Quantification of pollution loads from CSOs into surface water bodies by means of online techniques.

Based on novel technologies, a modular online monitoring station suitable for continuous application in sewer networks, wastewater treatment plants and receiving water bodies has been designed. The monitoring station serves as the backbone of a water quality pilot network. As one part of this network a sewer monitoring station has been installed at a combined sewer overflow in Graz to quantify pollution concentrations and loads in the combined sewer and into the receiving water and is operated since October 2002. The design and equipment of the measurement station and first operating experiences and results are given in this paper.     

The influence of biodegradability of sewer solids for the management of CSOs.

The re-suspension of sediments in combined sewers and the associated pollutants into the bulk water during wet weather flows can cause pollutants to be carried further downstream to receiving waters or discharged via Combined Sewer Overflows (CSO). A typical pollutograph shows the trend of released bulk pollutants with time but does not consider information on the biodegradability of these pollutants. A new prediction methodology based on Oxygen Utilisation Rate (respirometric method) and Erosionmeter (laboratory device replicating in-sewer erosion) experiments is proposed which is able to predict the trends in biodegradability during in-sewer sediment erosion in wet weather conditions. The proposed new prediction methodology is also based on COD fractionation techniques.     

Sampling for representative micropollutant loads in sewer systems.

Most commercially available auto-sampling devices do not support a continuous flow-proportional sampling mode, which would conceptually be the best for collecting representative composite samples. Instead different discrete sampling modes are available. Household chemicals can show considerable random short-term variations. With the anticorrosive benzotriazole, relating to a middle-frequent household activity, we show that, besides an accurate flow meter, mainly three factors are decisive for the representativeness of a substance's average load: the substance's load pattern, the sampling frequency and the length of the composite sample. When the sampling intervals are 10 minutes or longer, errors in the order of +/-40% (standard deviation) or more have to be accepted, if the substance of interest is contained in a low number of wastewater pulses (i.e., the level of household activity). This particularly holds true for specific pharmaceuticals e.g. carbamazepine. Ammonium would be less critical, because it relates to a larger number of sources in the same catchment.     

Anoxic control of odour and corrosion from sewer networks.

Anoxic processes can effectively control odour and corrosion in sewer networks. However, the absence of fundamental knowledge on the kinetics of anoxic transformation of sewage prevents the engineering applications of anoxic control in sewers. This paper focuss on a basic understanding of the anoxic transformations needed for a conceptual simulation of the water phase processes. Experiments conducted in batch reactors have shown that nitrite builds up in wastewater during denitrification. Part of the nitrate-reducing biomass is capable of utilizing nitrite after nitrate is depleted. Compared with aerobic transformation, anoxic processes have low values of maximum growth rate of the biomass and also a low endogenous respiration rate. Heterotrophic yield determined under anoxic conditions, at level of 0.25 mmol e-eq (mmol e-eq)(-1), accounted for less than 40% of the corresponding aerobic values.     

Stormflow-dominated loads of faecal pollution from an intensively dairy-farmed catchment

Rainstorms can flush large amounts of faecal pollution from land sources into water bodies, threatening, particularly, contact recreation and bivalve shellfish harvest. We quantified the faecal pollution loads of stormflows in the Toenepi Stream, draining a catchment in intensive dairy-farming (Waikato Region, New Zealand). In this stream, as is typical, E. coli concentration peaks well ahead of flow on storm flow hydrographs, which complicates calculation of loads. However, stormflow E. coli concentration correlates with turbidity in the Toenepi Stream, so we used a continuously-recording turbidimeter to estimate 'continuous' E. coli concentrations and thence E. coli fluxes (cfu/s) and loads (cfu). E. coli was measured on 25 out of the 30 (83%) of storm events occurring in the Toenepi Stream in a 12-month period, using an automatic sampler sampling every 2 hrs over stormflow hydrographs for microbial analysis (within 48 hr). E. coli (cfu) yield on individual events tended to increase systematically with event size. The sum of storm-flow exports (occurring 24% of total time) amounted to 95% of the total annual E. coli export from the Toenepi Catchment. The stream exported about 6% of the (expected) total E. coli production in cattle faeces within the catchment.     

monEAU: a platform for water quality monitoring networks.

Continuous monitoring of water quality creates huge amounts of data and therefore requires new concepts to guarantee high data quality and to prevent data graveyards. Monitoring stations commonly used in practice today suffer from insufficient flexibility and a lack of standardization. That is, although a lot of monitoring tasks are comparable and should lead to robust and powerful platforms, most monitoring stations are case specific developments.In this paper the underlying ideas of a new generation of monitoring networks is described. First a problem analysis of monitoring stations typically seen in current river monitoring practice is outlined, then the monEAU vision on monitoring networks will be discussed together with an overview of a planned system set-up with innovative data evaluation concept.     

Recent findings on sinks for sulfide in gravity sewer networks.

Sulfide buildup in sewer networks is associated with several problems, including health impacts, corrosion of sewer structures and odor nuisance. In recent years, significant advances in the knowledge of the major processes governing sulfide buildup in sewer networks have been made. This paper summarizes this newly obtained knowledge and emphasizes important implications of the findings. Model simulations of the in-sewer processes important for the sulfur cycle showed that sulfide oxidation in the wetted biofilm is typically the most important sink for dissolved sulfide in gravity sewers. However, sulfide emission and thereby potential hydrogen sulfide buildup in the sewer atmosphere is of particular importance in sewers constructed with large diameter pipes, in sewers constructed with steep slopes and in sewers conveying low pH wastewater. Precipitation of metal sulfides is only important when the sulfide concentration in the wastewater is low; i.e. less than 1 g Sm(-3).     

Anoxic sulfide oxidation in wastewater of sewer networks.

Investigations on anoxic sulfide oxidation in wastewater under sewer conditions are presented. Batch tests were designed and conducted to study both chemical and biological sulfide oxidation by nitrate in the water phase. Oxidation at pH 7.0 and 8.5 was performed in parallel and wastewater with anaerobic storage period of 0, 3, 4, 6 days was used. Initial sulfide concentrations at a level of 0-4.1 g S m(-3) were applied by either addition or sulfate reduction. Results showed that wastewater in sewers was capable of biological, but not chemical, sulfide oxidation under anoxic conditions. Elemental sulfur was the end-product during the experiment. Nitrite accumulates in wastewater as an intermediate. The anoxic oxidation rates for fresh wastewater was 0.48 g S m(-3) h(-1) at pH 7.0 and 0.62 g S m(-3) h(-1) at pH 8.5, which accounted for less than 30% of the potential aerobic oxidation rates. A long-term anaerobic adaptation of the wastewater was found to inhibit the oxidation process.     

Hydrogen sulfide emission in sewer networks: a two-phase modeling approach to the sulfur cycle.

Wherever transport of anaerobic wastewater occurs, potential problems associated with hydrogen sulfide in relation to odor nuisance, health risk and corrosion exist. Improved understanding of prediction of hydrogen sulfide emission into the sewer atmosphere is needed for better evaluation of such problems in sewer networks. A two-phase model for emission of hydrogen sulfide along stretches of gravity sewers is presented to estimate the occurrence of both sulfide in the water phase and hydrogen sulfide in the sewer atmosphere. The model takes into account air-water mass transfer of hydrogen sulfide and interactions with other processes in the sulfur cycle. Various emission scenarios are simulated to illustrate the release characteristics of hydrogen sulfide.     

Long term monitoring of sewer sediment accumulation and flushing experiments in a man-entry sewer.

This paper presents continuous field experiments carried out during 4 years in a man-entry egg-shaped combined sewer in Lyon, France in order to contribute to the knowledge and the modelling of sediment accumulation and sediment removal by means of a Hydrass flushing gate. The 250 microm sediments are mainly mineral, and their physical and chemical characteristics appear as rather stable in time and space. Long-term sediment monitoring reveals: (i) a regular asymptotic increase of both the sediment mass and the slope of its longitudinal profile, (ii) a clear correlation between local sediment profile irregularities and sewer ancillaries but without significant influence on the global and long term accumulation. Simple sediment accumulation modelling shows: (i) a good suitability of a three parameters conceptual model to reproduce asymptotic sediment volume accumulation, and (ii) a good suitability of the Velikanov model to reproduce sediment profiles. Both models reproduce observations with an acceptable margin of uncertainty for operational management purposes but are very sensitive to input data and parameter values. The Hydrass flushing gate is efficient and it appeared that the mass of sediments moves downstream linearly with the number of flushes.     

用发光细菌监测水质突发性污染的适用性

介绍了化学物质对发光细茵50%抑光率浓度的负对数log 1/EC50,对鱼的半致死浓度的负对数log 1/LC50及对大型水蚤50%活性抑制浓度的负对数log 1/LC50.分别与化学物质的分子连接性指数1χυ及辛醇、水分配系数的相关关系,以及log 1/EC50分别与鱼类的log 1/LC50、大型水蚤的log1/LC50的相关关系.说明发光细茵适用于监控水质突发性污染.由于用于检测的冰冻干茵或液体干茵培养基的差异,以及悬浮茵液不易均匀一致,会影响检测的灵敏度及精密度.用D=X土3SD计算警戒值较好.在用日常监测的抑光率计算水质污染的警戒值时,要将正值时段与负值时段分开计算D=X±3SD,以确定警戒上限和警戒下限.     

Impact of water source management practices in residential areas on sewer networks - a review

Prolonged drought which has occurred everywhere around the world has caused water shortages, leading many countries to consider more sustainable practices, which are called source management practices (SMPs) to ensure water availability for the future. SMPs include the practices of water use reduction, potable water substitution and wastewater volume reduction such as water demand management, rainwater harvesting, greywater recycling and sewer mining. Besides the well known advantages from SMPs, they also contribute to the alteration of wastewater characteristics which finally affect the process in downstream infrastructure such as sewerage networks. Several studies have shown that the implementation of SMPs decreases the wastewater flow, whilst increasing its strength. High-strength wastewater can cause sewer problems such as sewer blockage, odour and corrosion. Yet, not all SMPs and their impact on existing sewer networks have been investigated. Therefore, this study reviews some examples of four common SMPs, the wastewater characteristics and the physical and biochemical transformation processes in sewers and the problems that might caused by them, and finally the potential impacts of those SMPs on wastewater characteristics and sewer networks are discussed. This paper provides sewer system managers with an overview of potential impacts on the sewer network due to the implementation of some SMPs. Potential research opportunities for the impact of SMPs on existing sewers are also identified.     

Simulation of sulfide buildup in wastewater and atmosphere of sewer networks.

A model concept for prediction of sulfide buildup in sewer networks is presented. The model concept is an extension to--and a further development of--the WATS model (Wastewater Aerobic-anaerobic Transformations in Sewers), which has been developed by Hvitved-Jacobsen and co-workers at Aalborg University. In addition to the sulfur cycle, the WATS model simulates changes in dissolved oxygen and carbon fractions of different biodegradability. The sulfur cycle was introduced via six processes: 1. sulfide production taking place in the biofilm covering the permanently wetted sewer walls; 2. biological sulfide oxidation in the permanently wetted biofilm; 3. chemical and biological sulfide oxidation in the water phase; 4. sulfide precipitation with metals present in the wastewater; 5. emission of hydrogen sulfide to the sewer atmosphere and 6. adsorption and oxidation of hydrogen sulfide on the moist sewer walls where concrete corrosion may take place.     

An inventory analysis of rural pollution loads in China.

Rural pollution has attracted increasing attention over the past decade for its important consequences on surface and groundwater quality. This is particularly so in China due to the wide and effective control of industrial and municipal wastewater discharges over the past decade. Based on the discussion of rural activities in China, this paper develops a new method of inventory analysis through the definition of elementary unit (EU). This inventory analysis approach is then applied to estimate the total rural pollution loads of COD, TN and TP, as well as their spatial distributions in China. Further analysis is also conducted to investigate the correlations between rural pollution loads and agricultural production outputs, as well as population. It is found that China's agriculture is developing largely at the cost of environment quality, and a high population, as well as the increasing demand for agricultural products, is one of the dominant driving forces. The constructed EKC, which describes the relationship between rural pollution loads and agricultural income, also reveals that current agricultural development in China is mostly far from de-locked from the environmental problem.     

GIS-based quantification of future nutrient loads into Lake Peipsi/Chudskoe using qualitative regional development scenarios.

This study aims at the quantification of possible future nutrient loads into Lake Peipsi/Chudskoe under different economic development scenarios. This drainage basin is on the borders of Russia, Estonia and Latvia. The sudden disintegration of the Soviet Union in 1991 caused a collapse of agricultural economy, and consequently, a substantial decrease of diffuse and point-source nutrient emissions. For the future, uncertainties about economic development and the priorities that will be set for this region make it difficult to assess the consequences for river water quality and nutrient loads into the lake. We applied five integrated scenarios of future development of this transboundary region for the next twelve to fifteen years. Each scenario consists of a qualitative story line, which was translated into quantitative changes in the input variables for a geographical information system based nutrient transport model. This model calculates nutrient emissions, as well as transport and retention and the resulting nutrient loads into the lake. The model results show that the effects of the different development scenarios on nutrient loads are relatively limited over a time span of about 15 years. In general, a further reduction of nutrient loads is expected, except for a fast economic development scenario.     

Impact of sewage treatment plants and combined sewer overflow basins on the microbiological quality of surface water.

In a small river catchment, microbiological quality of different sewage treatment plants under regular conditions and in case of heavy rainfall, when combined sewage overflow basins (CSOs) are activated, was examined regarding microbial indicators and pathogens. In the watercourse, no self-cleaning effects could be observed. Small compact treatment plants discharge treated wastewater with a poor microbiological quality compared to river water quality and the quality of treated wastewater of larger plants. During storm water events, concentrations of microorganisms downstream of sewer overflows were approximately two logs higher than during dry weather conditions. Concentrations of parasites decreased slowly during the overflow, in parallel to filterable matter and particle-bound substances. The annual load of microorganisms originating from CSOs significantly exceeds the load from treated effluent of the sewage plants. Thus, an improved hygienic quality of the water course could be achieved by preventing overflows and by enhancing sewage treatment plants.     

河北省地表水资源的质量构成与污染治理

该文依据近期降水偏枯典型年的翔实水量及水质监测资料,给出了河北省地表水资源的质量构成、年内变化过程及分质地表水资源的空间分布,并根据河北省的实际情况,提出了相关治理措施,指明其水资源保护的重点在山区,治理重点在平原。     

加强入河排污口的监督管理为经济发展提供水资源保障

<入河排污口监督管理办法>自2005年1月1日起已开始施行,贯彻落实这个办法是水利部2005年重点推进的工作之一.为此,水利部专门下发了<关于加强入河排污口监督管理工作的通知>(水资源[2005]79号).目前海河流域、长江流域已完成了2004年的入河排污口调查工作,淮河流域每年都进行一次入河排污口调查工作.松辽、黄河、珠江流域都即将布置或正在布置开展入河排污口调查登记工作.     

吉林地区地表水资源污染源调查与分析

收稿日期吉林市位于吉林省的中东部,幅员面积27120km2,是吉林省第二大城市,拥有以石油化工、电力、汽车制造、纺织、电子、医药、食品饮料、建工建材等为骨干行业的工业体系。产业结构和城市建设规模变化较大,水资源的利用状况以及污染物质的排放规律亦有所改变。几年来,吉林地区加大了对水资源的管理力度,在加强对水资源进行监测和研究的同时,积极采用各种法律、经济、科技和宣传等措施和手段,对各类污染源进行了严格有效的监控和治理,使环境质量状况得到了明显的改善和提高,在保护水资源方面起到了重要作用。1地表水资源概况吉林市境内水…     

Attenuation of an ultrasonic beam by suspended particles and range of acoustic flow meters in sewer networks

Ultrasonic flow meters are commonly used in wastewater management. Under certain circumstances, a reduction in the flow meter range may occur and cause significant error in the flow rate measurement. Attenuation due to suspended particles is one of the phenomena capable of reducing the flow meter range. The present paper examines attenuation resulting from re-suspended pond sediment over a wide range of concentration values. It appears that a formula established for sand suspensions provides a good estimate of ultrasound attenuation for these types of particles as well. Experiments conducted for wastewater under particle concentrations commonly encountered in sewer networks demonstrate that the attenuation by particles only contributes to a negligible extent towards intensity decay, in accordance with theoretical predictions. We also theoretically determine herein the operating conditions under which the range of an ultrasonic flow meter would be significantly reduced due to particle attenuation.