bluuebunny/crossref_metadata_2025 huggingface dataset:
Upgrading and nitrification by submerged bio-film reactors - experiences from a large scale plant
Authors: Lessel T. H.
Published: May 2018

The upgrading and nitrification was a requirement in 1986 for the conventional sewage treatment plant Geiselbullach, west of Munich, Germany, designed for 250 000 inhabitants equivalents. The possibility was tested to use submerged bio-film reactors in the aeration tanks to increase the MLSS concentration. Half-scale experiments were undertaken with three different reactor types. A rope type material, called Ring-laceR was selected for the large-scale application, because it did not produce anaerobic sludge deposits, as the other tested reactor types did. The design criteria had to be developed. The process operation started in January 1988; a few months later the phosphorus removal by chemical precipitation was also put into operation. After stable conditions were assured the concentration of the MLSS could be increased to about 10 g/l, due to sludge volume indices of about 50, formerly 180 to 300. A nearly complete nitrification was achieved, which could even be continued in winter times at water temperatures of 8 to 10 °C.

Many highly developed microorganisms in the sessile sludge occurred (nematodes, tubifex…), which grew excessively under certain conditions and reduced the normal bacteria to unacceptable low quantities. A worm cure could reduce the worms to acceptable counts. Problems with the longtime stability of the material arose and were investigated.
Three years of full-scale captorR process operation at Moundsville WWTP
Authors: Golla P. S. , Reddy M. P. , Simms M. K. , Laken T. J.
Published: May 2018

Three years of full-scale operation of the CaptorR process had been completed at the Moundsville/Glen Dale Wastewater Treatment Plant (WWTP) treating a design flow of 8706 m3/d (2.3 mgd). The CaptorR process applied a combination of attached and suspended growth processes by adding polyurethane foam media to activated sludge process, raising the equivalent MLSS concentration. The CaptorR system was designed as a separate front portion of the activated sludge process, with one third of the total HRT of the activated sludge process. The suspended MLSS in the Captor basin was around 900-1700 mg/L and the equivalent media based attached MLSS was maintained at 6,500-12,000 mg/L. It has been found that soluble CBOD5 removal, nitrification and partial denitrification occurred simultaneously in the Captor basin. The influent loadings to the Captor chamber were at 100-130 mg/L of soluble BOD5, 20-30 mg/L NH3-N, and 50-70 mg/L of TSS at flow rates of 5678-10031 m3/d (1.5-2.65 mgd). Over the last three years, 95% soluble CBOD5 removal, 70-90% nitrification and 40-60% denitrification were achieved at an HRT of 50-90 minutes in the Captor chamber. The plant effluent characteristics consistently met 2-4 mg/L of CBOD5, 1-4 mg/L of TSS, and 2-4 mg/L of Ammonia at low temperatures of 12°C-15°C. The HRTs were 2.5-5 hours for secondary aeration with a sludge age of 3-5 days for the activated sludge portion.
Start-up of anaerobic fixed film reactors: technical aspects
Authors: Austermann-Haun U. , Seyfried C. F. , Zellner G. , Diekmann H.
Published: May 2018

For two years lab-scale experiments were done to find the conditions to enhance the start-up of anaerobic fixed film reactors. Five reactors were operated in parallel with a sythetic wastewater containing acetic, propionic and butyric acid in a weight relation of 2:1:1 resulting in a COD of 20,000 mg/l. Using polypropylene curlers (NOR-PAC R 92/1) as support medium (substratum) and mostly digested sludge of a municipal wastewater treatment plant as inoculum, we found that the activity of the starter culture, effluent recirculation, calcium dosage and the mode of increasing the organic loading rate had a significant influence on start-up behaviour. Depending on the way to run the start-up space loading rates of 10 to 30 g COD/(l·d) could be reached within 58 days. In contrast to these “manual” start-ups it is shown that the most efficient way is to run a start-up pH-statically with an automatic substrate feeding regulated by the pH measured in the top of the reactor. Within 36 days a space loading rate of 60 g COD/(l·d) with a COD removal efficiency of 70 % could be reached.
Scale-up and biomass hold-up characteristics of biological fluidized bed reactors
Authors: Ozturk I. , Turan M. , Idris A. H.
Published: May 2018

This paper presents a comprehensive study results on scale-up and biomass hold-up characteristics of biological fluidized bed reactors (BFBR). The overall objective of this study was to establish and test some basic design criteria for the scaling-up or scaling-down of anaerobic fluidized bed reactors. A 12.5 1 laboratory-scale fluidized bed was designed and constructed based on a geometrically similar 70 1 pilot scale fluidized bed and the process performances were compared. Biomass hold up characteristics of the BFBRs were also investigated during the experimental studies. A general expression was developed for predicting the biological fludized bed porosities. Using this expression, both the local and overall fluidized bed porosities could be predicted depending on biofilm thickness, expansion coefficient, media diameter and density. The validity of this expression was tested with the data from this study.
Kinetic study and mathematical modeling of biofilm in an anaerobic fluidized bed
Authors: Imai T. , Kusuda T. , Furumai H.
Published: May 2018

The objectives in this study are to develop a layered model with attrition for the growth process of biofilm in a methanogenic fluidized bed reactor, to discuss the possibility of existence of “dormant” biomass in the biofilm, and to estimate distributions of active biomass in the biofilm by the model. The model expresses characteristics and distributions of microorganisms inside the biofilm. Each substrate consumption activity of attached, sloughed, and remaining biomasses is measured by batch experiments. Comparing their specific activities, the possibility of existence of “dormant” biomass in the biofilm is indicated. Dormant biomass is inactive in the biofilm, but its activity recovers by the supply of substrates. Based on results of the experiments, a layered biofilm model is developed, into which the concept of “dormant” biomass is incorporated. The accumulation process of active and dormant biomasses in the biofilm is expressed by simulation with this newly developed model.
Comparative study evaluating removal mechanisms of hydrocarbons by fixed film versus suspended growth reactors
Authors: Galil N.
Published: May 2018

Biological treatment of wastewater from a petrochemical complex was performed in order to evaluate the removal mechanisms of hydrocarbons by two parallel processes: rotating biological contactor (RBC) and activated sludge. The influent contained 700 mg/L COD, 140 mg/L BOD, 7.5 mg/L phenols and 32 mg/L hydrocarbons in emulsified form. The hydraulic detention time was 14 to 18 hours for activated sludge and 4 to 5 hours for RBC. It was found that both units produced an effluent containing a residual hydrocarbon of about 10 percent from the initial effluent concentration. The distribution of the removed hydrocarbon was: in activated sludge 70 percent by attachment to biosolids and wasted with the removed sludge; in RBC 15 percent were stripped to the atmosphere, 25 percent by biodegradation and 50 percent were removed by wasted sludge. The higher fraction of hydrocarbon biodegraded by the fixed film seems to be the result of higher active biomass which could concentrate in the RBC reactor. The fact that RBC removes less hydrocarbon to the atmosphere is considered as an environmental advantage. Although the fixed film attached a major part of the hydrocarbons, the biosludge production and characteristics for the fixed film were substantially better than for the suspended growth.
Degradation of BTEX and their aerobic metabolites by indigenous microorganisms under nitrate reducing conditions
Authors: Alvarez P. J. J. , Vogel T. M.
Published: May 2018

Batch incubations, seeded with four different aquifer materials, were used to survey the catabolic capacity of indigenous microorganisms under nitrate reducing conditions. Benzene, toluene, ethylbenzene, xylenes (BTEX), and selected potential metabolites of their incomplete aerobic degradation, were tested as substrates for nitrate-based respiration. Toluene and its potential aerobic metabolites, benzoate, protocatechuate, 3-methylcatechol, 4-methylcatechol, succinate, and adipate were degraded in strictly anoxic (O2 < 0.1 mg/l) nitrate reducing incubations. Toluene degradation was directly coupled to nitrate reduction. Ortho-xylene removal was toluene dependent. Meta- and para-xylenes were degraded in nitrate reducing enrichments from only one of the four aquifer samples. Benzene, ethylbenzene, catechol and gentisate were not degraded within up to four months in any of the incubations, even though nitrate reduction occurred. Anaerobic benzene degradation was not observed. Incubations receiving nitrate as an adjunct electron acceptor to oxygen degraded significantly more benzene than incubations amended with only oxygen, although benzene was only degraded until the dissolved oxygen was depleted. Possibly, more oxygen was available to degrade benzene when nitrate was added because denitrifiers utilizing nitrate as terminal electron acceptor oxidized benzoate, which had been added to increase the biochemical oxygen demand of the system. Benzoate oxidation with nitrate apparently spared oxygen for benzene degradation.
Modeling of volatile organic contaminants in trickling filter systems
Authors: Melcer Henryk , Parker Wayne J. , Rittmann Bruce E.
Published: May 2018

Despite the widespread use of trickling filters, there has been minimal investigation of the fate of volatile organic contaminants (VOCs) in such systems. A model describing the fate of VOCs in trickling filters is described. The removal of VOCs was investigated in a pilot-scale trickling filter receiving a feed of sewage dosed with a constant concentration of selected VOCs. Increasing hydraulic loading tended to increase the proportion of influent VOCs found in the effluent. Imposing effluent recycle also increased the fraction of VOCs found in the effluent but also decreased the fraction stripped and increased the fraction that was biodegraded. The values of the biodegradation coefficient, Kb, were found to be reproducible and affected by a combination of high hydraulic loading rate and effluent recycle.
Recombinant plasmid retention and expression in bacterial biofilm cultures
Authors: Bryers James D. , Ching-Tsan Huang
Published: May 2018

Any exposure of plasmid recombinant microorganisms to an open system environment, either inadvertently or intentionally, mandates research into those fundamental organism:plasmid processes that influence plasmid retention, transfer and expression. In open environmental systems a majority of the microbial activity occurs associated with an interface, within thin biological layers consisting of the cells and their insoluble extracellular polymer, layers known as biofilms. Thus any study regarding the fate of recombinant DNA sequences in an open system must consider processes that affect plasmid retention and expression in a biofilm culture.

Biofilm cultures were cultivated in a parallel-plate flow cell reactor using E. coli DH5α which contained a recombinant plasmid with a plasmid stability factor, parB, (pTKW106) or without (pMJR1750). Using β-galactosidase as inducible reporter protein, plasmid retention and gene expression of pMJR1750 and pTKW106, in suspended versus biofilm cultures, were studied under different carbo to nitrogen ratios and plasmid induction levels. Recombinant biofilm formation under these environmental conditions was also investigated. Biofilm net accumulation rate of E. coli DH5α (pTKW106) decreases with increasing induction levels. The β-galactosidase production and ratios of β-galactosidase to total protein increase with increasing induction levels. Synthesis rates of total RNA, β-galactosidase mRNA and rRNA in biofilm cultures of E. coli DH5α (pTKW106) increase after induction by IPTG.
On-site stormwater detention systems in Sydney
Authors: O'Loughlin Geoffrey , Beecham Simon , Lees Stephen , Rose Lawrence , Nicholas Douglas
Published: May 2018

On-site stormwater detention (OSD) requirements are applied by most municipalities in Sydney, Australia. Persons redeveloping properties served by existing drainage systems must provide storages for stormwater, to compensate for increased runoff from the new development. While OSD is widely accepted, procedures differ considerably between municipalities. Many designers criticise guidelines and design methods, and express doubts about the maintenance and economy of OSD systems. This paper surveys the application of OSD in Sydney, describes typical installations, and reviews their effectiveness. It sets out the main arguments for and against OSD systems, discusses alternatives, and indicates how systems and procedures will evolve in the future.
Anoxic and oxic biological fluidized bed treatment of amines and phenol
Authors: Nguyen Van T. , Shieh Wen K.
Published: May 2018

Significant amounts of nitrogenous organic compounds found in industrial wastewaters can have major deleterious effects on the environment and public health; therefore, the removal of these compounds has become an essential component in industrial wastewater treatment. In this work the biodegradability of diisopropylamine and monoethylamine - compounds commonly found in petroleum refinery wastewater - was investigated under oxic and anoxic conditions. Biological fluidized bed reactors were employed in the investigation of single-stage carbon oxidation and nitrification with the amines and phenol as the compounds targeted for removal. Complete carbonaceous oxidation was achieved with a 50% nitrification rate. The feasibility of utilizing the amines and phenol as the organic carbon source for denitrification in an anoxic biological fluidized bed process was also examined. Carbon removal under anoxic conditions was greater than 85% at carbon loading rates less than 0.05 mg TOC/mg biomass-day and decreased to 60% at higher loading rates. Over the range of loading rates tested, the average ratio of mg TOC removed to mg NO3−-N utilized was observed to be 1.26.
Dynamics of the anaerobic utilization of organic substrates in an anaerobic/aerobic sequencing batch reactor
Authors: Carucci A. , Lindrea K. , Majone M. , Ramadori R.
Published: May 2018

The operation of an anaerobic/aerobic Sequencing Batch Reactor (SBR) with synthetic feed (glucose as the sole organic substrate) demonstrated periods of non-EBPR and EBPR operation in the absence of polyhydroxy alkanoate (PHA) storage. The glucose added as feed disappeared rapidly (within 10 minutes) and none of the normal fermentation products were detected in the supernatant in either mode of operation. Anaerobic/aerobic batch trials using the biomass from the SBR were conducted to examine the processes taking place and a rapid uptake of glucose was confirmed and was accompanied by a fall in pH. The biomass also demonstrated that anaerobic PHB storage occurred when acetate feed was used. The biomass was characterized by a large population of “G” bacteria, the absence of filamentous microorganisms, compact floc structure and high total carbohydrate (ca 40% w/w). The supernatant was characterized by low COD, TOC and the virtual absence of the glucose substrate. The observations indicate that EBPR was possible under circumstances which are not consistent with accepted mechanisms.
Application of the EU bathing water directive to the design of marine sewage disposal systems
Authors: Christoulas D. G. , Andreadakis A. D.
Published: May 2018

A mathematical model for the design of marine sewage disposal systems in accordance with the criteria of the EU Bathing Water Directive is developed and applied to the design of the outfall of the sewage from Athens, Greece. The model calculates the reduction of fecal coliforms due to initial and subsequent dilutions and die-off due to the effect of solar radiation and predicts the concentrations of fecal coliforms at the bathing area for specific hours and current velocities. A combination of these results with the probability distribution of the velocity of the sea currents results in a frequency distribution of fecal coliform concentrations at the bathing area, thus enabling evaluations with respect to conformity to the statistical criteria of the EU Directive.

The application of the model to the disposal system for the sewage of Athens shows that conformity, without the use of effluent disinfection, can be achieved for the nearest bathing area, located at a distance of 3.4 km from the outfall, irrespective of the definition of the bathing hours (8 am-8 pm or 24 hrs) and for a sufficiently conservative mortality rate. These results indicate that under Mediterranean or similar conditions, with typical wind induced currents, a sewage field travel distance of a few kilometres is sufficient to ensure bathing areas against infection, without the need for sewage disinfection. It should, however, be stressed that these conclusions are valid on the assumption that the sampling procedures outlined in the EU Directive refer to uniformly distributed sampling throughout the bathing period of the day or season.
Sedimentation of particles from jets discharged by ocean outfalls: a theoretical and laboratory study
Authors: Neves M. J. , Fernando H. J. S.
Published: May 2018

Usually, ocean outfalls dispose of wastewater by means of jets discharged by multiport diffusers. Although depending on the process of pre-treatment, the effluent contains particles that may settle in the vicinity of the diffuser, originating banks of sediments with undesirable environmental impacts.

This paper reports a study with theoretical and experimental components, on the sedimentation of particles from vertical round jets. It might be considered fundamental research, because it is expected to contribute for a better understanding of two-phase flows, but many practical applications can be referred, for instance, design of ocean outfalls, industrial chimneys, studies of sedimentation in lakes, volcanoes, etc.

The study provides practical criteria to predict the distance that particles will travel before settling, as well as their concentration on the ground.
Design and construction problems of a “big inch” outfall
Authors: Avanzini Carlo , Quirici Pierantonio
Published: May 2018

The increase in the population of cities and the formation of Great Metropolitan Areas has increased drastically the flow rates of waste water to the treatment plants. It means, in the coastal areas, an increase in diameter of the outfalls at the service of the treatment plants. Large diameter outfalls present design and construction problems of a different type and size to those of the smaller lines used until recently. The paper covers some of the problems encountered in the design and construction phases of so-called “big inch” outfalls.
The Üsküdar and Baltalimani sea outfalls of the Istanbul sewerage project: A construction case history
Authors: Sayinli Teoman , Yigit Selahattin
Published: May 2018

The Baltalimani (BL) and Üsküdar (Ü) Sea Outfalls are situated on two coasts of the Bosphorus and are 2×300 m and 270 m long with nominal diameter ⌈ 1727 mm and ø 1219 mm, respectively. These outfalls were constructed by the Alarko Company for ISKI in the years 1988-1993 to discharge the pretreated or treated waste waters to the bottom current of the Bosphorus.

The submarine pipelines have been installed by a) bottom pulling in the dredged trench, b) short launch-way (L/W) very close to the shore, c) pulling from the same coast via an anchored pulley in Ü, and d) pulling from the other coast of the Bosphorus in BL. Preparation of the pipes, comprising of corrosion coating, cathodic protection, assembly and concrete weight coating, was performed at the Kadìköy Site. Following dredging of the offshore trenches, bedding material was laid. Meanwhile the L/Ws were fabricated and erected. Installations of the pipelines were executed by placing the pipe sections on the L/Ws, making the field joints and pulling towards the sea into the trench. After testing, the submarine pipelines were covered; first with a layer of gravel then with a layer of armour stone and connected to the landline. Ü outfall was put into operation satisfactorily immediately upon completion.
Diffuser design for marine outfalls in areas with strong currents, high waves and sediment transport
Authors: Larsen Torben
Published: May 2018

The design of marine outfalls is often based on environmental criteria for a minimum initial dilution. Accordingly advanced diffuser arrangement are designed to fulfil these requirements. A large number of examples of malfunction and blocking in sea outfalls have occurred around the world as a result of this uncompromising consent to environmental demands. Two examples of unconventional design are given in this paper. Both cases involved risk of blockage of the diffuser section because of wave and current induced sediment transport. The paper also discusses how acceptable far field dilution conditions can be achieved even if normally accepted initial criteria are not fulfilled.
Case studies on preliminary treatment facilities at marine outfalls
Authors: Huber H. , Tanik A. B. , Gerçek M.
Published: May 2018

As with many coastal discharges, the search for a suitable primary treatment system has long been accepted as a first stage treatment of both municipal and industrial wastewater. Over the last decade, milliscreening has almost become the best alternative method among the conventional systems applicable to marine outfall treatment. This paper, summarizes three case studies using milliscreening equipment with variable bar spacings on treatment facilities at marine outfalls. The best solution was achieved at Poverty Bay in New Zealand where the bar spacing was 1 mm. The other two applications were attempted in United Kingdom. The milliscreens of 10 mm at Tonyrefail and 5 mm at Wooler were not able to meet the required performance. In regard of these studies, it is recommended that finer screens with bar spacing of less than 5 mm are likely to provide adequate performance when used to screen marine outfalls.
Use of constructed wetland to protect bathing water quality
Authors: Coombes C. , Collett P. J.
Published: May 2018

The European Bathing Water Directive imposes strict limits on the bacterial quality of waters used by the public for bathing.

At Thurlestone the site chosen for the sewage treatment works needed to improve bathing water quality is adjacent to a site of special scientific interest (SSSI), into which the treated effluent discharges. The effluent is required to be of a high bacteriological quality to protect the bathing water and high chemical quality to protect the SSSI.

South West Water Services (SWWS) in conjunction with their consultants, WS Atkins, designed and installed a horizontal flow Phragmites australis reed bed to give tertiary treatment to the effluent from a trickling filter plant. The media for the reed bed consists of crushed basalt and limestone chippings to try to maximise the phosphate removal from the effluent. The reed bed has been in operation for two years and produced an effluent of excellent quality soon after it was commissioned. Particular attention has been paid to bacteria removal. Total and faecal coliform removal have averaged two logs. Suspended solids and biochemical oxygen demand have averaged less than 5 mg/l in the effluent, with removals greater than 75%. Ammoniacal nitrogen has averaged less than 2 mg/l. The bathing water into which the effluent eventually discharges has not failed the Directive criteria since the works was commissioned.
Domestic wastewater treatment through constructed wetland in India
Authors: Juwarkar A. S. , Oke B. , Juwarkar A. , Patnaik S. M.
Published: May 2018

The paper highlights the use of constructed wetlands for the removal of BOD, nitrogen, phosphorus and pathogens from primary treated wastewater. The constructed wetland consists of emergent macrophytesTypha latifolia and Phragmites carca grown in cement pipes having 0.1256 m2 area and 0.8 meter deep filled with 30% soil and 70% sand. The hydraulic loadings were maintained at the rate of 5 cm per day.

The BOD removal in wetlands was observed to be 78-91%. The nitrogen content reduced from 30.8 mgl−1 to 9.5 mgl−1 whereas phosphate in treated wetland effluent was 9.6 mgl−1 as against the mean inflow total phosphate content of 14.9 mgl−1.

The country’s first constructed wetland, of 90m × 30m size, was installed at Sainik School, Bhubaneshwar in the State of Orissa. Two types of macrophytes, viz. Typha latifolia and Phragmites carca, were planted. At present 180-200 m3 wastewater is being treated through wetland. BOD and nitrogen removal were 67-90% and 58-63% respectively.

The constructed wetland treatment was found to be efficient in removal of BOD and N, and economically viable. The system, being easy to operate and low cost, can provide an economical viable solution for wastewater management.
Light as a selective factor in the distribution of phytoplankton species
Authors: Mur L. R. , Schreurs H.
Published: May 2018

Cyanobacteria are most often the dominant group of organisms in the phytoplankton of eutrophied freshwater lakes. In the first section the distribution of cyanobacterial populations in the Netherlands was described in relation to depth, chlorophyll concentration and average light climate. Long term dominance in shallow lakes was mainly caused by Oscillatoria like organisms. Microcystis was found to be dominant in deeper lakes. Although the dominance of Oscillatoria was closely related with high chlorophyll concentrations, the relation between the Oscillatoria dominance and the average underwater light climate was not clear. A good explanation could not be given. In the second section the dominance of Oscillatoria was followed during the restoration of three lakes. Here it was found that in two shallow lakes of different depth Oscillatoria disappeared from the epilimnion at a Zeu/Zm value of 0.4. This is in good agreement with competition experiments done in the laboratory. The stratified population of Oscillatoria rubescens disappeared from the metalimnion at a Zeu/Zm ratio of 1.2. This fitted also with the physiological information.
Competitive growth of blue-greens and diatoms (fragilaria) in the saidenbach reservoir, saxony
Authors: Horn H. , Uhlmann D.
Published: May 2018

Since 1975, different patterns of the growth of Fragilaria and Cyanobacteria in the mid or late summer have been observed in the Saidenbach Reservoir. In most of the years, there was a mutual exclusion of mass growths of these two groups. High yields of Fragilaria caused low yields of blue-greens and vice versa. In the first years, Fragilaria was always the first to achieve a mass growth, followed by the Cyanobacteria. Then, in the last years, the blue-greens were succeeded by Fragilaria. Only in some years, there was a large and simultaneous growth of both groups. It has been shown, that the supply of silicon and phosphorus immediately before controlled the pattern of succession in the midsummer period. Mostly, the Si:P ratio was the regulating factor, but there were also years in which the absolute concentration level of these two nutrients were either non-limiting high or below the minimum resource concentration necessary to compensate for the losses. In these cases, the Si:P ratio lost its controlling function. Other influencing factors are discussed, in particular the effect of turbulent mixing. The special nutrient conditions in the midsummer were not only determined by the external load but also by the Si depletion during the spring mass development of diatoms other than Fragilaria, which mostly is physically controlled. Therefore, the succession pattern in the midsummer is sensitive to the meteorological conditions to a large extent.
The microwaterscape - a four-dimensional view of interactions among water chemistry, phytoplankton, periphyton, macrophytes, animals and ourselves
Authors: Moss B.
Published: May 2018

Over a wide range of nutrient loadings or concentrations shallow lakes appear to have two main alternative states - clear water, macrophyte-dominated and turbid, phytoplankton-dominated, each with numerous detailed variants. This model is reviewed in terms of defining the problem, broad understanding, detailed understanding and wider meaning. For the former two, our information is reasonably good but there are many details yet to be investigated. Some aspects of this are the mechanisms by which plant beds may act as refuges for grazer Cladocera such as daphnids, the role of non-daphnid (plant-associated) Cladocera in grazing phytoplankton, the role of periphyton grazers and the detailed influence of mixed fish communities in predation. Finally it is suggested that the model has analogies in alternative ways of organising human communities and offers guidance in managing future human affairs.
Interaction of detritus with abundance of cyanobacteria and microalgae
Authors: Gons Herman J.
Published: May 2018

Detritus particles interact with phytoplankton growth through light attenuation and nutrient retention. A model is described for predicting abundance of cyanobacteria and microalgae in relation to the detritus dynamics in shallow lakes with varying phosphorus load. Steady-state P distribution among cyanobacterial biomass, detritus and the dissolved pool depending on mortality and detritus mineralisation rate was predicted from kinetics for P-limited growth and refractory fraction of the detritus. The depth-averaged irradiance was computed for a constant background attenuation and specific attenuation coefficients of biomass and detritus estimated from field and laboratory data. This light was compared to the light critical to net growth of microalgae based on initial slope of growth vs. irradiance relationship, maximal growth rate and constant maintenance rate. It was predicted that the probability of abundance of microalgae relative to that of cyanobacteria is high at low population loss rates, coinciding with the lowest depth-averaged irradiances at a particular P load. This prediction is consistent with observations on many shallow lakes.
Competition for nutrients and light among phytoplankton species in a mixed water column: theoretical studies
Authors: Huisman J. , Weissing F. J.
Published: May 2018

A brief overview is given of modelling studies that aim to analyse the effects of nutrient and light limitations on the development of phytoplankton communities and lead to a qualitative understanding of the competitive interactions involved.
Long-term changes in fish pond management as ‘an unplanned ecosystem experiment’: importance of zooplankton structure, nutrients and light for species composition of cyanobacterial blooms
Authors: Pechar L.
Published: May 2018

The study presents data on the species composition of cyanobacterial water blooms in Czech fish ponds from the 1950s to the 1990s. Since the 1950s, a shift from large-colonial Aphanizomenon flos-aquae var. flos-aquae through Microcystis aeruginosa and small-colonial species of Anabaena to single-filament species (Planktohrix agardhii, Limnothrix redekei, Aphanizomenon gracile) or single-cell forms (Microcystis ichtyoblabe), has been observed. The changes in the species composition of the water blooms are closely related to changes in fishery management (increase in fish stock, increase in application of organic fertilizers). At present the high predation of fish upon zooplankton results in elimination of large colonial blooms of A. flos-aquae associated with large filtering zooplankton (Daphnia). Low grazing pressure of zooplankton, low light conditions and low N:P ratios are suitable conditions for mass development of the small species of cyanobacteria. High pH is not necessary to achieve cyanobacteria dominance.
Organic near-bed fluid and particulate transport in combined sewers
Authors: Ristenpart E. , Ashley R. M. , Uhl M.
Published: May 2018

Studies in Germany, Belgium, France and Scotland have revealed that there are significant solids transport gradients in the depth of foul and combined sewage flows. Continuous field observations of changes in depths of sediment deposits in combined sewers have also indicated that there is an interaction between the erosion and deposition processes and changes in the mass transport of solids in regions in the overlying flow. A fuller understanding of the interactive phenomena is essential for both sewer sediment management and the minimization of associated pollution from wash-out of solids via CSOs. The paper presents results from the detailed studies in Hildesheim, Germany and those carried out in Dundee, Scotland, investigating the heterogeneity of solids movement with regard to gross solids, erosion of sewer sediments and their interactions with the suspended transport phases and the layer of very dense fluid found to be transported under certain circumstances, near the sediment bed or sewer invert (traditionally called ‘bed-load’).
Sediment properties and their changes in a sewer
Authors: Ristenpart E.
Published: May 2018

The inhomogeneity of sewer sediment bed material in terms of physical and pollution characteristics is known. To quantify the variations over time and depth of bed deposits an extensive study investigating the properties of bed deposits in a combined interceptor sewer in the city of Hildesheim was carried out. High temporal variations as well as vertical gradients of bed characteristics were found especially for pollution characteristics (chemical and biochemical oxygen demand) and volatile solids content; physical parameters (bulk density, total solids content) appeared to vary less. The fluctuations were related to degradation processes in the sediment bed and exchange processes between bed deposits and sewage.
Microbiological features of nitrification-denitrification biological excess phosphorus removal systems in the presence of oNP as an inhibitor
Authors: Topalova Y. , Ribarova I. , Dimkov R. , Arsov R.
Published: May 2018

The ecolog-microbiological structure of activated sludge in nitrification-denitrification biological excess phosphorus removal (NDBEPR) systems in classic version with real wastewaters and in the presence of inhibitor o-nitrophenol (oNP) has been investigated. The amount of the essential physiological groups microorganisms (aerobic-heterotrophic, nitrifying, denitrifying, phosphorus removing bacteria (Poly P, Poly P denitrifying), nitrophenols-degrading and heterotrophic ammonia releasing bacteria) has been defined in the presence of low and high oNP-concentrations. The dynamics of activated sludge microbial structure has been discussed in effect on treatment efficiency towards different parameters – COD, PO43− elimination, ammonia-oxidation, oNP elimination.

The results show that oNP decreases efficiency of biotreatment from 26% to 80% with the increasing of oNP concentration from 9.35 to 85.44 mg/l. The large flexibility and compensative possibilities of AS structure in NDBEPR systems have been established. The amount of poly P and oNP degrading bacteria is increased at high oNP concentration (85.44 mg/l). These microbial groups play the important buffer role for stabilization of BEPR in the presence of inhibitor, as well as for the biodetoxication of oNP.
A legislative initiative for the protection of Black Sea water from industrial indirect discharges
Authors: Paskalev Atanas , Dimova Galina
Published: May 2018

The legislative initiative is an attempt for elaboration of a programme for control of the industrial wastewaters before their discharge into the sewerage.

A short review of the existing Bulgarian legislation related to the ecological problems of the Black Sea is presented. The main problems obstructing the practical implementation of the laws and the regulations are analysed.

In outlining the approach for control of the industrial discharges, special attention is paid to the necessity of theoretically sound and economically substantiated limits on the discharged wastewaters, extension of the regional authorities' activities on pollution control and involving the municipal Waste Water Treatment Plants (WWTPs) in the wastewater treatment management.

The paper gives directions for the future development of a Black Sea Environmental policy, related to industrial indirect discharges at international, state and regional levels.
Lakes and reservoirs: reflecting waters of sustainable use
Authors: Matsui S. , Ide S. , Ando M.
Published: May 2018

The International Lake Environment Committee (ILEC) has been conducting, in cooperation with the United Nations Environment Programme (UNEP), a project entitled the “Survey of the State of World Lakes” since 1986 with the aim of collecting and compiling environmental data on as many important lakes and reservoirs of the world as possible to be used as the basis for environmentally sound management of lakes. The results so far obtained from the survey have been published in five volumes as the “Data Book of World Lake Environments”, which contain sets of detailed data on 217 lakes from 73 countries all over the world. The survey carried out by ILEC and UNEP illustrated that the following six major environmental problems are now widespread among lakes and reservoirs around the world, leading to a crisis of water resources and aquatic ecosystems: 1) Lowering of water level, 2) Rapid siltation, 3) Acidification, 4) Toxic contamination, 5) Eutrophication, and 6) Extermination of ecosystems and biota. A preliminary analysis on surveyed lakes and reservoirs also demonstrated some interesting correlations between 1) the volume of lake water and transparency, 2) suspended solids concentrations and the ratio of forest area to the whole catchment area, 3) suspended solids concentrations and the area of farmlands in the catchment area per unit volume of lake water, and 4) total nitrogen and total phosphorus concentrations in lake water, indicators of the degree of eutrophication, and the catchment area population per unit volume of lake water.
Bacteriology of urban runoff: the combined sewer as a bacterial reactor and generator
Authors: Ellis J. Bryan , Wang Yu
Published: May 2018

Combined Sewer Overflows (CSOs) are widely recognised as being a primary source of faecal pollution indicator bacteria and pathogens to urban receiving waters. The discharge and in-stream accumulation of sediments from CSOs have also been considered to constitute a bacterial reservoir yielding a continuous inoculation to the receiving water. This paper reports the findings of a microbiological study of CSO discharges and sediments within a N London urban catchments focusing on bacterial indicators (Total and Faecal Coliforms, Faecal Streptococci and pathogens) and the role of somatic coliphages in typing sewage pollution. Evidence is provided for both extended in-stream bacterial survival and bacterial generation in the presence of nutrified organic sediment.
Molecular methods to study the organization of microbial communities
Authors: Muyzer Gerard , Ramsing Niels B.
Published: May 2018

This review describes the potentials and limitations of different molecular techniques which are nowadays used to determine the species composition of microbial communities, and to study the spatial distribution of their inhabitants.
Solids retention time in heterotrophic and nitrifying biofilms in a biofilm airlift suspension reactor
Authors: van Benthum W. A. J. , van Loosdrecht M. C. M. , Tijhuis L. , Heijnen J. J.
Published: May 2018

The solids retention time in biofilms was determined by using fluorescent microbeads as solid tracers. Attachment to and detachment from the biofilms, as well as surface concentration of the microbeads were measured. The surface concentration depended on the surface characteristics of the biofilms. The attachment rate was equal in three experiments and dependent on hydrodynamic conditions in the reactor. In all cases the detachment rate was much smaller than the attachment rate and larger than the average solids retention time of the active biomass. Release of the beads was determined by local, nonuniform detachment phenomena. Microbeads were observed to penetrate into the biofilms. This is not in accordance with conventional biofilm models. Therefore a new biofilm model concept is proposed. The biofilm is a dynamic structure, in which formation of cracks and fissures is taking place continuously. The crevices are filled with fresh biomass rapidly and particulates which are present are entrapped inside the biofilm.
Dynamic changes in spatial microbial distribution in mixed-population biofilms: experimental results and model simulation
Authors: Okabe Satoshi , Hirata Kikuko , Watanabe Yoshimasa
Published: May 2018

Dynamic changes in spatial microbial distribution in mixed-population biofilms were experimentally determined using a microslicer technique and simulated by a biofilm accumulation model (BAM). Experimental results were compared with the model simulation. The biofilms cultured in partially submerged rotating biological contactors (RBC) with synthetic wastewater were used as test materials. Experimental results showed that an increase of substrate loading rate (i.e., organic carbon and NH4-N) resulted in the microbial stratification in the biofilms. Heterotrophs defeated nitrifiers and dominated in the outer biofilm, whereas nitrifiers were diluted out in the outer biofilm and forced into the inner biofilm. At higher organic loading rates, a stronger stratified microbial spatial distribution was observed, which imposed a severe internal oxygen diffusion limitation on nitrifiers and resulted in the deterioration of nitrification efficiency. Model simulations described a general trend of the stratified biofilm structure. However, the actual stratification was stronger than the simulated results. For implication in the reactor design, when the specific carbon loading rate exceeds a certain limit, nitrification will be deteriorated or require a long start-up period due to the interspecies competition resulting in oxygen diffusion limitation. The extend of microbial stratification in the biofilm is especially important for determination of feasibility of nitrification in the presence of organic matters.
The role of non-point nutrient sources in water pollution - present situation, countermeasures, outlook
Authors: Werner W. , Wodsak H.-P.
Published: May 2018

In a recent estimation of the quantitative importance of diffuse and point sources on the nitrogen and phosphorus pollution of surface waters in both parts of Germany just before the reunification, the share of the diffuse sources on the total input was found very similar in the case of N (56 and 57%), but different in the case of P (42% in the old FRG and 33% in the former GDR). The diffuse N and P inputs are dominated by the joint pathways ground water/drain water and soil erosion/surface run off, respectively. The reduction of the diffuse pollution potential until 1995 (compared to 1987/89) is estimated with about 18% for N and 30% for P. This is far below the governmental target of a 50% reduction in the period 1985 to 1995.

The reasons, why the up-to-now success of the different countermeasures against diffuse water pollution with N and P from agriculture is still unsatisfactory are discussed. Demands for an accelerated implementation of efficient countermeasures have to be addressed by both farmers and politicians.
The chesapeake bay story: the science behind the program
Authors: Shuyler L. R. , Linker L. C. , Walters C. P.
Published: May 2018

The Chesapeake Bay Program (CBP) is based on good science and high quality data. This has allowed the program to set and implement meaningful goals. The research phase resulted in the “1983 Chesapeake Bay Agreement”, which called for the jurisdictions to focus existing pollution control programs on reducing the nutrient loads to the Bay. A second “Bay Agreement” was developed and signed by the jurisdictions in 1987. This agreement contained 27 specific goals including a Basinwide Nutrient Reduction Strategy to reduce “1985 controllable” nutrient loads to the Bay by 40 percent in the year 2000. To assure high quality monitoring data, CBP established a strong quality assurance and quality control procedure which is used for all monitoring. To assist with the monitoring a computer program, “Chesapeake Bay Automated Monitoring System” was developed to evaluate the quality of field and laboratory data and to allow the data to be directly loaded into the CBP computers. The Chesapeake Bay Program Office developed models for the drainage basin and the water of the Bay. The watershed model simulates the pollutant loads from eight land uses, the majority of the point sources and atmospheric deposition. It processes these loads through the river systems and delivers the load to the Bay for use in the Bay model. The Bay model uses these loads and adds atmospheric deposition, loads from the ocean interface and loads from bottom sediments to simulate water quality data at all points in the Bay. The models were used to confirm that the 40% nutrient reduction goal was correct, resulting in an amendment to the 1987 Agreement, calling for a commitment by the jurisdictions to develop tributary specific strategies to reach the goal. The tributary strategies lay out the future goals and direction that must be taken to reach the nutrient reduction goals. These tributary strategies are being evaluated by the program office, using the models. The results of the evaluation and model simulation of the implementation progress in the basin are discussed along with the economic implications of reaching these goals.
Changes of biofilm properties in response to sorbed substances - an FTIR-ATR study
Authors: Schmitt Jürgen , Nivens David , White David C. , Flemming Hans-Curt
Published: May 2018

Biofilms play an important role as sorbents in the process of distribution of pollutants in surface water systems. The sorption properties of biofilms will influence the kind and the amount of sorbed substances. The heterogeneity of biofilms provides different sorption sites which exhibit a different sorption preference and capacity. As dynamic systems, biofilms will respond physiologically to their environment. Thus, the sorption of one substance may lead to a change in the composition of the EPS or other biofilm components and further alter the original sorption properties. In this paper, the influence of toluene on a biofilm was investigated. As a suitable method, FTIR-ATR spectroscopy was applied. The method is non destructive and allows the observation of biofilm formation and behaviour on line and in situ. A biofilm was allowed to form in ATR flow-through cells. The test strain was genetically engineered and contained a bioluminescent reporter gene which was switched on when toluene was metabolized. Thus, the degree of toluene degradation activity could be observed with great sensitivity. The FTIR spectrometer contained three flow-through cells which could be operated in parallel: one was run with sterile medium only, one with medium and bacteria, and one with medium, bacteria and toluene. This arrangement allowed the discrimination of the biofilm response from other effects. The IR spectrum showed specific bands of proteins, polysaccharides, phosphoryl compounds and other groups of molecules. A significant increase of EPS-polysaccharide formation was observed at a toluene level of 5 mg L−1. At 15 mg L−1, significantly more carboxyl groups were formed. Thus, the effect of the lipophilic organic pollutant toluene increased the amount of negatively charged groups and, consequently, the sorption capacity for metal cations. This result indicates that biofilms respond in a complex manner to different sorbates and alter their environmental properties.