bluuebunny/crossref_metadata_2025 huggingface dataset:
Control Objectives and the Modelling of MLSS in Oxidation Ditches
Authors: von Sperling M. , Lumbers J. P.
Published: May 2018

The role of the adequate control of the mixed liquor suspended solids (MLSS) in the overall performance of oxidation ditches is discussed. A dynamic model, developed principally for the control of MLSS in the short term incorporating diurnal variations, is described. The predicted model states are MLSS, return sludge suspended solids, dissolved oxygen, ammonia, sludge blanket height, effluent suspended solids and effluent BOD and the forcing functions are influent flow, suspended solids and ammonia. The simplified nature of the model makes it suitable for real time control purposes with the input variables being measurable on a continuous basis. The initial calibration and validation used data collected from a full-scale plant and gave satisfactory results for short-term predictions with good indications that the model is also valid for longer-term applications.
Measurements, Data Analysis and Control Methods in Wastewater Treatment Plants–State of the Art and Future Trends
Authors: Olsson Gustaf , Andersson Bengt , Göran Hellstrom Bengt , Holmström Hans , Reinius Lars Gunnar , Vopatek Petr
Published: May 2018

This paper is a summary of a committee working for the Swedish Water and Wastewater Works Association (VAV). The purpose of the report is to present the possibilities today to measure, present and analyze data and control treatment plants. The typical audience is the operator, the process engineer, or the consulting engineer. The methods presented are all known from different disciplines, but are here presented in a form that connects the methods to wastewater treatment operation. Unlike any manual of practice the report is not a concensus report of current practice-Rather it is an attempt to show the potential of modern methods for data analysis and control. This will help the potential equipment or computer buyer to specify relevant demands for the system.

The fact that any wastewater treatment plant is highly dynamic has to be reflected both in measurements and in control. The report discusses relevant sampling times for different measurements, both from the inherent dynamics and from the variability of the disturbances. Current design practice is almost always based on steady state analysis, and disturbances are too often controlled by larger tank volumes rather than relevant control actions.

In order to obtain relevant data analysis the purpose of the measurement has to be clearly stated. Interesting and relevant measurement variables are listed. Moreover, a short survey of existing instrumentation and its status is presented. The transfer of data from the primary sensor to the computer has to be carefully designed.

Once the data is in the computer, the data structure must be specified. The different compromizes between storage capacity, data formats and other relevant information are discussed. Simple measurement handling is described before statistical analysis is discussed. Numerous examples demonstrate the results. Some methods for parameter estimation and model building from measurement data are discussed, particularly with the purpose to make the methods available for on-line use. It is shown how estimated models can be used for the operation of plants. Different control methods are discussed. The basic kind of local control to keep the plant running is first mentioned, but more emphasis is laid on plant quality control, like dissolved oxygen, return sludge and waste sludge control.

Dynamic models offer interesting possibilities for plant simulation, and simulators are being developed, that can support the operator with further predictive information. Some future possibilities of knowledge-based systems for process diagnosis are further discussed. They offer new possibilities to use natural language for systematic error analysis and diagnostic searches.
Sludge Reaeration in Two-Step Nitrification
Authors: Bailey W. , White W. , Wilber C. , Wilson T. E. , Bizzarri R.
Published: May 2018

The District of Columbia has developed a unique way to overcome site limitations, reduce tankage requirements and at the same time add flexibility to its Blue Plains wastewater Treatment Plant. This 13.6 m3/s (309 MGD) two-stage nitrification plant will be expanded to 16.3 m3/s (370 MGD) by using step feed in both steps. Providing step-feed capability is already well known to be an effective method for reducing tankage and providing operating flexibility for secondary (carbonaceous) systems. Using it in a nitrifying system is believed to be unique, however. This paper discusses these Blue Plains Step Feed upgrades: full step feed in the carbonaceous step, limited step feed (re-aeration) in the second step. Also presented is a generalized comparison of single and two-stage step-feed plants which shows the advantages of the latter.
Operation of the Soreq Wastewater Treatment Plant with a Single-Stage Nitrification-Denitrification Activated Sludge System
Authors: Arueste G. , Farchill D. , Goldstein M. , Gruber Y.
Published: May 2018

The Soreq Biological wastewater Treatment Plant has been in operation almost one and a half years. The treatment performance and operational data obtained during the first year of full-scale operation, following the running-in period, are detailed in this paper as four consecutive seasonal operating periods. The results achieved have demonstrated the efficiency, in carbonaceous matter removal and the nitrification-denitrification processes, of the single-stage system, operated without primary treatment.

The influence of various operating parameters on the efficiency of the biological process and on the sludge settleability have been analysed. Two anaerobic tanks, preceding the anoxic zone of the biological reactors, were brought into operation at the end of March 1988. The influence of their addition to the biological process train has also been included herein.
Full-Scale Experiences with Biological Phosphorus Removal at the Wastewater Treatment Plants of West Berlin
Authors: Boll R. , Kayser R. , Peter A. , Sarfert F.
Published: May 2018

In investigations concerning sludge bulking in Berlin enhanced biological phosphorus removal was first observed unexpectedly. Because since 1986 an officially preset limit of 2 mg TP/l must be kept in all Berlin wastewater discharges it was decided to explore the capabilities of the observed mechanism under the specific circumstances of the existing two large treatment plants in Ruhleben (240,000 m3/d) and Marienfelde (100,000 m3/d). For this purpose some of the existing units at both plants were equipped with anaerobic zones which were generated mainly by process modifications. Additionally stage one of the Ruhleben plant was altered completely in order to investigate the combination of biological phosphorus and nitrogen removal as a special pilot study in three parallel trains. The research activities and treatment results gained in each of the two stages of the Ruhleben and in the Marienfelde plant are reported in detail. For example BOD-related phosphorus removal rates were obtained ranging from 2.3-4.5 mg TP per 100 mg BOD removed. It must be stressed that all examinations were performed under full-scale conditions. At present the given limit of 2 mg TP/l in the Ruhleben plant is met without any chemical precipitation at least on average. From the beginning biological phosphorus removal will be integrated into further projected extensions.
The Mersey Basin Campaign–The Technical Challenge
Authors: Alexander B. , Harper E.
Published: May 2018

The Mersey Basin Campaign is a major initiative launched in 1984 to revitalise the river system of the River Mersey and the adjacent waterfront. The long-term programme of major investment by North West Water to tackle the seriously polluted conditions of the river and estuary of the basin forms the central core of the Campaign. This programme provides for the substantial improvement of the ageing and inadequate sewerage and sewage disposal systems. The paper will review the technical challenges facing North West Water in the investigations, research and plans to meet the objectives for river water quality throughout the basin. The extensive pollution and the exceptional concentration of urban development and population require the production of integrated catchment plans for the most cost-effective investments for the achievement of modern environmental standards. The complex investment choices will require optimum solutions for the achievement of the right infrastructure balance between improved sewerage systems and effective sewage treatment. A key feature of the Campaign has been the commitment in terms of considerable financial support from the European Community.
River Basin Management in Scotland
Authors: Hammerton D.
Published: May 2018

The seven river purification boards, which cover the whole of mainland Scotland, are strictly single-purpose authorities whose function is to control pollution of inland and coastal waters. Unlike the water authorities in England and Wales they are not responsible for the management of water supplies, sewerage, sewage treatment, land drainage, flood prevention or fisheries. However, the author contends that it is this singleness of purpose and the complete independence of the boards from the polluters, whether local authorities or private industries, which has led in Scotland to better progress in the restoration of polluted waters than south of the border, progress which has been clearly demonstrated in recent government reports. Moreover, through close consultation at the planning stage with government departments, local authorities and other bodies, the river boards do have a significant influence on developments which affect the aquatic environment and hence are involved in the wider aspects of river basin management.
The Vienna Sewerage System
Authors: Bortenschlager Peter
Published: May 2018

After the practice for many decades had been to introduce waste waters into the nearest receiving bodies, i.e. Wien River, Donaukanal, and Danube, a multitude of intercepting sewers and a central treatment plant were built from 1969 to 1980. Subsumed under the working title “WABAS 80 -- Wiener Abwasserbeseitigungssysteme 1980”, these facilities guaranteed that all effluent produced in Vienna was brought to the central treatment plant for purification. Since 1986 a programme has been in effect to expand the existing sewage system and improve obsolete sewers, the aim being to preserve groundwater quality. Providing also for the construction of relief interceptors along the Donaukanal and the Wien River as well as the enlargement of the central treatment plant, the programme was designed not only to preserve but also to improve water quality in the Donaukanal and the Danube itself. The City has set apart AS 12 000 million for this project, which is to be completed by 2000.
Effect of Mercury on the Survival of Daphnia Magna
Authors: Brković-Popović I.
Published: May 2018

The median lethal time (LT) for each concentration of mercury was determined on the basis of mortality curves. Toxicity curves (i.e., the median life-span of Daphniamagna, LT 50, versus the concentration of mercury) for four tested conditions are shown. The experiments were carried out using two diluents of different total hardness (46 and 119 mg/l as CaCO3), at two temperatures (20°C and 25°C). A comparison of the LT 50s of the control organisms with the LT 50s of the test organisms at mercury concentrations of 0.0075 and 0.0050 mg. l-1 showed that the chemical characteristics and temperatures of the mediums tested did not affect the range of the ‘no effect' concentration. However, the incipient LC 50, and the time required for its appearance, did depend on the combination of the abiotic factors tested.
Removal of Coliphages from Wastewater Effluent by Phototrophic Bacteria
Authors: Hirotani H. , Agui Y. , Kobayashi M. , Takahashi E.
Published: May 2018

A wastewater purifying process using a phototrophic bacterium, Rhodopseudomonascapsulata, is presently operating in several countries. Removal of coliphage during the process was assessed by a field-test and a model study. It was found that 97.4% of coliphage was removed during the purification of wastewater from a pigpen. The model study was performed to ensure that the removal was due to biomass of the phototrophic bacterium, which produces an antiviral substance. Phage inactivation by chloroform-methanol extract from the bacterium with the presence of kaolinite as a contaminating particulate is also shown to describe the efficiency of the antiviral substance from the phototrophic bacterium to wastewater.
Evaluation of Purification Efficiency of Activated Sludge Treatment Plants for Pulp and Paper Industry Wastewaters in Finland
Authors: Junna J. , Rintala J.
Published: May 2018

Since 1984, when the first activated sludge treatment plant (ASTP) was built to treat pulp and paper industry wastewaters in Finland, twenty more plants have been introduced by 1989. An evaluation was undertaken to find out the actual performance of the ASTPs in BOD7, CODc r and phosphorus removal. The evaluation included all the 12 ASTPs in operation in the pulp and paper industry at the beginning of 1987. The highest average BOD7 removals were about 90 % at pulp mills as well as paper and board mills. CODc r removal was generally higher at paper and board mills (about 40-70 %) than at pulp mills (about 25-55 %). Phosphorus was added to wastewater in most plants. In some ASTPs, phosphorus concentrations were lowered by 20-40 % compared with wastewater from the mill. In some plants phosphorus load on the recipient was higher than the load coming from the mill. In treated wastewater, correlations between suspended solids and BOD7, CODc r, phosphorus and nitrogen were significant in most plants. This indicated that low removal efficiencies resulted from poor suspended solids removal in the secondary clarification. Volumetric and sludge CODc r loading rates could not explain removal efficiencies when all plants were included in the comparison. In plants treating chemical pulping effluents, higher removal efficiencies were normally achieved with lower loading rates. When the plants were studied separately, the influence of loading rate was generally significant.
Effects of Temperature and pH on the Settleability of Activated Sludge Flocs
Authors: Çetin F. Dilek , Sürücü Gülerman
Published: May 2018

In efficient and economical treatment of wastewaters,the settleability of activated sludge is of prime importance. Efficient settlement in the secondary sedimentation tank is required, both to keep the desired effluent quality and to sustain the necessary amount of microorganisms in the aeration tank. On the other hand, the settleability of microorganisms in the secondary clarifier is very dependent on the physiological and biochemical nature of activated sludge flocs, which are determined by the conditions of the aeration tank.

In this research, effects of temperature and pH of aeration basin on settleability of activated sludge were studied. Settleability was measured by zone settling velocity and sludge volume index (SVI). Five different temperatures and four different pH values were operated in the aeration basin. It was found that the settleability of activated sludge is greatly affected by these two parameters.
Pilot and Full-Scale Treatment Experiences on Paper Mill Effluents
Authors: Ozturk I. , Eroglu V. , Toröz I.
Published: May 2018

In this paper, biological treatability study results of a pilot-scale aerated lagoon treating white-waters from a mechanical groundwood-based pulp and paper mill, and long-term operating experiences on two full-scale aerated lagoon systems are presented. Biological treatability study was conducted in a 200 1 semi-pilot aerated lagoon. The results have shown that five-day Biochemical Oxygen Demand (BOD5) values are less than 50 mg/l for a hydraulic retention time of 5 days. BOD removal rate constant (K) was found as 1.01 per day for 20°C. Bioassay tests were also conducted to evaluate the toxic impacts of white-waters on receiving waters and 96 hours median tolerance level TL(96), was found as 84% for species Lapistes reticularis. Long-term operating results from two full-scale wastewater treatment plants for paper mill effluents are also presented.
Comprehensive Sludge Management Planning for the Hyperion Treatment Plant (Los Angeles, USA)
Authors: Harrison David S. , Smith Bradley M. , Crosse John T.
Published: May 2018

The City of Los Angeles Hyperion Treatment Plant currently processes 1.44 × 106m3/d (380 mgd) of flow with a secondary treatment capacity of 7.19 × 105m3/d (190 mgd). Under Federal Court Order, the City ceased ocean discharge of sludge in November, 1987, and will upgrade the plant's capacity to 1.7 × 106m3/d (450 mgd), with full secondary treatment, by 1998. The cessation of ocean discharge and the anticipated increase in sludge quantities led to the formulation of a Sludge Management Plan to address sludge processing facility needs on-site, as well as off-site options for reuse/disposal of dewatered sludge cake or sludge combustion ash. This paper presents the methods and analyses used to formulate the Plan, and the recommendations set forth in the Plan.
Sewage and Solids Disposal: Are Processes Such as Ocean Disposal Proper? The Case of Rio de Janeiro (Brazil)
Authors: Jordão Eduardo P. , Leitão Jorge R.
Published: May 2018

In developing countries, as is the case of Brazil, solutions proposed for sewage and sludge treatment and disposal must meet not only public environmental demands and obey proper legal regulations, but also take into account the availability of funds for new investments and operation of existing systems.

Brazilian federal regulations allow ocean disposal of sewage and solids, according to certain water quality criteria and specific standards.

On the other hand, federal regulations require that submarine outfalls must be studied by means of an Environmental Impact Assessment, and that a Report on the Environmental Impact be produced. Such studies must demonstrate that the site will be protected and that ocean disposal will not impair the environment and the beneficial uses, such as fisihing, recreation, navigation, or propagation of marine life.

The State of Rio de Janeiro has monitored its Ipanema Submarine Outfall since 1974, one year prior to going into operation. Present flow is 6m3/sec (140 mgd) of bar-screened domestic sewage. The submarine outfall is a 2.4m diameter concrete pipe, 4.3 km (2.7mi) long, and discharges at a depth of 27m (89ft). The paper presents and discusses existing regulations and data on the seawater monitoring program which is still in practice, having produced more than 90,000 analyses. Discussion covers the period 1974 - 1988, and shows that no adverse ecological impact has been noted on the marine ecosystem.
Evaluating the Impacts of Sludge Incineration Using a Risk Based Approach
Authors: Farrell Ann E. , Michalczyk Bert , Nance Anaya
Published: May 2018

The viability of continued sludge incineration at Central Contra Costa Sanitary District wastewater treatment plant is presented as a case study. A risk based approach was utilized to assess the long-term feasibility and cost of continued incineration compared to other available sludge handling methods. Three major tasks were conducted as part of the study: an incinerator capacity evaluation; a risk assessment; and, an evaluation of solids handling technologies. The study focused on toxics most often encountered in sewage incinerator emissions, including arsenic, beryllium, cadmium, chromium, lead, mercury, nickel, poly-chlorinated dibenzo-p-dioxins, and polychlorinated dibenzo-p-furans. The results of the study indicate that continued incineration of sludge is viable for Central Contra Costa Sanitary District, and that the most cost effective solids handling method is incineration using two duty units with backup provided by chemical stabilization. To confirm costs and design criteria, pilot testing of two potential back-up methods is currently being conducted.These methods are chemical stabilization and indirect drying.
Mesophilic and Thermophilic Digestion of Municipal Sludge in a Deep-Shaft U-Shaped Bioreactor
Authors: Tran F. T. , Tyagi R. D.
Published: May 2018

Aerobic digestion of primary and secondary sludges was studied in airlift bioreactors at mesophilic and thermophilic temperatures. The experimental studies were conducted with a laboratory U-shaped airlift reactor (operating volume = 23 1) and in a pilot U-shaped airlift reactor with an operating volume of 1150 1. In the laboratory reactor, at a lower temperature (6°C) and with a concentrated feed (3 to 4% solids) consisting of primary and secondary municipal sludge, a 30% VSS reduction was achieved with a hydraulic retention time of 2.5 days. A VSS loading rate of 8.2 kg VSS per m3 per day was achieved. This loading is comparable to that obtained in a pure-oxygen sparged mixed reactor.

In the pilot plant reactor at mesophilic temperatures (31 to 33°C), a VSS loading rate of 7.9 kg VSS per m3 per day and a VSS reduction of 33% were achieved with a hydraulic retention time of four days.
A Compaction-Granulation Process Turns Municipal Sludge into a Valuable Fertilizer Component
Authors: Wolstenholme Philip
Published: May 2018

To prepare dried municipal sludge material for use by the fertilizer industry, Ocean County Utilities Authority, New Jersey needed a process to increase the size of their sludge particles to between 1 and 3 millimetres. Several processes were evaluated during the planning and design phases of the project. The most cost-effective and reliable process was pressure agglomeration by compaction with a roll press, followed by granulation and screening of the compacted material. This process was tested with a sample of the Authority's digested sludge, which had been dried in a laboratory-scale evaporator. Fullscale compaction and granulation test equipment was used at a laboratory in West Germany to confirm the feasibility of the process and to develop data for the design of the project.

As a result of its “innovative” approach to sludge processing, the United States Environmental Protection Agency (EPA) qualified this $60 million project for special funding. The project is nearing construction completion and due to be commissioned in spring of 1990.
Solidification of Electroplating Wastewater Treatment Sludges with Cement
Authors: Rosa Cláudio Jair , Alem Sobrinho Pedro
Published: May 2018

At the São Paulo Metropolitan Area, the sludge resulting from treatment of electroplating industry wastewater is inadequately disposed of, generating environmental hazards. A possible way to solve this problem is the cementation of this sludge before disposal.

From July,1986 to March, 1987, the authors developed laboratory tests on cementation of electroplating wastewater treatment sludges. Performed at the laboratories of Escola Politécnica of the University of São Paulo and of CETESB, tests were conducted with three types of cement produced in Brazil - CPC - Portland Cement, POZ-pozzolanic cement and CAF - blast furnace cement. The tests had the following steps:characterization of electroplating industry wastewater treatment sludge and study of the sludge - cement mixtures;preparation of sludge - cement mixtures with water/cement ratios of 0.3, 0.5 and 0.7;measurements of mixture consistency with Casagrande soil mechanics equipment;determination of leaching quality and resistance to compression of solidified specimen at the ages of 7 days, 28 days and 90 days;analytical determination of the sludge cement mixture;test for solubility in water at the age of 90 days;analytical determination of cyanide and heavy metals in the cure water of specimen.

Results showed that solidification with cement is an efficient technology for the fixation of toxic metal ions such as Cd, Hg and Pb and other metals such as Cr, Ni, Cu or Zn present in large concentrations in electroplating wastewater treatment sludges. With the only exception of Al+++ the other metallicions determined in the leachate showed concentrations below drinking water standards. As to mechanical resistance after 90 days, the sludge - cement mixtures presented a performance similar to that of structural concrete.
Sewage Sludge Melting Process: Preliminary System Design and Full-Scale Plant Study
Authors: Sakai S. , Hiraoka M. , Takeda N. , Tsunemi T.
Published: May 2018

A sewage sludge melting process has been developed and some full-scale planls have been installed or are now under construction in Japan. Sludge melting process has its main advantages in that most sorts of hazardous materials, such as heavy metals, are tightly fixed in solid phase and the slag produced by this process can be used as construction materials. This article analyzes sludge treatment and disposal costs of the popular sludge treatment alternatives with emphasis on thermal processes, especially the sludge melting process. From preliminary system designs on a common design basis, relative energy requirements and total treatment & disposal costs were compared. As a result of cost analysis in terms of the annual treatment cost, it was revealed that the lime conditioning systems cost some 50% more than the polymer conditioning, that in a comparison between the incineration and the melting systems the treatment cost differed when the difference in energy cost was significant, and that in the anaerobic digestion systems the superiority in energy balance did not contribute to treatment cost reduction. Even if as one of the cost conditions to introduce the melting system in place of the incineration system, the ash disposal price is set as low as 5,000 yen/t, the coke melting system is still advantageous in the lime conditioning. Further, it turned out that in the polymer conditioning systems it was possible to establish cost conditions to introduce the melting system when the incinerated ash disposal price, the melting process coke ratio and the coke price took certain values.
Mechanisms and Kinetics of COD Removal and Simultaneous Oxygen Consumption in a Rotating Biological Contactor Biofilm
Authors: Bovendeur J. , Spuij F. , Hermans P. G. B. , Klapwijk A.
Published: May 2018

A study on aerobic biofilm COD removal and simultaneous respiration is made using a Wazu respirationmeter unit. In a closed recirculating system completely submerged RBC biofilm samples have been examined in short-term batch experiments, using the corresponding waste water or dissolved acetate. The removal of dissolved organic substrate and the respiration were found to answer the ½-order/0-order kinetic model, whereas the removal of suspended solids COD (CODs) showed 1-order kinetics. Under conditions usually met in practice the 0-order rates for dissolved COD(CODd) removal and respiration were 30–40 gm−2d−1 and 10–16 gm−2d−1, respectively; in absence of organic substrate a certain background respiration was observed (3.5–9.0 gm−2d−1). As a result of the 1-order kinetics over a wide concentration range, extremely high CODs removal rates were observed even exceeding 300 gm−2d−1. The difference between the maximum respiration and the CODs removal rates is attributed to physical biofilm adsorption processes. Biofilm COD removal kinetics for waste water containing both CODs and CODd are discussed, illustrating that the kinetic order of the combined process and the reaction constant strongly depends on the CODs/CODd ratio. Conclusion is that a RBC biofilm loaded with a CODs/CODd mixture oxidizes some dissolved organic matter and acts as a catalyst in the coagulation and flocculation of fine suspended solids.
Kinetics and Modelling of Aerobic and Anaerobic Film Growth
Authors: Capdeville B. , Nguyen K. M.
Published: May 2018

Our fundamental studies of the kinetics of growth and substrate removal by aerobic and anaerobic biofilms have shown that the process comprises six phases : the latent, dynamic, linear, decrease, stabilization and detachment phases. During these experiments we also observed:-steady state functioning in the liquid bulk from the end of the dynamic phase. At this point a very thin pseudo-thickness of biofilm was observed (50 µm maximum).-steady state functioning relative to the observed biofilm mass, reached in the stabilization phase, the corresponding thickness being generally several hundred microns.

To explain this phenomenon we suggest a new biofilm modelling hypothesis, based on physiological aspects, which consists of defining two types of bacteria : active bacteria (Ma) responsible for substrate removal and characterized by a specific growth rate (µo), and inert or deactivated bacteria (Md) which play no role in the removal process but are responsible for the observed accumulation of biofilm. Using this hypothesis, it is possible to modelize the dynamic and linear phases of growth of total biofilm dry matter (Mb) and carbon substrate removal kinetics.

This model enables the exponential growth rate (µo), the accumulation rate (K) and the maximum quantity of active bacteria (Ma)max to be calculated. In another series of experiments, we studied the influence on these parameters of several factors which affect growth, such as the carbon substrate concentration provided by the feed (So) and the dissolved oxygen for the aerobic biofilms.

The results demonstrate that the biological constants are strongly dependent on (So). The same is true for the volumetric substrate removal rate(kov), which shows that the process always depends on the reaction. Thus we have established that the substrate metabolization reaction occurs at the biofilm-liquid interface, and that it is preferable to use thin biofilms for an attached culture industrial process.

This has been done by optimizing the surface and volume properties of new granular materials called OSBG (Optimized Support for Biological Growth). Initial results, notably for three-phase fluidized bed carbon removal, show that it is possible to eliminate very high carbon loading (10 to 15 kg TOD.m3.day−1) under very stable conditions with a very small quantity of active biomass (0.5 D.W. m). In addition, excess sludge production is relatively low and respirometric studies performed in situ with a gas phase mass spectrometer confirm the very high catabolic activity of thin biofilm.
New Developments in Complete Nitrogen Removal with Biological Aerated Filters
Authors: Rogalla Frank , Bourbigot Marie-Marguerite
Published: May 2018

Biological aerated filters combine bacterial degradation of pollution by fixed biomass with physical filtration in a single reactor.Several full-size plants with the BIOCARBONE process have established the compactness, ease of operation and high removal rates achievable with this advanced treatment system. Based on large-scale industrial experiences, a new biofilter design offering simplified operation and increased performance is presented.

Design data for carbon and nutrient removal were collected during extensive pilot tests. Hydraulic conditions and pollution loadings were varied in order to optimize the biological and operational parameters of the filter. Carbon and ammonia oxidation as well as denitrification and suspended solids retention could be achieved with an overall hydraulic retention time of two hours.
Tertiary Nitrification Pilot Plants on Parisian Waste Water
Authors: Paffoni C. , Védry B. , Gousailles M.
Published: May 2018

The Paris Metropolitan area, which contains over eight million inhabitants, has a daily output of about 3 M cu.meters of wastewater, the purification of which is achieved by SIAAP (Paris Metropolitan Area Sewage Service) in both Achères and Valenton plants. The carbon pollution is eliminated from over 2 M cu.m/day at Achères. In order to improve the quality of output water, its tertiary nitrification in fixed-bed reactors has been contemplated. The BIOFOR (Degremont) and BIOCARBONE (OTV) processes could be tested in semi-industrial pilot reactors at the CRITER research center of SIAAP. At a reference temperature of 13°C, the removed load is approximately 0.5 kg N NH4/m3.day. From a practical point of view, it may be asserted that in such operating conditions as should be at the Achères plant, one cubic meter of filter can handle the tertiary nitification of one cubic meter of purified water per hour at an effluent temperature of 13°C.
Treatment of Distillery Wastewater Using an Anaerobic Downflow Stationary Fixed-Film Reactor: Performance of a Large Plant in Operation for Four Years
Authors: Racault Y.
Published: May 2018

The results of the first four years' operation of a downflow submerged packed bed reactor treating distillery waste with a COD of 30 g/l (95 % in soluble form) are presented. The digester contains 4300 m3 of packing, and is operational six months a year. It is one of Europe's largest units using this technique.

After a few problems with fixing the biomass on start-up, organic loading has been regularly increased, reaching an average of 6 kg COD/m3.d during the 2nd year and 10 to 12 kg COD/m3.d during the 4th year, with soluble COD reductions of 90 to 95 %. The biomass released into the treated effluent was in the region of 0.15 kg SS/kg COD eliminated in the latter campaign. Overall performance in the 2nd, 3rd and 4th seasons are presented and discussed. The stability of digestion was studied over the whole of the 2nd and 4th seasons using measures of VFA at various levels within the reactor. Tracer study was conducted at the end of 2nd year to characterize the hydraulic behavior of the reactor. Results indicated a flow pattern close to a complete mixing and dead space was in the region of 20 % of liquid volume.
Optimization of Nitrogen Removal in Small Activated Sludge Plants
Authors: Heduit A. , Duchene Ph , Sintes L.
Published: May 2018

In France, many small sewage treatment plants are of the activated sludge/extended aeration type and, generally, only receive a part of their nominal organic load. They are mostly equipped with surface aerators whose Standard wire Aeration Efficiency is in the range 1.3-1.9 kg 02 kwh−1. Consequently the sludge age and the supply of oxygen are sufficient to obtain a large elimination of nitrogen from domestic waste water even when the sludge temperature is low.

However the concern is with the optimizing of the nitrogen treatment by the nitrification of ammonia in the aeration basin whilst avoiding any parasitic denitrification in the clarifier.

Amongst other investigations, 4 small domestic wastewater treatment plants were studied over several months. A number of adjustment modifications were imposed on them in order to optimize the elimination of nitrogen : The final concentrations to be reached were : N-NH4− lower than 5 mg.l−1 and N-NO3− lower than 3 mg.l−1.

The daily operating time of the aerators depends on the received load, the sludge concentration and the oxygenation capacity. When the works are under-loaded, the non-operational periods of the aerators should be as long as 1 1/2 and 2 hours in order to achieve the nitrates reduction. When the load is higher, the time required to attain anoxia after the shutdown of the aerators is shorter and the length of the non-operational periods can be reduced. These field experiments have allowed an evaluation of the tolerances around an optimum adjustment of the aeration operation : a reduction of 5 to 10 % of the daily aeration time may bring about an increase in the residual concentration of Kjeldahl nitrogen which reaches 10 rag.1−1. Conversely, sludge losses may take place in the clarifiers if the daily aeration time is increased by 5 to 10 % in the case of completely mixed basins equipped with slow vertical shaft aerators, and more than 15 % in the case of oxidation ditches (better denitrification probably due to the continuation of the current after stopping the rotors). The sludge concentration should be kept within fairly tight limits (± 0.5 g.1−1). It is however essential to rectify the aeration adjustments during the seasons : a rise in the sludge temperature of 10°C generates an increase in the total oxygen demand by 3 to 5 %.

The particular case of plants with anoxic zone ahead is finally discussed.
Influence of Daily Variation of Flow and Pollution Load on the Performance of Submerged Anaerobic/Aerobic Biofilm System
Authors: Okubo T. , Okada M. , Murakami A. , Inamori Y.
Published: May 2018

Effects of daily variation of flow on the performance of submerged anaerobic/aerobic biofilm systems were investigated both by laboratory study using synthetic wastewater and by field study using gray water. In laboratory study, concentration of dissolved organic carbon (DOC) in effluent from anaerobic filter fluctuated with daily variation of flow when average hydraulic retention time (HRT) was below 10 h. However, daily mean values of DOC under the varied flow was almost the same as those under constant flow within the same daily mean HRT. Aerobic filter linked to anaerobic filter reduced the concentration of DOC satisfactorily though the concentration in anaerobic filter increased under short HRT. In field study, percent removal of organic carbon by anaerobic filter was considerably smaller (20-30%) than that in laboratory study (90-95%) both at HRT of 20 h though it was improved up to 60-80% by aerobic filter. Effects of peaking factor of flow on the variation of DOC were evaluated by mathematical analysis. It seemed that the peaking factor hardly affected daily mean values of DOC within the same daily mean HRT though maximum values of DOC increased with the increase of peaking factor.
Thermophilic Aerobic Digestion–A Reliable and Effective Process for Sludge Treatment at Small Works
Authors: Murray K. C. , Tong A. , Bruce A. M.
Published: May 2018

In January 1987 a thermophilic aerobic digestion (TAD) plant was installed at Haltwhistle STW to assess its suitability for sludge treatment at small isolated sewage works. The TAD plant and details of its operation and performance are described in relation to the particular problems associated with sludge treatment at small works. Experience at Haltwhistle has shown that TAD is an effective method of sludge stabilisation and disinfection. Permanent TAD plants are now being installed at two sites in the Northumbrian Water Authority area.
Sludge Handling and Disposal at Small Wastewater Treatment Plants in Norway
Authors: Paulsrud Bjarne
Published: May 2018

Most sludges from small wastewater treatment plants in Norway are either dumped in sanitary landfills or utilized on agricultural land. Norwegian guidelines for wastewater sludge disposal recommend all sludges to be dewatered prior to disposal. For agricultural use the sludge should be stabilized at the treatment plant or stored in piles for at least six months before utilization.

Almost every plant has possibilities for sludge gravity thickening, and polymer addition is becoming quite popular for that process. Dewatering of sludge will often take place at a larger treatment plant, or In areas with no such plants, dewatering lagoons and mobile dewatering trucks are employed. For sludge stabilization, aerobic digestion is the predominant method.
Performance Stability of Small Biological Chemical Treatment Plants
Authors: Storhaug R.
Published: May 2018

Biological and chemical treatment plants constitute a main portion of the overall number of treatment plants in Norway. The biological and chemical plants are divided into three process groups, simultaneous precipitation and activated sludge, combined precipitation and rotating biological contactors (RBC) and post precipitation and activated sludge. Aluminium sulphate or ferric chloride are the commonly used flocculants in the chemical precipitation process. Effluent data from 174 Norwegian biological chemical treatment plants are evaluated. Compared to the effluent standards for each process group, post precipitation shows the best performance. On an average these plants have the lowest actual utilization of the design capacity. The most important factors that cause the treatment plants not to meet the effluent standards are, poor quality of the sewer system, improper design of the plant and organizational problems. Satisfactory separation of particles, flow equalization and proper operational management, are the basic demands to achieve low effluent concentrations for tot-P and BOD7.
Urban Drainage Strategies for Small Communities in Developing Countries
Authors: Grottker Matthias , Khelil Amar
Published: May 2018

In this paper, the interactions of small waste water treatment plants within an urban drainage system are pointed out. Especially in developing countries, the characteristics of catchment areas differ very much from the ones in industrialized countries. Consequently, the plants have to be adapted to the local conditions of drainage, climate and location. Finally, an urban drainage strategy will give an idea how to sanitize drainage systems.
An Innovative Technology for Upgrading Nutrient Removal Activated Sludge Plants
Authors: Wanner Jiří , Kos Miroslav , Grau Petr
Published: May 2018

A brief survey of activated sludge systems for nutrient removal from wastewaters iss given and their characteristic features are discussed. Four modifications of the nutrient removal activated sludge process were tested in pilot-plant units with a wastewater from the town of Pilsen. The re-aeration of the returned sludge proved to be advantageous for achieving high nitrogen removal. For the design of a new wastewater treatment plant for the town of Pilsen, the activated sludge process, consisting of the anaerobic-anoxic-oxic sequence with the reaeration of the returned sludge, was used. The newly designed technological line of the so-called R-AN-D-N Process is very flexible thanks to the wastewater inlet in both the anaerobic and the anoxic zone and to the possibility of introducing the internal recycle in either the anoxic or the anaerobic zone.
Pre-Precipitation Facilitates Nitrogen Removal without Tank Expansion
Authors: Karlsson Ingemar , Smith Gunnar
Published: May 2018

Chemically coagulated sewage water gives an effluent low in both suspended matter and organics. To use chemical precipitation as the first step in waste water treatment improves nitrification in the following biological stage. The precipitated sludge contains 75% of the organic matter in the sewage and can by hydrolysis be converted to readily degradable organic matter, which presents a valuable carbon source for the denitrification process. This paper will review experiences from full-scale applications as well as pilot-plant and laboratory studies.
Steps in Planning the Expansion of the Large Sewage Treatment Plant at Buchenhofen, Operated by the Wupper Watershed Management Association
Authors: Londong Jörg , Zander Stefan
Published: May 2018

Sewage from 700,000 PE, roughly half of which is discharged by industry, is treated at the Buchenhofen plant operated by the WWMA, using a conventional, activated-sludge process without specific nutrient elimination.

A draft management plan has been prepared for the receiving stream of the treatment plant, the Lower Wupper. The chief forms of use for the waters are fixed in binding agreements. The use entailing the strictest limiting values is recreational fishing, which demands surface water quality class II.

Very substantial demands, which must be regarded as at least equivalent to state-of-the-art technology, are imposed on the Buchenhofen facility.

The Institut für Siedlungswasserbau, Wassergütewirtschaft und Abfalltechnik at the University of Stuttgart was commissioned to formulate realistic purification objectives for the treatment plant and to prepare expansion concepts.

At Buchenhofen, the single-stage activated sludge process with nitrification and preliminary de-nitrification has proved to be the most effective method for eliminating nitrogen while simultaneous precipitation followed by flocculation-filtration is the best process for eliminating phosphorus.

For purely scientific reasons, however, the extreme demands in terms of ammonium and nitrite rule out expansion of a treatment plant of this size. The proposed designs therefore require validation through commercial-scale testing.

Only after a 6- to 12-month test series has been evaluated will a draft design be prepared for approval, ultimately enabling the plant to be expanded and to fulfil the management planning objective of achieving surface water quality class II in the Wupper.
Performance Increase of Papermill Waste Water Treatment Plants by a High-Capacity Trickling Filter Inserted as First Biological Stage
Authors: Möbius C. H. , Demel I. , Huster R.
Published: May 2018

In many cases, it will be advisable to enhance operational safety and increase degradation performance of existing activated sludge plants by inserting a high-capacity trickling filter with plastic media. Easily degradable carbohydrates are largely decomposed in the trickling filter at low energy requirements. This allows the subsequent activated sludge stage to be set to reduced BOD sludge load levels which are required for efficient COD elimination, because the volume load has been reduced and a higher biomass concentration can be obtained at a lower sludge volume index. In the light of several years' pilot testing of numerous different effluents, and of knowledge derived from observations of several industrial plants in the paper sector, precise rating directives can now be given for plants of this type. It has proven advantageous to discharge the trickling filter effluent directly into the activated sludge plant without intermediate clarification. The effluent temperature, which frequently exceeds 35°C, is reduced by up to 10°C in the trickling filter. This improves the conditions prevailing in the activated sludge plant, thus permitting limit values for the discharge of effluents into surface waters to be adhered to.
Dosage Control for a Higher Efficiency of the Separation Process
Authors: Schrank Guenter
Published: May 2018

Apart from the biological decomposition of dissolved organic components, the wastewater treatment process is mainly a solid-liquid separation process. Solids: Inorganic and organic undissolved matter are separated from the liquid stream in several process steps. To ensure a good separation efficiency many different chemicals are added to the solid-liquid dispersion. Among other things, the variety of flocculants makes it very difficult to control the polymer dosage. However, weak flocculant dosage control can strongly affect the efficiency of the separation plant or equipment, and the predicted effectiveness of this process step cannot be achieved. To counter this difficulty, a control system working in most applications has been developed. This system works almost independently of the separation process or the type of flocculant used. The system and its function will be described using three different field installations in different applications as examples. These are a sedimentation basin, a flotation cell and a filtration plant. Depending on the function of operation in the past as well as on the size of the plant, the payback period will most certainly cover less than half a year.
Upgrading Existing Activated Sludge Treatment Plants with Fine Pore Aeration Systems
Authors: Stenstrom Michael K.
Published: May 2018

Over the past ten years aeration systems development in the United States has centered around fine pore diffuser upgrades to existing activated sludge plants. A variety of older aeration systems have been replaced with new diffuser systems which include full floor coverage systems, composed of ceramic or plastic discs, ceramic and plastic tubes, and membrane tubes or discs. This manuscript reports on aeration system upgrades at six different full scale treatment plants. Seven different devices were evaluated using the off-gas analysis technique. Diffuser cleaning methods were also evaluated. Results are presented which show the economic incentives for upgrading and the increased plant capacity which resulted from increased aeration efficiency. It was found that the effects of process operation, such as step feed, F/M, MLSS concentration, mean cell retention time and air flux had a major impact on transfer efficiency. The effects of diffuser fouling and cleaning methods are presented.