ECOLOGICAL RISK-ASSESSMENT METHODOLOGY: A UK CASE STUDY FOR LANDFILLS

The paper presents an ecological risk-assessment methodology which (a) addresses surface-water exposures to aquatic mammals and birds, and (b) accounts for long-term accumulation and biomagnification of pollutants. The methodology has been adapted from those developed in the USA for compliance with US Environmental Protection Agency requirements, and combines predicted or measured surface-water concentration data with information on the natural history of wildlife species and chemical-specific bioaccumulation factors, to determine whether estimated exposures would exceed toxicological criteria. Whilst the methodology is applied to metals in leachate discharges from landfill sites, the general approach is applicable to other industrial sites. The approach could provide the basis for a shift towards more numerical risk-based ecological assessments in a wide variety of contexts.     

Probabilistic environmental risk assessment of urban wet-weather discharges: an approach developed for Switzerland

Technical solutions aimed at limiting the impacts of urban wet-weather discharges are historically based on an end-of-pipe approach. The characteristics of wet-weather discharges, e.g. intermittent pollution loads, high variations in pollutant concentrations, effects in the receiving waters, etc., are generally not considered. This study presents a new probabilistic approach that links the characteristics of wet-weather discharges to their potential impacts in receiving waters. This new approach involves coupling a model for predicting fluctuating concentrations in rivers along with sediment changes to water quality criteria. The new approach produces a risk profile for receiving waters and includes assessment of uncertainty in input data as well as the uncertainty inherent in local receiving system processes. This new approach is expected to offer a better management of wet-weather discharges, resulting in lower environmental impacts.     

Setting Effluent Consent Standards

The paper outlines how consent standards are normally calculated in Scotland for both river systems and tidal waters. A background is given to the reason why a more statistical approach has been adopted in England and Wales where the use of combining distribution methods is more widespread. Comparison of the two approaches is made, particularly with regard to their potential impact on resources required for treatment plants, and also the problems of taking enforcement action. The setting of standards under the EC urban waste water treatment Directive is considered where, in addition to the implications of primary, secondary and more stringent treatment, consideration is given to storm-sewage overflows and industrial discharges.     

Environmental Implications of Treatment of Coastal Sewage Discharges

The environmental implications of implementing the requirement for treatment of coastal sewage prior to discharge, which were put forward in an EC draft Directive on municipal waste-water treatment, are examined. In order to establish the current situation, the results of a national survey of coastal and estuarine sewage discharges are presented. A review of the impact of sewage discharges on the marine environment is presented in conjunction with an assessment of the impact of sewage-treatment processes on the land and in the air. These aspects are integrated into overall conclusions about net environmental impact. Finally, a decision-tree approach to the assignment of priority to additional action required at individual locations is developed.     

Extent of sewage pollution in coastal environment of Mumbai,India: an object‐based image analysis

The coastal water quality of Mumbai is deteriorating by receiving partially treated effluent from wastewater treatment facilities, sewage discharges from ocean outfalls and discharges from point and non‐point sources in the creek and coast. A novel approach of object‐based image analysis has been used in this research study to assess the extent of sewage pollution in the coastal environment of Mumbai. For this, Indian Remote Sensing P6 Linear Imaging Self Scanning IV image was used for multiresolution segmentation and rule‐based image classification as per normalised difference water index and normalised difference turbidity index. Water quality regions as per classification were strongly correlated with observed water quality parameters. Based on classified regions and water quality parameters, extent of sewage pollution in the coast was ranked from high to least polluted. The approach developed in this methodology should be tested in similarly polluted waters to ascertain its adaptability for assessing the spatial extent of sewage pollution.     

The equitable approach to pollution control management in the thames estuary

Wood & Cockburn (IAWPR Conference, Vienna, 1979) outlined the theory of an equitable approach to pollution control. In order to use this approach, the pollution budget for the stretch of river must be defined, and this budget must be distributed equitably among the dischargers. The equitable approach assumes that all dischargers have an equal right to a share of the budget proportional to the potential load which would have been discharged were no treatment given. This paper extends the theory into practice and discusses some of the advantages and problems in the Thames Estuary. The dissolved oxygen pollution budget, based on quality objectives for the Thames, is defined, and is distributed equitably amongst the dischargers. In setting the equitable allowances it is clear that other restraints prevent the fresh water rivers from using their full allowance, and this becomes available for other dischargers, further, it is difficult to properly ascribe allowances for non-point discharges and storm discharges. Because the setting of the pollution budget, and the equitable approach use two different bases, they are not necessarily compatible, and therefore in the Thames a purely equitable approach would result in some failure to meet the objectives. A method for overcoming the problem is set out in the paper. When compatibility between equitability and the quality objectives has been achieved, required discharge standards can be calculated.     

Toxicity Measurements and Their Use in Treatment Strategies

The use of measured toxicity for evaluating the effects of a chemical or effluent on the environment, or monitoring the performance of an effluent treatment plant, is becoming increasingly important to complement the analytical techniques which are conventionally used. Although many consents on effluent discharges refer to specific chemical components, regulatory authorities are increasingly realizing the value of toxicity measurements to evaluate a combined effluent effect, particularly in the case of complex effluent streams.
This paper (a) describes the basic principles of conventional methods of measuring toxicity, (b) highlights the benefits and shortcomings of these methods, and (c) outlines some promising methodologies which are being developed. The use of these measurements is then discussed in evaluating treatment alternatives, modifying existing treatment plants and conducting treatment evaluations. Several case studies are outlined to illustrate the use of toxicological measurements in assessing industrial wastewater treatment processes.     

Rationale for a water pollution code

A water pollution code must quantitatively express the amount and locations of allowable waste discharges. To do this, each of the steps leading to the decision on allowable waste discharge must be defined and quantified.

Six of these steps were discussed in Part I of this analysis. The seventh step, which will be discussed here, concerns the assessment of the costs and benefits associated with different levels of water quality, and the selection of a water quality standard with reference to prevailing community attitudes. The procedure for making this assessment is discussed. The development of a social welfare function using the cost benefit approach and also the relative preferences approach, is described, and the selection of the appropriate water quality standard, using the social welfare function, is discussed.

The final step in deciding allowable waste discharges, which concerns the selection and application of the most acceptable and efficient waste control strategy, will be considered in Part III of this analysis.     

Use of Radial Basis Function Type Artificial Neural Networks for Runoff Simulation

In this paper, the applicability of the radial basis function (RBF) type artificial neural networks (ANNs) approach for modeling a hydrologic system is investigated. The method differs from the more widely used multilayer perceptron (MLP) approach in that the nonlinearity of the model is embedded only in the hidden layer of the network. Search for optimal model parameters is carried out in two steps, each of which can be made to be more efficient and much faster than in MLP. This approach is applied to simulate runoff discharges in a small catchment. The results show that the models based on RBF networks can predict runoff with accuracy comparable with that with the MLP approach. An added advantage of RBF network-based models is that they can be developed with relative ease and with much less time compared with their MLP counterparts.     

Improvement of urban thermal environment by managing heat discharge sources and surface modification in Tokyo

This paper analyzes the implications of anthropogenic heat discharges into the urban thermal environment of Tokyo. Heat discharges by the representative office, commercial and residential buildings were simulated with the help of the DOE-2 building energy simulation model. The approach used in this paper also takes into account the heat storage within building structures. The geographical information system based technique was used to estimate the heat discharge distribution all over Tokyo. The mesoscale analyses of the urban climate were carried out with a model that was based on the Colorado State University Mesoscale Model. The improvements in the urban thermal environment via the various measures were analyzed for two types of scenarios, namely, scenarios related to the management of heat discharge sources and urban surface modifications. The maximum improvement in average temperature for daytime was found to be 0.47°C (at noon) as a result of greening the areas around the buildings of Tokyo. Similarly, the maximum improvement in average temperature for the evening was found to be 0.11°C by discharging all heat to the ground.     

Comparative temporal ecotoxicological study in a river basin influenced by petrochemical industries

An approach was developed to evaluate ecotoxicological effects in river basins impacted by anthropic industrial discharges. Genotoxicity was the first level of evaluation of the river water, but when cytotoxicity was associated with genotoxic effects, our research group added chronic assays allowing the assessment of the ontogenic cycle in environmental diagnosis. The genotoxicity of river water sampled during two periods was compared using the microscreen phage-induction and Salmonella/microsome assays. The study assessed the ability of these assays to diagnose environmental quality in an area where petrochemical impacts occur. The study was performed at six sampling sites using the Salmonella/microsome assay for 10 sampling periods and the microscreen phage-induction assay for 15 samplings. The percentage of mutagenic activity was higher at the sites sampled in front of the petrochemical complex in both periods, but there were more significant mutagenic responses in the first assessment. However, comparing the percentages of samples with mutagenic and cytotoxic activity observed during the two periods it becomes clear that there are more cytotoxic samples during the second period throughout the area studied. The genotoxic activity analyzed by the microscreen phage-induction assay was constant in the second period. Chronic toxicity studies with the microcrustacean Daphnia magna confirm the toxic effects observed. The mortality of individuals was higher at the site most influenced by the petrochemical complex, followed by the station located upstream from this area, while the formation of ephippial eggs was uniform at all stations. The rise in the toxic potential of the region detected by cytotoxic and chronic toxicity may interfere and probably impair the use of the Salmonella/microsome assay to determine the potential of the area, showing the importance of assay association to evaluate potentially contaminated areas.     

Analysis of containment structures for randomly arriving transient loads

Hydrodynamic loads such as those due to safety relief valve discharges and a postulated accidental loss of coolant are some of the major loads on boiling water reactor (RWR) containments. Structural analysis of containments for these highly transient loads can be more efficiently carried out if the response transfer function approach is used. The formulation of such an approach is developed for axisymmetric containment structures. The load parameters, e.g. the maximum intensity, arrival time and predominant frequency may be randomly defined. To obtain the design response, repeated analyses for various sets of parameter values may be required. In such cases the transfer function approach as presented here is computationally very efficient. The formulation to obtain the mean and standard deviation of response for uniformly distributed load arrival time is also provided and the numerical results for a typical BWR containment are given.     

Occurrence of organic wastewater compounds in effluent-dominated streams in Northeastern Kansas

Fifty-nine stream-water samples and 14 municipal wastewater treatment facility (WWTF) discharge samples in Johnson County, northeastern Kansas, were analyzed for 55 compounds collectively described as organic wastewater compounds (OWCs). Stream-water samples were collected upstream, in, and downstream from WWTF discharges in urban and rural areas during base-flow conditions. The effect of secondary treatment processes on OWC occurrence was evaluated by collecting eight samples from WWTF discharges using activated sludge and six from WWTFs samples using trickling filter treatment processes. Samples collected directly from WWTF discharges contained the largest concentrations of most OWCs in this study. Samples from trickling filter discharges had significantly larger concentrations of many OWCs (p-value<0.05) compared to samples collected from activated sludge discharges. OWC concentrations decreased significantly in samples from WWTF discharges compared to stream-water samples collected from sites greater than 2000 m downstream. Upstream from WWTF discharges, base-flow samples collected in streams draining predominantly urban watersheds had significantly larger concentrations of cumulative OWCs (p-value=0.03), caffeine (p-value=0.01), and tris(2-butoxyethyl) phosphate (p-value<0.01) than those collected downstream from more rural watersheds.     

A Survey of Ferruginous Minewater Impacts in the Welsh Coalfields

The aim of this study was to locate all ferruginous discharges within the Welsh coalfield areas and to assess their impact upon receiving watercourses. The project was undertaken in two stages. In the first stage, visual assessments were carried out on an area of river bed affected by iron hydroxide deposition. Chemical samples of the discharges and the receiving watercourse were analysed for a suite of physico-chemical determinands. Ninety discharges were located impacting upon 59.4 km of river, and an area of 22 ha was affected by iron hydroxide deposits.
A ranking method, incorporating the physical/chemical determinands, was developed to assess the comparative impact which discharges were having on receiving watercourses. A total of 33 of the top ranked discharges- (20 to classified watercourses and 13 to unclassified watercourses) having the highest environmental impact were selected; chemical, biological and fisheries impact assessments were then carried out on these discharges in the second stage of the project. The sites were then ranked on the basis of biological and fisheries impact. A list of the highest impacted sites was produced, and some of these were further investigated for remediation options and associated costs.     

Flash flooding in Spain: geomorphological approaches supporting flood frequency analysis, and the implications for the design of structures

Conventional methods for the estimation of flood frequency are generally based on the statistical analysis of data series resulting from the measurement of water levels at specific locations, which are translated into discharges (m³/s) using standard stage/discharge relationships. Subsequently, these gauged flows are used to identify the largest flood event experienced by a river or catchment, and to produce growth curves used in the estimation of the return periods of specific flood events, as well as in the calculation of discharges for specific required design events (e.g. return period 1 in 100 year). In areas where gauging data records are scarce, and/or the data series are short or interrupted, geomorphological interpretation of the physical environment, dating of fluvial deposits and flooding episodes and hydraulic reconstruction of past flood events can be used as complementary tools aiding conventional hydrological and flood frequency analysis methods. This paper will discuss the undertaking of this approach in the Guadalope Catchment in northeast Spain. It will examine the findings in relation to the inadequate design of existing structures such as dams, spillways, canals and reservoirs, and will also look at the potential risks associated with flooding at present.     

A policy framework for trans‐boundary wastewater issues along the Green Line,the Israeli–Palestinian border

The annual discharges of municipal wastewater across the Green Line (the Israeli–Palestinian border) are causing a bi‐national conflict with political, environmental, and economic dimensions. This paper surveys the current scope of wastewater facilities in Palestinian communities and discusses the immense challenges to achieving sustainable wastewater treatment facilities. Current Israeli water policy hinders effective regional solutions to trans‐boundary wastewater issues. This paper proposes a less confrontational approach to solve common problems. The better management of bi‐national wastewater resources could establish sustainable trans‐boundary sanitation facilities. This would bring a range of benefits to health, the environment, and socio‐economic life.     

Biodegradability of organic matter associated with sewer sediments during first flush

The high pollution load in wastewater at the beginning of a rain event is commonly known to originate from the erosion of sewer sediments due to the increased flow rate under storm weather conditions. It is essential to characterize the biodegradability of organic matter during a storm event in order to quantify the effect it can have further downstream to the receiving water via discharges from Combined Sewer Overflow (CSO). The approach is to characterize the pollutograph during first flush. The pollutograph shows the variation in COD and TSS during a first flush event. These parameters measure the quantity of organic matter present. However these parameters do not indicate detailed information on the biodegradability of the organic matter. Such detailed knowledge can be obtained by dividing the total COD into fractions with different microbial properties. To do so oxygen uptake rate (OUR) measurements on batches of wastewater have shown itself to be a versatile technique. Together with a conceptual understanding of the microbial transformation taking place, OUR measurements lead to the desired fractionation of the COD. OUR results indicated that the highest biodegradability is associated with the initial part of a storm event. The information on physical and biological processes in the sewer can be used to better manage sediment in sewers which can otherwise result in depletion of dissolved oxygen in receiving waters via discharges from CSOs.     

The effects of water management on annual maximum floods of Lake Como and River Adda at Lecco (Italy)

This paper presents the results of an analysis aimed to assess the impact exerted on the flood regime of Lake Como and its emissary by different kinds of waterworks in the Adda basin (Italy). This includes construction of reservoirs in the Alps, increase in flow capacity of the exutory and regulation of Lake Como. The assessment of the management effect on peak floods is of particular interest as flood damages could be particularly heavy in densely populated areas along the lake banks and in the river flood plain downstream of the lake. The analysis is carried out by comparing the annual maxima of Lake Como levels and the river Adda discharges at Lecco, at the lake exutory, in different real and hypothetical situations. Both the construction of alpine reservoirs and the improvement of flow capacity of the exutory decrease lake levels and flood discharges, while lake regulation (for irrigation and power production) increases them. The overall effect is a generalised reduction of the flood levels and a slight increase in the discharges with return periods lower than 10 years. The discharges with higher return periods, instead, remain unchanged. The difference between peak and mean daily discharges negligible in all cases disappears altogether for return periods higher than 10 years.     

Screening at Marine Outfall Headworks

The UK approach to pollution control in tidal waters places considerable emphasis on balancing the contrasting needs of utilization of the waters for the assimilation of effluents with the protection of all identified uses, i.e. the Environmental Quality Objective/Environmental Quality Standard (EQO/EQS) approach. In order to protect uses of the waters for bathing and general amenity, this approach in the design of improvement schemes necessary for marine sewage discharges is examined. However, recent guidelines for consent applications dealing with schemes designed to protect bathing use suggest a departure from the EQO/EQS approach towards an emission standard when dealing with the solid phase of the sewage effluent. The implications of these approaches are discussed from the design (scientific and engineering) viewpoints.
A summary of headworks processes and the current practice for preliminary treatment at marine outfall sites in the UK is reviewed, together with comments on their effectiveness. The terms of reference and work of a joint working group to examine the efficiency of screening equipment at marine outfall headworks is described, together with a technical summary of results collected at a range of sites and with various types of equipment. Recommendations for future research are given, and a strategy for screening is developed.