bluuebunny/crossref_metadata_2025 huggingface dataset:
A new method for extraction of extracellular polymeric substances from biofilms and activated sludge suitable for direct quantification of sorbed metals
Authors: Wuertz S. , Spaeth R. , Hinderberger A. , Griebe T. , Flemming H.-C. , Wilderer P. A.
Published: May 2018

A method for extraction of extracellular polymeric substances (EPSs) with a dicyclohexyl-18-crown-6 ether was developed to determine levels of organic and inorganic contaminants sorbed to EPS. The crown ether selectively binds alkaline and alkaline earth metals but not heavy metals. The effectiveness of the extraction procedure was higher than that of 2 other methods tested and comparable with that of a method based on a cation exchange resin. On average it was possible to extract 20% of the TOC, 12% of the total protein content, and 4% of the total carbohydrate content of sludge or biofilm biomass. Metal sorption studies in activated sludge showed no influence of exposure time on the fractionation of metals within the biomass. Metals sorbed mostly to cellular material. In biofilms 12.2% of the cadmium and 9.1% of the zinc added was found in the EPS. In activated sludge EPS contained only 2.9% zinc. The distribution of metals within the biomass was dose dependent. The percentage of metals found in EPS decreased with increasing metal concentration. This indicates a higher affinity of metals for cellular binding sites. Time course experiments in a rotating biofilm annular reactor, which consisted of an external cylinder with removable slides and an internal solid drum, revealed a gradual change in zinc concentration associated with EPS, although the total zinc concentration in the biomass remained constant. Concurrently, the amount of extractable EPS decreased. This was a consequence of a microbial population shift, with bacterial counts decreasing and algal and fungal biomass increasing. Using confocal laser scanning microscopy and the fluorescent metal complexing agent Newport Green for in situ detection of zinc it was shown that metals were bound to algae and fungi in the latter part of the experiment. The biofilm became more and more heterogeneous coinciding with a decrease in EPS. To summarize, the observed sorption behavior of metals cannot be explained with the conventional paradigm of EPS ashydrophilic gel. Obviously, different binding mechanisms must be invoked to explain the role of EPS in the sorption and removal of toxic substances in activated sludge and biofilm systems. It is important to consider the microbial population to understand differences in sorption in different matrices.
Exopolysaccharides in biofilms, flocs and related structures
Authors: Sutherland I. W.
Published: May 2018

In biofilms, flocs and similar multispecies microbial communities, exopolysaccharides (EPSs) are always present, frequently as the major component other than water. The EPSs vary widely in their composition, structure and properties and thus it is impossible to generalise about their contribution to biofilm or floc structure. Relatively few of the polymers obtained from biofilms and flocs have been adequately purified and analysed but such evidence as is so far available suggests that the polysaccharides closely resemble those synthesised by the corresponding planktonic bacteria. From a knowledge of the physical properties of these, it is now possible to present a reasonably accurate picture of some of the factors which they may contribute to the structure and stability of complex aggregates of micro-organisms in biofilms and flocs.
SEM-EDS for determining the phosphorus content in activated sludge EPS
Authors: Oosthuizen D. J. , Cloete T. E.
Published: May 2018

Not all phosphorus removed in activated sludge systems can be accounted for by polyphosphate accumulating organisms (PAO). A method for the qualitative and quantitative in situ characterization of PAO cell clusters and closely associated extracellular polysaccharides (EPS) is described. X-ray microanalysis was performed on samples from four activated sludge plants situated in Pretoria, South Africa. Analyses were done by means of Scanning Electron Microscopy (SEM) combined with Energy Dispersive Spectrometry (EDS). Cell clusters with associated EPS on average contained between 57 and 59% phosphorus, while EPS alone contained on average between 23 and 30% phosphorus. Results suggest that phosphorus removal in activated sludge might be due not only to PAO, but also by EPS acting as a phosphorus reservoir. Extraction of EPS from two different activated sludge plants yielded different amounts of EPS, which, in combination with SEM-EDS, may shed light on different phosphate uptake abilities of different activated sludges.
Performance indicators in water and sanitation for developing areas
Authors: Pybus P. , Schoeman G.
Published: May 2018

There is a move throughout the developed world to introduce benchmarking techniques to the management of water and sanitation systems. The indicators that are being considered for benchmarking purposes tend to cover a broad band of activities that are part of the scope of management of large organisations. Most of the lists that have been prepared do not really cater for the implementation and operation of small rural schemes. The greatest need is the implementation of sustainable schemes for this category of consumer.

The implementation of a rural water and sanitation scheme involves the negotiation in the initial stages with the local community representatives of what the community wants and how it will be provided and operated. This may have to be preceded by a period of empowerment so that the negotiations can be conducted by informed people. At the conclusion of the negotiations a business plan can be prepared that should be implemented in association with the community. The project is at this stage mainly in the control of a professional engineer, responsible for the technical interpretation of the business plan and the management of the construction phase. Finally, after commissioning, a water service provider will be responsible for the operation, management and maintenance of the scheme on a sustainable basis.

The key actions and activities are identified and performance criteria defined. As communication at the beginning of the project is a critical component, the success of this is confirmed by examination and discussion as to how much has in fact been communicated and understood correctly. Other performance indicators for the operational phase are derived from the conventional ones used in the developed world. Finally, it is important that the participants, do not see the measurement of performance as a threatening situation, but rather a stepping stone to improvement of not only performance, but also of subsequent reward.
Effect of EPS on biofilm structure and function as revealed by an individual-based model of biofilm growth
Authors: Kreft J.-U. , Wimpenny J. W.
Published: May 2018

We have simulated a nitrifying biofilm with one ammonia and one nitrite oxidising species in order to elucidate the effect of various extracellular polymeric substance (EPS) production scenarios on biofilm structure and function. The individual-based model (IbM) BacSim simulates diffusion of all substrates on a two-dimensional lattice. Each bacterium is individually simulated as a sphere of given size in a continuous, three-dimensional space. EPS production kinetics was described by a growth rate dependent and an independent term (Luedeking-Piret equation). The structure of the biofilm was dramatically influenced by EPS production or capsule formation. EPS production decreased growth of producers and stimulated growth of non-producers because of the energy cost involved. For the same reason, EPS accumulation can fall as its rate of production increases. The patchiness and roughness of the biofilm decreased and the porosity increased due to EPS production. EPS density was maximal in the middle of the vertical profile. Introduction of binding forces between like cells increased clustering.
Photocatalytic degradation of dye pollutants in the presence of acetone
Authors: Tsui S.-M. , Chu W.
Published: May 2018

The photodegradation of textile azo dyes in aqueous solution containing acetone (ACE) photosensitizer was investigated at 253.7 nm. In this study, a typical azo reactive dye (C I Reactive Red 2 - RR2) is used as the probe compound. ACE is a powerful photosensitizer that possesses high triplet energy, and the presence of ACE significantly enhances the overall photodegradation reaction through simultaneous sensitization. In the UV/ACE system, at the optimum conditions, over 97% of RR2 can be successfully decomposed and decolored within 300 seconds of retention time. The photodegradation mechanisms of RR2 involve both photodechlorination and photoreduction, which follow pseudo first-order decay kinetics. The quantum yield of the photolysis system has been evaluated as a function of ACE concentration and the initial pH. RR2 contains the chlorotriazinyl group, which undergoes hydrolysis and results in the formation of hydrochloric acid, indicating that the photodechlorination process is the dominant reaction mechanism. The photo-product, H+, is likely to retard the quantum yield of dye decay, suggesting that the initial pH is a critical factor in changing the photodecolorization rates of dye. Generally, this system is more favorable at higher pH levels.
Enhancement of nitrifying biofilm formation using selected EPS produced by heterotrophic bacteria
Authors: Tsuneda S. , Park S. , Hayashi H. , Jung J. , Hirata A.
Published: May 2018

The possibility of enhancing nitrifying biofilm formation rate with the aid of selected EPS produced by heterotrophic bacteria was investigated. When EPS production characteristics were examined for four kinds of heterotrophs isolated from a domestic wastewater treatment reactor, two strains obtained from biofilms (B1, B2) exhibited a higher polysaccharide production rate than those from suspended flocs (A1, A2). Among EPS components, the concentration of uronic acids gave a good correlation with flocculation ability, which suggests that acidic polysaccharides play a major role in bioaggregate formation. Addition of 1g/L D-glucuronic acid as an EPS substitute enhanced the homocoagulation rate of autotrophic Nitrosomonas europaea and altered its zeta potential from ñ30.4mV to +4.3mV, which indicates a possibility that particular EPS components produced by heterotrophs are utilized as neutralising reagents for nitrifying biofilm formation. Moreover, when heterotrophic isolates with Nitrobacter winogradskyi were cultured in batch with fabric supports, biofilm formed on the substratum. These experimental results suggest the application of selected EPS for enhancing nitrifying biofilm formation.
Computer modeling of fecal coliform contamination of an urban estuarine system
Authors: Scaratos P. D.
Published: May 2018

This study is focused on the investigation of the sources, distribution and fate of fecal coliform populations in the North Fork of the New River that flows through the City of Fort Lauderdale, Florida, USA. The dynamics of this brackish river are driven by weak tides, regulated freshwater discharges, overland runoff, storm water drainage from sewers, and groundwater exchange. Extensive field studies failed to document any alleged source(s) of contamination, including birds, domesticated and undomesticated mammals, humans, septic tank leakage, urban runoff, non-point discharges from agricultural lands, waste disposal from live-aboard vessels and/or in situ re-growth of fecal coliform. In order to facilitate field sampling, and support the data analyses efforts, computer simulations were applied to assess the likelihood of the various possible pollution scenarios. The physically based computer model used is the WASP (Water Quality Analysis Simulation Program Modeling System) of the US Environmental Protection Agency. In addition, the Neural Network MATLAB Toolbox was utilized for data analysis. WASP was able to accurately simulate the water hydrodynamics and coliform concentrations within the North Fork, while the neural network assisted in identifying correlations between fecal coliform and the various parameters involved. The numerical results supported the conclusion that fecal coliform were introduced by the animal populations along the riverbanks and by storm water washout of the adjacent drainage basins and the banks. The problem is exaggerated due to the low flashing capacity of the river.
Study of the distribution of non-point source pollution in the watershed of the Miyun Reservoir, Beijing, China
Authors: Wang X. , Li T. , Xu Q. , He W.
Published: May 2018

Nitrogen and phosphorus are major nutrients to cause eutrophication to degrade the water quality of the Miyun Reservoir, a very important drinking water source of Beijing in China. These are mainly from non-point sources. The watershed in Miyun County is selected as the study region with a total area of 1400 km2. Four typical monitoring catchments and two experimental units were used to monitor the precipitation, runoff, sediment yield and pollutant loading related to various land uses in the meantime. The results show that the total nutrient loss amount of TN and TP is 898.07 t/a, and 40.70 t/a, respectively, in which nutrient N and P carried by runoff is 91.3% and 77.3%, respectively. There is relatively heavier soil erosion at the northern mountain area whereas the main nutrient loss occurs near the northeast rim of the reservoir. Different land uses influence the loss of non-point source pollutants. The amount of nutrient loss from agricultural land per unit is the highest, nutrient loss from forestry is the second highest and that from grassland is the lowest. However, due to the variability of land use areas, agricultural land contributes the greatest amount of TP and forestry lands the greatest amount of TN.
Automated monitoring of activated sludge in a pilot plant using image analysis
Authors: da Motta M. , Pons M. N. , Roche N.
Published: May 2018

An automated procedure for the characterisation by image analysis of the morphology of activated sludge has been used to monitor the biomass in a pilot wastewater treatment plant, in complement to the usual settleability (sludge volume index, settling velocity) and size distribution (by laser granulometry) measurements.
Runoff characteristics of major ionic species during rain events in forested watershed
Authors: Komai A. Y. , Umemoto S. , Inoue T.
Published: May 2018

The runoff characteristics of major ionic species from a stream in a forested watershed were investigated during two rain events. The values of EC and the concentrations of alkalinity, anions and cations, except for NO3−, decreased according to the increase of discharge, and showed a sharp lower peak. On the other hand, the concentrations of NO3− and K+ indicated an opposite change. The amount of output of anions and cations was also larger than those of the input, especially in a storm event. During a storm event, the NO3− concentrations in soil water 20 cm deep taken by a tension lysimeter were not detected, even though the surface soil of 0-5 cm deep included 20 to 50 mg/kg of NO3−. The direct contribution for NO3− concentrations by suspended solids in water was estimated through three percentages of the stream water output. Surface runoff was also not observed. These results suggest that the prompt subsurface runoff of the direct runoff from surface layer of soil may be predominant during rainfall in the forested area, and the increase of NO3− concentrations in the stream may be caused through the process.
Assessment of best management practices for improvement of dissolved oxygen in Chesapeake Bay estuary
Authors: Wang P. , Batiuk R. , Linker L. , Shenk G.
Published: May 2018

Two management scenarios, the base case and the full voluntary program implementation scenarios, are simulated with the three-dimensional Chesapeake Bay estuary model package to study the improvement of dissolved oxygen (DO) over the bay in response to the reduction of nutrient loads. The base case scenario is based on the 1985 nutrient management practices and the associated loads from the watershed and airshed to the bay. The full voluntary program implementation scenario is based on an expanded non-point source and point source program applying current technologies in nutrient and sediment management. The implementation of best management practices is assumed to be by voluntary participation, encouraged by a maximum 75% cost share by the states. The ten-year average (1985-1994) total nitrogen and total phosphorus loads to the bay are reduced 40% and 47%, respectively, from the base case to the full voluntary program implementation scenario. The average annual anoxia and hypoxia volume day is reduced 62% and 42%, respectively, in the whole bay. Daily development of bottom DO in the estuary is observed from an MPEG movie. Graphics of daily DO concentration and depth profile show a significant improvement in DO under improved nutrient control.
Modeling pesticide losses from diffuse sources in Germany
Authors: Bach M. , Huber A. , Frede H. G.
Published: May 2018

A GIS-based model estimates the losses from diffuse sources in surface waters in Germany for 42 active ingredients applied to 11 field crops, vineyards and orchards. For the following pathways of entry: tile drainage, runoff and spray drift, the calculated mean pesticide input amounts to 1490 kg/year, 9060 kg/year and 3350 kg/year, respectively, in 1994. The model results are highly sensitive to the model parameters, primarily the chemical properties of the active ingredients. The modeled water inputs were compared with measured pesticide loads in smaller catchments and large river basins to validate model results. Both datasets agree as to the order of magnitude, nevertheless due to the scale of the study the results should be addressed mainly to comparative interpretations with the focus on the proportions between different active ingredients, soil regions, climates and application periods.
An overview of the posters presented at Watermatex 2000. I. New models/integrated urban wastewater systems/time series analysis
Authors: De Clercq B. , Meirlaen J. , Verdonck F. , Vanrolleghem P. A.
Published: May 2018

This paper presents an overview of the posters presented in the sessions 1, 6 and 9 of the Watermatex 2000 conference. The first session focused on the development of new models in different areas of environmental technology, e.g. wastewater, ground pollution, sewers, etc. The sixth session dealt with integrated urban wastewater systems. Session 9 focused on the application of neural network modeling and principal component analysis in time series analysis. Rewarded posters are mentioned and selected for full paper publication in this issue of Wat. Sci. Tech.
An overview of the posters presented at Watermatex 2000. II. Sensor/monitoring, control and decision support systems
Authors: Volcke E. I. , Clement L. , Van De Steene M. , Vanrolleghem P. A.
Published: May 2018

This paper gives an overview of the poster sessions on sensor/monitoring, control and decision support systems, as they have been presented during the Watermatex 2000 conference. The COST benchmark for the comparison of different control strategies has been analysed. Two different teams have performed research on the control of sewers to decrease combined sewer overflows. Extended methods for gauge monitoring accuracy are proposed. The use of adaptive controllers for improving control performance under varying process conditions is demonstrated in two applications. More advanced techniques for monitoring and control are also discussed. Applications are situated in the field of fault detection and control. Three posters on decision support systems have presented the methodology and architecture of specific applications. Rewarded posters are mentioned and have been selected for full paper publication in this issue of Wat. Sci. Tech.
High-rate dissolved air flotation for water treatment
Authors: Raeli M. A. P. , Marchetto M.
Published: May 2018

This paper presents the results of an experimental investigation about the performance of a horizontal flow high-rate pilot scale Dissolved Air Flotation (HRDAF) unit containing inclined parallel plates for treating a coloured and low turbidity raw water. Experiments were performed with the DAF unit in order to verify the influence on flotation of : (i) the water velocity (Vh) between the plates, in the range 18 to 96.5 cm.min−1 with corresponding Reynolds numbers between 240 and 1060; (ii) the supplied air (S*) value ranging from 2.2 to 8.5 g of air/m3 of water ; (iii) the angle of the plates (60° or 70°). The best pilot plant operational condition was obtained applying only 4.0 g/m3 (S*) with Vh around 18 cm.min−1 for treatment of water coagulated with a Al2(SO4)3 dosage of 40 mg.l−1. In these conditions, the unit presented very good removal efficiencies of colour (90%, residual of 10 uC), turbidity (88%, residual of 0.8 NTU ) and TSS (94%, residual of 1.8 mg.l−1). Furthermore, the unit could operate at higher Vh values up to 76 cm.min−1 and still present good results. The DAF unit thus behaved as a high rate unit presenting good performance with low air requirement.
New developments in reactor and process technology for sulfate reduction
Authors: Hulshoff L.W. , Lens P.N.L. , Weijma J. , Stams A.J.M.
Published: May 2018

Sulfate reduction has been regarded in the past as an unwanted process in anaerobic treatment of sulfate-rich wastewaters. Research efforts were primarily focused on H2S toxicity, competition between sulfidogenic and methanogenic microorganisms and suppression of sulfidogenesis. More recently, the potential sulfidogenesis for treating a wide range of wastestreams contaminated with oxidized sulfurous compounds and/or heavy metals was also appreciated. Heavy metals can be removed by the formation and subsequent precipitation of poorly soluble metal sulfides. Basically two approaches can be distinguished in wastewater treatment: passive treatment using low-cost technologies and active treatment in newly developed bioreactors. Both strategies are discussed.
Solid waste digestors: process performance and practice for municipal solid waste digestion
Authors: Lissens G. , Vandevivere P. , De Baere L. , Biey E.M. , Verstraete W.
Published: May 2018

The most common types of anaerobic digesters for solid wastes have been compared based on biological and technical performance and reliability. Batch systems have the most simple designs and are the least expensive solid waste digesters. They have high potential for application in developing countries. Two-stage systems are the most complex and most expensive systems. Their greatest advantage lies in the equalisation of the organic loading rate in the first stage, allowing a more constant feeding rate of the methanogenic second stage. Two-stage systems with biomass accumulation devices in the second stage display a larger resistance toward toxicants and inhibiting substances such as ammonia. However, the large majority of industrial applications use one-stage systems and these are evenly split between ‘dry’ systems (wastes are digested as received) and ‘wet’ systems (wastes are slurried to about 12% total solids). Regarding biological performance, this study compares the different digester systems in terms of organic loading rates and biogas yields considering differences in input waste composition. As a whole, ‘dry’ designs have proven reliable due to their higher biomass concentration, controlled feeding and spatial niches. Moreover, from a technical viewpoint the ‘dry’ systems are more robust and flexible than ‘wet’ systems.
Potential of anaerobic digestion of complex waste(water)
Authors: Zeeman G. , Sanders W.
Published: May 2018

Although they differ greatly in origin complex waste(water)s mainly consist of proteins, lipids, carbohydrates and sometimes lignin in addition. Hydrolysis is the first and generally rate-limiting step in the process of anaerobic digestion of particulate organic substrates. Hydrolysis of particulate polymers can be described by Surface Based Kinetics, but for use in practice the empirical first order relation is advised. Unlike the hydrolysis of protein and carbohydrate, lipid hydrolysis is hardly occurring in the absence of methanogenesis. The latter is probably a physical rather than a biological process and affects the choice for either a one- or a two-step (phase) anaerobic reactor. In the chain of collection and transport, complex wastes often become complex wastewaters simply because of dilution. Dilution not only changes the reactor technology to be applied but also complicates the post-treatment and possibilities for resource recovery. Combining concentrated with diluted waste streams will almost always end up in much more complicated treatment technologies.
Anaerobic treatment: a key technology for a sustainable management of wastes in Europe
Authors: Lema J.M. , Omil F.
Published: May 2018

Environmental regulations in the European Union, based on the concept of integrated prevention and control of pollution, are oriented towards the sustainability of the production processes, and this leads to better recovery of resources from raw materials, energy saving, etc. This philosophy introduces a new framework to Environmental Engineers, who have to make efforts concerning waste minimisation. During the last few decades technologies based on the anaerobic treatment of wastewaters and organic wastes have been applied successfully to a wide variety of problems. A case study on the impact of applying anaerobic technology to the treatment of wastewaters from the sugar industry in Spain is presented. Nowadays, processes based on anaerobic treatment appear to be an excellent option as the core of an integrated process for waste and wastewater treatment.
The development of anaerobic treatment and its future
Authors: McCarty P.L.
Published: May 2018

Anaerobic treatment is well over 100 years old. Its initial development was for the treatment of domestic wastewaters, using anaerobic filters and hybrid processes that are still of interest today. It then progressed in application to separate sludge digestion, then to treatment of dilute industrial wastewaters. Several processes have been developed that accomplish efficient treatment of wastewaters at short detention times. Major contributions to the broad application of anaerobic treatment and the better understanding of this process has come from efforts by G. Lettinga and his colleagues. They have emphasized its importance for meeting the need for sustainable development in the future. Greater efforts are now needed for broad application of anaerobic treatment for ridding the environment of unwanted organic materials by converting them into methane, a renewable energy source.
Modelling the global efficiency of dissolved air flotation
Authors: Leppinen D. M. , Dalziel S. B. , Linden P. F.
Published: May 2018

The purpose of this paper is to examine how the efficiency of dissolved air flotation is affected by the size of bubbles and particles. The rise speed of bubble/particle agglomerates is modelled as a function of bubble and particle size, while the kinematics of the bubble attachment process is modelled using the population balance approach adopted by Matsui, Fukushi and Tambo. It is found that flotation, in general, is enhanced by the use of larger particles and larger bubbles. In particular, it is concluded that for the ultra-high surface loading rates of 25 m/hr or more planned for future flotation tanks, bubble size will have to be increased by a factor of two over the size currently employed in many facilities during dissolved air flotation.
The flow structure in the separation zone of a DAF pilot plant and the relation with bubble concentration
Authors: Lundh M. , Jönsson L. , Dahlquist J.
Published: May 2018

Fluid dynamics is believed to be of crucial importance for the removal mechanism in Dissolved Air Flotation. The paper is a presentation of experimental studies on velocity and air-content profiles in a DAF pilot plant. The correlation between air content and flow patterns is discussed. Two flow structures are detected. A stratified flow structure is defined by a horizontal transport of the water in a upper, less-dense layer, and a lower, downwards-vertical transport in the lower, dense layer. Between the layers a return flow is found. The short-circuiting flow is defined as an immediate downward deviation towards the outlet arrangement at the bottom of the tank, probably causing decreasing effluent quality. Density gradients, caused by differences in air content in the tank, are believed to generate a stratification of the water body, thus causing the water to be transported in layers. Measurements of air-content profiles correlate to the measured flow structures, also indicating a separation ofthe water body in two layers with a distinct boundary.
What are the areas for further research?
Authors: Jiang J.
Published: May 2018

The introduction of a national standard on odour measurement presents a new challenge for Australian olfactometry laboratories to meet tough new instrumental performance and panellist performance criteria. It also raises issues for end users of olfactometry results. For examples regulatory authorities may need to review the current status of odour regulations and guidelines. The paper reviews major issues pertaining to four components in odour impact assessment: measurement of odour, sampling techniques, air dispersion modelling, and the development of assessment criteria. The paper identifies and discusses the resolution of issues that could have a significant effect on the outcomes of odour impact assessment. It is hoped that the paper will provide a useful guide for industry and environmental protection authorities in the further development of an odour impact assessment procedure.
Recent odour regulation developments in Flanders: ambient odour quality standards based on dose-response relationships
Authors: Van Broeck G. , Van Langenhove H. , Nieuwejaers B.
Published: May 2018

Until now there has been little uniformity in the approach of odour nuisance problems in Flanders. A switch to a standardised and scientifically underpinned approach is essential and is currently in full development. This paper mainly discusses the results of five year research on odour concentration standard developments in Flanders, executed in the period 1996-2000. The research was focused on five pilot sectors: pig farms, slaughterhouses, paint spray installations, sewage treatment plants and textile plants. The general approach of the method to determine the dose-response relation was found to be sufficient. The methodology used is fully described in the paper presented by Van Broeck and Van Langenhove at the CIWEM and IAWQ Joint International Conference on Control and Prevention of Odours in the Water Industry in September 1999. For each location (16 locations in total) an unambiguous dose-response relation could be derived (rising nuisance for rising concentrations). In most cases, a “no effect” level could be determined. The background percentage nuisance fluctuated between 0 and 15%. For the sectors of the slaughterhouses, paint spray installations and sewage treatment plants a no effect level was 0.5, 2.0 and 0.5 sniffing units m−3 as 98th percentile (sniffing units are odour concentrations measured by means of sniffing measurements on the field) was determined. For the sectors of the textile plants and pig farms, no unambiguous no effect level was found. Currently research is undertaken to translate the no effect levels to odour standards. Other initiatives, taken to underpin the Flemish odour regulations, such as the development of an odour source inventory and a complaint handling system, are also briefly discussed.
Development of odour assessment criteria in New South Wales and application of the criteria for the assessment of a major public works project
Authors: Kaye R.
Published: May 2018

The introduction of the forthcoming Australian and New Zealand standard on odour measurement has led to the review of odour regulation in most Australian states. In New South Wales the regulator has drafted an odour impact assessment policy for point source emissions. The policy is based on the new odour measurement standard and defines regulatory dispersion modelling procedures. The New South Wales odour assessment policy was initially drafted on the basis of a literature review and has since been developed in consultation with various industry and government groups, including sewerage authorities. The policy, while still officially regarded as a draft, has already been used as the basis for the assessment of a number of sewerage projects that have been characterised by point source emissions. The application of modelling-based assessment procedures requires careful judgement concerning the selection of input data and close scrutiny on behalf of the assessor. This paper examines the assumptions underlying the development of the New South Wales draft odour assessment policy and draws important universal lessons from its application for the assessment of a major sewerage project. The introduction of peak to mean factors based on one second nose response times has been controversial and alternative procedures are proposed.
Prospects, problems and pitfalls of urban water reuse: a case study
Authors: Hermanowicz S. W. , Sanchez Diaz E. , Coe J.
Published: May 2018

This paper presents a successful water reclamation and reuse project in the San Francisco Bay area. The project, which includes a water reclamation facility and a separate distribution system, is operated by a wastewater utility and reclaims approximately 4% of its dry-weather flow. Project history, its design and implementation are further discussed. Planning, and especially demand analysis, was critical for project development. Earlier attempts of water reuse were not successful because reclaimed water quality did not match the requirements of potential large industrial customers. Current customers are a mix of public, commercial and residential users who apply the reclaimed water solely for landscape irrigation. In addition, a large fraction of the reclaimed water is used internally in the main wastewater treatment plant. Early connection of largest customers, innovative collaboration with a neighboring reclamation project and cooperation of the local water supplier were very important for project success. Distribution of internal process water consumes most energy. The second major energy use is for the treatment of reclaimed water while distribution of reclaimed water to external customers requires least energy.
Analysis of sludge management parameters resulting from the use of domestic garbage disposers
Authors: Galil N. I. , Yaacov L.
Published: May 2018

The use of domestic garbage disposers may reduce the amounts and improve the solid waste composition, by lowering putrid matter and water content and by raising the caloric potential. However, additional loading on the sewerage systems might require increased investments and operation costs of the wastewater treatment facilities. This project analyses additional amounts of solids, biosolids and process requirements connected with wastewater treatment facilities resulting from the domestic use of garbage disposers, as well as the additional production of biogas. It was found that the use of the domestic garbage disposers in 60% of the households in a given urban area, is expected to reduce the weight, volume and water content of the solid waste by 7.0%, 3.3% and 4.4% for garbage characterized by low organic content, and by 18.7%, 11.0% and 13.3% for high organic content, respectively. The additional amounts of sludge are expected to be the lowest in case of biological treatment only, 24 to 38 g/capita/day, and the highest in case of primary chemical sedimentation followed by biotreatment, 67 to 100 g/capita/day. In these conditions the energy potential from biogas obtained in anaerobic digestion of sludge from wastewater collected from the same area, will increase by 50% to 70%, depending on the wastewater treatment sequence. The investment in wastewater treatment is estimated to increase by 23% to 27% and the annual costs for operation and maintenance are expected to increase by 26% to 30%.
Growth of faecal coliforms and Salmonella spp. in physicochemical sludge treated with acetic acid
Authors: Barrios J.A. , Jiménez B. , Salgado S. , Garibay A. , Castrejon A.
Published: May 2018

The use of advanced primary treatment (APT) to remove helminth ova from wastewater has raised the issue of treating the generated sludge to allow its reuse or disposal. Several studies have been performed in Mexico in order to treat the sludge with the main goal of destroying helminth ova and bacteria, one of them analysing the acid treatment. Previous research has demonstrated the feasibility of applying such a process using acetic acid to disinfect the sludge, but the potential for bacterial growth was still to be proved. The results of a growth study of faecal coliforms and Salmonella spp. in sludge treated with acetic acid are presented in this paper. Physicochemical sludge generated in a semi-rural area of Mexico City was treated using acetic acid in 6 different doses ranging from 3,700 to 22,000 ppm (w/w) and the concentrations of faecal coliforms, Salmonella spp., and total and volatile solids, were monitored after 30 minutes, and 8, 21 and 35 days. Average initial concentrations in sludge were 1.1×108 MPN/g TS and 1.5×105 MPN/g TS for faecal coliforms and Salmonella spp., while pH, total and volatile solids were 5.4, 5.0% and 73% respectively. Apparently, some acidified samples presented anaerobic activity, observed as a change in sludge coloration, as well as bacterial growth. pH of the treated samples with less than 18,400 ppm raised from the initial value of approximately 4.0 up to 5.9 units, while samples with 18,400 and 22,000 ppm maintained the pH close to 4. Total and volatile solids did not present important changes except in the untreated sample where they were reduced by 0.3 and 3.4% respectively. Samples treated with more than 14,700 ppm of acetic acid did not present any increase in bacterial density. Additionally, concentrations of faecal coliforms and Salmonella spp. in untreated sludge were reduced throughout the time, in contrast to samples treated with doses lower than 14,700 ppm that showed some growth, which suggests that the use of acetic acid in doses lower than 15,000 ppm stimulates in some way the growth of these bacteria.
Reuse of reclaimed wastewater for golf course irrigation in Tunisia
Authors: Bahri A. , Basset C. , Queslati F. , Brissaud F.
Published: May 2018

In Tunisia, golf courses are irrigated with secondary treated effluent stored in landscape impoundments. The impact of the conveyance and storage steps on the physical-chemical and biological quality of irrigation water was evaluated on three golf courses over two years. It was found that the water quality varies all along the water route, from the wastewater treatment plant up to the irrigation site: nutrient and bacteria contents decreased along the route in the three cases. This variation depends on the wastewater quality, the length of the pipes conveying water, the number of regulation reservoirs and ponds, the water residence time in pipes, reservoirs and ponds, and the operation of the ponds. The bacteriological quality of irrigation water deteriorates during the irrigation period in the three golf courses as the ponds are operated as continuous flow reactors. The results obtained in this study indicate the inability of golf water supplies, as currently managed, to properly sanitize reclaimed wastewater and meet target quality criteria recommended by WHO (1989) for water intended for recreational use. For a safe reuse of reclaimed wastewater for golf course irrigation, changes in the design and operation of the ponds should be planned or additional treatment steps provided.
Extracellular polymers of ozonized waste activated sludge
Authors: Liu J.C. , Lee C.H. , Lai J.Y. , Wang K.C. , Hsu Y.C. , Chang B.V.
Published: May 2018

Effect of ozonation on characteristics of waste activated sludge was investigated in the current study. Concentrations of cell-bound extracellular polymers (washed ECPs) did not change much upon ozonation, whereas the sum of cell-bound and soluble extracellular polymers (unwashed ECPs) increased with increasing ozone dose. Washed ECPs in original sludge as divided by molecular weight distribution was 39% < 1,000 Da (low MW), 30% from 1,000 to 10,000 Da (medium MW), and 31% > 10,000 Da (high MW). It was observed that the low-MW fraction decreased, and the high-MW fraction increased in ozonized sludge. The unwashed ECPs were characterized as 44% in low MW, 30% in medium MW, and 26% in high MW. Both low-MW and medium-MW fractions of unwashed ECPs decreased while high-MW fraction increased in ozonized sludge. The dewaterability of ozonized sludge, assessed by capillary suction time (CST) and specific resistance to filtration (SRF), deteriorated with ozone dose. The optimal dose of cationic polyelectrolyte increased with increasing ozone dose. The production rate and the accumulated amount of methane gas of ozonized sludge were also higher.
Effect of aggregate size and structure on specific resistance of biosolids filter cakes
Authors: Guan J. , Amal R. , Waite T.D.
Published: May 2018

Investigation of the specific resistance to filtration of biosolids modified by cationic polymer addition reveals a dependence on both size and structure of the resulting biosolids flocs. This dependence is reasonably described by a modified form of the Carman-Kozeny equation and reveals that effects of differences in floc structure on cake resistance are most marked for flocs of small size. Conversely, effects of differences in floc size are most significant when flocs are more compact.
Pilot scale nanofiltration membrane separation for waste management in textile industry
Authors: Koyuncu I. , Kural E. , Topacik D.
Published: May 2018

This paper presents the pilot scale membrane separation studies on dyehouse effluents of textile industry. Nanofiltration (NF) membranes which have 2 m2 of surface area were evaluated for membrane fouling on permeate flux and their suitability in separating COD, color and conductivity in relation to operating pressure and feed concentration from textile industry dyehouse effluents. Successive batch runs demonstrated that any serious membrane fouling was not experienced for NF membrane tested in treating this type of wastewater. The permeate flux was found to increase significantly with operating pressure. Flux decreased with increasing recovery rate. The overall removal efficiencies of COD, color and conductivity were found as greater than 97%. COD was lower than 10 mg/l at 12 bar pressures. Permeate COD was also increased with increasing recovery and COD was 30 mg/l with recovery of 80%. Almost complete color removal was achieved with nanofiltration membrane. Color value was also decreased from 500 Pt-Co to 10 Pt-Co unit. This significant reduction in color and COD makes possible the recycle of the permeate in the dyehouse. Permeate conductivity was decreasing with increasing pressure and retention of conductivity increases with increasing pressures. This phenomenon is expected from the analysis of conductivity mass transport model. Economical analysis have been done and the total estimated cost will be 0.81 $/m3 based on 1000 m3/day of and this value is very economical for Istanbul City due to increasing industrial water supply tariffs.
Water quality assessment for indirect potable reuse: a new methodology for controlling trace organic compounds at the West Basin Water Recycling Plant (California, USA)
Authors: Levine B. , Reich K. , Sheilds P. , Suffet I. H. , Lazarova V.
Published: May 2018

The West Basin Water Recycling plant (California; USA) was built to increase the region's water resource availability. The plant influent is produced at Los Angeles Hyperion wastewater treatment plant and is treated through two parallel treatment processes depending on the end use : (1) Title 22 water for industrial and urban use, and (2) barrier treatment for groundwater recharge. A new methodology was applied to monitor the fate of base neutral compounds in the water barrier treatment train. The methodology included large sample volumes coupled with integrated chromatographic analysis (ICA). Data indicated a 25% increase in concentration of base neutral compounds after RO pretreatment, followed by a 70% removal efficiency after RO. The increase in concentration after RO pretreatment appears to be linked to the use of lime clarification.
Effect of charge neutralization on the dewatering performance of alum sludge by polymer conditioning
Authors: Wu C.C. , Wu J.J.
Published: May 2018

Cationic and anionic polymers with the same molecular weight were used as sludge conditioning reagent to study the polymer charge effect on alum sludge dewatering characteristics. On the basis of capillary suction time, bound water content, and zeta-potential measurement in this study, the function of charge neutralization appears to be an important consideration in the sludge dewaterability and moisture content. Using the dilatometric technique to measure the bound water content, we found that alum sludge conditioned by cationic polymer presented more significant variation in the bound water content than sludge subject to anionic conditioning. We hypothesise that the mechanism of charge neutralization caused much water depletion by replacement and exclusion in sludge and results in the decrease of bound water within the cationic polymer conditioning. An insignificant bound water variation found during the anionic conditioning resulted from the lack of charge neutralization. A lighter and looser floc structure is also be found in the anionic conditioned sludge after the analysis of wet floc density and fractal dimension. Such open floc structure can be attributed to the lack of charge neutralization as the flocs aggregate with anionic polymer.
The filter system for tertiary treatment of sewage effluent by land application - its performance in a subtropical environment
Authors: Gardner E. A. , Morton D. , Sands J. , Matthews P. , Cook F. J. , Jayawardane N. S.
Published: May 2018

FILTER is an innovative, CSIRO developed system for treating effluent using high rate land application and subsequent effluent recapture via a closely spaced, subsurface drainage network. We report on the summer performance of a FILTER system established in a subtropical environment on a relatively impermeable swelling clay soil underlain by a deep regional water table. Using secondary treated sewage effluent, the FILTER system produced effluent of tertiary nutrient standards (≤5 mg/L TN; ≤1 mg/L TP), with salinity levels suitable for subsequent irrigation reuse (EC ≤2.5 dS/m). Removal of faecal coliforms was considerably less effective. The hydraulic loading rate achieved was about two and a half times larger than conventional irrigation demand, but this was associated with high deep percolation losses (c 3 mm/day). Comparisons are made with the original FILTER system developed and tested by Jayawardane et al. in temperate Australia. Suggestions are made for modifications to, and further testing of FILTER in a subtropical environment.