bluuebunny/crossref_metadata_2025 huggingface dataset:
Ozone-enhanced photocatalytic degradation of natural organic matter in water
Authors: Zhang P. , Jian L.
Published: September 2006

Ozone-enhanced photocatalytic degradation of macromolecular natural organic matter (NOM) in drinking water source was investigated. The influences of ozone dosage, retention time and bicarbonate concentration on the NOM degradation rate were studied. The change of molecular weight distribution of NOM caused by ozone-enhanced photocatalysis was analysed, as well as the degradation rate of NOM with different molecular weight (MW). It was shown that ozone-enhanced photocatalysis was much better for NOM degradation than sole ozonation or photocatalysis. Increase of both ozone dosage and retention time could effectively increase the TOC removal rate, while biodegradability could be improved solely by an increase in ozone dosage. The existence of bicarbonate significantly reduced the photocatalytic degradation rate of NOM; however, its impact was effectively offset by the addition of ozone into the photocatalytic process. Macromolecular NOM was transformed into smaller molecules, and the larger NOM was mineralized by ozone-enhanced photocatalysis much faster than the smaller NOM.
Optimizing operation rules of waterworks by analysing probability of plant data in north China
Authors: Yongpeng X. , Fuyi C. , Zaigang W. , Zhiwei Z.
Published: September 2006

Optimizing the water treatment system can both ensure satisfactory finished water quality and reduce the operating costs of water treatment. It is difficult to optimize a water treatment system in winter in north China, since the characteristics of raw water are very complicated and change widely by seasons. In this paper, a systematic study of optimizing operating rules of water treatment plants in north China is presented, with the method of analysing a large number of plant data from one northern waterworks. The plant data collected from this water plant is studied with statistic methods, divided into 10 groups and statistical probability of the plant data calculated to determine the influence of optimum operating conditions. From this study, it was found that two direction figures of coagulant dosage and optimum settled water turbidity were determined. According to these two figures, the practice aim of optimum settled water turbidity, which will lead to qualified finished water and low operating costs can be ensured through the direction figure of the optimum settled water turbidity, and then the dosage of coagulation chemicals and coagulant aids will be decided by the direction figure of the coagulant dosage. The results demonstrate that the method can be applied for an estimate quantitative analyses of optimum conditions of a water treatment system.
Effects of Al3 +  and hydraulic characteristics on the removal and behaviour of particles in dissolved air flotation
Authors: Mun Jungsoo , Park Sungwon , Han Mooyoung
Published: September 2006

The removal efficiency of the dissolved air flotation (DAF) process to separate particles from water and wastewater depends on the size and zeta potential of bubbles and particles, the solution and operating conditions, hydraulic characteristics, etc. The effects of aluminium ions and turbulent flow-produced when air-saturated water was spouted into the reactor in the DAF process, on removal and, particle behaviour were on investigated. When bubble size was similar to particle size (10–50 μm), the maximum removal efficiency was 92% in a Kaolin solution of 10−3 M Al3 +  without pre-treatment for flocculation process, and, as time passed, the floc size was observed to increase at a pH of 8, which was the condition of high removal efficiency as seen through image analysis. When the air-saturated water was spouted into the reactor, the size of particle at p.z.c. (point of zero charge) seemed to increase to form a floc due to collision effects caused by turbulent flow. Consequently, floc formation by turbulent flow in the reactor seemed to positively affect removal efficiency.
Quantifying inorganic fouling in a membrane bioreactor treating nitrate-contaminated groundwater using hydrogen as energy source
Authors: Rezania B. , Cicek N. , Oleszkiewicz J.A.
Published: September 2006

A hydrogenotrophic denitrification system, which consisted of a sequencing batch membrane bioreactor, was evaluated for removal of nitrate from a synthetic groundwater feed. A hollow fiber microporous membrane diffuser was used for bubble-less diffusion of hydrogen into the bioreactor, and a membrane filter was used for separating the biomass from treated water. The nitrate loading of 0.328 kg N m−3 d−1 was completely denitrified to below detectable levels; however, inorganic fouling of both membrane filter and diffuser occurred. The increase in pH during denitrification caused inorganic precipitation and clogging of the membranes. The foulant material was quantified as beta three calcium phosphate βCa3 (PO4)2.
Evaluation of treatment methods to reduce the corrosivity of soft waters
Authors: Jaeger Y. , Oberti S. , Guichot L. , Baron J.
Published: September 2006

Soft waters characterised with low alkalinity tend to reduce the lifetime of pipes in drinking water distribution systems. Consequently, the corrosion induced is likely to deteriorate water quality at the consumer's tap. Two different types of treatment methods are commonly used to control the corrosion effects of soft waters: (i) the addition of phosphate corrosion inhibitors, and (ii) the remineralisation process. In order to facilitate the decision making of network operator to use suitable treatment methods, a comparative pilot-scale experiment was performed. The above two treatment strategies were tested using pipes representing both drinking water distribution systems (used materials: cast iron and steel) and household plumbing systems (used material: copper). The impact of the two techniques was assessed by means of water quality monitoring (pH, metal leaching, etc) and of corrosion measurements using electrochemical probes as well as weight-loss coupons. The results obtained after a 15 month long experiment showed that remineralisation method was clearly the most effective way to control soft water corrosion. The implementation of this method resulted in a 50% reduction in metals leaching and about 40% decrease in iron corrosion rates.
Fuzzy model identification and control system design for coagulation chemical dosing of potable water
Authors: Chen C.-L. , Hou P.-L.
Published: September 2006

A practical feedforward control system with fuzzy feedback trim is presented for controlling the dosing strategy of Changhsing Water Purification Plant of Taipei Water Department (TWD). The feedforward move is based on a regression model from successful dosing data between 2001 and 2004. The expert operators' adjusting actions in meeting the settled water turbidity trend and pH values are adopted to establish the fuzzy feedback control rules. A host of field tests have demonstrated the effectiveness of the proposed control strategy.
Technological requirements for water system asset management
Authors: Wu Z.Y.
Published: September 2006

Asset management is a broad term and a relatively new paradigm to the water industry. This paper is intended to present an overview of the asset management approach that emerges as a managerial and technical framework for a water utility to effectively manage above and below ground assets. Based upon the lessons learned from some limited practices in the developed countries including UK, USA, Australia and New Zealand, the article is focused on elaborating the new concept of asset management and technological requirements to implement it for a water or wastewater organization. Following the brief overview, the elements of asset management are addressed along with the classified essential technology that enables water asset management and the potential cost savings resulting from an effective program. It concludes by looking into the challenges and barriers for adopting this innovative approach.
Customer committees, economic regulation and the Water Framework Directive
Authors: Franceys R.
Published: September 2006

Public water monopolies, managed by public officials, often with a supervisory board of elected representatives or senior civil servants, are presumed to operate on behalf of public interests and therefore, though sometimes requiring a leap of faith, the customer interest. Private water monopolies with long-term contracts, where there can be minimal competition for the market let alone in the market, necessarily require some form of regulation, economic and environmental, to maintain public interests. One mechanism to ensure that customer interests are also represented in the regulatory balance is to develop some form of customer involvement through customer committees or councils. The English and Welsh approach to customer involvement in water supply, presently in its fourth iteration as the newly independent Consumer Council for Water, now has to find its role within the framework of the Article 14 requirements of the European Water Framework Directive.
Aspects of particle attachment in filtration
Authors: Kim J. , Lawler D.F.
Published: September 2006

Granular media filtration is used almost universally as the last particle removal process in conventional water treatment plants, but every particle cannot be removed. Laboratory-scale filtration experiments were performed at a filtration velocity of 5 m/h using spherical glass beads with mean diameter of 0.55 mm as collectors; the 10 cm depth ensured particles would be in the effluent. Particle suspensions (Min-U-Sil 5) with 1.7 μm mean particle size were filtered at pH values of 3.0, 4.0, and 5.0, all above the isoelectric point (near pH 2.0). Zeta potential distribution (ZPD) and particle size distribution (PSD) of influent and effluent particles were measured. More favorable particles, i.e. particles with smaller surface charge, were well attached to the collectors during the early stage of filtration. This selective attachment of the lower charged particles caused the ZPD of the effluent to move to a more negative range. However, the ZPD did not keep moving to a more negative range during later stages of filtration, and this result was thought to be caused by two reasons: ripening effects and detachment of flocs. In the early stages of filtration, particles were captured better at pH 3.0 than at the higher pH values (as expected), but this trend reversed at a cumulative hydraulic loading (CHL) of only 5–10 m3/m2. Particle breakoff apparently occurs as flocs of particles that are initially captured individually, as indicated by the trends for different particle sizes. At pH 3.0, particles in the 3–5 μm range had worse removal after a CHL of 5 m3/m2, whereas removal improved through the entire CHL of 20 m3/m2 for all size particles at pH 4.0. Chemical parameters such as zeta potential can be important during the initial stage of filtration, but their importance can decrease over time depending on the specific chemical conditions. The influent particle size distribution and the removal of certain size particles during the initial stage can significantly influence ripening which, in turn, can influence the overall particle removal efficiency. Better initial particle removal does not necessarily mean better overall particle removal.
Variation of dissolved organic matter and microbial regrowth potential through drinking water treatment processes
Authors: Kang M.-G. , Ku Y.-H. , Cho Y.-K. , Yu M.-J.
Published: September 2006

We investigated how various water treatment processes affect AOC (assimilable organic carbon) and MAP (microbially available phosphorus), which nutrient limits microbial growth between organic carbon and phosphorus, and what extent AOC is related to the MW fractions of NOM for raw waters of the Han River and process waters of two water treatment plants in Korea. In view of our results so far achieved, a significant difference was observed between MAP and MAP-P (potential MAP), while little difference was observed between AOC and AOC-P (potential AOC) for raw and pre-chlorinated waters, suggesting that organic carbon limits microbial growth instead of phosphorus. Conventional treatment processes poorly removed AOC-P (42.8%), since the AOC, which was mainly related to the small-molecular DOC, was hardly removed by conventional processes. Oxidants such as chlorine and ozone increased both of the AOC (AOC-P) and MAP (MAP-P), particularly ozone having the stronger oxidation power resulted in a larger increase. However, BAC and GAC removed AOC to less than 60 μg/L which meets the level for biological stability.
Ceramic membranes for direct river water treatment applying coagulation and microfiltration
Authors: Loi-Brügger A. , Panglisch S. , Buchta P. , Hattori K. , Yonekawa H. , Tomita Y. , Gimbel R.
Published: September 2006

A new ceramic membrane has been designed by NGK Insulators Ltd., Japan, to compete in the drinking water treatment market. The IWW Water Centre, Germany, investigated the operational performance and economical feasibility of this ceramic membrane in a one year pilot study of direct river water treatment with the hybrid process of coagulation and microfiltration. The aim of this study was to investigate flux, recovery, and DOC retention performance and to determine optimum operating conditions of NGK's ceramic membrane filtration system with special regards to economical aspects. Temporarily, the performance of the ceramic membrane was challenged under adverse conditions. During pilot plant operation river water with turbidities between 3 and 100 FNU was treated. Membrane flux was increased stepwise from 80–300 l/m2h resulting in recoveries between 95.9 and 98.9%. A DOC removal between about 20–35% was achieved. The pilot study and the subsequent economical evaluation showed the potential to provide a reliable and cost competitive process option for water treatment. The robustness of the ceramic membrane filtration process makes it attractive for a broad range of water treatment applications and, due to low maintenance requirements, also suitable for drinking water treatment in developing countries.
Influence of pretreatment on AMWD (apparent molecular weight distribution) of dissolved organics in the secondary effluent and membrane structure parameter model analysis for ultrafiltration
Authors: Wang L. , Wang X.D. , Chai J.T. , Kang Y.
Published: September 2006

This study analyzed the characteristics of the apparent molecular weight distribution (AMWD) of the secondary effluent organic matter and investigated the effect of various applicable pretreatment technologies for ultrafiltration (UF), including coagulation, powdered activity carbon (PAC) adsorption and O3-PAC process, on the AMWD of effluent and the flux decline. The influence of molecular size distribution on the mean pore size and pore density of membrane was then evaluated with the model of membrane structure parameter. The results showed: (1) after different pretreatments, the AMWD of raw water changed, coagulation could effectively remove high molecular weight organics, PAC adsorption was effective in removing low molecular weight organics, due to ozonization and PAC adsorption and O3-PAC pretreatment could remove both high molecular weight and low molecular weight organics; (2) the AMWD had great influence on membrane permeation, after different pretreatments, the AMWD of raw water changed and the variation of membrane permeation was also different; (3) the influence factors a1and a2 of the mean pore size and the membrane pore density of different pretreatment water samples were used as indexes which calculated through experiment and the model of membrane structure parameter. The influence of AMWD in water samples on the membrane mean pore size and pore density were then evaluated, which showed that low molecular weight organics could easily cause interior adsorption, and high molecular weight organics could easily cause membrane surface blocking.
The fouling of ultrafiltration membranes by natural organic matter after chemical coagulation treatment with different initial mixing conditions
Authors: Kim H.C. , Hong J.H. , Lee S.
Published: September 2006

The flux decline in the UF membrane filtration of water pretreated by chemical coagulation using different initial mixing conditions were compared and the influence of natural organic matter (NOM) on the fouling of membranes was investigated. It was suggested that organic matter in the molecular weight ranges 300–2,000 and 20,000–40,000 Daltons were mainly responsible for the fouling. The fouling was greater for hydrophobic than hydrophilic membranes. ATR-FTIR analysis of the fouled hydrophobic membranes indicated that aliphatic amide and alcoholic compounds as well as polysaccharides contributed to significant membrane fouling. These adsorptive foulants are considered as neutral fractions present in hydrophobic and hydrophilic NOM components. In the case of similar hydrophilic fractions, water precoagulated with a high hydrophobic content resulted in greater flux decline, which was presumed to be due to the organic matter with neutral properties contained within the hydrophobic fraction. The relative concentrations of each NOM fraction in coagulated water are important. Mechanical mixing for chemical coagulation, with a backmixing-type, rather than pump diffusion mixing, with an in-line type, is likely to be more effective at reducing the fouling caused by NOM.
Analysis of phosphorus removal and anaerobic selector performance in a full-scale activated sludge process in Singapore
Authors: Cao Y.S. , Ang C.M. , Raajeevan K.S. , Kiran A.K. , Lai K.C. , Ng S.W. , Zulkifli I. , Wah Y.L.
Published: September 2006

This paper analyses the performance of the anaerobic selector (A/O process) in a full-scale activated sludge process receiving mostly industrial sewage discharge (>60%) in Singapore. In addition to the sludge settleability, enhanced biological phosphorus removal (EBPR) was studied. The sludge volume index (SVI) reduced from 200 to 80 ml g−1 and foaming was suppressed significantly, indicating the effectiveness of the anaerobic selector in improving sludge settleability. The phosphorus removal efficiency was 66%, and 7.5 mg HAc-COD was consumed per mg PO3−4-P removed. In the anaerobic compartment, 31% of the SCOD and 73% of the acetic acid in the settled sewage were removed with PO3−4-P release of 14.1 mg PO3−4-P l −1. The linear correlation between PO3−4-P release in the anaerobic compartment and PO3−4-P uptake in the aerobic compartment indicates that there is about 0.8 mg PO3−4-P release in the anaerobic compartment per mg PO3−4-P uptake in the aerobic compartment. The fates of volatile fatty acids (VFAs) and its short chain acids (SCAs) in the process were studied and discussed.
Chromate sorption and reduction kinetics onto an aminated biosorbent
Authors: Deng S. , Ting Y.P. , Yu G.
Published: September 2006

A novel biosorbent was prepared by chemically grafting of polyethylenimine (PEI) onto the fungal biomass of Penicillium chrysogenum through a two-step reaction. The modified biosorbent is favorable for the removal of anionic Cr(VI) species from aqueous solution due to the protonation of amine groups on the biomass surface. The sorption capacity for Cr(VI) increased by 7.2-fold after surface modification. Sorption kinetics results show that the pseudo-second-order kinetic model described the experimental data well. During the sorption process, X-ray photoelectron spectroscopy (XPS) was used to analyze the chromium species on the biosorbent surface and the results indicate that part of the Cr(VI) ions were reduced to Cr(III) ions which can be chelated with the amine groups on the biomass surface. The reduced Cr(III) ions formed some aggregates on the surface at higher solution pHs.
Nucleic acids: indicators for dynamic processes of clogging in soil filter systems
Authors: Schwarz M. , Fuchs S. , Hahn H.H.
Published: September 2006

A high-performance liquid chromatography (HPLC)-method was established to quantify the development and degradation of DNA, rRNA and tRNA in the Langenalb soil filter fed with combined sewer overflow. The DNA served as a parameter for the microbial biomass and the RNA/DNA ratio for the growth rate. For nucleic acids, quantification samples were taken at different depths and sections of the clogged and the unclogged soil filter. Highest DNA concentrations were found at a depth of 0–2 cm in the clogged soil filter. During a starvation period of three months the DNA- and RNA-concentrations decreased twofold at depths between 0–8 cm. The higher nucleic acid concentrations at depths of 10–40 cm in the unclogged soil filter were attributed to a shift of the starved microorganisms. Similar RNA/DNA ratios in the clogged and the unclogged soil filter indicate similar growth rates and metabolic activities. It could be proven that the clogging of the soil filter was due to the microbial biomass and the DNA concentration, respectively.
Observation and mathematical description of the acceleration phenomenon in batch respirograms associated with ammonium oxidation
Authors: Guisasola A. , Chandran K. , Smets B.F. , Baeza J.A. , Carrera J. , Lafuente J.
Published: September 2006

Two-step nitrification models are generally calibrated using short-term respirometric batch experiments. Important discrepancies appear between model predictions and experimental observations just after the pulse addition since a fast transient in the OUR profile is experimentally observed. Acceleration of the OUR appears ongoing between the substrate addition and attainment of the maximum OUR value. Among the several phenomena that could contribute to this observation, the most probable cause is the limitation of reducing equivalents required for maximal ammonia monooxygenase activity at the time of substrate addition. Ignoring acceleration would result in large parameter estimation errors from respirometric batch experiments. This work proposes a simple methodology to successfully describe (not to explain) the acceleration phenomenon estimating only two parameters. This methodology consists of introducing a Gaussian-like expression in the model.
Simple approaches towards the design of an attached-growth sponge bioreactor (AGSB) for wastewater treatment and reuse
Authors: Ngo H.H. , Nguyen M.C. , Sangvikar N.G. , Hoang T.T.L. , Guo W.S.
Published: September 2006

Wastewater treatment and reuse is being emphasized due to the shortage of water sources and the continuous deterioration of the aquatic environment. In this study, a novel sponge bioreactor was studied as a low cost, high efficiency alternative for an attached growth biological system. This was designed by combining of number of sponge trays. This emerging technology has many beneficial properties in wastewater treatment and reuse. The approaches towards the conditions for system design were: (i) selection of sponge types; (ii) selection of sponge shapes; and (iii) selection of designated slope of sponge tray. They were determined through a series of experiments using a laboratory-scale unit with synthetic wastewater. It was then tested with a pilot-scale unit at the predetermined optimum conditions. The results indicate that the highest biomass growth was found at the sponge type with a cell count of 70–90 cells/in2 (6.45 cm2) The relationship between biomass growth and biological oxygen consumption was well established. The prism-shaped sponge (triangular polyurethane sponge of 70–90 cells/in2 with designated slope of sponge tray at 10 degrees) led to the best performance in terms of both organic and nutrient removal efficiency.
Microbial population structure changes in a suspended carrier biofilm reactor
Authors: Wang R.C. , Wen X.H. , Qian Y.
Published: September 2006

The changes of microbial population structure in biofilm caused by variations of COD/NHNH+4-N ratio in influent were investigated in a suspended carrier biofilm reactor (SCBR). When COD/NHNH+4-N was 10, the highest COD removal reached was about 73.8 per cent, whereas the highest NH+4-N removal, about 55.9 per cent, was reached when COD/NH+4-N was 5. By using fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM) observation, it was found that the thickness of the biofilm formed on the carrier was about 80 to 120 μm, and ammonia-oxidizing bacteria (AOB) and nitrifying bacteria existed mainly in the upper layer about 20 to 30 μm. The results of the quinone profile analysis showed that when the COD/NH+4-N increased, the microbial diversity (DQ) increased, while the proportions of AOB and nitrifying bacteria in the biofilm communities decreased.
Production and characterization of scum and its role in odour control in UASB reactors treating domestic wastewater
Authors: Souza C.L. , Silva S.Q. , Aquino S.F. , Chernicharo C.A.L.
Published: September 2006

There are few studies in the literature that have aimed at characterizing the physical, chemical, and microbial aspects of scum produced in UASB reactors. In addition, there is little information on the influence of operational conditions of UASB reactors on scum formation, and the present work addresses these issues. Three demo-scale UASB reactors, fed on domestic wastewater, were employed to monitor the formation and its characteristics. Scum production was periodically assessed during different operational phases, and its characterization involved analyses of BOD, COD, solids, sulfide, sulfate, microscopic observations, as well as biodegradability tests. The results show that the scum formed was physically, chemically, and microscopically similar in both geminated reactors, being comprised mainly of organic material of low biodegradability. Several bacterial morphotypes, mainly filaments and rods, with internal sulfur granules, were observed, and the aerobic microorganisms that developed at the scum layer as a result of photosynthetic activity of cyanobacteria, seemed to play an important role in sulfide removal and odour control. Scum production rates were similar in both reactors, but the imposed higher upflow velocities resulted in a higher production rate and in a reduced biodegradability of the scum.
Aerobic production of activated sludge polyhydroxyalkanoates from nutrient deficient wastewaters
Authors: Punrattanasin W. , Randall A.A. , Randall C.W.
Published: September 2006

It was found that aerobic strategies combined with multiple nutrient limitations produced greater quantities of polyhydroxyalkanoates (PHAs) than strategies relying on oxygen limitation (either micro-aerophilic or anaerobic/aerobic). This was true both for a synthetic wastewater composed of acetic and propionic acid, and also for a nutrient deficient industrial wastewater. PHA/substrate yields were shown to be comparable to axenic systems for many operating strategies analyzed, and it was found that PHA composition could be affected by process operational conditions. The molecular weight and melting point of the PHA produced were found to be in a desirable range with respect to material properties, which have not been well studied in the previous literature for mixed cultures (Salehizadeh and Van Loodsrecht, 2004). The effects of process staging, multiple treatment cycles, and inocula source were also addressed.
The main wastewater treatment plant of Vienna: an example of cost effective wastewater treatment for large cities
Authors: Wandl G. , Kroiss H. , Svardal K.
Published: September 2006

Two-stage activated sludge plants succeed in stable treatment efficiency concerning carbon removal and nitrification with far less reactor tank volume than conventional single stage systems. In case of large treatment plants this fact is of great economic relevance. Because of the very small specific volume of these two-stage treatment plants in comparison with low loaded single-stage plants, internal cycles have to be applied to ensure sufficient nitrogen removal. Due to these internal cycles two stage activated sludge plants offer many possibilities in terms of process management which results in new process optimisation procedures as compared to conventional single-stage nutrient removal treatment plants. The proposed extension concept for the Main Treatment Plant of Vienna was validated with pilot plant investigations especially with regard to nitrogen removal where it proved to comply with the legal requirements. The operation of the treatment plant can easily be adapted to changes in temperature and sludge volume index occurring in full scale practice. Sludge retention time and aerobic volume in the second stage are controlled in order to secure sufficient nitrification capacity and to optimise nitrogen removal by means of the variation of the loading conditions for the two stages. The investigations confirmed that the specific two-stage activated sludge concept applied in Vienna is an economically advantageous alternative for large wastewater treatment plants with stringent requirements for nitrification and nutrient removal.
Upflow anaerobic sludge blanket (UASB) treatment of supernatant of cow manure by thermal pre-treatment
Authors: Yoneyama Y. , Nishii A. , Nishimoto M. , Yamada N. , Suzuki T.
Published: September 2006

Upflow anaerobic sludge blanket (UASB) methane fermentation treatment of cow manure that was subjected to screw pressing, thermal treatment and subsequent solid–liquid separation was studied. Conducting batch scale tests at temperatures between 140 and 180 °C, the optimal temperature for sludge settling and the color suppression was found to be between160–170 °C. UASB treatment was carried out with a supernatant obtained from the thermal treatment at the optimal conditions (170 °C for 30 minutes) and polymer-dosed solid–liquid separation. In the UASB treatment with a CODCr loading of 11.7 kg/m3/d and water temperature of 32.2 °C, the CODCr level dropped from 16,360 mg/L in raw water to 3,940 mg/L in treated water (CODCr removal rate of 75.9%), and the methane production rate per CODCr was 0.187 Nm3/kg. Using wastewater thermal-treated at the optimal conditions, also a methane fermentation treatment with a continuously stirred tank reactor (CSTR) was conducted (CODCr in raw water: 38,000 mg/L, hydraulic retention time (HRT): 20 days, 35 °C). At the CODCr loading of 1.9 kg/m3/d, the methane production rate per CODCr was 0.153 Nm3/kg. This result shows that UASB treatment using thermal pre-treatment provides a CODCr loading of four times or more and a methane production rate of 1.3 times higher than the CSTR treatment.
Nitrogen removal rates at a technical-scale pilot plant with the one-stage partial nitritation/Anammox process
Authors: Cema G. , Szatkowska B. , Plaza E. , Trela J. , Surmacz-Górska J.
Published: September 2006

Traditional nitrification/denitrification is not suitable for nitrogen removal when wastewater contains high concentrations of ammonium nitrogen and low concentrations of biodegradable carbon. Recently, a deammonification process was developed and proposed as a new technology for treatment of such streams. This process relies on a stable interaction between aerobic bacteria Nitrosomonas, that accomplish partial nitritation and anaerobic bacteria Planctomycetales, which conduct the Anammox reaction. Simultaneous performance of these two processes can lead to a complete autotrophic nitrogen removal in one single reactor. The experiments where nitrogen was removed in one reactor were performed at a technical-scale moving-bed pilot plant, filled with Kaldnes rings and supplied with supernatant after dewatering of digested sludge. It was found that a nitrogen removal rate obtained at the pilot plant was 1.9 g m−2d−1. Parallel to the pilot plant run, a series of batch tests were carried out under anoxic and aerobic conditions. Within the batch tests, where the pilot plant's conditions were simulated, removal rates reached up to 3 g N m−2d−1. Moreover, the batch tests with inhibition of Nitrosomonas showed that only the Anammox bacteria (not anoxic removal by Nitrosomonas) are responsible for nitrogen removal.
E. coli transport in soil columns: implications for reuse of treated wastewater in irrigation
Authors: Smith E. , Hegazy S.
Published: September 2006

Reuse of treated wastewater in irrigation is gaining recognition as a vital element in the water resources management plan of developing countries, especially those situated in arid and semi-arid regions. An understanding of the transport of residual pollutants from treated wastewater, such as bacteria, in soil as a result of irrigation is critical to assessing health risks and the possible contamination of limited groundwater resources. In this work, retention of E. coli is evaluated for a soil that is irrigated by treated wastewater for growth of non-food crops near Egypt's Red Sea coast. In particular, the effects of soil organic fraction (SOF) and hydraulic loading rate (HLR) were investigated in laboratory soil columns. The matrix of experiments included three HLRs and three SOFs. The retention of bacteria by adsorption was observed at HLRs of 5 and 13 cm/h, with the magnitude of the adsorption increasing proportionally to the SOF. The impact of SOF was greater for the lower HLR. At the lowest HLR investigated (5 cm/h), filtration was also observed for the two higher SOFs (0.674 and 2.04 per cent). At a high HLR (66 cm/h) simulating flood irrigation, retention of bacteria was minimal regardless of the SOF. Since the bacterial solution is applied to a dry soil column to simulate field conditions, E. coli breakthrough after two pore volumes of throughput (vs. one) provided a meaningful comparison of bacterial retention as a function of HLR and SOF.
Microbial community change of sulfate reduction and sulfur oxidation bacteria in the activated sludge cultivated with acetate and peptone
Authors: Miyazato N. , Yamamoto-Ikemoto R. , Takamatsu S.
Published: September 2006

The growth of sulfate reducing bacteria (SRB) and filamentous sulfur bacteria was monitored on a laboratory scale in activated sludge reactors using acetate and peptone as the artificial wastewater. When the artificial wastewater contained acetate and peptone, filamentous bacteria increased in the sludge and the SVI values increased. There was a good correlation between sulfate reducing activity and sulfur oxidation activity in the produced sludge. The microbial community change of filamentous sulfur bacteria and sulfate reducing bacteria was analyzed using the fluorescent in situ hybridization (FISH) method. The tendency for the growth of filamentous sulfur bacteria Thiothrix eikelboomii following the growth of SRB was observed. The percentage of SRB385- hybridized cells and DNMA657-hybridized cells found in the total cell area increased from 2–3% to 7–10% when the filamentous bulking occurred.
Indepth diagnosis of a secondary clarifier by the application of radiotracer technique and numerical modeling
Authors: Kim H.S. , Shin M.S. , Jang D.S. , Jung S.H.
Published: September 2006

To make an indepth diagnosis of a full-scale rectangular secondary clarifier, an experimental and numerical study has been performed in a wastewater treatment facility. Calculation results by the numerical model with the adoption of the SIMPLE algorithm of Patankar are validated with radiotracer experiments. Emphasis is given to the prediction of residence time distribution (RTD) curves. The predicted RTD profiles are in good agreement with the experimental RTD curves at the upstream and center sections except for the withdrawal zone of the complex effluent weir structure. The simulation results predict successfully the well-known flow characteristics of each stage such as the waterfall phenomenon at the front of the clarifier, the bottom density current and the surface return flow in the settling zone, and the upward flow in the exit zone. The detailed effects of density current are thoroughly investigated in terms of high SS loading and temperature difference between influent and ambient fluid. The program developed in this study shows the high potential to assist in the design and determination of optimal operating conditions to improve effluent quality in a full-scale secondary clarifier.
Modelling hydrogen sulphide emission in a WWTP with UASB reactor followed by aerobic biofilters
Authors: Santos J.M. , Sá L.M. , Reis Junior N.C. , Gonçalves R.F. , Siqueira R.N.
Published: September 2006

Hydrogen sulphide (H2S) represents one of the main odorant gases emitted from wastewater treatment plants (WWTP) and a mathematical model can be a fast and low cost tool to estimate its emission. In this work H2S emission rates in a WWTP, composed of an up-flow anaerobic sludge blanket (UASB) reactor and an aerobic biofilter (BF), are estimated using four mathematical models available in the literature (AP-42, GPC, TOXCHEM+ and WATER8). The results show that the GPC model leads to the best agreement with the experimental data, except for the biofilter due to its lack of capability to include biodegradation as a H2S removal process. On the other hand, the AP-42 and WATER8 models showed a slightly better ability to predict H2S removal in the biofilter than the TOXCHEM+ model, as all models underestimate the H2S concentration decay.
Biological Cr(VI) reduction in indigenous sludge cultures from Gauteng, South Africa
Authors: Molokwanne P.E. , Chirwa E.M.N.
Published: September 2006

The Cr(VI) reducing capability of an acclimated indigenous culture cultivated from primary sludge was evaluated in batch and packed-bed bioreactor systems. Performance evaluation was carried out in unmodified cultures, cultures modified by substituting terminal organisms in the consortium by a known Cr(VI)-reducing organism (Escherichia coli ATCC 33456), and pure cultures of Cr(VI)-reducing organisms. A high Cr(VI) reduction rate was observed in modified cultures and in the pure culture of the Cr(VI)-reducing bacteria (Bacillus sp.). Furthermore, the Bacillus sp. pure culture outperformed both the unmodified and modified consortium cultures in reducing Cr(VI). Abiotic Cr(VI) reduction activity was evaluated in heat-killed and azide (N3−) inactivated control cultures. No significant Cr(VI) reduction was observed in the controls. This study is part of the continuing research to identify synergistic culture systems for treating toxic compounds from polluted environments.
Removal of endocrine-disrupting chemicals by ozonation in sewage treatment
Authors: Zhang Heqing , Yamada Harumi , Kim Sung-Eun , Kim Hyo-sang , Tsuno Hiroshi
Published: September 2006

Treatment experiments by two laboratory scale semi-batch reactors and a demonstration scale process were both carried out to evaluate endocrine disrupting chemical removal characteristics by ozonation in sewage treatment. In the semi-batch mode experiments, secondary effluent and primary effluent of sewage treatment plants were ozonated respectively. Behaviour of brominated by-products was also evaluated. The results based on these studies indicated that estrogenicity in wastewater can be removed by ozonation effectively. The condition of ozonation until dissolved ozone concentration increased to 0.1 mg/L, which corresponded to 1 mgO3/mgC and 0.4 mgO3/mgC of ozone consumption per initial DOC for secondary effluent and primary effluent, respectively, is proposed as an appropriate operational condition for efficient removal of EDCs as well as UV254 and SUVA without production of brominated by-products.
Analysis of off-flavor compounds in water at sub part per trillion level by GC/MS with programmable temperature vaporizer inlet
Authors: Zhang L. , Hu R. , Yang Z.
Published: September 2006

“Earthy-musty” off-flavor problems in water samples are due to organic compounds present at the sub part per trillion level. Most of the studies in the analysis of tastes and odorous compounds focus on the extraction pre concentration technique, with detection at picogram per liter level of the earthy-musty off-flavor compounds, which are difficult to achieve. The objective of this study is to develop a new method involving the GC/MS with programmable temperature vaporizer (PTV) inlet via large volume injection (LVI) or solid phase micro-extraction (SPME), to attain analytical sensitivity equal to or better than olfactory sensitivity. Six “earthy-musty” organic compounds; 2-methylisoborneol (MIB); geosmin; 2, 4, 6-trichloroanisole (2,4,6-TCA); 2, 3, 6-trichloroanisole (2,3,6-TCA); 2, 3, 4-trichloroanisole (2,3,4-TCA); and 2, 4, 6-tribromoanisole (2,4,6-TBA), were used as probes for this study. It was found that LVI via PTV could greatly improve system sensitivity towards the detection of off-flavor compounds with low volatility such as haloanisoles. For those off-flavor compounds with high volatility, eg MIB, SPME coupled with PTV-GC-MS with cool initial temperature has always demonstrated the best sensitivity.
High‐Resolution Fourier Transform Spectrometry of Gases
Authors: Guelachvili Guy , Picqué Nathalie
Published: September 2006

This article mainly focuses on the experimental aspects of high‐resolution Fourier transform spectroscopy (FTS) as applied to molecular gas studies. The main characteristics and peculiarities of Doppler‐limited vibrational spectroscopy of gases and some of the current trends in the technique are discussed using select examples.

An introduction to the general appearance of high‐resolution absorption and emission Fourier transform (FT) spectra is given. The specific advantages of the two most common FT recording procedures: the fast‐scanning and the stepping‐mode approaches are discussed. Some of the important scientific results that may be obtained in high‐resolution vibrational spectrometry using FTS are reviewed. Finally, recent developments on selective modulations and time‐resolved FTS are presented. About 300 references (titles included) provide a comprehensive overview of the various aspects of the ongoing applications.
Far‐Infrared Spectroscopy
Authors: Griffiths Peter R.
Published: September 2006

The far‐infrared spectral region is defined and transitions that absorb radiation in this region are discussed. The intramolecular vibrations of small organic and inorganic compounds that absorb in the far‐infrared region include stretching modes involving heavy atoms, skeletal bending modes, and torsional and ring‐puckering vibrations. Intermolecular vibrations of small molecules that absorb in the far infrared include hydrogen bonds and liquid lattice bands. The phonon bands of inorganic solids are briefly discussed. Intramolecular vibrations of polymers that absorb in the far‐infrared polymers can be due to localized torsions of individual functional groups and modes that are more delocalized along the chain. Intermolecular vibrations of polymers that are observed in the far infrared include rotatory and translatory motions of the chains. Absorption may also be induced by disorder and by the presence of impurities that have been either deliberately or accidentally introduced. Finally, the rotational transitions of small molecules in the vapor‐phase that absorb far‐infrared radiation are discussed.
R
aman Spectroscopy: Theory
Authors: Keresztury Gábor
Published: September 2006

A general introduction is given to the principles and theory of Raman spectroscopy, the discipline dealing with spectral analysis of inelastic scattering of light by the vibrating molecules in liquids, solids, or gases – the phenomenon called Raman scattering. The origin of Raman scattering and its association with molecular polarizability is outlined in this article. The frequency relations of the vibrational Raman effect are developed in terms of the classical theory of electromagnetic radiation. A simplified description of the factors governing the directional properties, intensity relations, and polarization characteristics of the scattered radiation are given by the classical theory, which are then refined according to a partial quantum mechanical treatment. The vibrational selection rules including the role of molecular symmetry are demonstrated using select examples of diatomic and polyatomic molecules, contrasting infrared and Raman spectroscopy and emphasizing their complementary nature.
Instrumentation for Step‐ScanFT‐IRModulation Spectrometry
Authors: Manning Christopher J.
Published: September 2006

Sample modulation measurements have made possible significant advances in the understanding of complex systems. Appropriate Fourier transform infrared (FT‐IR)–based instrumentation for measuring the spectral changes induced by sample modulation is described in detail. Small spectral changes can result from a variety of perturbations, including electrochemical, mechanical strain, photoexcitation and others, that are too numerous to list. The renaissance of the step‐scan technique was an important step toward widespread application of sample modulation techniques. Ubiquity of powerful computers has been particularly enabling. The advantage of step‐scan operation is that it removes the time dependence of the spectral encodement, thereby simplifying data acquisition and processing for the time‐dependent signals that result from sample modulation. A few representative examples from the literature are briefly reviewed and likely future innovations are described.
F
abry–
P
erot Interferometers for Mid‐Infrared Spectroscopy
Authors: Iwata Tetsuo
Published: September 2006

The sections in this article are

Fundamentals of the
F
abry–
P
erot Interferometer

Intensity Transmittance

Angular Dispersion and the Interval of the Interference Order

Free Spectral Range and Finesse

Optical Throughput and Theoretical Resolution

Wavelength Scanning

Extension of the Spectral Range

Synchronized Scanning of the Grating Monochromator and the

FPS

A Combination of the Spectrograph and the

FPS

Multiple

FP

Etalon Arrangement

Using the

FPI

as a Multichannel Wavelength Sampler

Multiplex

FP

Spectrometer

Confocal

FPI
Detectors for Mid‐ and Far‐Infrared Spectrometry: Selection and Use
Authors: Theocharous E. , Birch J.R.
Published: September 2006

This article is aimed at those who want to identify the most appropriate photodetector for their particular measurement application in the infrared or who wish to use their chosen detector under its optimum operating conditions. The article summarises the most important parameters governing the performance of infrared detectors and provides explanations as to how these parameters affect detector performance. The best procedure for identifying the most appropriate detector technology with a particular active area to fulfil a particular application is highlighted. The importance of the detector preamplifiers in determining the performance of an infrared detection system based on photon detectors is discussed. The merits of thermal and photon detectors are explained before the characteristics of different thermal and photon detectors are summarised.
Fast Time‐Resolved Mid‐Infrared Spectroscopy Using an Interferometer
Authors: Smith Gregory D. , Palmer Richard A.
Published: September 2006

Fast time‐resolved mid‐infrared (MIR) spectroscopy provides an effective tool to study transient chemical species and dynamic systems. Although several laser‐based approaches to time‐resolved IR offer extremely high time resolution, Fourier transform time‐resolved infrared (FT‐TRIR) techniques have a distinct advantage over these methods, particularly in terms of spectral bandwidth and spectral resolution. Depending on the time resolution required, interferometric techniques based on rapid and ultra‐rapid scanning, stroboscopic sampling, step‐scanning, or asynchronous sampling are capable of covering time domains from seconds to picoseconds. This article reviews the theory of operation of these techniques, their instrumental requirements, specific caveats, advantages and limitations, current applications, and the state of the art.
Instrumental Aspects of Time‐Resolved Spectra Generated Using Step‐Scan Interferometers
Authors: Rödig Christoph , Siebert Friedrich
Published: September 2006

The sections in this article are

Introduction

Principle of Time‐Resolved Step‐ScanFTMeasurements and Instrumental Considerations

Quantities to be Measured

Aspects of Detector Performance

Signal Fluctuations

Mirror Fluctuations and Refractive Index Fluctuations

Studies of Slow‐Cycling Systems and Irreversible Reactions