bluuebunny/crossref_metadata_2025 huggingface dataset:
Water safety plans for small systems: a model for applying HACCP concepts for cost-effective monitoring in developing countries
Authors: Howard G.
Published: May 2018

The development of water safety plans (WSPs) for small systems should be based on a thorough understanding of the relationships between risk factors and contamination events. This can be achieved through the use of well-designed assessments of water quality that provide better evidence to support the identification of control measures, performance limits, monitoring parameters and verification procedures. Training of community operators is critical to the success of the WSP and the understanding gained from the assessments provides a sound basis for addressing these needs. The WSP approach provides for more effective control of water quality and the use of targeted assessments is cost-effective in improving the design of WSPs.
Antibiotic selective pressure for the maintenance of antibiotic resistant genes in coliform bacteria isolated from the aquatic environment
Authors: Park J.C. , Lee J.C. , Oh J.Y. , Jeong Y.W. , Cho J.W. , Joo H.S. , Lee W.K. , Lee W.B.
Published: May 2018

Coliform bacteria isolated from the aquatic environment were investigated for antibiotic susceptibility and detailed structures of class 1 integrons. A high proportion of isolates were found to be resistant to sulfamethoxazole, aminoglycosides, and β-lactams. The 750 (53.6%) isolates were resistant to one or more of the antibiotics tested out of 1,400 coliform bacteria. Based on the MIC of antibiotics and antibiogram, 150 isolates were selected and further studied for class 1 integrons. The intI1 gene was found in 36 (24.0%) of the 150 isolates. Twelve isolates carried the gene cassettes responsible for antibiotic resistance, while no gene cassettes were found in 24 isolates. Seven different genes, dfrA5, dfrA7, dfrA12, dfrA17, aaA2, aaA5, and aad(3’), were detected in gene cassettes. The dfrA and aad genes located on class 1 integrons were responsible for resistance to trimethoprim and aminoglycosides. The remaining 24 coliform bacteria had the incomplete or non-functional class 1 integrons. These results indicated that antibiotic selective pressures may play an important role to maintain gene cassettes of class 1 integrons and in the absence of sustained antibiotic pressures, such as the aquatic environment, coliform bacteria may carry empty or non-functional class 1 integrons.
The nature and pollutant role of solids at the water-sediment interface in combined sewer networks
Authors: Chebbo G. , Ashley R. , Gromaire M.-C.
Published: May 2018

Solids at the water-sediment interface in combined sewers are known to be important for pollution potential during storm washout via CSOs. They have been investigated in several studies, but nonetheless, little is known about the origins, build-up, transport and nature of these solids. From a review of current knowledge, it is apparent that whilst there is general agreement that these solids are largely organic and have high polluting potential, their modes of transport and definition are not generally agreed upon. It is possible that there may be several “types” of these solids, defined as either: “near bed solids” or “fluid sediments/dense undercurrents”, possibly representing transport modes in flows with different ranges of ambient (dry weather) velocities and with differing sewerage layouts. Current knowledge is presented and new ideas for resolving the uncertainties regarding the nature, movement and effects of this material are outlined.
Enhancement of polycyclic aromatic hydrocarbons removal during anaerobic treatment of urban sludge
Authors: Trably E. , Patureau D. , Delgenes J.P.
Published: May 2018

Anaerobically stabilized sewage sludge has potential to partially substitute synthetic fertilizers. The main risk with the recycling of urban sludge on agricultural soils is the accumulation of unwanted products, such as trace metals and organic micropollutants. In this context, the polycyclic aromatic hydrocarbons (PAHs) are particularly monitored because of their toxic properties at low concentrations and their high resistance to biological degradation. The aim of the present study was to optimize PAHs removal during anaerobic digestion of contaminated sewage sludge. Thirteen PAHs were monitored in laboratory-scale anaerobic bioreactors under mesophilic (35°C) and thermophilic (55°C) methanogenic conditions. Abiotic losses were statistically significant for the lightest PAHs, such as fluorene, phenanthrene and anthracene. It was shown that PAH removal was due to a specific biological activity. Biological PAHs removal was significantly enhanced by an increase of the temperature from 35°C to 55°C, especially for the heaviest PAHs. Bioaugmentation experiment was also performed by addition of a PAH-adapted bacterial consortium to a non-acclimated reactor. Significant enhancement of PAHs removal was observed. It was finally shown that PAH removal efficiencies and methanogenic performances were closely linked. The rate of biogas production may be used as an indicator of bacterial activity on PAH removal.
Introducing the emission process of hydrogen sulfide to a sewer process model (WATS)
Authors: Yongsiri C. , Hvitved-Jacobsen T. , Vollertsen J. , Tanaka N.
Published: May 2018

Emission of hydrogen sulfide in sewer networks results in odor, health and corrosion problems. These problems generally occur when wastewater is transported under anaerobic and turbulent conditions. Studies on integrated aerobic/anaerobic processes in sewers have led to a conceptual sewer process model, WATS (Wastewater Aerobic/anaerobic Transformations in Sewers). The WATS model accounts for the carbon cycle, reaeration and sulfide formation. However, to handle odor, health and corrosion problems more efficiently, other aspects of the sulfur cycle need to be included. Emphasis in this study is on an extension of the WATS model in terms of hydrogen sulfide emission. A fundamental concept of this extended model is related to emission of the molecular form of hydrogen sulfide and thereby to pH of wastewater. An engineering application of the extended WATS model includes different scenarios of sewer performance concerning hydrogen sulfide emission under dissolved oxygen-limited conditions. By applying the extended WATS model, users can more realistically cope with the fate of hydrogen sulfide. Consequently, when dealing with the sulfur cycle, users need no longer be restricted to the sulfide formation process but can also take transfer of hydrogen sulfide across the air-water interface into account.
Modelling in-sewer pollutant degradation processes in the Costa do Estoril sewer system
Authors: Mourato S. , Matos J. , Almeida M. , Hvitved-Jacobsen T.
Published: May 2018

Characteristics of wastewater vary during transportation through sewer systems as a result of a number of processes. Under aerobic conditions, in long sewer systems, the reduction of the BOD or COD may be similar to the reduction obtained in conventional primary settling tanks. The mathematical model that was developed is based on a number of different existing models: the ASM n. 1 and ASM n. 2 models, the AEROSEPT model and the WATS model. The model also includes a prediction of reaeration at falls. The module of the anoxic conditions was adapted from the ASM n. 2 model. This module is a first attempt to model the degradation of organic matter in sewer systems under anoxic conditions. The mathematical model was applied to the Costa do Estoril intercepting sewer, and the obtained results are discussed taken into account the experimental data that was collected during a three-month period. Average removals of dissolved COD over 20% have been obtained. In the paper special emphasis is given to the importance of the performance of the Costa do Estoril sewer system as a biological reactor.
The use of hydrodynamic vortex separators and screening systems to improve water quality
Authors: Andoh R.Y.G. , Saul A.J.
Published: May 2018

The paper reviews the evolution of Hydrodynamic Vortex Separators (HDVS) in the context of their application as high rate rotary flow separators for achieving water quality improvements to meet with regulatory requirements in Europe and North America. The types of HDVS and their application for the control of wet-weather discharges such as combined sewer overflows (CSOs), sanitary sewer overflows (SSOs) and stormwater are outlined and a number of myths surrounding their use, dispelled. Reference is made to outputs of peer reviewed comprehensive monitoring, evaluation and demonstration projects on pilot and full-scale installations to demonstrate the efficacy and extensive track record of these systems. Recent developments and innovations in HDVS technologies are discussed, focusing on their combined use as solids liquid separators, contact vessels for wastewater disinfection, the incorporation of self-cleansing screening devices for the control of aesthetic pollutants (e.g. floatables) and the use of computational modelling for optimisation.
Life cycle analysis and sewer solids
Authors: Gouda H. , Ashley R.M. , Gilmour D. , Smith H.
Published: May 2018

The search for sustainable ways of living has necessitated a new look at the way in which water services are provided. The new paradigm includes whole-system perspectives for each of the primary criteria groups: social, environmental and economic. Whilst Life Cycle Analysis (LCA) techniques have been used successfully for products, they are much less used to assess processes. Nonetheless there is much to learn from the use of LCA for a much wider range of applications. An application is described whereby LCA has been used to determine energy, mass flows and environmental impacts for a number of sewer-related options for handling sewer solids, using the SimaPro software. This work has been part of a wider study to provide enhanced decision support systems for water utilities.
Microbiological removal of hydrogen sulfide from biogas by means of a separate biofilter system: experience with technical operation
Authors: Schieder D. , Quicker P. , Schneider R. , Winter H. , Prechtl S. , Faulstich M.
Published: May 2018

The “BIO-Sulfex” biofilter of ATZ-EVUS removes hydrogen sulfide from biogas in a biological way. Hydrogen sulfide causes massive problems during power generation from biogas in a power plant, e.g. corrosion of engines and heat exchangers, and thus causes frequent and therefore expensive engine oil changes. The BIO-Sulfex module is placed between the digester and the power-plant and warrants a cost-effective, reliable and fully biological desulfurization. In the cleaned gas concentrations of less than 100 ppm can be achieved. Power-plant manufacturers usually demand less than 500 or less than 200 ppm. At present, several plants with biogas flow rates between 20 and 350 m3/h are in operation.
Degradation of plant wastes by anaerobic process using rumen bacteria
Authors: Seon J. , Creuly C. , Duchez D. , Pons A. , Dussap C.G.
Published: May 2018

An operational reactor has been designed for the fermentation of a pure culture of Fibrobacter succinogenes with the constraints of strict anaerobic condition. The process is controlled by measurements of pH, redox, temperature and CO2 pressure; it allows an efficient degradation (67%) of lignocellulosic wastes such as a mixture of wheat straw, soya bean cake and green cabbage.
Methane production from sweet sorghum residues via a two-stage process
Authors: Stamatelatou K. , Dravillas K. , Lyberatos G.
Published: May 2018

The start-up of a two-stage reactor configuration for the anaerobic digestion of sweet sorghum residues was evaluated. The sweet sorghum residues were a waste stream originating from the alcoholic fermentation of sweet sorghum and the subsequent distillation step. This waste stream contained high concentration of solid matter (9% TS) and thus could be characterized as a semi-solid, not easily biodegradable wastewater with high COD (115 g/l). The application of the proposed two-stage configuration (consisting of one thermophilic hydrolyser and one mesophilic methaniser) achieved a methane production of 16 l/l wastewater under a hydraulic retention time of 19 d.
Role and levels of real-time monitoring for successful anti-fouling strategies - an overview
Authors: Flemming H.-C.
Published: May 2018

Biofouling is a biofilm problem and any anti-fouling strategy will be greatly improved if the site and extent of biofilm growth can be monitored. A suitable monitoring system will provide early warning capacity and allow for specific optimization of countermeasures. As water samples do not give reliable information about biofilms, surface sampling is mandatory. Conventional biofilm monitoring techniques rely on removal of material from representative sites or on analysis of test surfaces which have been exposed. This procedure is time consuming and, depending on the parameters to be measured, requires skilled laboratory personnel. There is a strong demand for direct, on-line, in situ, continuous, non-destructive real-time information about biofilms in a system. Such demands can only be fulfilled by physical or physico-chemical methods, a number of which have already been successfully applied for biofilm monitoring. It is important, however, to be aware of the actual parameter they refer to in order to interpret the data properly. Three levels of information can be identified: (i) systems which detect increase and decrease of material accumulating on a surface but cannot differentiate between biomass and other components of a deposit, (ii) systems which provide biological information and distinguish between biotic and abiotic material, and (iii) systems which provide detailed chemical information. Examples for all three levels are presented and discussed.
Biofilm monitoring by photoacoustic spectroscopy
Authors: Schmid T. , Panne U. , Haisch C. , Niessner R.
Published: May 2018

The use of photoacoustic spectroscopy (PAS) as a new biofilm monitoring technique is presented. Growth and detachment of biofilms at three different positions inside a flow channel were monitored by photoacoustic measurements in the visible spectral range (λ = 532 nm). The experimental approach allows the investigation of the influence of various process parameters (e.g. pH or flow conditions) on growth and detachment of biofilms. In addition, the distribution of the attached biomass can be monitored by depth-resolved photoacoustic measurements.
Seasonal variation in phosphorus removal processes _within reed beds - mass balance investigations
Authors: Headley T.R. , Huett D.O. , Davison L.
Published: May 2018

The phosphorus (P) removal processes in two pairs of High and Low Loaded reed beds were investigated during five periods within a 27-month study. The uptake/release of P was measured in seven mass balance compartments. With the exception of the first year of operation, the reed beds consistently removed over 96% of the influent P load, with total phosphorus (TP) concentrations being reduced from 0.5 mg/L to generally less than 0.005 mg/L across the range of loading rates and seasons studied. During the first year, uptake by Phragmites australis accounted for greater than 75% of P removed, and was equally distributed between above and below-ground biomass. During the second and third years, three seasonal stages were identified in the uptake and cycling of P by P. australis. A period of rapid above-ground growth and uptake occurred during spring fuelled partly by P reserves accumulated in rhizomes during the previous year. During summer, uptake by above-ground biomass was governed by the influent P loading rate, while the amount of P held in below-ground biomass remained relatively stable. During autumn and winter, P appeared to be translocated from senescent shoots to reserves in the rhizomes. Approximately 85% of the below-ground biomass P occurred in the top 20 cm of the substrate. Gravel fixation increased in importance from 12% in the first year to approximately 30% of P removed in the second year, with a highly significant correlation between the influent P loading rate and P fixed by the gravel. The weakly-bound P fraction from a sequential extraction was the dominant form of P fixed by the gravel. HCl extracts were inappropriate for the examination of sorption processes as they dissolved large amounts of mineral P from within the basaltic gravel. The bottom 30 cm of the substrate became the most important site for gravel fixation during the second year. Incorporation of P into the detritus/microbiota/other compartment increased after the first year to become one of the most important P removal processes, probably consisting mainly of leaf litter and slowly accreted organic sediments.
Monitoring biofilm detachment under dynamic changes in shear stress using laser-based particle size analysis and mass fractionation
Authors: Choi Y.C. , Morgenroth E.
Published: May 2018

Biofilm detachment under a dynamic change in shear stress was monitored using Focused Beam Reflectance Measurements (FBRM, LASENTEC®) and mass fractionation. An annular reactor was used to grow biofilm with glucose as substrate. Changing the rotational speed on the inner cylinder of the annular reactor from 150 RPM to 420 RPM induced a step increase in shear stress. It was observed that the rate of detachment increased rapidly after increasing shear stress and then returned to the previous level. Erosion was the dominant process of detachment under steady state operation, whereas sloughing was dominant following the sudden increase in shear stress. After reaching steady state detachment under high shear conditions, the rotational speed was decreased for a 12-hour period. During this brief period of lower shear, the biofilm adjusted to this new condition. When the shear stress was increased again, another sharp increase in effluent solids concentration was observed. A decrease in density indicates that the biofilm became more vulnerable to shear stress after being subjected to this short period of low shear.
Rapid detection of biofilms and adherent pathogens using scanning confocal laser microscopy and episcopic differential interference contrast microscopy
Authors: Keevil C.W.
Published: May 2018

Knowledge of biofilm structure and function has changed significantly in the last few years due to advances in light microscopy. One pertinent example is the use of scanning confocal laser microscopy (SCLM) to visualise corrosion pits caused by the biofilm mosaic footprint on corroding metal surfaces. Nevertheless, SCLM has some limitations as to its widespread use, including cost, inability to observe motile bacteria and eukaryotic grazers within biofilms, and difficulty to scan a curved surface. By contrast, episcopic differential interference contrast (EDIC) microscopy has provided a rapid, real time analysis of biofilms on opaque, curved, natural or man-made surfaces without the need for cover slips and oil. EDIC, coupled with epi-fluorescence (EDIC/EF), microscopy has been used successfully to visualise the 3-D biofilm structure, physiological niches, protozoal grazing and iron biomineralization, and the location of specific pathogens such as Legionella pneumophila, Campylobacter jejuni and Cryptosporidium parvum. These species were identified using gold nanoparticles or fluorophores coupled to monoclonal antibodies or 16S rRNA probes, respectively. Among its many potential uses, the EDIC technique will provide a rapid procedure to facilitate the calibration of the modern generation of biofilm-sensing electrodes.
Microbial community structure in biofilms and water of a drinking water distribution system determined by lipid biomarkers
Authors: Keinänen M.M. , Martikainen P.J. , Korhonen L.K. , Suutari M.H.
Published: May 2018

The development of microbial communities in biofilms of a drinking water distribution system was monitored, and compared to the microbial communities in water. The microbial communities were studied by phospholipid fatty acid (PLFA) profiles. In drinking water samples the most common PLFAs, with the proportion of 60.9%, were monoenoic fatty acids, such as 16:1ω7c and 18:1ω7c, indicating high abundance of gram-negative bacteria. Instead, in biofilm samples saturated fatty acids, such as 16:0 and 18:0, indicating general biomass, accounted for 54.9-78.4% of the total PLFAs. The proportions of monoenoic fatty acids in biofilm increased from 11.5% to 31.2% with water aging from 22 h to 62 h in the distribution system. In conclusion, water aging affected the structure of microbial communities in biofilms, and the microbes in water differed from those in biofilms. These differences might also reflect the differences in the physiological state of the microbes, which is influenced by water chemistry and by the growth environment, i.e. water or biofilm.
Molecular characterization of bacteria inhabiting a water distribution system simulator
Authors: Santo Domingo J.W. , Meckes M.C. , Simpson J.M. , Sloss B. , Reasoner D.J.
Published: May 2018

The objective of this study was to monitor the impact of chlorination and chloramination treatments on heterotrophic bacteria (HB) and ammonia-oxidizing bacteria (AOB) inhabiting a water distribution system simulator. HB densities decreased while AOB densities increased when chloramine was added. AOB densities decreased below detection limits after the disinfection treatment was switched back to chlorination. The presence of AOB was confirmed using a group-specific 16S rDNA-PCR method. 16S rDNA sequence analysis showed that most bacterial isolates from feed water, discharge water, and biofilm samples were α-Proteobacteria or β-Proteobacteria. The latter bacterial groups were also numerically dominant among the sequences recovered from water and biofilm 16S rDNA clone libraries. The relative frequency of each culturable bacterial group was different for each sample examined. Denaturing gradient gel electrophoresis analysis of total community 16S rDNA genes showed notable differences between the microbial community structure of biofilm samples and feed water. The results of this study suggest that disinfection treatments could influence the type of bacterial community inhabiting water distribution systems.
Simulation of subsurface flow constructed wetlands - results and further research needs
Authors: Langergraber G.
Published: May 2018

Simulation of constructed wetlands has two main tasks: to obtain a better understanding of the processes in constructed wetlands, and to check and optimise existing design criteria. This paper shows simulation results for two indoor pilot-scale constructed wetlands for wastewater and surface water treatment respectively. The results presented and discussed are mainly focussed on the hydraulic behaviour of the constructed wetland systems. In addition results of reactive transport simulations with CW2D are shown. The multi-component reactive transport model CW2D (Constructed Wetlands 2 Dimensional) was developed to model transport and reactions of the main constituents of wastewater (organic matter, nitrogen, and phosphorus) in subsurface flow constructed wetlands. For the pilot-scale constructed wetlands a calibration of the flow model was possible and therefore the results of the reactive transport simulations with CW2D fit the measured data well. The further research needs regarding the simulation of subsurface flow constructed wetlands are discussed.
On the dynamics and function of ciliates in sequencing batch biofilm reactors
Authors: Fried J. , Lemmer H.
Published: May 2018

Ciliates are known to directly influence the performance of wastewater treatment plants mainly by feeding on suspended particles. By monitoring two lab-scale sequencing batch biofilm reactors (SBBR), one filled with expanded shale (clay spheres), the other with “Kaldnes” particles (PE-carriers), the succession of biofilm communities with special emphasis on ciliates was monitored for one year. Ciliates were identified and quantified at the species level and compared to rotifer and nematode abundances. Members of the subclass Peritrichia clearly dominated the community of protozoa. Epistylis cf. coronata and Opercularia asymmetrica were the dominant species within this group. The tree-like structure of their colonies provided a distinctive augmentation of the area available for bacterial colonization. The flux of water, produced by E. cf. coronata due to cilia motility, has been visualized and measured by video processing. This flux of water was still measurable at distances > 500 mm and maximum water currents raised up to 180 mm s−1. Therefore, the role of ciliates is not only restricted to the ingestion of bacteria and suspended particles. They also alter water flux and carry nutrients to the inner parts of the biofilm. Thus, monitoring biofilm formation in wastewater treatment plants should always consider the impact of protists such as ciliates.
Potential use of mangrove plantation as constructed wetland for municipal wastewater treatment
Authors: Boonsong K. , Piyatiratitivorakul S. , Patanaponpaiboon P.
Published: May 2018

The study evaluated the possibility of using mangrove plantation to treat municipal wastewater. Two types of pilot scale (100 × 150 m2) free water surface constructed wetland were set up. One system was a natural Avicennia marina dominated forest system. The other system was a newly planted system in which seedlings of Rhizophora spp., A. marina, Bruguiera cylindrica and Ceriops tagal were planted in 4 strips. Municipal wastewater was retained within the systems for 7 and 3 days, respectively. The results indicated that the average removal percentage of TSS, BOD, NO3-N, NH4-N, TN, PO4-P and TP in the newly planted system were 27.6-77.1, 43.9-53.9, 37.6-47.5, 81.1-85.9, 44.8-54.4, 24.7-76.8 and 22.6-65.3, respectively. Whereas the removal percentage of those parameters in the natural forest system were 17.1-65.9, 49.5-51.1, 44.0-60.9, 51.1-83.5, 43.4-50.4, 28.7-58.9 and 28.3-48.0, respectively. Generally, the removal percentages within the newly planted system and the natural forest system were not significantly different. However, when the removal percentages were compared with detention time, TSS, PO4-P and TP percentages removed were significantly higher in the 7-day detention time treatment. Even though the removal percentages were highly varied and temporally dependent, the overall results showed that mangrove plantation could be used as constructed wetland for municipal wastewater treatment in a similar way to the natural mangrove system.
Screening the retention of thirteen pesticides in a small constructed wetland
Authors: Braskerud B.C. , Haarstad K.
Published: May 2018

When pesticides are used in arable watersheds, residues are usually found in the recipients. However, small constructed wetlands (CWs) in first and second order streams can reduce the loss of pesticides, since water purification processes are stimulated. This paper presents the results of adding 13 pesticides to a CW in Norway. The relative retention increased between 0 and 67% for the pesticides fluroxypyr, bentazone, dicamba, mecoprop, propiconazole, MCPA, dichlorprop, linuron, fenpropimorph, metalaxyl, metribuzin, metamitron and propachlor. In many cases, the CW reduced the peak concentrations to values regarded as non-toxic for aquatic life, even though the wetland covered less than 0.4% of the watershed surface area, and the average hydraulic load often was above 0.8 m d-1. Possible retention factors were adsorption to soil particles and organic matter, sedimentation of particles, low or high redox-potential, and biodegradation of nitrogen-rich pesticides. However, the retention processes are complex, and are not fully understood.
Distribution of Mn, Al, Cu and Zn in a constructed wetland receiving municipal sewage
Authors: Vymazal J. , Krása P.
Published: May 2018

A constructed wetland at Nucice near Prague, Czech Republic, has been in operation since 1996 and the system is designed to treat sewage from 650 PE together with stormwater. The total area of the beds planted with Phalaris arundinacea and Phragmites australis is 3,224 m2 (two beds 62 × 26 m each). Pea gravel (8/16 mm) is used as a filtration material. During the period 1998-1999, removal of Mn, Al, Cu and Zn from wastewater and distribution of the metals in sediments and plants were studied. Metals were measured in three vertical profiles of the filtration bed (0-15, 15-30 and 30-60 cm) and at four locations along the longitudinal profile of the bed (5, 16, 32, 48 m from the inlet). Metal concentrations in plant tissues (roots, stems, leaves) of Phalaris arundinacea were measured along the longitudinal profile of the bed at the same locations as for sediments. The results showed that the retention of metals is high (up to 98%) with the major decrease in metal concentrations within the first 5 metres of the bed. The major decrease in metal concentration in the filtration material was observed in the inlet zone between 5 and 16 metres. In Phalaris tissue, metal concentrations decreased in the order roots > stems > leaves but statistically significant differences varied among the studied metals.
International Freshwater Policy from Bonn to Johannesburg and Beyond
Authors: Berbalk D.
Published: May 2018

Thank you for inviting me to Stockholm and giving me the opportunity to speak on the international water policy following the results of the International Freshwater Conference, which we held in Bonn in December last year, and its implications for Johannesburg and beyond. After such a political speech of Minister Karlsson my speech might be to some extent repetitive and more bureaucratic; but it shows that we share the same views and come to the same conclusions – and that counts.
Essential metal depletion in an anaerobic reactor
Authors: Osuna M.B. , Iza J. , Zandvoort M. , Lens P.N.L.
Published: May 2018

The effect of the absence of trace elements on the conversion of a mixture of volatile fatty acids by a distillery anaerobic granular sludge was investigated. Two UASB reactors were operated under identical operational conditions except for the influent trace metal concentrations, during 140 days. Experiments were carried out in three periods, where different organic loading rates (OLR) were applied to the reactors. The total trace metal concentration steadily decreased at a rate of 48 μg metal/g TS.d in the deprived reactor (down to 35% of their initial value). In contrast, trace metals accumulated in granules present in the control reactor. At the end of the experiment, the COD removal efficiencies were 99% and 77% for the control and deprived reactors, respectively, due to the lack of propionate conversion. Cobalt sorption experiments were carried out in order to study its speciation, and its effects on the speciation of other metals as well. A paper mill wastewater treating granular sludge was also included in the study as a comparison. Results obtained showed that the principal metal forms normally associated with any sludge are a function of each soluble metal concentration in the system, and the characteristics of the particular sludge.
Balancing competing water uses - a necessity for sustainable development
Authors: Töpfer K.
Published: May 2018

The UNEP Water Policy and Strategy emphasises the need for environmentally sustainable water use as a key to sustainable development, including poverty reduction. The development of UNEP programmes over the years has produced an integrated, comprehensive and dynamic approach to competing water uses.
Influence of the initial substrate to microorganisms concentration ratio on the methanogenic inhibition test
Authors: Moreno-Andrade I. , Buitrón G.
Published: May 2018

The influence of the initial substrate to microorganisms ratio (So/Xo) on the inhibition of the methane production caused by 4-chlorophenol, 4CP, was studied. The effect of the 4CP on glucose degradation was evaluated measuring the quantity of methane produced during the test. One part of the inoculum was used as it came from its origin and another was fed with ethanol in order to maintain its activity. The inhibition tests were carried out using the same initial concentration of glucose, three initial suspended solids concentrations and eight initial concentrations of 4CP. The use of ethanol-acclimatized sludge presented a great influence on the inhibition results, since the inhibition was greater in the raw sludge than the acclimated one. Significant differences in the inhibition tests were found depending on the initial So/Xo ratio with respect to the glucose as substrate. It was observed that the inhibition decreases as the So/Xo decreases, in other words as the initial biomass concentration increases. When the results were analyzed in respect to the 4CP it was observed that the inhibition increases as the So/Xo increases. Also, it was observed that for the same value of So/Xo there is an increase of the inhibition when the quantity of Xo decreases.
Beyond the river: the benefits of cooperation on international rivers
Authors: Grey D. , Sadoff C.
Published: May 2018

Management of international rivers can be a cause of conflict or cooperation between states. Benefits of cooperation include benefits to the ecological river, the economic river, the political river and the catalytic river. The challenges are in balancing the trade-offs between states.
Automatic control of volatile fatty acids in anaerobic digestion using a fuzzy logic based approach
Authors: Puñal A. , Palazzotto L. , Bouvier J.C. , Conte T. , Steyer J.P.
Published: May 2018

A control law based on fuzzy logic was developed and validated for an anaerobic wastewater treatment process. The controlled variable was the concentration of volatile fatty acids (VFA) in the reactor and the manipulated variable was the input flow rate. In order to use it as the input of the fuzzy sets, the controlled variable was treated using an algorithm of interpolation, extrapolation and filtering. The treatment of VFA values attempted to anticipate the behaviour of the variable and to avoid the inherent delay of the response, associated to the time constant of the system. Furthermore, the controlled variable derivative was used as a second input of the fuzzy sets to increase or decrease the speed of the control action. The control law was applied to a 0.948 m3 fixed-bed anaerobic reactor treating raw and diluted (1:2) industrial distillery vinasses. The validation was performed establishing different transient states between different set points in the range of 0.8 and 1.8 g VFA/l and different concentrations of the influent. The control law proved to be reliable supplying an adequate control action in terms of amplitude and velocity to achieve the desired set point for different types of perturbation and control purposes.
Anaerobic biodegradation of BTEX using Mn(IV) and Fe(III) as alternative electron acceptors
Authors: Villatoro-Monzón W.R. , Mesta-Howard A.M. , Razo-Flores E.
Published: May 2018

Anaerobic BTEX biodegradation was tested in batch experiments using an anaerobic sediment as inoculum under Fe(III) and Mn(IV) reducing conditions. All BTEX were degraded under the conditions tested, specially under Mn(IV) reducing conditions, where benzene was degraded at a rate of 0.8 μmol l-1d-1, significantly much faster than Fe(III) reducing conditions. Under Fe(III) reducing conditions, ethylbenzene was the compound that degraded at the faster rate of 0.19 μmol l-1d-1. Mn(IV) reducing conditions are energetically more favourable than Fe(III), therefore, BTEX were more rapidly degraded under Mn(IV) reducing conditions. These results represent the first report of the degradation of benzene with Mn(IV) as the final electron acceptor. Amorphous manganese oxide is a natural widely distributed metal in groundwater, where it can be microbiologically reduced, leading to the degradation of monoaromatic compounds.
Influence of feedstock and bleaching technologies on methanogenic toxicity of kraft mill wastewater
Authors: Vidal G. , Diez M.C.
Published: May 2018

Chlorine-bleached effluent is problematic for anaerobic wastewater treatment due to its high toxicity against methanogenic bacteria. To date, alternative bleaching processes are being introduced, such as elemental chlorine-free (ECF) and total chlorine-free (TCF). The purpose of this study was to investigate the influence of bleaching technologies and different types of feedstock on methanogenic activity. In order to compare the toxicity of the different bleaching sequences per unit of COD, the 50%-inhibitory concentration (50% IC) for methanogenic bacteria of the different bleaching effluents were compared. The results show that there is no direct relationship between the effluentÕs methanogenic toxicity and the bleaching sequences. Methanogenic toxicity ranged from 0.6 to 2.4 g COD/L.
Riboflavin as a redox mediator accelerating the reduction of the azo dye Mordant Yellow 10 by anaerobic granular sludge
Authors: Field J.A. , Brady J.
Published: May 2018

Azo dyes are important persistent pollutants of textile industry effluents. Reduction of these dyes to their corresponding aromatic amines under anaerobic conditions can be used to initiate biodegradation. Since electron transfer is suggested to be rate limiting, redox mediators are being considered to improve dye reduction kinetics. This study evaluates the use of riboflavin, the redox active moiety of common occurring enzyme cofactors, as a redox mediator to accelerate the reduction of the azo dye, mordant yellow 10 (MY10). Dye reduction was found to follow zero order kinetics, the total rate constant (Vtotal) could be separated into two components: the rate of reduction due to direct contact between enzymes in the sludge with the dye (Vdirect); and the rate of reduction mediated by riboflavin (Vmediated). Riboflavin increased the Vtotal by 61% at extremely sub-stoichiometric concentrations of 9.1 μmol l-1, which corresponded to a molar riboflavin:dye ratio of 1:60. The accelerating effect of riboflavin displayed saturation kinetics at higher concentrations, with a maximum increase of Vtotal of approximately 2-fold. A model is presented which assumes that Vmediated depends on the activity of riboflavin reductase (RR) and thus follows Michaelis-Menton kinetics with respect to the riboflavin concentration. The half-velocity constant (Km) was very low (6.3 μmol l-1), indicating a high affinity of the sludge RR for riboflavin. Both Vdirect and Vmediated were found to be proportional to the assay sludge concentration. The results taken as a whole indicate that vitamin levels of riboflavin can be utilized to improve the kinetics of azo dye reduction during anaerobic treatment.
Workshop 7 (synthesis): integrating the water and energy sectors
Authors: Hagebro C. , Cederwall K.
Published: May 2018

Integration of the water and energy sectors is a key issue for effective resource management. However, everything that seems to make sense cannot always be easily accomplished. Barriers are ultimately related to political will where a variety of "instruments" is needed to make such coordination effective.
Impact of temperature on performance, microbiological, and hydrodynamic aspects of UASB reactors treating municipal wastewater
Authors: Singh K.S. , Viraraghavan T.
Published: May 2018

The present study examined the feasibility of treating municipal wastewater by a UASB system under low-temperature conditions. Two reactors were started-up at 20°C and subsequently operated at temperatures of 32, 20, 15, 11, and 6°C applying several hydraulic retention times (HRTs) ranging from 48 to 3 h during an operational period of approximately 900 days. Chemical oxygen demand (COD) removal efficiency ranged from 70 to 90% up to an HRT of 6 h and 11°C. The performance of the reactor was not very satisfactory during 6°C operation (average COD removal 40%). Sulfate reduction played an important role in COD reduction. Digital image analysis and scanning electron microscopic observations of sludge samples revealed aggregation of biomass in the form of irregular shaped granules (mean size ranged from 1.5 to 3.0 mm). The hydraulic regime in the reactor was impacted by the change in operating temperature. This study demonstrated that the UASB system could be applied successfully for pre-treatment/treatment of municipal wastewater under low-temperature conditions.
Effect of aluminium and sulphate on anaerobic digestion of sludge from wastewater enhanced primary treatment
Authors: Cabirol N. , Barragán E.J. , Durán A. , Noyola A.
Published: May 2018

The combined and individual effects of aluminium and sulphate at concentrations of 1,000 mg/l as Al(OH)3, and 150 mgSO42-/L as K2SO4, respectively, on the anaerobic digestion of sludge from enhanced primary treatment (EPT) were evaluated in 1 L capacity semi continuous reactors. It was found that at 59 days, aluminium inhibits the specific methanogenic activity (SMA) of methanogenic and acetogenic bacteria resulting in a 50% to 72% decrease. Sulphate also inhibits (48% to 65%) the SMA of the same type of bacteria. Methanogenic and acetogenic bacteria were able to adapt, to a different extent, to the assayed concentrations of aluminium and sulphate. However, the combination of aluminium and sulphate resulted in a higher inhibition, especially of the hydrogenophilic methanogenic bacteria. Indeed, this effect remained during the time of the experiment, maintaining an inhibition of 44% at 114 days. Feeding with EPT sludge led to a bigger decrease in SMA of each bacterial group, with respect to the other treatments with time. It is concluded that the acidification of anaerobic reactors fed with EPT sludge is due, among other causes, to the concurrent presence of aluminium and sulphate.
Hydrotechnical facilities within the Chernobyl nuclear power plant exclusion zone: impacts on hydrologic regime and plant growth patterns of floodplain water bodies of the Pripyat River
Authors: Gudkov D.I. , Zub L.N. , Savitsky A.L.
Published: May 2018

As result of the Chernobyl nuclear power plant accident the territory of the left-bank flood-lands of the Pripyat River have undergone intensive radionuclide contamination. With the purpose of preventing the washing away of radioactive substances, a complex of flood protection dams was constructed. This construction changed the hydrological regime of these territories and caused overgrowth by higher aquatic plants. Absence of a flowing mode of reservoirs, the stagnant phenomena during spring and seasonal high waters on the embank site have caused amplification of eutrophication processes, swamping and, connected with it, increase of water-marsh floristic complex in the structure of the vegetative cover.
Pollutant sources investigation and remedial strategies development for the Kaoping River Basin, Taiwan
Authors: Kao C.M. , Wu F.C. , Chen K.F. , Lin T.F. , Yen Y.E. , Chiang P.C.
Published: May 2018

The Kaoping River Basin, located in southern Taiwan, flows through approximately 171 km and drains towards the South Taiwan Strait. It is the largest and the most intensively used river basin in Taiwan. Based on the results from the pollutant sources investigation and water quality analysis, the main water pollution sources of the Kaoping River were livestock wastewater from hog farms, municipal wastewater, industrial wastewater, leachate from riverbank landfills, and non-point source (NPS) pollutants from agricultural areas in the upper catchment. Concern about the deteriorating condition of the river led the Government of Taiwan to amend the relevant legislation and strengthen the enforcement of the discharge regulations to effectively manage the river and control the pollution. The following remedial strategies have been taken to improve the river water quality since 2001: (1) hog ban in the upper catchment of the Kaoping River Basin, thus, 510 thousand hogs have been removed/relocated; (2) removal of riverbank landfills; (3) enforcement of the industrial wastewater discharge standards; (4) sewer system construction in five cities along the river corridor; (5) application of best management practices for NPS pollutant control; (6) application of natural wastewater treatment systems (e.g. land treatment, constructed wetland, overland flow, riverbank sedimentation/aeration pond) for domestic wastewater treatment in rural areas; and (7) construction of the watershed geographical information system (GIS) and real time water quality monitoring system to effectively monitor and manage the watershed. Recent water quality investigation results indicate that the biochemical oxygen demand (BOD) and nutrient loadings to the Kaoping River have been significantly reduced and the water quality has been improved after the implementation of the remedial strategies described above. Results and experience obtained from this study will be helpful in designing the watershed management strategies for other similar river basins.
An introduction of co-management approach into Babon River management in Semarang, Central Java, Indonesia
Authors: Susilowati I. , Budiati L.
Published: May 2018

The Babon River lies over three regions, i.e. Semarang District where the upstream is located while downstream it passes through Semarang Municipality and Demak District. This river has been used for many purposes by the neighbouring communities (e.g. water source, canal disposal, mining, etc). Thereafter many transboundary environmental problems have arisen here. The environmental management strategy (using a top-down approach) such as Program Kali Bersih (Clean River Program) on Babon River, which had been implemented by the Bapedalda of Semarang Municipality, is not successfully achieving the targets. In the past, most policies were formulated based on top-down orientation. Hence, the communitiesÕ participation was not paid enough attention. Co-management is a participative-management approach to empower the stakeholders (related parties) to achieve a certain goal. This study seeks answers to the research questions: (1) whether the co-management approach has good prospects for managing the Babon River; and (2) what kinds of strategy should be formulated to empower the stakeholders to manage the Babon River in the study area.

The study employed a multistage sampling method to select the location of the study areas and key-persons sample. Rowosari, Penggaron Kidul and Karangtoro were selected to represent the upstream, middle stream and downstream areas, respectively. The descriptive statistics method had been used to describe the significance of river resource attributesÕ characters. Institutional analysis approach, introduced by Pomeroy and Williams, was adopted with necessary modification in this study.

The results showed that the level of participation of the community in the three segments of the Babon River is different. The prospects for the co-management approach to manage the river resource in the study area are fairly good and in the upstream area are better than in the other two segments. The level of participation is far from complete; nevertheless the response from society towards development is quite good. There are five significant attributes in Babon River, which affect the community participation in river management, namely: (1) intensity of resource commercialisation; formal education of the community; and dependency of the community toward the resources, resource products distribution and resource damage. These variables could influence the pattern of participation of the community in the study area. The other stakeholders such as industrial or plant owners, academics, and the related institutions have not been explored in detail in this study.

The co-management model that has been developed in this study has the prospect of encouraging the community and other stakeholdersÕ empowerment in economic activities, natural resource conservation, and environmental law enforcement, as part of achieving the ultimate goal of sustainable environmental management.