bluuebunny/crossref_metadata_2025 huggingface dataset:
Nutrient Removal: On-Line Measurements and Control Strategies
Authors: Thornberg Dines E. , Nielsen Marinus K. , Andersen Klaus L.
Published: May 2018

New control strategy principles with respect to nitrogen and phosphorus removal in activated sludge plants are described. The principles include control of phase length and oxygen set point based on criteria functions and continuous on-line measurements of ammonium, nitrate, phosphate and pH. Five case studies are stated which describe improvements in biological nitrogen and phosphorus removal and in chemical phosphorus removal at activated sludge plants ranging from 5000 to 220000 population equivalents (0.25 to 11 MGD). The improvements due to the new strategies are basically a reduction of nutrients in the effluent and a reduction in the amount of chemicals and electricity consumed.
CSO-MASTERPLAN FOR THE CITY OF WALDENBURG, GERMANY
Authors: Michelbach S. , Weiß G. , Brombach H.
Published: May 2018

The small town of Waldenburg in South Germany planned to continue the implementation of stormwater treatment. The CSO-Masterplan dated from the year 1976. Meanwhile, new guidelines were issued and new technologies became available, like mathematical sewer models. Since the ecological impact of stormwater treatment is today much more accounted for, it was decided to revise the CSO-Masterplan. The goal was to find a solution with minimized ecological impact at low costs.

This urban hydrological study featured some unusual approaches. First, the present state of city, sewer system, treatment plant and receiving waters was analyzed in an interdisciplinary field study. Using the quantity-quality sewer model ASMI, the annual pollutant loads for various planning alternatives were calculated. This allowed statements about the environmental impact of each alternative, taking into account the sensitivity of the receiving waters known from the biological field study. The proposed final alternative saved nearly 1 million DM at a much lower impact on the environment compared with the original planning, showing that it is possible to cope equally with ecological and economical requirements.
COMPUTATIONAL MODELLING OF A VORTEX CSO STRUCTURE
Authors: Saul Adrian J. , Svejkovsky Karel
Published: May 2018

Vortex combined sewer overtlow (CSO) structures with a peripheral spill weir are sometimes used within UK sewerage systems for the prevention of tlooding and the retention of pollutants within the sewer system.

The velocity distribution within such a CSO chamber has been simulated using the 3D mathematical model FLUENT. Similarly the particle tracking routine of FLUENT has been utilised to predict the trajectory and final destination (treatment or spill) of individual particles with known size and terminal velocity which were introduced within the intlow to the chamber. From this data it has been possible to predict the solids separation retention efficiency for these particles and the results have been compared with previously published experimental data. Some agreement was observed between the two sets of results.

The paper is concluded by a discussion concerning the capability and limitations of the FLUENT model to predict the hydraulic and pollutant retention performance of a Vortex CSO chamber.
INTEGRAL CONTROL REQUIREMENTS FOR SEWERAGE SYSTEMS
Authors: Capodaglio Andrea G.
Published: May 2018

Sewerage systems and sewage treatment plants are often planned, designed and operated as totally separate entities. As a result, sewage treatment efficiency is subject to considerable variability, depending both on general hydrologic conditions in the urban watershed (wet versus dry periods), and on specific “instantaneous” operating conditions. It has been postulated that the integration of design and operation in urban drainage and wastewater treatment could allow minimization of the harmful effects of discharges from treatment plants, combined sewer overflows and surface runoff. This “ideal condition” can be achieved through the introduction of so-called “Real-Time Control” technology in sewerage collection and treatment operations. This paper examines the requirements of a hypothetical integrated sewer flow and sewage treatment model, the mathematical tools used to design and operate Real-Time Control systems, and the issues emerging from an integration of the conveyance and disposal aspects of the sewerage cycle.
Determination of Different Groups of Organics in Waste Waters Using Test Filters – Relevance to Drinking Water Production
Authors: Hobby Ralph , Gimbel Rolf
Published: May 2018

The test filter method was used to evaluate the waterworks relevant (non-biodegradable) and the drinking water relevant (non-biodegradable and non-adsorbable) organic substances in the River Rhine coming from the municipal sewage plants and the pulp industry in Germany. The results show that the test filter method is very suitable for the characterization of the different waste waters. An estimation based on the collected data shows that from 1987 to 1988 10% of the waterworks relevant AOX in the River Rhine has its source in municipal sewage water from Germany. In the same period about 30% was coming from the German pulp industry, but until today this value decreased strongly because the two most important pulp factories modified their bleachery. New investigations show that the dilution of the waste water in the River Rhine has to be taken into consideration.
Surface Water and Sediment Contamination in an Old Industrial Region of Poland – Two Critical Examples
Authors: Suschka J. , Ryborz S. , Leszczynska I.
Published: May 2018

The Upper Silesia Region, one of the most industrialized parts of Poland and also one of the oldest industrial regions in the world, has considerably contributed to the water pollution of the Vistula and Odra Rivers, the main watercourses in Poland. Wastewater from ferrous and non-ferrous metal industry, coal mines, coal-fired power and heat generation stations, chemical industry and large amounts of municipal sewage of the four million population have been discharged to the surface water for many years. Most rivers are highly polluted in spite of some remedial action which has been undertaken.

Studies on contamination of the river water and sediments, including analysis of their fate in the river course, have been carried out in order to find effective remediation actions. Special attention has been paid to heavy metals. The total concentration and their chemical form in suspended solids and in sediments was evaluated. Sediments deposited in the river bed serve not only as a historical record, but also demonstrate a serious hazard for the future, keeping in mind the continuous changes within the environment.

The paper shows the extent of contamination of two rivers in the examples of the Biala Przemsza River (tributary of the Vistula River) charged mainly by zinc-lead industry and the Klodnica River (tributary of the Odra River) charged mainly by coal mines, steel works wastewater and municipal sewage.
DECOMPOSING ORGANIC CHLORINE COMPOUNDS IN DRY CLEANING WASTEWATER BY FENTON'S REACTION ON RETICULATED IRON
Authors: Takemura Yozo , Seno-o Kengo , Mukai Tatsuo , Suzuki Motoyuki
Published: May 2018

Decomposition of tetrachloroethylene which is used in dry cleaning was studied. Static (vial bottle) and dynamic (circulating apparatus) experiments were performed. The comparison of effectiveness as an iron source for Fenton's reaction was made among several kinds of iron and reticulated iron was chosen as the best material. While organic chlorine compounds added in pure water were easily decomposed by Fenton's reaction on porous (reticulated) iron in aqueous phase, it was found difficult to achieve high efficiency in the case of wastewater from the actual laundry process. The reason was estimated to be the coexistence of high COD residuals, such as dirt and organic acids. The combination of circulation and air bubble agitation have even led to the total removal of99.8% of the tetrachloroethylene.
START-UP STRATEGY FOR SBR TREATMENT OF COMPLEX INDUSTRIAL WASTEWATER
Authors: Muñiz M. , Lavin A. G. , Díaz M.
Published: May 2018

In SBR processes, the start-up operation is of considerable interest, not only because of the effect of the efficiency on normal operation, but also because of the cost of the transport of sludge seed and the related feeding time with artificial substrate. The selection of the strategy bas not been studied previously as far as we know, although it is a problem of considerable economic importance. This is not only a problem of the relation between seed magnitude and the start-up timing, but also the effect on the process efficiency. The start-up in SBRs is more frequent than in conventional activated sludge when considering SBRs are mainly used for industrial wastewater treatment, where there are more stops and changes of organic load.

A start-up strategy for SBR biological treatment of industrial wastewater with several complex organic components, based on two steps (Filling and Conditioning Periods), bas been proposed and put into operation in a pilot plant column. The strategy looks for minimum time to achieve high steady state efficiency, and low cost of implementation, and sludge seeding. It makes a provision for feed on the basis of inhibition potential and organic needs, and introduces instructions during the operation, depending on the results being obtained.

The results of this strategy using a complex organic high salinity water are presented. The presence in this case of two types of solvents and very high salts concentration has been a good test problem for the proposed strategy because of the necessity of multiple adaptation of sludge and the considerably difficult problem to be solved.
Secondary Channels: Opportunities for and Limitations of Habitat Restoration
Authors: Barneveld H. J. , Nieuwkamer R. L. J. , Klaassen G. J.
Published: May 2018

For restoration of natural habitats in fluvial ecosystems secondary channels have been proposed. However, the other functions of the river should not be affected too much. In this paper the possibilities and limitations of re-opening these secondary channels are assessed. A methodology is outlined for the design of secondary channels and for the assessment of their effects on the other functions of the river. From the results of several complementary research projects we conclude that secondary channels in the flood plains can be designed to be quasi-stable. When applied only locally, additional measures in the main river are necessary to avoid deterioration of shipping conditions during low flows.
Tackling the Bank Erosion Problem: (Re-)Introduction of Willows on Riverbanks
Authors: van Splunder I. , Coops H. , Schoor M. M.
Published: May 2018

River regulation and increased shipping have resulted in serious erosion problems on the banks of the River Rhine. As an alternative for hard material or suppletion of sand, the Institute of Water Management and Waste Water Treatment is considering the use of willows for riverbank protection. Floodplain forests in The Netherlands are almost absent, mainly due to intensive cattle grazing. Various willow species were planted on sandy beaches at five locations along the River Rhine in 1990. After 2 growing seasons Common Osier (Salix viminalis) had the highest percentage survival and Grey Willow (S. cinerea) the lowest. Additionally, a survey has been planned to calculate roughness changes in the riverbed and wave extinction caused by the vegetation. Another goal of the project is to investigate the possibilities of establishment and development of a natural riverbank forest after excluding cattle.
Surface Flow and Particle Settling in a Coastal Reed Field
Authors: Hosokawa Y. , Furukawa K.
Published: May 2018

Hydraulic roughness of reed stems in shallow surface flow under low current velocity is discussed. The roughness coefficient, defined as a Manning's formula, depends upon depth and velocity in this flow. Depth and velocity, in turn, are altered by roughness through water surface slope. The interaction between these three parameters must be solved simultaneously for the prediction of the surface flow in a reed wetland. Stem roughness can be expressed as a function of Reynolds' number, similar to that for a single cylinder. Assigning this function, an iteration method easily gives us a suitable set of three parameters.

Settling experiments show that stems promote vertical mixing of fine particles in shallow flow. The model of vertically uniform SS concentration is more suitable. Though the observed data fluctuated widely, the apparent settling velocity of fine particles in the flow was very close to the settling velocity in quiescent water.

Using the above two models, one for flow and the other for settling in shallow wetland, we can estimate the clarification potential of a reed field under given hydraulic conditions and particle load. Numerical experiments show that fine particles tend to accumulate on the bottom of a reed field, as often observed in natural wetlands.
The Combination of a Flood-Retarding Basin and a Wetland to Manage the Impact of Urban Runoff
Authors: Breen P. F. , Mag V. , Seymour B. S.
Published: May 2018

Both agricultural development and urbanization of natural catchments have had a marked effect on the quantity and quality of runoff. Runoff quantity generally increases whereas quality usually decreases. Development in general also has a detrimental impact on the natural values of a catchment for both wildlife habitat and human recreation. This paper describes the design for a combination flood-retarding basin and wetland to manage both the quantity and quality of urban runoff. The combined system also has the potential to be managed for wildlife habitat and open space for passive human recreation.
SIMULATION OF THE OPERATING CONDITIONS OF THE MUNICIPAL WASTEWATER TREATMENT PLANT AT LOW TEMPERATURES USING A MODEL THAT INCLUDES THE IA WPRC ACTIVATED SLUDGE MODEL
Authors: Funamizu Naoyuki , Takakuwa Tetsuo
Published: May 2018

There are some advantages to using the sewage system to transport and melt snow in snowy regions. Since this would cause a drop in sewage temperature, adequate methods of operating treatment plants at low temperatures should be addressed. First, calibration of the IA WPRC activated sludge model was done using pilot plant data from a 10°C experiment. Then, the temperature coefficients in the reaction rate equations were estimated using the data from operation at 5°C. Comparison of the simulation results with data gathered under other temperature conditions showed that the IA WPRC activated sludge model could be applied to low temperature conditions. A newly developed model of the full-seale plant was able to simulate not only the biological reaction in the aeration basin but also the perfonnance of primary and final clarifiers, and sludge thickening and dewatering processes. The sludge and cake production rates, MLSS, and nitrification perfonnance calculated by this model coincided with plant operation results at I2°C. Operation maps of the plant in Sapporo were drawn at presumed low temperatures, 4 and 8°C. They showed that if nitrifying bacteria were kept in the plant, an overload in the sludge treatment process would be unavoidable without augmenting the capacity of water or of the sludge-treatment system.
Long-Term Impacts of Sewage Effluent Disposal on a Tropical Wetland
Authors: Osborne P. L. , Totome R. G.
Published: May 2018

Waigani Lake, near Port Moresby, Papua New Guinea, is part of an extensive wetland dominated by the Laloki and Brown Rivers. The wetland has received sewage effluent from stabilisation ponds for over 25 years. Water quality of the sewage, Waigani Lake and its outflow assessed in 1985 indicated that the wetland was significantly reducing suspended solid loads and the concentrations of dissolved nitrogen and phosphorus. Aerial photographs of Waigani Lake taken between 1966 and 1991 document the complete loss of submerged and floating-leaved plants and the decline in the extent of the littoral, emergent vegetation. These changes are related to sewage effluent disposal and, possibly, alterations in the magnitude of annual water level fluctuations. This study of a tropical wetland to which very large quantities of sewage effluent have been added demonstrates that the capacity of wetlands for water purification is limited and that further study on tropical wetlands is imperative before management strategies developed for temperate wetlands are applied directly to them.
Constructed Wetlands for River Water Quality Improvement
Authors: Kadlec R. H. , Hey D. L.
Published: May 2018

The Des Plaines River Wetlands Demonstration Project has reconstructed four wetlands in Wadsworth, Illinois, USA. The river drains an agricultural and urban watershed, and carries a non-point source contaminant load of sediment, nutrients and agricultural chemicals. Up to 40% of the average stream flow is pumped to the wetlands, and allowed to return from the wetlands to the river through control structures followed by vegetated channels. Native wetland plant species have been established, ranging from cattail, bulrushes, water lilies, and arrowhead to duckweed and algae. Pumping began in the summer of 1989, and has continued during the ensuing spring, summer and fall periods. The experimental design provides for different hydraulic loading rates, ranging from 5 to 60 cm/week. Intensive wetland research began in late summer 1989, and continues to present. Detailed hydrology is measured for each wetland. Sediment removal efficiencies ranged from 86–100% for the four cells during summer, and from 38–95% during winter. Phosphorus removal efficiencies ranged from 60–100% in summer and 27–100% in winter. The river contains both old, persistent and modem, degradable agricultural chemicals. The principal modem pollutant is atrazine, of which the wetlands remove approximately half. The project is successfully illustrating the potential of constructed wetlands for controlling non-point source pollution at an intermediate position in the watershed.
OPTIMAL EXPERIMENTAL DESIGN FOR STRUCTURE CHARACTERIZATION OF BIODEGRADATION MODELS: ON-LINE IMPLEMENTATION IN A RESPIROGRAPHIC BIOSENSOR
Authors: Vanrolleghem P. , Van Daele M.
Published: May 2018

The interaction between activated sludge and a wastewater is subject to important cbanges. This is reflected not only in changing biokinetic parameters but also in changing model structures. The need to select the ‘ right’ model structure in a reliable way on the basis of respirographic data provided by on-line sensors imposes serious real-time constraints on the methods used. First of all, fast structure characterization methods are presented allowing us to track the model structure on-line. Since these so-called a priori methods are less computing intensive, they can be at the basis of optimal experimental design calculations that can be performed on-line. This allows us to maintain the quality of the overall model identification under the changing process conditions of a wastewater treatment plant. Two applications of Optimal Experimental Design are given.
Wetland Treatment for Trace Metal Removal from Mine Drainage: The Importance of Aerobic and Anaerobic Processes
Authors: Eger P.
Published: May 2018

When designing wetland treatment systems for trace metal removal, both aerobic and anaerobic processes can be incorporated into the final design. Aerobic processes such as adsorption and ion exchange can successfully treat neutral drainage in overland flow systems. Acid drainage can be treated in anaerobic systems as a result of sulfate reduction processes which neutralize pH and precipitate metals.

Test work on both aerobic and anaerobic systems has been conducted in Minnesota. For the past three years, overland flow test systems have successfully removed copper, cobalt, nickel and zinc from neutral mine drainage. Nickel, which is the major contaminant, has been reduced around 90 percent from 2 mg/L to 0.2 mg/L. A sulfate reduction system has successfully treated acid mine drainage for two years, increasing pH from 5 to over 7 and reducing concentrations of all metals by over 90 percent.

Important factors to consider when designing wetlands to remove trace metals include not only the type of wetland required but also the size of the system and the residence time needed to achieve the water quality standards.
Case Studies of Wetland Filtration of Mine Waste Water in Constructed and Naturally Occurring Systems in Northern Australia
Authors: Noller B. N. , Woods P. H. , Ross B. J.
Published: May 2018

A problem common to mines operating in the tropics is the disposal of water, which may be alkaline, acidic, or contain toxic elements such as arsenic or cadmium. The availability of year-round water supply at many mine sites in Northern Australia, particularly from pit dewatering, together with the monsoonal climate, provide appropriate conditions for the formation of natural wetlands or establishment of artificial wetlands. Wetland species (particularly Typha spp.) flourish in the presence of flowing or shallow water from dewatering, and data collected from natural and experimental wetlands show reduction of metal concentrations by wetland filtration of mine waste water.

The following case studies are considered:Constructed wetlands, used to remove uranium from waste rock runoff before release to an adjacent creek provide a means of “polishing” runoff water prior to discharge to the creek.Creek-Billabong systems with existing wetlands adjacent to mine sites adventitiously “filter” waters discharged from mine sites. Trace elements in dewatering water from a gold mine discharged into an oxbow show reduction of elemental concentrations downstream, compared to discharge water.Naturally generated wetlands at several Northern Territory mines have developed along channels for discharge of pit water, with ingress of Typha domingensis. Such wetlands, associated with dewatering, have been examined at four mines, some with acid mine drainage. Water quality measured after wetland treatments shows reductions in concentrations of various heavy metals and sulfate. Volunteer Typha domingensis grows and spreads in shallow flowing channels, providing an inherent “filtration” of the water.Natural swamplands are incorporated in the waste rock runoff management design of a new gold mine, to reduce potentially high arsenic levels in the waste water.

Constructed and naturally occurring wetlands may be used in the treatment of most mine waste waters to achieve levels of constituents acceptable for discharge to the surrounding environment.
The Function of a Coastal Wetland as an Efficient Remover of Nutrients from Sewage Effluent: A Case Study
Authors: Soukup A. , Williams R. J. , Cattell F. C. R. , Krogh M. H.
Published: May 2018

The Racecourse Wetland in Wyong, New South Wales, was used for twenty years (1968–1988) as a site for disposal of secondarily treated sewage effluent. The area of the wetland is 90 ha and the average amount of effluent received was 1.7 ML/day. A nineteen-month study (June 1986-January 1988) was undertaken in order to determine the efficiency of pollutant assimilation in the wetland, with particular reference to plant nutrients. The wetland was sampled at approximately fortnightly intervals, at six different sites at various distances from the oxidation pond outlet. The first downstream sampling site was 650 m from the oxidation pond, where average concentrations of ammonia and total phosphorus were reduced by more than 99 percent to 59 μg/L and 39 μg/L respectively. Concentrations of nutrients in samples of effluent from the oxidation pond varied with season. Average summer concentrations for ammonia were 30 mg/L compared with 6 mg/L for winter. The corresponding total phosphorus concentrations were 12 mg/L and 9 mg/L. Downstream of the first sampling station the wetland seemed to function as a mild nutrient source rather than sink. However, the levels of nitrogen and phosphorus reaching the nearby Wyong River were very low, with phosphate and total Kjeldahl nitrogen levels only slightly higher than those already in the river.
Experimental Studies for Improved Nitrification in Shallow Lagoon Systems
Authors: Scott P. H. , Gross P. M. , Baskaran K. , Connor M. A.
Published: May 2018

Two separate experimental studies aimed at enhancing nitrification in lagoon systems are described. In the first study a system of four 1:10 scale experimental ponds was used to evaluate the potential for enhancement of nitrification through the control of hydraulic loading rates to lagoon systems. A relationship incorporating the parameters: hydraulic retention time, nitrifier growth rate, temperature, pH and chlorophyll a concentration was established. This relationship provides a useful guide to managing lagoons but further work is required to provide a better understanding of the processes involved. In the second study eight laboratory-scale reactors were used to evaluate the potential for enhancement of nitrification through the use of algal/bacterial biofilms. The study showed that these biofilms have the potential to enhance nitrification, particularly under more adverse conditions such as low hydraulic retention time, high organic loading and low levels of D.O., pH and temperature.
Quo vadis water quality management in central and eastern Europe?
Authors: Somlyody L.
Published: May 2018

Central and Eastern European (CEE) countries are going through unique political, economic, institutional, and social changes associated with the heritage of serious pollution problems from the past. The purpose of this paper is to analyze the water quality management strategies CEE countries may take including the rationale of introducing Western policies in the short run. The policy to be selected must be viable under the existing pressing financial conditions and should feasibly be expanded towards a long-term sustainable scenario as economy improves. As a basis the present economic, social, and institutional setting is outlined, and the state of water quality and the role of emissions of various origins are summarized. A special focus is devoted to municipalities with low and unbalanced levels of infrastructure; the development of these infrastructures could be aburden even for stable economies. An overview and evaluation are given for the water supply, sewerage, and wastewater treatment for urban areas with populations greater than 25,000 in five countries of the CEE region together with a discussion of legislation issues. Major elements of cost-effective development strategies are discussed and illustrated by examples. They incorporate improved demand management and the closing of material cycles, the upgrading of wastewater treatment facilities to match the level of sewerage, the application of regionally variable effluent (and/or ambient) water quality standards and their gradual tightening based on a river basin approach, the innovative selection of combined chemical-biological technologies (for both upgrading and new design) depending on local conditions and the multi-stage development of wastewater treatment plants. The policy suggested for the next couple of decades is characterized by a number of non-uniformities which raises considerable implementation challenges.
Development of least-cost water quality control policies for the Nitra River basin in Slovakia
Authors: Somlyódy L. , Kularathna M. , Masliev I.
Published: May 2018

The Nitra is one of the most polluted rivers in Slovakia due to numerous municipal and industrial discharges, as well as the low level of wastewater treatment. The ongoing economic transition and lack of financial resources for water quality management calls for the development of short-run least-cost policies on the basis of ambient standards or a combination of ambient and effluent ones. A water quality control policy model was developed which incorporates dissolved oxygen simulation models, alternative municipal treatment plans and dynamic programming. Least-cost policies to achieve various water quality goals were developed and compared to effluent standard based strategies (including that deriving from the application of the “best available technology”). The role of industrial emissions was demonstrated in a sensitivity fashion, while the influence of parameter uncertainty on the developed policies was analyzed in a multiobjective framework. The analyses show that significant cost savings are possible in comparison to uniform, effluent standard policies. They also suggest that a long-term strategy should be realized on the basis of a sequence of properly phased least-cost policies corresponding to ambient standards to be tightened gradually.
New aspects of urban drainage and pollution reduction towards sustainability
Authors: Niemczynowicz Janusz
Published: May 2018

A very basic problem of open material flows resulting in accumulation of pollution is not adequately addressed in present societies. Developed countries with expensive water-related infrastructure still contribute to local and global pollution. Developing countries to a great extent lack water treatment facilities and environmentally sound water management. Large scale end-of-pipe wastewater treatment is one of the spectacular examples of technologies that must change in order to provide a sustainable solution. In order to start the way towards a solution of increasing worldwide pollution problems, a new holistic approach to resource management must be applied. The final goal of such an approach is to close the cycles of residuals that damage the environment, and recover resources lost in residuals emitted from all human activities. Water management should be integrated with management of other activities such as waste handling, industrial production, transportation, energy production, etc. The most important action is to apply pollution prevention strategy, i.e. to prevent pollution formation at the source during all human activities. Different kinds of effluents should be separated instead of mixed together. Recycling of water, nutrients and solid residuals should be arranged on a lowest possible level of human settlements. Technologies exist that can solve the problem of pollution from wastewater on a very basic level of a single house or residential area. Stormwater flows with different origin can be separated and disposed locally or re-used in a single house. Industries should modify technologies so that, eventually, wastewater is not produced at all, instead all fluid, solid and gaseous residuals are recovered and recycled. Tools for implementation of such solutions are: legislation and administrative actions coupled with education programmes on all societal levels, increasing public awareness, competition rules of the market economy based on long-term profits. The goal is sustainability of the society by resource recovery and re-use. Demonstration projects, in which the rules of preventive approach and novel technology is applied may constitute a practical way of implementing such an approach.
Assessment of nitrification-denitrification potential of istanbul domestic wastewaters
Authors: Orhon Derin , Sözen Seval , Ubayo Emine
Published: May 2018

This paper summarizes experimental evaluations on Istanbul domestic wastewaters with respect to their potential of biological nitrogen removal. Characterization studies involve together with relevant carbonaceous and nitrogenous wastewater components, significant rate coefficients affecting aerobic and anoxic processes. Experimental results indicate a low biodegradable carbon to nitrogen ratio and a relatively small readily biodegradable COD fraction. A new method is introduced to determine maximum specific growth rate for autotrophic biomass. Correction factors for biological growth and hydrolysis under anoxic conditions are also assessed. The latter is found to be significantly higher than values proposed in the literature.
A comparison between ethanol and methanol as carbon sources for denitrification
Authors: Christensson Magnus , Lie Ewa , Welander Thomas
Published: May 2018

Ethanol and methanol were compared for their performance as carbon sources for denitrification. The study was carried out in two chemostats, operated in parallel on synthetic media containing ethanol and methanol respectively as carbon sources. In addition, pure culture studies were performed on one ethanol- and one methanol-utilizing denitrifier.

Ethanol was found to be considerably more readily available as a carbon source for denitrification than was methanol. An efficient denitrification with ethanol was established in a short time, while denitrification with methanol required a substantial adaptation time and never showed the same stability as denitrification with ethanol. The growth rate of denitrifiers with ethanol as carbon source was 2–3 times higher than with methanol. The amount of COD required to denitrify a certain amount of nitrate was somewhat lower for ethanol (3.85 g/gN) than for methanol (4.45 g/gN) in the continuous experiments, while it was considerably higher for ethanol (6.1 g/gN) than for methanol (4.1 g/gN) in pure culture batch cultivations.
Synthesis of denitrification enzymes in activated sludge: modelling with structured biomass
Authors: Wild D. , von Schulthess R. , Gujer W.
Published: May 2018

Three mechanisms are responsible for microbiological elimination processes in activated sludge: the survival of qualified organisms in the ecological selection process, the expression of specific enzymes and the absence of inhibitors limiting enzyme activity. A mathematical model with structured biomass has been formulated to improve the description of data from denitrification experiments. The model includes synthesis and decay of denitrification enzymes and is able to predict nitrate, nitrite and N2O concentrations. Kinetic parameters have been estimated and used to simulate the effect of cell saturation with enzymes in a waste water treatment process. Low dissolved oxygen concentrations in the anoxic reactor reduce the denitrification efficiency equally by inhibiting enzyme activity and enzyme synthesis: at 0.5 gm−3 O2 enzyme decay causes a cell saturation of below 40 %. Enzyme synthesis can take place in the sludge blanket of a secondary sedimentation tank and improve denitrification efficiency. The benefit of modelling with structured biomass is shown. The comprehension of experimental observations has been improved, and plant design and operation can be optimized. However, the multitude of unknown parameters still may restrict the validity of complex models.
A test method to determine inhibition of nitrification by industrial wastewaters
Authors: Böhm B.
Published: May 2018

A biotest to investigate wastewaters for the presence of nitrification-inhibiting substances has been developed. The principal feature of the test system is a packed-bed fixed-film biological reactor operated as a differential reactor. The test has been used to determine the effects on nitrification of wastewaters especially from textile and leather industries. Inhibition could be found even when the wastewater was diluted considerably. Tannery sewage may cause particularly severe problems in biological wastewater treatment, as the degree of inhibition of this wastewater has been observed to be similar to that of a solution of 2 mg/L allythiourea.
Denitrification in trickling filters
Authors: Dorias Bernd , Baumann Peter
Published: May 2018

National and international regulations require a minimum nitrogen removal efficiency of 70% in most public sewage treatment plants. Unlike in activated sludge plants, selective denitrification in trickling filters was not possible until now. Therefore the aim was to employ trickling filter plants for selective denitrification, using innovative technology that involved minimum capital expenditure. For selective denitrification, it is necessary to prevent as much as possible the transfer of oxygen into the trickling filter while feeding the nitrate to be removed, a process similar to upstream denitrification in the activated sludge process. In a test operation conducted in several sewage treatment plants for over a year, the new process with selective denitrification in a covered trickling filter has given successful results. The denitrification efficiency of this system is comparable to that of upstream denitrification in the activated sludge process. Thus, selective denitrification in the trickling filter is a practical alternative to other nitrogen removal processes, while maintaining the established advantages offered by the trickling filter process.
Genetic approach to enhanced biological phosphorus removal
Authors: Ohtake Hisao , Yamada Katsufumi , Hardoyo  , Muramatsu Ayako , Anbe Yuki , Kato Junichi , Shinjo Hisashi
Published: May 2018

Genetic improvement of bacterial ability to accumulate phosphate (Pi) was investigated using Escherichia coli as a test organism. High levels of Pi accumulation were achieved by (i) modifying the genetic regulation and increasing the dosage of the E. coli genes encoding polyphosphate kinase (ppk), acetate kinase (ackA), and the phosphate inducible transport system (pstS, pstC, pstA, and pstB) and (ii) genetically inactivating ppx encoding exopolyphosphatase. Acetate kinase was employed as an ATP regeneration system for polyphosphate synthesis. The best recombinant strain, which contained both pBC29 (ppk) and pEP02.2 (pst genes) accumulated approximately 10-fold more Pi than did the control strain. The phosphorus content of this recombinant reached a maximum of 16 % on the dry weight basis (49 % as phosphate). About 65 % of the cellular phosphorus was stored as polyphosphate.
Prediction of the performance of enhanced biological phosphorus removal plants
Authors: Maurer M. , Gujer W.
Published: May 2018

A static model is introduced, which allows for the estimation of the performance of a full scale EBPR plant. The model is based on the assumption that the readily biodegradable substrate from the influent and the total COD-turnover in the anaerobic zone determine the amount of phosphorus contained within phosphorus accumulating organisms. Model predictions are based on wastewater composition, operating temperature, effects of oxygen and nitrate addition to the anaerobic reactor, solids retention time and anaerobic mass fraction of the activated sludge. The model is calibrated with full scale experience and may be useful for the analysis of plant performance as well as the design of new treatment plants.
Nutrient removal using cyanobacteria (phormidium bohneri): experimental results with a batch reactor
Authors: Lessard Paul , Proulx Daniel , de la Noüe Joël
Published: May 2018

The implementation of nutrient removal is becoming a necessity for small communities. This paper presents an alternative biotechnology using cyanobacteria. Results of field experiments are presented and briefly discussed. Good performance is obtained with the system.
Wastewater inorganic N and P removal by immobilized chlorella vulgaris
Authors: Tam N. F. Y. , Lau P. S. , Wong Y. S.
Published: May 2018

The green alga, Chlorella vulgaris was immobilized in Ca-alginate beads at two stocking cell densities and grew in primarily treated domestic effluents. It was found that the cellular metabolic activities of this alga were retained after immobilization. The growth (in terms of cell counts) and photosynthetic rates of cells immobilized in beads of low stocking density were greater than those in beads of high density. Significant reduction of wastewater NH4+-N and PO43−-P was recorded especially in reactors containing algal beads of high density. These results suggested that immobilized Chlorella cells can be used as secondary treatment process for domestic sewage.
The influence of a surfactant on the rate of phenanthrene mass transfer into water
Authors: Grimberg Stefan J. , Aitken Michael D. , Stringfellow William T.
Published: May 2018

Polycyclic aromatic hydrocarbons (PAH) are hydrophobic pollutants found in contaminated soils at many sites in the U.S. One method proposed to improve remediation of PAH contaminated soil is to add surfactants to help mobilize these and other poorly soluble compounds. Previous work on the effects of surfactants on PAH and other pollutants has focused on equilibrium phenomena. The influence of a surfactant on the rate of dissolution of phenanthrene, a model PAH, was determined in this study. Phenanthrene dissolution kinetics depended on the observed mass transfer coefficient and the apparent saturation concentration, both of which depended on surfactant concentration. A simple two-step mass transfer model was developed to describe the relationship between dissolution rate and surfactant concentration. This approach may be useful in estimating effects on mass transfer kinetics for a variety of surfactants using data that are either available in the literature or are readily measured.
Biodegradtion of all three isomers of monochlorophenol in a fixed bed reactor to very low concentrations
Authors: Schöllhorn Andreas , Stucki Gerhard , Hanselmann Kurt
Published: May 2018

An enriched mixed culture able to mineralize all three isomers of monochlorophenol (MCP) and a pure culture (Alcaligenes sp. A7-2) were used to inoculate a non-aerated fixed bed reactor filled with sintered glass beads. Oxygen was supplied in form of a 1% solution of H2O2. The 3 monochlorophenol isomers, added as a mixture (concentration of each compound 3.3 mgl−1), were eliminated to over 99%. When the MCP concentrations were lowered to 1 mgl−1 of each isomer, no addition of H2O2 was necessary since the oxygen concentration in the feed was sufficient for complete mineralization of the chlorophenols. Residual concentrations in the effluent of the reactor of below 0.2 μgl−1 for 2-MCP, 0.05 μgl−1 for 3-MCP and 4-MCP, respectively, were obtained. These values were also the detection limits for the three isomers. The low effluent levels were even obtained at hydraulic retention times of 0.7 h, which was reached stepwise. NO−3 did not serve as an alternative electron acceptor to O2.
Population Dynamics and Nitrite Build-Up in Activated Sludge and Biofilm Processes for Nitrogen Removal
Authors: Rols J. L. , Mauret M. , Rahmani H. , Nguyen K. M. , Capdeville B. , Cornier J. C. , Deguin A.
Published: May 2018

This article has the objective of showing the cause effect relationship between the dynamics of growth of autotrophic populations involved in nitrification and the uncontrolled accumulation of nitrite ions. This accumulation results in a disequilibrium in number or viability between the genera Nitrosomonas and Nicrobacter. This disequilibrium can be imposed, for example, by an inhibition of the activity of the genus Nitrobacter linked to the presence of free ammonia in the environment. The threshold of inhibition and the resultant degree of accumulation of nitrite depend both on the history of the sludge utilised as inoculum (mixed autotrophic population or enriched in one of two sources) and on the hydraulic regime of the reactor (completely mixed reactor for the activated sludges and piston reactor for the fixed cultures). These results enable us to better understand the behaviour of a nitrification reactor and to propose solutions either to avoid the accumulation of nitrites or to intensify this accumulation with the goal of proposing a new process of nitritation-denitritation via the nitrites route (nitrates shunt).
Fate of Readily Biodegradable Substrate under Anoxic Conditions
Authors: Andreadakis A. D. , Chatjikonstantinou G. J.
Published: May 2018

Readily biodegradable substrate fate under batch conditions was investigated. Anoxic as well as aerobic experiments were performed and factors affecting substrate uptake were determined. Nitrate reduction processes were also studied.
Reactor Performance and Microbial Population Characteristics in a Channel with Suspended and Attached Biomass
Authors: Cao Y. S. , Alaerts G. J. , Kaewsaengtham M.
Published: May 2018

A well mixed recirculating indoor channel was adopted to investigate aerobic heterotrophic biodegradation in drainage systems with suspended and attached biomass. The focused points include microbial activity and intrinsic kinetics of the liquid and biofilm, and the process kinetics. The linkage between reactor performance and the characteristics of biomass population was noticed.
Mass transfer and biodegradation of PAH compounds from coal tar
Authors: Ramaswami A. , Ghoshal S. , Luthy R. G.
Published: May 2018

This study examines the role of physico-chemical mass transfer processes on the rate of biotransformation of polycyclic aromatic hydrocarbon (PAH) compounds released from non-aqueous phase liquid (NAPL) coal tar present at residual saturation within a microporous medium. A simplified coupled dissolution-degradation model is developed that describes the concurrent mass transfer and biokinetic processes occurring in the system. Model results indicate that a dimensionless Damkohler number can be utilized to distinguish between systems that are mass transfer limited, and those that are limited by biological phenomena. The Damkohler number is estimated from independent laboratory experiments that measure the rates of aqueous phase dissolution and biodegradation of naphthalene from coal tar. Experimental data for Stroudsburg coal tar imbibed within 236μm diameter silica particles yield Damkohler numbers smaller than unity, indicating, for the particular system under study, that the overall rate of biotransformation of naphthalene is not limited by the mass transfer of naphthalene from coal tar to the bulk aqueous phase. There is a need for investigation of mass transfer for larger particles and/or other PAH compounds, and study of microbial rate-limiting phenomena including toxicity, inhibition and competitive substrate utilization.
Microfauna Biomass in Activated Sludge and Biofilm
Authors: Madoni Paolo
Published: May 2018

The colonization dynamics of ciliated protozoa in a full-scale activated sludge plant and in a RBC pilot plant has been monitored in order to quantify their presence in terms of biomass. In both plants, as the concentration of sludge or biofilm increased, the overall biomass of the ciliate community increased until reaching the highest values during the full-running phase. Ciliate biomass reached values of 250 mg/l (dry weight) in the activated sludge and 314 µg/cm2 (dry weight) in the RBC biofilm. The ciliate biomass/volatile solids ratio was over 9 % for the activated sludge and 12 to 19% for RBC biofilm. High correlation coefficients between ciliate biomass and volatile solids were also observed, which emphasized the close association of ciliate populations with both sludge and biofilm.
Influence of water evaporation on soil vapor extraction (SVE)
Authors: García-Herruzo F. , Gómez-Lahoz C. , Rodríguez-Jiménez J. J. , Wilson D. J. , García-Delgado R. A. , Rodríguez-Maroto J. M.
Published: May 2018

As SVE proceeds large amounts of water are withdrawn from the soil with the gaseous stream together with the contaminants. This may lead to important variations in the pneumatic soil permeability and changes in the soil temperature. A one-dimensional column mathematical model is developed to study these effects, based on the Millington and Quirk expression and assuming local thermal equilibrium and fast water mass transfer from the condensed to the gaseous phase. This model yields a good agreement with experimental results obtained with fine-sand lab columns. The molar flux increases during the process, but most of this increase takes place during the latter period of the drying process. Important temperature drops (up to 10 °C) are also expected when relative moisture of the air is low.
Variations in Phenotypic Characters of Type 021N from Activated Sludge Systems
Authors: Hudson R. , Williams C. , Seviour R. J. , Soddell J. A.
Published: May 2018

Several cultures of Type 021N were characterised and although all had similar morphological properties they showed considerable variations in their substrate utilisation patterns and enzyme profiles.