bluuebunny/crossref_metadata_2025 huggingface dataset:
Establishment of Three Emergent Macrophytes Under Different Water Regimes
Authors: Giovannini S. G. T. , Marques D. M. L. da Motta
Published: May 2018

The behavior of three emergent aquatic macrophytes under different water regimes was studied with the aim of achieving reconvertion of degraded wetlands and wetland construction for water quality improvement. Scirpus californicus, Typha subulata and Zizaniopsis bonariensis establishment was evaluated under a split plot design, in a factorial experiment with three levels of a water regime factor over a subsoil substratum. The stagnant 10±2 cm water level was best suited to T. subulata and Z. bonariensis development and S. californicus developed better at oscillating water level (3±2 cm) with flooding at 48 hour intervals. The morphological response variables (thickness and width at half length of the tallest leaf or stem per plant, height of tallest leaf or stem per plant, number of green leaves or stems and number of shoots per plant, and survival of propagules' original leaves or stems) were satisfactory descriptors to differentiate (p<0.1%) growth of above ground parts as related to water regimes and species. The three species did survive satisfactory in subsoil-like substratum under the tested water regimes. Mortality was in the worse case, 17.2%, 36.7%, and 9.4% for S. californicus, T. subulata, and Z. bonariensis, respectively. Although Z. bonariensis growth was very poor, only S. californicus and T. subulata could be indicated for planting under similar limiting conditions.
Hydraulics Efficiency of Constructed Wetlands and Ponds
Authors: Persson J. , Somes N. L. G. , Wong T. H. F.
Published: May 2018

Constructed ponds and wetlands are widely used in urban design to serve a number of functions including stormwater management. The design of constructed wetlands for stormwater management involves a number of multi-disciplinary inputs. Fundamental to their sustainable operation are the proper control of the hydrologic regime of the wetland and optimal flow hydrodynamics within the wetland. Many ofthe problems encountered in constructed wetlands can be minimised or avoided by good engineering design principles. Poor wetland hydrodynamics are often identified as a major contributor to wetland management problems. Ponds and wetlands with a high hydraulic efficiency are expected to promote full utilisation ofthe available detention storage and near plug flow conditions. The shape and layout of urban ponds and wetlands are often varied to suit the landscape and to satisfy aesthetic requirements as an urban water feature. These can be achieved while maintaining an effective stormwater treatment outcome if steps are taken to ensure that the hydrodynamic behaviour of the system is not severely compromised. A consistent measure is required to allow the effects of design features to be evaluated against this criterion. This paper introduces a new measure for hydraulic efficiency that combines existing measures of flow uniformity and effective volume. Case studies are presented on the use of this measure to assess the effects of different pond and wetland shapes, locations of inlet and outlet, botanical layouts and basin morphology on the flow hydrodynamics.
The Removal of Urban Pollutants by Constructed Wetlands During Wet Weather
Authors: Scholes L. N. L. , Shutes R. B. E. , Revitt D. M. , Purchase D. , Forshaw M.
Published: May 2018

The Environment Agency for England and Wales has developed urban runoff treatment wetlands at two selected sites in Outer London. The systems were monitored for a range of determinands including heavy metals, suspended solids and BOD. Initial analysis of the data indicates that during dry weather, removal efficiencies vary greatly. However, during storm events removal efficiencies are higher with mean values of 71% for Zn, 72% for Cd, 69% for Pb, 66% for Cu, 34% for Ni and 81% for Cr at the Dagenham wetland. Mean removal efficiencies of 20% for Cd, 40% for Pb, 36% for Cu, 34% for Ni and 38% for Cr were monitored during storm conditions at the Brentwood wetland, but an overall increase in Zn was measured. Removal of BOD was greater at both sites during storm events with mean removal efficiencies of 24% and 29% at Dagenham and Brentwood, respectively. Suspended solids are reduced on passing through both wetlands during dry weather, but, during storm events there is an overall increase.

The metal removal capability of microorganisms isolated from the rhizosphere of Typha latifolia and Phragmites australis is being investigated. Laboratory experiments are assessing the efficiency of two metal tolerant strains to accumulate Pb and Zn. It is believed that this ability may prove to be an important year-round pollutant removal process in the treatment of urban runoff by constructed wetland treatment systems, and preliminary data are presented.
A comparison of NH4/NO3 control strategies for alternating activated sludge processes
Authors: Lukasse L. J. S. , Keesman K. J. , Klapwijk A. , van Straten G.
Published: May 2018

Four control strategies for N-removal in alternating activated sludge plants (ASP's) are compared: 1. timer-based, 2. switching the aeration on/off when depletion of nitrate/ammonium is detected, 3. switching the aeration on/off when ammonium crosses an upper/lower-bound, 4. the newly developed adaptive receding horizon optimal controller (ARHOC) as presented in Lukasse et al. (1997). The comparison is made by simulating the controllers' application to an alternating continuously-mixed activated sludge reactor preceded by a small anoxic reactor for predenitrification. The biological processes in the reactors are modelled by the activated sludge model no. 1. Realistic influent patterns, measured at a full-scale wastewater treatment plant, are used. The results show that three totally different controllers (timer-based, NH4-bounds based and ARHOC) can achieve a more or less equal effluent quality, if tuned optimally. The difference mainly occurs in the sensitivity to suboptimal tunings. The timer-based strategy has a higher aeration demand. The sensitivity of the ARHOC controller to sub-optimal tuning, known measurement time delays and changing plant loads is significantly less than that of the other controllers. Also its tuning is more natural and explicit.
Parameter estimation for activated sludge models with the help of mass balances
Authors: Nowak O. , Franz A. , Svardal K. , Müller V. , Kühn V.
Published: May 2018

Mass balances for carbon (as COD), nitrogen, and phosphorus are excellent tools for the evaluation of WWTPs in order to estimate fluxes of these substances, to compare operational data of different WWTPs with one another and, finally, to draw conclusions of general validity. In the case of activated sludge systems, mass balances can also be very helpful for model calibration, in particular for the ‘Activated Sludge Model No. 1’ (ASM1), because this model is consequently based on balances for COD and nitrogen. Hence, the results of mass balances can be utilised directly for the estimation of model parameters. Accordingly, it is recommended to evaluate the fluxes of COD and nitrogen, before the model calibration is started. By means of mass balances only the state of equilibrium can be described. Therefore, as regards model calibration, only parameters responsible for long-term behaviour can be estimated, i.e. the heterotrophic yield YH, the fraction of biomass yielding particulate organics fP, the heterotrophic decay rate bH and the concentration of particulate inert organics XI in the influent. A correct estimate of these parameters is a prerequisite for the validity of the simulation results, not only in regard to excess sludge production and SRT, but also with respect to the oxygen consumption for carbon removal and, therefore, to denitrification capacity.
Management optimisation of a large wastewater treatment plant
Authors: Carucci A. , Rolle E. , Smurra P.
Published: May 2018

The present study gives a useful way to optimize the operating (i.e. improving efficiency and saving energy) of a large wastewater treatment plant. The methodology was developed at the nitrogen removing activated sludge plant of “Roma-Est” (800,000 p.e.). Once design and operating data had been collected, a five-month experimentation was conducted to characterise the influent wastewater substrate fractions and to calculate the main kinetic parameters of the biomass. All data were used as parameters for a modified version of the ASM n.1 mathematical model, simulating the biological process flow, organic load and temperature variations as well as plant scheme modifications. Simulations showed the possibility of shutting down one of the three treatment lines and overloading the other two, with great operating improvement. Besides, neither the use of primary sedimentation, nor the aerated sludge internal recycle seem to be convenient.
On BOD tests for the determination of biodegradable COD for Calibrating Activated Sludge Model No. 1
Authors: Weijers Stefan R.
Published: May 2018

Application of Activated Sludge Model No. 1 requires an influent characterisation of COD over the different model COD components. Total biodegradable COD (CODBD) is the most important quantity in this characterisation. The use and interpretation of BOD tests for the determination of biodegradable COD were investigated. Of four grab samples, the BOD evolution in time was measured up to fifteen days, with addition of nitrification inhibitor. From the BOD curves, total BOD (BOD∞, or BOD infinite) was estimated with first and second-order models. Parameters were fitted with one (or two, for the second-order models) kinetic parameter per individual sample as well as one (two) for all samples together. The BOD curves were adequately described by first-order kinetics. The estimated kinetic parameters showed considerable variation over the samples from the same wastewater. As a consequence, the ratio BOD∞/BOD5 was not constant for a given wastewater. The ratio BOD∞/CODtot on the contrary proved much more constant. Therefore, the total COD instead of BOD5 is suggested as a basis for determination of biodegradable COD. The BOD∞ estimated has to be converted to CODBD. The conversion factor was computed by simulating the BOD tests using ASM1, reduced for aerobic conditions. This approach provides a quantitative basis for this conversion factor. The sensitivity of this conversion factor to model parameter values and COD fractionation was determined, which showed that the conversion has to be adjusted for non-default values of the heterotrophic yield.
Closed system for local reuse of blackwater and food waste, integrated with agriculture
Authors: Skjelhaugen O. J.
Published: May 2018

To increase the recycling rate of blackwater and food waste to farm land, a small scale system, independent of sewer pipelines and sewage works, has been developed. It reduces water and air pollution, allows for source control of the recycled material, integrates farmers into the waste handling business, and reduces domestic water consumption. Parts of the system have been implemented in four Norwegian communities. Greywater is treated in local nature-based systems or in a new compact filter unit. Food waste and blackwater from new water saving toilets is stored in sub-surface tanks close to the house for one to two years, and then treated in a closed system. By combining the separate blackwater and food waste streams into one, logistics are greatly simplified. After collection by a tanker, the material is sanitised and stabilised in a thermophilic aerobic reactor, especially suited for decentralised solutions. No ammonia is lost, and the product has the highest possible agronomic value, with respect to nutrient content and organic matter. The treated material is spread onto farm land during the growing season. The different parts of the system can be implemented step by step over a longer time period.
Solved and Unsolved Cases of Taste and Odor Episodes in the Files of Inspector Cluzeau
Authors: Bruchet A.
Published: May 2018

This paper examines 72 well documented taste and odor (T&O) episodes which occurred primarily in France over a four year period. Using the dominant descriptors, these episodes are classified according to the flavor wheel. The four major odor groups encountered are, group 7 (medicinal-phenolic), group 1 (earthy-musty-moldy), group 8 (chemical-hydrocarbon-miscellaneous) and group 2 (chlorinous-ozonous) respectively at 32, 29, 24 and 10% of the 72 episodes. Episodes from groups 1 and 2 which show the highest rate of unsolved cases are then discussed in detail.
Odor Profiling of Environmental Odors
Authors: Burlingame Gary A.
Published: May 2018

There is a need to standardize a field procedure for odor profiling of environmental odors. There is a need to drive the analytical procedures toward a practical, useful method for profiling odors in contrast to highly complex instrumentation or lab-based techniques. A technique for profiling odors, and tracking odor sources will be outlined. An example of its successful use in profiling odors at a wastewater treatment plant will be described.
Innovative methods for sludge characterization in biological phosphorus removal systems
Authors: Brdjanovic Damir , van Loosdrecht Mark C. M. , Hooijmans Christine M. , Mino Takashi , Alaerts Guy J. , Heijnen Joseph J.
Published: May 2018

This paper describes several techniques and methods for sludge characterization which are recently developed and used in our ongoing research on biological phosphorus removal (BPR): (i) chemical measurement of the poly-hydroxy-alkanoate (PHA) content of the biomass, (ii) bioassay for glycogen determination in BPR systems, (iii) determination of the fraction of denitrifying phosphorus accumulating organisms (DPAOs) in P-removing sludge, (iv) determination of the aerobic and anoxic ATP/NADH2 ratio (δ value) in BPR systems, and (v) determination of the glycogen accumulating organisms (GAOs) / phosphorus accumulating organisms (PAOs) ratio in activated sludge.
Detection of Odour and Health Risk Perception of Drinking Water
Authors: Jardine Cynthia G. , Gibson Nancy , Hrudey Steve E.
Published: May 2018

A substantial proportion of drinking water consumers have resorted to alternatives to their municipal water supply as their source of drinking water. Although health risk perceptions associated with drinking water are ranked low in comparison with other risks, they are subject to influence from the media as a primary information source. Although there may not be a strong connection between odour detection and health risk, consumers who make such a connection cannot be dismissed as irrational. There are substantial grounds to support the possibility that unfamiliar drinking water odours might reveal the presence of substances which pose a potential health risk. Failure to provide credible evidence as to the actual causes of odours will leave water utilities in an indefensible position on associated health risk.
Characterizing Response Variability and Method Uncertainty in Odour Perception Research
Authors: Jardine Cynthia G. , Hrudey Steve E.
Published: May 2018

Data previously collected to determine odour thresholds in fish flesh for individual contaminants identified as possible fish tainting substances from oil sands wastewaters were reanalyzed to determine both the variability in response for an 11 member panel and the range of uncertainty for the detection method. Results are presented for 8 compounds: naphthalene, 1-methylnaphthalene, 2,6-dimethylnaphthalene, 2,3,5-trimethylnaphthalene, 1.4-dimethylbenzene, benzothiophene, dibenzothiophene and 2,5-dimethylphenol. These results demonstrate that substantial variability was present in responses from a group of only 11 panelists who were selected for their sensitivity and consistency, while method uncertainty was tolerably narrow.
Factor Screening for Ozonating the Taste- and Odor-Causing Compounds in Source Water at Detroit, USA
Authors: Atasi Khalil Z. , Chen Theping , Huddleston Judith I. , Young Connie C. , Suffet I. H. (Mel)
Published: May 2018

Three odorants, geosmin (earthy), MIB (2-methylisoborneol) (musty), and IPMP (2-isopropyl-3-methoxypyrazine) (decaying vegetation/musty) were spiked into raw water taken from the Detroit River and subjected to bench-scale ozonation (with and without hydrogen peroxide). Statistical experiment design was employed to investigate operating variables such as ozone dose, ozone addition point, temperature, odorant spike level, and presence of hydrogen peroxide. Two additional odorants, cis-3-hexenyl acetate (grassy) and trans,trans-2,4-heptadienal (fishy) were also tested. Results showed that ozonation was capable of mitigating the spiked odorants in the Detroit source water. Ozone dose was the single most important factor in removing the odorants. Presence of hydrogen peroxide (without dose optimization) had a limited effect on odorant removal at tested pH and alkalinity conditions. Ozone application point and water temperature had significant impacts on ozone residual, but not on odorant removal. MIB was most difficult to remove by ozonation among the five spiked odorants.
Design and optimisation of Nambour Sewage Treatment Plant, Australia
Authors: Cusack Edward , Gloag Graham , Stevens Gerry
Published: May 2018

This paper describes the design and optimisation of the Nambour Sewage Treatment Plant. The plant utilises a 4 Stage Westbank Biological Excess Phosphorus Removal process (3 stage Bardenpho with pre-anoxic zone) and a static primary sludge fermenter (the first of its kind in Australia) to achieve better than a 50 percentile Total Nitrogen 10 mg/l and Total Phosphorus 2 mg/l treated wastewater standard. The plant also uses anaerobic digesters to produce a Grade B stabilised biosolids and lime treatment to remove phosphorus from the sidestream liquors. Commissioning and operational experiences are also discussed.
Optimise what you have first! Low cost upgrading of plants for improved nutrient removal
Authors: Solley David , Barr Keith
Published: May 2018

Brisbane Water has undertaken an investigation into low cost options to imprrove the removal of nitrogen and phosphorus for two of its wastewater treatment plants. Luggage Point Stage 2 (300,000 e.p.) is a conventional activated sludge plant designed for nitrification. Gibson Island (150,000 e.p.) is an extended aeration activated sludge plant designed for nitrogen removal to less than 10 mgTN/l. Extensive modelling and plant simulation were carried out to evaluate the potential of various modified operational modes before the most promising modes were trialed on the full scale plants. Operational trials are proceeding well and improved nitrogen removal to less than 3 mgTN/l for Gibson Island and to less than 10 mgTN/l for Luggage Point have been achieved. Improved phosphorus removal has also been achieved for periods at both plants (less than 4 mgTP/L for Luggage Point and less than 2.5 mgTP/l at Gibson Island). However, phosphorus removal has not been consistent and trials are ongoing to determine the sustainable level of phosphorus removal for these plants. The conclusion of the trials to date is that operational strategies can be implemented for these plants to effect the removal of substantial quantities of nitrogen and phosphorus for a minimum of capital cost. This paper presents the results of the various operational strategies that have been trialed and implemented for both plants. When considering the upgrading of a plant for improved nutrient removal, the principle of “Optimise What You Have First” can sometimes produce surprisingly high nutrient removal levels for a very modest capital expenditure.
Identification of the potential capacity of an intermittently decanted aerated lagoon (IDAL) through process optimisation
Authors: Rajanayagam Castor D. , Nguyen Tung , Sinanovic Yvonne , Walker John W.
Published: May 2018

An optimisation program was carried out at Sydney Water Quakers Hill sewage treatment plant to determine the nitrification and denitrification capacity of the Intermittently Decanted Aerated Lagoon. The program involved changing the IDAL selectors from aerobic to anoxic, implementing aeration control and various process control strategies, and stress testing the plant. The results indicated that anoxic selector and good aeration control improved denitrification, and innovative process control increased capacity. It was demenostrated that IDALs have 33 percent excess capacity.
Sustainable management of BNR biosolids
Authors: Kempton Timothy J. , Cusack Edward
Published: May 2018

The sustainable management of BNR biosolids requires a holistic approach which integrates BNR liquid treatment processes, on-site sludge handling processes and off-site biosolids reuse/disposal. A market focussed biosolids reuse/disposal strategy is a key element of the sustainable management of BNR biosolids. A methodology for preparing a biosolids management strategy is presented. BNR biosolids has a number of characteristics which affect biosolids management. These include: potential for mutrient release, dewaterability, and the need for biosolids stabilisation. Current practices for sludge handling and stabilisation in Australian BNR plants are also discussed.
Exposure Assessment of Taste and Odor Standards Used in the Method of Flavor Profile Analysis
Authors: Schweitzer Linda , Suffet I. H. (Mel)
Published: May 2018

Information on the toxicity of individual chemicals that have been used as known or representative odor standards in the method of Flavor Profile Analysis (FPA) was compiled for an exposure assessment. A full risk assessment was not possible since unit risk values for most of these chemicals do not exist. This study provides a recommendation as to what chemicals can be safely used as known and representative taste and odor standards for the next modification of the Flavor Profile Analysis Standard Method 2170. Excluding any potential odor standard listed as possible or probable carcinogens, there would be no known risk to FPA panelists being exposed to the selected odor reference chemicals at the concentrations used in FPA. Also, the concentrations which panelists are exposed to during an FPA (20 minutes per chemical) are lower than the legal threshold limit values for 8 hour occupational exposures. However, many of the odor reference chemicals have yet to be evaluated for their carcinogenic or noncarcinogenic endpoints. Recommendations are made as to which chemicals should be avoided.
Influence of operating conditions on population dynamics in nitrifying biofilms
Authors: Lazarova Valentina , Bellahcen Danièle , Manem Jacques , Stahl David A. , Rittmann Bruce E.
Published: May 2018

TURBO N® is a circulating-bed biofilm reactor that provides stable operation and high N removal for a wide range of N and BOD loadings. This paper describes the influence of operating conditions on biofilm composition and population dynamics when the TURBO N® is operated to achieve tertiary nitrification, simultaneous carbon and ammonia oxidation and total nitrogen removal when coupled with a pre-denitrification fixed floating bed reactor. In situ specific nitrification rates and respiration tests showed that ammonium and nitrite oxidizers became less active in the biofilm once oxidation of influent BOD became important. Analyses of community structure with oligonucleotide probes targeted to the 16S rRNA showed the same general trends for nitrifiers, but also suggested shifts in the makeup of the ammonium and nitrite oxidizers that could not be detected with respirometry or specific nitrification rates.
Marine Pollution Due to Wastewater Discharge in Kuwait
Authors: Shatti Jassim A. , Abdullah Tamama H. A.
Published: May 2018

The extent of marine pollution and sea beach contamination due to occasional untreated wastewater discharges through emergency outfall of different pumping stations was investigated. Pumping station A 3 has been selected for investigation in the present study. Fecal coliform and Fecal Streptococci as indicators and Salmonella the pathogenic bacteria were examined in the water and sand samples collected from Benid Al-Qar Sea beach.

Water samples and sand samples were collected for a span of 8 months. Sampling of sand was done at distances of 5 m and 10 m on both left and right sides away from the opening of emergency outfall. Shell samples were also collected to ascertain the presence of any contaminant.

The analytical data showed that occasional discharge of wastewater resulted in the accumulation of 710 colonies for F. coliform, 20 colonies for F. Streptococci and 125-colonies/100 ml for Salmonella in sand samples collected from 5 m distance on the left side of an emergency outfall. On moving to 10 m distance the intensity of accumulation was reduced about 50% i.e. 360 colonies, 10 colonies and 75 colonies/100 ml for F. coliform, F. Streptococci and Salmonella respectively. The intensity of accumulation was further reduced in the sand samples collected from the right side of the emergency outfall opening. Gradually all these accumulated types of bacterial cells showed inactivation due to solar radiation exposure and other oceanographic factors. Within a month no growth of any indicator or pathogenic microbe was noticed in the sand samples. Again the F. coliform bacteria started appearing in the sand samples collected during 7 months of the project due to discharge of untreated wastewater under the emergency situation, i.e. renovation of sewage networks. Again the same trend of inactivation of bacterial cells was noticed.

Thus Kuwait Sea beaches are not threatened of marine pollution due to occasional discharge of wastewater.
Microbial ecology of sulfate-reducing bacteria in wastewater biofilms analyzed by microelectrodes and fish (fluorescent in situ hybridization) technique
Authors: Okabe Satoshi , Satoh Hisashi , Itoh Tsukasa , Watanabe Yoshimasa
Published: May 2018

The vertical distribution of sulfate-reducing bacteria (SRB) in microaerophilic wastewater biofilms grown on fully submerged rotating disk reactors (RDR) was determined by the conventional culture-dependent MPN method and in situ hybridization of fluorescently-labelled 16S rRNA-targeted oligonucleotide probes for SRB in parallel. Chemical concentration profiles within the biofilm were also measured using microelectrodes for O2, S2-, NO3- and pH. In situ hybridization revealed that the SRB probe-stained cells were distributed throughout the biofilm even in the oxic surface zone in all states from single scattered cells to clustered cells. The higher fluorescence intensity and abundance of SRB probe-stained cells were found in the middle part of the biofilm. This result corresponded well with O2 and H2S concentration profiles measured by microelectrodes, showing sulfate reduction was restricted to a narrow anaerobic zone located about 500 μm below the biofilm surface. Results of the MPN and potential sulfate reducing activity (culture-dependent approaches) indicated a similar distribution of cultivable SRB in the biofilm. The majority of the general SRB probe-stained cells were hybridized with SRB 660 probe, suggesting that one important member of the SRB in the wastewater biofilm could be the genus Desulfobulbus. An addition of nitrate forced the sulfate reduction zone deeper in the biofilm and reduced the specific sulfate reduction rate as well. The sulfate reduction zone was consequently separated from O2 and NO3- respiration zones. Anaerobic H2S oxidation with NO3- was also induced by addition of nitrate to the medium.
The function of a toluene-degrading bacterial community in a waste gas trickling filter
Authors: Pedersen Anne R. , Arvin Erik
Published: May 2018

The function of a community of toluene-degrading bacteria in a biofilm system was investigated with regard to growth and toluene degradation in order to investigate substrate interactions in the community. This was done by the combination of experimental observations using a specific oligonucleotide 16S ribosomal RNA probe targeting the toluene-degrading species Pseudomonas putida, and by computer simulations (AQUASIM) of the biofilm growth based on a food web model. Biofilms were taken from a lab-scale trickling filter for treatment of toluene-polluted air. The biofilm growth and the activity of P. putida, a representative of the toluene-degrading species in the biofilm which have been described previously were simulated. The simulation indicated that the volume fraction of the toluene degraders in the biofilm decreased from 12% to only 2% (11% of dry weight) during two weeks. In spite of the low fraction in the biofilm, the toluene degraders supported growth of the dominating part of non-toluene-degrading heterotrophs in the biofilm, as toluene was the sole carbon source supplied to the system. The maximum intrinsic growth rate of P. putida in the biofilm was only 20% of the maximum growth rate determined in a batch experiment with suspended P. putida cells.
Upgrading of Secondary Clarifiers by Inclined Plate Settlers
Authors: Saleh Abdulsalam M. , Hamoda Mohamed F.
Published: May 2018

Secondary sedimentation is one of the most commonly used unit operations in wastewater treatment plants. It is customarily designed to achieve solids separation from biologically treated effluent through clarification of biological solids and thickening of sludge. As treatment plants receive increasingly high wastewater flow, conventional sedimentation tanks suffer from overloading problems which result in poor performance. Inclined plate settlers, a form of tube settlers, may have good potential in upgrading sedimentation tanks. This study was conducted to examine the possibility of applying inclined plate settlers in secondary sedimentation in order to upgrade conventional rectangular sedimentation tanks and improve their performance. Experiments were carried out at Al-Awir sewage treatment plant in Dubai using a pilot-scale inclined plate settler which received a mixed liquor stream from the high-rate activated sludge aeration tank. The results showed that inclined plate settlers perform slightly better than conventional type settlers during normal operation of plants, but during peak flows the inclined plate settlers showed much better performance than conventional settlers. The inclined plate settlers are less affected by overloading in comparison to conventional settlers. The solids removal efficiency increased as the hydraulic residence time was increased or as the surface loading rate was decreased. Application of these plates will not cause any interruption of daily operation of treatment plants and could be achieved at minimal cost when compared with other methods such as addition of chemicals, application of deep tanks, … etc. The study revealed that SS is a better parameter than TS, BOD, COD to evaluate the performance of sedimentation tanks. A statistical model was formulated to describe tank performance and design parameters were obtained based on the experimental results.
Biofilm structural forms utilized in bioremediation of organic compounds
Authors: Ebihara Tatsuji , Bishop Paul L.
Published: May 2018

Various biofilm structural forms were observed and characterized in sand columns simulating groundwater aquifer conditions. The mixed microbial community utilized toluene as a sole carbon source. Sand column experiments were conducted with a linear flow velocity of 5.3 m/d and toluene feed concentration of 6 mg/L. Sand columns attained a pseudo steady-state profile for bulk liquid toluene concentration prior to biofilm characterization. Profiles of viable biomass, carbohydrate, and bulk liquid toluene concentration were obtained at 5 cm intervals from 0 to 15 cm depth. Biofilm structural forms were observed using scanning confocal laser microscopy in flow cells that duplicated conditions in the sand columns. The following classes of viable biofilm structures were observed: thin uniform films, protrusions extending from the biofilm, and thin strands of cell aggregates bridging sand grains. Viable biomass profiles indicated approximately 45 percent of the biomass was weakly attached to sand grains versus firmly attached growth held on sand grain surfaces. Biofilm structural forms provided insight into distribution of viable bacteria during aquifer bioremediation and identified opportunities for engineered processes to modify biofilm structures for the optimization of hydrophobic organic compound bioremediation in groundwater aquifers.
Acidogenic Activity: Process of Carbon Source Generation for Biological Nutrient Removal
Authors: Rustrian E. , Delgenes J. P. , Bernet N. , Moletta R.
Published: May 2018

In this study, a sequencing batch reactor (SBR) connected with a two step anaerobic digestion system is proposed in order to investigate the possibility of simultaneous C, N and P removal from wastewater. The system was studied using synthetic wastewater. In this system, the effluent of nitrate from the SBR reactor is added to the acidogenic reactor influent. Nitrate elimination and VFA production are then achieved together in the acidogenic reactor. The performances of three lab-scale reactors, operated for C, N and P biological removal are analyzed. The removals of TOC, TN and TP-PO4 were greater than 96%, 75% and 86%, respectively. The results show that the combination of anaerobic digestion in two step-SBR treatment is effective for simultaneous C, N and P removal. The benefits from this process are the saving of carbon source for denitrification and phosphorus removal. Reactor arrangement made possible the existence of zones where the different bacterial populations involved could coexist. Complete denitrification occurs in acidogenic reactor and hence the methanogenic activity is not reduced nor inhibited by N-NO3 presence, allowing greater TOC removal. A stable P-release and P-uptake took place after coupling of the three reactors. Furthermore, a fast settling, compact sludge is generated in the SBR with the operational conditions applied.
Anaerobic Treatment of Slaughterhouse Wastewater in an Expanded Granular Sludge Bed (EGSB) Reactor
Authors: Núñez L. A. , Martínez B.
Published: May 2018

The performance of an Expanded Granular Sludge Bed (EGSB) reactor for treating slaughterhouse wastewater under mesophilic conditions (35°C), was investigated. The reactor was inoculated with granular sludge from an anaerobic reactor of a brewery factory. The averaged COD removal percentages were 67% for total organic loading rates (BV.TCOD) up to 15 kg COD m−3 d−1 and a hydraulic retention time (HRT) of 5 h. Total suspended solids (TSS) were 90% removed for total solids loads of 6 kg TSS m−3 d−1. Fats were 85% removed and no accumulation of fats on the sludge was observed. The specific methanogenic activity of the sludge, after 140 days, was about three times higher than the sludge inoculated into the reactor. The sludge activity did not significantly change after one year of work. These findings indicate that the anaerobic treatment of slaughterhouse wastewater in an EGSB system appears to be a feasible option.
The sorption capacity of long-time aerated activated sludge demonstrated with 2,6-dimethylphenol
Authors: Gulyas H. , Heldt U. , Sekoulov I.
Published: May 2018

The aim of this study was to evaluate the influence of the duration of activated sludge aeration on sorption capacity of the sludge for the hazardous substance 2,6-dimethylphenol (DMP). DMP was not degraded by normal activated sludge of a pilot scale treatment plant for municipal wastewater as shown by BOD measurements. Sludge aeration was performed for up to 50 days. In sorption assays the mixed liquor suspensions aerated for different times were added to solutions of DMP (10 to 50 mg/l) in tap water in order to give biomass concentrations of 1 g MLSS/l in the sorption assay. Also a sorption isotherm with different concentrations of activated sludge aerated for 50 days with a constant initial DMP concentration was recorded. In the experiments solid phase DMP concentrations of up to 20.9 mg DMP/g MLSS were found depending on aeration time of the activated sludge. Sorption equilibria were reached within short periods (about 10 min). DMP sorption capacity of activated sludge reached a maximum on the 43rd day of aeration and decreased afterwards. But the sorption capacity of sludge aerated for 43 days was significantly lower (about 40% removal of DMP at 1 g MLSS/l from an aqueous solution containing about 50 mg DMP/l) than the adsorption capacity of activated carbon (100% removal of DMP at 1 g activated carbon/l). On the other hand, activated sludge which had been aerated for an optimum period represents a rather good and cheap sorbent for the refractory DMP, considering the low specific surface of activated sludge compared to the specific surface of activated carbon. However, an appropriate method for removal of the sludge loaded with DMP has to be chosen in order to protect the environment against spreading of the hazardous compound DMP. A multistage biosorption process for DMP removal from industrial wastewater is suggested.
Water protection strategies – critical discussion in regard to the danube river basin
Authors: Kroiss H.
Published: May 2018

The River Danube has been a link between Central and Eastern Europe for ages. After the breakdown of the iron curtain new chances for political, economic and cultural development appeared. In regard to water protection the Danube catchment is closely linked to the Black Sea. In order to fulfil the task of water protection different strategies are discussed, based on EU water policy on the one hand and the experience gained from central European development which has a long tradition in solving the problems of multinational river basins on the other. The conclusion is that the success will very much depend on convincing all countries in the basin that water protection is a local, regional, national and international task which needs close co-operation of politicians, economists, engineers and natural scientists at all levels of administration, education and operation. Universities and professional associations will play an important role. The Danube Protection Commission (ICPDR) will have the difficult task of establishing confidence between the countries and to develop a common strategy adapted to the special conditions in the Danube catchment.
Heavy metal assessment in algae, sediments and water from the Bulgarian Black Sea coast
Authors: Jordanova A. , Strezov A. , Ayranov M. , Petkov N. , Stoilova T.
Published: May 2018

The aim of our investigation is a survey of heavy metal pollution in algae, sediments and water from the Bulgarian Black Sea coast and determination of algae species appropriate as bioindicators. The levels of iron, copper, manganese, zinc, lead and cadmium are determined in water, sediments and eight species of macroalgae: (four green: Cladofora laetevirens, Ulva rigida, Enteromorpha intestinalis and Bryopsis plumosa; two brown: Cystoseira crinita and Cystoseira barbata; and two red: Ceramium rubrum and Corallina mediterranium), widely distributed in the Bulgarian coastal zone, and dominant in the Black Sea. The studied area is the littoral coastal zone from four locations - Tuzlata, Ravda, Ahtopol and Sinemoretz. No significant variations between metal concentrations in algae samples are obtained, while for sediments and water there are significant differences between location and season. The Cladofora laetevirens and Ceramium rubrum species show the highest metal content while Cystoseira crinita and Cystoseira barbata show the lowest level. The correlation coefficients and concentration factors of the elements are calculated.
Anaerobic Treatment of Polyethylene Terephthalate (PET) Wastewater from Lab to Full Scale
Authors: Fdz-Polanco F. , Hidalgo M. D. , Fdz-Polanco M. , Encina P. A. García
Published: May 2018

In the last decade Polyethylene Terephthalate (PET) production is growing. The wastewater of the “Catalana de Polimers” factory in Barcelona (Spain) has two main streams of similar flow rate, esterification (COD=30,000 mg/l) and textile (COD=4000 mg/l). In order to assess the anaerobic treatment viability, discontinuous and continuous experiments were carried out. Discontinuous biodegradability tests indicated that anaerobic biodegradability was 90 and 75% for esterification and textile wastewater. The textile stream revealed some tendency to foam formation and inhibitory effects. Nutrients, micronutrients and alkali limitations and dosage were determined.

A continuous lab-scale UASB reactor was able to treat a mixture of 50% (v) esterification/textile wastewater with stable behaviour at organic loading rate larger than 12 g COD/l.d (0.3 g COD/g VSS.d) with COD removal efficiency greater than 90%. The start-up period was very short and the recuperation after overloading accidents was quite fast, in spite of the wash-out of solids. From the laboratory information an industrial treatment plant was designed and built, during the start-up period COD removal efficiencies larger than 90% and organic loading rate of 0.6 kg COD/kg VSS.d (5 kg COD/m3.d) have been reached.
Stochastic generation of spatial rainfall for urban drainage areas
Authors: Willems P.
Published: May 2018

Data from a dense network of rain gauges in the city of Antwerp (Belgium) has been used to study the stochastic structure of spatial rainfall at the small spatial scale of small hydrographic or urban catchments. The derived spatial rainfall model contains two structures: a deterministic structure for the physical description of individual rain cells and cell clusters, and a stochastic structure for the description of the intrinsic randomness in the sequence of different rain events. Such a model forms the basis of the stochastic generation of spatial rainfall for urban catchments. Spatial rainfall generations have many applications: long-term time series of spatial rainfall can be used as input to urban drainage models for the accurate generation of runoff, or to study model-uncertainties and -biases by the simplified use of point rainfall as a model input.
Water Treatment Practice and the Formation of Genotoxic Chlorohydroxyfuranones
Authors: Kronberg L.
Published: May 2018

It is generally known that chlorine disinfection of drinking water that is derived from surface water leads to the formation of mutagenic compounds. A very significant portion (in some cases over 60%) of the mutagenicity has been attributed to the presence of various chlorohydroxyfuranones (CHFs). Besides producing mutagenicity in bacterial assays, the CHFs have been reported to alter the genetic properties of animal and human cells. Recently, one of the compounds, namely 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), was shown to be a potent multiorgan carcinogen in rats. These findings have led to concern about the health effects associated with the mutagens in drinking water.

This paper is a short review of the work aiming at the identification of hydroxyfuranones and related compounds in disinfected drinking water. In addition, results are presented that show how change in water treatment practice is reflected in the mutagenicity of the drinking water and in the concentration of the main mutagen, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX).
Automatic determination of imperviousness in urban areas from digital orthophotos
Authors: Fankhauser R.
Published: May 2018

Determination of impervious areas in urban regions is the most labour-intensive part of data acquisition for rainfall-runoff modelling in urban hydrology. This paper presents an automatic determination method of imperviousness from aerial photographs. The colour, CIR (colour infrared) aerial photographs and orthophotos used have a ground resolution of 25 to 75 centimetres. A maximum likelihood classification algorithm was applied to assign each pixel to a surface category. Classification results were then then overlaid with the subcatchments to determine the imperviousness of each subcatchment. Classification and overlay were carried out with the raster-based GIS IDRISI. The method was tested on various catchment areas, and the results compared with data obtained from manually digitised surfaces. Accuracy of the estimated imperviousness for the entire catchment areas was within 10 %. The deviations for individual subcatchments were much higher. Equivalent results were obtained for colour and CIR photograplhs. A combination of both spectral ranges resulted only in a slight improvement. Consequently, this does not justify the additional costs of the second image. The developed method is an interesting alternative for use on large catchment areas where manual digitisation is very time-consuming and, thus, expensive.
Use of high-resolution geographical databases for rainfall-runoff relation in urbanised areas
Authors: Zech Y. , Escarmelle A.
Published: May 2018

Distributed models are more and more used in regional hydrology. One of the main reasons is their essential compatibility with raster data in Geographical Information Systems. Also in urban hydraulics, distributed models are promising but their development depends on the availability of high-resolution data able to represent urban features. Public databases from satellite imaging are not yet adequate. The paper investigates the possibility of using other kinds of databases designed more specifically for cartography. The advantages and inconveniences of such an approach are pointed out, based on two actual examples.
Removal of Natural Organic Matter by Ultrafiltration: Characterisation, Fouling and Cleaning
Authors: Maartens A. , Swart P. , Jacobs E. P.
Published: May 2018

Organic matter in natural brown water as well as humic acids from a commercial sample were characterised by ultraviolet-visible light-spectroscopy and used in ultrafiltration studies. During ultrafiltration the pure-water flux and the operational flux were measured continuously to determine the degree of membrane fouling. The natural organic matter and commercial humic acid concentrations of the feed and permeate solutions were determined spectrophotometrically. These variables were used in conjunction with conventional flux measurements, to determine the colour-removal efficiency of ultrafiltration as well as the degree of foulant adsorption onto the membranes. Fouled membranes were cleaned with alkaline chemical agents normally used to extract natural organic matter from soil samples. The cleaning efficiency and the effect of cleaning solutions on the membrane selectivity were studied.
The removal of litter from stormwater conduits in the developing world
Authors: Armitage N. P. , Rooseboom A.
Published: May 2018

As the less developed countries (LDC's) become more developed, they have experienced an exponential growth in the production of urban litter. Unfortunately few of these countries have the infrastructure to cope with the removal of this litter, and as a result it tends to end up in the water courses. Grids cannot be placed over stormwater inlets for fear of blockage and consequential flooding. Once the litter has entered the drainage system it is difficult to remove. This paper summarises the results of three years of laboratory investigations sponsored by the Water Research Commission of South Africa into the movement of urban litter through potential trapping structures. The results show substantial agreement with those of an independent investigation carried out in Australia. It concludes that declined self-cleaning screens show the greatest promise for the removal of urban litter from most stormwater conduits and streams in the LDC's.