bluuebunny/crossref_metadata_2025 huggingface dataset:
Organic material solubilization of domestic primary sludge in anaerobic digestion at controlled pH
Authors: Yangin Gomec C. , Speece R.E.
Published: May 2018

The role of the pH in the anaerobic digestion of domestic primary sludge at mesophilic temperature was evaluated. Since solubilization of organic materials is seriously affected by pH, much research has been performed for the evaluation of significant pH influence on the production of soluble organic carbon in the acid phase. In this study, the performance of continuously stirred anaerobic reactors for the production of soluble chemical oxygen demand (SCOD) and volatile fatty acids (VFAs) in domestic primary sludge was investigated. In the first anaerobic reactor, the pH was not controlled (pH-uncontrolled) whereas the pH was fixed at 6.5 (pH-controlled) in the second reactor. Two sets were performed. Results of both sets indicated that, VSS was removed with a corresponding production of VFAs and SCOD in both reactors. However, production of VFAs and SCOD stopped earlier in the pH-controlled reactors. Methanogenic phase started to operate at earlier times whereas hydrolysis and fermentation were still operating in the pH-uncontrolled reactors. The process stability and efficiency of anaerobic digestion of substrates such as domestic primary sludge can be improved by anaerobic digestion elutriated phased treatment (ADEPT) in which the acid elutriation reactor and methanogenic reactor are separated. In this respect, ADEPT was introduced.
Experimental investigation and modelling of the effect of sulfate on anaerobic biodegradation processes in municipal solid waste
Authors: Mora-Naranjo N. , Alamar-Provecho C. , Meima J. , Haarstrick A. , Hempel D.C.
Published: May 2018

The experimental investigations have been carried out in two parts. First, the biodegradation of the organic compounds in the municipal solid waste has been investigated with focus on different sulfate concentrations influencing the methane formation. Second, the inhibition effect of hydrogen sulfide in solution (H2Saq) on the acetate, and methane formation, respectively, has been studied at different pH and temperature values. In solution the equilibrium of hydrogen sulfide (H2S(aq)) and the hydrogen sulfide anion (HS-(aq)) mainly depends on pH. At pH 6.3 the favoured species is H2S(aq) whereas at pH 7.7 the HS-(aq) species is favoured. Additionally, the experiments have been carried out at two different temperatures (35°C and 55°C). According to the acetate and methane formation the H2S(aq) species is observed to have an inhibitory effect. All simulations based on a biodegradation model represented are in good agreement with the experimental data obtained.
Effect of intermediate soil cover on municipal solid waste decomposition
Authors: Márquez-Benavides L. , Watson-Craik I.
Published: May 2018

A complex series of chemical and microbiological reactions is initiated with the burial of refuse in a sanitary landfill. At the end of each labour day, the municipal solid wastes (MSW) are covered with native soil (or an alternative material). To investigate interaction between the intermediate cover and the MSW, five sets of columns were set up, one packed with refuse only, and four with a soil-refuse mixture (a clay loam, an organic-rich peaty soil, a well limed sandy soil and a chalky soil). The anaerobic degradation over 6 months was followed in terms of leachate volatile fatty acids, chemical oxygen demand, pH and ammoniacal-N performance. Results suggest that the organic-rich peaty soil may accelerate the end of the acidogenic phase. Clay appeared not to have a significant effect on the anaerobic degradation process.
The impact of sewage composition on the soil clogging phenomena of vertical flow constructed wetlands
Authors: Winter K.-J. , Goetz D.
Published: May 2018

The infiltration rate and therefore the principal function of a sand based vertical flow constructed wetland (VFCW) is influenced by the content of suspended solids (SS) and chemical oxygen demand (COD) of the waste water supply. In this study there were three operating conditions defined as “No Clogging”; “Partly Clogging” and “Clogging”. Investigations on 21 VFCWs approved analytical differences between these conditions. The content of SS and especially particles ? 50 µm are considered to play a key role. These particles are of the same size as the pores in which seepage mainly occurs. Thus their potential for surface blocking is high. It is concluded that the construction and size of the primary settling has to ensure that the mean concentration of SS after settling does not exceed 100 mg l-1. The results of this study indicate that the area of the VFCW should be designed for a maximum loading rate of 5 g m-2 d-1 and the COD load should not exceed 20 g m-2 d-1.
Compact vertical flow constructed wetland systems - first two years’ performance
Authors: Weedon C.M.
Published: May 2018

In order to move towards optimising wastewater treatment performance by vertical down-flow reed beds, user and installer demands were applied to design, resulting in the “compact vertical flow reed bed” (CVF bed). Performance data are presented for the two years since commissioning a CVF bed and pond system serving eight residents. Particular emphasis was placed on investigating oxygen transfer rate and susceptibility to hydraulic overloading. Average percentage concentration reduction effected by single passage through the bed exceeded 97% for suspended solids and biochemical oxygen demand, and 90% for ammoniacal nitrogen and total Kjeldahl nitrogen. The occurrence of nitrification and denitrification (up to 58%) within the same bed was clearly indicated. Percentage ortho-phosphate removal averaged 92% over the first 17 months’ operation and thereafter fell to approximately 45%. Faecal coliform density underwent an almost four log reduction. Oxygen transfer rate within the reed bed was between 28-36 gO2/m2.d. Normal operation was maintained until six times dry weather hydraulic load rate was exceeded, at which point surface flooding occurred. The capacity of a single vertical flow reed bed to achieve effective treatment of domestic sewage was demonstrated, with no requirement for reduced load rates, promising substantial advantages over established approaches.
On-line monitoring of biofilm formation in a brewery water pipeline system with a fibre optical device
Authors: Tamachkiarow A. , Flemming H.-C.
Published: May 2018

Any advanced anti-fouling strategy must be based on early warning systems which allow for timely, precisely directed and optimized countermeasures. Such systems must be able to detect biofilm growth on representative surfaces. In order to meet this requirement, a fibre optical device (FOS) has been developed. It is based on light which is scattered by objects deposited on the tip of an optical fibre. A receiving fibre collects the signal and forwards it to a detection and quantification unit. Both the sending and the receiving fibre are mounted in a measuring head which is integrated evenly on the inner surface of a water pipeline at representative sites. This device was applied to a water system of a brewery in order to put its reliability to test under practical conditions. The FOS detected the build-up of a deposit which was identified independently as consisting of microorganisms, i.e., a biofilm. A stable, well detectable and reproducible signal could be obtained above a colonization of 105 cells cm−2. Adjustment of the sensitivity of the amplifier allowed for detection of biofilms up to 1010 cells cm−2. Cleaning countermeasures could be detected clearly by a decrease of backscattered light intensity. The system proved to be suitable for on-line, non-destructive, real-time and automatic monitoring for a period of almost two years, and thus, provides an important constituent for an advanced anti-fouling strategy.
Evaluation of substrate clogging processes in vertical flow constructed wetlands
Authors: Langergraber G. , Haberl R. , Laber J. , Pressl A.
Published: May 2018

Substrate clogging is by far the biggest operational problem of vertical flow constructed wetlands. The term “substrate clogging” summarises several processes which lead to reduction of the infiltration capacity at the substrate surface. The lower infiltration rate causes a reduced oxygen supply and further leads to a rapid failure of the treatment performance. Reasons for substrate clogging include accumulation of suspended solids, surplus sludge production, chemical precipitation and deposition in the pores, growth of plant-rhizomes and roots, generation of gas and compaction of the clogging layer. However, it is not clear how much each process contributes to the clogging process. Detailed investigations were carried out at pilot-scale constructed wetlands (PSCWs) using a variety of methods: e.g. soil physical investigations, microbial methods, and various analysis methods of drinking water and wastewater. The paper shows the results of these investigations and presents an equation to calculate the theoretical clogging time.
Removal of indicator bacteria from municipal wastewater in an experimental two-stage vertical flow constructed wetland system
Authors: Arias C.A. , Cabello A. , Brix H. , Johansen N.-H.
Published: May 2018

The removal of sanitary indicator bacteria (total coliforms, faecal coliforms, and faecal streptococci) was studied in an experimental constructed wetland system consisting of (1) a 2-m3 three-chamber sedimentation tank, (2) a 5 m2 vertical flow constructed wetland, (3) a filter-unit with calcite aimed at removing phosphorus, and (4) a 10 m2 vertical flow constructed wetland. The indicator bacteria were enumerated before and after each unit of the wetland system during four monitoring episodes with different loading conditions. At a hydraulic loading rate of 520-1,370 mm/d, the first-stage vertical flow beds removed about 1.5 log-units of total coliforms, 1.7 log-units of faecal coliforms and 0.8 log-units of faecal streptococci. In the second stage bed receiving lower loadings both in term of concentration and quantity (260-690 mm/day), the eliminations were lower. It was not possible in the present study to identify any seasonal effects, but no measurements were done during summer. Recycling of treated effluent back to the sedimentation tank did not affect elimination. Area-based rate constants for the vertical flow wetland receiving effluent from the sedimentation tank averaged 3.2 m/d for total coliforms, 3.3 m/d for faecal coliforms and 2.1 m/d for faecal streptococci. The rate constants depended on loading rates. It is suggested that filtration is a major removal mechanism for bacterial indicator organisms in vertical flow constructed wetland systems.
Phosphorus removal in a vertical upflow constructed wetland system
Authors: Farahbakhshazad N. , Morrison G.M.
Published: May 2018

Mechanisms for P removal in a vertical upflow macrophyte system were studied in controlled laboratory columns filled with sand and planted with Phragmites australis. Substrate P removal was shown to increase with flow rate, a parameter which can be enhanced through effluent recirculation. An alternative substrate (leca, light expanded clay aggregate) provided improved equilibrium adsorption characteristics, but uncrushed and within the kinetic constraints of a macrophyte system gave no improvement for P adsorption over sand. Intermittent loading of the sand based macrophyte system permitted control of the P concentration, with lower effluent peak concentrations for increased resting interval (no P inflow). Where P loading was targeted, continuous flow provided the optimum mass removal conditions.
On-line biofilm monitoring by "BIOX" electrochemical probe
Authors: Mollica A. , Cristiani P.
Published: May 2018

The innovative electrochemical monitoring probe (BIOX) recently developed to improve the antifouling treatments of cooling systems in industrial plants is presented. On the basis of the good results obtained from applications on marine sites, some research has been started to validate this technique in biofilm growth and prevention of microbial corrosion in fresh and drinking waters.
Dynamic response of biofilm to pipe surface and fluid velocity
Authors: Cloete T.E. , Westaard D. , van Vuuren S.J.
Published: May 2018

Biofouling in pipelines is a function of the inner roughness of the specific piping material that is used in distribution systems and the concomitant biofilm formation. To test the effect of velocity on the growth of biofilm, a Roto-Scope was designed and built to imitate different materials and flow conditions in potable water distribution systems. Biofilm formation was monitored using DAPI staining and the total number of viable bacteria. Increased velocity in the system resulted in a specific detaching velocity, where the formation of biofilm was limited. Most of the time these detaching velocities were not the highest velocities tested. The range of detaching velocities was between ±3 m.s−1 and 4 m.s−1. A flow velocity within this range would thus be ideal for achieving reduced biofilm growth in a distribution system.
Pumice soil: a potential wetland substrate for treatment of domestic wastewater
Authors: Njau K.N. , Minja R.J.A. , Katima J.H.Y.
Published: May 2018

Laboratory and fieldwork studies were carried out to evaluate the potential of pumice soil for use as a wetland substrate in wastewater treatment. The composition of pumice soil was analysed by x-ray fluorescence (XRF) and x-ray diffraction (XRD) techniques. Adsorption kinetic studies were carried out in a semi-batch recycle system. Fieldwork tests were carried out on Subsurface Flow Constructed Wetland (SSFCW) cells planted with Phragmites mauritianus and Vetiveria zizanioides. The results have shown that pumice soil composition contains among other elements Al, Ca, Fe and Mg, which are positive indicators for phosphorus adsorption. The main minerals observed by XRD were augite, hematite, and sodium titanium silicate. Phosphorus adsorption kinetics have shown that phosphorus is adsorbed on pumice soil following first order kinetics and the adsorption was highly influenced by mass transfer. Approximately 3% of the phosphorus was removed by plant uptake.
The design, operation and performance of a municipal hybrid reed bed treatment system
Authors: O'Hogain S.
Published: May 2018

The first Irish municipal application of a hybrid reed bed treatment system (RBTS) was designed and constructed at Colecott, County Dublin. The hybrid design for Colecott RBTS was based on modifications to the Max Planck Institute Process (MPIP). The constituent parts of the design were a septic tank, a pump sump, two stage vertical flow beds, a secondary settlement tank, a horizontal reed bed, an outlet chamber and outfall pipe. The population at the time of design was 48, but with future development in mind 60 was used as the population equivalent (pe). Construction and operational characteristics are outlined. Results of a two year monitoring study are presented, showing good performance and producing a final effluent with 88% BOD removal, 89% COD removal and 99% SS removal.

Percentile compliance with EU discharge standards were BOD 60%, COD 100%, SS 100% with 50% for nitrogen and 0% for PO4. Surface water input increased flows to twice the average, resulting in increased maintenance visits without affecting results. The ability to deal with the excess inflow is demonstrated by the system. The method of distribution to the primary vertical beds was satisfactory while that on the secondary vertical beds was not.
Monitoring of biofilm reactors using natural fluorescence fingerprints
Authors: Wolf G. , Almeida J.S. , Crespo J.G. , Reis M.A.M.
Published: May 2018

Natural fluorescence as a method to monitor biofilm processes was studied, using the example of an extractive membrane bioreactor for the degradation of 3-chloro-4 methylaniline and 1,2-dichloroethane. Non-invasive, on-line, in-situ 2D fluorometry monitoring was employed to elicit biofilm process status. The fluorescence fingerprints were deconvoluted in a pattern recognition approach using artificial neural networks (ANN) through association with key process performance parameters.
Controlling a combined lagoon/reed bed system using the oxidation-reduction potential (ORP)
Authors: Kayser K. , Kunst S. , Fehr G. , Voermanek H.
Published: May 2018

Lagoon systems achieve good and stable effluent data in regard to organic pollutants, but they charge the receiving waters with relatively high ammonium loads. Therefore an existing lagoon-plant was extended by a vertical flow reed-bed for the special purpose of nitrification. This paper presents the efficiency of the combination plant as well as the possibility to monitor and control the reed-bed operation by the oxidation-reduction potential (ORP). The results show that the combination plant achieved excellent purification results, the average efficiency degrees were 97% for COD, 77% for Ntotal and 94% for the TKN elimination. The ORP in the effluent of the reed bed showed a clear dependence in its characteristic course and its absolute values on the current nitrification performance, the oxygen supply and the hydraulic behaviour of the reed bed. Therefore the ORP is a very good indicator for the state of the reed bed, which ultimately results from the accumulation of a large number of different influencing parameters. As the preservation of aerobic conditions in the reed bed is the crucial prerequisite for a high nitrification performance and for the avoidance of clogging, the ORP thus offers the possibility of immediate operation control.
Extraction of exopolymers from biofilms: the protective effect of glutaraldehyde
Authors: Azeredo J. , Henriques M. , Sillankorva S. , Oliveira R.
Published: May 2018

The extraction of the exopolymeric matrix is a prerequisite to properly assessing the composition of the biofilm. Several extraction methods have already been developed, however, no universal method has yet been adopted because the compromise between high yields of extraction and minimum cell lysis is difficult to establish. In fact, most of the extraction methods promote leakage of intracellular material. The most common extraction methods, Dowex resin and sonication, were assayed in biofilms of Pseudomonas fluorescens and Alcaligenes denitrificans submitted to a pre-treatment with glutaraldehyde (GTA). The assessment of ATP released after extraction was used as a criterion of cell lysis. The results showed that GTA is a protective agent against cell lysis. The pre-treatment with GTA is particularly useful combined with sonication.
Oxygen flux implications of observed nitrogen removal rates in subsurface-flow treatment wetlands
Authors: Tanner C.C. , Kadlec R.H.
Published: May 2018

Nitrification, an oxygen-requiring microbial process, is generally considered the rate-limiting step for N removal in subsurface-flow constructed wetlands treating organic wastewaters. We used a simplified model of sequential N transformations and sinks to infer required rates of oxygen supply at 5 stages along experimental wetland mesocosms supplied with four different organic wastewaters with contrasting ratios of COD: N and forms of N. Mass balances of water-borne organic, ammoniacal and nitrate N, and plant and sediment N uptake showed average net rates of N mineralisation ranging from 0.22-0.53 g m-2 d-1, nitrification 0.56-2.15 g m-2 d-1, denitrification 0.47-1.99 g m-2 d-1 (60-84% of measured N removal) and plant assimilation 0.28-0.47 g m-2 d-1. The nitrogenous oxygen demand (NOD) required to support the observed nitrification rates alone was high compared to expected fluxes from surficial and plant-mediated oxygen transfer. In the presence of high levels of degradable organic matter (COD removal rates up to 66 g m-2 d-1), heterotrophs with significantly higher oxygen affinities and energy yields are expected to out-compete nitrifiers for available oxygen. Problems with commonly held assumptions on the nature of coupled nitrification-denitrification in treatment wetlands are discussed.
Treatment of freshwater fish farm effluent using constructed wetlands: the role of plants and substrate
Authors: Naylor S. , Brisson J. , Labelle M.A. , Drizo A. , Comeau Y.
Published: May 2018

Freshwater fish farm effluents have low nutrient concentrations but high flow rates, resulting in a pollutant load, especially phosphorus (P), causing eutrophication. The feasibility was tested of a treatment combining, within a single constructed wetland, the contribution of macrophytes for reducing organic matter and nitrogen (N), with the high efficiency of steel slag and limestone for P removal. Twenty subsurface flow (SSF) basins of 280 L with different combinations of plants (Phragmites communis or Typha latifolia) and substrates (steel slag, limestone, gravel, peat) were fed with a reconstituted fish farm effluent in a greenhouse experiment. Pollutant removal was generally very good under all treatments. N and organic matter removal were correlated with plant biomass while P removal was better in substrates with steel slag and limestone. However, the high pH of the P-adsorbing substrate was detrimental to plant growth so that no combination of plants and substrates could maximise in one step the simultaneous removal of all evaluated pollutants. Therefore, the use of two sequential units is recommended, a first one consisting of a macrophyte planted basin using a neutral substrate to remove organic matter and N, followed by a second unplanted basin containing only a P-adsorbing substrate.
An assessment of mosquito breeding and control in four surface flow wetlands in tropical-subtropical Australia
Authors: Greenway M. , Dale P. , Chapman H.
Published: May 2018

In Queensland, Australia, the tropical-subtropical climate is ideal to promote macrophyte growth in surface flow wetlands; however, there have been concerns that constructed wetlands are potential breeding sites for disease-bearing mosquitoes. The aim of this study was to assess whether mosquitoes were breeding in these constructed wetlands, and if so, where they breed, and what parameters might influence breeding: e.g. water quality, vegetation, or macroinvertebrate communities. A study of four surface flow constructed wetlands located in different climatic regions was undertaken. Mosquito larvae were sampled using 240 ml dippers and macroinvertebrates using dip nets. The wetland with the greatest biodiversity of macrophytes and macroinvertebrates had the least number of mosquito larvae (< 1% of all dips). Samples with most mosquito larvae occurred amongst dense mats of Paspalum grass or dead Typha. Despite the presence of larvae in some parts of these wetlands very few late instars or pupae were found i.e. completion of the mosquito life cycle to adult mosquitoes was unsuccessful.

This study has shown that the presence of mosquito larvae can be minimised by increasing macro-invertebrate biodiversity, by planting a variety of macrophyte types and species, excluding aggressive plant species, and maintaining at least 30% open water. Macroinvertebrates are probably a crucial factor in the control of mosquito larvae ensuring that predation of the early instars prevents or limits the development of pupae and the emergence of adults.
Dynamics of extracellular polymeric substances in UASB and EGSB reactors treating medium and low concentrated wastewaters
Authors: Puñal A. , Brauchi S. , Reyes J.G. , Chamy R.
Published: May 2018

In this work the dynamic study of EPS (Extracellular Polymeric Substances) concentration and distribution during the operation of two different reactor configurations (UASB and EGSB) is presented, treating medium (5 g COD/l) and low-concentrated (0.5 g COD/l) wastewater. Medium-concentrated wastewater was supplied for granules maturation as well as for stabilisation of the process. The effect of substrate change on granule characteristics was followed in both reactors. Total concentration of EPS associated to steady operation, was higher in the UASB reactor. The change to a low-concentrated substrate led to an increased difference, promoting a sharp destabilisation of the EGSB reactor, observing an increment in filamentous structures, causing biomass flotation and wash out. Although total concentration of EPS remained almost constant in the UASB reactor, their composition and distribution presented significant differences. The ratio of protein/polysaccharides as well as acidic-polysaccharides/total (neutral + acidic) polysaccharides decreased drastically in the EGSB reactor, while in the UASB reactor, the decrease was not so important and not enough for destabilisation of granule structure. Moreover, polysaccharides distribution seemed to have an important role in granule stability being enough to maintain granule cohesion only in the case of the UASB reactor. These observations point to composition and distribution of EPS rather than their total concentration as key parameters for granule stability and settleability.
Evolution of the bacterial community during granules formation in denitrifying reactors followed by molecular, culture-independent techniques
Authors: Etchebehere C. , Cabezas A. , Dabert P. , Muxí L.
Published: May 2018

The microbial community in two acetate-fed denitrifying reactors, inoculated with methanogenic sludge, was monitored by 16S rDNA-based methods (SSCP and FISH). Both reactors converged to similar, stable communities. The predominant organisms belonged to the genera Thauera, Paracoccus and Denitrobacter, detected both by molecular and culture-based methods.
Politics and governance at the interface between water and development
Authors: Abrams L.
Published: May 2018

Water is not just a technical issue - it always has to be addressed within a complex political context. The water sector professional is generally unskilled in political processes, but political skill and awareness is needed to avoid negative politicization of water.
Simultaneous biodegradation of a phenol and 3,4-dimethylphenol mixture under denitrifying conditions
Authors: Puig-Grajales L. , Rodríguez-Nava O. , Razo-Flores E.
Published: May 2018

Denitrification is a feasible alternative for the treatment of phenolic bearing-wastewaters. The aim of this study was to evaluate the biodegradability of phenolic compounds, as the only carbon and energy source in batch and continuous experiments, using nitrate as a final electron acceptor. Experiments in a continuous upward anaerobic sludge bed reactor demonstrated the possibility of biodegrading a mixture of phenol and 3,4-dimethylphenol at organic loads of 251.6 and 39.5 mg/L-d, respectively, at a COD/NO3--N ratio of 2.57. A nitrogen production efficiency of 86% was obtained according to the nitrate consumption. GC-MS analyses demonstrated that m-cresol was an intermediate of 3,4-dimethylphenol degradation in batch conditions, and had an inhibitory effect on phenol degradation.
Anaerobic digestion of manure and mixture of manure with lipids: biogas reactor performance and microbial community analysis
Authors: Mladenovska Z. , Dabrowski S. , Ahring B.K.
Published: May 2018

Anaerobic digestion of cattle manure and a mixture of cattle manure with glycerol trioleate (GTO) was studied in lab-scale, continuously stirred tank reactors (CSTR) operated at 37¡C. The reactor codigesting manure and lipids exhibited a significantly higher specific methane yield and a higher removal of VS than the reactor treating manure. Microbial population analysis done by cultivation - most probable number (MPN) test and specific methanogenic activity (SMA) measurement, revealed higher MPN and increased SMA of methanogenic populations of biomass from the reactor codigesting manure and lipids. Spatial microbial distribution and activity was studied in digested materials fractionated into size of particles > 200 μm, 50-200 μm and 0.45-50 μm. With manure, the main pool of methanogenic activity from propionate, butyrate and hydrogen was associated with the particles > 200 μm, while the activity of acetotrophic methanogens was uniformly distributed in all fractions. When digesting manure and lipids, an enhanced methanogenesis was detected both for particles > 200 μm and the 50-200 μm fraction. The molecular methods - temperature gradient gel electrophoresis (TGGE), cloning library and sequencing of 16S rDNA - showed presence of a restricted number of archaeal species in both reactors. The vast majority of clones was phylogenetically most closely related to Methanosarcina siciliae.
Environmental flow requirements in arid zone rivers – a case study from the Lake Eyre Basin, central Australia
Authors: Costelloe J.F. , Puckridge J.T. , Reid J.R.W. , Pritchard J. , Hudson P. , Bailey V. , Good M.
Published: May 2018

The ARIDFLO project takes a multi-disciplinary approach to the collection and analysis of data required to formulate appropriate environmental flow requirements for rivers in the Lake Eyre Basin. The key drivers of the ecological processes underpinning the health of these rivers are identified by modelling whole-of-ecosystem biological responses to hydrological events over a range of spatial and temporal scales. First, the hydrology of these poorly gauged (often ungauged) rivers needs to be modelled and validated to mimic real flow and inundation patterns at the catchment, reach and waterbody scale. Modelled and actual discharge data are then used to provide a suite of hydrological predictor variables which, in conjunction with other environmental variables, are used to model observed biotic responses. The key hydrologic and environmental drivers identified by the statistical models need to be taken into account when determining environmental flow requirements for these river systems. Further work is required to assess the predictive power of the models in the highly variable, complex systems of the Lake Eyre Basin rivers.
Issues in environmental water allocation – an Australian perspective
Authors: Schofield N. , Burt A.
Published: May 2018

Environmental water allocation is a critical issue in Australia and internationally. It has been prominent in Australia for a little over ten years during which time major policy and scientific advances have been made, but little implementation. This paper examines current understanding of environmental water allocation across a broad range of disciplines including the biophysical sciences, social sciences, economics, law, and policy. Development of practical methods for assessing environmental water requirements and experience with implementation in Australia are discussed. The paper concludes with thoughts on future needs.
Restoring the Mauri of Oruarangi Creek
Authors: Mills M.
Published: May 2018

In recognition of the societal and cultural values of ecological restoration several community-based programs have been developed throughout the world. In particular those with interests in the field of freshwater and riparian management have developed numerous programs to encourage community involvement in their management. While each of these programs gives de facto recognition to an ethos typically espoused by indigenous peoples, the concerns, values and localised knowledge of indigenous peoples continues to remain excluded from the management process. In documenting key aspects of the proposed restoration of Oruarangi Creek this paper aims to provide an example of how the concerns, values and knowledge of local indigenous communities can form a major component of the restoration process.
Groundwater–surface water interaction in inland New South Wales: a scoping study
Authors: Braaten R. , Gates G.
Published: May 2018

Groundwater and surface water have traditionally been managed separately in New South Wales (NSW). However, where rivers and aquifers are hydraulically connected, groundwater pumping has the potential to deplete streamflow. To highlight the major areas of connection in inland NSW, major streams were overlaid with groundwater depth data and the locations of irrigation bores. A consistent pattern was revealed related to basin geomorphology. The main areas of connection are the mid-sections of the major rivers where alluvial systems are well developed yet still narrow and constricted and groundwater depths are shallow. The mapping was validated and the processes explored by calculating water balances for a connected and disconnected reach in the Murrumbidgee River. These showed that, in highly connected reaches, river losses and/or gains are closely related to groundwater levels.
Airlift-reactor design and test for aerobic environmental bioprocesses with extremely high solid contents at high temperatures
Authors: Feitkenhauer H. , Maleski R. , Märkl H.
Published: May 2018

Bioprocesses at high temperatures gained considerably in importance within the last years and several new applications for aerobic, extreme thermophilic environmental bioprocesses are emerging. However, this development is not yet matched by adequate bioreactor designs, especially if it comes to the treatment of solids. In this communication we propose the use of airlift reactors to bridge this gap. The design of an internal draught tube bioreactor (AreaRiser/AreaDowncomer. 1; Height/Diameter . 8) is described in detail. The influence of the temperature on gas hold-up, liquid velocity and mixing characteristics was investigated. It was shown that this reactor could hold up to 1 t quartz sand per m3 in suspension at moderate aeration rates. Despite the decreasing oxygen solubility, the oxygen transfer rate increased with rising temperature due to the improved mass transfer parameters. With rising solid content, the oxygen transfer rate increased and reached a maximum at a solid content of about 140 kg m-3 before it decreased again. However, it is only slightly reduced at the highest solid contents. The results demonstrate that aerobic bioprocesses at high temperatures are not only feasible, but can be very efficient if carried out in proper bioreactors.
Hazardous waste landfill leachate treatment using an activated sludge-membrane system
Authors: Setiadi T. , Fairus S.
Published: May 2018

This research was aimed to investigate the capability of a combined system of activated sludge and microfiltration processes with backflushing technique to reduce organic carbon and nitrogen compounds in hazardous landfill leachates. The experiments included acclimation, batch and continuous processes. The continuous process was conducted with a 24 hour HRT (Hydraulic Retention Time), and the SRT (Solid Retention Time) ranged from 16 to 36 days. The aeration basin volume was 5 L and the membrane filter used was a hollow fiber module made from polypropylene with pore size of 0.2 μm.

The batch process (without membrane separation) achieved its steady state condition over a period of 33 days. The removal of COD, BOD5 and ammonia-N were 52.5%, 94.3% and 75.5%, respectively. The kinetic parameters obtained are as followed : the maximum specific growth rate constant (μm): 0.96/day and the saturation substrate constant (Ks): 16,445.32 mg/L. The high value of Ks indicated that the leachate was not easily biodegraded. The continuous process revealed that the system with SRT of 32 days was more stable than that of 16 and 24 days. The reduction of COD, BOD5 and ammonia-N were 31.3%; 66% and 98%, respectively. The stable flux was achieved around 5 L/m2.hour.
Enrichment of nitrifying microbial communities from shrimp farms and commercial inocula
Authors: Paungfoo C. , Prasertsan P. , Intrasungkha N. , Blackall L.L. , Bhamidimarri R.
Published: May 2018

Nitrifying bacteria were selected from shrimp farm water and sediment (ÒnaturalÓ seed) in Thailand and from commercial seed cultures. The microbial consortia from each source giving the best ammonia removal during batch culture pre-enrichments were used as inocula for two sequencing batch reactors (SBRs). Nitrifiers were cultivated in the SBRs with 100 mg NH4-N/l and artificial wastewater containing 25 ppt salinity. The two SBRs were operated at a 7 d hydraulic retention time (HRT) for 77 d after which the HRT was reduced to 3.5 d. The amounts of ammonia removed from the influent by microorganisms sourced from the natural seed were 85% and 92% for the 7 d HRT and the 3.5 d HRT, respectively. The ammonia removals of microbial consortia from the commercial seed were 71% and 83% for these HRTs respectively. The quantity of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) was determined in the SBRs using the most probable number (MPN) technique. Both AOB and NOB increased in number over the long-term operation of both SBRs. According to quantitative fluorescence in situ hybridisation (FISH) probing, AOB from the natural seed and commercial seed comprised 21 ± 2% and 30 ± 2%, respectively of all bacteria. NOB could not be detected with currently-reported FISH probes, suggesting that novel NOB were enriched from both sources. Taken collectively, the results from this study provide an indication that the nitrifiers from shrimp farm sources are more effective at ammonia removal than those from commercial seed cultures.
Substrata effects on bacterial biofilm development in a subsurface flow dairy waste treatment wetland
Authors: Silyn-Roberts G. , Lewis G.
Published: May 2018

Biofilm development on two distinct rock substrata was investigated both in vitro and in a subsurface flow wastewater treatment wetland in order to determine the effect of hydrophobicity on initial bacterial adsorption, tertiary biofilm development and microbial population structure. Two commonly used wetland rock types, slag (a hydrophobic by-product of the steel smelter industry) and greywacke (a more hydrophilic sedimentary rock) were evaluated. In vitro investigations of initial microbial adsorption trends showed that the more hydrophobic slag displayed rapid bacterial adsorption rates compared to greywacke. Mean microbial adsorption rates of a mixed wetland bacterial population over 5 hours, described using a first order kinetics model, were 1.3 × 10-12 m/sec for slag and consistently lower at 8.7 × 10-13 m/sec for greywacke. Pristine rock studs of the two substrata were also exposed to wetland microbial communities during a six week field trial using confocal scanning laser microscopy to determine tertiary biofilm structure and fluorescent in situ hybridisation to investigate bacterial populations. During the first five weeks of growth CSLM analysis revealed that 75% of biofilms on slag were thicker and had greater coverage compared with those grown on greywacke. After six weeks of growth over 50% of the tertiary biofilms were structurally very similar on both rock types and only 25% of those grown on slag were larger than those on greywacke. In situ hybridisation analysis of bacterial populations revealed very little difference in population structure between biofilms grown on slag and those grown on greywacke. Eubacteria were present as a very high proportion of total bacteria throughout biofilm development (74.3%). The beta subgroup was the most populous of the Proteobacteria (31.4%) followed by the gamma subgroup (13.4%)and the alpha subgroup (1.3%).

The results of this study suggest that slag, as a more hydrophobic substratum, promotes the initial adsorption of bacteria during early biofilm growth and better supports mature biofilm structures when used in wetlands. This study has implications for the design and construction of wastewater treatment wetlands.
Drinking water quality management: a holistic approach
Authors: Rizak S. , Cunliffe D. , Sinclair M. , Vulcano R. , Howard J. , Hrudey S. , Callan P.
Published: May 2018

A growing list of water contaminants has led to some water suppliers relying primarily on compliance monitoring as a mechanism for managing drinking water quality. While such monitoring is a necessary part of drinking water quality management, experiences with waterborne disease threats and outbreaks have shown that compliance monitoring for numerical limits is not, in itself, sufficient to guarantee the safety and quality of drinking water supplies. To address these issues, the Australian National Health and Medical Research Council (NHMRC) has developed a Framework for Management of Drinking Water Quality (the Framework) for incorporation in the Australian Drinking Water Guidelines, the primary reference on drinking water quality in Australia. The Framework was developed specifically for drinking water supplies and provides a comprehensive and preventive risk management approach from catchment to consumer. It includes holistic guidance on a range of issues considered good practice for system management. The Framework addresses four key areas:•Commitment to Drinking Water Quality Management,•System Analysis and System Management,•Supporting Requirements, and•Review.

The Framework represents a significantly enhanced approach to the management and regulation of drinking water quality and offers a flexible and proactive means of optimising drinking water quality and protecting public health. Rather than the primary reliance on compliance monitoring, the Framework emphasises prevention, the importance of risk assessment, maintaining the integrity of water supply systems and application of multiple barriers to assure protection of public health. Development of the Framework was undertaken in collaboration with the water industry, regulators and other stakeholders, and will promote a common and unified approach to drinking water quality management throughout Australia. The Framework has attracted international interest.
The effects of de-icing in Helsinki urban streams, Southern Finland
Authors: Ruth O.
Published: May 2018

The environmental effects of road salt have been studied in Finland mainly in order to monitor and reduce groundwater contamination. In urban areas the road salt used for road maintenance in winter ends up in the storm water drains and receiving water bodies. We report here on water samples taken in 1998-1999 from three urban streams with catchments varying in area 1.7 to 24.4 km2 in different parts of the City of Helsinki.

Despite efforts to reduce the amount of road salt, high concentrations were found in the urban stream water. Sudden variations in water quality were very marked during the spring flood period, with sodium and chloride concentrations varying over nine-fold within one day. Some 35-50% of the salt used on the roads in Helsinki passes into natural streams and from there into the sea. The significant positive correlation between NaCl and dissolved zinc in stream water was observed. The results show that it is important to monitor water quality, especially at the beginning of the spring flood period, when road salt and other contaminant levels are markedly high in urban streams.
Low temperature biodegradation of airport de-icing fluids
Authors: Revitt D.M. , Worrall P.
Published: May 2018

The biodegradabilities of glycol- and acetate-based aircraft de-icing fluids on airport surfaces have been investigated at three temperatures between 0°C and 10°C. The aqueous solubilities of these substances can result in high BOD loadings in runoff and pose serious toxicity problems in receiving waters. The measured surface biodegradation rates for de-icing products based on ethylene/diethylene glycol (Konsin), propylene glycol (Kilfrost) and potassium acetate (Clearway) at 4°C were 0.082, 0.073 and 0.033 day-1. The resulting reductions in the potential BOD loadings, of a single application of a typical mixture of these products, over a 5 day biodegradation period are predicted to be 32.9%, 30.2% and 21.4%, respectively at 8°C, 4°C and 1°C. For consecutive daily applications, the comparable cumulative reductions over 5 days are 20.8%, 18.9% and 13.3%. The subsequent savings in the amount of treatment required for airport runoff prior to safe discharge to receiving waters are discussed and hence the relevance of surface biodegradation processes to the design of stormwater treatment systems involving the wash-off of biodegradable pollutants following retention on urban surfaces.
Facilities for treatment of stormwater runoff from highways
Authors: Aldheimer G. , Bennerstedt K.
Published: May 2018

Stormwater is the major water inflow to many water bodies in Stockholm. Stockholm City has adopted a strategy, which defines the need to treat different kinds of stormwater entering different receiving waters. The Stockholm Water Company has tested various ways of treating stormwater. In 2000, the City of Stockholm arranged a stormwater treatment technology competition. Prizes were awarded to four winning entries. One installation was completed in 2001 and another is now under construction.
Winter operation of an on-stream stormwater management pond
Authors: Marsalek P. M. , Watt W.E. , Marsalek J. , Anderson B.C.
Published: May 2018

The winter operation of an on-stream stormwater management pond in Kingston, Canada is characterised. The pond froze over in late November. Ice thickness varied from 0.2 to 0.5 m, and initially, was well described by Stefan's formula. The measured and modelled velocity field indicated a fast flow region, a small dead zone and a large recirculating zone. During a snowmelt event, near-bottom velocities reached 0.05 m·s-1, but were not sufficient to scour the bottom sediment. Pond water temperature increased with depth, from 0.5°C to 3.5°C. The dissolved oxygen (DO) levels observed in the pond (6-13 mg·L-1) indicated stable aerobic conditions at the sediment-water interface. In one brief episode, DO fell to zero after a long cold spell. Reduction in DO readings from inlet to outlet indicated an oxygen consumption of about 1.7 kg·day-1. pH ranged from 7.1 to 8.9. Conductivity readings indicated large quantities of total dissolved solids, representing mostly chloride from de-icing agents. During baseflow, conductivity increased with depth (total dissolved solids concentrations up to 1,200 mg·L-1 near the bottom), indicating density stratification. Average trace metal concentrations were mostly below detection limits.