Search Results (56)

Nature-based solutions (NBSs), such as green roofs, are among the most effective ways to manage urban stormwater, improve building energy efficiency, and adapt to climate change. However, conventional green roofs confront several restrictions related to stormwater drainage, retention capacity, irrigation demand, and pressure on urban water networks during dry periods. This study proposes and experimentally validates a novel system applicable to green roofs and other NBS, including streetside planting systems and vegetated sports grounds. The novelty of the proposed system lies in a double-layer design, the integration of filters within soil substrate to enhance short-term stormwater retention and controlled drainage, and passive subsurface capillary irrigation with cords to improve irrigation efficiency. Infiltration tests showed that filter hydraulic conductivity strongly depends on pore size, with measured infiltration rates ranging from 0.01 mm/min (ceramic, 0.1 μm) to 20 mm/min (polypropylene, 50 μm). The results showed that filter material and pore size significantly influence infiltration behaviour and short-term storage capacity. When integrated with the soil substrate, the combined system exhibited infiltration rates of 0.8–2.0 mm/min, decreasing as hydraulic head declined. Capillary rise experiments demonstrated a maximum vertical rise of 32 cm and horizontal rise of 39 cm for polyester cords (6 mm width), confirming the feasibility of passive subsurface irrigation through stored runoff reuse without external energy. The experiments were conducted at a laboratory scale (25 × 25 cm) as a proof-of-concept validation. Finally, the study results demonstrate the feasibility of the proposed system as a multifunctional NBS solution that enhances stormwater retention while enabling passive irrigation using retained runoff. Full article

The escalating global water crisis, coupled with the unsustainable accumulation of industrial and urban waste, demands innovative solutions that align with circular economy principles. This review explores the transformative potential of waste-derived ceramic membranes as a sustainable strategy for water purification, simultaneously addressing waste valorization and clean water scarcity. Ceramic membranes, traditionally fabricated from high-purity inorganic materials, are renowned for their superior chemical resistance, thermal stability, and durability. Recent advances demonstrate that industrial byproducts, such as red mud, coal fly ash, blast furnace slag, coal gangue, and kiln roller waste, can be effectively repurposed into cost-effective, high-performance filtration materials. This paper critically examines fabrication techniques, material properties, and performance metrics of waste-derived ceramic membranes. By transforming industrial waste into functional filtration materials, this approach not only mitigates environmental pollution but also contributes to sustainable water security. Full article

Ceramic materials have been utilized for centuries across a range of industries due to their chemical stability and porous microstructure. One prominent application is water filtration, where ceramics offer an effective medium for removing contaminants. Ceramic filters can operate under either pressure-driven or gravity-driven mechanisms. While traditional fabrication techniques, such as pottery, have been historically employed to produce ceramic filters, these methods are limited by user skills, lack of reproducibility, and geometric constraints. In contrast, modern additive manufacturing techniques provide enhanced precision, repeatability, and customization. This study employs extrusion-based 3D printing to fabricate gravity-driven ceramic filters with tailored geometries to meet specific performance requirements. The use of 3D printing allows for efficient production of uniform filters with optimized internal structures. The selected ceramic material, derived from natural sources, offers environmental compatibility, as it is both sustainable and biodegradable. The fabricated filters were evaluated for their effectiveness in treating water. The filtration tests showed significant improvements in water quality, including reduced turbidity, color, iron, manganese, and total and calcium hardness. pH increased from 6.23 to 7.26, and conductivity dropped from 7.43 mS to 4.5 mS, indicating effective ion removal. These findings highlight the potential of 3D-printed ceramic filters as an environmentally friendly and effective solution for decentralized water purification applications. Full article

This study explores the different techniques used to manufacture porous clay-based ceramics, examining their properties such as porosity, strength, permeability and filtration efficiency. Different techniques are discussed in this review, with additive manufacturing being one of the most innovative techniques for manufacturing porous ceramics. Porous ceramics have their applications in numerous domains. Such ceramic filters have the advantages of retaining heavy materials, suspended particles, bacteria, viruses and, water turbidity. Thus, the choice of the technique and propriety is a crucial step in obtaining a porous ceramic with the best performance. Barry et al. prepared porous phyllosilicate-based ceramics by freeze-tape casting on four samples and obtained porosity values in the range of 67–79% and diametrical compressive strength in the range of 3–7 MPa. Manni et al. prepared porous red ceramics from Moroccan clay and coffee waste (10, 20 and 30 wt.%) via uniaxial pressing and sintering at 1150 °C. They obtained porosities ranging from 30.2 to 63.8% and flexural strength values from 1.8 to 19.5 MPa. Medri et al. prepared ZrB2-based porous bodies with the use of sponges and polyurethane foams as templates via the replica method and obtained high porosity over 80% and compressive strength up to 4.8 MPa. The use of clay and peanut shell mixtures was used in preparing porous silicate ceramics after unidirectional pressing and sintering at 1100 °C. These samples included 25 mass% of peanut shells, and exhibited porosity in the range of 40 to 60% and diametrical compressive strength in the range of 1–6 MPa. Such properties are suitable for domestic use of these types of clay-based ceramic filters. Moreover, the permeability values and removal of some pollutants, like arsenic, have been satisfactory for the first set of samples. Full article

Microplastics (MPs) are reported as ubiquitous in the environment. In recent years, these microplastic particles have been found in table salt, seafood, and honey, as well as in drinking water. However, the process by which water reaches households for consumption has not yet been investigated. Thus, we compared the concentration, shape, color, size, and polymer types of MPs in water sources that have passed through different filtration techniques for human consumption such as water purifiers, ceramic filters, and tap water. A total of 9262 items of microplastics were identified in the analyzed water samples. Higher MP concentration (ANOVA, F = 68.16; D.F. = 2; p < 0.01) was observed in water from purifiers (1.41 MPs/L) and taps (1.13 MPs/L) compared to ceramic filter water (0.49 MPs/L). Transparent fibers ranging in size from <500 µ to >5 mm, composed of polyester, polypropylene, and polyamide, were predominant in all water samples. We emphasize that regulations and restrictions related to the production and use of plastics, promotion of environmental education (scientific dissemination) for the population, and the development and popularization of filters that promote the retention of MPs at the source and also in sinks are useful measures for reducing contamination of water bodies and water for human consumption. Full article

Iron and manganese in groundwater impair the quality of drinking water; however, the rates of iron and manganese removal with conventional aeration and rapid sand filtration (RSF) processes vary extensively. Five full-scale aeration–RSF processes in Nepal also showed varying efficiencies of iron and manganese removal; while the iron concentration was below the national standard (0.30 mg/L) in 31 out of the 37 treated waters, the manganese concentration was higher than the standard (0.20 mg/L) in all of the treated waters. Re-aeration and stirring of the treated water did not oxidize soluble manganese, and this caused the poor removal rates for manganese. Bench-scale dual-media filters comprising anthracite on top of sand/ceramic layers with dosages of poly aluminum chloride and chlorine worked well by removing coagulated iron in the anthracite layer and then removing manganese in the sand/ceramic layers. A manganese-oxide-coated ceramic filter provided the highest manganese removal from 1.10 mg/L to <0.01 mg/L, followed by manganese-oxide-coated sand and quartz sand. Increasing the pH from 7.5 to 9.0 stabilized the manganese removal. Therefore, we propose a re-design of the present treatment processes and the selection of suitable filter media for better removal of iron and manganese. Full article

Porous α-Al₂O₃ ceramics are a highly sought-after material with a multitude of applications; for example, they are used as filters, substrates, biomedicine materials, etc. Despite the availability of raw materials, a challenge associated with this technology is the high energy budget caused by sintering above 1500 °C. For the cold sintering processing (CSP) of ceramics, lowering the α-Al₂O₃ sintering temperature is one of the most urgent challenges in the background of its rapid development. This paper is the first to demonstrate a solution to this problem using the CSP of α-alumina ceramics in the presence of pure water as a transient liquid. The manufactured materials were examined using XRD analysis; the evolution of their microstructures during CSP was revealed by SEM; and the porosity was evaluated using the Archimedes method. Ceramics with an open porosity up to 36% were produced at 380–450 °C and 220 MPa in 30 min. An increase in the pressure was found to impede α-Al₂O₃ formation from γ-AlOOH. The development of the microstructure was discussed within the framework of the dissolution–precipitation model and homogenous nucleation. The results of the SEM study pointed to the coalescence of γ-AlOOH grains during CSP. Full article

Recirculating aquaculture systems (RASs) offer significant advantages in aquaculture by markedly decreasing water usage and increasing culture density. A vital component within a RAS is the filler material, which serves as a surface for microbial colonization. Effective microbial treatment is crucial for the efficient operation of a RAS as it assists in purifying the wastewater generated within the system. Nevertheless, traditional fillers often show low efficiency in biofilm formation. The commercial silicon carbide used in this study is a foam ceramic filter with a density of about 0.4–0.55 g/cm³, a number of holes of about 10, and a through porosity of 80.9%, with a diameter of about 5 cm. This research investigates the utilization of a titanium dioxide–silicon carbide (TiO₂-SiC) composite filler to improve the purification efficiency of ammonia nitrogen and chemical oxygen demand (COD) in aquaculture wastewater. The study involved the application of titanium dioxide films onto the surface of silicon carbide to produce the composite filler. This method takes advantage of the dipole interaction between titanium dioxide and microorganisms, which enhances biofilm culturing efficiency on the silicon carbide surface. The performance of three different fillers was assessed for their ability to purify aquaculture wastewater. Results showed that the TiO₂-SiC composite filler was 1.67 times more effective in removing COD and 1.07 times more effective in removing ammonia nitrogen compared to using silicon carbide alone. These results demonstrate that the incorporation of a titanium dioxide coating substantially boosts the microbial colonization efficiency of silicon carbide, thereby enhancing the overall wastewater purification efficiency in RAS. Full article

Tests of microfiltration efficiency used for the pretreatment of backwash water from sand filters were conducted at two water treatment plants treating surface water and infiltration water. Microfiltration efficiency was evaluated for three membrane modules: two with polymeric membranes and one with a ceramic membrane. This study showed that the contaminants that limit the reuse of backwash water from both plants by returning them to the water treatment line are mostly microorganisms, including pathogenic species (Clostridium perfringens). Additionally, in the case of backwash water from infiltration water treatment, iron and manganese compounds also had to be removed before its recirculation to the water treatment system. Unexpectedly, organic carbon concentrations in both types of backwash water were similar to those present in intake waters. Microfiltration provided for the removal of organic matter, ranging from 19.9% to 44.5% and from 7.2% to 53.9% for backwash water from the treatments of surface water and infiltration water, respectively. Furthermore, the efficiency of the iron removal from backwash water from infiltration water treatment was sufficient to ensure good intake water quality. On the other hand, manganese concentrations in the backwash water, from infiltration water treatment, pretreated using the microfiltration process exceeded the levels found in the intake water and were, therefore, an additional limiting factor for the reuse of the backwash water. In both types of backwash water, the number of microorganisms, including Clostridium perfringens (a pathogenic one), was a limiting parameter for backwash water reuse without pretreatment. The results of the present study showed the possibility for using microfiltration for the pretreatment of backwash water, regardless of its origin but not as the sole process. More complex technological systems are needed before recirculating backwash water into the water treatment system. The polyvinylidene fluoride (PVDF) membrane proved to be the most effective for DOC and microorganism removal from backwash water. Full article

Used water treatment is one of the most important aspects of environmental protection regarding industrial processes. Particulate matter dispersions affect water parameters; for example, increased pH values such as 10.21 are found for used floor tile water, and values of 10.84 are found for used wall tile water. However, pH decreases to about 9.42 after the sediment filtration process. This influences water turbidity, which is higher for used wall tile water due to its finer suspensions, and it is considerably decreased after the filtration process. Thus, the main aim of the present research is to investigate particulate matter dispersion into the water flows that are involved in ceramic tile technological processes before and after treatment at used water treatment facilities. X-ray diffraction (XRD) coupled with mineralogical optical microscopy (MOM) reveals that waters from wall tiles and floor tiles have similar mineral dispersions, containing mineral particles of quartz (5–50 μm), kaolinite (1–30 μm), and mullite (5–125 μm). Glass particles (having a dark appearance at MOM investigation) were also found in both samples in a size range of 20–55 μm. High-resolution SEM imaging coupled with the EDS elemental analysis confirms the XRD and MOM observations. Water samples collected after treatment at the treatment facility reveal a significant reduction in the particulate matter MOM, evidencing only small traces of quartz, kaolinite, and mullite in a size range of 1–15 μm, with most of the particles being attached to the filters, as confirmed by XRD. Atomic force microscopy (AFM) effectuated on this sample reveals the presence of kaolinite nanoparticles with a tabular–lamellar aspect and sizes ranging from 40 to 90 nm. The obtained results prove the efficacy of the filtering system regarding targeted particulate matters, ensuring water recirculation into the technological processes. The sludge resulting from the filtration process presents with a dense grainy structure of sediment particles containing quartz, mullite, and kaolinite, along with traces of iron hydroxide crystallized as goethite. Therefore, it cannot be reused in the technological flux, as the iron causes glaze staining; but the observed microstructure, along with the mineralogical composition, indicates that it could be used for other applications, such as ecological bricks or plasters, which will be further investigated. Full article

The escalating demand for innovative solutions is driven by the challenges posed by water quality degradation and the pervasive impacts of climate change. As such, this study evaluated the performance of filter media to mitigate these challenges through multi-functional applications in urban constructed wetlands (UCWs). Column testing of organic filter media, including biochar (BC), woodchip (WC), anthracite (AT), and activated carbon (AC), as well as inorganic filter media, such as ceramic balls (CB), basalt (BS), and porous sand (PS), with synthetic stormwater runoff influent was conducted to assess their performance through water quality parameters and Scanning Electron Microscopy with Energy Dispersive X-ray (SEM-EDX) analysis for carbon storage potential. Among the media tested, AC exhibited high pollutant removal efficiencies amounting to 84%, 54%, 56%, and 44% for total suspended solids (TSS), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP), respectively. For inorganic media, PS had the highest TSS and TN removal, whereas BS exhibited the highest COD and TP removal. Overall performance rating revealed that AC and BS, despite their efficient pollutant removal, are associated with higher costs, resulting in a lower ranking compared to AT and PS. SEM-EDX analysis identified PS and AC as standout media for potential carbon storage, attributed to their extensive surface areas and pore structures providing abundant adsorption sites. The results from this study highlighted the potential applications of various filter media in UCW designs with the aim of achieving carbon neutrality and sustainable urban development. Full article

Overcoming the scarcity of safe and sustainable drinking water, particularly in low-income countries, is one of the key challenges of the 21st century. In these countries, the cost of centralized water treatment facilities is prohibitive. This work examines the application of low-cost ceramic filters as point-of-use (POU) devices for the removal of methylene blue, o-toluidine blue, Staphylococcus aureus, and Staphylococcus typhi from contaminated water. The ceramic filters had typical kaolinite functional groups, making them suitable for the removal of dyes and pathogens. Surface charge measurements indicated strongly anionic filters, while thermal properties confirmed the carbonization of the biowaste additive leaving behind a porous kaolinite structure which subsequently dehydroxylated into meta kaolinite. In addition, morphological data showed heterogeneous filter surfaces. Increased biomass content improved the permeability, water adsorption, flow rate, and apparent porosity of the filter. The ceramic filter removed methylene blue (42.99–59.74%), o-toluidine (79.95–92.71%), Staphylococcus aureus (98–100%), and Staphylococcus typhi (75–100%). Overall, the study demonstrated the effectiveness of POU ceramic filters in removing organic pollutants in contaminated water while serving as disinfectants. Full article

Small communities and most rural settlements in the Kingdom of Saudi Arabia (KSA) store domestic wastewater in residential septic tanks and transport it to the nearest centralized wastewater treatment plant. Without a sanitary sewerage system, the residents encounter various socioeconomic and environmental challenges related to sewage collection vehicles, the production of objectionable gases, and leaking septic tanks. The present study developed a resident perception-based methodology to appraise the sustainability of a low-cost ceramic filter bioreactor-type decentralized wastewater treatment system (DWWTS) for a small community of 1300 residents (160 households) in Qassim (KSA). In addition to six demographic factors, nine indicators assessed residents’ perceptions about existing and proposed wastewater management systems. A hierarchical-based system of sub-indices evaluated the three dimensions of sustainability using four environmental, nine social, and three economic indicators. The indicators translated into dichotomous questions posed to 34 respondents in the study area. The statistical analysis assessed the association of responses with the willingness to accept (WTA) the proposed DWWTS. A subjective rating scheme translated the responses into performance scores, and a fuzzy-based method aggregated the scores into sub- and top-level indices. The top of the hierarchy showed a close agreement between the resident’s perception and DWWTS’ sustainability. The study found that residents’ knowledge about environment and resource conservation resulted in a moderately high willingness to reuse treated effluent and WTA the decentralized system. The study also showed that the economic viability of a DWWTS remained at a moderate performance level due to a low monthly waste disposal cost. The study’s findings present a high potential for sustainable community-maintained DWWTS initially supported by the government. The proposed approach facilitates decision-makers working in ministries concerning water resources, environmental protection, and agricultural production in evaluating the sustainability of DWWTS for small communities in arid regions. Full article

Although many households in the Kathmandu Valley rely on household water treatment and safe storage (HWTS) to obtain drinking water, the safety of treated water has not been evaluated in actual usage. Therefore, we assessed the performance and maintenance of five HWTS methods used in 101 households. The choice of HWTS methods by households was primarily influenced by the raw water source, that is, jarred water users opted for boiling and groundwater users selected reverse osmosis with ultraviolet irradiation (RO-UV). While boiling and electric dispensers (ED) did not remove inorganic contaminants (ammonia nitrogen, arsenic, and manganese), ceramic candle filters (CCF) and RO-UV reduced them moderately. The HWTS methods reduced E. coli and total coliforms (TC) by 95.8 and 84.1%, respectively, but 11.8 and 69.3% of treated water samples remained positive for these two bacteria. Combined methods (CM) and RO-UV showed an inferior TC reduction compared to the simpler HWTS methods, boiling, CCF, and ED, possibly due to difficulties with regular maintenance and storage contamination. Therefore, it is recommended to choose simpler HWTS methods that meet the requirements of the household’s water sources rather than more expensive and difficult-to-maintain methods, which should be chosen only if the raw water contains high concentrations of inorganic contaminants. Full article

Seawater reverse osmosis (SWRO) is the most energy-efficient process for desalination to produce drinking water from seawater. However, its sustainability is still challenged by membrane fouling. Appropriate feed water quality is one of the crucial prerequisites for SWRO operation. In the current study, a ceramic adsorption filter (CAF), which was predominantly coated with an aluminum-based adsorbent (i.e., Alumina, Al₂O₃), was employed to enhance the pretreatment performance of SWRO. The fouling performance of SWRO pre-treated with a CAF was evaluated by feeding with real ultrafiltration (UF)-filtrated seawater collected from a seawater desalination R&D facility in Singapore. The flux decline profile showed that the presence of CAF after UF could mitigate around 10–30% of SWRO fouling. Based on the autopsy of the fouled SWRO membranes, it was observed that SWRO with CAF pre-treatment and daily regeneration could alleviate around 77.5% of Ca-induced inorganic fouling as well as 76% of lower biofouling. The present work highlights the potential of applying adsorption technology to enhance pre-treatment performance to extend the lifespan of SWRO membranes. Coupling the adsorbents on a ceramic filter should be a useful way to ease their implementation, i.e., inline adsorption and re-generation. Full article