bluuebunny/crossref_metadata_2025 huggingface dataset:
Upgrading a Large Municipal Sewage Treatment Plant by a Combination of Biological and Chemical Processes
Authors: Hahn H. H. , Hoffmann E. , Kleinschmidt A. , Klute R.
Published: May 2018

The Standards controlling sewage treatment are continuously in development. Thus, upgrading existing plants is a frequently encountered problem. In the past this meant structural changes, mostly in terms of enlargement of existing facilities or addition of new units. More recently the possibilities of improving plant performance through chemicals addition (inducing precipitation and coagulation) with or without intensified biological treatment have been explored. Chemicals addition has become necessary in many instances due to the tightening of standards for phosphorous concentrations in the plant effluent.

The present discussion is based on a case study where possibilities and limits of chemical and/or biological upgrading have been investigated. The analysis showed that neither chemical stages nor secondary biological stages alone can guarantee the effluent standards formulated by the water authorities.
Nitrification and Denitrification in Combined Activated Sludge Systems
Authors: Wartchow D.
Published: May 2018

Various investigations into batch reactors as well as into continous flow activated sludge plants in laboratory and pilot scale had the aim to determine the difference of the nitrification and denitrification capacity of fixed and suspended biomass in combined systems. By adding porous support material a certain amount of biomass is fixed on this material in a conventional aeration basin of an activated sludge plant. The dimensioning of activated sludge plants for nitrification considers the sludge age of the activated sludge. With fixing the biomass on the support material in the aeration basin, the sludge age can be raised without increasing the MLSS and therefore without increasing the loading of the secondary clarifier.

Measurements of the oxygen consumption of the suspended sludge and the fixed sludge in situ, e.g. without removing the biomass from the support material, as well as the nitrogen balances showed that the nitrification capacity of the fixed biomass is about 20-30 % less than that of the suspended biomass, related to the organic dry matter (MLSS). Also the fixed sludge had a lower organic dry matter than the suspended sludge. This led to the conclusion that there is no linear dependency between increasing the biomass in the aeration basin by adding support material and the nitrification capacity of the whole sludge mass. Regarding the denitrification the measurements showed that a simultaneous denitrification takes place inside the support material although the oxygen concentration in the liquid phase is between 2-4 mg/l.

The denitrification is caused by a lack of oxygen in the deeper regions of the biofilm. This can also be a reason for the observed lower nitrification capacity of the fixed sludge. However, the combination of fixed biomass on porous support material and suspended biomass has the advantage of increasing the total biomass in the system. Furthermore under certain circumstances a simultaneous denitrification takes place in the totally aerated basin. The measurement itself and the findings of the investigations will be presented and discussed in detail in the paper.
Upgrading of Kanpur Wastewater Treatment Plant by Phased Expansion
Authors: Kulshrestha M. , Srivastava A. , Venkobachar C. , Ramaseshan S.
Published: May 2018

Wastewater conveyance and treatment systems are generally designed for a predetermined period. The nature of build-up of flow over the time horizon is generally overlooked, resulting in design entailing unwarranted lock-up of excessive finances. The proposed work envisages phased expansion of treatment facility for wastewater produced by a part of Kanpur city. In one of the phased expansion schemes as discussed here, the energy intensive extended aeration activated sludge (EAAS) is converted at a later time horizon to a capital intensive activated sludge unit (ASU) with a provision for sludge treatment, thus effecting deferred capital investment.
Wastewater Treatment by Soil Absorption Systems
Authors: Ebers T. , Bischofsberger W.
Published: May 2018

In the Federal Republic of Germany, the barely treated wastewater of about 7 million people is percolated into the soil. Groundwater quality has now become a major concern, and investigations into soil filtration as a means of eliminating pollution from household wastewater have been started. Experiments with six laboratory lysimeters (diameter = 0.4 m, height = 1.8 m) are described. Three lysimeters were filled with slightly silty sand, the other three with fine gravel sand. All lysimeters have been in operation for about two years. Initially they were loaded with mechanically treated wastewater from a municipal treatment plant and later with effluent from a septic tank. Hydraulic loading varied from 0.5 to 31 cm/d. Results showed good efficiency for fine gravel sand (aerobic conditions) in removal of BOD5 (98.0 to 99.2 %), COD (88.0 to 92.8 %) and Kjeldahl nitrogen (90.0 to 91.3 %). Elimination of phosphate ranged from 5.7 to 86.0 %. Slightly silty sand (anaerobic conditions) showed the best results in elimination of phosphate (86.0 to 99.3 %) and relatively good elimination rates were achieved for BOD5 (65.0 to 98.2 %) and COD (about 76 %). Elimination of Kjeldahl nitrogen ranged from 39.6 to 68.4 %.

The results for the two soils can be summarized as follows:

Fine gravel sand: high hydraulic loading capacity (aerobic conditions); high elimination rates of BOD5 and COD; high elimination rates of ammonium by nitrification; very low elimination of total phosphate.

Slightly silty sand: low hydraulic loading capacity and, despite this, anaerobic conditions; high elimination rates of BOD5 and barely inferior elimination rates of COD in comparison to fine gravel sand; low elimination rates of ammonium; very high elimination rates of total phosphate.
Evaluation of Pollutant Loads from Urban Nonpoint Sources
Authors: Marsalek J.
Published: May 2018

In preparation of remedial action plans for areas of environmental concern in the Great Lakes Basin, the magnitude of pollutant contributions from point as well as nonpoint sources needs to be assessed. For screening evaluations of urban nonpoint source pollution, a statistically-based method was applied in one of the areas of concern. This method computes the annual pollutant load as a product of the annual runoff and the mean pollutant concentration derived from a lognormal distribution of concentrations. Approximate confidence intervals can be determined for the mean concentration and used to compute confidence intervals of the loads. For the conditions studied, the probabilistic method produced load estimates which were sufficiently accurate for comparisons of pollution sources and formulation of the remedial strategy.
Stormwater Runoff of Hydrocarbons in the Tama River Basin in Tokyo (Japan) and Their Fate in the River
Authors: Yamane A. , Nagashima I. , Okubo T. , Okada M. , Murakami A.
Published: May 2018

Stormwater runoff pollution in urban areas has a significant impact on the aquatic environment. The Nogawa River, which is a tributary of the Tama River in Tokyo, runs through a residential district. At high water levels, more aliphatic hydrocarbons were found in the river water than at normal water levels. It seemed that the hydrocarbons in the water at normal water levels originated from gray water, and those at high water levels were from automobile emissions and/or resuspended bottom sediment. Concentrations of polycyclic aromatic hydrocarbons (PAHs) were negligible in river water at both normal and high water levels whereas they were high in the bottom sediment. It is most probable that the PAHs originated from sources other than automobile emissions.
Urban Storm Water Discharges: Effects upon Communities of Sessile Diatoms and Macro-Invertebrates
Authors: Willemsen G. D. , Gast H. F. , Franken R. O. G. , Cuppen J. G. M.
Published: May 2018

From 1985 to 1987, long-term and more or less permanent effects of discharges from combined or separate sewer systems on communities of sessile diatoms and macro-invertebrates in receiving waters have been studied. Sessile diatoms and/or macro-invertebrates have been investigated on 46 locations, spread all over The Netherlands. The results were related to the type of sewer system, the discharges, and the characteristics of the receiving water, and compared with results from sample(s) taken from a corresponding water not influenced by sewer overflows, the reference water.

In general, communities of sessile diatoms and macro-invertebrates indicate a more severe organic pollution and disturbance of receiving waters compared with reference waters. In the immediate vicinity of the overflows these communities were more disturbed than at some distance. In small ditches, effects were more pronounced compared with large waterbodies and waters with a constant flow regime. Finally, effects of combined sewer overflows were more pronounced than effects of discharges from separate sewer systems, except for locations in industrial areas.
Urban Storm Water Discharges: Effects upon Plankton Communities
Authors: Gast H. F. , Suykerbuyk R. E. M. , Roijackers R. M. M.
Published: May 2018

From 1985 to 1987, effects of sewer discharges on communities of phyto- and Zooplankton in receiving waters have been studied. Locations all over The Netherlands have been selected. The results were related to the type of sewer system, the discharges and the characteristics of the receiving water. Results were compared with those from samples taken from a corresponding water not influenced by sewer discharges, the reference water. Often either phyto- or Zooplankton communities could be used succesfully to describe the short-and medium-term effects of the discharges on the quality of the involved habitats. Plankton communities could also indicate permanent effects due to higher saprobic levels in the receiving water compared to the reference water: an obvious result of urban storm water discharges. In small and medium-sized stagnant waters, particularly in the immediate vicinity of the overflows, effects on plankton communities were more pronounced compared to large and running waters. Combined sewer system overflows (CSO) often proved to affect plankton communities more severely than separate sewer system discharges (SSD), except for some locations in industrial areas.
Fylde Coast Bathing Water Improvements – Storm Water Management for Compliance with Bathing Water Directive
Authors: Head P. C. , Crawshaw D. H. , Rasaratnam S. K.
Published: May 2018

As part of the investigations to determine the most appropriate scheme to bring the Fylde Coast bathing waters up to the quality required by the EC Bathing Water Directive, mathematical models have been used to examine the hydraulic behaviour of the sewerage system and the subsequent dispersion of effluent in the receiving waters. The discharge characteristics of the existing sewerage systems were examined by means of an extensive WASSP model, validated by means of flow measurements gathered from critical points of the sewer network. This model was then used, in conjunction with a time series rainfall record for the area, to investigate the effect of the intensity and duration of rainfall events on the volume of storm sewage to be discharged. Because the area is drained by a combined system, the management of storm water is of utmost importance and the output of the WASSP model was used to determine the input to the coastal dispersion model for rainfall events.

A preliminary examination of the possible sites for sewage treatment works and sea outfalls, for sewage and storm water, suggested four possible schemes involving either inland treatment, marine treatment or a combination of the two. All options required the discharge of storm water to the sea. Extensive dispersion modelling was carried out to examine the probable effects of various storm-water management strategies on bacterial concentrations in the receiving waters. From this it was apparent that storage of storm flows, with controlled discharge, at the state of tide when environmental impact would be minimal, was required to achieve compliance with the provisions of the Directive. By integrating the WASSP modelling of various base-flow and storm-water storage options with dispersion modelling, it was possible to establish appropriate design criteria.
Sewer Sediment and its Relation with the Quality Characteristics of Combined Sewer Flows
Authors: Verbanck M.
Published: May 2018

Combined sewer lines in the centre of Brussels are laid at very slack gradients, resulting during dry-weather in a systematic deficit of the load of particulate material at the outlet. The first results of a data collection programme are documented, with regard to the influence of in-sewer deposits upon pollution emissions. The monitoring of suspended solids load in the Main Trunk showed the extent of sediment deposition/resuspension processes in the system. Over a long period of time, the accumulation of deposits on sewer inverts is clearly noticeable. The total volume of deposition in the network also appears to be much more influenced by rainfall events than by human sewer-cleaning practices. Particle size analyses of sewer sediment samples have shown that most deposits in running sewers are composed of sandy material, which reduces the hydraulic capacity, but is suspected to have only slight adverse pollutional impact. Samples with finer material and higher organic contents were however found in some protected locations, not submitted to continuous dry-weather flow. From the experience gained in this study, it is strongly believed that the acquisition of detailed field data is essential in order to assess correctly the complex phenomena involved.
Policy, Law and Implementation of Industrial Wastewater Pollution Control
Authors: Tyagi Paritosh C.
Published: May 2018

The paper is based on the experience in India, The policy of industrial wastewater pollution control is summarised. It is essentially based on the polluter pays principle. The corner-stones of the policy for setting standards are environmental protection, harmony with development needs, public participation and implementability. Prevention is accepted as better than cure. Industries are classified with regard to their potential for pollution. The history of legislative measures for control of water pollution is briefly described and the effectiveness of legislation has been critically examined. The organisational structure of the statutory boards at the Centre and States is described and steps taken for assessment and control of pollution caused by industrial wastewater have been enumerated.
Improved Industrial Water Pollution Control in Botswana – From Strategy to Practical Implementation
Authors: Makela Timo
Published: May 2018

Botswana is at the moment industrializing and developing rapidly due to favorable economical conditions. Unfortunately, this development has also some negative impacts. Pollution hazards are increasing and more systematic and sound approach to pollution control is needed. Recently the new strategy for water pollution control was developed. Several areas of development were identified. Actions plans are based on rather practical and pragmatic approach with parallel activities in several areas so that delays in some areas will not hamper achievements in other areas. The areas of development are policy formulation, legislation, practical principles for handling pollution cases, inspection and monitoring activities, systematic guidelines, filing and reporting systems and cooperation with polluters and between different authorities. The paper presents chosen approach and some practical work already done to develop water pollution control work in the Department of Water Affairs.
Integrated Water Resources Planning as a Factor in Environmental Pollution Control
Authors: Ngirane-Katashaya Gaddi G.
Published: May 2018

Integrated water resources planning (IWRP) seeks to rationalize water resources projects in a region for optimum utilization of water, appropriate conservation, cost-effectiveness, and attainment of maximum economic and socio-environmental benefits.

This paper examines those aspects of water resources planning which interact with the environment. It also presents corresponding environmental conservation parameters and various approaches to pollution controls. Mutually pertinent points identify the planning parameters. Case studies of IWRP are presented.
Surface Water Quality Monitoring and Pollution Control in Ghana
Authors: Larmie S. A. , Osafo Rose A. , Ayibotele Nii Boi
Published: May 2018

Developing nations like Ghana, cannot afford to adopt a “wait to see” policy with their water environment. We must develop and/or strengthen infrastructure needed to maintain a healthy environment. In our eagerness to industrialize, care must be taken not to repeat mistakes of industrialized nations. Water quality monitoring activities should be streamlined and properly coordinated to develop good pollution control measures. We must research into and provide pollution control alternatives suitable for our particular environment.
Coffee Industry Wastes
Authors: Gathuo B. , Rantala P. , Määttä R.
Published: May 2018

Over 120 000 tons coffee is processed per year in Kenya. More than 1200 coffee factories produce a pollution loading equivalent to a staggering population equivalent of over 240 000 000. The coffee industry is therefore the most important industrial polluter in rural Kenya. Pulp, husks and wastewaters are produced. Husks can be directly used as fuel. Wet pulp could be composted and then used as a soil conditioner. Wastewaters have a high BOD5 sometimes even exceeding 9000 mg/l. In India and Central American countries, anaerobic lagoons are mainly used for the treatment of these wastewaters. In Keftya water re-use combined with land disposal with zero discharge has been recommended. However, in all these methods, the desired environmental soundness is rarely achieved. Anaerobic digestion with biogas production is potentially attractive. Fuel generated could be used for drying coffee. About 10 000 GJ of energy is required to dry 1 ton of coffee. The potential yield of biogas from one ton of pulp can be estimated as 131 m3. This is equivalent to 100 litres of petrol in fuel value.
Anaerobic Sludge Digestion in Industrial Wastewater Treatment
Authors: Puhakka Jaakko A.
Published: May 2018

A research strategy for evaluation of anaerobic digestion method for industrial sludge treatment is presented. The experimental approach is described as a case study. This case study with pulp mill waste activated sludge involved the following steps: preliminary tests to determine the biodegradability of sludge samples, process optimization in laboratory-scale reactors, and the evaluation of design criteria in a pilot-scale study. The investment and operation costs of full-scale application are discussed.
High-Rate Anaerobic Treatment of Industrial Wastewaters
Authors: Rintala J.
Published: May 2018

Anaerobic mesophilic treatment of synthetic (a mixture of acetate and methanol) and thermomechanical pulping (TMP) wastewater was studied in laboratory-scale upflow anaerobic sludge blanket (UASB) reactors and filters with emphasis on the process start-up. The reactors were inoculated with nongranular sludge. The start-up of mesophilic and thermophilic processes inoculated with mesophilic granular sludge was investigated in UASB reactors fed with diluted vinasse. The start-up proceeded faster in the filters than in the UASB reactors with TMP and synthetic wastewater. Loading rates of over 15 kgCODm−3d−1 with 50-60 % COD removal efficiencies were achieved in 10 days in the mesophilic and in 50 days in the thermophilic UASB reactor treating vinasse. The results show that high-rate anaerobic treatment can be applied to different types of industrial wastewaters under varying conditions.
A Low-Cost and High-Efficiency Solution for Sugar Factory Waste Water Treatment
Authors: von der Emde W. , Kroiss H.
Published: May 2018

The main goals for the design of waste water treatment plants are high efficiency, high operational reliability and minimal costs. The challenge to have very low investment costs especially exists for industrial plants which are only in operation for several months every year as e.g. in the beet sugar industry in Central Europe. A case study of an Austrian sugar factory treatment plant shows that using very simple and low-cost structures does not affect the efficiency of the treatment. This factory is also one of the rare cases where biologically treated effluent is recirculated to reduce fresh water consumption. Special emphasis is put on the start-up process, the influence of shock loadings in the influent, and design and operation of the plant.
Appropriate Industrial Waste Management Technologies: The New Zealand Meat Industry
Authors: Rao Bhamidimarri S. M.
Published: May 2018

The concepts of effluent irrigation and aerobic composting of organic solid wastes are not new, but the meat industry in New Zealand has developed these concepts further in recent years for effective treatment and recovery of resource in meat processing wastes. Significant advances have been made in developing design, operation, monitoring and control of these low-cost simple technologies, which are well suited for the treatment and utilization of meat industry wastes in New Zealand. The feasibility of utilizing these high-strength organic wastes for organic farming has been demonstrated.
Technical and Economic Analysis of Stabilization Ponds
Authors: Nie Meisheng , Xu Shuimin , Aulenbach Donald B.
Published: May 2018

Compared with other methods of wastewater treatment, stabilization ponds provide the advantages of low capital cost, low operation and maintenance (O&M) costs and simple manipulations at the expense of a large land area. This study analysed the technical and economic aspects of stabilization ponds in order to determine their recommendation for use in specific location.

Since few stabilization ponds in China were self-designed, and few integrated cost data were available, cost data were determined by a set of series designs. Stabilization ponds are contrasted with activated sludge (AS) system, since AS is a more frequently used method for municipal wastewater treatment. The cost data for AS system were obtained by surveying AS facilities built in China.

The aspects used in this model analysis included (1) capital cost, (2) O&M costs, and (3) occupied land cost. For comparing the total costs of stabilization pond and AS, a new concept, critical land price (Pro), was introduced. Pro is the price of land at which the total cost of a stabilization pond is equal to that of an equivalent AS system. When land price is above the Pro, AS is more economic than a stabilization pond. When land price is below the Pro, a stabilization pond is more economic. In addition to comparing the total costs of AS and stabilization ponds, a comparison was made between stabilization pond in South China and in North China.

The capital cost of a stabilization pond is 1/3 to 1/2 that of an equivalent AS plant, the O&M costs are 1/5 to 1/4 the AS costs, and the occupied land area is 15 to 40 times the AS land area. The Pro decreases with increasing wastewater flow. Using the model analysis, the critical land price in South China (Pros) is in the range of 10,000 to 30,000 RMB/Mo. (Mo. is an area unit used in China, it is equal to 1/15 hectares.) In North China, the critical land price (Pron) is 6,000 to 16,000 RMB/Mo.

Comparing stabilization ponds in the south with those in the north showed that the capital cost, 0&M costs, and occupied land cost in the north are 1.5 to 1.8 times, 1.5 times, and 1.6 to 1.7 times those in the south, respectively.
The Purifying Efficiency and Mechanism of Aquatic Plants in Ponds
Authors: Shi Shuangxi , Wang Xichun
Published: May 2018

In this paper we report preliminary research on the purifying efficiency of 5 species of aquatic plant on hospital wastewater, as well as the interrelation between purifying efficiency and physiological activity of the plants. The relationship between the accumulation of certain mineral elements within the plant body and the relative concentration in the water was also studied. Study of enzymatic activity indicated that increasing peroxidase activity in the plant body lead to the promoting of phytophysiological metabolic activity, and as a result the removal rate of pollutants from water was accelerated. Both the activity of enzymes and the accumulation of certain mineral elements inside the plant body were found to have linear correlation with the removal of pollutants from the water.
The Performance of a Heat Exchanger Type Anaerobic Biofilm Reactor
Authors: Escalera C. R. , Uchida S.
Published: May 2018

The performance of a heat exchanger-type anaerobic biofilm reactor(HEABR) was theoretically and experimentally studied. The treatment of a relatively low-strength artificial wastewater was experimentally feasible for a range of wall temperatures varying from 25° C to 37° C, inlet temperatures varying from 5° C to 15° C and loading rates varying from 0.2g-C/l.day to 0.8 g-C/l.day. Removal efficiencies in the range of 70–98% were obtained. It was found that the performance of the reactor is strongly dependent on the wall temperatures and the hydraulic retention times and that the inlet temperature effect is smaller. A reactor model was developed which considers that a consecutive reaction occurs both in the biofilm and the bulk liquid where the bacteria exist. The effects of temperature on the reaction and diffusion rates of the primary substrate and the intermediate product are also considered. A good fit between the experimental and calculated results showed the validity of the model.
Low-Cost and Low-Energy Wastewater Treatment Systems: A South African Perspective
Authors: Batchelor A. , Bocarro R. , Pybus P. J.
Published: May 2018

An overview of waste-water treatment alternatives in South Africa is presented. A comparison of the capital, operating and maintenance costs of biological filters, bio-discs, stabilisation ponds and an extended-aeration-actiyated sludge system suggest that stabilization ponds may be regarded as a low cost, low energy waste-water treatment system. However, in some instances, due to legal and land requirements they are not appropriate. In these instances a number of interacting factors play a role in determining the lowest cost option. The capital construction and operating costs of constructed wetlands are similar to those of stabilisation ponds but due to lack of full scale operational information they are not yet widely used as a waste-water treatment system.
Optimizing Water Quality Modeling in an Uncertain Environment
Authors: Warwick J. J.
Published: May 2018

Optimization of the overall modeling exercise must incorporate consideration of both model aggregation error (level of complexity) and input parameter uncertainty. Focusing on one issue, to the exclusion of the other, will not generally be optimal. Two distinct stream dissolved oxygen model formulations, each representing a different level of simulation complexity, are compared. A non-parametric statistic, the total likelihood (Ltotal) of successfully verifying a calibrated model, is chosen as the point of comparison. For normal levels of input parameter uncertainty and a minimum required dissolved oxygen accuracy of ±0.25 mg/L, the simpler single parameter model (Ltotal = 24.3%) had superior performance characteristics in comparison to the complex dual parameter model (Ltotal = 15.0%). In general, the performance (L total) of the complex model improved more rapidly than the simple model following reduction of input parameter variability.
Application of Systems Analysis in Water Pollution Control: Perspectives for Central and Eastern Europe
Authors: Somlyódy László
Published: May 2018

Recent major political changes in Central and Eastern Europe opened new avenues for environmental and water quality management. In the past there was practically no need for the application of systems analysis or any policy-related sciences. As an exceptional case the eutrophication control of Lake Balaton (Hungary) is discussed. The counterpart example is the Gabcikovo-Nagymaros barrage complex (Danube): here a systematic assessment is missing even today. The type of the analysis which would be required is illustrated by two examples: eutrophication of the upstream reservoir of the complex and oxygen household of pne of the side arms of the Danube. Future applications of systems analysis depend primarily on desired institutional changes and environmental legislation, as due to past economic development paths large number of problems exist in Central and Eastern Europe. These are discussed primarily for Hungary. Skill and scientific knowledge exist but experiences in application are lacking. Environmental education should be modernized. A specialized technology transfer is needed also towards changes of institutional structures and legislation, and also the training of managers. The most important task under the existing economic pressure is the preparation of well tailored, cost-effective water pollution control strategies for countries in question. This requires in itself a systems analytical approach.
Modeling and Animation of Wastewater Disposal in the Ocean Environment
Authors: Bale A. E. , Orlob G. T.
Published: May 2018

DisPatch, a graphically oriented interactive computer program, has been designed to model the far-field transport of wastewater discharge in the ocean environment Implemented on a microcomputer, DisPatch features high-resolution graphics, menus, and dialog boxes to facilitate user input of boundary conditions in such a way as to be accessible to a large audience of potential users. The DisPatch model is developed from the application of the advection-dispersion equation to a horizontally homogeneous, vertically averaged, turbulent velocity field representing the ocean environment in which a “patch” of discharged wastewater is presumed to travel. Designed to accept either average values or a stochastically generated set of values for initial dilution and trapping height, DisPatch displays the path of each discharge event onscreen as an animation of calculated patch position and dimension. Results are presented in the form of an elevation view of contaminant impact at a user-defined impact zone.
Operations and Control in Wastewater Treatment - Some Swedish Experiences
Authors: Olsson Gustaf
Published: May 2018

New demands on nutrient removal in Swedish wastewater treatment plants have motivated new research and development activities. In this paper some ideas behind a new Swedish government research program are described, and an outline of current research activities and programs is made. Operational problems are emphasized, and their interdisciplinary character is recognized. Consequently a research team has been formed in Lund with active participation from applied microbiology, process technology, control engineering and working environment technology, in cooperation with the sewage works in Malmö
Stochastic Control of the Activated Sludge Process
Authors: Kabouris John C. , Georgakakos Aris P.
Published: May 2018

A stochastic optimal control method is introduced and applied to the real-time management of an activated sludge process. The method includes a detailed dynamic process model and accounts for input uncertainty. The objective is to minimize the expected variations of effluent organic concentrations and is met by manipulating process flowrates. The method is applied to a hypothetical case study.
DBAPE – A Database and Model Parameter Analysis System for Agricultural Soils to Support Water Quality Management
Authors: Imhoff J. C. , Carsel R. F. , Kittle J. L. , Hummel P. R.
Published: May 2018

The Data Base Analyzer and Parameter Estimator (DBAPE) is a practical tool for (1) analyzing a national environmental data base containing geographic and soils properties data and locations for meteorologic stations, and (2) estimating parameters for subsurface flow models. DBAPE merges four teclnologies (data base management, a user interface, process algorithms, graphics) in a hardware-portable environment to provide a broad range of capabilities for search and analysis of agricultural soils to support water quality management.
Assessment of Eutrophication Control Programs Using an Ecological Model for a Dimictic Lake
Authors: Hosomi M. , Okada M. , Sudo R.
Published: May 2018

An ecological model of Lake Yunoko, a dimictic lake, was developed to assess various programs for eutrophication control. A multi-component dynamic model for nutrients in the bottom sediment-water system was incorporated into the model, a one-dimensional water temperature-water quality-ecological model. Good agreement between the model calculations and observed nutrients, chlorophyll-a, and dissolved oxygen concentrations in the water and nutrient concentrations in the bottom sediment was noted. The agreement between the model calculations and the measured nutrient flux from bottom sediment during the summer stagnation period was good. The effectiveness of sediment dredging, artificial circulation, and reduction of external phosphorus loading as eutrophication control programs on chlorophyll-a, PO4−P, and dissolved oxygen concentration in the water was assessed using a calibrated model.
Performance and Design of a Selector for Bulking Control
Authors: Patoczka Jerzy , Wesley Eckenfelder W.
Published: May 2018

Experimental data from continuous-flow activated-sludge reactors with selectors fed with highly biodegradable, soluble feed were correlated using a simple, semi-empirical formula. Rate of the substrate removal in the selector was demonstrated to be a function of the organic loading in the initial mixing chamber. The formula allows prediction of the substrate concentration in the selector and was used for the optimization of the selector's design for bulking control. Analysis of the equation demonstrated that an optimum sludge recycle rate exists for a set of systems parameters. The optimum recycle rate is always less than 100 percent and approaches this value as the system constant decreases. The substrate concentration in the contactor at the optimum sludge recycle rate is equal to one-half of the influent concentration.
On the Problem of “Two-Phase” Activated Sludge
Authors: Szetela R. W.
Published: May 2018

Steady-state models are presented to describe the wastewater treatment process in two activated sludge systems. One of these makes use of a single complete-mix reactor; the other one involves two complete-mix reactors arranged in series. The in-series system is equivalent to what is known as the “two-phase” activated sludge, a concept which is now being launched throughout Poland in conjunction with the PROMLECZ technology under implementation. Analysis of the mathematical models has revealed the following: (1) treatment efficiency, excess sludge production, energy consumption, and the degree of sludge stabilization are identical in the two systems; (2) there exists a technological equivalence of “two-phase” sludge with “single-phase” sludge; (3) the “two-phase” system has no technological advantage over the “single-phase” system.
Choice of Optimal Configurations for Two-Phase Biological Reactors on the Basis of Hydraulic Model Studies of a Wastewater Treatment Plant in Gdańsk
Authors: Maciejewski M.
Published: May 2018

The paper presents procedure, results and conclusions drawn from laboratory studies of nitrification and denitrification chambers of two-phase biological reactors with recirculation system, for a designed wastewater treatment plant of 270 000 m3/day capacity, for the city of Gdańsk.

On the 1:17 physical model, observations of stream lines and measurements of the velocity field in some characteristic regions have been performed.

The measurements have been carried out for 14 different configurations of the reactor operation, depending on the aerator turbines, mammoth rotors and prototypical mixers with horizontal axle and with guide-ring.

Based on these studies, and having introduced some structural innovations aimed at improving flow uniformity around aerators and rotors, a variant optimal from the point-of-view of hydraulic properties and energy consumption has been proposed for realization.

Moreover, using results of some other investigations performed on a structure in technical scale, conclusions concerning the following questions have been presented:

I/ the importance of uniform velocity distribution in the reactor for final effeot of operation of the wastewater treatment plant,

II/ relationships between velocity, discharge and hydraulic efficiency of the wastewater treatment plant chambers,

III/ the influence of geometry of chambers and of recirculation on the efficiency of the purification process.

The paper includes drawings, figures and short descriptions of the following experimental techniques used in the investigations: the method of varying temperature field, the colorimetric method, the conductometric method and the method using a current micrometer. A video film on the study is available.
Factors Affecting Biological Nitrogen Removal Efficiency in a Large Wastewater Treatment Plant
Authors: Plaza Elzbieta , Bosander Jan , Trela Jozef
Published: May 2018

The pre-denitrification method, with internal carbon source for biological nitrogen removal, has been studied in full-scale experiments at a large wastewater treatment plant (flow 130,000 m3/d). Factors controlling nitrogen removal, such as fraction of anoxic zone and organic material content in wastewater are discussed. A flexible system with fine bubble membrane disc diffusers made it possible to change the ratio between the volumes for nitrification and denitrification. The denitrification process was limited by lack of organic carbon in the wastewater and increasing the fraction of anoxic zone did not improve the efficiency of the system. With the help of on-line analysers for total nitrogen and chemical oxygen demand, the relationship between the denitrification efficiency and the carbon/nitrogen ratio has been given careful study. The average value for chemical oxygen demand after primary sedimentation was only 130 mg/l and the value for the COD/N ratio was found to be 6.3. The denitrification rate was usually in the range of 1.0 and 2.0 mg NO3-N/g MLVSS h.
Intensive Primary Treatment of Urban Wastewater
Authors: Coma J. , Jabbouri A. , Grasmick A. , Elmaleh S.
Published: May 2018

The intensification of primary treatment is basically obtained by destabilization through a fluidized bed which flocculates the suspension with or even without any flocculant. The abatement on suspended solids reaches 60 % in the latter case, and rises up to 90% when ferric chloride is injected. The required residence-time in the whole unit is only 15 minutes, settling included. The sludge has a better settling ability than sludge from classical devices which could reduce the cost of the sludge treatment itself.
On the Manifold Role of Lime Coagulation
Authors: Świderska-Bróż M.
Published: May 2018

Lime coagulation and 2-hour sedimentation were investigated for their utility in removing humic acids, colour, permanganate COD, and some heavy metals (Cu, Pb, Zn, Ni). Calcium carbonate was found to be responsible for the removal of the majority of the pollutants examined.

Magnesium hydroxide accounted for the further improvement in the removal efficiencies of colour, permanganate COD, humic acids and nickel. This was not so in the case of zinc, lead and copper. Their removal efficiencies decreased when pH reached values higher than 10.5 (which create favourable conditions for the precipitation of magnesium hydroxide). The contribution of magnesium hydroxide to the removal of organice was more pronounced in low-alkalinity solutions with poor precipitation of caloium carbonate.

Lime coagulation produces metal complexes of low solubility, thus providing advantageous conditions for metal-organic co-precipitation (copper and lead were removed together with humic acids).

The results obtained quantified the following finding: lime coagulation which is used in water renovation primarily for the removal of phosphates has an important contribution to the removal of other pollutants (some of them creating health hazards to the population).
Fluidized Bed Reactors for Anaerobic Wastewater Treatment
Authors: Iza J.
Published: May 2018

A review of the theoretical basis for the design and operation of fluidized bed reactors for anaerobic treatment of wastewaters is presented. After the description of the characteristics of three-phase fluidized bed and theoretical aspects which could affect the operation of an anaerobic reactor, the design considerations and recommendations based upon characteristics of the wastewater to be treated are presented. A step by step design strategy, including media selection, operative conditions of the reactor, equipment sizing and long-term run effects, as well as mechanical design hints on distribution system, reactor body, piping of recycle lines and gas collection are included.
Wastewater Treatment and Reuse Aspects of Lake Valencia, Venezuela
Authors: Lansdell Mark , Carbonell Luis M.
Published: May 2018

The environmental problems of the Lake Valencia Basin are described. A multipurpose project for the treatment and reuse of 9.5 m3/s of wastewater, which has received approval for international funding, is discussed along with technological adaptations to local opportunities and limitations.

The results of bench-scale studies for potable reuse of the Lake's water by softening and blending are also described along with experience of surrogate parameters for Trihalomethane Formation Potential Measurement in a Developing world context.
Wastewater Reclamation and Reuse at the Sugarbeet Factory ACOR-1 (Valladolid, Spain)
Authors: Kuzminski C. , Palencia J. I. , Fernández-Polanco F. , García P. A. , Iza J.
Published: May 2018

Traditionally the sugarbeet industry has been a heavy consumer of water and a big producer of organic pollution. This paper presents and discusses the plant modifications at the ACOR-1 sugarbeet processing factory at Valladolid, Spain. These changes were carried out to achieve an integrated water management. The segregation of streams, the installation of a biological anaerobic treatment plant and cooling towers and the recirculation of effluents allowed a reduction of water consumption from 330 L/s in 1984 down to 35 L/s in 1990, the pollution discharged to the environment being reduced by more than 90%.
Regulation of Effluents and Implications for Environmental Policy
Authors: Johnston P. A. , MacGarvin M. , Stringer R. L.
Published: May 2018

Adequate regulation of industrial effluent is integral to any strategy to reduce contaminants entering the North Sea. The present approach involves a list of identified priority pollutants. Current regulatory frameworks are based upon environmental quality objectives or fixed emission limits, underpinned by the concept of assimilative capacity. These are examined and illustrated using examples from the UK River Tees and Antwerp Harbour in Belgium. Neither system is able to address the problem of complex effluents, and therefore cannot provide comprehensive environmental protection. These failings are discussed in relation to the role of clean production techniques and it is concluded that zero discharge must be recognised as the ultimate goal of North Sea environmental protection strategy.
An Integral Approach to Support Managerial Actions on Micropollutants in the Southern North Sea
Authors: Roos A. , van Vliet J. F. M. , van Pagee J. A. , Nauta T. A. , de Vries M. B.
Published: May 2018

During the last decades the southern part of the North Sea has been exposed to high inputs of micropollutants from various sources.

Within the framework of the project Management Analysis North Sea (MANS), studies have been carried out to quantify the impact of anthropogenic pollution inputs on coastal water quality, sediments and biota.

In order to study the effects of different managerial actions an integrated modelling framework has been developed to enable a spatial evaluation. In this regard special attention has been given to:–the reduction of river inputs, as a result: of domestic and industrial waste water treatment–the storage of dredging sludge from the Rhine-Meuse estuary.

It is shown by the results of this study that input reductions of heavy metals since 1980 have resulted in a significant reduction of concentrations in Dutch coastal waters. Long-term simulation of accumulation of pollutants in the sediment, however, showed that due to the long time scale the reduction of the seabed can take several decades. Similar conclusions can be drawn for organic micropollutants, although the input reductions seem to be less pronounced.

Based on bioaccumulation modelling, the pollution of the sediment proved to be an important source for uptake of micropollutants in the food web. This study also made clear that significant reductions of North Sea pollution can be established if combined actions are taken. Reduction of pollutants from the Rhine-Meuse estuary, together with the storage of polluted dredging sludge from the Rotterdam harbours, will result in a significant reduction of the state of pollution of the coastal waters of the Netherlands.
North Sea Task Force Biological Effects Monitoring Programme
Authors: Stagg R. M.
Published: May 2018

This paper describes the biological effects monitoring programme proposed by the North Sea Task Force (NSTF). The rationale for each of the recommended methods will be outlined and the advantages and limitations, within the framework of the objectives of the monitoring programme, will be discussed.
A Comparison of the Ecological Risks from Fisheries and Pollution to the North Sea Biota
Authors: Turkstra E. , Scholten M. C. Th. , Bowmer C. T. , Schobben H. P. M.
Published: May 2018

A prototype of the ecological risk analysis framework REFEREE is used to demonstrate a comparative evaluation of the effects of three main perturbing factors on the functioning of the North Sea ecosystem. Fisheries obviously have a large impact on fish species: some are reduced, others are increased in density. Fisheries also contribute substantially to the decline of mammals, although pollution is the main causative factor in their demise and that of birds. Oddly, some fish species appear to benefit from contamination. Eutrophication causes an increase in crustaceans, polychaetes, coelenterates and meiofauna, and a decrease in echinoderms and molluscs. Sole is one of the few fish species that appears to benefit from eutrophication, the others are suppressed.