Modification of Aliphatic Polyesters and Their Reactive Blends with Starch

Modified polycaprolactone was synthesized by melt reaction of PCL and reactive monomers such as glycidyl methacrylate (GMA) and maleic anhydride (MAH) in the presence of benzoyl peroxide in Brabender mixer. MAH showed a different grafting phenomenon compared to GMA. The reaction mechanism was discussed with different reactive monomers. Reactive blends of the PCL-g-GMA and the gelatinized starch with glycerin were prepared and their mechanical properties and biodegradabilities were investigated. Reactive blends of PCL-g-GMA and starch showed well-dispersed starch domain in the matrix and better mechanical strength than the unmodified PCL/starch blend. However, the reaction between PCL-g-GMA and starch induced a crosslinking during the reactive blending and this crosslinking in the blend lowered the biodegradation of the blend during the composting test. The biodegradability was investigated by the weight loss and surface morphology change of the blend in the composting medium.     

A review of the biodegradability and utility of poly(caprolactone)

Since the early 1970s, it has been known that exposure of poly(caprolactone) (PCL) to a variety of microorganisms results in biodegradation of this polymer. Besides the ability of PCL to be utilized as a carbon source for microorganisms, it has been demonstrated that, during degradation, carbon dioxide is generated. Soil burial and compost experiments have shown that chain scission of the PCL backbone occurs, mechanical properties of articles prepared from PCL are reduced rapidly, and significant weight loss occurs in a short time period. This inherent biodegradability of PCL, in combination with its ability to be converted by conventional extrusion equipment, allows for the preparation of biodegradable articles that have utility.Paper presented at the Bio/Environmentally Degradable Polymer Society—Third National Meeting, June 6–8, 1994, Boston, Massachusetts.     

城市废水有机物生物降解性评价及难降解有机物治理对策

采用ＧＣ－ＭＳ法对某城市废水中的有机物组分进行了分析,利用好氧生物降解一级动力学模型,计算了各单项有机物的一级反应速率常数Ｋｂ（２０℃）,在此基础上,讨论了各单项有机物的生物降解特性。结果表明,某城市废水处理厂曝气池进水中主要有机物有３８种,出水中主要有机物有１６种;废水中的主要难降解有机物为邻苯二甲酸二丁酯和邻苯二甲酸二异辛酯。应通过污染源控制或适当的预处理,加强其治理。     

氯苯驯化活性污泥对同类有机物的好氧降解性比较研究

利用测定微生物呼吸耗氧量的方法,对氯苯类中的５种优先污染物：氯苯,邻,间,对－二氯苯１,２,４－三氯苯,用接种活性污泥和经氯苯驯化的污泥地它们的生物降解性能进行了测试。实验结果表明,用未经驯化的污泥,５种氯苯皆存在的抑制作用,抑制作用的大小和抑制时间的长短氯代程度和浓度的影响,用氯苯将此污泥驯化后,该污染不仅表现出对苯具有降解能力,而且也表现出邻二氯苯,间二氯苯等同类有机物的共代谢降解能力,经分析     

石化污泥对苯系化合物好氧生物降解的研究

为了探讨苯系化合物的生物降解途径,选用从石油化工污水处理场曝气池活性污泥中富集的混合菌种,在好氧条件下,研究了苯,甲苯,乙基苯,邻－,间－和对二甲苯的可生物降解性,当化合物的浓度为５０－１４０ｍｇ／Ｌ时,６种被试验化合物均可被微生物降解,从该混合菌种中筛选出１７株可降解甲苯,乙基苯,三甲苯,障－和对二甲苯的单一菌种,其中     

模拟阳光下Ag/I-TiO_2光催化预处理山核桃加工废水

研究了在模拟太阳光下,采用银修饰的碘掺杂二氧化钛光催化剂(Ag/I-TiO2)对某食品厂山核桃加工废水进行光催化预处理的效果。结合X射线衍射(XRD)、比表面积分析(BET)、紫外-可见漫反射光谱(UV-Vis)的表征结果,来分析催化剂结构对于废水处理效果的影响。探讨了Ag含量、废水初始pH(pHi)和光照时间等因素对化学需氧量(COD)去除及水质可生化性(B/C)提高的影响。并得出适宜的反应参数为:3%Ag含量;pHi为6;光照时间为240 min。在最佳条件下,COD去除率45%,废水B/C比由0.17上升到0.31。光催化氧化法能够有效降低山核桃加工废水的COD含量,并达到显著提高废水可生化性的目的。     

电催化氧化处理除草剂异草酮废水的效能简

为有效处理含异草酮除草剂废水,以Sb掺杂Ti/SnO₂电极为阳极,不锈钢板为阴极,采用电催化氧化技术对异草酮废水进行降解,研究了不同影响因素对异草酮去除率的影响,并分析了异草酮的降解效果。结果表明,当异草酮初始浓度为100 mg/L、电流密度为20 mA/cm²、电解质投加量为0.10 mol/L,反应120 min后,异草酮去除率达到94%,此时TOC去除率为57.9%,能耗为25 kWh/m³,且废水的可生化性能显著提高。     

多元微电解技术对高浓度化学清洗废水预处理的影响

以高浓度化学清洗废水为研究对象,分别考察了常规混凝沉淀、多元微电解2种工艺对有机物污染物的去除效率和改善废水可生化性的效果。结果表明:多元微电解工艺的最佳pH 3.0,填充比1∶3,微电解1 h,气水比1∶1的条件下,其对COD平均去除率可达到60%,而直接混凝沉淀仅为10.5%,多元微电解工艺能使BOD5/COD值由原来的0.12升高到0.32,提高了废水的可生化性,减轻了后续生化处理负荷,是对高浓度化学清洗废水的有效预方法。     

Occurrence and ecological hazard assessment of selected veterinary medicines in livestock wastewater treatment plants

The occurrence of some veterinary medicines in the livestock wastewater plants (WWTPs) was investigated. This investigation represented the occurrence of veterinary medicines to treat in the livestock WWTPs or be discharged into the water system in Korea since the sampling sites were widely distributed across the nation and samples were collected from the 11 livestock WWTPs. Nine antibiotics, two analgesics, and two disinfectants occurred in the livestock wastewater plants (WWTPs). From 11 livestock WWTP influents, chlortetracycline, oxytetracycline, acetylsalicylic acid, and disinfectants frequently occurred with the high concentrations. Meanwhile, sulfamethoxazole, erythromycin-H₂O, and trimethoprim did not occur during sampling periods. The values for log Kow of each chemical showed a high correlation with the number of hydrogen bonding acceptors and were important parameters to estimate and understand the biodegradability and toxicity of a compound in the environment. The biodegradability of each compound was proportional to the hydrophilicity of each compound and the toxicity was proportional to the number of hydrogen bonding acceptors of each compound. The expected introductory concentration (EIC), predicted exposure concentration (PEC), and hazard quotient showed that the livestock WWTP effluents were hazardous to ecosystems.     

O3／UV预处理磺酰脲类除草剂生产废水的研究

采用O3／UV工艺预处理磺酰脲类除草剂生产废水,考察了初始pH值、臭氧投量、叔丁醇投加等因素对废水处理效果的影响,并初步探讨了该工艺处理废水的反应机理。实验结果表明,在废水初始pH为13．59和臭氧投量为65．08mg／min的条件下,预处理80min后废水COD去除率达63．47％,BOD5／COD由0．03提高至0．56,EC50从11％提高至55％。随着叔丁醇浓度的增加,废水COD去除率明显降低,证明该反应体系有·OH存在;体系中加入MnO2后废水COD去除率下降了16％,氧化效率明显下降,证明该反应体系内中间产物HO2O在O3／UV降解有机废水过程中起到了重要的作用。