Improvement of the activated sludge treatment by its combination with electro Fenton for the mineralization of sulfamethazine

A combined process coupling an electro-Fenton pretreatment and a biological degradation in order to mineralize sulfamethazine (SMT) was investigated. The electro-Fenton pretreatment of SMT was first examined and the intermediates products were identified for an initial SMT amount of 0.36 mM, after 1 h electrolysis at pH 3, 18 °C, 200 mA. 94.2% SMT was degraded but the level of mineralization remained low (6.5%), ensuring significant residual organic content for a subsequent biological treatment. Two possible degradation reaction pathways involving all the identified and quantified intermediates are proposed. In a second part, biological treatments with fresh activated sludge were performed to complete the mineralization of the electrolyzed solution of SMT, showing an increase of the mineralization yield with time duration of the pretreatment. For an initial SMT concentration of 0.2 mM, a ferrous ions concentration of 0.5 mM, at pH 3, 18 °C and 500 mA, the mineralization yield during the biological treatment increased as follows: 61.4, 78.8 and 93.9% for 0.5, 1 and 4 h pretreatment, confirming the relevance of the proposed combined process.     

Biodegradation of oil sands process affected water in sequencing batch reactors and microbial community analysis by high-throughput pyrosequencing

Two sequencing batch reactors (SBR) were constructed and filled with different inocula of activated sludge (AS) and mature fine tailings (MFT) to treat oil sands process-affected water (OSPW). The COD was reduced by 82% in the AS-SBR and 43% in the MFT-SBR during phase I using 10% OSPW and 90% synthetic wastewater as reactor feed. However, COD removal reached 12% and 20% in the AS-SBR and the MFT-SBR, respectively, when 100% raw OSPW was fed into the reactors. Maximum removal of acid-extractable organics (AEO) was 8.7% and 16.6% in the AS-SBR and the MFT-SBR, respectively with a hydraulic retention time of one day. Pyrosequencing analysis revealed that Proteobacteria was the dominant phylum and beta- and gamma-Proteobacteria were dominant classes in both reactors. Evidence of a microbial community change was observed when influent raw OSPW was switched from 50 to 100%. More significant changes in the AS-SBR community were detected.     

Design,synthesis, and SAR of a series of activated protein C (APC) inhibitors with selectivity against thrombin for the treatment of haemophilia

A design strategy was used to identify inhibitors of activated protein C with selectivity over thrombin featured by a basic and/or aromatic functionality for binding to the S2 pocket. Our strongest inhibitor showed an IC₅₀-material value and selectivity for APC vs thrombin similar to a compound previously reported in the literature. However, in contrast to the reference compound, our compound showed a retained coagulant effect of thrombin with increasing substrate concentration in a modified Calibrated Automated Thrombogram (CAT) method. This was likely related to our compound being inactive against FVIIa, while the reference compound showed an IC₅₀ of 8.9 μM. Thus, the higher selectivity of our compound against all relevant coagulation factors likely explained its higher therapeutic potential in comparison to the reference compound. The data indicate that at least a 100-fold selectivity over other serine proteases in the coagulation cascade will be required for an effective APC inhibitor.     

Effect of continuous Cd feeding on the performance of a nitrification reactor

The inhibitory effect of Cd on nitrification was investigated in a continuous-flow system with enriched nitrifying bacteria. The maximum specific ammonium utilization rate and the half-saturation constant were found as 671 mg NH₄–N/g VSS day and 0.48 mg/l, respectively. In the case of continuous Cd input at 1 and 2.5 mg/l, nitrification was inhibited by 30% and 47%, respectively. Inhibition ranged from 20% to 40% and no further increase in inhibition was exhibited in new runs except at 10 mg/l influent Cd. At 10 mg/l influent Cd, specific ammonium utilization and nitrate production rates were inhibited by 90%. On the contrary, a serious nitrite accumulation was not observed during this period. When Cd feeding was stopped, recovery from inhibition was observed after 37 day which was seen by the improvement in ammonium utilization and nitrate production rates. A shift in microbial population from the initial Nitrosomonas sp. to the Cd-tolerant Nitrosospira sp. was observed in the recovery period from severe Cd inhibition. After the domination of Nitrosospira species, redosing at 10 mg/l and then at 15 mg/l did not affect the performance as before.     

Cloning and analysis of the polyhydroxyalkanoic acid synthase gene from an Acinetobacter sp.: Evidence that the gene is both plasmid and chromosomally located

Abstract The polyhydroxyalkanoic acid (PHA) synthase gene ( phaC_Ac ) of a species of Acinetobacter isolated from an activated sludge treatment plant was cloned by heterologous complementation in a poly-β-hydroxybutyrate (PHB) negative mutant of Alcaligenes eutrophus . Nucleotide sequence analysis of phaC_Ac revelaed an open reading frame of 1770 bp with potential to encode a 67.7 kDa protein. The deduced amino acid sequence displays high similarity to other PHA synthase proteins. Probing with an internal region of phaC_Ac revealed that the PHA sythase gene may be present in more than one copy and may occur at both plasmid and chromosomal locations in Acinetobacter spp. This is the first organisms for which evidence has been presented to suggest that a gene involved in PHA metabolism is plasmid-encoded. Purification of PHB granules from sucrose gradients identified proteins of 38 kDa, 41 kDa and 64 kDa which may have a role in PHB metabolism.     

The origin of polynucleotide-directed protein synthesis

Summary If protein synthesis evolved in an RNA world it was probably preceded by simpler processes by means of which interaction with amino acids conferred selective advantage on replicating RNA molecules. It is suggested that, at first, the simple attachment of amino acids to the 2′(3′)-termini of RNA templates favored initiation of replication at the end of the template rather than at internal positions. The second stage in the evolution of protein synthesis would probably have been the association of pairs of charged RNA adaptors in such a way as to favor noncoded formation of peptides. Only after this process had become efficient could coded synthesis have begun.     

Degradation of 17β-estradiol and its conjugates: Effects of initial concentration and MLSS concentration

There have been many strong retrospective observations regarding adverse effects in reproductive and fertile developments in human and the wildlife caused by the endocrine disrupting compounds (EDCs) present in the aquatic environment recently. Degradation by biomass is one of the main removal mechanisms for 17β-estradiol (E2), the most important EDC, and its conjugates from sewage in wastewater treatment plants. In this batch study, the degradation rates of E2 and its conjugates were found to be affected by initial concentration of concerned pollutants and mixed liquor suspended solids (MLSS) concentration of activated sludge tested. Quantitative analysis was performed by liquid chromatography tandem mass spectrometry (LC-MS-MS). Overall, Michaelis–Menten Model adequately described the degradation of E2 and its conjugates over the range of the initial concentrations and MLSS concentrations tested. The degradation rates increased with the increase of initial concentration and MLSS concentration.     

微生物群落结构探针杂交评价不同培养基从活性污泥分离优势菌群的能力

用ERICPCR （Enterobacterial Repetitive Intergenic ConsensusPCR）、苯酚羟化酶大亚基基因(LmPHs)扩增和群落结构探针分子杂交检测技术对LB、dCGY、MP和FWM 4种培养基从焦化废水处理厂2个曝气池活性污泥中分离优势功能菌群的能力进行了比较研究。LmPHs扩增显示7种回收菌群中均有以多亚基苯酚羟化酶为代谢途径的苯酚降解菌存在。用代表苯酚降解高峰期活性污泥优势菌组成的总DNA的ERICPCR产物经地高辛标记作为群落结构的混合探针M1和M8,对8种回收菌群的ERICPCR指纹图谱进行杂交检测,不同培养基回收优势菌的能力不同,以废水为基础的FWM培养基从活性污泥中回收到的优势菌种群最多(30.8%～42.9%)。本文建立了用微生物群落结构探针杂交技术对不同培养基回收分离优势菌能力进行评价的方法。     

Improved performance of membrane free single-chamber air-cathode microbial fuel cells with nitric acid and ethylenediamine surface modified activated carbon fiber felt anodes

Surface modifications of anode materials are important for enhancing power generation of microbial fuel cell (MFC). Membrane free single-chamber air-cathode MFCs, MFC-A and MFC-N, were constructed using activated carbon fiber felt (ACF) anodes treated by nitric acid and ethylenediamine (EDA), respectively. Experimental results showed that the start-up time to achieve the maximum voltages for the MFC-A and MFC-N was shortened by 45% and 51%, respectively as compared to that for MFC-AT equipped with an unmodified anode. Moreover, the power output of MFCs with modified anodes was significantly improved. In comparison with MFC-AT which had a maximum power density of 1304 mW/m², the MFC-N achieved a maximum power density of 1641 mW/m². The nitric acid-treated anode in MFC-A increased the power density by 58% reaching 2066 mW/m². XPS analysis of the treated and untreated anode materials indicated that the power enhancement was attributable to the changes of surface functional groups.     

Biological Rhythms in the Physiology and Pharmacology of Blood Coagulation

This article reviews the current knowledge on time-dependent variations in the physiology of blood coagulation and in the anticoagulant effect of heparin and warfarin. Animal data indicated that the shortest blood clotting time and the highest levels of coagulation factors II, VII, and IX were recorded during the resting period of the animal. These circadian rhythms were not altered by modifications of the lighting regimens. In healthy volunteers, the prothrombin time was longer at the end of the afternoon than early in the morning; the acro-phases of activated partial thromboplastin time and thrombin time occurred in the evening or during the night. The acrophases of fibrinogen, factors II, VII, VIII, and a-1-antitrypsin were obtained in the morning. There is no agreement on the chronobiology of platelet aggregation, and differences can be found in the time of maximal aggregability. The chronopharmacological studies of heparin infused at a constant rate to patients with thromboembolic diseases suggested that maximal effectiveness occurred at 04:00, while it was minimal at 08:00. Animal data indicated that oral administration of warfarin at the end of the activity period of rats produced maximal inhibition of vitamin K-dependent factors. This was the time of day when warfarin interference with the vitamin K cycle of the liver was highest. Further studies are needed to determine the clinical significance of biological rhythms in the physiology and pharmacology of blood coagulation.