Steady-state modeling of bio-fouling potentials with respect to the biological kinetics in the submerged membrane bioreactor (SMBR)

A mathematical model was developed for predicting the membrane bio-fouling potential as the operation conditions in the submerged membrane bioreactor (SMBR). Mass balance equations were computed, in terms of biological kinetics, for the production and degradation of extracellular polymeric substances (EPS) and soluble microbial products (SMP). The modified fouling index (MFI) was used for the prediction of bio-fouling potentials divided by soluble materials (MFISol) and suspended solids (MFISS) at the steady-state. The effect of changes in the solids retention time (SRT) on the bio-fouling potentials was more sensitive than that of the hydraulic retention time (HRT). The MFISol and MFISS were found to increase and decrease, respectively, with increases in the SRT. The simulation results showed that an increased sludge age could decrease the microbial activity in the MBR. The MFISol was slightly decreased with increase in the HRT, which was due to the reduction of the concentrations of SMP. Generally, the contribution of MFISS to bio-fouling was relatively low compared to that of MFISol under given conditions. The simulation results were calculated using the given assumptions and limited conditions only. It was suggested that consideration of the parameter changes caused by the properties of biological flocs, influent, membrane and microorganism community would be required to better predict the bio-fouling potentials in the SMBR. (c) 2006 Elsevier B.V. All rights reservedclose363

Multi-Functional Laccase Immobilized Hydrogel Microparticles for Efficient Removal of Bisphenol A

Hghly stable, reusable, and multi-functional biocatalytic microparticles with Laccase (Lac) enzyme (Lac/particles) were synthesized for bisphenol A (BPA) removal from aqueous solution. The Lac/particles were prepared by encapsulating Lac enzymes into poly ethylene glycol (PEG) hydrogel via the UV assisted emulsion polymerization method followed by cross linking with glutaraldehyde (GA). The obtained Lac/particles were spherical and micron sized (137⁻535 μm), presenting high enzyme entrapment efficiency of 100%, high activity recovery of 18.9%, and great stability at various pHs (3⁻7) than the free Lac. The Lac/particles could adsorb the BPA into the catalytic particles in a short time, promoting contact between BPA and enzyme, and further enzymatically degrade them without the shaking process and independent surrounding buffer solution. The Lac/particles could be reused for another round BPA adsorption and biotranformation by maintaining over 90% of BPA removal efficiency after seven times reuse. The synergistic effects of adsorption and biocatalytical reaction of Lac/particles have significant values in high efficient and cost-effective BPA removal

Single-molecule RNA capture-assisted droplet digital loop-mediated isothermal amplification for ultrasensitive and rapid detection of infectious pathogens

Abstract To minimize and control the transmission of infectious diseases, a sensitive, accurate, rapid, and robust assay strategy for application on-site screening is critical. Here, we report single-molecule RNA capture-assisted digital RT-LAMP (SCADL) for point-of-care testing of infectious diseases. Target RNA was captured and enriched by specific capture probes and oligonucleotide probes conjugated to magnetic beads, replacing laborious RNA extraction. Droplet generation, amplification, and the recording of results are all integrated on a microfluidic chip. In assaying commercial standard samples, quantitative results precisely corresponded to the actual concentration of samples. This method provides a limit of detection of 10 copies mL−1 for the N gene within 1 h, greatly reducing the need for skilled personnel and precision instruments. The ultrasensitivity, specificity, portability, rapidity and user-friendliness make SCADL a competitive candidate for the on-site screening of infectious diseases

Characteristics of soluble microbial products and extracellular polymeric substances in the membrane bioreactor for water reuse

In biological treatment processes, the effluent contains some portion of organic material originating from soluble microbial products (SMP) that is closely related with extracellular polymeric substances (EPS), although the biological activity is maximized. These SMP should be considered important target materials if additional processes are necessary to satisfy the required water quality for the intended reuse. In this study, the characteristic of SMP and EPS were investigated using a submerged membrane bioreactor, which is one of the most promising water reuse process. Most protein SNIP in the reactor existed at a molecular weight (MW) above 10 kDa. Over 86% of the carbohydrate SMP contained in the permeate had a MW below 1 kDa. The protein and carbohydrate SMP in the permeate account for 83-91% of the COD. The MW of the protein and carbohydrate SMP in the reactor, when converted to COD showed a bimodal pattern (less than I kDa or greater than 10 kDa), but over 81 % of those in the permeate existed below I kDa due to the membrane rejection. The relative hydrophobicity of the protein and carbohydrate SMP was affected by the influent characteristics, and the hydrophobicity was decreased after the membrane filtration. The total EPS concentrations increased with increases in the food to microorganism ratio in this study. The modified fouling index (MFI) was used to investigate the biofouling characteristics, in terms of soluble and suspended solid parts closely related with the SMP and EPS, respectivelyclose657

Boron removal from seawater using NF and RO membranes, and effects of boron on HEK 293 human embryonic kidney cell with respect to toxicities

Boron (B) is an important element which should be considered seriously for drinking water production. Boron removal from seawater using nanofiltration (NF) and reverse osmosis (RO) membranes was investigated. Increase in salt concentration effects boron removal positively when RO membranes and negatively when NF membranes were used. Time dependencies of membrane processes for boron removal were also investigated. Based on the boron concentration in seawater and treated seawater, toxicity tests were conducted using Western Blotting method. HEK 293, human embryonic kidney cell line and antibodies, Bcl-2 and beta-actin were used for boron toxicity testsclose161