Abstract
In the membrane bioreactor (MBR) process, problems such as performance deterioration due to membrane fouling, Excessive energy and chemical usage. This study aimed to develop a cell-entrapping carrier (CEC) using the quorum quenching (QQ) mechanism to inhibit fouling in MBR reactors. And this study aimed to develop a strategic plan for mitigating biofouling and reducing operational costs through the application of QQ-CEC. A solution comprising polyvinyl alcohol (PVA) and sodium alginate (SA) with Rhodococcus sp. BH4 was subjected to 1st and 2nd cross-linking reactions to complete CEC formation and evaluated its physical performance. Subsequently, definiting three types of conventional MBR with no CEC (cMBR), vacant-CEC (vMBR) and QQ-CEC (QMBR) were operated to investigate the carrier effect. The QMBR extended the operation duration to reach permissible TMP by more than 2.54 times that of the MBR and 1.35 times that of the vMBR. Furthermore, it has been established that biofouling can be mitigated through the application of QQ, resulting in a reduction of chemical usage by approximately 39.2%. Following operation of the QMBR, confirming that QQ-CEC inhibited biofouling. The extracellular polymeric substances (EPS) generated on the membrane surface was found to be 0.32 mg.L-1.day-1 per cumulative permeate volume that was less than 4 times and 2 times lower compared to the cMBR and vMBR. However, no significant differences in effluent quality were observed, as QQ did not have a substantial impact on the alterations in microbial communities. This study addresses membrane bioreactor (MBR) fouling and optimizes process operations, thereby establishing a foundation for scale-up.
Key Words
biofouling; cell entrapping carrier; EPS; MBR; quorum quenching; TMP
Address
Hyeonwoo Choi, Youjung Jang and Heekyong Oh: Department of Environmental Engineering, University of Seoul, 163 Seoulsiripdaero, Dongdaemun-gu, Seoul 02504, Republic of Korea
Shinho Chung: Department of Environmental Science, Forman Christian College (A Chartered University), Ferozepur Road, Lahore, Punjab, 54600, Pakistan
Abstract
The potential for the removal of nitrogen, phosphorus, and heavy metals such as copper and nickel by Rhodobacter blasticus known as purple non-sulfur bacteria was evaluated in this study. In addition, the resistance of R. blasticus to two heavy metals and the effects of these metals on its cell morphology were investigated. The heavy metal adsorption characteristics by R. blasticus were confirmed using Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX) and Fourier Transform Infrared Spectroscopy (FT-IR). The nitrogen and phosphorus removal efficiencies of R. blasticus decreased as the concentration of nitrogen and phosphorus increased from 50 to 500 mg/L. The resistance, based on the minimum inhibitory concentration of R. blasticus growing under aerobic-light conditions, was found to be in the order of Ni2+ > Cu2+. SEM analysis revealed that copper ions altered the morphology of R. blasticus, while nickel treatment did not differ from the control group. Futhermore, this study confirmed that the removal efficiencies for Cu2+ and Ni2+ by R. blasticus were 53
Key Words
adsorption; bioremediation; heavy metals; nutrients; Rhodobacter blasticus
Address
Eunji Oh: Urban Research Division, Korea Research Institute for Human Settlements, Sejong 30147, Republic of Korea
Deok-Won Kim: Department of Earth Resources and Environmental Engineering, Hanyang University, Seoul 04763, Republic of Korea
Jong-Geon Oh and Keun-Yook Chung: Department of Environmental and Biological Chemistry, Chungbuk National University, Cheongju 28644, Republic of Korea
Deok Hyun Kim: National Institute of Chemical Safety, Cheongju 28164, Republic of Korea
Sunhwa Park: National Institute of Environmental Research, Incheon 22689, Republic of Korea
Abstract
This paper reports the synthesis and use of a novel metal-organic framework (MOF), named Zr-BADS, within the thin-film nanocomposite (TFN) membranes for reverse osmosis (RO) applications. Two types of zirconium-based MOFs, Zr-BADS-1 and Zr-BADS-2, were synthesized via a solvothermal method using bicinchoninic acid disodium salt as a linker and either dimethylformamide or ethanol as solvent, respectively. TFN membranes were prepared by embedding these MOFs within the polyamide thin film supported by a polysulfone support sheet. The specific surface area of Zr-BADS-1 and Zr-BADS-2 was determined to be 396.1 and 278.6 m2/g, respectively, indicating significant surface area conducive to water permeation. Scanning electron microscopic analysis revealed a uniform distribution of Zr-BADS nanoparticles (NPs) with particle sizes < 100 nm within the TFN membranes. TEM images confirmed the dense packing of NPs within the membranes, influencing their texture and enhancing performance. FTIR spectroscopy demonstrated the presence of characteristic peaks corresponding to MOFs within the TFN membranes, with changes observed at higher loading ratios. The observed contact angle decreased with increasing MOF loadings, indicating an enhancement in the hydrophilicity. Zr-BADS-1 NPs increased water flux at its optimal loading of 0.3%, and the flux raised to 5.4 L/m2 h bar. Salt rejection slightly decreased at low concentrations but improved at higher loading ratios, indicating the interplay between porosity and charge effects. Zr-BADS-1 outperformed other MOFs in salt rejection and water flux, suggesting it is a remarkable RO membrane filler. This study demonstrates the potential of Zr-BADS MOFs for future membrane applications in the environment.
Key Words
desalination; MOFs; reverse osmosis; TFN membranes; water treatment
Address
Mohammed Kadhom: Department of Environmental Science, College of Energy and Environmental Science, Alkarkh University of Science, Baghdad, 10081, Iraq
Noor Albayati: Department of Chemical Engineering, College of Engineering, University of Baghdad, Baghdad, 10071, Iraq
Alaa E. Sultan: Department of Chemistry, College of Science, University of Diyala, Baquba, 32001, Diyala, Iraq
Mudhar A. Al-Obaidi: Technical Institute of Baquba, Middle Technical University, Baquba, Diyala, 32001, Iraq
Suhaib Salih: Department of Chemical Engineering, College of Engineering, Tikrit University, Tikrit, Saladin, 34001, Iraq
Baolin Deng: Department of Civil and Environmental Engineering, College of Engineering, University of Missouri-Columbia, Columbia, MO, 65211, United States
Abstract
Cyanobacteria are the primary culprits responsible for deteriorating the health of aquatic ecosystems in lakes or rivers. Nitrogen concentration is a crucial factor affecting the synthesis of cellular contents, which, in turn, influence the growth of cyanobacteria. This study focused on the growth and morphological characteristics of Anabaena sp., a representative filamentous cyanobacteria, depending on nitrate concentrations varying from 0.5 to 20.0 mg N/L. As the nitrate concentration increased, the filament density, optical density (OD680), cellular protein content proportionally increased. While growing, both nitrate and phosphate concentration depleted, notably affecting the cell compositions in filament: akinete, vegetative, and heterocyst cell. When nitrate concentration was exhausted, the heterocyst cell density of Anabaena sp. increased to supplement nitrogen through nitrogen fixation, whereas vegetative cell density kept increasing as long as nitrate remained. Morphological changes in akinete and heterocyst cells in Anabaena sp. were less affected by nitrogen concentration, whereas those in vegetative cells were affected by both growth state and nitrogen concentration. The close relationship between heterocyst cells and nitrogen concentration suggests that heterocyst cell can be used to characterize Anabaena growth responding to nitrogen loading, as well as provide an important information on nitrogen level affecting Anabaena bloom potential.
Key Words
Anabaena sp.; cyanobacteria; growth; heterocyst; nitrogen; phosphorus
Address
Dandan Dong, Hyeonjeong Jeong and Jae Woo Lee: Department of Environmental Engineering, Korea University, 30019, Republic of Korea
Abstract
The growing demand for high-quality freshwater makes seawater desalination essential. However, effective pretreatment is crucial to protect reverse osmosis membranes and ensure long-term efficiency. This study, conducted at the SORFERT complex, evaluates the performance of multimedia filtration by characterizing sand and Filtralite
Key Words
desalination; filtralite
Address
Naoual Bensaad and Khadidja Benyahia: Department of Process and Materials Engineering, National Polytechnic School, Oran, Algeria/ Physics-Chemistry Laboratory of Catalysis and Environment Materials, USTO, Algeria
Boumediene Haddou: Physics-Chemistry Laboratory of Catalysis And Environment Materials, USTO, Algeria/ Faculty of Chemistry, USTO, Algeria
Nour E. Badrane: Department of Process and Materials Engineering, National Polytechnic School, Oran, Algeria
Hanane Badid: Physics-Chemistry Laboratory of Catalysis and Environment Materials, USTO, Algeria
