bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling the embedded rainfall process using tipping bucket data
Authors: Thyregod Peter , Arnbjerg-Nielsen Karsten , Madsen Henrik , Carstensen Jacob
Published: May 2018

A new method for modelling the dynamics of rain measurement processes is suggested. The method takes the discrete nature and autocorrelation of measurements from the tipping bucket rain gauge into consideration. The considered model is a state space model with a Poisson marginal distribution. In the model there is only one parameter, a thinning parameter. The model is tested on 39 rain events. The estimated value for the various rain events is reflecting a subjective classification of rain events into frontal and convective rain. Finally, it is demonstrated how the model can be used for simulation and prediction.
Environmental monitoring initiatives to sustain growth in Ontario, Canada
Authors: Palmer R. M. , Jones C. , Walters M.
Published: May 2018

Sustainability, which attempts to balance environmental preservation and economic growth, includes puzzling problems such as better managing the world's water resources and enhancing the quality of life.

Municipalities within the Nottawasaga Valley and Lake Simcoe Watersheds, north of Toronto, are now considered to have a high potential for significant growth. Both watersheds form part of the Georgian Bay ecosystem, within the Great Lakes Basin. Integrated watershed management planning by the Nottawasaga Valley and Lake Simcoe Region Conservation Authorities is protecting water resources and ensuring the availability of water servicing for controlled development. This includes the maintenance of streamflows for the assimilation of treated sewage effluent from headwater basins and protection of unimpaired aquatic habitat at the same time.

Monitoring the performance and success of the watershed plans is a vital component to sustain a healthy ecosystem pulse while accommodating growth. The comprehensive GIS based, multi-partnered monitoring program being used is unique. This low-cost, transferable approach for watershed monitoring includes a biological method known as BioMAP. The monitoring program has a proven track record for pre-design and post-construction stages of new development. Various case studies are presented.
Influence of systematic errors from tipping bucket rain gauges on recorded rainfall data
Authors: Fankhauser Rolf
Published: May 2018

Tipping bucket rain gauges (TBR) are widely used in urban hydrology. The present study investigated the uncertainties in recorded rainfall intensity induced by the following properties of the TBR: depth resolution i.e. the bucket volume, calibration parameters, wetting and evaporation losses and the method of data recording (time between tips or tips per minute). The errors were analysed by means of a TBR simulator i.e. a simulation program that models the behaviour of a TBR. Rainfall data disaggregated to 6 seconds from measured 1-min data and randomly varied were taken as input to the simulator. Different TBR data series were produced by changing the properties of the simulated rain gauge. These data series together with the original rainfall events were used as input to a rainfall-runoff model. Computed overflow volume and peak discharge from a combined sewer overflow (CSO) weir were compared. Errors due to depth resolution (i.e. the bucket size) proved to be small. Therefore TBRs with a depth resolution up to 0.254 mm can be used in urban hydrology without inducing significant errors. Wetting and evaporation losses caused small errors. The method of data recording had also little influence. For larger bucket volumes variable time step recording induced smaller errors than tips per minute recording.
Characterisation of dredged materials
Authors: Förstner U. , Calmano W.
Published: May 2018

Management of contaminated sediments requires - similar to other waste materials - a holistic approach. In addition to the common predictive techniques for estimating contaminant losses - a priori techniques and pathway-specific tests - the interactive nature of various parameters has to be recognized. This means, that particular emphasis should be placed on the evaluation of the two data sets “driving force/geochemical gradient” parameters (mostly redox-sensitive components, which may be critical for the “acid producing capacity”) and “capacity controlling properties” (with prevalence of “carbonate content”). Assessment of these parameters and their long-term borderline conditions, as well as the potential links between the two sets of geochemical properties and of individual parameters should be an integrated part of the wider management scheme, i.e., the analytical and experimental parameters should always be related to the potential remediation options for a specific sediment problem.
Correction and preparation of continuously measured raingauge data: a standard method in North Rhine-Westphalia
Authors: Maul-Kötter B. , Einfalt Th.
Published: May 2018

Continuous raingauge measurements are an important input variable for detailed rainfall-runoff simulation. In North Rhine-Westphalia, more than 150 continuous raingauges are used for local hydrological design through the use of site specific rainfall runoff models. Requiring gap-free data, the State Environmental Agency developed methods to use a combination of daily measurements and neighbouring continuous measurements for filling periods of lacking data in a given raindata series. The objective of such a method is to obtain plausible data for water balance simulations. For more than 3500 station years the described methodology has been applied.
Trace metals in fine grained sediments of the Kaštela Bay, adriatic sea
Authors: Bogner D. , Juracic M. , Odžak N. , Baric A.
Published: May 2018

The aim of the present work was to study the past and present contamination of the Kaštela bay using chemical analysis of selected trace metals (Cd, Pb, Zn, Cu, Cr, Mn and Ni) in fine grained sediment cores. Sediment samples were taken at three locations with silty sediments. The highest concentrations of Cd, Pb, Cu and Zn and the lowest concentration of Ni were found in the east, the most contaminated part of the Bay. The decrease of Cd, Pb, Cu and Zn concentrations with increased depth, indicates their anthropogenic origin. Homogeneous distribution of Cr, Mn and Ni in the sediment cores indicates their terrigenous origin. The correlation of Zn, Cu and Ni concentration with the organic matter content was determined.
Monitoring of a water basin area in Istanbul using remote sensing data
Authors: Goksel Cigdem
Published: May 2018

In this study, using Landsat-TM Images (1984 and 1992), land-use/land-cover characteristics in Istanbul's Elmali Water Basin Area were analysed and evaluation of thematic and positional accuracy of images was performed. High accuracy raster data were converted to vectorial data and used in Geographic Information Systems. A data base to be used for water basin planning and managing, utilising statistical attribute data covering population, water potential, topographic position, industry and labour force was prepared and overlay analysis was carried out. Finally, comparison between water basin protected areas in 1984 and 1992 using GIS techniques was performed and results were illustrated on three dimensional surface models.
Issues of sustainability and pollution prevention in environmental engineering education
Authors: Gutiérrez-Martín F. , Dahab M. F.
Published: May 2018

This paper discusses the concepts of sustainability and pollution prevention and their roles in environmental science and engineering education. It is argued that environmental engineering science and education must be re-oriented to focus primarily on pollution prevention technologies as a mechanism for attaining the goal of sustainability. While it is acknowledged that traditional pollution control will remain as an integral part of environmental science and engineering education, the paradigm shift (in favor of pollution prevention) must be completed in order for humanity to realize, albeit remotely, the goal of sustainability. The paper presents two case studies; at the University of Nebraska-Lincoln (USA) and at the Universidad Politécnica de Madrid (Spain) where efforts are being made to re-orient environmental engineering education to promote the concept of sustainability as the primary goal of environmental management.
Computer simulation models in environmental engineering education
Authors: Egemen E. , Edwards F. , Nirmalakhandan N.
Published: May 2018

The traditional lecture-based teaching process has been criticized as a passive knowledge delivery process with much room for improvement in the teaching-learning process. It is now recognized that one of the essential prerequisites for improving the teaching-learning process is active and interactive participation of the students, both in and out of the classroom. In this paper, computer simulation models are identified as an effective teaching aid to promote active participation between student and teacher as well as among students. Using a sample simulation model, the different ways in which models in general can be used to encourage active and interactive participation are discussed. It is concluded that the use of such computer simulation models is appealing to students with diverse learning styles.
Instrumentation, control and automation progress in the United States in the last 24 years
Authors: Garrett M. Truett
Published: May 2018

A historical overview is presented of instrumentation control and automation as applied in US wastewater treatment plants. A description is given how computer equipment has progressed through direct digital control, distributed control, programmable logic controllers, to the use of personal computers along with PLC's or I/O boards in minimum systems. Software developments have brought systems analysis, expert systems, fuzzy logic control, and artificial neural network control. An instrumentation test house has been organized in the US to improve the odds of purchasing reliable instruments. Technical Conferences on ICA are presented regularly by the American Water Works Association and the Water Environment Association. There is still need for designers to consider a complete system that includes a data base for automatic preparation of reports on the plant for use at other levels as was called for by delegates to the early workshops.
Bacteriophages and bacteria as indicators of enteric viruses in oysters and their harvest waters
Authors: Chung H. , Jaykus L.-A. , Lovelace G. , Sobsey M. D.
Published: May 2018

Reliable indicators are needed to detect enteric virus contamination of bivalve molluscan shellfish and their harvest waters. Concentrations of male-specific (F+) coliphages, Bacteroides fragilis phages, Salmonella phages and several indicator bacteria in wastewater, estuarine receiving water and its oysters were examined for their ability to predict the presence and levels of faecal contamination and enteric viruses in oysters. Enteric viruses in oysters were detected by cell culture and RT-PCR methods. F+ coliphages, Salmonella phages, B fragilis phages and faecal indicator bacteria (faecal coliforms, E coli, enterococci and Clostridium perfringens) were generally positively associated and were highest in raw sewage and progressively lower in sewage effluent and in receiving waters at increasing distance from the wastewater discharge. Indicator levels in oysters were highest for F+ coliphages and C perfringens. One F+ RNA coliphage serotype (Group II) predominated in the wastewater, receiving water and oysters. Human enteric viruses were detected in 17/31 oyster samples. The levels of most indicators in oysters and water were higher when oysters were enteric virus-positive and lower when oysters were enteric virus-negative. F+ coliphages and C perfringens were the only indicators significantly associated with the presence of enteric viruses in oysters. F+ coliphages and their serotypes are promising indicators of human enteric virus contamination in oysters and their harvest waters.
Combined sewer overflows: a source of cryptosporidium and giardia?
Authors: Gibson C. J. , Stadterman K. L. , States S. , Sykora J.
Published: May 2018

Throughout the past several years there has been an increasing concern to reduce the pollutants within urban stormwater discharges, particularly combined sewer overflows (CSOs). The majority of the research on CSOs has focused on physical, chemical, and some biological components. This preliminary study investigated the occurrence of two pathogenic protozoa, Cryptosporidium and Giardia, in an urban stream during dry weather compared to their occurrence in a combined sewer overflow (CSO) end-of-pipe discharge to determine the loading potential and the potential human health impacts. Cryptosporidium oocysts and Giardia cysts were commonly observed in the urban stream during dry weather conditions, with concentrations of 5-105 oocysts/100L and 13-6,579 cysts/100L respectively. The CSO end-of-pipe samples during wet weather conditions discharged Cryptosporidium and Giardia at high levels, 250-40,000 oocysts/100L and 9,000-283,000 cysts/100L respectively. This preliminary study suggests that CSOs may significantly contribute to the load of Cryptosporidium and Giardia in ambient waters and source waters utilized for recreational use and potable water. However, further investigation will be needed to determine and characterize the full effect of this apparent loading source.
Correlation of combined sewer overflow reduction due to real-time control and resulting effect on the oxygen concentration in the river
Authors: Rauch W. , Harremoës P.
Published: May 2018

Real-time control of the sewer system is a frequently applied measure for the abatement of pollution caused by urban runoff in the receiving water. Although the goal is an improvement of the water quality the actual aim of real-time control is usually formulated as the reduction/avoidance of combined sewer overflow. However, testing a virtual drainage system by means of a three-month rain series, hardly any correlation between the combined sewer overflow reduction and the resulting effect on the oxygen concentration in the river has been found. The efficiency of real-time control for pollution abatement by means of artificial performance criteria has to be doubted.
Evaluation of a rapid method for E coli and thermotolerant coliforms in recreational waters
Authors: Robertson W. , Palmateer G. , Aldom J. , Van Bakel D.
Published: May 2018

The management of recreational beaches based on the standard methods for E coli or thermotolerant coliforms can present a challenge to public health officials. Typically there is a 30-48h delay between sample collection and availability of results. Bacteriological water quality can change significantly during this period. During 1995 and 1996, a rapid method, based on the production of glucoronidase by E coli or galactosidase by thermotolerant coliforms, was developed to shorten this delay. During the summer of 1997, the rapid method was compared to the standard membrane filtration technique for E coli. Using 563 comparisons, the correlation for E coli detected by the rapid method and membrane filtration yielded a r2 = 0.89. The percent agreement between the methods based on the number of times both provided results above or below the provincial objectives of 100 E coli/100mL was 84.6%. Similar results were obtained for 1,168 comparisons of thermotolerant coliform data. Using the rapid method, results for samples collected in the morning are available by the afternoon of the same day. The rapid method not only allows for the prompt closure of beaches but also maximises the times when the beaches are open.
Application of optical monitor to evaluate the coagulation of pulp wastewater
Authors: Shanshan Chou , Shihcheng Lin , Chihpin Huang
Published: May 2018

Coagulation/flocculation process is an important part of the solid/liquid separation in a wastewater treatment plant. However, conventional methods to determine coagulant dosage have led to poor results in real-time dosing control for the highly changeable quality of influent. In this study, we employ the photometric dispersion analyzer (PDA) to assess the feasibility of monitoring pulp suspended solids coagulation in pulp wastewater by batch trials. The use of PDA in the batch system to monitor the coagulation of filamentous microorganisms is also included. Batch test results indicate that PDA monitoring is an effective technique to reflect the state of aggregation of filament- and fiber-type solids and, therefore, can provide as a reliable index for determining the optimal dosage. In addition, in our coagulant dosing control system, the monitoring point of PDA should be set at the effluent of the rapid mixing unit. We also assess the feasibility using PDA monitoring in a continuous system simulating the wastewater treatment processes. Results demonstrate that stable PDA output can accurately reflect the changes of influent turbidity and coagulant dosage.
Influent flow control to increase the pollution load treated during rainy periods
Authors: Dauphin S. , Joannis C. , Deguin A. , Bridoux G. , Ruban G. , Aumond M.
Published: May 2018

The European Directive of May 1991 concerning urban wastewater treatment points out that sewerage systems must be designed to limit the pollution of receiving watercourses by stormwater discharges. As for the system management, the French Decree of 22 December 1995 states that flows or pollution loads exceeding the reference capacity of the treatment plant may be temporarily admitted. This is especially interesting in the case of separate wastewater sewerage, as inappropriate connections of runoff water and rainfall induced infiltration cause hydraulic overloads in such networks. An automated influent flow control has been implemented on a 8000 population equivalent plant to admit a maximum of twice the dry weather peak flow: the clarifier is then dynamically managed so that neither sludge loss nor degradation through anoxic conditions may occur. A yearly simulation of such a strategy on a smaller treatment plant shows a very significant reduction (90%) of the volume discharged during rainy periods. It can therefore be concluded that a plant with additional hydraulic capacity and good sludge quality can play a significant role in limiting the stormwater discharges from separate sewerage systems. However this operational benefit depends on the inflow composition in the sewerage system (wastewaters, rain and infiltration waters).
Load dependent control of BNR-WWTP by dynamic changes of aeration volumes
Authors: Thomsen Henrik A. , Nielsen Marinus K. , Nielsen Evald H. , Hansen Niels P.
Published: May 2018

The consequences of a heavy and varying load on a BNR-WWTP (biological nitrogen removing plant) have been investigated in full scale. The investigations took place at a 57.000 PE BNR plant which is operated according to the BIODENITRO principle. The plant had been heavily overloaded with BOD and N, 2–3 times the designed capacity. During the overload events, the BOD was efficiently removed to below the effluent limit. The N-removal, however, was reduced to below 50% during these events. The nitrification may be inhibited considerably after peak loadings due to a drop in pH caused by nitrification without denitrification. Full denitrification was obtained during peak loadings in spite of aeration of the total process volume. During high and varying loads, the most efficient utilisation of the process volume can be obtained by the following: 1) The plant design should allow of a change in aeration volume from 20% to 100% of the total process volume. Changing the aeration volume is much more effective than changing the oxygen set point. 2) On-line control of the aeration time by NH4, NO3 and pH on-line meters. The historic loadings must be included in the control strategy to avoid alkalinity depletion during heavy load variations.
A quantitative and qualitative study of biofilm disinfection on glass, metal and PVC surfaces by chlorine, bromine and bromochloro-5,5 dimethylhydantoin (BCDMH)
Authors: Armon R. , Arbel T. , Green M.
Published: May 2018

The present study was conducted on artificial biofilm formed in a laboratory water system using three support surfaces: glass, galvanised iron and polyvinyl chloride (PVC). Biofilm formation was followed by direct count on R2A medium and by scanning electron microscope (SEM) examination. As described, the development of biofilm was not the same on the various surfaces. Biofilm formed on various surfaces had different disinfection patterns as shown by the experimental data. Chlorine was the most efficient disinfectant against biofilm developed on glass and metal surfaces but less effective on PVC. Disinfection of glass and PVC biofilms with bromine was much less effective. Bromochloro-5,5 dimethylhydantoin (BCDMH) was very effective on galvanised iron, less effective on PVC and almost no effect was observed on glass surfaces. Addition of EDTA (1mM) to the biofilm system, prior to disinfection, was more effective in killing the biofilm bacteria, probably due to chelation of divalent ions (Ca2+,Mg2+) which open the matrix and allow the disinfectant to penetrate easily. Maintaining the system at certain BCDMH concentrations, following a disinfection shock with bromine and chlorine, allowed the system to remain at a low level of bacteria. SEM inspection made it possible to follow the biofilm organisation on the various surfaces before and after disinfection. Following disinfection, on all surfaces, the biofilm bacteria seemed to be “flat” and, after addition of EDTA, detachment of the extracellular polysaccharide polymer (EPS) from the surface was observed. It seems that the EPS perforation process allowed better penetration of the disinfectant into the biofilm barrier affecting bacterial viability. The various chemical and microbiological aspects of biofilm disinfection and future practices are discussed.
Disturbance detection in wastewater treatment plants
Authors: Rosen C. , Olsson G.
Published: May 2018

The development in sensor technology has made many wastewater treatment systems data rich but not necessarily information rich. To extract the adequate information from several sensors is not trivial, and it is not sufficient to consider only the time series. Different tools for detecting unusual on-line measurement data and deviating process behaviour are discussed. In this paper various dimension reduction as well as advanced filtering methods are considered in order to extract adequate information for fault detection and diagnosis. Both the operator and the process engineer can take advantage of such methods for proper monitoring of the plant, in particular extreme events and their causes.
An instrument for the measurement of colour and turbidity in natural waters
Authors: Edwards Henry O.
Published: May 2018

The development of a sensor to measure colour and turbidity of natural waters is described. Filtration of the water is not required, so maintenance intervals and costs will be reduced. A four-beam intensity compensation technique is used for robust measurement and resistance to fouling. Results of the operation of a prototype at a water treatment works are presented.
Selection of operational strategies in activated sludge processes based on optimization algorithms
Authors: Ayesa E. , Goya B. , Larrea A. , Larrea L. , Rivas A.
Published: May 2018

This paper presents a new optimization algorithm for the selection of design and operation parameters in complex Activated Sludge (AS) processes. The algorithm estimates automatically the dimensions and operating point of the plant that minimize a global penalty function combining effluent requirements and costs. The mathematical optimization is based on a direct search algorithm integrated in a previously developed simulation package.

Some illustrative examples concerning the design and operation of the Alpha process have been included to show the potential of this kind of mathematical tool when the complexity of plant configuration increases. The results obtained by the optimization procedure generate useful guidelines for the design and operation and suggest a great potential in the application for solving more complex problems when additional objectives and costs are included.
Causes of, and control strategies for, Microthrix parvicella bulking and foaming in nutrient removal activated sludge systems
Authors: Mamais D. , Andreadakis A. , Noutsopoulos C. , Kalergis C.
Published: May 2018

Bench and pilot scale nutrient removal activated sludge units were used to examine the effect of factors such as temperature, substrate type (easily biodegradable in the form of acetate and slowly biodegradable in the form of oleic acid) on Microthrix parvicella growth. The configurations examined include complete mix with and without selectors (anoxic and anaerobic) and plug flow reactors. The results indicate that low temperatures and substrates in the form of long chain fatty acids favour the growth of M. parvicella. With respect to reactor configuration, a plug flow configuration was shown to be quite effective in controlling the growth of M. parvicella and producing a sludge with good settling characteristics, while the presence of a selector, either anoxic or anaerobic, had no significant effect on the growth of M. parvicella.
Modelling of activated sludge for textile wastewaters
Authors: Babuna F. Germirli , Orhon D. , Çokgör E. Ubay , Insel G. , Yaprakli B.
Published: May 2018

A comprehensive evaluation of four different textile wastewaters was carried out to set the experimental basis for the modelling of activated sludge process. Experiments involved beside conventional characterization, detailed COD fractionation and assessment of major kinetic and stoichiometric coefficients by means of respirometric measurements. A multi-component model based on the endogenous decay concept was used for the kinetic interpretation and design of activated sludge. The fate and variation of major process components affecting effluent quality with the sludge age were evaluated by means of model simulations.
In situ characterization of substrate uptake by Microthrix parvicella using microautoradiography
Authors: Andreasen Kjær , Nielsen Per Halkjær
Published: May 2018

Microthrix parvicella is a filamentous microorganism responsible for bulking and foaming problems in many activated sludge treatment plants. The problems have increased with the introduction of nutrient removal in many countries, and presently, there is no reliable control strategy for M. parvicella. Little is known about the physiology of M. parvicella, and conflicting data exist about its preferred organic substrates, and whether it is able to be physiologically active under anaerobic and anoxic conditions. In this study, the ability of M. parvicella to take up various radioactively labeled organic compounds was investigated in situ at three nutrient removal plants using a microautoradiographic technique. Of 12 compounds tested under aerobic conditions only the long chain fatty acids (LCFA), oleic acid and palmitic acid, and to some extent a lipid, trioleic acid, were assimilated. None of the simple substrates such as acetate, propionate, butyrate, glucose, ethanol, glycine and leucine were taken up. Furthermore, the uptake of oleic acid was compared under anaerobic, anoxic and aerobic conditions, and it was demonstrated that in addition to aerobic conditions M. parvicella was also able to take up oleic acid under anaerobic and anoxic conditions. No difference in substrate uptake pattern for M. parvicella was found among the tested activated sludge plants. The results strongly indicate that a better control strategy against M. parvicella must rely on a better understanding of presence and availability of triglycerides and LCFA, and an improved knowledge of the physiology of M. parvicella under anaerobic and anoxic conditions.
The anaerobic treatment of a ligno-cellulosic substrate offering little natural pH buffering capacity
Authors: Banks C. J. , Humphreys P. N.
Published: May 2018

The stability and operational performance of single stage digestion with and without liquor recycle and two stage digestion were assessed using a mixture of paper and wood as the digestion substrate. Attempts to maintain stable digestion in both single stage reactors were unsuccessful due to the inherently low natural buffering capacity exhibited; this resulted in a rapid souring of the reactor due to unbuffered volatile fatty acid (VFA) accumulation. The use of lime to control pH was unsatisfactory due to interference with the carbonate/bicarbonate equilibrium resulting in wide oscillations in the control parameter. The two stage system overcame the pH stability problems allowing stable operation for a period of 200 days without any requirement for pH control; this was attributed to the rapid flushing of VFA from the first stage reactor into the second stage, where efficient conversion to methane was established. Reactor performance was judged to be satisfactory with the breakdown of 53% of influent volatile solids. It was concluded that the reactor configuration of the two stage system offers the potential for the treatment of cellulosic wastes with a sub-optimal carbon to nitrogen ratio for conventional digestion.
Common anaerobic treatability of pharmaceutical and yeast industry wastewater
Authors: Gulmez B. , Ozturk I. , Alp K. , Arikan O. A.
Published: May 2018

The purpose of this study is to demonstrate the feasibility of anaerobic treatment of pharmaceutical and baker's yeast industry effluents in a joint treatment system. Anaerobic treatability studies have been performed in a lab-scale upflow anaerobic sludge blanket reactor (UASBR). The experimental study has been carried out for 333 days. The influent COD's during the experimental study were about 10,000 mg/l. Pharmaceutical wastewater has a 5% of inhibition on the COD removals at the dilution rate of 1/100 or more in the joint anaerobic treatment with baker's yeast industry effluents. Maximum inhibition of 10% on the average was observed when the system was characterized with acclimation periods. The study has shown that, following the solvent extraction with pre-aeration process, a common anaerobic treatment can be applied to baker's yeast industry wastewater and to pharmaceutical industry effluents.
Control of heavy metal emission from metal plating industry in a german river basin
Authors: Bode Harro
Published: May 2018

The introduction of clear limits for the indirect discharge of heavy metals in Germany has greatly reduced the emissions from metal plating industry. Despite the more than 500 metal plating workshops within the Ruhr catchment area the current requirements for water quality of riverwater are met in the Ruhr (even the German limit values for drinking water are met). Nevertheless the industrial emissions into the sewers are still above the permitted level and above what routine checks of the industrial effluents lead to believe. Thus with respect to the German wastewater sludge regulation half of the dry sludge solids must be excluded from agricultural use. The complete implementation of legal requirements by all workshops will further diminish the heavy metal emissions into wastewater sludge and receiving waters.
Biological fluidized bed treatment of ethylene and propylene glycols
Authors: Shieh Wen K. , Lepore John A. , Zandi Iraj
Published: May 2018

The bioremediation of ethylene and propylene glycols using the aerobic biological fluidized bed (BFB) technology is evaluated. Under the steady-state conditions tested, the BFB reactors are capable of achieving good TOC removal (i.e., >96%) at empty bed HRTs as short as 1.7 hrs and at TOC loadings as high as 0.88 g/L-day. In addition, the BFB reactors are also capable of sustaining good TOC removal (i.e., >87%) during single-pulse loadings with a 10-fold increase in pulse magnitude and pulse durations as long as 7 hrs. The observed BFB process efficiency and stability are attributable to the high immobilized biomass inventories attained in reactors by using porous media particles for cell immobilization and retention.
Modelling simultaneous removal of trichlorfon and glucose in a hybrid bioreactor containing magnetically immobilized biomass
Authors: Chen Guang Hao , Ozaki Hiroaki , Terashima Yutaka
Published: May 2018

This paper focuses on a simultaneous removal of trichlorfon and glucose that was added as carbon source for degradation requirement of trichlorfon. A hybrid bioreactor, having both suspended and magnetically immobilized biomass, was used for investigating this removal of both substances. To evaluate the respective roles of these two types of biomass, a mathematical model was developed and also verified well with experimental results. It has been found that the suspended biomass plays a key role in removing both substances in the system. This is due to complete coexistence of both trichlorfon-degrading and glucose-removing bacteria completely in each type of the biomass. Such a system would be applicable to the treatment of complex industrial wastewaters that contain easily biodegradable organics as well as refractory pollutants.
Heavy metal sequestration properties of a new amine-type chelating adsorbent
Authors: Navarro R. R. , Sumi K. , Matsumura M.
Published: May 2018

The performance of poly(CGMAPEI), an amine-type chelating adsorbent synthesized by graft polymerization, was evaluated in a simulated waste stream containing Cu2+ and Co2+ heavy metal ions and NaNO3 salt. Comparisons of metal adsorption curves of this adsorbent with a previously synthesized cellulose-PEI and commercially available chitosan-polyamine and amberlite resins were made. The poly(CGMAPEI) exhibited the highest capacity in the absence of NaNO3. At high concentrations of NaNO3, the affinities of all the amine-type adsorbents were found to be enhanced quite tremendously. The chelating adsorbent with the highest amine content (CS-03) showed the highest improvement in capacity. This phenomenon was not observed with the ion-exchanger (amberlite IRC 50) studied. Sodium ions showed negligible affinity for poly(CGMAPEI). Competition between Na+ with Cu2+ for adsorption sites in the adsorbent was absent. Regeneration experiments revealed some reduction in Cu2+ affinity of poly(CGMAPEI) after acid treatment. Difficulty in stripping Co2+ from poly(CGMAPEI) even by strong acid was also observed.
Biodegradation of RDX-contaminated wastes in a nitrogen-deficient environment
Authors: Ronen Z. , Brenner A. , Abeliovich A.
Published: May 2018

A feasible biological treatment process for RDX-contaminated wastes was demonstrated in a bench-scale system, using real wastewater of a munitions factory. The wastewater mixture tested included the nitramine RDX together with high levels of nitrate and various organic solvents such as cyclohexanone and acetone. The purpose of the study was to remove both RDX and nitrate in order to prevent groundwater contamination. A two-stage reactor system including an anoxic stage followed by an aerobic one was tested. The anoxic stage was aimed at removing nitrate by denitrification, using available carbon sources present in the waste mixture. Additional supply of carbon source (acetone) was required to support complete removal of nitrate. Further removal of residual organic was achieved in the aerobic stage together with total mineralization of RDX. Complete removal of nitrate in the anoxic stage was found to be crucial to RDX mineralization in the aerobic stage, since RDX was used solely as a nitrogen source. Additional carbon source (cyclohexanone) was also required in the aerobic stage to assure complete removal of RDX. The treatment scheme tested may be a cost-effective alternative to physico-chemical treatments such as carbon adsorption and UV destruction, commonly applied for explosives-contaminated wastes.
Decolorization and toxicity screening of selected reactive azo dyes under methanogenic conditions
Authors: Beydilli M. I. , Pavlostathis S. G. , Tincher W. C.
Published: May 2018

The objective of this research was to generate technical background for the development of a fixed-film anaerobic reactor to renovate reactive textile dyebaths and reuse the high salt-containing mixture in the dyeing process. Six commercial reactive azo dyes (Black-5; Red-2 and 120; Yellow-3, 15 and 17) were chosen for this study. Using an anaerobic, methanogenic culture enriched from municipal sewage sludge, batch assays were performed to evaluate potential toxicity of the selected dyes to the anaerobic microorganisms as well as to determine the anaerobic biodegradability of these dyes. Total gas and methane production were monitored. No significant toxic effects were observed at 300 mg/L concentration for all dyes tested. At the end of three consecutive feeding cycles all dyes exhibited overall color removals in the range of 77.8 and 97.1%. An assay intended to determine the toxic limit and kinetics of color removal of Red-2 revealed that up to 300 mg/L, this dye was not toxic and contributed to increased total gas and methane production over that of a control. However, higher concentrations of Red-2 (500, 1000 and 2000 mg/L) depressed gas production despite continued decolorization. These results suggest that color removal under the low redox conditions maintained by the methanogenic culture occurs irrespective of the culture activity level.
Biodegradability enhancement of refractory pollutants by ozonation: a laboratory investigation on an azo-dyes intermediate
Authors: Lopez A. , Ricco G. , Mascolo G. , Tiravanti G. , Di Pinto A. C. , Passino R.
Published: May 2018

The effectiveness of ozone treatment for improving the biodegradability of recalcitrant pollutants has been proved by investigating the ozonation reaction of FAST-VIOLET-B (FVB) a bioresistant chemical intermediate of azo-dyes. Laboratory scale experiments have been carried out, at room temperature, by bubbling, for 90 min, ozonated air (9ppmO3/min) into 0.35 1 of an alkaline (pH=11) aqueous solution (50 ppm) of FVB. The experimental results indicate that during the ozonation, even though complete FVB degradation occurs in 10 min, ozone consumption goes on for a further 20 min after which time most degradation reactions are completed. The main ozonation by-products, identified by HPLC, IC, and GC-MS are formaldehyde, acetaldehyde, glyoxal, acetone, acetic-, formic-, oxalic- and carbonic-acid, plus six FVB derivatives scarcely biodegradable. At the end of the ozonation, i.e. after 30 min., the initial values of TOC (35 mgC/l) and COD (103 mgO2/l) are respectively 27 and 25 and correspond to a relative removal of about 23% and 76%. As for FVB solution biodegradability expressed as (BOD5)/(COD) ratio, during the first 10 min its value regularly increases from zero up to a maximum of 0.75 that corresponds to an ozone consumption of 2.4 mg per each mg of organic carbon initially present in the solution.
Using microbial fatty acids to quantify, characterize and compare biofilm and suspended microbial populations in wastewater treatment systems
Authors: Werker A. G. , Hall E. R.
Published: May 2018

Spectra of microbial fatty acid methyl esters were used to assess the influence of pH on the biofilm and suspended biomass populations within bench scale moving bed bioreactors treating bleached kraft mill effluent. The fatty acid spectral data were reduced by logcontrast canonical component analysis. The first canonical component differentiated biofilm from suspended populations and the second two appeared to indicate an influence of pH on microbial ecology. Thus, the biofilm and suspended microbial communities were distinct, as were the populations acclimated at pH 6 and pH 8. Experimental data for total organic carbon removal suggested that the more recalcitrant fraction of the influent was consumed by the slower growing, high SRT biofilm fraction of the biomass. Since the biofilm ecology was sensitive to pH within typical pH operating limits of full-scale systems, tighter pH control might improve treatment reliability in the event of process transients.
Control of bulking in a full scale plant by addition of talc (PE 8418)
Authors: Eikelboom D. H. , Grovenstein J.
Published: May 2018

A very severe bulking problem (Type 021N) in the water treatment plant of Bodegraven in The Netherlands was solved by the addition of a specially shaped talqueous powder, PE 8418. After addition of this mineral product, the SVI dropped almost instantaneously from 850 ml/g to 250 ml/g and over the next 2 weeks decreased further to 100 to 125 ml/g. A ratio PE 8418/biomass of 0.6:1 was sufficient to keep the SVI at this level. The settling velocity of the sludge increased from <1.0m/h to 1.5 m/h. These settling properties allowed normal plant operation. During the first 2 weeks of the experiment, scum on the final clarifier and the aeration tank caused some problems. It is assumed that the complete incorporation of PE 8418 particles into the flocs takes some time, if a large quantity of this product is added at once. Meanwhile, free particles may contribute to stabilization of gas bubbles, viz. flotation of activated sludge.
Phylogenetic assessment of five filamentous bacteria isolated from bulking activated sludges
Authors: Howarth R. , Head I. M. , Unz R. F.
Published: May 2018

Nearly complete 16S ribosomal RNA (rRNA) sequences were determined for fully characterised axenic strains of Thiothrix, Eikelboom type O21N, and Eikelboom type 1701 originally isolated from bulking activated sludges. Thiothrix strains formed a monophyletic group (100% bootstrap support) with previously described Thiothrix nivea strain JP2 and Thiothrix ramosa. Eikelboom type O21N strain AP3 revealed a sufficiently strong relationship to the Thiothrix group to suggest a common ancestry for the two organism although it was not possible to designate type 021N as a species of Thiothrix. Eikelboom type 1701 contained within its sequence the target sequence of an oligonucleotide probe for the detection of Sphaerotilus natans.
Hydrophobic/hydrophilic properties of activated sludge exopolymeric substances
Authors: Jorand F. , Boué-Bigne F. , Block J. C. , Urbain V.
Published: May 2018

Hydrophobic interactions may be fundamental in the cohesiveness and other properties of bacterial aggregates called flocs. Exopolymeric substances (EPS) form a matrix in which bacteria and other particles are embedded. However, knowledge about EPS hydrophobic properties is rather scanty.

In this study, EPS extracted from activated sludges from different origins were fractionated, exploiting their property of sorbability by non-ionic resins and the formation of precipitates under-acidic environment. In the light of the results obtained with the XAD-8 resin, at least 7% of the dissolved carbon and 12% of the proteins may be considered as hydrophobic. No carbohydrates were found in the hydrophobic fraction. The precipitable fraction at pH 2 on the other hand contained 64% carbohydrates and 76% proteins. This suggests that EPS are heteropolymers principally made up of carbohydrates and proteins.
In situ structure/function studies in wastewater treatment systems
Authors: Schramm Andreas , De Beer Dirk , van den Heuvel Han , Ottengraf Simon , Amann Rudolf
Published: May 2018

As an example of the importance and the potential of in situ structure/function studies, nitrifying aggregates from different zones of a lab-scale fluidised bed reactor were analysed by microelectrode measurements of O2, NH4+, NO2−, and NO3− and in situ hybridisation targeting the 16S rRNA of the nitrifying bacteria. A shift from an ammonia oxidising to a nitrite oxidising community is present along the reactor. In the single aggregates an active nitrifying shell of about 100 μm could be related to the maximum abundance of nitrifiers in this zone. Interestingly, the main actors in this system are not representatives of the well-described genera Nitrosomonas and Nitrobacter but some other ammonia oxidisers from the beta subclass of Proteobacteria and a thus far unknown nitrite oxidising population.
Variability of type 021N in activated sludge as determined by in situ substrate uptake pattern and in situ hybridization with fluorescent rRNA targeted probes
Authors: Nielsen P. H. , Andreasen K. , Wagner M. , Blackall L. L. , Lemmer H. , Seviour R. J.
Published: May 2018

Bulking sludges were investigated in seven industrial or municipal activated sludge treatment plants from Denmark, Germany and Australia. The dominating filaments were all identified as type 021N according to the Eikelboom key. The extent of variability in the filament taxonomy was assessed using fluorescence in situ hybridization (FISH) with rRNA-targeted nucleic acid probes specific for type 021N, Thiothrix and Leucothrix. Not all of the filaments morphologically identified as type 021N hybridized with the 021N probe. In one treatment plant the predominant filament hybridized with the probe for Thiothrix and in one treatment plant the predominant filament did not hybridize with any of these probes. In none of the plants did filaments hybridize with the probe for Leucothrix. A study of the in situ uptake of different organic substrates by the various filaments was also conducted using microautogradiography. The uptake of 6 different organic substrates under aerobic conditions was studied by providing C-14 or H-3 labeled substrates (acetate, glucose, ethanol, glycine, leucine and oleic acid) in incubations of a period of 3 hours. No filaments took up all the tested substrates, and type 021N from the various treatment plants varied in their uptake abilities. The study demonstrated that strain differences with regard to substrate utilization are likely to occur among bacteria within the same genera and designated types which are indistinguishable on the basis of morphological observations alone and by the molecular probes used in this study for identification. Whether there is a clear correlation between type of wastewater and the capability of taking up the various organic substrates for the filaments remains to be elucidated.
Effectiveness of oligonucleotide probes targeted against Thiothrix nivea and type 021N 16S rRNA for in situ identification and population monitoring in activated sludges
Authors: Pernelle Jean-Jacques , Cotteux Eric , Duchène Philippe
Published: May 2018

In situ hybridization (FISH) of two fluorescent oligonucleotide probes, TNI and 21N, directed against 16S rRNA fragments of Thiothrix nivea and type 021N filamentous bacteria, was used to study activated sludge samples of various origins. Comparison of the results obtained by this technique with morphological data enabled us to evaluate the sensitivity and specificity of the probes, as well as to propose practical classification criteria, in an effort to correlate the identification and ecology of these two microorganisms. We applied the two oligonucleotide probes to the study of Thiothrix sp. in pilot and laboratory batch reactors fed a substrate that was moderately deficient in rapidly available phosphorus. We monitored the growth dynamics of Thiothrix sp. in the pilot reactor, using various hydraulic configurations and after certain perturbations, such as transient substrate overloads. The results provided data which led us to question the importance of the length of time oxygen-deficient sludges spend in clarifier tanks and we discuss the effects of both moderate reductions in oxygen and of very intermittent feedings on the occurrence of Thiothrix sp. growth peaks. The identification and quantification of these filamentous bacteria by size class, made possible by in situ hybridization, are shown to be powerful tools for the early detection and evaluation of episodes of proliferation of filamentous bacteria, revealing them to be much more sensitive indicators than the sludge volume index (SVI).