bluuebunny/crossref_metadata_2025 huggingface dataset:
Screening of various types biomass for removal and recovery of heavy metals (Zn, Cu, Ni) by biosorption, sedimentation and desorption
Authors: Bakkaloglu I. , Butter T.J. , Evison L.M. , Holland F.S. , Hancock I.C.
Published: May 2018

The increasing awareness of accumulation of heavy metals in the environment has led to a quest for new and improved “clean” technologies. In this regard, an innovative heavy metal removal process composed of biosorption, sedimentation and electrolysis was developed. This study covers the comparison of various types of waste biomass including bacteria (S. rimosus), yeast (S. cerevisiae), fungi (P.chrysogenum) and activated sludge as well as marine algae (F.vesiculosus and A.nodosum), for their efficacy in the biosorption, sedimentation and desorption stages in the removal of zinc, copper and nickel ions. In the biosorption studies carried out with single metal solutions, A. nodosum, S.rimosus and F.vesiculosus proved to be the best biosorbents for zinc, copper and nickel ions respectively. In ternary metal solutions, the presence of other metal ions affected the biosorption efficiency. S.rimosus, however, exhibited high specificity for Cu and A.nodosum roughly retained its metal uptake for all of the metal ions. The sedimentation efficiencies were found to be proportional to the biosorption efficiencies. Desorptions were not effective, hence recycling did not yield good results. Overall, among the biomass tested, A.nodosum, S.rimosus, F.vesiculosus and P. chrysogenum were found to have the highest potential for use in the heavy metal removal process.
Arsenic removal in fresh and nom-preloaded ion exchange packed bed adsorption reactors
Authors: Vagliasindi F. G. A. , Benjamin Mark M.
Published: May 2018

Arsenic speciation and removal in continuous-flow packed bed adsorption reactors was investigated using a strong base anion exchange resin as the adsorbent. Preloading of the media was investigated passing arsenic-free Lake Washington water through columns packed with the resin prior to feeding influent spiked with arsenic. NOM preloading did not affect the systems, but sulfate adsorbed during the preloading and the subsequent adsorption steps caused chromatographic displacement of the adsorbed arsenic. Significant arsenic speciation changes occurred in the arsenic-spiked feeding solution that need further investigation.
Anaerobic treatment of soil wash fluids from a wood preserving site
Authors: Miller K. M. , Suidan M. T. , Sorial G. A. , Khodadoust A. P. , Acheson C. M. , Brenner R. C.
Published: May 2018

An integrated system has been developed to remediate soils contaminated with pentachlorophenol (PCP) and polycyclic aromatic hydrocarbons (PAHs). This system involves the coupling of two treatment technologies, soil solvent washing and anaerobic biotreatment of the extract. Specifically, this study evaluated the effectiveness of the granular activated carbon (GAC) fluidized-bed reactor to treat a synthetic waste stream of PCP and four PAHs (naphthalene, acenaphthene, pyrene, and benzo(b)fluoranthene) under anaerobic conditions. This waste stream was intended to simulate the wash fluids from a soil washing process treating soils from a wood preserving site. The reactor achieved a removal efficiency of greater than 99.8% for PCP with conversion to its dechlorination intermediates ranging from 47% to 77%. Effluent, carbon extraction, and isotherm data also indicate that naphthalene and acenaphthene were removed from the liquid phase with efficiencies of 86% and 93%, respectively. Effluent levels of pyrene and benzo(b)fluoranthene were extremely low due to the adsorptive capacity of GAC for these compounds. Experimental evidence does not suggest that these compounds were chemically transformed within the reactor.
Modeling nitrate leaching using neural networks
Authors: Kaluli J. W. , Madramootoo C. A. , Djebbar Y.
Published: May 2018

Accurate evaluation of nitrate leaching potential in agricultural fields is a major challenge. Field data are expensive to gather and use of existing prediction models is limited by inadequate understanding of the physical and chemical processes underlying nitrate leaching. A neural network model was developed to acquire the inherent characteristics of an experimental data set, and successfully used to simulate nitrate leaching in agricultural drainage effluent under various management systems. Simulation results indicated that: (i) sub-irrigation with a 0.5 m water table depth could reduce nitrate leaching to negligible levels, (ii) intercropping corn with ryegrass could reduce nitrate leaching by 50%, and (iii) the application of more than 180 kg N ha−1 of fertilizer may cause excessive nitrate leaching.
Adsorption of pentachlorophenol (PCP) by activated carbon in fixed beds: application of homogeneous surface diffusion model
Authors: Slaney A. J. , Bhamidimarri R.
Published: May 2018

The adsorption of pentachlorophenol (PCP) from aqueous solutions was investigated using fixed beds of activated carbon. The equilibrium behaviour was shown to fit a Freundlich isotherm with the values of parameters K and l/n of 95 and 0.180 respectively, which are comparable to those of other substituted phenolics. The surface diffusion coefficient was evaluated from batch kinetic adsorption experiments and was found to be 2.26 × 10−9 cm2s−1. The film transfer coefficient in the fixed beds was estimated using Gnielinski’s correlation. A Homogeneous Surface Diffusion Model (HSDM) was proposed to predict the PCP adsorption breakthrough curves in the fixed beds. The diffusion and convection equations were integrated using a combination of orthogonal collocation and Runge-Kutta techniques. The experimental results on the adsorption of PCP in activated carbon columns proved that the HSDM can predict the column performance satisfactorily and therefore can be used in the design of fixed beds for removal of PCP.
Rapid bioassay of toxicity in environmental water by LDL-uptaking activity of human cell
Authors: Shoji Ryo , Sakoda Akiyoshi , Sakai Yasuyuki , Suzuki Motoyuki , Utsumi Hideo
Published: May 2018

Recently, environmental waters involving river water usually used as a source of drinking water have been polluted by various chemicals produced by human activities. We reported in our previous work that the variation of toxicity in urban river water is so fast that the general bioassays cannot catch up with the variation. Thus, a bioassay that can rapidly detect the toxicity is required. in this work, we developed a rapid bioassay based on LDL, uptaking activity of human cells and elucidated its fundamental characteristics. Also, toxicity of 30 chemicals was evaluated by this assay and compared with that measured by a conventional cell growth inhibition assay. By the method developed, the cytotoxicity of river water was elucidated in only 4 hours. Therefore, the new bioassay proposed in this work is very promising for water quality management.
Estimating environmental pollution by xenobiotic chemicals using QSAR (QSBR) models based on artificial intelligence
Authors: Kompare B.
Published: May 2018

An attempt was made to construct QSAR (Quantitative Structure-Activity Relationships) or QSBR (Quantitative Structure-Biodegradation Relationships) formulae and models for predicting biodegradability of chemicals in aqueous aerobic environment with machine learning (ML) tools of artificial intelligence (AI). Inverse of biodegradability is environmental persistence, from which possible dynamics of soil, groundwater and water pollution can be inferred. We tried to predict the biodegradability with several programs that can learn from examples and construct decision or regression trees and/or can construct equations. Besides the given basic topological properties, the main contribution was inclusion of connectivity indices. Above all, normalization of properties to molecular weight or the number of carbon atoms significantly improved prediction. The obtained results are comparable (or better) to the best achieved results with other approaches. Contrary to the statistical methods, ML tools present the information (learned knowledge) in a compact, easily understandable manner which can help identify and understand the key properties of chemicals and mechanisms important for assessing biodegradation (and thus possible environmental contamination) from chemical structure only.
Water pollution control in the river basin by fuzzy genetic algorithm-based multiobjective programming modeling
Authors: Chen H. W. , Chang Ni-Bin
Published: May 2018

Designing water quality management strategies is often complicated by the difficulty in simultaneously considering large amounts of relevant data, applicable submodels, competing objectives, unquantifiable factors, nonlinear characteristics, and uncertainty during parameterization. Mathematical optimization techniques offer promise in identifying optimal or satisfactory strategies that may be used as benchmarks for decision making. Newer optimization techniques such as genetic algorithm (GA) and fuzzy mathematical programming make the search for optimal control strategies in an uncertain environment more feasible. Using a probabilistic search procedure that emulates Darwinian natural selection, GAs allow multicriteria decision making with respect to both nonlinear feature and fuzzy characteristics to be incorporated directly into the optimization process and generate trade-off curves between cost and environmental quality while identifying good control strategies. This paper verifies such a discovery by a case study of water quality control in the Tseng-Wen river basin in Taiwan.
Cometabolic biodegradation of trichloroethylene (TCE) in the gas phase
Authors: Cox Chris D. , Woo Hae-Jin , Robinson K. G.
Published: May 2018

Biofiltration is an effective means of destroying contaminants present in waste gases generated during subsurface remediation. Potentially, biofilters can be used in the cometabolic destruction of chlorinated organics. Biofiltration columns inoculated with Pseudomonas putida F1 removed between 30 and 60% of TCE using toluene as the primary growth substrate. Biofilter performance appeared to be limited by competitive inhibition, product toxicity, and the enzyme activity and NADH levels within the cells. Aqueous-phase batch experiments were used to quantify the extent of competitive inhibition and the effect of toluene and TCE on toluene dioxygenase enzyme activity.
Experimental setup for the study of soil vapor extraction: a practical approach to determine sorption effect
Authors: Rodríguez-Maroto J. M. , Gómez-Lahoz C. , Vereda-Alonso C. , García-Herruzo F. , García-Delgado R. A.
Published: May 2018

Soil Vapor Extraction is one of the most used in situ technologies for the removal of volatile contaminants from the vadose zone. Development of mathematical models and validation with field results has improved the understanding of processes occurring during remediation. One of the most important is the transport of the contaminants from the different phases present in the soil to the gaseous one which is governed by thermodynamic and kinetic laws. In this work, the analysis of the response curves to Dirac pulses in soil columns for the determination of both the thermodynamic and kinetic parameters is considered. Results obtained for sand columns with typical gasoline and solvent compounds are presented. This analytical technique does not require long periods of time, is sensitive to relatively low partition coefficients, and reproduces closely the actual soil conditions so any kinetic limitations that may appear during operation should be observable in these experiments.
Photocatalytic degradation of parathion in aqueous TiO2 dispersion: the effect of hydrogen peroxide and light intensity
Authors: Chen Tsu-feng , Doong Ruey-an , Lei Wen-gang
Published: May 2018

The photodegradation of parathion in the direct photolysis, UV/TiO2, UV/H2O2 and UV/TiO2/H2O2 systems was investigated at 25°C. The effect of light intensity was also examined to clarify the relationship between the photo flux and decomposition rate of parathion. Results of the study demonstrated that no obvious degradation of parathion in dark reaction occurred within 24 hours. However, the addition of TiO2 and/or H2O2 promotes the degradation efficiency of parathion. Adding H2O2 was more effective in the photocatalytic oxidation of parathion than TiO2. Also, hydrogen peroxide was found as an intermediate with the maximum concentration of 55 μM in UV/TiO2 system during the photodegradation of parathion. A higher intensity of lamp could increase the degradation rate of parathion. However, the quantum efficiency for degradation of parathion decreased from 0.053 to 0.006 when light intensity increased from 100 W to 450W. Photodecomposition followed a pseudo-first-order reaction. The rate constants of parathion ranged from 0.003 min−1 for direct photolysis to 0.023 min−1 for UV/TiO2/H2O2 system. This study indicated that photocatalytic degradation is a highly promising technology for detoxifying parathion.
Upgrading of waterworks with a new biooxidation process for removal of manganese and iron
Authors: Hedberg T. , Wahlberg T. A.
Published: May 2018

The paper describes how waterworks can be upgraded by the use of microbiologically unit operations to make it possible to remove manganese from groundwater and surface water. Pilot plant studies and full-scale plant studies show that conventional oxidants as permanganate may be replaced by biooxidation thus reducing the use of chemicals in water treatment. Water containing high amounts of Fe and/or Mn and organic matter may be difficult to treat and pilot plant studies are therefore recommended. This study shows that one ground waterworks and one surface waterworks succed in removing manganese where previous treatment with permangante had failed.
Upgrading wastewater treatment plants by the use of biofilm carriers, oxygen addition and pre-treatment in the sewer network
Authors: Æsøy Anette , Ødegaard Hallvard , Hægh Marius , Rislå Frode , Bentzen Greta
Published: May 2018

In upgrading of treatment plants for enhanced nitrification there are three strategies (1) the existing process may be optimised with respect to the biological activity, (2) the biological activity may be increased by changing to a process with a higher capacity, and (3) a combination of 1 and 2. The potential of the first strategy in a KMT moving bed biofilm process (the kaldnes process) is presented in this paper. The nitrification capacity was enhanced by using pure oxygen resulting in an increased oxygen concentration, and the specific biomass activity was increased by removing organic matter and sulphide in the sewer network by addition of nitrate to the wastewater. The results show that the nitrification capacity may be increased by 30–40% by pre-treatment of wastewater in the sewer network and increased by 40–50% by using an increased oxygen concentration in the first step of the nitrification reactor. Oxygen concentrations below 12 mg O2/l and/or the amount of biomass were found to be the limiting factors at ammonium concentrations above 5–7 mg NH4-N/l.
Upgrading for nitrogen removal under severe site restrictions
Authors: Balmér P. , Ekfjorden L. , Lumley D. , Mattsson A.
Published: May 2018

The Rya WWTP in Göteborg, Sweden is a highly loaded activated sludge plant which has been upgraded to remove nitrogen and to increase the biologically treated flow by 33% to reduce bypassing. Severe site restrictions made it difficult to increase the plant area. This was solved using a compant process based on tertiary nitrification in trickling filters and recirculation to a highly loaded activated sludge unit for denitrification. The necessary volumes were achieved by expanding the plant upwards, thus making it possible to place the trickling filters a in part of the area occupied by the former aeration basins. The recirculation of trickling filter effluent made it necessary to double the secondary settler capacity. This was solved by retrofitting the existing settlers as stacked settlers with a second tray on top of the original basin. The considerations behind process selection and plant design and costs are described.
Temperature effects on biological nutrient removal system with weak municipal wastewater
Authors: Euiso Choi , Daewhan Rhu , Zuwhan Yun , Euisin Lee
Published: May 2018

The wastewater characteristics of low organic strength coupled with low temperature would be considerable variables for design and operation of biological nutrient removal (BNR) systems. But temperature studies have mostly been focused on individual process with biological phosphorus removal, nitrification and denitrification, respectively. Overall temperature effects on BNR system may not be fully represented by sum of results of separated studies on biological nutrient removal steps. The operating result of a retrofitted full scale unit along with laboratory-scale BNR unit indicated 90% of nitrification was possible at temperature as low as 8°C. However, the denitrification was turned out to be a key step to regulate the overall nutrient removal efficiencies. When the operating temperature dropped down, a rapid decrease of phosphorus removal efficiencies was observed by the nitrate in return sludge. If nitrification was not well developed, phosphorus removal returned to the normal efficiency even at low temperature of 5°C. The phosphorus removal mechanism was not influenced at this low temperature.
Effects and mechanisms involved in preoxidation and particle separation processes
Authors: Jekel Martin R.
Published: May 2018

Particle separation in water treatment can be enhanced by preoxidation with different chemicals. Effects were reported for preoxidation by ozone, chloride, chlorine dioxide, permanganate and chloramines. The observations depend on the raw water source, season, oxidant dosage and the applied particle separation processes. Most research interest has found preozonation for particle removal and the underlying mechanisms. The literature of the last decades include several mechanisms thought to be responsible for the observed effects. A significant role is played by the natural organic matter (NOM) in view of its efficiency in stabilizing dispersed particles by adsorption and by its reactions with the coagulants. Preozonation effects in algae-laden waters are important but require further studies.
Particles under stress
Authors: Boller Markus , Blaser Stefan
Published: May 2018

The complex nature of particulate matter in natural water resources and in waste waters is characterized by the heterogeneous distribution of particle size, shape, density, and shear strength. Among these parameters, floc strength is most important in the last stages of flocculation. Experimental data on floc strength based on different methods are assessed and correlated with shear gradients in different aquatic environments. The analysis of turbulent motion reveals that the energy which affects particle agglomerates is only a small portion of the totally dissipated energy. Among the different flow fields in turbulent motion, converging/diverging flow cause strain forces which prove to be critical with respect to floc rupture. Model calculations of the surface forces on ellipsoidal particles in pure shear and strain flow fields and corresponding experiments confirm the importance of converging flow. A comparison of modeled and measured rupture forces allows to establish relationships between floc size, strain and shear rates and resulting surface forces leading to probable floc break-up. Flocs of appreciable size (200 - 2000 μm) prepared for settling are likely to be ruptured under moderate velocity gradients occurring in flocculation tanks, whereas smaller agglomerates (< 200 μm) may withstand strain forces much higher than found under practical conditions. An example of model application shows the particle stress in the entrance to porous media filters where typically high strain gradients may easily lead to a breakup of flocs larger than 200 μm.
Characterization and aquatic impacts of combined sewer overflows in greater vancouver British Columbia
Authors: Hall Ken J. , McCallum Donald W. , Lee Kathy , Macdonald Ronald
Published: May 2018

The Greater Vancouver Regional District has been assessing the environmental concerns and management problems associated with combined sewer overflows (CSOs) as part of their long range liquid waste management plan. There are currently 52 CSO outfalls in the region with some of the major outfalls having 100-150 discharge events/yr concentrated in the winter months. Physical/chemical/microbiological characterization studies of CSO discharge has been investigated at 7 sites. Statistical analysis of these quality data have demonstrated that it can be segregated into three groups based on land use characteristics, namely residential, light industrial, and heavy industrial. These quality characteristics were used along with land use characterization of the 52 collection areas and discharge data to determine the loading of contaminants to the different waterways in the region. The contaminant loading in the region is dominated by the Clark Drive CSO since it contributes 40% of the annual discharge volume to the inner harbor of Burrard Inlet. Contaminant loading calculations from other sources demonstrates that, the sewage treatment plant predominates in the outer harbor, while the CSO and stormwater predominate in the inner and central harbor respectively. At the large Clark Drive outfall, dye tracer and numerical modelling were used to characterize the dispersion plume. Ecological effects of the contaminants were determined using the sediment quality triad. Silver sediment contamination, toxicity bioassays, and benthic invertebrate community structure analysis were useful indicators of the environmental effects of this discharge. Similar studies at the English Bay CSO, which only has 1/90 of the Clark Drive discharge, found sediment contamination levels that exceeded sediment contaminant criteria, but ecological impacts were less severe.
Discriminating faecal pollution: a case study of stormwater entering Port Phillip Bay, Australia
Authors: Leeming R. , Bate N. , Hewlett R. , Nichols P. D.
Published: May 2018

This investigation was designed to provide preliminary information to the Environment Protection Authority concerning the input of faecal matter to stormwater drains in the Rippleside area of Geelong, Victoria. Results derived from the combined use of sterol biomarkers (e.g. coprostanol and 24-ethylcoprostanol) and four sub-groups of bacterial indicators (e.g. thermotolerant coliforms, E. coli, faecal streptococci and enterococci) indicated that during wet weather, all sites sampled were affected by significant human faecal contamination. Ratios of coprostanol to bacterial indicators were similar to those for samples collected from nearby sewer mains. During dry weather, there were still severely elevated levels of faecal contamination based on bacterial indicators, but correspondingly low concentrations of faecal sterols suggesting minimal human or herbivore faecal contamination. The origin of the majority of the faecal pollution in dry weather therefore remains to be fully explained. It is clear from this and related studies that the combined measurement of faecal sterols and bacterial indicators can greatly assist distinguishing sources of faecal pollution. It is also shown for aquatic environments that the measurement of coprostanol or other single indicators alone, is inadequate to fully discern faecal contamination from human sources.
Considering the impact of intermittent discharges when modelling overflows
Authors: Jubb Sarah , Hulme Philip , Guymer Ian , Martin John
Published: May 2018

This paper describes a preliminary investigation that identified factors important in the prediction of river water quality, especially regarding dissolved oxygen (DO) concentration. Intermittent discharges from combined sewer overflows (CSOs) within the sewerage, and overflows at water reclamation works (WRW) cause dynamic conditions with respect to both river hydraulics and water quality. The impact of such discharges has been investigated under both wet and dry weather flow conditions. Data collected from the River Maun, UK, has shown that an immediate, transient oxygen demand exists downstream of an outfall during storm conditions. The presence of a delayed oxygen demand has also been identified. With regard to modelling, initial investigations used a simplified channel and the Streeter-Phelps (1925) dissolved oxygen sag curve equation. Later, a model taking into account hydrodynamic, transport and dispersion processes was used. This suggested that processes other than water phase degradation of organic matter significantly affect the dissolved oxygen concentration downstream of the location of an intermittent discharge. It is proposed that the dynamic rate of reaeration and the sediment oxygen demand should be the focus of further investigation.
The influence of location and season on the concentrations of macroions and organic trace pollutants in roof runoff
Authors: Förster Jürgen
Published: May 2018

In a study of the quality of runoff from roof surfaces, five individual house roofs in the city of Bayreuth, Germany, were compared with experimental roofs on the university campus and with the depositing precipitation. While the city locations all had different exposition characteristics, the campus site experienced urban background conditions without local emissions on or nearby the roofs. The concentrations of the substances under investigation showed a high degree of variability both within and in between single precipitation events. While the wet deposition load of organic micropollutants is increased by washoff of dryly deposited substances (e.g. PAH, ammonium) from the roof surfaces, the concentrations of inorganic ions like calcium were also increased by leaching from the roof material itself. For both processes, there were marked differences between the roofs studied. PAH concentrations in runoff from one roof receiving emissions from old heating systems were elevated by more than one order of magnitude. According to the source variability for the respective substances, seasonal trends could also be detected. The investigation shows that it is difficult to generalise the pollution level of roof runoff even within a small area. This has to be taken into account for the planning of alternative urban drainage systems like infiltration facilities.
Advanced membrane technology for application to water treatment
Authors: Magara Yasumoto , Kunikane Shoichi , Itoh Masaki
Published: May 2018

Following the successful implementation of the ‘MAC21’ Project, the ‘New MAC21’ Project is being implemented for further development of membrane technology in Japan. The project includes various pilot-scale and laboratory experiments on 1) nanofiltration system, and 2) MF/UF system combined with advanced treatment processes such as activated carbon treatment, ozonation and biological treatment. As the result, it has been shown that both systems are applicable to drinking water treatment. Although a NF system was very effective for the removal of organic contaminants such as precursors of disinfection by-products, it is considered that the development of a proper treatment method for the concentrate will be very important in the future.
Initiatives to tackle diffuse pollution in the UK
Authors: D'Arcy Brian J. , Usman Fauzia , Griffiths David , Chatfield Phillip
Published: May 2018

Initiatives to address the problem of diffuse pollution in the UK are reviewed. Characteristics of the problem and key pollutants are identified: oil, pesticides, sediment, organic wastes, faecal pathogens, nutrient, trace metals and solvents; of importance to potable supplies as well as causing environmental pollution. Options to address the problem include action by central government, limited regulatory activity by environment agencies, and educational campaigns. Examples of several UK initiatives are given. Factors in considering effectiveness of measures are proposed, (i) in measurable improvements in the environment and (ii) in indirect measures, eg. numbers of BMP's provided, kilometres of buffer zone established, tonnage of waste oil recycled etc.
Water quality modeling in the watershed-based approach for waste load allocations
Authors: Gu Ruochuan , Dong Mei
Published: May 2018

The conventional method for waste load allocations (WLA) employs spatial-differentiation, considering individual point sources, and temporal-integration, using a constant flow, typically 7Q10 low flow. This paper presents a watershed-based seasonal management approach, in which non-point source as well as point sources are incorporated, seasonal design flows are used for water quality analysis, and WLA are performend in a watershed scale. The strategy for surface water quality modeling in the watershed-based approach is described. The concept of seasonal discharge management is discussed and suggested for the watershed-based approach. A case study using the method for the Des Moines River, Iowa, USA is conducted. Modeling considerations and procedure are presented. The significance of non-point source pollutant load and its impact on water quality of the river is evaluated by analyzing field data. A water quality model is selected and validated against field measurements. The model is applied to projections of future water quality situations under different watershed management and water quality control scenarios with respect to river flow and pollutant loading rate.
Estimating sanitary flows using neural networks
Authors: Djebbar Y. , Kadota P. T.
Published: May 2018

The estimation of sanitary sewer flows is required to effectively plan, design, build, operate, and maintain sewerage facilities. Existing flow estimation methods are crude and often not intended to represent actual conditions but rather to act as guidelines, often for design purposes. This study proposes a neural network approach to estimating actual sanitary flows under dry weather conditions. Development as well as validation showed the neural network model to produce results with an average error less than 16% when compared to measured data.
Forecasting of H2S build-up in a reclaimedwastewater pipe
Authors: Elmaleh S. , Delgado S. , Alvarez M. , Rodríguez-Gómez L. E. , Aguiar E.
Published: May 2018

The present study has been carried out in a completely filled gravity pipe, 61 km long, which transports reclaimed urban wastewater (RUWW), for crop irrigation in the island of Tenerife (Spain), at an average water velocity of 0.4 m/s. Due to the long residence time of the reclaimed wastewater in the pipe (40 hours), anaerobic conditions usually appear, and chemical transformation of reclaimed wastewater occurs during transportation, especially sulfide generation. Field studies have been conducted from November 1994 to January 1997. The variation in sulfide and oxidation-reduction potential (ORP) among other parameters during wastewater transportation have been reported. The object of this work is to study the kinetics of the sulfide generation in a full scale reclaimed wastewater pipe, in order to obtain a forecasting equation of sulfide generation, and to compare this equation with those previously proposed for raw wastewater sewers. Equations obtained from this research differ quite from those previously proposed for sewers. This can be due to the reclaimed wastewater used in this system, which has a very much lower organic matter content than raw wastewater.
Wastewater quality changes during transport in sewers – an integrated aerobic and anaerobic model concept for carbon and sulfur microbial transformations
Authors: Hvitved-Jacobsen T. , Vollertsen J. , Tanaka N.
Published: May 2018

Organic matter in sediments from pipes and silt traps in combined sewers was divided into fractions with different settling velocities. Biodegradability of organic matter for these fractions was characterised based on results from a conceptual model of aerobic transformations of resuspended sediments calibrated on oxygen utilisation rates. Pipe sediments as well as silt trap sediments were investigated and no differences between these deposits were detected. It was found that the largest fraction of organic matter is associated with material which settles relatively fast and only a small part is associated with relatively slow settling material. However, the fast settling organic matter was found to be rather slowly biodegradable compared to the slow settling organic fraction. Because the biodegradability of the organic matter discharged during combined sewer overflow (CSO) events is of significant importance to the impact on the dissolved oxygen concentrations in receiving waters, the biodegradability of sewer sediments is argued to be taken into account for detailed characterisation when dealing with CSO impacts.
On the spatial validity of heavy point rainfall measurements
Authors: Einfalt Th. , Johann G. , Pfister A.
Published: May 2018

Model simulations rely on rainfall measurements, mostly recorded by point measurement devices, i.e. raingauges. When using data from extreme rainfall events, the model user has to take into account the validity of point measurements in space. The presented study outlines investigations in the field of rainfall variability due to the actual situation of general weather types during several events. The Boye catchment is part of the Emscher system (850 km2), located in north west Germany. Data from seven continuous raingauges (1990 to 1996) were analysed, together with data from synoptic classifications of the general weather type. Various statistical parameters were computed for the 200 most important rain events, both stationwise and for the whole event over the complete catchment area. The investigation results show that for particular synoptic rainfall situations, the raingauge in the centre of the catchment overestimated the areal rainfall calculated by the Thiessen procedure from all seven raingauges. The results also demonstrate the spatial variation of rainfall as well as observed event duration and event volume variation for different synoptic situations. It is pointed out that reduction factors should be applied to the data of the single raingauge in the centre of the 80 km2 catchment area used in longterm simulation.
Problems of decision making for a sustainable development
Authors: Rauch W.
Published: May 2018

Current environmental policy guidelines are mainly based on cost-benefit analysis and concerned with the restriction of emissions. Sustainable development, on the other hand, is focusing on determining the optimal strategy for the overall performance of both the environment and the socio-economic system. This paper highlights some of the basic problems when developing strategies with the above aim in mind. The implications for decision making are investigated by means of a fictitious model of the economical and environmental interactions in a lake region.
Required accuracy of rainfall data for integrated urban drainage modeling
Authors: Rauch W. , Thurner N. , Harremoës P.
Published: May 2018

It is standard practice in integrated urban water management to apply mathematical models of the total drainage system for calculating the frequency of occurrence of critical states in the receiving water body. The model input for such computations are long term time-series of rainfall data. However, it is inevitable that those rainfall data measurements deviate from reality. This is a result of inaccuracy of the measurement devices, errors in data transmission, local meteorological effects, etc. In this work we investigate the effect of such uncertainty in the rainfall data on the return period of the occurrence of oxygen depletion in the river due to the drainage of storm water. The errors in the rain data measurements are simulated by means of both stochastic and deterministic models. A comparison of the results obtained from the erroneous data series against the reference data reveals the small effect of random deviation in rain measurements. Only a constant and significant offset of the measured data (greater 20%) has an equally significant effect on the modeling result.
Development of soil metal criteria to preserve groundwater quality
Authors: Lee Suen-Zone , Chang Lizone , Chen Chien-Min , Liu Ming-Chou , Tsai Li-Jyur
Published: May 2018

The principal impediment in the remediation of contaminated sites and in the protection of groundwater quality is the lack of appropriate and reasonable standards for heavy metals in soils. There are no standards applicable to predict the potential for groundwater contamination by heavy metals in Taiwan. Lack of these soil standards may result in subjective judgment regarding the remediation needed. The migration of heavy metals through the unsaturated zone to groundwater is controlled by sorption to the soil, a highly pH-dependent process, and the hydrological regime. Soil sorption behavior is the criterion upon which to establish a standard based on a maximum permissible concentration in groundwater. The maximum level of metal in soil for which the equilibrium soluble metal does not exceed the Drinking Water Standard can be computed, at any pH, from the measured adsorption coefficient for any metal and soil. These metal criteria can be used as soil standards that will be protective of groundwater quality. Criteria for soil remediation are based on specific soil types and the effect of pH on metal sorption because the partitioning of trace metals is highly dependent on the solution pH and the chemical nature of the soil.
Empirical and theoretical assessment of the wind induced error of rain measurement
Authors: Sevruk B. , Nespor V.
Published: May 2018

The computational fluid dynamics and the simulation of precipitation trajectories was applied to assess the wind induced error of precipitation measurements using the Hellmann gauge. The results agree well with the empirical correction formula for the same gauge type derived from field data obtained from inter comparison measurements of paired Hellmann elevated and pit gauges in Les Avants (982m asl), Switzerland. This means that correction procedures can be derived for any type of gauge using the theoretical approach instead of the empirical one. The computational and empirical results fit a model which uses the intensity of rain as an independent variable and produces a set of one parameter curves (wind speed) with increasing threshold value of intensity for increasing wind speed. Below the threshold values the wind-induced error increases quickly with decreasing intensity of precipitation; above it the increase is slow.
Biodegradation of polycyclic aromatic hydrocarbons (PAH) in marine sediment under denitrifying conditions
Authors: MacRae Jean D. , Hall Kenneth J.
Published: May 2018

Polycyclic Aromatic Hydrocarbons (PAH) are common environmental pollutants that have been linked to cancerous lesions in bottom fish. In this research, the feasibility of using nitrate as an alternative electron acceptor to stimulate PAH-degradation in anoxic marine sediment was investigated. PAH could be degraded under denitrifying conditions as long as other nutrients were not limiting. The half lives of low molecular weight PAH ranged from approximately 33-88 days. Degradation of high molecular weight PAH was slower, or not observed. Half lives ranged from 143-812 days. Nitrate may be applied to sediments in situ or used in bioreactors to reduce the cost of bioremediation operations ex situ.
Simulating cryptosporidium exposures in drinking water during an outbreak
Authors: Gale P.
Published: May 2018

This paper predicts exposures to Cryptosporidium parvum oocysts through drinking water under conditions which are consistent with a waterborne outbreak. Sources of variation which contribute to the variation in oocyst exposures include the oocyst densities in the raw waters, the efficiency of oocyst removal by treatment and the daily consumption of unboiled tap water. Even under outbreak conditions the majority of consumers may not ingest any oocysts each day. Of those who are exposed, some ingest just one oocyst/d while others ingest higher doses, which in a small proportion approach the ID50 for C parvum. Ignoring this variation and using a single point average exposure predicts that a much larger proportion of the population is exposed each day but only ever to very low doses of oocysts. The impact of ignoring this variation on the predicted risks depends on the nature of the dose-response curve and, in particular, the assumptions made about the low dose extrapolation. The heterogeneity of oocyst densities in drinking water during an outbreak could contribute to the failure to detect oocysts in some waterborne outbreaks.
A method for the prioritization of areas experiencing microbial pollution of surface water
Authors: Venter S. N. , Kühn A. L. , Harris J.
Published: May 2018

The increased threat of faecal pollution in recent years and the high priority of protecting human health by the government led to the initiation of a national microbial monitoring programme for surface water in South Africa. According to the design of the programme, monitoring sites had to be selected in order to assess the status and trends of faecal pollution. Issues of efficiency and cost-effectiveness dictated that the monitoring would focus on areas with the greatest risk. A method based on relevant land and water use information (e.g. level of water supply and sanitation, agricultural practices, surface runoff, recreation) was developed for the selection and prioritization of these areas. A measurement scale was described for all sensitive uses to ensure the objectivity of the selection process. For the prioritization purposes, weights were assigned to the different uses according to their impact. This was done by means of the simple multi-attribute rating technique (SMART). The method was found to be useful for the identification of high-risk areas but the availability and reliability of the data are some of the major constraints.
Process audit and asset assessment using on-line instrumentation
Authors: Watts John B. , Cavenor-Shaw Andrew R.
Published: May 2018

The traditional approach to assessing the performance of an Activated Sludge Plant (ASP) is to conduct an expensive and often labour intensive through-plant sampling survey. The results from this kind of survey do not give an accurate picture of the plant performance in real time, and often can be ruined by inaccurate or spoilt analytical results.

A new approach to Process Audits has been developed based on on-line instrumentation and remote monitoring. The key equipment required to dynamically monitor the ASP performance is the MSL Respirometer which is used to measure organic loading, required retention time and aeration system requirements.

Auto-cleaning, auto-calibrating Dissolved Oxygen sensors are used in conjunction with a Respirometer to assess the aeration system efficiency (actual Kla value) and the maximum oxygen demand (OUR) which can be sustained by the plant. Ultrasonic flow meters are used to determine flow splits and actual plant retention time which is compared to the required retention time measured by the Respirometer. Mixed Liquor Suspended Solids (MLSS) profiles are monitored continuously using a self-cleaning optical sensor, which is used along with Respirometric readings to measure the effect of poor wastage regimes and ingress of inert solids. On-line ammonia, phosphate and nitrate monitors can be used to give information on the diurnal variation of nutrients, related to the loading on the plant. As well as the normal plant operation, the effect of shock loads, storm conditions and sludge liquor returns can all be assessed.

All instruments are linked via a serial communications loop to a modern and telephone line. The plant is monitored remotely, making it an unobtrusive survey allowing operations to continue as normal and giving a true picture of the plant performance.

This approach has been used on several UK sewage treatment works and has proven to be a cost-effective method. In one case a proposed capital spend on final settlement tanks was shown to be unnecessary; in another case the plant was shown to be unable to support a nitrifying biomass.
Improved detection and vital staining of Cryptosporidium and Giardia with flow cytometry
Authors: Medema G. J. , Schets F. M. , Ketelaars H. , Boschman G.
Published: May 2018

Flow cytometry with fluorescence activated cell sorting (FACS) was used to purify Cryptosporidium (oo)cysts and Giardia cysts from water. With this purification step Cryptosporidium and Giardia were found in a higher percentage of the samples and significantly higher Giardia concentrations were detected in these positive samples. Because FACS removed most of the debris from the concentrated water sample, the microscopic preparations could be examined more rapidly for the presence of (oo)cysts and the morphological characteristics of the (oo)cysts could be interpreted more unambiguously than with the conventional immunofluorescence microscopy method. The use of FACS made it possible to apply PI-staining on environmental samples to determine the fraction of dead (oo)cysts. Sample processing did not appear to influence the PI-staining characteristics of the Cryptosporidium (oo)cysts, but did increase the percentage of PI-positive Giardia cysts. This suggests that this protocol can be used for determining the percentage of dead Cryptosporidium oocysts in environmental samples. Analysis of environmental samples suggests that reservoir storage increases the percentage of PI-positive (dead) oocysts.
Detection and survival of pathogens during two-stage thermophilic/mesophilic anaerobic treatment of suspended organic waste
Authors: Burtscher C. , Fall P. A. , Christ O. , Wilderer P. A. , Wuertz S.
Published: May 2018

The food-borne pathogens Salmonella typhimurium and Listeria monocytogenes were effectively eliminated from suspended organic waste during the thermophilic (55°C) phase of a two-stage thermophilic/mesophilic anaerobic reactor. The feasibility of PCR technology was evaluated in order to improve the speed of detection and reduce the effort involved in detecting the presence of a range of pathogenic bacteria. Our results show direct extraction of nucleic acids followed by purification and PCR to be a promising method that will enable the rapid verification of hygienic performance during waste treatment.
On-line nitrification inhibition monitoring using immobilised bacteria
Authors: Hayes E. , Upton J. , Batts R. , Pickin S.
Published: May 2018

As wastewater treatment plant managers are required to meet increasingly stringent standards the focus on processes has shifted more and more towards assessing the treatability of a waste. Many substances discharged to effluent treatment plants may inhibit the process of nitrification. Traditional testing methods are costly and cannot be used for real time control which has led to the development of the AmtoxTM system.

AmtoxTM uses a culture of immobilised nitrifying bacteria in a system maintained at 30°C. This enhances the rate of nitrification and gives an early warning of toxicity. This paper presents data comparing Amtox with the conventional nitrification inhibition test method and describes the instrument designed for laboratory use. Preliminary data for the on-line Amtox system are also included: these data provide the first, direct, continuous measure of nitrification inhibition on an effluent treatment plant.