault detection and more accurate diagnostic solutions.

Reverse Electrodialysis (RED) has shown to be a promising technology for electricity production but membrane fouling can influence the energy yield, thus, it is crucial to gain knowledge on the impact and prevention of fouling. We used a sequence of pre-treatments (dual-media filter, microfilter and activated carbon filter) to fractionate foulants in seawater based on size and investigated its effect on RED. Fouling reversibility was studied by applying a cleaning procedure with reversal and increased flow and air sparging at the end of the experiment. After 63 days of operation, when using only the dual-media filter as pre-treatment, the pressure drop increased by 520 mbar in the seawater compartments without affecting the electrochemical measurements. The application of the cleaning procedure allowed to recover 90 % of the pumping power losses. A membrane autopsy showed the development of a biofilm layer on the membrane of the stacks receiving the most treated water while it was not detected when only the dual-media filter was used, which showed that the presence of particulate matter could help limit biofouling development. Together with the performance recovery, we concluded that the application of the dual media filtration system is a suitable and cost effective pre-treatment for RED.

Marinas contribute to the degradation of coastal ecosystems, constitute non-indigenous species (NIS) hotspots and function as steppingstones in invasion processes. These often enclose highly modified water bodies that promote the concentration of pollutants and propagules, favoring NIS abundance. In these habitats, floating structures are often the most invaded by fouling NIS. This study aims to address the effect of floating substrate (buoys vs pontoons) on fouling assemblages, with special focus on NIS, in 6 marinas of Cadiz Bay during summer and winter seasons. Since the effect substrate type can depend on the water physicochemical conditions and environmental state and pressures of marinas, an environmental assessment was carried out for each marina using literature, physicochemical water measurements and environmental risk assessments. Despite the registered seasonal variation in fouling assemblages and the environmental variability among the studied marinas, the type of substrate played a key role in fouling assemblages' structure and abundance. The higher abundance of fouling assemblages in buoys than pontoons favor NIS prevalence in marinas and increase the risk of NIS dispersal, particularly considering that buoys are more likely to detach and drift at sea than pontoons. The results indicate that high-risk consideration should be given to this substrate type and that the potential environmental effects of biological pollution must be considered in risk assessments.