城市污水处理工艺的对比研究

介绍了包头市现有五座城市污水处理厂概况,分析了处理工艺低温的适应性。通过分析其中三座采用不同工艺相似水质污水处理厂的进、出水水质,研究不同处理工艺的处理效果。通过设定相同处理规模,分析三种不同工艺相同规模污水处理厂的经济性。最终得出目前包头市处理效果最佳、经济性最优的城市污水处理工艺,为包头市城市污水处理厂提标改造提供参考。     

关于黑龙江省大气污染物减排指标的分析

总量减排已成为环保工作的重中之重,按照十二五大气污染物减排指标,重点关注了二氧化硫、氮氧化物的排放情况。从全省、区域、行业等多角度展开研究,以期弄清黑龙江省大气环境中两项减排指标的排放现状。     

地表水中氨氮和总氮的相关性分析

为了解地表水中氨氮和总氮之间的相关关系,通过2010年濮阳市6个监测点位地表水的氨氮和总氮的监测数据,分析了氨氮和总氮之间的相关性,结果表明:地表水氨氮和总氮两个监测因子之间的相关关系为冬季最好R为0.9270,春、秋其次R分别为0.8980和0.8695,最后是夏季为0.6780。氨氮和总氮之间的比例系数波动范围较大为0.040～1.138,各不同季节的平均值为0.38。     

ASM3在城市污水处理厂工艺调整中的应用

现今城市污水处理厂氨氮处理能力不强,工艺改进实验需要大量资金投入,为了解决这一问题．结合国际水质协会（IWA）开发推荐的活性污泥模型（ASM3）数学模型来寻找一个最佳的解决方案,以便对污水处理厂工艺优化分析及模拟优化改造。     

Review of greenhouse gas emissions from crop production systems and fertilizer management effects

Fertilizer nitrogen (N) use is expanding globally to satisfy food, fiber, and fuel demands of a growing world population. Fertilizer consumers are being asked to improve N use efficiency through better management in their fields, to protect water resources and to minimize greenhouse gas (GHG) emissions, while sustaining soil resources and providing a healthy economy. A review of the available science on the effects of N source, rate, timing, and placement, in combination with other cropping and tillage practices, on GHG emissions was conducted. Implementation of intensive crop management practices, using principles of ecological intensification to enhance efficient and effective nutrient uptake while achieving high yields, was identified as a principal way to achieve reductions in GHG emissions while meeting production demands. Many studies identified through the review involved measurements of GHG emissions over several weeks to a few months, which greatly limit the ability to accurately determine system-level management effects on net global warming potential. The current science indicates: (1) appropriate fertilizer N use helps increase biomass production necessary to help restore and maintain soil organic carbon (SOC) levels; (2) best management practices (BMPs) for fertilizer N play a large role in minimizing residual soil nitrate, which helps lower the risk of increased nitrous oxide (N₂O) emissions; (3) tillage practices that reduce soil disturbance and maintain crop residue on the soil surface can increase SOC levels, but usually only if crop productivity is maintained or increased; (4) differences among fertilizer N sources in N₂O emissions depend on site- and weather-specific conditions; and (5) intensive crop management systems do not necessarily increase GHG emissions per unit of crop or food production; they can help spare natural areas from conversion to cropland and allow conversion of selected lands to forests for GHG mitigation, while supplying the world's need for food, fiber, and biofuel. Transfer of the information to fertilizer dealers, crop advisers, farmers, and agricultural and environmental authorities should lead to increased implementation of fertilizer BMPs, and help to reduce confusion over the role of fertilizer N on cropping system emissions of GHGs. Gaps in scientific understanding were identified and will require the collaborative attention of agronomists, soil scientists, ecologists, and environmental authorities in serving the immediate and long-term interests of the human population.     

旱作农业土壤矿质态氮随地表径流迁移特征研究

为了了解旱作农业土壤中氮素随地表径流的流失水平及规律,于野外夏玉米试验田中进行了模拟降雨与自然降雨条件下的对比试验,并通过对水量和水质的同步监测,研究了不同施肥水平下氮素的流失效应.其中,模拟降雨采用的两个降雨强度分别为40和70mm.h-1,3个尿素施肥水平分别为287、431和575kg.hm-2(以N计),每次自然降雨的试验小区布置相同.试验期间,共有20次降雨事件(包括模拟降雨),其中,4次降雨过程中产生了地表径流并有氮素流失.结果表明,次降雨径流过程中硝态氮流失浓度先迅速增大后逐步降低,而铵态氮流失浓度变化平稳,且流失浓度较低.次降雨间氮素流失平均浓度相差较大,尤其体现在硝态氮浓度上更为明显.此外,研究发现,次降雨径流过程地表氮素流失初期效应明显,且受降雨强度影响显著.通过氮素流失水平的计算发现,研究区大于25mm的降雨类型会有明显的地表径流产生及氮素流失.     

Particle size distribution and pollutants in road-deposited sediments in different areas of Zhenjiang,China

An understanding of road-deposited sediment (RDS) characteristics on an impervious surface is essential to estimate pollutant washoff characteristics and to minimise the impacts of pollutants on the water environment. A total of 62 RDS samples were collected from four different land-use types (commercial, residential, intense traffic and riverside park) in Zhenjiang City, China. The samples were fractionated into seven grain-size classes and analysed for particle size distribution and concentrations of pollutants. The samples are found to consist predominantly of fine particles (60–80%, <250 μm). The maximum mean concentrations of zinc, lead and copper were 686.93, 589.19 and 158.16 mg/kg, respectively, with the highest metal concentrations found in samples from the intense traffic area. The maximum mean contents of organic matter (12.55%), nitrogen (6.31 mg/g) and phosphorus (5.15 mg/g) were found in samples from the commercial area. The concentrations of heavy metals were highest in the smallest particle size fraction analysed (63 μm). The organic matter and nitrogen content generally increased with decreasing particle sizes in the <500-μm particle size range. The results also revealed that most of the total nitrogen (TN) is attached to the finer sediments and that to effectively reduce TN loads in particulates, treatment facilities must be able to remove the finer particles (down to 125 μm for TN).     

Nitrogen dynamics in the sediments of a wetland coastal ecosystem of southern India

The study area, Kuttanad Waters is a part of the Cochin estuarine system on the west coast of India. Kuttanad is well known for its agricultural activity and so the major contribution to the inorganic ions of nitrogen will be from fertilisers applied in agriculture. Based on observed salinity the stations have been divided into three zones. The fresh water zones had higher quantities of silt and clay whereas the estuarine zone was more sandy. The chemical speciation scheme applied here distinguishes three forms of ammoniacal nitrogen species: exchangeable, fixed, and organic ammoniacal nitrogen. No significant trends were observed in the seasonal distribution of total, exchangeable, fixed and organic nitrogen. A significant concentration of exchangeable ammonia was observed in the sediment due to their predominantly reducing environment, which restricts nitrification. High NH₄-N concentrations in the pore waters, along with the sedimentary composition leads to a significantly high quantity of fixed NH₄-N. The low values for N org is due to high mineralisation or deamination of organic nitrogen     

Varying water column stability controls the denitrification process in a subtropical reservoir, Southwest China

Reservoirs are regarded as hotspots of nitrogen transformation and potential sources of nitrous oxide（N₂O）. However, it remains unclear how the hydrological conditions due to dam construction control the processes of nitrogen transformation in reservoir waters. To address this issue, we examined the spatial-temporal characteristics of nitrate concentrations, δ¹⁵N-NO₃^-, δ¹⁸O-NO₃^-, δ¹⁸O-H₂O, relative...     

Effect of culture conditions on the formation of struvite by Myxococcus xanthus

The amount of struvite (MgNH₄PO₄·6H₂O) produced by Myxococcus xanthus as well as the culture parameter values (pH, total phosphorus, total Kjeldahl nitrogen) were dependent on the culture medium used. Struvite formation started during the exponential phase and the maximum concentration was observed at the beginning of stationary growth phase. The addition of each medium component to the liquid culture influenced the amount of crystal produced. This amount did not depend on the pH increase during the culture period. The moment of the bacterial growth phase, at which each medium component was added, influenced the struvite formation.