Storm water quality of first flush urban runoff in relation to different traffic characteristics

Storm water quality was monitored at four sites in a middle-sized Swedish town. The objective was to compare storm water pollution in the first flush storm water runoff between sites with different traffic intensities within a town. Flow proportional storm water runoff samples were collected. The samples were analyzed for suspended solids, conductivity, total nitrogen, total phosphorus, oil index, lead, cadmium, copper, chromium, nickel, and zinc.

The results showed that the levels of heavy metals and total phosphorus in storm water were highest at the site with the highest traffic intensity (7000 vehicles/day). A strong linear dependence between suspended solids (SS) and total phosphorus and heavy metals was observed. SS was the dominant explanatory variable for these parameters and a suitable predictor. The observed correlation between SS, heavy metals, and total phosphorus means that reducing levels of suspended solids in storm water would contribute to a substantial decrease of particle-bound heavy metals and total phosphorus in storm water. No samples were taken during winter; however, results indicate that de-icing material used in winter may affect surface runoff quality during other seasons. The results can be used as a reference for storm water quality management for traffic-related sites in towns with similar land use and climatic characteristics.     

Stormwater quality associated with a silt trap (empty and full) discharging into an urban watercourse in Scotland

The aim was to assess the influence of a full silt trap at the end of a stormwater drainage pipe on the water quality of stormwater discharged into a semi‐natural urban watercourse. For approximately eleven weeks, the water qualities of the preliminarily treated stormwater and of the receiving watercourse (Braid Burn) were studied. The mean outflow concentrations of suspended solids were 2.0 mg/l and 34.1 mg/l during dry and wet weather conditions, respectively. Suspended solids concentrations of up to 141.6 mg/l were recorded during storm events. Suspended solids values for treated stormwater were often too high compared to international secondary wastewater treatment standards of around 30 mg/l. Pollutants including heavy metals (e.g., zinc, copper and nickel) accumulated in the silt trap. However, high outflow velocities during heavy rainfall events did not result in clearly defined sediment layers due to sediment re‐suspension. Metals did not accumulate in the receiving watercourse.     

Heavy metal removal from waste water from wet lime(stone)—gypsum flue gas desulfurization plants

Waste water from wet lime(stone) gypsum flue gas desulfurization processes for coal-fired boilers contains suspended solids (gypsum, silica, hydroxides of iron and aluminum) and soluble salts (chlorides and sulfates of calcium, sodium and magnesium). Furthermore, small amounts of heavy metals such as As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se and Zn are present in these waste water streams. A treatment method has been developed to remove these heavy metals very efficiently. This method has been based on coprecipitation of metal hydroxides and sulfides. The hydroxide and sulfide precipitates are removed by a coagulation/flocculation technique followed by gravity settling. The coprecipitation can be carried out with sodium hydroxide or with lime. Both cases were investigated in two different pilot plants with synthetically composed waste water and with actual waste water from three different types of wet lime(stone)—gypsum flue gas desulfurization plants (lime—gypsum FGD plants without a prescrubber, one using seawater and another using river water as process water; a limestone—gypsum FGD plant with a prescrubber using river water as process water).     

动水条件下重金属在沉积物水之间的迁移规律

借助自主开发的不同水动力模拟水槽,选择4.01 cm/s（小流速, A槽）、12.70 cm/s（中流速,B 槽）、20.23 cm/s（大流速,C槽）3种流速条件,研究15 d运行周期内, 3个水槽中沉积物重金属Cd、Cr及类金属As在沉积物间隙水上覆水之间的迁移规律。结果表明：1）流速的增加能促进重金属的释放;2）间隙水中As的浓度远远大于上覆水中浓度,为其向上覆水迁移提供了条件;3）沉积物再悬浮是上覆水中重金属浓度增加的主要原因。同时,与静水条件相比,动水条件对沉积物中重金属的迁移有显著影响,但不同重金属受自身特性的影响显示不同的迁移规律。另一方面,3种水流条件对不同介质中重金属含量变化产生的影响过程和结果也不相同,但其影响程度总体为上覆水>沉积物>间隙水。     

Behaviour of persistent organochlorine micropollutants during primary sedimentation of waste water

The removal of polychlorinated biphenyls and the organochlorine insecticides gamma-HCH, aldrin, dieldrin and endrin during primary sedimentation of raw sewage has been studied using a pilot plant facility. A matrix of sixteen experiments was performed, where the pilot plant was operated at four different hydraulic loadings with four different influent suspended solids loadings. Significant removals of micropollutants into the primary sludge were observed, although no particular relationship with the removal of suspended solids was evident. It is concluded that a proportion of the organic microcontaminants present in raw sewage were associated with non-settleable solids and were also in the dissolved form. The significance of the behaviour of organochlorine micropollutants in waste water treatment processes and the hydrological cycle are discussed in the context of water re-use operations.     

Retrieval of suspended particulate matter concentrations in the Danube River from Landsat ETM data

Alternations in river channel morphology result in a disturbed natural transport of suspended particulate matter (SPM). Suspended particulate matter serves as a transport medium for various pollutants, e.g. heavy metals. It is therefore important to understand how artificial obstructions alter the natural transport of suspended matter. Measurements of SPM in rivers are traditionally carried out during in situ sampling campaigns, which can provide only a limited view of the actual spatial distribution of suspended matter over large distances. Several authors have studied how space-borne remote sensing could be used for mapping of water quality in standing waters, but with only little attention paid to rivers. This paper describes the methodology how a Landsat ETM image was used to map the spatial patterns of SPM in the Slovak portion of the Danube River. Results of our investigation reveal that the Danube River in Slovakia exhibits gradual longitudinal decrease in concentrations of SPM. Based on a strong relationship between the Landsat near-infrared band (TM4) and field measurements, we developed a map of suspended particulate matter in the Danube River with a standard error (SE) of 2.92 mg/L. This study aims to show how archived satellite data and historical water quality data can be used for monitoring of SPM in large rivers. A methodology describing the minimum samples required for sufficiently accurate results is discussed in this paper also.     

Comparison of remote sensing data, model results and in situ data for total suspended matter (TSM) in the southern Frisian lakes

Suspended matter plays an important role in water quality management since it is related to total primary production and fluxes of heavy metals and micropollutants such as PCBs. Synoptic information on suspended matter at a regular frequency is difficult to obtain from the routine in situ monitoring network since suspended matter is (like chlorophyll) a spatially inhomogeneous parameter. This can be solved by the integrated use of remote sensing data, in situ data and water quality models. A methodology previously developed for integrating information from remote sensing, and models (Vos and Schuttelaar, Neth Remote Sensing Board (1995) report 95-19), was applied for the assessment of suspended matter concentrations in the southern Frisian lakes in the Netherlands. The model is a one-dimensional network model. Remote sensing data (Landsat-TM5 and SPOT-HRV) were atmospherically corrected and converted to total suspended matter maps. The algorithms are based on analytical optical modelling, using the in situ inherent optical properties. This methodology enables the development of multi-temporal algorithms for estimating seston dry weight concentration in lakes from remotely sensed data; thus satellite data can now become an independent measurement tool for water management authorities.     

Preliminary Analysis Of Heavy Metals In The Kahrizak Landfill Leachate: A Conceptual Approach

No data have been published on the leachate quality for the Kahrizak landfill site, including heavy metal concentrations. Therefore concentrations of Cu, Zn, Pb, Cd, Ni, Co, Fe and Mn were measured in four fresh and older leachate samples during a 10 months period. Conceptually, heavy metals can be considered to be present in three phases: ( a ) Dissolved; ( b ) adsorbed onto suspended solids; and ( c ) adsorbed onto the suspended solids with particle sizes less than 0.45 w m. A method is proposed in this paper to measure the concentrations of heavy metals in each of the three phases. Other samples were analyzed for phases ( a ) and ( b ). Fresh leachate samples with lower pH values had higher dissolved concentrations of heavy metals than the older leachate samples with higher pH values. Particulate heavy metal concentrations were slightly lower at higher pH values.     

Vulnerability of bank filtration systems to climate change

Bank filtration (BF) is a well established and proven natural water treatment technology, where surface water is infiltrated to an aquifer through river or lake banks. Improvement of water quality is achieved by a series of chemical, biological and physical processes during subsurface passage. This paper aims at identifying climate sensitive factors affecting bank filtration performance and assesses their relevance based on hypothetical ‘drought’ and ‘flood’ climate scenarios. The climate sensitive factors influencing water quantity and quality also have influence on substance removal parameters such as redox conditions and travel time. Droughts are found to promote anaerobic conditions during bank filtration passage, while flood events can drastically shorten travel time and cause breakthrough of pathogens, metals, suspended solids, DOC and organic micropollutants. The study revealed that only BF systems comprising an oxic to anoxic redox sequence ensure maximum removal efficiency. The storage capacity of the banks and availability of two source waters renders BF for drinking water supply less vulnerable than surface water or groundwater abstraction alone. Overall, BF is vulnerable to climate change although anthropogenic impacts are at least as important.     

矿山废水处理技术现状

阐述了矿井废水处理及利用的现状,针对煤矿废水的水质特征,介绍了高悬浮物、高矿化度、酸性废水、含重金属、含微有机物这五类煤矿废水的处理工艺技术,以期为煤矿废水的处理研究提供参考借鉴。     

Comparison of anthropological and “natural” input of substances through waters into Adriatic, Baltic and Black Sea

BOD₅, COD, total suspended solids, total nitrogen, phosphates, surface active substances, detergents, mineral oils, phenols, PAH, Zn, Ni, Cr, Mn, Cu, Pb, Cd and Hg annual loading for the Adriatic Sea, Baltic Sea and Black Sea through wastewater and “natural” waters have been estimated. The quantities of “natural” waters, which are several orders of magnitude higher than the anthropological ones, the expected “natural” loading of substances considered here highly exceeds annually, weak reflections on the natural concentration increase in the whole sea system have been observed. This is essentially due to enormous quantities of suspended matter, and highest pollution is registered in the narrowest littoral zone. The present pollution has ecological implications primarily on the enchanted point-source spots. Comparison of the results for these closed seas reveals that the Adriatic sea has the smallest loading taken absolutely and relatively considering its volume, while the Black Sea, and particularly the Baltic Sea, have significantly higher loading.     

Production and transport of urban wet weather pollution in combined sewer systems: the “Marais” experimental urban catchment in Paris

An experimental catchment area was set up in the centre of Paris (France) so as to follow up the quality of wet weather flows from the entry to the exit of a combined sewer network. The distinctive characteristic of this site is its location in a town centre and the extent of the equipment used to monitor the water pollution over the whole length of its course through the catchment area. The results obtained show a change in quality between the runoff entering the sewer network and the combined storm water flow at the sewer's outlet, which cannot be explained only by the mixture with domestic wastewater. In particular, an increase was observed in the concentrations of suspended solids (SS), VSS, COD, BOD and Cu, in the proportion of pollutants linked to particles and in the characteristics of the particles. A calculation of the total masses going in and out of the sewer network during a rainfall event shows that the erosion of in-sewer pollution stocks is the main source of particles and of organic matter in wet weather flows, whereas heavy metals loads originated from roof runoff, due to the corrosion of metallic roofs. Particles eroded from the sewer sediments during rain events were found to be quite different from the particles of type A deposits and organic biofilms. Nevertheless, they have mean organic and metallic loads that are of the same order of magnitude as the particles of the organic layer at water sediment interface. A change in the chemical form of heavy metals was noticed during the transport in the sewer and it is suspected that a fraction of the dissolved metals from the runoff is adsorbed on sewer sediments.     

Hydrochemical processes controlling arsenic and heavy metal contamination in the Elqui river system (Chile)

Severe arsenic poisoning from drinking water has been documented in Northern Chile. However, the Elqui River, which provides water for approximately 200,000 people in this region, is poorly studied and no data on contaminants have been published to date. In this study, trace elements and the main aqueous constituents were monitored for approximately 2 years in the entire river system. Aqueous species of trace elements were determined via thermodynamic equilibrium calculations, and two operationally-defined suspended fractions were analyzed. Chalco- and arsenopyrite deposits in the upper Andes, in conjunction with mining and geothermal activity, were identified as exclusive point sources of heavy metals and arsenic. The annual input to the river system was approximately (t year(-1)): Fe 600, Mn 110, Cu 130, Zn 35 and As 2.0. The confluence with pH-buffered waters in the upper river system caused collapse of iron hydroxide colloids and coprecipitation of all heavy metals, e.g. dissolved copper concentrations decreased from approximately 100 to approximately 0.2 micromol l(-1), which is still of ecotoxic concern. The heavy metal enriched suspended solids settled only in the lower Elqui River. Arsenate did not adsorb to suspended solids and behaved strictly conservatively, exceeding the WHO guideline value for drinking water (0.13 micromol l(-1)) in the entire river system. Decontamination may be accomplished with reasonable efforts upstream in direct vicinity to the sources via coprecipitation, settling and appropriate pH adjustment for arsenate adsorption.     

The character of the suspended and dissolved phases in the water cover of the flooded mine tailings at Stekenjokk, northern Sweden

Studies of the suspended and dissolved phases of the pond water, material collected from sediment traps, and surficial sediments/tailings from the flooded tailings pond at Stekenjokk have been performed. The aim was to characterise the material, to study the seasonal variations and to quantify possible resuspension of the tailings in the pond. The element concentrations in the pond at Stekenjokk seem to be largely controlled by processes controlling the precipitation and dissolution of Mn- and Fe-oxyhydroxides in both the water column and in the surficial tailings. Physiochemical processes such as weathering of silicates on the surrounding mountain slopes or dykes contributes both dissolved elements and detrital particles. The suspended phase consists of detrital silicate material as well as Fe- and Mn-oxyhydroxides. The average heavy metal concentrations are high, e.g. 0.42% Cu, 0.15% Pb and 3.1% Zn, which is probably due to sorption onto Fe- and Mn-oxyhydroxides. The suspended phase is richer in Fe, and particularly Mn, during the winter. The suspended phase resembles the material collected in sediment traps and the material in the surficial sediments. The pond water is well mixed during the ice-free season. The dissolved heavy metal concentrations are generally rather low with, e.g. maximum concentrations of 2.03 micrograms/l Cu, 0.23 microgram/l Pb and 268 micrograms/l Zn during the winter. Higher dissolved concentrations are found below the ice-cover above the sediment surface during the winter, caused by diffusion of elements from the sediment-water interface up into the pond water. Most of the metals occurring in the pond are dissolved and resuspension of tailings is negligible.     

The fate of selected micropollutants in a single-house MBR

Membrane bioreactor (MBR) technology is an interesting option for single-house wastewater treatment or small communities. Because typically a very high effluent quality is achieved with respect to pathogens, suspended solids, organics and nitrogen, the permeate is well suited for reuse. Little is known about the fate of micropollutants in such small systems. The differences between centralized and decentralized biological wastewater treatment with respect to micropollutants are manifold: besides the operational parameters like hydraulic and sludge retention time, the main difference is in the load variation. While the influent load is expected to be more or less constant in large catchments, it varies strongly in small MBRs due to irregular consumption (e.g. of medication by individuals). Concentrations of micropollutants are higher by a factor 50-1000 than in centralized treatment. It is also unknown how reliable degradation of micropollutants is in case of irregular exposure.In this study, two experiments were conducted in a small MBR treating the wastewater of a three-person household. During normal operation of the treatment plant, 25 pharmaceuticals (antibiotics, antiphlogistics, lipid regulators, iodinated contrast media and hormones) that had not been used by members of the household were added in concentrations typical for municipal wastewater. The removal of most substances was in the same range as for centralized wastewater treatment. It was shown that biological transformation was the main elimination process while adsorption to the activated sludge was negligible for most substances due to the low sludge production at high sludge retention time. No appreciable lag for inducing biological degradation was observed. The high hydraulic and sludge residence time had a positive effect on the elimination of slowly degradable substances, but this was partly compensated by the lower biological activity.An experiment with antibiotics concentrations typical for decentralized treatment (between 500 and 1000 μg l⁻¹; sulfamethoxazole, sulfapyridine, trimethoprim, clarithromycin, roxithromycin) did not show an inhibitory effect on either nitrification or denitrification.     

Method of selective dissolution for characterization of particulate forms of Radium and Barium in natural and waste waters

A new method is proposed for characterization of particulate forms of radium and barium in natural and waste waters. Particulate solids suspended in 1–3 l. of water are first concentrated by membrane filtration or by centrifugation to 20–50 ml of a concentrate which is then filtered through a small-size membrane filter. The solids retained by the filter are successively washed with three selective solvents releasing “loosely bound”, “acid soluble” and “barium sulfate” forms of radium and barium. Compositions and volumes of the selective solvents have been chosen using model experiments and partially checked by analysis of natural samples. Radium and barium “in crystalline detritus” remain on the filter and are determined after an acid digestion of the filter. The principal criteria and selectivity of the method are discussed.     

The behavior of chlorobenzenes in Ise bay, estimated from their concentrations in various environmental media

Field survey of pollutants in various environmental media is indispensable for modeling the behavior of organic compounds discharged into the coastal environment. In this study, the concentrations of chlorobenzenes were measured in Ise Bay where industrial wastewater enters. Some chlorobenzene congeners, 1, 3-dichlorobenzene and 1, 2, 4-trichlorobenzene, were detected in seawater, suspended particulate and bottom sediment samples and their behavior was analyzed.The horizontal distributions showed that these chlorobenzene concentrations in the surface water and sediments were higher in the area near the shore of the industrial area than in the offshore area. The soluble chlorobenzene concentrations in the bottom water were low at all stations. The vertical distribution survey at each sampling site showed that the soluble concentrations were high in the surface water and low in the bottom water, but that those in the suspended particulates and the bottom sediments (dry solid base) had relatively similar concentrations. This indicated that chlorobenzenes in the bottom suspended particulates and in the bottom sediments were not equilibrated with chlorobenzenes in the bottom seawater. This could be explained by the following chlorobenzene behavior: the chlorobenzenes were adsorbed by suspended particulates in the surface water and settled to the bottom swiftly through less polluted seawater in the lower water layer with little desorption. This caused the chlorobenzene concentration gradient in the bottom sediment which reflected the chlorobenzene concentration absorbed by suspended particulates in the surface water.The behavior of chlorobenzenes suggested in this study showed that the use of chemical fate models based on the assumption that the soluble fraction and the fraction adsorbed by suspended particulates are always in equilibrium may yield misleading results.     

Sources, nature, and fate of heavy metal-bearing particles in the sewer system

A preliminary insight into metal cycling within the urban sewer was obtained by determining both the heavy metal concentrations (Cu, Zn, Pb, Cd, Ni, Cr) in sewage and sediments, and the nature of metal-bearing particles using TEM–EDX, SEM–EDX and XRD. Particles collected from tap water, sump-pit deposits, and washbasin siphons, were also examined to trace back the origin of some mineral species. The results show that the total levels in Cu, Pb, Zn, Ni, and Cr in sewage are similar to that reported in the literature, thus suggesting that a time-averaged heavy metal fingerprint of domestic sewage can be defined for most developed cities at the urban catchment scale. Household activities represent the main source of Zn and Pb, the water supply system is a significant source of Cu, and in our case, groundwater infiltration in the sewer system provides a supplementary source of Ni and Cd. Concentrations in heavy metals were much higher in sewer sediments than in sewage suspended solids, the enrichment being due to the preferential settling of metal-bearing particles of high density and/or the precipitation of neoformed mineral phases. TEM and SEM–EDX analyses indicated that suspended solids, biofilms, and sewer sediments contained similar heavy metal-bearing particles including alloys and metal fragments, oxidized metals and sulfides. Copper fragments, metal carbonates (Cu, Zn, Pb), and oxidized soldering materials are released from the erosion of domestic plumbing, whereas the precipitation of sulfides and the sulfurization of metal phases occur primarily within the household connections to the sewer trunk. Close examination of sulfide phases also revealed in most cases a complex growth history recorded in the texture of particles, which likely reflects changes in physicochemical conditions associated with successive resuspension and settling of particles within the sewer system.     

A dynamic model of caesium transport in lakes and their catchments

A mathematical model has been developed to predict radiocaesium concentrations over time within individual compartments of the lake and its catchment. The lake has been divided into five compartments; catchment, lake water (epilimnion and hypolimnion during stratification), lake sediment and fish. Radiocaesium enters the lake via contaminated rainfall and catchment runoff. A proportion of this radiocaesium absorbs onto suspended solids in the lake. This proportion is represented by a distribution coefficient. Sedimentation of the suspended solids occurs at a rate defined by the areal removal coefficient and results in increased caesium concentrations in the sediment. The ingestion of radiocaesium by either water column or benthic feeding fish is described by transfer functions. The model has been tested against data collected from Esthwaite water and Windermere shortly after the Chernobyl reactor accident from May 1986 to December 1987. The model simulates observed radiocaesium concentrations in Esthwaite lake water and sediment and also in lake water, sediment and fish in Windermere. The model could form the basis of a valuable management tool for the water industry should a major airborne pollution event occur again.