bluuebunny/crossref_metadata_2025 huggingface dataset:
CHROMIUM REMOVAL AND RECOVERY FROM TANNERY WASTES: LABORATORY INVESTIGATION AND FIELD EXPERIENCE ON A 10 m3/d DEMONSTRATION PLANT
Authors: Petruzzelli Domenico , Tiravanti Giovanni , Santori Mario , Passino Roberto
Published: May 2018

After extensive laboratory investigation of an ion exchange based process for selective removal, separation and recovery of Cr(III), AI(III) and Fe(III) from tannery wastes (spent chrome baths and leather washing waters), a 10 m3/d mobile pilot plant was assembled to demonstrate technical reliability and economic feasibility of the process.

The IERECHROM (Ion Exchange REmoval of CHROMium) process is based on a weak electrolyte carboxyl resin, able to remove the metals from the liquid effluent followed by selective separation and recovery during a regeneration step. The resin is regenerated with alkaline hydrogen peroxide brines (0.15 M H2O2, 1M NaCl, O.1M NaOH, pH ≈ 11) through an internal oxidation of chromic species to chromate, whereas aluminium is co-eluted after hydrolysis as aluminate ion. Ferric species are not released by the resin in these conditions and are easily regenerated by subsequent acidic elution (1M H2SO4). Aluminate is thus separated from chromate ion in the alkaline spent regeneration eluate by pH adjustment to 8.5 and precipitation of aluminum hydroxide.

In this paper the basic principles of the process are reported and the promising data obtained with a 10 m3/d mobile demonslration plant running at a tannery site in the Naples area.
The Toxicity of Organic Concentrates to Photobacterium Phosphoreum of River Meuse Water in the Stretch between Remilly (France) and Keizersveer (The Netherlands)
Authors: Polman H. J. G. , de Zwart D.
Published: May 2018

Organic concentrates of River Meuse water were tested for toxicity with a five minutes test (Microtox*) on luminescent bacteria (Photobacterium phosphoreum). Over the year 1992, the surface water was sampled six times at seven stations in the stretch between Remilly (France) and Keizersveer (The Netherlands).

Unfiltrated water samples were concentrated by neutral adsorption on XAD resin followed by elution with acetone. The measured toxicity is expressed as the concentration factor causing 20% reduction in bacterial luminescence after five minutes of exposure (EC20,5). The observed toxicity is transformed into a so called pT-value, pT=10log(EC20,5/100), relating toxicity to acceptability criteria.

Along the river, the toxicity attributable to organic pollution did not reach environmentally acceptable levels. The toxicity in the French and Belgian parts of the river increased gradually to a maximum toxicity generally observed near the industrial centre Liège. In the Dutch stretch, the organic toxicity generally decreased as a consequence of lower pollutant input, pollutant degradation, or pollutant adsorption to newly formed particulates.
The Belgian Project “Meuse Salmon 2000”. First Results, Problems and Future Prospects
Authors: Philippart J. C. , Micha J. C. , Baras E. , Prignon C. , Gillet A. , Joris S.
Published: May 2018

In 1983, a hydrobiological study was undertaken to evaluate the possibility of restoring a salmon run in the Belgian R. Meuse. This investigation resulted in the “Meuse Salmon 2000” programme that started in 1987. A major part of this programme deals with the assessment of the potential of smolt production in three tributaries (R. Ourthe, R. Semois and R. Samson) of the R. Meuse. Experimental stockings are being performed using parrs and presmolts obtained from Scottish (R. Connon) eggs reared in a hatchery by the Service de la Pêche of the Région Wallonne. By the end of 1992, over 220,000 young salmons had been released in the wild, especially in the River Ourthe-Amblève sub-basin. The paper shortly reports on the first results of stocking experiments and on the main problems (water quality in Belgium, fish passes at dams and hydropower stations, professional fishing in The Netherlands, international status of the R. Meuse) that have to be solved before adult salmon come back to the important potential spawning areas in Southern Belgium.
International Commission for the Hydrology of the Rhine Basin (CHR)
Authors: Wagenaar-Hart A. M.
Published: May 2018

The Commission for the Hydrology of the Rhine basin (CHR) is an organisation in which hydrological institutes from the six main riparian states of the Rhine cooperate in the field of hydrological research. The member states of the CHR are: Switzerland, Austria, Germany, France, Luxemburg and The Netherlands. The main objective of the CHR is to study hydrological phenomena in the Rhine basin. The Commission' s first activities were mainly focused on making an inventory of hydrological data, which resulted in the publication of an extensive monograph on the Rhine basin. After that, the Commission began work on a new research programme to improve the water resources management in the Rhine basin. This programme included topics such as: standardization of data, improvement of hydrological forecasts and the description of extreme hydrological events. Nowadays, the Commission concentrates on a number of topical themes, such as: influence of climatic changes on the discharge of the Rhine, anthropogenic influences on the discharge regime, development of an alarm model for pollution transport, sediment transport in the Rhine basin and ecological rehabilitation of floodplains.
EMERGING TRENDS IN ELECTRICAL ENERGY USAGE AT CANADIAN (ONTARIO) MUNICIPAL WASTEWATER TREATMENT FACILITIES AND STRATEGIES FOR IMPROVING ENERGY EFFICIENCY
Authors: Evans B. , Laughton P.
Published: May 2018

The province of Ontario is Canada's most populous province with over 8 million residents out of a total population of 27 million. The Province is situated in the eastern portion of North America and stretches from 41°N to 50° N. All the Great Lakes fall within Ontario's boundaries and the Province is estimated to have over 280,000 lakes. The area along Lake Ontario is home to 5 million of the residents who are serviced by 11 large sewage treatment plants. The remaining 403 treatment plants are scattered throughout the province. with an average size of 20 000 m3/d.

Ontario Hydro commissioned a study of the wastewater treatment plants to identify the main power users at the various types of sewage treatment plants, as well as potential areas within each plant where significant energy savings could be generated. By using this information, Ontario Hydro hoped to assess the potential to reduce the load and identify any electrical efficiency improvements, fuel switching and load shifting opportunities that may exist as well as the impact of environmental regulations on power saving initiatives.

It was found that several major opportunities existed. These included:■ that up to 25% of power currently used can be reduced by introducing energy efficient measures■ of all the unit operations in wastewater treatment plants, aeration accounts for 42% of the power usage, influent and effluent pumping - 20%, and dewatering - 6%. Of this influent and effluent pumping, specifically influent represented the best target area as significant aeration system upgrade had already taken place.
USING pH AS A REAL-TIME CONTROL PARAMETER FOR WASTEWATER TREATMENT AND SLUDGE DIGESTION PROCESSES
Authors: AI-Ghusain Ibrahim A. , Huang Jason , Hao Oliver J. , Lim Bong S.
Published: May 2018

The alternating aerobic-anoxic (AAA) process offers many advantages for wastewater treatment and sludge digestion. Laboratory scale experiments were conducted to investigate the feasibility of using pH as a realtime control parameter for this process. Several well defined control points on the pH curve were identified, e.g., ammonia valley and nitrate apex. These points were directly related to the alternating nitrification and denitrification reactions in the process, and were found to be consistent with those previously identified using ORP. Although both pH and ORP can be used as real-time control parameters, pH provides several additional advantages over ORP. Based on these findings, real-time control strategies (fixed pH setpoints and dynamic pH control) were developed and tested. Results from laboratory scale AAA sludge digestion using fixed pH setpoints (6-8) indicated that 36% MLVSS reduction, 39% TN reduction and almost 48% saving in aeration energy was achieved after 300 hrs of digestion.
REAL-TIME CONTROL OF NITROGEN REMOVAL AT FULL-SCALE USING OXIDATION REDUCTION POTENTIAL
Authors: Wouters-Wasiak K. , Héduit A. , Audic J. M. , Lefèvre F.
Published: May 2018

Full-scale studies at a 16,000 p.e. wastewater treatment plant were carried out to examine the use of oxidation-reduction potential (ORP) (and dissolved oxygen (DO) concentrations for real-time monitoring of biological nutrient control. Breakpoints in DO and ORP time profiles proved particularly useful (with correct aeration conditions) in optimising nitrogen removal.
Orange County Florida Eastern Service Area Reclaimed Water Wetlands Reuse System
Authors: Schwartz Larry N. , Wallace Peter M. , Gale Paula M. , Smith Willard F. , Wittig James T. , McCarty Stephanie L.
Published: May 2018

As part of an integrated multiple reuse program reclaimed water is discharged to a system of natural and created wetlands before ultimate discharge to a river. A research plan bas been required to determine the long-term effects of reclaimed wastewater on the wetlands, their waste recycling efficiency and the impact on downstream waters. This paper presents results from three years of this monitoring and research program which show the wetlands reuse system to function well, with no adverse impacts on wetlands or receiving waters.
Water quality improvements in the Trent catchment (UK): a view of their relationship to management and legislative changes
Authors: Martin J. R.
Published: May 2018

This paper outlines the improvements in water quality which have occurred in the River Trent catchment since about 1960 and the strategies by which they have been achieved. During this period there have also been several major changes in the structure of water quality management, in pollution control legislation and in the use of river and effluent quality standards. The links between quality trends, legislation, management structures and investment in sewerage and sewage treatment are considered. Prospects for the future under the current management regime are discussed.
Nitrogen and phosphorus in the Vistula River, Poland -- changes from source to mouth
Authors: Sundblad Karin , Tonderski Andrzej , Rulewski Jacek
Published: May 2018

Nitrogen and phosphorus concentration data representing samples collected once a month for nine months at 13 locations along the Vistula River are considered in a preliminary discussion of the sources of the nutrients transported to the Baltic Sea. Concentrations in relation to flow data indicated substantial differences between subbasins. Based on those differences, on the area-specific nutrient loss for a six-month period and on the wastewater discharge in each subbasin, four regions could be recognized in the river basin: i) the southern region with a large impact of point sources, ii) the south central region, where diffuse sources seemed to be of major importance, iii) the north central region with a combined effect of point and diffuse sources, and retention in two reservoirs, iv) the northern region where point sources seemed to be the dominating source, at least for phosphorus.

Our results illustrate the importance of differences in phosphorus retention between the basins. Long-term retention along the course of the river, particularly in the two reservoirs, must be estimated to allow proper source apportionment in the Vistula basin. Concentration decreases in the Wloclawek Reservoir varied between 44 and 68% for P, and 11 to 37% for N, in the months with significant retention. In some months, however, concentrations increased, indicating a release of nutrients.
Pollution prevention and waste minimization at a galvanizing and electroplating facility
Authors: Dahab M. F. , Montag D. L. , Parr J. M.
Published: May 2018

Pollution prevention, often referred to as source reduction, encompasses all activities that lead to reductions in the amount and/or toxicity of wastes. Waste minimization, on the other hand, refers to all activities including source reduction, on-site reuse, and recycling that lead to reductions in the amount and/or toxicity of waste generated, stored, treated, or disposed of by a given facility. Pollution prevention generally is regarded as the most cost-effective component of integrated waste management strategies. This paper describes an industrial pollution prevention program at an aging manufacturing facility in the Midwestern United States. The study focuses on metal electroplating and galvanizing. The facility under study produces fabricated metal products for farm and industrial use. The facility performs many operations including electroplating, conversion coating, cleaning, machining, grinding, impact deformation, shearing, welding, sand blasting, hot-dip galvanizing, painting, assembly and testing. Many of these processes result in the production of a variety of pollutants (gaseous, solid, and liquid) that must be disposed of in some fashion. For example, the electroplating line results in the production of acids and rinse water containing zinc and chromium and the hot-dip galvanizing line results in the production of acids and rinse water containing zinc and iron. All of these wastes must be treated as hazardous substances. The painting processes result in the production of used industrial acids, solvents, and chemicals used for cleaning and de-greasing metal components. Most of the recommended operational and process modifications were simple to implement, and their pay-back periods were fairly short.
Nitrogen elimination from sludge treatment reject water – comparison of the steam-stripping and denitrification processes
Authors: Teichgräber Burkhard , Stein Andreas
Published: May 2018

Steam stripping and nitrification/denitrification for the elimination of nitrogen from sludge treatment reject water from the Central Sludge Treatment Facilities (CSTF) of the Emschergenossenschaft in Bottrop were tested in half-scale pilot plants. More than 90% efficiency could be achieved with both systems; the nitrification/denitrification process also removed organic nitrogen. Operational experience has shown that full scale application of both systems is possible. The design surface load of the stripping column has been evaluated as 10 m3/(m2*h) and the steam/water ratio as 0.12 t/m3. The nitrification/denitrification process can be designed for 0.07 kgN/(kg MLSS*d) and 1.4 days hydraulic retention time. Total treatment costs are estimated to be between 5 and 7.5 DM/kg N.
Influence of dissolved oxygen and oxidation–reduction potential on the denitrification rate of activated sludge
Authors: Lie Ewa , Welander Thomas
Published: May 2018

The influence of low concentrations of dissolved oxygen (DO) and the oxidation-reduction potential (ORP) on the denitrification activity of activated sludge has been studied in batchwise experiments. The ORP was maintained at different levels by automatic titration with air and the denitrification activity was determined by following the disappearance of nitrate. Oxygen was found to have a negative effect on denitrification even at lower concentrations than can be measured with conventional oxygen probes (<0.1 mg/L). The ORP was found to be a useful indicator of the DO concentration at this low level and the denitrification rate was found to decrease linearly with increasing ORP. However, the effect of the ORP on denitrification differed between sludges from different treatment plants. A linear relationship was also found between the ORP and the DO concentration in the region of measurable DO concentrations. Extrapolation of this straight line into the region where DO was under the detection limit indicated that oxygen exerts an inhibitory effect on denitrification at such low concentrations as a few μg/L.
Nitrogen removal in activated sludge systems including denitrification in secondary clarifiers
Authors: Siegrist H. , Gujer W.
Published: May 2018

Denitrification in the secondary clarifier can contribute substantially to the nitrogen removal of activated sludge systems. This is illustrated on two treatment plants with different secondary clarifier systems. A model to estimate denitrification capacity and to design activated sludge systems for nitrogen removal is developed and verified with data from two treatment plants. The model includes denitrification in the secondary clarifier, wastewater composition (soluble readily biodegradable COD, particulate degradable COD), oxygen input into the anoxic volume, temperature, and solids retention time (SRT). The influence of aerated grit chambers and primary sedimentation on denitrification is discussed.
Denitrification and neutralization with an electrochemical and biological reactor
Authors: Sakakibara Y. , Araki K. , Tanaka T. , Watanabe T. , Kuroda M.
Published: May 2018

Denitrifying microorganisms were immobilized with a sodium alginate gel on a cathode electrode, and electric current was applied using a carbon electrode as the anode. Biological reductions of nitrate through the use of H2 at the cathode and formations of inorganic carbons at the anode were observed. Experimental results showed that oxidation of carbon electrode to CO2 was favorable for developing anoxic conditions and to neutralize alkalinity formed during denitrification. Several volts of potential was needed to operate the reactor.
Deterioration of enhanced biological phosphorus removal by the domination of microorganisms without polyphosphate accumulation
Authors: Satoh H. , Mino T. , Matsuo T.
Published: May 2018

Enhanced biological phosphorus removal by anaerobic-aerobic operation is not always achieved successfully. In this study, microbial metabolism in the activated sludge of a failed enhanced biological phosphorus removal process was investigated to clarify the cause of the failure. The dominant microorganisms in the sludge consumed carbohydrates in the uptake process of acetate or propionate under anaerobic conditions and accumulated polyhydroxyalkanaate. But significant release of phosphate was not observed because polyphosphate was not utilized. Consumed carbohydrates were found to have been converted to polyhydroxyalkanoate via propionyl-CoA in addition to acetyl-CoA, indicating that the microorganisms had enzymes to convert phosphoenolpyruvate or pyruvate produced in glycolysis to propionyl-CoA. The propionate fermentation was supposed to work as the sink of the reducing power excessively produced in glycolysis; thus while maintaining the redox balance, microorganisms were able to get energy not from polyphosphate but from glycogen. The difference in the metabolic systems between polyphosphate accumulating bacteria and the present microorganisms may give hints to avoid the deterioration of enhanced biological phosphorus removal.
Modelling of the carrousel plant
Authors: Derco Ján , Králik Milan , Hutnan Miroslav , Bodík Igor , Cernák Rastislav
Published: May 2018

The results of experimental and mathematical modelling of simultaneous processes of organic and nitrogen impurities removal in an industrial Carrousel wastewater treatment plant are presented. The hydrodynamic regime measurements in the full-scale Carrousel system have led to the conclusion that at least three hydrodynamic models such as tank-in-series, ideally mixing reactor with aerobic and anoxic volume and completely mixing reactor with an intermittent aeration, are suitable to describe the dynamic behaviour of this bioreactor. The tank-in-series and the intermittently aerated completely mixing equipments were used in lab-scale modelling of the Carrousel plants. Various kinetic models and a statistical approach were applied to the evaluation of laboratory and full-scale data. The simplified kinetic model proved to be convenient for the process control purposes due to the significant computational time reduction in model parameters determination in comparision to tank-in-series hydrodynamic modelling. Also, the statistical model is very suitable approximation of the processes carried out in the Carrousel system. The completely mixing bioreactor with intermittent aeration is advantageous for experimental simulation of simultaneous nitrification and denitrification processes performed in high-rate recycled activated sludge systems. The influence of wastewater substances on oxygen transport rate is implicitly incorporated through aerobic and anoxic ‘switching functions’ evaluated based on oxygen profile data monitored in the bioreactor when applying the modified IAWPRC kinetic model.
Probing Activated Sludge with Fluorescently Labeled rRNA Targeted Oligonucleotides
Authors: Wagner M. , Amann R. , Lemmer H. , Manz W. , Schleifer K. H.
Published: May 2018

Activated sludge samples from municipal sewage treatment plants were characterized using 16S and 23S ribosomal RNA targeted oligonucleotide probes specific for defined phylogenetic groups of bacteria. Comparison of in situ community structures as determined by molecular biological methods with the composition of the heterotrophic saprophyte flora isolated on nutrient rich medium revealed large discrepancies. These are caused by the selectivity of media and culture conditions. The most significant effect of cultivation on nutrient rich medium is an underestimation of bacteria belonging to the beta-subclass of Proteobacteria and an overestimation of bacteria belonging to the gamma-subclass of Proteobacteria. Therefore, culture dependent enumerations of the gamma-subclass bacteria of the genus Acinetobacter in plants with enhanced biological phosphate removal (EBPR) resulted in significant overestimations. In situ identification by fluorescent oligonucleotide probing revealed that Acinetobacter numbers were below 8% of the active bacterial cells in the examined EBPR-plants. In situ hybridization techniques also bear the potential for the early and correct identification of filamentous bacteria as indicators for sludge bulking and foaming. A 16S ribosomal RNA targeted oligonucleotide probe specific for Sphaerotilus spec, was developed and successfully applied for in situ investigation of this filamentous bacterium.
pH: Keyfactor in the Biological Phosphorus Removal Process
Authors: Smolders G. J. F. , van Loosdrecht M. C. M. , Heijnen J. J.
Published: May 2018

Experiments have been performed, using a sequencing batch reactor, to examine the effect of pH on biological phosphorus removal in the activated sludge process. The results, which indicate that glycogen metabolism occurs during anaerobic conditions, are useful in elucidating the biochemical mechanisms involved in phosphorus-removal, and have potential implications for systems such as Phostrip.
Biological treatment of airstreams contaminated with organic vapors
Authors: Ye Lin , Khandan Nirmala N. , Edwards Findlay G.
Published: May 2018

Increases in regulatory control of discharges of organic vapors require improvement of traditional methods of removal and treatment of organic vapors from airstreams. The traditional methods of removal, various forms of adsorption, only change the phase of the pollutants. Subsequent treatment of the pollutants has proven to be energy intensive and therefore expensive. Biological treatment of organics has proven to be inexpensive but requires that the organics be in dissolved form, in the liquid phase, and at a concentration above a minimum concentration. Adsorption of organics in the gas phase onto activated carbon, which is suspended in water, will remove the pollutants from the gas phase and can increase the aqueous concentration, in the region around each activated carbon particle, above the required minimum for biological degradation. The organic pollutants can then be biodegraded leaving harmless by-products. Design of a reactor to provide for the phase change and the biodegradation of the pollutant requires development of a theoretical model and validation of the model.
Field evaluation of perox-pure™ chemical oxidation technology
Authors: Topudurti Kirankumar , Keefe Michael , Wooliever Patrick , Lewis Norma
Published: May 2018

This paper presents the field evaluation results for an advanced chemical oxidation technology developed by Peroxidation Systems, Inc., of Tucson, Arizona. The technology, known as the perox-pure™ technology, was evaluated under the U.S. Environmental Protection Agency Superfund Innovative Technology Evaluation program at Lawrence Livermore National Laboratory (LLNL), Site 300 in Tracy, California, in September 1992.

The perox-pure™ technology uses ultraviolet radiation and hydrogen peroxide to oxidize dissolved organic compounds in water. At the LLNL site, this technology was evaluated in treating groundwater contaminated with volatile organic compounds (VOC) including trichloroethene (TCE); tetrachloroethene (PCE); 1,1,1-trichloroethane (TCA); 1,1-dichloroethane (DCA); and chloroform. The perox-pure™ system generally produced an effluent that contained TCE, PCE, and DCA at levels below detection limits, and TCA and chloroform at levels slightly above detection limits. The system achieved maximum removal efficiencies of greater than 99.9, 98.7, and 95.8 percent for TCE, PCE, and DCA, respectively. The system also achieved removal efficiencies of up to 92.9 and 93.6 percent for TCA and chloroform, respectively. The treatment system effluent met California drinking water action levels and federal drinking water maximum contaminant levels for all VOCs at the 95 percent confidence level. Cost analysis indicated that the groundwater remediation cost for a 50-gallon per minute perox-pure™ system would range from $7 to $11 per 1,000 gallons, depending on contaminated groundwater characteristics. Of this total cost, the perox-pure™ system direct treatment cost would range from $3 to $5 per 1,000 gallons.
Rate-Capacity Characterization of Wastewater for Nutrient Removal Processes
Authors: Henze Mogens , Holm Kristensen Gert , Strube Rune
Published: May 2018

The detailed composition of wastewater has significant impact on the biological wastewater treatment processes. The carbon sources present govern the oxygen uptake rate, the rate of denitrification and the biological phosphorus uptake rate.

In this paper, the respiration rate determinations used for the bi- or tri-substrate determinations are coupled to removal capacity in order to develop rate-capacity diagrams, that gives a fuller picture of the wastewater and its influence on the biological processes. The directly degradable carbon source gives high reaction rates, but the concentration and thus the capacity can be very limited. In such a case the overall obtainable removal rate is of more interest than the peak rate.

The rate-capacity diagrams are shown for raw, primary settled and primary precipitated wastewater, characterized by detailed investigations of the respiration rates obtainable. It shows the effect of pretreatment not only on the total concentrations in the pre-treated wastewater, but also in the rate-capacity curves for biological denitrification. The rate-capacity curves are in practice coupled to the design and operation of the treatment plant. These two factors determine whether the carbon sources in the influent wastewater are used for denitrification (or biological phosphorus removal), for oxidation with oxygen or for sludge production.
Management of Papermill Wastes: The Role of Filamentous Microorganisms as Indicators
Authors: Cingolani L. , Ciccarelli E. , Cossignani M. , Tornari Q. , Scarlata V.
Published: May 2018

A study was made at nine papermill activated sludge treatment plants, affected by bulking phenomena, on the behaviour of filamentous microorganisms in connection with plant performances. In the sludge samples 24 organisms were identified, the most frequently observed being type 0041 and 0675. The principal causes of inconvenience, isolated through statistical analysis, were identified as low oxygenation, high load, low F/M, nutrient deficiency. Changes made in operating conditions improved bulking in some plants.
The Implementation of Bulking Control in the Design of Activated Sludge Systems
Authors: Wanner Jiri
Published: May 2018

The factors affecting the growth of most common filamentous microorganisms are discussed. In a design procedure the following factors should be considered: wastewater composition (readily and slowly biodegradable substrates, inoculation), biomass retention time, actual substrate concentration in reactor, operational parameters in reactor (DO and nutrients concentration, pH, temperature) and cultivation conditions. The configurations of activated sludge process supporting the growth of floc-formers are described. As general design methods and criteria for the design of bulking control systems are not available due to the complexity of selection mechanisms, the technological parameters from successful bulking control case histories are summarized. The possibilities of mathematical activated sludge process models for design purposes are evaluated.
Isolation and Physiological Characterization of Thiothrix sp.
Authors: Tandoi V. , Caravaglio N. , Di Dio Balsamo D. , Majone M. , Tomei M. C.
Published: May 2018

Thiothrix CT3 was isolated in pure culture by micromanipulation technique. The growth of this microorganism was analyzed in autotrophic, heterotrophic and mixotrophic conditions, in a bicarbonate-containing mineral medium supplemented with thiosulphate and/or acetate. Thiothrix CT3 was able to grow in all the conditions examined: the maximum growth rates estimated were 1.8, 2.5 and 2.5 d−1 respectively. The capacity of this organism to grow autotrophically, as supposed by Winogradsky in 1888, is a strong advantage over the other bacteria present in activated sludge, when sulphides are produced or carried by the sewer. Both the maximum growth rate and growth yield coefficient shown during heterotrophic and mixotrophic growth were comparable, indicating that the simultaneous presence of two substrates (acetate and a reduced sulphur compound) does not give it any particular advantage. The strong presence of Thiothrix spp. in many plants located in South Italy can be explained by the wide nutritional versatility of this filamentous bacterium.
The Microthrix parvicella Puzzle
Authors: Eikelboom Dick H.
Published: May 2018

Nowadays the excessive growth of many filamentous bacteria in activated sludge plants can be controlled by the application of so-called selectors. In the Netherlands, about 80 selectors have been constructed at full scale plants so far. However, selectors are frequently not very effective for controlling bulking if M. parvicella is dominating the sludge population. As M. parvicella has also been frequently observed in nutrient removal plants, the development of control strategies for this bacterium has become very urgent.

From the substantial information on the occurrence of and attempts to control M. parvicella collected during the last decade, several main conclusions can be drawn.The development of M. parvicella in Dutch treatment plants shows a very distinctive seasonal rhythm, the population reaching its maximum size in early spring.Foaming in Dutch treatment plants is usually caused by M. parvicella.M. parvicella and Actinomycetes spp. seem to compete for the same ecological niche in treatment plants.By comparing the population size of M. parvicella as a function of various modifications in the activated sludge process, it is concluded that this bacterium grows better in so-called carrousel systems than in other extended aeration plants.M. parvicella causes severe bulking in carrousels fed with presettled sewage.The impact/usefulness of selectors for controlling M. parvicella seems to decrease as the overall sludge load of the plant increases.

This information is presented to start a discussion about possibilities to solve the M. parvicella puzzle.
Practical Investigations on Bulking and Foaming in Activated Sludge Plants with Biological Phosphorus Removal
Authors: Kunst S. , Reins M.
Published: May 2018

Six processes implemented at treatment plants with biological phosphorus removal aiming to avert sludge bulking were examined systematically. Intensive observation of the filamentous microorganisms (characterised according to a new scheme) and microscopic observation of sludge structures are used to identify the significant organisms and their bulking behaviour.
The Effect of Incomplete Denitrification on Anoxic-Aerobic (Low F/M) Filament Bulking in Nutrient Removal Activated Sludge Systems
Authors: Musvoto E. V. , Casey T. G. , Ekama G. A. , Wentzel M. C. , Marais GvR
Published: May 2018

Experiments have been performed to investigate the hypothesis that the alternation of anoxic and aerobic conditions is the major factor influencing filamentous bulking in low F/M systems. The results provided strong supporting evidence for the hypothesis; nitrite, rather than nitrate, appears to play a dominant role in causing the bulking.
Integrated Approach for Biofilm Characterisation and Biomass Activity Control
Authors: Lazarova V. , Pierzo V. , Fontvielle D. , Manem J.
Published: May 2018

Biofilm activity control is an important requirement for the successful operation of biofilm reactors for wastewater treatment. Widely used parameters for biofilm characterisation are the biofilm thickness and total dry weight. These characteristics are, however, not sufficient to describe biofilm activity. Understanding of the physiological behaviour of the fixed biomass needs improved analytical methods and procedures. Direct application of known methods for free biomass characterisation to biofilm analysis is not always possible and is not well studied and developed.

In this paper an integrated approach is proposed for representative estimation of biofilm activity, by means of appropriate analytical methods to control biofilm dynamics and wastewater treatment process performance. The relevance of this approach is tested using different nitrifying biofilms.
Experience from More than Twenty Years of Operation of a Comprehensive Hazardous Waste Management System (Kommunekemi/Chemcontrol)
Authors: Vestergaard Niels K.
Published: May 2018

Denmark started development of its national hazardous waste management system in 1971,and since then the system has been continuously developed as a result of technical and political changes.

This paper describes the development of this national registration, collection and treatment system for oil-and chemical wastes, seen from an operator's point of view.

Development in waste amount is presented and commented on based on the corresponding political and legal actions taken due to the increased environmental concern in the country.

Trends in development of alternative treatment and recycling facilities resulting from technological developments and economical incentives are mentioned.
Evaluation of Treatment Efficiency of Processes for Petroleum Refinery Wastewater
Authors: Kean Chin Kee
Published: May 2018

Processes used in the treatment of a petroleum refinery wastewater included initial API oil separator to be followed by dissolved air flotation and an extended aeration system. The API oil separator removed most of the settleable solids and oil. The residual oil varied from around 680 mg/l to 104 mg/l and was further treated with chemical coagulation, flocculation and dissolved air flotation which remove more than 80 % of the oil and grease. Mean COD after dissolved air flotation was around 970 mg/l and it was lowered to around 378 mg/l using the extended aeration biological system at 15-day HRT. The final effluent COD/BOD ratio was high indicating the presence of a high percentage of refractory organic compounds.
Global sludge management: a status report and perspective
Authors: Spinosa L. , Kempa E. S. , Okuno N. , Vesilind P. A.
Published: May 2018

Sludge management is a more and more complex problem due to increased difficulties in locating disposal works and meeting more stringent environmental quality requirements. The most recent notable developments in conventional processing systems have regarded dewatering and stabilization, which remain essential prerequisites to any disposal method. With the increasing pressure on disposal options, such as agricultural use and landfilling, there has been a resurgence of interest in incineration. New processes and alternative uses have been proposed and experienced, but most of them still require further investigations to evaluate effectiveness and reliability. In any case, it is not realistic to search for a global solution to the problem, but the best solutions must derive from local and site-specific considerations.
Microbial aggregates in wastewater treatment
Authors: Ganczarczyk Jerzy J.
Published: May 2018

Basic forms of microbial aggregates generated in wastewater treatment and techniques used to study them, are described and discussed. The role of the free-setting velocity in evaluation of some physical properties of activated sludge flocs is emphasized. Several regression models were applied to correlate the flocs' settling velocity with flocs' size values. For the studied samples a simple linear model proved to be superior to a multiplicative one, and an introduction to this model of a settling shape factor function instead of constant intercepts, provided a very good correlation of the experimental data. It is expected that a difference between shape factors for the most stable conditions of the flocs and those for the flocs under the settling conditions will make it possible to determine softness or stiffness of these microbial aggregates.
Mechanisms of floc formation in sludge conditioning with polymers
Authors: Langer Stefan J. , Klute Rudolf , Hahn Hermann H.
Published: May 2018

In flocculation of dilute suspensions a period of slow mixing is necessary to increase the probability of particle collisions that are necessary for flocculation to occur. When flocculating sludges, the collision frequency is so high that flocs are formed immediately after rapid mixing. However, controlled mixing of the flocculated sludge for some time period does improve dewaterability. The mechanisms that are involved have been studied in detail and the subject of this paper. The results show that after rapid mixing and initial floc formation there might still be polymer in solution, depending on polymer dose. Prolonged mixing results in breakage of large aggregates and in particle/floc surfaces that are not yet covered with polymers. Subsequently the excess polymer adsorbs onto these surfaces. From changes in sludge rheology one can see that within a period of about one half to one minute the bulk properties change dramatically. After the initial floc formation the suspension is in a state characterized by a three-dimensional network structure with strongly interacting, voluminous flocs. After the mixing period there are more discrete and less interacting flocs. Especially the properties of the filter cake from pressure filtration are then more favorable.
Advanced sludge thermal processes in Japan
Authors: Hiraoka M.
Published: May 2018

As a result of the spread of sewerage systems, the management of growing quantities of sewage sludge is becoming an urgent need. As the method of sludge management, thermal processes have mostly been applied to the treatment and disposal of sewage sludge in Japan, because of the difficulty of finding final disposal sites. This paper describes the progress of thermal processing technologies, especially focusing on drying-incineration process systems and melting-slag recycling process systems.
Elimination of microcystis cyanobacteria (blue-green algae) by an ozoflotation process: a pilot plant study
Authors: Benoufella F. , Laplanche A. , Boisdon V. , Bourbigot M. M.
Published: May 2018

It is now known that since cyanobacteria (blue-green algae) occur in both swimming and drinking water supplies, and lakes and rivers, they represent an increasing hazard to animal life and human population. Moreover, high algal contents pose also a number of operation problems for water purification plants. The objective of the work is to study the elimination of a Microcystis strain of cyanobacateria by the use of an ozoflotation process which associates the oxidizing properties of ozone and the physical aspects of flotation. The functioning and the efficiency of a pilot unit is presented according to such parameters as: ozone dose, flow rate, coagulants and raw water quality. The use of ozone in pretreatment leads to an inactivation of the algal cells. Experiments let us calculate the specific ozone utilisation rate of Microcystis and the [C.t] (ozone concentration, contact time) curve is determined versus algal removal. Under real conditions, a previous coagulation stage is necessary; best results are obtained with ferric chloride. Preozonation is also of influence on the enhancement of the coagulation efficiency. Association of the ozoflotation process and bilayer filtration can solve the algae problems of waters presenting low turbidity and low organic content, and improve water quality.
Algal flocculation-sedimentation by pH increase in a continuous reactor
Authors: Yahi H. , Elmaleh S. , Coma J.
Published: May 2018

The effectiveness of microalgae flocculation by pH increase was investigated using the jar test procedure. The results indicated that pH values between 11.8 and 12 induced extensive flocculation without need of adding magnesium. pH was increased by sodium hydroxide or calcium hydroxide. In both cases, the total solids abatement was more than 95% producing sludge of excellent settleability and good mechanical resistance quantified by a destructive test. The next step was the operation of a continuous flocculator which might optionally be packed with granular sand or inert resin. It was shown that a fluidized bed or any other mechanical energy transfer device was not required to obtain more than 95% efficiency with a superficial upflow velocity of 30 m/h corresponding to a residence time through the whole unit of 5 minutes only.
Sediment accumulation in a series of four pilot-scale stabilization ponds
Authors: Ghrabi A. , Ferchichi M.
Published: May 2018

Settling and accumulation of sediments have been measured on the bottom of the facultative and three maturation ponds of a series of pilot-scale stabilization ponds. The mean deposition rate in the facultative pond showed that the attempt to establish a short-term sedimentation by in situ measurements failed. The rates were largely overestimated and the values calculated from the sediment accumulated in a long-term are closer to the reality. The sediment depth increase rates are 5 cm/year for the facultative pond and 1.3 cm/year for second and third maturation ponds. In the last maturation pond it is 1.6 cm/year.

The rate of sediments deposit (volatile solids) in the first pond can be estimated by an at−b equation.
Effects of pH on photocatalysis of 2,4,6-trichlorophenol in aqueous TiO2 suspensions
Authors: Tanaka Shuzo , Saha Uttam Kumar
Published: May 2018

The effects of pH on the photocatalytic decomposition of 2,4,6-trichlorophenol (TCP) were investigated in the presence of titanium dioxide suspensions illuminated by a high pressure mercury lamp over the wavelength range of 302-405 nm. Higher degradation rate was observed under alkaline conditions than acidic conditions. Although a rapid adsorption of TCP onto the TiO2 surface was observed at low pH and no adsorption at high pH, the role of adsorption of TCP was found insignificant in photocatalysis. With sodium chloride addition, a decrease in reaction rate was observed at pH 5 due to Cl− ions inhibition, but at pH 10 the same anions had no adverse effect on the measured photocatalytic efficiency and Na+ ions enhanced the degradation rate of TCP. With no oxygen, however, the photocatalytic decomposition of TCP in sodium chloride solution gives lower degradation rate than with dissolved oxygen and no sodium chloride at various pH. Complete mineralization requires a longer illumination time than the decomposition of the parent compound. A mechanism for the reaction based on photogeneration of hydroxyl radicals was proposed.
Nitrate and chloride formation in chloramination
Authors: Diyamandoglu V.
Published: May 2018

The formation of nitrate and chloride as end-products of chloramination (combined chlorination) was investigated at pH ranging between 6.9 and 9.6 at 25°C. The experimental results comprised concentration-time profiles of combined chlorine residuals along with nitrate and chloride. Nitrite, if present, was always below the detectibility limit of the analytical method used (25 ppb). Mass balances on chlorine species depicted that chloride formed during the slow decay of combined chlorine residuals does not account for all the chlorine lost. This substantiates the formation of other reaction end-products which are yet to be identified. A kinetic model for chloramination is proposed based on the kinetic data obtained in this study.
Fish Processing Wastewater Treatment Requirements by Line Production Changes
Authors: Battistoni Paolo , Fava Gabriele
Published: May 2018

An Italian seafood factory, engaged in the preparation of retail fish products, was investigated. The behaviour of the wastewater treatment plant constituted by a low load biological oxidation, with nitrogen denitrification was studied. Operative difficulties connected with the quali-quantitative changes in the industrial production are evidenced. The major points outlined are: start-up at design conditions, four years' management at extended oxidation (SRT = 80 days), discharge lines organization to assure plant efficiency after introducing seafood prefrying production.
Acetoclastic methanogenic toxicity produced by aliphatic organochloride solvents
Authors: Sanz J. L. , Rodríguez N. , Amils R.
Published: May 2018

The toxicities to acetoclastic methanogenic bacteria of various organochloride compounds have been determined by the head-space method. This short-term test indicates toxicity trends with tri- and tetrachlorides being the most toxic, but further work is required.
Treatment of Effluents from Hemp-Based Pulp and Paper Industry I. Waste Characterization and Physico-Chemical Treatability
Authors: Dilek Filiz B. , Gökçay Celai F.
Published: May 2018

This study was conducted to determine the wastewater characteristics as well as the treatment alternatives for the Tafköprü Pulp and Paper Mill in Turkey. The physico-chemical treatability study was conducted by standard Jar-test equipment. The highest COD removal efficiency obtained was 96% for the paper machine, 50% for the alkali extraction and 20% for the bleaching effluents by using alum as coagulant. The colour removal efficiency was around 80% for the alkali extraction effluents.
Uranium and vanadium sorption by chitosan and derivatives
Authors: Guibal E. , Saucedo I. , Jansson-Charrier M. , Delanghe B. , Le Cloirec P.
Published: May 2018

The modification of chitosan, by grafting of oxo-2-glutaric acid, allows its sorption performance to be increased. This enhancement of uptake ability is observed in overall sorption capacity and specificity in sorbing particular metals. This work focuses on the sorption of uranium (VI) and vanadium (V). The sorption isotherms are studied. The experimental results are described according to the Langmuir and Freundlich models. It was shown that uranium sorption is best described by the Freundlich model, while vanadium sorption is difficult to model. The influence of the particle size, significant in the case of uranium, but not for vanadium, shows that the sorption mechanism is not the same for the two metals : surface control is predominant in the case of uranium, due to the poor porosity of the sorbents. The control of overall sorption capacity is related to the chemistry of the metal and polymer : the appearance of hydrolyzed species and protonation of the polymer.