bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation Model for Prediction of BOD Removal Rate in Streams
Authors: Kawashima Hiroyuki , Suzuki Motoyuki
Published: May 2018

A numerical simulation model is developed in order to predict BOD removal rate in streams on the basis of mass transfer and biochemical reaction kinetics. The double layer model of a flat aerobic and anaerobic bacterial film applies to BOD and DO balances in a stream. A relationship which relates energy dissipation, BOD and DO concentrations in streams and surface area available for attached biomass to the BOD removal rate per unit area is proposed. The different oxygen consumption rates observed in actual streams can be explained by using the model proposed here.
River Catchment Management: An Approach to the Derivation of Quality Standards for Farm Pollution and Storm Sewage Discharges
Authors: Whitelaw K. , Solbé J. F. de L. G.
Published: May 2018

Water quality in certain UK rivers has deteriorated due to episodic pollution from farms and storm sewage overflows. In response to the need to further our knowledge of the effects of episodic events on water quality and to derive appropriate quality standards, WRc Environment has established a number of case studies involving both field and laboratory investigations. This paper describes the approach to standard setting which has been adopted in these studies. Two complementary approaches are used: the first based on examining published toxicity data in order to derive working draft standards; the second is the testing of these draft standards against the performance of living organisms.
Estimation of the Readily Oxidizable Organic Matter Reserve and its Effect on the Intensity of Organic Matter Destruction by Bacteria in the Danube River
Authors: Kh Bashmacova I.
Published: May 2018

During an international expedition devoted to studying the River Danube in March 1988, the influence of readily oxidizable organic matter on the destruction of organic matter by bacteria was investigated. Readily oxidizable (labile) organic matter (LOM), LOM turnover rate, and concentration of particulate organic matter (POM) were quantitatively analysed.

It was found that the minimum values of the parameters studied occurred in the Middle Danube, i.e., the Bulgarian and Yugoslavian stretches of the river. Self-purification did not exceed 23 days. Regarding the Upper Danube (i.e., Austria, Czechoslovakia, and Hungary), higher LOM and POM concentrations, bacterial respiration intensity, and self-purification rates (15 days) were observed. However, the maximum values were found in the Kilia delta (USSR). This was attributed to the great amount of organic matter (OM) in particulates contributed from the upper reaches of the river. At the same time, the Soviet stretch of the Danube was characterized by the most intense processes of destruction of OM associated with aggregated bacterioplankton, which gave higher self-purification rates (up to 9 days).
Some Aspects of Pollution of the Danube
Authors: Tarasova O. G. , Tsvetkova A. M. , Osipov L. F. , Arsan O. M. , Klujev N. A.
Published: May 2018

Residues of organochlorine pesticides in the Danube were studied during the 1-st International Danube Research Expedition. Some other pollutants were identified as well. The levels of organochlorine pesticide pollution have decreased significantly as compared with background levels in 1979-1980’s.
Sorption of Organic Contaminants
Authors: Rao P. S. C.
Published: May 2018

Sorption of organic contaminants plays a dominant role in their rate of transport through porous media such as soils, sediments and aquifers. The rate of abiotic and biotic transformations may also be significantly altered by sorption. This paper presents a brief overview of the current knowledge base on sorption of organic contaminants by natural sorbents, and examines several emerging issues that need further study. Partitioning into sorbent organic matter is viewed as the predominant process for sorption of nonpolar organics from aqueous solutions, and various methods have been proposed for estimating sorption/partition coefficients. Recent experimental and theoretical work has established a basis for predicting organic contaminants sorption from polar mixed solvents (mixtures of water and miscible cosolvents). Data on sorption of ionic and ionogenic organic compounds (e.g., phenols, amines) are limited, and initial efforts are underway to develop models for such sorbates. There also has been a recent resurgence of interest in studying vapor-phase sorption and transport of volatile organic compounds. Much of the early work on sorption dealt with equilibrium sorption, but considerable advances have been made in characterizing and predicting sorption nonequilibrium as well. Molecular-scale measurements are needed in order to provide direct, unequivocal evidence for selection among several contending phenomenological models proposed for describing sorption equilibrium and kinetics.
Adsorption of a Homologous Series of Alkylbenzenes to Mineral Oxides at Low Organic Carbon Content Using Headspace Analysis
Authors: Perlinger Judith A. , Eisenreich Steven J. , Capel Paul D. , Carr Peter W. , Hag Park Jung
Published: May 2018

A homologous series of alkylbenzenes was sorbed to well-characterized mineral oxides in batch experiments to elucidate mechanisms of sorption in the absence of natural organic matter. Sorbed concentration was determined by measuring the headspace concentration in a closed vessel partially filled with a water/alkylbenzene/solid slurry. Partitioning of dissolved alkylbenzenes to sorbed alkylbenzenes was observed at high sorbed concentrations. At low sorbed concentrations, the mechanism was surface adsorption limited by the surface area of the solids. Enhancement of the adsorption of individual compounds was observed when alkylbenzenes were sorbed as a mixture.
Mobility of Soluble and Non-Soluble Hydrocarbons in Contaminated Aquifer
Authors: Ducreux J. , Bocard C. , Muntzer P. , Razakarisoa O. , Zilliox L.
Published: May 2018

After the contamination of an aquifer by petroleum products, the residual oil trapped is a constant source of pollution by the entrainment of the most soluble hydrocarbons. By studying the exchanges of residual hydrocarbons between oil-water-air and soil, we pointed out that the liquid/gas exchange is the major factor of retention of soluble alkanes masking the adsorbing materials effects. For the soluble aromatic hydrocarbons, the main phenomenon observed is the liquid/solid exchange. The role of residual air is no more preponderant.

The residual contamination of the vadose zone thus plays a preponderant role in the long-term pollution of a groundwater table. It is thus imperative to implement methods to prevent such harmful effects. The use of surfactants, by lowering the oil/water interfacial tension seems to be a new and effective method. Their adsorption into a natural matrix was studied with different porous substrates (sand, sand/silt). Their retention on sand is poor, but it increases with silt content. This is mainly due to a cationic exchange (Ca2+/Na+). In order to avoid this phenomenon a salt preflush by a 10 g/l Na Cl solution is effective. That allows a gas-oil recovery enhancement by reducing loss of surfactant in soil. Moreover, a surfactant partition between oil and water is underscored. A better understanding of these parameters would lead to the optimizing of the enhanced drainage technique for recovering residual oil trapped in an aquifer.
Enzymatic Oxidation of Some Substituted Phenols and Aromatic Amines, and the Behaviour of Some Phenoloxidases in the Presence of Soil Related Adsorbents
Authors: Claus H. , Filip Z.
Published: May 2018

When considering phenoloxidases as agents in treating chemical pollution in soil and groundwater environments, possible effects of the specific soil constituents and environmental factors on these enzymes should be investigated. In our invitro experiments various aromatic amines and alkyl or halogensub-stituted phenols were oxidized by a laccase and a tyrosinase. Oxidation of the latter compounds was accompanied by partial dehalogenation. However, the activity of phenoloxidases was differently inhibited by the presence of clays and clay-humus complexes. Also pH and temperature exerted different effects on the phenoloxidases.
Fate and Transport of Alachlor, Metolachlor and Atrazine in Large Columns
Authors: Alhajjar B. J. , Simsiman G. V. , Chesters G.
Published: May 2018

14C ring-labelled atrazine, alachlor, and metolachlor were surface-applied at 3.14 kg a.i./ha in greenhouse lysimeters containing two soils in an ongoing experiment. Bromide (Br) – a conservative tracer – at 6.93 kg/ha as KBr and nitrate-nitrogen (NO3-N) at 112 kg/ha as KNO3 were mixed with each herbicide and surface-applied. Growth of Red top (Agrostis alba) was established in each column (105 cm long and 29.4 cm i.d.). The experiment consisted of 12 columns (2 soils × 3 herbicides × 2 replicates) each fitted with four sampling ports for leachates, a volatilization chamber, and an aeration and irrigation system. Volatile materials are being trapped directly in solvents. One column replicate was dismantled for soil and plant analyses. Columns of Plainfield sand and Piano silt loam treated with alachlor and metolachlor were sampled after 23 and 28 weeks, respectively; the atrazine columns after 35 weeks. Herbicide residues are determined by liquid scintillation counting, extracted and separated by thin-layer chromatography using autoradiographic detection. Volatilization was ≤ 0.01% of the amount of herbicide applied. The order of herbicide mobility was alachlor > metolachlor >> atrazine. As many as 8 to 12 alachlor metabolites and 2 to 6 metolachlor metabolites were separated in leachates.
Aerobic Treatment of Ammonium Fertilizer Effluent in a Fixed-Film Biological System
Authors: Hamoda M. F.
Published: May 2018

A fertilizer plant effluent that contains high levels of ammonia was treated using a four-stage, fixed-film aerated bioreactor in a pilot plant design. Ammonia concentrations in the influent wastes were maintained up to 480 mg L−1 NH3-N and reactor hydraulic loading rates were varied up to 0.14 m m−2 d−1 during continuous operation. Process performance was satisfactory and nitrification rates were determined based on steady-state operation. Ammonia removal was not inhibited by the organic content and the high ammonia concentrations of the influent waste. Removal rates obtained at 20°C ranged between 0.49 to 3.23 NH3-N per day per g volatile solids of attached biomass, which are considerably higher than those reported for the activated sludge and RBC processes under similar operating conditions. This could be attributed to the good oxygen transfer capacity and the large quantity of attached biomass attained in the studied reactor. The rate of nitrification in this system apparently follows first-order kinetics. Design relationships were developed for nitrification of fertilizer effluent and an optimum design loading of 25 g NH3-N m−2d−1 is recommended to achieve higher than 90% ammonia removals.
Effect of Temperature on Anaerobic Filter Treatment of Dairy Wastewater
Authors: Viraraghavan T. , Kikkeri S. R.
Published: May 2018

An 11-month study was conducted to compare the performances of three laboratory plastic medium upflow anaerobic filters operating at 12.5°C, 21°C, and 30°C, treating dairy wastewater. Two of the reactors were started at 21°C and the third at 30°C. Steady-state operation of the three reactors was carried out at different hydraulic retention times (HRTs) of 1 to 6 days. It was found that the start-up of anaerobic filters was possible at 21°C without any adverse effect on its future performance. Temperature effects on organic removal efficiency were not found to be pronounced at high HRTs. The anaerobic filter at 30°C consistently achieved higher levels of performance compared to the other reactors at 12.5°C and 21°C. The anaerobic filter operating at 12.5°C was the most affected by changes in HRT. At an HRT of 4 days, average COD removals in the three anaerobic filters were approximately 92%, 85%, and 78% at 30°C, 21°C, and 12.5°C respectively. The volume of methane generation (m3/kg COD removed) was lower at lower temperatures; the amount of methane in biogas was found to be higher at lower temperatures.
Combined Treatments of Urban and Olive Mill Effluents in Apulia, Italy
Authors: Boari G. , Mancini I. M.
Published: May 2018

The effluent from olive mill plants (OME) presents a seasonal problem, as although small in volume it has very high organic content, and in consequence it is particularly difficult to meet Italian law discharge limits. This problem has been carefully studied in Apulia where, during the olive milling season, organic pollution exceeds that from domestic use by a factor of three. Preliminary research allowed the estimation of organic load per ton of milled olives, and the comparison of the effectiveness of feasible treatment processes. The results have been utilized in the Water Reclamation Plan of the Apulia Region (WRP).

This Plan permits the discharge of OME into public sewers only when its contribution is less than 20% of urban wastewater's (UW) organic load, or provides the transport of a controlled amount to treatment facilities, over a period ranging from 100 to 300 days.

Results of full-scale and pilot biological treatment plants for combined UW and OME effluents are reported, together with the main project parameters. Anaerobic processes are more economical but their successful operation needs to be confirmed on full-scale plants.
Factors Influencing Formation and Maintenance of Granules in Anaerobic Sludge Blanket Reactors (UASBR)
Authors: Kosaric N. , Blaszczyk R. , Orphan L.
Published: May 2018

Four, 20 L UASB reactors were operated under different hydrodynamic regimes continuously for more than 150 days. The influence of superficial liquid upflow velocities over the range 0.2 5 to 1.5 m h−1, on granule activity and characteristics was investigated, maintaining constant temperature (35°C), and volumetric loading rate (6.2 g COD L−1 day−1). Reactor pH, COD removal, VFA concentration, bed height and gas production were continuously monitored and evaluated. It was found that hydrodynamic conditions can influence the size of granules, and their settling characteristics. Low upflow velocities (0.25 and 0.5 m h−1), are favourable for granule growth and accumulation. At high upflow velocities (1.0 and 1.5 m h−1), no sludge accumulation and disintegration of larger granules were observed.
Sludge Management and Disposal Practices of the County Sanitation Districts of Los Angeles (USA)
Authors: Carry Charles W. , Stahl James F. , Hansen Blair E. , Friess Philip L.
Published: May 2018

The County Sanitation Districts of Los Angeles County (Districts) operate a network of six wastewater treatment plants called the Joint Outfall System (JOS) which treat a wastewater flow of approximately 22.3 m3/s (510 mgd). Centralized sludge processing for the JOS is performed at the largest plant in the system, the Joint Water Pollution Control Plant (JWPCP). Sludge is anaerobically digested, dewatered in scroll centrifuges, and either composted and sold to a private company which produces bagged soil amendment products or codisposed with refuse at a site which recovers energy from landfill gas with a 46 net megawatt steam turbine power plant. Future sludge handling will include dehydration followed by incineration for most of the sludge now landfilled. JWPCP accomplishes an environmentally sound and cost effective balance of solids disposal to the air, land and water.
Moisture Distribution in Sludges
Authors: Tsang K. R. , Vesilind P. A.
Published: May 2018

By studying the drying characteristic curve, the moisture in sludge is classified into four categories: free moisture, interstitial moisture, surface moisture and bound moisture. The effects of three dewatering procedures: gravity drainage, vacuum filtration, and centri-fugation, as well as chemical conditioning by a cationic polymer, and physical conditioning by freeze-thaw on the moisture distribution, are investigated. It is found that the dewatering procedures studied can only remove part of the free and interstitial moisture; surface and bound moisture are not affected. Part of the free and interstitial moisture also remains with the sludge cake, which can be considered as the inherent inefficiency of the dewatering process. The complete removal of all the free moisture can be considered as the theoretical best performance any mechanical dewatering device can achieve. Polymer addition is found to improve the dewaterability of the sludge by reducing the inherent inefficiency, primarily by reducing the amount of free moisture retained in the cake. Freeze-thaw is found to effect the removal of free, interstitial and surface moisture, bringing about a dramatic increase in dewaterability. The treated sludge cake drains readily and retains no free moisture.
Cost-Effective Dewatering of Municipal Treatment Plant Sludges Using Belt Presses
Authors: Clarke W. N. , Hodges Ed. , Ooten Robert J.
Published: May 2018

An evaluation was conducted at the County Sanitation Districts of Orange County (CSDOC) which led to the purchase and installation of the belt filter presses currently in use. A selection process was made including pre-qualification of bidders after an exhaustive nationwide search and study of all known existing belt filter press facilities. Subsequent methods were employed for purchasing belt filter presses of the same make and manufacturer. Operating experiences and maintenance costs as well as minor modifications which were found to be desirable were documented. The paper will discuss in some detail the design criteria, capacity, polymer addition system, performance at CSDOC Plant No. 1 and Plant No. 2, sludge characteristics and the effect of chemical conditioning. Discussion regarding operation and maintenance criteria, such as staffing, operating and maintenance modes, operational checks, belt life and belt specification, safety ventilation required for the removal of odorous materials and hydrogen sulfide, data recording, and polymer dosing is included. Cost considerations, including capital costs, as well as operating and maintenance costs for the past five years are covered.
Commercialization of Pressurized Electroosmotic Dehydrator (PED)
Authors: Kondoh S. , Hiraoka M.
Published: May 2018

Application of electroosmosis to conventional filter press dehydrators has been studied to decrease water content in the sludge generated from waste water treatment process. Experiments realized the reduction of water content in the biological excess activated sludge down to 50-60%, which had never been achieved by the conventional dewatering method. The new method has been commercialized by pre-concentration of the excess activated sludge, addition of electrolyte, and development of special carbon electrodes. Moreover, observation using a scanning electron microscope enabled us to demonstrate the suitability of the PED process to the excess activated sludge.

The newly-developed dehydrators and processes have been operating successfully at three commercial plants for the first time in the world.
Modified Polyurethane Carriers for Biochemical Waste Water Treatment
Authors: Pascik Imre
Published: May 2018

For aerobic and anaerobic waste water treatment, modified porous polyurethane carriers with different ionic charges and surface activities have been synthesized in order to investigate the relations between their material properties and biodegradation efficiency.

It has been found that the modified carriers are more effective than the non-modified equivalents. Continuous anaerobic experiments in the laboratory and on pilot plant scale have shown that the use of this type of carrier leads to higher degradation rates and process stability in the treatment of persistent bleaching effluents obtained in sulphite pulp production.
A Mathematical Model for Rotating Biological Contactors
Authors: Gujer W. , Boller M.
Published: May 2018

A mathematical model for aerobic and anoxic degradation of organic components as well as nitrification in RBC systems is developed and verified against experimental experience after primary, secondary and tertiary treatment. The model considers biomass distribution within the biofilm as well as along a reactor chain. The simulation program is not yet ready for practical application but may well prove to become a design tool in the future.
Operating Experience with Large Random Packed Biofilm Reactors
Authors: Orr P. , Lawty R.
Published: May 2018

The intermittent operation of large biofilm reactors with high influent suspended solids has sometimes resulted in the production of offensive odour. Covering the reactors and treating the off gas may solve the odour problem but excessive biomass accumulation within the media must also be avoided. Methods of biomass control at the Manukau Sewage Purification Works, Auckland, New Zealand, are discussed with particular reference to the use of high irrigation intensity and its effect on BOD removal efficiency under conditions of very high load variations.
Expanded Bed Treatment of Complete Recycle Aquaculture Systems
Authors: Jewell William J. , Cummings Robert J.
Published: May 2018

The popular dietary shift to fish and the limits on natural fish populations have caused rapid growth in fish farming and aquaculture. Optimized aquaculture systems are attempting to use as complete recycle as possible to obtain maximum control over the fish populations, and limit water and energy requirements. Closed systems aquaculture is severely limited by water quality since pollutants accumulate in the system. This study examined the possibility of simultaneous BOD5 reduction, SS removal, nitrification and denitrification with an expanded bed in complete recycle growth systems with Atlantic salmon and brook trout. The fish rearing tank volume was 10 m3 and the expanded bed volume was 2.6 m3. The total duration of the study was 180 days.

The expanded bed developed a film capable of nitrification and denitrification within 40 days. After this time, the SS and BOD were maintained at less than 6 mg/l. Ammonia, nitrates, and nitrites were below detectable levels, thus confirming the simultaneous one-stage removal potentials. Maximum nitrogen removal rates of 40 mg per liter of AFEB per day are similar to the higher removal rates predicted for maximum removal efficiencies at bulk solution ammonia-nitrogen concentrations of 0.5 mg/l. Dissolved oxygen concentrations in the expanded bed appear to be the most sensitive control parameter for these simultaneous reactions.

This one-stage pollution control process for complete recycle aquaculture would be useful in both freshwater and seawater applications. The system is easily modularized for fish rearing tank capacities of 1,000 to more than 10,000 kg. The treatment system volume would be less than half the rearing volumes at low fish densities and low ammonia concentrations (less than 0.5 mg/l of ammonia nitrogen).
Operational Performance of Package Sewage Treatment Plants in North West England
Authors: Greaves F. E. , Thorp B. , Critchley R. F.
Published: May 2018

North West Water Authority owns and operates 21 rotating biological contactors and 7 package extended aeration plants. The rotating biological contactors have performed effectively, reliably and cheaply. Site visits are required up to three times a week for simple routine maintenance, whilst desludging is required periodically, typically 3 to 9 times a year. The prefabricated extended aeration plants generally perform well but typically with more demanding operational requirements and higher capital and electricity costs than rotating biological contactors. The Authority has concluded that the rotating biological contactor is the primary option for sewage treatment for small communities.
Onsite Wastewater Treatment with Intermittent Buried Filters
Authors: Schudel Paul , Boller Markus
Published: May 2018

A few intermittent buried sand filters have been constructed in Switzerland for the onsite treatment of small wastewater sources. The good experiences to date will certainly favour a more frequent application in the future. Investigations of the hydraulic behaviour and the removal efficiency, especially in one filter during and after a hydraulic flush, showed that the hydraulic load per dosing interval should preferably not be larger than 10 1/m2,interval. Tracer experiments as well as the analysis of pollutants during the intervals revealed considerable quality fluctuations along the hydraulic peak discharge depending strongly on the instantaneous hydraulic dose. Furthermore, maturation periods of several months are necessary in order to reach a maximum steady state performance that usually includes full nitrification. Besides detailed information on the hydraulic behaviour, a series of performance data of different buried filters gives an overview of the concentrations and the removal rates observed for organic matter and nitrogen compounds.
Effect of Biological Clogging on Infiltration Rate in Soil Treatment Systems
Authors: Kawanishi Takuya , Kawashima Hiroyuki , Chihara Kazuyuki , Suzuki Motoyuki
Published: May 2018

Effect of biomass on the soil hydraulic conductivity was clarified on andosol soil. The approximate value of the maximum allowable density of biomass was determined, which corresponds to the minimum hydraulic conductivity of the clogged andosol soil. On the basis of these values and the mass balance of the substrate, the relation among substrate concentration, thickness of clogged zone and the percolation rate was discussed.

In addition, a numerical model was constructed, and the biomass growth and the change of permeability were simulated. Calculated results were compared with the results of two-dimensional infiltration flow experiments. By using the model, the conditions to avoid infiltration failure were determined.
Suitability of Different Biological Sewage Treatment Systems
Authors: Bucksteeg K.
Published: May 2018

Small wastewater treatment plants suffer from higher specific peak loads and less qualified operational services. Therefore, small plants need special rules for design, construction and operation on the basis: the smaller, the less sophisticated - the less sophisticated, the better! Advantages and disadvantages as well as process stabilities of activated sludge plants with long time aeration, trickling filters, rotating bio-contactors and different pond systems are described and compared to each other. Technical plants should be preferred for serving housing estates when separate sewerages exist. Ponds are a favourable solution for villages with combined sewerages, especially such in rural areas. Emergent hydrophyte treatment systems (reed beds) are considered as still being under development.

Practice proves that newly developed, highly sophisticated technical systems tend toward simplification, and small reaction volumes or areas are increasing when applied under practical conditions.
Nutrient Removal in Small Wastewater Treatment Plants
Authors: Skov Olesen Niels
Published: May 2018

In some areas of Denmark nutrient removal is required even for very small wastewater plants, that is down to 500 pe (pe = person equivalents). The goal for the removal is 80% removal of nitrogen and 90% removal of phosphorus, or in terms of concentrations: 8 mg nitrogen/l and 1.2 mg phosphorus/l. The inlet concentrations are typically 40 mg N/l and 10 mg P/l. The paper presents the results from two such plants with a capacity of 800 pe. Phosphorus removal is made by simultaneous precipitation with ferrous sulphate. Nitrogen removal is carried out using the recirculation method. Both plants were originally rotor aerated oxidation ditches. They have been extended with a denitrification reactor and a recirculation pumping station. At present both plants have been in activity for about 3 years and with satisfactory results. Average concentrations of nitrogen (summer) and phosphorus is 7 mg/l and 0.9 mg/l respectively.

Nitrogen removal seems to be a practical solution on these small plants. It is,though, sensitive to temperature and highly oxidized rain water. Phosphorus removal seems to be an easily run and relatively non-sensitive technique at least when using simultaneous precipitation.
Qualitative and Quantitative Characterization of Waste Water for Small Communities
Authors: Pujol R. , Lienard A.
Published: May 2018

An understanding of the waste water nature, from both the qualitative and quantitative points of view, is a fundamental factor in the selection of treatment techniques and their subsequent operation. This is even more so in the case of small communities whose discharges are more subject to variation. An analysis of French data in this field provides values for small communities in rural areas (the majority). So far as other communities are concerned there are three examples which particularly illustrate the effects of the different factors (way of life…) on specific loads.
Treatment of Oily Cafeteria Wastewater by Single-Phase and Two-Phase Anaerobic Filter
Authors: Hanaki Keisuke , Matsuo Tomonori , Kumazaki Katsuo
Published: May 2018

Cafeteria wastewater containing about 30% of lipid on COD basis was treated at 20°C by laboratory-scale anaerobic filter in single-phase system and two-phase systems. Stable COD removal (about 80%) was achieved in spite of large fluctuation in influent COD concentration (normal range of 1,300 - 2,500 mg−l) both in the single-phase system (hydraulic retention time (HRT) longer than 1.3 d) and in the two-phase system (HRT longer than 3.3 d). The single-phase system gave better effluent quality than the two-phase system because the former entrapped suspended solids better than the latter. However, material balance revealed that methane conversion from removed COD was higher in the two-phase system than the single-phase system. The single-phase system perhaps removed lipids by entrapment with filter media without biodegradation, and this might cause clogging problems in long-term operation. The two-phase system is recommended since it degrades lipids better than the single-phase system.
Fully Biological Wastewater Treatment without Energy Consumption
Authors: Csépai L.
Published: May 2018

By two Sewage Treatment Plants it is demonstrated that a fully biological wastewater treatment without external energy supply is possible provided there is a sufficient natural gradient to guarantee a free flow through the entire plant. Both plants have now been in operation for more than 2 years. Test results show a very good purification efficiency. Elimination of BOD5 is over 93%, of COD 84%, of TOC 86%, of NH4 66 % and that of nitrogen totals 29%. The results of the two-year operation of both plants prove that also smaller units allow for meeting all requirements to obtain a good purification efficiency. Especially pre-settling and final clarifying ponds with interposed trickling filters represent a very simple but economic addition to the ample variety of modern wastewater techniques. It has also been demonstrated that, when planning wastewater treatment plants, every effort should be made to adjust the hydraulic longitudinal section to the existing area conditions, even at the risk of increased building costs. As far as economic considerations are concerned, a unit operating without energy consumption certainly proves advantageous. At the same time it offers a running guarantee, which is equally important, especially in case of smaller units. Particularly if local communities experience prolonged economic difficulties such considerations gain increasing priority. In addition to all these advantages the plants show a high buffering efficiency, minimum maintenance requirements and very low running costs.
Small Domestic Sewage Works of the Carlsbad-Type
Authors: Haindl K.
Published: May 2018

The biological sewage works of Carlsbad-type are situated underground. Oxidation of the biological suspension is based on the ring jump principle with creation of a spiral motion in the activated sludge tank. The ring jump, a hydraulic phenomenon on the transition of annular to fullprofile flow, entrains air and ensures a high oxygen transfer. The basic hydraulic and oxygen input equations are presented; the results of long term monitoring of the treatment effect are in all seasons permanently high. The sewage works are situated in close vicinity to living houses, under parks, gardens, in mountain regions, do not interfere with the landscape, are odour- and noiseless; their construction is done within a week, the only moving component is the pump, their operation and attendance are simple, investment costs low.
The Olifantsfontein Nutrient Removal Plant
Authors: van Huyssteen J. A. , Barnard J. L. , Hendriksz J.
Published: May 2018

The paper describes the upgrading of an existing trickling filter (TF) plant by adding a new activated sludge (AS) plant in order to remove nutrients from the combined effluent of both plants. In spite of the low COD/TKN ratio, good nitrogen and phosphate removals were obtained in the three-stage Bardenpho (AS) plant. This is at variance with the University of Capetown mathematical model which predicted that nutrient removal in this plant would not be possible due to predicted recycle of nitrates to the anaerobic basin. The results showed that the average effluent phosphate was below 1 mg P/ℓ while the ammonia and nitrates could be controlled to values well below the limits of the South African General Standard. Possible reasons for the anomaly are given.
Upgrading of Wastewater Treatment Plants for the Reduction of Nitrogen and Phosphorus in Schleswig-Holstein, FRG
Authors: Seyfried C. F. , Dammann E.
Published: May 2018

In order to solve the problems occurring in the North Sea and the Baltic Sea, programmes for the reduction of nutrients in wastewater treatment plants were initiated in the Schleswig-Holstein region. In 1988, all wastewater treatment plants with capacities greater than 17 000 population equivalents were upgraded for phosphate reduction, to give effluent concentrations of less than 2 mg P/l. By 1995, standard values of Ntot < 10 mg/l and P < 0.5 mg/l are expected.

Designs for the expansion of several wastewater treatment plants are presented in this paper. In particular, the problems which result from seasonal peaks, high phosphorus concentrations, and the combination of trickling filter and activated sludge processes are discussed.
Aerated Biofilters for Nitrification and Effluent Polishing
Authors: Paffoni Catherine , Gousailles Michel , Rogalla Frank , Gilles Pierre
Published: May 2018

To comply with new effluent discharge standards of 10 mg TKN/l, different upgrading methods for a highly loaded activated sludge plant were explored. As a conclusion, demonstration units were tested to assess process feasibility and performance data of an innovative technology. The Achères Treatment plant of the city of Paris is currently being extended to purify a flow of about 2 700 000 m3/d, corresponding to 8 Million population equivalents. Conventional activated sludge, loaded at about 0.6 kg BOD/kg SS d, delivers an effluent of 30 mg/l for both BOD and SS.

To achieve nitrification, a considerable multiplication of basin volume and clarifier area would be required. In the densely urbanised Paris area, insufficient space is available for a such an extension. Therefore, new technology for plant upgrading was tested on industrial scale. Biological aerated filters combine aerobic degradation of pollutants with physical retention of suspended solids in one reactor. A high concentration of active biomass can be retained in the packed bed, and nitrifying bacteria can be attached to the filter media. Removal efficiency becomes thus independent of clarification and sludge settling, and ammonia oxidation can be achieved without sludge age requirements.

Four parallel units were installed on the Colombes research platform, handling a total flow of 3000 m3/d. An extensive demonstration test program was carried out over a period of five years to assess the feasibility and performances of the process in line with a conventional activated sludge plant. The limits of loading to achieve different residual ammonia concentrations were studied, and the influence of temperature on biological and hydraulic parameters was verified. Backwash requirements and residual values of carbonaceous and suspended matter were explored in dependence on influent values and filtration velocity.

At 13 °C, an ammonia load of 0.5 kg N/m3 d was completely oxidized. A concentration of 20 mg/l N-NH4 can thus be totally converted with an empty bed contact time of 1 hour. The Arrhenius temperature coefficient for nitrification was measured as 1.05. Biodegradable carbonaceous and suspended matter was completely removed at filtration velocities higher than 4 m/h, yielding an effluent of less than 5 mg/l for both SS and BOD. Backwash frequency was less than once per day, and a maximum of 5 % of the filter flowrate was used for backwashing.
Development of a Methodology to Determine the Pollution Discharged by a Combined Sewer Network
Authors: Cherrered M. , Chocat B.
Published: May 2018

Until a few years ago, there was not much research in France into Combined Sewer Overflow phenomena in storm weather. The water of urban runoff has always been considered “clean” and one considered that the dilution of dry weather flows in storm water decreased the impact of the pollution generated by overflows.

Now, with increased urban development and realization of the importance of pollution caused by urban runoff, the problem can be considered differently. Indeed, some quality studies of receiving waters show that combined sewer networks represent an important pollution source for the natural environment, due to the increasing relative effect of combined sewer overflow discharge into receiving waters.

Thus, combined sewer overflows have until recently been the least known part of the sewer system.

In this present communication, methodology to estimate combined overflows has been elaborated after exploitation of data resulted from ten French real case studies where such problems were observed.

This study has been realized in four steps:- A bibliography study to discover the actual state of the problem in terms of existent methods concerning both experimentation and modelling and to define the needs of the research.- Ten French studies have been selected, analysed, and used to define the different methods used, and to show methodological lacunas from the observations and results realized. Elements of improvement have been proposed.- Methods and new propositions have been defined and a coherent methodological diagram has been realized to compare and test these methods.- Computer tools have been conceived and tested in the ten study cases.
The Quality of Sewage Flows and Sediment in Dundee
Authors: Ashley R. M. , Coghlan B. P. , Jefferies C.
Published: May 2018

Inter-related studies are underway in Dundee to investigate the nature, origins, disposition and movements of sewer sediments and associated pollutants. These studies, funded mainly by the Water Research Centre, have provided support for a proposed subjective classification system for combined sewer sediments based on visual appearance, occurrence and polluting strength. Data obtained from samples of suspended sediments at either end of a 175m length of the main Dundee sewer during dry weather and storm flows have been used to carry out a mass balance for the length over a one month period and, despite the obvious limitations, the results compare surprisingly well with the observed changes in the volume of bed deposits along the length for the same period.
Distribution of Sedimentation Rates of Suspended Solids and Heavy Metals in Combined Sewer Overflows
Authors: Benoist Alfred P. , Lijklema Lambertus
Published: May 2018

Measured absolute concentrations and the distributions of sedimentation rates (DSR's) of suspended solids (SS) and heavy metals in Combined Sewer Overflows (CSO's) show a strong variation between events. These variations can be explained partly by a relationship between the maximum discharge rate during an overflow and a) the concentrations of SS and the heavy metals Pb and Zn and b) the fraction of the DSR with high settling rates and the associated Pb concentrations. However, no unambiguous relationship between the DSR for the SS concentrations and the associated heavy metal concentrations has been detected. In contrast to the general experience a specific association of heavy metals with the fine fraction (low settling rates) in the SS of CSO's has not been found. The measured DSR's of SS and heavy metals have been used as input to a receiving water quality model. The simulated response is satisfactory, with regard to SS concentrations but not for heavy metals.
Monitoring a Vortex Storm Sewage Overflow with Peripheral Spill
Authors: Cootes T. , Balmforth D. J. , Russell S. , Doughty G. M.
Published: May 2018

Based on a design developed using model tests at Sheffield City Polytechnic, a full-scale prototype of a vortex storm sewage overflow with peripheral spill has been built in Sheffield. A project is running to monitor this overflow in order to assess its performance, both hydraulically and qualitatively. Flows into and out of the overflow chamber are being recorded, and samples of sewage are being taken, both from the flow entering the overflow and that spilling to the watercourse. A system known as the ‘Gross Solids Monitor' has been developed to get an estimate of the quantities of large objects in the flow, and examine how effective the overflow is at restaining such material from spilling.

Due to equipment failures and little rain, only limited results have been gathered to date. These show that the overflow appears to exert good hydraulic control, but has little separating effect on finely suspended or dissolved material.

Further data must be gathered before any conclusion can be reached as to how well the overflow restrains larger objects from spilling.

Further work is required on the Gross Solids Monitor before data analysis becomes fully automated.
Dairy Wastewater Treatment and Reuse
Authors: Hadjivassilis I.
Published: May 2018

Dairy wastewater (200 m3/d, 345 kg BOD5/d) is treated by activated sludge plant with an oxic selector, followed by a high- rate multilayer coagulation - filtration and disinfection. Treated water is reused for cooling and irrigation.
Appropriate Technology Hygiene Facility for Small Communities
Authors: Anda Martin , Mathew Kuruvilla , Ho Goen
Published: May 2018

Small communities will often need alternative systems of water supply, sanitation, washing and wastewater disposal facilities. Numerous agencies supply various models of ablutions facilities. The Remote Area Hygiene Facility comprises laundry, shower, toilet, wastewater disposal trench, solar water heater, chipheater, hand-operated washing machine and washing line. The toilet is a water–seal, low water demand, pit type. A plastic, solar water heater has been developed to overcome the problems experienced by commercial, metallic units such as blockages, breakages and ruptures due to freezing. The plastic design is more durable in the chosen environment and quite easy to assemble. Wastewater disposal is by evapotranspiration which is shown to be more effective than leach drains in tight, clay soils and promotes the growth of trees and shrubs. The Remote Area Developments Group proposes the installation of these units as community–based training projects to provide general construction skills, environmental hygiene education and a commitment to maintenance.
Computer Simulation of the Hydrodynamic and Salinity Behavior of Weeks Bay, Alabama, at Equatorial Tide Conditions
Authors: Thollapalli Ashok , April Gary C. , Raney Donald C. , Schroeder William W. , McCormick Barry C. , Lu Zhaodong
Published: May 2018

Whereas the long term goal of the work described focuses on issues related to estuaries in general, specific attention in this paper focuses on one – Weeks Bay, Alabama. This estuary is one of seventeen estuarine research reserves established as “natural field laboratories” for long-term scientific and educational programs (See Figure 1).

Initially, Weeks Bay will be assumed to be a well mixed estuary such that two-dimensional (depth averaged) modeling can be used. The Waterways Experiment Station Implicit Flooding Model (WIFM), developed by the U.S. Army Corps of Engineers, Vicksburg, Mississippi is used.

Complete data sets at equatorial tidal conditions were chosen from the field data available. Good agreement of model results with field measured water elevations was noted. These results are typical of the kind of agreement that is expected from two-dimensional depth averaged model simulations.

As anticipated, there seems to be little or no movement of salt along the western shoreline when the Bon Secour Bay salinities are low. This indicates selective flow of Fish River water down the western side of the bay with a corresponding preference for Bon Secour Bay water to flow along the eastern shore.
Detention of Sanitary Sewage as a Method to Reduce Combined Sewer Overflow Pollution Loads
Authors: Kollatsch Dirk-Th , Bünzel J.
Published: May 2018

Sanitary sewage yields the basic and most important pollution load diverted to receiving waters during combined sewer overflow (CSO). To reduce overflow pollution loads, it is proposed to store waste water in sanitary sewage detention tanks (SST).

For high efficiency those SSTs should be filled and emptied by pumps or gates, operated by control devices. Control strategies have to be worked out depending on different situations and parameters (catchment, rain and flow characteristics).
Economic Removal of Organic and Nutrient Substances from Municipal Wastewaters with Full-Scale U.A.S.B. Fluidized- and Fixed-Bed Reactors
Authors: Collivignarelli C. , Urbini G. , Farneti A. , Bassetti A. , Barbaresi U.
Published: May 2018

New biotechnologies (both aerobic, anoxic and anaerobic) based on attached biofilm or microbial-conglomerate processes have recently gained a considerable interest, as regards municipal wastewater treatment.

These systems, besides involving certain advantages, e.g. low energy consumption and reduced sludge production, are proving to be rather reliable: this made us think that such plant engineering solutions can be, in perspective, a real alternative to conventional biological processes.

This work deals with the main results obtained from an experiment carried out with municipal wastewater at ambient temperature (7 - 27°C) on a plant consisting of a UASB reactor, an aerobic fixed-bed reactor and an anoxic fluidized-bed reactor. The main object of the experimentation, still in course, is the technical verification of various plant engineering solutions aiming at locating the one most reliable for development on a large scale.

This report points out some of the aspects emerged; for other considerations, refer to works already published by the authors on this subject (see references).