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13 pages, 1276 KB

Open AccessArticle

Zero-Valent Iron and Sand Filtration Reduces Levels of Cyclospora cayetanensis Surrogates, Eimeria tenella and Eimeria acervulina, in Water

by Alan Gutierrez, Matthew S. Tucker, Christina Yeager, Valsin Fournet, Mark C. Jenkins, Jitender P. Dubey, Kalmia E. Kniel, Benjamin M. Rosenthal and Manan Sharma

Microorganisms 2024, 12(11), 2344; https://doi.org/10.3390/microorganisms12112344 - 16 Nov 2024

Cited by 1 | Viewed by 1389

Abstract

Recurring outbreaks of cyclosporiasis linked to fresh produce demonstrate the need to develop interventions to reduce C. cayetanensis in irrigation water. C. cayetanensis is resistant to commonly used irrigation water treatments, such as chemical sanitizers, making removal of oocysts by filtration the most [...] Read more.

Recurring outbreaks of cyclosporiasis linked to fresh produce demonstrate the need to develop interventions to reduce C. cayetanensis in irrigation water. C. cayetanensis is resistant to commonly used irrigation water treatments, such as chemical sanitizers, making removal of oocysts by filtration the most suitable intervention. This study evaluated the reduction of Eimeria tenella and E. acervulina, as surrogates for C. cayetanensis, in water using filters packed with sand alone or mixtures of sand and zero-valent iron (ZVI). Water inoculated with Eimeria spp. oocysts was filtered through laboratory-scale (PVC column) and field-scale (swimming pool filter) filters packed with either 100% sand or 50% ZVI/50% sand (v/v). Filtered and backflush water was examined microscopically for oocysts. Laboratory-scale filters with 50% ZVI significantly (p < 0.05) reduced 99.9% of E. tenella oocysts compared to 55.3% with filters containing 100% sand. At the field-scale level, 50% ZVI filters significantly (p < 0.05) reduced 70.5% of E. acervulina oocysts compared to 54.5% by 100% sand filters. Filters were backflushed to examine the recovery of these parasites during routine filter-media cleaning procedures. Backflush recovery of oocysts ranged from 4.42–16.7%. The addition of ZVI significantly improved the reduction of Eimeria spp. oocysts at both filter scales. and should be further investigated as a potential irrigation water intervention to reduce C. cayetanensis. Full article

(This article belongs to the Special Issue Advances in Research on Waterborne Pathogens)

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21 pages, 1410 KB

Open AccessArticle

Ultrafiltration Harvesting of Microalgae Culture Cultivated in a WRRF: Long-Term Performance and Techno-Economic and Carbon Footprint Assessment

by Juan Francisco Mora-Sánchez, Josué González-Camejo, Guillermo Noriega-Hevia, Aurora Seco and María Victoria Ruano

Sustainability 2024, 16(1), 369; https://doi.org/10.3390/su16010369 - 31 Dec 2023

Cited by 2 | Viewed by 2841

Abstract

A cross-flow ultrafiltration harvesting system for a pre-concentrated microalgae culture was tested in an innovative anaerobic-based WRRF. The microalgae culture was cultivated in a membrane photobioreactor fed with effluent from an anaerobic membrane bioreactor treating sewage. These harvested microalgae biomasses were then anaerobically [...] Read more.

A cross-flow ultrafiltration harvesting system for a pre-concentrated microalgae culture was tested in an innovative anaerobic-based WRRF. The microalgae culture was cultivated in a membrane photobioreactor fed with effluent from an anaerobic membrane bioreactor treating sewage. These harvested microalgae biomasses were then anaerobically co-digested with primary and secondary sludge from the water line. Depending on the needs of this anaerobic co-digestion, the filtration harvesting process was evaluated intermittently over a period of 212 days for different operating conditions, mainly the total amount of microalgae biomass harvested and the desired final total solids concentration (up to 15.9 g·L⁻¹ with an average of 9.7 g·L⁻¹). Concentration ratios of 15–27 were obtained with average transmembrane fluxes ranging from 5 to 28 L·m⁻²·h⁻¹. Regarding membrane cleaning, both backflushing and chemical cleaning resulted in transmembrane flux recoveries that were, on average, 21% higher than those achieved with backflushing alone. The carbon footprint assessment shows promising results, as the GHG emissions associated with the cross-flow ultrafiltration harvesting process could be less than the emissions savings associated with the energy recovered from biogas production from the anaerobic valorisation of the harvested microalgae. Full article

(This article belongs to the Special Issue Microalgae-Based Wastewater Treatment Processes and Biorefineries)

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11 pages, 3317 KB

Open AccessArticle

A Study of the Pulse Cleaning Process for Metal Fiber Filter Bags Based on a Discrete Phase Particle Deposition Model

by Wenming Liu, Zhiqiang Xu and Xuedong Liu

Atmosphere 2023, 14(1), 156; https://doi.org/10.3390/atmos14010156 - 10 Jan 2023

Cited by 1 | Viewed by 2546

Abstract

Emissions of airborne particulate matter are a major cause of air pollution. A numerical approach was used to establish a single-filter-bag cleaning model based on the discrete phase particle deposition distribution law to study the effect of pulse backflushing operation parameters on the [...] Read more.

Emissions of airborne particulate matter are a major cause of air pollution. A numerical approach was used to establish a single-filter-bag cleaning model based on the discrete phase particle deposition distribution law to study the effect of pulse backflushing operation parameters on the cleaning performance of the specific structure of the dust collector. It was found that increasing the pulse blowing pressure (0.2 MPa to 0.6 MPa) and extending the pulse width (0.02 s to 0.1 s) resulted in an increase in the side wall pressure of the filter bag and, thus, improved its cleaning effect. The influence of the injection pressure on the side wall pressure peak of the filter bag was more obvious than that of the pulse width. However, it cannot be concluded that the greater the injection pressure and pulse width, the better the cleaning effect. Therefore, in the actual production application, the operating cost of the equipment needs to be taken into account, as well as the amount of dust on the surface of the filter bag. Full article

(This article belongs to the Section Air Pollution Control)

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19 pages, 4075 KB

Open AccessArticle

Fouling Analysis in One-Stage Ultrafiltration of Precipitation-Treated Bacillus subtilis Fermentation Liquors for Biosurfactant Recovery

by Mai Lien Tran, Ying-Shr Chen and Ruey-Shin Juang

Membranes 2022, 12(11), 1057; https://doi.org/10.3390/membranes12111057 - 28 Oct 2022

Cited by 10 | Viewed by 2180

Abstract

Primary recovery of surfactin from precipitation-pretreated fermentation broths of Bacillus subtilis ATCC 21332 culture by one-stage dead-end and cross-flow ultrafiltration (UF) was studied. Dead-end experiments were first performed to select suitable conditions, including the amount of added ethanol—a micelle-destabilizing solvent (0–70 vol%), type [...] Read more.

Primary recovery of surfactin from precipitation-pretreated fermentation broths of Bacillus subtilis ATCC 21332 culture by one-stage dead-end and cross-flow ultrafiltration (UF) was studied. Dead-end experiments were first performed to select suitable conditions, including the amount of added ethanol—a micelle-destabilizing solvent (0–70 vol%), type (polyethersulfone, polyacrylonitrile, poly(vinylidene fluoride)) and molecular-weight cut-off (MWCO, 30–100 kDa) of the membrane in the surfactin concentration range of 0.25–1.23 g/L. Then, the cross-flow UF experiments were conducted to check the recovery performance in the ranges of feed surfactin concentration of 1.13–2.67 g/L, flow velocity of 0.025–0.05 m/s, and transmembrane pressure of 40–100 kPa. The Hermia model was also used to clarify membrane fouling mechanisms. Finally, three cleaning agents and two in situ cleaning ways (flush and back-flush) were selected to regain the permeate flux. As for the primary recovery of surfactin from the permeate in cross-flow UF, a polyethersulfone membrane with 100-kDa MWCO was suggested, and the NaOH solution at pH 11 was used for membrane flushing. Full article

(This article belongs to the Special Issue Membrane Separation Techniques: Advances, Challenges, and Future Avenues)

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25 pages, 7090 KB

Open AccessArticle

Membrane Separation Used as Treatment of Alkaline Wastewater from a Maritime Scrubber Unit

by Maryse Drouin, Giulia Parravicini, Samy Nasser and Philippe Moulin

Membranes 2022, 12(10), 968; https://doi.org/10.3390/membranes12100968 - 2 Oct 2022

Cited by 4 | Viewed by 2684

Abstract

Since 1 January 2020, the sulfur content allowed in exhaust gas plume generated by marine vessels decreased to 0.5% m/m. To be compliant, a hybrid scrubber was installed on-board, working in closed loop and generating a high volume of alkaline wastewater. The alkaline [...] Read more.

Since 1 January 2020, the sulfur content allowed in exhaust gas plume generated by marine vessels decreased to 0.5% m/m. To be compliant, a hybrid scrubber was installed on-board, working in closed loop and generating a high volume of alkaline wastewater. The alkaline water suspension was treated by a silicon carbide multitubular membrane to remove pollutants, and to allow the water discharge into the natural environment. In this paper, membrane filtration behavior was analyzed for the maritime scrubber wastewater. A range of operating parameters were obtained for several feedwater quality-respecting industrial constraints. The objective was an improvement of (I) the water recovery rate, (II) the filtration duration, and (III) the permeate quality. Thus, in high-fouling water, a low permeate flow (60 L h⁻¹ m⁻²) with frequent backflushing (every 20 min) was used to maintain membrane performance over time. In terms of water quality, the suspended solids and heavy metals were retained at more than 99% and 90%, respectively. Other seawater discharge criteria in terms of suspended solids concentration, pH, and polyaromatic hydrocarbons were validated. The recommended operating conditions from laboratory study at semi-industrial scale were then implemented on a vessel in real navigation conditions with results in agreement with expectations. Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in France 2021-2022)

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14 pages, 2658 KB

Open AccessArticle

Investigations on Backflush Cleaning of Spent Grain-Contaminated Filter Cloths Using Continuous and Pulsed Jets

by Roman Alejandro Werner, Alexander Michael Hummel, Dominik Ulrich Geier and Thomas Becker

Foods 2022, 11(12), 1757; https://doi.org/10.3390/foods11121757 - 15 Jun 2022

Cited by 1 | Viewed by 2316

Abstract

This study investigated the continuous and pulsed backflush cleaning of woven fabrics that act as filter media in the food and beverage industry. Especially in breweries, they are commonly used in mash filters to separate solid spent grains from liquid wort. After filtration, [...] Read more.

This study investigated the continuous and pulsed backflush cleaning of woven fabrics that act as filter media in the food and beverage industry. Especially in breweries, they are commonly used in mash filters to separate solid spent grains from liquid wort. After filtration, the removal of such cereal residues via self-discharge is necessary. However, this filter cake discharge is typically incomplete, and various spots remain contaminated. In addition to the reduced filter performance of subsequent batches, cross-contamination risk increases significantly. A reproducible contamination method focusing on the use case of a mash filter was developed for this study. Additionally, a residue analysis based on microscopical image processing helped to assess cleaning efficiency. The experimental part compared two backflushing procedures for mash filters and demonstrated fluid dynamical, procedural, and economic differences in cleaning. Specifically, pulsed jets show higher efficiency in reaching cleanliness faster, with fewer cleaning agents and less time. According to the experimental results, the fluid flow conditions depended highly on cloth geometry and mesh sizes. Larger mesh sizes significantly favored the cloth’s cleanability as a larger backflush volume can reach contamination. With these results, cloth cleaning can be improved, enabling the realization of demand-oriented cleaning concepts. Full article

(This article belongs to the Section Food Engineering and Technology)

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19 pages, 52247 KB

Open AccessArticle

Improving the Performance of the Reverse Osmosis Process with Fiber Filter and Ultrafiltration: Promoting Municipal Sewage Reclamation and Reuse for Industrial Processes

by Shih-Shuo Chan and Jung-Hua Wu

Sustainability 2022, 14(9), 5443; https://doi.org/10.3390/su14095443 - 30 Apr 2022

Cited by 1 | Viewed by 3035

Abstract

Wastewater reuse presents a promising solution to the growing need for the sustainable use of available water resources. The reclamation of municipal sewage through reverse osmosis can be applied for diverse uses to alleviate chronic water scarcity. In this study, a pilot plant [...] Read more.

Wastewater reuse presents a promising solution to the growing need for the sustainable use of available water resources. The reclamation of municipal sewage through reverse osmosis can be applied for diverse uses to alleviate chronic water scarcity. In this study, a pilot plant was fabricated to measure the efficiency and the costs that are associated with pretreatment by the fiber filtration and ultrafiltration of secondary effluent from a water resource recovery facility in Taiwan. The results of this dual-membrane process meet the quantity and quality standards for industrial reuse. The pretreatment produced feedwater with a silt density index (SDI₁₅) lower than 4.1, and with average turbidity removal rates of 42.7% (fiber filtration) and 99.2% (ultrafiltration). Following reverse osmosis, a 97.9% rejection of the electrolyte conductivity was achieved in the reclaimed water. The fouling of the membranes was controlled through the application of intensive backwash, chemically enhanced backflushing, and cleaning in place. The proposed system improves the feasibility, reliability, and economy of the dual-membrane process as a tertiary treatment for safe water reuse, and it thereby demonstrates that this technology has reached maturity for the full-scale implementation of sustainable water reuse. Full article

(This article belongs to the Special Issue Technology for Sustainable Wastewater Treatment)

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15 pages, 890 KB

Open AccessReview

Cleaning Methods for Ceramic Ultrafiltration Membranes Affected by Organic Fouling

by Kamila Gruskevica and Linda Mezule

Membranes 2021, 11(2), 131; https://doi.org/10.3390/membranes11020131 - 14 Feb 2021

Cited by 56 | Viewed by 10017

Abstract

The use of ceramic membranes in the treatment and processing of various liquids, including those of organic origin, has increased tremendously at the industrial level. Apart from the selection of the most appropriate membrane materials and operational conditions, suitable membrane cleaning procedures are [...] Read more.

The use of ceramic membranes in the treatment and processing of various liquids, including those of organic origin, has increased tremendously at the industrial level. Apart from the selection of the most appropriate membrane materials and operational conditions, suitable membrane cleaning procedures are a must to minimize fouling and increase membrane lifespan. The review summarizes currently available and practiced non-reagent and cleaning-in-place methods for ceramic membranes that are used in the treatment of organic liquids, thus causing organic fouling. Backflushing, backwashing, and ultrasound represent the most often used physical methods for reversible fouling treatment. At the same time, the use of alkalis, e.g, sodium hydroxide, acids, or strong oxidants are recommended for cleaning of irreversible fouling treatment. Full article

(This article belongs to the Section Inorganic Membranes)

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15 pages, 3792 KB

Open AccessArticle

Photoactive Gel for Assisted Cleaning during Olive Mill Wastewater Membrane Microfiltration

by Yilong Han, Lidietta Giorno and Annarosa Gugliuzza

Membranes 2017, 7(4), 66; https://doi.org/10.3390/membranes7040066 - 25 Nov 2017

Cited by 8 | Viewed by 4766

Abstract

A photoactive gel has been fabricated on the surface of polyethylene membranes for enhancing the fouling resistance during olive mill wastewater treatment. Light and pH responsive materials have been introduced in the membrane surface through the build up of a layer-by-layer pattern, which [...] Read more.

A photoactive gel has been fabricated on the surface of polyethylene membranes for enhancing the fouling resistance during olive mill wastewater treatment. Light and pH responsive materials have been introduced in the membrane surface through the build up of a layer-by-layer pattern, which is formed by photocatalytic nanoparticles and ionic polyelectrolytes. The best working conditions to contrast foulants adsorption have been explored and identified. Repulsive interfacial forces and assisted transfer of foulants to catalytic sites have been envisaged as crucial factors for contrasting the decline of the flux during microfiltration. Tests in submerged configuration have been implemented for six continuous hours under irradiation at two different pH conditions. As a result, a worthy efficiency of the photoactive gel has been reached when suitable chemical microenvironments have been generated along the shell side of the membranes. No additional chemical reagents or expensive back-flushing procedures have been necessary to further clean the membranes; rather, fast and reversible pH switches have been enough to remove residues, thereby preserving the integrity of the layer-by-layer (LBL) complex onto the membrane surface. Full article

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