bluuebunny/crossref_metadata_2025 huggingface dataset:
Monitoring in inline storage sewers for stormwater treatment to determine efficiencies
Authors: Frehmann T. , Mietzel T. , Kutzner R. , Spengler B. , Geiger W.F.
Published: May 2018

A special structure of combined sewer overflow tanks is the inline storage sewer with downstream discharge (SKU). This layout has the advantage that besides the sewer system, no other structures are required for storm water treatment. Consequently only very little space is required and compared to combined sewer overflow tanks, there is an enormous potential in reducing costs during construction. To investigate the efficiency of an inline storage sewer, a monitoring station was established in Dortmund-Scharnhorst, Germany. The monitoring station was in operation for a period of 2.5 years. Within this period water samples were taken during a total of 20 discharge events. Besides the complete hydraulic data collection, seven water samplers took more than 5,000 water samples during dry and wet weather. This adds up to a total of more than 20,000 individual lab analyses. The average of the total efficiency for the SKU-West is 86%. 29% of this efficiency can be attributed to the throttle flow. The remaining 57% can be divided into a part of 48% that can be attributed to the process storage and 9% that can be attributed to sedimentation and erosion process.
The acoustic attenuation and hydraulic roughness in a large section sewer pipe with periodical obstacles
Authors: Horoshenkov K.V. , Yin Y.A. , Schellart A. , Ashley R.M. , Blanksby J.R.
Published: May 2018

The acoustic attenuation, relative sound pressure levels and the equivalent Nikuradse wall roughness under variable flow conditions in a 600 mm concrete sewer pipe are experimentally investigated. The values of the acoustic attenuation are obtained in the case of airborne sound propagation in the dry pipe. A range of values of the equivalent wall roughness is artificially generated by deploying a periodical array of engineering bricks. A novel method of rapid evaluation of the acoustic attenuation is proposed. The method relies upon sound reflections from the adjacent manholes. The results demonstrate that the acoustic attenuation depends strongly on the value of the equivalent wall roughness. This work can pave the way to the efficient methodology for the in-situ, physical evaluation of the equivalent hydraulic roughness of new and existing sewer networks.
Ion selective transistor modelling for behavioural simulations
Authors: Daniel M. , Janicki M. , Wroblewski W. , Dybko A. , Brzozka Z. , Napieralski A.
Published: May 2018

Computer aided design and simulation of complex silicon microsystems oriented for environment monitoring requires efficient and accurate models of ion selective sensors, compatible with the existing behavioural simulators. This paper concerns sensors based on the back-side contact Ion Sensitive Field Effect Transistors (ISFETs). The ISFETs with silicon nitride gate are sensitive to hydrogen ion concentration. When the transistor gate is additionally covered with a special ion selective membrane, selectivity to other than hydrogen ions can be achieved. Such sensors are especially suitable for flow analysis of solutions containing various ions. The problem of ion selective sensor modelling is illustrated here on a practical example of an ammonium sensitive membrane. The membrane is investigated in the presence of some interfering ions and appropriate selectivity coefficients are determined. Then, the model of the whole sensor is created and used in subsequent electrical simulations. Providing that appropriate selectivity coefficients are known, the proposed model is applicable for any membrane, and can be straightforwardly implemented for behavioural simulation of water monitoring microsystems. The model has been already applied in a real on-line water pollution monitoring system for detection of various contaminants.
Dynamic monitoring system for full-scale wastewater treatment plants
Authors: Yoo C.K. , Lee J.-M. , Lee I.-B. , Vanrolleghem P.A.
Published: May 2018

This paper proposes a new process monitoring method using dynamic independent component analysis (ICA). ICA is a recently developed technique to extract the hidden factors that underlie sets of measurements, whereas principal component analysis (PCA) is a dimensionality reduction technique in terms of capturing the variance of the data. Its goal is to find a linear representation of non-Gaussian data so that the components are statistically independent. PCA aims at finding PCs that are uncorrelated and are linear combinations of the observed variables, while ICA is designed to separate the ICs that are independent and constitute the observed variables. The dynamic ICA monitoring method is applying ICA to the augmenting matrix with time-lagged variables. The dynamic monitoring method was applied to detect and monitor disturbances in a full-scale biological wastewater treatment (WWTP), which is characterized by a variety of dynamic and non-Gaussian characteristics. The dynamic ICA method showed more powerful monitoring performance on a WWTP application than the dynamic PCA method since it can extract source signals which are independent of time and cross-correlation of variables.
Electron-optical characterization of nano- and micro-particles in raw and treated waters: an overview
Authors: Leppard G.G. , Mavrocordatos D. , Perret D.
Published: May 2018

State-of-the-art information is presented on the analysis, by transmission electron microscopy (TEM), of aquatic colloidal particles in the size range of 3 to 500 nm least dimension, with a focus on nanoparticles (1-100 nm). Case studies include selections from both natural waters and waters undergoing treatment. The “species” of nano-particles receiving the greatest attention are: humic substances, polysaccharide fibrils, hydrous iron oxides, viruses, clay minerals, refractory cell debris, and heavy metal agglomerates on biological surfaces. Artifacts and how to both detect and minimize them are outlined. Correlative use of TEM with other imaging techniques is emphasized, along with associated spectroscopy. Noted is the potential of computerized image analysis for quantifying colloids on a “per colloid species” basis, using water samples centrifuged onto electron microscope grids.
Size fractionation of COD in urban wastewater from a combined sewer system
Authors: Marani D. , Renzi V. , Ramadori R. , Braguglia C.M.
Published: May 2018

The objective of this work was to determine the partitioning of the pollutant load in urban wastewater in order to improve the conventional sewage treatment. In addition to settling tests, physical fractionation of COD in the degritted influent of Roma-Nord sewage treatment plant was performed via sequential filtration through sieves and membrane filters of the following pore size: 150-100-50-25-1-0.2 μm, and 100 kD (about 0.02 μm). Biodegradability studies were also performed on the different size fractions. Size fractionation showed that COD in Roma-Nord sewage is predominantly associated with settleable and supracolloidal (> 1 μm) particles, each size range including about 40% of total COD. Biodegradability tests indicated that the large fraction of COD associated with supracolloidal particles, which are not removed in the primary treatment, is characterised by slow degradability. This suggests that removal of these particles prior to biological treatment may greatly improve the overall treatment scheme. Preliminary pilot plant coagulation tests with lime at pH 9 showed that lime-enhanced primary treatment may increase COD removal efficiencies from typical 30-35% up to 65-70%, by inducing almost complete removal of the COD fraction associated with supracolloidal particles.
The scientific basis of flocculator design
Authors: Lawler D.F. , Nason J.A.
Published: May 2018

A new guideline for the design of flocculators is proposed. This guideline is to design continuous flow flocculators on the basis of the characteristic reaction time for the loss of one micrometre particles in the suspension. The most commonly used guideline at the present time is that of Camp, but later proposals by Ives and O'Melia expanded the Camp guideline and incorporated more complete knowledge of flocculation. The suggestion here continues that process, by accounting explicitly for the heterodisperse nature of typical suspensions and the multiple collision mechanisms for particles in determining a characteristic reaction time. While the historical guidelines have served the water treatment industry well for reasonably similar size distributions in waters destabilized by precipitating metal hydroxides, the proposed guideline should be more robust in considering other suspensions. In particular, the new guideline can account explicitly for the effects of nanoparticles on flocculation.
Particle visualisation - a tool for determination of rise velocities
Authors: Ljunggren M. , Jönsson L. , la Cour Jansen J.
Published: May 2018

Particles from a post denitrifying Kaldnes Moving Bed™ Process were studied using an optical borescope, a visualisation technique that provides opportunities for both qualitative and quantitative studies of the separation mechanism in Dissolved Air Flotation (DAF). Rise rates for particle/bubble aggregates were estimated showing great variability. Two groups of aggregates were distinguished; relatively small flocs (<100 μm) with single bubbles attached rising comparatively slowly and large flocs (>100 μm) with several bubbles attached rising very fast. The high rise rates for large aggregates are discussed, possibly explained and suggested as the reason for the effective separation of large particles noticed in previous studies. Removal efficiency of different size categories of particles in DAF were investigated on the basis of particle size analysis indicating increased separation efficiency with increasing particle size.
Organic colloids and their influence on low-pressure membrane filtration
Authors: Laabs C. , Amy G. , Jekel M.
Published: May 2018

Wastewater treatment by low-pressure membrane filtration (MF and UF) is affected to a large extent by macromolecules and colloids. In order to investigate the influence of organic colloids on the membrane filtration process, colloids were isolated from a wastewater treatment plant effluent using a rotaryevaporation pre-concentration step followed by dialysis. Stirred cell tests were carried out using redissolved colloids, with and without additional glass fiber filtration. After constant pressure membrane filtration of 190 L/m2, the initial flux had declined by 50% for colloids > 6-8 kD (glass fiber filtered) with a hydrophilic MF membrane and for colloids >12-14 kD (glass fiber filtered) with a hydrophobic MF membrane. For the non-filtered colloidal solutions, the flux decline was even steeper with the flux being below 10% of the initial flux after 190 L/m2 were passed through the membranes. As with larger particles, colloids form a filtration cake layer on top of the membrane surface when used as isolates without prior filtration. This filtration cake is easily removed during backwashing. However, polysaccharides as a macromolecular component of the colloid isolate cause severe fouling by the formation of a gel layer on the membrane surface that is difficult to remove completely.
The stability of nitrite nitrification with strong nitrogenous wastewater: effects of organic concentration and microbial diversity
Authors: Yun Z. , Jung Y.-H. , Lim B.-R. , Choi E. , Min K.S.
Published: May 2018

A stable achievement of nitritation with strong nitrogenous wastewaters is considered as a difficult task in practice, probably due to the fate of interaction between dominating heterotrophs and nitrifier species. An experimental study was carried out to examine the organic effects in lab-scale biofilm nitritation reactors. The control unit without organic addition showed a stable nitritation performance for more than 220 days of operating period. The nitritation activity gradually failed at the reactors with an organic addition, but the nitritation activity eventually recovered with a prolonged aeration. It was not possible to explain the nitritation recovery with neither free ammonia inhibition concept nor DO competition hypothesis in these cases. The results suggest that the nitritation with organic requires a long start-up period for acclimation. In addition, the results of quinone profile analysis were in agreement with nitritation activity in reactors. The diversity of microbial community in the nitritation reactors could be described by the quinone profiles.
Biohydrogen production by mesophilic fermentation of food wastewater
Authors: Wu J.-H. , Lin C.-Y.
Published: May 2018

Batch experiments were conducted to convert molasses wastewater (10-160 g COD/L) into hydrogen at 35°C at various pH (4-8). The maximum hydrogen productivity (HP) and hydrogen production rate (HPR) reached 47.1 mmol-H2/g CODre and 97.5 mmol-H2/L-day, respectively, at a substrate concentration of 40 g COD/L and pH 6.0. The methane-free biogas contained up to 50% (v/v) of hydrogen. Fermentation at wastewater concentrations higher than 60 g COD/L required a long acclimation period (more than 20 h). Though the fractions were substrate concentration and pH-dependent, acetate and butyrate were the two main liquid fermentation products. A comparison of the HP and HPR data indicates that defining a hydrogen yield indicator to evaluate hydrogen generation efficiency should be taken into consideration in practical fermentation operations.
Activity of sulphate reducing bacteria according to COD/SO42- ratio of acrylonitrile wastewater containing high sulphate
Authors: Byun I.G. , Lee T.H. , Kim Y.O. , Song S.K. , Park T.J.
Published: May 2018

This study was performed to evaluate the biodegradability of acrylonitrile wastewater, microbial inhibition effect of acrylonitrile wastewater on removal efficiency and the activity of sulphate reducing bacteria (SRB) according to COD/sulphate ratio. Acrylonitrile wastewater was hardly biodegradable in a biodegradability test, however, SRB activity was 57% for overall consumption of electron donor and it was relatively high value compared to 17% of reference test with glucose. COD removal of acrylonitrile wastewater was improved to 57% and 61% from 20% as the COD/sulphate ratio were 0.5 and 0.3 by sulphate addition to acrylonitrile wastewater. First order reaction rate constants k on organic removal of acrylonitrile wastewater were 0.001, 0.004 and 0.004 at each COD/sulphate ratio of 0.9, 0.5 and 0.3. Thus it was suggested that the activity of SRB was a significant factor for removing organics and sulphate simultaneously in acrylonitrile wastewater.
Biological nitrogen removal in SBR bypassing nitrate generation accomplished by chlorination and aeration time control
Authors: Peng Y. , Song X. , Peng C. , Li J. , Chen Y.
Published: May 2018

A novel control strategy for biological nitrogen removal with high nitrite built-up through chlorine dosage was studied. In the biological nitrogen removal process operated in a bench-scale sequencing batch reactor, dose of chlorine of 0.2 mg/l in the form of sodium hypochlorite was applied after the COD was depleted. The aerobic phase switched to an anoxic phase shortly after the ammonium was completely biotically oxidized. Nitrite accumulation was stably achieved which was attributed to the chlorination and the lag-time of nitrification. With the time control, stable 100% conversion of nitrite could also be sustained even under the absence of chlorine for at least 20 days. The nitrite oxidizer should have been killed rather than been suppressed in this study. For engineering applications, the advantages of the nitrification/denitrification via nitrite can compensate the cost of chlorine dosage. Combined with the aeration time control, it is feasible to apply chlorination in a biological nitrogen removal process in SBRs.
Denitrification with ɛ-caprolactam by acclimated mixed culture and by pure culture of bacteria isolated from polyacrylonitrile fibre manufactured wastewater treatment system
Authors: Lee C.M. , Wang C.C.
Published: May 2018

The aim of this study is to isolate denitrifying bacteria utilizing ɛ-caprolactam as the substrate, from a polyacrylonitrile fibre manufactured wastewater treatment system. The aim is also to compare the performance of PAN (polyacrylonitrile) mixed bacteria cultures acclimated to ɛ-caprolactam and isolated pure strain for treating different initial e-caprolactam concentrations from synthetic wastewater under anoxic conditions. The result showed that the PAN mixed bacteria cultures acclimated to e-caprolactam could utilize 1538.5 mg/l of ɛ-caprolactam as a substrate for denitrification. Sufficient time and about 2200 mg/l of nitrate were necessary for the complete ɛ-caprolactam removal. Paracoccus thiophilus was isolated from the polyacrylonitrile fibre manufactured wastewater treatment system and it could utilize 1722.5 mg/l of ɛ-caprolactam as a substrate for denitrification. About 3500 mg/l of nitrate was necessary for the complete removal of ɛ-caprolactam. When the initial ɛ-caprolactam concentration was below 784.3 mg/l, the removal efficiency of ɛ-caprolactam by Paracoccus thiophilus was better than that for the PAN mixed bacteria cultures. The growth of Paracoccus thiophilus was better. However, when the initial ɛ-caprolactam concentration was as high as 1445.8 mg/l, both the ɛ-caprolactam removal efficiency by Paracoccus thiophilus and Paracoccus thiophilus specific growth rate were similar to the PAN mixed bacteria cultures.
Nutrition and feed management strategies to reduce nutrient excretions and odors from swine manure
Authors: Sutton A.L. , Richert B.T.
Published: May 2018

Manipulation of the pig's diet to reduce nutrient excretions and odors is feasible and practical. Avoiding excessive dietary protein, using high quality protein sources, and feeding low protein, amino acid supplemented diets are practices that will reduce the N in excreta. Avoiding excessive overages of dietary P, balancing diets on an available P basis, and use of phytase as a dietary supplement offers potential for further reducing the P in manure. Use of reduced or organic forms of Cu, Zn, Fe and Mg will reduce excretion of these nutrients in manure. Feeding management technologies that will enhance feed efficiencies and reduce nutrient excretion include feeding for phase, sex and genetic ability of the animal. Reducing the intact protein levels in diets and balancing with synthetic amino acids, use of low levels of specific non-starch polysaccharides (NSP; soybean hulls, sugar beet pulp), and maintaining the proper acid-base balance and buffering in the diet can significantly reduce odorous compounds. Greater nutrient reductions may be possible through the development of specialty feed ingredients that will be used for specific animal diets. Research to fine-tune the diets for production systems is needed.
Formation mechanism of nitrifying granules observed in an aerobic upflow fluidized bed (AUFB) reactor
Authors: Tsuneda S. , Ejiri Y. , Nagano T. , Hirata A.
Published: May 2018

The influences of trace metals in the wastewater and shear stress by aeration were particularly examined to clarify the formation mechanism of nitrifying granules in an aerobic upflow fluidized bed (AUFB) reactor. It was found that Fe added as a trace element to the inorganic wastewater accumulated at the central part of the nitrifying granules. Another result obtained was that suitable shear stress by moderate aeration (0.07-0.20 L/min/L-bed) promoted granulation. Furthermore, it was successfully demonstrated that pre-aggregation of seed sludge using hematite promoted core formation, leading to rapid production of nitrifying granules. From these results, a nitrifying granulation mechanism is proposed: 1) as a first step, nitrifying bacteria aggregate along with Fe precipitation, and then the cores of granules are formed; 2) as a second step, the aggregates grow to be spherical or elliptical in form due to multiplication of the nitrifying bacteria and moderate shear stress in the reactor, and then mature nitrifying granules are produced. Fluorescence in situ hybridization (FISH) analysis successfully visualized the change in the spatial distribution of nitrifying bacteria in the granules, which supports the proposed granulation mechanism.
Aerobic granular sludge in an SBR-system treating wastewater rich in particulate matter
Authors: Schwarzenbeck N. , Erley R. , Wilderer P.A.
Published: May 2018

Aerobic granular sludge was successfully cultivated in a lab-scale SBR-system treating malting wastewater with a high content of particulate organic matter (0.9 gTSS/L). At an organic loading rate (CODtotal) of 3.4 kg/(m3·d) an average removal efficiency of 50% in CODtotal and 80% in CODdissolved was achieved. Fractionation of the COD by means of particle size showed that particles with a diameter less than 25–50 μm could be removed at 80% efficiency, whereas particles bigger than 50 μm were only removed at 40% efficiency. Tracer experiments revealed a dense sessile protozoa population covering the granules. The protozoa appeared to be responsible for primary particle uptake from the wastewater.
A collection and treatment system for organic waste and wastewater in a sensitive rural area
Authors: Malmén L. , Palm O. , Norin E.
Published: May 2018

In the municipality of Sund, located in a sensitive rural area in Åland, a demonstration project is now carried out with the overall objective to move the most concentrated fractions of wastewater from the coastal area to a treatment plant situated close to arable land. Blackwater and greywater septic sludge from about twenty households and two tourist camps are treated together with energy rich organic material from a nearby potato-chip factory. The collection concept is based on the use of extremely efficient water-saving toilets, with separate systems for the blackwater and greywater in the households. The collected materials are co-treated in a batchwise aerobic thermophilic treatment process (wet composting process), where the materials reach at least 55°C during a minimum of 10 hours. The dry matter content of the collected material was about 2%. After stabilisation and sanitation (by the temperature rise caused by microbial activity during the treatment process), the compost slurry is utilized as a liquid organic fertilizer on arable land.
Cost-effective treatment solutions for rural areas: design and operation of a new package treatment plant for single households
Authors: Daude D. , Stephenson T.
Published: May 2018

The design approach and operation of a newly developed package plant treating domestic sewage from single households were evaluated. Combining submerged aerated filter (SAF) technology with jet aeration and incorporating both into a compact and shallow tank resulted in a cost-effective treatment solution. A trial unit was permanently installed at a rural site, serving a single household. Jet aeration proved to be the best aeration method for the shallow bioreactor design. Further trials revealed a 50% reduction in suspended solids (SS) through the use of a static effluent filter and found that annual plant maintenance was vital to sustain stable operating conditions. Despite high variations in influent conditions, the trial unit produced good effluent quality during steady-state operation. Average effluent BOD5, COD and SS values were 19.6 mg l-1, 98 mg l-1 and 32 mg l-1 achieving overall removal efficiencies of 94.2%, 85.9% and 87.6% respectively. However, effluent ammonia nitrogen (NH4-N) levels were found to be inconsistent varying from 9 mg l-1 to over 60 mg l-1.
Quantification of biofilms in a sub-surface flow wetland and their role in nutrient removal
Authors: Larsen E. , Greenway M.
Published: May 2018

Subsurface flow wetlands contain gravel or sand substrates through which the wastewater flows vertically or horizontally. The aims of this study were, firstly, to quantify biofilm development associated with different size gravel in sections of a subsurface flow wetland with and without plants, and secondly, to conduct laboratory experiments to examine the role of biofilms in nutrient removal. Techniques to quantify biofilm included: bacterial cell counts, EPS and total protein extraction. Based on comparative gravel sample volume, only EPS was greater on the smaller 5 mm gravel particles. There was no significant difference between biofilm growth in sections with and without plants. Two vertical flow laboratory-scale reactors, one containing fresh wetland gravel, the other containing autoclaved gravel, were constructed to determine nutrient transformations. The autoclaved gravel in the “sterile” reactor rapidly became colonised with biofilm. Both reactors were dosed with two types of influent. Initially the influent contained 7.25 mg/L NO3-N and 0.3 mg/L NH4-N; the biofilm reactor removed most of the ammonium and nitrite but nitrate concentrations were only reduced by 20%. In the “sterile” reactor there was negligible removal of ammonium and nitrite indicating little nitrification, however nitrate was reduced by 72%, possibly due to assimilatory nitrate reduction associated with new biofilm development. When the influent contained 3 mg/L NO3-N and 16 mg/L NH4-N almost 100% removal and transformation of NH4-N occurred in both reactors providing an effluent high in NO3-N. Organic P was reduced but inorganic soluble P increased possibly due to mineralisation.
Oxidation processes and clogging in intermittent unsaturated infiltration
Authors: Bancolé A. , Brissaud F. , Gnagne T.
Published: May 2018

Intermittent infiltration of wastewater through a non saturated sand bed is an extensive treatment process aimed at eliminating organic pollution, oxidizing ammonia and removing pathogens. A 1D numerical model, IPOX, has been worked out to simulate the transfer and oxidation of dissolved organic matter and nitrogen in unsaturated sand beds. IPOX was calibrated after real scale tests performed in Spain and Burkina Faso. Simulations allowed us to point out the influence of (i) kinetics on oxidation performances and (ii) biomass development on the process sustainability. These results brought a new light on the sizing and operation of infiltration percolation and soil aquifer treatment (SAT) plants.
Modelling a spatially heterogeneous biofilm and the bulk fluid: selected results from Benchmark Problem 2 (BM2)
Authors: Eberl H.J. , van Loosdrecht M.C.M. , Morgenroth E. , Noguera D.R. , Perez J. , Picioreanu C. , Rittmann B.E. , Schwarz A.O. , Wanner O.
Published: May 2018

The numerical simulation of mass transfer and conversion in spatially heterogeneous biofilms on the meso-scale requires an accurate description of the hydrodynamics in the biofilm systems and of spatial effects. This leads to systems of three-dimensional nonlinear partial differential equations that are numerically very expensive to solve and to data requirements that are not easy to meet. In this paper several modeling approaches to reduce the physical complexity and, hence, accelerate the computation are compared. They range from a mere reduction of dimensionality by lumping the problem along a secondary flow direction to global mass balances or empirical correlations, at the core of which a one-dimensional boundary value problem must be solved. It is found that even strongly simplified models can describe the qualitative behaviour of the model with regard to variations in the geometrical and hydrodynamic model parameters quite well. In order to obtain also quantitatively reliable results the hydrodynamics must be considered in an appropriate manner.
Results from the multi-species Benchmark Problem 3 (BM3) using two-dimensional models
Authors: Noguera D.R. , Picioreanu C.
Published: May 2018

In addition to the one-dimensional solutions of a multi-species benchmark problem (BM3) presented earlier (Rittmann et al., 2004), we offer solutions using two-dimensional (2-D) models. Both 2-D models (called here DN and CP) used numerical solutions to BM3 based on a similar mathematical framework of the one-dimensional AQUASIM-built models submitted by Wanner (model W) and Morgenroth (model M1), described in detail elsewhere (Rittmann et al., 2004). The CP model used differential equations to simulate substrate gradients and biomass growth and a particle-based approach to describe biomass division and biofilm growth. The DN model simulated substrate and biomass using a cellular automaton approach. For several conditions stipulated in BM3, the multidimensional models provided very similar results to the 1-D models in terms of bulk substrate concentrations and fluxes into the biofilm. The similarity can be attributed to the definition of BM3, which restricted the problem to a flat biofilm in contact with a completely mixed liquid phase, and therefore, without any salient characteristics to be captured in a multidimensional domain. On the other hand, the models predicted significantly different accumulations of the different types of biomass, likely reflecting differences in the way biomass spread within the biofilm is simulated.
Removal of ammonia from tannery effluents in a reed bed constructed wetland
Authors: Kucuk O.S. , Sengul F. , Kapdan I.K.
Published: May 2018

A horizontal subsurface flow reed bed, Pragmites australis, constructed wetland system was operated continuously for one year at 5 different hydraulic retention times between 5 days-11 days with real tannery industry effluent to investigate mainly NH4-N and COD removal performance of the system. The bed was also operated at different initial NH4-N concentrations between 10–30 mg/L by adding NH4Cl into the tannery effluent. The results indicated that ammonia-nitrogen removal is significantly affected by hydraulic retention time while COD is not. The optimum HRT was determined as 8 days with over 95% NH4-N and around 30% COD removal efficiency. The system shows higher removal performance at high initial NH4-N concentrations. Almost complete (99%) NH4-N removal and over 40% COD removal was obtained at (NH4-N)0 = 20 mg/L and HRT = 7 days. PO4-P and total chromium removal were not significantly affected by operating conditions
Low cost anaerobic system for Indonesia: single baffled septic tank
Authors: Wibisono G. , Mathew K. , Ho Goen
Published: May 2018

The insertion of a single baffle into a laboratory septic tank to mix incoming feed with sludge has been shown to improve anaerobic degradation of the feed. This is particularly true of soluble organic matter such as glucose. Oil or cellulose fed separately does not undergo degradation. It is expected however that a balanced feed such as sewage will be better degraded.
Treatment of municipal wastewater in a hybrid process using a new suspended carrier with large surface area
Authors: Christensson M. , Welander T.
Published: May 2018

An activated sludge/biofilm hybrid process treating municipal wastewater was studied in pilot plant trials. A new type of suspended carrier, with large effective surface area, was employed in the process with the aim of enhancing nitrification. The pilot plant was operated for 1.5 years in five different configurations including pre-denitrification in all five and enhanced biological phosphorus removal in the final two. The wastewater temperature ranged between 11°C and 20°C, and the nominal dissolved oxygen (DO) level was 5-6 mg/L. The nitrification rate obtained on the new carrier within the hybrid stage was in the range of 0.9-1.2 g NH4-N/m2/d corresponding to a volumetric rate of 19-23 g NH4-N/m3/h (total nitrification including nitrification in the suspended solids). More than 80% of the total nitrification took place on the carrier (and the remainder in the suspended solids). The nitrification rate was shown to correlate with DO, decreasing when the DO was decreased. The results supported the idea of using the new carrier as a tool to upgrade plants not having nitrification today or improve nitrification in activated sludge processes not reaching necessary discharge levels. The large surface area present for nitrification makes it possible to obtain high nitrification rates within limited volumes. The possibility to keep the total suspended solid content low (<3 g/L) and avoiding problems with the filament Microthrix parvicella, are other beneficial properties of the hybrid process.
The UASB reactor as an alternative for the septic tank for on-site sewage treatment
Authors: Coelho A.L.S.S. , do Nascimento M.B.H. , Cavalcanti P.F.F. , van Haandel A.C.
Published: May 2018

Although septic tanks are amply used for on site sewage treatment, these units have serious drawbacks: the removal efficiency of organic material and suspended solids is low, the units are costly and occupy a large area and operational cost is high due to the need for periodic desludging. In this paper an innovative variant of the UASB reactor is proposed as an alternative for the septic tank. This alternative has several important advantages in comparison with the conventional septic tank: (1) Although the volume of the UASB reactor was about 4 times smaller than the septic tank, its effluent quality was superior, even though small sludge particles were present, (2) desludging of the UASB reactor is unnecessary and even counterproductive, as the sludge mass guarantees proper performance, (3) the UASB reactor is easily transportable (compact and light) and therefore can be produced in series, strongly reducing construction costs and (4) since the concentration of colloids in the UASB effluent is much smaller than in the ST effluent, it is expected that the infiltration of the effluent will be much less problematic.
Moving bed biofilm reactors: a small-scale treatment solution
Authors: Daude D. , Stephenson T.
Published: May 2018

The design and operational suitability of the moving bed process for small-scale sewage treatment systems were evaluated. A prototype plant was installed at a new housing development near Winchester, UK, and operated under different conditions over an eight-month period. During normal operation, the MBBR plant produced a good quality effluent with average values for BOD5, COD, SS and NH4-N of 15.6 mg l-1, 65.9 mg l-1, 21 mg l-1 and 4.7 mg l-1, respectively. The plant was further subjected to organic and hydraulic shock loads. The treatment performance remained high over the organic shock period, however, hydraulic surges of up to 10 times the design flow caused a loss of solids from the final settlement stage. While organic carbon removal resumed to over 80% within a single week after a prolonged power failure, effluent NH4-N values remained high for a period of three weeks. Besides producing a good quality effluent, the MBBR plant proved to be simple and reliable to operate, thus providing a viable treatment solution for small-scale applications.
Effect of temperature on the nitrogen removal performance of a sequencing batch reactor treating tannery wastewater
Authors: Murat S. , Insel G. , Artan N. , Orhon D.
Published: May 2018

The effect of temperature on the nitrogen removal performance of the sequencing batch reactor technology is evaluated for tannery wastewater. The study involved the operation of a pilot-scale sequencing batch reactor installed on site to treat the plain-settled effluent. The nitrogen balance of the system is observed for a wide temperature range between 9 to 30°C. The results are evaluated by means of model calibration of COD, nitrate and ammonia nitrogen concentration profiles during cyclic operation. The fates of the major nitrogen parameters are also interpreted on the basis of fundamental stoichiometry for nitrification and denitrification.
Feasibility study of sequencing batch reactor system for upgrading wastewater treatment in Malaysia
Authors: Al-Shididi S. , Henze M. , Ujang Z.
Published: May 2018

The objective of this study was to assess the feasibility of the Sequencing Batch Reactor (SBR) system for implementation in Malaysia. Theoretical, field, laboratory investigations, and modelling simulations have been carried out. The results of the study indicated that the SBR system was robust, relatively cost-effective, and efficient under Malaysian conditions. However, the SBR system requires highly skilled operators and continuous monitoring. This paper also attempted to identify operating conditions for the SBR system, which optimise both the removal efficiencies and the removal rates. The removal efficiencies could reach 90–96% for COD, up to 92% for TN, and 95% for SS. An approach to estimate a full operational cycle time, to estimate the de-sludging rate, and to control the biomass in the sludge has also been developed. About 4 hours react time was obtained, as 2.25 hours of nitrification with aerated slow fill and 1.75 hour of denitrification with HAc addition as an additional carbon source. Inefficient settling was one of the problems that affect the SBR effluent quality. The settling time was one hour for achieving Standard B (effluent quality) and 2 hours for Standard A.
Bioaugmentation of a sequencing batch biofilm reactor by horizontal gene transfer
Authors: Bathe S. , Mohan T.V.K. , Wuertz S. , Hausner M.
Published: May 2018

Bioaugmentation by introduction of catabolic genes residing on mobile genetic elements into the microbial community of a soil or wastewater environment might be an alternative to bioaugmentation by addition of bacterial cells with chromosomally encoded catabolic genes. This study investigates the possibility to enhance degradation of the xenobiotic model compound 2,4-dichlorophenoxyacetic acid in a sequencing batch biofilm reactor (SBBR) by using the conjugative plasmid pJP4 carrying genes for 2,4-D degradation. After introduction of a plasmid donor strain to a lab-scale SBBR operated without 2,4-D, the number of plasmid-carrying cells first dropped, and then increased after switching to 2,4-D as the sole carbon source. The donor cells were unable to grow in the applied synthetic wastewater with 2,4-D as the sole carbon source. Transconjugants could be detected both by culture-dependent and culture-independent methods in the 2,4-D degrading biofilm. In contrast to 90% 2,4-D degradation in the bioaugmented reactor within 40 h, a control reactor which had not received the plasmid still contained 60% of the initial 2,4-D concentration after 90 h. This experiment clearly demonstrates the introduction of 2,4-D degradative genes into a microbial biofilm and indicates that horizontal gene transfer is a promising tool for bioaugmentation of reactors treating wastewater.
Optimizing nitrogen removal in the BioDenitro process
Authors: Irizar I. , Suescun J. , Plaza F. , Larrea L.
Published: May 2018

The potential and limits of different configurations of the BioDenitro-alternating process to suit the various design cases that can arise depending on the wastewater characteristics, space necessary and effluent nitrogen requirements were analysed through simulations of the activated sludge model No. 2. The first analysis involved the combination in one cycle of the main phase in the alternating reactors with an aerated phase having the two reactors in aerobic conditions and/or a hydraulic phase using the flow only in the anoxic reactor. This option has been found to have a very high potential for cases with strict requirements concerning effluent total nitrogen, but limited when the requirements are low effluent NH4-N, relatively high effluent total nitrogen and minimum solids and hydraulic retention times. When the latter conditions have to be fulfilled the incorporation of a post-aeration reactor to the alternating reactor was found to be very effective. In addition the configuration is very flexible because multiple combinations of post-aeration reactor volumes and in the duration of the different phases in the alternating reactors can be selected to achieve effluent nitrogen requirements. This flexibility is limited to the use of moderate values in the post-aeration reactor volumes and in the duration of the aerated phase. An experimental trial of the latter configuration was carried out and demonstrated its operational simplicity by achieving the desired nitrogen requirements in the effluent simply by changing the duration of the aerated phase for a given post-aeration reactor volume. From the experimental results an enhanced simultaneous nitrification-denitrification at the start of aeration in the alternating reactors was found and the ASM2 model was shown to have a satisfactory predictive capacity.
Biofilm bacteria inactivation by citric acid and resuspension evaluations for drinking water production systems
Authors: Tsai Y.P. , Pai T.Y. , Hsin J.Y. , Wan T.J.
Published: May 2018

The study investigates the inactivation of biofilm bacteria colonized on the surface of polyvinyl chloride (PVC) pipes delivering either groundwater or treated wastewater. It does so using a citric acid (C6H8O7) solution. The results of the study showed that the optimal conditions of the biofilm bacteria inactivation were over 10,000 mg/L citric acid concentration and 60 minutes of contact time at least. Under these conditions, the removal efficiency could reach above 99.999% for heterotrophic plate count (HPC) bacteria and 99.95% for coliform bacteria. The study also showed that the biofilm bacteria were the major sources of planktonic bacteria resuspended into water purified by drinking water production systems (DWPS).
Use of reflectors to enhance the synergistic effects of solar heating and solar wavelengths to disinfect drinking water sources
Authors: Rijal G.K. , Fujioka R.S.
Published: May 2018

Aluminum reflectors were added to solar units designed to inactivate faecal microorganisms (faecal coliform, E. coli, enterococci, FRNA coliphage, C. perfringens) in stream water and diluted sewage by the two mechanisms (solar heat, solar UV) known to inactivate microorganisms. During sunny conditions, solar units with and without reflectors inactivated E. coli to <1 CFU/100 ml to meet drinking water standards. Solar units with reflectors disinfected the water sooner by increasing the water temperature by 8-10°C to 64-75°C. However, FRNA coliphages were still detected in these samples, indicating that this treatment may not inactivate pathogenic human enteric viruses. During cloudy conditions, reflectors only increased the water temperature by 3-4°C to a maximum of 43–49°C and E. coli was not completely inactivated. Under sunny and cloudy conditions, the UV wavelengths of sunlight worked synergistically with increasing water temperatures and were able to disinfect microorganisms at temperatures (45-56°C), which were not effective in inactivating microorganisms. Relative resistance to the solar disinfecting effects were C. perfringens > FRNA coliphages > enterococci > E. coli > faecal coliform.
Kinetic study of reactions between ozone and benzothiazole in water
Authors: Valdés H. , Zaror C.A. , Jekel M.
Published: May 2018

Benzothiazoles are frequently present in wastewater from rubber related applications, and may be found in surface and underground water bodies causing significant environmental impact. Cost effective treatment processes to deal with such contaminants are needed in both small and large-scale applications. These compounds are poorly biodegradable and could be removed by ozone oxidation before discharge to recipient water courses. Unfortunately, there is limited experimental data reported in the literature on such processes involving benzothiazoles. This article presents experimental data on ozone treatment of benzothiazole (BT), with a view to process design. The effects of pH and radical scavengers on process rate and removal efficiency were assessed at bench scale. Experimental results show that BT could be effectively removed using ozonisation, particularly at pH above 4. The presence of free radical scavengers drastically reduced the BT removal rate even at very low concentrations. Both direct and indirect reactions between ozone and BT were adequately described by second order kinetic schemes, with rate constants estimated at 20°C: kD = 2.3 mol l-1 s-1 and kI = 6 × 109 mol l-1 s-1, respectively. The free radical mechanism accounted for 83–96% of BT removal rate within the pH range 2–9, at 20°C.
β-endosulfan removal from water by ozone oxidation
Authors: Yazgan M.S. , Kinaci C.
Published: May 2018

β-endosulfan solutions were ozonated in a lab scale semi-batch reactor in various experimental conditions. Ozonation kinetics of β-endosulfan and effects of some parameters such as pH, temperature, partial pressure and ozone dosage on oxidation were investigated. Increasing ozone dosage and decreasing of temperature and pH increased the oxidation rate of β-endosulfan. Maximum 97% of β-endosulfan could be removed at both 16-mg/min ozone dosages and pH = 4 for 60 minutes of ozonation. The order of the reaction is determined as pseudo first order. Although the rate of reaction was lower than other pesticide oxidation rates cited in the literature, β-endosulfan reaction to ozonation was achieved with almost 90% removal rate. The temperature dependent rate constant for β-endosulfan oxidation was determined as kd = 0.947 exp(-2.16 × 10-3/T).
Regulated Deficit Irrigation (RDI) to save water and improve Sauvignon Blanc quality?
Authors: Greven M. , Green S. , Neal S. , Clothier B. , Neal M. , Dryden G. , Davidson P.
Published: May 2018

With a fast change of land use in Marlborough from extensive pastoral farming to intensive irrigated viticulture, a need has risen to investigate the sustainable use of the available water. In 2001 a 5 ha irrigation research project was installed in a Marlborough Sauvignon Blanc vineyard. Irrigation treatments installed were control (compensate 100% for crop evapotranspiration (ETO)), 80%, 70% and 60% of ETO. During the two years that the Regulated Deficit Irrigation (RDI) trial has run so far, very different climatic conditions created much greater differences in yield and vegetative growth, than up to 40% reduction in irrigation, none of which were significant. The use of sap flow in the vines has been fine-tuned and is now giving reliable results on which to base vine water need.
Wastewater planning in Djenné, Mali. A pilot project for the local infiltration of domestic wastewater
Authors: Alderlieste M.C. , Langeveld J.G.
Published: May 2018

The city of Djenné (Mali) is famous for its mosque which is the world's largest adobe building. Djenné is considered to be one of the most interesting cities in Western Africa from an architectural point of view. Since 1988, Djenné is listed as a UNESCO World Heritage Site. In the 1990s, a drinking water supply network was provided by foreign development organisations. However, no facilities were provided for the disposal of wastewater, resulting in an increase of waterborne diseases.

This paper describes the urban drainage problem in Djenné and discusses the systematic evaluation of possible solutions and the subsequent pilot project for the local infiltration of sullage. The infiltration of sullage proved to be an appropriate technology for solving the urban drainage problem in Djenné.