bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance and Operation of Small Activated Sludge Plants in Tourist Areas
Authors: Katsiris N. , Kouzeli-Katsiri A.
Published: May 2018

Small scale activated sludge plants are used extensively in tourist areas for the treatment of wastewaters from hotels and other tourist establishments. A recent survey carried out in a big tourist island of Greece showed that the majority of small plants did not perform satisfactorily. The most important problems identified were associated with diurnal flow fluctuations, inadequate control of air supply and sludge return rates, accumulation of grease and fats in the plant and bad design. Another important problem appeared to be the lack of trained personnel for the operation and maintenance of the plant. These problems are discussed in detail and possible measures are presented. Experimental results from the monitoring of two small extended aeration plants confirmed the bad effect of sudden surges of flow on effluent quality. Moreover it was found that the time required for the startup of the plant was approximately six weeks.
Reclamation of Municipal Wastewater
Authors: El-Gohary Fatma A. , Abo-Elela Sohair I. , El-Kamah H. M.
Published: May 2018

The feasibility of applying direct advanced treatment to municipal wastewater has been investigated. A. two-stage scheme was implemented. The first stage was direct chemical coagulation of primary effluent using different coagulants to remove suspended solids and reduce the carbon to nitrogen ratio to a range suitable for nitrification. The second stage was biological sand-bed to oxidize ammonia to nitrate. The pilot plant was designed to treat 6m3/day. The results obtained showed that chemical coagulation using ferric chloride gave high quality effluent suitable for agricultural purposes. Nitrification of the 2 chemically treated effluent using sand-bed at an overflow rate of 1.358 m3/m2/d completely eliminated ammonia. Almost complete removal of suspended solids was achieved. Residual COD and BOD values were 45 mg/l and 15,5 mg/l, respectively. Fish biotoxicity was completely eliminated after nitrification process.
The Impact of Waste Discharges on Coral Reef Regions
Authors: Bell P. R. F. , Greenfield P. F. , Hawker D. , Connell D.
Published: May 2018

Runoff and sewage discharges from tourist resorts can cause serious adverse impacts on coral reef communities. These impacts result from both the contaminants contained in the discharges and from the freshwater carrier itself. Of the many components of sewage, the nutrients nitrogen and phosphorus appear to cause the most severe adverse impacts. The main effects of nutrients on corals appear to be indirect. The higher nutrient levels result in increased algal growth which can ultimately lead to complete destruction of the delicately balanced coral reef ecosystem. The available evidence implies that denitrification and phosphorus removal are necessary treatment requirements if acceptable levels (after dilution) of these components are to be achieved. The disposal of run-off needs to be considered carefully. Factors such as re-diversion, storage, reuse, treatment for removal of nutrients and disposal via submarine outfall all need to be considered.
Effect of Water Treatment on the Levels of Chlorinated Organics at Different Water Stations in the Vicinity of Alexandria, Egypt
Authors: El-Sebae A. H. , Macklad F. E. , El-Bakary A. S. , El-Gendy K. S. , Ahmed N. S. , Soliman S. A.
Published: May 2018

The effect of water treatment processes on the levels of chlorinated hydrocarbons(α, β, γ-HCH, DDE and P,P'-DDT) and chlorophenols(2,4-D; 2,3-D; 2,3,4-T; 2,4,5-T; 2,3,4,6-Tet. and PCP) collected from Bab-Shark and Abo-Hormos were analysed by GLC. The results showed that water treatment steps did not significantly reduce or remove HCH from the treated water. This was shown by the high HCH content in the treated water when compared with the raw water. However, other compounds, like DDE and P,P'-DET, were undetected after water treatment. The data of chlorophenols content showed that 2,4-D was slightly reduced by water purification, while the other chlorinated phenolic compounds were increased. Generally the levels of chlorinated hydrocarbons and chlorinated phenolic compounds were within the permissible levels in the drinking water, according to WHO guidelines.
Water Management and Recreational Values; Some Cases in Victoria, Australia
Authors: Paterson John
Published: May 2018

The growing recognition of recreational and amenity demands on water systems introduces a multitude of issues, many of them complex, to the established tasks of water quality management and water management generally. Victorian case studies are presented. They (1) illustrate the range and diversity of situations that can arise in managing competition and enhancing compatibility between traditional water supply objectives and recreational demands. (2) Fluctuation of storage levels, essential to storage operations, detract from recreational value. Recreational and tourism demands upon Lake Hume have grown to threaten traditional operating flexibility. (3) Mokoan is another such instance, but with its supply function in a state of flux, Lake Mokoan provides more scope for a shift in the balance. (4) Salinity management has become an issue in the management of lakes and wetlands when water supply interests and environmental/recreation interests respectively have different perspectives on salt disposal. (5) Recreational use of town supply sources has long been a vexed issue, although marked shifts in the attitudues of many supply authorities have occurred in recent years. (6) Eutrophication of lakes and estuaries raises difficult issues of responsibility and scientific uncertainty, and the water management connection may be tenuous but will attract public attention. (7) The water body attributes valued by specialised recreational interests require definition in terms that water managers can deal with using routine techniques of systems analysis and evaluation. (8) The demands of the fish population and anglers introduce a new perspective in river management and perceptions of instream values are changing markedly. (9) Direct costs of recreational services supplied by water authorities are not fully accounted: allocation choices and fiscal incidence will emerge as issues of significance. (10) These case studies raise only a fraction of the total range of matters that will, in the years to come, tax the technology and political skills of governments and management.
Management of Water Quality in the Great Barrier Reef Marine Park
Authors: Woodley Simon
Published: May 2018

The Great Barrier Reef is the largest coral reef system in the world. It is recognised and appreciated worldwide as a unique environment and for this reason has been inscribed on the World Heritage List. The Reef is economically-important to Queensland and Australia, supporting substantial tourism and fishing industries. Management of the Great Barrier Reef to ensure conservation of its natural qualities in perpetuity is achieved through the establishment of the Great Barrier Reef Marine Park.

The maintenance of water quality to protect the reef and the industries which depend on it is becoming an increasingly important management issue requiring better knowledge and possibly new standards of treatment and discharge.
Setting and Achieving Water Quality Criteria for Recreation
Authors: Crockett J. A. , Hartley K. J. , Williams W. D.
Published: May 2018

Water-based recreation is popular in Australia. On the coast many canal estates and marinas are being constructed. Australia's arid and variable climate introduces unusual problems in the establishment of inland recreational lakes. In setting water quality criteria what is achievable must be balanced with what is desirable and criteria may need to be varied between flood and dry periods. Greater emphasis should be placed on understanding, monitoring and managing the ecology of water-bodies. If a stable ecology is maintained, it will generally follow that water quality and conditions surrounding the water-body will be acceptable for human use. In developing new lakes and canals we must carry out some mathematical modelling in order to provide a rational basis for determining water quality criteria and the necessary management actions.
Dispersion of Sewage Wastes in Nearshore Coastal Waters: Applicability of Water Quality Criteria
Authors: Lord D. A. , Grabow W. O. K. , Roberts M. J.
Published: May 2018

Deepwater outfalls can be satisfactorily designed to ensure rapid dilution of sewage wastes, and allow for conventional water quality criteria which prescribe low bacterial levels in areas used for recreational purposes and shellfish harvesting, to be achieved. However, surface shoreline discharges of similar wastes dissipate far less readily, and normally result in shoreline bacterial levels far in excess of desirable criteria. The absolute assessment of water quality in suspect areas should ideally also include viral counts as well as epidemiological information on infections of persons exposed to contaminated seawater or seafood.
Baroon Pocket Dam (Australia) Recreation Strategy: An Approach to a Plan
Authors: Wight W. V.
Published: May 2018

Baroon Pocket Dam is a water supply reservoir being constructed by the Landsborough Maroochy Water Supply Board in the hinterland of the Sunshine Coast of Queensland.

Sinclair Knight and Partners was engaged to assess recreational opportunities and to prepare a management plan giving due regard to:the existing occupation of the catchmentthe picturesque nature of the localitythe current popularity of the locality for tourists and day trip visitors, andthe rare opportunity for “white water” recreation downstream.

Assessment of opportunities and constraints included adaptation of “Outdoor Recreational Opportunity Spectrum” techniques. As the stored water will require extensive treatment in any case, the nature and intensity of recreation was found to be constrained by factors other than water quality. Opinion gathered through public submissions and discussions with user groups was overwhelmingly opposed to motorised activity.

Tranquility and maintenance of the visual setting were valued highly. The retention of land in private ownership in close proximity to the ponded area imposed further constraints on recreation management.
Water Quality, Phosphorus Budgets and Management of Dune Lakes Used for Recreation in Queensland (Australia)
Authors: Arthington A. H. , Miller G. J. , Outridge P. M.
Published: May 2018

The water quality and trophic status of two Queensland dune lakes are compared in the context of assessing the impacts of recreational use and other human activities. Lake Freshwater, Cooloola, has a mean total phosphorus concentration of 12.1 ± 3.3 µg l−1 and is approaching mesotrophic status, whereas Blue Lagoon, Moreton Island, is oligotrophic. Natural loadings of total phosphorus, ranging from 0.2 to 0.35 g m−2 yr−1, are consistent with the progression of Lake Freshwater from oligotrophic to mesotrophic status. The phosphorus loadings predicted by Vollenweider's (1976) one-compartment model, for two values of mean lake depth, also indicate that Lake Freshwater is tending towards eutrophic conditions. The management implications of phosphorus loadings and budgets are discussed.
A Review of Water Quality and Management Problems in Canal Estates in Western Australia
Authors: Atkins R. P.
Published: May 2018

Canal estates are located on the Peel-Harvey Estuarine System, a nutrient enriched waterbody with excessive growths of both macroalgae and phytoplankton. Yunderup Canals have poor water quality exhibiting typical symptoms including frequent phytoplankton blooms, depressed oxygen levels, odour emissions and fish kills.

Water in Waterside Mandurah Canals is marginally poorer than that in the Peel Inlet Channel but within an acceptable range. The difference between developments is related to the proximity of the ocean and therefore tidal action. Canal water quality projections are made and several management options evaluated.
Criteria for Sewage Treatment and Disposal in a Tourist City
Authors: King J. L.
Published: May 2018

This paper sets out the design criteria used by the Gold Coast City Council in the design of its sewage treatment and disposal system. Tourism is the City's major industry and the City's raw sewage is almost completely domestic in its nature. The quantity and quality of the raw sewage are discussed and parameters defined for treatment. Unpolluted beaches and waterways are an essential part of the tourism image and the effluent standards required by the Water Quality Council of Queensland and the method of disposal and effluent standards adopted by Gold Coast City Council are discussed.
Giardia and Virus Monitoring of Sewage Effluent in the State of Arizona
Authors: Rose Joan B. , De Leon Ricardo , Gerba Charles P.
Published: May 2018

Arizona, located in the arid Southwestern United States, is heavily dependent on groundwater. In order to protect this limited resource, wastewater reuse has been implemented. Virus and Giardia monitoring of wastewater used for irrigation has also been initiated as a means for controlling the public's exposure to these pathogens. Treatment facilities must produce wastewater with no detectable Giardia cysts and one virus plaque forming unit (pfu) per 40 liters (L) for unrestricted reuse. For restricted reuse, 125 pfu/40 L is allowed. Methods based on filtration were used to monitor facilities at monthly, quarterly or biannual frequencies. Results after two years of monitoring are presented. All 11 treatment facilities produced water meeting the virus standard of 125 pfu/40 L. Only plants which used sand filtration and disinfection achieved consistent levels of virus below 1 pfu/40 L. Out of 70 samples, 74% contained no detectable viruses. Giardia was detected in 29 to 50% of the samples. Most plants would need to upgrade their treatment in order to meet standards for unrestricted irrigation.
Viral Multicloning Procedure and Replicates Technique
Authors: Vilaginès Ph , Sarrette B. , Vilaginès R.
Published: May 2018

The identification of virus particles is usually a lengthy process requiring extensive technical assistance. Studies of virus migration through agar media used for plaque assays demonstrated that it was possible to repetitively sample virus particles from a plaque with a pin and transfer them by pricking into an agar film pre-overlaid on a cell monolayer. Moreover, when antibodies were incorporated in the pre-overlay, it was possible to serotype the transferred virus with a 24 h response for poliovirus. This simple technique allows very fast sampling and identification of viral populations isolated from environmental sources, opening up a new direction for epidemiological studies. From a practical point of view, an implement was designed for the simultaneous transfer of several plaques in order to obtain replicas.
Influence of Contact Loading on Polysaccharide Storage and Settleability of Activated Sludge
Authors: Yamamoto Ryoko , Matsui Saburo
Published: May 2018

A new concept of substrate loading of activated sludge, “contact loading” is introduced, which means the instantaneous contact ratio of substrate to sludge. Using a substrate made up of glucose and peptone the activated sludges were cultivated under several contact loadings. The influence of contact loading on the capacity of polysaccharide storage and settleability related to the growth of filamentous bacteria was examined. The competition of filamentous and non-filamentous bacteria was analyzed under the different conditions of contact loading and aeration time.
Fixed Biomass Carriers in Activated Sludge Plants
Authors: Rogalla F. , Bacquet G. , Bonhomme M. , Boisseau M.
Published: May 2018

To upgrade existing activated sludge treatment plants, the effect of submerged elements in the aeration basins was verified. In a full scale unit, one complete section of the plant fitted with biofilter packing was operated in parallel with a similar unmodified section as reference. The volume occupied by the fixed beds was varied between 20 and 40 % of the tank. The biofilm evolution and hydraulic behaviour of the packing was followed. No significani change in sludge settleability was observed, but fixed biomass addition reduced sludge production. The submerged elements improve removal efficiency at higher loads. Effluent quality can be maintained even though loadings are increased. Existing treatment plants can thus be adapted to higher loads without additional basin volume. For a constant loading, the basins with biomass carriers improved residual pollution values. Higher purification standards can thus be met without increasing plant capacity.
Crop Production and Sewage Treatment Using Gravel Bed Hydroponic Irrigation
Authors: Butler J. E. , Loveridge R. F. , Bone D. A.
Published: May 2018

A field scale two stage sewage treatment/crop production system was constructed using a series of gently sloping channels each lined with an impermeable membrane and filled with gravel aggregate. The primary stage was planted with a selection of reeds and grasses and fed with settled sewage. The secondary stage was planted with a commercial crop, sugar beet and received sewage from the reed system. During a six month period the performance of the primary system was examined principally by measurement of BOD and suspended solids. The secondary stage was similarly monitored but with the additional measurement of ammonia, phosphate and crop quality.
Rainfall Time Series for Storm Overflow Assessment
Authors: Henderson R. J.
Published: May 2018

With increasing emphasis on the polluting effects of combined sewer overflows the engineer needs to be able to quantify the frequency, rates, volumes and durations of overflow discharge during day to day rainfall conditions. The performance of an existing combined sewer and its associated overflows may now be assessed using a simulation model of the system, together with recently developed rainfall time series representing a typical year of rainfall for a number of UK regions.

This paper reviews potential applications of the series and describes the development and practical use of the series with the WASSP-SIM sewer flow model. A technique is outlined which allows assessment of pollutant loadings to waters receiving storm overflow discharges.
Practical Performance of Various Systems for Small-Scale Waste Water Treatment during a Two-Year Field Test
Authors: van der Graaf Jaap H. J. M. , Fastenau Frits A. , van Bergen Annette H. M.
Published: May 2018

Diffuse pollution, caused by direct discharges from individual houses or groups of houses for which connection to central waste water treatment systems is not feasible, may be significantly reduced by on-site treatment. The performances of 14 different systems for on-site treatment in the range of 5-200 population equivalents (p.e.) in the Netherlands were tested over a two-year period of field research.

Treatment results showed reasonably comparable removal percentages in relation to large systems, the effluent quality however may not be as good due to higher influent concentrations. Significant differences in treatment, operation and maintenance aspects were recorded, causing some systems to be preferred to others. A further evaluation involving costs is currently being carried out.

The feasibility of wide-spread application of small treatment plants may depend more on financial, management and organizational aspects than on technological aspects.
Post Treatment of Anaerobic Effluent Using Sequencing Batch Reactors
Authors: Chin Kean Kee
Published: May 2018

A 150ℓ field unit and two 7.5ℓ laboratory scale sequencing batch reactors (SBRs) were used to polish edible oil refinery wastewater pretreated by attached film anaerobic reactors. SBRs performed well with respect to COD and suspended solids removal. At a loading rate of less than 2 kg COD/m3-d more than 90% COD removal efficiency was achieved. Solids settling was good with SVI generally less than 160. The system showed stability under large variations of organic loading and operating conditions. A significant amount of COD was removed during the long filling and anoxic period.
Wet Air Oxidation of Toxic Industrial Effluents
Authors: Kálmán J. , Izsáki Z. , Kovács L. , Grofcsik A. , Szebényi I.
Published: May 2018

The disposal of process wastewater from a wood carbonization factory was studied in a laboratory batch reactor. Chemical oxygen demand (COD) reduction of 92 - 96% was achieved for samples with initial COD concentrations of more than 100 g/l. The samples subjected to wet air oxidation showed no toxic effects in toxicology tests and were readily biodegradable. Effluent containing cyanide was also subjected to wet air oxidation, and a COD reduction of 75% and cyanide removal of 99.99997% was attained. The reaction rate and activation energy of cyanide hydrolysis were determined.
Behaviour and Modelling of NTA Degradation in Activated Sludge Systems
Authors: Siegrist H. , Alder A. , Gujer W. , Giger W.
Published: May 2018

The general model for single-sludge wastewater treatment systems of the IAWPRC task group (Henze et al., 1987) was extended to describe the biological degradation of NTA and adsorption of NTA onto activated sludge based on literature studies and experiments undertaken at the Glatt wastewater treatment plant (waste water discharge: Q = 55 - 60 000 m3/d, 110 000 inhabitants) for the city of Zurich. During two days, the behaviour and diurnal load variation of nitrilotriacetate (NTA), zinc, lead and copper were analyzed on one lane (volume = 1 812 m3, Q = 14 700 m3/d) of the four parallel lanes used in secondary treatment.

The plant had a sludge age of about 3.6 days and was partly nitrifying (wastewater temperature = 10-11 °C). The average daily load of NTA for the investigated lane was 14 kg NTA/d, corresponding to 0.5 g NTA/person.d. The influent concentration varied between 300 and 1 500 µg NTA/l. NTA was biologically degraded up to 97 %.

Between 12 am and 2 pm of the second day 17 kg NTA (120 % of the daily load of one lane) had been added to the primary effluent. During 4 to 5 hours the biological NTA degradation was saturated and four times more than the daily average of NTA was degraded. Zinc and lead did increase in the secondary effluent during the NTA shock loading.
The Role of Acetate in Denitrification and Biological Phosphate Removal in Modified Bardenpho Systems
Authors: Winter C. T.
Published: May 2018

The importance of easily biodegradable organic substances such as acetate and propionate in biological phosphate removal has been recognised by many researchers. Laboratory-scale studies on the performance of three-stage modified Bardenpho nutrient removal systems, fed with settled sewage supplemented with 0, 50, 100 and 200 mg/l sodium acetate respectively are described. Particular attention is given to the effects of these additions on biological phosphate release and uptake and also to the fate of parameters such as pH, calcium, potassium, ammonia and nitrate. Additional phosphate of 10 mg/l (as P) was initially introduced into the feed in order to burden the experimental systems beyond their normal phosphate removal capacity. This was increased to 20 mg/l and eventually to 40 mg/l of phosphate (as P). Increasing concentrations of sodium acetate resulted in distinct increases in pH values, increase in phosphate release in the anaerobic zones and significantly improved overall phosphate removal in the experimental units. The correlation of phosphate removal on acetate concentration was found to be 0.9886. In some instances the unit receiving 200 mg/l acetate removed up to an average of 30 mg/l of phosphate (as P), constituting an improvement of up to 200% compared with the unit receiving no acetate. The alternating release and uptake of phosphate was accompanied by an equivalent sequence for potassium and magnesium. The high pH value plus the disappearance of phosphate, ammonia and magnesium places doubt on a purely biological phosphate removal but could point at the crystallization of ammonium magnesium phosphate.
Theoretical Principles of Streaming Current Detection
Authors: Dentel S. K. , Kingery K. M.
Published: May 2018

In spite of the increased use of streaming current detectors (SCDs) as a means of monitoring and/or controlling coagulant dosage, knowledge regarding fundamental workings is incomplete. This paper provides an initial attempt at predicting and verifying functioning compared to electrophoretic mobility. The instrument's components -- the sensor and the signal processor -- are first described. Equations modelling electro-double layer behavior in its sensor are then developed. Simplifying assumptions include the use of a capacitance model of the double layer and a triangular velocity profile for fluid within the sensor's annulus. More complex modelling approaches are also suggested which incorporate the Gouy-Chapman electro-double layer model and an exact solution for the velocity profile. Experimental results confirm predictions of the simplified model under conditions of low potential. A monotonic relationship exists between streaming current electrophoretic mobility, which is required for its use as a control parameter. Deviations from model predictions are suggested to be due to charge characteristics of the sensor surfaces themselves.
Application of Pipe Flocculator and Cross-Flow Tilted Plate Settler for Effective Separation of Precipitate from Electroplating Wastewater
Authors: Kurbiel Jerzy , Sapulak Adam , Schade Horst
Published: May 2018

During a research program, the flocculation and settling of suspended solids in electroplating wastewater were tested. The experimental unit comprised a pipe flocculator and a cross-flow tilted plate settler. The experiment showed high efficiency of the system at short flocculation and settling times: τf = 50 s and τc = 11 min., respectively.
Destruction of Iron-Complexed Cyanide by Alkaline Hydrolysis
Authors: Robuck Stephen J. , Luthy Richard G.
Published: May 2018

Iron-complexed cyanide compounds are found in various industrial wastes, and are resistant to destruction by conventional technologies used to treat cyanide-bearing wastes. This study evaluated hydrolytic destruction of iron-complexed cyanide in leachates from land disposal of spent carbonanceous material used to line aluminum reduction cells. The investigation showed that iron-cyanide complexes may be hydrolyzed under alkaline conditions at elevated temperatures and pressures, e.g. in the range of 165-180 °C and 100-150 psig. The hydrolysis reaction is apparently first-order with respect to total cyanide. The reaction yields stoichiometric amounts of ammonia and formate, and Fe3O4(s). The rate of the reaction is especially temperature dependent, and for the case of spent potlining leachate, the hydrolysis rate may be estimated by an Arrhenius kinetic expression for hydrolysis of simple cyanide. The rate of the hydrolysis reaction for iron-complexed cyanide is compared to that for other metal-cyanide complexes. It is shown that waste composition may affect the hydrolysis rate, and that the instability of certain metal-cyanide complexes with respect to alkaline chlorination does not correlate with instability with respect to alkaline hydrolysis. Alkaline hydrolysis is an appropriate technology for destruction of iron- and other metal-cyanide compounds in wastes at high concentrations.
Generalised Model of the Effect of Different Control Measures in Reducing Health Risks from Waste Reuse
Authors: Blumenthal U. J. , Strauss M. , Mara D. D. , Cairncross S.
Published: May 2018

Health risks from wastewater and excreta reuse are assessed using an epidemiological definition of attributable risk instead of the presence of a microbiological hazard. Measures for health protection need not rely on total pathogen removal by waste treatment processes but may include ways to prevent direct human exposure to the wastes. The range of possible options for health protection includes: waste treatment, crop restriction, localised application methods, control of human exposure, and combinations of the different methods. A generalised model is used to show the effectiveness of each option in reducing health risks to agricultural workers and consumers of the crops grown. Three different regimes are available for rendering waste reuse ‘safe' to both workers and consumers, and several regimes are capable of reducing but not eliminating health risks. Case studies are given of the application of the model to wastewater and excreta reuse in agriculture and aquaculture in 6 different countries. The model can be used to aid decisions by planners and engineers to ensure that health protection measures are targetted towards specific exposed groups in the population, within their local context.
A Technique to Determine Unsteady-State Inhibition Kinetics in the Activated Sludge Process
Authors: Watkin Andrew T. , Eckenfelder W. Wesley
Published: May 2018

A technique for rapidly determining Monod and inhibition kinetic parameters in activated sludge is evaluated. The method studied is known as the fed-batch reactor technique and requires approximately three hours to complete. The technique allows for a gradual build-up of substrate in the test reactor by introducing the substrate at a feed rate greater than the maximum substrate utilization rate. Both inhibitory and non-inhibitory substrate responses are modeled using a nonlinear numerical curve-fitting technique. The responses of both glucose and 2,4-dichlorophenol (DCP) are studied using activated sludges with various acclimation histories. Statistically different inhibition constants, KI, for DCP inhibition of glucose utilization were found for the various sludges studied. The curve-fitting algorithm was verified in its ability to accurately retrieve two kinetic parameters from synthetic data generated by superimposing normally distributed random error onto the two parameter numerical solution generated by the algorithm.
Simulation of the Sludge Blanket of a Vertical Clarifier in an Activated Sludge Process
Authors: Laikari H.
Published: May 2018

This study deals with evaluation of peak loading effects from storm and snow-melt waters on the operation of a final settling unit. The load variations have been investigated using a full–scale final settling unit for which a dynamic simulation model has been developed. The model simulates profile changes in the sludge blanket caused by load variations. Furthermore, it can be used for detailed investigations into the effects of flow, solids loading, and sludge recycling on the sludge profile and clarifier capacity by varying the settling velocities within the sludge blanket. With help of the model, the dimensioning and design principles of a vertical clarifier can be further improved. In addition, a new in–situ method for the determination of sludge settling velocity has been developed, which can also take into account the influence of sludge blanket thickness on sludge settling velocity.
Hydraulic Performance and Control of Pollutants Discharged from a Combined Sewer Storage Overflow
Authors: Saul A. J. , Thornton R. C.
Published: May 2018

The development of the Wallingford Procedure WASSP (1981) and the MOSQITO (Moys 1987) models will provide the sewerage engineer with design tools to assess the quantitative and qualitative performance of sewer systems. As part of the development of such a quality model, the University of Manchester, financed by the Water Research centre and North West Water, have undertaken a fieldwork program of research to monitor the hydraulic performance and the temporal variation of pollutants in the inflow and the overflow at five combined sewage overflows in the North West of England. These projects are integrated into the program of research co-ordinated by the River Basin Management group at WRc Engineering.

This paper describes the instrumentation used at a typical field site and illustrates the monitored temporal variation of pollutants for a number of storm events. These results show the complexity of the monitored pollutographs and highlight the large number of variables which influence combined sewer quality. Using data monitored in 1986, it is hypothesised that the long term impact of combined sewer discharges on receiving waters may be estimated from the flow retention performance and some estimate of annual average pollutant concentration. To predict the short term impact on river quality it is necessary to consider the complex processes associated with combined sewer flow and to include the separation performance of the overflow structure.
Hazard Assessment of Wastewater Discharges – A Confluence of Biological and Physical Parameters
Authors: Pols H. B.
Published: May 2018

In order to develop a criteria system for assessing the environmental hazards associated with wastewater discharges, a research project was initiated to investigate the suitability of tests commonly used in the assessment of single substances. Toxicity tests with micro-organisms, algae, waterflea and fish, a mutagenicity test and a RPLC-based method were applied to industrial effluents and sewage treatment plant effluents. The biological tests, including the Ames Salmonella test, showed good applicability/sewage treatment plant effluents being a proper reference. The RPLC-analysis on the contrary needs to be further investigated and optimized. Special attention has to be paid to the interpreting of the results from these laboratory tests in relation to possible adverse effects in the receiving surface waters.
The Application of a Water Quality Index to River Management
Authors: Tyson J. M. , House M. A.
Published: May 2018

River water quality in the United Kingdom is categorised within a five class system developed in 1978 (NWC). This system suffers from problems of subjectivity, reproducibility and sensitivity which limit its value in identifying benefits of management practice. It was expected, in North West Water Authority (NWWA), that use of the Water Quality Index (WQI) developed by House (1986) would meet information requirements for the management of river water quality.

Application of the WQI to data, drawn from a selection of river reaches typifying a range of river qualities, has shown that the Index fulfils many of the requirements of operational managers and adds to the overall information derived.
Process Improvement by Computer-Aided Load Smoothing in Activated Sludge Treatment
Authors: Naghdy G. , Helliwell P.
Published: May 2018

The benefits obtainable from smoothing flow and load to conventional activated sludge treatment units were examined in a large twin-stream pilot plant. Forecasting flow and load using ARIMA* models was found to lead to a reduction in the volume of storage required to permit flow and load smoothing. Process improvement, as mirrored in effluent quality, was achieved even when air feed was reduced by 25% to the smoothed stream.
A Comparison of Several Control Algorithms for Activated Sludge Waste Rate
Authors: Vaccari D. A. , Christodoulatos C.
Published: May 2018

Several algorithms for the control of the waste flow rate of the activated sludge process were compared by computer simulation. The algorithms included: constant waste flow rate; constant proportion of the mass; proportional-integral-derivative (PID) control of the dynamic sludge age (DSA); PID control of mass inventory; and feedforward ratio control based on B.O.D. loading. The study examined the effect of each algorithm on variability in DSA, biomass, and F/M ratio. PID control of DSA minimized variability in sludge age; PID control of biomass minimized variability in biomass; and constant flow rate minimized variability in F/M ratio when mixed liquor was wasted; when return sludge was wasted then constant proportion wasting was significantly better than constant flow wasting in terms of sludge age variability. It is concluded that until the relationship between sludge age, F/M and biomass and effluent quality in an unsteady-state process is better understood, a conservative control strategy is recommended: plants that waste mixed liquor should use constant flow wasting; those that waste return sludge should use constant proportion wasting.
System Design and Full-Scale Plant Study on a Drying-Incineration System for Sewage Sludge
Authors: Sakai S. , Hiraoka M. , Takeda N. , Ohhama I.
Published: May 2018

The system design of a drying-incineration process for sewage sludge is discussed using an energy-balance model of the system. In particular, the profitability of this system is considered from the energy and cost points of view. An energy-balance model including drying, incineration, waste heat recovery, and exhaust gas treatment processes was formulated. This showed that autothermic conditions could be established at a lower dewatered cake calorific value, i.e., 350 to 400 kcal/kg wet solids (WS), in the drying-incineration system, in contrast to the higher dewatered cake calorific value of 700 to 750 kcal/kg WS necessary to produce autothermic conditions in direct incineration systems. The drying-incineration system had reduced energy costs but involved an increase in investment costs due to construction of the dryer. The authors designed a full-scale plant at the East Area Sludge Center in Kobe City, Japan. The capacity of one line in this plant is 200 tons of cake per day. From the results of full-scale operation, fuel oil consumption was 23 l/t cake (at a cake moisture content of 81.2% and a low calorific value of 180 kcal/kg), which is a lower value compared to conventional incineration systems.
Operational Aspects of Doha South Sewage Treatment Works
Authors: Holmes P. G.
Published: May 2018

Extensions to Doha South Sewage Treatment Works provided preliminary, primary, secondary and tertiary treatment for a design population of 100,000 persons, producing disinfected effluent for use in restricted municipal irrigation with digested sludge being conditioned and dewatered by plate pressing. Secondary treatment was designed to be non-nitrifying surface aeration activated sludge, and experience was gained in preventing partial nitrification by strict control of dissolved oxygen residuals. The works operated successfully to ensure a high quality of final effluent despite hydraulic overloading of 1.85 times design DWF and disruptions caused by contracts to further extend the plant. Treatment costs reflected the emphasis placed upon the purchase of imported chemicals and spare parts to ensure continued operation. Operating experience confirmed the suitability of the chosen processes to achieve intended effluent and sludge qualities.
Impact of Further Impoundments on the Oxygen Balance and Water Quality of the Danube in Germany
Authors: Müller D. , Kirchesch V.
Published: May 2018

The construction of two or three impounding dams in the remaining freely flowing reach (73 km) of the Danube is under discussion. The purpose of these impoundments is to guarantee a minimum navigable depth of 3 m needed for modern cargo ships and to produce electric power. The impact of these developments is discussed on the basis of experience with similar impoundments further upstream and of the results from water quality model calculations. The mathematical model used is of the deterministic type, calculating the growth of slowly-growing organisms (nitrifying bacteria, algae and zooplanktons) according to MONOD and MICHAELIS-MENTEN.

Compared with impoundments on other German rivers or the Iron Gate impoundments on the Danube, the effect of the impoundments under discussion on water quality parameters is likely to be fairly small, reflecting the slight changes in morphology which would be necessary for attaining the water depth required. Therefore, the more important effects of these developments would be the changes in the ecologic situation at the river bed and near the banks of the river.
Water Biological Sufficiency and Quality of the Bulgarian Danube Stretch (845–375 River Km)
Authors: Uzunov Y. I. , Russev B. K.
Published: May 2018

The possibility of categorizing water biological sufficiency and quality through criteria for state biotic standards has been evaluated for 7 sections of the Bulgarian Danube stretch. The results of saprobiological analysis show the relatively stable beta-mesosaprobic level of the entire studied stretch, while indices of the structural organization of the benthic invertebrate communities do not correspond to this and rather correspond to the status of zoobenthos in different types of bottom substrata distributed over the length and width of the stretch. We discuss the necessity of further studies for the precise definition of criteria and norms for the assessment of the water biological sufficiency and quality, corresponding to the specific Danube conditions.
Water Quality of the Danube in Hungary and its Major Determining Factors
Authors: Varga P. , Abraham M. , Simor J.
Published: May 2018

Three District Water Authorities cover the whole Hungarian stretch of the Danube. Since the formation of the monitoring network fifteen years ago, the water quality has been observed at fifteen sampling points. Throughout this time, sampling has been performed under different hydrometeorological conditions.

Based on these investigations, it was found that the quality of the river was influenced equally by the local and the hydrometeorological conditions. Major pollution sources are: the sewage from Bratislava, Györ and Budapest; the paper pulp, chemical, and sugar beet factories in the Slovakian catchment; the Hungarian chemical, petro-chemical, and food industries; and non-point source pollution from agriculture. The effects of these sources depend on the degree of wastewater treatment, and on the mixing rate. The waste loads provide a continuous source of nutrients, giving rise to bacterial proliferation. The organic nitrate and phosphorus loads are increasing, which is compensated for by biodegradation.

In the winter, when the water temperature falls below 10°C and solar radiation is low, saprobic conditions characterize the water quality. In the summer, when solar radiation and temperature increase, trophic conditions determine the water quality. Thus, in winter the ammonia content increases, but in the spring, nitrification starts to improve and, especially in the lower reaches, algal overproduction can be detected. This situation changes during flood periods, when the concentration of polluting material is decreased by dilution, and at the same time, the high level of suspended solids inhibits the growth of organisms needing solar radiation. The most unfavourable water quality conditions occur in the winter low-flow period, when problems may occur in drinking water supply if the water is chlorinated.
Downstream Effects of Intermittent Power Generation
Authors: Bretschko G. , Moog O.
Published: May 2018

Intermittent power generation creates frequent and dramatic discharge peaks combined with intervening extremely low water conditions. Whereas no alterations were found in the qualitative composition of zoobenthos, the decrease in abundance and biomass may amount up to 95%. The mismatch between the hydrography of surface water and groundwater might well be a cause of the detrimental effects of frequent and artificially created spates. The drastic reduction of zoobenthic biomass affects not only fish production but minimizes self-purification processes as well. Until tributaries diminish the effects of intermittent power generation, the river is reduced to a mere transport vehicle.
Impacts of River Training on the Quality of Bank-Filtered Waters
Authors: László F. , Homonnay Zs , Zimonyi M.
Published: May 2018

The impacts of river training and gravel dredging on the quality of bank filtered waters are considered along the Danube sections upstream and downstream of Budapest, where important sources of drinking water are situated.

Case studies are presented to show that training structures and dredging operations affect the hydraulic conditions in the river that are conducive to silting in areas with reduced flow velocities. Adverse hydrochemical changes occur in the silted filter layer, especially the dissolution of iron and manganese,and higher concentrations of ammonium-ion are observable. Dredging tends to disrupt the biologically active filter layer, while the ensuing bed degradation causes changes in the inflow ratio, increasing the proportion of polluted groundwater from the background areas in the wells.
Sedimentation in the Reservoir of the Altenwoerth Hydropower Plant
Authors: Nachtnebel H. P. , Summer W. , Mueller H. , Schwaighofer B.
Published: May 2018

This paper addresses two objectives. The first objective is to describe the sedimentation process in the reservoir of the hydropower scheme Altenwoerth. It is located on the Austrian part of the Danube about 60 km upstream from Vienna. Starting in 1976 the aggradation of the river bed has been monitored annually to estimate the sedimentation rate along a longitudinal section in the reservoir. Further, cores were taken over the whole sediment layer to analyse the grain size distribution, the bulk density, the mineralogic structure of the sediment and the heavy metal concentrations in the layer. It was found that the annual average sedimentation of suspended material amounts to 390 000 m3/a. The grain size of the samples vary from well sorted sands to poorly sorted, clay rich sediments. The heavy metal concentrations refer to the fraction less than 20 µ m. In comparison to the guidelines for sewage sludge disposal the observed heavy metal content of zn and Pb is slightly above the respective limits.

The second objective is to demonstrate the application of a one dimensional sedimentation model which describes the accumulation over the operation period from 1976 to 1985. The model is related to the unit stream power concept and is based on the transport capacity equation of Engelund and Hansen. The model yields satisfying results for both the quantity of the sediment and also its gradation.
The Impact of the Chernobyl Accident on the Radioactivity of the River Danube
Authors: Čonkić Lj , Ivó M. , Lulić S. , Košutić K. , Simor J. , Vancsura P. , Slivka J. , Bikit I.
Published: May 2018

Some results of the joint Yugoslav-Hungarian investigations of the radioactivity of the Danube on the border profile in the period 1978 –1988 are presented. From the results of gross β, 90Sr, 3H activity and γ-spectroscopy measurements on the water, fish, sediment and algae samples obtained before and after the Chernobyl accident, the long term impact of that accident on the river ecosystem is determined. By the analysis of the data, it was concluded that the annual mean elimination rate of 106Ru, 137Cs and 134Cs from all media has the value 40% per year. The values of the annual equivalent doses from long-lived man-made nuclides in water and fish are estimated showing an increase by a factor of 5 in the µSv range due to the Chernobyl accident.