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151.
A simple and sensitive spectrophotometric method of measuring electron transfer in the transport system (ETS) in marine phytoplankton has been developed and characterized. The assay is based on the reduction of the tetrazolium salt 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) by homogenates in the presence of the nonionic detergent Triton X-100. The simplicity and sensitivity of this assay have considerable advantage over existing methods of measuring ETS activity in marine samples where numerous assays must be rapidly carried out on samples which often demonstrate low activities. Several established substrates and inhibitors of electron transport in the ETS were investigated, and each is discussed in relation to the site of INT reduction in the diatoms Skeletonema costatum and Chaetoceros debilis and in the unicellular green alga Dunaliella tertiolecta. The results from these studies suggest that the maximum rate of electron transport, V max, is measured in each case. 相似文献
152.
153.
Influence of aeration rate and reactor shape on the composting of poultry manure and sawdust 总被引:1,自引:0,他引:1
Waqas Qasim Byeong Eun Moon Frank Gyan Okyere Fawad Khan Mohammad Nafees 《Journal of the Air & Waste Management Association (1995)》2019,69(5):633-645
To achieve successful composting, all the biological, chemical, and physical characteristics need to be considered. The investigation of our study was based on various physicochemical properties, i.e., temperature, ammonia concentration, carbon dioxide concentration, pH, electrical conductivity (EC), carbon/nitrogen (C/N) ratio, organic matter (OM) content, moisture content, bacterial population, and seed germination index (GI), during the composting of poultry manure and sawdust for different aeration rates and reactor shapes. Three cylindrical-shaped and three rectangular-shaped pilot-scale 60-L composting reactors were used in this study, with aeration rates of 0.3 (low), 0.6 (medium), and 0.9 (high) L min?1 kg?1 DM (dry matter). All parameters were monitored over 21 days of composting. Results showed that the low aeration rate (0.3 L min?1 kg?1 DM) corresponded to a higher and longer thermophilic phase than did the high aeration rate (0.9 L min?1 kg?1 DM). Ammonia and carbon dioxide volatilization were directly related to the temperature profile of the substrate, with significant differences between the low and high aeration rates during weeks 2 and 3 of composting but no significant difference observed during week 1. At the end of our study, the final values of pH, EC, moisture content, C/N ratio, and organic matter in all compost reactors were lower than those at the start. The growth rates of mesophilic and thermophilic bacteria were directly correlated with mesophilic and thermophilic conditions of the compost. The final GI of the cylindrical reactor with an airflow rate of 0.3 L min?1 kg?1 DM was 82.3%, whereas the GIs of the other compost reactors were below 80%. In this study, compost of a cylindrical reactor with a low aeration rate (0.3 L min?1 kg?1 DM) was more stable and mature than the other reactors.
Implications: The poultry industry is growing in South Korea, but there are problems associated with the management of poultry manure, and composting is one solution that could be valuable for crops and forage if managed properly. For high-quality composting, the aeration rate in different reactor shapes must be considered. The objective of this study was to investigate various physicochemical properties with different aeration rates and rector shapes. Results showed that aeration rate of 0.3 L min?1 kg?1 DM in a cylindrical reactor provides better condition for maturation of compost. 相似文献
154.
Organochlorine pesticide residues in catfish,Tachysurus thalassinus (Ruppell, 1835), from the South Patches of the Bay of Bengal 总被引:1,自引:0,他引:1
Twenty-one wild brown rats (Rattus norvegicus) were collected from four areas of Milan (Italy). Main organs were harvested from each rat, fixed in 10% neutral buffer formalin, and embedded in paraffin. Organ sections were stained with hematoxylin and eosin, kidney sections were also stained with the Ziehl-Neelsen method. Graphite furnace atomic absorption spectrophotometry was performed on all kidney samples. The presence of inclusion bodies and karyocytomegaly was scored. Six adult rats out of 21 (28.6%) showed kariocytomegaly and intranuclear inclusion bodies of the renal proximal tubules, characteristic of lead toxicity. The nuclear inclusion bodies were always Ziehl-Neelsen positive. The six rats which showed the characteristic histological alterations ascribed to lead, had lead concentrations statistically higher than the three control rats (4 microg/g wet wt. versus 0.09 microg/g wet wt., P<0.001) and than the captured wild rats. Intranuclear inclusion bodies were found in rats with kidney lead concentrations greater than 0.6 microg/g wet weight. There were significant differences between the four areas of capture. The incidence of intranuclear inclusion bodies and karyocytomegaly in proximal tubular cells was higher in rats with high lead levels detected by spectrophotometry. The present results indicate a renal lead concentration of 0.6 microg/g wet weight as a threshold to detect histologic kidney changes due to lead absorption. Results demonstrate that the examination of adult free-living rats may be considered an appropriate method to obtain a rapid, sensitive, easy, cost effective estimate of lead contamination in urban areas. Animal models allow us to evaluate potential human health risk associated with environmental contamination. 相似文献
155.
鸡粪厌氧发酵产沼气中H2S含量高,在发电或提纯制备生物燃气前需要对其进行去除.开展批次鸡粪发酵试验,向发酵瓶中通入微量空气,通过生物氧化作用去除H2S.试验以连续稳定运行90d的中温厌氧罐出料为接种污泥,通入7~50mL/gVS的空气.结果表明,空气通入显著地降低了沼气中的H2S浓度,空气通入量为30mL/gVS的实验组平均脱硫效率最高,达到62%.同时,该空气通入条件下累积甲烷产量达到335mL/gVS,相较于空白累积甲烷产量提升了78.6%.通入微量空气的生物脱硫方法具有工艺简单和高效脱除H2S的应用前景. 相似文献
156.
M. A. Tantawy Salwa A. Ahmed Elham M. Abdalla Mostafa I. Qassim 《Journal of Material Cycles and Waste Management》2016,18(2):263-272
This work aims to study the influence of thermal treatment of Cu2+ laden kaolin wastes on its immobilization efficiency in cement paste. Compressive strength and toxicity characteristic leaching procedure (TCLP) of 5–20 % kaolin waste blended cement pastes were tested. X-ray diffraction (XRD) results illustrate that adsorption of Cu2+ ions modify the crystal structure of kaolinite mineral. Fourier transform infrared (FTIR) results indicate that the adsorption sites on the kaolin surface that were occupied with free water molecules have been replaced with Cu2+ ions adsorbed from aqueous solutions. The thermal treatment of kaolin waste improves fixation ratio of Cu2+ in cement pastes containing up to 20 % of thermally treated waste. This is due to: pozzolanic activity of calcined kaolin, conversion of leachable adsorbed Cu2+ ions into encapsulated unleachable phase that does not retard the hydration of cement as well as adsorption of much of leachable Cu2+ ions on surfaces of hydration products and occlusion in its lattice structure as illustrated from XRD, FTIR, thermogravimetric, scanning electron microscopy and TCLP results. The fixation ratio of Cu2+ in cement paste blended with 20 % of thermally treated kaolin waste, reaches maximum value of about 97 % compared to 82 % for cement paste blended with 20 % of untreated kaolin waste. 相似文献
157.
Ashfaque Ahmed Chowdhury M. G. Rasul M. M. K. Khan 《Water, Air, & Soil Pollution: Focus》2009,9(5-6):517-527
The effects of poor indoor air quality and mould growth in working environment are major problems in built environment, and there is a need to look for improvement of the health, comfort and productivity of the building occupants. Airborne mould sampling studies were conducted in a reference building located in Rockhampton, Central Queensland, Australia. Both indoor culturable and mould spore levels were observed. It was found through the indoor–outdoor ratios of the species that indoor concentrations are mostly related to the outdoor mould levels. The moulds differ in their relative humidity and temperature requirements to support surface growth. Indoor humidity has a significant effect on occupants comfort, perceived air quality, occupants’ health, building durability, emissions and energy efficiency. Practical hygrothermal simulation models are employed to analyse the combined heat and moisture behaviour within the built environment. A review of the current modelling options available to predict building performance based on energy and mass transport simulation is presented, and then a case study is presented with the assessment of indoor built environment to avoid mould problem. 相似文献
158.
Removal of chloride from recycled cooling water is needed to reduce corrosion and prolong equipment life. Laboratory experiments have demonstrated that the ultra-high lime with aluminum (UHLA) process has the ability to achieve high chloride removal efficiency from recycled cooling water. In an effort to further understand the behavior of chloride in the UHLA process, a fundamental model of the chemical processes was developed. The purpose of this paper is to describe this equilibrium model and present values for solubility products of precipitated solids that have not been investigated previously. The model was based on PHREEQC and a new program called INVRS K was integrated with PHREEQC to calculate values of unknown or poorly defined equilibrium or kinetic constants using a Gauss-Newton nonlinear regression routine. Model predictions indicated that the results could be best described by assuming the formation of a solid solution of calcium chloroaluminate (Ca4Al2Cl2OH12), tricalcium hydroxyaluminate (Ca3Al2OH12), and tetracalcium hydroxyaluminate (Ca4Al2OH14). 相似文献
159.
160.