bluuebunny/crossref_metadata_2025 huggingface dataset:
Step-feed operation at short detention times – a cost effective method for improving wastewater treatment
Authors: Adamski R.E. , DeSantis V. , Spangel A. , Pynn J. , Betty L. , Koch C.M. , Gyory S.A.
Published: May 2018

The Newtown Creek Water Pollution Control Plant (WPCP) is New York City's largest wastewater treatment plant. Wastewater treatment is provided by a high-rate activated sludge process without primary sedimentation. This process has achieved approximately 65 percent BOD5 and 75 percent TSS removal. As part of a revised facility plan, two alternative tracks were recommended for upgrading the plant to secondary treatment and providing nitrogen removal. One track would require demolishing most of the existing tankage and constructing new primary tanks followed by a step-feed biological nitrogen removal activated sludge process. The second track would preserve the existing high-rate activated sludge process and use biological filters to remove additional TSS, BOD5 and nitrogen. Alternatives have been investigated to enhance treatment at the Newtown Creek WPCP while the secondary treatment plant upgrading is being completed. This investigation demonstrated that simply converting the existing aeration tanks to step-feed operation could significantly improve TSS and BOD removals. These findings have led the City to consider a third track to meet secondary treatment requirements, (but with no nitrogen removal), consisting of modifying the existing plant to step-feed and adding additional step-feed aeration/sedimentation capacity. This track offers significant cost savings over Track 1 and Track 2.
Evaluation of agricultural utilisation of the sludge produced at Psyttalia WWTP
Authors: Mamais D. , Kouzeli A. , Christoulas D. G. , Andreadakis A. , Aftias E.
Published: May 2018

A six-month experimental study was conducted to evaluate the agricultural use of the sludge produced at Psyttalia after completion of secondary biological treatment. Based on the results obtained from a bench scale activated sludge system the average biological sludge production for the year 2000, is estimated to be approximately 111 tn DS/day. Using the values of heavy metals measured in Psyttalia primary dewatered sludge and in the biological sludge obtained from the laboratory scale unit, the approximate heavy metal concentrations of the sludge produced in Psyttalia after the construction of the Biological Treatment Plant were determined: 327 mgCu/kg DS, 4140 mgZn/kg DS, 981 mgCr/kg DS, 264 mgPb/kg DS, 228 mgNi/kg DS, 1.6 mgCd/kg DS and 7 mgHg/kg DS. According to the above results the use of sludge in agriculture is unfeasible at present given the high zinc concentrations that exceed EC Regulations, but also considering the high concentrations of other heavy metals that exceed the more stringent regulations of several European countries.
The intensification of sludge digestion by the disintegration of activated sludge and the thermal conditioning of digested sludge
Authors: Dohányos M. , Zábranská J. , Jeníček P. , Štěpová J. , Kutil V. , Horejš J.
Published: May 2018

The study is focused on the anaerobic degradation of different disintegrated materials containing a cell lysate. The aerobic cell lysate was produced by a disintegration of the excess activated sludge by means of a lysate-thickening centrifuge, and the anaerobic cell lysate, by a rapid thermal treatment of anaerobic digested sludge.

The improvement of both the methane yield and the biodegradability of thickened activated sludge is influenced by the quality of input excess activated sludge and the parameters and efficiency of the thickening centrifuge. The improvement of the methane yield was on average 11.5-31.3% depending on the sludge quality. The relation of the stimulation effect, the disintegration rate and the anaerobic sludge activity suggest that the efficiency of the disintegration will be probably higher in the more intensive digestion process.

The rapid thermal treatment of digested sludge produced a material with an active anaerobic lysate. The stimulation effect of the anaerobic lysate caused an improvement of the methane yield of raw sludge in the range of 35-49% depending on the lysate amount. The rapid thermal reactor produced a relatively very active cell lysate from anaerobic bacteria; the heat energy of the lysate can be utilised in the digester heating system.
Integrated sidestream treatment for enhanced enlargement of sewage plants
Authors: Kolisch G. , Rolfs T.
Published: May 2018

The filtrates or centrates from dewatering of digested sludges cause high internal nitrogen loads on sewage treatment plants. Especially at poor inflow C:N ratios separate treatment of these sludge liquors can significantly relieve the biological treatment stage. We developed a new process for a biological sidestream treatment with primary sludge as the carbon source for denitrification. The process has beeen tested in laboratory-scale tests and by computer simulations. The stability of the process is being investigated in a full-scale application under practical conditions.
Characterisation of production of organic rich topsoil from sludge
Authors: Andreasen P. , Mortensen P. B. , Stubsgaard A. , Langdahl B.
Published: May 2018

The stabilisation of a sludge-mineral soil mixture and a method to evaluate the state of stabilisation were investigated. The organic matter and nitrogen content are reduced up to 50% during a stabilisation process of three months under Danish climatic conditions. The stabilisation was shown to be an aerobic process limited by oxygen transport within the mixture. The degree of stabilisation was evaluated by oxygen consumption in a water suspension and the results showed that a stable product was achieved when oxygen consumption was stable and in the level of natural occurring aerobic soils (0.1 mgO2/(g DS*hr). The study thereby demonstrates that a stability of a growth media can be controlled by the oxygen consumption method tested.
Windrow composting of wastewater biosolids: process performance and product stability assessment
Authors: Lasaridi K. E. , Stentiford E. I. , Evans T.
Published: May 2018

The composting process at the Thames Water composting facility at Little Marlow, Buckinghamshire, UK, was monitored in order to access the value of both process parameters (temperature, drying tendency) and compost stability indicators (VS, COD, respiration rate) for process performance evaluation. A simple model was developed to describe the process rate on the basis of volatile solids and respirometric results.

Pile core temperature exceeded 55°C in the first 2-3 days and reached ambient levels after 8-10 weeks. Compost stability, as determined by both wet (SOUR) and dry (DSOUR) respirometry increased with age, the two parameters correlating well with each other and composting time. The SOUR dropped from about 20 mg/g VS/hr for the fresh compost to 5 mg/g VS/hr at the end of the 4 weeks of turning and to 1.5 mg/g VS/hr after five months of maturation. The COD, optical density at 665, 465 and 280 nm, and the E4/E6 ratio of water extracts were also analysed as potential stability parameters, but the information revealed was limited.
Influence of organic chlorine on emissions from sludge incineration by a pilot fluidised bed furnace
Authors: Mininni G. , Lotito V. , Spinosa L. , Guerriero E.
Published: May 2018

To demonstrate that sewage sludge incineration could be a safe operation if well conducted and that hazardous compounds could also be disposed of without problems in sludge incinerators plants, a research program has been set up by the Italian Water Research Institute on a demonstrative scale plant where a completely circulating fluidised bed furnace and a rotary kiln furnace can operate alternatively. In this paper results of tests performed by a fluidised bed furnace on sewage sludge spiked with highly chlorinated compounds under different operating conditions are presented. A deep investigation on micropollutants formation has been made at different sampling points: before and after bag house filter, and at the chimney. The experimental data show that concentrations of PCDDs+PCDFs (TE) and of PAHs do not strictly depend on the operation of the afterburning chamber and that a complete compliance with the European and Italian standards on the emissions were always achieved even in the most critical conditions investigated.
Microbial water quality and diversity in hydraulic systems using tap water as a pressure medium
Authors: Soini S. M. , Koskinen K. T. , Vilenius M. , Puhakka J. A.
Published: May 2018

Water hydraulics uses tap water or demineralised water as a pressure medium and has fewer environmental impacts than oil-using hydraulics. The applicability is restricted by the microbial quality of the medium. The objectives of this study were to determine whether microbes grow in the pressure medium of a water hydraulic system, biofilm is formed on the surfaces and to describe the diversity of bacteria that survive and grow in water hydraulic systems. A pilot-scale water hydraulic system was used in the experiments. The viable counts in the pressure medium increased in three days from 102 to 3 ×104 cfu/ml followed by a gradual decrease towards the steady-state concentration of 6× 1034 cfu/ml. The total cell numbers decreased from 3×105 to 2 ×104 cells/ml during the three weeks of operation indicating attachment onto the system surfaces as biofilms. The biofilm cell densities on collector slide surfaces varied between 7 ×103 and 1.2 ×104 cells/cm2 after 21 days of operation. The phosphatase activity in the pressure medium was in conformity with the numbers of viable bacteria. The enzymatic activities (α- and β- glucosidase, phosphatase, aminopeptidase) varied between 0.4 and 300 nmol/lh. The diversity of bacteria growing in the system was wide and differed from that of tap water.
Aerobic biodegradation of benzene, toluene and ethylbenzene in liquid medium by a bacterial consortium, isolated from non-history clay soil, and their interrelation effect
Authors: Armon R. , Arbel T. , Narkis N. , Rubin H.
Published: May 2018

The present study was carried out in order to investigate the ability of isolated subsurface bacteria, from a non-history clay soil, to biodegrade the non-aqueous phase-liquids (NAPLs), monoaromatic hydrocarbons: benzene, toluene and ethylbenzene. First stage of the study was focussed on stand-alone biodegradation of each contaminant under described conditions. Benzene (100, 260 and 500 mg/l) exposed to isolated soil bacteria for 14 days, was biodegraded 100, 70 and 50%, respectively, ethylbenzene (100, 260 and 500 mg/l) at 85, 87 and 90%, respectively and toluene (100, 260 and 500 mg/l) revealed the lowest rate of 45, 50 and 52%. Toluene and ethylbenzene showed a direct increase in biodegradation associated with increase in their concentration. The second stage was the biodegradation of benzene, toluene and ethylbenzene admixture (all three compounds at the very same concentrations, w/v) in glucose absence and supplemented with Tween 80 (10 and 15 mg/l). The overall biodegradation improved when contaminants were mixed together.
Modelling of N and P transformations in an SBR treating municipal wastewater
Authors: Brenner A.
Published: May 2018

An advanced mathematical model describing N and P transformations in an SBR treating municipal wastewater has been calibrated based on experimental results. This model is a consequence of intensive field and computer studies carried out for several years. During this time both laboratory-scale and a pilot-scale SBR systems were operated to treat municipal sewage from Beer-Sheva. The study resulted in partial determination of the kinetic and stoichiometric coefficients included in the model. In addition, detailed characterization of organic carbon (based on the COD measure) was done. The final version of the model is based on the concepts proposed by the IAWQ Task Group for Activated-Sludge Modelling. The calibration procedure (AQUASIM) compared theoretical simulated results to actual measurements to estimate the best-fit set of kinetic and stoichiometric parameters. Calibration and validation were based on several dynamic experiments, each of which contains data such as COD, MLSS, NH4, NO3, NO2, PO4, DO and OUR. The final version of the model includes 40 stoichiometric and kinetic coefficients and a set of 15 process rate equations. The proposed model can serve for the improvement of process design, analysis, and control.
The influence of environmental pollution on the SOD and GST-isoenzyme patterns
Authors: Lenártová V. , Holovská K. , Javorský P.
Published: May 2018

The present study investigates the change of the specific isoenzyme pattern of superoxide dismutase (SOD) and glutathione S-transferases (GSTs) in the livers of sheep and fish after their exposure to metal pollutants (predominantly Cu, Hg, and Fe) in industrial areas. Moreover, the influence of mercury on the activities of antioxidant enzymes of rumen bacteria Streptococcus bovis and Selenomonas ruminantium have been studied. In the liver of sheep, the new SOD isoforms (pI 5.7, 5.3 and 5.1) were seen in polluted animals as well as in the liver of fish (pI 5.2, 5.1 and 4.45). With regard to GST isoenzymes, in the liver of sheep, subunit 1 was induced in polluted sheep, and subunit 3 was induced in both polluted sheep and fish liver. Subunit 7 was inactivated in sheep and fish liver. The SOD activity of S. bovis which was considered as Mn-SOD, increased when incubated with HgCl2 in both anaerobic and aerobic conditions. S. ruminantium showed no SOD activity. The differences in antioxidant activity between polluted and reference animals led us to propose that the induction of some isoenzymes of SOD and GSTs could provide useful biomarkers for monitoring environmental pollution.
Pilot study of SBR biological treatment and microfiltration for reclamation and reuse of municipal wastewater
Authors: Messalem R. , Brenner A. , Shandalov S. , Leroux Y. , Uzlaner P. , Oron G. , Wolf D.
Published: May 2018

In Israel the shortage of water and concern for the quality of groundwater resources have led to an awareness that a national wastewater reclamation program must be developed. Such a program could cover a major part of the agricultural water demand and could facilitate disposal of effluents without health hazards or environmental problems. A two-stage pilot-scale system comprising secondary sequencing batch reactor (SBR) treatment and tertiary microfiltration was operated for the treatment of Beer-Sheva municipal wastewater. The self-cleaning, continuous microfiltration system comprised a filter module made up of hollow fiber microporous membranes, with a pore size distribution of less than 0.1 μm, encapsulated into a bundle. The unit, which has a nominal filtration area of 4 m2, can treat 4–5 m3 of sewage per day, at a nominal rate of about 500 L/h. SBR treatment of the raw sewage produced an effluent with a biochemical oxygen demand (BOD) of <20 mg/L and total suspended solids (TSS) of <20 mg/L. Further treatment by microfiltration resulted in a BOD <5 mg/L, TSS <1 mg/L and turbidity <0.2 nephelometric turbidity units (NTU). Bacterial counts showed 6-log removal of coliforms and fecal coliforms. These results indicate that the two-stage scheme is capable of producing an effluent that meets or even surpasses the requirements for unrestricted water reuse for agriculture.
An experimental study on iron removal with ferric sludge recycling
Authors: Tufekci N. , Sarikaya H.Z. , Ozturk I.
Published: May 2018

An iron removal process, which makes use of the catalytic effect of ferric iron, is proposed. For this purpose, the reaction kinetics derived from the data of the batch experiments was applied to the continuous flow system. Based upon this reaction kinetics, it has been theoretically demonstrated that the volumes of aeration tanks can be significantly reduced by keeping a high concentration of ferric iron in the reactor. However, in natural waters, Fe(II) is found commonly to be in the range of 0.01–10 mg/l. These ferrous iron concentrations are not high enough to maintain the high concentrations of ferric iron in the aeration tank. Therefore, similar to the activated sludge processes used in wastewater treatment, it is suggested that the required Fe(III) concentrations can be maintained by recycling Fe(OH)3 sludge back to the aeration tank.

It is known that the oxygenation of ferrous iron is catalyzed by the reaction product, ferric hydroxide. Catalytic action of the ferric iron sludges on the oxidation of ferrous iron by aeration has been identified and the kinetics of this catalytic reaction has been formulated by the authors. The oxidation of Fe(II) was studied in batch reactors in which the concentration of Fe(III) was in the range of 0–600 mg/l.

The oxygenation rate increased linearly with the increasing Fe(III) concentrations up to 50 mg/l and a second-order polynomial relationship was found between the reaction rate and the Fe(III) concentrations in the range of 50–600 mg/l. The required volume (V) of the aeration tank and the effluent Fe(II) concentrations were determined as a function of the Fe(III) concentration. The volume of the aeration tank required for the same Fe(II) conversion was reduced by a factor of 15 when the Fe(III) concentration was raised from 0 to 600 mg/l at pH=6.7. No incremental benefit of the increase of Fe(III) concentration was observed at Fe(III) levels beyond the 600 mg/l.

This study has experimentally demonstrated that significant savings can be achieved in iron removal systems by recirculating the Fe(III) sludges back to the aeration tank.
The rapid quantification and detection of nitrifying bacteria by using monoclonal antibody method
Authors: Ikuta H. , Noda N. , Ebie Y. , Hirata A. , Tsuneda S. , Matsumura M. , Inamori Y.
Published: May 2018

Monoclonal antibodies against the two kinds of nitrifying bacteria Nitrosomonas europaea (IFO14298) and Nitrobacter winogradskyi (IFO14297) were raised and isotypes of these monoclonal antibodies, IgM and IgG1, were successfully obtained. Cross reactivities of these monoclonal antibodies against various kinds of representative heterotrophic bacteria turned out to be relatively low by competitive ELISA. In contrast, these monoclonal antibodies were very specific for nitrifying bacteria used as antigens. By means of sandwich ELISA using different isotype monoclonal antibodies such as IgM and IgG1, calibration curves were successfully developed for quantification of nitrifying bacteria. It was shown that the obtainable lower limit of quantification of N. europaea and N. winogradskyi were 7.0 × 106 N/ml and were 6.0 × 105 N/ml, respectively. Nitrifying bacteria in activated sludge of advanced domestic wastewater treatment johkaso were counted by sandwich ELISA and MPN methods. The bacterial number estimated by MPN method was lower than that estimated by sandwich ELISA. It was indicated that this monoclonal antibody method could be used as a quick and powerful tool for estimating and controlling the population of nitrifying bacteria in the advanced domestic wastewater treatment processes.
The kinetic characteristics of the biomass fixed inside the porous medium in the totally mixed reactor
Authors: Deguchi H. , Mori N. , Matsui Y. , Kashiwaya M.
Published: May 2018

The characteristics of the biomass fixed inside porous medium (sponge cube) have been investigated to see whether it can be recognized as biofilm. The acrylic cube is used as control medium. Two types of flow pattern of bulk water are used in the test to examine its effect on substrate transportation. From the kinetic test, it is found that the biomass fixed inside a sponge cube has biofilm characteristics. At the condition where the diffusion phenomenon is dominant, two layers whose yield constant are different from each other are confirmed from stoichiometric study. When the sponge cube is in the counter flow, the whole biomass fixed inside the medium works at the same time. It is considered that a certain amount of water is flowing through the medium when a sponge cube is exposed to counter flow.
Optimizing enhanced coagulation for DOC removal with ultrafiltration membrane separation using response surface methods and particle trajectory analysis
Authors: Park K. , Seo Y.T. , Whang G.D. , Lee W.
Published: May 2018

An enhanced coagulation study was conducted on bench scale to determine the optimal coagulation condition in terms of pH and coagulant dose for DOC removal by response surface method. 22 factorial design was performed to obtain the optimal coagulation condition of pH = 6.0 and alum dose = 50.4mg/l. A membrane separation experiment with ultrafiltration unit was conducted with the selected conditions of pH and alum dose around the optimal coagulation condition. Flux change, DOC removal efficiency, and turbidity removal efficiency were measured to see the performance of membrane separation. The particle trajectory model suggested by Altena and Belfort was used to analyze the relationship between the size of particles formed by enhanced coagulation and the fouling of ultrafiltration membrane processes, with simulation of the experimental conditions used in this study. The flux of PM30 ultrafiltration membrane was strongly affected by particle size formed in coagulation pretreatment rather than DOC removal rate.
The genotoxity of by-products by chlorination and ozonation of the river water in the presence of bromide ions
Authors: Nobukawa T. , Sanukida S.
Published: May 2018

This study focused on the evaluation of the genotoxic characteristics of chlorinated and brominated substances produced by ozonation and chlorination of the river waters containing bromide ions. The mutagenic activities of drinking waters and disinfected river waters were measured by Ames tests using S. typhimurium strains TA100 and TA98, and by chromosomal aberration test using cultured Chinese hamster lung cells (CHL/IU) in vitro. After flowing samples through CSP800 or XAD-2 resin column, absorbed substances dissolved in dimethyl sulfoxide, and submitted to the mutagenicity assays.

Correlation was high between water qualities revealed by chemical analysis and mutagenic potentials. Mutagenic activities of the drinking waters produced by chlorination were observed to be higher than those by ozonation. Chlorinated waters highly increased in cells with the exchange- and chromatid-type of chromosomal aberrations compared with unchlorinated waters. The increase of mutagenic potentials was caused by by-products when bromide ions were substituted for chloride ions with various ratios.
Dynamic denitrification of 3,600 m3/h sewage effluent by moving bed biofiltration
Authors: Kramer J.P. , Wouters J.W. , Noordink M.P. , Anink D.M. , Janus J.M.
Published: May 2018

STP “De Groote Lucht” in the Netherlands had to be upgraded in order to meet the tightened criterion for total nitrogen (10 mg/l N as yearly average). ASTRASAND moving bed biofiltration, has been introduced for post-denitrification. Pilot plant tests were executed in 1996 and it was found that in order to achieve good filter performance with the specific process conditions, an adequate process control system was required. This filter control ensured removal efficiencies of >95% with influent concentrations up to 30 mg/l NO3−N and strongly fluctuating influent flows. The full scale denitrification installation with a capacity of 3,600 m3/h, the first full scale installation of this type used for biological denitrification in Europe, was built in 1998 and started up in 1999. Since the start up, the filter performance is good and the nitrate removal efficiencies are higher than required.
Methanosaeta fibers in anaerobic migrating blanket reactors
Authors: Angenent L.T. , Zheng D. , Sung S. , Raskin L.
Published: May 2018

An anaerobic migrating blanket reactor (AMBR) was seeded with flocculent biomass from a digester and fed a substrate consisting of volatile fatty acids and sucrose to study granulation. After three months of operation, a mature granular blanket developed in the reactor. Moreover, fibers of approximately 1 cm long had become prevalent in the AMBR. Scanning electron microscopy (SEM) and light microscopy revealed a very dense structure consisting of bundles of filaments resembling Methanosaeta cells. Further studies with fluorescence in-situ hybridization (FISH), showed that Methanosaeta concilii was the predominant microorganism in these fibers.
Simultaneous removal of nitrate and atrazine from groundwater
Authors: Katz I. , Dosoretz C. , Ruskol Y. , Green M.
Published: May 2018

The objective of this research was to study the simultaneous removal of atrazine and nitrate by Pseudomonas ADP in a continuous reactor. Results obtained from batch experiments demonstrated that P. ADP kept the ability to degrade and mineralize atrazine under both aerobic and anoxic conditions. Results from fluidized bed reactors with P. ADP proved efficient biological removal of both nitrate and atrazine. Atrazine degradation in all the reactors studied and under all operational conditions followed the same pattern: First phase, which lasted for 3–5 weeks, with atrazine degradation of about 95% conversion, followed by a second phase where atrazine degradation efficiency decreased gradually, reaching a value of between 10–25%. Results from sterile and non-sterile chemostats experiments indicated that the reason for the decrease in atrazine degradation activity in the continuous reactors was due to the penetration of foreign denitrifying bacteria which did not have the ability to degrade atrazine.
Treatment of ozonated water in biofilters containing different media
Authors: Melin E.S. , Bohne R.A. , Sjøvold F. , ødegaard H.
Published: May 2018

Four parallel biofilters were tested for treatment of ozonated humic water. Two of them contained Kaldnes plastic cylinders (KMT media), one marble and one expanded clay aggregates (Filtralite NC) as biofilm media. Dual-media filter was used for removal of bacteria from biofilter effluents. After four months of operation, average TOC removal was 37–38% and CODMn removal was 43–45% in the ozonation/biofiltration process. Ozonation removed 83% of colour from the raw water. Over 83% removal of ozonation by-products (aldehydes and ketoacids) was also achieved. Biofiltration increased the levels of heterotrophic bacteria in the water but they were reduced by 88% in the dual-media filter. The biofilter media did not have significant effect on treatment efficiency at the empty bed contact time of 30–40 min.
COD balance and nitrogen removal in a biofilter pilot plant
Authors: Nikolavcic B. , Schweighofer P. , Kroiss H.
Published: May 2018

Biological nitrogen removal from wastewater depends on nitrogen incorporation and on denitrification. Both processes strongly depend on the degradation of COD. On the hand of operational data from a biofilter pilot plant, the relation between COD-removal and nitrogen removal is shown. Mass balances for the two parameters COD and N are the base of this consideration, as they are excellent tools for the evaluation of WWTPs (large scale plants as well as pilot plants) in order to estimate the fluxes of these substances and to draw conclusions of general validity. When applying the results from the pilot scale investigation to the whole treatment process (which includes sludge stabilisation), reject water must be taken into account. Therefore, the N removal efficiency was calculated both for the process with and without return liquor.
Chemical composition and activity of a biofilm during the start-up of an airlift reactor
Authors: Lopes F.A. , Vieira M.J. , Melo L.F.
Published: May 2018

For the successful operation of a biofilm reactor, it is important to characterise the fixed biomass, its activity and composition. The purpose of this research was to monitor the biofilm characteristics of an airlift reactor, namely its composition in terms of exopolymers (polysaccharides and proteins), attached biomass, thickness, total proteins, as well as its activity in terms of substrate consumption rates. During the early phases of biofilm development, a high exopolymer production was observed, which helped in promoting the initial cell adhesion. The high turbulence with strong abrasive conditions might also trigger the excretion of those polymers. Low levels of extracellular proteins were detected, showing that the proteins in the biofilm were mainly intracellular. The biofilm accumulation on the carrier was accompanied by an increased biological activity; however, at the end of the experiment, the specific substrate consumption rate decreased, probably because of a reduction of the cell density within the biofilm.
Operation of a nitrifying activated sludge airlift (NASA) reactor without biomass carrier
Authors: Campos J.L. , Mendez R. , Lema J.M.
Published: May 2018

An ammonia loading rate of 4.1 kg N-NH4+/m3d was fully oxidized to nitrate using a nitrifying airlift without biomass carrier. The developed sludge, with a concentration of 12 gVSS/L and high density (100 gVSS/Lparticle), allowed particles to be retained with small diameter, having very low concentrations of solids in the effluent (5–10 mg VSS/L). The mean diameter of particles containing the majority of total biomass increased from 220 to 360 m during the operation time. The particle size analysis showed that the percentage of flocs with small diameter (1–3 m) is very high but the biomass content of these flocs is negligible with respect to the total biomass value. The oxygen transfer coefficient (KLa) was measured operating at different air flow rates, obtaining similar values during the overall operational period. The use of activated sludge without support gives high nitrifying rates with an easier fluidization and a lowercritical air flow rate than in a biofilm airlift reactor.
Using advanced control, post-denitrification and equalisation to improve the performance of a submerged filter
Authors: Sørensen K.H. , Thornberg D. , Janning K.F.
Published: May 2018

In 1998, the capacity of the BIOSTYR® submerged biofilter at Nyborg WWTP was extended from 48,000 PE to 60,000 PE including advanced sensor based control, post-denitrification in BIOSTYR® and equalization of side flows.

The existing configuration with 8 BIOSTYR® DN/N cells is based on pre-denitrification and an internal recirculation of 600–800%. The extended plant comprises 7 BIOSTYR® DN/N cells with 50–225% recirculation followed by 3 BIOSTYR DN cells for post-denitrification. The advanced control loops include blower control, control of the number of active cells (stand-by), automatic switch to high load configuration, control of the side flow equalization, control of the internal recirculation and control of the external carbon source dosing.

In this paper, the achieved improvements are documented by comparing influent and effluent data, methanol and energy consumption from comparable periods before and after the extension. Although the nitrogen load to the plant was increased by 20% after the extension, the effluent quality has improved significantly with a reduction of Total-N from 7–8 mg/l to 3–4 mg/l. Simultaneously, the methanol consumption has been reduced by more than 50% per kg removed nitrogen. The energy consumption remained constant although the nitrogen load was increased by 20% and the inflow by 80%.
Mathematical modeling of trichloroethylene (TCE) degradation in membrane-attached biofilms
Authors: Noguera D.R. , Pizarro G. , Clapp L.W.
Published: May 2018

A mathematical model for the counter-diffusional membrane-attached methanotrophic biofilm reactor was developed. The model included competitive inhibition between trichloroethylene (TCE) and methane, production of inactive cells by TCE byproduct toxicity, and biomass detachment as a function of inactive cell concentration. Simulation results indicated that the optimum oxygen to methane ratio was dependent on the biofilm and the membrane thickness. Furthermore, the model confirmed experimental observations that the efficiency of the process is not limited by competitive inhibition or substrates mass transfer, but by the back-diffusion of TCE through the membrane and the consequent TCE accumulation in the gas phase.
The role of biofilms in the mobilisation of polycyclic aromatic hydrocarbons (PAHs) from the coal-tar lining of water pipes
Authors: Maier M. , Maier D. , Lloyd B.J.
Published: May 2018

The influence of biofilm formation on the coal-tar lining of water pipes in drinking water distribution systems was investigated in batch experiments as well as in a continuously flown circular reactor system. The nutrient source for the growth of the biofilm was only the drinking water and the coal-tar coating on the slides. The growth and existence of the biofilm was examined using different techniques. Leaching experiments showed clearly that the biofilm has protective characteristics because enhanced PAH concentrations could be detected after the removal of the biofilm from the slides. Moreover, the dosage of chlorine as a disinfectant during the reactor experiments gave indication that the chlorination resulted in a destabilisation of the biofilm which lead to elevated PAH concentrations. The results are in correspondence with observations made in real distribution systems where enhanced PAH concentrations were observed during disinfection processes. The examination of coal-tar coated water mains revealed that in addition to the protective effect of a biofilm a vast amount of the PAHs was adsorbed on particles embedded in the biofilm, e.g. from the iron oxidising bacteria Gallionella.
Influence of different substrates on the formation of biofilms in a biofilm airlift suspension reactor
Authors: Villase%ntilde;or J.C. , van Loosdrecht M.C. , Picioreanu C. , Heijnen J.J.
Published: May 2018

The effect of different C1 carbon substrates (formate, formaldehyde, methanol) on biofilm formation in biofilm airlift suspension reactors was studied. The biofilm structure depended on the type of substrate. There seems to be a trend that more reduced substrates or substrates allowing a lower biomass growth rate lead to more dense biofilms. Variations in detachment forces (biomass hold up and carrier concentration) during the experiments affected biofilm characteristics and detachment. Detachment of biofilm biomass under non-growing conditions was studied. The detachment experiments clearly showed that detachment of a growing biofilm is larger than for a non-growing biofilm subjected to the same detachment forces. It is hypothesized that the growth zone of a biofilm forms a more weakly attached biofilm. A trend between biofilm density and the weakly attached fraction of biomass in the biofilm was found.
Fluid flow and transport in defined biofilms: experiments and numerical simulations on a microscale
Authors: Bungartz H-J. , Kuehn M. , Mehl M. , Hausner M. , Wuertz S.
Published: May 2018

As in other fields of science and engineering, the need to understand and predict biofilm systems both on a physical and on a technical scale results in an increasing demand for reliable and efficient numerical simulations of the different processes that take place within biofilms. For that, the expertise of biofilm specialists on the one hand and modern computational techniques on the other hand have to be brought together. In this paper, we present results of a combined and interdisciplinary attempt to simulate fluid flow and transport in defined pure-culture biofilms at the level of continuum mechanics. In order to provide a realistic setup for the simulation and to offer possibilities for a validation of the obtained results, our approach is embedded into state-of-the-art confocal laser scanning microscopy including automated image acquisition and semi-automated image analysis within extended 3D-regions of biofilm structures, which allow both the generation of real-life starting geometries for simulation purposes and the direct comparison of computed and experimental data. An important issue of our approach is flexibility, and the used code NaSt++ offers extensions for taking into account biomass growth or EPS as well as for dealing with more than one substrate.
Evaluating 3-D and 1-D mathematical models for mass transport in heterogeneous biofilms
Authors: Morgenroth E. , Eberl H. , van Loosdrecht M.C.
Published: May 2018

Results from a three dimensional model for heterogeneous biofilms including the numerical solution of hydrodynamics were compared to simplified one dimensional models. A one dimensional model with a variable diffusion coefficient over the thickness of the biofilm was well suited to approximate average concentration profiles of three dimensional simulations of rough biofilms. A new compartmentalized one dimensional model is presented that is then used to evaluate effects of pores and channels on microbial competition in heterogeneous biofilms. Surface and pore regions of the biofilm are modeled using separate compartments coupled by a convective link. Local concentration profiles from the three dimensional simulations could be adequately reproduced using the compartmentalized one dimensional model. The compartmentalized one dimensional model was then used to evaluate bacterial competition in a growing biofilm and in a mushroom type biofilm assuming different modes of detachment.
Using sequencing batch biofilm reactor (SBBR) to treat ABS wastewater
Authors: Chang C.-N. , Chen H.R. , Huang C.H. , Chao A.
Published: May 2018

Ratio of total Kjeldahl Nitrogen to COD for ABS (acrylnitrile, butadiene and styrene) wastewater is in a range of 0.12–0.17, which is significantly higher than that needed for optimal growth of an activated sludge. In this work, an automated Sequencing Batch Biofilm Reactor (SBBR) system at lab-scale is applied to reduce the amount of ABS; this system is controlled by an on-line monitoring of oxidation-reduction potential (ORP). A comparison of the operation efficiency for the lab-scale SBBR operated with the control of fix-time method and ORP-based real-time automatic method is presented. The results show that the system ORP can be used as an available parameter for achieving a real-time operation and control of the lab-scale SBBR. It is found that the reaction time is reduced of 11.1–55.2% if an ORP-based real-time control is used, instead of the fixed-time control. Also, the SBBR system is made more efficient and cost-effective.
Thermophilic sulfate and sulfite reduction with methanol in a high rate anaerobic reactor
Authors: Weijma J. , Haerkens J.-P. , Stams A.J.M. , Hulshoff Pol L.W. , Lettinga G.
Published: May 2018

Thermophilic sulfite and sulfate reduction offers good prospects as part of an alternative technology to conventional off-gas desulfurization technologies. Thermophilic sulfate and sulfite reduction with methanol as the sole carbon and energy source for the sulfate reducing bacteria was studied in lab-scale Expanded Granular Sludge Bed (EGSB) reactors operated at 65 °C and pH 7.5. At a hydraulic retention time (HRT) of 4 hr, sulfite and sulfate elimination rates of up to 0.22 mol-S.l-1.day-1 (100% elimination) and 0.15 mol-S.l-1.day-1 (80% elimination), respectively, were achieved. Sulfite and sulfate reduction accounted for 85–90% of the electrons released during degradation of methanol. In addition, 10–13% and 1–2% of the consumed methanol was converted to acetate and methane, respectively. Acetate was not utilized as electron donor for sulfate reduction. Acetate production seemed to be linearly correlated to the amount of sulfite and sulfate reduced. Sulfite disproportionating activity of the sludge was demonstrated by the simultaneous appearance of sulfide and sulfate in batch tests with sulfite. However, sulfite disproportionation rates were 4 times lower than sulfate reduction rates with methanol. The results clearly demonstrate that methanol can be efficiently used as electron and carbon source to obtain high sulfite and sulfate elimination rates in thermophilic bioreactors.
Evaluating variation of estrogenic effect by drinking water chlorination with the MVLN assay
Authors: Itoh S. , Ueda H. , Naasaka T. , Nakanishi G. , Sumitomo H.
Published: May 2018

It is important to evaluate the estrogenic effect of disinfection by-products in drinking water in addition to typical possible endocrine disrupting chemicals. The estrogenic effect was measured by the MVLN assay as an estrogen receptor transcriptional activation assay. The results suggested that the isolation procedure of aquatic humic substances using XAD7HP resin can be recommended to detect the estrogenic effect of natural water and its chlorinated drinking water by the MVLN assay. Sample volume necessary for the assay would be 1.2 L and required concentation factor would be 100 times. The relative importance of organic substances in Lake Biwa water and the chlorinated one concentrated using XAD7HP resin is large in terms of estrogenic effect. It was also suggested that 4-nonyl phenol and 17 β-estradiol would be important chemicals in investigating the estrogenic effect of natural water. The estrogenic effect of Lake Biwa water increased by chlorination. The estrogenic effect of chlorinated water was approximately 2.3 times as strong as that of Lake Biwa water itself.
Measuring heavy metals by quantitative thermal vaporization
Authors: Ludwig C. , Schuler A. J. , Wochele J. , Stucki S.
Published: May 2018

It is our vision to separate volatile toxic contaminants from waste by thermal treatment. In this context the evaporation behavior of heavy metal traces (Cd, Cu, Pb, and Zn) from model compounds and mixtures, and from fly ash (FA) of municipal solid waste incineration (BCR No. 176) was investigated. In this study we tested a new method which allows on-line detection of heavy metals in hot gases using conventional Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) equipment. A quantitative relation between the amount of evaporated heavy metal traces and the ICP-OES signal was established. In addition, gaseous HCl was successfully used for the total removal of heavy metal traces from non-volatile compounds. The evaporation behavior predicted by speciation calculations were in agreement with the experimental results. The experiments have shown that the method could become a complementary tool for common analytical digestion and measuring methods for the determination of heavy metal traces in solid samples. As our method combines extraction and analytical steps it therefore can shorten conventional procedures. It allows simultaneous, and compared to a conventional digestion and ICP-OES analysis, more sensitive measurements of several elements. The application could become especially powerful for the analysis of contaminated soil and waste residuals.
Heterogeneous and homogeneous photocatalytic degradation of chlorophenols in aqueous titanium dioxide and ferrous ion
Authors: Doong R.-A. , Maithreepala R. A. , Chang S.-M.
Published: May 2018

Photocatalytic degradation of 100 mg/l chlorophenols was studied using TiO,2 and Fenton reagent as catalysts. 2-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol were selected as the target compounds. Results showed that direct photolysis of chlorophenols was faster than that in the TiO,2-amended system. The photodegradation of 2CP followed a first-order rate relationship and the rate constants were 0.022 and 0.0103 min–1 in direct photolysis and TiO,2/UV systems, respectively. The apparent-first-order reaction rate for decomposition of 4-chlorophenol was higher than that for 2-chlorophenol and 2,4-dichlorophenol under acidic conditions, while 2,4-dichlorophenol was higher than 2-chlorophenol and 4-chlorophenol in an alkaline medium. Both the TiO,2 catalyst system and direct photolysis process were faster in basic medium than acidic and neutral medium processes. The Fenton system is excellent for the degradation of chlorophenols and its activity has become low in high pH medium.
Cytotoxicity evaluation of chemicals using cultured fish cells
Authors: Mori M. , Wakabayashi M.
Published: May 2018

Development of simple and rapid cytotoxicity assays using fish cell lines was attempted. Cytotoxicity of chemicals was evaluated by neutral red assay using five monolayer-cultured fish cell lines, BB cells, CHSE-214 cells, EPC cells, FHM cells, RTG-2 cells, and one suspension-cultured fish cell line, CHSE-sp cells. The strength of cytotoxicity was observed in an order of cadmium chloride>zinc sulfate>copper chloride>nickel chloride. The concentration of no observable effect on the CHSE-214 cells viability was 2%(v/v) for DMSO and 0.5%(v/v) for DMSO containing 20 mg · ml–1 taurodeoxycholic acid. The correlation between the 24-hour NR50 values of eleven chemicals to the CHSE-sp cells and those to the CHSE-214 cells was very high (r=0.98). The cytotoxicity assay using suspension-cultured fish cells was found to be one of valuable device for screening the toxicity of chemicals for fish.
Effects of inoculum's mean cell volume on algal toxicity tests
Authors: Chao M.-R. , Chen C.-Y.
Published: May 2018

The aim of the present study is to compare the effects of the mean cell volume (MCV) of algal inoculum to the sensitivity and reproducibility of the toxicity test. Two sets of experiments were conducted using inoculums with the MCV equal to 60 μm3/cell and 40 μm3/cell, respectively. The initial cell densities, however, were kept the same at 10,000 cells/mL. The results show that larger MCV of the inoculum results in greater EC50 values. Similar observations and conclusions were obtained from comparisons based on NOEC values. Thus, MCV of the inoculum significantly influences the observed toxic response in terms of EC50 and NOEC values. It is also evident that, there is a significant increase in the test variability if the MCV is not controlled properly. This study reports that standardizing the initial mean cell volume of algal culture can improve inter-laboratory and intra-laboratory precision. Furthermore, replacing the EC50 values by the calculated exposure values (EE50) can reduce the variability in data due to differences in the MCV of the inoculum.
Biodegradation of household chemicals in river water under untreated discharge conditions
Authors: Peng C.-G. , Arakaki T. , Jung K. , Namkung E.
Published: May 2018

A series of batch die-away tests was conducted to evaluate the decay rates of MBAS and COD under conditions simulating untreated discharge. Under aerobic conditions, decay of MBAS was consistently faster than that of COD, and dilution into river water had no effect on either rate. Under strictly anaerobic conditions, neither MBAS nor COD decreased in concentration. Additional testing examined the fate of 14C-LAS and the results showed that LAS disappeared and was mineralized after a lag period. Half-lives were 8–10 hours for loss of parent and 11–12 hours for mineralization. Addition of 14C-LAS in sewage to systems previously exposed to raw sewage resulted in no lag and shorter half-lives. This work indicates that MBAS and LAS degrade more rapidly than COD, suggesting these materials would be at low levels once a stream had recovered from the addition of untreated sewage.