bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of NTA on the Fate of Heavy Metals in Sediments
Authors: Lo S. L. , Huang L. J.
Published: May 2018

Sodium tripolyphosphate (STPP), which is widely used as a builder in synthetic detergents, was found as one of the major factors of eutrophication in rivers and lakes. Many countries have used nitrilotriacetate (NTA) in detergents to replace STPP, but it induced another pollution problem. Because NTA is an effective chelating agent, it will dissolve heavy metals from the sediments and affect the fate of metal species in rivers. The purpose of this study is to investigate the effect of the mobilization of heavy metals from sediments by NTA. The experimental results indicated that NTA increases the mobilization of heavy metals as the shaking time increases and reaches an apparent equilibrium concentration after 24–48 hours. Typical results show that using 20mg/l of NTA and shaking time of 6 days, the fraction mobilized is about 8 to 15% for Cu, 1 to 7% for Zn, 7 to 10% for Pb, and 7 to 30% for Cd. Hardness of the water affects the formation of heavy metal-NTA complexes significantly. Biodegradation of the trisodium salt of NTA starts after 6–9 days with degradation time of the metal-NTA complexes decreasing in the order of Cu > Cd > Zn > Pb > Ca.
Convective Transport of Chemicals across a Sediment-Water Interface
Authors: Dahl M. , Dunning C. P. , Green T.
Published: May 2018

The transport of dissolved chemicals across a horizontal interface between surface water and a saturated porous medium, associated with an unstable density gradient across the interface, is studied experimentally. Particular attention is paid to the starting conditions (i.e. the rate at which the density difference increases), and to the effect of changes in the density difference once the convective flow pattern has been established. The goal is a general flux law for any time variation of the density difference. Three significant observations are discussed. First, greater masses added to the overlying water results in larger density instabilities that drive greater fluxes. Second, the rate of addition of the mass affects both the peak density gradient and the long-term flux across the interface. Slower rates of addition result in greater variability in the resulting flux. Third, throughout all experiments, the ratios of final fluxes for different masses are similar, regardless of addition time.
The Impact of Christchurch City (New Zealand) on Heavy Metals in Sediments of the Avon-Heathcote Estuary
Authors: Deely J.
Published: May 2018

This paper reviews heavy metal (Cr, Cu, Fe, Mn, Ni, Pb, Zn) content in the clay fraction (<4 µm) of soils, suspended sediment, surface sediment, and core sediment associated with the Avon-Heathcote Estuary. Despite the estuary's low clay content (<10%), significant metal and organic matter trends are apparent in the clay fraction, which are less obvious in parallel studies of silt (4-63 µm), sand (>63 µm), and total sediment. Clay fraction depth profiles record periods of high heavy metal input in sediments deposited slowly but not in sediments deposited rapidly. Most metals, organic matter, mud, and Fe oxides accumulate in a broad anaerobic band across the western area of the estuary. Organic matter and metal concentrations are increasing towards the surface in depth profiles of this zone. This pattern combined with the increasingly eutrophic state of the estuary suggests more serious heavy metal contamination in the future.
Lake Michigan Sediment Contamination from 73 Years of Trap and Skeet Shooting
Authors: Pott D. B. , Shephard B. K. , Modi A.
Published: May 2018

This study assessed sediment and soil contamination at the site of the former Lincoln Park Gun Club located on the shore of Lake Michigan in Chicago. Between 1918 and 1991 a shooting organization utilized the site for trap and skeet shooting, discharging tons of lead shot and clay targets to Lake Michigan. The targets were primarily dolomitic limestone with a petroleum pitch binder containing polynuclear aromatic hydrocarbons (PAH). This study measured vertical and lateral extent of lead and PAH contamination in site soils, near-shore sediments, lake water and ground water. Statistically significant correlations were found between the following pairs of Lake Michigan sediment analyses: TCLP lead and total lead; TCLP lead and supernatant lead; and supernatant lead and total lead. No significant correlations were found between any of the lead chemical analyses and lead shot counts. Microbial bioassays performed on sediment extracts found no measurable toxicity.
Future Directions in Instrumentation, Control and Automation in the Water and Wastewater Industry
Authors: Vassos Troy D.
Published: May 2018

The need to optimize treatment plant performance and to meet increasingly stringent effluent criteria are two key factors affecting future development of instrumentation, control and automation (ICA) applications in the water and wastewater industry. Two case studies are presented which highlight the need for dynamic modelling and simulation software to assist operations staff in developing effective instrumentation control strategies, and to provide a training environment for the evaluation of such strategies. One of the limiting factors to date in realizing the potential benefits of ICA has been the inability to adequately interpret the large number of existing instrumentation inputs available at treatment facilities. The number of inputs can exceed the number of control loops by up to three orders of magnitude. The integration of dynamic modelling and expert system software is seen to facilitate the interpretation of real-time data, allowing both quantitative (instrumented) and qualitative (operator input) information to be integrated for process control. Improvements in sensor reliability and performance, and the development of biological monitoring sensors and control algorithms are also discussed.
Flow and Sediment Movement Monitoring in Large Sewers
Authors: Ashley R. M. , Longair I. M. , Wotherspoon D. J. J. , Kirby K.
Published: May 2018

The development of more precise computer models for the simulation of the performance of sewerage systems and for management in real-time necessitates the acquisition of more precise data. Existing portable systems for the in-situ measurement of velocity in sewers as commonly used for model development have limited applicability to larger sized sewers (>1200mm). When considered together with the emerging need to monitor the behaviour of sediments in sewers, this lack of instrumentation available to observe detailed velocity gradients in the larger sewers, where sedimentation is most likely to occur, is a severe constraint. A programme of research studying sediment movements in the sewers in Dundee has led to the development of ultrasonic systems for the measurement of three dimensional velocity distributions in large sewers, and sonar systems for the monitoring of bed erosion at points within the sewer network. Data obtained from these systems has contributed to the development of a new cohesive sediment erosion model for sewers.
Dynamic Modelling of an ASP Sewage Works – A Case Study
Authors: Stokes L. , Takács I. , Watson B. , Watts J. B.
Published: May 2018

The application of the GPS-X computer simulation of sewage works to a 55 Ml/d dry weather flow (dwf) nitrifying activated sludge plant (ASP) is described. The role of simulation and the features of a simulation package as required by the end user are outlined. The plant processes, operation, performance and the instrumentation are described. The on- line measurements are collected and displayed by the GFX monitoring system which acts as input/output stage for GPS-X. The simulation package uses the IAWPRC model with modifications based on Dold (1990). The features of the model, its calibration and successful verification are described.
Reduced Order Models for On-Line Parameter Identification of the Activated Sludge Process
Authors: Jeppsson U. , Olsson G.
Published: May 2018

A reduced order dynamic model for an activated sludge process performing carbonaceous removal, nitrification, and denitrification is proposed. Based on directly measurable real time data - by methods available today - all model parameters are identified on-line. A simplified extended Kalman filter is used for the actual identification. Verification of the results is based on computer simulations of the IAWQ Activated Sludge Model No. 1. The reduced order model presented herein may serve as a tool for predicting the dynamic behaviour of a biological wastewater treatment plant since the parameters under varying operating conditions can be tracked on-line. The model parameters are effectively estimated even when the measurements are affected by a significant level of noise. The model is aimed for operation and control purposes as an integral part of a hierarchical control structure.
Simulation of a Strategy to Start up Nitrification at Bromma Sewage Plant Using a Model Based on the IAWPRC Model No. 1
Authors: Finnson Anders
Published: May 2018

At the Bromma sewage plant in Stockholm a project is being carried out where the aim is to elaborate different operational strategies for the plant. One of the strategies, the seeding of nitrificating bacteria from one line to other lines in the activated sludge process, was simulated with the assistance of the Danish computer program EFOR. The simulations showed that it was possible to use EFOR for this kind of simulation and that the seeding effect which was achieved in the sewage plant was of relatively small importance for reducing the NH4-N in the effluent water.
Real-Time Control of Wastewater Treatment Systems Using ORP
Authors: Wareham David G. , Hall Kenneth J. , Mavinic Donald S.
Published: May 2018

Oxidation-Reduction Potential (ORP) can be used as a process control parameter for real-time automated control of batch sewage treatment systems. Results suggest that ORP has great potential for the control of anoxic sequences, since the distinct breakpoint in the ORP-time curve correlates to the disappearance of nitrates.
Measurement of Trihalomethanes (THM) in Drinking Water with an Automatic THM Analyzer
Authors: Kawakami K. , Tanaka Y. , Zaitsu Y. , Hoshikawa H.
Published: May 2018

For waterworks the most fundamental subject is to maintain the safety of drinking water. It has become important every year to monitor the concentrations of trihalomethanes (THM). We developed a new automatic THM analyzer based on fluorometry with membrane separation, and investigated a correlation between the gas Chromatographic method and our THM analyzing method on drinking waters at 10 cities in Japan. The investigation resulted in good correlation (r=0.9807) between both methods. Good results were obtained when continuous measurements of THM in drinking water were performed by the analyzer. Consequently, it was found that the present analyzer could measure THM in drinking waters simply, rapidly, with good precision and could be applied to continuous monitoring of THM.
CHEMODYNAMICS OF TRACE POLLUTANTS DURING SNOWMELT ON ROOF AND STREET SURFACES
Authors: Daub J. , Förster J. , Herrmann R. , Robien A. , Striebel T.
Published: May 2018

In order to investigate the concentration levels and chemodynamic behaviour of organic micropollutants and heavy metals in snowmelt runoff from urban sealed surfaces, meltwater was sampled from one street :and four different roof catchments. Apart from peak concentrations of suspended solids during short intense street runoff from rain, concentrations of suspended solids in snowmelt runoff are two to fivefold higher than in rain runoff. However, the specific metal concentrations in suspended solids of snowmelt (except Zn) are lower than in suspended solids of rainwater runoff. This partly compensates the higher concentration of suspended solids. There are no distinct differences in concentrations of heavy metals between rain and meltwater runoff willi the exception of dissolved Cd; its concentrations are increased when high concentrations of macro ions are present. We explain high concentrations of PAH with a molecular weight of 202 or less in snowmelt with longer equilibration times available during melting than during rain runoff. An enhancement of solubility by DOC seems to be likely. The physical and chemical properties of various roof surfaces greatly influence the temporal variation of PAH concentrations during snowmelt runoff.
THE ACTIFLO® PROCESS: A HIGHLY COMPACT AND EFFICIENT PROCESS TO PREVENT WATER POLLUTION BY STORMWATER FLOWS
Authors: Guibelin E. , Delsalle F. , Binot P.
Published: May 2018

Prevention of pollution due to stormwater flow is the new challenge in water pollution control. With a view to avoid heavy investments in buffering capacity, a new process called Actiflo® has been developed. This process allows an upflow velocity of 130 m/h over the lamella, which means a total area of only 0.03 m2 per m3/h of influent capacity. Under these conditions, a reduction of 80% of the TSS is achieved using about 60g/m3 of ferric chloride and 0.8 g/m3 of polyelectrolyte. High compactness and quick start up of the process allows one to set up the Actiflo® in any place where prevention of stormwater flow is suitable, with low operating and investment costs compared to conventional solutions.
OPTIMIZING OPERATION OF WASTEWATER TREATMENT PLANTS BY OFFLINE AND ONLINE COMPUTER SIMULATION
Authors: Otterpohl Ralf , Rolfs Thomas , Londong Jörg
Published: May 2018

Computer simulation of activated sludge plant for nitrogen removal has become a reliable tool to predict the behaviour of the plant Models including biological phosphorus removal still require some practical experience but they should be available soon. This will offer an even wider range than today's work with nitrogen removal. One major benefit of computer simulation of wastewater treatment plants (WTP) is the optimization of operation. This can be done offline if hydrographs of a plant are collected and computer work is done with “historical” analysis. With online simulation the system is fed with hydrographs up to the actual time. Prognosis can be done from the moment of the computer work based on usual hydrographs. The work of the authors shows how accuratly a treatment plant can be described, when many parameters are measured and available as hydrographs. A very careful description of all details of the special plant is essential, requiring a flexible simulation tool. Based on the accurate simulation a wide range of operational decisions can be evaluated. It was possible to demonstrate that the overall efficiency in nitrogen removal and energy consumption of ml activated sludge plant can be improved.
BIOLOGICAL TREATABILITY OF AMINE LADEN REFINERY WASTEWATER
Authors: Chong Nyuk-Min
Published: May 2018

Mono- and Di- hydroxyl amines are used in the desulfuration processes for refined petroleum products. The refinery wastewater treatment plant may be shocked by amine laden wastewater periodically, bringing operation difficulties to the biological treatment units. Data on the treatability, shock load behaviour and on long term system stability of biological treatment of amines are therefore required. Shake-flask test results showed that pure diethanol amine and diisopropanol amines have characteristics of persistent compounds. Each of the two compounds has a prolonged lag time when first inoculated with indigenous activated sludge. Acclimated activated sludge in a continuous flow reactor treated a feed of ethanol amine with a 93 percent COD removal and a 98 percent nitrification, but the system was unstable because amine caused a bulking sludge. By physical retention of the activated sludge, 550 mg/l influent COD of amines was treated to m1 average 50 mg/l effluent COD. Sludge yield was approximately 0.26 mg MLSS per mg COD. The activated sludge system withstood a chm1ge of feed to a real refinery wastewater laden with the; amine. A mean cell residence time above five (5) days should be maintained for safe treatment of; amine.
A HYDROLYSIS/THICKENING/FILTRATION PROCESS FOR THE TREATMENT OF WASTE ACTIVATED SLUDGE
Authors: Woodard Steven E. , Wukasch Ronald F.
Published: May 2018

A process has been developed for reducing both the mass and volume of waste activated sludge generated by the biological treatment of a pharmaceutical wastewater. As a result of the mixture rule, the sludge is classified as a hazardous waste. Thus, treatment and disposal have traditionally been very costly. This study focused on optimizing an engineered hydrolysis operation in terms of solids reduction, environmental impact, practicality and cost. Dewaterability screening studies were also conducted in an attempt to transform the residual solids into a readily filterable material.

The resultant hydrolysis/thickening/filtration process begins with room temperature sludge acidification using sulfuric acid. This results in 50 to 60 percent solubilization of suspended solids, thus sharply reducing the mass of solids to be handled. Also, carbon dioxide is liberated during the reaction phase, enabling solids separation and thickening to occur via flotation. Subnatant hydrolysate can then be recycled to enhance solids solubilization. Once properly conditioned with acid and cationic polymer, the residual solids are readily pressure filtered to cake dryness in excess of 50% solids. Results of laboratory studies indicate that the overall process is capable of substantially reducing sludge cake production.
The Effects of Environmental Changes Caused by Human Activities on the Biological Communities of the River Don (Azov Sea Basin)
Authors: Volovik S. P.
Published: May 2018

The Don River is the main river system in the Azov Sea Basin. The average water flow is about 28 km3 per year. The biota of the river system is characterized by a rich vegetation and animal life including aquatic organisms. Great changes in the environment of the River Don have been observed since the period 1930 - 1960, when large numbers of dams were constructed, diverting water flow for heavy industry, energy production, agriculture and other uses. Simultaneously, water pollution increased. As a consequence, the biota of the region has been impacted negatively. Some of the detrimental effects are the decreased reproduction of commercially important fish species, and the much reduced catches of these fish. This report reviews the changes that have occurred in the ecosystem of the River Don Basin.
The Population Explosion of the Amphipod Corophium curvispinum in the Dutch Lower Rhine
Authors: Paffen B. G. P. , van den Brink F. W. B. , van der Velde G. , bij de Vaate A.
Published: May 2018

Densities of Corophium curvispinum Sars, 1895 collected from stones at two localities (Lobith and Nijmegen) in the Lower Rhine at a water depth of 2-3 metres during 1992 were found to be very high. At both localities Corophium was the dominant macroinvertebrate, outnumbering all other species by many times. The population of the zebra mussel (Dreissena polymorpha) was further reduced in 1992, because all stones are covered with a 1-4 cm thick layer of muddy tubes of Corophium. Muddy material including macroinvertebrates fixed by Corophium was found to be 61-609 g DW m-2 and 9-99 g AFDW m-2 stone surface.
KINETICS OF THE AQUEOUS ALKALINE HOMOGENOUS HYDROLYSIS OF HIGH EXPLOSIVE 1, 3,5,7-TETRAAZA- 1, 3,5,7-TETRANITROCYCLOOCTANE (HMX)
Authors: Heilmann Harro M. , Stenstrom Michael K. , Hesselmann Rolf P. X. , Wiesmann Udo
Published: May 2018

In order to get basic data for the design of a novel treatment scheme for high explosives we investigated the kinetics for the aqueous alkaline hydrolysis of 1,3,5,7-tetraaza-1,3,5,7-tetranitrocyclooctane (HMX) and the temperature dependence of the rate constants. We used an HPLC procedure for the analysis of HMX. All experimental data could be fit accurately to a pseudo first-order rate equation and subsequent calculation of second-order rate constants was also precise. Temperature dependence could be modeled with the Arrhenius equation. An increase of 10°C led to an average increase in the second-order rate constants by the 3.16 fold. The activation energy of the second-order reaction was determined to be 111.9 ±0.76 kJ·moJ‒1. We found the alkaline hydrolysis to be rapid (less than 2.5% of the initial HMX-concentration left after 100 minutes) at base concentrations of 23 mmol oH‒/L and elevated temperatures between 60 and 80°C.
Environmental Risks of Inland Water Transport
Authors: van Hengel W. , Kruitwagen P. G.
Published: May 2018

The objective of this study is to determine the environmental risks caused by inland water transport. A method has been developed to determine the accident-rate with environmental-hazardous goods during transportation over water, and to estimate the effects (risks) of such accidents on the environment. With the results of the study the present environmental risks of inland water transport are evaluated, as well as some proposed measures, intended to improve safety. It turns out that accidents upstream of Lobith dominate the environmental Immission risks at the Dutch region of the river Rhine. A comparison with static industrial plants is still subject of further study.
Development of a Propagation Model to Determine the Spread of Accidental Pollution in Rivers
Authors: Bildstein O. , Vançon J. P.
Published: May 2018

Pollutant spread in rivers is affected by numerous complicated phenomena, and only through modelling such spread is it possible to predict the concentration of solutes at strategic points along the river in case of accidental water pollution and to set up appropriate procedures to limit undesirable effects. The BRGM (Bureau de Recherches Géologiques et Minières) has developed such a model to simulate the behaviour of any pollutant spilled into the surface water network and has integrated it in the “SeauS” (SOS Water) software package designed by the BRGM to help reach a decision in matters of water protection. The model is based on the “mixing cells” method which has a high execution speed and is suitable for simulating the various flow mechanisms occurring in rivers; i.e. advection, diffusion, connected networks, interactions between the main flow and areas of stagnant water or groundwater, etc. Once its numerical performance had been proved, the model was tested in schematic cases and its results compared with analytical solutions. In each case the model showed its ability to represent the natural phenomena very well.
The “Dreissena-Monitor” – First Results on the Application of this Biological Early Warning System in the Continuous Monitoring of Water Quality
Authors: Borcherding Jost , Volpers Markus
Published: May 2018

The “Dreissena-Monitor” is a biological early warning system used in the continuous monitoring of water quality. The system is based on a computer assessment of valve movements in two groups of up to 42 zebra mussels (Dreissena polymorpha). Every 5 minutes, the percentage of open mussels and the average number of valve movements per mussel are calculated to describe the activity behaviour of the mussels. Rapid changes in both parameters normally reflect the onset of stress. More than 5½ years of experience in the continuous monitoring of water quality have revealed (1) that the “Dreissena-Monitor” is suited to large rivers like the Rhine as well as small rivers like the Erft or Ruhr, (2) that a lack of technical interruptions guarantees reliable, unattended operation, (3) that normally less than 3 hours of weekly maintenance are required, (4) that the validity check of the primary measurements was capable of identifying dead mussels and poorly aligned measurement components, (5) that the system can operate under unfavourable conditions (e.g. temperatures below 5° C), (6) that mortality rates were low and correlated positively with temperature, and (7) that the alarm thresholds provided a high degree of statistical security.
Impact of Heavy Metals on Benthic Oligochaete Communities in the River Ill and Its Tributaries
Authors: Rosso A. , Lafont M. , Exinger A.
Published: May 2018

The aim of this research is to describe the impact of heavy metals contaminating sediments on oligochaete communities. Sediments were collected three times (June, August, October 1991) for chemical and biological analyses in 15 sites situated in the river I11 and its tributaries (Rhine Basin, France). The sediments are characterized by high contents of heavy metals, mainly Hg, Cu, Cr, Pb, Zn from below the city of Mulhouse. The majority of sediments are heavily loaded with organic matter and organic micropollutants are also present. Oligochaete communities are rich in species. However five species only, considered as pollution-tolerant or opportunist, are significantly present and abundant. The percentages of Tubificidae without hair setae are positively related to heavy metal contents of the sediments, and the percentages of Tubificidae with hair setae are negatively related. Several species such as N. communis, N. barbata, D. digitata and Bothrioneurum sp. are considered as tolerant to heavy metals; on the contrary L. claparedeanus, L. udekemianus, Stylodrilus sp. and S. josinae are considered as intolerant. The reproductive strategy of oligochaetes in contaminated areas and the role of organic matter are discussed. Several recommendations are given for the rehabilitation of the investigated sites.
Bed Degradation – Nature, Causes, Countermeasures
Authors: Gölz E.
Published: May 2018

Bed degradation is the dominant morphological process along the freely flowing river Rhine between Iffezheim and the German-Dutch border with degradation rates varying between 5 and 50 mm year1. As a continuing bed degradation may cause severe economical and ecological damage, nature, causes and extent of degradation have been studied using two diving bell watercraft. Additional petrographic examinations of bed sediments as well as bed load measurements have revealed that bed degradation of the Lower Rhine is mainly caused by bed load deficits due to the specific morphotectonic conditions as well as anthropogenic interference, especially impounding of the big tributaries. Low degradation rates are a precondition for certain rehabilitation measures as, e.g. restoring of flood plain areas and reactivation of abandoned channels and meander belts. Therefore stabilisation of the river bed is an important task for ecological river engineering. For the river Rhine a stabilisation strategy is suggested combining conventional river training works, maintenance measures and artificial bed load supply.
Denitrification in Constructed Wastewater Wetlands Receiving High Concentrations of Nitrate
Authors: van Oostrom A. J. , Russell J. M.
Published: May 2018

Nitrogen removal in constructed wetlands receiving nitrified wastewaters can be limited by insufficient organic carbon for denitrification. Experiments were undertaken to determine the importance of decaying plant material, in a floating mat of the wetland plant Glyceria maxima, as a source of organic carbon and anoxic sites for denitrification in surface-flow wetlands. In the laboratory, a mat of G. maxima floating on a nitrified meat processing effluent (87 g m−3 NO3-N) promoted a denitrification rate of 3.8 g m−2 day−1 at 20°C. Under strictly anoxic conditions, and where G. maxima leaves were the sole carbon source for denitrification, about 2.1 g of the biomass carbon was consumed for every gram of NO3−N removed. The biomass carbon produced by G. maxima growing on meat processing effluent has the potential to sustain a denitrification rate of 2.4 - 4.8 g m−2 day−1. In a pilot-scale wetland completely covered with G. maxima and receiving a nitrified meat processing effluent, nitrogen removal rates ranged from 0.6 g m−2 day−1 in winter to 3.0 g m−2 day−1 in summer. The floating plant mat and the sediment are the most active denitrification sites in the wetland. Nitrogen removal may potentially be enhanced by improving the contact between the wastewater and the decaying plant material.
Nitrogen Transformations in Gravel Bed Hydroponic Beds Used as a Tertiary Treatment Stage for Sewage Effluents
Authors: Williams J. B. , May E. , Ford M. G. , Butler J. E.
Published: May 2018

The potential nitrogen transforming activities of bacteria were measured in the water and biofilms of a Gravel Bed Hydroponic (GBH) sewage treatment system. Within the GBH system, the organic matter and biofilms create complex partitioned micro-environments which promote nitrogen cycling. Biofilms attached to the rhizomes of Phragmites auslralis support higher potential rates of nitrogen transformations per unit surface area than those attached to gravel. Comparison of the transforming activities of the bacteria with the environmental conditions within the bulk water identified the effectors of ammonification, nitrification and denitrification. Rhizome and gravel biofilms respond differently to changes in their environment Nitrogen transformation potential exists throughout the bed, but whereas the potential ammonification and nitrification activities are evenly distributed, those for denitrification are greatest at the top of the bed where the availability of carbon and the local redox conditions promote microbial production of gaseous nitrogen. Thus, the success of GBH beds in treating effluents can, in part, be explained by a stimulation of nitrification/denitrification activities on the surface of the rhizomes. The nature of the effluent will depend on the balance between the rates of these two processes.
Functions of Macrophytes in Constructed Wetlands
Authors: Brix Hans
Published: May 2018

Macrophytes have several intrinsic properties that makes them an indispensable component of constructed wetlands. The most important functions of the macrophytes in relation to the treatment of wastewater are the physical effects brought about by the presence of the plants. The macrophytes stabilise the surface of the beds, provide good conditions for physical filtration, prevent vertical flow systems from clogging, insulate against frost during winter, and provide a huge surface area for attached microbial growth. Contrary to earlier belief, the growth of macrophytes does not increase the hydraulic conductivity of the substrate in soil-based subsurface flow constructed wetlands. The metabolism of the macrophytes affects the treatment processes to different extents depending on the design of the constructed wetland. Plant uptake of nutrients is only of quantitative importance in low-loaded systems (surface flow systems). Macrophyte-mediated transfer of oxygen to the rhizosphere by leakage from roots increases aerobic degradation of organic matter and nitrification. The macrophytes have additional site-specific values by providing habitat for wildlife and making wastewater treatment systems aesthetically pleasing.
Treatment of Dairy Farm Wastewaters in Horizontal and Up-Flow Gravel-Bed Constructed Wetlands
Authors: Tanner Chris C.
Published: May 2018

The treatment performance of four horizontal and two up-flow pilot-scale constructed wetlands planted with Schoenoplectus validus were investigated over a 20 month period (two winters and two summers) treating dairy parlour wastewaters at a range of loading rates. Removal of BOD.TN and TP were positively correlated with retention time. Reduction of BOD (70 - 90%) and SS (40 - 90%) in relation to loading rate were similar in both flow formats. The horizontal-flow wetlands showed 40 - 90 % reduction of TN and 30 - 80 % reduction of TP. The up-flow wetlands showed reduced levels of TN and TP removal, particularly when the loading rates were increased during the latter 5 months of the trial. Results are compared with those of other published studies of horizontal and upflow wetlands treating NH4-N rich organic wastewaters.
The Influence of Water Regime on the Performance of Aquatic Plants
Authors: Rea Naomi , Ganf George G.
Published: May 2018

Experimental results demonstrate bow small differences in depth and water regime have a significant affect on the accumulation and allocation of nutrients and biomass. Because the performance of aquatic plants depends on these factors, an understanding of their influence is essential to ensure that systems function at their full potential. The responses differed for two emergent species, indicating that within this morphological category, optimal performance will fall at different locations across a depth or water regime gradient. The performance of one species was unaffected by growth in mixture, whereas the other performed better in deep water and worse in shallow.
TERTIARY TREATMENT OF URBAN WASTEWATER BY CROSS FLOW MICROFILTRATION
Authors: Pouet M.-F. , Grasmick A. , Homer F. , Nauleau F. , Cornier J. C.
Published: May 2018

Using cross flow microfiltration as a tertiary treatment would make the treatment reliable and achieve virtually a total disinfection. However, the use of the membrane techniques is IimiIed because of the material fouling. Our results show that the fouling mechanisms depend on the choice of the secondary upstream process. The quality of the effluent and the permeaIe flux obtained are very different if the sewage has been treated by a biological or by a physico-chemical process. The operating conditions of these processes have also an influence on the variations of the membrane permeability. In particular we have observed the importance of the load in the case of an activated sludge process and the role of the coagulant dose in the case of a physico-chemical process. The supracolloidal fraction of the suspensions seems to be one of the main fouling reasons.
Coupling Wetland Treatment to Land Treatment: an Innovative Method for Nitrogen Stripping?
Authors: Bryce Cooper A.
Published: May 2018

The ability of two small wetlands to remove added nitrate was studied as part of a wider investigation into the feasibility of using a combined forest irrigation-wetland treatment system to meet strict receiving water limits. In laboratory microcosm experiments, wetland sediments removed nitrate at rates between 0.019 - 0.609 g m−2 d−1, with rates being dependent upon nitrate loading and the vegetation that supplied the decaying organic matter (Typha orientalis > Carex spp. > Azollafiliculoides). Denitrification could account for between 32 - 100% of the observed nitrate loss, indicating that in some microcosms other nitrate removal processes were operating. Additions of bromide (a conservative tracer) and nitrate to the two wetlands demonstrated more rapid nitrate loss in a Typha stand (decay coefficient, ke = 4.44 d−1) compared to loss in an Azolla pond (ke = 1.1 d−1). The time course of bromide concentration at the wetland outlets, and its distribution within the wetlands, showed the presence of preferential flow paths and “dead” zones. This non-uniform flow is a common characteristic of wetlands and, in this case, may exert a major control on the scheme's overall nitrate removal efficiency.
OPTIMISATION OF W ASTEW A TER TREATMENT PLANTS BY MEANS OF COMPUTER MODELS
Authors: Dupont René , Sinkjær Ole
Published: May 2018

The objective of the work presented is to demonstrate how computer based models can be used to improve the effluent quality from wastewater treatment plants by optimisation of the operation. The investigation was carried out in connection with pilot plant investigations at Damhusllen Wastewater Treatment Plant in order to establish the design basis for upgrading the treatment plants in the city of Copenhagen.

Calibration of the model was done with thorough characterisation of the wastewater and the activated sludge as the primary calibration tool. Special attention was paid to the nitrification process, which by previous investigations was shown to be occasionally inhibited. Model constants for the nitrification process were detennined from experiments. Default constants were used for nearly all other constants. The pilot plant was optimized with the calibrated model. Different operational strategies for improvement of the denitrification process were tested. The denitrification process was operated relatively poorly at the time for the optimisation.

The calibration showed that it was possible to calibrate the model using the characterization of the wastewater and the activated sludge as the primary calibration tool. Further it was shown that the calihrated model could be used as a tool for optimising the operation of the pilot plant. The suggested operation correlated well with the practical realisable operation.
Preservation and Management of Natural Wetlands in the South Australian Murray Valley
Authors: Jensen Anne , Nicolson Clare , Carter Jason
Published: May 2018

The impact of river regulation has been to reduce flood frequencies on the Murray floodplain below Mildura. The lower frequency of inundation of wetlands reduces the number of successful breeding and regeneration events in floodplain biota, causing a decline in the health and vigour of many floodplain plants and animals. The potential for rehabilitation of floodplain wetlands through increased flushing flows has been demonstrated. The ultimate aim is to enhance habitat value and achieve maximum biodiversity. Future opportunities are identified for hydrological manipulation within river operating strategies to extend beneficial management on a floodplain scale to improve wetland habitat. These can be combined with rehabilitation techniques such as specific water allocations, grazing controls and physical works on individual wetlands to ensure preservation and sustainable management of natural wetlands along the South Australian Murray Valley. Results so far indicate that successful restoration of the wetlands will take a number of flushing events and will be dependent primarily on the acceleration and protection of natural regeneration processes.
The Hungarian water and wastewater industry: past, present and future
Authors: Newbry Brooks W.
Published: May 2018

The levels of service provided by the Hungarian water and wastewater industry to its customers are below those provided in most of western Europe. The situation in Hungary is typical of much of eastern Europe. A team of Hungarian and western engineers, financial experts and regulatory specialists examined the water and wastewater industry and prepared a restructuring framework to assist in guiding development. Key recommendations for restructuring are that private sector disciplines should be introduced for development and operation of infrastructure; that clear commercial, financial and environmental regulatory measures should be put in place; and that clear priorities should be established for infrastructure development programmes. Hungarian water and wastewater industry professionals were intimately involved in developing the framework and are currently leading its implementation. This work, supported by the British Know How Fund, has direct application to other parts of central and eastern Europe. It demonstrates how a strong international partnership can facilitate water and wastewater industry development.
Pollution prevention: a winning strategy for the protection of the environment
Authors: Lindstrom K. P. , Renescu Adriana
Published: May 2018

This case study presents the development and implementation of the County Sanitation Districts of Orange County (Districts) Pollution Prevention Program (P3) aimed at reducing the environmental release of pollutants. The P3 has been integrated in the Districts' environmental management program and incorporates the goals of the Districts' 30-year Master Plan called 2020 Vision. The Districts take a multi-media approach to environmental protection giving equal importance to emissions to air, water or the land. The Districts' P3 efforts, applied in combination with an aggressive Source Control Program, has resulted in significant reductions in heavy metals and other pollutant discharges to the environment.

The P3 is a major element of the Districts' Source Control Program. During the past seven years, pollution prevention (the management of waste generation or reduction of waste before it is generated) has proven to be the most effective strategy to protect the environment. The Program has resulted in reductions in influent loadings of heavy metals and other pollutants of concern, and an improving record of compliance by major industrial dischargers. The reduction in metals and other pollutants has resulted in quantifiable improvements in environmental conditions in the marine environment (in the vicinity of the discharge) several miles offshore near the ocean outfall, in reduced air emissions from the treatment plants, and in the concentrations of heavy metals in the residual biosolids produced for recycling. Long-term monitoring data shows improvements in effluent toxicity (as measured by fish survival), reductions in the concentrations of metals in sediments around the ocean outfall and long-term gradual improvements in biological conditions as measured by the number of species of benthic invertebrates. Data on the trends for each of these and other conditions, are presented along with the specific methods employed to achieve the reductions from industrial dischargers.

The successes of P3 were acknowledged by the United States Environmental Protection Agency (EPA), which awarded the Districts the Administrator's national 1992 Pollution Prevention Achievement Award.
The effects of external carbon loading on nitrogen removal in sequencing batch reactors
Authors: Tam N. F. Y. , Leung G. L. W. , Wong Y. S.
Published: May 2018

A bench-scale study was undertaken to examine the effects of easily biodegradable organic carbon substrate on denitrification reaction and overall nitrogen removal from domestic wastewater under a modified sequencing batch reactor (SBR) system. The operation strategy of the SBR consisted of 0.75 h FILL, 8 h REACT separated into 4 h aerobic, 3 h anoxic and 1 h aerobic stages, 1.5 h SETTLE, 1 h DRAW and 0.75 h IDLE. Methanol, sodium acetate and sodium propionate, at the concentrations equivalent to theoretical COD values of 50, 100 and 150 mg O2 1−1 were used as the external carbon sources and added to the reactors prior to the anoxic stage. The study reveals that 4 h aerobic stage was sufficient to nitrify more than 98% NH4+-N and carbon addition caused slightly more nitrification than the control. Addition of sodium propionate at a low concentration (50 mg O2 1−1) significantly enhanced the denitrification process, the nitrate content in this reactor dropped to 3 mg 1−1 (89% reduction) at the end of the anoxic stage. Among the three substrate added at low dose, sodium propionate was the most effective carbon source, followed by acetate and the least effective one was methanol. When the carbon substrate were added at the doses of 100 and 150 mg O2 1−1, the denitrification rates of the acetate reactors recorded at the first hour of the anoxic stage were similar to those of the propionate's and significantly higher than the methanol reactors. When high dose (150 mg O2 1−1) of acetate or propionate was used, 95% reduction in wastewater NOx-N was found after 1 h anoxic stage while 3 h anoxic stage was required when the carbon dose was at 100 mg O2 1−1, indicating that addition of external carbon substrate at large quantity could shorten the denitrification time. However, the final effluent discharged from reactors treated with high dose of acetate and propionate contained more than 20 mg 1−1 BOD5 which might cause a contamination problem. Therefore, addition of sodium acetate or propionate at the concentration equivalent to theoretical COD values of 100 mg O2 1−1 appeared to be the most economical and reliable option.
Study on nitrified liquor recycling process operations using polyurethane foam sponge cubes as a biomass support medium
Authors: Deguchi H. , Kashiwaya M.
Published: May 2018

An experimental study was carried out to find a way of using sponge cubes as a biomass support medium to reaction tanks for nitrified liquor recycling process. Type-A, in which biomass fixed cubes are contacted with both anoxic and oxic stages and Type-B, where biomass fixed cubes are contacted with either anoxic or oxic stages, were selected as experimental cases.

The results showed that the amount of CO2-C generated which was related to sludge production for Type-B exceeded the amount for Type-A by between 12 to 21%. The nitrification and denitrification rate coefficients at 20°C in Type-A were 1.5 and 1.6 times respectively higher than the coefficients for suspended growth. The rate coefficients in Type-B were 1.5 and 2.0 times respectively higher than the coefficients for Type-A.
Dynamics of phosphorus and organic substrates in anaerobic and aerobic phases of a sequencing batch reactor
Authors: Carucci A. , Majone M. , Ramadori R. , Rossetti S.
Published: May 2018

This paper describes a lab-scale experimentation carried out to study enhanced biological phosphate removal (EBPR) in a sequencing batch reactor (SBR). The synthetic feed used was based on peptone and glucose as organic substrate to simulate the readily biodegradable fraction of a municipal wastewater (Wentzel et al., 1991). The experimental work was divided into two runs, each characterized by different operating conditions. The phosphorus removal efficiency was considerably higher in the absence of competition for organic substrate between P-accumulating and denitrifying bacteria. The activated sludge consisted mainly of peculiar microorganisms recently described by Cech and Hartman (1990) and called “G bacteria”. The results obtained seem to be inconsistent with the general assumption that the G bacteria are characterized by anaerobic substrate uptake not connected with any polyphosphate metabolism. Supplementary anaerobic batch tests utilizing glucose, peptone and acetate as organic substrates show that the role of acetate in the biochemical mechanisms promoting EBPR may not be so essential as it has been assumed till now.
Selecting soil amendment materials for removal of phosphorus
Authors: Cheung K. C. , Venkitachalam T. H. , Scott W. D.
Published: May 2018

Phosphorus sorption capacities of several different materials including Merribrook soil (a loamy sand) and some industrial solid wastes (red mud neutralized with gypsum, fly ash, bottom ash and black oxide) were determined in sorption isotherms by Langmuir and Freundlich equations. The materials were characterized by bulk density, particle density, total porosity and particle size distributions. Red mud gypsum possessed the best sorption capacity based on the Langmuir maxima. Alkaline fly ash and Merribrook soil had lower sorption maxima compared to the red mud gypsum. Bottom ash and acidic fly ash had very low sorption capacity at low concentrations. Merribrook soil had the highest hydraulic conductivity. The results suggested that alkaline fly ash may be a promising amendment for coarse sand bed to enhance phosphorus removal. Merribrook soil appears to be suitable for on-site wastewater treatment.
Effect of nitrate on phosphorus release in biological phosphorus removal systems
Authors: Kuba T. , Wachtmeister A. , van Loosdrecht M. C. M. , Heijnen J. J.
Published: May 2018

The effect of nitrate on phosphorus release by biological phosphorus removing organisms has been studied. Denitrifying (DPB) or aerobic phosphorus removing bacteria were enriched in an anaerobic-anoxic or anaerobic-aerobic sequencing batch reactor (SBR). The enrichment sludges were used in batch tests, in which the effect of simultaneous presence of substrate (HAc) and nitrate was studied on the phosphorus release. It could be concluded that a reduction of the phosphorus release by nitrate in biological phosphorus removal systems is partly due to the presence of DPB, which utilize HAc for denitrification, not for phosphorus release. PHB (poly-β-hydroxybutyrate) was always produced and phosphorus was released by DPB sludge when nitrate and HAc were simultaneously present. The reducing power (NADH2) and the energy (ATP) for this process seemed to be obtained from HAc oxidation by nitrate as well as from polyphosphate degradation. After removal of the HAc, PHB degradation and phosphorus uptake occurred.