UASB反应器反硝化处理工业废水

采用絮状污泥成功启动升流式厌氧污泥床(UASB)反应器处理含甲酸、苯胺、环已酮、NO3-等的工业废水。UASB反应器以低负荷启动,10天后逐渐提高进水COD,出水COD保持在710~770 mg/L,COD去除率为40%~60%;出水TOC保持在115~314 mg/L,TOC去除率由60.3%逐渐升高至87.2%,最终维持在81%左右;出水中ρ(NO3-)维持在134~176 mg/L,NO3-去除率为90%左右,系统稳定后NO3-去除率几乎为100%。在进水COD容积负荷不超过5.00 kg/(m3·d)的条件下,实际COD容积负荷稳定在2.00 kg/(m3·d)左右,实际TOC容积负荷稳定在1.00 kg/(m3·d)以上。当进水COD容积负荷不大于4.48 kg/(m3·d)时,COD去除率为55%~74%,TOC去除率为63%~87%,NO3-去除率大于95%。     

升流式厌氧污泥床处理抗生素制药废水

采用升流式厌氧污泥床(UASB)反应器处理抗生素制药废水。实验结果表明:进水COD为9 300mg/L、容积负荷为9.3kg/(m3.d)时,COD去除率仍在80%以上;在COD∶ρ(SO42-)=6、进水ρ(SO42-)为1 500mg/L以下时,COD去除率一直保持在80%以上,SO42-去除率始终在23%以下。SO24-的存在对产甲烷菌影响不大,UASB反应器运行稳定。UASB反应器产沼气的产气率达0.48m3/kg,沼气中甲烷体积分数为68%,二氧化碳体积分数为27%,产甲烷菌具有较高的活性。     

干法腈纶生产废水脱氨氮研究

采用本实验室富集驯化的高效硝化细菌对生化处理后的干法腈纶生产废水进行了脱NH3-N研究,在连续运行装置中考察了DO和MLSS的变化特征,并研究了废水NH3-N负荷和COD负荷对脱NH3-N效果的影响.实验结果表明:该菌能适应干法腈纶生产废水中的难生物降解物质并有效去除废水中的NH3-N,启动期DO呈现"高-低-高"的变化,运行期污泥增长速率呈现"S"型变化;进水NH3-N负荷达到0.405 kg/(m3·d)时仍能维持出水P(NH3-N)在5 mg/L以下,进水COD负荷由0.126 kg/(m3·d)提高到0.975 kg/(m3·d)的过程中,NH3-N去除率始终高于96%.     

IC反应器厌氧处理MTO废水

以初步驯化后的絮状污泥作为内循环(IC)反应器的接种污泥,厌氧处理甲醇制烯烃(MTO)废水(COD大于50 000 mg/L、TOC大于10 000 mg/L),以高负荷、高进水浓度方式培养颗粒污泥,考察了反应器运行过程中废水处理效果及污泥性状的变化情况。实验结果表明:IC反应器的进水COD容积负荷可达29.0 kg/(m~3·d),COD和TOC去除率可稳定在96%以上;在污泥培养阶段,废水升流速率宜采用0.4~0.6 m/h;在颗粒污泥未成熟时废水升流速率不宜提高过快,而在颗粒污泥成熟后,废水升流速率可在一定范围内快速提高。     

IC反应器处理MTO废水的中试研究

中试研究了内循环(IC)反应器处理甲醇制烯烃(MTO)废水的启动和运行过程,同时考察了颗粒污泥的性状及沼气产量的变化情况。试验过程运行稳定,系统抗冲击性强。以絮状污泥为接种污泥,经过131 d的启动和运行,IC反应器的COD去除负荷可达10 kg/(m~3·d)以上,COD去除率可达90%以上。IC反应器中的成熟颗粒污泥形状规则、密实、粒径大、沉降速率快。IC反应器的沼气产量符合理论预期。     

EGSB—MBBR处理高浓度聚酯废水

采用膨胀床颗粒污泥反应器(EGSB)—移动床生物膜反应器(MBBR)处理高浓度、难降解(COD≥10000mg/L,BOD5/COD0.3)聚酯废水。实验结果表明:在(37±1)℃、停留时间(HRT)为15.4h、进水COD为10000mg/L的条件下,EGSB反应器容积负荷达5.31kg/(m3.d),COD去除率达95%以上;在室温、HRT为48.0h的条件下,MBBR反应器出水COD100mg/L,BOD530mg/L,出水水质达到GB8978—1996《污水综合排放标准》中的一级排放标准。     

厌氧折流板反应器处理石化剩余污泥

研究了厌氧折流板反应器(ABR)在厌氧消化处理石化剩余污泥启动过程中的性能及相关参数。实验结果表明:污泥挥发性固体含量的去除率达43.7%;反应器内pH维持在6.4~7.4;从启动到稳定运行,第一隔室最大比产甲烷活性变化不大,在0.14 L/(g·d)以下,第二、第三、第四隔室的最大比产甲烷活性在0.29 L/(g·d)以上,污泥在反应器内部实现了分级分相处理。     

pH对厌氧氨氧化反应脱氮效能的影响

采用具有恒定pH功能的SBR接种厌氧氨氧化颗粒污泥,研究了pH对厌氧氨氧化菌脱氮效能的影响。实验结果表明:在进水ρ(氨氮)和ρ(亚硝酸盐氮)分别为58.00 mg/L和79.28 mg/L、TN容积负荷为0.82 kg/(m3·d)、不控制反应pH的条件下,随着反应的进行,pH不断升高,当pH=8.02时,菌种的去除效能最高;在进水ρ(氨氮)和ρ(亚硝酸盐氮)分别为120.00 mg/L和159.33 mg/L、TN容积负荷为1.62 kg/(m3·d)、恒定反应pH为8.00的条件下,反应4.0 h时的容积基质氮去除速率(NRR)达到1.42 kg/(m3·d),氨氮去除率达98.39%,亚硝酸盐氮去除率达99.48%;拟合曲线推导的最适pH的理论值为7.85,反应4.0 h时的NRR理论最大值达1.52 kg/(m3·d)。     

AEB反应器反硝化处理高浓度硝酸盐废水

采用缺氧膨胀床(AEB)反应器处理高浓度硝酸盐废水,研究了反应器的快速启动和挂膜特性,以及在反硝化连续流运行条件下对废水的处理效果。实验结果表明:采用自然挂膜方式,填料层从下至上生物膜厚度逐渐增加;AEB的快速启动8 d可完成,COD去除率由44.9%升至92.3%,NO_3~--N去除率由39.8%升至98.4%;稳定运行阶段(进水COD 4 628～5 548 mg/L、ρ(NO_3~--N) 1 339～1 505 mg/L),COD去除率稳定在95%左右,NO_3~--N去除率稳定在98%～99%,COD和NO_3~--N的容积负荷去除量最高可达27.8 kg/(m~3·d)和7.3 kg/(m~3·d)。     

膜生物反应器处理抗生素废水

采用一体式膜生物反应器处理抗生素废水.在原水试验中,在废水pH 8.0左右、DO 2.5 mg/L、温度30℃、COD体积负荷0.957 kg/(m3·d)条件下,出水COD、NH3-N质量浓度平均值分别达到26.53 mg/L和2.84 mg/L.     

Review of the kinetics of alkaline degradation of cellulose in view of its relevance for safety assessment of radioactive waste repositories

The degradation of cellulose (a substantial component of low- and intermediate-level radioactive waste) under alkaline conditions occurs via two main processes: a peeling-off reaction and a basecatalyzed cleavage of glycosidic bonds (hydrolysis). Both processes show pseudo-first-order kinetics. At ambient temperature, the peeling-off process is the dominant degradation mechanism, resulting in the formation of mainly isosaccharinic acid. The degradation depends strongly on the degree of polymerization (DP) and on the number of reducing end groups present in cellulose. Beyond pH 12.5, the OH^- concentration has only a minor effect on the degradation rate. It was estimated that under repository conditions (alkaline environment, pH 13.3-12.5) about 10% of the cellulosic materials (average DP = 1000-2000) will degrade in the first stage (up to 10⁵ years) by the peeling-off reaction and will cause an ingrowth of isosaccharinic acid in the interstitial cement pore water. In the second stage (10⁵-10⁶ years), alkaline hydrolysis will control the further degradation of the cellulose. The potential role of microorganisms in the degradation of cellulose under alkaline conditions could not be evaluated. Proper assessment of the effect of cellulose degradation on the mobilization of radionuclides basically requires knowing the concentration of isosaccharinic acid in the pore water. This concentration, however, depends on several factors such as the stability of ISA under alkaline conditions, sorption of ISA on cement, formation of sparingly soluble ISA-salts, etc. A discussion of all the relevant processes involved, however, is far beyond the scope of the presented overview.     

Study of Aging Characteristics of Ternary Blends of Polyethylenes—II

Six film samples of low-density polypropylene (LDPE)/linear LDPE (LLDPE)/high-density polypropylene (HDPE) with varying ratios of LDPE (20–45 ... wt%) and LLDPE (25–50 wt%) having a fixed amount of HDPE at 30 wt% were prepared by blown film extrusion technique. The samples were aged at four different temperatures, 55°, 70°, 85°, and 100°C, for four different time periods in the interval of between 150 hours and up to 600 hours. The change in the structure of various constituents and the formation of various oxygenated (peroxy and hydroperoxy) and unsaturated groups during thermo-oxidative degradation was discussed by infrared spectroscopy. The visiosity-average molecular weight was found to have decreased slowly in the initial aging hours and temperatures, whereas it decreased by 10% with its previous value tensile strength that is, 100°C when aged for 600 hours. The tensile strength of the sample first increased by 67% at 55°C and 89% at 70°C up to 450 hours, whereas the values increased by 52.5% at 85°C and 33.9% at 100°C when aged for 150 hours and then decreased. The percentage elongation at break increased by 2.7% at 55°C and 10.7% at 70°C for 150 and 300 hours of aging, respectively, whereas the percentage decreased when aged at 85°C and 100°C for up to 600 hours of aging. The values of gel content (percent) increased and initial degradation temperature decreased with aging time and temperature.     

Calculation of carbon balances for evaluation of the biodegradability of polymers

Establishing carbon balances has been proven to be an applicable and powerful tool in testing biodegradability of polymers. In controlled degradation tests at a 4-L scale with the model polymer poly(-hydroxybutyrate) (PHB), it was shown that the degree of degradation could not be determined with satisfactory accuracy from CO₂ release alone. Instead, the course of degradation was characterized by means of establishing carbon balances for the degradation of PHB withAcidovorax facilis and a mixed culture derived from compost. Different analytical methods for determining the different carbon fractions were adapted to the particular test conditions and compared. Quantitative determination of biomass and residual polymer were the main problems in establishing carbon balances. Amounts of biomass derived from protein measurements depend strongly on assumptions of the protein content of the biomass. Selective oxidation of biomass with hypochlorite was used as alternative, but here problems arose from insoluble metabolic products. Determination of soluble components with the method of chemical oxygen demand (COD) also includes empirical assumptions but seems acceptable if the dissolved carbon fraction is in the range of some 10% total carbon. Results confirm both analytical assays and theoretical approaches, in ending up at values very close to 100%, within an acceptable standard deviation range under test conditions comparable to standard test practice.Paper presented at the Bio/Environmentally Degradable Polymer Society—Third National Meeting, June 6–8, 1994, Boston, Massachusetts.     

Model of technological alternatives of production of sodium chromate (VI) with the use of chromic wastes

This article presents a mathematical model which describes the sodium chromate (VI) production process with the use of chromic waste as a substitution of natural raw materials. This model is a function of selected process parameters common for all of the examined alternatives and based on equations of material balance. Optimization of the elaborated technological alternatives of the production process with use of recycling of chromic waste has been evaluated by determining the extreme value of the quality indicator WJ. This indicator defines the quantity of waste created in the process. Optimization results enabled the selection of the optimal technological solution from all of the alternatives possible for use in industrial practice. Negative values of the indicator prove that there is the possibility of introducing to the process a larger quantity of waste than the one obtained in the process and transported to the storage heaps.     

化学品生物降解性的评价与预测

介绍了有机化学物质生物降解性的测定方法及其预测方法研究概况，并讨论了生物降解性评价的发展前景。     

Determination of the Burning Characteristics of a Slick of Oil on Water

The burning rate of a slick of oil on a water bed is characterized by three distinct processes, ignition, flame spread and burning rate. Although all three processes are important, ignition and burning rate are critical. The former, because it defines the potential to burn and the latter because of the inherent possibility of boilover. Burning rate is calculated by a simple expression derived from a one-dimensional heat conduction equation. Heat feedback from the flame to the surface is assumed to be a constant fraction of the total energy released by the combustion reaction. The constant fraction (χ) is named the burning efficiency and represents an important tool in assessing the potential of in situ burning as a counter-measure to an oil spill. By matching the characteristic thermal penetration length scale for the fuel/water system and an equivalent single layer system, a combined thermal diffusivity can be calculated and used to obtain an analytical solution for the burning rate. Theoretical expressions were correlated with crude oil and heating oil, for a number of pool diameters and initial fuel layer thickness. Experiments were also conducted with emulsified and weathered crude oil. The simple analytical expression describes well the effects of pool diameter and initial fuel layer thickness permitting a better observation of the effects of weathering, emulsification and net heat feedback to the fuel surface. Experiments showed that only a small fraction of the heat released by the flame is retained by the fuel layer and water bed (of the order of 1%). Ignition has been studied to provide a tool that will serve to assess a fuels ease to ignite under conditions that are representative of oil spills. Two different techniques are used, piloted ignition when the fuel is exposed to a radiant heat flux and flash point as measured by the ASTM D56 Tag Closed Cup Test. Two different crude oils were used for these experiments, ANS and Cook Inlet. Crude oils were tested in their natural state and at different levels of weathering, showing that piloted ignition and flash point are strong functions of weathering level.     

Mechanism of Microbial Degradation of Slow-Release Fertilizers

Methyleneureas are condensation products of urea and formaldehyde of different molecular mass and solubility; they are used in large amounts both as resins, binders, and insulating materials for industrial applications, as well as a slow-release nitrogen fertilizer for greens, lawns, or in bioremediation processes. In the present study, the microbial breakdown of these products was investigated. The nitrogen was released as ammonia and urea, and the formaldehyde released immediately oxidized via formiate to carbon dioxide. The enzymatic mechanism of metabolization of methyleneureas was studied in microorganisms isolated from soil, which were able to use these compounds as the sole source of nitrogen for growth. A strain of the Gram-negative bacterium Ralstonia paucula (formerly Alcaligenes sp. CDC group IVc-2) completely degraded methylenediurea and dimethylenetriurea to urea, ammonia, formaldehyde, and carbon dioxide. The enzyme initiating this degradation (methylenediurease) was purified and turned out to be different from the previously described enzyme from Ochrobactrum anthropi with regard to its regulation of expression and physicobiochemical properties. Fungal degradation of methyleneureas may occur via the formation of organic acids, thus leading to a nonenzymatic degradation of methyleneureas, which are unstable under acidic conditions.     

Effect of Degree of Substitution of Octenyl Succinate Starch on Enzymatic Degradation

Octenyl succinate starch of degree of substitution (ds) 0.03, 0.07, and 0.11 was synthesized in an aqueous medium. These compounds were then tested for the susceptibility to enzymatic degradation. The multiple-enzyme regime of -amylase, amyloglucosidase, and pullulanase was chosen for the evaluation. This combination of enzymes had been proven to degrade 99.5% of unmodified starch to glucose and hence was chosen for this study. It was found that even small amounts of subsituent caused a considerable decrease in the extent of degradation. The net extent of degradation decreased with increasing ds. Surprisingly, the amount of glucose from all three substituted substrates was quite similar, suggesting the effect small amounts of subtituent had on the enzymatic activity.     

Electron Microscope Observation of Biodegradation of Polymers

Biodegradable polymers generally decompose in the various media in our environments. These environments contain soils, seawater, and activated sludge. If biodegradable materials waste is discarded, they decompose in these media. The biodegradation process of biodegradable polymers was investigated by scanning electron microscopy. Polycaprolactone, polybutylene succinate, and P(3HB-co-3HV) were tested. The shapes of holes on the decomposing surfaces are different according to the biodegradation media. Semispherical holes are observed on the surfaces of polybutylene succinate films degraded in activated sludge and cracks are observed on the surfaces of polycaprolactone films degraded in soil.     

Structure-biodegradation relationships of polymeric materials. 1. Effect of degree of oxidation on biodegradability of carbohydrate polymers

The biodegradability of oxidized starch and inulin has been studied in relation to the degree of periodate oxidation to dialdehyde derivatives, by measuring oxygen consumption and mineralization to carbon dioxide. A higher degree of oxidation of dialdehyde starch and dialdchyde inulin results in a lower rate at which the polymers are biodegraded. It is demonstrated that the biodegradation rate of dialdehyde inulin derivatives decreases more than that of equivalent starch derivatives. The differences in biodegradation behavior between dialdehyde starch and dialdehyde inulin, resulting from comparable modifications, are discussed in terms of conformational structure.