bluuebunny/crossref_metadata_2025_split huggingface dataset:
Upgrading of rotating biological contactor (RBC) systems to achieve higher effluent quality, including biological nutrient enrichment and reduction techniques
Authors: Neu Kenneth E. 
Published: May 2018

This paper explores RBC system mechanical and process upgrade alternatives. There may be multiple upgrade opportunities. Some process upgrades are proprietary while others are not. Mechanical and process upgrades describe many positive advantages for existing plants that need to be upgraded to meet more stringent effluent limits or for increased capacity.
A case study was conducted to evaluate a process upgrade. Simple physical manipulation of existing process parameters within the treatment plant and the addition of a new process feature to facilitate secondary sludge recycle to the RBCs showed increased organic capacity and improvement in effluent quality. Also, a significant reduction in nutrients (N & P) without the use of chemicals and a significant reduction in RBC shaft weight were other benefits. The easily settleable solids contained at least a doubling of the phosphorus content and dewatered well without chemical supplementation.
High rate aerated biofilters for plant upgrading
Authors: Rogalla F. , Lamouche A. , Specht W. , Kleiber B. 
Published: May 2018

Biocarbone aerated biofilters were developed more than ten years ago. Almost one hundred plants worldwide provide complete treatment in very short hydraulic retention time. This allows to construct compact plants in sensitive areas such as inner cities, sea or mountain resorts. The filters can be adapted to high effluent qualities expected by the European directive on wastewater treatment. Full oxidation of ammonia can be achieved in less than two hours. A plant for complete removal of nitrogen has been operated for more than a year in Denmark to meet Europe's most stringent effluent requirements by using an anoxic biofilter in series with the Biocarbone.
A new aerated biofilter, turning the Biocarbone principle upside down, is presented : a synthetic floating material allows enhanced performance, simplified backwash and a combination of anoxic and aerobic zones in one reactor. Effluent quality of less than 10 mg/l for all components (BOD, SS, TN) was demonstrated in a one-year long on-site test in Denmark and the first facility for 60 000 population equivalents is under startup. Full scale results of the upflow floating filter, Biostyr, are presented for nitrogen and phosphorus removal according to the European directive.
Sedimentation in Storage Tank Structures
Authors: Stovin Virginia R. , Saul Adrian J. 
Published: May 2018

Although storage tanks provide an effective means of reducing the magnitude and frequency of combined sewer overflow discharges, and thereby of alleviating urban watercourse pollution, poorly designed storage structures frequently suffer from maintenance problems arising from sedimentation. The development of design guidelines that optimise the self-cleansing operation of storage structures is clearly a priority for urban drainage research.
This paper describes a system that has been developed to study sediment deposition in laboratory model-scale storage structures. The patterns of deposition resulting from a selection of flow regimes are described, and the need for time-varying and time series storm tests is highlighted. Sedimentation patterns are shown to predominantly depend on the flow field, and the critical bed shear stresses for deposition and erosion in the model situation are identified. Hence, the potential application of numerical models to the design problem is discussed.
The Prediction of Combined Sewer Overflow Performance from Models – A Case Study
Authors: Hedges Peter D. 
Published: May 2018

Hydrodynamic separators have been employed as combined sewer overflows (CSOs) in the UK since the early 1960s. Since little was known of their operating characteristics, Severn Trent Water Authority contracted Aston University to monitor the performance of a separator constructed during 1986-87 at James Bridge, Walsall, UK. Unfortunately only three overflow events were fully documented during the monitoring period, which was particularly dry. One separator was therefore artificially charged by pumping from the adjacent river to simulate storm flow conditions. A model study was not included in the original proposal, but one was established to complement the main programme since the characteristics of hydrodynamic separators were poorly understood.
The arrangement of the field site is described, and the results from the monitored storm events, pump tests and model studies are summarised. Characteristics derived from the model study are combined with sewage settling velocity grading curves to predict the performance of the prototype hydrodynamic separator for one of the observed storm events. Given the limitations inherent in the sewage data used, a comparison of the predicted and observed separator efficiencies demonstrates the potential of this approach for the design and selection of CSOs for specific locations.
Selector Volume in Pulp and Paper Activated Sludge Wastewater Treatment Plants – Bench Scale and Pilot Plant Studies
Authors: Wessberg J. , Welander T. , Jönsson M. 
Published: May 2018

Laboratory activated sludge reactors were operated on effluent wastewater from a kraft mill. Two of the three reactors were initially preceded with a “normal” size aerated selector, 2% of the total aerated volume, with unsatisfactory sludge volume index development. When the selectors were replaced by larger ones, 13% of the aerated volume, the sludge volume index could be kept below 50 ml/g for the selector processes while continuing to be higher and more unstable in the reference process.
A pilot plant, operated in situ on the same wastewater, showed a comparable improvement in sludge volume index when its selector, 7% of the total volume, was replaced by one that constituted 13% of the total volume, corresponding to a selector load of 3 g BOD / g VSS * d.
According to studies of the COD balance around one bench scale selector, the COD removal mechanism in the selector was respiration/assimilation rather than uptake/storage.
Biological aerated filters: assessment of the process based on 12 sewage treatment plants
Authors: Canler J. P. , Perret J. M. 
Published: May 2018

Biological aerated filtration is a recent and intensive process which has been greatly developed over the last few years. It is a technology based on biological processes with certain advantages, in particular the absence of secondary clarifiers, the modular nature and the wide variety of treatment applications.
The monitoring of a dozen medium capacity (7,500 to 150,000 p.e.) plants designed to treat organic pollution, has enabled us to evaluate the process and its performance.
The results obtained show that at applied loads of less than 7 kg of COD, the effluent is of satisfactory quality (&lt; 90 mg / 1 of COD) and that the process has a high efficiency to remove suspended solids. Numerous other aspects have been studied and the data collected confirm the potential of this process, which nevertheless requires a careful and regular system operation procedure.
Tertiary nitrification in aerated pilot biofilters
Authors: Tschui M. , Boller M. , Gujer W. , Eugster J. , Mäder C. , Stengel C. 
Published: May 2018

Three different types of internally aerated pilot scale biofilters were operated as tertiary nitrification systems. Long-term performance of the three aerated biofilters was tested under various operating conditions. The maximum volumetric nitrification rates under non NH4-limiting conditions for the three aerated biofilter systems were investigated. Based on measured temperature dependencies, an exponential relationship was established enabling the prediction of the nitrification rates at desired temperatures. Based on a temperature of 10°C, the results allow a comparison between the surface and volume specific nitrification rates in the tested biofilters as a function of the NH4 effluent concentration.
As shown by experiments, nitrification performance depends on water as well as air velocities in the filter. Higher velocities of both air and water increase the nitrification rate. However, they also increase the head loss and thus decrease the filter run time. Therefore, the optimal operating conditions depend also on the filter media and the required effluent quality.
Compared to fully O2-limiting operating conditions, nitrification performance during a period under partially NH4-limiting conditions clearly decreased in all tested biofilters.
Optimized lamellae settling for urban stormwater waste
Authors: Delporte C. , Pujol R. , Vion P. 
Published: May 2018

Lamellae sedimentation is an efficient and compact solution for handling high stormwater influx at wastewater treatment plants during rainy periods. This paper presents and comments on the results obtained at several different sites using specially adapted lamellae settlers.
Surface hydraulic loads above 100 m3/m2.h have been reached using optimized doses of chemical reagents.
One key advantage of the reactor is that start-up is practically instantaneous; this means that efficient treatment is obtained right from the start of the high flow period.
Evaluation of hydrodynamic characteristics of the Bosphorus regarding the performance of the marine outfall systems
Authors: Akyarli Adnan , Arisoy Yalçin 
Published: May 2018

Considering strong interrelations between hydrodynamic features of the Bosphorus and the tube-tunnel crossing which may affect the performance of marine outfall systems, the Institute of Marine Science and Technology (IMST) conducted a comprehensive meteo-oceanographic data acquisition campaign to collect information both for the reliable design of marine outfall systems and for the environmental impact assessment (EIA) of the railroad tunnel, on the joint request of the owners of the projects.
The main objectives of this paper are to outline the results of the EIA, and also to discuss the newly adopted plan which proposes to divert the sewage collected in the Kadìköy drainage area to Riva, located along the Black Sea. Recent evaluations by the authors on the blocking of lower layer flow, and findings presented on the mixing along the Bosphorus, have been included as scientific evidences in this discussion.
Mass balance of total phosphorus in the Izmit Bay
Authors: Legovic T. , Morkoç E. , Okay O. S. , Egesel L. , Tüfekci V. , Tüfekci H. 
Published: May 2018

Elements needed to obtain mass balance of a nutrient in a coastal sea by direct methods are: movement of water masses (current field), estimates of location and intensity of all major nutrient sources, estimate of nutrient inflow from the neighboring sea and a reliable estimate of the nutrient extinction in the water column. In practice, the intensity of major sources and extinction of nutrient water column are seldom known. Therefore inverse methods for the transport equation are employed to obtain mass balance.
Mass balance of total phosphorus in the Izmit Bay for March 1994 suggests that total source from the coast is about 1.3 t P/day. The extinction constant is 12 days. The majority of TP originating from the land-based sources of the bay proper ends up in the lower layer of the bay. A small part is transported into the Marmara sea.
Selective mechanisms controlling algal succession in Aydat lake
Authors: Lafforgue Michel , Szeligiewicz Wojciech , Devaux Jean , Poulin Michel 
Published: May 2018

Aydat lake is a dimictic eutrophic lake where Cyanophycean blooms occur. In order to study with accuracy this lake functioning, a one-dimensional vertical model (Licorne 2 model) was developed. This model takes into account physical, chemical and biological interactions and simulates the algal succession of the five main phytoplankton algae for two different years (1984 and 1985).
It appears that the growth rate, the sedimentation rate, or the death rate do not explain by themselves the algal succession, and more specially the blue-green blooms.
However, a good correlation between field data and Licorne 2 results are obtained by introducing specific advantages of blue-green algae such as buoyancy regulation mechanisms, capacity to fix atmospheric nitrogen and to grow at high pH value and toxin production.
In the view of these results, a new understanding of the Aydat lake algal succession is then possible, where competition for light, food and limitation of the losses (sedimentation, grazing) take an important place in a thermal and chemical vertical stratified environment.
Determination of the pollutant far-fields dilution using variable turbulent diffusion coefficients
Authors: Gardanov T. V. 
Published: May 2018

The main subject of the paper is deriving appropriate relationships to calculate the horizontal turbulent diffusion coefficient, the size of the far-field polluted plume and the concentration distribution in the case of the continuous steady state wastewater discharge into receiving marine environment.
The simplified advection diffusion-diffusion equation with variable (depending on the distance from the outfalls) coefficients of turbulent diffusion has been solved for this purpose.
Capturing and releasing settleable solids – the significance of dense undercurrents in combined sewer flows
Authors: Verbanck Michel A. 
Published: May 2018

Particulate organic matter concentrations determined at the outlet of a low-sloped combined sewer are observed to increase significantly in the very early stage of storm runoff events. It is found that this is not a result from scouring of actual deposited sediments in the sewer (which are granular), but from the dynamic behaviour of a distinct component of the sewage flow itself. During low flows in dry weather, a part of the coarsest material present in normal sanitary sewage (primarily organic debris such as human and food wastes, of about millimetric size and larger) settles and leaves the main body of the flow, but does not reach the sewer bottom to deposit there. The lowest part of the flowing sewage acts in this case as a temporary storage of highly polluting matter, as its longitudinal velocity is lower than the one of the remaining flow. An explanation for the building of these ‘dense undercurrents’ is formulated, based on a difference between free settling in the main body of flow and hindered settling near the bottom. Although this still merits further confirmation, it is likely that the process which maintains coarse solids in suspension in the undercurrent is a lift force induced by shear in the near-bed zone.
The collapse of the undercurrent and the subsequent release of polluting material into the whole water column has been observed in the considered sewer to occur when bed shear stress exceeds about 1.1-1.2 N/m2. This low value can explain flushing effects occurring frequently during rainy period, or even at peak dry weather flows. On the basis of properties illustrated in this study, a number of management options can be considered for revised day-to-day operation of low-sloped interceptor sewers where dense undercurrents are likely to develop.
Mathematical modelling of sulphides and hydrogen sulphide gas build-up in the Costa do Estoril sewerage system
Authors: Matos J. S. , Aires C. M. 
Published: May 2018

The Costa do Estoril sewerage system is one of the largest separate systems ever built in Portugal. Because of the quality of the environment in the region and the high level of touristic use, special care was given, in its design, to sulphide calculations.
This paper describes the application to the Costa do Estoril sewerage system of an integrated computer model for forecasting sulphides and hydrogen sulphide gas build-up along sewer atmospheres. The empirical sulphide prediction equations have been calibrated with experimental results obtained under a research project carried out in a gravity tributary and in a rising main located near the Costa do Estoril zone. The hydrogen sulphide gas concentrations along the main trunk line have been predicted according to an mathematical model described by Matos and Sousa.
The results of the model have been considered to be adequate for identifying critical reaches and for predicting the effects of corrective and preventive measures on the overall behaviour of the system.
Sorption sites in biofilms
Authors: Flemming Hans-Curt 
Published: May 2018

The distribution of pollutants in water is strongly dependent on the processes at the solid-liquid interface, such as soprtion. The solid phase is represented by many different materials, mostly minerals but also metals and organics. In technical and natural water systems, biofilms occur to a greater or lesser extent. They will cover the underlying material (substratum) at least partially and represent a gel-type layer, mainly consisting of extracellular polymeric substances (EPS), formed by biofilm organisms, in which the latter are embedded. Thus, the sorption properties of biofilms will significantly determine the overall process. This effect may have been almost completely overseen, e.g., in the assessment of the fate of pollutants in waters, in the process of sediment diagenesis, and in chemical sorption studies. Sorption data can differ considerably between sterile and non-sterile assays; this aspect puts in question many results gained in biologically uncharacterized systems. Sorption in biofilms can be undesired, if pollutants accumulate in biomass such as activated sludge. The same effect, however, can be biotechnologically exploited, e.g. in biosorption reactors.
Biofilms can sorb water, inorganic and organic solutes and particles. As sorption sites can serve: EPS, cell walls, cell membranes and cell cytoplasm. These sites display different sorption preferences, capacities and properties. The situation becomes even more complex as biofilms may respond physiologically to sorbed substances. For example: the uptake of toluene can lead to the formation of uronic acids in the EPS and, thus, to an increased sorption capacity for cations.
When decomposing, biofilms will release sorbed substances. This can be of significance if trickling deposition of sewage water on soil is finished. The biomass will decompose, sorbed pollutants are remobilized and can contaminate the ground water if not retained abiotically by other soil components.
A substantial research demand is identified regarding the following questions: (i) what do biofilms sorb; (ii) what are the binding sites; (iii) what are the sorption mechanisms and capacity, and (iv) what is the remobilization potential?
Fish farming in Denmark: environmental impact of regulative legislation
Authors: Iversen T. M. 
Published: May 2018

The main environmental problems associated with fish farming in Denmark are attributable to the dam, the “dead reach” and nutrient and organic matter discharge. The environmental regulation of fish farming in Denmark started with the Environmental Protection Act of 1974, the Statutory Order of 1985 forbidding wet feed, and the Action Plan on the Aquatic Environment of 1987. In the case of freshwater fish farms, the latter was implemented through the measures stipulated in the 1989 Statutory Order on Fish Farms.
The impact of Danish legislative measures to reduce and regulate the environmental effects of freshwater fish farms can be summarized as follows:
- the number of fish farms has been reduced from about 800 in 1974 to about 500 at present;
- production has tripled since 1974 and has been stable since 1989;
- a change from wet to dry feed has reduced the environmental impact of the farms;
- the national goals of the Action Plan on the Aquatic Environment of 1987 for reducing fish farm discharges of organic matter, nitrogen and phosphorus have been fulfilled.
The main remaining problems are that:
- the local impact of fish farms on downstream stream quality is still much too high in about 15% of cases;
- the problem of the passage of migrating invertebrates and fish is still unsolved at some farms;
- the problems posed by “dead reaches” are still unsolved.
It is concluded that sustainable fish farming is possible in Denmark, but with the present technology production will have to be significantly reduced.
A hydroacoustic waste feed controller for tank systems
Authors: Summerfelt Steven T. , Holland Kyle H. , Hankins Joseph A. , Durant Martin D. 
Published: May 2018

The objective of this work was to develop a commercially viable method to reduce waste feed and thus improve production efficiency and reduce discharge of solids and nutrients within tank based aquaculture systems. We developed and custom fabricated a feeding controller which uses ultrasound to detect uneaten feed and controls feeding events based upon appetite satiation as measured by the quantity of waste feed detected. During feeding, the developed device functions as a combination ultrasonic detector, feedback controller, and interval timer. The device functions as a feedback controller by ultrasonically sampling the stock tank effluent and turning off the feeder when an excessive amount of feed enters the effluent flow. After feeding has been inactivated, the ultrasonic waste feed controller operates as an interval timer and provides a user selected delay between feedings. A custom hydroacoustic probe assembly was developed to detect uneaten feed.
The controller can be calibrated by adjusting the transducer signal gain to detect signals resulting from feed pellets, while reducing signals resulting from faeces. The controller has an adjustable set-point for deactivating the feeder circuit based upon the number of feed pellets detected by the transducer and a programmable delay time interval (from 5 to 160 min) to set the time between feedings. The controller also has an adjustable sampling rate for detection at different pipe velocities and an adjustable observation volume for use in standard 2, 3, 4 and 6 inch diameter effluent pipes.
The cost in materials and labour to produce this waste feed controller was estimated at around $100 (U.S.).
Difficulties in modelling phosphate evolution in a high-rate algal pond
Authors: Mesplé F. , Troussellier M. , Casellas C. , Bontoux J. 
Published: May 2018

The High-Rate Algal Pond is an efficient treatment for controlling wastewater pollution by reducing the organic matter and the inorganic nutrient. The removal of phosphate is of great importance considering eutrophication. Deterministic modelling of the HRAP ecosystem could provide a rational basis for pond management.
The aim of this paper is to underline the difficulties in modelling orthophosphate evolution in an HRAP. A model simulating the evolution of orthophosphate concentrations in an experimental HRAP was developed taking into account the usual processes: inflow, outflow, mineralization of dead algae and uptake by phytoplankton. These processes allow us to simulate quite well the evolution of the orthophosphate concentration.
According to the literature, the precipitation of calcium phosphate (at high pH) should be taken into account in calcium-rich waters but the models allowing calculation of PO4 concentration according to pH variations neglect PO4 uptake by algae.
The problem is that both direct (uptake) and indirect (precipitation) phenomena act on phosphate removal when algae grow.
It is possible, by striking chlorophyll a and phosphorus balance, to assess the precipitation of phosphates; the results are consistent with the fact that uptake by phytoplankton is the main process acting on PO4 evolution.