bluuebunny/crossref_metadata_2025_split huggingface dataset:
A systematic approach to error isolation in computerized wastewater simulation models
Authors: Lennox J. A. , Yuan Z. , Harmand J. 
Published: May 2018

Activated sludge models are used extensively in the study of wastewater treatment processes. While various commercial implementations of these models are available, there are many people who need to code models themselves using the simulation packages available to them. Quality assurance of such models is difficult. While benchmarking problems have been developed and are available, the comparison of simulation data with that of commercial models leads only to the detection, not the isolation of errors. To identify the errors in the code is time-consuming.
In this paper, we address the problem by developing a systematic and largely automated approach to the isolation of coding errors. There are three steps: firstly, possible errors are classified according to their place in the model structure and a feature matrix is established for each class of errors. Secondly, an observer is designed to generate residuals, such that each class of errors imposes a subspace, spanned by its feature matrix, on the residuals. Finally, localising the residuals in a subspace isolates coding errors. The algorithm proved capable of rapidly and reliably isolating a variety of single and simultaneous errors in a case study using the ASM1 activated sludge model. In this paper a newly coded model was verified against a known implementation. The method is also applicable to simultaneous verification of any two independent implementations, hence is useful in commercial model development.
Industrial applications of new sulphur biotechnology
Authors: Janssen A.J.H. , Ruitenberg R. , Buisman C.J.N. 
Published: May 2018

The emission of sulphur compounds into the environment is undesirable because of their acidifying characteristics. The processing of sulphidic ores, oil refining and sulphuric acid production are major sources of SO2 emissions. Hydrogen sulphide is emitted into the environment as dissolved sulphide in wastewater or as H2S in natural gas, biogas, syngas or refinery gases. Waste streams containing sulphate are generated by many industries, including mining, metallurgical, pulp and paper and petrochemical industries.
Applying process technologies that rely on the biological sulphur cycle can prevent environmental pollution. In nature sulphur compounds may cycle through a series of oxidation states (-2, 0, +2, +4, +6). Bacteria of a wide range of genera gain metabolic energy from either oxidising or reducing sulphur compounds. Paques B.V. develops and constructs reactor systems to remove sulphur compounds from aqueous and gaseous streams by utilising naturally occurring bacteria from the sulphur cycle. Due to the presence of sulphide, heavy metal removal is also achieved with very high removal efficiencies. Ten years of extensive laboratory and pilot plant research has, to date, resulted in the construction of over 30 full-scale installations. This paper presents key processes from the sulphur cycle and discusses recent developments about their application in industry.
Experimental and modeling evaluation of upward and downward velocities in the coaxial flotation column
Authors: Park K. , Cho J.-M. , Oh J. , Chung K. 
Published: May 2018

This study was conducted to show the influence of upward velocity in the inner column and downward velocity in the outer column of the coaxial cylinder-type flotation column on the solids removal efficiency, solids concentration in the treated water, and so on. The SIMPLE (Semi-Implicit Method for Pressure Linked Equation) solution was applied to the coaxial flotation column to simulate the velocity vectors of the elements of water flowing in the column. The effects of solids loading and residence time in the agglomerate separation zone on the solids removal efficiency were also tested.
In the pilot scale coaxial DAF column experiments with solids concentration of 1,000–2,000 mg of SS per liter and solids loading less than 350 kg/m2/day, approximately 90% of the solids removal efficiencies were obtained using the upward velocity of up to 110 cm/min in the contact zone of the inner column and the downward velocity of up to 30 cm/min in the outer column. In the simulation, similar results were observed as in the experiments. The solids loading in the excess of 350 kg/m2/day caused the instability of the sludge float layer and aggravated the quality of the treated water.
Water recycling at the Millennium Dome
Authors: Hills S. , Smith A. , Hardy P. , Birks R. 
Published: May 2018

Thames Water is working with the New Millennium Experience Company to provide a water recycling system for the Millennium Dome which will supply 500m3/d of reclaimed water for WC and urinal flushing. The system will treat water from three sources:rainwater - from the Dome roofgreywater - from handbasins in the toilet blocksgroundwater - from beneath the Dome site
The treatment technologies will range from “natural” reedbeds for the rainwater, to more sophisticated options, including biological aerated filters and membranes for the greywater and groundwater. Pilot scale trials were used to design the optimum configuration. In addition to the recycling system, water efficient devices will be installed in three of the core toilet blocks as part of a programme of research into the effectiveness of conservation measures. Data on water usage and customer behaviour will be collected via a comprehensive metering system. Information from the Dome project on the economics and efficiency of on-site recycling at large scale and data on water efficient devices, customer perception and behaviour will be of great value to the water industry. For Thames Water, the project provides vital input to the development of future water resource strategies.
Particle size analysis as a tool for performance measurements in high rate effluent filtration
Authors: van der Graaf J. H. J. M. , de Koning J. , Tang J. 
Published: May 2018

In the Netherlands almost all wastewater treatment plants have been redesigned and adapted in order to remove nitrogen, phosphorus and suspended solids to a very low level. The improved effluent quality leads to a growing interest in the reuse of effluent of the modernised wastewater treatment plants. This again results in investigations on filtration techniques as deep bed filtration and membrane filtration. At the wastewater treatment plant Ede research was done on deep bed filtration in order to develop relations between particle removal and filter performance and to explore ways of optimization.
The results of the experiments are rather typical for effluent of modern Dutch wastewater treatment plants. The very low concentrations of suspended solids and precipitable substances result in poor flocculating properties.
From turbidity measurements it may be concluded that the best results were obtained with a dosage of flocculant. However, the particle size measurements indicated the opposite. Suspended solids calculations, based on the particle volume distributions, showed a better removal without a dosage of flocculant. From this it is concluded that a dosage of coagulant (Fe3+ or Al3+) has an adverse effect on the removal efficiencies even at low dosages (1 mg/l).
Moving-bed biological treatment (MBBT) of municipal wastewater: denitrification
Authors: Maurer M. , Fux C. , Graff M. , Siegrist H. 
Published: May 2018

Denitrification in a full-scale installation and a pilot plant for moving-bed biological treatment (MBBT) was subject to detailed investigation. Two different types of carriers were used in conventional activated sludge reactors: foam cubes and plastic tubes (Kaldnes®).
Both investigated carriers showed the same behavior with regard to denitrification capacity, temperature dependency and maximum COD and nitrate turnover. In contrast to the plastic tubes (Kaldnes®), the sponge cubes stored remarkable amounts of substrate. The maximum denitrification rate with acetate as a substrate was 420 gNm-3d-1 at 10°C and 730 gNm-3d-1 at 20°C. An average denitrification rate of 240 gNm-3d-1 (10°C) was achieved with wastewater. A maximum of 37% of the COD in the influent was denitrified with a volumetric loading rate in the anoxic zone of 2.2 kgCODm-3d-1.
New simulators for the optimum management and operation of wastewater treatment plant
Authors: Ayesa E. , Garralon G. , Rivas A. , Suescun J. , Larrea L. , Plaza F. 
Published: May 2018

This paper presents the basic description and the first full-scale implementation of a new kind of simulator specially designed to facilitate and improve the management and operation of modern wastewater treatment plants (WWTP). This new kind of simulator for plant operation is specifically adapted to every WWTP and the software is developed considering the common needs of the operators in plant exploitation.
The internal structure of the plant operation simulator is based on a complete connection between the real data and the mathematical model of the plant. The software is then able to perform the processing, storage and management of the plant data and to predict the evolution of the process reading the required inputs from its stored files. The results obtained with the first application recommend the implementation of this new kind of simulators for plant operation in other treatment plants. However, it is important to note that the application of this technology implies a systematic and rigorous methodology in the acquisition and processing of the most significant plant data.
Removing filterable reactive phosphorus from highly coloured stormwater using constructed wetlands
Authors: Lund M.A. , Lavery P.S. , Froend R.F. 
Published: May 2018

A constructed wetland design, consisting of 16 repeating cells was proposed for Henley Brook (Perth, Western Australia) to optimise the removal of FRP from urban stormwater. Three replicate experimental ponds (15×5 m), were constructed to represent at a 1:1 scale a single cell from this design. Three 5 m zones of each pond were sampled: shallow (0.3 m) vegetated (Schoenoplectus validus) inflow and outflow zones and a deeper (1 m), V-shaped central zone. In 1998/99, inflows and outflow waters were intensively sampled and analysed for FRP and Total P. In addition, all major pools of P (plants, sediment) within the ponds, and important P removal processes (benthic flux, uptake by biofilm and S. validus) were quantified.
A removal efficiency of 5% (1998) and 10% (1999) was obtained for FRP. Initial uptake was mainly in plant biomass, although the sediment became an increasingly important sink. Benthic flux experiments showed that anoxia did not cause release of P from sediments, indicating that most of the P was bound as apatite rather than associated with Fe or Mn. The highly coloured waters were believed responsible for the very low biofilm biomass recorded (&lt;1 g.m-2). We have demonstrated that constructed wetlands can be effective for removing FRP immediately after construction, although their long-term removal capacity needs further research.
Nitrogen removal in a combined system: vertical vegetated bed over horizontal flow sand bed
Authors: Kantawanichkul S. , Neamkam P. , Shutes R.B.E. 
Published: May 2018

Pig farm wastewater creates various problems in many areas throughout Thailand. Constructed wetland systems are an appropriate, low cost treatment option for tropical countries such as Thailand. In this study, a combined system (a vertical flow bed planted with Cyperus flabelliformis over a horizontal flow sand bed without plants) was used to treat settled pig farm wastewater . This system is suitable for using in farms where land is limited.
The average COD and nitrogen loading rate of the vegetated vertical flow bed were 105 g/m2.d and 11 g/m2.d respectively. The wastewater was fed intermittently at intervals of 4 hours with a hydraulic loading rate of 3.7 cm/d. The recirculation of the effluent increased total nitrogen (TN) removal efficiency from 71% to 85%. The chemical oxygen demand (COD) and total Kjeldahl nitrogen (TKN) removal efficiencies were 95% and 98%. Nitrification was significant in vertical flow Cyperus bed, and the concentration of nitrate increased by a factor of 140. The horizontal flow sand bed enhanced COD removal and nitrate reduction was 60%. Plant uptake of nitrogen was 1.1 g N/m2.d or dry biomass production was 2.8 kg/m2 over 100 days.
Occurrence and die-off of indicator organisms in the sediment in two constructed wetlands
Authors: Stentström T.A. , Carlander A. 
Published: May 2018

The interest in constructed wetlands for municipal wastewater and stormwater treatment has recently increased but data for the reduction efficiency of indicator organisms are often restricted to the water phase. In a full-scale wastewater wetland in Sweden fecal coliforms and enterococci were reduced by 97-99.9% and coliphages by approximately 70%. The factors affecting the reduction are however less well understood.
In two full-scale wetlands, for stormwater and wastewater treatment, an assessment has been done of the particle associated fraction of indicator organisms. No significant differences in the particle-associated numbers were seen between the inlet and the outlet of the wetlands, but the amounts of sedimenting particles varied between the two sites. In the stormwater wetland the amount of sedimenting particles at the outlet was 3% of the amount at the inlet, while the wastewater wetland had much lower particle removal efficiency. The reduction of suspended particles seems to be the main factor for bacterial elimination from the water phase, governed by vegetation and design. In the sediment, survival of presumptive E.coli, fecal enterococci, Clostridium and coliphages were long with T90-values of 27, 27, 252 and 370 days, respectively. The organisms can however be reintroduced by resuspension. Viruses in the water phase may be of main concern for a risk assessment of receiving waters.
A constructed surface flow wetland for treating agricultural waste waters
Authors: Borin M. , Bonaiti G. , Santamaria G. , Giardini L. 
Published: May 2018

A study was conducted between December 1997 and December 1998 in NE Italy on a 3,200 m2 surface flow vegetated wetland receiving agricultural drainage water from a cultivated field of about 6 ha and occasional applications of organic wastes. The study aimed at evaluating: 1) biomass and seasonal nitrogen dynamics in above- and below-ground biomass of Phragmites australis Cav. (Trin.) and Typha latifolia (L.) grown in separate zones; 2) the effectiveness of the wetland in removing nutrients and sediments coming from the fields; 3) the possibility that wetland could treat occasional applications of organic wastes and 4) to collect some general information on whether the wetland can receive heavy loads coming from storm water runoff.
Monthly observations showed that, in both species, aboveground biomass, nitrogen concentration and nitrogen content reached maximum values in summer and minimum values in winter. The contrary occurred in below-ground biomass. The total input of water in the wetland was 66,000 m3 ha-1, of which 7,700 were drained. Total nitrogen input was 526 kg ha-1, of which 58 were discharged out of the wetland.
Sludge accumulation in polishing ponds treating anaerobically digested wastewater
Authors: Cavalcanti P. , van Haandel A. , Lettinga G. 
Published: May 2018

When ponds are used for wastewater treatment, settleable solids will form a steadily growing bottom sludge layer, which reduces their effective volume. Eventually this sludge must be removed to ensure that the pond maintains the required retention time to keep performing properly. The settleable solids may either be present in the influent or they are formed during the treatment as a result of algal flocculation.
An experimental investigation was carried out to evaluate bottom sludge accumulation in a polishing pond used for treatment of UASB effluent. The mass and composition of the bottom sludge formed in a polishing pond was evaluated after the pilot scale pond had been in operation for 1 year and about 60 m3 of digested wastewater had been treated per m3 of pond. The bottom sludge mass represented a solids accumulation of 70 g per m3 of digested wastewater. About half of these solids were the result of settling of influent solids in the first part of the pond, while the other half was attributable to settling of algae, formed in the pond. It is concluded that the bottom sludge growth in a polishing pond is so low, that desludging during the useful life span of the pond will most likely not be necessary. This leads to the important conclusion that excess sludge discharge from UASB reactors (a major factor in operational costs) may be omitted, if a polishing pond is used for post-treatment. The bottom sludge had a high volatile solids concentration (58%) and the macronutrient fractions were also high (3.9% N and 1.1% P of the TSS mass). The bottom sludge was stable and could be dried directly without problems. The hygienic quality of the bottom sludge was very poor: about half the influent helminth eggs during one year of operation were found in the bottom sludge and the faecal coliform concentration was very high.
The use of rapid environmental assessment techniques to monitor the health of Australian rivers
Authors: Greenwood-Smith S.L. 
Published: May 2018

River managers require tools to assess the ecological condition of waterways and prioritise management strategies. As benchmarking the condition of an entire waterway with detailed surveys is often not practical, Rapid Environmental Assessment Techniques have been developed to provide an indication of the state of a river's health, both rapidly and at a low cost. In this investigation, three such techniques, developed recently in Australia, are applied to the same creek in order to compare the outcomes and the levels and types of resources required for their application.
The output from the three indices ranges from descriptive to statistically analysed data, making them difficult to compare directly. Overall, the three indices all report that the sample creek had relatively poor health. The results from the Victorian Index of Stream Condition and New South Wales' Pressure, Biota, Habitat Stream Assessment appear to correlate well.
An important finding of the investigation is the variation in the resources required to apply each assessment technique. Generally, the resource demands increase with the requirement for a higher level of scientific rigour. The methods are either relatively inexpensive and rapid to undertake or more resource intensive, yet thorough in the data collected. A two step process incorporating the techniques in a cost-effective manner is recommended.
Ecological condition of central Australian arid-zone rivers
Authors: Choy S.C. , Thomson C.B. , Marshall J.C. 
Published: May 2018

Australian arid-zone rivers are known to be ecologically variable and go through “boom and bust” cycles based on highly variable and unpredictable flow regimes. They are facing increasing pressure from land and water resources development and, whilst they are considered to be still in relatively good condition, no studies have yet been carried out to verify this. Such baseline studies are crucial if we are to assess any ecological changes in response to development and management interventions. The ecological condition of four of these endorheic rivers (Georgina, Diamantina, Cooper-Thomson and Bulloo) flowing into the Lake Eyre and Bulloo Basins in central Australia was assessed using several criteria (level of human influence, habitat condition, water chemistry and aquatic macroinvertebrate composition). Using criteria based on the level of human influence, most of the sites were assessed to be relatively unimpacted (reference) condition. The most discernible and widespread impact was riparian and bank damage by stock access. However, the level of this impact was considered to be only moderate.
Most aquatic macroinvertebrates found in the area are considered to be opportunistic and tolerant of a wide range of environmental conditions, but with their life histories known to be linked to flow conditions. Their trophic guild was dominated by collectors and predators. The AusRivAS modelled observed to expected values of macroinvertebrate composition indicated that there were differences in ecological condition between sites (e.g. different waterholes) and between times (e.g. seasons and years). Overall, 75% of sites were assessed to be good condition with the remainder being mildly impaired.
Water chemistry of the sites was characterised by high spatial and temporal variability with low conductivity and alkaline pH, relatively high turbidity, total nitrogen and total phosphorus, and wide-ranging dissolved oxygen. Given the high variability in water quality and ecological condition within a catchment, there was little evidence of any overall difference in these factors between the catchments. However, given that the hydrology of each river system is distinctly different, one might expect some differences in ecological structure and function at finer scale. Periods of hydrological isolation (eg. to allow natural dryouts) as well as the maintenance of natural connectivity (eg. instream, overbank and floodplain wetting) are both necessary for the maintenance of ecological integrity of these systems.
Surface aeration and a small footprint can be combined
Authors: Janssen P.M.J. , Meinema-Linders K. , Niermans R.P. 
Published: May 2018

In densely populated areas new WWTPs will need to be designed on a relatively small area. This paper describes a deep Carrousel© (oxidation ditch) concept resulting in a “small footprint” for the aeration basin combined with an efficient and flexible oxygen input. To enable surface aeration in a deep Carrousel system, the basin was provided with so-called draft tubes, vertical cylinders located underneath aerators, almost extending down to the bottom. A draft tube enables the aerator to draw sludge/water mixture from the bottom of the tank, thereby ensuring proper oxygenation of the tank contents over the entire tank depth. The results of pilot-scale tests for verification of the performance of an aerator equipped with a draft tube are presented.
The full scale WWTP Leidsche Rijn, a compact “wrapped-around” Carrousel-3000 system where the draft tube technology is applied in a 7.5 metre deep basin, is described. Before the plant was put into operation a verification test for the aeration efficiency with clean water was carried out. The test showed that the draft tubes have no negative impact on the aeration efficiency of the surface aerators and justified the chosen design concept.
The Millennium Dome “Watercycle” experiment: to evaluate water efficiency and customer perception at a recycling scheme for 6 million visitors
Authors: Hills S. , Birks R. , McKenzie B. 
Published: May 2018

Thames Water's “Watercycle” project at the Millennium Dome was one of the largest in-building recycling schemes in Europe, designed to supply up to 500 m3/d of reclaimed water for WC and urinal flushing. It catered for over 6 million visitors in the year 2000. Overall, 55% of the water demand at the Dome was met by reclaimed water. The site was also one of the most comprehensive studies ever carried out of water conservation in a public environment, evaluating a range of water efficient appliances and researching visitor perceptions of reclaimed water.
Within the Dome there were six identical core buildings housing the washrooms, which were equipped with a variety of different water-efficient devices for comparison. Water usage by the different appliances was monitored using a sophisticated metering and telemetry system. The importance of correct installation and maintenance of “high tech” water efficient devices was highlighted during the research programme, as some water wastage occurred due to poor installation. The results prove that metering should complement any large-scale water efficient system, so that any faults with the appliances can be quickly identified. The visitor survey showed very positive attitudes to the use of reclaimed water for non-potable uses.