bluuebunny/crossref_metadata_2025 huggingface dataset:
Preserving the (water) harvest: effective water use in agriculture
Authors: Kijne Jacob W.
Published: May 2018

The alternative to increasing the world's irrigated area by an estimated 30% to secure food security for all, seems to be limited irrigation expansion and consequently higher food prices and probably food shortages. This paper explores other options for ensuring food security. It discusses meaningful similarities between innovative approaches for land and water management in rainfed and irrigated agriculture. The focus is on innovative approaches to increase yields in sub-Saharan Africa and South Asia.

Innovative technologies, such as improved tillage practices and water harvesting are important. But at least as important are the processes by which new agricultural practices are developed, improved and extended. In the end it comes down to human inventiveness.
Hybrid reactor performance in pentachlorophenol (pcp) removal by anaerobic granules
Authors: De Almeida Prado Montenegro M. , De Mattos Moraes E. , Moreira Soares H. , Filomena Vazoller R.
Published: May 2018

The present research aimed at evaluating pentachlorophenol (PCP) degradation in a hybrid reactor supplied with a mixture of fatty acids (propionic, butyric, acetic and lactic) and methanol. The performance of the reactor is remarkably stable and efficient during PCP additions at range of 2.0 to 21.0 mg/L. The reduction of chemical oxygen demand (COD) was around 97% and methane was found to be 86% in the biogas production. The efficiency of volatile fatty acids breakdown was 93%, 64% and 74% respectively for butyric, propionic and acetic. PCP total removal of more than 99% was reached by granular sludge activities formed during 21 months of reactor operation. Methanogenic microorganisms predominance was noticed with 105 to 106 cells/mL during enumeration on methanol or lactate added to sulfate culture media. The removal rate was 1.07 mg PCP · g−1 VS · d−1 during the highest PCP concentration addition.
Phenol degradation in horizontal-flow anaerobic immobilized biomass (HAIB) reactor under mesophilic conditions
Authors: Bolaños R. M.L. , Varesche M. B.A. , Zaiat M. , Foresti E.
Published: May 2018

A bench-scale horizontal-flow anaerobic immobilized biomass (HAIB) reactor was assayed aiming to verify its potential use for phenol degradation. The HAIB reactor consisted of a bore-silicate tube (100 cm long; 5.04 cm diameter) filled with polyurethane foam matrices containing immobilized anaerobic sludge. Before being subjected to phenol, the reactor was fed with synthetic substrate at the influent chemical oxygen demand (COD) of 1,028 mg.l−1 achieving 98% of COD removal efficiency. Thereafter, phenol as the sole carbon source was added under step-increasing concentrations from 50 to 1,200 mg.l−1. Phenol degradation was evaluated by gas chromatographic analysis of influent and effluent samples. Process monitoring included determinations of pH, volatile acids, alkalinity and COD. The HAIB reactor was operated at a constant hydraulic detention time (HDT) of 12 hours. After 33 days with 50 mg/l of phenol in the influent, the reactor achieved 98% of COD removal efficiency. Successful phenol degradation (efficiency removal of 99%) occurred for influent concentrations of 100, 300, 600, 900 and 1,200 mg.l−1 after 148, 58, 47, 29 and 7 days, respectively. The predominance of Methanosaeta-like, rods and methanogenic cocci could be observed in all the operating conditions, besides the presence of phenol oxidizing microorganisms as irregular rods. The results indicate that phenol degradation at very high rates can be accomplished in HAIB reactors containing acclimatized biomass.
Degradation of lineal alkylbenzene sulphonate (LAS) in an acidogenic reactor bioaugmented with a Pseudomonas aeruginosa (M113) strain
Authors: Almendariz F. J. , Meráz M. , Soberón G. , Monroy O.
Published: May 2018

The degradation of of lineal alkylbenzene sulphonate (LAS) was studied in a two-stage anaerobic system where the acidogenic reactor was bioaugmented with a strain of Pseudomonas aeruginosa (M113). This is a strain, which under aerobic and denitrifying conditions uses LAS as carbon source. Results show that LAS was only degraded within the acidogenic stage while in the methanogenic reactor there was no degradation and eventually there was an inhibition due to a LAS accumulation in the sludge. During the experiment, the M113 strain remained in the acidogenic conglomerate (at around 104 CFU/mL) although there is no evidence of their involvement in LAS degradation.
Influence of porosity and composition of supports on the methanogenic biofilm characteristics developed in a fixed bed anaerobic reactor
Authors: Picanço A. P. , Vallero M. V.G. , Gianotti E. P. , Zaiat M. , Blundi C. E.
Published: May 2018

This paper reports on the influence of the material porosity on the anaerobic biomass adhesion on four different inert matrices: polyurethane foam, PVC, refractory brick and special ceramic. The biofilm development was performed in a fixed-bed anaerobic reactor containing all the support materials and fed with a synthetic wastewater containing protein, lipids and carbohydrates. The data obtained from microscopic analysis and kinetic assays indicated that the material porosity has a crucial importance in the retention of the anaerobic biomass. The polyurethane foam particles and the special ceramic were found to present better retentive properties than the PVC and the refractory brick. The large specific surface area, directly related to material porosity, is fundamental to provide a large amount of attached biomass. However, different supports can provide specific conditions for the adherence of distinct microorganism types. The microbiological exams revealed a distinction in the support colonization. A predominance of methanogenic archaeas resembling Methanosaeta was observed both in the refractory brick and the special ceramic. Methanosarcina-like microorganisms were predominant in the PVC and the polyurethane foam matrices.
Summary and Conclusions from the SIWI Young Professionals Workshop Hydrosolidarity intergenerational challenges: long-term commitment for long-term issues
Authors: Kuylenstierna Johan , Rockström Johan
Published: May 2018

The year 2000 Young Professionals Seminar focused on long-term intergenerational challenges. Water related problems are symptoms of complex and ultimately societal problems linked to human behaviour, political support and managerial and institutional structures. Although integrated water resources management is presented as a solution, it is not always well understood, and can create a sense of hopelessness among professionals. To make it operational requires long-term commitments among various professionals and the involvement of new actors. A number of key topics crystallised as needing further attention, including ethical dimensions in policy making, the development of a framework for a 'Future Generation Impact Assessment' (FGIA), and efforts to achieve true dialogue among stakeholders. Young water professionals must become more involved in political processes and take active part in institutional changes. Such engagement will require changes in the working environment facing many young professionals that causes frustration due to inefficient and conservative hierarchical structures and the lack of transparency
Post-treatment of anaerobic effluents in constructed wetland systems
Authors: de Sousa J. T. , van Haandel A. C. , Guimarães A. A.V.
Published: May 2018

This papers describes the behaviour of wetlands as a post-treatment unit for anaerobically treated sewage for the removal of organic matter, suspended solids, nutrients (nitrogen and phosphorus) and faecal coliforms. Raw sewage was treated in a UASB reactor with a retention time of 5 h and the effluent was used in four units of wetlands with coarse sand as the medium and operated with different hydraulic loads. Three of the units had emerging macrophytes (Juncus sp), whereas the fourth one was operated as a control unit without plants.

During the 12 months of operation, the organic material removal efficiency (measured as COD) was in the range of 79 to 85%, whereas suspended solids removal varied from 48 to 71%. Faecal coliform removal was very high (99,99%); phosphorus was also efficiently removed (average efficiency of 90% for the lowest hydraulic load), but nitrogen removal was only partial (45 to 70% for ammonia and 47 to 70% for TKN). The experimental results clearly show the technical feasibility of using wetlands for treatment of municipal sewage after a pre-treatment in the UASB reactor.
Polishing ponds for post-treatment of digested sewage part 1: flow-through ponds
Authors: Cavalcanti P. F.F. , van Haandel A. , Lettinga Gatze
Published: May 2018

Polishing ponds are used to improve the quality of effluents from efficient anaerobic sewage treatment plants like UASB reactors, so that the final effluent quality becomes compatible with legal or desired standards. The residual organic material and suspended solids concentrations in the digested sewage are reduced, but often the main objective of polishing ponds is to improve the hygienic quality, measured by the concentration of two indicator organisms: helminth eggs and faecal coliforms (FC). The FC removal is normally the slowest process and for that reason becomes the main design criterion for a polishing pond. By contrast in conventional waste stabilisation pond (WSP) systems the organic material removal is the governing design parameter.

The feasibility of operating a single polishing pond for the post-treatment of UASB effluent is shown in this paper and the final effluent quality as a function of the retention time is discussed. Even under the most adverse weather conditions (several weeks of rain) the population of algae remained stable and produced enough oxygen to maintain a predominantly aerobic environment. The final effluent TSS and BOD concentrations were not very low for retention times of less than 1 week, but this could be attributed to the presence of algae in the final effluent. Filtered effluent BOD and TSS concentrations were very low. For retention times of more than 1 week algae were efficiently removed from the liquid phase by the action of predators and algae flocculation and settling, so that a final effluent with a very low BOD and TSS concentrations was produced.

To maximise the FC removal efficiency the polishing pond was constructed with the objective of approaching a plug flow regime. However, the observed efficiency was well below the expected value for all retention times, which was attributable to imperfections of the flow regime. From tracer studies it was established that the dispersion number was in the range of 0.14 to 0.16, which means that moderate mixing occurred, even though the pond was designed to avoid mixing as much as possible. Also the dead volume fraction ranging from 0.12 to 0.15 was quite considerable. Due to these imperfections the required retention time for an effluent to be used in unrestricted irrigation was produced for a retention time of about 10 days, twice the value of the minimum retention time for a batch or true plug flow pond. Although the plug flow regime could not be approached in practice, the required retention time of 10 days is still very much shorter than the value used in conventional WSPs (20 to 30 days).
Photocatalytical oxidation of de-icing agents in aqueous solutions and aqueous extract of jet fuel
Authors: M. Krichevskaya , T. Malygina , S. Preis , J. Kallas
Published: May 2018

Improper handling of jet fuel at abandoned military bases has resulted in heavy pollution of the soil and groundwater. Experimental research of photocatalytical oxidation (PCO) of jet fuel aqueous extract and aqueous solutions of de-icing agents was undertaken. The influence of different parameters - pH, concentration of substances to be oxidised, presence of inorganic admixtures, effect of OH• radical generators - on the PCO of solutions of de-icing agents and jet fuel aqueous extract was determined. The role of OH• radicals was found to be less important in determining the PCO rate. The PCO of organic pollutants was also investigated using a catalyst immobilised onto the surface of buoyant hollow glass micro-spheres. Attached titanium dioxide (TiO2) showed lower photocatalytical activity than when suspended in slurry, although it allows waters to be treated in simple shallow ponds without intensive stirring. The biodegradability of aqueous solutions of de-icing agents and jet fuel aqueous extract increased as PCO proceeded.
Effect of Fe(III)-ligand properties on effectiveness of modified photo-Fenton processes
Authors: Aplin R. , Feitz A.J. , Waite T.D.
Published: May 2018

This paper examines a modified photo-Fenton (UV/Fe oxalate/H2O2 process. The degradation of oxalate in this system in the absence of Reactive Red 235 was studied using both experimentation and kinetic modelling. The degradation of Reactive Red 235 in this system was also studied. Light intensity and solution pH had large effects on the degradation of both oxalate and Reactive Red 235, with the effect of pH not due simply to speciation changes. The most important properties of the oxalate ligand in the UV/Fe oxalate/H2O2 process are that it forms Fe(III)-oxalato complexes that are easily photolysed and also is relatively unreactive with OH• radicals.
Oxidation of nitrobenzene by O3/UV: the influence of H2O2 and Fe(III). Experiences in a pilot plant
Authors: Contreras S. , Rodríguez M. , Chamarro E. , Esplugas S. , Casado J.
Published: May 2018

The degradation of nitrobenzene using some advanced oxidation processes (O3/UV, O3/UV/H2O2 and O3/UV/Fe(III)) has been investigated. In the combined O3/UV process, the effect of pH and ozone was studied. In the other combinations, the influence of the amount of hydrogen peroxide and ferric ion in the degradation rate and TOC evolution, has been studied. Under our conditions, the combination O3/UV did not improve the degradation rate obtained by ozonation. The best TOC decrease was obtained when the O3/UV process was carried out at low ferric ion concentrations.
Radar based rainfall forecast for sewage systems control
Authors: Aspegren H. , Bailly C. , Mpé A. , Bazzurro N. , Morgavi A. , Prem E. , Jensen N. E.
Published: May 2018

There has been an increasing demand for accurate rainfall forecast in urban areas from the water industry. Current forecasting systems provided mainly by meteorological offices are based on large-scale prediction and are not well suited for this application. In order to devise a system especially designed for the dynamic management of a sewerage system the “RADAR” project was launched. The idea of this project was to provide a short-term small-scale prediction of rain based on radar images. The prediction methodology combines two methods. An extrapolation method based on a sophisticated cross correlation of images is optimised by a neural network technique. Three different application sites in Europe have been used to validate the system.
Treatment of dyehouse liquors in a biological sequencing batch reactor with recursive chemical oxidation
Authors: Krull R. , Hempel D.C.
Published: May 2018

A new developed sequencing batch process for the purification of residual water containing concentrated azo dye was investigated. Within a treatment cycle the biological anoxic decolorization, followed by an aerobic mineralization of organic metabolites in combination with the biodegradability-achieving partial oxidation with ozone are carried out sequentially. The split flow can be destructively purified to 90% with respect to the parameter DOC. It was decolorized to an extent of 98% and the toxicity measured by the bioluminescence test decreased up to 99%. With an unspecific facultative anaerobic bacterial mixed culture anoxic decolorization of the residual liquor (20 gdye/L) without addition of an external auxiliary substrate was observed. In the first phase of the treatment cycle, the azo dye-molecules are cleft at the azo bond by biochemical reduction which leads to the corresponding sulfonated aromatic amines. In the following aerobic phase the cleft products were mineralized by the same microorganisms in the same reactor. Because of the recalcitrant and respectively toxic character of a part of the remaining metabolites, further aerobic mineralization was initialized by partial oxidation with ozone. The recursive ozonization in a recircled stream with biological post-treatment of the transformed substances led to an increased reaction selectivity and lower consumption of ozone. The results have shown that the chosen sequencing batch reactor with the ozonization bypass is suitable for an effective treatment of high concentrated dyehouse liquors.
Simple mass balance approach for assessment of flood control sumps in an urban watershed: case study of heavy metal loading
Authors: Smith E. H. , Abumaizar R. J. , Halff A. H. , Skipwith W. E.
Published: May 2018

Levee sump systems are used by many riverine communities for temporary storage of urban wet weather flows. The complex hydraulics and transport of stormwater pollutants in sump systems, however, have not been systematically studied. The objective of this work is to present a case study, utilizing a relatively simple and low-cost methodology, for assessing the hydraulic performance of flood control sumps in an urban watershed. Two sumps of highly variable physical and hydraulic characteristics were selected for analysis. HEC-1 software was used to estimate the flow hydrograph for each outfall to a sump as part of the overall flow balance, resulting in a total runoff hydrograph for a precipitation event. To validate HEC-1 results, a water balance was used to estimate the total runoff using sump operational data. The results suggest that HEC-1 calculation provide a satisfactory estimate of the total runoff and its time-distribution to the sump. The hydraulic model was then used to estimate nonpoint loads of selected heavy metals to the sump and to the river. Although flow of stormwater through a sump system is regulated solely by flood-control requirements, these sumps may function as sedimentation basins that provide purification of stormwater. An example calculation of removal of heavy metals in a sump using a mass balance approach is presented.
The effects of particle size distribution on the settleability of CSOs pollutants
Authors: Shin E. B. , Yoon H. S. , Lee Y. D. , Pae Y. S. , Hong S. W. , Joo B. H.
Published: May 2018

Over the past decades, flocculation and/or sedimentation processes have been adopted to remove pollutants from CSOs. It has been learned that major factors affecting settlement of pollutants are the particle size distribution, their settling velocities and their specific gravity. It is, therefore, a good idea to analyze the particle size distribution and settleability of CSOs pollutants in order to develop details in designing a process. Discussed in this study are pollutant characteristics of CSOs such as particle size distribution and settleability of pollutants. The power law function is applied and is found to be an effective and reliable index for expressing the particle size distribution of pollutants in CSOs. Based on the particle size spectrum analysis, the tendency toward settling and simultaneous flocculation-settling phenomenon of CSOs pollutants is described. Based on the regression analysis it is observed that the derived constants of curves representing settling velocity profile are proportional to the initial concentration of particles and to the β-values of power law distributions. It is also revealed that the simultaneous flocculation-settling processes are effectively described by the changes of the average particle diameter and of the β-values of power law distributions.
Ozonation of 1,2-dihydroxybenzene in the presence of activated carbon
Authors: Zaror C. , Soto G. , Valdés H. , Mansilla H.
Published: May 2018

This work aims at obtaining experimental data on ozonation of 1,2-dihydroxybenzene (DHB) in the presence of activated carbon, with a view to assessing possible changes in its surface chemical structure and adsorption capacity. Experiments were conducted in a 0.5 L reactor, loaded with 2 g Filtrasorb 400 granular activated carbon, and 1-5 mM DHB aqueous solution at pH 2-8. Ozone gas was generated with an Ozocav generator, and fed into the reactor for a given exposure time, in the range 0.5-240 min, at 25°C and 1 atm. After each run, liquid and activated carbon samples were taken for chemical assays. Soluble organic groups present on the active carbon surface were desorbed and analysed by GC-MS and HPLC. Activated carbon chemical surface properties were analysed using TPD, FT-IR, and XPS techniques. Reactions between ozone and adsorbed DHB were shown to be fast, leading to formation of C-6, C-4 and C-2 by-products. Oxygenated surface groups, particularly, COOH and C = O, increased as a result of ozonation.
Water resources protection today: end-of-pipe technology and cleaner production. Case study of the Czech Odra River watershed
Authors: Chour V.
Published: May 2018

This paper reports on integrated watershed-based protection and sustainable use of water resources to increase the effectiveness of water pollution abatement. The approach includes improvements in end-of-pipe waste-water treatment technologies and implementation of Cleaner Production (CP) principles and policies within the watershed. An example of the general effectiveness of this approach is illustrated by the Czech Odra River Cleaner Production Project where reductions in pollution were achieved with improved industrial production. The CP theme is worth considering as an important challenge for the IWA.
Solar detoxification of wastewater in a novel aerated cascade photoreactor (ACP)
Authors: Xi W. , Geissen S.-U. , Vogelpohl A.
Published: May 2018

A newly developed aerated cascade photoreactor (ACP), based on a non-concentrating suspension photoreactor, combines the advantages of a cascade with the increased mass-transfer and the use of oxygen from air as an oxidizing agent in a bubble column. Systematic studies of the limiting hydrodynamic conditions in the ACP and the solid/liquid-separation of the photocatalyst from the treated wastewater have shown that the ACP is technically and commercially attractive. The ACP outperforms the thin-film fixed-bed reactor (TFFBR) with respect to a 3-13 times higher degradation efficiency for the model compound dichloroacetic acid (DCA). The treatment of two biologically pretreated real wastewaters, one from a textile factory and one from car-washing, have been successfully carried out under artificial light and sunlight.
Input pathways and river load of pesticides in Germany - a national scale modeling assessment
Authors: Bach M. , Huber A. , Frede H.-G.
Published: May 2018

A model has been developed which estimates the magnitude and the spatial distribution of pesticide losses from diffuse sources (surface run-off, tile drains and spraydrift) into surface waters for the entire area of Germany. The cumulative annual losses of 42 active ingredients applied to 11 field crops, orchards and vineyards are calculated for river basins in Germany based on grid maps with a resolution of 1 × 1 km2. The model validation showed a sufficient degree of accuracy of the model results compared to measured pesticide loads in 13 small catchments. According to the model results the pesticide input from diffuse sources into surface waters amounted to 13.8 t in 1994 aggregated for the entire area of Germany. Input via surface runoff contributed 9.1 t while tile drainage was 1.4 t and spraydrift 3.4 t respectively. Alongside the model calculations empirical data of the pesticide load of rivers in Germany are presented. A comparison of the measured river loads with the modeled inputs from non-point sources leads to the conclusion that in most regions of Germany the largest portion of the load is due to the input from farm effluents.
A water quality index for contact recreation in New Zealand
Authors: Nagels J. W. , Davies-Colley R. J. , Smith D. G.
Published: May 2018

We surveyed the opinions of 16 water quality experts in order to develop a water quality index for contact recreation in freshwaters in New Zealand. The index was developed by postal surveys using the Delphi method, involving feedback of information to the panel members at each iteration. Determinands selected for use in the index were as follows: faecal bacterial indicators (faecal coliforms or E. coli), pH, Munsell colour, visual clarity indicators (black disc visibility or turbidity), and nutrients promoting nuisance growths (filtered BOD5, and dissolved forms of phosphorus and nitrogen). “Sub-index” curves relating suitability-for-use to these water quality determinands have been developed. The mean (“consensus”) sub-index curves can be used to interpret water quality data in terms of suitability-for-use scores. We advocate using the lowest suitability-for-use score for a water as its overall index value for contact recreation. Thus the water body's suitability-for-use is determined by its “poorest”characteristic. The index is now ready to be tested by water managers for its utility in state-of-environment reporting.
Kinetics of decolorization and mineralization of the azo dye Reactive Black 5 by hydrogen peroxide and UV light
Authors: Mohey El-Dein A. , Libra J.A. , Weismann U.
Published: May 2018

C.I. Reactive Black 5 is one of the most used reactive dyes for textile finishing. It is a diazo dye, which can be decolorized by facultative anaerobic bacteria, sulfate reducing bacteria and aerobic white rot fungi. Mineralization by microorganisms has proven difficult. Advanced oxidation processes are promising alternatives for the decolorization and mineralization of Reactive Black 5, alone and in combination with aerobic biodegradation. The kinetics of the decolorization of Reactive Black 5 using a combination of hydrogen peroxide and UV radiation have been investigated. The rate of decolorization is first order with respect to dye concentration. It is enhanced with increasing hydrogen peroxide concentrations up to an optimum value. In our model we have correlated an empirical reaction rate expression which considers the contribution of both hydrogen peroxide and UV flux radiation based on the reaction kinetics. This empirical correlation agrees well with the experimental data for these conditions. Complete decolorization corresponded with 40-50% mineralization of the dye. Further mineralization can be achieved with extended radiation time.
Comparison of advanced oxidation processes in flow-through pilot plants (Part I)
Authors: Müller J.-P. , Jekel M.
Published: May 2018

The advanced oxidation processes (AOPs) UV/H2O2, UV/O3 and O3/H2O2 were optimised to achieve a 90% degradation of the micropollutant atrazine in continuous-flow reactors. The experiments were performed with spiked Berlin tap-water. The comparison of mechanistically different oxidation systems needs a non-specific figure-of-merit to avoid influences by system-inherent parameters. The chosen figure-of-merit consists of the electrical energy per order of magnitude in oxidation per m3, EE/0. The combination O3/H2O2 proved to be the most efficient process by means of energy consumption.
Photochemical oxidation of iodized X-ray contrast media (XRC) in hospital wastewater
Authors: Sprehe M. , Geißen S.-U. , Vogelpohl A.
Published: May 2018

Iodized X-ray contrast media (XRC) for medical applications are responsible for the high concentration of AOX (halogenated organic compounds adsorbable on activated carbon) in hospital wastewater exceeding the legal German discharge limit. The refractory properties of these substances lead to an accumulation in the natural waterbody. The elimination of contrast media from hospital wastewater by photochemical oxidation with hydrogen peroxide was investigated. The mechanism and the kinetics of the degradation of XRC were examined. These experiments demonstrate that a complete removal of the organically bonded iodine and a partial mineralization is feasible. The degradation in the UV reactor could be enhanced by adding hydrogen peroxide and by using a bubble column to remove the formed elemental iodine from the solution by stripping. Furthermore, the influence of various operating parameters such as gas flowrate, H2O2 input, XRC concentration and kind of XRC were investigated. Experiments showed that a recycling of elemental iodine from the exhaust gas is technically and economically possible.
Interaction analysis of stakeholders in water supply systems
Authors: Tillman T. , Larsen T. A. , Pahl-Wostl C. , Gujer W.
Published: May 2018

An analysis of the characteristic goals, strategies and rules of behavior of relevant stakeholders allows the efficacy and potential risks of past and current engineering and management concepts to be estimated. The study is driven by the observable shift from security to cost-centered strategies by water utilities and the difficulties of balancing technical and financial needs in an uncertain future. Its benefits include a methodology with a twofold result. With the aid of domain knowledge from experts involved in a participatory process, the interactions of a subset of stakeholders are quantified and documented in a rule catalog. This leads to an improved understanding of their decision-making rules. An agent-based model comprising these stakeholders' rules of behavior in subsequently development. Once the model is validated with data sets from a real utility, multiple-scenario testing helps to explore different strategies and can be used to generate ideas for developing flexible management and design schemes. Despite the complexity of the system described, simple model rules which are repeated annually can replicate the general development of both capacity and cost-related parameters. Scenario simulations show the effects of different management strategies on key parameters such as capacity, water price and financial debt.
Evapotranspiration for domestic wastewater reuse in remote indigenous communities of Australia
Authors: Anda M. , Mathew K. , Ho G.
Published: May 2018

In the past sewage ponding in indigenous settlements was commonplace as a result of overcrowding combined with inappropriate septic tank and leach drain design, installation and operation. The response over the past 10 years has been to develop reticulated sewerage systems to lagoons when the funds become available. These are often successful in terms of operation, improved public health and low maintenance but are expensive and wasteful of limited water supplies. Evapotranspiration (ET) is an effective method for on-site domestic effluent disposal in areas of Western Australia with soils of low permeability. Evapotranspiration systems have been established in a number of communities both for research/demonstration and as specified by architects. The systems usually follow two septic tanks for the disposal of all domestic effluent. A case study will be presented for a remote indigenous community where the ET systems installed for greywater only have been monitored over the last two years since installation. The use of evapotranspiration has enabled reuse of effluent for successful examples of revegetation and food production and points to the need for a holistic approach to design and service delivery in these communities that includes a total environmental management plan.
Effect of heavy metals (Cu, Pb, and Ni) on the compositions of EPS in biofilms
Authors: Jang A. , Kim S. M. , Kim S. Y. , Lee S. G. , Kim I. S.
Published: May 2018

A series of batch adsorption tests to estimate the biofilm capacity for removal of the heavy metals (Cu, Pb, and Ni) in wastewater were carried out. The metal sorption results were fitted to the Freundlich isotherm model to compare their sorption capacity. The change of the composition of EPSs (extracellular polymeric substances) was simultaneously represented by the ratio of carbohydrate to protein (C/P) when the biofilm was exposed to the heavy metals. EPS composed of slime loosely bound to the cell and capsular materials was extracted by the four general extraction methods including regular centrifugation, regular centrifugation with formaldehyde, EDTA extraction and steam extraction. Although the various extraction methods showed different results, C/P ratio of biofilm exposed to copper and lead metal ions was generally lower than that of control.
Study of impacts of treated wastewater to the Krka river, Slovenia
Authors: Cotman M. , Zagorc-Koncan J. , Droic A.
Published: May 2018

Surface waters are used for disposal of treated effluents from wastewater treatment plants. These effluents usually contain only small amounts of various contaminants but these harmful components accumulate over time in the river, especially in sediments.

An integrated approach for the evaluation of the impact of treated effluents was used to predict an ecological risk assessment to the Krka river beside Novo Mesto. The effluents from pharmaceutical and municipal wastewater treatment plants were discharged too closely into the receiving stream, so that separate impacts could not be distinguished. Biologically treated industrial effluents contained great amounts of barely biodegradable organic pollution, organic nitrogen, ammonia and phosphorus, and sometimes zinc. The toxicity of effluents was mostly dependent on their chemical composition. The municipal discharge contained greater amounts of organic pollution that was completely biodegraded but still had a great nutrient pollution load. The effluents were nontoxic. The harmful substances from the effluents were traced in the river. In the downstream site slightly higher concentration of organic pollutants, organic nitrogen, phosphorus, and zinc were detected due to discharges. The river water was over-saturated with oxygen, especially in the summer. In toxicity tests, samples of the river water were nontoxic. Sediments at the downstream site accumulated from discharged organic nitrogen, phosphorus, or zinc.

The results of our study show that the main problem is eutrophication of the river Krka, so it is obvious we must reduce the quantity of nutrients in the effluents from wastewater treatment plants. In both effluents it will be necessary to reduce the polluting load of phosphorus, the limiting element for growth of algae and macrophytes in the receiving stream. In the industrial effluent it will be necessary to reduce substances which cause toxicity, such as zinc and nonbiodegradable organic compounds that may be accumulated in the water ecosystem over time.
Evaluation of total nitrogen pollution reduction strategies in a river basin: a case study
Authors: Droic A. , Zagorc-Končan J. , Cotman M.
Published: May 2018

The enrichment of groundwater and rivers by nutrients (nitrogen and phosphorus compounds) and their consequences is one of the most severe problems across Europe as well in Slovenia. Transfer of nutrients from different sources into the environment causes eutrophication of surface waters, nitrate accumulation in groundwater, and others. In this paper, the methodology of the material flow analysis is presented and applied to develop a nitrogen balance in a river basin and to evaluate different scenarios for total nitrogen pollution reduction. Application of the methodology is illustrated by means of a case study on the Krka river, Slovenia. Different scenarios are to be considered: the present level of sewerage and treatment capacities, different stages of wastewater treatment and management of agricultural activities on land. The results show that beside effluents from wastewater treatment plants, agriculture contributes significantly to the total annual nitrogen load. Beside reduction of point sources by means of wastewater collection and implementation of nutrient removal technology, managing agricultural nitrogen in order to protect river water quality and drinking water supply should become a major challenge in the Krka river basin.
Adsorption of heavy metals by EPS of activated sludge
Authors: Liu Y. , Lam M. C. , Fang H. H.
Published: May 2018

Extracellular polymeric substances (EPSs) were extracted by high-speed centrifugation at 20,000 G for 30 min from an activated sludge treating municipal wastewater. Each gram of sludge, as measured in volatile suspended solids (VSS), contained 7.3 mg of EPS, including 6.5 mg of protein (EPSp) and 0.8 mg of carbohydrate (EPSc). The EPSp had a mean MW of 2.0×105; about 18% of EPSp had MW over 5×104 and 16% below 5×103. For heavy metal concentrations ranging 10-100 mg/l, EPS on average removed 99% of Zn2+, 98% of Cu2+, 97% of Cr3+, 85% of Cd2+, 69% of Co2+, 37% of Ni2+, and 26% of CrO42-. The relative degrees of metal removals were inconsistent with those reported for the activated sludge process. Each mg of ESP had the capacity to remove up to 1.48 mg of Zn2+, 1.12 mg of Cu2+, 0.83 mg of Cr3+, 0.90 mg of Cd2+, 1.10 mg of Co2+, 0.25 mg each of Ni2+ and CrO42-. Results suggest the feasibility of recovering ESP from waste sludge for use as adsorbent. Freundlich isotherm correlated satisfactorily with the adsorption data of Ni2+,Cu2+, Cd2+, and CrO42-, (R2 ranging 0.89-0.97), whereas Langmuir isotherm correlated satisfactorily with those of Zn2+, Cr3+ and Ni2+ (R2 ranging 0.93-0.96). Both correlated poorly for those of Co2+.
Degradation kinetics of reactive dye by UV/H2O2/US process under continuous mode operation
Authors: Fung P. C. , Poon C. S. , Chu C. W. , Tsui S. M.
Published: May 2018

Degradation of a dye, C.I. Reactive Red 120, in dyeing wastewater by the process of UV/H2O2/US was studied with a bench-scale reactor under the continuous mode of operation. The effects of dyeing wastewater flow rate and the feeding rate of an oxidant, H2O2, on the color removal efficiency of the process were investigated. The significance of ultrasonic (US) combined with UV irradiation was also investigated and the performances of the process on color removal were evaluated. The results showed that the decoloration process followed a pseudo first-order kinetic model and the UV light is the most significant factor on dye removal. Besides, at higher flow rates, incomplete color removal was observed due to relatively insufficient irradiation time (low degradation rate). In order to achieve a higher degradation rate, the feeding rate of H2O2 should be increased.
Sludge and washwater management strategies for the Vaalkop water treatment plant
Authors: Haarhoff J. , van Heerden P. , van der Walt M.
Published: May 2018

The Vaalkop plant, owned and operated by Magalies Water, provides a valuable South African case study of sludge and washwater management at a large water treatment plant. Starting out as a small plant of 18 Ml/day about thirty years ago, it has steadily grown to a plant with treatment capacity of 210 Ml/day; fairly large by South African standards. During the preceding years, it has not only been subject to a vastly larger scale of operation, but it also had to adapt to a tremendous increase in the cost of raw water, an increased environmental awareness amongst water treatment professionals and general public alike, and a much more sophisticated and complicated legislative framework. It is the objective of this paper to track the sludge and washwater management practices adopted over the years at Vaalkop, and to present the current strategies adopted for the medium to long term.

The paper will summarize the previous methods of sludge and washwater disposal, with reasons why they were adopted. The multitude of technical analyses and alternatives that were performed over the years will be summarized, and may provide valuable pointers for other applications in South Africa. The current system, which has just been commissioned, will be presented; its technical design parameters, the anticipated mode of operation, its costs and how the current environmental and legislative requirements are being met.
On-site wastewater technologies in Australia
Authors: Ho G. , Dallas S. , Anda M. , Mathew K.
Published: May 2018

Domestic wastewater reuse is currently not permitted anywhere in Australia but is widely supported by the community, promoted by researchers, and improvised by up to 20% of householders. Its widespread implementation will make an enormous contribution to the sustainability of water resources. Integrated with other strategies in the outdoor living environment of settlements in arid lands, great benefit will be derived. This paper describes six options for wastewater reuse under research by the Remote Area Developments Group (RADG) at Murdoch University and case studies are given where productive use is being made for revegetation and food production strategies at household and community scales. Pollution control techniques, public health precautions and maintenance requirements are described. The special case of remote Aboriginal communities is explained where prototype systems have been installed by RADG to generate windbreaks and orchards. New Australian design standards and draft guidelines for domestic greywater reuse produced by the Western Australian State government agencies for mainstream communities are evaluated. It is recommended that dry composting toilets be coupled with domestic greywater reuse and the various types available in Australia are described. For situations where only the flushing toilet will suffice the unique “wet composting” system can be used and this also is described. A vision for household and community-scale on-site application is presented.
Cell surface and exopolymer characterization of laboratory stabilized activated sludge from a beverage bottling plant
Authors: Boyette S. M. , Lovett J. M. , Gaboda W. G. , Soares J. A.
Published: May 2018

Fermentor-stabilized activated sludge from an industrial beverage bottling plant was grown on three different food sources: normal plant wastewater, plant wastewater containing high sucrose concentrations, and a synthetic glucose-based feed stock. Surface charge, hydrophobicity, and exopolysaccharide composition were measured on the stabilized bacterial flocs. Cell surface charge was measured by electrophoretic mobility, dye exchange titration, and a standard colloid titration, while cell hydrophobicity was determined using the bacterial adhesion to hydrocarbons (BATH) test. Exopolysaccharide profiles were determined by measuring concentrations of glucose, galactose, mannose, glucuronic, and galacturonic acids in digested exopolymer extractions using HPLC. Changes in the physical surface properties of the bacteria and the chemical composition of the extracted exopolymers were correlated with differences in the three food sources. Cell surface hydrophobicity was similar for cultures grown on different plant wastewaters, while the culture grown on synthetic food produced less floc hydrophobicity. Electrophoretic mobility measurements, charge titrations, and dye exchange titrations showed different total surface charge as well as varying charge availability. Additionally, total surface charge and total exopolysaccharide concentrations appeared less dependent on food source than the food-to-mass ratio. High concentrations of biodegradable food produced dispersed growth and high concentrations of exopolysaccharides that contributed to poor settling.
Catch basin inserts to reduce pollution from stormwater
Authors: Lau S.-L. , Khan E. , Stenstrom M. K.
Published: May 2018

Stormwater contamination represents the largest source of contaminants to many receiving waters in the United States, such as Santa Monica Bay in Los Angeles, California. Point sources to these same waters generally receive secondary or better treatment before they are released, and they are usually discharged through outfalls that diffuse the wastewater plume to prevent it from contacting the shoreline. Stormwaters receive no treatment and reach the receiving waters through a variety of ways, but most enter through catch basins or inserts to storm drains that terminate at the beach or in shallow coastal areas. Under these conditions, the stormwater discharge may have greater impact on the quality and utility of the receiving water than the treated wastewater discharges. One method of reducing pollution is to equip catch basins with an insert that can capture pollutants. A number of commercially available devices exist but few have been evaluated by independent parties in full-scale applications. A series of tests using bench and full-scale devices under both laboratory and field conditions were conducted to evaluate their ability to remove trash and debris, suspended solids and oil and grease in stormwaters. The results presented in the paper should provide a basis for future insert development and application.
Runoff of acidic substances that originated from atmospheric deposition on Yakushima Island, a world natural heritage site
Authors: Nagafuchi O. , Kakimoto H. , Ebise S. , Inoue T. , Koga M.
Published: May 2018

In this paper we present monitoring data of stream waters that may reflect acidic impacts on the island as well as the rainwater qualities. The pH ranges of the river water in the Kawara streams in the western part of the island and the Yodogo stream in the central part of the island were 5.71-6.35 and 5.85-6.12 during 1992-1999, respectively. The concentrations of SO42− and NO3− in the river water were lower than those in the rainwater. Many differences were observed among the sampling sites. Higher concentrations of acid substances are found in the stream waters of the western area compared to the other areas. On the other hand, sulfuric acid is the major acid in the rainwater, snow and rime ice. No differences were observed in the ion constituents of the rainwater collected in the areas. These results suggested that the densely growing canopy may play a role in holding air pollutants, and acidic substances deposited on the canopy would be discharged as a through-fall and a stem flow. Furthermore, the water mass containing high ionic substances in the western area has been held in the groundwater layer, continuously supplying the stream waters during dry weather days. On the other hand, part of the basic runoff will be diluted with a surface runoff during the rainy days. As a result, the concentrations of the ionic substances in the stream waters during rainy days decreased.