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741.
Morphological changes in flocs were elucidated by small-angle light scattering, free settling tests and microscopic observation to determine the effects of pre-hydrolysis (alkaline treatment and ultrasonication) on two sludges--primary raw sludge from the Malabar Sewage Treatment Plant, Sydney (sludge M) and biological sludge collected at the nitrogen removal unit of St Marys Sewage Treatment Plant in Sydney (sludge S). Ultrasonication or alkaline treatment released a marked amount of insoluble organic matter in a soluble form. The latter treatment was more efficient than the former. Meanwhile, the pre-hydrolyzed flocs had more compact structures than the original ones, as shown by their higher free-settling fractal dimension, lower areal porosity and smaller internal pores. In particular, alkaline treatment yielded flocs with more compact interiors than did ultrasonication. Such detailed structural information could not be elicited by monitoring the change in floc size. The greater resistance to mass transfer of the hydrolyzed flocs thus produced does not reduce the efficiency of subsequent digestion, indicating that the surface reaction rate on the solid surface might have dominated since the pre-hydrolysis steps modified the local chemical environment to promote digestion. 相似文献
742.
Grease traps are widely used by most restaurants and food processing industries in Hong Kong to reduce oil and grease to an acceptable level before it can be discharged to public sewers. To meet demanding effluent standards in the future, it is necessary to polish the effluent by upgrading the conventional trap design. This study evaluated the possibility of upgrading traditional grease traps by installing tube settlers inside the trap. Their efficiency of removing chemical oxygen demand (COD) and oil/grease was examined to justify the performance. It was found that installing a tube settler is a feasible and cheap way to upgrade the conventional grease trap, since it improved oil/grease removal efficiency by 8-10% compared to the conventional design. In addition, a remarkable improvement in COD removal was observed following a very short hydraulic detention time after the installation of tube settlers. This ensured acceptable effluent quality under peak flowrates. Two mathematical models were also proposed to facilitate trap design. 相似文献
743.
Xiaona Chu Jiangyong Hu Say Leong Ong 《Frontiers of Environmental Science & Engineering in China》2009,3(4):393-403
Proteomics involves the separation of proteins, identification of the amino acid sequence of the interested or target proteins,
study of the function of the proteins, modification, structure and ultimate assignments to functional pathways in the cell.
The proteomic investigations have contributed greatly to human diseases studies, new drugs discovery researches, and environmental
science in recent years. This article provides a review on the development of the main proteomic technologies, including both
the gel based and non-gel based technologies, and their applications in environmental science. Proteomic technologies have
been utilized in the environmental stresses studies to analyze the induction or reduction of proteins at expression level
and identify the target proteins to investigate their function in response to environmental stresses, such as high or low
pH, oxidation stress, and toxic chemicals. Such protein responses are also helpful to understand the mechanisms of some cellular
activities and the functions of some proteins. 相似文献
744.
745.
Zhihua Liu Asad Naeem Shah Yunshan Ge Yan Ding Jianwei Tan Lei Jiang Linxiao Yu Wei Zhao Chu Wang Tao Zeng 《环境科学学报(英文版)》2011,23(5):798-807
The effects of continuously regenerating diesel particulate filter (CRDPF) systems on regulated gaseous emissions, and number-size
distribution and mass of particles emanated from a diesel engine have been investigated in this study. Two CRDPF units (CRDPF-1
and CRDPF-2) with di erent specifications were separately retrofitted to the engine running with European steady-state cycle (ESC).
An electrical low pressure impactor (ELPI) was used for particle number-size distribution measurement and mass estimation. The
conversion/reduction rate (RCR) of hydrocarbons (HC) and carbon monoxide (CO) across CRDPF-1 was 83% and 96.3%, respectively.
Similarly, the RCR of HC and CO and across CRDPF-2 was 91.8% and 99.1%, respectively. The number concentration of particles
and their concentration peaks; nuclei mode, accumulation mode and total particles; and particle mass were highly reduced with the
CRDPF units. The nuclei mode particles at downstream of CRDPF-1 and CRDPF-2 decreased by 99.9% to 100% and 97.8% to 99.8%
respectively; and the particle mass reduced by 73% to 92.2% and 35.3% to 72.4%, respectively, depending on the engine conditions.
In addition, nuclei mode particles increased with the increasing of engine speed due to the heterogeneous nucleation initiated by the
higher exhaust temperature, while accumulation mode particles were higher at higher loads due to the decrease in the air-to-fuel ratio
(A/F) at higher loads. 相似文献
746.
排污权交易初始价格定价方案研究 总被引:1,自引:0,他引:1
排污权交易初始分配价格的合理性将在很大程度上决定排污权交易市场的活跃程度,并使排污权交易更好地发挥市场经济手段的最大效用。初始价格的确定依据应为结合排污权时限及贴现率下的不同污染物的社会平均污染治理成本,并兼顾区域经济发展、行业水平、企业公平等因素。文章从定价方式、时限、发布与调整机制、配套措施等方面研究排污权初始价格的定价方案;并以某市为例,通过调查排污量占全市排污量85%以上的企业的污染治理成本,根据所研究的方案获得该市COD、SO2等排污权交易初始分配价格。 相似文献
747.
748.
749.
750.
Xiaolong Wang Jingyi Han Ligang Xu Junfeng Gao Qi Zhang 《Environmental monitoring and assessment》2011,177(1-4):127-139
Contamination of nutrients and heavy metals within aquatic system is of great concern due to its potential impact on human and animal health. The Grand Canal of China, the largest artificial river in the world, is of great importance in supplying water resource, transporting cargo, and recreating resident, as well as great historical heritage. This study assessed and examined the impact of human activities on characters of contamination distribution within the section of the Canal in Taihu watershed. Physicochemical parameters of surface water quality were determined monthly from the year 2004 to 2006 at 11 sites that were influenced by different anthropogenic activities along the Canal. Moreover, contaminations at surface sediments (20 cm) at the same locations were also analyzed in September 2006. Results showed that the Canal had been seriously polluted, which was characterized with high spatial variations in contaminations distribution. The sites influenced mainly by industry and urbanization showed higher contents of nutrients and lower levels of dissolve oxygen than other sites. Concentrations of nitrogen at all studied sites exceeded the worst level of surface water quality according to the National Criterion of Surface Water Quality, China, with the average values varying from 2.27 to 10.34 mg/L. Furthermore, the site influenced mainly by industry (i.e., Site 4) presented the highest contents of cadmium (3.453 mg/kg), chromium (196.87 mg/kg), nickel (87.12 mg/kg), zinc (381.8 mg/kg), and copper (357.32 mg/kg). While sites in vicinity to cities had presented relatively higher contents of metals, especially for the site located downstream of Changzhou City (Site 3) had presented the highest contents of mercury (1.64 mg/kg) and lead (197.62 mg/kg). Copper at Sites 2 to 6, Nickel at Sites 2 to 9 except for Site 7, chromium, lead, and zinc at Sites 3 to 6 had exceeded New York State Department of Environmental Conservation (NYSDEC) Severe Effect Level (SEL). By multivariate statistical, nutrient variables, companied with V-phen, had contributed the most variation of water quality, while nutrient and metals had explained the most part of total variance of contaminations in sediment. This study indicated that the canal had been polluted severely and urgently need to control. 相似文献