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1.
The capabilities of denitrifying Polyphosphate Accumulating Organisms (DPAOs) in two large-scale plants in northern Poland performing enhanced biological phosphorus removal (EBPR) were evaluated in this study. A series of batch tests with the process biomass aimed at the measurements of phosphate release (with artificial substrate and real wastewater) and subsequent phosphate uptake under anoxic/aerobic conditions. The process kinetics were predicted using ASM2d implemented in the GPS-X ver. 4.0.2 simulation package. The results from one experimental series (summer) were used for the model calibration, whereas the results from another series (spring) were used for the model validation. The model parameters were also accurately confirmed by predictions of the accompanying field measurements in the full-scale bioreactors. The experimental and simulation results revealed that a relatively small fraction of PAO could denitrify (eta(NO3,PAO) = 0.32). The denitrification rates associated with the anoxic storage of PP and the anoxic growth of PAO only constituted 16.0-21.0% of the denitrification rates associated with the anoxic activity of "ordinary" heterotrophs. 相似文献
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Desmidt E Ghyselbrecht K Monballiu A Verstraete W Meesschaert BD 《Water science and technology》2012,65(11):1954-1962
The removal of phosphate as magnesium ammonium phosphate (MAP, struvite) has gained a lot of attention. A novel approach using ureolytic MAP crystallization (pH increase by means of bacterial ureases) has been tested on the anaerobic effluent of a potato processing company in a pilot plant and compared with NuReSys(?) technology (pH increase by means of NaOH). The pilot plant showed a high phosphate removal efficiency of 83 ± 7%, resulting in a final effluent concentration of 13 ± 7 mg · L(-1) PO(4)-P. Calculating the evolution of the saturation index (SI) as a function of the remaining concentrations of Mg(2+), PO(4)-P and NH(4)(+) during precipitation in a batch reactor, resulted in a good estimation of the effluent PO(4)-P concentration of the pilot plant, operating under continuous mode. X-ray diffraction (XRD) analyses confirmed the presence of struvite in the small single crystals observed during experiments. The operational cost for the ureolytic MAP crystallization treating high phosphate concentrations (e.g. 100 mg · L(-1) PO(4)-P) was calculated as 3.9 € kg(-1) P(removed). This work shows that the ureolytic MAP crystallization, in combination with an autotrophic nitrogen removal process, is competitive with the NuReSys(?) technology in terms of operational cost and removal efficiency but further research is necessary to obtain larger crystals. 相似文献
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Gertrud K. Nürnberg Bruce D. LaZerte Pei Sun Loh Lewis A. Molot 《Journal of Great Lakes research》2013
Hypoxia and cyanobacteria still occur occasionally in large, mesotrophic Lake Simcoe, and total phosphorus (TP) concentration has remained relatively constant despite external nutrient load reduction. This may indicate a potential internal P source. Internal load as redox-dependent P release from bottom sediments is hard to determine in such a relatively shallow and mostly mixed lake. This study represents the first attempt to quantify internal P loading over many years for the three main sections of Lake Simcoe. Internal load was determined (a) as in situ estimate based on TP increases between July and October and (b) as gross estimate from the product of experimentally determined P release rates and hypoxic extent of sediment surfaces in space and time. Hypoxic extent was quantified (1) as the hypoxic factor determined from dissolved oxygen profiles below the level of 3.5 mg/L, and (2) as active sediment area release factor (AA) modeled from summer euphotic TP concentration, which is especially useful in the mixed sections. Annual internal load for the whole lake was determined as a near constant 62.2 metric tonnes/yr (86 mg/m2/yr) for 1980–2011 using the gross estimates of the AA approach and 88 t/yr before and 53 t/yr after external load abatement and zebra mussel invasion using in situ estimates. Means of in situ and AA-based estimates for 2000–2011 are in close agreement except for polymictic Cook's Bay. These estimates are 45 to 89% of external load, which suggests that internal loading is an important source of P in Lake Simcoe. 相似文献
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根据电力系统的负荷特性或业主的直接要求,提出对水电站群的负荷要求。分析水电站群的来水特性和负荷要求,在尽可能满足负荷要求的前提下确定水电站群的调度目标,并给出相应的凋度方法。这个方法统称为“用判别系数和调度图相结合的方法”。为实现水库调度的初级目标时,调度图中使用的是“保证出力”的概念;而为实现水库调度的高级目标时,调度图中使用的是“基础出力”的概念。 相似文献
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滇池沉积物内源磷释放初步研究 总被引:13,自引:0,他引:13
沉积物内源磷释放是湖泊富营养化重要的污染来源。本次研究在滇池20个采样点进行了原状柱状沉积物样品的采集。分析测试了分层沉积物样品的总磷、总氮、总有机质含量,揭示了滇池全湖沉积物中营养组分的含量特征和分布规律。为估算沉积物磷释放的通量水平和初步解释滇池磷释放的主要作用机制,现场提取出了沉积物间隙水,并分析了间隙水以及采样点湖水中溶解总磷、溶解磷酸盐和溶解有机磷的含量,根据实测运用费克扩散定律计算了沉积物-水界面之间磷的交换通量。同时对代表性样点进行了原样沉积物柱磷释放的实验室模拟。通量计算和模拟实验的结果表明,滇池沉积物具有较强的向水体的释磷能力,全湖沉积物平均磷释放通量为0.095mg/cm^2/a,沉积物磷释放成为全湖磷负荷的重要部分。实验数据相关性分析表明,滇池表层沉积磷活化释放的主要机制是表层沉积物有机质矿化降解,有机磷分解形成的浓度梯度驱动了溶解磷从沉积物向水体扩散。 相似文献
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以磷酸钙盐形式从内循环反应器中回收磷的初步研究 总被引:4,自引:0,他引:4
为探讨连续流内循环反应器以磷酸钙盐形式从污泥厌氧消化液中回收磷的工艺条件,考察了pH、Ca/P摩尔比、曝气强度和水力停留时间等因素对磷回收工艺过程的影响.结果表明,在污泥厌氧消化液总磷浓度86~108 mg/L、正磷浓度66~80 mg/L的条件下,保持反应体系pH9.0~9.5、Ca/P摩尔比2.0、水力停留时间45 min、曝气强度0.014 L/(L·min),内循环反应器磷的回收率接近90%,同时回收产品中磷的含量(以P2O5计)达到22.15%,可以作为磷肥生产原料. 相似文献
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While the mechanism of biological phosphorus removal (BPR) and the need for volatile fatty acids (VFA) have been well researched and documented to the point where it is now possible to design a plant with a very reliable phosphorus removal process using formal flow sheets, BPR is still observed in a number of plants that have no designated anaerobic zone, which was considered essential for phosphorus removal. Some examples are given in this paper. A theory is proposed and then applied to solve problems with a shortage of VFA in the influent of the Henderson NV plant. Mixed liquor was fermented in the anaerobic zone, which resulted in phosphorus removal to very low levels. This paper will discuss some of the background, and some case histories and applications, and present a simple postulation as to the mechanism and efforts at modelling the results. 相似文献
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Case study on the implementation of deammonification for the process water treatment of Munich WWTPs
The two-staged WWTP 'Gut Grosslappen' has a capacity of 2 mio. PE. It comprises a pre-denitrification in the first stage using recirculation from the nitrifying second stage. A residual post-denitrification in a downstream sand filter is required in order to achieve the effluent standards. Presently the process water from sludge digestion is treated separately by nitrification/denitrification. Due to necessary reconstruction of the biological stages, the process water treatment was included in the future overall process concept of the WWTP. A case study was conducted comparing the processes nitritation/denitrititation and deammonification with nitrification/denitrification including their effect on the operational costs of the planned main flow treatment. Besides the different operating costs the investment costs required for the process water treatment played a significant role. Six cases for the process water treatment were compared. As a result, in Munich deammonification can only be recommended for long-term future developments, due to the high investment costs, compared with the nitritation/denitritation alternative realizable in existing tanks. The savings concerning aeration, sludge disposal and chemicals were not sufficient to compensate for the additional investment costs. Due to the specific circumstances in Munich, for the time being the use of existing tanks for nitritation/denitritation proved to be most economical. 相似文献
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Reducing the total discharge from a large WWTP by separate treatment of primary effluent overflow. 总被引:1,自引:0,他引:1
N Hanner A Mattsson C Gruvberger U Nyberg H Aspegren O Fredriksson A Nordqvist B Andersson 《Water science and technology》2004,50(7):157-162
At many large wastewater treatment plants (WWTPs) the increased hydraulic load, caused by combined sewer systems during storm events, results in primary effluent overflow when the capacity of further treatment is exceeded. Due to stringent effluent standards, regulating the total discharge from the WWTPs, the Rya WWTP in G?teborg and the Sj?lunda WWTP in Malm? will have to reduce the impact of primary effluent overflow. Separate, high rate, precipitation processes operated only during high flow conditions have been investigated in pilot units at the two WWTPs. Precipitation in existing primary settlers operated at a surface loading of 3.75 m/h removed phosphorus to 0.35 mg/l. The Actiflo process was also shown to remove suspended solids and phosphorus well. BOD was reduced by 50-60%. With such processes the overall effluent concentrations from the plants can be reduced significantly. Key upgrading features are small footprints, short start up time and high efficiency. 相似文献
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为了高效利用国家基础设施资源,提出了大跨径槽桥合建的结构体系并分析了其荷载效应.对水重、交通活载在主跨100~300m范围内的槽桥合建结构响应进行了分析,并针对预应力混凝土刚构、上承式拱结构、斜拉索结构三种结构体系开展了研究.结果表明:在混凝土刚构槽桥合建中,恒载效应为上部箱梁弯矩控制因素,当主墩相对刚度变化较大时,温... 相似文献
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离心模拟试验是通过离心机的转动创造超重力场,使小比尺模型处于原型应力状态,从而模拟土工构筑物力学特性的一种研究手段。随着工程技术的不断发展和技术难度的逐渐提高,在超重力场中开展模拟实际工况中的特定动作,逐渐成为离心模拟试验中的一个热点问题,而如何在超重力场中实现大荷载力的施加是离心模型试验研究中的一个难点。为解决这一问题,中国水利水电科学研究院基于液压技术,开发了可在超重力场中模拟各种施工动作的试验系统,本文介绍了该系统的工作原理和主要特点,并结合试验案例,证明该系统的实用与可靠性。 相似文献
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基于1960-2020 年蒙江流域日降水资料、蒙江控制站太平站径流和输沙资料分析蒙江流域降水量、径流量和输沙量的演变特征及原因;运用线性趋势回归检验法分析其趋势成分;采用Mann-Whitney-Pettitt 突变点分析法对其进行突变分析;采用Morlet 小波分析法分析其周期成分。结果表明:除夏季降水量、径流量、输沙量和冬季降水量呈不明显的减少趋势外,其余序列呈不明显的增加趋势;年降水量、年径流量和年输沙量呈不明显的增加趋势,没有发生显著突变;年降水量序列存在4 年、7 年、20 年、45 年左右的周期;年径流量序列存在3 年、7 年、19 年、50 年左右的周期;年输沙量序列存在4 年、6 年、11 年、16 年、46 年左右的周期;人类活动是引起蒙江流域年输沙量减少的主导因素。 相似文献
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《Journal of Great Lakes research》2022,48(1):84-96
Extensive efforts are underway to reduce phosphorus (P) export from the Lake Erie watershed. On the Canadian side, the Thames River is the largest tributary source of P to Lake Erie’s western basin. However, the role of dams in retaining and modifying riverine P loading to the lake has not been comprehensively evaluated. We assessed whether Fanshawe Reservoir, the largest dam reservoir on the Thames River, acts as a source or sink of P, using year-round discharge and water chemistry data collected in 2018 and 2019. We also determined how in-reservoir processes alter P speciation by comparing the dissolved reactive P to total P ratio (DRP:TP) in upstream and downstream loads. Annually, Fanshawe Reservoir was a net sink for P, retaining 25% (36 tonnes) and 47% (91 tonnes) of TP in 2018 and 2019, respectively. Seasonally, the reservoir oscillated between a source and sink of P. Net P release occurred during the spring of 2018 and the summers of 2018 and 2019, driven by internal P loading and hypolimnetic discharge from the dam. The reservoir did not exert a strong influence on DRP:TP annually, but ratio increases occurred during both summers, concurrent with water column stratification. Our analysis demonstrates that Fanshawe Reservoir is not only an important P sink on the Thames River, but also modulates the timing and speciation of P loads. We therefore propose that the potential of using existing dam reservoirs to attenuate downstream P loads should be more thoroughly explored alongside source based P mitigation strategies. 相似文献
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The Paraná upper reaches, above the confluence with the Paraguay River, drains a predominantly humid, tropical-subtropical basin that has been extensively altered by anthropogenic activities. Deforestation followed by intense mechanized agriculture has progressively increased in the last decades. Many industrial settlements and hydroelectric impoundments have been developed. Suspended matter, total phosphorus, and inorganic nitrogen exportation rates were estimated at 14 t km?2 y?1, 28kg TP km?2 y?1 and 188kg N km ?2 y?1 respectively. These rates are compartively low when compared to other areas of the world. It was estimated that riverine mass transport represented roughly 6 per cent of the phosphorus and 20 per cent of the nitrogen inputs in the basin. Mass transport of suspended matter and soluble reactive phosphorus are lower and inorganic nitrogen higher than in 1967–1969. Siltation in the man-made lakes reduced both suspended matter and phosphorus transport. Inorganic nitrogen increase is thought to be related to increased fertilizer inputs. 相似文献
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为研究南方道路降雨径流污染负荷,分析对比了重庆市和苏州市4场典型降雨过程中污染物浓度及污染负荷的变化。结果表明:雨型是污染负荷分布的重要影响因素,Ⅱ型降雨的污染负荷变化相对Ⅶ型降雨与径流量(或降雨强度)变化更为相似;污染物浓度与污染负荷的相关性差,径流量(或降雨量强度)与SS/TSS、TP、Pb的污染负荷存在明显相关性。南方城市道路径流污染控制在截留高浓度的初期雨水的同时,也应从污染负荷方面进行总量控制。 相似文献
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