bluuebunny/crossref_metadata_2025 huggingface dataset:
The Use of Rheology for Sludge Characterization
Authors: Campbell H W , Crescuolo P J
Published: May 2018

Rheological measurements were conducted on a variety of anaerobically digested sewage sludges to evaluate the potential use of rheology in describing the effects of chemical conditioning on the physical characteristics of sludges.

The objectives of the study were to evaluate the influence of the method of chemical conditioning on rheological measurements; to determine the response of the viscometer system to changes in the instrument variables; and to evaluate interrelationships between rheology and other physical properties. All rheological measurements were made using a coaxial rotational viscometer.

Evaluation of a variety of test procedures identified that both the method of adding chemical conditioners, and the acceleration rate of the rotational viscometer, could significantly alter the shape of the rheograms. A suggested methodology was identified and selected samples were analyzed in triplicate to test the reproducibility of the procedures.

Existing mathematical models do not adequately describe the variety of flow behaviour patterns observed with sewage sludge. The concepts of yield stress and apparent viscosity also have limited value due to problems of definition and calculation. A parameter termed the “instantaneous viscosity”, defined as the derivative of the flow curve, is suggested as being more suitable for describing sludge behaviour.

The relationships between chemical conditioning, particle size distribution and applied shear were explored. As polymer addition increased, the sludge particles became more susceptible to shear breakup. The extent of particle size reduction was a function of the rate of shear and the time during which the shear was maintained.
Continuous Countercurrent Ion Exchange for Desalination and Tertiary Treatment of Effluents and Other Brackish Waters
Authors: Hendry B A
Published: May 2018

A continuous countercurrent ion exchange (CCIX) process has been developed for desalination of mineralized effluents and brackish water. The process utilizes macroporous resins in a strong cation/weak anion sequence. Removal of organic matter by the anion resin results in colour and odour removal and approximately 70% reduction of the COD of humus tank effluent.

No pretreatment is required and resin has been in use over the equivalent of more than two years of continuous operation without significant fouling or loss of capacity. Any required degree of desalination is attinable. The basic four-colunn system (cation load and regeneration pair and anion load and regeneration pair) of countercurrent fluidized bed multistage contactors attains greater than 80% water recovery using up to 1,0 N sulphuric acid and 0,2 N lime slurry as regenerants. Low solubility of CaSO4, in the cation waste liquid and column operating problems if high lime concentrations are used set limits on the water recovery. Calcium content of the feed water affects water recovery.

New techniques using five-column systems permit byproduct recovery and/or reuse of spent regenerants and result in over 90% water recovery. The capital cost estimate for a 10 000 kℓ/day plant is R5 million while unit costs of water are 30 to 40 c/kℓ. for removal of 500 mg/ℓ TDS. Present work involves lime contacting improvements and evaluation of carbon adsorption polishing of the ion exchange product to produce potable water.
Involving Practitioners in Research–A Key to Successful Technology Transfer
Authors: Odendaal P E
Published: May 2018

Personal contact has been identified by many authors as a prerequisite for success = ful technology transfer. The most successful way of optimizing personal contact is the involvement of user agencies in research. The paper identifies opportunities for practitioner involvement at the following stages of the research process: the identification of research needs; research planning; research and development; and the packaging of research findings. Practitioner involvement could under certain circumstances limit research application to the needs of one user agency only and precautionary measures should be taken. The major initiative for involving users in research should be ‘push' from research funding organizations, but co-operative ‘pull' from user agencies are necessary for successful involvement.
German Experiences with Low and High Technology Methods for Disinfection of Municipal Sewage Sludges
Authors: Strauch D
Published: May 2018

Municipal sewages contain considerable amounts of infectious agents like bacteria, viruses and parasites. It is known that primary, secondary and tertiary treatment of sewage do not destroy the infectious agents totally. Therefore the effluents of sewage treatment plants still carry infectious bacteria, viruses and parasites which are discharged into the receiving waters.

The sludges which are retained in the treatment plants (raw, surplus, and chemical) are enriched with pathogens. Even anaerobic digestion does not eliminate all of these pathogenic agents.

Because of the microbial hazards which these sludges pose for public health they must be disinfected prior to their agricultural use. Some available methods are: composting of liquid sludge in windrows with straw, pasteurization, aerobic-thermophilic stabilization, addition of lime as conditioner for dewatering in filter presses, irradiation with electron accelerators or radioactive sources, composting dewatered sludge in windrows or in aerated stationary/movable reactors with or without addition of matter like straw, sawdust, bark, refuse etc., solidifying with unslaked lime.

With these methods experiments using salmonellas, enteroviruses and eggs of ascaris suum as test agents were performed to evaluate their disinfecting effects. The results are described and discussed.
Agricultural Utilisation of Sewage Sludge in the U.K.
Authors: Matthews P J
Published: May 2018

The paper describes the overall problems facing the UK water industry in the disposal of sewage sludge and gives relevant statistics. The greatest proportion of sludge (about 45%) is used in agriculture and the paper continues by describing national policies and practices which, if followed, will ensure that a valuable resource is recycled safely without damage to the environment or public health. Guidelines issued by the Department of the Environment (National Water Council Committee) are reviewed and summarised. Operational aspects of the services provided to agriculture by the water industry are also discussed.
Composting: Engineering Practices and Economic Analysis
Authors: Epstein E , Alpert J E , Gould M
Published: May 2018

Composting of sewage sludge is becoming an attractive management system in the U.S. The predominant system being used is the U.S. Department of Agriculture's static pile system. Improvements in materials handling and system design is discussed and related to existing operations. The economics of facilities producing 5, 50, and 100 dry m. tons in relation to sludge solids content of 17 and 25 are presented.
Forced Aeration Composting
Authors: Willson George B
Published: May 2018

Composting enhances the acceptability of sewage sludge for land application especially in high density population areas. A relatively simple method of forced-aeration pile composting was developed at the Beltsville Agricultural Research Center. Pilot tests of full scale composting were conducted to determine process control and facility design requirements. The amount of bulking materials needed to condition the sludge for composting is related to the percentage of sludge solids. Aeration is discussed as it relates to oxygen consumption, temperature control and moisture removal. The process is readily adaptable to many operating conditions, to a variety of materials, and to a wide range of levels of compost production.
Using Lime Treated Acid Mine Water for Irrigation
Authors: du Plessis H M
Published: May 2018

The disposal of acid sulphate mine water poses a universal problem. Although water quality is much improved when neutralised by lime treatment high salt loads nevertheless make release to better quality surface streams undesirable. The feasibility of using such water for irrigation was evaluated using a steady state chemical equilibrium model to predict the composition of water draining from successive soil segments under a range of leaching fractions. Large amounts of gypsum are expected to precipitate in the soil profile resulting in a greater reduction in salinity than would occur if the water contained chloride instead of sulphate. A comparatively smaller reduction in crop yields can thus be expected and a greater variety of the marginally salt sensitive crops can be grown. The precipitation of gypsum however results in an increased sodium hazard to soil physical properties. This does not appear serious when evaluated against published data on soil hydraulic conductivity as affected by sodium and electrolyte concentration. A drastic reduction in the salt load in drainage from irrigated land compared to that in the applied water is predicted. Irrigation with lime treated acid mine water does not only seem feasible but also advantageous for the protection of water resources from mineral pollution.
Virus Behavior in Irradiated Sludge
Authors: Vasl Robert J , Eizenberg Eli , Lapidot Mordechai , Kott Yehuda
Published: May 2018

The effects of the gamma and microwave radiation of virus seeded sludge were studied. Both seemed to be feasible solutions in the disinfection of wet sludge for its re-use. The storage of radiated sludge for a number of weeks was also effective in reducing the numbers of pathogenic microorganisms.
Coal-Fired Power Generation in Ontario – A 60 Year Phenomenon. Coal Ash Disposal in Ontario – A 1000 Year Legacy?
Authors: Dodd D J R
Published: May 2018

The production of electricity from coal combustion started in Ontario in 1951; by 2010 most of Ontario Hydro's existing coal-fired power plants could be largely retired. The legacy of this 60 year period of coal combustion will be a few fly ash-cement buildings, a few fly ash-filled bridge abutments and several large megatonne fly ash disposal sites. In-house research studies into ash leaching characteristics began 20 years after fly ash disposal commenced - current environmental awareness, coupled with advances in chemical analytical technology dictate that laboratory studies and disposal site monitoring will continue for years to come. Some of the variables - coal source, ash characteristics, disposal site location and design, leachate monitoring, collection and treatment plans - are discussed in relation to the Ontario situation and the anticipated time frame for continued study. Future areas for research and future prospects for large scale fly ash disposal projects are identified. The current findings indicate that properly engineered ash disposal projects are an asset, not a burden, to the people of Ontario.
Historical Changes in Acid Precipitation and Heavy Metals Deposition Originating from Fossil Fuel Combustion in Eastern North America as Revealed by Lake Sediment Geochemistry
Authors: Ouellet M , Jones H G
Published: May 2018

The present study deals with the geochemical stratigraphic evolution of the most recent sediments in lakes of Eastern Canada (Quebec). In particular, the sediments from two representative soft water lakes (Tantare and Laflamme) in “undisturbed” watersheds on the southern edge of the Precambrian Shield were studied.

The increase in A1 in the sediments of Lake Tantare since about 1950 is attributed to the processes of surface water acidification of this watershed induced by acid precipitation. The analogous upper strata of the sediments from Lake Laflamme, a non-acidified lake, show no such increase in Al content.

Pb, Zn and Hg levels in the sediments increased significantly from 1940 onwards. However, the subsequent reduction in the stratigraphic concentration of Zn since 1960 in both Lake Tantare and Lake Laflamme is, in all probability, the result of the important decrease of the total particulate emissions to the atmosphere from coal-fired plants. The same phenomenon may also explain Hg decrease during the same period. In contrast, Pb shows no such reduction in the more recent strata and the sustained increase of this element in the sediments is attributed to the progression in motor vehicle activity during the past twenty years.

Further data from other isolated lakes suggest that the major sources of heavy metal deposition and acid precipitation in the Province of Quebec are the emissions from fossil fuel combustion (coal and/or motor fuel) originating in the heavily industrialized American Midwest and Great-Lakes Regions.
Observations Supporting Phosphate Removal by Biologically Mediated Chemical Precipitation – A Review
Authors: Arvin Erik
Published: May 2018

Chemical precipitation of phosphorus in biological treatment plants may be mediated biologically in at least two ways. First the elevated P-concentrations created by anaerobic phosphate release from bacteria can initiate and accelerate calcium phosphate precipitation. Secondly biological denitrification in fixed biofilms and possibly also in bacterial floes can lead to phosphate precipitation due to the elevated pH-conditions inside the biofilms. In both cases the bulk precipitation conditions must be generally favourable, i.e. the calcium concentration should be reasonably high, roughly above 50 mg/ℓ, and the concentration of precipitation inhibitors low: magnesium, pyrophosphates and bicarbonate (alkalinity). With respect to accelerated bulk precipitation it is also essential that the pH is relatively high, preferably above 7.5.

Biologically mediated phosphate precipitation is only two P-removal mechanisms out of several mechanisms. Apart from normal biological P-assimilation phosphate can be removed through polyphosphate accumulation in bacteria and through normal chemical bulk precipitation. The paper gives a survey of the mechanisms.

Virtually all the published literature on P-removal in biological treatment plants contain insufficient data to evaluate the alternative P-removal mechanisms.

In particular there is a need for agreement on procedures with which to characterize the P-fractions in the sludge in order to determine how much P is removed by the bacteria and by mineral phases.

Still much qualitative and quantitative knowledge is required on both the biological and chemical P-removal mechanisms before reasonable optimization strategies and design criteria can be outlined.
Performance and Operational Aspects of Biological Phosphate Removal Plants in South Africa
Authors: Paepcke B H
Published: May 2018

A survey was undertaken of the operation and performance of eleven multi-stage activated sludge plants in South Africa designed for biological nitrogen and phosphorus removal. The results indicate that phosphorus removal has been consistently good in only one case, although several other plants have performed very well in recent months. The major factors adversely affecting phosphorus removal are excessive amounts of nitrate and dissolved oxygen in the anaerobic basins. Nitrate is introduced into the anaerobic basin in the return activated sludge when denitrification is incomplete. Incomplete denitrification is due to a disproportionately low amount of carbonaceous matter in the influent wastewater relative to the total nitrogen concentration. The dissolved oxygen is the result of air entrainment at the Archimedes screw return activated sludge pumps, at cascades in the influent and return sludge channels, and by vortices caused by the stirrers. Other factors which have significantly affected plant performance are mechanical problems, inadequate operator training, and insufficient sample analyses on which to base operating decisions. With due recognition paid to these problem areas, the performance of future designs should be much improved.
Design Consideration Regarding Phosphate Removal in Activated Sludge Plants
Authors: Barnard James L
Published: May 2018

This paper enumerates various practical consideration concerning the design and operation of activated sludge plants for the removal of phosphates. When phosphate removal is required without the conversion of ammonia to nitrates, either the Pho-strip or the Phoredox processes could be used. If ammonia conversion and/or the removal of nitrogen are also required, the use of the Phoredox process in combination with internal nitrification and denitrification would be required. Nitrates, when formed in the process should be removed to sufficiently low levels through internal denitrification so that they will not prevent anaerobic conditions of being maintained at all times in the anaerobic basin. Factors that may influence the proper functioning of the plant include temperature, pH, carbon to nitrogen ratio, septicity of the sewage, operator input, DO control, sludge age and clarifier design.
Statistical Evaluation of the Blind Test Method for Water Quality Control
Authors: Bousquet G , Ouvrard J , Rigal S , Vilagines R
Published: May 2018

Each of the three taste panels, consisting of ten persons, participated in 18 water-tasting sessions which included a duplicate estimation of 4 randomly distributed dilutions. The statistical analysis of the 1 440 scores obtained showed a good correlation (r = 0.87) in between scores of the first water tasting and the scores of the second one. Factorial analysis showed that the panelists as a whole find a flavour in the same samples and are able to arrange the dilutions in a proper sequence. This analysis also showed that the differences in the estimation of the intensity of flavour carried out in the absence of periodical calibrations lead to a significant interval between taste threshold values given by each panel. The study of score-dilution contingency tables displayed the sensitivity of each panelist as well as the homogeneity or the heterogeneity of his panel. A change in the water origin and a simple change of the taste panel room reduced temporarily the coherence of scores. The data showed that water tasting is a reliable and reproducible technique in which the observed discrepancies among taste panels are similar to differences found in chemical analyses of palatable substances among laboratories.
Off-Flavors in Pond-Cultured Channel Catfish
Authors: Lovell R T
Published: May 2018

A serious problem in pond culture of fish is the absorption of compounds from the aquatic environment which impart disagreeable flavor in the fish. “Musty” or “muddy” off-flavor is caused by geosmin (trans, 1, 10,-dimethyl-trans-9- decalol) and 2-methylisoborneol. These compounds can be produced by various species of algae and actinomycetes. Aquarium studies with mono-species cultures of geosmin-producing algae indicate that channel catfish can absorb off-flavor compounds exclusive of the digestive tract. Geosmin was absorbed at sensorily detectable levels within 24 hours. Off-flavor can be purged from catfish relatively quickly by holding in clean water for 4-10 days. Temperature influences rate of flavor removal and also rate of weight loss by the fish. Although the “musty-muddy” flavor has been regarded as the predominant pond-related off-flavor in fish, a recent study in which catfish from 220 commercial ponds was sensorily evaluated showed that it accounted for only 17% of the off-flavor. “Sewage” was the dominant flavor in 25% of the off-flavor samples. “Stale”, “rancid”, “metallic”, “moldy”, “petroleum”, and “weedy” were other off-flavors described. Geosmin was chemically identified in the fish with the “musty-muddy” flavor; the other compounds have not been identified.
Recent Development in Analytical Methods for Identification of Off-Flavour Compounds
Authors: Veijanen A , Lahtiperä M , Paukku R , Kääriäinen H , Paasivirta J
Published: May 2018

The best resolution of individual off-flavour compounds is achieved by glass or quartz capillary gas chromatography. A special two-column system was used by which simultaneous instrumental detection and sniffing (odour desorption) of odorous compounds could be done. The measuring detectors were flame ionization (FID), electron capture (ECD), flame photometric (FPD) and a mass spectrometer (MS). Structural assignments of the odorous substances were done from MS data and verified by model compounds. Before the GC run the sample was collected at the head of the double column using a cold trap device. The sample for analysis was injected in liquid form or, more efficiently, thermally desorbed from an adsorption tube or from different headspace devices with the cold trap on.
Biodegradation of Recalcitrant Organochlorine Compounds in Fixed Film Reactors
Authors: Salkinoja-Salonen M S , Hakulinen R , Valo R , Apajalahti J
Published: May 2018

Biodegradation in fixed film reactors of chloroorganic compounds in kraft bleaching effluent and in pesticides was studied. Specific biofilm reactors could be adapted for the mineralization of chloroform, chlorophenols, chlorocatechols, chloroguaiacols, chloroveratroles and chlorinated resin acids in bleaching effluent and for chlorophenols in spills of pesticides for blue stain and wood rot. Mineralization of chloroorganic compounds into inorganic chloride and carbon dioxide occurred in the solid phase of the reactor. The ability to degrade the chlorine compounds could be transferred from one reactor to another by transferring the liquid but no degradation occurred before addition of solids in the reactor. The degradation of pentachlorophenol was most active when softwood bark was used as the solid material It was less active on unglazed pottery, and inactive on glass (beads or fibre), cellulosic fibre, clay and ion exchange resin. The mineralization of the chloroorganics occuring in kraft bleaching effluent was less fastidious about the type of solid materials used. The biofilm grew equally well on softwood bark, ion exchange resin and various types of plastic and fiber.
Dairy Waste Treatment with Anaerobic Stationary Fixed Film Reactors
Authors: van den Berg L , Kennedy K J
Published: May 2018

Cheese whey and a dilute waste from a cheese factory with a Chemical Oxygen Demand of 66,000 and 4,000 mg (COD)/L respectively, were treated at high loading rates in 0.7 to 1.2 L downflow anaerobic stationary fixed film reactors and an upflow sludge bed reactor. In downflow stationary fixed film reactors treating cheese whey, COD removal efficiencies of 97% were achieved at a loading rate of 5 kg COD/m3/day and 92% at a maximum loading rate of 22 kg COD/m3/day. With dairy plant waste, loading rates of up to 15 kg COD/m3/day were possible with COD removal efficiencies averaging 75%, decreasing slightly with increasing loading rates. In an upflow sludge bed reactor the COD removal efficiency of dairy plant waste, decreased from 87% at 5 kg COD/m3/day to 73% at 15 kg COD/m3/day. A stationary fixed film reactor treating a skim milk powder waste (4,000 ppm) could only be operated at up to 10 kg COD/m3/day with a treatment efficiency of 72%. Methane was produced from all wastes at rates corresponding to 0.32 m3 CH4 (0°C, 1 atm) per kg COD removed. Results show that stationary fixed film reactors are capable of treating dairy wastes at high loading rates and high COD removal efficiencies.
Use of Blood Lead and Erythrocyte θ-Amino Levulinic Acid Dehydratase Activity to Detect Lead Exposure of Fish Populations
Authors: Hodson P V
Published: May 2018

The measurement of blood lead concentrations and inhibition of erythrocyte θ-amino levulinic acid dehydratase activity (ALA-D) has been used successfully to diagnose lead exposure in human populations. While blood lead is one of the best indicators of lead exposure, its measurement is expensive, time consuming, subject to bias through contamination and requires highly skilled personnel. The advantages of assaying ALA-D activity are those of cost, speed, sample size and simplicity. Since most organisms possess this enzyme in a variety of tissues, and since its activity is inhibited only by lead, there is potentially a large variety of aquatic species that may be used to monitor “biologically available” lead in aquatic ecosystems. Sessile and migratory species could integrate short-term fluctuations in waterborne lead and provide data on spatial and temporal variations.

Fish are convenient organisms to sample and fish blood is a particularly rich source of ALA-D. Laboratory experiments have defined the optimum conditions for blood sampling and assaying ALA-D activity as well as the strong negative correlation between blood lead concentrations and ALA-D activity and between waterborne lead concentrations and ALA-D activity. Other toxic metals (e.g. Cu, Hg, Zn, Cd) and PCB's do not inhibit ALA-D, and factors that increase lead toxicity (e.g. decreased environmental pH) also increase lead uptake and the inhibition of ALA-D. Consequently, ALA-D activity provides a measure of both exposure and effect. Species variation in rates of lead uptake allows a selection of a suitable monitoring species for a given, situation.

Preliminary surveys of Lake Ontario fish populations indicate that monitoring of ALA-D activity is technically simple and straightforward, the assay is much cheaper and faster than blood lead or whole body lead analyses, and activity is correlated to other measures of lead in fish.
Tests Made of Separate Mechanical Thickening of Surplus Activated Sludge in the Treatment Plant at Wuppertal-Buchenhofen, F.R.G.
Authors: rechtel Heinz B
Published: May 2018

For better exploitation of the existing digesters and for optimizing the sludge incinerator, tests have been carried out for mechanical thickening of surplus activated sludge.

The biological treatment stage operates at a daily capacity of 6,300 m3 surplus activated sludge with a solids content of 0.7 %.

The results of the tests carried out by means of static thickening, flotation, as well as with the aid of nozzle separator, screen bowl, and a standard dewatering centrifuge have not been satisfactory.

A newly developed nozzle-thickening centrifuge operating at a rated capacity of 60 m3/h achieved test results within a solids content range of 4 - 6 % in the cake.

A larger thickening centrifuge of 120 m3/h capacity is also operating successfully at present.

As can be taken from the test results, mechanical thickening of the surplus activated sludge to a solids content of more than 4 % can be achieved, and thus the sludge volume reduced to 1/5 - 1/6 of the original value. By this method, a degree of separation of approx. 80 % and a solids content of between 0.07 and 0.12 % in the centrate is reached without the addition of polymers.
The Sheffield (U.K.) Sludge Incineration Plant: 1968 - 1983
Authors: Tench H B , Haigh M D F
Published: May 2018

Operating experience with the first plant commissioned in England is described with particular reference to the changes in operating conditions and costs which have occurred. In the year ending 31st March, 1970 the operating costs, including transport of presscake and ash, were ₤2.8 per tonne sludge dry solids but in that ending March 1982 they were ₤73.

The factors, in addition to inflation, which were responsible for this are discussed. Reference is also made to plant reliability and maintenance aspects and to the improvements which have been made.

Investigations of ways of reducing costs, notably by tipping half the presscake in conjunction with the ash produced by burning the rest of the presscake, are described. Trials using waste derived fuel as a substitute for oil are referred to as is the use of polyelectrolytes for sludge conditioning instead of lime and copperas.
Sludge Treatment and Disposal Techniques for Operation of the Coleshill Sludge Destruction Plant, U.K.
Authors: Tabberer R , Broughton J S
Published: May 2018

The Coleshill Sludge Destruction Plant has to process 1100 m3/d of wet sludge to achieve an inert ash occupying 18-20m3.

Output is expected to increase dramatically with the closure of small, less effective works and increasing use of sewer transport as a means of exporting sludges to large treatment centres.

The greatest progress at this large pressing-incineration unit is a better understanding of the nature and variation of the feed sludge.

Sophisticated monitoring techniques and the judicious blending of both organic and inorganic chemical conditioners has led to the best plant performance to date. Overall performance and economic studies are leading to increased use of microprocessor control and computer technology.
The Haringvliet-Project: The Development of the Rhine-Meuse Estuary from Tidal Inlet to Stagnant Freshwater Lake
Authors: Ferguson H A , Wolff W J
Published: May 2018

In 1970 the common outlet of the rivers Rhine and Meuse, the Haringvliet estuary, was closed by the construction of large sluices and changed from a brackish tidal inlet into a stagnant freshwater lake. Ecological knowledge on the effects was available, but at that time hardly used in the design and execution of this large project of coastal engineering. Besides the expected ecological changes the closure resulted in, partly expected, negative effects on the ecosystems in the new lake through lack of physical planning, lack of conservation measures, pollution, unrestricted development of outdoor recreation, shore erosion and absence of mitigating measures in general. It is shown that part of these negative developments could have been avoided by timely integration of ecological knowledge in the realm of coastal engineering and by physical planning of the area.
Tidal Management: Consequences for the Salt-Marsh Vegetation1
Authors: Groenendijk A M
Published: May 2018

The construction of a storm-surge barrier in the mouth of the Eastern Scheldt will allow complete control of the tidal conditions in the estuary.

In order to indicate the limiting conditions for tidal management for the plant species, a number (10) of the most prominent salt-marsh angiosperms were tested for their tolerance against elongated inundation times of 2, 4 and 8 days. Criteria such as: die back, regrowth, generative development and seed germination were measured. The results indicate that for the majority of salt-marsh angiosperms a prolonged inundation is not likely to cause immediate die back.

Only the species from the higher reaches of the marsh are severely affected by the impact of the barrier closure at high water levels. All species involved show a decreasing immersion tolerance with increasing water temperatures, with a subsequent die back of the less tolerant species.

In contrast with the vegetative parts of the species, the inflorescences suffer an overall severe negative effect from prolonged immersions. This leads to the conclusion that prolonged summer inundations have to be avoided as much as possible.
Integration of Ecology in Coastal Engineering
Authors: Saeijs H L F , Duursma E K , Davoren W T
Published: May 2018

This article aims at a brief evaluation of the ECEP-symposium from the viewpoint of ecology. From this viewpoint first of all the importance of coastal zones, and more especially estuaries for man and other life is emphasized. Trial and error in coastal engineering and coastal management is illustrated with some examples derived from the papers of this symposium. On the basis of some rough cost/benefit calculations it becomes clear that without integration of ecological aspects, from the beginning to the end, expensive and unforseen additional expenditures may result with costs comparable or even many times higher than the original project costs.

Attention is focussed on the lessons to be learned from the papers. The major observations are briefly classified in order of importance. The main conclusion is first of all to handle carefully the integrity of coastal environments, with special attention for estuaries, and to find solutions for society's problems and wishes without disrupting modifications or transformations. But in doing so the process of change requires a close control in terms of planned modification or transformation, an integral ecosystem approach and an adaptive environmental management strategy. In this relation a new management and design strategy is proposed, with the recognition that we are dealing with a process. It is an open ended strategy which requires adaption to new unforeseen events in decision making or in (new) environments. In conclusion a number of statements are presented.
Quantification of Accumulated Loads on Road Surfaces and Their Runnoff Characteristics
Authors: Wada Yasuhiko , Miura Hiroyuki
Published: May 2018

For the purpose of reducing nonpoint-pollution loads, we must first survey the quantity of accumulated load on the road surfaces, and investigate the composition and local distribution of accumulated load, and then examine how these loads are flushed out by rainfall.

In this paper, in the first half, the accumulated load is determined and the characteristics of the accumulation are examined in each area. In the latter half, runoff characteristics of accumulated loads in rainfall are considered by simulating the runoff accumulated load.

The accumulated load on road surfaces is determined in each area. It has become clear that the accumulated load on road surfaces shows large differences among each area and that it is flushed out in great quantities at a comparatively early stage in rainfall. It is concluded that in this way we will be able to simulate the runoff accumulated loads on road surfaces, and we can obtain useful information on the prevention of water quality deterioration.
Nitrification Dynamics in the Oxidation Ditch Wastewater Treatment Process
Authors: Cook S
Published: May 2018

A dynamic, stochastic model of nitrification in a Carrousel Oxidation Ditch wastewater treatment process is constructed using systems analysis techniques and operational data. Input and output data time-series are passed through Kaiman Filter algorithms in order to estimate model parameters recursively. Successive hypotheses on model structure arise from un-modelled parameter time-behaviour. Performance of the proposed model in both adaptive and non-adaptive simulation is good but performance in verification is less acceptable.
Methods of Assessing the Trophic State of Lakes and Reservoirs
Authors: Henderson-Sellers B
Published: May 2018

A review is undertaken of various methods of assessment of trophic state in lakes and reservoirs. Input-output models, multi-layer models and trophic state indices are evaluated. Future development of multi-layer models and the use of biological indicators as contributors to compound trophic state indices is advocated.
Characteristics of Paper/Board Mill Wastewaters Relevant to Anaerobic Treatment
Authors: Webb L J
Published: May 2018

Apart from the inherent amenability of the organics present to anaerobic fermentation, a number of other factors are important to the technical and economic viability of the overall process. These include wastewater strength, wastewater temperature, the nature of suspended solids present and the presence of toxic materials, notably sulphates/sulphides and biocides. Analytical data is presented from various Pira research projects, describing the composition of UK mill wastewaters in terms of BOD/COD/DOC, suspended solids, the speciation of dissolved organics (eg carbohydrates, fatty acids) and inorganic sulphur compounds. In the context of anaerobic treatment, this is then discussed in terms of in-mill microbiological activity, the extent of water system closure and the type of sizing system employed.
Anaerobic Treatment of Sulfite Pulp Mill Effluents
Authors: Kroiss H , Svardal K , Fleckseder H
Published: May 2018

Sulfite pulping will still play an important role in Austria in the foreseeable future. Therefore, efficient and economic means of waste-water treatment have to be searched for. The experience gained with operating laboratory scale and semi-technical scale experiments for anaerobic treatment of condensates and the extraction stage effluent from two mills is presented.

As we foresee, in full scale conditions a series of problems arise (neutralization, solids retention, SO2 toxicity, start-up of process) The advantage of the anaerobic process in terms of energy alone cannot, as we had to realize, be the single basis of the investment decision.
Treatment of Different Wastewaters from Pulp and Paper Industry in Methane Reactors
Authors: Latola P K
Published: May 2018

A wastewater from an integrated paper mill with a COD of 1200 mg/dm3 was anaerobically treated in a multi-stage reactor. The BOD7 removal efficiencies of 60-75 % were achieved at maximal loading rates of 5-6 kg COD/m3d and HRT of 4-6 hours due to the granular sludge. Industrial sulphite evaporator condensates from Ca- and Na-processes were treated in anaerobic filters containing light gravel, plastic foam and power plant slag as filter media. The BOD7 removals of 78 % on average were achieved at loading rates of 1.8-3.3 kg COD/m3d with Ca-process evaporator condensates and 80 % BOD7 removals were achieved with Na-process condensates at loading rates of 3.5-4.1 kg COD/m3d.
Comparison of Aerobic and Anoxic-Aerobic Digestion of Waste Activated Sludge
Authors: Warner A P. C. , Ekama G. A. , Marais G v. R.
Published: May 2018

The laboratory scale experimental investigation comprised a 6 day sludge age activated sludge process, the waste sludge of which was fed to a number of digesters operated as follows: single reactor flow through digesters at 4 or 6 days sludge age, under aerobic and anoxic-aerobic conditions (with 1,5 and 4 h cycle times) and 3-in-series flow through aerobic digesters each at 4 days sludge age; all digesters were fed draw-and-fill wise once per day.

The general kinetic model for the aerobic activated sludge process set out by Dold et al., (1980) and extended to the anoxic-aerobic process by van Haandel et al., (1981) simulated accurately all the experimental data (Figs 1 to 4) without the need for adjusting the kinetic constants.

Both theoretical simulations and experimental data indicate that (i) the rate of volatile solids destruction is not affected by the incorporation of anoxic cycles and (ii) the specific denitrification rate is independent of sludge age and is K4T = 0,046(l,029)(T-20) mgNO3-N/(mg active VSS. d) i.e. about 2/3 of that in the secondary anoxic of the single sludge activated sludge stystem. An important consequence of (i) and (ii) above is that denitrification can be integrated easily in the steady state digester model of Marais and Ekama (1976) and used for design (Warner et al., 1983).
Immiscible Contaminant Transport in Soils and Groundwater with an Emphasis on Petroleum Hydrocarbons: System of Differential Equations vs Single Cell Model
Authors: Corapcioglu M. Y. , Baehr A.
Published: May 2018

Soil and groundwater contamination resulting from leaks of petroleum products, from faulty storage tanks and pipelines has become a recent environmental concern. A generalized mathematical model, incorporating the physical, chemical and biological processes which collectively describe the transport of a reactive and immiscible contaminant in soils and groundwater is presented. The problem is one of multiphase transport, that is, the contaminant can be transported as solutes in water, vapors in air and as unreacted constituents in an immiscible phase. Additionally, it may be adsorbed onto the soil surface. Conservation principles lead to a system of nonlinear partial differential equations governing the phenomenon.

As an alternative, a single cell model as a simplified version of this generalized system is also presented. The whole system is represented by a single element. Such an approach yields conservative estimates of a single constituent contaminant as only advective solute transport is allowed. The model has been applied to study the fate and transport of individual hydrocarbon constituents in an unsaturated zone. The results predict the concentrations of each hydrocarbon in all phases in space and time allowing the user to estimate the amounts of hydrocarbons which enter the underlying aquifer or which leave the soil via volatilization into the atmosphere. Such predictions are presented for selected cases. Comparisons of the single cell model with the generalized one are also given.
Retardation of Toxic Chemicals in a Contaminated Outwash Aquifer
Authors: Patterson R. J. , Jackson R. E. , Graham B. W. , Chaput D. , Priddle M.
Published: May 2018

Organic chemicals disposed between 1969 and 1980 in a “Special Waste Compound” at the Gloucester Landfill near Ottawa, Canada, are migrating through a confined outwash aquifer. The subsurface distribution of the chemicals down gradient from the disposal site suggests that chromatographic dispersion (i.e. aqueous phase solute transport plus sorption) is the major process controlling migration. Retardation factors calculated on the basis of relative lengths of contaminant plumes agree closely with those determined independently during a purge-well test and indicate a linear relationship with the logarithm of the octanol/water partition coefficient (Kow):

The slope, 0.50, of this relationship is at the low end of the range of values reported for other expressions of the same form determined principally on the basis of laboratory experiments. This lower slope may reflect the fact that in aquifers flow is predominantly through the coarser, less organic-rich units. The relatively low range of Kow values (log Kow from −0.27 to 2.83) represented by the contaminants may also be a factor contributing to a smaller slope value.
The Recovery of Viruses from Drinking-Water by Means of an in-Line Electropositive Cartridge Filter
Authors: Nupen E. M. , Bateman B. W.
Published: May 2018

Efficient, fast and relatively inexpensive techniques, which will consistently give high recoveries of viruses from one hundred or more litres of water, are still sought for the monitoring of drinking-water systems.

A technique using electropositive absorbent filters showed promise if sample volumes were limited to 100 ℓ. Investigation of this recovery method was warranted, as the use of an in-line cartridge filter would constitute an ideal monitoring tool if the filter could be inserted at set points in a distribution system, removed under sterile conditions after the filtration of a known volume of water, and returned to a specialized virological laboratory for elution and virus isolation.

In the present study, tests were carried out to determine the efficiency of positively charged AMF-Cuno Virosorb cartridge filters in processing 100 ℓ of tap water continuously seeded with varying dosages of different viruses. Viruses were desorbed by the cycling of a 3 g/ℓ beef extract solution in 50 mM glycine - NaOH at pH 9.5 for 5 min, followed by immediate neutralization with 1 mol/ℓ HCl. In order to avoid a second concentration step, the 1 ℓ eluent was converted into growth medium by the addition of dehydrated Dulbecco's modified Eagle medium with decontamination by filtration through a 147 mm diameter 0.22 µm membrane. In eleven tests where the average poliovirus 1 seed was 22 × 106 TCID50 per 100 ℓ, virus recoveries were 75.9% ± 25.9%. In subsequent tests the virus seed was progressively reduced by one log at a time until the theoretical dosage was between one and ten TCID50 virus per 100 ℓ tap water. Virus could always be isolated from at least one to ten Nunc flasks which had been changed to the Virosorb eluent medium. Comparisons are given of the efficiency of the technique for the recovery of poliovirus types 1 and 2, reovirus type 1, the SA 11 rotavirus and coliphages.
Evaluation of Temperature Effects on Trickling Filter Plant Performance
Authors: Adin A. , Baumann E. R. , Warner F. D.
Published: May 2018

This paper presents a mathematical-statistical method to help evaluate the temperature effect on BOD and SS residual ratio during and after a trickling filter plant treatment. Mathematical relationships are developed and brought to workable linear forms which are then used for statistical examination by the F test method. The data for this purpose is provided by regular measurements of wastewater quality in a full-scale treatment plant. While settling performance did not respond consistently to temperature changes, the secondary treatment and the overall plant performance provided good correlations with the correct representative temperatures.
The Influence of Extended Anaerobic Retention Time on the Performance of Phoredox Nutrient Removal Plants
Authors: Gerber A. , Winter C. T.
Published: May 2018

Laboratory-scale studies on the performance of three-stage Phoredox nutrient removal systems under nominal anaerobic retention times varying from 6 to 24 h are described. Particular attention is given to the effect of these extended periods of anaerobiosis on biological phosphate release and uptake, nitrification and denitrification. Increasing the retention time in the abovementioned range had no deleterious effect on nitrification, COD removal, sludge settleability and denitrification but resulted in significantly improved phosphate removals. Up to 15 mg/ℓ phosphate (as P) could be removed from settled wastewater at nominal anaerobic retention times of 12 h or more.
Kinetic Studies of the Microbiological Conversion of Sulphate to Hydrogen Sulphide and their Relevance to Sulphide Generation within Sewers
Authors: Holder G. A. , Vaughan G. , Drew W.
Published: May 2018

The relevance of the studies carried out, to the important practical problem of predicting sulphide generation rates within sewers, is discussed in the introduction section of the paper. The predictive equations presently in use are compared, and the desirability of replacing these empirical equations by a more scientific approach based on an analysis of mass transport and biochemical reaction is stressed.

A theoretical analysis of mass transport and metabolism of sulphate during laminar flow in a model sewer is then described. This theoretical section is followed by the description of the laboratory experimental studies. These studies consisted of flowing simulated sewage through tubes containing biofilms of mixed cultures of sulphate reducing bacteria.

The results obtained in the laboratory studies showed that the diffusional resistance in the liquid phase was negligible and that the biological conversion of sulphate to sulphide followed zero order kinetics when mass transfer was not rate limiting. The observed sulphate removal rates gave good agreement with Australian field data for sulphide generation in sewers. The value of the zero order rate constant (measured at 41 °C) was 30 mg cm−3 h−1.
Flexible Modelling of the Activated Sludge System – Theoretical and Practical Aspects
Authors: Sheffer M. S. , Hiraoka M. , Tsumura K.
Published: May 2018

For the purpose of optimal modelling, a “Flexible Modelling” method was developed. A flexible set of models consisting of hierarchical mechanistic models derived from a highly detailed structured model by mechanistic simplification was obtained. The performance of a computer program with an algorithm for parameter fitting in the time domain was evaluated by use of simulation. The program was able to estimate the models' parameters, even when using data with different degrees of inaccuracy. A computer program for model selection was developed, whereby the model was selected according to the information required. It was found that for prediction of the dynamic behavior of the MLVSS, the simplest model can supply all the necessary information. For prediction of effluent substrate concentration, the differences between the models' predictions depend on the characteristics of the disturbances and on the values of the models' parameters. The selection of the proper model and updating its parameters can be done by a computer which uses the presented program for model selection and parameter fitting.