生物稳定聚氨酯材料研究进展

综述了聚氨酯生物材料的体内降解机理以及所谓的“生物稳定聚氨酯材料”的研究进展,并对其发展进行了展望。     

Improvement of treatment efficiency of thermophilic oxic process for highly concentrated lipid wastes by nutrient supplementation

The biodegradation of highly concentrated lipid wastes was conducted by a thermophilic oxic process (TOP). In order to improve the treatment efficiency of TOP, the stimulatory effect of nutrient supplementation was examined. A model nutrient supplement that satisfied the essential components necessary to promote degradation of lipid wastes was developed. The importance of balanced nutrient supplement consisting of organic and inorganic components was demonstrated. Regardless of the source of either vegetable oil or animal fat, the combination of 1.5 g of yeast extract, 1 g of urea and 60 ml of trace-element solution was effective to stimulate the degradation of 15 g of lipids by TOP. With this combination, degradation efficiencies of 68% and 77% in a 120-h treatment were attained for salad oil and lard, respectively. The conversion ratio of degraded lipid materials to CO2 was 0.91, confirming the advantage of TOP, i.e., very low excess sludge generation. The effectiveness of the model nutrient supplement for stimulating the degradation of lipid materials by TOP was also confirmed when tested on three kinds of actual highly concentrated lipid wastes. A constant degradation efficiency of around 60% in a 120-h treatment was attained for all lipid wastes although further improvement of degradation efficiency was possible by some nutrient addition into the model supplement combination. Based on the model nutrient supplement, the essential components for stimulating oil degradation by TOP and the possible alternative materials for the model nutrient supplement were discussed. The results demonstrated the possibility of employing TOP (stimulated by nutrient supplement) as a new biological treatment strategy for highly concentrated lipid wastes.     

垃圾填埋场中有机污染物的生物降解

概述了垃圾填埋场中微生物对污染物的吸收与生物化学作用，有机污染物的生物降解的基本原理及其影响因素，介绍了垃圾生物降解的四种基本动力学方程，提出了要重视我国在填埋场有机物降解机理方面的研究。     

Preliminary study of biodegradation of AZ31B magnesium alloy

Magnesium alloys are potential to be developed as a new type of biodegradable implant material by use of their active corrosion behavior. Both in vitro and in vivo biodegradation properties of an AZ31B magnesium alloy were investigated in this work. The results showed that AZ31B alloy has a proper degradation rate and much lower hydrogen release in Hank’s solution, with a degradation rate of about 0.3 mm/year and hydrogen release below 0.15 mL/cm². The animal implantation test showed that the AZ31B alloy could slowly biodegrade in femur of the rabbit and form calcium phosphate around the alloy sample, with the Ca/P ratio close to the natural bone.     

微生物及酶对己内酰胺的降解动力学研究

采用微生物菌株和从该菌株提取的粗酶液对己内酰胺进行降解，并对己内酰胺的降解动力学进行了研究．结果表明，初始己内酰胺的浓度越小，降解速率常数越大，半寿期越短，微生物的降解能力越强；由微生物提取的粗酶液（胞外酶）的Km值较小，对己内酰胺有较强的亲和力，可有效地降解己内酰胺。     

Effect of Sediment on the Biodegradation of Petroleum Contaminants in Natural Water

Biodegradation of petroleum contaminants in natural water was studied within an Asian river context where high-suspended sediment content exists. Petroleum contaminant is one of the main pollutants in the Yellow River; at the same time, there is a high sediment content in the river system. This research highlighted the effect of sediment on the biodegradation of petroleum contaminants, as well as the related mechanisms regarding the effect. Biodegradation of petroleum contaminants was studied under different sediment contents. The distribution of petroleum contaminants in water and sediment phases as well as the relevant biodegradation kinetics were also investigated. The results showed that in water system with the sediment content of 0.5 g/L, about 84% of petroleum contaminants with the initial concentration of 11.64 mg/L could be degraded after incubation for 63 days at 20°C. It was also indicated that the presence of sediment exerted significant influences on the biodegradation of petroleum contaminants in water system, and the influences were different from one cultivation stage to another. In the first stage, the biodegradation rate was higher in the water system with sediment than in that without sediment. In the second stage, the biodegradation rate was lower in the former than in the latter. In the last stage, the biodegradation rate was higher in the water system with sediment than in that without sediment. The presence of sediment could stimulate the growth of petroleum contaminant-degrading bacteria. Moreover, about 90% of the contaminants and bacteria were attached on the sediment. The sorbed contaminants on sediment could also be biodegraded by bacteria. The biodegradation of contaminants in water and sediment phases all fit well with the first-order kinetics, and the biodegradation rate constant in water phase was higher than that in sediment phase. However, as the contaminant concentration at the sediment phase was much higher than that in water phase, the biodegradation of petroleum contaminants mainly occurred at the sediment phase.     

Immobilization of polyphenol oxidase on alginate–SiO2 hybrid gel: stability and preliminary applications in the removal of aqueous phenol

An organic/inorganic hybrid gel of alginate–SiO₂ (ALG–SiO₂) was used to immobilize the partially purified potato polyphenol oxidase (PPO) for the treatment of phenolic wastewater. The influences of alginate concentration, quantity of both enzyme and tetramethoxysilane (TMOS) on immobilization were investigated. The Michaelis constant for immobilized PPO was determined as 14.7 mmol L⁻¹ at 25 °C, and the highest activity of immobilized PPO was achieved at pH 7.0. The ALG–SiO₂ immobilized PPO was more stable than the free PPO or ALG(alone) immobilized PPO. This study suggests that ALG–SiO₂ immobilized PPO might be a potential tool for the removal of phenolic compounds from industrial wastewater. Copyright © 2008 Society of Chemical Industry     

Influence of the hydrophilic moiety of anionic and nonionic surfactants on their aerobic biodegradation in seawater

The extent and kinetics of the primary biodegradation have been characterized for the most commonly-used surfactants, employing four homologues with the same alkyl chain: dodecyl ethoxy sulfate (C₁₂AES), sodium dodecyl sulfate (SDS), dodecyl alcohol ethoxylate (C₁₂AEO) and dodecyl benzenesulfonate (C₁₂LAS). A brief acclimatization period has been required to enable an effective degradation of C₁₂LAS and C₁₂AES to take place, but this lag phase has not been detected for SDS and C₁₂AEO. Primary biodegradation percentages at the end of these experiments were higher than 99%, showing a fast degradation rate in all cases (average half-life lower than 2 days). The secondary biodegradation of C₁₂LAS was also monitored. C₁₂LAS external isomers, which are predominant, are preferentially degraded by successive β-oxidations, generating significant amounts of external even isomers of sulfophenylcarboxylic acid (SPC) (mainly 2,3ΦC_4,6SPCs). In ontrast, internal isomers are converted into internal odd isomers of SPC (mostly 4,5ΦC_5,7SPCs) by ω-oxidation followed by α-oxidation and/or β-oxidations.     

Biodegradation kinetics of benzene,methyl tert‐butyl ether,and toluene as a substrate under various substrate concentrations

Owing to the complexity of conventional methods and shortcomings in determining kinetic parameters, a convenient approach using the nonlinear regression analysis of Monod or Haldane type nonlinear equations is presented. This method has been proven to provide accurate estimates of kinetic parameters. The major work in this study consisted of the testing of aromatic compound‐degrading cultures in batch experiments for the biodegradation of benzene, methyl tert‐butyl ether (MTBE), and toluene. Additionally, batch growth data of three pure cultures (i.e., Pseudomonas aeruginosa YAMT421, Ralstonia sp. YABE411 and Pseudomonas sp. YATO411) isolated from an industrial petrochemical wastewater treatment plant under aerobic conditions were assessed with the nonlinear regression technique and with a trial‐and‐error procedure to determine the kinetic parameters. The growth rates of MTBE‐, benzene‐, and toluene‐degrading cultures on MTBE, benzene, and toluene were significant. Monod's model was a good fit for MTBE, benzene and toluene at low substrate concentrations. In contrast, Haldane's equation fitted well in substrate inhibition concentration. Monod and Haldane's expressions were found to describe the results of these experiments well, with fitting values higher than 98%. The kinetic parameters, including a maximum specific growth rate (µ_m), a half‐saturation constant (K_s), and an inhibition constant (K_i), were given. Copyright © 2007 Society of Chemical Industry     

Simultaneous degradation of atrazine and simazine by a binary culture of Stenotrophomonas maltophilia and Arthrobacter sp. in a two‐stage biofilm reactor

BACKGROUND: The impact of mixtures of chloro‐triazinic herbicides, such as atrazine and simazine, on aquatic ecosystems is of environmental concern. To study their biodegradation under various operational conditions, a binary community comprising Stenotrophomonas maltophilia and Arthrobacter sp. attached to the porous support of a packed bed reactor, was evaluated. RESULTS: The genetic analysis of the two atrazine‐degrading strains revealed that genes atzA, atzB, atzC are present in both bacteria, but only S. maltophilia possess atzD. Thus, by cultivating Arthrobacter sp. on these herbicides, cyanuric acid accumulation was observed. When the binary community was cultivated in the biofilm reactor, at all the loading rates probed, both herbicides were entirely removed. However, complete biodegradation of cyanuric acid was not achieved. CONCLUSIONS: Even with a two‐stage reactor, cyanuric acid was only partially removed. This fact could be attributed to the absence, in the second stage, of an easily degradable energy source, required by S. maltophilia for the uptake and cometabolic degradation of the recalcitrant heterocyclic ring. Responding to differences in nutritional conditions prevailing at each reactor stage, local differences in species' predominance were clearly detected by microbiological and molecular biology methods. Copyright © 2010 Society of Chemical Industry