bluuebunny/crossref_metadata_2025 huggingface dataset:
In Situ Examination of Effects of Pressure Differential on Compressible Cake Filtration
Authors: Bierck B. R. , Dick R. I.
Published: May 2018

A synchrotron X-ray absorbance technique was used to monitor suspended solids concentration changes in compressible filter cakes formed at different constant pressure differentials. Results for a kaolin slurry and an activated sludge manifested the markedly higher compressibility of the latter sludge. A model developed to describe effects of pressure differential on filtrate production behavior of an ideal compressible slurry indicated that the kaolin slurry behaved as such. However, the activated sludge was not ideal because changes in pressure differential did not cause the idealized change in filtrate production rate. A thin skin of activated sludge solids at the filter medium accounted for the non-ideal compressive behavior. Porewater pressure data acquired 0.86 mm above the filter medium during activated sludge filtration provided evidence of skin formation and its effect - virtually the total pressure drop occurred within this 0.86 mm region throughout cake formation (after which shrinkage began). Hence, significant effective stresses required to consolidate the sludge cake did not develop in most of the cake until cake formation was complete and shrinkage began.
Characteristics of Sewage Sludge Affecting Dewatering by Belt Press Filter
Authors: Hashimoto M. , Hiraoka M.
Published: May 2018

Dewatering characteristics of sewage sludge were determined by conditioning the sludge with the most effective cationic polyelectrolyte studied, and dewatering using a belt press filter. The characteristics of sludges (16 mixed, and 8 anaerobically digested) were measured for 33 factors affecting dewaterability. The correlations of sludge factors with sludge dewaterability were investigated.

The results revealed the following. A factor affecting the gravitational filterability of conditioned sludge is the suspended solids concentration of raw sludge. A factor affecting the moisture content of dewatered sludge cake is viscosity of the sludge adjusted to 4.0 % of suspended solids concentration. Factors affecting the viscosity are the intrinsic viscosity of alkaline extracts, the ratio of (VSS-Fiber)/SS : Ash/SS : Fiber/SS, and the charge density of sludge particles. A factor affecting the extension degree of dewatered sludge cake is the charge density of sludge particles. Factors affecting the amount of residual solids on the filter cloths are the charge density of sludge particles and the fibrous substances content of sludge. As for polyelectrolytes, a highly cationized polyelectrolyte is effective to lower the moisture content, the extension degree and the amount of residual solids on filter cloths. And a factor affecting the required dosage of a polyelectrolyte is anionic substances content in the liquid of raw sludge.
Models of Sewage Sludge Conditioning
Authors: Lotito V. , Mininni G. , Spinosa L.
Published: May 2018

Models of sewage sludge conditioning are needed in order to assess the type of chemicals to be preferred and the optimal dosages. Laboratory and pilot tests were carried out with organic and inorganic chemicals for determining their influence on sludge parameters and equipment performance. A new parameter, named “Specific Resistance to Centrifugation”, for evaluating sludge centrifugability was developed. The pilot tests confirmed that satisfactory solids recoveries can be obtained when the value of this parameter is of 20-30 s. A correlation was also found between the “Specific Resistance to Centrifugation” and dosage, molecular weight and charge density of polyelectrolytes. Other correlations were determined for Specific Resistance to Filtration and compressibility coefficient. In conditioning by inorganic chemicals it was found that ferric chloride mainly influences the specific resistance, while lime the compressibility coefficient. Due to some discrepancies between the classical theory of filtration and actual results of pilot tests, a new parameter called “Average Specific Resistance to Filtration” was proposed. As far as beltpress operation is concerned, a laboratory test was defined thus allowing the drainage phase and the compression one to be simulated. The final cake concentration can be also predicted and it was found a good agreement with the actual experimental values.
Solar Energy for Sludge Drying in Alexandria Metropolitan Area: Case Study in Egypt
Authors: Hossam A. A. , Saad S. G. , Mitwally H. H. , Saad L. M. , Noufal L.
Published: May 2018

An experimental study was conducted to assess the drainability of sludge generated by different treatment processes, and to assess a pilot solar heated sand drying bed in comparison with the regular beds located in the pilot plant at Alexandria Eastern Sewage Treatment Plant. It was found that the climatic conditions were generally favourable for dewatering sludge on sand drying beds except when there was heavy rainfall during the wet season which prolonged the drying time. The solar air heated drying beds saved about 35% of the bed area as compared with conventional sand drying beds, and the drying time was cut from 18 days to 8 days. It was also found that the solar air heated beds were less expensive than the conventional open sand beds.
Melting System for Sewage Sludge
Authors: Oku S. , Kasai T. , Hiraoka M. , Takeda N.
Published: May 2018

In Japan, melting plants for sewage sludge are attracting great attention for their capability to produce molten slag and the possibility for their effective application. Several plants have already commenced operation. The authors have developed a new sewage sludge melting system, a melting after carbonizing sludge (MACS) system, using a swirling flow melting furnace. In 1987 a 50-t/d-scale demonstration furnace was installed, and since then the technique has been demonstrated. Heavy oil required to melt sludge in the plant is about 50 L/t-cake and the power about 83 kWh/t-cake.
Open-Pore Sintered Glass as a High-Efficiency Support Medium in Bioreactors: New Results and Long-Term Experiences Achieved in High-Rate Anaerobic Digestion
Authors: Breitenbücher K. , Siegl M. , Knüpfer A. , Radke M.
Published: May 2018

An open-pore sintered glass material (SIRAN) was developed for the immobilization of slow growing microorganisms. Due to the excellent properties of the inert carrier, e.g. porosity, pore size distribution, surface area, which can be adjusted individually to the applications, good system efficiencies are possible. Thus in the field of anaerobic digestion significant high COD removal rates are achievable.

The open-pore structure of the carrier offers surface areas up to 90.000 m2/m3 to be colonized by active biomass. Compared to conventional support media, the use of open-pore carriers results in high start-up and steady-state performance at high process stability.

The fixed bed loop reactor guarantees economical process solutions if open-pore sintered glass raschig rings are applied. Granules and beads have been proven in fluidized bed reactor systems, maintaining COD loading rates of 206 kg/m3 · d by treating evaporator condensates from pulp industry.

The paper describes main characteristics of the carrier, treatability studies with pilot plants, scale-up and experiences with full-scale installations at production site using SIRAN carriers.
Wastewater Treatment by Attached-Growth Microorganisms on a Geotextile Support
Authors: Valentis G. , Lesavre J.
Published: May 2018

A geotextile support is used for wastewater treatment by aerobic, attached-growth microorganisms. The relative process which is developed in this paper, works like a submerged bed. The geotextile medium makes easier the installation and operation of treatment plants in comparison with granular biofilters. The colonization of the selected medium takes place in a pilot plant of 0.75 m3. The process does not need a secondary clarifier. The reactor works in cycles varying between 2 and 12 days interrupted by backwashing and air scour. The maximum efficiency, measured as inlet volumetric loading, is about 7 kg COD/m3.day . Under these conditions, a cycle of 3–4 days assures an effluent quality characterized as level “e” by French standards (TSS 30 mg/l, BOD5 30 mg/l, COD 90 mg/l). Two phases can be distinguished during the operation of the system : In phase A, the biomass and the TSS are held on the geotextile. Thus we avoid the use of a secondary settlement tank. The phase A stands for a working cycle. When backwashing does not take place, the operation of the biological reactor carries on in phase B where, by a saturation effect, the geotextile cannot hold any more biomass. In this way, an abrupt increase of the TSS is observed in the effluent. During phase A, the particulate loading of the treated water depends, at the same time, on biofilm detachment, which is a function of the water flowrate, and of the growth of the suspended bacteria. The efficiency of the treatment is controlled by the TSS at the outlet of the reactor.
Treatment of Leather and Fur Wastewater by a Rotating Biological Contactor
Authors: Zao-yan Yang , Zhen-san Fan
Published: May 2018

The operation of a leather and fur wastewater treatment plant has been stable for 8 years. The volumetric loading was 85 to 110 l/m2.d, and the BOD loading and COD loading of the influent to the rotating biological contactor (RBC) were 15 to 20 g/m2.d and 50 to 65 g/m2.d respectively. Analyses have shown that the BOD5, COD, suspended solids (SS), S2−, and Cr3+ removals were 87.8, 77.4, 84.8, 93.6, and 81.0%, respectively.

Several factors were considered in the design and performance of this leather and fur wastewater treatment plant. The pretreatment stage has a great influence on the operation of the RBC. The performance of the pre-aeration tank and primary clarifier regarding both BOD and COD removal approached 50%, therefore the organic loading of the RBC was reduced. However, shock flows of limewash waste from the workshop decreased the efficiency of the RBC. The high pH in the liquid film on the discs caused CaCO3 to precipitate and settle as scale on the surfaces of the discs. As the pH increased, NH3 stripping in the liquid film increased, and care had to be taken regarding proper room ventilation when the wastewater pH was high. Due to the high concentrations of organic matter and poorly biodegradable matter in the leather and fur wastewater, the rotational speed of the RBC must be increased compared with municipal wastewater treatment to ensure adequate aeration and to prevent blockages. In practice, the RBC linear velocities were between 25 to 30 m/min.
Industrial-Scale Applications of Fixed Biomass on the Mediterranean Seaboard. Design, Operating Results
Authors: Gilles P.
Published: May 2018

The technology that consists of treating sewage on submerged granular filters is now far beyond the stages of research and testing on pilot units. Fifteen or so full-scale facilities are in operation in France using, as a biological treatment stage, the fixed biomass technology as realised by the Biocarbone process, particularly for the treatment of sewage from built-up areas along the seaboard. These are cases where the advantages of this technique can be put to decisive use.

The Mediterranean seaboard is an ideal site for this technology. Cases in point are the waterworks of Sanary Bandol (pop.60,000) and Perpignan (pop.160,000), that have been in operation for two years and one year respectively. Waterworks in Monaco (pop.100,000) and Antibes (pop.170,000) will be commissioned in 1989 using the same technology.

Results obtained during intensive controls show that the fixed biomass, designed with a suitable industrial technology, is capable of producing in routine conditions, on full industrial-scale plant, a very good quality effluent. (COD : 70 mg/l, TSS : 20 mg/l) for pollutant loads in the order of 8 kg COD/m3 day. It enables the fluctuations in the daily flow-rate and pollution load of the influent to be absorbed.

The units currently being built are examples of what can be done in compact roofed facilities incorporating a fixed biomass treatment stage, with the objective of reaching a no-nuisance level.
Biologically Intensified Filtration (Dual-Media Dry Bed Filter) for Advanced Waste Water Treatment
Authors: Kraft A. , Seyfried C. F.
Published: May 2018

In this paper, the dry filtration process is described. In the experimental part, the results of tests on the semi-technical scale are presented. Additionally to the determination of material parameters and characteristics of different filter materials, their back wash characteristics are examined. The biofilm on the filter material desired in wastewater technology causes a reduction of 20% of the necessary back wash velocity. On the other hand, mixing phenomena in dual-media filters were increasingly observed. The tests concerning nitrification performance showed that the dry filtration system is an extraordinarily efficient process. Volumetric degradation performances of up to 1.5 kg NH4-Nel/m3d were achieved. Volumetric load and filter velocity turned out to be decisive measurement parameters.

In the second part of this paper a dry bed filter plant on a large- technical scale of a municipal wastewater treatment plant is presented. The plant is described, operating results are discussed and operating problems are discussed
Operational Behaviour of an Industrial Fixed Bed Reactor for Biomethanation of Alcohol Slops from Different Crops
Authors: Weiland P. , Thomsen H.
Published: May 2018

Distillery slops from a multicrop ethanol plant are difficult to treat anaerobically, because the composition and load changes throughout the year due to processing of different sugar-and starch-containing crops. For achieving high COD removal efficiencies and good process stabilities at medium strength loading rates, a two-phase anaerobic treatment process with a fixed-bed reactor for biomethanation was developed and tested in pilot-scale. On the basis of these experiments a full-scale unit with 1,800 m3 reactor volume was erected, which has been in operation for more than one year.

The fixed-bed reactor is operated with COD loads up to 10 kg COD/m3d at hydraulic retention times of about 5 days. A variety of highly concentrated slops can be treated successfully with COD removals from 85 % to over 90 %. The fixed-bed reactor withstood sudden changes in wastewater strength and composition and is able to handle hydraulic overloads. Operational data from the industrial unit show that the performance and reliability of the fixed-bed reactor is much better than a conventional contact system, which was operated in a parallel run in the same scale. The results show, that the application of fixed-bed reactors can be recommended for a wide variety of high-strength wastewaters with low suspended solids contents.
Pilot-Scale Experiments on Anaerobic Treatment of Wastewater from a Fish Processing Plant
Authors: Balslev-Olesen P. , Lynggaard-Jensen A. , Nickelsen Claus
Published: May 2018

From November 1985 to May 1988, experiments with anaerobic treatment of wastewater from a fish cannery were carried out at the Water Quality Institute (WQI) at Aarhus, Denmark. An anaerobic fixed filter (AF) reactor and an anaerobic fluidized bed (AFB) reactor were used for the pilot-scale experiments. The reactors were monitored and controlled by a microcomputer.

The aim of the experiments was to determine the biogas yield from COD reduction and to show the efficiency of the reactor as a function of the following operation parameters: Volumetric organic load, 3–15 kg COD/(m3·day); temperature, 30–35°C, pH (control of); salinity, 1–4%.

Operational data are presented, including start-up after stand-by periods of varying lengths, from one day to three months. Both reactors showed excellent capability of handling load variations and were capable of quick start-up and high efficiency even after long stand-by periods.
Anaerobic-Aerobic Treatment of Municipal Wastewaters with Full-Scale Upflow Anaerobic Sludge Blanket and Attached Biofilm Reactors
Authors: Collivignarelli C. , Urbini G. , Farneti A. , Bassetti A. , Barbaresi U.
Published: May 2018

The results of pilot experiments on municipal wastewater treatment using advanced processes are described. The most important aims of this research were to achieve reductions in energy consumption, environmental impact, quantity of stabilized sludge produced, and area necessary for plant construction. The pilot plant, which was constructed in the environs of the Senigallia (AN, Italy) municipal wastewater treatment plant, had a capacity of 500 to 2500 population equivalents (p.e.). In the most attractive system, municipal wastewaters with a low organic concentration were first treated in an upflow anaerobic sludge blanket (UASB) bioreactor with a capacity of 336 m3. Part of the effluent from this process was then conveyed to an anoxic biological fluidized bed (with a volume of 8 m3 filled with 3 m3 of quartzite sand) for pre-denitrification, and then to an aerobic fixed bed (with random plastic media and a volume of 8m3) for nitrification. It was also possible to treat the municipal wastewaters using the anaerobic fluidized bed directly, after microscreening or primary sedimentation. The research undertaken was intended to verify the reliability of these processes at ambient temperatures and with variable wastewater concentrations. The preliminary results obtained for COD, BOD, and N removal from municipal wastewaters indicate that this system is quite an attractive treatment alternative, mainly due to its low sludge production and energy consumption. These results will enable accurate design criteria to be identified for the construction of more economic treatment plants on a larger scale.
Sewage Treatment for Small Local Authorities: Choice of Process and Recent Trends in France
Authors: Racault Y. , Vachon A.
Published: May 2018

France has a large number of small rural waste treatment plants. A fairly wide range of technologies suitable for small local authorities has been developed in recent years. The choice of process is now based on a detailed analysis of the limitations imposed by local conditions, with particular regard to those involving the quality objectives for the receiving environment. The main processes used are presented, together with the design basis generally applied.

An overview is presented of the situation of France's small treatment plants, through an analysis of a sample of 976 plants with a capacity of less than 2000 inhabitant-equivalents in 11 mainly rural departments covering 13% of France surface area. The distribution of the processes used and the evolution of the choices adopted are analyzed with regard to the size of the plants. The activated sludge process, widely used in all size classes ten years ago, has been gradually replaced by extensive processes, essentially where the capacity is less than 800 inhabitant-equivalents. In some departments, local practices have a great influence over the choice of process.
Dewatering of Sludge by Natural Methods
Authors: Marklund S.
Published: May 2018

Drying fron a free water surface and from a waste activated sludge was studied In three separate experimental arrangements. Evaporation in a closed chamber with a surface area of 1.0 m2 was studied with temperatures between 20 and 60°C and air flows between 75 and 300 m3/hour. The rate of evaporation varied between 351 and 746 gram/m2 hour. The efficiency varied between 11 and 20%. To increase the efficiency the air-liquid area has to be enlarged.

Evaporation from two pilot sludge drying beds was studied in an open air test lasting four months. One similar bed was tested in a controlled environment. The results showed that above a critical moisture content between 600 and 1100% evaporation from sludge equals the rate of evaporation from a free water surface. Below the critical moisture level the rate decreases rapidly.

Further work should be directed towards full-scale tests with covered drying beds. Special attention should be drawn to methods to improve the drying rate during the falling rate period, to two phase drying and to the evaluation of a combined dewatering system with sludge freeze drying in winter season and sludge drying in summer season.
Raising the Standard of Operation of Small Sewage Works
Authors: Dakers J. L. , Cockburn A. G.
Published: May 2018

Thames Water operates about 400 sewage works in the catchment area of the River Thames, over half of these serve populations of less than 2000. These small works are mainly biological filter works but also include oxidation ditches and reed beds. Most of these works discharge to the headwaters of salmonid rivers which are used as drinking water sources and therefore have to meet high standards including in many cases full nitrification and low suspended solids.

The paper describes the consent standards set for the works. Currently a number of small works do not meet these standards so Thames Water has committed itself to having all works operating within standards by 1992.

There are a number of reasons for failure which include, overloading due to increase in population and water use, trade effluent discharges, and operational problems. Small works may also fail to meet their standards because they are unmanned apart from infrequent maintenance visits, and thus any plant failure may go unnoticed for some days.

Thames Water is adopting a two fold strategy to overcome these problems. Firstly, so that operational problems may be identified quickly a simple cost effective system of automation and telemetry is being installed and secondly, to overcome operational and facility deficiencies, a Project Management team has been set up to identify the causes of failure, to prioritise remedial work, to recommend alternative operational strategies, if appropriate, to design and build extensions or new works if appropriate, and, if remedial works cannot be built quickly enough, to install temporary plant to ensure compliance with effluent standards.
Upgrading for Biological Nitrogen Removal – Some Full-Scale Experiences from Sweden
Authors: Andersson Bengt , Rosén Björn
Published: May 2018

Nitrogen removal is now required by the Swedish parliament. The new requirements will be valid before 1995 and in some cases before 1992. A comprehensive development program, mostly in full scale at about 35 municipal sewage treatment plants, has been started to meet the new demands. In order to co-ordinate all activities, a National Nitrogen Project with representatives from authorities and municipalities has been formed.

The general ambition is to meet the demand by process development, using existing volumes rather than to invest in civil works. A Swedish concept has appeared, which in most cases has served as a guideline for the development program. The basic principles are to decrease the load on the biological process by pre-precipitation, to utilize the remaining organic content in the wastewater in a pre-denitrification system, to increase the active biomass in the biological system and to use a two-sludge system with post-denitrification.

In this paper, some experiences from the activities in Sweden are discussed and exemplified with results mainly from Falkenberg, Malmö and Norrköping. The treatment plant in Falkenberg was the first to introduce biological nitrogen removal in Sweden. A pre-denitrification system has been in operation since May 1983 with good results. Comprehensive full-scale and pilot tests are in operation at the Sjölunda and Klagshamn sewage treatment plants in Malmö. Special interests have been paid to studies on different applications of fixed film technology. The plant in Norrköping is operated with pre-precipitation followed by combined pre- and post-denitrification.
Ultraviolet Disinfection in Municipal Wastewater Treatment Plants
Authors: Maarschalkerweerd Jan , Murphy Rory , Sakamoto Gail
Published: May 2018

Pilot and full-scale studies of UV disinfection of wastewater have demonstrated that the process could consistently meet an effluent fecal coliform standard of 200/100 mL or less, depending on suspended solids and UV transmission. Since 1984 over three hundred systems have been installed at municipal wastewater treatment plants in North America. The majority of these are in treatment plants which have been using chlorination. The UV systems have been retrofitted into the existing chlorine contact tanks or existing channels. The capital costs of retrofitting compare favourably to the costs of upgrading chlorination systems, especially when de-chlorination equipment is required. As experience is gained in the operation of these UV systems, their performance has been monitored for their disinfection efficiency and cost of operation. Several installations are examined and their performance and costs analyzed. The evidence to date supports the premise that UV disinfection can meet demands for reliable effluent disinfection in a cost effective manner.
Upgrading Wastewater Treatment by Water Hyacinth in Developing Countries
Authors: Kumar Pradeep , Garde R. J.
Published: May 2018

With increasing stress on existing wastewater treatment systems, it is necessary either to upgrade the treatment unit(s) or install an entirely new treatment plant. Obviously, the upgrading is preferred over the alternative of having a new system. Keeping this in view, in the present project, an attempt has been made to explore the possibility of upgrading existing facultative ponds using water hyacinth. Bench-scale batch studies were designed to compare the performance of hyacinth treatment system with facultative ponds. Investigations were carried out with synthetic wastewater having COD in the range of 32.5-1090 mg/l. The efficiency of COD removal in water hyacinth ponds was 15-20 percent more than the facultative ponds. Based on the results, an empirical model has been proposed for COD removal kinetics. In the second phase of the project a hyacinth pond was continuously operated. BOD, COD, TS, TN, TP, pH, and DO were regularly monitored. However, the DO of the effluent from hyacinth treatment system was considerably reduced. Effluent should be aerated before it is discharged. The results indicate that the existing facultative ponds can be stalked with water hyacinth to improve their performance as well as hyacinth treatment systems can be installed to support the conventional treatment.
Urban Storm-Induced Discharge Impacts: US Environmental Protection Agency Research Program Review
Authors: Field R. , Pitt R. E.
Published: May 2018

Fecal coliform bacteria (and pathogens), high flow rates, sediment, toxic heavy metals and organic pollutants are most commonly associated with urban receiving water problems. Most beneficial uses have been shown to be adversely affected by urban runoff, including shell fish harvesting, fish and aquatic life propagation, drinking water supplies, aesthetics and recreation. Most of the problems occur over long periods of time and are not associated with individual runoff events, making cause and effect relationships difficult to study.

The Storm and Combined Sewer Program of the U.S. Environmental Protection Agency has sponsored several long-term research projects to investigate these problems, along with data reviews to identify urban runoff problems from available information. Current research efforts are stressing sources and controls for toxicants in urban runoff.
Microbial Aspects of Sewage and Sewage Sludge in Dundee, Scotland
Authors: Jefferies C. , Young H. K. , McGregor I.
Published: May 2018

Studies of the populations of coliforms and faecal streptococci in sewage and sewer sediments have been carried out in Dundee. Samples have been obtained and tested by standard methods from five storm and five dry weather flow events. The temporal variation of bacterial populations and concentrations during both types of flow regimes found are discussed in relation to flow rates and other relevant parameters. Average daily variations of bacterial concentrations are proposed for dry weather flows. No consistent pattern of bacterial population variation was found for storm events. No interpretation of the data for sediments was possible.
Long-Term Simulation of Pollutant Loads in Treatment Plant Effluents and Combined Sewer Overflows
Authors: Durchschlag A.
Published: May 2018

As a result of urbanization, the pollutant discharges from sources such as treatment plant effluents and polluted stormwaters are responsible for an unacceptable water quality in the receiving waters.In particular, combined sewer system overflows may produce great damage due to a shock effect. To reduce these combined sewer overflow discharges, the most frequently used method is to build stormwater storage tanks.

During storm water runoff, the hydraulic load of waste water treatment plants increases with additional retention storage. This might decrease the treatment efficiency and thereby decrease the benefit of stormwater storage tanks. The dynamic dependence between transport, storage and treatment is usually not taken into account. This dependence must be accounted for when planning treatment plants and calculating storage capacities in order to minimize the total pollution load to the receiving waters.

A numerical model will be described that enables the BOD discharges to be continuously calculated. The pollutant transport process within the networks and the purification process within the treatment plants are simulated. The results of the simulation illustrate; a statistical balance of the efficiency of stormwater tanks with the treatment plant capacity and to optimize the volume of storm water tanks and the operation of combined sewer systems and treatment plants.
Development, Calibration and Further Data Requirements of the Sewer Flow Quality Model Mosqito
Authors: Payne J. A. , Moys G. D. , Hutchings C. J. , Henderson R. J.
Published: May 2018

MOSQITO is the initial version of a sever flow quality model being developed by Hydraulics Research Ltd and the Water Research Centre as part of the UK River Basin Management programme.

MOSQITO I simulates the time-varying behaviour of suspended solids, biochemical oxygen demand, chemical oxygen demand, ammoniacal nitrogen and hydrogen sulphide on catchment surfaces and in sewer systems. The model produces discharge pollutographs for these determinands which can be used as input to a river water quality model.

MOSQITO consists of four sub-models which represent washoff from catchment surfaces, foul water inflow, pollutant behaviour in pipes and channels, and pollutant behaviour in ancillary structures within drainage systems. These sub-models are linked to the flow simulation model incorporated in the WALLRUS package which is the latest computer implementation of the Wallingford Procedure.

The rationale behind the model, its structure and its operational basis have been discussed elsewhere (Moys and Henderson, 1988) and are therefore described briefly so that emphasis can be placed on the aspects which follow.

Calibration and verification of the model are being carried out using data from a variety of experimental catchments in the UK. These catchments have been selected to exhibit a wide range of characteristics and include separate and combined sewer systems.

Results of the calibration work are presented together with illustrations of the performance of the various sub-models and the overall model.
The Development of Ecotoxicological Criteria in Urban Catchments
Authors: Bascombe A. D. , Ellis J. B. , Revitt D. M. , Shutes R. B. E.
Published: May 2018

Metal uptake and mortality rates are determined for selected body areas of Gammarus pulex under both in-situ stream and laboratory test conditions. Metal equilibrium concentration levels are chieved in soft tissue within 5 to 6 weeks exposure in the field with four-to five-fold increases over background control levels noted for saturation levels in caged organisms at sites subject to sewer discharges. Laboratory bioassays yield short-term LC20 values in the order Pb>Cu>Zn, although there is little difference in metal toxicities over exposure periods of about one week. The controlled toxicity tests demonstrate a substantial short-term toxic enhancement over the in-situ field bioassays.
Evaluation of COD Removal Performance Based on Organic Acid Decomposition in an Anaerobic Fixed Bed Reactor
Authors: Kuroda M. , Sakakibara Y.
Published: May 2018

COD removal performance in an anaerobic fixed bed reactor(AAFBR), which treats soluble organic matter, was investigated theoretically by using a simplified biofilm model. The COD removal rate was assumed to be controlled by the decomposition rates of volatile fatty acids such as acetate, propionate and butyrate. The simplified biofilm model took into consideration the effects of intrabiofilm and interbiofilm substrate diffusion rates on substrate biodegradation rates. The COD removal rates in AAFBR were evaluated for various operating conditions by using known kinetic parameters. The calculated results show that the COD removal rates are not affected by adhered biomass provided that the bio-mass is more than about 4 mg-C/cm2, and vary with temperature, bulk liquid substrate concentrations and the bulk liquid flow rates which are in the range 0.01 ~ 1 m/hr. Relations between allowable COD loading rates and packing diameters were shown schematically for different bulk liquid flow rates.
Treatment of p-Cresol with a Recirculating UASB Reactor Using the Concept of Kinetic Control
Authors: Hwang Ping-Chih , Cheng Sheng-Shung
Published: May 2018

A series of batch Biochemical Methane Potential(BMP) tests and an Upflow Anaerobic Sludge Bed (UASB) bioreactor were conducted to investigate the biodegradability of p-cresol.The inhibition of microbes caused by substrate accumulation due to shock loading, recirculating pump turn-off and thermal shock were also studied. The results showed that the microbial activity was inhibited or even poisoned in the high concentration range(1000mg/L) of p-cresol.

However, the volumetric loading of the reactor could be maintained relatively high at 8.0 kgCOD/m3·day, if the recirculation of effluent was used to maintain the substrate concentration in the reactor within a suitable range. The concept of so-called kinetic control was proved to be a critical strategy for the treatment of the inhibitory substrate. The results of shock loading, recirculation cessation and thermal shock tests all showed that the concentration control in the reactor would be of vital importance for the treatment of inhibitive compounds with biological processes, and the critical concentration of the highest degradation rate could be estimated with a modified Haldane equation derived from the batch BMP data.
Dyeing Wastewater Treatment by Ash–Cinder and Dust/Off Gas
Authors: Li Guolin , Zhao Qingliang
Published: May 2018

Two systems using ash–cinder and dust–offgas to treat textile dyeing wastewater were studied, one being an ash-cinder filtration adsorption system, and the other an integrated system consisting of ash–cinder filtration–adsorption and dust/offgas scrubbing adsorption, in which high-color dyeing wastes were introduced to the scale-removal system of a boiler, resulting in both hydraulic antiscaling and wastewater treatment. Because of the very low cost of wastewater treatment and the saving of antiscaling process, comprehensive treatment and utilization of various wastes was sucessfully realized.
Principles of Modelling
Authors: Beck M. B.
Published: May 2018

The scope for modelling the behaviour of pollutants in the aquatic environment is now immense. In many practical applications there are effectively no computational constraints on what is possible. There is accordingly an increasing need for a set of principles of modelling that in some respects may well be different from those applicable when conceptualisation, the accuracy of the numerical solution scheme, and the inadequacies of an overly simplified model structure, were the issues of the day. Given the availability of increasingly comprehensive software, the user of a model is increasingly likely to be accelerated into a position where the issue of model calibration (identification) is an immediate problem. From the practical point of view of needing to make a decision on the control of a pollutant, the problem of identification may, or may not, be avoided. It is argued that a consistent approach to establishing whether such identification is necessary depends on establishing the significance, or otherwise, of model uncertainty. Identifying the model against field data does not have merely the goal of yielding “best” estimates of the unknown coefficients (parameters) appearing in the given model structure. It may also serve the purpose of identifying and modifying the uncertainty attaching to the model as a description of observed behaviour, which uncertainty will then be propagated forward in any predictions made with the model.
Identification of a Mechanistic Model for the Diurnal Dissolved Oxygen Pattern in Lakes with Discrete Time Series Analysis
Authors: van Straten G. , Kouwenhoven J. P. M.
Published: May 2018

Discrete time data analysis indicates that a first-order autoregressive model with exogenous variables (ARX) is sufficient to describe observed diurnal dissolved oxygen patterns in a lake. It is shown that this model is equivalent to a simple three parameter mechanistic model, augmented with a first-order noise filter. The noise dynamics can be interpreted in terms of natural stochastic parameter variations. Tests with data simulated with the identified stochastic model structure reveal that the usual least squares (LSQ) fitting of the mechanistic model without the noise term leads to biased parameter estimates. Therefore, with the actually measured data, ARX parameter estimates are probably preferable to LSQ estimates, even though the output error is larger. In the true system slow parameter variations probably also occur which are not covered by the simple model.
TETrans: A User-Friendly, Functional Model of Solute Transport
Authors: Corwin D. L. , Waggoner B. L.
Published: May 2018

A beta-test version of TETrans (acronym for Trace Element Transport) is presented which models the movement of inorganic solutes through the vadose zone under transient-state conditions. TETrans is a complete software package consisting of an interactive tutorial, user's guide and applications software. Both IBM-compatible and Macintosh versions are available to users. TETrans is specifically designed to be intuitive in its operation and require only readily available input parameters in order to enhance its utility as a real-world applications tool for transport modeling.

The transport model utilizes a mass-balance approach to determine solute concentration distributions over time and solute-loading to the groundwater. Several modeling options are available for simulating such transport-influencing factors as plant-water uptake, hydraulic bypass and adsorption. In the Macintosh version, TETrans makes full use of the Macintosh interface to enhance the user-friendliness of the model. All functions are available from pull-down menus, and simulation results are displayed in text and graphic windows.

Test data are shown which include a comparison of simulated and measured results for the movement of chloride through a soil lysimeter column over a 900-day study period. Excellent agreement is found when a single parameter for bypass is used. TETrans is distinguished from other transport models in the straightforward manner in which it handles the exacerbating problem of hydraulic bypass. The hydraulic bypass parameter, termed the mobility coefficient, is determined from simple chemical analysis of chloride in the soil solution through the soil profile following the application of a plug of chloride in the irrigation water. The mobility coefficient reflects the volume of soil water which is not subject to piston displacement
Development of a Personal Computer-Based System to Support Basin-Wide Management of Water Quality in Lakes and Rivers
Authors: Okada M. , Chihara K. , Kawashima H. , Suzuki M.
Published: May 2018

A personal computer based easy of access software to help water authorities for setting basin-wide comprehensive management program on water quality control was developed. Users are requested to input geological and administrative mapping of pollution sources and related socioeconomic information such as unit loading, activities, wastewater treatment efficiencies supported by the advisory system. Then the system enables to estimate pollution loads from the basin including both point and non-point sources and to predict quality of the water bodies, i.e. river systems and lakes, based on the present load and expected loads after alternative management plans are implemented. The C-language was used for system development. Lake Sagami-ko and its tributary, Katsura River, was used as a model basin for system development and validation.
Development of a Control Strategy to Reduce Combined Sewerage Overflows: The Case of Bremen – Left of the Weser
Authors: Khelil Amar , Schneider Stefan
Published: May 2018

In recent years, the population and authorities in West Germany have become very concerned with water pollution. In this respect, combined sewage discharges have been pointed out as a major source. Various measures can be considered, which can be ordered into three categories: a redefinition of the objectives of the Urban Drainage System (UDS), the reshaping of the UDS (e.g. extension of the storage capacity) or the modification of its operation. Among the latter measures, Real-Time Control (RTC) constitutes the main option. It aims at a better exploitation of the existing storage potential. As the city of Bremen (Germany) decided, several years ago, to renew the on-line survey and monitoring system of its UDS, the determination of on-line strategies to operate the pumps came to the fore. Methods and tools to investigate the possibility to reduce the pollution loads through improved control strategies have been developed. Some results are presented.
Cormix: An Expert System for Mixing Zone Analysis
Authors: Jirka G. H. , Doneker R. L. , Barnwell T. O.
Published: May 2018

United States water quality policy includes the concept of a mixing zone, a limited area where initial dilution of a discharge occurs. Current practice in mixing zone analysis is plagued by a number of problems --mixing zone definitions vary widely; there is a diversity of discharge and site conditions; existing models focus on near-field mixing while legal definitions extend to greater distances; and there are a large number of permitting applications needing review. The Cornell Mixing Zone Expert System (CORMIX) is a series of software elements for analysis and design of submerged buoyant or nonbuoyant discharges containing conventional or toxic pollutants into stratified or unstratified waters, with emphasis on the geometry and dilution characteristics of the initial mixing zone. Subsystem CORMIX1 deals with single port discharges, CORMIX2 addresses multiport diffusers, and subsystem CORMIX3 analyzes surface discharges. The software is implemented on microcomputers using the MS-DOS operating system. It contains two key elements -- 1) a rigorous flow classification scheme that analyzes the near-field behavior of a discharge and 2), a collection of predictive elements for each discharge scenario. This paper describes the development philosophy underlining CORMIX, the capabilities of the three subsystems, and describes the procedure for obtaining the software.
Rule-Based Expert Systems in the Control of Wastewater Treatment Systems
Authors: Laukkanen Risto , Pursiainen Jorma
Published: May 2018

Rule-based expert systems create a low-cost solution to master all empirical knowledge available in existing wastewater treatment plants. Currently there exists no universal model for processes of biological wastewater treatment, while existing data records and human experience form, however, a valuable knowledge base for an enhanced understanding of process interrelations. In spite of the natural ambiguity of human reasoning and expression, final control policy can, nevertheless, be efficiently translated into on-line automation.
The Integrated Model Evaluation System (IMES): A Database for Evaluation of Exposure Assessment Models
Authors: Schreiner S. P. , Gaughan M. , Schultz H. L. , Walentowicz R.
Published: May 2018

The USEPA Office of Health and Environmental Assessment develops methodologies for conducting exposure and risk assessments. Protocols appropriate for specific analyses have been developed to aid in the selection of an exposure assessment model and to assess the validation and uncertainties associated with models used for toxic chemical exposure assessments in surface water, groundwater, and air. A software package has been developed to provide users with a quick and intuitive tool to access information for selected models and applications based on these protocols. The Integrated Model Evaluation System (IMES) is composed of three modules: 1) Selection, query systems for selecting a model based on technical criteria (currently for surface water, non-point source, and groundwater models); 2) Validation, a database containing validation and other information on over 50 models in various media; and 3) Uncertainty, a database demonstrating uncertainty simulations for several surface water models applied to exposure assessments of several chemicals. The selection modules are linked to the uncertainty and validation modules to access information for chosen models. The PC-based software system employs pull-down menus, help screens, and graphics to display its information.
Modelling and Experiments on Fluidized-Bed Biofilm Reactors
Authors: Bignami L. , Eramo B. , Gavasci R. , Ramadori R. , Rolle E.
Published: May 2018

Over the last few years considerable attention has been devoted to biological fluidized-bed technology which seems to be potentially more advantageous than both dispersed biomass processes and fixed bed systems. An obstacle to the spreading of this technology is the lack of rigorous criteria in designing reactors, due to the poor knowledge of interconnections of fluid-dynamic aspects with kinetic ones.

This paper reviews the rational basis for reactor design and reports on the experimental tests carried out in order to gain a better understanding in the areas of biofilm modelling and fluidization mechanics.

In particular a biofilm model, in the general case of the Michaelis and Menten equation, was developed and its validity was verified utilizing experimental data obtained in nitrifying batch tests. As to fluidization mechanics the experimental work confirms the Wen and Yu(1966) approach to correlate the bed porosity with the superficial liquid velocity.