Enhancement of biological slow filtration by micro-electric field with granular electrodes: Influence of anode position and microbial characteristics

Toxic impacts of nitrite on fish and intervention strategies.

Direct potable reuse (DPR) is a promising solution to address water scarcity. However, a better understanding of how introducing advanced treated water (ATW) affects microbial communities present in distribution systems is needed. In this study, we measured changes to the microbial water quality in simulated distribution systems that were conditioned using treated, unimpaired surface water (SW) and then transitioned to ATW. In addition, we investigated whether adding a biological filtration step would seed the microbial community of the ATW and whether the influence would persist in the simulated distribution systems. We found that the bulk water in the ATW-fed distribution systems had lower cell counts and ATP concentrations and a distinct microbial community (based on 16S amplicon sequencing) compared to the SW-fed or the seeded ATW-fed systems. However, biofilm community composition and biomass remained consistent regardless of the feedwater. Increased microbial biomass and diversity were present in the seeded ATW, with several amplicon sequence variants identified as being introduced by the biological filter. Our results suggest that directly introducing ATW to distribution systems could disturb the existing microbial community. Preparing ATW for distribution via biological filtration may deliver more predictable and stable microbial water quality than introducing unseeded ATW.

Abstract This study investigates the performance of a Hybrid System Membrane Bioreactor (HS‐MBR), an emerging and sustainable technology for advanced wastewater treatment. The Membrane Bioreactor (MBR) integrates the activated sludge and biofilm processes, combining their advantages to minimize Mixed Liquor Suspended Solids (MLSS) while enhancing treatment efficiency and effluent quality. In this research, the HS‐MBR is developed as an alternative, cleaner, and more efficient approach for wastewater purification. The system incorporates hollow fiber ultrafiltration (UF) membranes with plastic carriers, effectively coupling biological degradation and membrane filtration to achieve superior pollutant removal. The performance of the HS‐MBR was evaluated under different hydraulic retention times (HRTs) of 1, 2.5, and 5 h to determine the influence of HRT on effluent quality and transmembrane pressure (TMP), an indicator of membrane resistance. Experimental results showed that the HS‐MBR achieved about 80% COD removal at an HRT of 1 h, 83% at 2.5 h, and 92% at 5 h. Similarly, NH 4 ‐N removal efficiencies after 30 days ranged between 78% and 90% at 1 h, 81–90% at 2.5 h, and 89–94% at 5 h, demonstrating excellent biological performance. At an HRT of 2.5 h, suspended and attached biomass concentrations increased gradually and stabilized, while at 5 h, adhered biomass remained nearly constant, indicating steady‐state conditions and system equilibrium. Longer HRTs enhanced contact between microorganisms and organic compounds, leading to more effective COD degradation and greater membrane stability. Overall, the HS‐MBR system proved to be a reliable and high‐performance solution for advanced wastewater treatment applications.

Brackish water used in aquaculture often contains high levels of contaminants that require treatment to make it suitable for farming. This study evaluates the effectiveness of sand filters in improving raw water quality at the Brackish Water Aquaculture Fisheries Center in Takalar, South Sulawesi, over a two-month monitoring period. A pre- and post-filtration analysis was conducted on key water quality parameters, including Total Organic Carbon (TOC), Ammonia (NH₃), Nitrite (NO₂), and Total Bacterial Count (CFU/mL). Results indicated that the sand filter system effectively reduced TOC by 20.99% and bacterial load by 13.18%. However, ammonia removal was minimal at 1.04%, and nitrite levels rose significantly by 23.93% after filtration. These findings indicate that while sand filters effectively reduce organic and microbial pollutants, they are inadequate for managing nitrogen compounds. The novelty of this study lies in its use of sand filtration in operational, high-salinity aquaculture environments, a context that remains insufficiently explored in existing research literature. Further integration with biological filtration systems is advised to boost nitrogen removal and enhance overall treatment efficiency.

ABSTRACTDiaspore (e.g., seed and spore) dispersal is recognized as a key mechanism in plant dynamics, including endozoochory, which can be a risky journey for diaspores. Endozoochory is achieved when diaspores are consumed and may germinate after the mastication, the gut and fecal matrix passage, all representing filters for diaspores. Nevertheless, endozoochory is a highly studied mechanism through numerous methods, notably based on the observation of frugivorous behavior, diaspores retrieved in feces or germination experiments. However, most of those methods consider partially the endozoochorous filters (ingestion, mastication, gut, feces). Hence, the combined effect of the methods and filters consideration may lead to biased inference of endozoochory. In this study, we used a collection of 52 brown bear (Ursus arctos) feces to highlight five methods inferring endozoochory. Two methods consider the ingestion filter and used metabarcoding of fecal eDNA to identify fleshy fruits (i) or plants during fruiting periods (ii). The third method (iii) was based on the intact propagules retrieved in feces, considering ingestion and mastication filters. Another method (iv) was based on the germination from disaggregated feces, considering up to the gut passage filter. The last method (v) was based on the germination from aggregated feces, considering the four filters. We compared the number of taxa, the community and the plant life forms inferred among methods. We inferred the largest number of taxa in method (iii), but the germination‐based methods inferred the most diverse plant life forms. We identify few shared taxa among methods. The metabarcoding‐based methods might be an interesting tool as a first approximation of endozoochory while detailing the diet. The method (v) appeared as the most reliable. Overall, we invite future studies to mitigate their interpretations according to the filters of endozoochory considered and plant detectability related to the method used.

Feasibility of combining biological hydrogel reactive filter media with electrokinetic for sustainable site remediation

Efficient removal of nitrogen, phosphorus and antibiotics in freshwater aquaculture wastewater using a novel hybrid aeration biological filter.

Spatio-temporal dynamics of heavy metals during Arabidopsis germination: Endosperm barrier function and fulvic acid-mediated Pb detoxification revealed by μ-SRXRF and XANES.

Background: Phylogeographic surveys of obligate freshwater fishes could serve as a pivotal lens through which the biological footprints of historic drainage rearrangements can be deciphered. Methods: Focusing on the headwater-restricted cyprinid Acrossocheilus kreyenbergii in the Pearl, Yangtze, and Huai river basins, we examined variations in mitochondrial cytochrome b gene (Cyt b) to elucidate the phylogeographic architecture and evolutionary history of this stream fish in South–Central China through integrative analyses of phylogeny, ancestral area reconstruction, genetic structure, and population demography. Results: A time-calibrated phylogeny recovered two primary lineages, K-I and K-II, which diverged ca. 2.15 Ma: K-I split into K-Ia (Huai River) and K-Ib (Yangtze–Poyang Lake catchment) at 1.53 Ma, whereas K-II gave rise to K-IIa, K-IIb, and K-IIc through sequential divergences at 1.29 Ma and 0.83 Ma, with K-IIa restricted to the Poyang Lake catchment. K-IIb was shared between the Poyang Lake catchment and the Qiupu River (Yangtze basin), and K-IIc was distributed in the Xijiang River (Pearl basin) as well as the Yangtze–Dongting Lake catchment. Conclusions: Our findings reveal that the phylogeographic architecture of A. kreyenbergii was sculpted by a succession of geologic and anthropocentric events: the Late-Cenozoic collapse of the Zhe–Min Uplift first fractured its range; the intervening Mufu–Lianyun–Luoxiao Mountains then acted as a persistent barrier; the large waters of Poyang and Dongting Lakes served as biological filters; and the 2200-year-old Lingqu Canal—constructed during the Qin dynasty—briefly re-established a corridor for gene flow. Together, these forces disrupted and reorganized the species’ genetic connections, leaving a visible imprint today.

Membrane bioreactors (MBRs) are increasingly recognized as a key technology in sustainable wastewater treatment, offering a high effluent quality through the integration of biological degradation and membrane filtration. Among the critical factors influencing their performance are biofilm dynamics and membrane fouling. This article critically examines recent advances in biofilm engineering and antifouling strategies for MBRs, with an emphasis on microbial community modulation, quorum quenching, and hydrodynamic control to improve biofilm stability. In parallel, the review examines material-based and biological methods to mitigate membrane fouling, emphasizing multifunctional surfaces and emerging biocontrol strategies. Key operational challenges, such as energy consumption, cleaning frequency, and membrane aging, are evaluated alongside future research directions in materials design, microbial ecology, and real-time system optimization. The integration of these innovations is essential for advancing MBR technologies that are robust, resource-efficient, and aligned with circular economy principles.

Slow sand filters(SSFs) are increasingly recognizedfor enhancingthe biological stability of drinking water. While research has historicallyfocused on the top layer (Schmutzdecke) of SSFs,the contribution of deeper filter depths in removing dissolved organiccarbon (DOC) and ammonium (NH4+) has recentlybeen acknowledged. This study investigated the occurrence and potentialpathways of DOC release in mature full-scale, and young laboratorySSFs. The top layer (5 cm) reduced the easily biodegradable DOC, mainlylow-molecular-weight (LMW) acids and building blocks. The middle layers(20–60 cm) released DOC, particularly LMW acids and neutrals,at depths where nitrification was nearly complete. This release occurredin both mature and young SSFs and may result from bacterial activityunder carbon or nitrogen limitation or from the transformation ofslowly degradable DOC into labile forms. Whatever the precise mechanismof release, the bottom layers (60–90 cm) subsequently removedthis released DOC and reduced PO43– toultralow levels, highlighting the importance of the deepest layersin maintaining effluent quality. This study provides the first evidenceof biodegradable DOC release in SSFs and emphasizes the need to betterunderstand its implications for carbon cycling and removal processesin biological filters.

Abstract The rapid growth and expansion of Neotropical cities make it increasingly challenging to identify and delineate regions within the urban continuum, such as peri-urban and intra-urban regions, where transitional spaces, or ecotones, often function as biological filters. Despite their ecological importance, such zones remain underexplored within the urban contexts. In this study, we focused on bird communities to identify ecologically relevant regions within the urban continuum of a Neotropical city in southern Mexico (Tuxtla Gutiérrez, Chiapas). We assessed changes in avian community composition, species richness and phylogenetic diversity across peri-urban and intra-urban sites at increasing categorical distances from the urban center. Composition analysis revealed that bird distribution along the urban continuum is not uniform, showing greater species turnover than nestedness among areas, supporting the ecological distinction between intra-urban and peri-urban regions. Rarefied species richness was higher in the peri-urban region than in the intra-urban region, but differences were not statistically significant. Phylogenetic diversity was significantly higher in the peri-urban region, possibly due to unique, evolutionarily ancient species that are distantly related, contribute to greater phylogenetic differentiation and making it the key ecological distinction between regions. Our findings highlight the importance of identifying and managing ecologically distinct urban regions to support sensitive species and mitigate the impacts of urban expansion. Likewise, incorporating measures of diversity, such as phylogenetic diversity, along with spatial data, were effective in preserving key aspects of biodiversity, as it enables a more comprehensive understanding of species distribution and conservation priorities within urban landscapes.

Integrating constructed wetlands with maize cobs biological trickling filter for antibiotic removal: An innovative waste-to-treatment approach.

Environmental DNA (eDNA) biodiversity surveys have the power to transform the detection of species in natural environments, which is crucial for the conservation and management of freshwater, estuarine and marine environments. Globally, eDNA-based analyses have increased significantly, with fishes being the most widely studied aquatic organisms. However, the extent of work and the current status of eDNA-based surveys for southern Africa are unclear. A literature search for studies with a focus on fishes was carried out for Botswana, Namibia, Mozambique, South Africa and Zimbabwe and retrieved 16 papers. Most of these were from South Africa (n = 14), with one paper each from Botswana and Mozambique. No papers were found for Namibia and Zimbabwe. Eleven papers utilized metabarcoding to detect fish communities, whereas four utilized species-specific primers to detect rare (e.g., coelacanth, pipefishes, endangered and vulnerable freshwater fishes) or invasive (silver carp) species and one consisted of a diet study. There were five papers from freshwater and 11 studies applying eDNA-based surveys in estuaries or marine systems. A scan of some of the technical aspects of the eDNA workflow (biological replication filtration, inclusion of negative controls, primer choice and technical replication) showed a wide range of approaches, highlighting the need for standardization of the eDNA workflow and the reporting of its data. Unsurprisingly, one of the largest challenges remains the lack of referenced barcodes, which limits the ability to determine species distributions and associated ecological inferences. Building on the exciting work highlighted here and to fully realize the power of eDNA will require increasing collaborations across all aspects of the eDNA workflow. Further, exploring pathways for the meaningful integration of data derived from eDNA surveys to support conservation and management decisions, not only for fishes but also for all the incredible biodiversity of southern Africa, is crucial.

Forests are considered one of the most valuable natural areas in metropolitan region landscapes. Considering the sensitivity and ecosystem services provided by trees, the definition of urban forest ecosystems is nowadays based on a comprehensive understanding of the entire urban ecosystem. The effective capturing of particulate matter is one of the ecosystem services provided by urban forests. These ecosystems function as efficient biological filters. Plants accumulate pollutants passively via their leaves. Therefore, another ecosystem service provided by city forests could be the use of tree organs as bioindicators of pollution. This paper aims to estimate differences in trace metal pollution between the wooded urban areas of Vienna and Krakow using leaves of evergreen and deciduous trees as biomonitors. An additional objective of the research was to assess the ability of the applied tree species to act as biomonitors. Plant samples of five species—Norway spruce, Scots pine, European larch, common white birch, and common beech—were collected within both areas, in seven locations: four in the “Wienerwald” Vienna forest (Austria) and three in the “Las Wolski” forest in Krakow (Poland). Concentrations of Cr, Cu, Cd, Pb, and Zn in plant material were determined. Biomonitoring studies with deciduous and coniferous tree leaves showed statistically higher heavy metal contamination in the “Las Wolski” forest compared to the “Wienerwald” forest. Based on the conducted analyses and the literature study, it can be concluded that among the analyzed tree species, only two: European beech and common white birch can be considered potential indicators in environmental studies. These species appear to be suitable bioindicators, as both are widespread in urban woodlands of Central Europe and have shown the highest accumulation levels of trace metals.

Abstract Fossil data are subject to inherent biological, geologic, and anthropogenic filters that can distort our interpretations of ancient life and environments. The inevitable presence of incomplete fossils thus requires a holistic assessment of how to navigate the downstream effects of bias on our ability to accurately reconstruct aspects of biology in deep time. In particular, we must assess how biases affect our capacity to infer evolutionary relationships, which are essential to analyses of diversification, paleobiogeography, and biostratigraphy in Earth history. In this study, we use an established completeness metric to quantify the effects of taphonomic filters on the amount of phylogenetic information available in the fossil record of 795 extinct squamate (e.g., lizards, snakes, amphisbaenians, and mosasaurs) species spanning 242 Myr of geologic time. This study found no meaningful relationship between spatiotemporal sampling intensity and fossil record completeness. Instead, major differences in squamate fossil record completeness stem from a combination of anatomy/body size and affinities of different squamate groups to specific lithologies and depositional environments. These results reveal that naturally occurring processes create structural megabiases that filter anatomical and phylogenetic data in the squamate fossil record, while anthropogenic processes play a secondary role.

National-scale insights into AMR transmission along the wastewater-environment continuum.

Aquatic macrophytes serve as a remarkable biological filter. By absorbing the dissolved metals and pollutants through their tissues, they can efficiently detoxify water streams. The majority of human activities result in the discharge of toxic substances, including heavy metals, as byproducts into water, sediments, and the environment. This study assesses the efficacy of the usage of submerged aquatic macrophytes, such as Ceratophyllum demerssum L. (Family: Ceratophyllaceae) and Potamogeton pectinatus L. (Family: Potamogetonaceae), gathered from El-Burullus Lake, which is located northeast to deltaic vicinity of Egypt, to purify waste-polluted water from heavy metals: cadmium, lead, zinc and manganese. Concentrations of these metals in the wastewater samples were measured by means of atomic absorption spectroscopy. Results showed that C. demerssum has an elimination performance of 63% for heavy metals studied, which was lower than that of P. pectinatus measured at 75%. Therefore, aquatic macrophytes studied are promising candidates for remediating wastewater, comparing extent of eco-toxicity, and preventing pollution occurring in the aquatic environments.

Abstract This study investigates the removal efficiency of various water contaminants using a Biological Sand Filtration (BSF) system under different operational conditions. The performance of the BSF system was evaluated for microbial contaminants (E. coli), suspended solids, dissolved solids (TDS), electrical conductivity (EC), hardness, chloride (Cl), sulfate (SO₄), and turbidity. Key operational parameters such as pH, retention time, flow rate, and the biological layer thickness were optimized to determine their impact on contaminant removal efficiency. The results demonstrated that a 48-hour retention time achieved complete E. coli removal (100%), while the 2 mm biological layer contributed to a significant reduction in microbial contaminants (81.2%). The highest turbidity reduction (85.4%) was achieved at a 0.5 m/h flow rate, and the pH 4.01 condition optimized the removal of TDS (65.4%) and EC (56.9%). Total hardness removal was maximized at 25°C, while magnesium removal was most effective with a 48-hour retention time (75.2%). Chloride removal peaked at 25°C (73.2%), and sulfate removal was optimized at pH 6.86 (52.9%). The study highlights the importance of adjusting operational parameters to optimize the performance of BSF systems for diverse contaminants, providing a sustainable and efficient solution for water quality improvement. The findings offer valuable insights for designing and operating BSF systems in varying environmental conditions and contribute to the development of cost-effective water treatment technologies.