bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the addition of precipitants on the biological phosphorus elimination in a pilot plant
Authors: Röske I. , Schönborn Chr.
Published: May 2018

A bench-scale plant for (advanced) biological P elimination was operated with mechanically pretreated domestic sewage. It consisted of an anaerobic and an aerobic tank and a clarifier. The plant was operated with and without addition of precipitants (3 and 6 mg/l Fe). The polyphosphates were examined by nuclear-magnetic resonance spectrometry of aerobic activated sludge, in some cases after pretreatment with NaOH, and by X-ray spectrometry. The polyphosphates were associated either with Ca or with Mg and K. This became evident from the X-ray spectra of polyphosphate granules. The Mg and K was released in the anaerobic and taken up in the aerobic tank parallel to the phosphorus. The Ca on the other hand, remained immobilized. Obviously it was metabolically inactive. The addition of 3 mg/l Fe did not affect the biological P removal, and the time required for a complete P removal in the aerobic tank was even shorter than the time without addition of Fe.
Quainification and Characterisation of Nitrosomonas and Nitrobacter Using Monoclonal Antibodies
Authors: Sandén B. , Grunditz C. , Hansson Y. , Dalhammar G.
Published: May 2018

Nitrobacter and Nitrosomonas were isolated in pure cultures from two large waste water treatment plants in the Stockholm area. Using the hybridoma technique, monoclonal antibodies were produced specific for Nitrobacter and Nitrosomonas respectively. Using a competitive ELISA (enzyme linked immunosorbent assay) we can estimate cell numbers in pure cultures of the bacteria as well as in activated sludge. The antibody directed against Nitrobacter was tested with sludge from several waste water treatment plants in the Stockholm area and is able to recognise Nitrobacter, indicating a common epitope. There is a good correlation between activity measurements and cell number estimations in activated sludge indicating that we have the necessary tools to further develop a method for the quick and reliable detection and quantification of Nitrobacter and Nitrosomonas.
Molecular Identification of Activated Sludge Foaming Bacteria
Authors: Blackall Linda L.
Published: May 2018

The formation of a stable, dark, viscous foam or scum on activated sludge aeration basin surfaces is a recent and increasing problem. Microscopically, the foam is comprised of a predominance of one of a few different types of filamentous bacteria. The diversity of filaments found in the foam is increasing with time. However, two prominent foaming organisms in Australia are Nocardia amarae and Nocardia pinensis. Although these nocardioforms can be microscopically differentiated, N. amarae is indistinguishable from other foaming filaments such as Rhodococcus rhodochrous and Tsukamurella paurometabolum. Morphology is the cardinal character used in differentiating bulking filamentous microorganisms. However, microorganism morphology is a notoriously poor descriptive attribute that can vary widely depending upon nutritional conditions. The past decade has witnessed the use of molecular biological techniques as the dominant approach for the detection of microorganisms that are difficult to identify by conventional culture techniques or microscopy. The most common nucleic acid target sequences for molecular probes are found in conserved genes such as 16S rDNA. Genomic DNA was isolated from strains of N. amarae and N. pinensis. The 16S rDNA was amplified by the polymerase chain reaction and sequenced using an automated DNA sequencing machine. The sequences were compared and regions that could be exploited for oligonucleotide probes were highlighted. These regions can differentiate the two species and by comparison with sequences available in Genbank, they can differentiate N. amarae from other foaming nocardioforms for which 16S rDNA sequence information is available.
Effect of chlorinated alkenes on the reductive dechlorination and methane production processes
Authors: Zhuang Ping , Pavlostathis Spyros G.
Published: May 2018

Mixed, acetate-fed methanogenic cultures were used to assess the effect of increasing tetrachloroethylene (PCE), trichloroethylene (TCE) and cis-1,2-dichloroethylene (cDCE) concentrations on the reductive dechlorination and primary metabolism (methane production) processes. In addition, the effect of TCE on the rate and extent of the reductive dechlorination of PCE was investigated. All cultures were developed in serum bottles and incubation was carried out at 35°C in the dark. Soil samples from two sites contaminated with chlorinated solvents served as the inoculum for this study. All chlorinated alkenes used were supplied as saturated solutions in the culture media. The rate of PCE dechlorination increased with increasing PCE concentrations. Both TCE and cDCE showed an increase in the dechlorination rate up to a solvent threshold concentration followed by a decrease. In all cases, the methane production rate decreased as the chlorinated alkene concentrations increased. However, the effect of chlorinated alkenes was more pronounced on methane production rather than on the extent of dechlorination. The relative toxicity of the chlorinated alkenes tested in this study formed the following ascending series: PCE < TCE < < cDCE.
Biomass Reduction and Mineralization Increase Due to the Ciliate Tetrahymena pyriformis Grazing on the Bacterium Pseudomonas fluorescens
Authors: Ratsak C. H. , Kooi B. W. , van Verseveld H. W.
Published: May 2018

The currently high sludge production and increasing processing costs call for waste-water treatment plants with high purification efficiency and low biomass production. We studied the latter issue through two-stage chemostat cascades to assess the overall biomass reduction due to ciliate grazing. The bacteria were cultured in the first chemostat whereas the ciliates, grazing on the bacteria from the first chemostat, were cultured in the second chemostat. Mathematical modelling was used to describe the bacteria/ciliate dynamics and some of the growth parameters were fitted. In the second chemostat 22-44% of the carbon originating from the first chemostat was mineralized to CO2. An extra biomass reduction of 12-43% was possible due to grazing by the ciliates. At lower growth rates of the ciliates the extra biomass reduction was higher than at high growth rates. This finding is auspicious, suggesting that predator organisms indeed can reduce sludge production.
Experimental Approaches for the Characterisation of a Nitrification/Denitrification Process on Industrial Wastewater
Authors: Bortone G. , Čech J. S. , Germirli F. , Bianchi R. , Tilche A.
Published: May 2018

Laboratory experiments were carried out to evaluate the feasibility of the biological removal of nitrogen from mixed textile (80%) and municipal (20%) wastewater. Three modified “Ludzack Ettinger” bench scale plants were used. Wastewater characterization and process kinetic constants were evaluated experimentally. The results of this experience demonstrated that long sludge age is necessary in order to overcome the nitrification inhibitory effect of some compound(s) that were present in the treated wastewater. Moreover it can be concluded that experimental approaches are necessary to make reliable design of a full scale industrial wastewater treatment plant.
Effects of hydraulic and medium characteristics on solute transfer to surface runoff
Authors: Lai J. L. , Lo S. L. , Lin C. F.
Published: May 2018

A two-stage scouring-based model including two parameters for each stage, the ultimate scoured depth and rate of change of scoured depth, was developed to describe solute transfer to surface runoff. While the first stage is a quick decrease of mass loss of solute to surface runoff, the second stage is a slow one. An experimental flume with a medium packed bed was designed. Four different sizes of glass beads were chosen to be the media and saturated with uniform concentration (20000 ppm) of potassium chloride solution before runoff occurred. In a series of experiments, runoff was passed at varied flow rate, velocities, and depths over the medium bed. Runoff samples were taken at the end of flume and the concentration of potassium chloride analysed. By use of this model, the dimensionless ultimate scoured depth and the dimensionless rate of change of each stage were investigated. The results showed that the Reynolds number within media and the relative length were two important factors affecting mass loss of chemicals.
Kinetic Selection of Microorganisms by Means of a Selector – Twenty Years of Progress: History, Practice and Problems
Authors: Chudoba P. , Pujol R.
Published: May 2018

Historical development, as well as the main principles of a kinetic selection theory (KST) of non-filamentous microorganisms is reviewed, and the original definition of a selector for filamentous bulking sludge control is given. The idea of a selector based on KST originated from experiments with a compartmentalized system at the beginning of seventies. Since that time, KST has been completed and confirmed by additional experiments with both intermittent substrate feeding and influence of degree of longitudinal mixing on sludge bulking. Nevertheless, numerous examples of practical use of a selector showed both positive and negative results on filamentous bulking control. Consequently, it is concluded that due to both a large diversity of filamentous organism's physiology and a complexity of bulking phenomena, there is no universal method to control the growth of all filamentous species. For each case, a specific analysis is necessary before choosing the specific solution. In the case of low F/M bulking with filaments like Microthrix p., types 0041 or 0092, the application of KST using contact zone has given good results for several full scale treatment plants.
Nitrification Kinetics in Activated Sludge with Both Suspended and Attached Biomasses
Authors: Chudoba P. , Pannier M.
Published: May 2018

A series of nitrification kinetic tests was carried out with both suspended and fixed biomasses originated from a combined activated sludge system with a plastic support for biomass growth introduced into the aeration tank (Experimental combined unit - ECU). The results of these batch tests were compared with kinetics calculated from continuously run pilot plant. It was concluded that nitrification kinetics of both suspended and attached biomasses were similar and, consequently, it was assumed that the percentage of autotrophs is the same in both biomasses. The kinetics determined in both batch and continuous systems were comparable. Kinetic constants measured for suspended biomass of the ECU were higher than those reported by the literature, which was attributed to an overaeration of the ECU and an energetic mixing
Alternative Strategies for Meeting Stringent Effluent Guidelines
Authors: Wesley Eckenfelder W.
Published: May 2018

Stringent effluent guidelines relating to volatile organic carbon (VOC), effluent toxicity and priority pollutants require a reappraisal of design criteria for wastewater treatment plants in the chemical and petrochemical industry. In the case of volatiles, the biodegradability of the VOC as well as the type of aeration equipment needs to be considered. High temperatures in covered aeration basins can create serious sludge settling problems. Priority pollutant removal requires careful consideration of adequate sludge age. Temperature is particularly significant in reducing priority pollutants to acceptable levels.

The generation of non-degradable by-products, SMP, can create effluent toxicity problems. This may require tertiary treatment with activated carbon.
Hydrochloric Acid Recycling from Chlorinated Hydrocarbons
Authors: Sowieja D. , Schaub M.
Published: May 2018

Chlorinated hydrocarbons present a major ecological hazard since most of them are only poorly biodegradable. Incineration is an economical process for their destruction, however the usually recovered sodium or calcium chlorides do not present a value and their disposal may even be very costly. Recovery of hydrochloric acid may therefore present an economical solution, mainly where large quantities of highly chlorinated compounds can be processed.
Combined action of electro-osmotic drainage and mechanical compression on sludge dewatering
Authors: Gazbar S. , Abadie J.M. , Colin F.
Published: May 2018

The efficiency of the implemented industrial means of sludge dewatering, at the present time, is not sufficient. Therefore, research of new techniques of advanced dewatering is necessary. Electro-osmotic drainage, notably used to consolidate soils, has recently been used to dewater sludges. In this work, a laboratory cell has been constructed. It permits one to superimpose a mechanical pressure adjustable to 7 kg/cm2 to the electro-osmotic drainage. The application of an electrical field decreases the specific resistance of sludges to filtration with variable factor, which can result from both the electrical conductivity and the charge of the particles. However, in thickening, it enables organic sludges to reach very high solids concentration when compared to their dewatering by filtration under high mechanical pressure. The energy consumption does not seem to be an important constraint in sludge dewatering with this technique.
Wastewater Treatment and Integrated Environmental Protection at the BASF AG in Ludwigshafen, Germany
Authors: Strotmann U. J. , Weisbrodt W.
Published: May 2018

A large chemical complex like BASF AG in Ludwigshafen has a high demand of process and cooling water. Therefore, water protection and wastewater treatment are predominant tasks. With the help of a dual sewage system for the separate discharge of cooling water and process water an efficient wastewater management is made possible. The cooling water is continuously supervised for contaminations and directly discharged into the river Rhine whereas the process water is treated in a central wastewater treatment plant. The daily amount of wastewater treated is up to 600,000 m3. The BOD5 removal is about 98% and the TOC and COD removal about 88%. As wastewater management is closely connected to waste minimization several examples for waste minimization processes are discussed. Furthermore, also important topics of environmental safety of the products produced at BASF AG are presented.
The behavior of ash components in the sludge melting process
Authors: Fukui Tunekazu , Murakami Tadahiro , Ichikawa Muneharu
Published: May 2018

The Coke-bed sludge melting process is used for incinerating sewage sludge and producing slag that is recycled as construction materials. The behavior of ash exiting the melting furnace was examined. Heating tests were carried out with different kinds of sludge. Heating from 600°C to 1200°C, weight reduction of around 30% was measured, but reduction rate was due to the kind of sludge. Weight reduction was big when heating up to 815°C, and reduction at a temperature over 815°C was due to the type of sludge. Main materials causing weight reduction were unburnt carbon (C) and some other elements like sulfur (S), chlorine (Cl), some metals like sodium (Na), potassium (K) and oxygen (O) released from some kinds of oxides. Even though very small quantity, zinc (Zn) and lead (Pb) were also vaporized. Some of these vaporized substances precipitate and produce fine particle dust at the low-temperature section of gas treatment facilities. Washing harmless salts out from the dust then recycling the dewatered dust in the melting furnace was found to be effective in maximizing slag recovery and reducing the precipitator load.
Response of mixed cultures of chlorella vulgaris and heterotrophic bacteria to variation of pH
Authors: Mayo A. W. , Noike T.
Published: May 2018

The effects of hydrogen ion concentration on the growth of heterotrophic bacteria and alga Chlorella vulgaris, one of the dominant species in waste stabilization ponds were investigated in fed batch cultures. Glucose used as a source of organic carbon was fed daily in granular form and pH was controlled between 3.0 and 11.5 by addition of either HCl or NaOH. Heterotrophic bacterial densities were highest between pH 4.0 and 5.5, but the growth rate of Chlorella vulgaris was optimum at pH 4.5∼8.0. Chlorella vulgaris was sensitive to alkaline pH values, with maximum growth rates, μmax, of 2.03, 1.12 and 0.75 d−1 at pH 7.0, 9.0 and 10.0, respectively. The saturation constants, Ks, for the same pH values were 181, 157 and 52 mg/l, respectively. The optimum total biomass yield was 0.381 mg POC/mg glucose and was observed at pH 5.5∼8.0, but the magnitude was strongly influenced by the pre-culture pH conditions. Glucose metabolism was significantly affected at alkaline conditions than at acidic conditions. These results also suggest that in a mixed culture with bacteria, algae are largely responsible for glucose metabolism, with apparent saturation constants at pH 7.0 of 27 mg/l and 181 mg/l for bacteria and Chlorella vulgaris, respectively.
Effect of microalgae growing on wastewater batch culture on escherichia coli and vibrio cholerae survival
Authors: Mezrioui N. , Oudra B. , Oufdou K. , Hassani L. , Loudiki M. , Darley J.
Published: May 2018

The stabilization pond is one of the more important biological wastewater treatment systems, applied in many countries. An experiment treating wastewater by stabilization ponds under the arid climate of Marrakesh (Morocco) has been underway since 1985. The experimental installation, made from two lined stabilization ponds, received domestic sewage which carried not only the organic load but also a significant bacterial load and other microorganisms. In this new habitat, the cells' bacterial behaviour was affected by various physico-chemical and biological factors. It appears that in such treatment system, known for excessive algal production, the microalgae has evidently an influence on bacterial growth. In this paper, we proposed to appreciate how microalgae essentially: Chlorella (Chlorophyta), Synechococcus andSynechocystis (Cyanobacteria), can affect the behaviour, survival and temporal evolution of Escherichia coli and Vibrio cholerae. In wastewater stabilization ponds of Marrakesh high levels of V. cholerae and low concentrations of coliform bacteria were noted during summer periods. This period coincided with a bloom of picocyanobacteria associated with a weak relative abundance of Chlorella. Some interactions tests were carried out with these bacteria and these algae, using a treated wastewater batch culture. Results show that the green algae reduces V. cholerae (pathogenic bacteria) abundances more than E. coli (fecal contamination bacteria) where as better survival of this pathogenic bacteria was noted in presence of Cyanobacteria. The die-off of E. coli appears to be more reduced in presence of Cyanobacteria than Chlorella. Furthermore, the alkaline pH seems to present a more bactericidal effect on E. coli than on V. cholerae. Thus, the Cyanobacteria blooms, associated with a weak percentage of Chlorella abundance, occurring periodically during summer in sewage stabilization ponds of Marrakesh, will be considered as one of the major factors leading to high levels of V. cholerae and low abundances of fecal coliform bacteria during the hot period.
An innovative approach to reduce excess sludge production in the activated sludge process
Authors: Yasui H. , Shibata M.
Published: May 2018

A new process has been developed to reduce excess sludge production, in which both excess sludge digestion and wastewater treatment are conducted simultaneously in the same aeration tank. The ozonation enhances biological degradation of the activated sludge, which is decomposed in a subsequent biological treatment. A considerable amount of biomass is mineralized biologically in proportion to the amount of recirculated biomass from the ozonation stage to the biological stage. It was observed that the amount of excess sludge is reduced to nearly zero when 1.2 kg/m3-aeration tank volume of biomass is recirculated in a day from the biological stage to the ozonation stage at a BOD loading of 1.0 kg/m3/d. A biomass concentration of 4200 mg/L was maintained at 1.0 kg-BOD/m3/d without drawing excess sludge for 6 weeks of experimental period under ozone dose of 0.05 g-O3/g-SS and recirculation rate at 0.3 d−1. Only a limited difference in the effluent quality was observed between the new process and the conventional activated sludge process.
Data-Handling and Management of Preventive Measures Using a Dynamic Integrated Monitoring System
Authors: Lynggaard-Jensen A. , Balslev P. , Nielsen M. K.
Published: May 2018

The concept and procedures of a data-handling system, which can be described as a “Dynamic Integrated Monitoring System” are presented together with examples which can be produced by such a system. The monitoring is based on on-line measurements, laboratory analyses on different types of samples, information on raw materials and products as well as the production equipment/facilities used. The data-aquisition (online and off-line) is controlled by a management system, which secures the coordination, fastest updating and follow up of the key element in the system – the data.

In order to turn the data into useful information, the former is continuously processed, validated and stored, while simultaneously quantitative information and operation indexes are calculated. Through application procedures, this basic information is now used for several different tasks such as alarms, statistics, emission control and prognosis, waste minimization and long term general environmental management.
Industrial Waste Management in the Athens Area
Authors: Christoulas D. G. , Andreadakis A. D. , Katsiris N. , Kouzeli-Katsiri A.
Published: May 2018

Industrial contributions constitute as much as 20% of the 700 000 m3 .d−1 of sewage discharged to the Saronikos gulf through the sewerage system which serves the Greater Athens area. The main industrial discharges originate from food, textile, pulp and paper, chemical, tanning and metal processing and electrical industries. In the majority of the cases the pretreatment is inadequate and the existing emission standards are violated. This results in increased concentrations of toxic metals in the sewage. The impact of these toxic discharges on the marine environment and the sewage treatment works have been investigated. Increased concentrations in the water column and the sediments have been reported but there are no indications of accumulation of toxic metals in the body of benthic organisms. The impact on the imminent operation of the treatment works for the sewage of Athens, have been investigated with the aid of pilot and bench scale studies. The results did not indicate a serious inhibition of the sensitive digestion and nitrification processes. However due to the high concentrations of the heavy metals, with average values approaching threshold values, it is important that appropriate action is taken to control industrial discharges through a revised and rational regulatory framework.
Inhibition of the Nitrification Process in Municipal Wastewater Treatment Plants by Industrial Discharges
Authors: Grüttner H. , Winther-Nielsen M. , Jørgensen L. , Bøgebjerg P. , Sinkjær O.
Published: May 2018

More than three years of pilot-plant operation has documented that inhibition of nitrification was found to influence the dimensioning of the largest Danish wastewater treatment plant, which serves a major part of Copenhagen. Hence, a program for investigating the sources of substances inhibitory to nitrification was initiated. Since the number of substances potentially inhibitory to nitrification is very high, the investigations used direct testing of inhibitory effects on nitrification as a tool for the mapping operations.

The overall purpose of the investigation was to determine the types of sources of inhibitory substances and to suggest a program for source control to be implemented by the individual municipalities in the catchment area. This paper describes the strategy for sampling and the results of the first two years of activity. Major conclusions have been that the most important sources of inhibitory substances are to be found among the industries, and that nearly all of the industries investigated exhibited some kind of inhibitory effect Further, is was demonstrated that the toxic unit calculation might be used in the quantification of the sources, and that the observed effects could be explained by the chemical substances in the wastewater from the industries.

Based on the above described results, a strategy for control of the inhibitory effects at the different levels of the catchment area was suggested.
Reutilization of ammonia from wastewater using cation exchange resins
Authors: Buday M.
Published: May 2018

The paper deals with adsorption of ammonium ions from wastewater of ammonia and ammonium nitrate plant on cation exchange resins. The aim of the treatment was not only separation of ammonium ions but also their return to the technology of ammonium nitrate fertilizer. Therefore, it was desirable to obtain high concentration of eluate. The columns of cation exchangers were arranged in the so-called “coupled columns” technique. The results were obtained on the pilot scale (0.6 m3.h−1) and in full scale (50 −110 m3.h−1) plants. Nitric acid was used for the regeneration of the exhausted resins. Its concentration was in the range of 3.9 − 7.0 mol.1−1. The average ammonium concentration of the eluate was in the range of 0.95 − 2.35 mol.l−1. This parameter of the treatment process depended on the pH value of wastewater and on the concentration of the regenerant. The concentration of ammonium nitrate achieved in the eluate is sufficient for its utilization in the technology for the ammonium nitrate fertilizer production.
Filtration of submicron particles: effect of ionic strength and organic substances
Authors: Prasanthi H. , Vigneswaran S. , Waite T. D. , Aim R. Ben
Published: May 2018

Hematite (α-Fe2O3) suspension was used in this study to investigate the effects of aggregate size and solution chemical characteristics on particle removal and headloss development in a deep bed filter. When electrolyte (KCl) concentration in the suspension was increased from 0-80 mM, the size of hematite aggregates in suspension increased from 85 to 990 nM but had no significant effect on zeta potential. It was found that at low KCl concentrations (0-10 mM), the initial removal is governed by surface chemical properties while at higher concentrations (40-80 mM), the effect of particle size (steric effect) predominates. The transient stage filter performance was found to be controlled by the favourable chemical conditions prevailing in the filtration system rather than the size of the particles.

Studies of the effect of a natural organic material (fulvic acid) on particle removal indicated that fulvic acid at low concentrations (less than 0.75 mg/L) enhanced particle aggregation and improved filtration efficiency. At concentrations higher than 2 mg/L, it was found to increase the stability of particles thus affecting filtration efficiency.
The effect of different oxidation and filtration processes on the molecular size distribution of humic material
Authors: Kainulainen T. , Tuhkanen T. , Vartiainen T. , Heinonen-Tanski H. , Kalliokoski P.
Published: May 2018

The effect of different oxidation and filtration processes on the amount and character of organic matter in drinking water was studied. TOC, KMnO4 value, colour and fractions of humic material were analyzed from bank filtrated lake water, chemically coagulated and sand filtrated water, ozonated, O3/H2O2 treated, chlorinated, granular activated carbon (GAC) filtrated and nanofiltrated water. Size exclusion chromatography was used to separate different fractions of humic molecules. Six different fractions were found from bank filtrated lake water and from chemically coagulated and sand filtrated water. The molecular weight of humic fractions ranged from about 1000 (the last fraction) to about 100 000 dalton (the first fraction). Most of the humic molecules of bank filtrated lake water were found in the third and fourth fractions. After the oxidation and filtration processes the first fraction of humic molecules disappeared completely and the fourth and fifth fractions dominated. The total sum of the humic fractions was most effectively reduced after the O3/H2O2 treatment, by about 70%.
Evaluation of Two Upflow Anaerobic Digesters Purifying Industrial Wastewaters High in Organic Matter
Authors: Howgrave-Graham Alan R. , Isherwood Helen A. , Mike Wallis F.
Published: May 2018

Two full-scale anaerobic digesters, one a clarigester purifying a maize processing wastewater and the other with an upflow anaerobic sludge blanket (UASB) configuration treating brewery effluent, contained well settling, granular sludges efficient in pollutant removal. Due to differences in both digester design and feed composition, the sludges differed in activity and microbial population. The clarigester granules contained a diverse population with a multiformity of hydrolytic, acidogenic and acetogenic bacteria while the predominant methanogens, in order of significance, were Methanothrix and Methanosarcina. These granules did not reconstitute on re-start up following digester shutdown and possible reasons for this are discussed. The UASB granules contained a more uniform population with three major microbial morphotypes, the predominant methanogens being Methanothrix and, possibly, Methanobacterium. In this paper the differences in digester design, feed composition, sludge microbiology and process performance are discussed.
Pretreatment of Complexed Metal Wastewaters
Authors: Tünay Olcay , Kabdasli Isik , Tasli Rüya
Published: May 2018

This study investigates the applicability of hydroxide precipitation to complexed metal wastewaters using inorganic cations that may function as ligand sharing agents. Within this context Ca2+, Fe2+, Fe3+, Mn2+ and Mg2+ cations with the metals Cd and Cu and EDTA and NTA as ligands are used to define the systems for which theoretical and experimental evaluations are made. Results indicate that calcium is the only cation that effectively binds the ligands that makes it possible to apply the hydroxide precipitation. Fe2+ and Mn2+ are not effective due to their rapid oxidation. Mg2+ is found partly effective but may not be adequate for pretreatment purposes.
Assessment of the ecological value of rivers in flanders (Belgium)
Authors: Wils C. , Schneiders A. , Bervoets L. , Nagels A. , Weiss L. , Verheyen R. F.
Published: May 2018

Assessment of the ecological value of streams and rivers is important to determine which watercourses should be preserved for the future. Throughout the world, a large number of evaluation systems have been developed either to assess complete river systems or merely to evaluate the water quality.

However, in a region such as Flanders, where rivers are generally very polluted, it is not only important to evaluate the current ecological value, but also to recognize those watercourses which still have a high potential value. For this purpose a system was developed in Flanders to assess the present as well as the potential ecological value of streams and rivers. The evaluation is based on a number of morphological characteristics, on the water quality and on the aquatic communities. The result is a global ecological evaluation map of each river basin. This map is made available to policy makers in order to assist in the elaboration of purification programmes and river restoration and conservation projects.
Analysis of sampling frequency in groundwater quality monitoring systems: a case study
Authors: Szucs Andrea , Jordan Gyözö
Published: May 2018

Sampling frequency is one of the most crucial factors in the design of groundwater quality monitoring systems. Monitoring systems in general have two major objectives: (1) to describe natural processes and long-term changes and (2) to serve as alarm-systems and detect single pollution events. A comparison between two data sequences of different sampling frequency - weekly and monthly - is made through an example of the groundwater quality monitoring system in the karstic region of the Transdanubian Mountains in Hungary. Hydrogeochemical time series were first decomposed into their components: trend, periodicity, autocorrelation, and rough in succession. In order to identify outliers within the rough, Exploratory Data Analysis (EDA) was applied. Optimal sampling frequency was determined based on the analysis of the above components. Results have shown that: (1) seasons shorter than two months do exist in the studied time series which cannot be captured by monthly sampling; (2) for monitoring seasonal processes samples should be collected at the Nyquist frequency (at least two samples per period); for pollution detection autocorrelation lag-time (or semi-variogram range in time) should determine the sampling distance; in the lack of autocorrelation property the analysis of outliers should guide the sampling design; (3) cross-correlation analysis between precipitation and the observed parameters indicative of pollutant travel time yields valuable additional information on the pollution sensitivity of the hydrogeological system.
Microtox evaluation of industrial wastewaters
Authors: Lin Cheng-Fang , Hao Oliver J. , Jeng Fu-Tien
Published: May 2018

The main purpose of this study was to establish an inhibitory database using the Microtox assay for different wastes. The waste samples included 19 pretreated industrial wastes from two different industrial parks, 11 other industrial wastes outside industrial parks, and different treatment process effluents. The following is a brief summary of the findings from this study: (1) COD and BOD had a close relationship among different wastes; (2) Microtox data did not correlate with the conventional parameters of BOD, COD and SS; (3) many wastes did not meet the pretreatment standards and exhibited high Microtox toxicity; (4) some wastes exhibited high Microtox toxicity, although they met the pretreatment standards; (5) the mixture of the individual wastes exhibited an antagonistic effect; (6) the activated sludge process removed 60-75% of influent toxicity; and (7) the final effluent sometimes showed an increase in Microtox toxicity.
Chlorination byproducts of 4,4′-methylene dianiline(MDA) and their mutagenicity
Authors: Tsuchiya Y.
Published: May 2018

A mutagenicity study was carried out on 4,4′-methylene dianiline(MDA) an epoxy resin hardener and chlorinated MDA using an Ames Salmonella/microsome assay. As reaction products of MDA with chlorine in the water six spots were observed by thin layer chromatograph(TLC) and high performance liquid chromatography(HPLC) analysis revealed eighteen peaks on the HPLC chromatogram. MDA exhibited mutagenic activity for strain TA100 in the presence of S9 mix. In the mutagenicity test of chlorinated MDA corresponding to 7.8∼250 μg/plate, at 250 μg/plate the specimen showed mutagenic activity for strain TA98 without S9 mix, but more diluted specimens had no mutagenicity. At 31 and 250 μg/plate, the specimen showed weak mutagenic activity for the strain TA98 in the presence of S9 mix. The strain TA100 without S9 mix was killed on the culture plate with 250 μg/plate. However strong mutagenicity such as net revertant colonies 1270 per plate was obtained with the diluted specimen of 7.8 μg/plate. At 31 μg/plate, the specimen showed mutagenic activity for the strain TA100 with S9 mix. The mutagenicity test of five fractionated specimens from the TLC analysis, spot No. 1 and No. 2 showed no mutagenicity for strain TA98 and TA100 with and without S9 mix. The specimen of Spot No. 3 exhibited weak mutagenic activity for strain TA98 without S9 mix, the specimen of spot No. 4 at 125 μg/plate showed mutagenicity for strain TA98 and TA100 with and without S9 mix, and diluted samples showed high mutagenic activity for strain TA100 with and without S9 mix. Several newly identified mutagenic substances were found to be produced by the chlorination of MDA. GC/MS analysis of chlorinated MDA revealed eleven compounds on the chromatogram. Benzaldehyde, benzoquinones and chloroanilines were identified. However, the structural formula of the highly mutagenic substances could not be determined by GC/MS.
Fate of tricresyl phosphate isomers in Kurose River (Japan)
Authors: Kyung Jin Cho , Takimoto Kazuto , Okada Mitsumasa
Published: May 2018

The origin and fate of TCP isomers were studied in Kurose River, Hiroshima, Japan. As main factors controlling the fate, the adsorption characteristics of TCP isomers onto sediment and biodegradation in river water and sediment were studied. Concentration of TCP isomers in river water, sediment and SS were the highest in autumn (about ten times as large as in winter). High concentration of o-TCP was noted except in spring. In contrast to other seasons, in summer the concentration of o-TCP was relatively low and m-TCP was not detected. These variations seemed to be due to the difference in the rate of biodegradation with temperature. The concentrations of TCP isomers increased with the increase in flow rate under flood conditions. TCP in the river originated from non-point sources and not from wastewaters or atmospheric origins. The adsorption of TCP isomers on sediment followed Freundlich isotherms. No equilibrium was observed between bottom sediment and river water, indicating TCP was biodegraded rapidly in the bottom sediment. The biodegradation rate in the sediment was lowest for o-TCP and highest for p-TCP. The biodegradation rate of m-TCP was small under low temperature, whereas it was large in high temperatures above 20°C. The most biodegradable isomer, p-TCP, was not detected in most cases.
Eutrophication in stratified deep reservoirs
Authors: Straškrabová Vera , Hejzlar Josef , Procházková Lidmila , Vyhnálek Vojtech
Published: May 2018

The response of phytoplankton development to an increased nutrient input in deep canyon-shaped stratified reservoirs was shown in four case studies. In contrast to lakes, specific features were described: longitudinal succession of phytoplankton development along the valley, transport of algal biomass and the peculiarities of P loading to epilimnion during summer stratification. Long term studies in two reservoirs showed the fluctuations of particular plankton components due to variations in flushing rate on the one hand and fish succession leading to prevalence of planktivorous species on the other.
Water management of two shallow urban eutrophic lakes
Authors: Romo Susana , Bécares Eloy
Published: May 2018

The efficiency and effects of aluminium sulphate on water quality of two shallow urban eutrophic lakes of Madrid (Spain) is reported. Almost all the controlled variables improved with the treatment, especially nutrients, pH and transparency. The application of the method during spring and summer reduced nutrient content for the remainder of the seasons. However, phytoplankton density in both lakes needs supplementary measures for long-term control. The treatment seems not alter fish populations.
Nitrogen and biological phosphorus removal in submerged biofilters
Authors: Gonçalves R. F. , Nogueira F. N. , Le Grand L. , Rogalla F.
Published: May 2018

An operational procedure is presented which enables biological phosphorus removal to be performed using a set of five submerged high rate biofilters. The new process was developed using an upflow biofilter with floating filter media, originally conceived to perform nitrification and denitrification of wastewaters (Biostyr-ND). Anaerobic contact periods were introduced in the functioning periods of the biofilters under continuous feed, ensuring alternating anaerobic/aerobic conditions (A/O) on the fixed biomass. The selection of phosphate-removing bacteria in the biofilm was verified by the efficiency of P removal (60 - 70%) and by the high concentrations of total P in the sludge removed from the system during backwash (≈ 3.4 % Pt/TSS). The activity of the autotrophic nitrifying bacteria was not affected by the alternating A/O conditions reached values close to 1 kg N-NH4/m3d. An improvement in the denitrification process was observed due to carbon storage during anaerobic contact.
Ecological interactions among denitrification, poly-P accumulation, sulfate reduction, and filamentous sulfur bacteria in activated sludge
Authors: Yamamoto-Ikemoto Ryoko , Matsui Saburo , Komori Tomoaki
Published: May 2018

Effects of anoxic-oxic conditions on the growth of sulfate reduction, poly-P accumulation and filamentous sulfur bacteria were examined in the laboratory scale sequential batch reactors. In the anoxic-oxic conditions, denitrification bacteria are dominant. The growth of sulfate reducing bacteria and poly-P accumulating bacteria was suppressed. The number of sulfate reducing bacteria in the activated sludge was below 104 MPN/g MLSS, and the sulfate reduction rate was very low. Filamentous bulking was also suppressed. On the other hand, when nitrate was removed from the artificial wastewater, sulfate reducing bacteria could grow predominantly in the anaerobic conditions. The number of sulfate reducing bacteria was about 106∼107 MPN/g MLSS and the sulfate reduction rate increased (0.17 ∼ 0.21 g SO4/g MLSS·hr). Filamentous bacteria Type 021N increased over 103 cm/mg MLSS. Sodium molybdate was added to the artificial wastewater in order to prevent sulfate reduction. When the concentration of sodium molybdate increased to 980 mg/L, the number of sulfate reducing bacteria decreased to 103 ∼ 104 MPN/g MLSS and the sulfate reduction rate decreased. Filamentous bulking was completely suppressed in these conditions. These results show that sulfate reduction is a main trigger of the filamentous bulking due to Type 021N that can utilize reduced sulfur for an energy source.
The influence of cadmium on activated sludge activity
Authors: Zarnovsky L. , Derco J. , Kuffa R. , Drtil M.
Published: May 2018

The influence of solid retention time, cadmium loading and the effect of the process of acclimation on the activity of activated sludge in the presence of the metal were studied. Activated sludge was cultivated in plug-flow and continuous completely mixed lab-scale bioreactors. Respirometric measurements were applied to evaluate the inhibition effects of cadmium on activated sludge. Monod's equation and the equation of non-competitive inhibition were applied to describe the toxicity and inhibition of cadmium. Maximum inhibition effect of cadmium was observed at different time periods of cadmium acting on both acclimated and non-acclimated sludges. The dependence of the attainment of maximum inhibition effect on the metal loading as well as solid retention time was observed. Therefore, maximum inhibition should be included in the assessment of metal toxicity.
A survey of filamentous foaming in activated sludge plants in Hong Kong
Authors: Chua H. , Le K. Y.
Published: May 2018

Of five major secondary sewage treatment works surveyed during 1993 in Hong Kong, two had frequent foaming in the activated sludge plants which resulted in unmanageable operational problems. In this study, branched-filamentous Nocardia amarae was identified as the main causative bacteria in foaming sludges. In vitro studies showed that fatty acids that are commonly found in municipal sewage could be utilized by N. amarae as the sole carbon source, and presence of these fatty acids in sewage could stimulate growth.
Real-time expert system control of anaerobic digestion
Authors: Chynoweth D. P. , Svoronos S. A. , Lyberatos G. , Harman J. L. , Pullammanappallil P. , Owens J. M. , Peck M. J.
Published: May 2018

The objective of this research was to develop on-line measurement and feed-back control strategies for evaluation and optimization of a glucose-fed CSTR digester. Using methane yield as a direct on-line measurement, a model and algorithm were developed and applied for feed-back control and adaptive optimization of the digester for temperature. The model and algorithm were modified and integrated into an expert system to use methane production rate and dilution rate to automatically detect and recover digester abnormal performance resulting from underloading, overloading, and addition of an inhibitor (phenol). On-line fluorometric measurement of NADH, which is a measurement of overall microbial activity, was evaluated for its potential contribution to this control strategy.
Comparison of single-stage and two-stage activated sludge processes for the expansion of the Innsbruck WWTP
Authors: Winkler H. K. , Widmann W.
Published: May 2018

A modification of the legal framework conditions shortly prior to the commencement of the construction works in the course of the expansion of the Innsbruck WWTP, necessitated a design adaptation for the new effluent standards to be met. The time pressure and doubts whether the initially chosen AB process did in fact constitute the optimum solution for the WWTP expansion under the new boundary conditions, led to the installation of a pilot plant with the aim of simultaneously testing the single-stage and AB processes. During the elaboration of the pilot plant tests, the AB process was optimised step by step so as to allow the achievement of the required effluent concentrations with a similar degree of reliability as accomplished with the single-stage plant. The comparison of investment and operating costs as well as plant operation and plant layout ultimately led to the choice of the single-stage alternative.
Upgrading of the wastewater treatment plant of the city of Oldenburg
Authors: Kayser Rolf
Published: May 2018

Instead of a planned two stage activated sludge plant the design was changed to a single stage activated sludge plant with enhanced biological phosphate removal and pre-anoxic zone denitrification. For flexible operation it is possible to vary the rato of VD/V from 0.3 to 0.5. Problems with the aeration equipment in the nitrification/denitrification cells occurred and were solved. The circular clarifiers are equipped with scrapers. Instead of a sludge hopper a collector in the centre of the tank was constructed.
Modelling of a plug-flow pilot reactor producing VFA by anaerobic fermentation of municipal solid wastes
Authors: Sans C. , Mata-Alvarez J. , Cecchi F. , Pavan P.
Published: May 2018

The production of volatile fatty acids (VFA) by anaerobic fermentation of municipal solid wastes was studied at pilot-plant level. A plug-flow reactor (80 1 total volume) without solid or liquid recirculation was employed to digest a mixture of two types of organic fraction of the municipal solid waste (OFMSW): OFMSW mechanically selected and OFMSW coming from a market of fruit and vegetables. The acidogenic process was studied at different retention times (between 2 and 6 days) in the mesophilic (37° ± 2°C) range of temperature. The VFA concentration obtained in the first valve of the tubular reactor ranged from 9.1 to 13.4 g 1−1 and in the outlet sludge oscillated between 11.8 and 23.1 g 1−1, increasing when increasing retention time from 2 to 6 days. A mathematical model of a continuous steady state plug-flow reactor proposed in a previous paper was used to represent the VFA production obtained experimentally. The results obtained when fitting the mathematical model with the experimental results were not sufficiently good. Some modifications of the initial model were considered. The best fitting of the results was obtained when the inhibition effect of the fermentation product on microorganisms growth was taken into account. The errors of this fitting, calculated by least squares, can be considered optimal for retention times between 4 and 6 days, while at shorter retention times the inhibition effect of pH and product makes the volatile acid production lower than the values obtained experimentally.