模糊层次分析法在保定市城镇污水处理技术综合评价中的应用

基于保定市城镇生活污水处理技术,采用改进的模糊层次分析法建立一个4层12个指标8种方案的综合评价体系,从经济、技术和管理等角度对氧化沟工艺、CASS工艺、UNITANK工艺、百乐克工艺、CAST工艺、A2/O与百乐克结合工艺、倒置A2/O工艺、A2/O工艺8种处理工艺进行综合评价。同时采用专家打分法对8种技术进行评价,结果表明CASS工艺的分值最高。     

Effect of nitrate concentration on filamentous bulking under low level of dissolved oxygen in an airlift inner circular anoxic-aerobic incorporate reactor

This laboratory research investigated a possible cause of filamentous bulking under low level of dissolved oxygen conditions (dissolved oxygen value in aerobic zone maintained between 0.6-0.8 mgO2 /L) in an airlift inner-circular anoxic-aerobic reactor. During the operating period, it was observed that low nitrate concentrations affected sludge volume index significantly. Unlike the existing hypothesis, the batch tests indicated that filamentous bacteria (mainly Thiothrix sp.) could store nitrate temporarily under carbon restricted conditions. When nitrate concentration was below 4 mg/L, low levels of carbon substrates and dissolved oxygen in the aerobic zone stimulated the nitrate-storing capacity of filaments. When filamentous bacteria riched in nitrate reached the anoxic zone, where they were exposed to high levels of carbon but limited nitrate, they underwent denitrification. However, when nonfilamentous bacteria were exposed to similar conditions, denitrification was restrained due to their intrinsic nitrate limitation. Hence, in order to avoid filamentous bulking, the nitrate concentration in the return sludge (from aerobic zone to the anoxic zone) should be above 4 mg/L, or alternatively, the nitrate load in the anoxic zone should be kept at levels above 2.7 mg NO-3N/g SS.     

Methane emissions from rice fields under continuous straw return in the middle-lower reaches of the Yangtze River

A three-year experiment was conducted in the middle-lower reaches of the Yangtze River in China to study the influence of continuous wheat straw return during the rice season and continuous rice straw return in wheat on methane (CH 4 ) emissions from rice fields in which, the rice-wheat rotation system is the most dominant planting pattern. The field experiment was initiated in October 2009 and has continued since the wheat-growing season of that year. The analyses for the present study were conducted in the second (2011) and third (2012) rice growing seasons. Four treatments, namely, the continuous return of wheat straw and rice straw in every season (WR), of rice straw but no wheat straw return (R), of wheat straw but no rice straw return (W) and a control with no straw return (CK), were laid out in a randomized split-plot design. The total seasonal CH 4 emissions ranged from 107.4 to 491.7 kg/ha (2011) and 160.3 to 909.6 kg/ha (2012). The increase in CH 4 emissions for treatments WR and W were 289% and 230% in the second year and 185% and 225% in the third year, respectively, in relation to CK. We observed less methane emissions in the treatment R than in CK by 14%-43%, but not statistically significant. Treatment R could increase rice productivity while no more CH 4 emission occurs. The difference in the total CH 4 emissions mainly related to a difference in the methane flux rate during the first 30-35 days after transplant in the rice growing season, which was caused by the amount of dissolved oxygen in paddy water and the amount of reducible soil materials.     

Effect of dissolved organic matter on nitrate-nitrogen removal by anion exchange resin and kinetics studies

The effects of dissolved organic matter (DOM) on the removal of nitrate-nitrogen from the model contaminated water have been investigated utilizing the strong base anion exchange resins. With the increase of gallic acid concentration from 0 to 400 mg/L, the adsorption amount of nitrate-nitrogen on the commercial resins, including D201, Purolite A 300 (A300) and Purolite A 520E (A520E), would significantly decrease. However, the presence of tannin acid has little impact on nitrate-nitrogen adsorption on them. Compared to D201 and A300 resins, A520E resin exhibited more preferable adsorption ability toward nitrate-nitrogen in the presence of competing organic molecules, such as gallic acid and tannin acid at greater levels in aqueous solution. Attractively, the equilibrium data showed that the adsorption isotherm of nitrate-nitrogen on A520E resin was in good agreement with Langmuir and Freundlich equations. The rate parameters for the intra particle diffusion have been estimated for the different initial concentrations. In batch adsorption processes, nitrate-nitrogen diffuse in porous adsorbent and rate process usually depends on t 1/2 rather than the contact time. The pseudo first- and the second-order kinetic models fit better for nitrate-nitrogen adsorption onto A520E resin. The observations reported herein illustrated that A520E resin will be an excellent adsorbent for enhanced removal of nitrate-nitrogen from contaminated groundwater.     

Life cycle and economic assessment of enhanced ecological floating beds applied water purification

Environmental Science and Pollution Research - The ecological floating beds (EFB) are widely used in water quality restoration because of its low cost, high efficiency, and green characteristics....     

采暖锅炉氧腐蚀的原因与防腐对策

热水锅炉及其采暖系统在运行和停运期间都存在较严重的氧腐蚀,但由于主客观原因的限制,并没有引起人们的高度重视.氧腐蚀对锅炉及其采暖系统运行的安全性和经济性造成重大影响,严重时引起爆管,被迫停炉等危害.大力提倡节能减排的今天,延长锅炉的寿命,促进安全经济生产意义重大.本论文分析总结采暖锅炉目前的水质与防腐工作的现状,同时提出了对采暖锅炉今后锅炉及热力管网防腐的对策.     

液桥凝聚用于办公废纸脱墨的研究

研究了混合办公废纸脱墨的选择性凝聚技术，在废纸浆中添加分散在水中并不与水相溶的长链烷作凝聚剂，这些凝聚剂选择性地将印刷墨粉通过液桥连结在一起，且形成大颗粒的球形聚团，再分选脱除。研究表明只需要加入占纸重量4％的廉价长链烷，即可获得95％以上的脱墨率。因此在混合办公废纸脱墨时加入凝聚剂进行液桥凝聚，可降低脱墨浆中的尘埃度并增加产品的白度。     

Advances in emission control of diesel vehicles in China

Diesel vehicles have caused serious environmental problems in China. Hence, the Chinese government has launched serious actions against air pollution and imposed more stringent regulations on diesel vehicle emissions in the latest China VI standard. To fulfill this stringent legislation, two major technical routes, including the exhaust gas recirculation (EGR) and high-efficiency selective catalytic reduction (SCR) routes, have been developed for diesel engines. Moreover, complicated aftertreatment technologies have also been developed, including use of a diesel oxidation catalyst (DOC) for controlling carbon monoxide (CO) and hydrocarbon (HC) emissions, diesel particulate filter (DPF) for particle mass (PM) emission control, SCR for the control of NOx emission, and an ammonia slip catalyst (ASC) for the control of unreacted NH₃. Due to the stringent requirements of the China VI standard, the aftertreatment system needs to be more deeply integrated with the engine system. In the future, aftertreatment technologies will need further upgrades to fulfill the requirements of the near-zero emission target for diesel vehicles.     

海洋石油勘探开发溢油环境污染损害风险可保性研究

海洋石油勘探开发溢油污染是最为严重的海洋环境损害之一,其发生带来了巨额的赔偿、补偿。因此,开展海洋石油勘探开发溢油环境污染损害责任保险的专项研究十分重要,风险可保性作为确定保险标的的关键是研究的基础。本文运用法学及经济学理论,分析了海洋石油勘探开发溢油环境污染损害风险基于可保性“经典定义”存在的不足,以及基于可保性“现代定义”优化的可行性。同时,运用海洋数值模拟技术,选取渤海为示例海域,分析了溢油污染损害风险影响范围的可预测性,论证了海洋石油勘探开发溢油环境污染损害风险的可保性。     

江西锦江流域抗生素污染特征与生态风险评价

利用固相萃取-超高效液相色谱串联质谱法,测定分析了江西省锦江流域地表水、地下水、生活污水和养殖废水中8种磺胺类、9种喹诺酮类、4种四环素类、4种大环内酯类和2种硝基咪唑类共27种抗生素的浓度和分布特征.结果表明,锦江流域水体存在抗生素的污染,地表水中共检出20种抗生素,浓度范围为32.3~280 ng·L^-1.地下水中检出15种抗生素,浓度范围为28.4~55.8 ng·L^-1.废水中检出21种抗生素,浓度范围为231~8.71×10⁴ ng·L^-1.与国内外河流湖泊中8种常见抗生素浓度进行对比表明,锦江流域污染程度处于中等水平.对比国内外地下水中磺胺甲唑浓度可知,锦江流域地下水中磺胺甲唑污染程度中等偏下.与国内外养殖厂废水中3种抗生素浓度对比可知,锦江流域养殖废水中磺胺嘧啶的污染程度较高.生态风险评价结果表明,研究区中高风险抗生素有9种,分别是克拉霉素、红霉素、环丙沙星、磺胺噻唑、罗红霉素、四环素、氧氟沙星、恩诺沙星和磺胺甲唑,其余为低风险或无风险.