Integrated assessment for aerobic biodegradability of organic substances

In this paper, the amount of oxygen consumption, end products and activities of microorganisms are considered as the three factors which affect the biodegradability of organic substances in water. Two integrated assessment methods for biodegradability of organic substances, fuzzy clustering integrated assessment and weighted integrated assessment, have been developed. Simultaneously, the detail steps for assessing a new organic substance biodegradability with these two integrated assessment methods are proposed.     

Influence of microbial biomass on the biodegradability of organic compounds

The influence of different types of inocula as well as the amount of inoculum (microbial biomass) on the biodegradation pattern of acetate, 4-nitrophenol, and the three methoxyaniline isomers was investigated in the Modified OECD test and a NPR guidline. Using sediment of the river Rhine as inoculum 4-nitrophenol could not be degraded, while an inoculum from garden soil gave only 60% degradation in the OECD test. Effluent of an activated sludge plant however was able to degrade 4-nitrophenol at a concentration of 19 mg/1 in the OECD test completely. At a concentration of 94 mg/1 no degradation was observed. Testing the methoxyanilines for biodegradability it was found that at a low inoculum level (OECD protocol) no degradation of the three compounds occurred. Using activated sludge (1.5 ml/1) as inoculum 3- and 4-methoxy aniline could be degraded for 60% respectively completely while 2-methoxyaniline was still refactory to degradation. Measuring the microbial biomass by means of ATP during biodegradation strongly suggested that the microbial flora which rapidly metabolize acetate is quite another microflora than the microflora responsible for the degradation of 4-nitrophenol.     

Dissipation pathways of organic pollutants during the composting of organic wastes

The organic pollutants (OPs) present in compostable organic residues can be recovered in the final composts leading to environmental impacts related to their use in agriculture. However, the composting process may contribute to their partial dissipation that is classically evaluated through the concentration decrease in extractable OPs, without identification of the responsible mechanisms as mineralization or stabilization of OP as non-extractable residues (NER) or bound residues. The dissipation of four (14)C-labeled OPs (fluoranthene; 4-n-nonylphenol, NP; sodium linear dodecylbenzene sulfonate, LAS; glyphosate) was assessed during composting of sewage sludge and green waste. The dissipation of LAS largely resulted from its mineralization (51% of initial LAS), whereas mineralization was intermediate for NP (29%) and glyphosate (24%), and negligible for fluoranthene. The NER pathway mostly concerned NP and glyphosate, with 45% and 37% of the recovered (14)C being found as NER at the end of composting, respectively. In the final composts, the proportions of water soluble residues of OPs considered as readily available were <11% of recovered (14)C-OPs. However, most fluoranthene remained solvent extractable (72%) and potentially available, whereas only 18% of glyphosate and less than 7% of both NP and LAS remained solvent extractable in the final compost.     

城市有机垃圾热解过程中NH3、H2S和HCl的析出特性

为了对城市有机垃圾热解过程中NH3、H2S和HCl的析出特性进行研究,采用箱式气氛炉在500~800℃热解终温下进行热解实验。热解过程中产生的NH3、H2S和HCl分别用硼酸溶液、乙酸锌-乙酸钠溶液以及NaOH溶液吸收,并分别采用分光光度法和滴定法进行量化。实验结果表明：NH3-N、H2S-S和HCl-Cl的析出率随着温度的升高而增加,热解终温为500、600、700和800℃时,NH3-N的析出率分别为39%、40%、30%和44%,H2S-S的析出率分别为18%、22%、25%和26%,HCl-Cl的析出率分别为68%、71%、76%和85%;热解终温控制在700℃有利于减少NH3-N的析出,低温热解（500℃）有利于减少H2S和HCl的析出;热解炭中S和Cl的残留率随着热解终温的升高而降低,终温800℃时的残留率分别为41%和5%。     

有机固体废物堆肥化处理的微生物学机理研究

由于符合持续发展的理念 ,利用微生物技术处理有机固体废物越来越受到人们的重视 ,其核心问题则是木质纤维素的生物降解。随着园林废物等高木质纤维素含量的城市生活垃圾的不断增加 ,以及对农业固体废物和食品工业废物再利用的需要 ,这一领域的研究取得了很大的进展。在研究中 ,针对好氧堆肥和厌氧发酵 2项主要的微生物处理技术 ,对其优势微生物菌群、不同降解底物和微生物降解动力学方面的最新研究进展进行了回顾和总结 ,并对环境微生物制剂的应用以及有机固体废物的微生物处理技术的发展做了合理的展望。     

有机固体废弃物的热解处理研究

通过对锯末、稻壳、纸屑、橱芥、塑料和橡胶6种具有代表性的有机固体废弃物原料的热解实验,测量了它们三相产物收率,并分析了它们固体、液体和气体三相产物的组成.特别对液体产物,针对它们的特殊性分别采用了层析、模拟蒸馏和全烃气相色谱分析,详细探讨了热解焦油的具体组分,得到了热解法处理有机固体废弃物的一些有意义的数据.     

添加乙醇碳源对驯化菌种降解油制气废水的影响

进行了添加乙醇作为碳源强化油制气废水生物降解的研究,并利用GC／MS分析对油制气废水中芳烃类化合物的降解进行了初步研究。研究表明,共代谢基质乙醇的加入,可使菌种S-2、Y-3、XH-3、M-3对COD、氨氮、可萃取有机物等指标的去除率分别提高17．6％～25．6％、34．9％～42．8％、10．4％～14．2％;但在所采用的时间范围内,酚类化合物的去除率降低;芳烃类化合物的去除率提高15．4％～21．2％。除了维持无共代谢条件下对芳环数≤3的芳烃类化合物的良好降解能力外,对芳环数为4～6的化合物降解能力也有所提高。     

超临界水氧化法改善有机污染物可生化性的研究

难生化有机污染物二甲基甲酰胺、乙睛、氨基萘磺酸或羟基萘磺酸的高浓度水溶液 (4777— 2 82 4 4mg/L) ,经超临界水氧化处理后 ,其可生化性都有了大幅度的提高。二甲基甲酰胺、乙睛、氨基萘磺酸和羟基萘磺酸处理前的BOD5/CODCr,分别为 8.4 %、1.5 6 %、1.5 6 %和 2 .73%。经过超临界水氧化处理 ,它们的BOD5/CODCr可分别达到 2 3.2 %、5 5 .1%、5 0 .2 %和 38.8%。且随着处理温度的升高和COD去除率的上升 ,可生化性越来越好。这表明 ,超临界水氧化法不仅可以用来彻底降解有机污染物 ,也可以用于难生化有机污染物的预处理 ,为难生化有机污染物的生物处理创造条件     

危险废物中有机物热降解动力学模型

为研究有机危险废物在高温工业窑炉中的协同处置效果,对典型有机物苯和氯乙烯进行热降解实验。将定量的气态苯、氯乙烯和空气的混合物分别通入高温管式炉中煅烧,用气相色谱质谱仪检测尾气中有机物浓度,确定其热降解动力学特性。结果表明：低温阶段苯和、氯乙烯的热降解率随温度较快速增加,高温阶段缓慢增加,1 000℃以上可完全热降解;延长煅烧时间促进苯和氯乙烯的热降解。最终得到苯和氯乙烯的热降解动力学模型,模型可以用于预测危险废物中有机物高温热降解率。     

Determination of the aerobic biodegradability of polymeric material in aquatic batch tests

Results of an international ring-test of two laboratory methods are presented for investigating the biodegradability of organic polymeric test materials in aquatic test systems based on respirometry and the evolution of carbon dioxide. These methods are developed further from the well-known standardized biodegradation tests ISO 9408 (1999) and ISO 9439 (1999), which have been successfully used for many years. The most important improvements are the extension of the test period up to six months, the increase of the buffer capacity and nutrient supply of the inorganic medium, an optimization of the inoculation, and optionally, the possibility of a carbon balance. A ring test, organized by the International Biodeterioration Research Group (IBRG), was run using a poly(,-caprolactone)-starch blend and an aliphatic-aromatic co-polyester as test materials and a microcrystalline cellulose powder as a reference material. The test results and the experience gained by the participants showed that the methods are suitable and practicable. The test methods have been meanwhile established as standards ISO 14851 (1999) and ISO 14852 (1999).     

Influence of plants on the chemical extractability and biodegradability of 2,4-dichlorophenol in soil

This study investigated the fate and behaviour of [UL-(14)C] 2,4-dichlorophenol (DCP) in planted (Lolium perenne L.) and unplanted soils over 57 days. Extractability of [UL-(14)C] 2,4-DCP associated activity was measured using calcium chloride (CaCl(2)), acetonitrile-water and dichloromethane (DCM) extractions. Biodegradability of [UL-(14)C] 2,4-DCP associated activity was assessed through measurement of (14)CO(2) production by a degrader inoculum (Burkholderia sp.). Although extractability and mineralisation of [UL-(14)C] 2,4-DCP associated activity decreased significantly in both planted and unplanted soils, plants appeared to enhance the sequestration process. After 57 days, in unplanted soil, 27% of the remaining [UL-(14)C] 2,4-DCP associated activity was mineralised by Burkholderia sp., and 13%, 48%, and 38% of (14)C-activity were extracted by CaCl(2), acetonitrile-water and DCM, respectively. However, after 57 days, in planted soils, only 10% of the [UL-(14)C] 2,4-DCP associated activity was available for mineralisation, whilst extractability was reduced to 2% by CaCl(2), 17% by acetonitrile-water and 11% by DCM. This may be due to the effect of plants on soil moisture conditions, which leads to modification of the soil structure and trapping of the compound. However, the influence of plants on soil biological and chemical properties may also play a role in the ageing process.     

Determination of volatile organic profiles and photochemical potentials from chemical manufacture process vents

The main objective of this study was to monitor the volatile organic compounds (VOCs) in the stack gas released from organic chemical industrial plants to determine emission factors. Samples from 52 stacks, with or without air pollution control devices (APCDs), from seven industrial processes were taken and VOCs measured using U.S. Environmental Protection Agency (EPA) Method 18. These 7 processes, including 26 plants, were the manufacturers of acrylonitrile-butadiene-styrene (ABS), polyvinyl chloride (PVC), polystyrene (PS), acrylic resin (ACR), vinyl chloride (VC), para-terephthalic acid (PTA), and synthetic fiber (SYF). The results clearly indicate significant variations of emission factors among the various industrial processes, particularly emission factors for those without APCDs. As expected, those with APCDs yield much less emission factors. Regardless of those with or without APCDs, the order of manufacturing processes with regard to VOC emission factors is SYF > ABS > PS >ACR > PTA > PVC > VC. The emission factors for some processes also differ from those in EPA-42 data file. The VOC profiles further indicate that some VOCs are not listed in the U.S. VOC/Particulate Matter Speciation Data System (SPECIATE). The potential O3 formation is determined from the total amount of VOC emitted for each of seven processes. The resultant O3 yield varied from 0.22 (ACR) to 2.33 g O3 g(-1) VOC (PTA). The significance of this O3 yield is discussed.     

The fate of recombinant plasmids during composting of organic wastes

Composting was investigated as a means for safe disposal of organic waste containing bacteria that carry transgenes in recombinant plasmids. To generate model recombinant plasmids, a mobile IncQ plasmid, RSF1010, and a non-mobile plasmid, pGFP, were genetically modified to carry a DNA segment encoding both green fluorescent protein and kanamycin resistance and were designated as RSF1010-GFPK and pGFPK. Escherichia coli (E. coli) C600 harboring these plasmids were inoculated into chicken manure specimens that were placed in compost at 20 and 60 cm from the bottom of a 1.0-m high compost bin. Control specimens were held at ambient temperature. By day 10, compost temperatures at the lower and upper levels of the bin had reached 45.3 and 61.5°C, respectively, and at both levels the target E. coli had been inactivated and the plasmids had lost their capacity to be transformed or mobilized. Furthermore, based on real time Polymerase chain reaction (PCR), the transgene fragments along with the host chromosomal DNA fragment from specimens at the upper level had been degraded beyond the detection limit. However, at the lower level where temperatures remained below 48°C these fragment persisted to day 21. At ambient temperatures (0–8°C), the E. coli, plasmids and the transgene fragments persisted in manure specimens throughout the 21 day test period. The study showed the potential for composting as a safe procedure for disposal of bacteria carrying transgenes in recombinant plasmids.     

Biohythane production from organic wastes: present state of art

The economy of an industrialized country is greatly dependent on fossil fuels. However, these nonrenewable sources of energy are nearing the brink of extinction. Moreover, the reliance on these fuels has led to increased levels of pollution which have caused serious adverse impacts on the environment. Hydrogen has emerged as a promising alternative since it does not produce CO₂ during combustion and also has the highest calorific value. The biohythane process comprises of biohydrogen production followed by biomethanation. Biological H₂ production has an edge over its chemical counterpart mainly because it is environmentally benign. Maximization of gaseous energy recovery could be achieved by integrating dark fermentative hydrogen production followed by biomethanation. Intensive research work has already been carried out on the advancement of biohydrogen production processes, such as the development of suitable microbial consortium (mesophiles or thermophiles), genetically modified microorganism, improvement of the reactor designs, use of different solid matrices for the immobilization of whole cells, and development of two-stage process for higher rate of H₂ production. Scale-up studies of the dark fermentation process was successfully carried out in 20- and 800-L reactors. However, the total gaseous energy recovery for two stage process was found to be 53.6 %. From single-stage H₂ production, gaseous energy recovery was only 28 %. Thus, two-stage systems not only help in improving gaseous energy recovery but also can make biohythane (mixture of H₂ and CH₄) concept commercially feasible.     

Determination of the aerobic biodegradability of polymeric material in a laboratory controlled composting test

A laboratory method is presented for investigating the biodegradation of an organic test material in an aerobic composting system based on the evolution of carbon dioxide. In addition to carbon conversion, biodegradation can also be monitored through weight loss and physical disintegration. The test method is different from other biodegradation tests, especially aquatic tests, because of the elevated temperature representative for real composting conditions and also because of enhanced fungal degradation activities. A ring test was run using paper and poly-β-hydroxybutyrate/valerate as test materials and cellulose powder as a reference material. The test results and the experience gained by the participants showed that the method is suitable and practicable. Experience with real technical-scale composting facilities confirms that the method provides test results of high predictive value. The test is designed to become a European Standard in connection with determining the compostability of packagings and packaging materials.     

Observations and assessment relating to incineration of chlorinated chemical wastes

Tests have been carried out on the chemical waste incinerator operated by Re-Chem International at Bonnybridge, Scotland, to determine whether any emissions of polychlorodibenzo-p-dioxins (PCDD) or polychlorodibenzofurans (PODF) occurred during incineration under typical conditions of certain organo-chlorine feedstocks. No detectable emissions of PCDDs or PCDFs were found during the incineration of 2,4,5-I esters, pentachlorophenol residues or PCB in liquid form. A just measurable amount of 2,3,7,8 TCDF was detected during the incineration of large intact capacitors and prior shredding, or puncturing, is preferred. The measured levels of PCDDs and PCDFs in soils collected in the vicinity of the Bonnybridge plant were found to be comparable to or less than those reported in urban or rural environments elsewhere. The reported detection of these compounds in a soil sample collected in 1877 suggests that they may be ubiquitous. It is demonstrated that cows grazing close to the Bonnybridge incinerator are unlikely to have suffered ill-effects from these emissions.     

利用不同有机和无机固体废物配制人工土壤的研究

以生活污泥、牛粪、蚓粪、菌菇渣、粉煤灰、脱硫石膏、钢渣和煤矸石8种固体废物为原料配置人工土壤,探讨不同有机和无机固体废物配比对人工土壤性质的影响。结果表明,获得的人工土壤中,粒级0.250 mm的水稳性团聚体质量分数总体在20%~50%,接近或达到正常的自然土壤标准,制得的人工土壤为弱碱性,pH实测值在7.12~8.14。培养过程中,人工土壤中有机碳含量大大降低。生活污泥组、蚓粪组人工土壤在培养过程中呈现铵态氮向硝态氮的转化,而牛粪组人工土壤在培养过程中虽然有较多的有机氮被矿化,但同时也有较多的硝态氮被重新同化成有机氮。合成的人工土壤在物理、化学、养分和生物毒理学性质方面均已达到自然土壤相关参数的正常范围值,可以满足植物生长的要求。但由于部分固体废物原料重金属超标,则应尽量避免用于种植可食用类植物。