bluuebunny/crossref_metadata_2025 huggingface dataset:
Acid Precipitation – An International Environmental Problem
Authors: Overrein Lars N
Published: May 2018

The acidification is no longer confined to Scandinavia, it is a trans-World problem. The concept of acidification is bound up with the discharge into the atmosphere of sulphur dioxide, nitrogen oxides, and metals and other micro-pollutants - and the subsequent effects of these substances on the environment. The bulk of man-made emissions occurs over industrialized regions covering less than 5% of the earth's surface. In these regions, man-made emissions exceed the natural emissions by a factor of five to twenty. In the 1950's a sharp rise in oil combustion increased the SO2 emissions in Europe to about 25 million tonnes of sulphur per year by 1970. European emissions of NO have increased from low values 100 years ago to the present value of about 6 million tonnes of nitrogen per year. Similar emission trends of SO2 and NOx have taken place in North America. Sulphur dioxide emissions in Europeare predicted to remain about the same as present-day emission through 1990. Further trends in emission will depend critically on the energy policies of each country and the entire region.

Strong acids have decreased the mean annual pH of precipitation in much of Northwestern Europe and large areas of North America to between 4 and 4.5. The sources and environmental consequences of acid deposition are often separated by hundreds, even thousands, of kilometres. Its impacts on aquatic systems in more susceptible areas of Europe and North America are clearly documented today. Tomorrow, the emission source areas exposed to the heaviest depositions will be facing serious direct and indirect effects on natural ecosystems, materials and possibly even human health. Further, metal toxicity in soils, surface waters and groundwaters with consequences for terrestrial and aquatic life will most likely develop in both heavily polluted and sensitive areas.
Observations Supporting Phosphate Removal by Biological Excess Uptake – A Review
Authors: Marais G v R , Loewenthal R E , Siebritz I P
Published: May 2018

The paper briefly reviews the development of the biological excess removal of phosphorus in the activated sludge process, from 1959 when it was first observed to the present. It concludes by proposing, tentatively, a biochemical mechanism whereby excess P uptake and release can be explained.
Phosphate Precipitation in Biofilms and Flocs
Authors: Arvin Erik , Kristensen Gert Holm
Published: May 2018

The experiments have confirmed that denitrification in biofilms may lead to calcium phosphate precipitation inside the biofilms due to the increased pH created by the denitrification reaction. This has been shown in a laboratory fixed film reactor with well defined geometry and feed with well defined substrates.

The phosphate precipitate was in one case found similar to a carbonate containing apatitic phase. It accumulated in the bio-film to 9.3% P based on dry solids.

A mathematical model has been developed relating the phosphate to nitrate molar removal rates to the concentration of phosphate, calcium, bicarbonate, the solubility of the solid phosphate phase and the type of carbon source used for denitrification. The model was supported by the experiments.

The experiments show that the biofilm precipitation may be of significant practical interest, but factors as filamentous growth on the biofilm surface or precipitation of an easy soluble amorphous calcium phosphate can also make the biofilm precipitation insignificant.

The precipitation effect is expected to be feasible in floes, if a homogeneous biomatrix with a thickness of more than approx. 100 µm exist in the floc substructure.
A Parametric Model for Biological Excess Phosphorus Removal
Authors: Siebritz I P , Ekama G A , Marais G v R
Published: May 2018

Biological excess phosphorus removal in nitrification-denitrification single sludge activated sludge processes is shown to be stimulated by having a concentration of rapidly biodegradable COD (Sbsa) ≧25 mg/ℓ in the anaerobic reactor; the magnitude of the P removal is determined by a P removal propensity factor (Pf) defined by the product of (Sbsa−25) and the fractional mass of sludge in the anaerobic reactor. Sbsa is rapidly depleted by nitrate entering the anaerobic reactor; in the Phoredox process treating municipal waste flows if the TKN/COD ratio of the influent is greater than about 0,08 mgN/mgCOD the process, if designed to ensure efficient nitrification, is unlikely to remove all the nitrate and nitrate is recycled to the anaerobic reactor whereupon P removal declines. A new process is proposed that protects the anaerobic reactor from the nitrate in the effluent; tests indicate that this process can give excess P removal for TKN/COD ratios up to 0,14 mgN/mgCOD.
Full Scale Experience with Phosphorus Removal in an Alternating System
Authors: Bundgaard Erik , Kristensen Gert Holm , Arvin Erik
Published: May 2018

Nitrogen removal performed by the alternating mode of operation results in alternating aerobic, anoxic and anaerobic conditions during different operational sequences of the treatment process.

Phosphorus release and phosphorus uptake have been observed under the anaerobic and aerobic conditions respectively. Phosphorus release is observed when oxygen, nitrate, and nitrite are absent in the bulk liquid. With oxygen or nitrate present re-uptake of phosphorus is observed. Therefore, information about the dynamic parameter variations in the reactors is considered important in order to optimize the effluent phosphorus quality.

Operational results from two treatment plants show enhanced phosphorus removal: 8 mg P/l out of 11 mg P/l in the inlet is removed.

Chemical analyses of sludge samples indicate that precipitation of a calcium-iron-phosphate is responsible for the enhanced phosphorus removal. The precipitate constitutes 12% of the total sludge mass.

At one treatment plant nitrogen removal is combined with phosphorus removal by simultaneous precipitaion with ferrous sulphate. It is shown that even in this system phosphorus release and phosphorus uptake is observed, and knowledge about the dynamic parameter variation during the alternating mode of operation can be used to ensure a stable and low effluent phosphorus concentration.
Practical Experience with Biological Phosphorus Removal Plants in Johannesburg
Authors: Pitman A R , Venter S L V , Nicholls H A
Published: May 2018

This paper describes three years operating experience with two full-scale biological nutrient removal activated sludge plants. Factors affecting biological phosphorus removal are highlighted and possible process improvements suggested.
Drinking Water Contamination and Taste Assessment by Large Consumer Panels
Authors: de Greef E , Zoeteman B C J , van Oers H J , Köster E P , Rook J J
Published: May 2018

The absence of both a general accepted methodology and straightforward objectives on taste and odour assessment of drinking water bring about relatively unreliable results. Also, appropriate standards, such as maximum acceptance levels are absent. In general the assessment of taste and odour of drinking water is practized in waterworks laboratories by small panels. It is not clear if observations by these panels reflect the opinion of the consuming population. Moreover, it has been shown in previous studies that water taste especially is a sensitive parameter, which can be related to the presence of certain toxic chemicals. These considerations related in a study to establish an acceptability criterion for the consumer. This paper considers the results of an experimental period of 51 consecutive weeks. In this period the sensory water quality of two distribution areas was assessed simultaneously by two consumer panels of about 100 persons each. The results show that large panels can be kept motivated over prolonged periods of time. Also, comparison of the results of assessments by small laboratory panels with the consumer panel indicate that the latter is far more accurate, inexpensive and reliable and therefore renders a means for monitoring drinking water taste. Application of consumer taste panels will provide the supplier of drinking water with an expedient to establish and maintain acceptance criteria for drinking water quality with respect to taste. Finally, a combination of laboratory panels to relate taste and odour of drinking water with treatment methods and consumer panels for public acceptance evaluation is proposed.
Odour Problems in Two Reservoirs
Authors: Popovska P
Published: May 2018

The Klicava reservoir was regularly monitored for almost two years. The dissolved oxygen (DO), pH, water temperature, depth, and the relationship between numbers of autotrophs, Actinomycetes and fungi and odour intensity (OI) were measured. using statistical methods, the relationships between odour intensity and pH, OI and DO content were shown. By multiple regression OI in the Klicava water was found to be dependent on the concentration of DO and, to a lesser degree, on water depth. The effect of pH on OI is negligible. The Hubenov reservoir was studied for one year, with a view to the number of Actinomycetes in particular. A negative correlation between OI and DO in the surface water was found.
Occurrence of Various Off-Flavours in Fish in Finland from 1969 to 1981
Authors: Kuusi T , Suihko M
Published: May 2018

Off-flavours in fish were studied from 1969 to 1981 at the Food Research Laboratory of the Technical Research Centre of Finland using sensory methods. In all, 1982 samples of 18 species of Finnish fish, most of them suspected of being tainted, were studied. A trained taste panel scoring on a numerical scale of 0-10, where a score of 5 or less was unacceptable, was used. The off-flavours described were oil, kraft pulp mill effluent, sewage (musty), muddy, rancid, and others. Of all these samples, 34.9% were unacceptable. The most common off-flavour was kraft pulp mill effluent, present in 41.2 % of the unacceptable samples. In acceptable fish slight off-flavours were somet imes found. Of the muddy fish, only 35.2 % of the bream and 28.8 % of the northern pike were unacceptable. The panel was able to discriminate between the different off-flavours, but, in some cases, the boundaries were vague.
Chemical and Sensory Analysis of Off-Flavours in Fish from Polluted Rivers in Norway
Authors: Berg N
Published: May 2018

Fish caught in waters polluted with paper mill effluents have been analysed by a gas chromatographic headspace technique in order to identify the organic compounds causing the strong off-flavour present in the fish. Both chemical and sensory analyses were done and the results compared. The concentrations of off-flavour volatiles present in the different fish samples showed good correlations with the degree of off-taste found by sensory analyses. Typical organic compounds from paper mill effluents such as terpenes and their derivatives caused strong off-flavour, whilst low concentrations of haloforms and other halogen-containing compounds were found.
Off-Flavours in Crustaceans Caught in Australian Coastal Waters
Authors: Whitfield F B , Freeman D J
Published: May 2018

Australia is a major producer of crustacean sea-foods for local consumption and export. Species harvested in commercial quantities from estuarine and ocean sources include prawn, lobster and crab. The common off-flavours encountered in these species are described as garlic, garlic-metallic, rotten onion, solvent and iodoform-like. Chemical studies, including the application of GLC, GLC-MS, micro-NMR spectrometry and microreaction GLC, have led to the identification of most of the compounds responsible for these off-flavours. Compounds identified include bis-(methylthio)-methane, dimethyl trisulphide, (5Z)-octa-1,5-dien-3-ol and a number of aromatic hydrocarbons. Studies related to the biological origin of the offending compounds indicated that microbial spoilage, environmental pollution and diet were the most likely sources of the off-flavours. The paper describes the identification of the off-flavour compounds, indicates their likely biological origin and lists the species affected.
Comparison of Sorption and Extraction Methods for Recovery of Trace Organics from Water
Authors: Blok V C , Slater G P , Giblin E M
Published: May 2018

Several commercially available adsorbents were compared with solvent extraction methods for their utility in recovering trace organics from water. The adsorbents examined included Amberlite XAD-2, XAD-4 and XAD-8, Ambersorb XE340 and XE348 and Tenax-GC. All were found to produce high artifact levels, even after extensive clean-up, making them unsuitable for the analysis of trace organics in water. Quantitatively, Likens-Nickerson or continuous liquid-liquid extraction with méthylene chloride gave better recoveries than the adsorbents. Qualitatively, extractive methods were preferred as they yielded much lower levels of impurities than the adsorbents.

These methods of recovering trace organics were evaluated using a standard mixture of compounds added to the water at a level of 55 µg/l. Likens-Nickerson extraction gave comparable recoveries of this mixture at 55 µg/l and 11 µg/l.
Isolation and Identification of Odourous Compounds from a Lake Subject to Cyanobacterial Blooms
Authors: Slater George P , Blok Vivian C
Published: May 2018

Buffalo Pound Lake in southern Saskatchewan, Canada, is subject to heavy blooms of blue-green algae, mainly Anabaena, Oscillatoria and Aphanizomenon. The occurrence of any of these species is usually followed by the appearance of pronounced tastes and odours. Water samples were extracted using a Likens- Nickerson or continuous liquid-liquid apparatus and capillary GC of the extracts showed that a large number of compounds are always present although the taste and odour vary in intensity. Many of these compounds have been identified using capillary GC-MS. Geosmin, which imparts a muddy flavour to water, was detected but methylisoborneol was absent. Other compounds present in the water included alkanes, alkylbenzenes, acetophenone, cyclohexanone, phenylacetonitrile, and α-pinene, some of which could affect the palatability of the water. Although some water samples had a musty odour extracts were frequently dominated by a pungent, smoky or tobacco flavour consistent with the presence of β-cyclocitral which was also indicated by GC-MS.
Municipal Drinking Water Treatment Procedures for Taste and Odour Abatement – A Review
Authors: Montiel A J
Published: May 2018

Taste and odour of water are sensory qualities the consumers can appreciate very easily. It is of prime importance that, during the water treatment process, taste and odours be removed and that the tap water have no abnormal taste or odour.

There are three sources of tastes and odours, the removal of which must be studied separately. All the odorous compounds originating in the raw water should be removed in the treatment processes which are clarification, oxidation and adsorption. During water treatment processes such as the oxidation stage (chlorination), tastes and odours may be produced and the use of such treatments must be carefully monitored. Tastes may be produced in the water distribution system by microbiological activity which must be suppressed.
The Role of Acute Toxicity Tests with Aquatic Animals in Chemical Registration and Notification Schemes
Authors: Lloyd R
Published: May 2018

Existing and proposed chemical registration and notification schemes include a requirement for acute toxicity test data on representative aquatic vertebrate and invertebrate species. These data, taken in conjunction with the pattern of disposal and use of the chemical, its physical and chemical properties, its stability and its potential for biodegradation and transport in the aquatic ecosystem, together with data on mammalian toxicity, contribute towards the initial hazard evaluation. A decision is then made, inter alia, whether further aquatic toxicity tests should be requested. In order to keep such requests to a minimum, it is essential that the maximum amount of useful information should be extracted from the basic toxicity tests.

There has been a recent tendency in standard fish toxicity tests to report only the 96-h LC50 together with confidence limits; the statistical treatment of mortality data has been developed to ensure the maximum accuracy of the derived LC50. Such superficial refinements tend to obscure the scope for inaccuracies in these simple biological tests. The data which are of much greater value are a time series of LC50's within the 96-h period (3, 6, 24, 48, 72 h) from which a toxicity curve can be constructed. These curves have been recognised for many years as providing valuable information on the toxicity of chemicals and form a sound foundation on which to judge the validity of the test technique used for a particular chemical, and if necessary the type of further tests required. Examples will be given of various types of curves and their possible interpretations.

An essential requisite for obtaining accurate toxicity curves is that the test concentrations of a chemical must be kept as constant as possible. Because of the problems and expense of chemical analyses to check whether concentrations of a substance have remained close to the nominal value in static toxicity tests, the basic test technique should be flow-through; static tests can be used only if the existing chemical, physical and biological data indicate that there will be no significant loss of toxicant from the test solution.
Unionacean Clams as Indicators of Persistent Substances in Fresh Water
Authors: Forester A
Published: May 2018

Measurement of total or nominal pollutant concentration in the physical compartment of the aquatic environment (water, sediments, etc.) seldom gives a valid indication of the ultimate threat to the ecosystem. An alternative is to use a living organis to reflect the biological availability of the contaminant and to integrate its changing levels in the environment by monitoring over an extended period.

Pelecypods have been used as indicators of marine coastal pollution, but have received relatively little attention in fresh waters. The large, unionacean clams and mussels show a number of features which suggest that they would be useful as monitors of biological availability of freshwater pollutants: ability to accumulate a wide variety of contaminants; mode of feeding; position on food chain; longevity; sedentary habits; facility with which their age can be determined; abundance; distribution; size and hardiness.

The current programme is concerned with: (1) evaluating unionaceans as potential indicators and the factors that affect pollutant uptake; (2) development of the methodology for monitoring; and (3) characterisation of the pollutant status of Ontario shield lakes which are subject to direct inputs of toxic metals with the precipitation and their mobilisation through the ecosystem as a secondary function of environmental acidification.
Formulation of Water Quality Standards to Protect Aquatic Life
Authors: Lloyd R
Published: May 2018

Water quality standards for aquatic life protection are required only for those chemicals which are likely to occur in harmful concentrations within the aquatic environment. The first requirement is to define the extent to which the aquatic ecosystem is to be protected; three broad categories which might be appropriate are described.

The appropriate standard should be set on the basis of a 95 percentile compliance. This concentration might be greater than the NOEC for the most sensitive life stage of the most sensitive species, as measured by exposure to a constant concentration of the chemical under laboratory conditions.

The standards should be firmly based on laboratory and field data, and be internally consistent. Some recent EPA standards have erred in this respect. Two general rules which apply to the validity of standards are outlined.

Standards should take into account the effect of significant modifying variables such as water hardness and pH. The application of safety factors to the NOEC depends in part on the value of the resource to be protected. For those substances which are bioaccumulated to a significant extent, standards should be based on animal tissue concentration and not on aqueous concentration.
Cold Climate Environmental Engineering–An Overview
Authors: Smith D W , Heinke G W
Published: May 2018

The practice of environmental engineering in cold climates has undergone several significant changes in the last decade. Two of the major reasons have been the increase in resource extraction efforts and the related influx of people, and the development of new and more suitable utilities construction materials. The paper presents current practice information, identifies the major problems to be solved and reviews research needs in the areas of water supply, water treatment, water distribution, wastewater collection and treatment, solid waste management and fire protection.
State of the Art Review–Water Distribution and Sewage Collection in Northern North America
Authors: James F W
Published: May 2018

Reviews development of various methods of water distribution and sewage collection in the North American North and the particular problems facing engineers in carrying out such development work. Examples of various communities and current construction designs and techniques are given. Special emphasis is placed in a shallow buried piped system developed by the author in the Northwest Territories. A brief outlook at the direction of future system designs and planning approaches is given.
Influence of Pretreatment on Anaerobic Stabilisation of Sewage Sludge
Authors: Wechs F
Published: May 2018

In order to intensify anaerobic stabilisation of sewage sludge, several pretreatment processes have been tested. Pretreatment processes investigated are: prepasteurisation, separate acidification, short-term anaerobic digestion. Anaerobic stabilisation was performed in 500 1 digestors. All experiments were performed in parallel to a process operated with untreated raw sludge, the later serving as a reference process. Prepasteurisation turned out to improve solids degradation and dewaterability of the digested sludge, whereas acidification was found to be a rather slow and uncomplete process due to the rate limiting function of hydrolysis of sludge particulates. Using a short-term anaerobic digestion process before anaerobic stabilisation, the easily degradable organics were readily converted to methane. It was shown that this two-stage process improves stabilisation efficiency in comparison to a 20 day one-stage process very significantly.
Design of Anaerobic Digestion of Lime Sludges
Authors: Bell B A , Kobylinski E A
Published: May 2018

Previous work has demonstrated that inhibition of volatile solids destruction during anaerobic digestion occurs at elevated calcium levels. In this work, calcium inhibition has been taken into account in the design of a treatment facility digesting sludges which contain lime from phosphorous removal. A conventional activated sludge treatment facility has been designed along with a facility removing phosphorous by lime addition to primary clarifiers. Unit sizing, costs and energy requirements are compared and discussed.
Operation of Milwaukee's Major Treatment Plants as an Integrated System, U.S.A.
Authors: Graef Stephen P , Cahill Harold P
Published: May 2018

Milwaukee has integrated the operation of its two large secondary treatment plants in a manner similar to that of an industrial complex. Raw materials, intermediate and final products are interchanged between its plants to optimize process capacity, O/M costs and product delivered. The key materials interchanged have been raw wastewater, thickened waste activated sludge and digested sludge. Detailed direct operating and maintenance costs are kept for each process. Indirect costs are also allocated to each process in proportion to its direct costs. Since early 1982 it has been advantageous to transfer waste activated sludge and digested sludge from the plant producing a liquid sludge, AGRI-LIFE, for agricultural application to the plant that produces a heat dried sludge, Milorganite, for commercial sale. The interplant transfer has been by truck, however, the District is now designing a 12 mile pipeline to connect the two plants. Operations and maintenance costs are presented for each of Milwaukee's processes.
The Impact of a Fishing Harbour under Construction on the Distribution and Zonation of the Flora and the Molluscan Fauna of a Tropical Mangrove Ecosystem
Authors: Rambabu A V S , Prasad B V , Lakshmana Reddy D , Rao P N , Balaparameswara Rao M
Published: May 2018

The region concerned is Nizampatnam (15° 54ꞌN; 80° 43ꞌE), a major fishing village in the Krishna estuarine region, located at about 35 km south of Krishna River confluence in South India. This region is traversed by a number of canals (some are from river Krishna) and drains which open into the Bay of Bengal, and is characterized by the presence of swampy ground with dense to scattered mangroves.

The coastal engineering project now under construction (for the last 3 years) at this region, is a Pishing Harbour. The present paper deals with the changes in the distribution, density and zonation of the flora and the molluscan fauna before and during the construction of this engineering project.
Ecological Consequences of Large Harbour-Cities Growth
Authors: Zaremba Peter
Published: May 2018

Ecological balance between man, technic and environment in urbanized areas depends from their spatial and functional structure. An analysis of selected European maritime agglomerations is presented in order to compare ecological consequences of their spatial growth.
Conceptual Ecological Modelling and Interaction Matrices as Environmental Assessment Tools in Coastal Planning
Authors: Knight K D , Dufournaud C , Mulamoottil G
Published: May 2018

Conceptual ecological modelling and interaction matrices are useful techniques for examining complexity and interdependency in ecological systems. Hierarchical models characterize important component resources, biophysical processes, cultural stresses and food chain relationships. Interaction matrices are used to calculate kth order interdependencies that are not readily apparent in the model. An integrated approach, combining ecological modelling and an interaction matrix is applied to the Long Point ecosystem located on the north shore of Lake Erie, Canada. This approach provides a useful precondition to environmental assessment and aids in integrating data for coastal planning.
Effect of Salinity on Reaeration Coefficient of Receiving Waters
Authors: Wen Ching-Gung , Kao Jao-Fuan , Wang Lawrence K , Liaw Chii Cherng
Published: May 2018

A practical method of determining reaeration coefficients would greatly aid design engineers in determining the degree of wastewater treatment required for a proposed effluent discharge. Many previous tidal river and estuary studies emphasized mainly the effects of flow conditions (such as velocity, water depth, turbulent intensity, hydraulic gradient, etc.) and temperature on stream aeration, and the effect of salts was not seriously considered. In this research a new mathematical model of reaeration coefficient considering the effect of salts has been developed for water quality analysis in tidal rivers and estuaries. The reaeration coefficient in saline water, k2s(day−1, base e) at any chloride concentration C(g/l) and at 20°C, can be expressed byin which k2f is the reaeration coefficient in fresh water at 20°C. The correlation coefficient of k2s/k2f and C is 0.88.
Long Term Monitoring of the Macrobenthos of the Upper Clyde Estuary
Authors: Henderson Anne R
Published: May 2018

The sublittoral macrobenthic invertebrate populations of the Upper Clyde Estuary are described. The estuary has a long history of organic pollution. The long term changes in species composition, faunal density and dominance patterns between 1974 and 1980 are presented. The fauna is dominated by brackish, pollution tolerant oligochaetes and polychaetes. Fluctuations in populations can be related to both seasonal variation in environmental conditions and long term improvements in water quality through a reduction in pollution loading to the estuary.
The New Goals and Strategy Adopted in Finland for the Protection of Rivers
Authors: Laikari Hannu
Published: May 2018

Water power plants and artificial lakes have been constructed in the Finnish rivers. Rivers beds have been cleared and the natural lakes discharging into them have been regulated. These works have been carried out primarily to protect cultivated lands from flood and to increase the production of electricity. Dams and dredgings have affected adversely fisheries in the rivers and estuaries. Now the aim is to restrict river construction e.g. by drawing up a relevant water protection programme for the period 1985-95. According to the programme some valuable rivers or sections of rivers are to be totally protected against construction. Cultural and scenic values should be given more weight when decisions concerning river construction works are made. State works should be directed towards maintenance and protection of watercourses instead of construction.
On the Development and Application of Models for Water Quality Management
Authors: Beck M B
Published: May 2018

A brief survey of contemporary problems and future prospects for the development and application of water quality models is given. The main body of the paper is prefaced by a discussion of the way in which developments in modelling have tended to cluster around four types of pollution problem, easily degradable organic wastes, eutrophication, nitrates, and the discharge of toxic substances. The increased importance of uncertainty in the development of models (system identification; model calibration), in the use of models for prediction, and in strategies for the management of water quality is noted. Special attention is also drawn to the need for the analysis of interactions among the four categories of pollution problems, among the traditionally separate components of wastewater treatment, the receiving water body, and water purification, and between long-term planning and short-term operational management. Aspects of planning and operations in the face of contingencies and continually changing priorities for river basin management are discussed.
Synthetic Design Storm and its Relation to Intensity-Duration Frequency Curves
Authors: Urcikán P , Horváth J
Published: May 2018

In the current hydrodynamic rainfall-runoff models the design rainfalls have been applied, the course of which may be simulated by means of several stochastic-mathematical models. The methods applied in developing the design storms with optional time position of the intensity maximum with increasing and decreasing intensity course, expressed by means of exponential equations have been analysed in this paper. The medium value of the intensity maximum time position tmax/td = 0,317 was identified in eight recording raingauge stations from the set of actual rainfalls of a five-year evaluation period.
Univariate versus Multivariate Rainfall Statistics – Problems and Potentials (A Discussion)
Authors: Schilling Wolfgang
Published: May 2018

Problems of conventional (univariate) rainfall statistics are discussed.

A multivariate approach is presented. It takes into account separation of rainfall events as well as the description of intensity sequences. More theoretical support as well as methodological simplification seem necessary.
Effect of Spatial Rainfall Distribution on Sewer Flows
Authors: Schilling Wolfgang
Published: May 2018

Errors in computing flows are caused by uncertainties about input data as well as uncertainties about appropriate models and model parameters.

It is investigated how errors of the input “rainfall”, especially errors in spatial resolution, propagate by computation of sewer flows.

Results of a case study about a sewer system with a catchment area of 2 km2 and ca. 1000 reaches between manholes show−that mean errors in rainfall event depths of about 20 % occur even with five raingages within or close to the catchment−that the errors by disregarding the spatial distribution are amplified rather than damped by the rainfall-runoff transformation and−that using spatially homogeneous rainfall input for flow computations cause systematic errors due to the wrong assumption of spatially homogeneous initial losses and due to dominating directions of storm movement.
An Evaluation of Urban Design Storm Sensitivity
Authors: Wenzel H G , Voorhees M L
Published: May 2018

This paper describes an evaluation of the assumption commonly employed in drainage design that the return period of the rainfall used to design a system is the same as the peak flow produced by that rainfall. Specifically, the sensitivity of the frequency response of three catchments to design storm parameters is examined. Parameters include, hyetograph shape, antecedent soil moisture and rainfall duration. A continuous simulation model is used to compute simulated historical frequency responses for three different long term rainfall records. Design storms are also developed from depth-duration-frequency analysis of the rainfall data. Comparisons are made on frequency graphs. It is concluded that significant parameter sensitivity exists but that an appronriate choice of design storm parameters can produce a design which yields peak flows of the desired return period.
Control Strategies for Bulking Sludge
Authors: Tomlinson E J , Chambers B
Published: May 2018

This paper is a guide to operators and designers of activated-sludge plants. It is designed to present information on bulking in a logical sequence of control measures which can be used to alleviate problems.
Experiences with Oxygen Transfer Testing of Diffused Air Systems under Process Conditions
Authors: Boyle W C , Campbell H J
Published: May 2018

This paper outlines three procedures used to evaluate oxygen transfer under process conditions. Steady state procedures, a radioactive tracer technique and off gas methods are described and methods of calculation are outlined. Two case histories, an industrial waste site and a municipal site, are presented.
Energy Use Considerations in the Activated Sludge Process in Los Angeles, U.S.A.
Authors: Garber WF
Published: May 2018

The City of Los Angeles has four secondary-tertiary treatment plants receiving wastewater flows of 1,590,000, 151,000, 114,000 and 75,000 m3/d. Operational difficulties with fine bubble air diffuser combined with low energy costs had resulted in the use of 4–5% efficiency diffusers as standard design. Increasing energy costs made revaluation of higher efficiency diffusers necessary. Long term treatment plant tests of ceramic domes, fused silica tubes and jet diffusers indicated that long term 8–10% air diffusion efficiency was possible. Energy savings of the order of 40% could be achieved by such diffuser retrofit. The type of diffuser to use would depend upon ambient air and waste characteristics, tank design and the sizing of existing equipment such as blowers.

Data from respirometer studies in operating plants indicated a further 10–30% decrease in energy use could arise from computer control leading to an equalized F/M ration throughout each day. Further tests of this possibility are planned.
Biological Phophorus Removal: Study of the Main Parameters
Authors: Malnou D , Meganck M , Faup G M , du Rostu M
Published: May 2018

The biological phosphorus removal phenomenon has been studied in a modified “Phoredox” type pilot plant. The interpretation of the results obtained was facilitated by batch tests on the sludge. The influence of the duration of anaerobiosis, the presence of nitrates and various organic substances in the anaerobic zone were thus studied successively. The results obtained tend to confirm the hypothesis that biological phosphorus removal is due primarily to the bacterial strain Acinetobacter. Microbiological examination of the sludge has revealed the presence of these bacteria and that of acidogenic bacteria producing volatile fatty acids promoting the growth of Acinetobacter. Pure culture tests have confirmed the possibility of a greater phosphorus storage capability of Acinetobacter.
Thickening Zone and Sludge Removal in Circular Final Settling Tanks
Authors: Günthert FW
Published: May 2018

In horizontal flow final settling tanks mechanical sludge removal methods are necessary to remove the thickened and stored sludge. The frequently designed circular tanks are commonly fitted with travelling bridge scrapers and their performance is given by their velocity, their blades and the number of arms per clarifier. In five final settling tanks investigations were made at different operation parameters, modified scraper velocities and deepening the scraper blade to measure the influence of scraper performance and operation parameters on the thickening zone and the sludge retention time. The results show the relation between sludge return rate and short circuiting flow from the clarifier inlet to the sludge drawoff. The thickening zone is mainly influenced by the sludge volume flow and the sludge volume loading. The positive effect of higher scraper velocities and deepening the scraper blade on the thickening depth was found.
Improving the Performance of Houston's Southwest Wastewater Treatment Plant, U.S.A.
Authors: Garrett M T , Ma Josten , Yang William , Hyare Gurdip , Norman Teresa , Ahmad Zaki
Published: May 2018

In 1981, the City of Houston's Southwest Wastewater Treatment Plant (144,000 m3/d) was experiencing occasional afternoon bulking with loss of solids to the effluent. The plant employs sludge reaeration with about even allocation of tank volume to mixed liquor and return sludge aeration. A dynamic model of solids transfer from influent to mixed liquor to settling tank to return sludge aeration and wasting was developed for use on a desk-top computer.

The model predicted that a counter-intuitive reduction in the return sludge rate would redistribute the solids to less in the mixed liquor and more in the sludge reaeration tanks, but would also generate a sludge blanket during the transition period. However, if the change were made when there would be several low-flow days, then the blanket would stay within the settling tanks.

The Thanksgiving Holidays of 1981 were chosen for the change in the return sludge rate. Low flow occurred as expected and there was no loss of solids. The effluent suspended solids improved as expected, but the SVI also improved from 172 ml/g to 72 ml/g. The reduction in the return sludge flow rate allowed extra hydraulic capacity for storm flows. The improved control of solids was demonstrated by simulating a storm flow of 4.0 m/h overflow rate by taking settling tanks out of service with resulting effluent TSS of less than 20 mg/L.
Fluidized Bed Technology in the Anaerobic Treatment of Forest Industry Wastewaters
Authors: Salkinoja-Salonen M S , Hakulinen R , Silakoski L , Apajalahti J , Backström V , Nurmiaho-Lassila E.-L
Published: May 2018

The reasons for studying anaerobic fluidised bed technology for the treatment of forest industry wastewaters are twofold: the very large volume enforcing hydraulic loading beyond the limits tolerated by conventional anaerobic techniques and the low nutrient need compared with aerobic methods. In this paper we describe the results obtained for four different pulp mill waste streams: sulfite bleaching and evaporator condensate wastewaters , wastewater from displacement bleaching of kraft pulp and from thermomechanical pulping. We found that all four could be purified anaerobically within a hydraulic detention time of ≤12h and with a treatment efficiency of 3 to 4 kg of CODCr removed m−3 d−1. 80 to 90% of the CODCr of the thermomechanical pulp mill wastewater and evaporator condensate could be removed during anaerobic treatment, yielding ≥0.5m3 of biogas kg−1 CODCr removed. The bleaching wastewaters needed aerobic post-treatment and yielded little or no biogas.
Operational Experience with Anaerobic/Aerobic Treatment System for Paper Mill Wastewater
Authors: Priest Charles J
Published: May 2018

The paper mill located in Indiana began operation in 1975. The initial effluent treatment system was aeration stablization and settling basins. The waste system discharged to the Wabash River. Primary solids from the clarifier are recycled to the mill. Secondary solids from the settling basins were applied to farm land.

Original B.O.D. load entering the first aeration basin was 4,000 Kg per day @ 3786 cubic meters water per day. Present raw waste discharge is about 11,000 Kg per day @ 3786 cubic meters. The production rate has increased from 318 to 545 metric tons per day. The designed waste treatment system was 240 horsepower of surface aeration. In an attempt to keep up with the increasing B.O.D. load, surface aeration horsepower was increased to 450. This combination resulted in greater production of secondary solids (biomass).

An anaerobic pilot plant study was conducted in 1978. Based on the study's results, the Indiana Water Pollution Control Division approved conversion of the Newport effluent treatment system to an anaerobic/aerobic system. In November 1978 we converted one aeration basin to an anaerobic cell. (The first paper mill in North America to have such a system). The other aeration basin received a total of 300 horsepower available aeration. From November 1978 to April 1979 we learned the operational controls and modified the anaerobic cell. In May 1979 the anaerobic pond efficiency was 80% B.O.D. reduction. Total effluent system efficiency has averaged 98% for the past 3 years.

Aerobic biomass generation has been reduced 80 to 90% as measured by settleable solids. Recent studies and project modifications will reduce the aerobic biomass even further.

In changing to anaerobic-aerobic treatment a seventy percent production increase has been possible without expansion of the wastewater treatment facilities.
Anaerobic Fermentation of Sulphite Pulp Mill Effluents
Authors: Geller A , Göttsching L
Published: May 2018

Despite internal measures modern sulphite pulp mills are still releasing considerable amounts of effluents loaded with organic pollutants. The main sources are the spent liquor evaporator and the bleach plant. In the laboratory scale two anaerobic systems (stirred fermentation vessel and fixed bed reactor) were tested for the fermentation of effluents from a magnesium sulphite mill. The efficiency of the fixed bed reactor was substantially better than the efficiency of the fermentor. Upon treatment of evaporator condensates, COD removal exceeded 90 % with corresponding BOD removal of 99 % after a residence time of 36 hours, whereas the necessary residence time for the same results was about 16 days in the fermentor. The methane production increased with increasing loading, reaching a maximum at a COD loading rate of 7 kg.m−3 .d−1. BOD elimination from bleaching effluents was better than 95 % with fixed bed reactor, whilst COD removal remained below 50 %. All experiments were run over a period of more than two years, exhibiting stability of the fixed bed filter, low needs for maintenance and negligible biomass generation.
Influence of Sulfur Compounds on Biogas Production from Forest Industry Wastewater
Authors: Puhakka J A , Rintala J A , Vuoriranta P
Published: May 2018

Various inorganic sulfur compounds and lignosulfonate were studied with respect to their effect on biogas production from synthetic wastewater simulating sulfite evaporator condensate. The sulfur balance during the anaerobic degradation was also investigated. In biogas production assay tests municipal digester sludge was used as seed material.

Differences in sulfur inhibition of methanogenesis between various oxidation states of inorganic sulfur were detected. Sulfate and sulfide in concentrations 100 mg S/l had no effect whereas sulfite, thiosulfate and dithionite caused a lag-period in biogas production. Reduced biogas production was observed even with the addition of 1000 mg S/l as SO=4, SO=3 and S2O=3. Dithionite was the most toxic compound investigated. Sodiumlignosulfonate in concentrations 5-15 g/l has a supplementary increase in biogas production. Inorganic sulfur compounds were partially reduced to sulfide in anaerobic conditions.
Rotavirus Survival in Raw and Treated Waters and Its Health Implications
Authors: Sattar Syed A. , Raphael Roderick A. , Susan Springthorpe V.
Published: May 2018

Rotaviruses are among the major causes of acute gastroenteritis in man as well as a variety of animals. Although not much is known about the mechanisms of transmission of these viruses in nature, fecally-contaminated water appears to play a role in this regard. This study was, therefore, aimed at determining how well rotaviruses could survive in water. Calf rotavirus (strain C-486) grown in MA-104 cells was used as a model in this study. Samples of raw (RW) and municipally-treated tap water (TW) from the Ottawa River (Ontario, Canada) were contaminated with the virus to give a final concentration of approximately 5.0 × 104 plaque forming units (PFU)/ml. The virus-contaminated water samples were held either at 4°C or 20°C in the dark for a total of 64 days. In TW held at 4°C, there was no significant drop in the virus titre even after 64 days, whereas, at 20°C the titre was reduced by nearly 2-logl0 over the same period. In RW a 3-10gl0 drop in PFU occurred in 16 and 32 days at 20°C and 4°C, respectively. These data indicate that rotaviruses could survive long enough in the water environment to give water a considerable potential as a vehicle for their spread.
Genomic Analysis of RNA Viruses Isolated from Water
Authors: Hodgkiss M. T. , Moodie J. W.
Published: May 2018

Polyacrylamide gel electrophoresis (PAGE) was used to distinguish human from animal rotaviruses and type four reoviruses isolated from sewage effluent. A simple method of extracting the ds RNA was used without resorting to viral purification. The electrophoretic patterns were clearly discernible after silver nitrate staining. The human rotaviruses were of different strains and could be easily distinguished from the simian agent. All four reoviruses were of the same type, Type 3, but appeared to be of a different strain from the control type 3 with which they were compared. The feasibility of building a collection of various animal and human rota- and reovirus genomic profiles is discussed.
Detection of Hepatitis a Virus in Drinking Water by Enzyme -Immunoassay Using Ultracentrifugation for Virus Concentration
Authors: Schnattinger A.
Published: May 2018

Ten litres of tapwater were seeded with 200 µl (8×108 HAV particles) of a commercial (Organon Teknika) suspension of hepatitis A virus.

Following WALTER and RÜDIGER (1981), the contaminated tapwater was treated with a two-stage technique for concentration of viruses from solutions with low virus titers.

The two-stage technique consists of aluminium hydroxideflocculation (200 mg/l Al2(SO4)3. 18 H2O, pH 5,4-5,6) as first stage, the second stage of a lysis of aluminium hydroxidegel with citric acid/sodium citrate-buffer (pH 4,7; 1 ml/l sample), separation of viruses from the lysate by ultracentrifugation and suspension in 1 ml phosphate buffer solution (pH 7,2).

A commercial solid phase enzyme-linked immunosorbent assay (ELISA) was used for the detection of HAV.

HAV was detecterl in the 10.000:1 concentrates, but not in the seeded 101 samples. Approximately 4×108 of the inoculated 8×108 HAV particles were found in the 1 ml concentrates.

The efficiency of detection is about 50%, the virus concentration 5000-fold. Although the percentage loss of HAV in comparison with concentration by means of membrane filtration is similar, the ultracentrifugation method yields a larger sample/concentrate ratio, so that smaller amounts of HAV can be detected more efficiently because of the smaller end-volume.