bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.
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.
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.
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.
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.
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.
Surface active agents and their influence on oxygen transfer
Authors: Wagner Martin , Pöpel H. Johannes 
Published: May 2018

Oxygen transfer rates of fine bubble aeration systems in uniform arrangement are reduced down to 40% to 70% in wastewater compared to clean water conditions. Surfactants in wastewater are the main reason for the inferior and therefore uneconomic performance. The influence of different types of surfactants (anionic and nonionic) and of their concentration on oxygen transfer is investigated at various properties of pure water (content of electrolytes, hardness) by means of extensive experiments.
The main results of the investigations are:in dependence of the type of surfactant, its concentration and the types of water:– the aeration coefficient kLa decreases (down to 55%)– the specific interfacial area (a) increases (up to 350%)– the oxygen transfer coefficient (kL) decreases (down to 20%)nonionic surfactants reduce the oxygen transfer more strongly than anionic surfactantsat the same surface tension, but different types of surfactant α-values can vary over a range of 0.12. Therefore α-values can not be calculated from surface tension measurementsα-values of approximately 0.55 should be taken for designing fine bubble aeration systemsIn new guidelines for the measurement of oxygen transfer rates, addition of 5 gm−3 of an arbitrary surfactant into clean water to simulate wastewater conditions must be abandoned.
Inventories of point and diffuse sources and estimated nutrient loads - a comparison for different river basins in Central Europe
Authors: Behrendt Horst 
Published: May 2018

A comparison of the estimated emissions (input) with the measured loads at monitoring stations (output) is presented for the large Rivers Rhine, Elbe and its main tributaries and for the River Warnow, a smaller river in the north-east part of Germany. The comparison shows that the discrepancies between the estimated emissions and the measured load is small for the Rhine and its main tributaries, Mosel, Neckar and Main. Large discrepancies were found for the Elbe and its main tributaries.
For all investigated river systems a strong relationship exists between the quotient of measured nutrient load versus the estimated sum of point and diffuse emissions of nutrients and the areal specific runoff. A function is derived for the dependency of the sum of retention and/or losses in a river system on the specific runoff and the nutrient concentration in the river. The high accuracy of the estimated retention and/or losses within the different river basins offer the possibility to use these equations for a prediction of the emitted nutrients from measured nutrient load in similar rivers.
Experience with UASB reactor start-up under different operating conditions
Authors: Ghangrekar M. M. , Asolekar S. R. , Ranganathan K. R. , Joshi S. G. 
Published: May 2018

Four laboratory upflow anaerobic sludge blanket (UASB) reactors were operated at different operating parameters viz., hydraulic retention time (HRT), upflow velocity, organic concentration, and Ca2+ concentration in the wastewater. These operating parameters gave different values of organic loading rates (OLRs) and sludge loading rates (SLRs). The reactor performance during start-up was evaluated at different values of the above listed parameters. Also, the effects of these parameters on the granule characteristics were investigated.
It was observed that COD removal efficiency at steady state was profoundly influenced by SLR. The reactor started with SLR of 0.6 kgCOD/ kg VSS.d could result in about 50% COD removal at steady state. The reactor performance could not improve even after three months of operation. Up to 0.3 kgCOD/ kgVSS.d the reactor performance was good with more than 90% COD removal at steady state. The OLD and SLR also determine time required for the reactor to achieve steady state.
Different operating conditions also have the bearing on the strength of the granules cultivated. The methanogenic activity measured on acetate for each reactor was observed between 0.259 and 0.909 kg CH4 COD/ kgVSS.d. The sludge production in all the reactors was between 0.087 and 0.13 kgVSS/ kgCODin. The mathematical model was developed in order to predict sludge production.
Microbicidal effect of reflected UV radiation in devices for water disinfection
Authors: Sommer R. , Cabaj A. , Haider T. 
Published: May 2018

A standardised biodosimetric method was used to quantify the influence of reflection on the reduction equivalent UV doses (RED) in two commercially available water disinfection systems. One device, possessing a reflector made of aluminium, showed a decrease of RED of about 40% after removing the reflector. In the other plant, made of stainless steel, the inner surface of the irradiation chamber served as a reflector by itself. After eliminating the reflectance by black lacquering the inner surface of the irradiation chamber a distinctive decrease of RED was measured. This effect depended on the transmittance of the water (253.7 nm). With increasing water transmittance an increasing relative loss of RED was observed.
The results showed that the relative extent of the RED caused by reflection may even exceed the reflectance of the material due to multiple reflection, especially in water with high transmittance. However, in UV disinfection plants with inner surfaces made of reflecting material the reflectance may decrease during the operating life. Therefore, measuring the extent of reflection influencing the RED by using a suitable biodosimetric method is essential in UV devices for water disinfection.
Catalytic effects of high Fe(III) concentrations on Fe(II) oxidation
Authors: Tüfekci N. , Sarikaya H. Z. 
Published: May 2018

Catalytic effect of the ferric hydroxides on the oxidation of ferrous iron by aeration has been demonstrated and the kinetics of this catalytic reaction has been formulated by the recent studies. It has been reported that the oxidation rate is linearly increasing with Fe(III) concentrations up to 100 mg/l.
In this study, the oxidation of Fe(II) is studied in batch reactors in which the concentration of Fe(III) was in the range of 0-600 mg/l. A quadratic equation has been given to determine the catalytic reaction rate constant as a function of Fe(III) concentration. It was experimentally demonstrated that there was no significant effect of Fe(III) on the ferrous iron oxidation at Fe(III) concentrations beyond 600 mg/l.
Determination of aggregation and breakup constants during flocculation
Authors: Haarhoff Johannes , Joubert Hannes 
Published: May 2018

The Argaman-Kaufman flocculation model holds great promise as a practical tool for the generalization of flocculation behaviour from relatively few, simple batch tests in the laboratory. There are, however, valid reasons that have prevented it from being widely accepted in design practice. This paper deals with a number of these obstacles:
• There is the need of a standardized test method in terms of equipment, procedures and data analysis. The effects of settling time and the choice of the flocculation performance parameter are demonstrated.
• The flocculation constants are critically dependent on the level of coagulant dosage. In the sweep flocculation regime, the optimum coagulant dosage cannot be precisely pinpointed with jar testing, which presents a formidable problem for routine application.
• The flocculation constants are, contrary to the model, dependent on the initial particle concentration. This currently precludes the extrapolation of test results to raw water turbidities different from the turbidity at which the test was conducted.
• The flocculation performance parameter is not an intuitive parameter in design practice, and the design procedure for flocculation systems will have to be adapted to reach a specific design objective.
Oxidation of aromatic compounds with UV radiation/ozone/hydrogen peroxide
Authors: Mokrini A. , Ousse D. , Esplugas S. 
Published: May 2018

A large variety of organic and inorganic compounds may be found in wastewater. Among these compounds, aromatics are characterized by their high toxicity and very low degradability by conventional treatments.
This paper presents the results of an investigation about the oxidation of two substituted benzenes in a semi-batch reactor: phenol, substituted with an electron-donating group (-OH), and benzoic acid substituted with an electron- withdrawing group (-COOH). The advanced oxidation processes studied were UV, ozone, hydrogen peroxide and its combinations. The pH dependence and the influence of the initial concentration of hydrogen peroxide were studied to find the optimal conditions for a complete and fast oxidation of both compounds.
Experimental results indicated that both phenol and benzoic acid are destroyed more rapidly by ozone at higher pH (9–12), while ozonation combined with hydrogen peroxide or/and UV is considerably faster at low pH (3–7).