污水生物除磷研究进展

水体富营养化是世界性难题,其中磷通常是主要限制因子.生物除磷工艺简单,污泥产量少,可节约能源,运行费用也较低,便于操作和磷的回收.在介绍水体中磷的来源、污染特点及其造成危害的基础上,着重综述了国内外生物除磷的研究进展,并对生物除磷存在的问题和发展趋势提出了一些看法.     

连续流间歇曝气氧化沟处理生活污水脱氮除磷研究

为了提高低C/N(3.0～3.5)生活污水的脱氮除磷效率,对设置选择池和厌氧池的氧化沟工艺采用了微孔曝气加搅拌的实验方式和连续流间歇曝气的运行方式,通过对总循环周期(tc)、曝气率(fa)以及出水稳定性的分析讨论,得出TN负荷在0.02 kg N/kg MLSS·d下,控制氧化沟曝气时间与总停留时间比在40%左右时,能实现80%以上的除氮率和35%以上的除磷率.与连续曝气氧化沟相比,不仅出水水质更好,而且节省能量.     

氮输入对沼泽湿地碳平衡的影响

以小叶章沼泽化草甸为对象,利用静态箱-气相色谱法,在三江平原进行野外原位试验,研究氮输入对沼泽湿地碳平衡及其各分量的影响.氮素输入后,沼泽湿地生态系统总初级生产力提高,生物量增大,分别比对照处理增加了10%和26.8%.同时,CH₄和生态系统呼吸CO₂排放量提高,而生态系统CO₂净交换(NEE)和净碳(CO₂和CH₄都转化成对应的碳)交换降低,CO₂、CH₄和NEE的季节变化动态未改变.2004年整个生长季氮输入处理的CO₂和CH₄排放量分别比对照处理升高了34%和145%,NEE和净碳交换分别降低了70%和81.6%,但整个生长季2个处理仍然表现为碳的净吸收.氮输入没有改变沼泽湿地碳“汇”的功能,只是减弱了其作为碳“汇”的功能.     

胶州湾沉积物中的磷及其环境指示意义

研究了胶州湾沉积物中磷形态的地球化学分布特征、控制因素及环境意义,将胶州湾沉积物中的磷分为可交换态磷、铝结合态磷、铁结合态磷、闭蓄态磷、自生钙磷、碎屑态磷和有机磷7种不同的形态,并结合210Pb测年法计算了不同年代各形态磷的埋藏通量,在此基础上,分析了胶州湾沉积物中磷所给出的环境信息.结果表明,无机磷是胶州湾沉积物中磷的主要形态,有机磷只占较小的比例,无机磷中钙磷占的比例相对较大,其中碎屑态磷是含量最高.磷的含量及埋藏通量的垂向分布受到pH、盐度、温度、生物扰动、沉积速率等环境因子的影响.相关分析及元素的OC/OP比值分析证明,近20a,陆源输入是胶州湾沉积物主要来源,并且沉积速率不断增大.由于近年来采取的较为得力的治污与排放措施,胶州湾的环境状况已有明显改观.研究还表明,Fe-P,Al-P和Oc-P的含量与海域污染程度有较密切的关系,可作为表征海洋沉积环境污染状况的指示因子之一.     

Simultaneous phosphorus and nitrogen removal in a continuous-flow two-sludge system

The ability of simultaneous biological phosphorus and nitrogen removal was investigated in a lab-scale continuous-flow two-sludge system. Alternating anaerobic and anoxic conditions were combined with contact oxidation stage for treating raw municipal wastewater. Long-term experiments showed that the contradiction of competing for the organic substrate between denitrifying bacteria and PAOs （phosphorus accumulating organisms） in traditional phosphorus and nitrogen removal system has been resolved. The system can adapt to low influent COD/TN ratio （C/N）. Furthermore the SRT （sludge retention time） of nitrifying sludge and denitrifying phosphorus removal sludge can be controlled at optimal conditions respectively. The removal efficiency of COD, TP, TN, and NH4-N was 81.78%, 92.51%, 75.75%, and 84.47% respectively. It was also found that the appropriate influent C/N should be controlled at the range of 3.8-6, while the optimal C/N to the system ranged between 4-5, and the BFR （bypass sludge flow rate） should be controlled at 0.35 around.     

Dynamic phosphorus budget for lake-watershed ecosystems

Lake eutrophication caused by excess phosphorus （P） loading from point sources （PS） and nonpoint sources （NPS） is a persistent and serious ecological problem in China. A phosphorus budget, based on material flow analysis（MFA） and system dynamic （SD）, is proposed and applied for the agriculture-dominated Qionghai Lake watershed located in southwestern China. The MFA-SD approach will not only cover the transporting process of P in the lake-watershed ecosystems, but also can deal with the changes of P budget due to the dynamics of watershed. P inflows include the fertilizer for agricultural croplands, soil losses, domestic sewage discharges, and the atmospheric disposition such as precipitation and dust sinking. Outflows are consisted of hydrologic export, water resources development, fishery and aquatic plants harvesting. The internal P recycling processes are also considered in this paper. From 1988 to 2015, the total P inflows for Lake Qionghai are in a rapid increase from 35.65 to 78.73 t/a, which results in the rising of P concentration in the lake. Among the total P load 2015, agricultural loss and domestic sewage account for 70.60% and 17.27% respectively, directly related to the rapid social-economic development and the swift urbanization. Future management programs designed to reduce P inputs must be put into practices in the coming years to ensure the ecosystem health in the watershed.     

Quantifying The Rainfall-Water Level Fluctuation Process in a Geologically Complex Lake Catchment

Abstact Simulating hydrologic processes in geologically complex environments is a difficult scientific task since it incorporates high level of uncertainty. Many studies have attempted to accurately quantify the rainfall-water level elevation relationship in freshwater bodies so as to predict flooding and drought events. For this purpose several types of models have been implemented including distributed, black box and conceptual models that often provide efficient results, depending on the availability of reliable data as well as on the level of understanding of the system. Nevertheless, in the particular effort, three different models have been used to describe the relationship between rainfall and water level elevation in Trichonis Lake during the period 1951–1997. A Transfer Function model, a Dynamic Linear Regression and a physically based model, consisting of the lake's water budget equation, its Digital Bathymetric Model and GIS algorithms. These models have been tested to assess their efficiency and applicability in a karstic environment and the aim of the study was to find the best modeling option for developing sustainable water management plans and establishing a flooding/drought warning system in the particular lake catchment. The results indicated that in areas with geologically complex conditions, simple, physically-based models operate better than mechanistic models which usually cannot describe adequately the complexity of the system     

Temporal and Spatial Variation of Nutrient Levels in the Nemunas River (Lithuania and Belarus)

There are discordant results on trends in nutrient river water quality from the economical transition countries in Europe. The present study assessed the impact of these economical changes on the load and concentration at 17 monitoring stations along the Nemunas River and its major tributaries (Lithuania and Belarus). Three time periods were evaluated: the Soviet rule command system period 1986–1991, the transfer to market economy period 1992–1996 and the post reform period 1997–2002. The most surprising result in this study, was the increased area-specific load of NO₃-N from the first to the third period at almost all the sampling sites. The increase was particularly large (43–78%) at the sites in the Lithuanian part of the river. The corresponding load increase in the Belarussian part of the river was only 1–15%. The statistical analyses of concentration data confirm the strong upward NO₃-N trend at the Nemunas mouth and at 5 of the 6 tributaries in the lower part of Nemunas. Temporal and spatial analysis of nitrates transport in the Nemunas River and its main tributaries revealed that nitrates mainly originate from agricultural areas. The upward trends were most likely an effect of ploughing of pastures and unbalanced crop fertilisation in combination with large storage and accumulation of soil-nitrogen during the Soviet period.On contrary to nitrate-N, the area-specific load of PO₄-P decreased significantly from the first to the third period at all sites along the Nemunas River (31–86%). Seasonal (SMK) and Partial (PMK) Mann-Kendall tests on PO₄-P concentrations also showed significant downward trend at 14 of 16 investigated sites. The decrease of PO₄-P levels was attributed to the reduction of municipal and industrial point source emissions and to the decreased livestock numbers.The NH₄-N load showed the same pattern as PO₄-P. At the river mouth the load was 90 kg km⁻² yr⁻¹ during the first period compared to only 20–30 kg km⁻² yr⁻¹ in the third period. The trend test on NH₄-N concentrations detected significant downward trends at 5 out of 16 sites. The declines were explained by decreased emissions from cities and large animal breeding farms.This study showed that trend analysis at multiple sites in a river basin is crucial for the understanding of the variability in time and space. Such analysis is also important for our interpretation of underlying sources and fluxes in a drainage basin over time. This is particularly important for compounds that have different source origin.     

废水生物除磷机理的研究——循序间歇式生物脱氮除磷处理系统中微生物的组成

考察了在不同运行阶段,间歇式生物脱氮除磷处理系统内活性污泥混合蔽中细菌总数及主要细菌组成的变化特性。试验结果表明:①在稳定运行期,试验装置内活性污泥混合液中细菌总数大大多于启动期(约大26倍);②在启动运行期,活性污泥混合液中的优势菌为气单胞菌属;其次是假单胞菌属;没有发现不动杆菌属。在稳定运行期间,优势菌是假单胞菌属,其次是气单胞菌属和棒杆菌属。     

乙酸盐对废水生物脱氮除磷影响的研究

考察了乙酸盐（钠）含量对循序间歇式废水生物脱氮除磷工艺的氮、磷去除效果及污泥沉降性能的影响。试验结果表明,废水中乙酸盐（钠）含量对ＰＯ＾３－４－Ｐ,ＰＮ＾－ｘ－Ｎ的明显。随着乙酸盐（钠）浓度的增加,ＰＯ＾３－４－Ｐ及ＮＯ×－Ｎ的去除率相应提高。乙酸盐（钠）的最低起始浓度为１２５ｍｇ／Ｌ,但超过２１５ｍｇ／Ｌ后,便产生污泥膨胀现象。