bluuebunny/crossref_metadata_2025 huggingface dataset:
Operation of full-scale fluidized bed for denitrification
Authors: Bosander J. , Westlund Å.D.
Published: May 2018

The SYVAB company has extended the plant with a fluidized bed for post denitrification. The method was chosen mainly for two reasons. First, the relatively low investment cost and second, the flexibility in the process to adjust the discharged nitrogen according to the circumstances in the recipient. Start-up took place in April 1997 with an adaption period of four weeks. From mid September the same year the plant has been in full denitrifying operation. The average nitrate-nitrogen reduction rate has been 90% with 1.9 mg NO3–N in the outlet. Methanol is used as external carbon source. At the present purification rate the cost for total nitrogen reduction is 18 SEK (2.25 USD)/kg N.
Effects of humus soil on the settling and dewatering characteristics of activated sludge
Authors: Choi Y. G. , Chung T. H.
Published: May 2018

Effects of humus soil on the settling and dewatering characteristics of the activated sludge were investigated. Addition of the humus soil improved the sedimentation characteristics of the activated sludge remarkably. The initial lag phase was diminished and the zone settling velocity increased as the humus soil dosage increased. For estimation of the chemical effect of the humus soil on sludge settling, cation mixtures equivalent to the cations leaching from the humus soil were added and only the chemical effect was examined. The physical effect was then isolated by subtracting the chemical effect. The chemical effect on sludge settling was about30∼50% of the equivalent humus soil powder dosage and the physical effect was more important in improvement of the sludge settling properties. Dewatering characteristics of the activated sludge were dependent on both the concentration and distribution of the cations leaching from the humus soil. Divalent cations, calcium and magnesium from the humus soil decreased the bound water content of the sludge, which in turn increased floc density and cake solids content. However, excess sodium ion increased the SRF (specific resistance to filtration) slightly. Addition of humus soil to thickened activated sludge improved the dewatering properties, which could be well explained by the effect of the cations leaching. The SRF showed a good trend with the monovalent to divalent cation (M/D) ratio, which could be utilized as a useful tool for evaluation of the sludge dewatering characteristics.
Renovation of the WWTP of Bruges
Authors: Boonen I. , Bruynooghe H. , Carrette R. , Bixio D. , Ockier P.
Published: May 2018

For meeting the EU standards existing installations have to be upgraded to nutrient removal (nitrogen and phosphorus). One of these installations is the WWTP of the city of Bruges. In the process design phase of the WWTP a pilot study and dynamic modelling are used to optimise the dimensions of the different tanks. To minimise the load overflowing in the collector system it is decided to increase the maximum flow through the WWTP using a storm water regime in the aeration tank.
Production of biopesticides as a novel method of wastewater sludge utilization/disposal
Authors: Sachdeva V. , Tyagi R. D. , Valéro J. R.
Published: May 2018

Production of Bacillus thuringiensis (Bt) var. kurstaki HD-1, an industrially produced biopesticide source, was tested as a potential method to valorize wastewater treatment sludge. The effects of sludge solids concentration and inoculum size were verified on the production of Bt. Inoculum sizes of 1% and 5% were tested. The cell and spore counts achieved were comparable to those in the industry standard. Sludge with 1% (v/v) inoculum size gave higher entomotoxicity compared to that of 5% inoculum. It was observed that sludge samples with lower solids concentration gave marginally lower cell and spore count but gave considerably higher toxicity. The production time was also comparable to the industrial standard. Results from these experiments and their economical implications are discussed in this paper.
Minimizing of foaming in digesters by pre-treatment of the surplus-sludge
Authors: Barjenbruch M. , Hoffmann H. , Kopplow O. , Tränckner J.
Published: May 2018

Several reasons can lead to the emergence of foam in digesting tanks, for instance overloading or the impact of hydrophobic substances. Furthermore, the foaming is in regular periods going together with the emergence of filamentous microorganisms. Up to now, several strategies to avoid foaming have been tested out (for instance reduction of the sludge load in the activated sludge stage, lowering of the sludge level in the digestion tank, dosage of anti foaming agents), but these have been done relatively unsystematically and with more or less success. For our contribution, laboratory-scale digestion tests were run to analyse mechanical and thermal pre-treatment methods for the destruction of the surplus sludge. Whereas the disintegration by a high pressure homogeniser did only achieve a low reduction of the foam phase, the thermal pre-treatment at 121°C made for an effective subduing of the foam emergence. Both methods allowed for a cutting up of the filaments, but only the heating up effected the reduction of the hydrophobic substances; thus, the foaming is possibly caused by them.
Advanced compact wastewater treatment based on coagulation and moving bed biofilm processes
Authors: Ødegaard H.
Published: May 2018

Advanced compact wastewater treatment processes are being looked for by cities all over the world as effluent standards are becoming more stringent and land available for treatment plants more scarce. In this paper it is demonstrated that a very substantial portion of the pollutants in municipal wastewater appears as particulate and colloidal matter. Pre-coagulation, therefore, gives very efficient pre-treatment that results in considerable saving in the total space required by the plant, especially when combined with a biofilm process for the removal of the soluble matter. A new biofilm process for this purpose is described. The moving bed biofilm process is based on plastic carriers, that move in the reactor, on which biomass attach and grow. The carriers are kept withinthe reactor by a sieve arrangement and biomass that is sloughing off the carriers is separated before effluent discharge. In addition to combining the moving bed biofilm process with pre-coagulation, the paper discusses also the use of a high-rate moving bed process combined with coagulation directly after the biofilm reactor in order to enhance separability. This results in very compact treatment plants for secondary treatment and possibly phosphate removal.
Novel biological removal of hazardous chemicals at trace levels
Authors: McCarty P.L.
Published: May 2018

Of recent concern is the removal of toxic compounds in wastewaters, soils, and groundwater to concentrations in the low microgram per litre level or less. Threshold limits to bioremediation exist and must be considered in biological treatment schemes to achieve such limits. These limits may be related to reaction kinetics or thermodynamics. Techniques for removing compounds below threshold levels exist that rely on appropriate approaches such as plug flow treatment. Novel biological methods exist for removal of refractory contaminants to low levels. Examples are provided for removal of trace levels of chlorinated solvents, such as tetrachloroethene (PCE) and trichloroethene (TCE), that employ dehalorespiration under anaerobic conditions or cometabolism under aerobic conditions. These approaches are currently being used in engineered systems or through natural attenuation for remediation of soils and groundwater. Successful results offer insights for similar removals of trace chemicals in both aerobic and anaerobic biological systems for treatment of wastewaters and sanitary landfills.
Biotreatment of persistent substances using effective microorganisms
Authors: Fujita M. , Ike M. , Kawagoshi Y. , Miyata N.
Published: May 2018

To efficiently biotreat the persistent substances contained in wastewater, it is necessary to fully elucidate the degradation mechanisms of the substances by specific degrading microorganisms. Especially clarifying the enzymatic reactions responsible for the degradation of persistent substances is very important. Here three different kinds of aerobic or oxidative degradation reactions of persistent substances are introduced. Polyvinyl alcohol (PVA) degradation by Pseudomonas vesicularis var. povalolyticus strain PH, co-oxidative degradation of trichloroethylene (TCE) by a variety of phenol degrading bacteria, and decolorization of melanoidin by a white rot fungus Coriolus hirsutus were shown.
Denitrification of greenhouse leachates in an upflow sludge blanket reactor
Authors: Tarre S. , Moshe A. , Green M.
Published: May 2018

Biological denitrification of greenhouse leachates was investigated in laboratory scale upflow sludge blanket (USB) reactors. Two simulative solutions, representing greenhouse leachates at “high concentration” (200 mg/L NO3––N and 140 mg/L PO43–) and “low concentration” (120 mg/L NO3––N and 15 mg/L PO43–) ranges were used in the experiments. Ethanol was added as the carbon and electron source for bacterial metabolism. The USB reactor successfully removed 99% of the nitrate at retention times from 1 hour to 10 minutes. Nitrogen removal rates reached 16.7 g NO3––N/L · d for the “low concentration” reactor and 26.8 g NO3––N/L · d for the “high concentration” reactor. Due to the large increase in alkalinity resulting from the denitrification, precipitation of calcium compounds occurred which resulted in sludge with good settling characteristics (SVI=6.5 to 8 ml/g). The mineral fraction of the granular sludge was higher than 50%. High concentrations of biomass (100g/L TSS and 40 g/L VSS) were also observed. From the mineral analysis of the granular sludge, the main precipitating compound in the “low concentration” reactor was identified as calcium carbonate. In the “high concentration” reactor, the mineral analysis did not give a clear answer as to the composition of the precipitating compound. Using theoretical Ksp values together with the remaining soluble concentrations of calcium, phosphate and pH in the effluent, amorphous Ca3(PO4)2 was suggested as the main precipitating compound. The calcium phosphate rich sludge was shown to be unstable and dissolved when the influent concentrations were changed. Modeling the biological and chemical processes in the reactor was done using AQUASIM modified to include chemical systems. When experimental Ksp values were used, the model gave good agreement with reactor results.
The characteristics of nitrogen removal by the biofilter system
Authors: Ouyang C.F. , Chiou R.J. , Lin C.T.
Published: May 2018

Previous research has shown that nitrogen from municipal wastewater could be eliminated by a biofilter system. In this study a system of combined pre-denitrification/nitrification biofilters was set up. It is to investigate the effect of the hydraulic loading and recycled ratio on nitrogen removal. The characteristics of bacterial activity at different heights is discussed. The experiment shows that longer hydraulic loading would result in better total nitrogen removal. Total nitrogen removal might be not dependent on denitrification but nitrification. Hydraulic loading that affects nitrification might be due to the diffusion of NH3–N from the bulk solution to the inner biofilm. The recycling NO3–N could be completely eliminated in the anoxic biofilter. The operation with longer retention time (HRT of 12 hours) would result in inner denitrification in the aerobic biofilter. Biological activity could be determined by the distribution of bacteria. The specific rates of pollutant decomposition depend on biological activity and effective biological VSS. The effect of the recycled ratio on the nitrogen removal is significant. Total nitrogen removal rate and nitrogen type of effluent would be determined by recycle ratio. The operation at low recycled ratio would result in worse total nitrogen removal, but the NH3–N of effluent would be lower. The operation in higher recycle ratio would be opposite to low recycle ratio.
Modelling of anaerobic digestion using self-organizing maps and artificial neural networks
Authors: Holubar P. , Zani L. , Hagar M. , Fröschl W. , Radak Z. , Braun R.
Published: May 2018

In this work the training of a self-organizing map and a feed-forward back-propagation neural network was made. The aim was to model the anaerobic digestion process. To produce data for the training of the neural nets an anaerobic digester was operated at steady state and disturbed by pulsing the organic loading rate. Measured parameters were: gas composition, gas production rate, volatile fatty acid concentration, pH, redox potential, volatile suspended solids and chemical oxygen demand of feed and effluent. It could be shown that both types of self-learning networks in principle could be used to model the process of anaerobic digestion. Using the unsupervised Kohonen self-organizing map, the model's predictions could not follow the measurements in all details. This resulted in an unsatisfactory regression coefficient of R2= 0.69 for the gas composition and R2= 0.76 for the gas production rate. When the supervised FFBP neural net was used the training resulted in more precise predictions. The regression coefficient was found to be R2= 0.74 for the gas composition and R2== 0.92 for the gas production rate.
Estrogen and estrogen mimics contamination in water and the role of sewage treatment
Authors: Matsui S. , Takigami H. , Matsuda T. , Taniguchi N. , Adachi J. , Kawami H. , Shimizu Y.
Published: May 2018

The yeast estrogen screen was applied to sewage treatment process waters to identify the presence of estrogenic activity and to investigate the fate and behavior of estrogenic substances through treatment. Hydrophobic fractions in the water phase were extracted and concentrated using C18 cartridges for the effective extraction of 17β-estradiol (E2) and other estrogen mimics. Clear dose-dependent elevation in the synthesis of β-galactosidase in the yeast screen was observed with all the samples tested, demonstrating that these samples were estrogenic. However, estrogenic activity tended to reduce during the treatment, especiallyiin the biological process. Quantification results of the yeast estrogen screen in terms of E2 equivalent were compared with actual E2 concentrations measured by an ELISA. E2 occupied 34% of the whole estrogenicity in the raw sewage, while almost 100% in the final effluent. The analyses of the sewage treatment process waters revealed that human estrogens are major causative substances in terms of estrogenic activity in sewage and its treated effluent. Although findings of possible correlation of environmental estrogens with the real impact on human health and the ecosystem are still the focus of scientific debate and investigation, proper management should be established in the sewage treatment process which receives various environmental contaminants.
Integrated mechanical, biological and physico-chemical treatment of liquid manure streams
Authors: Kalyuzhnyi S. , Sklyar V. , Rodriguez-Martinez J. , Archipchenko I. , Barboulina I. , Orlova O. , Epov A. , Nekrasova V. , Nozhevnikova A. , Kovalev A. , Derikx P. , Klapwijk A.
Published: May 2018

The results obtained during the first year of execution of a joint Russian-Dutch project “The development of integrated anaerobic-aerobic treatment of liquid manure streams with maximisation of production of valuable by-products (fertilisers, biogas) and re-utilisation of water” (1999–2001) are discussed. The application of a straw filter was an effective means to separate the solid and liquid fractions of diluted pig manure wastewater and resulted in the removal of a significant part of the dry matter, total nitrogen and phosphorus (65, 27 and 32%, respectively). From the filtrate generated, 60–80 % of the COD was removed in a UASB reactor operating at 20–30°C. Up to 66% of phosphate was precipitated after air stripping of the CO2 from the anaerobic effluents. Ammonia was efficiently removed (>99%) from the anaerobic effluents using zeolite (Ural laumantite) as an ion exchanger. However, the N-content of the resulting zeolite was too low to be used as a fertiliser. A feasible alternative for nitrogen elimination involved nitrification of the anaerobic effluent followed by denitrification in a UASB reactor using the COD of the filtrated manure wastewater as carbon source.
Flow characterization in a gas-liquid column: application to a bioscrubber for the deodorization of waste gases
Authors: Humeau P. , Baléo J.-N. , Raynaud F. , Bourcier J. , Le Cloirec P.
Published: May 2018

The flow pattern of a countercurrent gas-liquid packed column is characterized for gas and liquid phases. Three packing materials are used (10 mm ceramic Raschig rings, 16 mm polypropylene Pall rings and 45 mm×18 mm polypropylene Spiralpac) and various operating conditions are applied. A first approach consists in the study of pressure drops. On the one hand, this study enables to determine, using the Ergun relation, the representative parameters of the three packing materials towards the flow. On the other hand, a study in a three-phase system is performed to establish the limit conditions using the Eckert model (flooding point, conditions of minimum wetting rate). An investigation of residence time distribution allows the hydrodynamic parameters to be obtained for each phase. A dispersion model represents the gas flow. The tanks-in-series with mass exchange model is retained for the washing solution flow representation. The influence of operating conditions on hydrodynamic parameters is evaluated. The determination of these parameters is of great interest to scale up and optimize the biological system of deodorization.
Comparison between sucrose, ethanol and methanol as carbon and energy sources for biological sulphate reduction
Authors: Greben H. A. , Maree J. P. , Mnqanqeni S.
Published: May 2018

Sulphate was reduced via sulphide to sulphur when operating a single-stage completely mixed reactor configuration feeding synthetic feed. The aim of this study was to determine the volumetric and specific sulphate reduction rates using sugar, ethanol and methanol as a carbon and energy sources. The presented results indicated that sugar and ethanol were found to be suitable carbon and energy sources resulting in a volumetric and a specific sulphate reduction rate of 10.4 and 4.8 g SO4/(l.d) and 0.8 and 2.8 g SO4/(gVSS.d), respectively, at a Hydraulic Retention Time (HRT) of 3.6 h and at ambient temperature (21°C). Methanol induced methanogenesis rather than sulphidogenesis. The experimental sulphide/sulphate ratio was consistently lower than the theoretical value which indicated that part of the formed sulphide was oxidized to sulphur.
The geohydrology and water quality of the springs and wells of the western catchment to the Dead Sea, West Bank, Palestine
Authors: Abed Rabbo A.
Published: May 2018

This study is based on the analysis of water samples collected on a seasonal basis from the wells and springs of the southern basins of the Mountain Aquifer. The Herodion-Beit Fajjar well field is located near the main recharge area between Bethlehem and Hebron. The springs discharge from perched aquifers, or discharge directly into the Dead Sea. The analyses of the samples collected indicate three major water types: calcium carbonate water, calcium-sodium bicarbonate water, sodium chloride water; attributed to the geochemical dissolution and ion exchange processes and to mixing with wastewater. A large number of the samples are contaminated with fecal coliform and therefore unsuitable for drinking without proper disinfection. Most samples range between hard and very hard water indicating high concentrations of calcium and bicarbonte. Some of the samples exceed the nitrates limits of the WHO (1995) and a few exceed the potassium limits, indicating pollution and mixing with wastewater. Chemical treatment is required in order to bring such water up to acceptable drinking water standards. The samples registered a low sodicity and a high salinity hazard. This type of water should be limited and controlled in order to mitigate the possible negative effects on both the soil and the cultivation of plants.
Cost assessment of averting groundwater pollution
Authors: Haruvy N. , Hadas A. , Ravina I. , Shalhevet S.
Published: May 2018

Modern agriculture serves as a source for groundwater pollution caused by nitrate leaching carried downward by seepage of excess water. Farmers do not usually consider these environmental hazards in their decision-making unless forced to by market or administrative measures. We compare the possibilities open to individual farmers and to the state, assess consequent environmental hazards to groundwater, and suggest appropriate measures to control them. Estimation is based on an optimization model applied to the central area of Israel located above the coastal aquifer.
Pilot plant for reclaimed wastewater reuse in nurseries
Authors: Gori R. , Lubello C.
Published: May 2018

In this paper, after a brief introduction on irrigation wastewater reuse, we take a closer look at Pistoia, the most important nursery area in Italy, which specializes in production of woody ornamental plants. Groundwater resources are used for irrigation in competition with urban use, causing serious shortage problems in summer. Treated municipal wastewater can be a good alternative source of water and fertilizer nutrients for ornamental plant production. During 1998, we carried out an experiment along with local corporate bodies to evaluate the effects of Pistoia's wastewater treatment plant (WWTP) effluent irrigation of the (Pistoia) area – compared with traditional well water irrigation – on three container-grown species, each of them characterized by different growth habits. Plants irrigated with the effluent, treated with UV irradiation in a disinfection pilot plant, showed better physiological and growth parameters than those irrigated with traditional well water.
Portuguese–Spanish river basins: bilateral agreements' evolution and context
Authors: Maia R.
Published: May 2018

The main aim of the Portuguese–Spanish active bilateral international rivers Conventions (1964 and 1968) was to rule on the sharing of water and hydroelectric potential production of bordering river stretches. The new “Convention on Cooperation for Portuguese–Spanish River Basins Protection and Sustainable Use”, signed by the two governments but still to be ratified, envisages co-ordinating efforts on shared river basins management, aiming to attain improved risk prevention and ecosystem protection on those basins, respecting modern principles of international law. An analysis of the new Portuguese–Spanish Convention will be presented, bearing in mind international and European Union law and principles, namely the European Union Water Framework Directive Proposal. Different issues such as water resources development, protection and management of the Portuguese–Spanish river basins, including an envisaged flow regime definition, will be analysed, always according to the legal and political paradigms.
A proposal for sustainable groundwater management as influenced by a pyramid of social needs: the case of Israel's coastal aquifer
Authors: Melloul A. J. , Collin M. L.
Published: May 2018

The psychologist Abraham Maslow developed a pyramid of human social needs. A comparable pyramidal hierarchy of groundwater needs can be envisaged. In the pyramid of social needs, until lower level needs are fulfilled, higher level needs remain irrelevant to people. Analogously, only once a society's basic groundwater concerns are fulfilled can groundwater management decision-makers hope to press onwards towards an ultimate goal of attaining sustainable groundwater resources development. Groundwater resources of the Sharon region of Israel's coastal aquifer can be taken as a case in point. To effectively carry out management recommendations for achieving sustainable groundwater development, technical concerns must be integrated with social concerns. Alignment between comparable levels of the pyramids of social and groundwater needs can only be achieved by educating the society to perceive the significance of sustainable resource development for future generations. Only then will the society be fully prepared to pay the price for such development and to participate in the long-term environmental planning required.
Approximate analysis of the containment of contaminated sites prior to remediation
Authors: Rubin H. , Rabideau A.
Published: May 2018

This study presents an approximate analytical model, which can be useful for the prediction and requirement of vertical barrier efficiencies. A previous study by the authors has indicated that a single dimensionless parameter determines the performance of a vertical barrier. This parameter is termed the barrier Peclet number. The evaluation of barrier performance concerns operation under steady state conditions, as well as estimates of unsteady state conditions and calculation of the time period requires arriving at steady state conditions. This study refers to high values of the barrier Peclet number. The modeling approach refers to the development of several types of boundary layers. Comparisons were made between simulation results of the present study and some analytical and numerical results. These comparisons indicate that the models developed in this study could be useful in the design and prediction of the performance of vertical barriers operating under conditions of high values of the barrier Peclet number.
Environmental quality and national security
Authors: Soffer A.
Published: May 2018

This article defines national security and environmental quality, points to the developing connection between the two, and uses the case of Israel to illustrate this link. The following matters have to be learned about national security as well as world security – rainfall and water table levels as predictors of famine and the collapse of governments, or the spread of the Sahara Desert as a predictor that ethnic strife will result. Failure to halt the deterioration of ecological systems threatens national security and human survival as a whole. There are disasters that are immediate, but most of them do not constitute a threat to the national security of states, the exceptions are nuclear threat as in the Chernobyl case, or droughts and flooding. There are disasters that are felt only in the medium term, like climatic changes and they can endanger entire states, thus weakening national security.
Membrane for water reuse: effect of pre-coagulation on fouling and selectivity
Authors: Soffer Y. , Ben Aim R. , Adin A.
Published: May 2018

Membrane filtration is adequate for producing disinfected clear water suitable for various kinds of applications. However, fouling of membranes is the main limitation. This study has focused on the ability of flocculation to remove from wastewater the organic colloids which play an important role in the fouling phenomena. First, flocculation was optimized for high-efficiency removal of suspended solids and organic material, and then, at a selected ferric chloride dose and pH, was used as a first step before filtration on membranes ranging from UF (50 KDa) to NF. This resulted in an improvement of the filtration flux. Fouling increased when high molecular weight cut-off (MWCO) membranes were used. The foulingmechanism seems to be blocking, by internal clogging and cake formation becoming preponderant with time. pH 5.5 (charge neutralization zone) provided better removal and lower fouling intensity than pH 7.8 (sweep coagulation zone). Ultrafiltration of 4 KDa at acidic pH 5.5 and 150 mg/L ferric chloride could reduce DOC by 70% and UV-254 nm by 60%. The quality of the filtrate was better than that obtained with nanofiltration at basic pH 7.8 with the same dose of flocculant and the fouling was lower with a 4 KDa membrane. Thus coupling of flocculation with a UF membrane might be the best compromise for producing, in very compact units, very clear water for possible reuse in industrial areas.
Biofiltering action on hydrogen sulfide by unmodified activated carbon in sewage treatment plants
Authors: Bandosz T. , Askew S. , Kelly W.R. , Bagreev A. , Adib F. , Turk A.
Published: May 2018

Because effluents to atmosphere from sewage treatment typically include hydrogen sulfide (H2S) among other malodors, and because H2S is a light gas, it is commonly assumed that unmodified (“virgin”) activated carbon, which acts largely by physical adsorption, is inadequate for such applications. Instead, caustic-impregnated and other modified carbons have been used in the U.S.A., Europe, and Israel for odor control where H2S is an expected airborne component.

Our laboratory and full-scale comparative studies question this assumption and practice, and strongly support the advantages of virgin over impregnated or other special carbons for control of H2S as well as for general odor removal. In this report, we suggest that biofiltration in the carbon bed helps achieve such favorable outcomes.
Understanding anaerobic decolourisation of textile dye wastewater: mechanism and kinetics
Authors: Willetts J.R.M. , Ashbolt N.J.
Published: May 2018

Worldwide, some 280,000 tons of textile dyes are discharged per annum. Degradation of the predominant highly soluble reactive dyes is poor within activated sludge plants, and instead requires anaerobic pretreatment for reductive cleavage of the chromogenic azo bond to precede aerobic degradation. The mechanism for the anaerobic reductive cleavage, which results in decolourisation, is not well understood. Further, thermophilic anaerobic pre-treatment has not been reported, although the wastewater is produced at high temperature (50–80°C). This project therefore aimed to compare decolourisation kinetics under mesophilic (35°C) and thermophilic (55°C) conditions and elucidate biotic and abiotic factors in the decolourisation of the dye, Reactive Red 235.

Preliminary experiments indicated that acclimation of the up-flow anaerobic sludge blanket (UASB) biomass was unnecessary and there was no dye toxicity at expected wastewater concentrations (0.05–0.1g/L). Decolourisation of Reactive Red 235 was studied under batch conditions with intact and autoclaved biomass, and also using the pre-reduced supernatant from a spent culture (0.2 μm filtered). Based on HPLC identification of the dye and reaction products, first-order kinetics was observed and rate constants of –0.0096/min (thermophilic) and –0.0034/min (mesophilic) were estimated for intact, viable biomass. Abiotic decolourisation was 60–80% lower for the autoclaved samples, and under 12–35% lower for the filtered supernatant. Hence it may be concluded that active anaerobic cells give the most efficient and complete decolourisation, especially under thermophilic conditions. Nonetheless, abiotic reduction does occur and has implications for the design of a novel uncoupled reactor system.
Evaluation of the vulnerability of the Western Mountain aquifer to pollution
Authors: Bachmat Y. , Wollman S. H.
Published: May 2018

The paper introduces a preliminary physical measure of vulnerability of groundwater to pollution called “mean relative travel time of a pollutant”, which is defined as the time of passage through the unsaturated zone of a front of water containing a conservative pollutant and applied to the ground surface at a unit intensity of supply. A methodology for mapping the mean relative travel time is presented and applied to the recharge area of the Western Mountain, (Yarkon-Taninim) aquifer. The aquifer, which extends from the mountain range west of the Jordan River to the Mediterranean coast line, is subdivided into a set of 5×5 km2 cells, and a mean relative travel time is computed for each cell within the recharge area of the aquifer. The estimated mean travel times are directly proportional to the depth to groundwater and inversely proportional to the ratio between the coefficient of replenishment and the water content of the unsaturated zone. Estimates of the latter are obtained from regression of the rise in well water levels during the winter season on the corresponding seasonal rainfall depth. They show relative travel times in the range of one decade in the outcrops of the lower subaquifer and along the foothills, and relative travel times in the range of two to three decades along the mountain range outcrops of the upper subaquifer.
Impact of COD/N/S ratio on dentrification by the mixed cultures of sulfate reducing bacteria and sulfur denitrifying bacteria
Authors: Kim I.S. , Son J.-H.
Published: May 2018

This study proposed a new process, which can carry out denitrification and removal of organics simultaneously in the absence of an external carbon source or in a low COD/N ratio by taking advantage of the symbiotic relationship between sulfur denitrifying bacteria (SDB) and sulfate-reducing bacteria (SRB). The kinetic and stoichiometric coeficients for nitrate removal by SDB were as follows :k = 0.9 hr-1, Ks = 7 mg NO3-N/L, Y = 0.118 mgVSS/mgNO3-N and Kd = 0.057 hr-1. In the activity tests of the SRB culture, organic matter, acetic acid, was used by the heterotrophic denitrifying bacteria (HDB) as an electron donor in the denitrification reactions. When below the theoretical COD/N ratio, the formation of nitrogen gas did not occur because of nitrite accumulation. In the mixed cultures of SDB and SRB, most denitrification reactions were accomplished by SDB using the reduced sulfur compounds as a sulfur source for the removal of the nitrate. Denitrification was completed within 6 hours in all batch reactors with 60% of the produced gas being nitrogen. The rate of denitrification was unaffected by the COD/N ratios. However, the degradation rate of the organic matter was very low.
Formulating biossay data of chemicals and environmental water
Authors: Shoji R. , Sakoda A. , Sakai Y. , Suzuki M.
Published: May 2018

The quality of environmental waters such as rivers is often deteriorated by various kinds of trace and unidentified chemicals despite the recent development of sewage systems and wastewater treatment technologies. In addition to contamination by particular toxicants, complex toxicity due to multi-component chemicals could be much more serious. The environmental situation in bodies of water in Japan led us to apply bioassays for monitoring the water quality of environmental waters in order to express the direct and potential toxicity to human beings and ecosystems rather than determinating concentrations of particular chemicals. However, problems arose from the fact that bioassays for pharmaceutical purposes generally required complicated, time-consuming, expert procedures. Also, a methodology for feedback of the resultant toxicity data to water environment management has not been established yet. To this end, we developed a novel bioassay based on the low-density lipoprotein (LDL) uptake activity of human hepatoblastoma cells. The assay enabled us to directly detect the toxicity of environmental waters within 4 hours of exposure. This is a significantly quick and easy procedure as compared to that of conventional bioassays. The toxicity data for 255 selected chemicals and environmental waters obtained by this method were organized by a mathematical equation in order to make those data much more effectively and practically useful to the management of environmental waters. Our methodology represents a promising example of applying bioassays to monitor environmental water quality and generating potential solutions to the toxicity problems encountered.
Electrochemically reductive dechlorination of chlorophenol using nickel and zinc electrodes
Authors: Lin C.H. , Tseng S.K.
Published: May 2018

Electrochemically reductive dechlorination of chlorophenols on zinc and nickel electrodes in propylene carbonate solvent is investigated. The reductive dechlorination of a variety of chlorophenols on the zinc electrode occurred at different potentials. For pentachlorophenol, two reductions were found at −2.4 V and −1.7 V. Two reductions were also found at −2.7 V and −1.95 V for 2,3,4,6-tetrachlorophenol. Only one reduction was found for 2,4,5-trichlorophenol, 2,4-dichlorophenol and 2-chlorophenol, it was observed at −2.2 V, −2.35 V and −2.5 V respectively. The electrolysis of controlled potential was held at −2.7 V. 2,3,4,6-tetrachlorophenol was dechlorinated and trichlorophenols and dichlorophenols were the major intermediate products. 2-chlorophenol was also dechlorinated at the potential of −2.7 V. The result shows chlorophenols can completely dechlorinate on the zinc cathode.
Effect of dissolved organic carbon on leaching of copper and zinc from swine manure compost
Authors: Hsu J.-H. , Lo S.-L.
Published: May 2018

Swine manure was comprehensively characterized with respect to Cu and Zn due to feed additives. Separated swine manure (SSM) composts were collected from five pig farms at Tainan County. The total content, base extractability, synthetic acid rainwater (SAR) solubility, and leachability at varying pH of Cu and Zn were determined to assess its environmental hazard. The influence of dissolved organic carbon (DOC) from compost on leaching of these elements was evaluated. The SSM composts were enriched with Cu (208-1380 mg/kg) and Zn (847-2840 mg/kg). The SAR and neutral pH leachable fractions of Cu, Zn, and organic C were generally low (< 6% of their total content). Copper leachability in F2 compost, however, was high (14%), resulting from immaturity and associated substantial dissolution of organic C (11%). Most of Cu (86% on average) while small portion of Zn (14% on average) were distributed on humic substances (HS) which comprised about 40% of total compost organic C. Extracted Cu increased rapidlyand was highly correlated to the increase of organic C concentration as the pH raised above pH 8, while extracted Zn remained low. High leachability of Cu at alkaline pH and during HS extraction was due at least in part to complexation with DOC.
Non-steady variations of SOD and phosphate release rate due to changes in the quality of the overlying water
Authors: Inoue T. , Nakamura Y. , Adachi Y.
Published: May 2018

A dynamic model, which predicts non-steady variations in the sediment oxygen demand (SOD) and phosphate release rate, has been designed. This theoretical model consists of three diffusion equations with biochemical reactions for dissolved oxygen (DO), phosphate and ferrous iron. According to this model, step changes in the DO concentration and flow velocity produce drastic changes in the SOD and phosphate release rate within 10 minutes. The vigorous response of the SOD and phosphate release rate is caused by the difference in the time scale of diffusion in the water boundary layer and that of the biochemical reactions in the sediment. Secondly, a negative phosphate transfer from water to sediment can even occur under aerobic conditions. This is caused by the decrease in phosphate concentration in the aerobic layer due to adsorption.
Biological treatment of highly foaming pharmaceutical wastewater by modified bubble-column under mechanical foam control
Authors: Yamagiwa K. , Yoshida M. , Ohkawa A. , Takesono S.
Published: May 2018

Activated sludge treatment of highly foaming pharmaceutical wastewater was carried out with modified bubble columns equipped with a mechanical foam-breaker (MFRD). The geometry of the bubble column was modified based on the foam breaking mechanism of the MRFD in order to improve the foam breaking capacity and hence to enhance the treatment capacity. Four types of modifications were examined. The activated sludge treatment of the wastewater with the modified columns was successfully carried out with COD removal efficiency about 90% at BOD loading of 4 g/Ld. Little effect of the mechanical foam control on the sludge settling characteristics was observed. The column modification significantly reduced the power required for foam control. The maximum power decrement of 75% was attained. Furthermore, oxygen transfer was found to be facilitated in the modified bubble columns. The results are expected to be helpful for economic and effective treatment of highly foaming organic wastewater.
Pilot testing and preliminary design of moving bed biofilm reactors for nitrogen removal at the FREVAR wastewater treatment plant
Authors: Rusten B. , Hellström B.G. , Hellström F. , Sehested O. , Skjelfoss E. , Svendsen B.
Published: May 2018

A moving bed biofilm reactor (MBBR) pilot plant, using Kaldnes type K1 biofilm carriers, was tested for nitrogen removal at the FREVAR wastewater treatment plant. The pilot plant was fed primary treated municipal wastewater, at temperatures from 4.8 to about 20°C. The results showed that a reasonable design nitrification rate will be 190 g TKN/m3d, at 10°C and a reactor pH≥7.0. Pre-denitrification was very dependent on the concentration of readily biodegradable organic matter and the amount of oxygen in the influent to the first anoxic MBBR. It was found that a MBBR process for nitrogen removal at FREVAR will require a total reactor volume corresponding to an empty bed hydraulic retention time of 4–5 hours at average design influent flow. This was based on an influent concentration of 25 mg total N/l, 70% annual average removal of total N and a treatment process consisting of primary treatment, MBBRs with combined pre- and post-denitrification, and followed by coagulation/flocculation and a final solids separation stage.
Tertiary nitrification in an up flow biofilter on floating media: influence of temperature and COD load
Authors: Payraudeau M. , Paffoni C. , Gousailles M.
Published: May 2018

The wastewater plant Seine Aval (located in Acheres, France) treats 6 million PE (25 m3/s average flow, 570 MGD) with activated sludge. Following a research program called “Azote Acheres” which demonstrated that biofilters are an economical solution, the Paris Metropolitan Area Sewage Service (SIAPP) has tested 3 industrial prototypes during a period of more than 4 years. One of these is an up-flow biofilter using a floating filter bed made of expanded polystyrene beads. This specific process is called BIOSTYR and is used here as a nitrifying tertiary biofilter.

The purpose of this paper is to show that the biofilter process achieves very low, steady state, effluent ammonia concentrations with different applied nitrogen loads (0.3 to 2.7 kg NTK/m3.d), even with low temperature and high applied carbonaceous load.

During this 4 years period, a model has been developed to explain the hydraulic behavior of the filter. By measuring the operating conditions (temperature, loads), the head loss of the filter can be predicted.

After this test period, the prototype has been operated by Seine Aval plant staff. The results obtained have confirmed the previous test results.
Performance of nitrogen removal and biofilm structure of porous gas permeable membrane reactor
Authors: Suzuki Y. , Hatano N. , Ito S. , Ikeda H.
Published: May 2018

A porous gas permeable membrane can supply oxygen effectively, utilizing the high ability of oxygen uptake of nitrifying biofilm. If the membrane with the biofilm is applied to wastewater treatment, simultaneous denitrification occurs, but control of the biofilm thickness is necessary to maintain the high efficiency of the treatment.

In this research, small fluidized cylinders were tested as the media for slough off of excess biofilm, and the performance of nitrogen removal was investigated supplied with municipal wastewater. The results showed that the nitrogen removal efficiency was well kept for a long period with the method tested, especially the nitrification rate in the range of 1.1 to 3.1 gN/(m2 d), and that the biofilm formed a stable structure of double layers, that is, an inner firm nitrifying biofilm and an outer loose denitrifying biofilm.
Control of membrane-attached biofilms in extractive membrane bioreactors
Authors: Nicolella C. , Garcia Appendini I.C. , Zhang S-F. , Livingston A.G.
Published: May 2018

Control of Membrane Attached Biofilm (MAB) formation and accumulation is a key aspect in the operation of Extractive Membrane Bioreactors (EMBs). In this work, MAB control was attempted in a novel EMB configuration which presents two innovative aspects: the presence of a biphasic biomedium and a contained liquid membrane module. This reactor, where the benefits of high shear forces and the use of a biphasic biomedium are effectively combined, was operated without any biofilm formation or reduction in organic substrate flux over time.
Attachment, strength and performance of a porous media in an upflow anaerobic filter treating dairy wastewater
Authors: Ince O. , Kasapgil Ince B. , Donnelly T.
Published: May 2018

Attachment, strength and performance of a porous media in an upflow anaerobic filter (UFAF) treating dairy wastewater were investigated. Microscopic examination showed that the number of autofluorescent methanogens varied 15–28% of the number of total bacteria along the UFAF while the number of viable methanogens was 10–70 times less that of autofluorescent methanogens. The most dominant species was found to be Methanococcus followed by short rods, medium rods, long rods, filaments and Methanosarcina. The quantity of attached biomass was the highest at the bottom, 103 mg VSS/media ring and lowest at the top, 23 mg VSS/media ring and an average of 55 mg VSS/media ring in the mid-height inside the UFAF. An average of 50% reduction in compressive strength of the sintered glass media after 8 months of operation was measured. The UFAF was operated up to an organic loading rate of 21 kg COD/m3·d with a hydraulic retention time of 0.5 day and an average of 80% COD removal efficiency for most of the operating period was achieved.
Polysulfide sulfur in pipewall biofilms: its role in the formation of swampy odour in distribution systems
Authors: Heitz A. , Kagi R.I. , Alexander R.
Published: May 2018

Biofilms and pipewall sediments in drinking water distribution systems were analysed for dimethylpolysulfides (DMPS) and inorganic polysulfides in an effort to determine the origin of dimethyltrisulfide, which causes unpleasant swampy odours in drinking water. Inorganic polysulfides were determined using the technique of methyl iodide derivatisation, and subsequent analysis as DMPS by gas chromatography-mass spectrometry. The technique was shown to be quantitative from 0.15 μg/L to 370 μg/L, and not subject to interference from other sulfur compounds. The polysulfide-rich biofilms and sediments occurred in pipes constructed from a variety of different materials, and fed by water from several different surface and groundwater sources. The biofilm/sediment matrix appeared to retard oxidation of polysulfides, by preventing their diffusion into the oxic water and by providing a barrier against the oxidative action of chlorine and dissolved oxygen.
Impacts of implementing a corrosion control strategy on biofilm growth
Authors: Rompré A. , Prévost M. , Coallier J. , Brisebois P. , Lavoie J.
Published: May 2018

Biofilm growth and corrosion are interrelated processes in a drinking water distribution system. The presence of corrosion tubercles alters the quality of the water in many ways, such as increasing the number of available attachment sites on the walls of the pipes for bacteria. Moreover, the presence of corrosion by-products significantly reduces chlorine disinfection and the efficiency of biofilm control. This study is aimed at evaluating the effect of implementing a corrosion control program on the development of biofilm on distribution system pipe walls. No impacts were found during full-scale experimentation, however the results of a pilot-scale study carried out with annular reactors showed that, both in the presence and absence of corrosion by-products, the anti-corrosion chemicals tested (orthophosphates, a blend of ortho-polyphosphates, and sodium silicates) had no impact on biofilm development at the concentrations tested. Higher numbers of bacteria fixed on the walls of the reactors wereassociated with larger corrosion deposits on the annular reactors. Removing these corrosion deposits may have a positive impact on biofilm control in a distribution system.