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541.
构建了多级土壤渗漏系统(MSL)以处理农村生活污水,主要研究了MSL的挂膜启动特征,进水水力负荷对MSL处理生活污水性能的影响,以及MSL运行过程中生物膜的特征.实验结果表明,采用连续进水的方式挂膜28d后,挂膜成功,MSL对生活污水中COD,氨氮,TN,TP的去除率分别达到84.5%,74.7%,66.7%,76.4%.MSL运行过程中,表现出对进水水力负荷变化较强的适应性,水力负荷为400L/(m2·d)时,生活污水中COD,氨氮,TN,TP的平均去除率分别达到93.4%,94.9%,80.4%,94.7%,系统出水水质能够满足城镇污水处理厂污染物排放标准(GB18918-2002)一级A标准.MSL对有机物和氮磷的去除途径结果表明,微生物降解和转化作用对污水中COD,氨氮,TN的去除贡献率最大,Fe3+与PO43-的化学沉淀作用则是TP去除的主要途径.实时荧光定量PCR技术检测结果显示,生物膜中硝化功能菌占总菌群的35.5%. 相似文献
542.
Volatilization and biodegradation are major competitive volatile organic compound (VOC) removal mechanisms in biological wastewater
treatment process, which depend on compound specific properties and system design/operational parameters. In this study, a
mathematical model was used to determine major removal pathways at various organic loading rates (OLR), solids residence time
(SRT) and dissolved oxygen (DO) concentrations in a biological process for vinyl acetate. Model results showed that biological
treatment process should be designed with long SRT, high OLR and low DO concentrations to maximize biodegradation and minimize
volatilization of VOCs. Unless a VOC is toxic to microorganisms under the given conditions, low VOC emission rates are an
inherent advantage of MBRs, which operate at higher OLR and longer SRT compared to conventional activated sludge process.
A lab scale membrane bioreactor (MBR) was operated at varying OLR to investigate the relative volatilization and biodegradation
rates for acetaldehyde, butyraldehyde and vinyl acetate. Synthetic wastewater containing three VOCs was introduced to the
MBR. The DO concentration and SRT was maintained at 2.0 mg L− 1 and 100 days, respectively. The overall VOC removal rate was more than 99.7% for three VOCs at all the OLR. For vinyl acetate,
the biodegradation rate increased from 93.87 to 99.40% and the volatilization removal rate decreased from 6.09 to 0.59% as
OLR was increased from 1.1 to 2.0 kg COD m− 3 d− 1. It was confirmed that a MBR can be a promising solution to reduce VOC emissions from wastewater. 相似文献
543.
544.
William F. James Robert H. Kennedy William E. Sham Richard K. Myers 《Journal of the American Water Resources Association》1988,24(4):831-837
ABSTRACT: The impoundment of Richard B. Russell Lake resulted in the inundation of 3490 ha of forested area or 33 percent of the total area of the lake. Estimates of the total inundated leaf litter biomass were combined with a leaf litter decomposition study to determine the nutrient load and dissolved oxygen demand to the reservoir. Hickory leaf bags broke down most rapidly at the 3-m and 28-rn depths, followed by short-needle pine, white oak, a hardwood litter mixture, beech, and red oak. Leaf bags incubated at the 3-m depth exhibited significantly higher breakdown rates than those at the 28-m depth for most leaf types, due to differences in dissolved oxygen and temperature. Respiration rates of litter were also higher at the 3-m depth. Most leaf types accumulated nitrogen and phosphorus and lost organic carbon after an initial leaching period. Richard B. Russell Lake exhibited extensive anoxia and the buildup of total organic carbon, nitrogen, and phosphorus during summer stratification. Leaf litter breakdown accounted for 64 percent of the organic carbon increase but acted as a sink for nitrogen and phosphorus. The dissolved oxygen demand of the litter accounted for over 50 percent of the demand incurred in the lake. 相似文献
545.
546.
The rapid rate of development in the South Carolina (SC) coastal zone has heightened public concern for the condition of the state's estuaries, and alerted scientists to the potential that novel and adverse effects on estuarine ecosystems may result. Although well-developed databases from long-term monitoring programs exist for many variables valuable in predicting and following system responses, information on phytoplankton distributions in SC estuaries has lagged. Knowledge of the dynamical relationship between environmental (e.g., nutrient quantity and quality) and biological (e.g., grazing) regulation, and phytoplankton biomass and composition is critical to understanding estuarine susceptibility to eutrophication or harmful algal blooms (HABs). Recently, SC scientists from federal, state, and academic institutions established a collaborative monitoring program to assess HAB distribution and ecology statewide. The South Carolina Harmful Algal Bloom Program includes: a) intensive temporal monitoring at areas of known HAB occurrence or those exhibiting symptoms potentially related to HABs (e.g., prevalent fish lesions), b) extensive spatial monitoring in coordination with existing statewide efforts, c) a citizen volunteer monitoring network, d) nutrient response bioassays, and e) laboratory-based physiological experiments on HAB isolates. By combining trip-wire surveillance and rapid response systems, routine monitoring of environmental parameters and HAB distribution, and process-oriented studies examining the physiological functioning of HAB species, an enhanced understanding of the impact and environmental control of HABs in SC estuaries will be achieved. The application of this approach to studies on the distribution and physiological ecology of a new widespread SC red tide, and to the discovery of several potentially toxic blooms (including Pfiesteria) in SC holding ponds, are described. 相似文献
547.
本文针对某一具体城市集水区,简要介绍一种污染物集聚模型和冲洗模型参数的率定方法。该方法概念清晰,操作简便,且成果符合实际,有一定精度。 相似文献
548.
针对矿修车间的采煤机截割部的加载问题,研制开发面向维修的采煤机截割部加载试验台,对维修后的采煤机截割部进行加载试验。试验台采用电力测功机加载,节能效果非常明显,加载调节使用方便、结构简单、可靠性高,功能完善。试验台的研制成功有利于提高生产管理水平,有效地避免井下的人机安全事故,有着巨大的经济价值和社会效益。 相似文献
549.
Judy Z. Drexier Barbara L. Bedford Arthur T DeGaetano Donald I. Siegel 《Journal of the American Water Resources Association》1999,35(4):753-769
ABSTRACT: Few water budgets exist for specific types of wetlands such as peatlands, even though such information provides the basis from which to investigate linkages between wetlands and upland ecosystems. In this study, we first determined the water budget and then estimated nutrient loading from an upland farm field into a 1.5 ha, kettle-block peatland. The wetland contains highly anisotropic peat and has no distinct, active layer of groundwater flow. We estimated the depth of the active layer using Fick's law of diffusion and quantified groundwater flow using a chemical mass balance model. Evapotranspiration was determined using MORECS, a semi-physical model based on the Penman-Monteith approach. Precipitation and surface outflow were measured using physical means. Groundwater provided the major inflow, 84 percent (44,418 m3) in 1993 and 88 percent (68,311 m3) in 1994. Surface outflow represented 54 percent (28,763 m3) of total outflows in 1993 and 48 percent (37,078 m3) in 1994. A comparison of several published water budgets for wetlands and lakes showed that error estimates for hydrologic components in this study are well within the range of error estimates calculated in other studies. Groundwater inflow estimates and nutrient concentrations of three springs were used to estimate agricultural nutrient loading to the site. During the study period, nutrient loading into the peatland via groundwater discharge averaged 24.74 kg K ha-1, 1.83 kg total inorganic P had, and 21.81 kg NO3-N ha-1. 相似文献
550.
Jialu SHI Shengnan YI Chao LONG Aimin LI 《Frontiers of Environmental Science & Engineering》2015,9(5):840
In this study, nanoscale zero-valent iron (NZVI) were immobilized within a chelating resin (DOW 3N). To investigate the effect of Fe loading on NZVI reactivity, three NZVI-resin composites with different Fe loading were obtained by preparing Fe(III) solution in 0, 30 and 70% (v/v) ethanol aqueous, respectively; the bromate was used as a model contaminant. TEM reveals that increasing the Fe loading resulted in much larger size and poor dispersion of nanoscale iron particles. The results indicated that the removal efficiency of bromate and the rate constant (Kobs) were decreased with increasing the Fe loading. For the NZVI-resin composite with lower Fe loading, the removal efficiency of bromate declined more significantly with the increase of DO concentrations. Under acidic conditions, decreasing the pH value had the most significant influence on NZVI-R3 with highest Fe loading for bromate removal; however, under alkaline conditions, the most significant influence of pH was on NZVI-R1 with lowest Fe loading. The effects of co-existing anions N O 3 − , P O 4 3 − and H C O 3 − were also investigated. All of the co-existing anions showed the inhibition to bromate reduction. 相似文献