bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sediment resuspension and light conditions in some shallow Dutch lakes
Authors: Blom G. , van Duin E. H. S. , Lijklema L. 
Published: May 2018

The relationship between sediment resuspension and light conditions has been studied in three shallow Dutch lakes. In shallow eutrophic lakes, the contributions of algae and suspended sediments to light attenuation are usually dominant. Wind induced resuspension of bottom sediment and sedimentation often determine the dynamics and the spatial variability of the suspended solids concentration and the light attenuation coefficient. A model is discussed relating the suspended solids concentration and light attenuation coefficient to the orbital velocity, induced by waves, and to the fall velocity of solids.
Using experimental data, the relationships between fall velocity, organic matter content and the specific vertical attenuation coefficient are analyzed. Differences in the specific vertical attenuation coefficient and in fall velocities of sediment fractions, are related to differences in particle size as well as differences in composition. The contribution of (resuspended) particles to the suspended solids concentration and to light attenuation is primarily due to slow settling sediment fractions which are rich in organic matter. So in modelling light attenuation dynamics especially these fractions are of interest. Heavier fractions can be disregarded. A model for the relationship between resuspension and light attenuation dynamics, based on this conclusion, has been tested successfully for 2 shallow Dutch lakes.
Biological nutrient removal applied to weak sewage
Authors: Charlton J. 
Published: May 2018

The Melby Wastewater Treatment Plant is located in the municipality of Frederiksværk on the island of Sealand, Denmark. This may be the first full-scale plant in Europe purpose built for biological nutrient removal from diluted wastewater, i.e. weak domestic wastewater mixed with infiltration waters.
The relatively strict effluent standards have required the existing treatment plant to be upgraded in capacity, including the design for biological Nitrogen and Phosphorus removal. Due to the weak nature of the influent wastewater, the treatment process that has been adopted includes the application of a primary sludge fermenter to alter the influent characteristics suitable for biological nutrient removal. The treatment process used is the Modified University of Cape Town process utilising a primary sludge fermenter developed at the University of British Columbia in Canada. The combination of these two processes has been successfully applied to meet the strict discharge licence requirements, without the addition of chemicals, despite the unsuitable characteristics of the influent wastewater for biological nutrient removal. The paper describes the operational results for the treatment plant.
Upgrading of existing sewage treatment plants by computer simulation: game or reality?
Authors: van der Kuij R. J. , van Bentem A. G. N. , van Breukelen F. Th. 
Published: May 2018

From 1 January 1995 in The Netherlands 75% of the phosphorus in the influent has to be removed in the waste water treatment plants (wwtp's). At this moment 40 – 50% is reduced by biological incorporation and some chemical dosing. By additional measures an extra 35% reduction has to be accomplished. A further reduction of total nitrogen to 75% has to be realised from 1 January 1998.
Further extension of the activated sludge system is not always possible and in most cases rather expensive. Therefore optimization of the existing treatment plant is considered.
For this purpose the advanced simulation model STREAM• is used. With STREAM• almost every waste water treatment plant can be simulated with the computer. In this way, for example, the effect of different control mechanisms and other measures can be studied without costly research.
Computer simulation has been applied at the Kralingseveer wwtp of the HH van Schieland (Waterboard in the Netherlands) to optimize aeration control and to evaluate a number of technological process adjustments. Attempts are being made to reduce nitrogen drastically using equipment currently available, supplemented where possible with other limited measures.
It can be concluded from the results of simulation, that the use of integrated aeration control, whereby influent flow, and nitrate and ammonium concentrations in the activated sludge are measured on-line, further improves the treatment process. Furthermore, when the sludge content in the aeration tank is raised and nitrogen is removed from the internal return flows, it seems that an average annual effluent quality of 10 mg Ntotal/1 is feasible. Verification of these factors will be carried out in the near future using practical measurements.
The Kralingseveer project demonstrates that computer simulation is more than simply a ‘game’. It has become a real means of guiding or even limiting the need for extensive and costly (practical) investigation.
Performance of methane fermentation pits in advanced integrated wastewater pond systems
Authors: Oswald William J. , Green F. Bailey , Lundquist Tryg J. 
Published: May 2018

Advanced Integrated Wastewater Pond Systems (AIWPSs) involve a series consisting of Advanced Facultative Ponds with internally located fermentation pits; secondary ponds with either photosynthetic oxygenation or mechanical aeration; tertiary ponds for sedimentation of either algae or aeration solids; and, quaternary ponds for controlled discharge, irrigation storage, aquaculture, or other beneficial uses of reclaimed wastewater.
This paper deals mainly with design and performance of Advanced Facultative Ponds containing internally located fermentation pits. Experiences with a 1,894 m3 day−1 (0.5 MGD) AIWPS and a 7,576 m3 day−1 (2.0 MGD) AIWPS indicate that primary facultative ponds with internal fermentation pits require less land than do conventional anaerobic ponds and that sludge removal is postponed for many years. New, more detailed, and controlled scientific studies on a 133 m3 day−1 (0.035 MGD) demonstration AIWPS at the University of California, Berkeley, Environmental Engineering and Health Sciences Laboratory in Richmond, California provide evidence that these simple pits remove suspended solids and biochemical oxygen demand more effectively than do comparably loaded conventional anaerobic ponds and produce much less odor. In addition they improve removal of parasites, bacteria, viruses, heavy metals, and halogenated hydrocarbons. The reliability and cost effectiveness of AIWPS is compared with more conventional ponds and with mechanical wastewater treatment systems.
Biological phosphorus uptake in submerged biofilters with nitrogen removal
Authors: Gonçalves R. F. , Le Grand L. , Rogalla F. 
Published: May 2018

This paper introduces biological phosphorus removal (Bio-P) from wastewater on a submerged biofilter. Pilot scale research was carried out over a period of two years using a floating upflow aerated filter, originally designed for nitrification and denitrification of sewage. The factors which influence Bio-P on fixed film processes and the possible biofilter configurations which eliminate C, N and P are discussed. The procedures are applicable to all types of treatment plants using biofilters, both new and already in existence, making no distinction between the different processes available today, co-current and counter-current filters.
Biological phosphorus removal can be associated to the different treatment levels required: organic matter removal; secondary nitrification secondary nitrification and denitrification. For the third option - complete nutrient removal, treatment is completed with a hydraulic retention time in the filter bed of under four hours. Because of the simultaneous filtration with effluent SS below 10 mg/l, low phosphorus residuals can be achieved by Bio-P alone. The modifications required for setting up this operating procedure on any treatment plant are presented.
Aerobic biodegradation of azo dyes in biofilms
Authors: Jiang H. , Bishop P. L. 
Published: May 2018

Factors affecting biofilm removal of azo dyes from a synthetic, municipal-type wastewater were investigated using lab-scale, rotating drum biofilm reactors. Among the three azo dyes studied - Acid Orange 8, Acid Orange 10, and Acid Red 14 - only AO-8 degraded aerobically. The azo bond cleavage occurred very easily for all three dyes under anaerobic conditions. AO-8 removals ranged from 20% to 90%. Statistically designed experiments were used to characterize the response of pseudo-steady state biofilms. Two AO-8 removal rate maxima were identified - one at high bulk-phase dissolved oxygen and low COD removal flux, and the other at low dissolved oxygen and high COD flux.
The presence of azo dyes, along with other factors such as COD loading, bulk-phase DO level and shear force, showed impact on biofilm accumulation.
General assessment of potential CSO reduction by means of real time control
Authors: Jørgensen Michael , Schilling Wolfgang , Harremoës Poul 
Published: May 2018

A number of case studies have been carried out in which the potential reduction of combined sewer overflows (CSO) by means of real time control (RTC) is assessed for existing sewer systems. It is an inherent problem of case studies that results cannot necessarily be generalized. In this paper results of a systematic investigation of hypothetical combined sewer systems are presented. The systems were characterized in terms of their topological structure, size, type and arrangement of storage and transport elements.
The RTC optimization model LOCUS was applied to simulate the performance of local control and of optimum control strategies. The results are expressed as “CSO reduction achieved by optimum control, compared to the locally controlled system”.
General conclusions are drawn with respect to possible CSO reduction for a system with given topology, storage and transport characteristics. Finally, these are compared to some case studies reported in the literature in order to verify and show the general applicability of the findings.
Modelling the coliforms inactivation rates in the Cantabrian sea (bay of Biscay) from in situ and laboratory determinations of T90
Authors: Canteras Juan C. , Juanes José A. , Pérez Luisa , Koev Kalin N. 
Published: May 2018

Precommissioning studies of proposed outfalls along the north coast of Spain included in situ and laboratory determinations of T90 values directed at the development of a local-specific inactivation model.
The effect of salinity, light intensity, temperature and depredation on inactivation (T90) of Escherichia coli, was studied in unifactorial experiments carried out in the laboratory. The values of T90 obtained fitted the exponential model of die-off for the first three variables (salinity, light, temperature: R &gt; 0.93). Light intensity showed the greatest bactericidal effect, with T90 values near or lower than 1 hour, when light radiation was greater than 120 Wm−2. The logarithm of T90 showed a linear relationship with each one of these three factors. Nevertheless, the global relationship which best fits the values obtained was not linear in its coefficients.
The values of T90 estimated from experiments in situ, carried out in summer (33.6 min) and winter (116.8 min), reflected the seasonal differences in the environmental conditions in this zone, mainly from light intensity. Differences between these values and those obtained applying the model pointed out the need to study in depth the effect of light on the bacterial die-off in natural systems.
The use of wetlands for the control of non-point source pollution
Authors: Raisin G. W. , Mitchell D. S. 
Published: May 2018

There is increasing interest in the use of wetlands to intercept nutrients in diffuse run-off from rural catchments. However, the scientific basis for this strategy is far from secure. While research in several countries provides support for this approach, there is a general lack of rigorous data sets of nutrient balances showing the real effect of such wetlands on the quality of run-off emanating from rural catchments. Research being conducted on two natural and one constructed wetlands in south-eastern Australia will contribute to filling this gap.
In each of these three wetlands, volume of inflow and outflow is being measured at 15 minute intervals. Automatic water samplers connected to the flow measurement device are measured and are triggered to take samples at appropriate intervals during run-off events. All these water samples are analysed chemically and the total loads of selected chemicals entering and leaving a wetland are calculated for several storm events over the winter and spring period during 1993.
Results for Total Nitrogen and Total Phosphorus show that during winter there is a net release of these nutrients from the linear wetlands with greater flows resulting in greater flushing. However, in spring and early summer there was a net retention of nutrients in the wetlands despite similar hydrological loadings. These results were affected by the size of the wetland relative to the catchment (and therefore retention time), land use of the catchment, any intrusion of ground water and the nature of the wetland in terms of its shape and vegetation.
Refuse pollution of seas and oceans
Authors: Clunie W. F. , Hendricks D. W. 
Published: May 2018

Refuse pollution of seas and oceans is not visible and the effects are difficult to assess. Attention to this problem has emerged seriously only since the 1980s. Marine scientists and environmental groups have been obtaining various data, however, and have indicated serious problems on a global scale to human values. Health, ecology, fisheries, commerce, recreation, etc., are areas of concern. The Black Sea may be as polluted as the world seas as a whole.
Refuse concentration of the oceans globally and of the Black Sea was estimated by the materials balance principle. A conceptual model, based upon the entropy principle, provides a means to estimate the energy of refuse cleanup. The model provides a rationale as to why the strategy for control must be containment of refuse.
Volatile fatty acids and sulfide in pressure mains
Authors: Hvitved-Jacobsen T. , Raunkjær K. , Nielsen P. H. 
Published: May 2018

The main objective was to study the anaerobic transformation of organic matter and sulfide production during wastewater transportation. Emphasis was on the transformation of easily biodegradable organic matter in terms of volatile fatty acids (VFA). Samples from two intercepting pressure mains located in the Northern part of Jutland, Denmark, were taken.
The concentration of VFA in the wastewater varied considerably during day and night, being typically between 5 and 50 g/m3. A net production as well as a net removal of VFA was seen during transportation in the pressure mains probably depending on the quality and quantity of the organic matter. Typically 85% of the VFA was acetate and 10% propionate; the remainder was formate, n-butyrate and iso-butyrate. Observed sulfide production rates from the sewer biofilms were typically 0.05 and 0.005 g S/m2 h at 12 and 4 °C, respectively. A high sulfide production rate corresponded with a high VFA concentration. TOC removal was observed in the pressure mains.
The gully pot as a biochemical reactor
Authors: Morrison Gregory M. , Revitt D. Michael , Ellis J. Bryan 
Published: May 2018

Roadside gully pots (catch basins) have been identified as potential sources that can make significant contributions to stormwater pollutant loadings. Between storm events the gully pot sediment and liquor undergo changes in composition as a result of biochemical reactions. Sediment maturation and acidic dissolution processes release pollutants from the contaminated chamber sediments and interstitial pore waters into the relatively clean gully pot liquor. Dissolved pollutant profiles for gully pot outflows therefore show substantial early contributions from gully pot liquor and interstitial waters reflecting microbial and geochemical degradation processes which act upon the trapped chamber sediments both during and between storm events.
The majority of dissolved organic carbon is washed out in the gully pot outflow in the early low flow stages, suggesting that the main contributing source is the supernatant gully pot liquor. Small additional releases coincide with, and indicate additional releases of, soluble organics from the interstitial waters as the basal sediments are disturbed. Conductivity changes show that dissolved inorganics also exhibit efficient removal during the low flow stages of storms, with the absence of delayed peaks indicating a negligible contribution from the settled gully pot sediments.
During storm events, low runoff rates produce marked decreases in pH levels from the initial gully pot liquor value of pH 6.0-7.1 to a value approaching typical rainfall levels (average rainfall pH = 4.1). This lowering of the pH indicates that the dissolved buffering agents initially present on the road surface and in the gully pot liquor have become depleted and exhaustion of dissolved Ca clearly illustrates this effect. Initial decreases in dissolved oxygen concentrations and redox potential are indicative of exposure of the reduced basal sediments as overlying supernatant liquor is washed out. A subsequent secondary decrease in redox potential, coinciding with increasing flows, is due to the additional release of reduced interstitial waters as the gully pot basal sediments are disturbed. Finally, dissolved oxygen levels return to normal as the oxygenated surface waters become predominant in the outflow waters.
Is it possible to influence water temperature and quality in the river seine upstream of Paris in summer by managing the upstream reservoirs?
Authors: Malatre K. , Goose Ph. 
Published: May 2018

There are four major reservoirs upstream of Paris, on the Seine, Aube, Marne and Yonne rivers. These reservoirs partially prevent flooding in winter and spring, and supply water in summer to maintain a minimum river flow. The quantitative and qualitative impact of summer water releases from dams on temperature and quality of downstream rivers has been assessed, thanks to a measurement survey conducted in 1990 and 1991 and use of simulation models.
Two types of reservoirs are distinguished:
– the Yonne reservoir, directly on the river, which is rather deep and can have a significant influence on the near downstream temperature, but hardly any just upstream of the Seine confluence
– the Seine, Aube and Marne reservoirs, bypassing the rivers, which are shallow and have a very moderate impact on downstream temperatures.
The study of an experimental water release on the Seine showed that for this second type of reservoir it is difficult to achieve considerable improvement in water quality in the downstream rivers by means of reservoir releases in summer, except locally in cases of significant pollution inputs. Among the ten parameters under study, conductivity and alkalinity were the only ones measured whose values could be affected by the dam release over a distance greater than 100 km downstream.
Study of nitrifying biofilms in submerged biofilters by experimental design methods
Authors: Fdz-Polanco F. , Méndez E. , Villaverde S. 
Published: May 2018

The relative influence of influent ammonium concentration, pH, temperature, filter height and liquid and gas superficial velocities over the biofilm growth and activity in submerged nitrification biofilters has been experimentally studied. The goal is to quantify the relative contributions of the different control parameters over the biofilm growth and the specific activity of ammonia and nitrite oxidizer microorganisms.
The use of statistical tools like the experimental design methods, allows to characterize quantitatively the control parameters of the system and the levels providing the most favorable response of the system, in such a way that the noise factor influence is minimized. The experimental period is reduced eight times comparing to the traditional study of parameters influence.
Multicriteria methods in river basin planning – a case study
Authors: Anand Raj P. 
Published: May 2018

A large number of multicriteria decision making (MCDM) methods have been proposed in the past and applied to water resources planning. The development and application of systems analysis techniques to assist decision makers in evaluating project alternatives having more than one objective in river basin planning is of recent origin.
In this paper an attempt is made to demonstrate the use of ELECTRE (ELimination and (Et) Choice Translating REality) I and ELECTRE-II techniques for water resources planning in one of the major river basins (Krishna river basin) of South India. The river basin consists of 8 reservoirs and a diversion work. Formulation of the problem is provided leading to an array of 27 alternative systems (different combinations of reservoirs with a minimum of three in each alternative) with 6 criteria related to: (i) irrigation, (ii) power production, (iii) drinking water, (iv) environmental quality; (v) floods and (vi) cost of the project. Out of the six criteria two, namely environmental quality and floods, are qualitative in nature. A set of best alternative systems with their partial ordering is obtained from ELECTRE-I, which forms the input for ELECTRE-II. Complete ordering of the reduced alternatives is achieved with ELECTRE-II. Sensitivity analysis shows that changing the weights assigned to each criterion has greater effect on the results than does changing the scales. However, neither effect is significant. Therefore it is recommended that ELECTRE-I be used for screening alternatives under consideration and ELECTRE-II for complete ordering of the reduced set.
Two-stage UASB concept for treatment of domestic sewage including sludge stabilization process
Authors: Sayed S. K. I. , Fergala M. A. A. 
Published: May 2018

A multi-target study was conducted to assess the feasibility of the UASB-reactor system for the anaerobic treatment of raw domestic sewage (low-strength complex wastewater; CODtot=200-700 mg/l and CODss=45-55% of CODtot) combined with sludge stabilization process under a moderate temperature of 18-20 °C.
The study has produced a design of a modified Three-Phase Separator (TPS) to control the sludge retention inside the UASB reactors as well as the determination of design parameters of the treatment process viz. the hydraulic retention time (HRT), the potential period of loading the UASB reactors and the most convenient digestion time required for advanced sludge stabilization. The study was performed in a Two-Stage Flocculent-Granular-Sludge UASB-reactor system. The first stage consisted of two identical UASB reactors seeded with flocculent sludge and operated alternately (i.e. one reactor was fed while the other was unfed for the stabilization of the sludge). The second stage consisted of one UASB reactor seeded with granular sludge and was operated continuously. The feed period and the corresponding feedless period of the first stage were two days.
The results study have shown that the removal efficiency of the COD increases considerably with the decrease of the HRT, as a treatment efficiency of 75% was achieved at HRT=10 h (8 h for Stage I and 2 h for Stage II), while the treatment efficiency was 84% at HRT=6 h (4 h for Stage I and 2 h for Stage II). In contrast to the above the extent of sludge stabilization (i.e. conversion into methane) for the first stage of the system was directly proportional to the HRT as 41% of the removed CODtot was converted into methane at HRT=8 h, the conversion ratio decreased to 28% at HRT=4 h.
For the granular sludge (the second stage of the system), the conversion ratio of the removed CODtot into methane was almost stable in the range of 17-20%. The percentages CODpaper-filtered of the CODtot were 85-90% and 92-97% for the effluents of the first and second stages respectively with the conclusion that the modified Three-Phase Separator (TPS) has a satisfactory operational potential.