bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accelerating the rate of cometabolic degradations requiring an intracellular electron source-model and biofilm application
Authors: Bae W. , Rittmann B. E. 
Published: May 2018

This paper applies our recently acquired knowledge of the large and systematic changes in internal reducing power to controlled changes in the cell's primary electron-donor and -acceptor substrates. The systematic cellular responses of the NADH/NAD ratio is incorporated into kinetic equations for reductive dehalogenation and oxygenation reactions. Results show that the external donor and acceptor concentrations strongly affect the percentage removal of hazardous compounds. The simplest strategy for maximizing the efficiency of reductive dehalogenation is to maintain a saturating concentration of the primary electron donor, or, as a next best alternative, to minimize the concentration of electron acceptors. For mono- or dioxygenation reactions, consistently high percentage removals can be achieved when the concentrations of both primary substrates are high.
Removals of carbon tetrachloride in denitrifying biofilm experiments are in perfect accord with the model predictions for reductive dehalogenation. They show a dramatic increase in percentage removal when the primary electron acceptor (NO3−) is removed from the reactor and a substantial decrease when the electron donor (acetate) is removed. Thus, the biofilm experiments verify that biodegradation reactions can be accelerated dramatically by manipulation of primary donor and acceptor concentrations and in a manner consistent with modeling predictions based on the internal reducing power.
The implementation of biokinetics and conservation principles in ASIM
Authors: Gujer Willi , Larsen Tove A. 
Published: May 2018

The Activated Sludge SIMulation program ASIM is introduced as a didactic tool to be used in design courses for the simulation of the dynamic behaviour of modern nutrient removal activated sludge systems. It allows for free definition of the biokinetic model, the flow scheme, process control strategies and load variation. Its user interface is simple enough to be used in the classroom but powerful enough to support even professional work.
The most difficult aspect of ASIM is the preparation of the biokinetic model (transformation processes) to be used. A systematic use of stoichiometric conservation principles simplifies this task and at the same time reduces the number of empirical parameters. The practical application of conservation principles for charge, elements and theoretical COD is presented in detail. Composition equations are introduced as a link to the wastewater treatment plant reality.
The use of wetlands for water pollution control in Australia: an ecological perspective
Authors: Mitchell D. S. , Chick A. J. , Raisin G. W. 
Published: May 2018

The potential use of natural and constructed wetlands to treat rural and urban wastewaters and run-off has been under active investigation in Australia by the authors and others associated with them for about 15 years. The results of these investigations will be briefly summarised in relation to factors affecting their performance and their application for management of water pollution.
Investigations have included rigorous experimentation with wetland microcosms, calculation of nutrient balances for natural and artificial wetlands, fundamental research on the role of wetland plants, the construction of experimental wetlands of various designs at a pilot scale, and the installation of operating systems.
The results confirm the potential of wetland systems to ameliorate water quality but do not demonstrate how to do this consistently under normal day-to-day operating conditions. Issues that now need to be addressed include hydraulic short-circuiting, the role and management of the wetland plants, the extent to which constructed systems should mimic natural systems, and problems associated with scaling up from successful experimental systems to full scale operating treatment plants.
Nutrient-related selection mechanisms in marine phytoplankton communities and the impact of eutrophication on the planktonic food web
Authors: Riegman R. 
Published: May 2018

A general increase in nutrient discharges during the last few decades has caused various changes in the algal community structure along the European continental coast. Coincidentally and maybe consequently, the foodweb structure and functioning has altered in local areas causing various phenomena like oxygen depletion, mortality of groups of organisms, foam on beaches, and an increase in the productivity of benthic communities and some commercial fish species. The observed increases in algal biomass and shifts in species composition are discussed in relation to the involved key mechanisms: resource competition and selective grazing.
Along the Dutch coastal zone of the North Sea eutrophication has caused a doubling of the yearly averaged algal biomass during the past three decades. The sudden appearance of Phaeocystis summer blooms coincided with a shift from P-limitation towards N-limitation in the Dutch coastal area due to a stronger increase in P-discharge relative to the increase in N-discharge. Competition experiments in continuous cultures showed Phaeocystis to become dominant under N-limitation. Additionally, the large Phaeocystis colonies, which can reach a diameter up to one centimetre, escape from microzooplankton grazing.
A computer model is presented which demonstrates a shift from bottom-up towards top-down control if the pelagic environment becomes eutrophicated. Implementation of this concept in a size-differential phytoplankton control model generates the prediction that algal blooms are dominated by species that escape from grazing by those zooplankton species which have a high potential numerical response. In marine environments these are microzooplankton species. These organisms mainly feed on cyanobacteria, prochlorophytes and some nano-algal species. One of the consequences for foodweb structure and the carbon fluxes in marine foodwebs is that eutrophication will lead to the dominance of poorly edible algal species.
Eutrophication favours the downward transport of carbon and nutrients towards the sediments not only due to higher algal biomasses but also as a consequence of a shift towards larger algal species with higher sedimentation characteristics.
An example is given how these new insights can be used for water quality management purposes.
TSS/BOD removal efficiency and cost comparison of chemical and biological wastewater treatment
Authors: Nenov Valentin 
Published: May 2018

Based on standard settling column tests, Jar tests and continuous activated sludge laboratory experiments as well as combination of these processes implemented for a treatment of municipal wastewater with a composition typical for the influent water of Ravda Municipal Wastewater Treatment (MWWT) plant, the removal efficiency obtained in respect of the total suspended solids (TSS) and the biochemical oxygen demand (BOD) was evaluated.
The laboratory experiments confirmed the high efficiency of the chemically enhanced mechanical treatment (CEMT) towards TSS and BOD/COD removal. The data obtained show that low dose chemical treatment in a large range of surface flow rate of precipitation provides a reduction of TSS and BOD/COD larger than 60% and 50%, respectively.
Regarding Ravda WWTP as a typical case for the Black Sea coast it was proved that CEMT is an attractive alternative for retrofitting the existing plants based on the activated sludge process as a secondary treatment process. CEMT upgrading can be done at much lower cost (practically only O&M treatment expenditure is required) compared with an eventual biological step extension.
The fate of detergent surfactants in sewer systems
Authors: Matthijs E. , Debaere G. , Itrich N. , Masscheleyn P. , Rottiers A. , Stalmans M. , Federle T. 
Published: May 2018

The fate of detergent surfactants in the sewer can be studied both in laboratory tests and in field experiments. The laboratory studies can be used to determine the rate of disappearance of a test molecule as a function of residence time and estimate its half-life in a given habitat. In addition, important information can be obtained on the mechanism of degradation. Field studies can determine the actual environmental concentrations of surfactants in raw sewage which can then be compared with the expected concentration based on consumption volumes. The difference between the measured and predicted concentration provides an estimate for the disappearance of the test chemical during its travel in the sewer and confirms the results of the laboratory tests.
This paper focuses on the fate of a number of important representative anionic, nonionic and cationic surfactants, in the sewer. The results of laboratory die-away studies showed that, in general, the half-life for disappearance in the sewer was in the order of hours for Fatty Alcohol Ethoxylate (AE), Fatty Alcohol Ethoxy Sulphate (AES) and Di-Ethyl-Ester Di-methyl-Ammonium Chloride (DEEDMAC). These laboratory findings for AES were confirmed by monitoring actual raw sewage reaching municipal sewage treatment plants. In addition, a field study demonstrated that the concentration of glucose amides (GA) is considerably reduced during its travel in the sewer. These complementary laboratory and field studies provide key information for the safety assessment of surfactants. They demonstrate that the concentration of surfactants can be significantly reduced in the sewer resulting in a rapid reduction of the environmental loading, which is particularly important in environmental situations where inadequate or no sewage treatment exists.
Aggregation of sulphate-reducing bacteria and homo-acetogenic bacteria in a lab-scale gas-lift reactor
Authors: van Houten R. T. , van Aelst A. C. , Lettinga G. 
Published: May 2018

This paper discusses aspects of the formation, growth and detachment of sulphate-reducing aggregates, growing on H2/CO2 and H2/CO gas mixtures in a 4.5 L lab-scale gas-lift reactor. The biomass in the aggregates consisted predominantly of Desulfovibrio sp. and Acetobacterium sp.
Our experiments with H2/CO2 showed that aggregates with pumice particles, i.e. biofilms, as well as carrier-free aggregates were formed. At pH 7.0, all the aggregates had a very hairy structure. This structure, however, was pH dependent. At lower pH-levels the aggregates became smooth. At pH-values higher than 7.0 the hairy structure became even more irregular. The predominant microorganisms were rather heterogeneously distributed throughout the aggregates at all pH-values.
Growth on gas-mixtures of H2/CO led to the formation of smooth aggregates. Presence of CO also led to formation of a layered biomass structure in which the Acetobacterium sp. were more at the outside of the aggregates and the Desulfovibrio sp. were located at the inner part of the aggregates.
The observed changes in the surface structure of the sulphate-reducing aggregates are related to the growth rate of the microorganisms present. A high growth rate yields a rough and hairy aggregate surface. A low growth rate yields a smooth aggregate surface, since the low growth rate of the microorganisms allows detachment of the large protrusions from the aggregate surface.
The surface structure is not dependent on the type of bacteria present at the surface, i.e. sulphate-reducing bacteria or homo-acetogenic bacteria.
Evaluating and modelling the kinetics in a full scale submerged denitrification filter
Authors: Janning K. F. , Harremoës P. , Nielsen M. 
Published: May 2018

Experimental data in forms of vertical concentration profiles has been provided from a full scale submerged denitrification filter with biocarbone as filter material.
Denitrification rates were determined in full scale under different loads of nitrate and methanol with methanol in excess. Vertical concentration profiles of nitrate and methanol have verified kinetics in the half-order region with removal rate constants in the range of k0.5A = 0.13-0.21 g N0.5 m−0.5 d−1 (0.5 order for partial penetration in the 0 order intrinsic concentration range). The removal rates found are low with methanol as carbon source as compared to information from literature.
The experience with detailed mathematical modelling is that “best fit” can be achieved by different sets of parameters with the computer program AQUASIM. Full scale experiments have to be supplemented with dedicated laboratory scale experiments to determine all important parameters.
Influence of the microbial content of different precursory nuclei on the anaerobic granulation dynamics
Authors: El-Mamouni R. , Leduc R. , Costerton J. W. , Guiot S. R. 
Published: May 2018

Anaerobic granule nuclei enriched in either acidogens (AF), syntrophic consortia (SN), Methanosaeta spp. (MT) and Methanosarcina spp. (MN) were developed in four upflow bed filter reactors fed with sucrose, an ethanol/acetate mixture, acetate and methanol, respectively. The four developed granule nuclei presented different settling velocities: 3.2, 8.7, 10.5 and 11.3 m/h for the AF flocs, the MS-, the SN- and the MT-nuclei, respectively. The ash content represented 60%, 40%, 30% and 16% of dry weight for the MT-, MS-, SN-enriched nuclei, and AF flocs, respectively. Acidogenic flocs contained high amount of extracellular polymeric substances.
The influence of these four different nuclei on the time course of complex granule development was investigated by shifting the feed carbon of all of the four reactors to sucrose. Granulation proceeded rapidly both on syntrophic and Methanosaeta nuclei. The largest granules (Sauter diameter of 2.36 mm), however, were obtained within the shortest period in the reactor started with syntrophic nuclei. These nuclei presented also the best colonization by fermentative bacteria as shown by the evolution of their glucotrophic activities. Less satisfying granulation was obtained on Methanosarcina nuclei. In contrast, granulation was significantly retarded when acidogens were used as precursors. From these results it appears that syntrophs and Methanosaeta spp. play the principal role in anaerobic granulation process.
Upscaling biomanipulation in 600 ha Lake Zuidlaardermeer
Authors: Roos C. , Klinge M. , Heringa J. , de Vries D. A. , Torenbeek R. 
Published: May 2018

In the 600 ha Lake Zuidlaardermeer in The Netherlands enclosure experiments were carried out in order to test the feasibility of biomanipulation. In two enclosures of 625 m2 each the effects of reduction of fish and wind and waves on water chemistry, phyto- and zooplankton and submerged macrophytes were studied and compared to the lake.
In the “fishless” enclosure transparency increased from 40 to 120 cm, chlorophyll-a dropped from 70 to 20 μg/l, total-P dropped from 0.20 to 0.10 mg/l, Daphnia sp. &gt; 1 mm increased from 30 to 130 individuals/l and submerged macrophytes returned. The “fish” enclosure largely behaved in a way intermediate between the “fishless” enclosure and the lake: transparency increased to 60 cm, chlorophyll-a dropped to 40 μg/l, total-P dropped to 0.12 mg/l and Daphnia sp. &gt; 1 mm increased to 80/l. Submerged macrophytes however did not develop.
The experiments show the potential of the lake for ecological rehabilitation. Nevertheless the effect of wind and waves on a larger scale remains uncertain. Therefore plans have been made to build a larger enclosure (40–100 ha). In this way, the effects of fish and wind and waves can be studied on a larger scale while at the same time recovery of the submerged macrophytes within this enclosure will be a significant step towards ecological rehabilitation of the whole lake.
Beside the return of the submerged macrophytes the management is also aimed at the development of substantial amounts of emergent vegetation, thus supporting enough Northern Pike (Esox lucius L.) for regulation of the planktivorous fish community.
The water system explorations – a new dutch project (the aquatic outlook) for combining monitoring, research and policy analysis for integrated water management
Authors: Luiten J. P. A. 
Published: May 2018

Sustained development is the target of almost every modern policy dealing with the aquatic environment. Sustainability is focused on human life, but also on the ecological quality of our environment. Both aspects are essential for life on earth.
The ecological quality of aquatic systems can be expressed by biotic and abiotic parameters. Monitoring and research give information about these parameters and a comparison with the targets brings us to the necessity of supplementary policy-measures.
Human activities are considered to be the cause of the environmental problems. All kinds of social and economical activities influence the water bodies. Reaching the goals is only possible if human influence on environment is changed or reduced.
Within a catchment area, relations could be laid between human activities and ecological problems in the reception areas. Policy analysis is especially looking for the most efficient way to remove the bottlenecks. For an effective policy analysis in river catchment areas the following elements are essential:
– quantitative data; monitoring programs have to consider more than ever the ecological aspects of policy analysis;
– the determination of target values (probably by means of laboratory experiments);
- knowledge about the factors causing violation of the targets;
– an inventory of measures for influencing the existing or future situation;
– sufficient knowledge about the relation between the measures and (i) the ecological parameters and (ii) the social and economical activities in society;
– a policy analysis for defining future policies;
All of these studies will generate many data; to present these in a clear and succinct manner is one of the goals of the project “The Aquatic Outlook”.
Evaluation of daqahla wastewater treatment plant, aerated lagoon and ponds system
Authors: El Sharkawi F. , El Sebaie O. , Hossam A. , Abdel Kerim G. 
Published: May 2018

In Egypt, Daqahla wastewater treatment plant (WTP) includes two anaerobic ponds, one aerated lagoon followed by three maturation ponds. It started operation in 1989. This plant is chosen as an example for evaluation as a cost-effective method for wastewater treatment in rural areas.
A sanitary survey, laboratory analysis and cost survey were carried out during the period between December 1991 to September 1992. It was found that Daqahla community has high strength wastewater characterised by an average BOD5 of 454 mg/l and average SS of 508 mg/l. Furthermore, it was noticed that Daqahla WTP was loaded with an actual flow (833 m3/d) higher than the design flow (520 m3/d). In addition there was a wide fluctuation in the loads applied to the system. The system was evaluated, and the average removal efficiencies of suspended solids, BOD5 and COD were 92%, 95% and 93% respectively. While there was no removal of ammonia and phosphate, with respect to the efficiency of the anaerobic ponds, it was noticed that about 50% of the organic loading was removed and this is consistent with the literature. In order to upgrade the efficiency of the aerated lagoon and the first maturation pond, the design load and detention time must be taken into consideration. Sludge removal processes must be considered since the first maturation ponds was working as a settling pond. It was noticed that the second and the third maturation ponds were working as facultative ponds. To upgrade their efficiencies, the actual organic loading must not exceed the design load with a minimum retention time of 3 days per pond.
The cost survey indicates that the construction cost is 63 LE/cap. Land costs in delta and desert areas are 19 and 2 LE/cap., respectively (acre prices in delta and desert are 40000 and 4000 LE respectively. Total construction cost in the delta is 82 LE/cap., while in the desert, the total construction cost is 65 LE/cap. Furthermore, the operation and maintenance cost is 12 LE/cap. year.
Composting of sewage sludge in a rotating vessel
Authors: Fürhacker M. , Haberl R. 
Published: May 2018

Composting of sewage sludge can enhance its quality and suitability for agricultural use. In this work the optimal conditions for composting sewage sludge of small domestic wastewater treatment plants in a rotating vessel with the aim of sanitary safety were investigated. An intensive control programme with regard to viruses, bacteria and parasites was carried out that showed that the hygienic quality was satisfactory.
A second aspect was the investigation of a possible reduction of hazardous organic and inorganic pollutants. The amount of inorganic micropollutants was low and did not change based on inorganic content. Based on inorganic residues, losses of 15.7% of the AOX and 25% of the EOX could be found. Relatively high decreasing rates of detergent concentrations could be measured. Only 31.1% of the original load of anionic detergents (measured as MBAS), 38.7% of the cationic and 57.4% of the non-ionic detergents could be detected in the end material. For PAH concentration reduction between 31.5% of fluoranthene and 90.6% benzo(a)pyrene can be reported. All values are based on the inorganic residues.
The quality of the resulting compost showed in the plant test a growth rate which qualified the compost to be used to increase soil quality.
Ammonia elimination processes in stabilisation and high-rate algal pond systems
Authors: Gómez E. , Casellas C. , Picot B. , Bontoux J. 
Published: May 2018

Stabilisation pond (SP) and high-rate algal pond (HRAP) wastewater treatment systems are based on the same processes, but differ in their capacity to remove ammonia. This study analyzes the processes concerning ammonia elimination.
The different factors studied are: (i) light irradiance and temperature, (ii) phytoplankton uptake, and (iii) chemical characteristics affecting ammonia concentration. The variables relevant to these processes have been used in path analysis studies.
Different variables describing the studied processes have been used to quantify the different phenomena. A conceptual model has been developed, and applied to each pond. Path analysis technique has been applied. It is a causal modelling technique. The evaluation of causal models involves theoretical, methodological and statistical analysis. Theoretical considerations have been defined in the list of the processes studied. Methodological considerations involve the variable measurements on a defined time-scale. The statistical aspect consists of the evaluation of structural equation models.
The results of these studies show that the principal phenomena affecting ammonia in SP systems are temperature, pH, and total nitrogen input. In HRAP systems ammonia variability is directly linked to pH, temperature, nitrite and total nitrogen input, and indirectly linked to chlorophyll a concentration and pH.
The percentage of observed variability given by the models (R2 =coefficient of determination) ranges between 46% and 60.8%.