bluuebunny/crossref_metadata_2025 huggingface dataset:
Operating experiences with submerged filters for nitrification and denitrification
Authors: Meaney B. J. , Strickland J. E. T.
Published: May 2018

A bioreactor has been developed utilising floating plastic granules with a density close to water. The reactor can be either aerated or non-aerated and can be used for nitrification, denitrification or solids removal. Particular applications are in tertiary treatment to achieve suspended solids levels below 10 mg/l and ammonia levels below 5 mg/l, and in a pre-denitrification mode to reduce nitrate levels in effluent from bacteria bed works in order to comply with the UWWTD.
Pre- or post-denitrification at biological filter works? A case study
Authors: Dee A. , James N. , Jones I. , Strickland J. , Upton J. , Cooper P.
Published: May 2018

Pilot plant studies were conducted to evaluate the use of pre-denitrification for nitrogen removal at low-rate biological filter works. The plant was operated over a range of recycle ratios to determine the optimum operating conditions. It was possible to meet a total nitrogen limit of 15 mg TN/l with a 2:1 ratio of recycled filter effluent to settled sewage. Following the studies, an economic comparison was made to compare the costs of pre-denite plant with post-denitrification in tertiary sand filters. The cost-effectiveness of the pre-denite process depended on the price of the external carbon source used in post-denite plant. Biological fluidised beds were shown to be the most cost-effective type of pre-denite plant.
Determination of optimal biofilm activity in a biological fludized bed (BFB) reactor
Authors: Ruggeri B. , Caire G. , Specchia V. , Sassi G. , Bosco F. , Gianetto A.
Published: May 2018

Experimental tests were carried out in order to ascertain the biomass activity in a biological fluidized bed reactor. A semi-pilot fluidized bed reactor was used with two different supports (sand and glass particles). The specific biomass activity was followed during the tests. It reached a maximum and after declined vs. biomass hold up and bed expansion. The results clearly put in evidence as the activity is strongly effected by liquid-solid mass transfer and support roughness which in turn determines the compactness of biofilm and its diffusive properties. By controlling the bed expansion it is possible to decide the macro reaction regime of work: external mass transfer, biokinetics or diffusive control according to incoming substrate concentration, in order to maximize the bioreactor performance.
Interactions between the biofilm growth and the hydrodynamics in an aerobic trickling filter
Authors: Lekhlif B. , Toye D. , Marchot P. , Crine M.
Published: May 2018

We analyse the interactions between the biofilm growth and the liquid flow distribution in a trickling filter. Experiments are carried out on 0.5 m3 pilot scale reactor. We determine both the liquid flowrate distribution by local measurements and the filter performance by measuring the conversion. The liquid superficial flowrate ranges between 0 and 0.9 m/h. The synthetic effluent consists of a water solution of beet molasses and potassium dihydrogenophosphate. The hydrodynamic modelling allows us to relate the characteristics of the liquid flow distribution and the reactor performance to a single set of packing parameters. The packing irrigation rate plays a key role. Our results confirm the definite effect that the biofilm activity may have on the quality of the liquid flow distribution.
Application of biofilm theory to the prediction of sulfide production from bioslimes
Authors: Holder G. A.
Published: May 2018

The problems caused by the formation of sulfide within sewerage systems are briefly reviewed. The mechanism by which the hydrogen sulfide is produced within sewers and the procedures for controlling its production are briefly outlined. In order to design effectively for sulfide control a reliable means of predicting the rate of sulfide production is desirable. The different procedures which have been developed in Australia, the United Kingdom and the U.S.A. (i.e. the equations developed respectively by Thistlethwayte, Boon and Lister, and Pomeroy) are, however based on empirical correlations of experimental data, and hold over a limited range of operating conditions. These procedures are also known to be unreliable. The desirability of replacing the present procedures by a more rational approach is demonstrated. A major advantage of the new approach, which is based upon a chemical engineering analysis of the mass transport and biochemical processes which occur, is that, whereas the previous procedures were developed essentially for domestic sewage, the more rational approach can be applied to sewage containing a high proportion of industrial effluent.
Towards a universal stormwater management practice for arid zone residential developments
Authors: Argue John R.
Published: May 2018

The principal centres of research and development in stormwater management are in the World's temperate regions for which a wide range of best practices are already known. The article suggests a strategy for improving performance in urban flood control, pollution minimisation and stormwater harvesting in arid/semi-arid regions. The basis of the approach is, firstly, systematic documentation of performances in strategic project cases – by regions – followed by integration of these into a universal best practice. A documentation matrix for stormwater management cases in Adelaide, South Australia, is described. Factors considered in the matrix include devices and treatments, development types and forms, aquifer recharge capability and soil types. The matrix will provide, progressively, vital information for planners and designers and guide researchers in the most productive use of limited monitoring resources.
Biodegradation of naphthalene in montmorillonite/polyacryamide suspensions
Authors: Magdaliniuk S. , Block J. C. , Leyval C. , Bottero J. Y. , Villemin G. , Babut M.
Published: May 2018

The biodegradation of naphthalene in the presence of Na montmorillonite particles, of montmorillonite/polyacrylamide complexes and of polyacrylamide alone was studied in batch assays under aerobic conditions. The concentrations of naphthalene used were below aqueous phase saturation. Adsorption-desorption experiments with montmorillonite and montmorillonite/polyacrylamides complex indicated that little or no naphthalene was adsorbed. Adsorption appeared totally reversible and desorption was rapid, reaching completion in less than 24 hours. Naphthalene was rapidly degraded by an adapted strain of Pseudomonas cepacia (10-25 hours) as a function of the initial viable bacteria count of the inoculum. The kinetics of naphthalene degradation in the presence of montmorillonite/polyacrylamide complexes or even with montmorillonite alone (with no naphthalene adsorbed), were slower (0.64 mg l−1 h−1) than in clayless aqueous solution (0.84 mg l−1 h−1). Dissolved non-biodegradable polyacrylamide had no effect on naphthalene degradation. These results indicate that particles decrease the rate of naphthalene breakdown byPseudomonas cepacia . This may be caused by the fact that montmorillonite particles are smaller on average than bacteria cells. Montmorillonite particles may cover bacteria and so limits nutrient mass transfer.
Optimisation of retention basin decanting
Authors: Bourgogne Pierre , Chorda Jacques
Published: May 2018

The cleaning of rainwater is a big challenge for the coming years. Numerous experiments are undertaken, especially in the field of elutriation. The option of decanting gives the most interesting results in the elimination of this particular kind of pollution.

By contributing to such research activity, the Bordeaux Urban Community Council wishes to develop a new type of settling basin, enabling an efficient decanting process, a good removal of pollution, as well as easy maintenance, without having to use sophisticated equipment.
Simultaneous removal of organic materials and nitrogen by micro-aerobic biofilms
Authors: Watanabe Y. , Okabe S. , Hirata K. , Masuda S.
Published: May 2018

Simultaneous nitrification with denitrification was investigated using a single rotating biological contactor (RBC). The authors proposed two means to achieve simultaneous nitrification with denitrification in the single reactor: (1) to control oxygen transfer rate by reducing oxygen partial pressure (P02) in the air phase and (2) to develop a combined partially (aerobic) and fully (anaerobic) submerged RBC (CPFSR) reactor. For the former experiment, the maximum denitrification efficiency of 90 % was obtained at C:N ratio=6 and P02=0.10 atm. Moreover, heterotrophs, NH4- and NO2-oxidizers, and denitrifiers were distributed throughout the biofilm, suggesting that nitrification and denitrification can occur wheresoever the local environment meets their growth conditions. For the latter experiment, effects of type of organic matter and influent carbon:nitrogen ratio (C:N ratio) on the efficiency of simultaneous nitrification with denitrification were investigated using the CPFSR reactor. Acetate, ethylene-glycol, phenol, and poly-vinyl-alcohol (PVA) were used as carbon sources for denitrification. An excellent nitrification efficiency was obtained for all experimental runs and all organic substrates could be degraded and used for denitrification, indicating a great potential for simultaneous removals of nitrogen and xenobiotic compounds by the CPFSR reactor.
A grey nonlinear programming approach for planning coastal wastewater treatment and disposal systems
Authors: Ni-Bin Chang , S. F. Wang
Published: May 2018

Coastal wastewater treatment and ocean outfall facilities are usually planned as two separate subsystems in the conventional design strategy. However, the technical efforts in planning these subsystems can be combined by considering the minimization of system costs and the maximization of utilization rate of environmental assimilative capacity. But the system uncertainties should be further addressed in the modelling framework as the variations of environmental factors become significant. The grey systems theory is found to be an effective tool to modify the deterministic models. Therefore, a grey nonlinear programming model is developed in this paper to support such an uncertainty analysis. The case study of the Guishuic wastewater treatment and disposal project in Taiwan is used as a numerical demonstration.
Distribution and bioaccumulation of heavy metals from produced water discharges to the gulf of Mexico
Authors: Trefry John H. , Naito Kelly L. , Trocine Robert P. , Metz Simone
Published: May 2018

Produced water, the largest volume waste generated during production of offshore gas and oil, is typically discharged into the ocean at the sea surface. Concentrations of some heavy metals, such as Cd, Pb, Fe and Ba, are enriched in produced water from the Gulf of Mexico relative to ambient seawater by factors of about 10 to >10,000. In contrast, concentrations of other metals in produced water, including Hg, Ni and V, are generally close to or less than those in seawater. Concern for enhanced bioaccumulation of metals from water surrounding oil platforms was addressed by analyzing mollusks collected within 10 m of the discharge pipe. No statistically significant differences in tissue levels of Ba, Cd, Hg, Ni, Pb or V were identified for clams (Chama macerophylla) or oysters (Crassostrea virginica) collected from production platforms with variable loadings of heavy metals. Sediment in discharge areas from the Gulf of Mexico often had elevated levels of Pb and Ba relative to Al; however, such enhancement is unlikely to be solely related to produced water.
Bacterial die-away rates in red sea waters
Authors: Sarikaya H. Z. , Saatçi A. M.
Published: May 2018

Total coliform bacteria have been chosen as the indicator organism. Coliform die-away experiments have been carried out in unpolluted sea water samples collected at about 100 m off the coastline and under controlled environmental conditions. The samples were transformed into one litre clean glass beakers which were kept at constant temperature and were exposed to the solar radiation. The membrane filter technique was used for the coliform analysis. The temperature ranged from 20 to 40° C and the dilution ratios ranged from 1/50 to 1/200.

Coliform decay rate in the light has been expressed as the summation of the coliform decay rate in the dark and the decay rate due to solar radiation. The solar radiation required for 90 percent coliform removal has been found to range from 17 cal/cm2 to 40 cal/cm2 within the temperature range of 25 to 30° C. Applying the linear regression analysis two different equations have been given for the high (I>10 cal/cm2.hour) and low solar intensity ranges in order to determine the coliform decay rate constant as a function of the solar intensity.

T-90 values in the light have been found to follow log-normal distribution with a median T-90 value of 32 minutes. The corresponding T-90 values in the dark were found to be 70-80 times longer. Coliform decay rate in the dark has been correlated with the temperature.
Respirometry as a tool for rapid characterization of wastewater and activated sludge
Authors: Spanjers Henri , Vanrolleghem Peter
Published: May 2018

A procedure is presented to estimate biokinetic parameters for heterotrophic and autotrophic process models and to estimate wastewater characteristics in the context of the Activated Sludge Models No. 1 and No. 2. The procedure is based on respirometric measurements at low substrate to biomass ratio (S/X). The addition of nitrification inhibitor is avoided by applying a calibrated nitrification model to the respiration rate data resulting from both heterotrophic and autotrophic degradation. Furthermore, a new procedure is developed for simultaneous assessment of decay coefficients for heterotrophic and autotrophic biomass. The results show that, for a given wastewater/sludge combination S/X can be crucial in obtaining reliable parameter estimates: at a very low ratio not all parameters could be identified. A higher ratio caused problems because of nitrification inhibition.
Improvement of a recirculating plant by introducing star control
Authors: Nielsen Marinus K. , Önnerth Tine B.
Published: May 2018

During the last 20 years, control of wastewater treatment plants has developed from very simple to advanced computer control methods based on on-line measurements. Fortunately, both on-line equipment and computer system technology are still developing fast and have become applicable at WWTPs. The use of on-line measurements for real time control is advantageous at most plants over 15.000 personal equivalent performing biological nutrient removal. Control strategies have demonstrated their efficiency at several Scandinavian wastewater treatment plants. Experience shows that the applied control strategies are efficient and robust for practical implementation, provide savings in energy and chemical consumption and decreases the nitrogen content in the effluent. Experience from a recirculating BNR plant using the STAR concept for advanced real time control is described. The on-line nutrient measurements and excitation of the processes through control strategies have improved the process understanding. Control has reduced the consumption of energy by about 30% and eliminated the need for external carbon addition, as well as improved the effluent quality of total nitrogen from the plant. The new measurements and data handling methods will make it possible to perform dynamic identification of activity in recirculating plants (Nielsen et.al., 1994), and hence give information as to which control strategies improve the biomass activity or favour desired cultures of micro-organisms.
Saline intrusion in deep riser outfall systems
Authors: Howard Roger A.
Published: May 2018

Saline intrusion can seriously affect the performance of outfall systems and an understanding of the mechanisms causing intrusion is important in the hydraulic design of outfalls, particularly for deep riser tunnelled outfalls. The paper outlines the reasons for the occurrence of saline intrusion, the problems that arise when it is present and the methods available for prevention and purging. The paper draws on recent work undertaken on the design of a major deep tunnel outfall system using a physical model and outlines some novel methods devised for purging of the system.
Problems related to an existing marine outfall: Marmaris - an example
Authors: Samsunlu A. , Akça L. , Uslu O.
Published: May 2018

Marmaris is a tourist city on the South-west Coast of Turkey. A sewage disposal project for Marmaris with an estimated population of 39,000 (excluding the temporary tourist population) for the year 2012, was completed in 1982. The sewage disposal system consisted of wastewater collection, treatment and deep sea discharge. The length of discharge pipe was determined as 520 m and a diffuser was placed 20 m below the sea level, so that the total coliform concentration at the protection zone boundary could be less than 1000/100 ml.

Following the approval of the project, a wastewater collection and marine disposal system was constructed. The material of the discharge pipe was selected as glass reinforced plastic (GRP). The pipe was buried up to a point 10 m below sea level, so that effects of hydrodynamic forces would be minimized. After that point, the pipe was supported at some location by grout bags due to the uneven sea bed. A few years later, it was recognized that the discharge pipe was broken. The fragile GRP material had fractured as a result of the sliding of some of the supports with resultant free spanning conditions. As a result, the pipe had broken at one point. Although the breakage was repaired, recent data have shown that the water quality in Marmaris Bay has a tendency to be worsening; consequently, adding biological treatment units to the present system is advisable.
Monitoring of sewage outfalls in northern spain: preliminary studies of benthic communities
Authors: Juanes José A. , Canteras Juan C.
Published: May 2018

Baseline studies constitute, at the same time, the base and the reference point for the development of site-specific monitoring programs. As a previous step in the analysis of the structure of benthic communities in the infralitoral off Avilés and Gijón, multivariate techniques were used to assess the agreement between the distribution pattern of samples, from both rocky and soft bottom benthos, according to their species or family compositions.

Sampling was carried out in summer 1992. Stations were located on a depth gradient basis (A: −1 m; B: −5 m; C: −15 m; D: −25 m; E: −35 m; F: −45 m) along eight transect lines. Abundance data from replicate samples from each station, aggregated at both the species and the family levels, were tested by three complementary multivariate measures of community structure: clustering (CL), principal components analyses (PCA) and multidimensional scaling (MDS) techniques.

The main results obtained in this study demonstrated the adequacy of family-based abundance data for carrying out classification and ordination of samples from both rocky and soft bottom benthic ecosystems.
Dilution studies on three marine outfalls in South Africa
Authors: Botes Willem A. M. , Kapp J. F.
Published: May 2018

Field dilution studies were conducted on three “deep” water marine outfalls located along the South African coast to establish the comparibility of actual achievable initial dilutions against the theoretical predicted values and, where appropriate, to make recommendations regarding the applicability of the different prediction techniques in the design of future outfalls.

The physical processes along the 3000 km long coastline of South Africa are diverse, ranging from dynamic sub-tropical waters on the east coast to cold, stratified stagnant conditions on the west coast. Fourteen existing offshore marine outfalls serve medium to large industries and various local authorities (domestic effluent). For this investigation three outfalls were selected to represent the range of outfall types as well as the diversity of the physical conditions of the South African coastline.

The predicted dilutions, using various approaches, compared well with the measured dilutions. It was found that the application of more “simple” prediction techniques (using average current velocities and ambient densities) may be more practical, ensuring a conservative approach, in pre-feasibility studies, compared to the more detailed prediction models, which uses accurate field data (stratification and current profiles), when extensive field data is not readily available.
Enhancement of nitrogen removal in subsurface flow constructed wetlands employing a 2-stage configuration, an unsaturated zone, and recirculation
Authors: White Kevin D.
Published: May 2018

Constructed wetland technology is currently evolving into an acceptable, economically competitive alternative for many wastewater treatment applications. Although showing great promise for removing carbonaceous materials from wastewater, wetland systems have not been as successful at nitrification. This is primarily due to oxygen limitations. Nitrification does occur in conventional wetland treatment systems, but typically requires long hydraulic retention times. This paper describes a study that first evaluated the capability of subsurface flow constructed wetlands to treat a high strength seafood processor wastewater and then evaluated passive aeration configurations and effluent recirculation with respect to nitrogen treatment efficiency. The first stage of a 2-stage wetland treatment system exhibited a relatively short hydraulic retention time and was designed for BOD removal only. The second stage wetland employed an unsaturated inlet zone and effluent recirculation to enhance nitrification. Results indicate that organic loading, and thus BOD removal, in the first stage wetland is key to optimal nitrification. Passive aeration through an unsaturated inlet zone and recirculation achieved up to 65-70 per cent ammonia nitrogen removal at hydraulic retention times of about 3.5 days. Inlet zone configuration and effluent recirculation is shown to enhance the nitrogen removal capability of constructed wetland treatment systems.
The nutrient retention by ecotone wetlands and their modification for Baiyangdian lake restoration
Authors: Chengqing Yin , Zhiwen Lan
Published: May 2018

Shallow and eutrophic Baiyangdian Lake is a decaying lake and has broad ecotone wetlands, composed of reed communities and ditches. Experiments were carried out to study the fate of nutrients and organic pollutants during the runoff, flowing from a contaminated river through the ecotone to the lake. Under moderate hydrological conditions, water flows through the ditches and through the root zone soil of the reed community. The retention of total nitrogen (TN) and total phosphorus (TP) by surface flow through a 300-m ditch was measured to be 42% and 65% respective-ly. The retention of TN and TP by an 8-m stretch of reed community soil was 59% and 88%. The retention by the reed community mainly happened at the rhizosphere below the soil surface. The removal of organic matter was also observed. The retention of nutrients by the subsurface flow was more than 10 times greater than that by surface flow. The harvest of reed biomass recycles 1120 metric tons of nitrogen and 53 tons of phosphorus from lake-side ecotones back to the terrestrial ecosystems each year. There is a potential use of ecotone wetlands as the advanced treatment facility for nutrient-rich water, and a good design can enhance the treatment efficiency. Ecotone engineering for advanced water treatment is an economical method with low environmental risks and high efficiency.
Ammonium removal in constructed wetlands with recirculating subsurface flow: removal rates and mechanisms
Authors: Sikora F. J. , Zhu Tong , Behrends L. L. , Steinberg S. L. , Coonrod H. S.
Published: May 2018

From June 1993 through February 1994, the removal of NH4-N was evaluated in constructed wetlands at the TVA constructed wetland research facility in Muscle Shoals, AL. The objectives were to determine rates for NH4-N removal and speculate on potential mechanisms for removal. Nine constructed wetland cells were used with approximate dimensions of 9.1 × 6.1 × 0.6 m3 and a recirculating subsurface flow system in a gravel base. Treatments consisted of an unplanted (WO=control) and two polycultural planting schemes (P1=Scirpus acutus, Phragmites communis and Phalaris arundinacea; P2=Typha sp., Scirpus atrovirens georgianus and Scirpus cyperinus) replicated 3 times. Salt solutions were added and recirculated in each cell resulting in initial concentrations of 50 and 300 mg l−1 of NH4-N and COD, respectively, when fully diluted with wetland water. Salts were added to wetlands approximately every 6 weeks with the first addition on June 1, 1993 and the last addition on February 9, 1994 for a total of 6 time periods (times I, II, III, IV, V and VI). The COD of the waters was removed at rates ranging from 5.5 to 10 g/m2/d during times I through IV with no discernible difference amongst the planting treatments. Wetland cells with P1 were more efficient at removing NH4-N (1.1 g/m2/d) than P2 (0.6 g/m2/d) or WO (0.5 g/m2/d) at time I with differences decreasing by time IV (0.3 to 0.7 g/m2/d). During the winter (times V and VI), there were no differences in NH4-N removal amongst planting treatments with an average removal rate of 0.35 g/m2/d. There was a seasonal change in NH4-N removal in all the treatments, with the change most noticeable in the planted cells. The removal of NH4-N in WO was speculated to be due to a combination of sorption onto gravel, microbial assimilation, and nitrification at the air-water interface. The extra NH4-N removal in the planted cells diminished in the winter because the removal was most likely due to a combination of enhanced nitrification from O2 transport and NH4-N uptake mediated by seasonal macrophyte growth.
Comparative study of domestic wastewater treatment efficiencies between facultative pond and water spinach pond
Authors: Karnchanawong Seni , Sanjitt Jaras
Published: May 2018

Two pilot-scale studies were comparatively conducted under tropical conditions during December 1992 to September 1993. One study involved facultative ponds(FP) and the others water spinach ponds(SP). Four rectangular concrete ponds, 0.8 m × 2.4 m × 1.1 m (width × length × depth), were employed to treat the Chiang Mai University campus wastewater. Water spinach (Ipomoea aquatica) was planted in two of the ponds. The influent characteristics noted showed a low organic content, i.e. BOD 25.4-29.9 mg/l, with BOD:N ratio around 1:1. The investigations were conducted using the following hydraulic retention times (HRT): 1.6, 2, 2.7, 4, 8 and 16 d. The results showed that the BOD, COD and SS mass removal rates increased as the mass loading rates increased and the SP was significantly more effective in reducing the organic content than the FP. No relationship was found between TN mass removal and the loading rates. However, the TP mass removal rates in the SP and the FP were rather low and were considered to be insignificant. It was observed that SS accumulated in the water spinach root systems which tended to act as a strainer. This process led to plant growth inhibition and finally die-off. The average water spinach growth rates varied from 37 to 107 g wet wt./(m2.d) and no relationship was established between the growth rates and the HRT.
Reclamation of polluted riverwater for aquaculture: removal of nutrients by microalgae
Authors: Wong M. H. , Cheung Y. H. , Leung S. F. , Wong S. P.
Published: May 2018

The present experiment was designed to simulate an on-going field trial at Au Tau Substation, Agriculture and Fisheries Department, Hong Kong Government, using a series of fishponds to treat polluted riverwater, as well as for promoting algal growth, before the water was used for rearing freshwater fish. It was revealed that aeration was necessary to lower the level of ammonia. It also accelerated the conversion of ammonia to nitrite, and then nitrite to nitrate. Substantial amounts of metal (K, Mg, Cu, Zn) were also removed from the riverwater, possibly by algal assimilation. The algal products contained a high crude protein content (42% dry weight basis) which could be used to feed carp and tilapia.
On the net growth of phytoplankton in two dutch estuaries
Authors: Kromkamp J. , Peene J.
Published: May 2018

Langdon's model has been used in the calculation of net primary production of phytoplankton in the (turbid, eutrophic) Westerschelde and (relatively transparent) Oosterschelde estuaries. The results for the Westerschelde are shown to be much closer to the observed values than is achieved using other methods (fixed respiration rate) of calculation.
An assessment of water quality in a coastal embayment (Phaleron Bay, Greece)
Authors: Theodorou A. J.
Published: May 2018

Athens basin drains by gravity to the coast into the Phaleron Bay by the Kifissos river. The Phaleron coast is currently undergoing extensive remodelling and is scheduled for development as a major amenity and recreational centre. Thus, an assessment of the Phaleron Bay's present water quality constitutes a prerequisite for the future environmental management of its waters. Analysis of oceanographic data, collected during 1989–1990, showed that eutrophic conditions prevail in the vicinity of Kifissos river, where nutrients and chlorophyll-a occur in high concentrations. Also in this area, the benthic communities have been modified and they are dominated by detritus or sediment feeding polychaetes. However, beyond this region the impact of the river discharge diminishes with distance offshore and in the entrance of the bay, both water column quality and benthos are indistinguishable from those of the open Saronikos Gulf.
The Black Sea factor influencing the wastewater disposal strategy for Istanbul
Authors: Gönenç I. Ethem , Müftüoglu Oguz , Baykal Bilsen Beler , Dogan Ertugrul , Yüce Hüseyin , Gürel Melike
Published: May 2018

Unlike other seas of the world, the Black Sea shows unique quality and trophic properties. Fortunately, only the upper layer water of the Black Sea is introduced into the Bosphorus and has a significant effect on the quality and trophic conditions of the Marmara Sea. These effects are discussed in the light of data obtained from collaborative efforts of Turkish and Romanian research institutions and processed satellite images. In conjunction with these discussions, recommendations for a suitable effluent disposal strategy for Istanbul's wastewater have been given.
Sea outfalls for the disposal and treatment of wastewater effluents
Authors: Caine Raymond F.
Published: May 2018

The paper brings together a useful summary of all aspects of design and implementation of outfall schemes for the disposal of wastewater effluents. It outlines methods of assessment of the receiving water in relation to short-term and long-term impacts using the concept of Environmental Quality Objectives, with reference to European Union (EU) Standards and United Kingdom (UK) Practice. The need for good field data is outlined with appropriate methods and an indication of cost. A discussion of predictive modelling techniques and of the need to integrate combined storm discharges is included. The principles of hydraulic and structural design are outlined with special reference to the design of diffusers and to the impact on this of different characteristics of the receiving water. Finally, a brief review is given of the construction methods available at the present time.
Enhancement of biomass concentration in activated sludge systems
Authors: Plaβ R. , Sekoulov I.
Published: May 2018

By installation of lamella in the activated sludge tank an increase of biomass concentration in the activated sludge tank can be achieved without additional charge of the secondary clarifier. Integrated packages of lamella which are installed in the discharge of the activated sludge tank at an angle of 60° effect a partial sedimentation and so a MLSS-preseparation.

The MLSS in the activated sludge tank (influent of the lamella construction) was 6.5 g/l, the MLSS in the influent to the final clarifier (effluent of the lamella) was 3.1 g/l. That means that the lamella increased the MLSS concentration in the activated sludge tank by a factor of two. Despite a volume loading of 1.24 kg BOD5/(kg MLSS • d) a complete nitrification could be obtained. For ensuring a stable process and a balanced concentration of the biomass in the influent of the secondary clarifier, the preseparation of solids in the lamella is controlled by addition of air bubbles.

By the enhancement of biomass concentration using this preseparation device, the extension of waste water treatment plants can be carried out with lower investment costs.
Quality characteristics of surface and sea waters in Greece in relation to European union legislation
Authors: Andreadakis A. D. , Katsara A.
Published: May 2018

The paper summarises the results of a survey of the quality characteristics of 21 lakes, 24 rivers and 5 gulfs in Greece. The field data was collected by the Ministries of Agriculture and Environment & Public Works and covers the period 1989–1992. Data processing and evaluation, in order to determine the degree of pollution and the sensitivity of the water bodies, was conducted by considering the relevant European Union (EU) legislation. The quality characteristics of 90% of the surface waters do not violate the mandatory limits of the Directives 75/440 and 80/440. However, a significant number of lakes (about 60%) are meso-eutrophic or eutrophic with nitrogen being the limiting nutrient. The main sources of nitrogen in these cases are related to agricultural practices and the measures specified in Directive 91/676 (closer monitoring, improvement of agricultural practices) should be implemented. Furthermore, the discharge of treated sewage should be avoided or in any case the degree of treatment should include nutrients removal, in accordance with the requirements of the Directive 91/271 for sensitive recipients. The evaluation of the quality characteristics of the examined gulfs was performed taking into consideration the classification proposed by the Directive 91/271, which is based on the degree of sensitivity of the water bodies with respect to eutrophication.
Evaluation of the impact from the Black Sea on the pollution of the Marmara Sea
Authors: Orhon Derin
Published: May 2018

The Marmara Sea is now the recipient of a large number of wastewater discharges from land-based sources. At the same time, it is in direct exchange both with The Black Sea and The Mediterranean. A correct and efficient wastewater management programme with nutrient removal may be acceptable if it can effectively reduce the pollution in The Marmara Sea. This can only be evaluated by means of a comparative evaluation of the relevant pollutant loads originating from the land-based sources in the coastal zone and from the adjacent seas. This paper evaluates significant quality parameters related to the Black Sea – The Bosphorus – The Marmara Sea system, quantifies the pollution exchange between The Marmara Sea and The Black Sea and provides a critical appraisal of the effect of The Black Sea on the pollution in The Marmara in comparison with land-based sources.
Protecting Europe's water resources: policy issues
Authors: Enderlein Rainer E.
Published: May 2018

Main policy issues for the protection and use of water resources cover the application of the precautionary principle, prevention of pollution at source, the polluter-pays principle, the sustainability principle, and the cooperation among States to prevent disputes on water issues. The paper describes recent developments and progress made by European countries in cooperating on these issues.
Management of interdisciplinary teams
Authors: Engel H.
Published: May 2018

Large water resources development projects have a strong impact on the river basin as a whole. It is for that reason that the studies not only involve technical experts like geologists, hydrologists and engineers but also social-geographers, ecologists and economists. But how are these experts involved? Why have even projects sponsored by the very careful World Bank so often encountered implementation, operational and social problems? This article suggests that involving these different experts in a useful way is difficult and asks for skills and attitudes that were not needed for less complex endeavours. Based on the experience with the Dutch Delta works, this contribution describes the most important qualities of the organization needed for fruitful multidisciplinary work. These qualities are (1) openness, meaning no secrets on important issues of the project, (2) a widely accepted goal for the project and (3) a sound project management, instead of the commonly used hierarchical management.
Microbial transformation of PCBs in sediments: what can we learn to solve practical problems?
Authors: Stortelder Paul B. M. , Beurskens Jacobus E. M.
Published: May 2018

The disappearance of several polychlorinated biphenyls (PCBs) was observed in the deeper anaerobic sediment layers of Lake Ketelmeer, a sedimentation area of the Rhine River. Laboratory studies with an anaerobic consortium from this area demonstrated the capabilities for transforming PCBs. The field and laboratory observations indicate that disappearances of PCBs in the sediment might be caused by in situ microbial dechlorination. These processes appear to have lowered the PCB toxicity of four reactive congeners by 75% during the last two decades. In addition, dechlorination reactions are the essential first steps in the only natural pathway that eventually may lead to a complete elimination of PCBs from the aquatic environment. This can only be achieved if the dechlorination products are subsequently mineralized under aerobic conditions. Several implications for environmental policies with regard to contaminated sediments are discussed. Long-term prognoses on sediment quality generated with mathematical models that include these reactions may lead to a distinct, probably less costly, sediment policy.
Ecological restoration of the Rhine/Maas estuary
Authors: Kuijpers J. W. M.
Published: May 2018

In 1995 it will be 25 years since the estuary of the Rhine and Maas was closed off from the sea by a dam with outlet sluices. After 1970 it gradually became clear that the change of an open estuary into a semi-stagnant lake had many negative ecological effects: bank erosion, accumulation of polluted sediments and the disappearance of a natural transition zone between the estuary and the sea. As the public attention to nature conservation in The Netherlands grew over the years, this ecological degradation was more and more recognized as a problem.

To achieve a healthier ecosystem a program of remedial action has been launched. Some elements such as the protection of valuable wetlands against erosion have almost completely been realised. Others such as the removal of large quantities of polluted sediment and a change in the operating program of the outlet sluices are being prepared. The main challenge is to find a compromise between ecological values and all kinds of human use of the water system.
Eutrophication and ecological rehabilitation of Dutch lakes: Presentation of a new conceptual framework
Authors: Klinge M. , Grimm M. P. , Hosper S. H.
Published: May 2018

Lake restoration is a major issue in water management in The Netherlands. In this context biomanipulation is considered an important tool following the reduction of the nutrient load. Here we present a new conceptual framework and try to quantify the productivity level below which predator control of the fish population, which is considered a prerequisite for successful biomanipulation, occurs.

The conceptual framework focuses on a balance between preyfish production and piscivorous fish consumption. When the piscivorous fish consumption (top-down control) is too low to control the preyfish community (bottom-up forces), the abundance of small planktivorous fishes will increase, leading to the cascading effects of a heavy predation on zooplankton and an excessive development of algae resulting in an increase of turbidity. With the framework the total-P concentrations characterising lake productivity at such turning points can be calculated.

The framework is used to explain the eutrophication process of Dutch lakes, which is described as a series of stages between which shifts in community structure including the dominant piscivorous fish species occurred. Furthermore, based on the framework some predictions and methods for ecological rehabilitation will be presented.
Ecosystem development in Lake Volkerak-Zoom: concept and strategy
Authors: Ligtvoet W. , de Jong S. A.
Published: May 2018

In the 6000 ha Lake Volkerak-Zoom, a new freshwater system in the estuarine southwest of The Netherlands, biomanipulation is used as a tool in ecosystem development. The basic ecological concepts for ecosystem development are described. Key factors in the integrated water management are fish stock management and water level management, geared towards creating optimal conditions for northern pike, the dominant predator in mesotrophic waters. The main aspects of the water level management and the fish stock management are outlined.
Studies on the dynamics of immobilization of anaerobic bacteria on a plastic support
Authors: Meraz M. , Monroy O. , Noyola A. , Ilangovan K.
Published: May 2018

The paper presents a comparative study of the immobilization dynamics of mesophilic and thermophilic anaerobic bacteria. The support used was fine polyethylene particles and the immobilization system was a down flow fluidized bed. The maximum acetoclastic specific activity of the mesophilic bioparticles was of 0.0083 mmol acetate/mg VSS/h while for the thermophilic bioparticles was near zero. The final immobilized VSS content for both system was around 45 mg/g dry support. The substrate affinity determined only for mesophilic bioparticles was of 68 mg COD/1; for the thermophilic bioparticles could not be determined due to the low acetoclastic rates presented. The SEM studies showed that predominantly the bacterial group attached was Methanothrix-like bacilli, and the mesophilic was structurally different from the thermophilic one.
Policy analysis and complexity – a non-equilibrium approach for integrated water management
Authors: Geldof Govert D.
Published: May 2018

In integrated water management, the issues are often complex by nature, they are capable of subjective interpretation, are difficult to express in standards and exhibit many uncertainties.

For such issues, an equilibrium approach is not appropriate. A non-equilibrium approach has to be applied. This implies that the processes to which the integrated issue pertains, are regarded as “alive”’. Instead of applying a control system as the model for tackling the issue, a network is used as the model. In this network, several “agents”’ are involved in the modification, revision and rearrangement of structures. It is therefore an on-going renewal process (perpetual novelty).

In the planning process for the development of a groundwater policy for the municipality of Amsterdam, a non-equilibrium approach was adopted. In order to do justice to the integrated character of groundwater management, an approach was taken, containing the following features: (1) working from global to detailed, (2) taking account of the history of the system, (3) giving attention to communication, (4) building flexibility into the establishing of standards, and (5) combining reason and emotions.

A middle course was sought, between static, rigid but reliable on the one hand; dynamic, flexible but vague on the other hand.
A method for quantifying the effects of groundwater shortages on aquatic and wet ecosystems
Authors: Gieske J. M. J. , Runhaar J. , Rolf H. L. M.
Published: May 2018

This paper describes a method for quantifying the effects of groundwater shortages or parching on aquatic and wet ecosystems. Linear relations are determined between hydrological indicators and the degree to which ecosystems are parched. The degree of parching is expressed as a number between 0 (not affected) and 1 (fully affected). The method takes into account the following processes: lowering of water tables, decreasing intensity of upward seepage, increasing water table fluctuations and inflow of allochthonous surface water. It enables the degree of parching to be determined annually. The method was developed by the TNO Institute of Applied Geoscience and the Centre of Environmental Studies Leiden at the request of the Dutch government, which wishes to evaluate the effect of its environmental policy annually. It can also be used to monitor nature reserves on a local scale.
The lake ecosystem simulation program
Authors: Heringa J. , Hylkema H. , Kroes M. , Ludden E. , van Schaick Zillesen P. G.
Published: May 2018

The computer program LAKE simulates a shallow lake ecosystem. The program is based on a mathematical model. In the model the most important aspects of several models for water resources management are integrated (Collins and Wlosinski, 1988; Jørgensen, 1976; Jørgensen et al., 1978; Scheffer, 1988). Furthermore, the model describes several ecological processes that have not yet been described by lake-ecosystem models so far. In the computer program, the mathematical model and an advanced, object oriented, user interface are combined. Following this approach the use of the original research models was extended to a use for the purpose of teaching lake ecology. We suggest that the same approach may be followed to open research models to other groups concerned with water resources management, such as management authorities, industry, agricultural extension, nature conservation and recreation.
Photocatalytic mineralisation of perchloroethylene using titanium dioxide
Authors: Gupta Hani , Tanaka Shuzo
Published: May 2018

The photocatalytic mineralisation of perchloroethylene (PCE) is demonstrated mainly in terms of CO2 formation to investigate the effects of various factors such as dissolved oxygen (DO), titanium dioxide semiconductor (TiO2) catalyst dosage, PCE concentration and pH on PCE photocatalysis. PCE was rapidly adsorbed onto the TiO2 particles followed by its gradual degradation, and CO2 production started after a short lag time that corresponded to the adsorption phase. The rate of CO2 formation increased with increasing DO, TiO2 dosage and PCE concentration. There was no significant effect of initial pH on the CO2 production rate over a wide pH range. The dependence of the CO2 formation on PCE concentration was found to obey the Langmuir-Hinshelwood model. No intermediates were detected during PCE degradation and PCE degradation followed a first-order reaction.
Effect of sulfate on anaerobic processes fed with dual substrates
Authors: Polprasert Chongchin , Haas Charles N.
Published: May 2018

Anaerobic reactors were operated in a semi-batch mode and fed with the dual substrates glucose (G) plus acetic acid (Ac) as primary organic sources to study the effect of sulfate on COD oxidation. With glucose, COD removal by methane formation was seriously inhibited, resulting in COD accumulation in the reactor. Although acetic acid can be consumed by some sulfate-reducing species, it was not a major substrate for sulfate reduction, but was largely responsible for methane formation in the anaerobic mixed culture used in this study. With dual substrates, extreme inhibition of methanogenesis did not occur as did with glucose alone. Instead, methanogens were found to work in harmony with acid formers as well as sulfate reducers to oxidise COD. Interestingly, from 12-hour monitoring, increased G/Ac COD ratios decreased COD removal rates as well as biogas production, but resulted in higher sulfate reduction. This suggests that there should be an optimal feed G/Ac COD ratio, for which removal of both organics could be maximised.