bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of heavy metal pollution in inner-city canal sediments
Authors: Bijlsma M. , Galione A. L. S. , Kelderman P. , Alaerts G. J. , Clarisse I. A.
Published: May 2018

The spatial distribution of heavy metal pollution of canal sediments (City of Delft, The Netherlands) was investigated in the framework of a mass balance study. Heavy metal pollution in the accumulated dredged sediments showed marked spatial and vertical variations. In the sediment top layer of 10 to 15 cm thickness, copper levels varied from 45 to 281 mg Cu/kg, lead from 218 to 562 mg Pb/kg and zinc from 216 to 1400 mg Zn/kg. Values in the sediment bottom layer of 10 to 15 cm thickness were 20 to 50% higher, indicating a diminishing pollution load over the past years. Significant statistical correlations were found between the Cu, Pb and Zn contents, pointing at (a) common source(s) of pollution for these metals. Particle size analysis showed substantially enhanced levels of heavy metals in the fraction smaller than 106 μm. Results of preliminary mass balance calculations indicate that the quality of the surface water used for flushing the city canal system has a predominant effect on the inner-city sediment accumulation and pollution rates.
Occurrence and removal of Ascaris sp. ova by waste stabilisation ponds in Kenya
Authors: Grimason A. M. , Smith H. V. , Young G. , Thitai W. N.
Published: May 2018

A study was conducted to determine the occurrence of Ascaris sp. ova in municipal wastewater and their removal by a variety of waste stabilisation pond systems in the republic of Kenya. A total of 52 wastewater samples were examined for the presence of ova, comprising 10 raw wastewater and 42 pond effluent samples over a two month period during 1990. Ascaris sp. ova were detected in 6 out of 10 designated pond systems examined. In raw wastewater, ova concentrations ranged from 17.5 to 133.3 ova/l and in pond effluents from 0.7 to 88.9 ova/l. Although the majority of ova were removed in primary ponds that received raw wastewater, ova were detected in pond effluents with estimated hydraulic retention times far in excess of estimated settling rates for Ascaris. The occurrence of ova in pond effluent samples suggested that in these multi-pond systems, estimated cumulative retention periods of 12.4 (Eldoret), 26.2 (Dandora) and 17.8 (Nakuru) days, respectively, were required to achieve an effluent free of Ascaris sp. ova. Laboratory experiments were performed to assess physico-chemical and microbiological parameters to provide an indication of pond performance.
Performance of the Phase II Dandora waste stabilisation ponds the largest in Africa: the case for anaerobic ponds
Authors: Pearson H. W. , Avery S. T. , Mills S. W. , Njaggah P. , Odiambo P.
Published: May 2018

This paper describes the performance of the Dandora Waste Stabilisation Pond System which treats the industrial and domestic sewage from the City of Nairobi, Kenya and is the largest pond system in Africa. The ponds have the capacity to treat a dry weather flow of 80,000m3/d but currently treat only half this flow. Increased sewage strengths over and above the design value mean that although the hydraulic load is halved the organic surface load on the primary facultative ponds is only 37% below the design loading of 190kg BOD5/ha/d. The results of the ongoing monitoring programme show that effluent quality is good and meets WHO guidelines for unrestricted irrigation. Extrapolation of the existing results show that the system is performing to predictable efficiencies for the existing organic load and retention times (>90% BOD5 removal and >6 log reduction in FC) and will continue to do so as design flows and loads are reached. A pilot anaerobic pond study with what turns out to be full size anaerobics, showed BOD5 removal in excess of 80% in the single celled anaerobic ponds at design loadings of 240g/m3/d against a design prediction of 53% removal. Most importantly anaerobic pond loadings as low as 17-26% of the permissable volumetric loading maintained their efficiency without odour problems. This allows anaerobic ponds to be operated at flows well below design levels without risk of odour and without the need therefore to by-pass the anaerobics during commissioning and low initial flows. The benefits of land saving in the tropics by including anaerobic ponds in the system design is discussed as are the benefits of detailed monitoring programmes for large pond systems.
Performance evaluation of anoxic and facultative wastewater stabilization ponds
Authors: Saqqar Muwaffaq M. , Pescod M. B.
Published: May 2018

The performance of anoxic and facultative ponds in Jordan was investigated for 12 months. Calculated values of the first order kinetic equation rate for CBOD removal (KCBOD) has resulted in different KCBOD's for different ponds in the same month, at the same temperature. It is evident that factors other than temperature must influence values of KCBOD. The KCBOD values determined were generally lower than those reported in the literature. The maximum value found was only 0.16 (/day). A pond was emptied after 18 months of operation and sediment was found randomly distributed over the pond area, with a depth ranging from 2 to 6 cm (averaging ≈ 4 cm). A simple model has been established to estimate sediment depth (Hs in cm) in terms of the operating time in months (t).
Advanced integrated wastewater pond systems for nitrogen removal
Authors: Green F. Bailey , Bernstone L. S. , Lundquist T. J. , Oswald W. J.
Published: May 2018

Wastewater treatment lagoons are well known for their effectiveness in removing biochemical oxygen demand, suspended solids, and pathogens of sewage origin. Their performance in removing fixed nitrogen is somewhat less recognized and documented.

Advanced Integrated Wastewater Pond Systems (AIWPSs), developed at the University of California, Berkeley's Engineering Field Station and constructed at several locations in California and elsewhere, do permanently remove significant amounts of nitrogen from wastewater streams. A major part of this removal can be attributed to the unique design of AIWPSs. Because the unique characteristics of AIWPSs are not yet widely known and understood in the wastewater treatment field a somewhat detailed description of AIWPSs is in order.

First, the basis for the name Advanced Integrated Wastewater Pond Systems will be explained. The termadvanced is used because the design of AIWPSs represents an advancement over that of conventional waste stabilization ponds. The term integrated is used because these systems involve a number of well known and lesser known unit processes brought together in optimal sequence. The term pond is used because the individual bioreactors of an AIWPS are primarily constructed of earthwork. The term systems is used because the ponds are sequentially arranged and hydraulically controlled to optimize their multiple unit processes. The term wastewater is included to distinguish the function of these ponds from other types of water impoundments.
High rate algal oxidation ponding for the treatment of tannery effluents
Authors: Rose P. D. , Maart B. A. , Dunn K. M. , Rowswell R. A. , Britz P.
Published: May 2018

The growth of Spirulina sp has been observed in tannery effluent stabilization ponds. The development of a Spirulina-based High Rate Oxidation Pond was undertaken and both substantial remediation and odour reduction were achieved. Accumulating alkalinity associated with algal growth in the pond cascade was successfully used to reduce the ammonia toxicity effects on Spirulina productivity.

Evaluation of the feed value of harvested biomass was undertaken in Artemia salina, chickens, abalone and rainbow trout. A Spirulina-based High Rate Algal Oxidation Ponding process has been shown to present a potential opportunity factor in the form of value-added biomass providing a novel dimension to the treatment of tannery effluents.
Pathogen removal in experimental deep effluent storage reservoirs
Authors: Pearson H. W. , Mara D. D. , Cawley L. R. , Oragui J. I. , Silva S. A.
Published: May 2018

Studies on batch loaded pilot-scale deep effluent storage reservoirs (ESR) in NE Brazil using the operating regime of Fill, Rest and Use, rapidly produced a high microbiological quality effluent suitable for unrestricted irrigation ie. within 28 days at water temperatures of 25°C. There was little vertical variation in water quality in the ESR as the water column turned over at night. Physico chemical quality rather than microbiological quality of the effluent was more likely to control effluent re-use strategies and purification times as there were persistantly high ammonia and sulphide levels. ESR's could be organically loaded at rates similar to those used for facultative lagoons either using anaerobic pond effluent or raw sewage but the latter involved slightly longer purification times. The ESR's produced no odour problems. FC proved a good indicator of microbiological effluent quality and helminths could not be detected in the water column by the time the reservoir was full.
New method for studying the hydraulic behaviour of tanks in series -- application to aerated lagoons and waste stabilization ponds
Authors: Naméche T. , Vassel J. L.
Published: May 2018

All attempts to modelize and wastewater treatment process must go through the imperative knowledge of its mixing characteristics. Such a knowledge calls for the realization of tracing experiments, classically one per basin; an operation that becomes rapidly tedious, especially when it has to be repeated for a series of reactors.

The transfer function theory would allow to avoid such a multiplication of tracing operations. The transfer function which characterizes every system is indeed equal, under well defined initial conditions, to the Laplace transform of the distribution of residence times (R.T.D.) in this same reactor. The R.T.D. can then be calculated from the transfer function by a deconvolution process.

The main interest of this method consists in the fact that, unlike the R.T.D. the transfer function can be evaluated from any input/output signals whatsoever. Thus, the hydraulic pattern of a series of reactors can be easily and, more important, individually studied by means of tracer concentrations measured during only one tracing experiment at the exit of each basin.

The only difficulty in applying this method lies in the choice of the deconvolution procedure used to estimate the R.T.D. Four different methods of calculation are proposed and compared:

* deconvolution by Fourier transforms.

* deconvolution by multilinear regression.

* deconvolution by the algebraic resolution of a set of n equations with n unknowns.

* adjustment by the least-square method to an n order ARX model.

The last mentioned gives the best results. This method provides, for each pond, different parameters like Peclet number, percentage of dead-space or short-circuits. From these results, correlations between dispersion numbers and other state variables can be evaluated. Finally several hydraulic models (completely-stirred, dispersive plug flow, completely mixed tanks in series) may be simulated and compared with observed R.T.D.s.
Modelling solid transport in building drainage systems
Authors: Swaffield John A. , McDougall John A.
Published: May 2018

The transient flow conditions within a building drainage system may be simulated by the numerical solution of the defining equations of momentum and continuity, coupled to a knowledge of the boundary conditions representing either appliances discharging to the network or particular network terminations. While the fundamental mathematics has long been available, it is the availability of fast, affordable and accessible computing that has allowed the development of the simulations presented in this paper.

A drainage system model for unsteady partially filled pipeflow will be presented in this paper. The model is capable of predicting flow depth and rate, and solid velocity, throughout a complex network. The ability of such models to assist in the decision making and design processes will be shown, particularly in such areas as appliance design and water conservation.
Ammonia removal from sewage using natural Australian zeolite
Authors: Booker N. A. , Cooney E. L. , Priestley A. J.
Published: May 2018

A rapid adsorption process, which utilises the ammonium ion selectivity of a natural Australian zeolite, is being developed for removal of ammonia from sewage. The study reported in this paper claims not to have invented nor discovered this technique of ammonia removal from wastewater, but aims to realise the value of this natural Australian resource as an efficient alternative to existing treatment processes. An understanding of the equilibrium and kinetic behaviour of this material provided insight into its expected capacity as an adsorption media. Favourable results led to pilot scale trials, which revealed excellent performance of the zeolite under continuous column operation. The zeolite adsorption process has proved effective, at pilot scale, in reducing ammonium ions in sewage from concentrations ranging from 25 to 50 mg NH4-N/L down to levels below 1 mg NH4-N/L. Under optimised operating conditions, the adsorption capacity of the zeolite for this range of influent ammonium concentrations was about 4.5 mg NH4-N/g. The rate of treatment by the pilot zeolite column makes it ideally suited as a retrofit to high rate secondary sewage treatment processes, for removal of the soluble ammonium component.
Gross solids transport in small diameter sewers
Authors: Brown D. M. , Butler D. , Orman N. R. , Davies J. W.
Published: May 2018

Currently, little is known about the properties of sanitary gross solids or their transport mechanisms in sewers. This paper describes a project designed to study solids movement in small gravity sewers by laboratory, field and modelling work. Results of laboratory tests on gross solids' transport under steady flow conditions are presented. An ‘idealised’ field-based sewer has been constructed and will be used to monitor solids' movement under non-steady, intermittent flow. A computational model based on a method of characteristics solution of the St Venant equations has been produced. This will be extended to account for solids' erosion, transport and deposition.
Photocatalytic oxidation and subsequent adsorption characteristics of humic acids
Authors: Bekbölet Miray , Çeçen Ferhan , Özkösemen Gülhan
Published: May 2018

Effect of TiO2 photocatalyzed oxidation on the degradation and decolorization of humic acids was studied. The photocatalytic oxidation products were further investigated in terms of adsorptivity on activated carbon. With photocatalytic oxidation in a lab-scale batch reactor significant decolorization and a decrease in UV280 and UV254 took place. Simultaneously there was a decrease in TOC and COD. Parallel to this an evolution of BOD5 was observed. Thus the BOD5/COD ratio increased with irradiation time and more biodegradable substances have been formed. A significant change in the structure of compounds in humic acid took place only after 3-4 hours of irradiation as determined by the decrease in COD/TOC ratio. Generally there was a slight decrease of adsorptivity after irradiation as concluded from the comparison of Freundlich isotherm constants for raw and irradiated humic acid. This decrease increased as the irradiation time increased. But for irradiation times to be used in practice in photocatalytic oxidation no significant change in adsorption is expected.
Chromium removal by a bipolar electro-chemical precipitation process
Authors: Kongsricharoern N. , Polprasert C.
Published: May 2018

This research was conducted in laboratory to investigate an alternative for Cr removal from an electroplating wastewater using the electro-chemical precipitation (ECP) process. The ECP unit, operated in the bipolar mode, had six steel plates including the anode and cathode and was supplied with DC power. The electroplating wastewater used in the experiments contained Cr concentrations in the range of 570-2100 mg/l. The Cr removal efficiencies in the bipolar ECP units were higher than 99% and the Cr concentrations in the treated effluent were less than 0.5 mg/l. The acceptable conditions of the bipolar ECP unit treating the electroplating wastewater were found to be: I - 1.0 amp (or i - 6.70 amp/m2) and initial pH (pHi) of 4.5. At these acceptable conditions, the electric power and steel electrode plate consumptions were 20.0 kWh/m3 and 1.1-2.8 kg-Fe/kg Cr removed, respectively. X-ray fluorescence and X-ray diffractometric analysis performed on the precipitated sludge revealed the main compounds to be maghemite (Fe2O3) and chromite (FeCr2O4). The percent Fe2O3 and FeCr2O4 contents of the dried ECP sludge were 68% and 25%, respectively. From the mass balance analysis, the percent of Cr removal by precipitation in the ECP unit and adsorption on the ECP sludge were 85.1 and 14.8%, respectively.
Microfiltration of municipal wastewater for disinfection and advanced phosphorus removal
Authors: Dittrich J. , Gnirss R. , Peter-Fröhlich A. , Sarfert F.
Published: May 2018

The objective of Research Project 02 WA 9253/4 on “Advanced Treatment of Municipal Wastewater: Microfiltration of municipal wastewater for disinfection and advanced phosphorus removal” which is supported by the BMBF (Federal Ministry for Education, Science, Research and Technology) is to show whether microfiltration (MF) is a technically feasible and economically competitive process for disinfection and phosphorus removal of secondary effluent. For bacteria and phosphorus removal, three different microfiltration systems (systems with flat sheet, tube and hollow-fibre modules) with a pore size of 0.2 μm are tested in small-scale pilot plants to find out whether they are suitable for municipal wastewater treatment. The most suitable system will afterwards be tested in one full-scale unit to obtain operational data. The monitoring program with the small-scale MF plants using the final effluent of the Berlin-Ruhleben wastewater treatment plant started in November 1993 and the results obtained so far can be summarized as follows.

Total coliforms, E. coli, faecal streptococci and salmonella are removed to levels below the detection limit, less than 1 cfu/100 ml in the effluent of all three MF plants.

Coliphage - as a surrogate organism for enterovirus - are significantly reduced with a 2-3 log removal, which means that the limit value for enterovirus laid down in the EU Bathing Water Directive can be met in the effluent of the MF plants.

The average concentrations for total phosphorus (PT) in the effluent are 60 μg/l for the Memcor and the DOW units and 90 μg/l for the Starcosa unit without the use of precipitants.

With a low ferric dosage of 0.014 mol/m3 prior to the MF, the average effluent PT concentrations of all three MF units are lower than the target concentration of 50 μg/l (no polymer feed).

With a specific energy consumption of about 0.2 kWh/m3 filtrate the dead-end MF (Memcor) requires at least five times less energy than the cross-flow MF. Based on the energy consumption dead-end MF should be preferred if large volumetric flows of wastewater with a low concentration of solids have to be treated.

Because of unfavourable energy consumption the tests with the cross-flow MF have been discontinued.

When using MF systems in the final effluent of wastewater treatment plants, evidence must be produced in a full-scale MF unit to demonstrate that microfiltration is really suitable for practical application. This as well as a reliable calculation of investment and operating costs are the main objectives of further investigations within the framework of this research project.
The behavior of inorganic constituents and disinfection by products in reverse osmosis water desalination process
Authors: Magara Yasumoto , Aizawa Takako , Kunikane Shouichi , Itoh Masaki , Kohki Minoru , Kawasaki Mutuo , Takeuti Hiroshi
Published: May 2018

The countries and regions which suffer from the shortage of fresh water resources have developed sea and brackish water desalination plants to supply drinking water. The desalination process has usually been designed from the rejection ratio of salt to meet the level of soluble residue, chloride concentration for drinking purposes. The Japanese government revised the drinking water quality standards to enhance an appropriate drinking water quality management for many hazardous micro-pollutants in drinking water. Since there has not been sufficient studyies on the performance of R.O. desalination processes on micro hazardous constituents, the authors carried out a pilot plant study and field study of several desalination plants for the public water supply.

Most of the constituents of R.O. filtrate meets the drinking water quality standard under the design and operational condition that to attain 99% of the salt rejection. However, Langlier's index, boron and bromoform produced different figures from other inorganic constituents and organic micro pollutants. The rejection ratio of boron ranged only from 43 to 78%. Although the rejectio ratio of boron can be improved by increasing the driving pressure and by adjusting pH, the filtrate cannot meet the drinking water quality standard. Chlorination in the R.O. desalination process produces bromoform that can be removed by the R.O. membrane. However, bromide ion in the filtrate can enhance the formation of disinfection byproducts, if the filtrate is mixed with fresh water, in the distribution system of the public water supply.
Prediction of locations with sediment deposits in sewers
Authors: Mark Ole , Cerar Uros , Perrusquía Gustavo
Published: May 2018

The present paper presents an application of MOUSE ST, a general deterministic sediment transport model for sewer systems. MOUSE ST is used to predict the locations subjected to sedimentation in the sewer system of Ljubljana, Slovenia. The prediction is made by means of a sediment transport model with a movable bed. This model is run in parallel with the hydrodynamic MOUSE model. The results, in terms of locations with sediment deposits, are compared with field data from the sewer system in Ljubljana. Further, the model is used to predict the effect of the removal of the sediment deposits on the combined sewer overflows.
Two experimental sediment traps: operation and solids characteristics
Authors: Bertrand-Krajewski Jean-Luc , Madiec Hervé , Moine Olivier
Published: May 2018

Specific sediment traps for solids transported as bed load during storm events could be an interesting alternative to usual grit chambers. Two field experiments have been carried out in Bordeaux (south-west of France) in 1993 and 1994 to characterise the solids caught in the traps and to assess the sediment trap efficiency. These two sites have been chosen because it was easy to transform the existing usual grit chambers with a set of boxes used as sediment traps. The mass of trapped solids is well correlated with the rainfall height, for rainfalls of less than 50 mm. For greater rainfalls, the experimental sediment traps were too small to catch all solids. The efficiency of the sediment traps located at the grit chamber inlet side is assessed at about 70-80% in mass. Only 20-30% of solids are trapped at the outlet side. The efficiency decreases rapidly for the traps that are not in alignment with the median axis of the inlet pipe. The grain size distribution of the trapped solids is very characteristic: the d10, d50 and d90 values decrease when the traps are farther away from the median axis of the inlet pipe. This distribution of the trapped solids is due to the enlargement of the grit chamber which leads to a decrease of the flow velocity. The organic fraction increases when the d50 decreases: the finer the particles, the more organic the fractions.
Efficiency prediction for storage chambers using computational fluid dynamics
Authors: Stovin Virginia R. , Saul Adrian J.
Published: May 2018

Research was undertaken in order to identify possible methodologies for the prediction of sedimentation in storage chambers based on computational fluid dynamics (CFD). The Fluent CFD software was used to establish a numerical model of the flow field, on which further analysis was undertaken. Sedimentation was estimated from the simulated flow fields by two different methods. The first approach used the simulation to predict the bed shear stress distribution, with deposition being assumed for areas where the bed shear stress fell below a critical value (τcd). The value of τcd had previously been determined in the laboratory. Efficiency was then calculated as a function of the proportion of the chamber bed for which deposition had been predicted. The second method used the particle tracking facility in Fluent and efficiency was calculated from the proportion of particles that remained within the chamber. The results from the two techniques for efficiency are compared to data collected in a laboratory chamber. Three further simulations were then undertaken in order to investigate the influence of length to breadth ratio on chamber performance. The methodology presented here could be applied to complex geometries and full scale installations.
Sludge activity and cross-flow microfiltration - a non-beneficial relationship
Authors: Brockmann M. , Seyfried C. F.
Published: May 2018

For the past year a half-scale pilot plant for the anaerobic pretreatment of potato starch wastewater has been in operation. A reactor of 4 m3 was equipped with a settler and a so-called membrane thickener to reduce the amount of sludge which has to pass the membrane. According to other publications on membrane supported anaerobic digesters, organic loadings of more than 6 kg COD/m3d rarely have been achieved by this reactor. A loss of 50% of activity was observed after circulating the sludge 20 times and a 90% loss within 100 cycles. It can be shown that the symbiosis between acidogenic and methanogenic bacteria is the most sensitive part. These observations imply that a “gentle” transport of sludge through the membrane module must be developed, if membrane filtration at anaerobic reactors is to be further utilized. The results for an aerobic batch reactor implied that parallel to the destruction of sludge flocs due to the unsuitable pumps or to high transmembrane pressure, a significant decrease of the specific activity will take place.
The diversity of sewer sediments and the consequences for sewer flow quality modelling
Authors: Jack Andrew G. , Petrie Mark M. , Ashley Richard M.
Published: May 2018

As a consequence of recent EU Directives and a substantial increase in the environmental awareness of the general public, practising engineers and researchers are now more than ever required to collaborate to provide the higher standards of water quality being demanded. The engineers role is to implement a cost effective, practical and sustainable solution; the researcher must provide the engineer with the tools and ‘know how’ to allow this solution to be attained.

Recent research endeavours in the UK have resulted in a philosophy known as Urban Pollution Management. This philosophy allows the engineer to solve a drainage catchment problem utilising either simple or complex approaches, depending upon the ability of the receiving watercourse to assimilate discharges from CSOs and WTP's. The backbone of the complex approach is the sewer flow quality model. Consequently for a ‘realistic’ solution to be implemented, the sewer flow quality model must represent reality accurately. Work carried out in the City of Perth, has shown that there are significant limitations to the accuracy of a typical sewer flow quality model; limitations which cannot be attributed to the mathematics or the limitations of the particular package, but are due to the complexity and diversity of the phenomena encountered within sewerage systems, particularly the effects of the sediments. This paper questions whether in fact the recent UK research endeavour has actually provided engineers with a tool/philosophy which can provide cost effective, practical and sustainable solutions to complex drainage catchment problems.
Flush cleaning of sewers
Authors: Lorenzen Arne , Ristenpart Erik , Pfuhl Wolfgang
Published: May 2018

Flush cleaning experiments were conducted in a combined sewer in the city of Hannover using two existing gate valves. The aim of the investigation was to find a practicable cleaning recipe for a particular sewer section, where frequent cleaning actions are necessary due to massive sedimentation. Flush cleaning could be shown to be a powerful method to move sediments, however, the distance between the gate valves and the sewer section to be cleaned was to large, as to successfully clean the particular sewer section. The flush height, its velocity and duration, the frequency of flush events and perhaps the time of arrival of a flush are important qualities in oder to achieve good cleaning results. Modern flush cleaning tools like the Biogest system and the Hydrass Valve are powerful devices with excellent performances and without the shortcomings of other typs of valves. Flush cleaning should be considered when choosing a cleaning method for a particular sewer. It is a method which is economic and ecologic.
Membrane separation of produced water
Authors: Bilstad T. , Espedal E.
Published: May 2018

Each time regulatory agencies initiate more stringent environmental controls, treatment technologies are refined to meet the updated standards. Centrifuges and hydrocyclones are, by and large, producing satisfactory effluents for meeting current quality requirements for the offshore petroleum industries. The European standard for effluent from onshore petroleum activities, however, requires less than 5 mg/l total hydrocarbons (HC) and less than 10 mg/l suspended solids. Such low concentrations are out of reach for the above classical separation processes.

The amount of produced water in the North Sea is projected to increase by a factor of 6 from 1990 to the year 2000; from 16 to 90 million cubic meters each year. Produced water is the predominant source for oil discharges. The synergistic effects of chemicals, oil and dissolved components in the produced water effluent are given increased attention, with expectations of tougher effluent criteria.

Microfiltration (MF) and ultrafiltration (UF) pilot trials with produced water from the Snorre field in the North Sea showed that UF, but not MF, could meet more stringent effluent standards for total HC, suspended solids and dissolved constituents. Total HC in the produced water was typically 50 mg/l and was reduced to 2 mg/l in the UF permeate (96% removal). The aromatics benzene, toluene and xylene (BTX) were similarly reduced by 54% and the heavy metals copper (Cu) and zinc (Zn) by 95%.

UF trials were performed with organic tubular membranes with typical transmembrane pressures between 6 and 10 bars. The feed velocities through the tubes were between 2 and 4 m/s. Flux varied from 140 to 550 l/m2/h (lmh) at a produced water temperature of 60°C and membrane molecular weight cut-off between 100,000 and 200,000 daltons.

By recirculating UF retentate as membrane feed, a volume reduction (VR) of 24 was obtained in the trials; i.e., 96% permeate recovery. The limited volume of produced water available in the feed tank negated further volume reduction. Full-scale design is based on permeate recovery of 99%.

No irreversible fouling of the membrane surface was experienced. The cleanwater flux was restored after chemical cleaning. The alkaline detergent Ultrasil 11 was chosen as the optimal cleaning agent.
Practical applications of vortex flow separators in the Czech Republic
Authors: Koníèek Zdenìk , Pryl Karel , Suchánek Milan
Published: May 2018

Investigations of hydraulic models of swirl, vortex and helical bend separators were accomplished at hydraulic laboratories of the CTU Prague from 1980. Significant separating efficiencies were observed, indicating a possible reduction of pollutant loads CSO and WWTP bypasses. The paper will present some practical applications of vortex flow separators in the Czech Republic, as well as proposed designs of helical bend CSO's. The first application has been made in the suburb of Prague Kbely. The projected vortex separators substitute the storage tanks and especially a pretreatment of stormwater is highlighted with regard to their applications. Nowadays a few of these structures are in operation (Kbely, Liberec, Brno, etc.) and others are just constructed (Vrchlabí, Hradec Králové) or designed (Chodov, Mseno, etc.). Finally a review of separation efficiencies of the vortex flow separators is presented, describing the efficiencies with regard to BOD5, COD and total suspended solids. All data are related to the hydraulic load of considered structures.
An evaluation of methods for assessing the removal efficiency of a grit separation device
Authors: Gardner Peter , Deamer Andrew
Published: May 2018

The paper considers the many problems which can beset any attempt to verify or measure the performance of a grit removal device, including contractual ambiguities, the difficulties of assessing any flow dependency, sampling difficulties, uncertainty about analytical techniques and efficiency definitions. The different definitions of efficiency are discussed and it is concluded that the ‘partial penetration’ would be the most applicable to the situation. The usefulness is discussed of attempting to separate grits which do not damage machinery and improve the handleability of the primary sludge.

In the measurement of efficiency only two process streams need be sampled. Different protocols are considered which specify which streams should be sampled, and the advantages and disadvantages of each are set out. Solid stream sampling of recovered grit and primary sludges over a lengthy period is rejected as an unwieldy technique which may be impracticable on certain sites. The analysis of sludges for a small quantity of grit is problematic and subject to error, but this is also true of settled liquid stream samples. Rather it is concluded that supplementary grit addition coupled with liquid effluent stream sampling would give an efficiency subject to little error.

The results of recent significant work carried out in the testing of a Grit KingR Separator, both in-situ and under controlled conditions, using different methods are presented in this paper.

The recommended technique is described together with the sampling methods and further work required to verify/validate the procedure.
Biotreatment of naphthalene by PAH-acclimated pure culture with white-rot fungus phanerochaete chrysosporium
Authors: Wan-Li Liao , Dyi-Hwa Tseng
Published: May 2018

The tolerance of PAH toxicity for a PAH-acclimated pure culture with the fungus P. chrysosporium was evaluated by growth characteristics. The result showed that PAH-acclimated culture could still maintain its microbial activity, whereas the nonacclimated culture showed a declined growth when a high concentration of naphthalene (NTL) or benzo(a)pyrene (B(a)P) was present. In the treatment of NTL, the PAH-acclimated culture was also superior to the nonacclimated one. More than 90% of NTL removal had been attained by the PAH enrichment culture in agitated vessels within 24 h. However, in this experiment, about 20% of NTL was adsorbed on the fungal mycelia. After 4 days of reaction in the vessels, some ethyl acetate-extractable metabolites of NTL with high polarity in the HPLC elution were detected. One of these polar products was identified to be catechol compound. This study also demonstrated that NTL treatment in the aerated batch bioreactor was not comparable to that the agitated vessel owing to low efficiency in oxygen transfer of the system.
Biosorption of cationic dyes by dead macro fungus fomitopsis carnea: batch studies
Authors: Mittal Atul K. , Gupta S. K.
Published: May 2018

Application of dead macrofungus, Fomotopsis carnea for the sorption of three cationic dyes viz., Orlamar Red BG (ORBG), Orlamar Blue G (OBG) and Orlamar Red GTL (ORGTL) has been investigated. This study mainly focuses on the effect of various sorption kinetic parameters for the uptake of ORBG. Fomitopsis carnea shows excellent sorption potential for all the dyes studied. Saturation capacities for ORBG, OBG and ORGTL are 503.1, 545.2 and 643.9 mg g−1 respectively. Biosorption in the batch adsorber can be described by first-order reaction kinetics. Sorption decreases with decrease in pH.
Control of microbiological growth in recycling water in a waste paper processing mill
Authors: Jepsen Svend-Erik , Kristensen Gert Holm , Christensen Henrik Wenzel , Knudsen Hans Henrik , Mortensen Anna Lise , Ringbæk Ulla
Published: May 2018

Closing the water circuit in waste paper processing mills results in high concentrations of COD in the recirculating white water. Part of the COD is easily degradable and causes problems with microbiological growth in the water system. The load of dissolved COD to a paper mill producing moulded paper was determined: partly the incoming dissolved COD with the waste paper and partly the production of dissolved COD in the stock preparation and paper machine.

Pilot-plant experiments with biofiltration document that it is possible to remove efficiently easily degradable COD from the recycling white water. Very high loads have been applied to the filter owing to the high temperature and easy degradable carbon. Controlling the dosage of nutrients is essential to avoid growth problems in the white water system. It is shown that nutrients can be dosed to the filter with concentrations close to zero in the effluent, and still achieve significant removal capacity of the filter.
Using bundle filters to process petrochemical secondary effluent for industrial reuse
Authors: An Dingnian , Zhang Junzhen , Yuan Yi
Published: May 2018

The objective of this project is to study the advanced treatment technique for the secondary effluent from petrochemical wastewater treatment plants in order to meet requirements for the reuse of industrial wastewater. Based on the characteristics of the secondary effluent of petrochemical wastewater, a direct filtration process with highly effective filter is selected and designed. The test results indicate that the process can achieve good results in turbidity and COD removal. It can meet the need for the industrial reuse of the secondary effluent of petrochemical wastewater as the turbidity value of effluent is less than 3 and COD of effluent is less than 40 mg/l. A great economic efficiency is obtained. The filtration system costs low because of the longer operating cycle (14-24h). It is a creative achievement in the reuse of petrochemical wastewater, and is the pioneering study in China.
Public perception and water quality management
Authors: House Margaret A.
Published: May 2018

The visual and odorous characteristics of the environment tend to be those which have the greatest impact upon the public's assessment of environmental quality. In many cases the public's perception of water quality may be based entirely on these aesthetic aspects of a water environment. Those responsible for the management of surface water quality recognise the need to apply a range of management strategies including a consideration of the public's perception of water quality and the impact of this upon their use of rivers and beaches for recreation and amenity.

This paper reports upon the results from a recent investigation into the impact of sewage derived litter on perceived water and environmental quality.
Water quality monitoring network design of keelung river, northern taiwan
Authors: Lo S. L. , Kuo J. T. , Wang S. M.
Published: May 2018

The purpose of this study was to design the water quality monitoring network of the Keelung River which was channel regulated recently. A steady-state water quality model was used to simulate the BOD and DO curves. Kriging theory was applied for selecting the optimal locations of water quality monitoring network. The sampling frequency was determined by variances of water quality, considering the significant level and confidence interval. The optimal results indicated that more monitoring stations are needed in the downstream reaches. The stations suggested in the total number of monitoring network of the Keelung River is twenty-one, and the sampling frequency needs to be about two or three times per month.
Enhanced denitrification with methanol at WWTP Zürich-Werdhölzli
Authors: Purtschert I. , Siegrist H. , Gujer W.
Published: May 2018

In coordination with the EU-guidelines the large wastewater treatment plants in Switzerland have to be extended with enhanced nitrogen removal. Due to the existing plant configuration, the low COD/N ratio and dilute wastewater, denitrification supported by an external carbon source instead of extending the plant may be an interesting and cost effective solution for municipal wastewater treatment.

At the wastewater treatment plant Zürich-Werdhölzli different experiments were performed with methanol addition to predenitrification from March to July 1994. The aim of this work was to evaluate the use of methanol as an alternative to plant extension to achieve a higher nitrogen removal efficiency. Therefore, two parallel denitrifying lanes were investigated, one served for methanol addition experiments and the other as a control. The effect of oxygen input into the anoxic zone due to influent, return sludge and mixing was investigated, too.

The results show that nitrogen removal efficiency can be substantially increased as compared to the reference lane. The adaptation period for methanol degradation was only a few days and the process was relatively stable. Based on total nitrogen in the inflow, the average denitrification was 55% with methanol addition and 35% without methanol. The yield coefficient YCOD was 0.4 g CODX g−1 CODMe. Due to the small net growth rate of the methanol degraders the denitrification capacity is relatively low and nitrate peak loads cannot be fully denitrified. Hence, methanol as a carbon source requires more or less constant dosing. To prevent nitrate limitation, methanol addition should be controlled by the anoxic nitrate concentrations.
A sewage disposal strategy for the isle of man
Authors: Burrows R.
Published: May 2018

The Isle of Man sits in the middle of the Irish Sea, surrounded by the United Kingdom (UK) coasts of England, Scotland, Wales and Northern Ireland. It is, however, independently governed by its own Parliament, Tynwald, and is not part of the European Union (formerly the European Community, EC). A radical scheme for the integrated sewerage provision of the whole of the Island, of population approximately 65,000, involving centralised treatment and re-use of sewage sludges, has been accepted in principle. The policy adopted, as realised in the so-called ‘IRIS’ scheme, goes beyond the level of provision called for by the recent EC Directive on Urban Wastewater Treatment, yet the threat posed by the Isle of Man to the waters of the Irish Sea is negligible in comparison to the major inputs from its more populous neighborus. The geographic separation of the Island from the major pollution inputs from the British and Irish mainlands should ensure unobstructed assimilation of its releases by the marine environment. In many instances the coastal communities of the island, through their small size, would be without the statutory responsibility for land based treatment provision, even if bound by the EC legislation. This article, based on evidence presented to Public Inquiry on a first phase of the scheme's implementation, expresses the view that the strategy for future sewerage provision should be re- evaluated in the light of the flexibilities in implementation which would be afforded to the Isle of Man under the EC legislation. More fundamentally, however, it is suggested that the ‘marine treatment’ option using long- sea outfalls should be incorporated in the range of scheme options to be evaluated against achievement of a ‘best environmental solution’. The argument developed herein draws extensively on the background leading to the UK Water Industry's reluctant adoption of the EC legislation. These circumstances are considered worthy of report in their own right and the Isle of Man provides an ideal case study.
Water availability index based on quality and quantity: its application in Mexico
Authors: Jiménez-Cisneros Blanca
Published: May 2018

This paper presents an Availability Index based on water quality and quantity. The Index has two elements, the first one indicates the water availability in terms of quantity (renewable freshwater), and the second indicates the quality (in terms of the treatment needed to obtain adequate quality for potential use). Water quality is based on the calculation of another index called Potential Use Index, which enables one to classify the water in terms of its measured quality and to determine its suitability for a defined use. This methodology was applied to Mexico and it allowed a new regionalisation of the country for establishing several water quality preservation programs to start. Also, results were employed to redefine the national monitoring system as well as to initiate a process to change the water quality standards of Mexico. The Availability Index has the advantage of being very simple to evaluate and suitable for countries with no systematic monitoring (same type of information for different regions, regular periods of sampling and historical records).
Specific organic and nutrient loads in stabilized sludge from municipal treatment plants
Authors: Nowak O. , Franz A. , Svardal K. , Müller V.
Published: May 2018

By means of theoretical considerations and of statistical evaluations, specific organic and nitrogen loads in separately stabilized sludge have been found to be in the range of 16 to 20g VSS/PE/d and of 1.1 to 1.5 g N/PE/d respectively. About 0.6g P/PE/d are removed from the wastewater in activated sludge plants without chemical or enhanced biological P removal. By using the single-stage activated sludge process without primary sedimentation and without separate sludge stabilization, almost complete nitrogen removal can be achieved, but specific organic and nitrogen loads in the waste sludge are up to two times higher than in separately stabilized sludge.
Moisture distribution and removal efficiency of waste activated sludges
Authors: Lee D. J.
Published: May 2018

A classification scheme based on the bound water content measured via filtration (WFIL), expression (WEXP) and drying test (WDRY) was utilised for constructing the moisture distribution in excess activated sludges. The differences WFIL-WDRY-WEXP and WEXP were respectively interpreted as the interstitial water, surface water and internal water. The distribution and removal efficiency of moisture in excess activated sludges taken from a large wastewater treatment plant were found. The relative moisture removal efficiency for a belt filter press was near constant.
Biological anoxic phosphorus removal - the dephanox process
Authors: Bortone G. , Saltarelli R. , Alonso V. , Sorm R. , Wanner J. , Tilche A.
Published: May 2018

Simultaneous enhanced biological phosphate uptake and biological denitrification under anoxic conditions were investigated in a modified lab-scale nutrient removal activated sludge system (DEPHANOX). The aim of the experiments was to find whether it can be technologically convenient to use the capability of poly-P bacteria of taking up phosphate under anoxic condition by utilizing nitrate as electron acceptor. An experimental comparison of removal efficiencies with a more conventional treatment flow scheme (JHB), using low influent TKN/COD ratio, was also carried out. Phosphate uptake in anoxic condition was compared to that in oxic environment in batch tests. PHB anoxic and oxic degradation was evaluated by respirometric tests. Results of the long-term operation of continuous-flow lab-scale system as well as results of batch tests showed that the anoxic phosphate uptake with simultaneous denitrification after a previous anaerobic substrate uptake could significantly reduce the extent of competition for organic substrate between poly-P bacteria and denitrifiers. A side-stream nitrification in fixed-film reactor reduced the losses of organic carbon by oxidation and stabilized the slow-growing population of nitrifiers in the system.