Papers by Keyword: Biodegradation

Abstract: The oily sludge was more serious polluted to the environment, it is necessary to harmless treatment. Analysised the composition of the oily sludge. Three ways to deal with oily sludge included chemical treatment, biological degradation and resource utilization. Elaborated the application of three ways, dicussed the pros and cons, thought waste utilization was the most effective way.

Abstract: Twelve strains belonging to the genus Cordyceps were investigated for their ability to degrade organochlorine pesticide dieldrin. Based on the screening results, we further investigated Cordyceps militaris KS-92 and Cordyceps brongniartii ATCC66779 to determine their degradation capacity and metabolic products towards dieldrin. C. militaris KS-92 and C. brongniartii ATCC66779 removed about 45% and 36% of dieldrin in PDB medium, respectively, after 28 days of incubation. A hydrolysis product, 6,7-dihydroxydihydroaldrin, was detected as a initial metabolite of dieldrin in both fungal cultures using GC/MS analysis. C. militaris KS-92 particularly can degrade dieldrin to dihydrochlordenedicarboxylic acid through oxidation of 6,7-dihydroxydihydroaldrin or directly oxidation of dieldrin. The results suggested that dieldrin was metabolized to hydrophilic/low-toxicity products by selected fungi.

Abstract: One strain of Candida L-2, capable of degrading azo dyes 4,5-Diamino-1-pyrazole sulfate, was isolated from a lab-scale sequence biological reactor (SBR) sludge treating textile effluent. The isolate was identified as Candida rugopelliculosa according to its physiological characteristics, biochemical tests, and 26S rDNA D1/D2 gene phylogenetic analysis.

Abstract: The experiment introduce the performance of orange oil cleanser containing natural orange oil, sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether and alcohol that selected in the best ratio by uniform experimental design method, using the stiring-emulsification method to make a cleanser solution of compounded system at normal temperature, and measured the surface tension. We found that with the content of sodium dodecyl sulfate and alcohol increasing, the surface tension reduced significantly, the cleaning effect improved too. The orange oil cleanser with best formula of sodium dodecyl sulfate -14.2 (mass ratio), fatty alcohol polyoxyethylene ether -2.7(mass ratio), Ethanol-5.1(mass ratio), 22 in total, orange oil-10 ml, contributing the surface tension of 17.8 can be completely biodegraded.

Abstract: Polyethylene (PE) has found widespread use as a packaging material. Plastics waste disposal, as one of the serious environmental issues, has caused much criticism. The environmental oxidative- and bio- dual degradable linear low-density polyethylene (LLDPE) samples containing Eco-Benign Plastics (EBP) pro-oxidant additives were submitted to an investigation aimed at evaluating their preliminary oxidative degradation in natural environment or accelerated oven aging and their ultimate biodegradation in solid incubation substrate or soil composting conditions. Original and test samples submitted to abiotic oxidation including photo degradation and thermal degradation were characterized by means of FT-IR and GPC. Biodegradation test simulating soil burial and composting conditions reveals that the biodegradation degree exceeded 30%. The degradation process is accompanied by a dramatic change in the structural characteristics of the test samples. It is clear that LLDPE-EBP formulations are effective in promoting the oxidation and subsequent biodegradation of polyethylene in natural and soil environment.

Abstract: In this study, with phenol as sole source of carbon, a phenol-degrading strain was isolated from rotting wood and polluted sludge. The strain was identified as Rhodococcus ruber SD3 according to their morphological features and 16S rDNA sequence. Rhodococcus ruber SD3 almost completely degraded 1.0g L-1 phenol in 72 hours. Rhodococcus ruber SD3 was also capable of growing in a medium containing isooctane, cyclohexane, benzene, n-heptane, toluene, acetonitrile, chlorobenzene, naphthalene, n-hexane, 1-naphthol and dimethylbenzene as sole carbon source, respectively. Rhodococcus ruber SD3 was mutated using LiCl as a chemical mutagen. The optimal concentration of LiCl for mutagenesis was 0.3 %. The mutant M1 could degrade 99.8 % of 1.5 g L-1 phenol within 72h. The optimum pH and temperature for the degradation of phenol with mutant M1 were 7.5 and 35°C.

Abstract: Harmful cyanobacterial blooms are a growing environmental problem worldwide in natural waters, and the biodegradation is found to be the most efficient method for removing microcystins (MCs) produced by harmful cyanobacteria. Based on the isolation of a promising bacterial strain of Sphingopyxis sp. USTB-05 for biodegrading MCs, a gene USTB-05-A (HM245411) that is responsible for the first step in the biodegradation of MCs was cloned and expressed for the first time. The cell-free extracts (CE) of recombinant E. coli DH5α containing USTB-05-A had high activity for biodegrading MCs. Based on an analysis of the liquid chromatogram-mass spectrum (LC-MS), the enzyme encoded by gene USTB-05-A was found to be active in cleaving the target peptide bond between Adda and arginine, and converting cyclic MC-RR and MC-YR) to linear MC-RR and MC-YR as their first degradation products, respectively, which offered direct evidence for the first step on the pathway of MCs biodegradation by Sphingopyxis sp. USTB-05.

Abstract: Wool, a natural keratin fiber, and polylactic acid (PLA), a so-called biodegradable man-made fiber, were assessed on their biodegradability under natural soil and aqueous medium conditions. Cotton, a natural cellulose fiber, was used as positive control. The biodegradation of the three samples were evaluated at 35°C for 42days by the time-dependent changes in weight loss, strength loss and morphology in both conditions. The experimental results indicate that biodegradation activities in natural soil was more efficient and faster than that in aqueous medium; The order of their degradation rates are: cotton>wool>PLA fiber, that implies the natural fibers are more easily degradable than man-made biodegradable PLA fiber; and the mechanical properties decreased faster than biodegradation rate.

Abstract: This paper mainly enumerated several kinds of base oil which all have a good biodegradation, such as vegetable oil, synthetic ester, poly-alpha-olefin, polyethylene glycol , introduced their performances, functions, the research status and the application prospect in the cutting fluid and brings forward the direction of the metal cutting fluid's development.

Abstract: polycaprolactone diols (MW=540, 1000, 2000) and citric acid were used as monomers, polycaprolactone-citric acid preformed polymer was preparated firstly by the heating polycondensation, then the preformed polymer was heated and cross-linked to obtain biodegradable elastomeric material. The molecular structure and Molecular weight was proved respectively by 1-HNMR and Gel Permeation Chromatography (GPC). The shape and glass transition temperature (Tg) of polycaprolactone-citric acid polymer was certified by differential scanning calorimetry(DSC). The hydrophilicity of the polymer was evaluated by its contact angle. The polymer’s mechanical property and degradation speed was also investigated.