bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid core waveguide with fiber optic coupling for remote pollution monitoring in the deep ultraviolet
Authors: Belz Mathias , Dress Peter , Klein Karl-F. , Boyle William J. O. , Franke Hilmar , Grattan Kenneth T. V.
Published: May 2018

A new combination of silica fibres, highly transparent in the ultraviolet (UV) and showing long term stability, combined with a teflon-coated liquid-core waveguide (LCW) is presented for remote sensing in the deep UV, for monitoring one of the major pollutants, nitrates, in water, but with potentially wider applicability. The arrangement exhibits low spectral loss in the range between wavelengths of 200 nm and 400 nm and can be used for analytical investigations to determine small concentrations of such impurities in water. The operation of the optical system to achieve guidance of UV light below a wavelength of 250 nm for fibre optic sensors is discussed. With an optical pathlength of 203 mm, nitrate concentrations as low as 22 μg/l could be detected.
Development of a monitor to simultaneously measure dissolved ozone and organic matter in ozonated water
Authors: Tsugura Hiroshi , Watanabe Tetufumi , Shimazaki Hiroshi , Sameshima Shoichi
Published: May 2018

A method for measuring both dissolved ozone (DO3) concentration and UV absorbance was developed adopting ultraviolet (UV) absorption method (JWWA, 1993) using sodium thiosulfate (Na2S2O3) solution for removing residual ozone in ozonated water. A DO3 monitor based on this method was tested. This method was proven to be effective from experimental results. The performance of the monitor was examined with continuous ozonated water. As a result, the monitor performed stably during about 2 months, so that both DO3 concentration and UV absorbance in the ozonated water could be accurately measured. Therefore, the authors have proposed the new aquatic control system with this monitor for ozonation.
Overestimated COD values for raw wastewaters extracted by vacuum sampling devices due to sedimentation effects
Authors: Haider R. , Haider S.
Published: May 2018

Automatic vacuum sampling devices are frequently used to obtain representative samples of raw wastewaters. As a relatively high frequency of sampling is desired to cover the full range of load fluctuations and the volume of a composite sample is generally limited, the volume used from each sampling event is significantly less than that actually extracted by the sampler. On 5 different wastewater treatment plants the authors have found that the COD concentration in the sample volume used for analyses was significantly higher than that in the sample volume wasted by the vacuum sampler. It is hypothesized that the observed change in sample quality after the excess sample volume has been wasted is due to the sedimentation of solids in the sample chamber. This leads to a significant overestimation of the COD in subsequent analyses. Subsequent tests, where samples from vacuum samplers were compared with samples drawn by hand and by a scoop sampler respectively, support this hypothesis.
Evaluation of industrial biological treatment design on the basis of process modelling
Authors: Orhon Derin
Published: May 2018

This paper reviews the basic steps, often overlooked, in the design of activated sludge systems on the basis of recent concepts introduced for process modelling. Firstly, it evaluates the necessary data base for a rational design approach, emphasizing the required wastewater characterization. Secondly, it underlines the significance of functional relationships between reactor biomass, volume and the sludge age recommended as the major design parameters. Then, it defines excess sludge production with specific reference to VSS/SS ratio and to the importance of the influent fixed solids concentration. Finally, it deals in detail with the oxygen requirement of the system, outlining different modelling approaches to be used for such an evaluation and emphasizing the pitfalls to be encountered when using BOD5 parameter for this calculation.
Case history - two stage, low-rate anaerobic treatment facility for South American alcochemical/citric acid wastewater
Authors: Wilson D. R. , Page I. C. , Cocci A. A. , Landine R. C.
Published: May 2018

This paper describes the case history of a two-stage, low-rate anaerobic treatment system at a South American alcochemical and citric acid plant. Environmental concerns associated with land irrigation of a high-strength industrial wastewater forced the plant to implement wastewater treatment. This paper will also outline results from an on-site pilot study which was conducted to develop the design criteria for the full-scale system.

The installed full-scale system will be described in detail, including the plant s physical layout, design parameters, system performance, biogas production and utilization, and some of its unique aspects. Among these is the use of a floating biofilter (bagasse) on the second stage to eliminate any nuisance odours from off gases.

All biogas generated in the first stage is collected, with a significant portion drawn off and burned in a retrofitted 8000 kW boiler to generate process steam. The excess biogas is flared. Effluent from the treatment system is combined with other low-strength process plant streams and discharged to a river.

During the first year of operation, performance has been very good, with chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS) removals averaging 74 percent, 93 percent, and 70 percent, respectively. The corresponding COD, BOD, and TSS results obtained in the pilot study were 74 percent, 96 percent, and 70 percent, respectively, and agree very well with those being obtained in full scale.
Aerobic treatment of reverse osmosis permeate in the dairy industry for reuse
Authors: Bickers P. O. , Bhamidimarri R.
Published: May 2018

The aerobic treatment of reverse osmosis (R/O) permeate was investigated to determine its suitability for reuse in the dairy industry. The biodegradability was characterised by a series of batch tests and the biokinetic parameters μm, Ks and Y were found to be 2.4 d−1, 38 mg L−1 and 0.45 mg TSS/mg Chemical Oxygen Demand (COD) respectively. The permeate was treated aerobically in a 5 litre reactor resulting in an effluent soluble COD of 18 mg L−1. The feasibility of biotreatment was also tested at a pilot plant level. Soluble COD removal efficiencies of over 90% were achieved in trials at 10 and 20-hour hydraulic retention times. True steady state operation was never achieved due to highly variable influent substrate concentrations. The Sludge Volume Index was in the range of 40 to 50 at an HRT of 10 hours, and increased to 70 to 140 at a 20 hour HRT. The test showed that R/O permeate has biodegradability comparable to general dairy effluent, and can potentially be reused after secondary treatment.
Modeling mass transfer and substrate utilization in the boundary layer of biofilm systems
Authors: Horn Harald , Hempel Dietmar C.
Published: May 2018

The use of microelectrodes in biofilm research allows a better understanding of intrinsic biofilm processes. Little is known about mass transfer and substrate utilization in the boundary layer of biofilm systems. One possible description of mass transfer can be obtained by mass transfer coefficients, both on the basis of the stagnant film theory or with the Sherwood number. This approach is rather formal and not quite correct when the heterogeneity of the biofilm surface structure is taken into account. It could be shown that substrate loading is a major factor in the description of the development of the density. On the other hand, the time axis is an important factor which has to be considered when concentration profiles in biofilm systems are discussed. Finally, hydrodynamic conditions become important for the development of the biofilm surface when the Reynolds number increases above the range of 3000-4000.
Use of a dynamic gassing-out method for activity and oxygen diffusion coefficient estimation in biofilms
Authors: Khlebnikov Artem , Samb Falilou , Péringer Paul
Published: May 2018

p-toluenesulphonic acid degradation by Comamonas testosteroni T-2 in multi-species biofilms was studied in a fixed bed biofilm reactor. The polypropylene static mixer elements (Sulzer Chemtech Ltd., Switzerland) were used as a support matrix for biofilm formation. Biofilm respiration was estimated using the dynamic gassing-out oxygen uptake method. A strong relation between oxygen uptake and reactor degradation efficiency was observed, because p-toluenesulphonate degradation is a strictly aerobic process. This technique also allowed us to estimate the thickness of the active layer in the studied system. The mean active thickness was in order of 200 μm, which is close to maximum oxygen penetration depth in biofilms. A transient mathematical model was established to evaluate oxygen diffusitivity in non-steady-state biofilms. Based on the DO concentration profiles, the oxygen diffusion coefficient and the maximum respiration activity were calculated. The oxygen diffusion coefficient obtained (2 10−10-1.2 10−9 m2 s−1) is in good agreement with published values. The DO diffusion coefficient varied with biofilm development. This may be, most likely, due to the biofilm density changes during the experiments. The knowledge of diffusivity changes in biofilms is particularly important for removal capacity estimation and appropriate reactor design.
Removal and recovery of lead fixed-bed biosorption with immobilized bacterial biomass
Authors: Chang Jo-Shu , Huang Jeng-Charn , Chang Chia-Cheng , Tarn Tsueng-Jeng
Published: May 2018

Fixed-bed columns packed with immobilized biomass of Pseudomonas aeruginosa PU21 were utilized to remove lead (Pb) from the contaminated water. Effects of the immobilization method, bed length, flow rate, and the particle size on the performance of Pb removal by the biosorption columns were systematically investigated. Calcium alginate-immobilized cells were found to hold better Pb capacity than polyacrylamide (PAA)-entrapped cells. Typical saturation capacity of calcium alginate (CA)-immobilized cells was 280 mg Pb/g, and 31 mg Pb/g for PAA-immobilized cells. Results of fixed-bed biosorption showed that the breakthrough time (tb) appeared to increase with the bed length, but decreased with the flow rate. The typical overall adsorption efficiency (Q) was within 50-60%, and did not appreciably fluctuate with changes in the operation conditions or the particle size. The initial rate of adsorption was facilitated nearly 40% as the size of immobilized cells was reduced from 3.5 mm to 2 mm, whereas the particle size did not affect the equilibrium adsorption of the immobilized biomass. The length of unused bed (LUB) remained constant with different bed length, while it slightly increased with the raising of the Pb loading rate. The metal-laden column was regenerated by elution of HCl solution (pH 2.0). For up to four adsorption/desorption (A/D) cycles, the metal recovery efficiency of each cycle was over 98%, and the recovery ratio was 8:1 and 27:1 for PAA and CA-immobilized cells, respectively. The regenerated beds were able to restore over 66% of their original adsorption capacity after four successive A/D cycles.
Influence of electron donor and toxic materials on the activity of sulfate reducing bacteria for the treatment of electroplating wastewater
Authors: Song Young-Chae , Piak Byeong-Cheon , Shin Hang-Sik , La Sung-Jin
Published: May 2018

The effects of electron donor and toxic materials on the activity of SRB (sulfate reducing bacteria) were evaluated to ensure the efficient treatment of electroplating wastewater using an anaerobic batch test. The maximum utilization rate of glucose by SRB was slightly slower than that of lactate and acetate, but the affinity of glucose on the SRB was similar to that of the acetate and the lactate. The concentration of carbon source required to reduce 2,000mg/L of sulfate, that is the common concentration of sulfate in the raw electroplating wastewater, was estimated as about 2,200mg COD/L. The efficiency of carbon source for the reduction of sulfate was the highest at around 0.33 of the COD/SO4−2 ratio, but the rate of sulfate reduction was increased according to the increase of COD/SO4−2 ratio ranged from 0.18 to 1.21. Inhibition of copper on the activity of SRB was able to explain using non-competitive inhibition model, and IC50 for copper, that is the concentration causing 50% inhibition of SRB activity, was about 100mg/L of copper. The inhibition of chromium(VI) on the activity of SRB was observed as a mixed inhibition, but the degree of inhibition on the activity of SRB was only about 15% at 130mg/L of the chromium(VI). The inhibitory effect on the SRB caused by 10mg/L of cyanide compound was over 30% of the control, and it was rapidly increased with the cyanide concentration. That could be explained using uncompetitive inhibition model, and IC50 was estimated as about 20mg/L.
Degradation of azo dye RP2B by Pseudomonas luteola
Authors: Hu T. L.
Published: May 2018

Pseudomonas luteola grew well in media containing low glucose concentration (0.125%) and no nitrogen source. It had 95% color removability within 5 days through shaking-static incubation process. It was found that the azoreductase of P. luteola was an inducible enzyme; it reacted with RP2B in a first order reaction. The azo dye acted as an inducer without serving as a growth substrate. The metabolic product of the degradation of RP2B by P. luteola was orthanilic acid. P. luteola's high RP2B degradation ability, low nutritient requirement and shaking-static decolorization process enable it to be used in the treatment of industrial effluent containing azo dyes.
Parallel operation of ultrafiltration and aerobic membrane bioreactor treatment systems for mechanical newsprint mill whitewater at 55°C
Authors: Ragona C. S. F. , Hall E. R.
Published: May 2018

An ultrafiltration system and a membrane biological reactor were operated in parallel to compare the removal efficiencies achieved for total and dissolved solids and chemical oxygen demand, from a simulated, low water-use, mechanical newsprint mill whitewater at 55°C. The ultrafiltration system was operated at water recovery fractions (Y) of 0.9, 0.95 and 0.983, while the membrane biological system was operated at water recovery fractions of 0.95, 0.975 and 0.983. In all cases, the membrane biological reactor exhibited higher removal efficiencies than the ultrafiltration system alone. The MBR demonstrated 48–58% removal of total COD, 35–45% removal of dissolved COD, 25–35% removal of total solids and 20–30% removal of dissolved solids. Maximum flux through the membranes was highest at lower water recovery fractions for both the ultrafiltration system and the membrane biological reactor. Fouling time, based on the time required for a 20% loss of flux, increased with increasing water recovery for the membrane biological reactor and decreased with water recovery fraction for the ultrafiltration system.
Effects of potassium ion on sludge settling, dewatering and effluent properties
Authors: Murthy Sudhir N. , Novak John T.
Published: May 2018

Potassium ions appear to play an important role in determining the nature of activated sludge flocs. Relative to sodium, the concentration of potassium ions in most industrial activated sludge is typically low. Laboratory and field studies were conducted to examine the influence of potassium on activated sludge properties. The concentration of potassium affected the concentration of readily extractable (slime) proteins in the floc and the proteins in the surrounding solution. In laboratory tests, an increase in this cation's concentration beyond nutrient requirements impeded sludge dewatering properties as measured by capillary suction time (CST) and specific resistance to filtration (SRF) and associated with an increase in soluble protein. An increase in effluent total organic carbon and effluent turbidity was observed at higher concentrations of this ion. Conversely, an increase in concentration of potassium ion improved the settling properties of sludge with low equivalent monovalent to divalent cation ratio.
Application of tubular ceramic membranes for reuse of wastewater from buildings
Authors: Ahn Kyu-Hong , Song Ji-Hyeon , Cha Ho-Young
Published: May 2018

This research investigated the possibility of applying ceramic membranes for simple and compact treatment to reuse wastewater generated from hotel buildings for secondary purposes such as toilet flushing water. The tested membranes were ultrafiltration (UF) and microfiltration (MF) membranes of 15 kDa, 300 kDa, and 0.1 mm. Parameters such as transmembrane pressure, crossflow velocity, MWCO/pore size were changed and the performance of the membranes and the quality of the permeate observed.

Since the average particle size of the influent wastewater was 2.18 μm, larger than the pore size of the membranes tested, the effect of MWCO/pore size on the filtration performance was marginal. When a pseudo-steady state was reached, permeate flux increased with increased crossflow velocity. Furthermore, it was better to adopt turbulent flow (Re>20,000) rather than laminar flow in order to maintain constant transmembrane pressure and system stability.

The optimum transmembrane pressure was found to be 150 kPa; a higher pressure will densify the cake layer unnecessarily on the membrane surface which will induce quicker membrane fouling.

When energy consumption was compared, MF with 0.1 μm, which was capable of producing higher permeate flux in the initial phase of experimentation than other tested membranes, was found to be the least energy consuming; the effect of other parameters besides the pore size of the membrane was negligible on the energy efficiency.

The quality of permeates obtained from all the experiments investigated in this research satisfied the guidelines set by the Korea Ministry of Environment for the reuse of wastewater for secondary applications such as in toilet flushing water.
Extracellular redox activity in activated sludge
Authors: Wuertz Stefan , Pfleiderer Petra , Kriebitzsch Klaus , Späth Rosi , Griebe Thomas , Coello-Oviedo Dolores , Wilderer Peter A. , Flemming Hans-Curt
Published: May 2018

The tetrazolium salts triphenyltetrazolium chloride (TTC) and 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride (INT) have been used extensively for the measurement of respiratory activity in natural waters, drinking water, sediments and activated sludge. Usually this is done spectrophotometrically after extracting the reduced formazan salt. Other tetrazolium salts like 5-cyano-2,3-di-4-tolyl-tetrazolium chloride (CTC) are reduced to formazan salts which are fluorescent. This property has been used to microscopically determine the proportion of metabolically active cells in a sample. The observation that CTC is also reduced extracellularly prompted an investigation of the role of this activity in activated sludge. In order to test the assumption that extracellular reduction is stimulated by recalcitrant molecules a bench-scale sequencing batch reactor (SBR) was fed with synthetic wastewater containing either lignin or amylose as well as hexanoic acid, glycerol and sucrose as organic constituents. About 4 times as much tetrazolium salt 3′-{1-[(phenylamino-)carbonyl]-3,4-tetrazolium}-bis (4-methoxy-6-nitro) benzene-sulfonic acid hydrate (XTT) was reduced by extracts containing extracellular polymeric substances (EPS) produced in the presence of lignin than by extracts derived from amylose-fed cells. These differences are statistically significant at P > 0.05. Extracellular redox activity in lignin-containing activated sludge accounted for approximately 2% of total redox activity. In addition to experiments involving reactors fed with different substrates, the extracellular redox activity was measured microscopically using a Zeiss confocal laser microscope. Planktonically grown cells of Escherichia coli or activated sludge flocs were treated with CTC and the nucleic acid stain PicoGreen which fluoresces in the red and green visible light regions, respectively. In Escherichia coli preparations, CTC-formazan crystals were found exclusively inside cells. By contrast, activated sludge flocs revealed crystals both inside and outside the cells. Formaldehyde-treated flocs did not show any reduction of CTC. The extracellular crystals accounted for up to 50% of the total CTC reduction. It follows that extracellular redox activity is associated with the production of EPS. Its role may be to help microbial systems to deal with organic materials which are difficult to utilize.
The use of chemical uncouplers for reducing biomass production during biodegradation
Authors: Low Euan W. , Chase Howard A.
Published: May 2018

Reducing the energy available for anabolism of cell mass was identified as a method to minimise disposal requirements of excess biomass produced in the activated sludge process. A model system consisting of Pseudomonas putida, maintained in a chemostat, was employed to investigate biomass production in the presence of the energy dissipating protonphore, p-nitrophenol (pNP). The efficiency of biomass production was reduced by up to 62% when the feed was supplemented with 100 mg pNP.l−1 with a simultaneous increase in the specific substrate uptake rate. The data obtained have been analysed to reveal maintenance energy requirements and true growth yields. Cells were found to satisfy their maintenance energy requirements prior to utilising energy in anabolism. Decreases in pH alone had no effect on biomass production, but caused additional protonphore induced reduction of biomass production. A pH 6.2 the efficiency of biomass production was reduced by up to 77% when the feed was supplemented with 100 mg pNP.l−1.
Integration of membrane filtration into the activated sludge process in municipal wastewater treatment
Authors: Engelhardt N. , Firk W. , Warnken W.
Published: May 2018

Energy-efficient membrane modules for microfiltration are available to realize a new process engineering in municipal wastewater treatment. The microfiltration membrane ensures that all microorganisms are retained in the aeration tank. A content of mixed-liquor suspended solids of e.g. 15 gMLSS/l can easily be achieved in a large scale plant. Thus the aeration tank is considerably reduced in size. A secondary clarifier is no longer needed. A filtration and a disinfection can be dismissed. A pilot plant gives first knowledge on the application of the activated sludge process with submersed membrane filtration. Based on the tests' results and the knowledge gained during the operation of the pilot plant, a WWTP with membrane filtration for 3000 inhabitants is designed. The costs of investment and operation are estimated.
Immersed membranes activated sludge process applied to the treatment of municipal wastewater
Authors: Côté Pierre , Buisson Hervé , Praderie Matthieu
Published: May 2018

An immersed membrane activated sludge process has been evaluated at pilot scale by Anjou Recherche. This process represents a new generation of hybrid techniques, which aims at coupling biological treatment and membrane filtration functions, in a configuration adapted to the treatment of municipal wastewater.

The process was evaluated under extended aeration conditions, but with concentrations of biomass of between 15 to 25 gMLSS/l, which corresponded to volumetric loadings of between 1.2 to 2.3 kg COD/m3/d. Under these conditions, COD and TKN removal were better than 96% and 95%, respectively. The membrane ensured total removal of suspended solids and produced treated water of excellent bacteriological quality. The sludge production stabilized at 0.20 gDS/kg COD removed. The membrane flux was stable for all conditions tested.
Description of behavior in rejection of pollutants in ultra low pressure nanofiltration
Authors: Ratanatamskul C. , Urase T. , Yamamoto K.
Published: May 2018

Low pressure operation of nanofiltration process ranged from 0.3 bar to 5 bar was examined. The lower rejection of nitrate compared to that of chloride was found in all cases especially in lower pressure operation. A set of extended Nernst-Planck equations was applied to describe the rejection difference theoretically. The original extended Nernst-Planck equation failed to explain the difference in rejection between nitrate and chloride though it can explain the rejection difference between monovalent ions and divalent ions. The difference in rejection between chloride and nitrate was well explained by introducing a new parameter which describes partitioning of ions at the membrane-solution interfaces. The new parameter might be related to materials of membranes and to the affinity of ions on the membrane surface.
Bioaugmentation of sequencing batch reactors for biological phosphorus removal: comparative rRNA sequence analysis and hybridization with oligonucleotide probes
Authors: Oerther Daniel B. , Danalewich James , Dulekgurgen Ebru , Leveque Eric , Freedman David L. , Raskin Lutgarde
Published: May 2018

Four laboratory-scale sequencing batch reactors (SBRs) were operated to evaluate whether bioaugmentation with Acinetobacter spp. can be used to improve start-up and performance of enhanced biological phosphorus removal (EBPR) systems. Two of the SBRs were bioaugmented during start-up by adding pure cultures of Acinetobacter spp., the third reactor received an amendment of activated sludge from a laboratory-scale EBPR system, and the fourth reactor, receiving no amendment, served as a control. Various chemical parameters were measured to monitor the performance of the four SBRS. Oligonucleotide probes of nested phylogenetic specificity were designed to quantify the contribution of Acinetobacter to EBPR. The probes were characterized for use in quantitative membrane hybridizations and fluorescent in situ hybridizations. Data from hybridizations with samples collected from the SBRs show declining levels of Acinetobacter spp. over the experiment. All four reactors achieved significant phosphorus removal and 90% nitrification after three days of operation. The results do not show a positive correlation between levels of Acinetobacter and successful EBPR.
Cadmium salts transport through a nanofiltration membrane: experimental results and model predictions
Authors: Garba Y. , Taha S. , Gondrexon N. , Dorange G.
Published: May 2018

This article discusses the transport mechanism of cadmium salts (CdCl2, Cd(NO3)2) through a nanofiltration membrane. A model based on the extended Nernst-Planck and the film theory equations is reported. This model is characterized by three transport parameters: the water permeability Lp, the ion transmittance Φ and the effective transfer coefficient Keff. The knowledge of the feed and permeate concentrations and the permeate flux enable the calculation of these parameters. The model was used to predict cadmium salt solution rejection by a NANOMAX 50 membrane. The experimental values and calculated predictions are in good agreement.
Characterisation of enhanced biological phosphorus removal activated sludges with dissimilar phosphorus removal performances
Authors: Bond Philip L. , Keller Jürg , Blackall Linda L.
Published: May 2018

A sequencing batch reactor (SBR) was operated for enhanced biological phosphorus removal (EBPR) and dramatic differences in the P removing capabilities were obtained in different stages of the operation. At one stage extremely poor P removal occurred and it appeared that bacteria inhibiting P removal overwhelmed the reactor performance. Changes were made to the reactor operation and these led to the development of a sludge with high P removing capability. This latter sludge was analysed by fluorescent in situ hybridisation (FISH) using a probe specific for Acinetobacter. Very few cells were detected with this probe indicating that Acinetobacter played an insignificant role in the P removal occurring here. Analysis of the chemical transformations of three sludges supported the biochemical pathways proposed for EBPR and non-EBPR systems in biological models. A change in operation that led to the improved P removal performance included permitting the pH to rise in the anaerobic periods of the SBR cycle.
Interactions between filamentous sulfur bacteria, sulfate reducing bacteria and poly-P accumulating bacteria in anaerobic-oxic activated sludge from a municipal plant
Authors: Yamamoto-Ikemoto Ryoko , Matsui Saburo , Komori Tomoaki , Bosque-Hamilton Edja. Kofi.
Published: May 2018

The interactions between filamentous sulfur bacteria (FSB), sulfate reducing bacteria (SRB) and poly-P accumulating bacteria (PAB) in the activated sludge of a municipal plant operated under anaerobic-oxic conditions were examined in batch experiments using return sludge (RAS) and settled sewage. Phosphate release and sulfate reduction occurred simultaneously under anaerobic conditions. SRB were more sensitive to temperature changes than PAB. SRB played an important role in the decomposition of propionate to acetate. When the sulfate reduction rates were high, there was a tendency for the maximum release of phosphate also to be high. This was explained by the fact that PAB utilized the acetate produced by SRB. Sulfur oxidizing bacteria were sensitive to temperature change. When the sulfate reduction rate was high, the sulfide oxidizing rate was also high and filamentous bulking occurred. The results showed that sulfate reduction was a cause of filamentous bulking due to Type 021N that could utilize reduced sulfur.
Modelling sediment accumulation and dispersion of contaminants in Lake Ijsselmeer (The Netherlands)
Authors: Blom G. , Winkels H. J.
Published: May 2018

In this study two models are integrated for the simulation of sediment distribution and quality in the Lake IJsselmeer area. STRESS-2d, a two dimensional dynamic model for simulation of sediment transport due to resuspension, erosion, sedimentation and horizontal advection and dispersion is used to simulate the sediment transport dynamics for a period of one year. The model is calibrated on water level, suspended solids concentration and sedimentation flux measurements. The model has a high spatial and temporal resolution. The model DIASPORA, which is based on STRESS-2d results, simulates the effects of sediment transport on morphology and contaminant concentrations in the sediment for a period of decades. DIASPORA also simulates dilution by internally produced CaCO3 and consolidation of sediment layers. The models produce a reasonable reconstruction of suspended solids concentrations and long term accumulation of sediments in deep areas within the lake. Also the temporal and spatial variability in the contaminant concentration in sediments in Lake IJsselmeer is reconstructed with sufficient quality. Model simulations show that internal redistribution of old deposits in the IJsselmeer area and internal production of CaCO3 are diluting the contaminated solids supplied by the river IJssel.
Non-steady state behaviour of heavy metals in contaminated freshwater sediments
Authors: van den Berg Gerard A. , Loch J. P. Gustav , Zwolsman John J. G. , van der Heijdt Lambertus M.
Published: May 2018

The behaviour of heavy metals has been investigated in contaminated sediments of the river Meuse, The Netherlands. Due to temporal changes in temperature and degradability of organic matter, the depths of the redox boundaries fluctuate. This contributes to a non-steady state. As a result of oxidation processes, a distinct peak in heavy metal concentrations in pore water is measured at the sediment-water interface. Because the studied anoxic sediments contain low levels of sulphide, other solid phases are expected to be of importance in the binding of heavy metals. Furthermore, heterogeneity of the sediment and complexation with dissolved organic compounds may result in supersaturation of the anoxic pore waters with respect to discrete heavy metal sulphides, thus influencing heavy metal mobility. Calculations using concentration gradients of heavy metals indicate that diffusive fluxes between the sediment and the surface water contribute to concentrations in the surface water, although significant effects may be confined to specific locations.
Sediment and heavy metal distribution and transport in a coastal area affected by a submarine outfall in the Basque Country (Northern Spain)
Authors: Uriarte Adolfo , Franco Javier , Borja Angel , Valencia Victoriano , Castro Raúl
Published: May 2018

In 1989 a submarine outfall was brought into service in the coastal area of Zarautz, in the Basque Country (north of Spain). The outfall discharge point is located at ∼35 m depth and ∼1 km offshore. This work deals with the sediment dispersion and distribution patterns in the vicinity of an outfall. The methodological field procedures included bathimetric surveys and sediment sampling for grain size characterization and analysis of organic matter content and heavy metal concentrations. Sediment resuspension and transport paths were estimated. Small-sized sediments have been only deposited in the proximity of the outfall discharge point. Heavy metal distribution in the sediments shows only minor influence of the outfall. Only under storm weather conditions sediments will get into suspension. Sediment transport studies suggest a net transport from the outfall discharge point to the N-NW. It can be established that sediments discharged by the outfall will not be transported coastwards; thus, water quality in this area will not be affected.
Metals, acid-volatile sulfides, organics, and particle distributions of contaminated sediments
Authors: Christensen E. R.
Published: May 2018

An overview of key physical/chemical parameters for contaminated sediments is presented. While sediment cores from remote lakes show little or no enrichment with heavy metals (Pb, Hg, Cd, Zn, Cu) and PAHs in top layers, the contamination near industrial areas is more significant. Cd in more bioavailable geochemical phases can occur in response to Cu inputs to sediments, and aeration during dredging operations of anaerobic sediments can reduce the pH causing release of heavy metals. The toxicity of anaerobic sediments to benthos can be effectively predicted based on interstitial water concentrations and the molar ratio between simultaneously extracted metals and acid-volatile sulfides (SEM/AVS). The toxicity of PAHs and other organics can be predicted based on equilibrium partitioning. Principal component analysis indicates that PAHs are associated with organic carbon and silt, and PCBs with inorganic clay. Finally, formulated reference sediments appear to be useful in toxicity testing by creating uniform parameters matching field conditions, and by isolating the effects of specific contaminants.
Dioxin, dioxin-like PCBS and organotin compounds in the river Elbe and the Hamburg harbour: identification of sources
Authors: Götz Rainer , Steiner Bernd , Sievers Susanne , Friesel Peter , Roch Klaus , Schwörer Roland , Haag Franz
Published: May 2018

Using neural networks (in this case the Kohonen network) and a multivariate statistical method - the hierarchical cluster analysis -, a classification of dioxin data has been carried out. A principal conclusion, which can be drawn, is that a significant source of dioxin in the river Elbe, Hamburg harbour, the soils of the flood plains of the river Elbe and in soils originating from dredging materials, has been shown to originate from the dioxin contaminated region of Bitterfeld. The results indicate that the dioxin contamination in the Bitterfeld region was caused partly by metallurgy processes, not just by chemical production. Furthermore, the results show that a main dioxin source responsible for the contamination of Hamburg surface waters, not influenced by the river Elbe, is of “thermal origin”. The river Elbe shows a characteristic butyltin pattern. The cause is probably a plant in Bitterfeld. The precise sources of the dioxin-like PCB are still unknown.
Bioleaching of heavy metals from contaminated aquatic sediments using indigenous sulfur-oxidizing bacteria: a feasibility study
Authors: Seidel H. , Ondruschka J. , Morgenstern P. , Stottmeister U.
Published: May 2018

The removal of heavy metals from contaminated river sediments was studied using suspension leaching under laboratory conditions and percolation leaching in a pilot plant. The leaching potential of indigenous sulfur-oxidizing bacteria was compared with acid treatment. Bioleaching with elemental sulfur as substrate was found to be better than treatment with sulfuric acid for the solubilization of all metals tested. The physical and chemical properties of the sediments used in this study did not affect leaching capacity under optimum conditions in the laboratory.

Under the practical conditions in the pilot plant, the redox state of sludge had a considerable influence on leaching efficiency. In a deposited oxic sediment with good permeability, about 62% of the metals tested were removed by percolation leaching after 120 days. Zn, Cd, Ni, Co and Mn were sufficiently leached to enable treated sediments to be reused as soil. In a freshly dredged anoxic sediment, only a total of 9 % of metals were removed. The results indicate that freshly dredged sediments need to undergo pretreatment before percolation leaching to improve mass transfer and to activate the leaching active bacteria.
Intracellular storage compounds, oxygen uptake rates and biomass yield with readily and slowly degradable substrates
Authors: Goel Rajeev , Mino Takashi , Satoh Hiroyasu , Matsuo Tomonori
Published: May 2018

An experimental study was undertaken to quantify the effects of intracellular storage polymers on the Oxygen Uptake Rate (OUR) profile and biomass yield coefficients for readily and slowly degradable substrates using a sludge from anaerobic-aerobic Sequencing Batch Reactor (SBR). Glucose and acetate were chosen as readily biodegradable substrates and soluble starch served as a model polymeric slowly degradable substrate. In case of acetate as substrate, PHA was the major storage polymer while polysaccharide acted as the main storage compound in case of glucose and starch. The accumulation of storage compounds even in the case of starch suggests that storage may be an integral part of the metabolic process for the sludge having storage capabilities. The maximum storage amounted to about 45%, 68% and 36% of total acetate, glucose and starch COD removed from bulk respectively. A new approach to calculate the true biomass yield coefficients based on exogenous OUR and considering intracellular storage is proposed. The relative independence of the calculated yield values to the amount of storage makes them suitable for application in growth kinetics. The calculated yield coefficients based on the proposed approach worked out to be 0.24–0.28, 0.58–0.50 and 0.64 for acetate, glucose and starch respectively and were significantly lower than the yield coefficients calculated based on conventional approach of not accounting storage. Further, the average degradation rate of intracellular glycogen were estimated to be 15 mg carbohydrate COD/g. MLSS. hr. with an average biomass yield of 0.45 mg biomass COD/mg carbohydrate COD.
Measurement of local effective diffusivity in heterogeneous biofilms
Authors: Beyenal H. , Tanyolaç A. , Lewandowski Z.
Published: May 2018

We have developed a novel technique to measure local effective diffusivity distribution in heterogeneous biofilms. Mobile microelectrodes (tip diameter 10 μm) and the limiting current technique were employed to measure the effective diffusivity of electroactive species introduced to natural and artificial biofilms. We calibrated the microelectrodes in artificial biofilms of known effective diffusivity and known density. In mixed population biofilms, local effective diffusivity varied from one location to another and decreased toward the bottom of the biofilm. We related local effective diffusivity to local biofilm density using an empirical equation. Surface-averaged biomass density depended on liquid flow velocity at which the biofilms were grown. The higher the flow velocity, the denser were the biofilms. Our technique permits fast evaluation of local effective diffusivity and biofilm density in heterogeneous biofilms.
Bench scale investigations of bacterial regrowth in drinking water distribution systems
Authors: Ollos P. J. , Slawson R. M. , Huck P. M.
Published: May 2018

Laboratory reactors operated under conditions relevant for drinking water distribution systems were used to examine the impact of support surface, chloramine residual, biodegradable organic matter (BOM) concentration, shear, and temperature on the growth of heterotrophic microorganisms. In terms of both heterotrophic bacterial growth-supporting and corrosion characteristics, mild steel and stainless steel/polycarbonate substrata bracket metallic pipe materials, such as ductile iron. Results of gradually increasing disinfectant dosage studies suggest that a 0.5 mg/L free or combined chlorine residual on polycarbonate surfaces, and 0.5 mg/L free chlorine or 2.0 mg/L combined chlorine residual on ductile iron substrata would be needed to reduce biofilm HPC numbers to approximately 103 CFU/cm2. Regression analysis suggests low or very low correlation between biofilm and suspended HPC numbers.
Feasibility of the UASB/AF system for domestic sewage treatment in developing countries
Authors: Chernicharo C. A. L. , Machado R. M. G.
Published: May 2018

This paper presents the results of three pilot units comprising one UASB reactor followed by two anaerobic filters (AFs) operating in parallel (upflow and downflow modes). The UASB reactor had a volume of 416 litres, being operated at hydraulic retention times (HRT) of 6 and 4 hours. The anaerobic filters had total volumes of 102 litres (32 litres of packing material), being operated at HRT varying from 24 to 1.5 hours (upflow velocities varying from 0.06 to 1.44 m/h). These different operational conditions characterised seven phases of research. Both reactors were fed with domestic sewage pumped directly from the main interceptor of Belo Horizonte city – Brazil.

After almost one year of continuous monitoring, the UASB/AF system produced very good results in terms of COD and BOD removal, and also very low solids concentration in the final effluent. The average results of COD and BOD removal varied from 85 to 95%, sufficient to maintain the COD concentration in the final effluent in the range of 60 to 90 mg/l and the BOD values systematically below 40 mg/l. The overall averages of SS in the final effluent were kept below 25 mg/l.

The UASB/AF system could become a very promising alternative for the treatment of domestic sewage in developing countries, since the system can be designed at very short hydraulic retention times (6 hours for the UASB reactor and 3 to 4 hours for the AF), resulting in a very compact and low cost treatment unit. Besides, there is no energy consumption and the labour costs are minimum.
Influence of synthetic and natural polymers on the anaerobic granulation process
Authors: El-Mamouni R. , Leduc R. , Guiot S. R.
Published: May 2018

The influence of synthetic Percol 763 and natural chitosan polymers on the granulation rate of suspended anaerobic sludge was studied in laboratory-scale upflow anaerobic sludge bed (UASB)-like reactors. The results showed that supplementation of the reactors with polymers, either natural or synthetic, enhanced the granulation in comparison to control reactors (without the addition of polymers). A greater granulation was, however, obtained with chitosan compared to that with Percol 763. Chitosan yielded a granulation rate as high as 56 m/d compared to 35 m/d Percol 763. The superior granulation performance of chitosan was probably related to its polysaccharidic structure, hence acting similarly to the extracellular polymeric substances (EPS) in aggregating anaerobic sludge. The granules specific activities were enhanced in the reactors supplemented with both polymers compared to those in control reactors. Overall, the results showed that polymers play a more critical role than microbial trophic groups in enhancing anaerobic granulation in UASB-like reactors.
Removal of chlorinated phenols in upflow anaerobic sludge blanket reactors
Authors: Droste Ronald L. , Kennedy Kevin J. , Lu Jingua , Lentz Mercedes
Published: May 2018

The dechlorination of chlorophenol (CP) compounds was investigated using upflow anaerobic sludge blanket reactors. A total of five trichlorophenols (TCPs) and a single dichlorophenol (DCP) were individually treated: 2,3,4-TCP; 2,3,5-TCP; 2,3,6-TCP; 2,4,5-TCP; 2,4,6-TCP; and 3,5-DCP. Synthetic wastewater composed of sucrose and acetic acid provided an alternate, readily biodegradable carbon source. Each chlorinated compound was concurrently fed to separate reactors. The parameters that were quantified include biogas composition, acetic acid concentration, COD, and VSS. The degree to which CPs were sorbed to the granular biomass in actively dechlorinating UASB reactors was found to be insignificant. CP compounds were able to be metabolized to mineral end products to a large extent at loadings where reactor performance was not impaired. Ortho chlorine atoms were most readily removed from CPs. CPs containing chlorine atoms in the para position were the most toxic agents with 2,4,5-TCP being the most toxic compound. Toxicity was reversible.
Effect of HRT and temperature on the acidogenesis of municipal primary sludge and industrial wastewater
Authors: Banerjee A. , Elefsiniotis P. , Tuhtar D.
Published: May 2018

Two bench-scale completely mixed reactors were used to study the effect of hydraulic retention time (HRT), temperature and wastewater composition on the acid-phase anaerobic digestion process. One reactor was fed with a 1:1 mixture of starch-rich industrial wastewater and municipal primary sludge, while the other was fed with primary sludge alone. Results show that net volatile fatty acid (VFA) production and chemical oxygen demand (COD) solubilization increase significantly with the addition of the industrial wastewater and also with increase in HRT from 18 to 30 hours. In general, increase in temperature led to reduction of the net production due to poor performance of the clarifiers.
Nitrogen removal in attached growth waste stabilization ponds of wastewater from a rubber factory
Authors: Rakkoed A. , Danteravanich S. , Puetpaiboon U.
Published: May 2018

Nitrogen removal from wastewater from rubber factories using attached-growth waste stabilization ponds (AGWSP) was evaluated. Usually, wastewaters generated from rubber factories such as concentrated latex factories and rubber sheet factories contain a high amount of nitrogen originating from natural rubber and ammonia compounds added in the production processes. From an investigation of 3 rubber factories at Songkhla, Thailand, average concentrations of TKN, NH3-N and Org-N in raw factory wastewater were found to be 889, 578 and 311 mg/l respectively. Two series of laboratory waste treatment ponds, waste stabilization ponds (WSP) and attached-growth waste stabilization ponds were investigated to compare the efficiency of nitrogen removal from wastewater from a concentrated latex factory. The wastewater fed to the experimental units was collected from the effluent of the anaerobic treatment pond at the factory. The experiments were conducted with hydraulic retention times (HRT) of 40 and 20 days. Another experiment run with an HRT of 40 days together with 50% recirculating of effluent was also conducted. Finally, an experiment run at an HRT of 4 days was carried out in order to observe the effect of shock loading. The results revealed that TKN, NH3-N and BOD5 removal efficiencies in AGWSP were higher than in control ponds (WSP). Increased removal efficiencies were achieved which resulted from an increase in biomass on media in the pond water.