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251.
含单环芳香烃废水的超声降解实验研究 总被引:6,自引:0,他引:6
利用超声波译水体中的单环芳香烃降解进行探索性试验。结果表明,超声辐照70min,含单环芳香烃废水的降解规律基本遵循一级反应动力学;超声辐照90min,初始浓度为2.295~14.57mg/L的含苯废水,却除率可达到99%以上。 相似文献
252.
磷(P)是控制水体生态系统生产力的重要元素,了解陆地与水体间P的迁移特征,是了解控制水体生态系统中P有效供给的重要途径。本研究选择青藏高原东缘贡嘎山海拔2800 m左右峨眉冷杉林带中一小湖泊——草海子及其流域,通过对流域内土壤、湖泊沉积物中P的形态组成分析,探讨流域内P的形态组成及其迁移特征。结果表明,草海子流域内土壤成土母质中的磷以Ca-P为主,表层土壤中的磷以Al、Fe结合态为主,占总磷的49%~80%,而湖泊沉积物中Al、Fe结合态P下降到46%左右。在成土作用及植物吸收的过程中P由土壤剖面下部向上迁移,迁移的主要形态为树脂提取态(或称可交换态,R-P),而R-P还是由陆地向水体迁移的主要形态P。土壤的Al、Fe结合态P难以释放转化,因此少有随地表径流迁移向湖泊。 相似文献
253.
5种植物沉床系统对富营养化水体修复效果研究 总被引:1,自引:0,他引:1
以狐尾藻、马来眼子菜、金鱼藻、伊乐藻和苦草5种沉水植物为试验材料,构建以沉水植物为核心的人工沉床,探讨富营养化水体中沉水植物的生长状况和沉水植物沉床系统对氮、磷和COD_(Mn)的净化效果。结果表明:5种沉水植物在富营养水体中生长良好,生物量明显增加,以金鱼藻生物量最大。5种沉水植物沉床系统对富营养化水体中的TP、TN和NH_4~+-N去除率较高,均值分别为70.16%、79.60%、79.82%,而对COD_(Mn)的去除率较低,平均为39.74%;其中金鱼藻沉床系统对富营养化水体中的TP、TN、氨氮、COD_(Mn)去除率均最高,分别为79.76%、85.23%、85.81%和46.16%。因此,金鱼藻沉床系统对富营养化水体修复效果最好,同时金鱼藻也是该沉床系统的优选植物。 相似文献
254.
255.
采用多种形式的塘和湿地组合生态工艺完善传统的生态塘和湿地系统,能实现系统处理环境的多样化,提升对氮、磷的去除效能。对山东某组合生态处理系统的研究表明,组合生态处理系统能够有效提升对氮、磷营养物的去除效果。各生态单元水环境的差异影响着氮和磷的主导去除机制,使氮、磷表现出不同的季节去除规律。其中氮的去除主要依靠生物的硝化反硝化作用。底泥中的磷按照Fe-P>OPalk>Al-P>Ca-P>OPres逐渐变为Ca-P>Fe-P>Al-P>OPalk>OPres,与磷共沉降逐渐成为的主导去除机制。 相似文献
256.
采用由生物浮床、生物接触氧化以及河道生态系统构成的生态组合系统处理农村生活污水,考察了其对农村生活污水的净化效果以及季节和污水停留时间(HRT)对污染物的去除效果的影响。结果表明,该组合系统对污染物具有良好的去除效果,COD,NH4+-N,TN,TP的平均去除率分别为57.68%,51.13%,52.38%和49.02%。污染物的去除率随HRT的增加而提高,4 d后变化趋于平缓,在HRT为6 d时,NH4+-N,TN,TP和COD的去除率分别达到80.36%,72.85%,60.74%和71.97%。与秋季相比,夏季时该组合系统对NH4+-N,TN,TP的去除率相对较高,但季节变化对COD去除效果的影响不大。 相似文献
257.
258.
以生活污水作为处理对象,采用双泥折流板反应器,进行了反硝化除磷的启动运行试验研究。在进水有机负荷为0.5kg/(m^3.d),m(C)lm(N)=5,t=30(+0.5)℃,HRT=11.08h,R=0.4,r=0.38,SRT=20d的条件下,系统对CODCr,TN,TP,氨氮的去除率分别为67%,63%,50%和82%,出水质量浓度分别为70mg/L,18mg/L,2.8mg/L,6.8mg/L.表明采用该装置进行反硝化除磷的研究是可行的。 相似文献
259.
Estimation of Nitrogen and Phosphorus in Effluent from the Striped Catfish Farming Sector in the Mekong Delta,Vietnam 总被引:1,自引:0,他引:1
In this study an attempt is made to estimate nitrogen and phosphorus discharged to the environment from the striped catfish
(Pangasianodon hypophthalmus) farming sector in the Mekong Delta (8°33′–10°55′N, 104°30′–106°50′E), South Vietnam. The sector accounted for 687,000 t
production in 2007 and 1,094,879 t in 2008, with over 95% of the produce destined for export to over 100 countries. Commercial
and farm-made feeds are used in catfish farming, currently the former being more predominant. Nitrogen discharge levels were
similar for commercial feeds (median 46.0 kg/t fish) and farm-made feeds (median 46.8 kg/t fish); whilst, phosphorus discharge
levels for commercial feeds (median 14.4 kg/t fish) were considerably lower than for farm-made feeds (median 18.4 kg/t fish).
Based on the median nutrient discharge levels for commercial feeds, striped catfish production in the Mekong Delta discharged
31,602 t N and 9,893 t P, and 50,364 t N and 15,766 t P in 2007 and 2008, respectively. However, the amount of nutrients returned
directly to the Mekong River may be substantially less than this as a significant proportion of the water used for catfish
farming as well as the sludge is diverted to other agricultural farming systems. Striped catfish farming in the Mekong Delta
compared favourably with other cultured species, irrespective of the type of feed used, when the total amounts of N and P
discharged in the production of a tonne of production was estimated. 相似文献
260.
Temporal variability of groundwater chemistry in shallow and deep aquifers of Araihazar, Bangladesh 总被引:2,自引:0,他引:2
Dhar RK Zheng Y Stute M van Geen A Cheng Z Shanewaz M Shamsudduha M Hoque MA Rahman MW Ahmed KM 《Journal of contaminant hydrology》2008,99(1-4):97-111
Samples were collected every 2-4 weeks from a set of 37 monitoring wells over a period of 2-3 years in Araihazar, Bangladesh, to evaluate the temporal variability of groundwater composition for As and other constituents. The monitoring wells are grouped in 6 nests and span the 5-91 m depth range. Concentrations of As, Ca, Fe, K, Mg, Mn, Na, P, and S were measured by high-resolution ICPMS with a precision of 5% or better; concentrations of Cl were measured by ion chromatography. In shallow wells <30 m deep, As and P concentrations generally varied by <30%, whereas concentrations of the major ions (Na, K, Mg, Ca and Cl) and the redox-sensitive elements (Fe, Mn, and S) varied over time by up to +/-90%. In wells tapping the deeper aquifers >30 m often below clay layers concentrations of groundwater As were much lower and varied by <10%. The concentrations of major cations also varied by <10% in these deep aquifers. In contrast, the concentration of redox-sensitive constituents Fe, S, and Mn in deep aquifers varied by up to 97% over time. Thus, strong decoupling between variations in As and Fe concentrations is evident in groundwaters from shallow and deep aquifers. Comparison of the time series data with groundwater ages determined by (3)H/(3)He and (14)C dating shows that large seasonal or inter-annual variations in major cation and chloride concentrations are restricted to shallow aquifers and groundwater recharged <5 years ago. There is no corresponding change in As concentrations despite having significant variations of redox sensitive constituents in these very young waters. This is attributed to chemical buffering due to rapid equilibrium between solute and solid As. At two sites where the As content of groundwater in existing shallow wells averages 102 microg/L (range: <5 to 648 microg/L; n=118) and 272 microg/L (range: 10 to 485 microg/L; n=65), respectively, a systematic long-term decline in As concentrations lends support to the notion that flushing may slowly deplete an aquifer of As. Shallow aquifer water with >5 years (3)H/(3)He age show a constant As:P molar ratio of 9.6 over time, suggesting common mechanisms of mobilization. 相似文献