Experimental and model-based evaluation of the role of denitrifying polyphosphate accumulating organisms at two large scale WWTPs in northern Poland.

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.     

Evaluation and thermodynamic calculation of ureolytic magnesium ammonium phosphate precipitation from UASB effluent at pilot scale

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.     

Quantification of internal phosphorus load in large,partially polymictic and mesotrophic Lake Simcoe,Ontario

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.     

适应负荷要求的水库调度

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。     

以磷酸钙盐形式从内循环反应器中回收磷的初步研究

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.     

Saving phosphorus removal at the Henderson NV plant

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.     

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.     

南水北调中线需求侧供水负荷管理调度初探

需求侧供水负荷的管理调度(DSM)技术对供水负荷调峰、减少供需差和有效利用水资源方面具有重要意义。结合南水北调中线调度运行初步研究,提出供水负荷的定义,通过供水负荷的调查分析,提出各种负荷的分类原则和标准。在分析南水北调中线调度运行特点的基础上,提出了基于中线相关调度准则下负荷管理的调度模型理论和多目标分层最优化的计算方法。     

Reducing the total discharge from a large WWTP by separate treatment of primary effluent overflow.

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.     

Influence of river regulation on nitrogen and phosphorus mass transport in a large south American river

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.     

药剂投加点对沉淀池出水浊度的影响

根据运河水厂实际生产情况,通过烧杯试验和生产实践研究PAC(聚氯化铝)、PAM(聚丙烯酰胺)投加点对沉淀池出水浊度的影响,结果表明:设置合理的药剂投加点,可以有效地改善絮凝与助凝效果。通过调整PAC和PAM投加点,沉淀池出水浊度比调整前降低了1NTU左右。     

Enhanced removal of chemical oxygen demand, nitrogen and phosphorus using the ameliorative anoxic/anaerobic/oxic process and micro-electrolysis

Synthetic wastewater was treated using a novel system integrating the reversed anoxic/anaerobic/oxic (RAAO) process, a micro-electrolysis (ME) bed and complex biological media. The system showed superior chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal rates. Performance of the system was optimised by considering the influences of three major controlling factors, namely, hydraulic retention time (HRT), organic loading rate (OLR) and mixed liquor recirculation (MLR). TP removal efficiencies were 69, 87, 87 and 83% under the HRTs of 4, 8, 12 and 16 h. In contrast, HRT had negligible effects on the COD and TN removal efficiencies. COD, TN and TP removal efficiencies from synthetic wastewater were 95, 63 and 87%, respectively, at an OLR of 1.9 g/(L·d). The concentrations of COD, TN and TP in the effluent were less than 50, 15 and 1 mg/L, respectively, at the controlled MLR range of 75-100%. In this system, organics, TN and TP were primarily removed from anoxic tank regardless of the operational conditions.     

Impacts of the North Atlantic Oscillation on Scandinavian Hydropower Production and Energy Markets

Dramatic swings in the North Atlantic oscillation (NAO) during the 1990s motivated the authors to build a statistical model of NAO impacts on hydropower production and energy markets in Scandinavia. Variation in the NAO index is shown to explain 55% of the variance of streamflow in Norway and up to 30% of the variance in Norway's hydropower output. It is also possible to identify the influence of NAO anomalies on electricity consumption and prices. Government liberalization allowed a financial market to grow around the international trading of electricity, which in Norway is produced almost entirely from hydropower. The model offers a possible tool for predicting the effects of future NAO movements on hydropower production and energy prices in Scandinavia. The potential influence of skillful climate prediction is discussed.     

大区域经济数据借用在生产经营用水量预测中的应用

第二产业的工业增加值是生产经营用水量预测的主要影响因素。目前,由于行政区变更或者统计口径变化,使部分区域第二产业工业增加值中有合理统计价值的数据难以被获得。鉴于小区域与所属大区域的工业生产的性质、发展趋势往往有较为紧密的正相关关系,生产经营用水的预测可以借用相关性较高的大范围统计数据来得到合理的统计规律。同时,利用张家口市生产经营用水预测验证了该理论的可行性。     

山西省降水资源的成因分析

系统的分析了山西省降水分布规律及影响因素,通过大量资料统计计算,对影响降水的重要因素进行了分析.这些结论对研究山西省降水特性、判断资料的合理性、可靠性,以及不同地区、不同流域的径流情势的分析和降水资料的应用都有一定的参考价值.     

四清水库土坝大滑坡原因分析

文章对郴州市四清水库土坝大滑坡原因做了较为全面的分析,认为滑坡是由于坝体填土质量差、不恰当翻修施工和集中暴雨三方面因素引起的.     

Rain events and their effect on effluent quality studied at a full scale activated sludge treatment plant.

The effect of rain events on effluent quality dynamics was studied at a full scale activated sludge wastewater treatment plant which has a process solution incorporating pre-denitrification in activated sludge with post-nitrification in trickling filters. The incoming wastewater flow varies significantly due to a combined sewer system. Changed flow conditions have an impact on the whole treatment process since the recirculation to the trickling filters is set by the hydraulic limitations of the secondary settlers. Apart from causing different hydraulic conditions in the plant, increased flow due to rain or snow-melting, changes the properties of the incoming wastewater which affects process performance and effluent quality, especially the particle removal efficiency. A comprehensive set of on-line and laboratory data were collected and analysed to assess the impact of rain events on the plant performance.     

以上年度降水量做参变数确定年降水径流关系

对年降水量与径流量关系不密切的中小流域,以上年度降水量做参变数,使其关系得到改善,即可利用年降水资料比较准确地推求年径流量。