Membrane fouling caused by complex greywater synthesized by personal care products and detergents commercially available for household applications was investigated using dead-end microfiltration ...(MF) and analyzed systematically by a multistage Hermia blocking model as a first attempt. The highest flux decline was associated with the smallest pore size of the membrane (0.03 μm). This effectiveness was more pronounced at higher applied pressures to the membrane. A cake layer was formed on the membrane consisting mainly of silica particles present as ingredients in greywater. Although organic rejection was low by the porous MF membrane, the organic compound contributed to membrane fouling in the filtration stage. With a 0.03 μm pore size of the membrane, dominant fouling mechanisms were classified into three stages as applied pressure increased, such as complete pore blocking, intermediate pore blocking, and cake layer formation. Specifically, during the early stage of membrane filtration at 1.5 bar, membrane fouling was determined by complete pore blocking in the 0.10 μm pore size of the membrane. However, the later stage of membrane fouling was controlled mainly by intermediate pore blocking. Regardless of the applied pressure, pore constriction or standard blocking played an important role in the fouling rate with a 0.45 μm pore size of the membrane. Our results also support that complex formation can occur due to the concentration of organic and inorganic species present in simulated greywater. Thus, strategic approaches such as periodic, chemically enhanced backwashing need to be developed and tailored to remove both organic and inorganic fouling from MF membranes treating greywater.
Excavator–truck operations, characterized by their repetitive excavation and loading tasks, present a prime candidate for automation. While numerous studies have aimed to automate the earthworks, ...practical implementations remain scarce. This research introduces a task component design focused on excavator–truck operation planning to improve the functionality of an earthwork automation system. To address this, fundamental task primitives necessary for executing excavation tasks were engineered, and a web-based system was developed to automate the generation of work plans for both point and trench excavation through algorithmic processes. Additionally, a JSON-based protocol was introduced to facilitate efficient integration with other subsystems. Field tests were conducted to validate the effectiveness of the newly developed algorithm and protocol within the broader context of earthwork automation systems. The results demonstrated the successful implementation of the task components, confirming their operational viability and seamless integration into the existing earthwork automation framework.
Background
Chronic wound infections are a serious global health concern affecting millions of people. One of the major challenges in treating biofilm-based wound infections is the presence of an ...extracellular polymeric substance (EPS) that limits the penetration of antimicrobial agents.
Area covered
This review focuses on conventional, current, and prospective anti-biofilm therapies for treating topical biofilm-based wound infections. Conventional strategies involving wound debridement, topical antibiotics, pH modulation, and surfactants have limited efficacy owing to the regrowth of bacteria, development of bacterial resistance, and difficulty in pH modulation. Improvements in anti-biofilm strategies involve current treatment modalities such as antimicrobial peptides, photodynamic substances, bacteriophages, quorum sensing inhibitors, nanoparticles, and hybrid hydrogels. Such strategies exhibit potent anti-biofilm effects upon topical application by targeting multiple mechanisms. However, the prospects of microbial resistance are still prevalent. Therefore, prospective strategies, such as Natural Deep Eutectic Solvents (NADES) and Clustered Regularly Interspaced Short Palindromic Repeats interfering system (CRISPRi), are required for effective anti-biofilm therapy of infected wounds.
Expert opinion
Strategies that completely eradicate biofilm-forming bacteria at wound sites can promote infection control and subsequent wound healing. Further developments in prospective strategies for topical anti-biofilm therapy for infected wounds are warranted. Our review provides valuable insights into the challenges and advancements in the treatment of biofilm-based wound infections, and highlights the need for ongoing research in this area.
A laboratory-made high-performance thin-film composite (TFC) forward osmosis (FO) membrane supported by a polyacrylonitrile (PAN) support was firstly employed to treat the effluent produced by an ...anaerobic fluidized bed bioreactor (AFBR). Synthetic wastewater was prepared to operate the AFBR, which produced the effluent for the FO process as post-treatment. The performance of the FO membrane was characterized via the measurement of the permeate flux, reverse salt (NaCl) flux and the rejection efficiency of ammonium nitrogen (NH4-N) mostly present in the AFBR effluent having low removal characteristics. An ultrathin and highly-crosslinked polyamide selective layer combined with the PAN support having a low structural parameter of the prepared PAN-supported TFC (PAN-TFC) membrane resulted in higher rejection to both nitrogen and salt compared to a commercial FO membrane. Importantly, the rejection of NH4-N higher than 70% was achieved by the PAN-TFC FO membrane. At 0.5 M NaCl draw solution, the PAN-TFC membrane exhibited the nitrogen flux of 0.92 ± 0.01 g m−2 h−1 and the permeate flux of 25 L m−2 h−1. The results demonstrate that the FO membrane can be one of the promising ways to effectively control the removal of contaminants present in AFBR effluent such as NH4-N as a post-treatment.
•Highly permselective thin-film composite forward osmosis membrane was developed.•New TFC-FO membrane was employed to treat the effluent from anaerobic fluidized bed bioreactor.•Highly cross-linked polyamide layer combined with PAN layer showed high salt rejection.•Rejection of nitrogen with PAN-TFC membrane was 50% higher than commercial FO membrane.•FO membrane can be integrated with AFBR to control ammonium nitrogen effectively.
The impacts of concrete on global warming through its use in structures such as buildings and infrastructure must be identified and better understood, as concrete is known to have a very high global ...warming potential (GWP). However, in contrast with ordinary on-site constructed reinforced concrete, GWPs of off-site factory-made prefabricated concrete products such as precast concrete (PC) and concrete piles that are widely used in construction are rarely evaluated, owing to the complicated manufacturing processes that make the determination of greenhouse gas emission difficult. In this study, the embodied life cycle GWPs were derived for PC and pretensioned spun high-strength concrete (PHC) piles to enable precise assessment of the global warming impact of concrete structures and the concrete industry of Korea. The determined embodied GWPs of PC and PHC piles were 1.77 × 10−1 kg CO2 eq/kg and 1.87 × 10−1 kg CO2 eq/kg, respectively. As a result, both prefabricated concrete products were determined to have high GWP due to input materials, such as cement rebars, while the GWP contributions of the off-site prefabrication processes were low. Moreover, the embodied GWPs of both prefabricated concrete products were significantly higher than those of ordinary reinforced concrete, and the impact of both products on global warming was found to be approximately 4% of the impact of the Korean concrete industry. This indicates that it is necessary to consider the impacts of the PHC pile and PC industries when assessing the impacts of greenhouse gas occurring in the concrete industry at the national level. It is expected that these findings will be widely used to obtain a more accurate assessment of the impact of concrete structures and industry on global warming.
•A SAF-MBR was operated to investigate removal efficiency of micropollutant.•More than 96% of overall COD removal was achieved at 8.7 h of total HRT.•Transmembrane pressure maintained less than 0.3 ...bar during reactor operation.•Diclofenac, ibuprofen and sulfamethoxazole were removed by SAF-MBR completely.•Biodegradation and sorption on GAC dominated organic removal pathways.
This study applied a laboratory-scaled, staged anaerobic fluidized bed membrane bioreactor (SAF-MBR) added with granular activated carbon (GAC) as fluidized media to treat a synthetic wastewater containing 0.1 mg/L of three different pharmaceutical micropollutants. Diclofenac, ibuprofen, and sulfamethoxazole were selected as target micropollutants to investigate their removal efficiency during SAF-MBR operation. More than 96% of overall COD removal efficiency was achieved at 8.7 h of total HRT with 288 mg/L of bulk VSS concentration. Transmembrane pressure (TMP) from membrane remained less than 0.3 bar during operational period. After the SAF-MBR was introduced with the micropollutants at 5 Lm−2 h−1 of permeate flux, they were removed completely within 3 days of operation. Our batch experiments supported that the removal of micropollutants in reactor bulk was immensely pronounced by adsorption to GACs, sorption and biodegradation due to the biofilm formed on GACs fluidized in SAF-MBR system.
The effects of operational conditions such as permeate recirculation velocity, mixing intensity, and trans-membrane temperature on the performances of hydrophobic polyethylene (PE) hollow-fiber ...membrane were investigated by operating the submerged direct contact membrane distillation (SDCMD) process treating a synthetic low-strength wastewater. Permeate flux of the membrane increased with increasing a permeate recirculation velocity through the fiber lumen. However, the effectiveness was less pronounced as the velocity was higher than 0.5 m/s. Increasing rotational speed to 600 rpm, which can lead to mixing intensity from a bulk wastewater toward hollow-fiber membrane, enhanced permeate flux. Feed temperature played a more significant role in enhancing permeate flux rather than a permeate temperature under constant trans-membrane temperature. The SDCMD process treating a synthetic low-strength wastewater achieved an excellent rejection efficiency which is higher than 97.8% for both chemical oxygen demand (CODCr) and total phosphorus (T-P) due to the hydrophobic property of membrane material which can allow water vapor through membrane. However, the rejection efficiency of the ammonia nitrogen (NH3-N) was relatively low at about 87.5% because ammonia gas could be volatized easily through membrane pores in SDCMD operation. In a long-term operation of the SDCMD process, the permeate flux decreased significantly due to progressive formation of inorganic scaling on membrane.
The effect of ozone dosage and hydrodynamic conditions on permeate flux in a hybrid ozonation–ceramic ultrafiltration membrane system treating natural water was studied. Ozone injection into the feed ...water upstream from the membrane module resulted in an increase in the permeate flux over a wide range of operational conditions. At the same ozone dosage, less fouling was observed at higher cross-flow velocities and lower transmembrane pressures (TMP). At lower ozone dosages, the effects of cross-flow velocity and TMP on the extent of fouling were less pronounced. Ozone transfer efficiency from the gas phase to the bulk liquid phase was found to be higher at higher ozone concentrations, cross-flow velocities and TMPs. The accessibility of foulants to ozone at the catalytic membrane surface is believed to be a key factor affecting fouling behavior. The reduction of fouling observed in the hybrid system is largely due to the reaction of ozone or secondary oxidants, such as
OH radical, with the foulants rather than to the effect of scouring by the bubbles present in the feed water. The total organic carbon (TOC) concentrations found in the retentate decreased with increasing ozone dosage. TMP and cross-flow velocity had little effect on retentate TOC levels.
The objectives in this study are to improve the performance of PVDF membrane by incorporating TiO2 and silane at various dosages and optimize fabricating conditions by using response surface ...methodology (RSM) for membrane distillation (MD) application. The PVDF membrane was synthesized by phase inversion method using various TiO2, silane and polymer concentrations. Membranes were characterized by performing contact angle measurements, SEM and FTIR observations. Ammonia rejection and permeate flux were measured by operating a direct contact distillation module treating ammonium chloride solution. A PVDF membrane created by adding TiO2 modified by silane improved membrane hydrophobicity. However, the effect of silane on membrane hydrophobicity was less pronounced at higher TiO2 concentrations. Highest ammonium rejection was associated with the highest membrane hydrophobicity. RSM analysis showed that fabricating conditions to achieve highest flux (10.10 L/m2·h) and ammonium rejection (100.0%) could be obtained at 31.3% silane, 2.50% TiO2, and 15.48% polymer concentrations. With a PVDF-TiO2 composite membrane for MD application, the effect of TiO2 was dependent upon silane concentration. Increasing silane concentration improved membrane hydrophobicity and ammonium rejection. RSM analysis was found to bea useful way to explore optimum fabricating conditions of membranes for the permeate flux and ammonium rejection in MD.
PDF