一株氨化菌的分离鉴定及其氨化特性研究

从升流式厌氧污泥床(UASB)中分离到一株高效氨化菌AHJ1,通过形态观察、生理生化试验、16S rRNA基因序列分析,初步鉴定为球形芽孢杆菌;进一步探讨了UASB处理工艺各因素对AHJ1氨化特性的影响,结果表明在温度37℃,pH 6.0、装液量30%,氨化率可达58.62%,且在一定程度上抑制了厌氧处理中鸟粪石的生成.

ABR预处理畜禽养殖废水及其氨化研究

利用厌氧折流板反应器(ABR)与改良SBR联用工艺处理模拟畜禽养殖废水,旨在揭示厌氧过程中氨化现象的影响因素及其规律。试验中所处理的废水是人工模拟畜禽养殖废水,该类废水含有大量的有机物,特别是蛋白质等含氮化合物,COD从1 000～10 000 mg/L逐渐增大,相应地氨氮质量浓度范围为78.6～773.2 mg/L。研究了ABR的启动过程中水力停留时间(HRT)、pH值、温度以及进水氨氮浓度等因素对氨化的影响。结果表明,HRT是一个重要的因素,很大程度地影响其他因素的研究,16 h为峰值点;氨化菌在pH值为6.5～8.0的范围可以保持一定活性,其中以pH=7.0为最佳点;随着温度升高,氨化菌活性提高,氨化率也随之提高,33℃为最佳温度,但ABR对温度的敏感性不是很高,考虑经济原因,可以在25℃运行;氨化率随进水氨氮浓度的增加而减小。最佳氨化率条件是HRT=16 h,pH=7.0,T=25℃,此时进水COD为10 000 mg/L。

镁碱化对土壤微生物活性和水解酶的影响

研究了镁碱度对土壤微生物生物量及其活性的影响,研究地点位于甘肃河西走廊疏勒河中游昌马洪积冲积扇缘。从10个具有不同镁碱化程度的采样点,采集土壤样品30个,测定了土样的pH、镁碱度、Mg2+/Ca2+、HCO3-+CO32-、钠碱度、有机碳、全氮、微生物生物量碳、微生物熵、精氨酸氨化率、β-葡萄糖苷酶、磷酸酶、蛋白酶-casein、蛋白酶-BAA、脲酶等指标。结果表明:土壤pH和钠碱度没有明显的相关性,而和镁碱度、Mg2+/Ca2+、HCO3-+CO32-显著正相关,相关系数分别为0.70、0.69和0.72。镁碱度和Mg2+/Ca2+显著正相关,相关系数为0.84。有机碳、全氮、微生物生物量碳、微生物熵、精氨酸氨化率的变化范围分别是6.4~18.5 g·kg-1、0.28~1.20 g·kg-1、23.1~351.9 mg·kg-1、0.37~2.52%、0.77~1.83μmol.g-1.d-1,和Mg2+/Ca2+之间显著负相关,相关系数分别是-0.52、-0.50、-0.59、-0.62、-0.65。β-葡萄糖苷酶、磷酸酶、蛋白酶-casein、蛋白酶-BAA、脲酶的变化范围分别是6.68~27.79μmol.g-1.h-1、7.03~25.99μmol.g-1.h-1、0.11~0.76μg.g-1.h-1、0.05~0.48μmol.g-1.h-1、0.07~0.61μmol.g-1.h-1吗,和微生物生物量碳之间显著正相关,相关系数分别是0.73、0.71、0.78、0.87、0.81,和Mg2+/Ca2+之间显著负相关,相关系数分别是-0.59、-0.58、-0.60、-0.56、-0.54。可见,镁碱化会造成土壤有机质含量下降、微生物生物量变小、微生物活性降低、水解酶活性低下,镁碱化是导致土地生产力低下的原因之一。

N Mineralization and Nitrification in a Primary Lithocarpus xylocarpus Forest and Degraded Vegetation in the Ailao Mountain, Yunnan Province

Using the closed-top tube incubation method, we examined the soil nitrogen (N) mineralizationand nitrification in the primary Lithocarpus xylocarpus forest, a secondary oak forest and a tea plantationin the Ailao Mountain, Yunnan Province, China. This study was conducted in the dry season fromNovember 20, 1998 to May 15, 1999. Results showed that there were significant differences among thethree vegetation types in both net N mineralization and nitrification rates, and they also demonstratedtemporal variation. The net ammonification rate (RA) was much higher than net nitrification rate (RN), andthe latter was about 0.5%-10% of the former. Our results indicated that incubation period, vegetation typeand the location of plot all interactively affected RA, RN and net mineralization rate (RM). We providedevidence that anthropogenic disturbances could result in changes of ecosystems processes such as Nmineralization and nitrification rates. It is obvious that tea plantation and secondary growth forest havemore physically (mainly temperature and moisture) controlled N transformation processes than thewell-preserved primary L. xylocarpus forest, implying that the conservation of primary forest ecosystemsin the Ailao Mountain region should be emphasized.

Theoretical Study on Decomposition of CF3OH Catalyzed by Water Dimer and Ammonia

The G3 and CBS-QB3 theoretical methods are employed to study the decomposition of CF3OH into FCFO and HF by water, water dimmer, and ammonia. The decomposition of CF3OH into FCFO and HF is unlikely to occur in the atmosphere due to the high activated energy of 88.7 k J/mol at the G3 level of theory. However, the computed results predict that the barrier for unimolecular decomposition of CF3OH is decreased to 25.1 kJ/mol from 188.7 k J/mol with the aid of NH3 at the G3 level of theory, which shows that the ammonia play a strong catalytic effect on the split of CF3OH. In addition, the calculated rate constants show that the decomposition of CF3OH by NH3 is faster than those of H2O and the water dimmer by 10^9 and 10^5 times respectively. The rate constants combined with the corresponding concentrations of these species demonstrate that the reaction CF3OH with NH3 via TS4 is of great importance for the decomposition of CF3OH in the atmosphere.

Effect of Shrimp(Litopenaeus vannamei) Farming Waste on the Growth, Digestion, Ammonium-Nitrogen Excretion of Sea Cucumber(Stichopus monotuberculatus)

In this study, specific growth rate(SGR), ingestion rate(IR), food conversion ratio(FCR), apparent digestion ratio(ADR) and ammonium-nitrogen excretion were determined for sea cucumber(Stichopus monotuberculatus) reared in plastic containers(70 L; 4 containers each diet treatment). Sea cucumbers were fed with five diets containing different amounts of farming waste from shrimp(Litopenaeus vannamei)(100%, 75%, 50%, 25% and 0) and a formulated compound(20% sea mud and 80% powdered algae). Sea cucumbers grew faster when they were fed with diet D(25% shrimp waste and 75% formulated compound) than those fed with other diets. Although IR value of sea cucumber fed with diet A(shrimp waste) was higher than those fed with other diets, both the lowest SGR and the highest FCR occurred in this diet group. The highest and the lowest ADR occurred in diet E(formulated compound) and diet A group, respectively, and the same to ammonium-nitrogen excretion. The contents of crude protein, crude lipid and total organic matter(TOM) in feces decreased in comparison with corresponding diets. In the feces from different diet treatments, the contents of crude protein and TOM increased gradually as the contents of crude protein and TOM in diets increased, while crude lipid content decreased gradually as the crude lipid content in diets increased.

Effects of salinity and body mass on oxygen consumption and ammonia excretion of mudskipper Boleophthalmus pectinirostris

We evaluated the effects of salinity and body mass on the oxygen consumption rate and ammonia excretion rate of mudskipper Boleophthalmus pectinirostris under laboratory conditions. Salinity and body mass had highly significant effects on the oxygen consumption rate （Ro） and ammonia excretion rate （RN） （P〈0.01）. The interactive effects between salinity and body mass on Ro and RN were insignificant （P〉0.05） and highly significant （P〈0.01）, respectively. Ro and RN of B. pectinirostris decreased significantly as the individual body mass increased. The relationship between Ro and body mass was represented by Ro=aWb （R^2=0.956, P〈0.01）. The relationship between RN and the body mass ofB. pectinirostris was represented by RN-cW^at （R^2=0.966, P〈0.01）. The Ro/RN （O：N） ratios increased significantly as the salinity increased from 12 to 27, but decreased as salinity increased from 27 to 32. The atomic O：N ratios were significantly higher at 27 than at other salinity levels. The average O：N ratio was 25.25. Lipid and carbohydrate were the primary energy sources and protein was the secondary energy significantly higher at 27 than at other salinity levels B, pectinirostris is 27. source within the salinity range 12 32. Ro andRN were Our results suggest that the optimum salinity level for B. pectinirostris is 27.

Removal of Microcystin-LR in Water by Chlorine Dioxide

Microcystins （ MCs ） are well known as hepatotoxins produced by blooms of toxic cyanobacteria （blue-green algae） abundant in surface water used as drinking water resource and have drawn attention of environmentalists world over by leading to adverse health effects. A study on efficiency and reaction kinetics of microcystin-LR （ MC-LR ） degradation by CIO2 was performed. Experimental results indicated that MC-LR was removed by CIO2 effectively and the residual concentration of MC-LR could meet the national guideline（GB5749 - 2006） （1.0 μg · L^-1）, the efficiency of removal was in positive correlation to CIO2 dosage and reaction time and in negative correlation to initial concentration of MC-LR and pH value, whereas it was affected by temperature slightly. CIO2 dosage was the most important reaction factor on base of the orthogonal test results. The reaction was second order overall and first order with respect to both CIO2 and MC- LR, and had an activation energy of 78.81 kJ · mo1^-1 . The reaction rate constant was 4.74× 10-^2 L/（mol · min） at 10 ℃. Therefore, oxidation of CIO~ could be taken as an effective technology for removing MC-LR from drinking water resources in traditional drinking water supplies.

Effect of germination on the nutritional quality of Pearl millet

Changes in proximate composition, trypsin inhibitor activity, phytic acid, tannins, in vitro protein digestibility and amino acids content of Pearl millet were investigated after germination for 5 days. Germination significantly increased protein content of pearl millet, with a parallel decrease in lipid and carbohydrates. Trypsin inhibitor activity and the phytic acid content showed significant decrease whereas tannin content increased after 5 days germination. In vitro protein digestibility （IVPD） was significantly decreased with germination, suggesting that tannins may be responsible for enzymes inhibition. Amino acid analysis revealed significant increase in essential amino acids and none essential amino acids.

Promotive Effects of Alginate-Derived Oligosaccharides on the Inducing Drought Resistance of Tomato

In order to determine the role of alginate-derived oligosaccharides (ADO) in drought stress resistance of tomato (Ly-copersicon esculentum Miller) seedlings, the leaves were exposed to different concentrations of ADO (0.05%, 0.10%, 0.20%, 0.30% and 0.50%) after drought stress was simulated by exposing the roots to 0.6 molL-1 PEG-6000 solution for 6 h. Changes in biomass, electrolyte leakage and malondialdehyde (MDA), free proline, total soluble sugars (TSS) and abscisic acid (ABA), the enzyme activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and phenylalanine ammonia-lyase (PAL) were measured to investigate the effects of ADO treatment. The results showed that the treatment with an ADO concentration of 0.20% exhibited the highest performance of drought stress resistance in the tomato seedlings by decreasing the electrolyte leakage and the concentration of MDA, increasing the contents of free proline, TSS and ABA, and increasing the activities of CAT, SOD, POD and PAL after treatment with ADO. It is suggested that changes in electrolyte leakage, MDA, osmotic solutes, ABA, anti-oxidative enzyme and PAL activities were responsible for the increased drought stress resistance in tomato seedlings. To our best knowledge, this is the first report of the effect of ADO treatment on enhancing the drought stress resistance of tomato seedlings.

Experimental Research on Coke Wastewater Treatment by Hybrid Biological Reactor

Phase hybrid biological reactor （HBR） was used in treating coke wastewater by adding submerging fiber-ball fillers in suspended growth activated sludge. The optimum operation parameters for the highest performance were determined. It was found that the hybrid biological reactor worked well for the coke wastewater treatment in terms of Chemical Oxygen Demand （COD）, NH4＋ -N and other refractory organic compounds removal efficiencies. Compared with conventional activated sludge system, the removal rate of COD and NH4＋ -N and the nitrating rate were higher and more stable in the hybrid biological reactor. COD of effluent was less than 75 mg/L and the removal rate of COD and NH4＋ -N could be up to 95.0% and 92.5% when COD of influent and NH4＋ -N were less than 700 mg/L and 300 rag/L, respectively. In this way, the quality of effluent concentration could reach the first class of integrated wastewater discharge standard （GB8978-1996） （COD ≤100 mg/L）.

Modelling the Hydrogen Inhibition Effect on Ammonia Decomposition

Recently ammonia has been investigated as a fuel for SOFCs （solid oxide fuel cells）. Ammonia is widely produced and transported globally, and stores hydrogen in its bonds making it an excellent fuel for fuel cells. The high temperature of SOFCs allows for internal decomposition of ammonia. Previous models of ammonia-fed SOFCs treat ammonia decomposition as having first order dependence on ammonia partial pressure, and ignore the effect of hydrogen inhibition. However, research has shown that at low temperatures （≤ 600 ℃） and low ammonia partial pressures, the rate of ammonia decomposition is inhibited by the presence of hydrogen. This hydrogen inhibition effect was studied and implemented in a model of an ammonia decomposition reactor. Results showed that it may significantly decrease the rate of hydrogen generation. This work sets the foundation for more accurate modelling of intermediate temperature ammonia-fed SOFCs.