bluuebunny/crossref_metadata_2025 huggingface dataset:
Treatment of Wastewater from Flue Gas Cleaning
Authors: Vendrup Michael , Sund Christina
Published: May 2018

Wet scrubber systems for flue gas treatment, giving rise to a production of wastewater contaminated with heavy metals, are used at many coal-fired power stations in Europe, the USA and Japan.

In order to remove the heavy metals from the wastewater, chemical precipitation with hydroxide and sulphide is applied. Results from two full-scale plants are given.

Due to strict regulations for landfilling of waste contaminated with heavy metals, the amount of sludge must be minimised. Different techniques to meet this requirement are described.

Biological post-treatment to reduce the nitrogen content of the wastewater will apparently be a need in the future, and pilot-scale testing is presently being carried out to determine the basic operation rules for a full-scale plant.
Waste Generation and Management in the Semiconductor Industry: A Case Study
Authors: Vagliasindi Federico G. A. , Poulsom Susan R.
Published: May 2018

The production of semiconductors is an extremely complex process involving the deposit of several layers on silicon wafers, patterning the layers through photolithography and adding dopants to alter the conductivity. The process generates gaseous, liquid and solid waste streams consisting of many diverse and toxic components including toxic organics, variable pH, fluoride and arsenic. This paper presents the results of a study which investigated the manufacturing processes of semiconductors, including: generated pollutants, applicable regulations in the USA, waste minimization practices, and waste treatment and disposal alternatives. As part of this investigation, a case study was conducted on the waste generation and management of a semiconductor facility located in the USA.
Water quality index – application for rivers in Vistula river basin in Poland
Authors: Dojlido J. , Raniszewski J. , Woyciechowska J.
Published: May 2018

This paper describes the method of the water quality index (WQI), which is used to estimate the cleanness of water. It contains the lists of basic and additional parameters, the formula for the summarized index and the algorithm for evaluation of summarized and guarantee index. It is illustrated by practical examples of evaluation of WQI in the rivers of the Vistula basin in Poland.
Binding of natural humic matter to polycyclic aromatic hydrocarbons in rivers of the Southeastern United States
Authors: Alberts James J. , Griffin Cheryl , Gwynne Katherine , Leversee Gordon J.
Published: May 2018

The binding constants (Koc) of four polycyclic aromatic hydrocarbons (PAH) were determined for sedimentary fulvic and humic acids and the dissolved organic carbon (DOC) of five rivers in Georgia, USA. The log Koc for the PAH ranged: anthracene, 4.63-5.57; phenanthrene, 4.58-5.62; pyrene, 4.90-5.65; benzo(a)pyrene, 3.48-5.20. Log Koc values for the PAH compounds with riverine DOC were very similar for all rivers and more closely resembled those of sedimentary humic acids than the fulvic acids. The molecular size distribution of the riverine DOC indicates that >75% of the DOC occurs in size fractions >10,000 daltons. Despite similarities in Koc, there appear to be inter-river differences in the distribution of PAH among molecular size classes of the DOC, which have ramifications for water quality both in rivers and estuaries.
Barcelona's water supply improvement: the brine collector of the Llobregat river
Authors: Martín-Alonso Jordi
Published: May 2018

The Llobregat is a 156 km long river, which supplies 35% of the Barcelona's drinking water needs from the Sant Joan Despí Water Treatment Plant. Since the establishment of the Salt Mine Works in the Llobregat basin in 1923, a progressive salinization of the water sources has been recorded. The operation of the Brine Collector, as a public work carried out by Aigües de Barcelona (AGBAR), started in 1989; it enabled a very significant improvement in the quality of the surface water used for drinking-water production.
Sediment resuspension and light conditions in some shallow Dutch lakes
Authors: Blom G. , van Duin E. H. S. , Lijklema L.
Published: May 2018

The relationship between sediment resuspension and light conditions has been studied in three shallow Dutch lakes. In shallow eutrophic lakes, the contributions of algae and suspended sediments to light attenuation are usually dominant. Wind induced resuspension of bottom sediment and sedimentation often determine the dynamics and the spatial variability of the suspended solids concentration and the light attenuation coefficient. A model is discussed relating the suspended solids concentration and light attenuation coefficient to the orbital velocity, induced by waves, and to the fall velocity of solids.

Using experimental data, the relationships between fall velocity, organic matter content and the specific vertical attenuation coefficient are analyzed. Differences in the specific vertical attenuation coefficient and in fall velocities of sediment fractions, are related to differences in particle size as well as differences in composition. The contribution of (resuspended) particles to the suspended solids concentration and to light attenuation is primarily due to slow settling sediment fractions which are rich in organic matter. So in modelling light attenuation dynamics especially these fractions are of interest. Heavier fractions can be disregarded. A model for the relationship between resuspension and light attenuation dynamics, based on this conclusion, has been tested successfully for 2 shallow Dutch lakes.
An experimental study to suppress scum formation accompanying the abnormal growth of Nocardia by adding ozone in the aeration tank
Authors: Goi M. , Nishimura T. , Kuribayashi S. , Okouchi T. , Murakami T.
Published: May 2018

In order to suppress scum formation of activated sludge accompanying the abnormal growth of Nocardioform Actinomycetes (Nocardia sp.) in the final sedimentation tank, etc., an experimental study was made by adding ozone (at ozone consumption 2-6 ml/l) in the aeration tank. The abnormal growth of Nocardia almost disappeared, and foaming in the aeration tank and scum formation of activated sludge in the final sedimentation tank were not seen, showing that the scum suppression effect of ozone addition was obvious. The treated water quality was little affected except for accelerated nitrification by ozone addition, and the sludge settleability was improved.
Biological nutrient removal applied to weak sewage
Authors: Charlton J.
Published: May 2018

The Melby Wastewater Treatment Plant is located in the municipality of Frederiksværk on the island of Sealand, Denmark. This may be the first full-scale plant in Europe purpose built for biological nutrient removal from diluted wastewater, i.e. weak domestic wastewater mixed with infiltration waters.

The relatively strict effluent standards have required the existing treatment plant to be upgraded in capacity, including the design for biological Nitrogen and Phosphorus removal. Due to the weak nature of the influent wastewater, the treatment process that has been adopted includes the application of a primary sludge fermenter to alter the influent characteristics suitable for biological nutrient removal. The treatment process used is the Modified University of Cape Town process utilising a primary sludge fermenter developed at the University of British Columbia in Canada. The combination of these two processes has been successfully applied to meet the strict discharge licence requirements, without the addition of chemicals, despite the unsuitable characteristics of the influent wastewater for biological nutrient removal. The paper describes the operational results for the treatment plant.
Upgrading of existing sewage treatment plants by computer simulation: game or reality?
Authors: van der Kuij R. J. , van Bentem A. G. N. , van Breukelen F. Th.
Published: May 2018

From 1 January 1995 in The Netherlands 75% of the phosphorus in the influent has to be removed in the waste water treatment plants (wwtp's). At this moment 40 – 50% is reduced by biological incorporation and some chemical dosing. By additional measures an extra 35% reduction has to be accomplished. A further reduction of total nitrogen to 75% has to be realised from 1 January 1998.

Further extension of the activated sludge system is not always possible and in most cases rather expensive. Therefore optimization of the existing treatment plant is considered.

For this purpose the advanced simulation model STREAM• is used. With STREAM• almost every waste water treatment plant can be simulated with the computer. In this way, for example, the effect of different control mechanisms and other measures can be studied without costly research.

Computer simulation has been applied at the Kralingseveer wwtp of the HH van Schieland (Waterboard in the Netherlands) to optimize aeration control and to evaluate a number of technological process adjustments. Attempts are being made to reduce nitrogen drastically using equipment currently available, supplemented where possible with other limited measures.

It can be concluded from the results of simulation, that the use of integrated aeration control, whereby influent flow, and nitrate and ammonium concentrations in the activated sludge are measured on-line, further improves the treatment process. Furthermore, when the sludge content in the aeration tank is raised and nitrogen is removed from the internal return flows, it seems that an average annual effluent quality of 10 mg Ntotal/1 is feasible. Verification of these factors will be carried out in the near future using practical measurements.

The Kralingseveer project demonstrates that computer simulation is more than simply a ‘game’. It has become a real means of guiding or even limiting the need for extensive and costly (practical) investigation.
Treatment of organic wastewater by anaerobic biological fluidized bed reactor
Authors: Tseng Szu-Kung , Lin Min-Ray
Published: May 2018

Anaerobic biological fluidized bed method (AFBBR) for wastewater is already known to have higher specific surface area and biomass concentration than the conventional complete-mixing anaerobic reactor, so the removal efficiency for organic wastewater treatment is higher. Experiments were carried out with three kinds of wastewaternamely synthetic domestic and MSG wastewater. The results show that the AFBBR can exploit its advantages to compensate for the decrease in the digestive rate caused by temperature drop, while still showing the high treatability of organic wastewater. Treating wastewater containing chlorophenol and nitrophenolat below 0.9 kg compound/m3.d, the COD removal efficiency can reach ≥ 90%.
The influence of chemical structure on the anaerobic catabolism of refractory compounds: a case study of instant coffee wastes
Authors: Azhar N. G. , Stuckey D. C.
Published: May 2018

Due to concerns about meeting the strict legislation currently in force, anaerobic treatment is being investigated for the treatment of a variety of waste streams. Instant coffee wastes are one type of industrial effluent that appears to be amenable to anaerobic digestion, and this paper presents some results on the biodegradation of this effluent. The method used was a batch bioassay technique known as the Biochemical Methane Potential assay (BMP), which gave 84% degradation of a composite coffee waste sample. Various fractions of the coffee waste revealed mixed degradation results mostly attributed to structural differences, with the liquid fractions being almost 60% degradable, and the solids filter cake fraction, containing most of the lignocellulosic material being only 9% degradable. Volatile fatty acid (VFA) analysis revealed high concentrations of formate being formed and subsequently degraded in the bioconversion process, and a possible role for formate production was postulated. Variations in structure did not appear to affect the route by which VFAs were produced. Bioconversion of 5-6 major classes of pure organic compounds thought to be potentially recalcitrant in coffee effluent was investigated to determine possible mechanisms of degradation, and the extent to which structural variation affected degradability. The phenolics and chlorogenic acids gave the highest degradation of 70% and 60% respectively, and the cyclic volatiles the least degradation at 40%.
Micro-straining as advanced treatment of wastewater applied to the main wastewater treatment plant in Wiesbaden
Authors: Grau Arno , Haeusler Michael , Schmitt Wälti
Published: May 2018

Micro-straining as an advance treatment of wastewater has been evaluated in a half as well as full technical unit. Mesh dimensions of 10, 20 and 40 μ have been used, straining velocities between 10 to 35 m/h have been measured and suspended solids retention of 75 – 85 % could be achieved. The investment and operational costs are lower than those of other systems, e.g. sand filtration.
High rate thermophilic anaerobic wastewater treatment in compartmentalized upflow reactors
Authors: van Lier J. B. , Boersma F. , Debets M. M. W. H. , Lettinga G.
Published: May 2018

Thermophilic anaerobic treatment of acidified and partially acidified wastewater was studied using Upflow Staged Sludge Bed (USSB) reactors. Reactors were composed of various compartments of which each was equipped with a gas-solid separator. This novel approach for thermophilic wastewater treatment led to a reduction or even elimination of major biological and physical limitations of conventional high rate thermophilic conversion processes. The main achievements of the plugflow reactor were i) very low concentrations of volatile fatty acids (VFA) in the effluent, ii) a high degree of sludge retention, and iii) stable reactor performance. The start-up of the reactors was done with either ‘crushed’ mesophilic granular sludge (MGS) or the digested organic fraction of municipal solid waste (OFMSW) as inoculum. A mixture of VFA and a mixture of sucrose-VFA were used as feed. A good operation performance was achieved within 1 month, and the granulation process of the thermophilic biomass was clearly visible after 1-1.5 months of operation. Within 2-3 months, the organic loading rate could be increased up to 100 kg sucrose-VFA-COD m−3 day−1 with a COD removal efficiency exceeding 90% at a HRT of 2-2.5 h. No significant wash-out of the thermophilic biomass was observed despite the extreme biogas load of 40-50 m3 m−3 reactor day. A certain percentage of sucrose was essential for the thermophilic granulation process; in the reactors treating solely the VFA mixture almost no granules were formed. Nevertheless, also in the latter reactors a satisfactory biomass hold up was observed despite the disperse nature of the sludge. The advantage of using compartmentalized reactors was clearly demonstrated under extreme loading conditions. A typical sequence in the degradation of the partially acidified substrate was found. In the first compartment sucrose was converted, followed by the conversion of butyrate and acetate in the next compartments. Propionate was the most difficult intermediate to degrade, but in the last compartments even this fatty acid was degraded almost completely.
Performance of methane fermentation pits in advanced integrated wastewater pond systems
Authors: Oswald William J. , Green F. Bailey , Lundquist Tryg J.
Published: May 2018

Advanced Integrated Wastewater Pond Systems (AIWPSs) involve a series consisting of Advanced Facultative Ponds with internally located fermentation pits; secondary ponds with either photosynthetic oxygenation or mechanical aeration; tertiary ponds for sedimentation of either algae or aeration solids; and, quaternary ponds for controlled discharge, irrigation storage, aquaculture, or other beneficial uses of reclaimed wastewater.

This paper deals mainly with design and performance of Advanced Facultative Ponds containing internally located fermentation pits. Experiences with a 1,894 m3 day−1 (0.5 MGD) AIWPS and a 7,576 m3 day−1 (2.0 MGD) AIWPS indicate that primary facultative ponds with internal fermentation pits require less land than do conventional anaerobic ponds and that sludge removal is postponed for many years. New, more detailed, and controlled scientific studies on a 133 m3 day−1 (0.035 MGD) demonstration AIWPS at the University of California, Berkeley, Environmental Engineering and Health Sciences Laboratory in Richmond, California provide evidence that these simple pits remove suspended solids and biochemical oxygen demand more effectively than do comparably loaded conventional anaerobic ponds and produce much less odor. In addition they improve removal of parasites, bacteria, viruses, heavy metals, and halogenated hydrocarbons. The reliability and cost effectiveness of AIWPS is compared with more conventional ponds and with mechanical wastewater treatment systems.
The effect of disc submergence level on the performance of a laboratory-scale anaerobic rotating biological contactor: implications for digester design and modelling
Authors: Tseng D. W.-S. , Connor M. A.
Published: May 2018

A hypothesis was advanced that an anaerobic rotating biological contactor (AnRBC) digester, if operated with its discs half rather than fully submerged, should show an enhanced capability to withstand shock loads. Laboratory-scale AnRBC digesters were constructed and their performance under 50% and 100% disc submergence conditions compared. In all cases, under otherwise comparable conditions the performance in the 50% disc submergence mode was better. From measurements, including biogas hydrogen concentration, pH and propionic acid content of the digester liquid, it was concluded that it was the markedly better hydrogen stripping capability of the digester operated with discs only half submerged that accounted for its superior performance. Implications for design and modelling of digesters are discussed. It is concluded that current models of anaerobic digester systems need to reflect more accurately the actual hydrodynamic conditions in digesters if good predictions of digester performance under dynamic conditions are to be realised.
Combination of anaerobic digestion and denitrification in a hybrid upflow anaerobic filter integrated in a nutrient removal treatment plant
Authors: Tilche A. , Bortone G. , Forner G. , Indulti M. , Stante L. , Tesini O.
Published: May 2018

A new nutrient removal plant configuration was designed and tested in pilot-scale for the treatment of piggery wastewater. The core of the process is represented by a Hybrid Upflow Anaerobic Filter where both anaerobic digestion and denitrification takes place. The pre-screened piggery wastewater is fed to the mesophilic anaerobic reactor. In the bottom of the sludge bed, anaerobic digestion and sulfate reduction are the prevalent processes. In the upper filter zone, a stream of nitrified clarified effluent is recycled and nitrates are denitrified utilizing the remaining available carbon and sulfides as electron donors. The anaerobic reactor should be slightly overloaded in order to provide VFAs for denitrification. The effluent of the anaerobic reactor is fed to the following P-removal stage, which is composed of a sludge pre-denitrification step, an anaerobic P-release step, an aerobic nitrification tank and a final settler. The pilot-plant treated 5 m3 d−1 of pre-screened piggery wastewater. The anaerobic digester (volume 15 m3) demonstrated it was to couple anaerobic digestion and denitrification. The overall plant removal efficiency was around 96% for COD, 92% for nitrogen and 92% for phosphorus. The anaerobic digester contributed 80% to the overall denitrification capacity.
Pilot-scale anaerobic treatment of cheese whey by the substrate shuttle process
Authors: Cohen Alberto , Thiele Jürgen H , Zeikus J. Gregory
Published: May 2018

An experimental system was set up to study the Substrate Shuttle Process (SSP). Whey was fed to an acidogenic UASB reactor. The effluent was intermittently circulated through an Ion Exchange Unit (IEU) containing an anionic exchange resin. During a load cycle, organic acids were adsorbed onto the ion exchange resin. After completion of the load cycle, the ion exchange resin was regenerated by recirculating through it the effluent of a methanogenic UASB reactor, into which the organic acids were released, prior to returning the liquid into the reactor. The pilot system was designed to operate automatically with two IEUs operating in tandem, of which one at a time was operating in a load cycle, while the other was being regenerated. The first experimental period lasted 9 days with a cycle duration of one hour. Acids were removed from the acid UASB liquor, with a concomitant rise of pH and the production of methane in the methanogenic UASB. The acid UASB produced little gas and no methane was detected. The amount of acids circulated through the IEUs was directly proportional with the quantity of methane produced by the methane UASB. After the trial, acid binding capacity had declined to 70% of its original value. A second experiment lasted 118 days, with a cycle duration of five hours. Final conversion of all acid circulated through the IEUs into methane averaged 19%. After initial conditioning of the resin, no significant long-term deterioration of process performance was evident.
Estimation of Short-Duration Rainfall Distribution Using Data Measured at Longer Time Scales
Authors: Van Nguyen Van-Thanh , Raj Pandey Ganesh
Published: May 2018

An investigation on how to estimate the distribution of short-duration (hours or shorter) rainfalls based on available daily rainfall measurements was undertaken. On the basis of the theory of multifractal multiplicative cascades, a scale-independent mathematical model was proposed to represent the probability distribution of rainfalls at various time scales. Using rainfall records from a network of seven recording gauges in the Montreal region in Quebec (Canada), it was found that the proposed model could provide adequate estimates of the distribution of hourly rainfalls at locations where these short-duration rainfall data are not available. Further, it has been observed that one single regional model can be developed to describe the scaling nature of rainfall distributions within the whole study area.
Toxic Metals in Urban Runoff: Physico-Chemical Mobility Assessment Using Speciation Schemes
Authors: Flores-Rodríguez J. , Bussy A.-L. , Thévenot D. R.
Published: May 2018

Physico-chemical characterization of lead, zinc and cadmium has been carried out on eight samples from both separate and combined sewers. Dissolved and paniculate total metal levels have been determined. A speciation scheme has been used to further divide these phases in two dissolved fractions, bioavailable and stable, and five paniculate fractions, ion-exchangeable, acid-soluble, reducible, oxidizable and residual. Total dissolved lead concentrations were found to be largely below European Community (EC) directives for drinking water production. Lead was represented by stable forms while zinc and cadmium were mainly bioavailable. Paniculate concentrations were higher than natural levels found in the Seine-Normandie basin. Zinc was characteristic for municipal effluents, and lead and cadmium were more concentrated in separate sewers. Correlations have been observed between paniculate heavy metals and volatile matter on the ring highway, or with iron at the Savigny site. The paniculate metal speciation scheme has demonstrated the important dependence of heavy metal distribution on the sampling site, as well as the potentially more mobile nature of zinc and cadmium, compared to that of lead. The structural modifications undergone by solids during their transport along the sewer networks had a significant impact on paniculate metal mobility. This has been clearly noted for lead, whose mobility decreased from upstream to downstream in the studied system.
Estimations for Percentage of Impervious Area by the Use of Satellite Remote Sensing Imagery
Authors: Deguchi C. , Sugio S.
Published: May 2018

This study aims to evaluate the applicability of satellite imagery in estimating the percentage of impervious area in urbanized areas. Two methods of estimation are proposed and applied to a small urbanized watershed in Japan. The area is considered under two different cases of subdivision; i.e., 14 zones and 17 zones. The satellite imageries of LANDSAT-MSS (Multi-Spectral Scanner) in 1984, MOS-MESSR(Multi-spectral Electronic Self-Scanning Radiometer) in 1988 and SPOT-HRV(High Resolution Visible) in 1988 are classified. The percentage of imperviousness in 17 zones is estimated by using these classification results. These values are compared with the ones obtained from the aerial photographs. The percent imperviousness derived from the imagery agrees well with those derived from aerial photographs. The estimation errors evaluated are less than 10%, the same as those obtained from aerial photographs.
Integrated Pollution Control of Emissions from the Pulp and Paper Industry
Authors: Webb L. J.
Published: May 2018

A new regulatory system known as integrated pollution control (IPC) is being introduced in the UK over the period 1991-1996. This will apply to combustion processes, some coating processes and some pulp and paper mill processes. Prescribed processes will have to use control concepts based on “best available techniques” and optimisation of waste streams released to the different receiving media. BAT standards have been set for the combustion processes, but not yet for the pulping and papermaking processes. The main types of UK mill that could be affected by this new regime are non-integrated paper mills, which use imported pulp and/or wastepaper. If prescribed under IPC, mills will have to justify their raw materials/process selection and pollution abatement technologies in terms of minimising impacts to air, water and land.
Kinetic Models for Describing Degradation of AOX in the Waste Water of a Mill Producing Bleached Sulphate Pulp
Authors: Frisk T. , Bilaletdin Ä
Published: May 2018

In the study, submodels for describing degradation of organic chlorine (measured as AOX) coming from a mill producing bleached sulphate pulp were developed. The submodels coupled to a hydrodynamic model can then be used in assessing the behaviour of AOX in receiving waters. The data used in developing the models was based on mesocosm-scale experiments carried out in two lakes. Waste waters of two mills were used at two dilutions (2% and 10%). Part of the mesocosms were darkened in order to study the effect of light on degradation. In the first phase of the modelling first-order kinetics with a constant coefficient were used. The next steps were to include the effect of temperature and light in the model. Including temperature and light did not much contribute to the modelling results. It was found that more than half of the degradation was caused by the light-dependent component of the degradation reaction. The reaction obeys first order kinetics satisfactorily. However, the reaction coefficient is greater in the beginning of the experiment than later. A correction function describing the decrease of the reaction coefficient was included in the model. The correction function is based on the idea that the most readily decaying components of AOX disappear from the solution in the beginning and therefore the apparent reaction coefficient decreases. Only data on AOX was available in this study but the approach can be applied for different chloro- organic compounds and also for other organic substances.
Adsorbable Organic Halide Removal Mechanisms in a Pulp and Paper Mill Aerated Lagoon Treatment System
Authors: Stuthridge T. R. , McFarlane P. N.
Published: May 2018

The aerated lagoon treatment system of a New Zealand pulp and paper mill exhibited 65% removal of adsorbable organic halide (AOX). This value is high compared to published data and an assessment was made of possible mechanisms for the observed AOX removal. Much of this removal took place in a short section (3.3 hour residence time) of the system's main lagoon. The initial AOX decrease in the aqueous phase could be achieved in part by settling of AOX-containing suspended solids from the influent wastewaters and by alkaline dehalogenation. In addition, lime and bacterial solids present in the treatment system were able to adsorb AOX from the influent wastewaters. Only a small proportion of the organic chlorine removed was found in sludges. A mass balance of aqueous and solid phases indicated that over 99% of the removed AOX was mineralised.
Biotreatability of Blow Heat Condensates with and without Hydrogen Peroxide Pretreatment
Authors: Barton D. A. , Drake E. P.
Published: May 2018

Pulp mill modifications implemented by kraft mills for the purposes of controlling air emissions, such as the installation of indirect secondary condensers installed in blow heat handling systems, may result in altered characteristics of wastewater treatment plant influents. This study examines the impacts on biological treatment processes associated with the presence of blow heat condensates in the influent stream. In addition, the effectiveness of pretreatment of the condensate stream with hydrogen peroxide, in the presence of the ferric ion, is examined under controlled conditions through the use of bench-scale bioreactors. The study results indicate that the presence of blow heat condensates may adversely impact the mixed liquor settleability properties in the activated sludge process, although subsequent trials conducted to re-create this condition were not successful. Effluent soluble BOD5 was not affected by the presence of the condensates. Ferric/peroxide pretreatment was found not to be effective at destroying either the methanol or the turpentine present in the condensate stream. However, a significant improvement in Microtox biological response was observed, presumably due to a reaction between the ferric ion and reduced sulfur compounds. Furthermore, no adverse impacts on settleability were observed in a bio-reactor receiving condensates which were pretreated with ferric/ieroxide.
Decolorisation of Extraction Stage Bleach Plant Effluent by Combined Hypochlorite Oxidation and Anaerobic Treatment
Authors: Clark T. , Bruce M. , Anderson S.
Published: May 2018

The feasibility of sequential sodium hypochlorite decolorisation and anaerobic biological treatment, as a low-cost process for decolorisation of extraction-stage bleach plant effluent, was studied. Treatment of E-stage effluent with chlorine can reduce colour by 50-90%, depending on the reaction pH. At pH 10, where the hypochlorite ion is the reactive species, the highest levels of colour removal were observed and, compared with pHs 4 and 7, the effluent produced was less inhibitory to anaerobic bacteria. A chlorine dosage of 0.1 kg active Cl/kg colour was sufficient to achieve about 90% colour removal, although the AOX concentration of the wastewater increased by about 50%. Subsequent anaerobic treatment of the decolorised wastewater was able to reduce the AOX concentration to close to its original level. Only a small amount of colour reversion was observed and an overall colour removal of about 80% was achieved. The hypochlorite treatment caused a substantial increase in the concentration of low molecular mass AOX, which was amenable to anaerobic dechlorination. Anaerobic treatment of untreated ?-stage effluent had no effect on the concentrations of AOX or colour. These results suggest that this treatment method may have potential as a low cost technology for providing a short-term solution to bleach plant colour problems.
High rate nitrifying trickling filters
Authors: Andersson B. , Aspegren H. , Parker D. S. , Lutz M. P.
Published: May 2018

A two year pilot plant study has been performed in order to evaluate a nitrifying trickling filter (NTF) process within an upgrading project for increased nutrient removal. The operation of the filters was very stable without upsets due to predators. The filter microfauna was dominated by worms and the presence of filter fly larvae was limited. Suggested predator control methods like flooding or varying the flushing intensity did not affect the identified microfauna. By operating the filters in a two stage alternating series filtration mode, higher nitrification rates and lower effluent ammonia concentrations could be reached simultaneously in comparison to operating the filters in a single stage filtration mode.
Phosphorus requirements for tertiary nitrification in a biofilm
Authors: Nordeidet B. , Rusten B. , Ødegaard H.
Published: May 2018

Internationally, phosphorus limitation in nitrification of municipal wastewater has been given little attention. However, pre-precipitation of low alkalinity wastewater normally results in phosphate concentrations significantly below 0.10 mg PO4-P/l. Tests have been carried out for tertiary nitrification in rotating biological contactors (RBCs), with different influent phosphorus concentrations. These tests showed that tertiary nitrification in biofilm reactors was clearly phosphate limited at influent concentrations below approximately 0.15 mg PO4-P/l. This means that with todays practice, extension of Scandinavian chemical treatment plants with downstream biofilm reactors for nitrogen removal (i.e. nitrification and post-denitrification) will be hampered by phosphorus limitation in the biological stages. Actions to increase the phosphate concentrations in these biological reactors must be taken.
Biological phosphorus uptake in submerged biofilters with nitrogen removal
Authors: Gonçalves R. F. , Le Grand L. , Rogalla F.
Published: May 2018

This paper introduces biological phosphorus removal (Bio-P) from wastewater on a submerged biofilter. Pilot scale research was carried out over a period of two years using a floating upflow aerated filter, originally designed for nitrification and denitrification of sewage. The factors which influence Bio-P on fixed film processes and the possible biofilter configurations which eliminate C, N and P are discussed. The procedures are applicable to all types of treatment plants using biofilters, both new and already in existence, making no distinction between the different processes available today, co-current and counter-current filters.

Biological phosphorus removal can be associated to the different treatment levels required: organic matter removal; secondary nitrification secondary nitrification and denitrification. For the third option - complete nutrient removal, treatment is completed with a hydraulic retention time in the filter bed of under four hours. Because of the simultaneous filtration with effluent SS below 10 mg/l, low phosphorus residuals can be achieved by Bio-P alone. The modifications required for setting up this operating procedure on any treatment plant are presented.
Fractal properties of the RBC biofilm structure
Authors: Zahid W. M. , Ganczarczyk J. J.
Published: May 2018

Fractal analysis showed two different populations of pores in RBC biofilms. The porosity of mature biofilms was largely influenced by the presence of large rugged pores, but that of biofilms of early-development stages were significantly controlled by the large number of very fine pores.
Development of an automatic control system for monitoring an anaerobic fluidized-bed
Authors: Ehlinger F. , Escoffier Y. , Couderc J. P. , Leyris J. P. , Moletta R.
Published: May 2018

The start-up procedure of a laboratory fluidized-bed was monitored by an automatic control system. Twenty six days were necessary to increase the load from 1 to 35 kg COD/m3.d. The system took into account the pH of the liquid phase, the production of gas, and the concentration of hydrogen in the gas phase. These parameters were measured by on-line sensors. According to variations of these parameters, algorithm based on a principle very close to an expert system adjusted the flow-rate of the feeding pump. The automatic control system was tested in the following situations: perturbations in the process generated by large pH variations (± 0.2 to 0.7 pH unit) and organic overloads (from 50 to 100 kg COD/m3.d). After 44 hours of overloading, CH4 and CO2 concentrations in the gas phase were very useful to detect the deviation of the reactor.
Kinetic behavior of heterotrophic and autotrophic biofilms in wastewater treatment processes
Authors: Moreau M. , Liu Y. , Capdeville B. , Audic J. M. , Calvez L.
Published: May 2018

Conventional laboratory scale annular reactors were employed to investigate the growth dynamics of both heterotrophic and autotrophic biofilms. Based on the experimental observations and physiological aspects, which consist of defining two types of biomass: active biomass (Ma) responsible for substrate removal, and non-active biomass (Md), which plays no role in the biological substrate removal process but is responsible for the observed additional accumulation of biofilms. The experimental results showed that the biological constants were strongly dependent on the influent substrate concentration (So). It was found that the same was true for the volumic substrate removal rate (kov), which shows a surface reaction independent of the film thickness, and that substrate removal in both heterotrophic and autotrophic biofilm reactors remains reactive. The results demonstrated that thinner biofilms ranging from 20 to 30μm have a higher specific removal rate. It is preferable to use thin biofilms for attached culture industrial processes such as three-phase fluidized-bed and turbulent reactors. The results showed that it is possible to eliminate very high carbon loadings up to 10 to 15 kgTOD/m3/d in a three-phase fluidised-bed reactor, and promising results were obtained for simultaneous removal of carbon and nitrogen in the turbulent bed.
Nitrogen removal from wastewaters by a bio-reactor with partially and fully submerged rotating biofilms
Authors: Watanabe Y. , Bang D. Y. , Itoh K. , Matsui K.
Published: May 2018

This paper concerns simultaneous nitrification and denitrification in a completely mixed bio-reactor with partially and fully submerged rotating biological contactors. The bio-reactor is designed to cause the nitrification and denitrification in partially and fully submerged biofilms, respectively. An experimental investigation was made into the effect of organic material and ratio of influent organic carbon to ammonia nitrogen concentrations(C/N ratio) on the efficiency of simultaneous nitrification and denitrification in the bio-reactor. Settled municipal wastewater and synthetic wastewater containing ammonia nitrogen and organic material such as acetate, ethylene-glycol, phenol and poly-vinyl-alcohol(PVA) were fed into the experimental units. A biofilm dominated by nitrifiers developed on the partially submerged contactors, while a biofilm dominated by heterotrophs developed on the fully submerged contactors. A micro-aerobic environment was formed and biological denitrification occurred in the submerged biofilm. In the municipal wastewater treatment where the influent C/N ratio was around 3.5, the maximum nitrogen removal efficiency was about 60 %. Acetate and ethlene-glycol were effectively used as the organic source of the denitrification. The ability to aerobically degrade PVA was induced by phenol. Once the bacteria inhibiting the biofilm gained the ability to degrade PVA, PVA became an effective organic source of the denitrification.
Applying entrapped mixed microbial cell techniques for biological wastewater treatment
Authors: Yang P. Y. , Ma T. , See T. S. , Nitisoravut N.
Published: May 2018

The entrapment of mixed microbial cell was accomplished by using a porous material, such as cellulose triacetate, to confine the migration of microorganism. Synthetic glucose, phenol, carbaryl and nitrate wastewater was used as substrate to evaluate this process. Applying entrapped microbial cell techniques for biological water/wastewater treatment was previously investigated mainly by using the pure culture system. For the past six years, the University of Hawaii has investigated this technology for biological wastewater treatment by using a mixed culture approach. It was found that the developed carrier, using cellulose triacetate, is the most suitable for providing the necessary mechanical strength and durability under both the aerobic and anaerobic conditions. It also provides many advantages, such as a short start-up period, high effluent quality in terms of COD, NO3-N concentrations and removal efficiency, low effluent suspended solid concentration, and high SRT with low HRT. The process has potential to replace or upgrade the existing biological processes for water and wastewater treatment. A pre-engineered and packaged plant can be easily developed for a small wastewater treatment system for toxic or hazardous wastewater.
Aerobic biodegradation of azo dyes in biofilms
Authors: Jiang H. , Bishop P. L.
Published: May 2018

Factors affecting biofilm removal of azo dyes from a synthetic, municipal-type wastewater were investigated using lab-scale, rotating drum biofilm reactors. Among the three azo dyes studied - Acid Orange 8, Acid Orange 10, and Acid Red 14 - only AO-8 degraded aerobically. The azo bond cleavage occurred very easily for all three dyes under anaerobic conditions. AO-8 removals ranged from 20% to 90%. Statistically designed experiments were used to characterize the response of pseudo-steady state biofilms. Two AO-8 removal rate maxima were identified - one at high bulk-phase dissolved oxygen and low COD removal flux, and the other at low dissolved oxygen and high COD flux.

The presence of azo dyes, along with other factors such as COD loading, bulk-phase DO level and shear force, showed impact on biofilm accumulation.
Modelling of rainfall induced infiltration into separate sewerage
Authors: Belhadj N. , Joannis C. , Raimbault G.
Published: May 2018

Flowrate changes in separate wastewater sewerage during wet weather are often attributed to inappropriate connections of runoff water. But these inputs are not the only cause of such behaviour and infiltration through leaking defects or cracks can supply large flows into collection pipes. The characterization of these flows is not an easy task since they involve complex processes, depending not only on rainfall events but also on hydrological conditions and seasons. Using 16 months of hourly measurements of rainfall and flowrates, we developed a six parameter conceptual model to simulate rainfall induced infiltration into a small sewer system. Sensitivity analysis applied to the proposed model showed good achievements under various calibration conditions but displayed high parameter interactions which may be a serious drawback for some specific model uses. Model application to another sewer network yielded good agreement between observed and simulated flows. The suitability of this model must be further checked on other sites.
Technology of membrane biofilm reactors operated under periodically changing process conditions
Authors: Wilderer Peter A.
Published: May 2018

Biological treatment of problematic wastewaters requires the application of specialized reactor systems and operation strategies. Two novel approaches to meet the specific requirements are discussed: (1) application of gas permeable membranes as a means to transfer oxygen into the reactor, and to provide surface area for biofilm growth, and (2) operation of biofilm reactors in a fill and draw mode (Sequencing Batch Biofilm Reactor (SBBR) Technology). Membrane oxygenation and biofilm SBR technology can be favourably combined to treat wastewaters which contain volatile organics, organics in low concentration (e.g. contaminated groundwater) or organics which are degraded only by selected, slow growing microorganisms. The current state of reactor development is summarized. Examples for reactor design are given.
Space-time heterogeneities of rainfalls on runoff over urban catchments
Authors: Roux Christian , Guillon Anne , Comblez Anne
Published: May 2018

Simulated outlet flow series are compared downstream of a 14 sq. km. urban watershed. They are generated either with design rainfall, with long-term point rainfall series, or with long-term space distributed rainfall series (measured with 3 raingauges or with radar). The use of the double-triangle shaped hyetograph as design rainfall provides the same T-year flow as the long term 3 raingauge series, if it is used with a areal reduction factor and uniformly applied to the watershed. For the same T-year mean areal precipitation depth during the time of concentration, the rainfall spatial and temporal heterogenities may induce differences up to +/− 30% on the peak flow, compared to the T-year peak flow.
Continuous measurement of pollution due to urban effluents under wet conditions using optical systems
Authors: Ruban Gwenael
Published: May 2018

Optical sensors appear well adapted to the pollution measurement of urban discharges during wet weather: they allow a continuous and long time investigation of sudden and highly variable phenomena such as rainfall events. They may also be connected to remote monitoring and sanitary equipment automation systems. This paper deals with the measurement principles and use of this type of equipment: adjustment and calibration, sample collection, equipment maintenance and measurement validation. Taking into account the hydraulicity (flow rate or velocity) allows one to improve appreciably the calibration for runoff waters. Calibration at the laboratory seems better than calibration using registered data on the field, as it makes it possible to eliminate the Suspended Matter under-estimation resulting from sampling/analysis.
General assessment of potential CSO reduction by means of real time control
Authors: Jørgensen Michael , Schilling Wolfgang , Harremoës Poul
Published: May 2018

A number of case studies have been carried out in which the potential reduction of combined sewer overflows (CSO) by means of real time control (RTC) is assessed for existing sewer systems. It is an inherent problem of case studies that results cannot necessarily be generalized. In this paper results of a systematic investigation of hypothetical combined sewer systems are presented. The systems were characterized in terms of their topological structure, size, type and arrangement of storage and transport elements.

The RTC optimization model LOCUS was applied to simulate the performance of local control and of optimum control strategies. The results are expressed as “CSO reduction achieved by optimum control, compared to the locally controlled system”.

General conclusions are drawn with respect to possible CSO reduction for a system with given topology, storage and transport characteristics. Finally, these are compared to some case studies reported in the literature in order to verify and show the general applicability of the findings.
Use of ribosomal RNA-based molecular probes for characterization of complex microbial communities in anaerobic biofilms
Authors: Raskin Lutgarde , Amann Rudolf I. , Poulsen Lars K. , Rittmann Bruce E. , Stahl David A.
Published: May 2018

The use of ribosomal RNA (rRNA) probe technology for the characterization of complex microbial communities is reviewed and illustrated by discussing the results of a long-term study of four anaerobic fixed-bed biofilm reactors. Two distinct approaches were used to characterize the microbial community structure in these biofilm reactors. The first used a collection of phylogenetically defined oligonucleotide rRNA probes for methanogens and sulfate-reducing bacteria (SRB) to quantify their populations. Population abundance was linked to the functional behavior of the biofilm reactor community by determining the effluent concentrations of the substrates, intermediates, and final products of microbial metabolism. This analysis indicated that the presence of SRB (especially Desulfovibrio-species) was not dependent upon the presence of sulfate. Methanobacteriales-species were the major competitors for hydrogen with these SRB in the absence of sulfate. The second approach involved selective amplification, cloning, sequencing, and whole cell hybridization to identify, visualize, and isolate a biofilm community member (strain PT-2). Subsequently, it was determined that the growth rate of strain PT-2 was significantly higher in young biofilms than in established biofilms.