The Effect of Preozonation on the Anaerobic Biodegradability of Resistant Phenolic Compounds

Ozone pretreatment studies of four model phenolic compounds were conducted to evaluate the effects of ozonation on the anaerobic biodegradability and toxicity of these compounds. Two types of batch studies, the Biochemical Methane Potential (BMP) and the Anaerobic Toxicity Assay (ATA), were performed on samples ozonated upon phenol, o-cresol, 2,5-dichlorophenol, and 2,4-dinitrophenol. Experimental results showed that toxic and refractory phenolic compounds were converted to methane gas by means of preozonation. In general, the biodegradable fraction of the oxidation products increased as the ozone dose was increased. However, ozonation to achieve at least 60% COD reduction was necessary to faciliate methane production. Ozonation reduced the toxicity of 2,5-DCP and 2,4-DNP on both acetate utilization and phenol degradation. The early ozonation products of o-cresol and phenol, however, were more toxic than the initial compounds. The rates of COD and DOC reduction through ozonation were faster and products formed were less inhibitory in the basic pH range than in the acid pH range

Effects of Aromatic Concentration on Methane Fermentation

The anaerobic biodegradability and toxicity of fourteen aromatic compounds were evaluated over a wide range of concentrations using a serum bottle technique. Benzene, toluene, and all three isomers of xylene were not significantly degraded to methane in a phenol-enriched culture. Complete degradation of 1000 mg/L phenol, 800 mg/L catechol, 100 mg/L 2-NP, 100 mg/L 3- NP, and 100 mg/L 4-NP was observed within two months while depletion of 100 mg/L resorcinol and 1000 mg/L hydroquinone required more than six and eight months incubation, respectively. None of the three isomers of chlorophenol were degraded in the phenol-enriched culture. Batch toxicity assay revealed that the phenol-enriched culture was more susceptible to inhibition caused by substituted phenols than the acetate-enriched culture. In general, the inhibitory effects on both phenol degradation and acetate utilization did not vary significantly with the isomer but rather with the substituted group. The degree of inhibition was in the order of nitrophenols \u3e chlorophenols \u3e hydroxyphenols. The Haldane inhibition model was used to fit experimental data from phenol and catechol. The inhibition of phenol degradation by chlorophenols, resorcinol, and hydroquinone was described rather well by a Monod-type, noncompetitive model

Letter to the Editor: Authors’ Response

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141389/1/jper1035.pd

Modulation of Serum Antinuclear Antibody Levels by Levamisole Treatment in Patients With Oral Lichen Planus

Background/PurposeSerum autoantibodies, including antinuclear antibodies (ANAs), have been found in patients with oral lichen planus (OLP). This study evaluated whether Taiwanese OLP patients had significantly higher frequencies of serum ANAs than healthy control subjects, and whether levamisole treatment could modulate the antibody levels.MethodsThis study used an indirect immunofluorescence technique to measure the baseline serum levels of ANA in a group of 583 Taiwanese OLP patients and 53 healthy control subjects. Seventy-nine ANA-positive OLP patients were treated with levamisole under a regular follow-up schedule in our dental clinic, and their serum ANA levels were measured after treatment.ResultsWe found that the frequencies of serum ANA in patients with OLP (23.2%), erosive OLP (EOLP, 23.8%), major EOLP (31.5%), and minor EOLP (18.1%) were all significantly higher than that (5.7%) in healthy control subjects. In addition, major EOLP patients had a significantly higher serum ANA positive rate than minor EOLP or non-erosive OLP patients. Of 135 ANA-positive OLP patients, 79 were treated with levamisole under a regular follow-up schedule. We found that treatment with levamisole for a period of 2–38 months (mean, 12 ± 9 months) effectively reduced the high mean serum ANA titer (557 ± 98) at baseline to an undetectable level (0) in all ANA-positive OLP patients, regardless of different high initial serum titers of ANA.ConclusionThere was a significantly higher frequency of serum ANA (23.2%) in Taiwanese OLP patients than in healthy control subjects. Treatment with levamisole for 2–38 months reduced the high serum ANA to an undetectable level, and significantly improved the signs and symptoms in all treated OLP patients

A novel fouling control strategy for forward osmosis membrane during sludge thickening via self-forming protective layer

Severe membrane fouling significantly limited forward osmosis (FO) process for sludge thickening (FST). Here, a novel antifouling strategy by loading a self-forming protective layer on FO membrane surface was proposed in this study. The protective layer was coated on FO membrane surface via a short-term FO process using activated sludge as the feed solution. Results indicated that the self-forming protective layer made FO membrane surface more negatively charged and more hydrophilic. As for the control FO (C-FO) membrane, the water flux decreased approximately 66% of the initial flux in Cycle 2 of FST process and thus resulting in the sludge concentration only increased to 40 g/L. In contrast, the flux decline rate of modified FO (M−FO) membrane was about 22%, and the corresponding sludge concentration still rose to 50 g/L. It suggested that the M−FO membrane with a protective layer had a better sludge thickening efficiency and a lower flux decline during sludge thickening compared to the C-FO membrane. Furthermore, less deposited foulants and better fouling reversibility were observed for M−FO membrane after two cycles of sludge thickening, implying that the protective layer effectively mitigated FO membrane fouling during sludge thickening. This phenomenon could be attributed to the excellent barrier effect of the protective layer and the enhanced surface hydrophilicity and negative charge, which improved the antifouling performance of the FO membrane. The findings of this study were conducive to better understanding of FO membrane fouling mechanisms and further development of fouling mitigation strategy via a protective layer.</p

A novel fouling control strategy for forward osmosis membrane during sludge thickening via self-forming protective layer

Severe membrane fouling significantly limited forward osmosis (FO) process for sludge thickening (FST). Here, a novel antifouling strategy by loading a self-forming protective layer on FO membrane surface was proposed in this study. The protective layer was coated on FO membrane surface via a short-term FO process using activated sludge as the feed solution. Results indicated that the self-forming protective layer made FO membrane surface more negatively charged and more hydrophilic. As for the control FO (C-FO) membrane, the water flux decreased approximately 66% of the initial flux in Cycle 2 of FST process and thus resulting in the sludge concentration only increased to 40 g/L. In contrast, the flux decline rate of modified FO (M−FO) membrane was about 22%, and the corresponding sludge concentration still rose to 50 g/L. It suggested that the M−FO membrane with a protective layer had a better sludge thickening efficiency and a lower flux decline during sludge thickening compared to the C-FO membrane. Furthermore, less deposited foulants and better fouling reversibility were observed for M−FO membrane after two cycles of sludge thickening, implying that the protective layer effectively mitigated FO membrane fouling during sludge thickening. This phenomenon could be attributed to the excellent barrier effect of the protective layer and the enhanced surface hydrophilicity and negative charge, which improved the antifouling performance of the FO membrane. The findings of this study were conducive to better understanding of FO membrane fouling mechanisms and further development of fouling mitigation strategy via a protective layer.</p

Introduction of an Aliphatic Ketone into Recombinant Proteins in a Bacterial Strain that Overexpresses an Editing-Impaired Leucyl-tRNA Synthetase

Like leucine? A leucine analogue containing a ketone has been incorporated into proteins in E. coli. Only E. coli strains overexpressing an editing-deficient leucyl-tRNA synthetase were capable of synthesizing proteins with the aliphatic ketone amino acid. Modification of ketone-containing proteins under mild conditions has been demonstrated

Effects of a Mineralized Human Cancellous Bone Allograft in Regeneration of Mandibular Class II Furcation Defects

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141918/1/jper0416.pd