bluuebunny/crossref_metadata_2025 huggingface dataset:
CHARACTERIZATION OF INDUSTRIAL WASTEWATER TREATMENT DYNAMICS USING FAST FOURIER TRANSFORM ANALYSIS
Authors: Bécares Eloy , García-Olivares Antonio J.
Published: May 2018

Fast Fourier transform analysis has been applied to decompose the variance of some temporal series from an A + B industrial wastewater treatment system, as well as to discriminate which frequencies are basically contributing to parameter variability. The basic oscillations of the effluents, evaluated by means of the total COD, are shown to be mainly dependent on the internal dynamics of the reactors, whose design and control features are the generating forces for the final effluent fluctuations. Owing to the shorter retention time in the first reactor, the output signal was more complex than the input one. Although the second reactor reduces system complexity, it does not have an important effect on the final total COD.
INDUSTRIAL WASTEWATER TREATMENT TODAY AND TOMORROW
Authors: Pols H. B. , Harmsen G. H.
Published: May 2018

The way we treat our wastewater nowadays is not always favourable for improving the quality of our environment. Indeed, the quality of the surface waters has increased by the high investments we have made in our treatment facilities, but it cannot be denied that these same facilities have a major impact on other environmental issues. From ibis point of view the question is raised as to which treatment techniques are favourable not only for the water phase, but also from the viewpoint of energy, waste production and renewal of resources. Over thirty techniques, all of them chemical/physical treatment techniques, have been reviewed, especially for the treatment of industrial wastewaters. More importantly, these techniques have been analysed thoroughly in a multi-criteria-analysis, not only for their environmental impacts, but also on criteria influencing the implementation of these techniques. From ibis multi-criteria-analysis the most favourable treatment technique to be developed and implemented may be chosen.
AOX Levels in the River Rhine: Fifty Percent of Natural Origin?!
Authors: Hoekstra Eddo J. , de Leer Ed W. B.
Published: May 2018

An AOX transport model is used to distinguish natural and anthropogenic sources of organohalogen compounds in river basins. Application of this model to AOX data of the river Rhine basin in the years 1986 to 1991 shows a constant natural AOX contribution of about 15 µg.l-1 to the total AOX flowing into The Netherlands. The anthropogenic discharge has decreased by 70-95% for the river Rhine basin in this six years resulting in a situation that today 30-70% of the total AOX flowing into The Netherlands at Lobith originates from naturally produced organohalogen compounds.
AEROBIC TREATMENT OF EFFLUENT FROM THE WOOD PANELLING INDUSTRY
Authors: Li X. Z. , Boyden B. H. , Sun D.
Published: May 2018

Intermittent decanted aerated reactors (IDARs) were used for biological treatment of eucalypt wood panel industrial wastewater. IDARs in extended aeration mode were effective for removal of 50-80 % of total COD and 90-96 % of total BOD5. Kinetic studies revealed a sludge yield of 0.45 (g biomass/g COD removed) and more effective treatment using a sludge age of greater than 20 days and F/M ratios less than 0.2. Colour increases of greater than 200 % resulted from biological treatment, but the average molecular weight of chromophoric species were reduced.
OZONATION – AN IMPORTANT TECHNIQUE TO COMPLY WITH NEW GERMAN LAWS FOR TEXTILE WASTEWATER TREATMENT
Authors: Gähr Frank , Hermanutz Frank , Oppermann Wilhelm
Published: May 2018

The German textile industry is challenged by the introduction of new governmental regulations in the field of textile wastewater treatment This causes a large increase of water costs in comparison with other European countries. Many economic experts even see Germany seriously endangered as a place of textile production, however there are also opportunities with the development of high performance cleaning technologies as a result of these governmental measures. In particular the required separate treatment of selected wastewaters of different fmishing processes bas some good perspectives since specialized wastewater techniques can be applied efficiently. For instance the separation of unfixed reactive dyes is the ideal basis for ozone oxidation. Ozonation being a sludge-free method to decompose dyestuff, fmishing products, and other organic materials is of increasing importance because of the limited space for disposal of sludges. Other advantages of ozone treatment are the improvement of biodegradability, reduction of aromatic and halogenated organic compounds and also a significant decrease of chemical oxygen demand. The ozonation of textile wastewaters in combination with inexpensive biological processes has the potential to play a major role in the future. Partial replacement of coagulation/precipitation can be expected.
Gravel-Pit Lakes Connected with the River Rhine as a Reserve for High Productivity of Plankton and Young Fish
Authors: Neumann D. , Seidenberg-Busse Chr , Petermeier A. , Staas St , Molls F. , Rutschke J.
Published: May 2018

During the last two decades an increasing number of sand and gravel-pits were established in the original flood plain of the River Rhine. Some of these are connected with the stream by a small canal for the transport of the spoil. Some of these dredged lakes have been studied during recent years at the ecological field station of the University of Köln, with regard to seasonal phytoplankton succession, productivity of copepods and cladocerans, occurrence of macrozoobenthos, and both spawning and recruitment of fish populations. These eutrophic lakes represent a valuable substitute biotope for lost lentic waters of the former flood plain. They offer via the canal connection an advantageous habitat to resident fish species of the Lower Rhine, (1) for reproduction and growth of the 0+-generation, and (2) for shelter during flood events. Recommendations for reclamation plans of such lakes are required.
Fish Abundance and Fish Migration in Gravel-Pit Lakes Connected with the River Rhine
Authors: Molls F. , Neumann D.
Published: May 2018

The total fish abundances of two gravel-pit lakes connected with the River Rhine have been observed by a hydro-acoustic method (echo-sounder: Lowrance X16) for about one year. Diel (24-hour-period) as well as seasonal changes in fish distribution and aggregation behaviour have been established. Concerning the assessment of the fish stocks, these changes in fish behaviour have to be considered. Some clear fluctuations of fish numbers, which coincide with flood events of the river are interpreted as indications of fish migration from the river into the lentic water.
Design Criteria and Practice for Constructed Wetlands
Authors: Crites Ronald W.
Published: May 2018

Constructed wetlands are categorized into two types: free water surface flow or subsurface flow. Design criteria are set out for both types and operational details are given for both municipal wastewater treatment plants.
ODOUR EMISSIONS OF WASTEWATER TREATMENT PLANTS – RECENT GERMAN EXPERIENCES
Authors: Frechen Franz-Bernd
Published: May 2018

Odorous emissions from wastewater treatment plants can cause serious annoyance in the vicinity. According to recently issued federal regulations. when designing new WWTPs or expanding existing ones, expert opinion has to be taken into account. Also problems arise with existing plants that have to be solved. It is necessary to understand the basics of odour and odour-related annoyance as well as the use of appropriate measurement technique in order to describe the problem correctly. Then problems can be detected and solved properly by using appropriate measures. There are many measures to be taken against odour emissions, depending upon the type of plant, process design, way of operation and others. If, however, these measures are not able to guarantee a sufficient emission level, then collection of waste air and subsequent deodorization must be chosen to solve the problem. Different technologies for deodorization are known today, and available data concerning these techniques at Germany's wastewater treatment planlts are shown later. Among the possible technologies developed in recent years biological methods are gaining more and more attention. as they are efficient. cost-effective and environment-friendly.
Gravel Media Filtration as a Constructed Wetland Component for the Reduction of Suspended Solids from Maturation Pond Effluent
Authors: Sapkota D. P. , Bavor H. J.
Published: May 2018

Experiments were carried out in a horizontal gravel media filter (GMF) with media size ranging from 5-40 mm. Such gravel-based, sub-surface flow units have been used in both planted and unplanted formats in a range of constructed wetland systems. This GMF was subjected to various hydraulic application rates ranging from 1 m3/(m2.d) to 36 m3/(m2.d) over a twc-year period. The range of suspended solids (SS) concentration was 2-36 mg/l and that of turbidity (NTU) was 3-44 during the experimental period. The average removal of suspended solids varied from 30-86%. It was observed that SS was reduced by a maximum of 86% at an application rate of 13m3/(m2.d), within the above noted SS range. An additional laboratory scale experiment was carried out with artificially grown algae in a vertical perspex tube of 190 mm inner diameter (I.D.) in upward flow condition. Results from the laboratory scale and pilot scale experiments are presented and discussed. The study demonstrates that a constructed wetland format with a subsurface flow and horizontal gravel media component could be used as an alternative method for reducing suspended solids from maturation pond effluent
MODELLING OF OXYGEN TRANSFER IN DEEP DIFFUSED-AERATION TANKS AND COMPARISON WITH FULL-SCALE PLANT DATA
Authors: Pöpel H. Johannes , Wagner Martin
Published: May 2018

In upgrading or extending activated sludge treatment plants, there is a trend to apply deeper (8 to 12 m) aeration tanks than until now (4 to 6 m). Such tanks consume less area, need less air and produce less off-gas. Sometimes, a greater aeration efficiency (kg O2/kWh) and hence energy savings are expected. On the other hand, there is not sufficient experience to safely design air diffusion systems for deep tanks.

Based on the physics of gas transfer, a model for simulation of oxygen transfer in deep tanks is developed. The simulated data allow quantitative conclusions with respect to the potential advantages stated above. According to the model, a reduction of the required air flow is considerable up to depth of some 15 m but energy savings cannot be expected. The model is verified using 98 full-scale plant measurements at various tank depths. The comparison shows a good agreement between simulated and actual data. Further investigations are required to support the model at greater depth and to enable a safe design procedure for air diffusion systems in deep tanks.
Constructed “Source” Wetland Concepts Applied to Urban Landscapes
Authors: Hopkins Ben , Argue John R.
Published: May 2018

A class of wetland is introduced which employs engineering practices and installations to collect, store, dispose of, retrieve and use stormwater, at source, in the urban landscape. Two Adelaide (South Australia) examples of “source wetlands” are described. At New Brompton Estate, roof runoff from (eventually) a cluster of 15 residences is diverted to a 106 m gravel-filled trench in a central reserve. The collected water sustains a row of deciduous trees bordering the reserve and provides frequent (winter) charges, via a bore, to a Quaternary aquifer at depth 30 m.

At Northfield a swale/trench system which handles all storm runoff from a residential street (including domestic contribution) will be trialled. Runoff seeping to the trench from the swale will be of high quality and will provide charges of water to a 5 m Quaternary aquifer. Some runoff of good quality will pass from the catchment in large storm events. In both cases, New Brompton and Northfield, water retrieved from the Quaternary aquifers in summer will be used for open space irrigation. Constructed source wetlands offer a valuable new option in urban stormwater quantity/quality management.
NDBEPR PROCESS OPTIMIZATION IN SBRs: REDUCTION OF EXTERNAL CARBON-SOURCE AND OXYGEN SUPPLY
Authors: Demuynck Carl , Vanrolleghem Peter , Mingneau Carine , Liessens Jan , Verstraete Willy
Published: May 2018

In SBR plants for nutrient removal it is often necessary to add supplementary rbCOD during the anoxic phase to obtain complete nitrogen removal. In addition to the aeration, this supply of high-quality BOD is a non-negligible part in the operating costs. Because of the complexity of the bighly interconnected biological processes a heuristic approach for process optimization is hardly possible. Therefore the Nitrification Denitrification Biological Excess Phosphorus Removal (NDBEPR) model of Wentzel et al. and a numerical optimization a1goritbm were used to optimize SBR time scheduling, i.e. minimize both effluent concentrations and operating costs. It was found that a sequence of short aerobic/anoxic phases appears to be better than the usual sequence (one aerobic phase followed by one anoxic phase). This result was validated on a 500 I scale SBR. The optimized process saves up to 50% on extra BOD supply and up to 30% on aeration time. Moreover, it was shown that these cost savings were not at the expense of the phosphorus removal efficiency or the nitrification rate. From an additional numerical optimization it was seen that the ideal SBR time scheduling may depend on the loading. Therefore. a control strategy hased on OUR and ORP measurements is proposed.
Natural Wetland Polishing Effluent Discharging to Wooloweyah Lagoon
Authors: Patruno J. , Russell J.
Published: May 2018

A natural wetland discharging to a lagoon has been receiving effluent from a treatment works for 20 years. Nutrient levels in the lagoon and through the wetland were studied as part of an overall investigation into increasing the load on the sewage treatment works. The wetland is removing 94% of phosphorus (P) and 77% of nitrogen (N) from the effluent. Potential exists to augment the treatment works and retain/improve the wetlands ability to polish effluent and continue discharge to the lagoon.
INTERACTION BETWEEN COMPUTER SIMULATIONS AND CONTROL USING ON-LINE NITROGEN MEASUREMENTS
Authors: Thornberg Dines E. , Thomsen Henrik A.
Published: May 2018

Mathematical models are a useful tool to help in the prediction of results of operation changes in activated sludge plants. Some calibration of the models is usually necessary, but there is often a lack of data describing the influent wastewater sufficiently. Combining the modelling with continuous measurements of ammonia and nitrate gives a good basis of data in connection with biological nitrogen removal. In this study, phased oxygen control is introduced in a recirculation plant and on-line ammonia measurements in the aeration tank are used to estimate the variations in influent load. After the influent is described the calibration of process constants is done using the on-line data. The calibrated model is used to test the effect of varying recirculation and phase lengths. A mobile monitoring station supplied the on-line data of ammonia and nitrate.
The Use of Constructed Wetlands for Treating Industrial Effluent (Textile Dyes)
Authors: Davies T. H. , Cottingham P. D.
Published: May 2018

Constructed wetlands bave the capability to treat industrial wastewater containing a wide range of chemicals, including priority pollutants such as phenols and cresols, by processes such as absorption and bacterial breakdown, chemical oxidation, adsorption onto the bed matrix and sedimentation. A brief overview of this technique is presented along with details of preliminary trials carried out on textile dyeing and processing water.

The trials were conducted in a horizontal flow, gravel bed reed (30m × 5m), located in Melbourne, Australia. The textile dye wastewater was applied at an influent rate of 10 1/min., resulting in a retention time in the reed beds of 3–4 days, results indicated that breakdown of the visible dye occurred mainly in the first one third of the bed.
ON-LINE ESTIMATION OF THE RESPIRATION RATE AND THE OXYGEN TRANSFER RATE AT KUNGSANGEN W ASTEW ATER TREATMENT PLANT IN UPPSALA
Authors: Carlsson B. , Lindberg C.-F. , Hasselblad S. , Xu S.
Published: May 2018

In this paper, a method for on-line estimation of the oxygen transfer rate (KLa) and the respiration rate is successfully evaluated on real data from the municipal sewage plant Kungsängen in Uppsala, Sweden. Possible applications for the estimator include process diagnosis and model based control. The estimator is based on a Kalman filter approach where the oxygen transfer ra.te is modelled with a static, constrained, piecewise linear model and the respiration rate is modelled as a random walk, The paper also presents experience with using an autotuning controller for the control of the dissolved oxygen concentration.
AUTOMATED RESPIRATION INHIBITION KINETICS ANALYSIS (ARIKA) WITH A RESPIROGRAPHIC BIOSENSOR
Authors: Kong Z. , Vanrolleghem P. , Verstraete W.
Published: May 2018

Respirometric techniques have been used for the on-line and off-line assessment of toxic effects of substances. A model-hased method to describe toxic effects on the biodegradation kinetics based on a respirometric technique has been developed by Volskay and Grady, However. this so-called RIKA-procedure (Respiration Inhibition Kinetics Analysis) is rather laborious and time consuming.

In this paper, a fast and automated method will be presented which allows us to perform the RIKA test within 3 hours by using an activated sludge based respirographic biosensor (RODTOX, Rapid Oxygen Demand and TOXicity tester). These results could be achieved because a respirogram obtained from this biosensor gives rise to a degradation rate versus substrate concentration data-set that covers the whole substrate concentration range required by the RIKA test. Starting from an initial concentration of 20 mg COD/1 in the ARIKA procedure, the biogenic substrate is degraded completely in less than 30 minutes. Using a model-based approach coupled to a non-linear parameter estimation algorithm. the kinetic parameters of the biodegradation process can be obtained. Performing batch tests with different toxicant concentrations (usually 4) then allows us to deduce the dependence of the kinetic parameters on the toxicant concentrations. Since the method is automated, the procedure is fast and labour-saving.
Marrakesh Wastewater Purification Experiment Using Vascular Aquatic Plants Eichhornia crassipes and Lemna gibba
Authors: Mandi L.
Published: May 2018

This work tests experimentally the capacities of water hyacinth (Eichhornia crassipes) and duckweed (Lemna gibba) to purify wastewater in Marrakesh.1)Eichhornia crassipes was grown in continuous culture with a constant flow rate of 10 l.min.−1 Organic, bacterial and parasitical loads were examined to determine the efficiency of the system. The results show that water hyacinth is well suited to the climatic conditions of Marrakesh. Domestic sewage purification by water hyacinth leads to satisfactory efficiency during the summer with an 87% reduction in chemical oxygen demand (COD) and 95% reduction in total suspended solids (TSS). Bacterial load reduction expressed by control of faecal contamination bacteria achieved 2 log units for a short theoretical retention time (7 days). Moreover, this process reduced parasitic helminth eggs to undetectable levels.2)Lemna gibba was grown in continuous culture with a constant flow rate of 3 1. day−1. Only organic loads were examined. Three categories of influents were tested to determine the system efficiency. The results obtained show that Lemna gibba has the capacity to purify a low organic load (COD:305–530 mg.l−1). The average influent COD was reduced by 82%. During the summer period the average influent COD and TSS has been reduced by 61% and 82% respectively.
MONITORING OF THE MAXIMUM RESPIRATION RATE
Authors: Spanjers Henri , Temmink Hardy , Klapwijk Abraham
Published: May 2018

The maximum respiration rate is useful for estimating the active biomass concentration and detecting toxic effects on the activated sludge. In this paper we describe a method for continuously measuring the maximum respiration rate of sludge in an activated sludge plant. The method is based on the continuous addition of wastewater into sludge flowing through a respiration chamber. The measurement is verified, at regular intervals, by stepwise increasing the wastewater sample flow to the respiration chamber whilst recording the respiration rate.

The results of a measuring period at a pilot plant are presented. The influent flow to this plant was varied according to a square wave pattern with a period of 12 hours. The maximum respiration rate was monitored and during each period the measurement was verified.

The verifications show that the wastewater sample flow applied was sufficiently high to attain saturation with respect to the substrate concentration. It was concluded that in both periods the maximum respiration rate was really measured. The experiment was repeated several times during another measuring period. It was found that saturation was not always achieved at the wastewater sample flow applied and thus the maximum respiration rate was not measured in these cases. Explanations are given and suggestions for improvement of the measurement are provided.
Bureaucracy and effectiveness in water pollution control
Authors: Holmes Paul R.
Published: May 2018

Water pollution has been a steadily growing challenge to many rapidly industrializing regions of the Pacific Rim. Governments have typically responded in the same way as those of the world's older developed countries, by piecemeal development of sewerage, leading ultimately to huge sewage disposal infrastructures in the public sector where resources have not been too scarce. The bureaucratic management of these services is not always perceived as effective by those whom it exists to serve. The paper examines the phenomenon of public bureaucracy, and critically reviews the benefits of the leading alternative, private sector involvement in the management of water pollution control. Using the history of institution building in Hong Kong as an example, it traces the development of an organizational style in response to water pollution issues. It suggests awareness of organizational characteristics and behaviour can help to improve service, but concludes that research into organizational effectiveness in pollution control is needed.
An East-West perspective on riverine loads of nutrients in the Vistula and Rhine basins
Authors: Tonderski A. , Grimvall A. , Sundblad K. , Stålnacke P.
Published: May 2018

Measures proposed to reduce the load of nutrients to the Baltic Sea focus on the removal of point emissions through introduction of environmental technology in the eastern and southern parts of the drainage basin. This article draws attention to the mixed success of Western European river basin management by comparing water quality trends and turnover of nutrients in the Vistula and Rhine basins. Removal of point sources in the Rhine basin has caused a marked drop in the concentrations of phosphorus and ammonium nitrogen, whereas the long-term upward trend in the concentration of nitrate was broken only recently. As compared to the Vistula river, the Rhine is still in some respects more polluted. Expressed as area-specific export, the riverine load of nitrate from the Vistula basin is only about one sixth of that of the Rhine basin. The area-specific export of phosphorus is comparatively higher in the Vistula, but still only half of that of the Rhine. In addition to the lower input of nutrients in the Eastern European agriculture, the much lower runoff in the Vistula basin is an important explanation to the observed differences. Furthermore, in-stream processes, such as sedimentation of phosphorus, play an important role.
Source reduction and recycling for pollution prevention in chemical plants
Authors: Ansari M. A.
Published: May 2018

This paper reviews and describes the methods currently used to reduce water pollution from chemical plants using waste minimization at the source and recycling when necessary.

Techniques, including process changes, equipment modifications, changes in operational set points, improved process control and automation are discussed.

The discussion focuses on AlliedSignal's successful experience using techniques of total quality management in reducing pollution at the source and through recycling. Examples are presented as to how management's commitment to waste minimization concepts, operator training and involvement, and team work helped in reducing significant plant's effluent emissions.
Nitrification inhibition – a method for the estimation of actual maximum autotrophic growth rates in activated sludge systems
Authors: Nowak O. , Schweighofer P. , Svardal K.
Published: May 2018

Since more or less severe nitrification inhibition was observed in several pilot and full-scale activated sludge plants, a means to quantify the extent of inhibition under operational conditions has been sought. Thus a method for the estimation of the actual maximum autotrophic growth rate μ^A,T was developed. This parameter helps to detect low nitrification capacity, before the effluent ammonia concentration increases. Two case studies show that nitrifying activated sludge plants may become acclimatized to inhibitory compounds but have to be protected from peak loads of both nitrogen and inhibitory compounds.
Nitric and nitrous oxides from denitrifying activated sludge at low oxygen concentration
Authors: von Schulthess R. , Wild D. , Gujer W.
Published: May 2018

To determine the net-production of the denitrification intermediates nitric oxide (NO) and nitrous oxide (N2O), two batch experiments with different nitrite concentrations have been performed (A: 3.5 g NO2−-Nm−3, B: 12 g NO2−-Nm−3). In these experiments the concentration of oxygen in the reactor has been varied from 4 g O2m−3 to 0 g O2m−3. As NO and N2O might be produced by nitrifiers as well, the sludge used was unable to nitrify due to a low sludge age. High nitrite as well as aerobic conditions favor the production of N2O but not the production of NO. Furthermore, NO was accumulated at very low concentration and the highest emission was under completely anoxic conditions. A mathematical model has been formulated describing the reduction of nitrate, nitrite, and nitrous oxide. Noncompetitive inhibition of these processes by oxygen and nitrite has been included in the kinetics. The estimated parameters indicate that nitrite serves mainly as a denitrification intermediate rather than as an inhibitor. The net-production of N2O at low oxygen concentrations can be explained by different oxygen inhibition of the three reduction steps. The fast reduction of N2O is most inhibited by oxygen. As a consequence, the reduction of N2O is a slower process under low oxygen pressure than the reduction of nitrate and nitrite.
Production of nitrous oxide gas during nitrification of wastewater
Authors: Zheng H. , Hanaki K. , Matsuo T.
Published: May 2018

Laboratory-scale experiments were conducted to examine nitrous oxide (N2O) production during the nitrification process. Substrate containing 400 mgN l−1 of NH4HCO3 as a nitrogen source was continuously fed into a 10 or 3 liter completely mixed reactor with varied dissolved oxygen (DO) and SRT. The DO of the continuous systems were fixed at 0.1, 0.2, 0.5, 1.7 and 6.8 mg l−1. The SRT were controlled at 3, 5, 10 and 20 days. Total amount of N2O production reached higher than 36 mgN l−1 in some conditions, and up to 16% of nitrified nitrogen was converted into N2O. N2O production was observed in all tested runs. Lower DO and shorter SRT resulted in higher N2O production. Incomplete nitrification was found at DO lower than 0.5 mg l−1 and an SRT shorter than 5 days. The highest concentration and conversion rate of N2O production was obtained at DO of 0.2 mg l−1 or when SRT was 3 days. The results suggest that N2O production is significant during nitrification process. The accumulation of NO2 may contribute to the high amount of N2O production.
Drinking water denitrification in a membrane bioreactor
Authors: Delanghe B. , Nakamura F. , Myoga H. , Magara Y. , Guibal E.
Published: May 2018

Drinking water denitrification was studied on a membrane bioreactor pilot plant. The nitrate removal yields remained constant at 99 %. The specific denitrification activities averaged 0.16 kg N-NO3.kg−1MLSS.d−1 at 20°C and pH 8. The permeation flux was about 0.5 m3.m−2.d−1 throughout the study and did not vary with an increase in the suspended solids concentration. The dependence of the process efficiency on temperature and pH was put into equation. The specific denitrification activity decreased by a factor 1.9 with a temperature decrease of 10°C. The optimal pH was found to be 8 – 8.5. The ethanol consumption was 1.4 g C.g−1N-NO3. The membrane bioreactor technique seems to be a promising answer for the nitrate problem of drinking waters.
Upgrading of existing trickling filter plants for denitrification
Authors: Mehlhart G. F.
Published: May 2018

New European Union Guidelines ask for nutrient removal. For trickling filters it was necessary to develop new design criteria for denitrification. The paper presents the results of half-scaled and full-scaled experiments with activated sludge systems, fixed bed reactors prepositioned and postpositioned. Further results out of literature are added. Possible design criteria are shown. It is emphasized that some trickling filters show simultanous nitrogen elimination of up to 80 %.
Effect of the anaerobic solids retention time on enhanced biological phosphorus removal
Authors: Matsuo Yoshitaka
Published: May 2018

Three continuous flow enhanced biological phosphorus removal (EBPR) systems were operated to investigate the effect of the anaerobic SRT on the phosphate removal. The P removal in the system with a short anaerobic SRT declined due to growth of non phosphate accumulating microbes which competed in anaerobic substrate uptake against polyphosphate accumulating bacteria. The phosphorus removal, however, was improved by extending the anaerobic SRT. Restoration and stabilization of P removal by the long anaerobic SRT were confirmed in two other systems.
The effect of fermentation products on enhanced biological phosphorus removal, polyphosphate storage, and microbial population dynamics
Authors: Randall A. A. , Benefield L. D. , Hill W. E.
Published: May 2018

Using anaerobic/aerobic sequencing batch reactors (SBRs) it was found that pre-fermentation of influent glucose resulted in a microbial population capable of enhanced biological phosphorus removal (EBPR). Batch tests indicated the C1-C5 carboxylic acids, except propionate, typically improved phosphorus removal. Branched molecules were superior to their linear isomers. The C1-C5 alcohols did not affect removal. Glucose, propionate, and an amino-acid rich substrate were detrimental. Using NMR spectroscopy it was observed that intracellular forms and locations of phosphorus did not change regardless of the substrate received. Polyphosphate (polyP) was present throughout the cells at the end of aerobiosis. It then degraded to inorganic phosphate via a zero-order enzymatic reaction concentrated at the cell membrane. An anaerobic/aerobic SBR receiving starch, rather than glucose fermentation products, showed only marginal EBPR and did not respond to carboxylic acids or other substrates in batch tests. Pseudomonas and Bacillus were numerous in the glucose system but were not isolated from the starch system. Aeromonas were dominant in the starch system. Although the glucose system showed better phosphorus removal than the starch system, it also showed greater variability. Phosphorus removal varied in a chaotic, but bounded, manner, probably due to population dynamics.
Roles of solid components on the sorption of trichloroethylene (TCE) onto natural solids from the vapor phase
Authors: Shimizu Yoshihisa , Takei Noboru , Terashima Yutaka
Published: May 2018

The sorption of trichloroethylene (TCE) from the vapor phase was investigated by batch sorption experiments. The role of solid components in natural solids was evaluated with a model solid phase system, consisting of six individual model solid phases (humic acid, montmorillonite, kaolinite, amorphous aluminosilicate gel, amorphous iron oxides, and amorphous manganese oxides) and two binary model solid phases (montmorillonite with amorphous aluminosilicate gel and montmorillonite with amorphous iron oxides). Experimental results indicated that swelling clays, which are represented by the montmorillonite, are a dominant sorbent in natural solids. The amorphous metal oxides of aluminosilicate and iron effectively block the sorption site of the swelling clay. The water associated with model solid phases (i.e., moisture content) reduces the sorption. The reduction rate, normalized with respect to the sorption onto each model solid phase of zero moisture content, is greater for the inorganic model solid phases than for humic acid. The sorption experiments with natural solids observed a greater reduction rate for the natural solid of low organic carbon content. Therefore, it was hypothesized that moisture content of the swelling clays in a natural solid is smaller than that of the organic matter.
A rule-based fuzzy-set approach to risk analysis of nitrate-contaminated groundwater
Authors: Dahab M. F. , Lee Y. W. , Bogardi Istvan
Published: May 2018

Groundwater nitrate contamination has been a subject of concern because nitrate salts can induce infant methemoglobinemia and possibly human gastric cancer. In general, nitrates in drinking water may not be the main component of total nitrate intake, but nitrate-contaminated drinking water can make an important contribution to total nitrate intake. In this paper, a nitrate risk-assessment methodology is developed to assist decision makers in estimating human health risks corresponding to a particular nitrate dose to humans and in determining whether regulatory action must be taken to reduce the health risks. The case of a community with a nitrate water quality problem is used to illustrate the nitrate risk assessment methodology. The uncertainty associated with assessing health risks of nitrate and its impact on results are represented by using a fuzzy-set approach and incorporated into the nitrate risk assessment methodology. Therefore, a nitrate risk assessment can be made that is more realistic and appropriate than the one made without taking uncertainty into account.
Sequencing Batch Reactor: A Tool for Wastewater Characterization for the IAWPRC Model
Authors: Torrijos M. , Cerro R.-M. , Capdeville B. , Zeghal S. , Payraudeau M. , Lesouef A.
Published: May 2018

The use of a sequencing batch reactor (SBR) for wastewater characterization requires the interpretation of the total respirometric response obtained in batch culture with primary settled water. In a first step and with the aim of understanding this total response, the water was divided by filtration into three fractions, the respirometric responses of which were analysed separately. This paper presents the results of the study of the biodegradability and of the specific respirometric responses of the soluble and colloidal fractions of an urban wastewater during batch cultures with a high concentration in pre-acclimatized activated sludges (low So/Xo ratio). For the water studied, the soluble fraction could be divided in two fractions of equal size : a readily biodegradable fraction and an inert fraction. Ultrafiltration of the soluble fraction during the cultures allowed stating the specific evolution of the soluble organic compounds according to their Molecular Weight. For the colloidal fraction, the observed behaviour was totaly different. Indeed, the colloidal organic matter disappeared very quickly from the liquid phase according to a physical phenomenon but without any important biological oxidation during the first 5 hours of a batch culture. Latest work concerns the study of the particulate organic matter and the interpretation of the total respirometric response knowing the specific response of the three fractions.
A Comparative Study of Biopolymers from a Conventional and an Advanced Activated Sludge Treatment Plant
Authors: Frølund B. , Keiding K. , Nielsen P. H.
Published: May 2018

Biopolymer characteristics from a traditional and an advanced activated sludge treatment plant performing biological N and P removal were compared. The biopolymers were extracted using an ion exchange resin (DOWEX in Na-form). Differences between chemical compositions of the total sludges were observed by measuring protein, polysaccharide and uronic acids whereas differences in the same compounds were not found in the extracted biopolymers. High Pressure Size Exclusion Chromatography was performed on the two biopolymer matrixes and differences were found in the biopolymer matrixes. Biopolymers from the advanced treatment plant contained two fractions of large and hydrophobic compounds which contributed to a major fraction of the chromatogram area. These peaks could only to a minor extent be found in the extracted biopolymers from the traditional treatment plant.
Estimation of Biomass Concentration and Population Dynamics in a Captor® Activated Sludge System
Authors: Reddy M. P. , Pagilla K. R. , Senthilnathan P. R. , Johnson H. W. , Golla P. S.
Published: May 2018

A technique was developed to measure the equivalent MLSS in the fixed film Captor® media-activated sludge process. The technique accounts for the wear in the media as well as unequal wear in different media. The microbial population variations encountered during three years of full scale operation of the Captor® process, at the Moundsville WWTP were recorded. It has been found that fixed film media seem to support predominantly rotifers, followed by free swimming ciliates, and single stalk ciliates. In contrast, the suspended growth activated sludge population contained lower level organisms, mostly free swimming ciliates, followed by stalk ciliates, flagellates, and a few rotifers.
Settling Characteristics of Activated Sludge in Danish Treatment Plants with Biological Nutrient Removal
Authors: Holm Kristensen Gert , Jørgensen Per Elberg , Nielsen Per Halkjær
Published: May 2018

In 1989-91, a study was performed to investigate the settling characteristics of activated sludge in Danish treatment plants with biological nutrient removal. The study included three screening series on 38 treatment plants. Furthermore, the study included investigations during one year on seasonal variations in sludge settling characteristics at three treatment plants. The screening investigations were performed in November 1989 and May and September, 1990. Results showed that in the May-screening, 35-45% of the plants had a filament index of 2-2.5 or above, corresponding to a sludge volume index above 150 ml/g. When comparing data for diluted and non-diluted sludge volume indices, a SVI value of 150 ml/g seemed parallel to a DSVI of 110 ml/g. In the November- and September-screenings, some 30% of the plants had activated sludge showing a filament index in or above the critical area. Dominating filamentous microorganisms were found to be (in decreasing order): Microthrix parvicella, Type 0041, Type 021N, Type 0092, Type 0914, and Type 1851. A distinct variation over the year in sludge settling characteristics was found for the three plants. Sludge settling characteristics improved during summer, and deteriorated during winter. For activated sludge with a high content of filamentous microorganisms, the best parameter to follow the variations in sludge settling properties was the filament number. If the activated sludge concentration, the MLSS, varied significantly, the specific filament number was to be applied.
Biological Foams: The Cause-Effect Relationship, Test Results and Combat Strategy
Authors: Duchene Ph.
Published: May 2018

This paper presents the results obtained by “G.I.S. MOUSSES”, which comprises the CEMAGREF and the six main private companies operating wastewater treatment plants (WWTP) throughout FRANCE.

Over 75% of French activated sludge (AS) WWTP, 20% are reported to be affected by foaming. 60% of theseare linked with Microthrix and only 14 % with Nocardioforms. Few factors conducive to foaming were statistically proved. Experiments run on more than 40 AS WWTP helped us to identify cause-effect relationships and useful methods to reduce foaming, varying with the type of dominant hydrophobic filamentous microorganisms. The finer points related to design and operation are identified in order to be effective against foaming.

Depending on the type and degree of urgency of each case, different combat strategies are proposed.
Neutralisation of Acid Water in the Chemical Industry with Limestone
Authors: du Plessis P. , Maree J. P.
Published: May 2018

The replacement of lime with limestone for the neutralisation of acid water was investigated through batch and semi-continuous studies. A fluidised-bed reactor with multiple stages of increasing diameters is preferred for the limestone neutralisation process as it allows fluidisation of the bigger particles but also prevents washout of the smaller particles in the case where ungraded particle size limestone is used. It was determined that the rate of neutralisation is influenced by the particle size of limestone and the type of metal in solution. Sulphate is removed as gypsum to the level where the water is saturated with calcium sulphate, while CO2 is produced as a by-product.
Profitability Increase of Alcohol Distilleries by the Rational Use of Byproducts
Authors: van Haandel Adrianus C. , Cavalcanti Catunda Paula Frassinetti
Published: May 2018

Industrial alcohol production in Brazil is based on fermentation of sugar cane juice. After centrifugation and distillation, azeotropic alcohol is obtained along with four side streams: (1) bagasse, the solid part of the cane plant, (2) yeast, grown during the fermentation, (3) carbon dioxide released during the fermentation and (4) waste water called vinasse composed of the bottom fraction of the distillation and wash waters. The profitability of alcohol distilleries can be improved by a more rational use of the side stream products. The solid products have a diversified application potential. By applying anaerobic digestion to vinasse, methane can be produced at a proportion of 100 kgCH4 per m3 of produced alcohol. Full scale application has shown anaerobic digestion to be technically and economically feasible and the digested waste water can be used for irrigation, whereas the produced solids can be applied as soil conditioners.

An alternative for improved energy production is to abandon alcohol fermentation and apply anaerobic digestion directly to the vegetal energy source. In that case the useful energy production is much higher and can be obtained using much simpler equipment. More importantly, the source for energy production would no longer be restricted to cane: Other crops, notably those produced in the drier hinterland of North East Brazil (cassava, sweet potatoes), could also be used for this purpose.
Planning the best strategy for sludge treatment and disposal operations
Authors: Davis Robert D.
Published: May 2018

Sludge treatment and disposal operations on a local or regional basis need careful planning to ensure that the strategy undertaken is environmentally acceptable, reliable and cost-effective. A database of information is needed for the area concerned which may include up to 100 wastewater treatment plants of varying size. Sludge quantities and quality have to be assessed now and into the future. Disposal options for sludge have to be analysed by an environmental assessment approach which studies the accessibility of all outlets, environmental legislation and attitudes of collaborating agencies and the public at large. Other wastes which may compete with sludge for disposal outlets must be considered. Outlets which involve recycling and beneficial use of sludge are advantageous but may not be practical. Sludge treatment must be evaluated in relation to the disposal options available. Sludge treatment centres, treating sludge from several surrounding wastewater plants, may be required especially if thermal drying or incineration are likely options. Economic evaluation has to consider capital and operating costs of sludge treatment and transport and other costs associated with disposal. The paper discusses how to evaluate all the information and options and find a suitable sludge treatment and disposal strategy.
Mechanical freezing of alum sludge
Authors: Martel C. James
Published: May 2018

This paper presents a new mechanical freezing concept for freezing alum or other hydroxide sludges as a conditioning step for dewatering. The basic concept is to freeze a thin layer of sludge on a continuously moving fabric belt. Sludge is attached to the belt by a vacuum drum belt filter which also removes one-half of the water and thus reduces the amount of sludge to be frozen. Filter leaf tests were conducted to determine the operational parameters and approximate production rates of this concept. These tests show that freezing alum sludge in thin layers will separate out the water as ice crystals and transform the solids into the same type of granular material produced in natural freezing beds. The average production rate of frozen sludge was 6.5 kg/hr.m2 at −20°C. The belt area needed for a 10,000-m3/day plant was estimated to be 48 m2. This concept has been patented by the U.S. Patent Office.
Use of constructed wetlands in water pollution control: historical development, present status, and future perspectives
Authors: Brix Hans
Published: May 2018

During the last two decades the multiple functions and values of wetlands have been recognized not only by the scientists and managers working with wetlands, but also by the public. The ability of wetlands to transform and store organic matter has been exploited in constructed wetlands. This paper summarizes the state-of-the-art of the uses of constructed wetlands in water pollution control by reviewing the basics of the technology, the historical development, and the performance expectations with focus on the use of free water surface and subsurface flow constructed wetlands for municipal wastewater treatment. Performance data from a total of 104 subsurface flow systems and 70 free water surface flow systems are reviewed. The present state of knowledge is sufficient to apply constructed wetlands as a tool for improving water quality. The potential applications range from secondary treatment of municipal and various types of industrial wastewaters to polishing of tertiary treated waters and diffuse pollution. In many situations constructed wetlands is the only appropriate technology available. The treatment capacity of subsurface flow systems can be improved by selecting vertical flow systems with intermittent loading, by proper media selection, and by recycling of the wastewater. Further research is needed to help define and optimize engineering design criteria and the long-term performance capabilities and operational problems.
A Centralized Hazardous Waste Treatment Plant: The Facilities of the Zvsmm at Schwabach as an Example
Authors: Amsoneit Norbert
Published: May 2018

As a rule, hazardous waste needs a pre-treatment, either a thermal or a chemical-physical one, before it can be disposed of at a landfill. The concentration of different kinds of treatment facilities at a Centralized Hazardous Waste Treatment Plant is advantageous. The facility of the ZVSMM at Schwabach is presented as an outstanding example of this kind of Treatment Centre. The infrastructure, the chemical-physical plant with separate lines for the treatment of organic and inorganic waste and the hazardous waste incinerator are described. Their functions are discussed in detail. Emphasis is laid on handling the residues produced by the different treatment processes and the final disposal.