bluuebunny/crossref_metadata_2025 huggingface dataset:
Full Scale Investigations on Enhanced Biological Phosphorus Removal – P-Release in the Anaerobic Reactor
Authors: Wedi D. , Wilderer P. A.
Published: May 2018

Most of the fundamental processes responsible for enhanced biological phosphorus removal (EBPR) were obtained through laboratory tests under defined conditions with pure or enriched cultures. Acinetobacter sp. was identified as the most important group of bacteria responsible for bio-P removal. Full scale data showed, however, that laboratory results do not match full scale results well enough. There is a lack of data on the effects of sub-optimal process conditions such as inadequate availability of volatile fatty acids (VFA), high nitrate recycle, storm water inflow or low temperatures. In this paper the results of full scale experiments on P-release are presented and compared with theoretical values. Measurements at a full scale Phoredox-system showed a surprisingly low P-release in the anaerobic reactor. Only 4 to 10% of the phosphorus in the activated sludge was released in the bulk liquid. With laboratory batch-tests, a maximum of 20% of the P in the sludge could be released. It is assumed that under the prevailing process conditions either the fraction of Acinetobacter sp. was very small, or bacteria other than Acinetobacter sp. were responsible for the P-removal, or most of the phosphorus was bound chemically but mediated by biological processes.
Investigation of a Bacteria-Enzyme Additive to Prevent Foaming in Activated Sludge Plants
Authors: Franz A. , Matsché N.
Published: May 2018

Operating and performance problems arise when fats and oils are a major fraction of the organic content of the waste water. These problems are frequently associated with the presence of the microorganisms Nocardia spp. and Microthrix parvicella which can cause foaming of activated sludge plants. Bacteria and enzyme additives (B-E-additives) are produced by some companies who claim to prevent the growth of nocardioform actinomycetes by addition of these B-E-additives to the mixed liquor. In order to investigate these claims a research program for the control of sludge foaming was started using a commercial B-E-additive combatting these operational problems. The B-E-additive was investigated in batch experiments in laboratory scale (0.25-40 1) using mixed liquors from different plants (domestic and industrial plants). In a second phase the B-E-additive was applied on a large scale over extended periods in two different activated sludge plants. Plant A had a severe foaming problem due to waste water from a pet-food factory. Plant B treated mainly waste water of domestic origin. A continuous addition of the B-E-additive could not avoid a severe scum formation on the aeration tank after lipid loadings from industry. The addition of the B-E-additive caused a shift in the biocenosis from Nocardia spp. to Microthrix parvicella but did not influence the foam production in the plant. The addition of the B-E-additive in a plant with two identical, parallel-run activated sludge tanks where the product was only applied in one half of the plant, whereas the other unit served for control purpose, did not show significant differences. The results obtained during the investigations did not show any significant advantage in effective grease removal, foam control or aeration efficiency.
pH-controlled feed-on-demand for high-rate anaerobic systems
Authors: Pretorius William A.
Published: May 2018

The carbonate and short chain fatty acid (SCFA) buffer subsystems govern the pH and thus the required alkalinity in high-rate anaerobic wastewater treatment systems. By controlling the SCFA concentration through a pH-controlled feed-on-demand system, the required alkalinity is only a function of the partial pressure of carbon dioxide (PCO2), and for non-alkalinity producing substrates, independent of the organic loading rate. This makes the pH-controlled feed-on-demand system a simple and very effective method for minimising the start-up time and improving the reliability of high-rate anaerobic digestion. For maximum sensitivity the controlling pH was measured in a pH region near the bicarbonate equivalence point. This condition was obtained by measuring the pH in a biogas stripped side stream. The concept of pH-controlled feed-on-demand was successfully applied for the start-up and operation of an upflow anaerobic sludge bed (UASB) reactor, using SCFAs as substrate.
The influence of pH on the performance of a two-stage anaerobic treatment system: model prediction and validation
Authors: Romli M. , Keller J. , Lee P. L. , Greenfield P. F.
Published: May 2018

The effect of lowering the pH of the acidification reactor on the overall performance of a two-stage anaerobic wastewater treatment system was determined both experimentally and through simulation of a dynamic structured model. The system operated at low pH was then subjected to a short-term step increase in feed concentration. The measured and the predicted dynamic responses of reactor variables to the shock load were evaluated. The result indicated that lowering the pH setpoint from 6.0 to 5.3 led to a reduction in the external alkali addition by 30% without any significant deterioration in the final effluent quality. The model prediction showed good agreement with the experimental results for most reactor variables. The dynamic response of the system to a concentration shock load indicated a decrease in effluent quality during the disturbance, but the system did recover quickly as soon as the shock load terminated. The comparison between the experimental and the simulation results demonstrated the feasibility of the model to be applied for reactor design and operational evaluation purposes.
Electroosmotically enhanced sludge dewatering: pilot-plant study
Authors: Smollen Maryla , Kafaar Achmad
Published: May 2018

Owing to the inherent inefficiency of dewatering equipment widely used today, the search for improved dewatering techniques has been pursued by the investigation of new innovative ideas. The main thrust of these investigations has been in electroosmotic dewatering which presents a novel approach in South Africa.

The separation of the sludge liquid phase is governed by the intensity of binding forces. There are different physical forms of water in sludge and these different forms play an important role in determining the ease or difficulty of phase separation. It seems that the inefficiency of dewatering applied to gelatinous and fine-particle sludges can be overcome by mechanical dewatering enhanced by electroosmosis. A prototype pilot-plant embodying these principles has been developed for commercial application to dewatering of troublesome sewage sludges.
Source Pollution Control Program at the Camaçari Petrochemical Complex: Overall and Individual Improvements
Authors: Freire P. A. , Neto D. B. , Carvalho D. M.
Published: May 2018

Along with the technical progress experienced by the Camaçari Petochemical Complex in the last few years, new policies, following new worldwide trends, in pollution control and prevention became mandatory.

The knowledge acquired from recent development and research has helped CETREL-Empresa de Proteçao Ambiental S.A. and the State of Bahia EPA (CRA) to develop and implement new programs for the environmental protection of the entire Camaçari Petrochemical Complex area.

Among these strategies the Source Pollution Control Program (SPCP) has been playing a very important role in industrial pollution prevention.

In addition to other measures taken by CETREL to reduce pollutant emissions, the implementation of an incineration unit for organic chlorinated liquid residues has also proven to be a very efficient treatment. It not only avoids problems for CETREL's centralized activated sludge plant, but it also reduces dramatically the emission of volatile chlorinated hydrocarbons into the environment.
Operation results of the sewage sludge melting system and estimation of scale-up method for the reflector type melting furnace
Authors: Hiraoka M. , Hukui T. , Kimura A. , Shimizu K. , Takiguchi H.
Published: May 2018

Sludge melting systems have been recently applied to the treatment of a great deal of sludge generated from sewage treatment plants, and the plant scale has become bigger and bigger in accordance with the social requirements. This paper reports operating data of one of the biggest scale melting plants for sewage sludge equipped with two reflector type melting furnace trains and includes running cost data as well as estimates for scaling up the process.
Phosphorus uptake in Florida marshes
Authors: Kadlec Robert H.
Published: May 2018

Four Florida wetlands have been studied, by various groups, to provide data on hydrology, biota, and water chemistry. A subset of that data is here further analysed to determine the unifying principles of phosphorus removal. The uptake of this nutrient was found to be first order on an areal basis for long term average performance. Flow-through wetlands exhibit strong gradients in the direction of flow. The first order rate equation was used in conjunction with mass balances on water, soils and biota for water and phosphorus, to determine values of the rate constant ranging from 6.4 to 13 m/yr.
A four-year mass balance for a natural wetland system receiving domestic wastewater
Authors: Hosomi M. , Murakami A. , Sudo R.
Published: May 2018

In order to clarify the natural purification potential of a natural wetland having free-flowing water, we performed a four-year study on such a wetland system which had been receiving for 12 years the domestic wastewater discharged from a residential area comprised of 45 households. The wetland's removal rate of organic matter throughout the four years ranged from 80% for COD to 95% for BOD, whereas the corresponding nitrogen removal rate was comparatively lower. Results indicate that NH4-N release from the bottom sediment and repression of nitrification are the main factors responsible for the wetland's low removal rate of nitrogen during winter. The wetland purification performance even in winter was determined as follows (g m−2 d−1): 2.2 BOD, 0.81 COD, 1.1 TOC, 0.10 T-N, and 0.023 T-P.
Joint Treatment of Industrial Effluent: Case Study of Limassol Industrial Estate
Authors: Hadjivassilis I. , Tebai L. , Nicolaou M.
Published: May 2018

The treatment plant has been designed and installed for the treatment of wastewater discharged from various industries at Limassol Industrial Estate. The total daily flow and biological load after the last extension of the plant are 1000-1200m3/d and 220-264kg BOD5/d respectively. Chemical treatment followed by biological treatment is applied. The main steps of the treatment process are as follows: equalization, flotation, coagulation-flocculation, settlement of chemical sludge, pH-adjustment, nutrient addition, aeration of activated sludge, settlement of biological sludge, chlorination and sludge stabilization. The efficiency of the plant with respect to BOD5 and COD removal is over 90%. The quality of the treated effluent is BOD5 < 15mg/l and COD < 40mg/l. The concentration of trace elements are below the recommended limits for reclaimed water used for irrigation purposes.
Combined Treatment of Olive Mill Effluent and Municipal Wastewater in a Small Tourist Community
Authors: Croce F. , Poulsom S. , Hendricks D. W.
Published: May 2018

A technologically simple, cost-effective solution was provided to upgrade an existing municipal wastewater treatment plant in the tourist village of Casteldaccia, Italy, to support the seasonal loading of wastes from the olive oil industry. During the summer months, when the population of the village is about 15,000, the traditional activated sludge treatment plant will handle 100% of the municipal wastes.

During the eight months winter period, the municipal BOD loading is lower by a factor of two. During this time, the excess treatment capacity of the plant will accommodate the effluent from the local olive mills. The storage of this waste water, in a series of aeration tanks, permits its release as a steady flow to the activated sludge plant.
Pretreatment Requirements for Leather Tanning Industry Wastewaters
Authors: Tünay Olcay , Orhon Derin , Kabdasli Isik
Published: May 2018

In this study, experiments are conducted on leather tanning industry wastewaters to evaluate efficiencies of alternative schemes of physical-chemical treatment with regard to pretreatment standards. Carbonation and protein removal are employed in addition to sulfide oxidation, chromium precipitation, plain sedimentation and chemical precipitation. Two samples are used from two different tanneries processing cattlehide. Results indicate that carbonation and protein removal have little effect on COD. TKN removal in protein precipitation is about 20 %. Plain sedimentation is found to be as efficient as chemical precipitation for all parameters except chromium. However, as the results are evaluated with regard to pretreatment standards chemical precipitation is suggested to be the method of choice to meet the chromium as well as suspended solids and sulfide standards.
Treatment of Recalcitrant Organic Compounds in Oil Reclaiming Wastewater by Ozone/Hydrogen Peroxide and UV/Titanium Dioxide
Authors: Gulyas H. , Bockelmann D. , Hemmerling L. , Bahnemann D. , Sekoulov I.
Published: May 2018

Refractory organic compounds in samples of a biologically treated oil reclaiming wastewater with a COD of about 300 mg/l were removed by ozonation with or without hydrogen peroxide or by irradiation with UV light in the presence of titanium dioxide in laboratory scale batch experiments. A 5 hrs UV/TiO2 treatment at pH 3 (energy consumption: about 0.9 kWh/l) resulted in a COD elimination of 70% and an enhanced biodegradability of the organic wastewater constituents. Ozonation was hardly affected by hydrogen peroxide, and a treatment for 47 min (energy consumption about 0.005 kWh/l) led to a COD reduction of about 17% and also to an improved biodegradability. Both processes are suitable for further treatment of biologically oxidized oil reclaiming wastewaters.
Nitrate removal from water supplies using biodenitrification and GAC-sand filter systems
Authors: Dahab M. F. , Sirigina S.
Published: May 2018

In this paper, a study on using fixed-film biological denitrification to remove nitrates from water supplies is reported. Fixed-film biological systems have not been used in water supply systems in the U.S. although they are proven to be efficient and economical for removing nitrates with the reason being the possibility of imparting residual organics, suspended solids and bacteria to the treated water. In this research, fixed-film upflow biodenitrification columns were operated under carbon-starved conditions and the effluent was treated with a granular activated carbon (GAC) and sand filter system (combined in one unit) to remove residual organics and suspended matter. The system resulted in an average effluent turbidity of 0.8 NTU, and COD and total suspended solids (TSS) concentrations of 5.7 and 0.6 mg/L, respectively.
Effects of water characteristics on granular sludge formation in a USB reactor for denitrification of drinking water
Authors: Tarre S. , Armon R. , Shelef G. , Green M.
Published: May 2018

The effects of water chemical composition on granular sludge formation in a denitrifying USB reactor was studied. The mineral fraction and sludge volume index (SVI) of the granular sludge in the reactor were found to be closely related to the composition of the influent water. Groundwater and simulated ‘hard’ water produced granules with good settling characteristics and high reactor VSS concentrations. Sludge granules from the reactor fed with surface water, which had lower concentrations of calcium and alkalinity, had a low mineral content and high SVI values resulting in biomass washout and reactor instability. The mineralization process, as expressed by the sludge's ash content (mainly CaCO3), is due to an increase in the pH and alkalinity during denitrification thereby changing the reactor's precipitation potential.
Identification of Trace Organics in a Treated Lubricating Oil Refinery Wastewater
Authors: Töws I. , Albers G. , Gulyas H. , Eickhoff H.-P. , Reich M. , Sekoulov I.
Published: May 2018

Organic substances in the influent and in the effluent of a fixed bed biology located at a lubricating oil refinery were characterized by gas chromatography/mass spectrometry (GC/MS). Totals of hydrocarbons were 0.8 mg/l (influent) and 0.1 mg/l (effluent) indicating a biological removal of nearly 90% of the hydrocarbons. High temperature gas chromatography/high resolution mass spectrometry of 1,1,2-trichloro-trifluoro-ethane extracts revealed that monocycloalkanes were the major group of hydrocarbons in the influent (590 µg/l) as well as in the effluent (65 µg/l) of the biological stage. A small amount of the hydrocarbons in the influent were aromatic compounds (mainly alkyl benzenes and benzocycloalkanes) which were degraded in the bioreactor to a lower extent than the aliphatic compounds. In dichloromethane extracts of the 60-fold concentrated effluent of the biological stage only few organics were identified gas chromatographically. Besides 1-methyl-2-propyl-cyclohexane a couple of ethers and nitrogen-containing heterocycles were the main components detected in the dichloromethane extracts. The data presented here confirm that aerobic fixed bed biology is an efficient final treatment step for refinery wastewaters.
Application of Immobilized Nitrifiers Gel to Removal of High Ammonium Nitrogen
Authors: Tanaka Kazuhiro , Nakao Masakazu , Mori Naomichi , Emori Hiroyoshi , Sumino Tatsuo , Nakamura Yoshio
Published: May 2018

Immobilized nitrifiers gel was used to remove high levels of ammonium nitrogen from the exhaust gas scrubber wastewater of a municipal sludge drying facility. Prior to full-scale application, the effects of temperature and pH on characteristics of immobilized gel pellets and the removal of ammonium nitrogen were investigated. The activated sludge was entrapped in polyethylene glycol gel, and elastic pellets containing activated sludge were obtained. The lifespan of the pellets in terms of compressive strength was estimated using Arrhenius equation. The results indicated that the lifespan of the pellets was at least five years at pH between 6 and 9, and at a temperature of 40 °C. The pilot plant study showed that wastewater containing 95-260 mg/l of ammonium nitrogen could be treated by immobilized pellets within a retention time of 6 hours and the removal of ammonium nitrogen was 98%. The 480 m3/d full-scale plant was constructed and has been operated successfully.
The ecological state of the Elefsis Bay prior to the operation of the athens sea outfall
Authors: Theodorou A. J.
Published: May 2018

Nutrient pollution in Elefsis Bay arises mainly from the disposal of Athens untreated wastewater at the eastern entrance of the Bay. The absence of river discharge, lack of cultivated agricultural areas providing runoff and the Bay's limited circulation provide the conditions for the Bay's eutrophication by the discharge of untreated wastewater. In the spring of 1993 this discharge was replaced by a new deep outfall system. To monitor any future changes an assessment of the present ecological state of the Bay is required. Analysis of appropriate data showed that Elefsis Bay accumulates nutrients. In summer a strong thermal stratification causes anoxic conditions to occur in the lower layer. The ecosystem exhibits reduced species diversity and strong oscillations of plankton annual cycles. Flagellates (Cryptomonas sp.) dominate the phytoplankton, followed by dinoflagellates (Gyrodinium aureolum, Prorocentum dentatum) and only in the spring diatoms (Nitzschia) predominate. The zooplankton was dominated by copepods (Acartia clausi) and cladoceran (Podon polyphemoides). Macrobenthos consists of a small number of pollution-resistant species of Polychaeta (Capitela capitata), whilst in summer only one species of Molluscs (Corbula gibba) survives.
An analysis on parameters of suspended sediment models for a shallow lake
Authors: Koncsos L. , Somlyody L.
Published: May 2018

The objective of the present paper was to clarify the inconsistencies on parameters of two formerly developed resuspension models for Lake Balaton. With the aid of a new scale analysis based on the Richardson law it was demonstrated that the settling velocity of the resuspended sediment particles is primarily dependent on the hydrodynamic conditions and the water content of the sediment. On the other hand the particle size distribution of the bottom sediment does not play a significant role in influencing the settling velocity.
Characterization of detachment mode of biofilm developed in an attached-growth reactor
Authors: Ohashi Akiyoshi , Harada Hideki
Published: May 2018

In this study the in situ behavior of biofilm development and detachment was continuously observed by a video camera. The model biofilms consisting of denitrifiers were formed on the flat surfaces of polyvinyl-chloride plates that were placed in a rectangular open-channel reactor. The effects of intrinsic biofilm properties on biofilm detachment, such as intrafilm gas-vacuoles formation, extracellular biopolymer (ECP) content, biofilm density and cavity formation at the biofilm/substratum interface were quantified using attached-biofilms onto flat substrata. The result indicated that there were three phenotypes of massive biofilm detachment (see Fig. 4) under the conditions of low shear stress of flow. The first type showed that a large fraction (approximately 1/4-1/3) of the biofilm was sloughed off as a whole layer from the substratum surface at a relatively early stage of biofilm formation. This type was primarily caused by the cavity formation and by the decrease of ECP content. Succeeding to the first type, the second type occurred as fragmentary detachments. The second phenomenon was attributable to the increase in biofilm buoyancy due to the gas-vacuoles formation within the biofilm. The third type took place as the combination of the first and the second types following the occurrence of the second type. In contrast, at a higher flow shear stress only the second type of detachment became prevalent throughout the progression of biofilm formation.
Biological wastewater treatment by three-phase fluidization - characteristics and basic design method
Authors: Hirata Akira , Noguchi Motoharu
Published: May 2018

A three-phase fluidized bed bioreactor is expected to treat wastewater quite efficiently, because the reactor has large specific surface area of biofilm, and oxygen for the biodegradation is simultaneously supplied from gas to liquid with oxygen consumption for biooxidation. However the reactor design and operation had been quite difficult particularly with a plug flow type fluidized bed, because of complicated behavior in the reactor. This paper concerns the current research work by the authors in focusing on the following characteristics and basic design method: (1) Behavior of biofilm immobilization on particulate media, fluidization of immobilized biofilm media and characteristics of oxygen absorption and substrates biodegradation. (2) Characteristics of biological treatment by immobilized biofilm. (3) Basic design method of a plug flow type three-phase fluidized bed bioreactor.
Spatial arrangement of the components of activated sludge flocs
Authors: Zartarian F. , Mustin C. , Bottero J. Y. , Villemin G. , Thomas F. , Aillères L. , Champenois M. , Grulois P. , Manem J.
Published: May 2018

The purpose of this work was to observe the internal structure of activated sludge flocs and the relationship between the different components. Activated sludge flocs from the municipal sewage treatment plant at Nancy (France) were physically stabilized and solidified in an epoxy resin. The flocs were sliced into 0.1 μm thick sections and stained for characterisation of components and exopolymers by transmission electron microscopy. One small floc (10 μm × 20 μm), embedded in resin, was chosen and studied using a laser scanning confocal microscope. The focal plane was incremented in steps of 2 μm along the z axis of the microaggregate. In order to extract quantitative data (number of cells, floc size) a numerical treatment of the images was applied.

A typical floc exhibits an unhomogeneous distribution of the mass of the exocellular polymer matrix (mainly polysaccharides). This matrix maintains the integrity of the floc and connects most of the components. These components are isolated bacteria, waste and debris inherited from the effluent and microcolonies. The structure of the microflocs is fractal with a fractal dimension Df ≈ 3. This large value implies that the growth of the small aggregates is possibly generated by cellular division and polymer production.
Development of a land limited wastewater treatment plant for small and rural communities in the tropics
Authors: Yang P. Y. , Chen H. , Ma T.
Published: May 2018

The treatment systems for strict and moderate land limited approaches were investigated. Both synthetic glucose and actual wastewater (domestic wastewater) were studied. For the strict land limited approach, a packed entrapped mixed microbial cell (PEMMC) process using cellulose triacetate as the polymer carrier was tested for synthetic wastewater. For the moderate land limited approach, a combined aquatic weed on the water surface and a bio-fixed film in the lower portion of the pond system was investigated for both the synthetic and actual wastewater. The actual domestic wastewater was examined in a single pond system with vertical flow under the BOD5 loading rate of 135 Kg/ha/day. BOD5 and nitrogen removal efficiencies of more than 85% and 70%, respectively, were received. The glucose synthetic wastewater was examined in a single pond system with horizontal flow at a BOD5 loading rate of 130 Kg/ha/day. BOD5 and nitrogen removal efficiencies of 92% and 60%, respectively, were received.

For the strict land limited treatment approach, it was found that more than 90% and 85% of soluble COD and total COD (including effluent suspended solid), respectively, could be removed at the loading rate of 1.6 g COD/L/day. The hydraulic retention time of 3.5 hours and the influent COD concentration of 200-250 mg/L were maintained and operated. This is comparable with the process performance of the conventional activated sludge for treating the domestic sewage under the same operational conditions. The PEMMC process also provides the advantages of maintaining a high SRT (Solid Retention Time) without external sludge recycling and a short starting period of less than 10 days.

Application of the present two systems will be dependent on the land and/or energy requirement. It is appropriate to use the treatment system of combining the aquatic plant with the bio-fixed film for moderately available land and in tropical areas. A strict land limited treatment system, of course, requires additional energy input.
On-line automatic control system for monitoring an anaerobic fluidized-bed reactor: response to organic overload
Authors: Moletta René , Escoffier Yves , Ehlinger Frédéric , Coudert Jean-Pierre , Leyris Jean-Pierre
Published: May 2018

The aim of this study was to develop an automatic system based on selected parameters collected from the biological process to control a fluidized-bed reactor. In the first part of this study, identification of parameters sensitive to overloads was carried out with vinasses as wastewater. From these results, three parameters, considered as the most realistic for the monitoring of the reactor, were selected: pH in the liquid phase, the biogas production and its concentration of dihydrogen. These were used to develop an algorithm based on expert system principle. This automatic control system calculated the flow rate of the feeding pump in order to adjust continuously the load applied to the reactor. The system was used to monitor and control several kinds of overload in an anaerobic fluidized bed reactor, of laboratory and pilot scales. The strategy used was able to operate automatically the digesters.
Upgrading to nutrient removal by means of internal carbon from sludge hydrolysis
Authors: Brinch Pia Prohaska , Rindel Kim , Kalb Kathryn
Published: May 2018

Due to the introduction of stricter nutrient effluent standards, many existing wastewater treatment plants performing only primary or secondary treatment are about to be upgraded. As the space available at the plants is, however, often limited, processes are required which will accommodate the need for increased treatment capacity without requiring much more space. In the hydrolysis of primary or pre-precipitated sludge direct-degradable organic carbon is produced which can speed up the reaction rate and increase both biological phosphorus and nitrogen removal. Full-scale tests with dosing of hydrolysate for biological P and N removal, respectively, have shown that this is a most viable process. The use of on-line monitoring has improved the process further.
Organic and ammonium nitrogen and oxygen in relation to granular sludge growth in lab-scale UASB reactors
Authors: Thaveesri J. , Gernaey K. , Kaonga B. , Boucneau G. , Verstraete W.
Published: May 2018

Laboratory studies of in-reactor granular-sludge yield (Ygran) were carried out to investigate the effect of substrates rich in proteins. Both lab-scale upflow anaerobic sludge blanket (UASB) and shake-flask systems were used to monitor the behaviour of the sludge. Influent based on molasses with a COD to N ratio of 100:2.5-3.0 gave good Ygran; increasing substitution of the carbohydrate COD by protein COD resulted in a deterioration of the sludge characteristics. The negative effects appear to be related to the protein rather than to the NH4+ formed. Of the various environmental parameters examined, the surface tension of the mixed liquor was the main deviating factor. At a proper range of oxygenation i.e., by means of monitoring of both the input COD to oxygen ratio (gCOD gO2−1) and the daily oxygen loading rate (mgO2 gVSS−1.d−1), the UASB reactors treating the nitrogen-rich wastewater showed enhanced Ygran with only a minor reduction in methanogenesis. A range of working conditions in which this principle can be applied to decrease fluffy growth to the advantage of granular increase is proposed.
Upgrading of waste-water treatment plants for the biological nitrogen elimination by the injection of on-line prepared mixed cultures
Authors: Glancer Margarete , Ban Siniša , Soljan Vice , Pascik Imre
Published: May 2018

By mixing of defined single bacterial and yeast strains with known biokinetic and growth properties, it is possible to prepare various efficient designed mixed cultures for the biodegradation of defined persistent substances and their derivatives. Preparing the mixed cultures on line in separate propagators and enriching the activated sludges semi-continuously by injection of the mixed culture into the activated sludge reactor it is possible to improve the biodegradation efficiency of waste water treatment plants. Applying this technology in a cokery effluents treating plant designed for the removal of COD and phenols, additionally to an improved COD-removal it succeeded in establishing a very efficient nitrification. Injecting a mixed culture, containing oxygen tolerant denitrifying strains into the municipal waste water treatment plant of Salzburg it was possible to establish a simultaneous nitrification and denitrification under aerobic conditions
Stirring and aeration system for the upgrading of small waste water treatment plants
Authors: Höfken Marcus , Zähringer Katharina , Bischof Franz
Published: May 2018

A novel agitating system has been developed which allows for individual or combined operation of stirring and aeration processes. Basic fluid mechanical considerations led to the innovative hyperboloid design of the stirrer body, which ensures high efficiencies in the stirring and the aeration mode, gentle circulation with low shear forces, excellent controllability, and a wide range of applications.

This paper presents the basic considerations which led to the operating principle, the technical realization of the system and experimental results in a large-scale plant. The characteristics of the system and the differences to other stirring and aeration systems are illustrated. Details of the technical realization are shown, which conform to the specific demands of applications in the biological treatment of waste water. Special regard is given to applications in the upgrading of small compact waste water treatment plants.
Increase of efficiency of an activated sludge plant in paper manufacturing industry by application of a fluidized bed system
Authors: Schneeberg Emil
Published: May 2018

In the past the paper mill Niefern GmbH had a yearly production of approximately 20 000 tons of high quality refined paper. For the purification of its wastewater in 1978 the paper mill put a mechanical/biological wastewater treatment plant into operation. Over years the conditions for the effluent concentration into the receiving water could be kept below requirements.

In the course of the years the production was switched over more and more to recycling products. Therefore the hydraulic load of the wastewater treatment plant increased by 140 %, the organic load by 295 %.

In order to keep the minimum requirements for the future the upgrading of the company's wastewater treatment plant became necessary. A conventional extension of the wastewater treatment plant was not possible because of the extremely restricted space. Therefore it was decided to employ a fluidized bed for the upgrading of the plant.

In spring 1991 the extended wastewater treatment plant was put into operation. The company's experience within approximately 1 1/2 years showed that upgrading of water purification plants by additional use of fluidized bed systems in paper producing factories offers an ecological and convenient possibility for extension.
Ultrafiltration membrane separation for anaerobic wastewater treatment
Authors: Fakhru'l-Razi Ahmadun
Published: May 2018

Membrane technology has attracted a lot of attention from scientists and engineers in recent years as a new separation process. Various membrane technologies such as reverse osmosis (RO), ultrafiltration (UF) and microfiltration (MF) have been successfully used for a variety of water and wastewater treatment applications.

In this study UF membranes of 10 000 nominal molecular weight limit were used in conjunction with an anaerobic reactor to treat wastewater from a brewery. The UF membranes serve to retain active biomass in the reactor, which is essential for a good reactor performance and for the production of a clear final effluent. The reactor was operated over a range of hydraulic retention times and organic loading rates (OLR) in order to evaluate its treatment efficiency.

Six steady states were attained over a range of mixed liquor suspended solids (31 000-38 000 mg 1−1). The maximum organic loading rate applied was 19.7 kg COD m−3 d−1 resulting in a methane yield of 0.27 1 CH4 g−1 COD. The percentages of COD removal achieved were above 96%. The results indicated that the UF membranes were capable of efficient biomass-effluent separation thus preventing any biomass loss from the reactor and have potential for treating industrial wastewaters.
Three-phase anaerobic digestion of organic wastes
Authors: Kübler Hans , Schertler Cosima
Published: May 2018

A new process has been developed for efficient anaerobic digestion of the organic fraction of municipal solid waste. The BTA-process comprises pretreatment of incoming waste followed by a three-phase anaerobic biology consisting of acidification, solids hydrolysis and methanization. One main fraction of organic wastes is cellulose causing a diauxie effect during anaerobic digestion. Acidification of the pretreated waste occurs spontaneously, and is not limited by the level of anaerobic microorganisms in the waste. Solid retention time and pH in the hydrolysis reactor have an important influence on volatile solids degradation. Favourable conditions are pH 6.7 and solid retention times of 50 to 60 hours. Cellulose to lignin ratios in the products indicate an extensive degradation of cellulose.
Treatment of wool scouring effluent by anaerobic bioflocculation
Authors: Lapsirikul Wipa , Cord-Ruwisch Ralf , Ho Goen
Published: May 2018

Biological destabilisation of the wool grease/water emulsion in wool scouring effluent using anaerobic bacterial activity (biological flocculation) was investigated. The aim of biological flocculation is to remove the bulk of wool grease which is the major source of COD, therefore serving as a pretreatment step, prior to classical biological processes either aerobic or anaerobic.

In a semi-continuous system, a two-stage anaerobic bioflocculation process was employed to treat a high grease (> 15 g l−1) wool scouring effluent (WSE). After 110 days of operation, the process showed removal of 70 to 90% grease at a combined hydraulic residence time (HRT) of 4 to 10 days. With low grease (< 10 g l−1) WSE grease removal was lower. At an HRT of 3 days a single stage bioflocculation process removed 40% grease. The supernatant from the process was easily treated by activated sludge process reducing grease concentration from about 1.5 g l−1 to less than 0.1 g l−1 in the final effluent (HRT 3 days).

Methane production of the process was negligible. Most of the grease was removed by flocculation as a result of anaerobic bacterial activity. The mechanisms of the process were investigated by a series of batch experiments and found to be; (1) appropriate gentle mixing between WSE and anaerobic sludge results in the absorption of wool grease from the liquid to the sludge phase, (2) further destablisation of the wool grease emulsion is obtained when the mixed liquor is left undisturbed. The latter was due to bacterial activity and growth on organics contained in WSE.
A Continuous Simulation Approach to Design Storm Calibration
Authors: Cao Carlo , Piga Enrico , Saba Andrea
Published: May 2018

The paper suggests the opportunity to calibrate the design storm parameters and associated antecedent soil wetness conditions for each climatic situation of interest on the basis of the results obtained by means of a continuous simulation of catchment response, extended to a sufficiently wide spectrum of catchment characteristics. Assuming a suitable model to represent catchment response, calibration was performed by direct comparison between the peak flow probability distributions derived from design storm application and the related frequency distributions obtained through continuous simulation, in order to reach a reasonable agreement between the two. The results show that this methodological approach is fully satisfactory. Generally speaking, the synthetic storm parameters appear to be quite dependent on catchment loss characteristics, and especially on potential infiltration, but are almost insensitive to pervious soil percentage and to other factors related to net rainfall catchment response. For practical purposes, similar calibrations should be performed with reference to the main climatic situations of each region of interest. In this way the results could be applied, under similitude assumptions, to any specific location where detailed rainfall information is lacking or insufficient.
The Influence of Spatial Heterogeneity of Rainfall upon the Hydrologic Response of an Urban Drainage Basin
Authors: Brunelle D. , Blanchet F. , Rousselle J. , Jacquet G. , Guillon A.
Published: May 2018

Hydrologic models of the black box type are the easiest simulation models to use, as much for their simplicity of conception as for their fast calculation times. One drawback, however, is that these general models consider each rainfall event to be perfectly homogeneous over the entire drainage surface of the watershed. Of course, such conditions are practically non-existent given the short time steps used in urban hydrology which tend to accentuate the heterogeneity of rainfall events. The main objective of this study was to verify whether the spatial heterogeneity of rainfall does in fact influence the hydrologic response of an urban drainage basin. Upon observing the results obtained, differences in the response of the drainage basin for heterogeneous precipitation and homogeneous precipitation events of equal average intensity may be considered significant. Differences of greater than 35% for peak flows and 15 minutes for peak flow response times were observed in certain cases. The influence of spatial heterogeneity depends simultaneously upon the precipitation intensity, its duration, and also upon which zone is favoured by strong precipitation intensities. These factors aside, it was shown that the filling rate of the collectors also has an important effect.
Hystem-Extran – Improvements to EPA-Extran
Authors: Fuchs Lothar , Scheffer Claudia
Published: May 2018

The paper describes extensions to the EPA-EXTRAN module which can be used for single event or continuous rainfall-runoff simulations as well as for real time control purposes. For surface runoff three different approaches are described. Their use depends on the goal of the simulations - single event or continuous simulation - or the availability of appropriate data (detailed or lumped simulation). The extensions and modifications of the EXTRAN block are reducing stability problems at special structures and make it possible to simulate real-time control devices. The on-line version makes it possible to simulate the behaviour of these devices to test the control strategy for an existing sewer system. The model can be used for training the operators - connected to the control centre and using the available environment - or for testing and further development of the control strategy in a stand alone mode or connected to another PC.
Prediction of Suspended Solids in Urban Sewers by Transfer Function Model
Authors: Delleur J. W. , Gyasi-Agyei Y.
Published: May 2018

There is increasing concern about the sediments transported in urban storm sewers. Progress has been made on the measurement of suspended solids, and telemetry systems have been installed that permit remote access to flow, temperature and suspended solids concentration data. Using observations obtained in the main trunk sewer in Brussels, Belgium, a transfer function model for the prediction of suspended load concentration from temperature and discharge measurements was developed. This model is based on the transfer function methodology developed by Box and Jenkins. It is shown that the transfer function model correctly tracks the suspended solids observations and makes reasonable forecasts. It provides a valid alternative for the determination of suspended solids in urban sewers from discharge and water temperature observations which are more easily measurable on line than suspended solids.
Simulation of Basin Scale Runoff Reduction by Infiltration Systems
Authors: Herath S. , Musiake K.
Published: May 2018

A modelling approach is presented to simulate infiltration systems in urban areas. The model consists of a hydrological sub-model and an infiltration system sub-model. Infiltration characteristics of individual facilities are first established using steady state numerical simulation of Richards' equation. These are represented as linear relations between the facility water head and infiltration rate for given facility widths. The infiltration system model is obtained by applying continuity equation to infiltration facilities lumped over a sub-catchment. This model is then coupled to a catchment runoff model to simulate storm runoff with infiltration systems. The model is applied to an infiltration system installation in a residential area, where stormwater runoff is monitored in a pilot area and a comparative area. The observed results suggest the method is adequate to evaluate the performance of infiltration systems. Except for the catchment storage routing parameter, all model parameters are determined from physical catchment characteristics.
Alternative Urban Drainage Concept and Design
Authors: Grotehusmann D. , Khelil A. , Sieker F. , Uhl M.
Published: May 2018

A System of INterconnected Infiltration POnds and Trenches (SINIPOT) is presented as an alternative to classical solutions for the extension and/or renovation of urban drainage systems in Germany. In many cities, modifications of the existing drainage network have been necessitated by restrictive pollution laws. For a catchment in the City of Gelsenkirchen, long term simulations with a hydrologic transport model have been performed for three different sanitation solutions. The most important comparison criteria are the Combined Sewer Overflow (CSO) quantities and the induced flow pattern in the receiving waters (a small creek).
Transfer Function Modelling of Urban Drainage Systems, and Potential Uses in Real-Time Control Applications
Authors: Capodaglio Andrea G.
Published: May 2018

According to the present state-of-the-art, sewerage systems, sewage treatment plants and their subsequent improvements are often planned and designed as totally separate entities, each subject to a specific set of performance objectives. As a result, sewage treatment efficiency is subject to considerable variability, depending both on general hydrologic conditions in the urban watershed (wet versus dry periods), and on specific “instantaneous” operating conditions. It has been postulated that the integration of urban drainage and wastewater treatment design and operation could allow minimization of the harmful effects of discharges from treatment plants, overflows and surface water runoff. This “ideal condition” can be achieved through the introduction of so-called “real-time control” technology in sewerage collection and treatment operations. To be a feasible goal, this technology poses the demand for more powerful simulation models of either aspect of the system - or, ideally, of a unified sewer-and-treatment plant model - than most of those currently available. This paper examines the requirements of rainfall/runoff transformation and sewer flow models with respect to real-time control applications, and focuses on the methodology of stochastic, transfer function modelling, reporting application examples. Modalities and limitations of the extraction of information from the models thus derived are also analyzed.
Scenario Analysis of Pulp Manufacture in Finland to the Year 2010
Authors: Malinen Raimo , Wartiovaara Ilkka , Välttilä Olli , Anttila Suvi
Published: May 2018

A scenario analysis was performed of alternative methods of pulp production in Finland up to the year 2010. The analysis included the effects of changing to totally chlorine-free bleaching of kraft pulp (TCF pulp), closure of the water cycles at kraft mill bleaching plants, and increased use of recycled fibre in papermaking. Scenarios for total figures in Finland were evaluated anticipating four different courses in the use of new technology and the increasing use of waste paper and TCF pulp.

The results revealed that the high investment rate in effluent management and air pollution control during the 80s and 90s will result in a very significant decline in pollution from the Finnish forest industry before the year 2000. The technology needed to eliminate AOX would be very costly and would have no significant effect on pollution parameters other than AOX. Closing the water cycles at kraft mill bleaching plants would cut discharges of dissolved substances and nutrients from the pulp and paper industry to at most half of those achievable with external methods.