bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of two approaches to model chlorine residuals in Severn Trent Water Ltd (STW) distribution systems
Authors: Rodriguez M.J. , West J.R. , Powell J. , Sérodes J.B.
Published: May 2018

Increasingly, those who work in the field of drinking water have demonstrated an interest in developing models for evolution of water quality from the treatment plant to the consumer's tap. To date, most of the modelling efforts have been focused on residual chlorine as a key parameter of quality within distribution systems. This paper presents the application of a conventional approach, the first order model, and the application of an emergent modelling approach, an artificial neural network (ANN) model, to simulate residual chlorine in a Severn Trent Water Ltd (U.K.) distribution system. The application of the first order model depends on the adequate estimation of the chlorine decay coefficient and the travel time within the system. The success of an ANN model depends on the use of representative data about factors which affect chlorine evolution in the system. Results demonstrate that ANN has a promising capacity for learning the dynamics of chlorine decay. The development of an ANN appears to be justifiable for disinfection control purposes, in cases when parameter estimation within the first order model is imprecise or difficult to obtain.
Identification and characterization of water quality transients using wavelet analysis. I. Wavelet analysis methodology
Authors: Dohan Kathleen , Whitfield Paul H.
Published: May 2018

The methodology used in the identification and characterization of transient water quality events using wavelet transforms is described. The use of wavelets in the analysis of transient events is a distinct improvement over the methods which have been used previously, as wavelets are better suited to aperiodic processes than frequency decomposition. The methods presented here allow us to identify the location, duration and magnitude of a transient event in a water quality time series.
Application of constructed wetlands for wastewater treatment in Hungary
Authors: Lakatos Gyula , Kiss Magdolna K. , Kiss Marianna , Juhász Péter
Published: May 2018

This paper presents a brief survey of the Hungarian constructed wetland types that have been established for wastewater treatment in the last thirty years, and gives an analysis of the design and performance of those reed ponds that have been constructed for the polishing of petrochemical wastewaters. Natural treatment processes are in great demand because they are protective of the environment and have low operation costs and satisfactory purification efficiency. Three major types of treatment wetlands are utilized in Hungary: free water surface system, subsurface flow system, and artificial floating meadow system. Since the 1970s, the petrochemical industry has utilized sewage treatment systems consisting of ponds of emergent and/or submerged macrophyte vegetation that operate as free water surface systems. In the wastewater treatment system of Nyirbogdány, the average COD removal efficiency is around 60%, while the reed-submerged weeds pond has an efficiency of 25%. In the reed pond of the TIFO post-treatment pond system, the total phosphorus removal averaged 40% for several years, while the nitrogen removal efficiency has not exceeded 35%. For both constructed wetlands, the nutrient stabilising and heavy metal accumulating role of the aquatic plant-periphyton complex has been quantified, and the biological water quality has been found to be typical of any other natural water bodies.
Rotating biological contactor-solid contact system for the treatment of wastewater from small communities
Authors: d'Antonio Giuseppe , Mendia Luigi , Pirozzi Francesco , Polese Arturo
Published: May 2018

In Rotating Biological Contactor (RBC) WasteWater Treatment Plants (WWTP) the fixed film unit effluent quality can be improved by means of a biological refinement system, consisting of an aerated Solid Contact (SC) unit. This process, known as an RBC/SC system, is an alternative to other tertiary treatment systems and can be used with good results in the new WWTPs of small communities and in upgrading existing RBC plants whose effluents no longer respect the established standards. The results of an experimental study on an RBC/SC dual biological system fed with clarified municipal sewage are presented and used to validate a new concept mathematical model of each system's phase behaviour. RBC removal efficiency proved to be near stable for total COD while it tended to decrease for particulate COD at higher load values. The aerated SC phase allowed the overall removal efficiency to be improved; the main advantage was observed in the suspended matter removal increase (averaging 26%), while for total and soluble COD the increases averaged 18 and 17% respectively.
Adsorption of Cr(VI) onto TiO2 from dilute aqueous solutions
Authors: Weng C. H. , Wang J. H. , Huang C. P.
Published: May 2018

Cr(VI) adsorption onto TiO2 (anatase) particles was performed in batch equilibrium experiments. Results showed that pH was the key factor affecting the adsorption characteristics. The marked adsorption was observed under acidic condition and the adsorption capacities decreased with increasing pH, temperature, and ionic strength. The adsorption obeyed the Langmuir adsorption isotherm and the maximum adsorption capacities were determined at specific pH values. A surface complex formation model was proposed to describe the adsorption reaction between aqueous chromates and TiO2 solid surface. Because the magnitude of electrostatic energy, the adverse solvation, and lateral interaction energy which contribute to the total adsorption are relatively small in comparison with the specific chemical energy, we conclude that the specific chemical interaction is the major mechanism responsible for the adsorption process.
Removal of arsenic(V) ion from aqueous solutions by lanthanum compounds
Authors: Tokunaga Shuzo , Wasay Syed A. , Park Sang-Won
Published: May 2018

A new adsorption process for the removal of As(V) ion from aqueous solutions has been studied using lanthanum hydroxide (LH), lanthanum carbonate (LC) and basic lanthanum carbonate (BLC). These La compounds were effective in removing As ion to decrease the concentration down to < 0.001 mM. Dissolution of these La compounds was measured in the pH range of 2 to 12. The dissolution was appreciable at initial pH <4.3, <4.3 and <4.0 for LH, LC and BLC, respectively. Kinetic study showed that the As removal was a first-order reaction in the neutral pH range and the rate constants were in the order of LH > LC > BLC. The As removal was highly pH-dependent. The optimum pH range was 3-8, 4-7 and 2-4 for LH, LC and BLC, respectively. The following two mechanisms are proposed: (i) adsorption by exchange of CO3 and/or OH group with As ions in the neutral to alkaline pH range where La does not dissolve and (ii) precipitation of insoluble lanthanum arsenate, LaAsO4, in the acid pH range.
Breakthrough curve for adsorption of mercury (II) on polyaminated highly porous chitosan beads
Authors: Kawamura Yoshihide , Yoshida Hiroyuki , Asai Satoru , Tanibe Hiroaki
Published: May 2018

The equilibrium isotherm and the breakthrough curve for adsorption of Hg(II) on polyaminated highly porous chitosan beads (PEI-CS) were compared with those for Unicellex UR-120H which was the best commercial chelate resin for removal of Hg(II) in Japan. As the intraparticle effective diffusivity Deff in PEI-CS was about two times larger than that in UR 120H, and adsorption capacity Hg(II) on PEI-CS was also larger than that on UR-120H, adsorption of Hg(II) on PEI-CS appeared feasible technically. The intraparticle concentration profiles of Hg(II) were measured for different period of time using X-ray micro-analyzer. The value of Deff was almost constant at 4 Re′ 7, and the mean value was 3.86 × 10−12 m2/s. The value od Deff increased in proportion to the influent concentration of Hg(II) Co,Hg. The pore diffusivity and surface diffusivity were determined using Deff based on the parallel transport model of surface and pore diffusions. The result showed that both the pore and surface diffusions of Hg(II) in PEI-CS particle were significant.
Diffusion and sorption of water vapor and benzene within a dry model soil organic matter
Authors: Lin Tsair-Fuh
Published: May 2018

The sorption behavior of water vapor and benzene within a dry model soil organic matter (SOM), peat, was studied. An electrobalance system was employed to determine both the equilibrium sorption isotherm and sorption-desorption kinetics. The sorption isotherm for water vapor was found to resemble that previously reported for this sample, while the sorption isotherm for benzene could not be determined, due to a failure to obtain reproducible sorption capacity. In the kinetic study, strong asymmetries between sorption and desorption rates were observed for both water vapor and benzene. Two diffusion models, accounting for either gas-phase pore diffusion within peat grains or solid-phase diffusion within microspheres of SOM, were used to interpret the asymmetric sorption rate data. Considering gas-phase pore diffusion only, the model resolved the asymmetry of sorption rates and described the experimental data very well for water vapor at three different concentrations. However, the pore diffusion model failed to capture the dominant feature of the experimental data for benzene. As a refinement, a model assuming that solid-phase intra-SOM diffusion is the rate-limiting mechanism produced a better description of the experimental data.
Sorption characteristics of biological powdered activated carbon in BPAC-MF (biological powdered activated carbon-microfiltration) system for refractory organic removal
Authors: Seo G. T. , Ohgaki S. , Suzuki Y.
Published: May 2018

The sorption characteristic of biological powdered activated carbon (BPAC) were investigated in a hybrid membrane process which was accomplished by introducing powdered activated carbon (PAC) into a crossflow microfiltration system and seeding microorganisms. This combined process was designated BPAC-MF and could be an alternative system for reclamation of secondary sewage effluent. Experiments were carried out to identify the ability of BPAC to remove various dissolved refractory organic matter in secondary sewage effluents such as peptone, beef extract, lauryl sulfate, humic acid, tannin, lignin and gum arabic. Adsorption test by fresh powdered activated carbon (PAC) showed significantly different adsorption characteristics for each organic substance. These adsorption characteristics were identified by the analysis of gel permeable chromatography (GPC). The sorptive capacity of BPAC was almost four times higher than that of fresh PAC. This phenomenon could be explained from the sorption capacity of PAC and BPAC for each substance. For the hardly adsorbable refractory organics, humic acid and gum arabic, the sorption capacity of bPAC was 12.1 and 8.7 mg/g respectively. These values are significantly high compared with 3.6 and 0.2 mg/g obtained by PAC. It was estimated that the enhanced sorption capacity of BPAC was due to the stimulation of activated carbon adsorption by biological effect.
Removal of organic substances from water by ozone treatment followed by biological activated carbon treatment
Authors: Takeuchi Yasushi , Mochidzuki Kazuhiro , Matsunobu Noriyuki , Kojima Ryozo , Motohashi Hiroshi , Yoshimoto Syunichi
Published: May 2018

As an advanced water treatment, a combination of ozonation and biological activated carbon (BAC, hereafter) treatment is being applied to purify raw water for municipal use in some cases. The authors examined effects of ozonation on water quality in a batch system, using water samples containing organic substances fractionated to several molecular weight ranges. Also, a flow test of laboratory-scale was performed to study on the capability of the treatment in terms of removal efficiency of the dissolved organic substances, e.g., fumic substances, which preoxidized with ozone. As a result, the changes in equilibrium adsorption and in the biodegradability of organic substances dissolved in water before and after oxidation with ozone were made clear.
Purification of polluted river water by ultrafiltration-ozonization-biological activated carbon filtration
Authors: Park Y.-K. , Lee C.-H. , Lee S.-H. , Jang N.-Y.
Published: May 2018

The main Nakdong river water mixed with polluted Kumho river was used as raw water in this research. The removal efficiencies of TOC and UV254 nm absorbance in the ultrafiltration process were both approximately 15% higher than those in the coagulation/rapid sand filtration process. In the biological activated carbon filter, the ammonia nitrogen removal efficiency goes up to over 90% after 35 days of operation in the early spring at empty bed contact time (EBCT) of 25 min. At EBCT of 25 min, the removal of TOC and UV254 nm absorbance were higher by about 5% and 10%, respectively, than at EBCT of 10 min. By the combination of ozonization to ultrafiltration-biological activated carbon process, the AOX and THM formation potential were effectively reduced.
Selective adsorption on fibrous activated carbon of organics from aqueous solution: correlation between adsorption and molecular structure
Authors: Brasquet Catherine , Subrenat Etienne , Le Cloirec Pierre
Published: May 2018

In industrial processes, granular activated carbon (GAC) is generally used to remove pollutants from wastewater. Recently, a new adsorbant has been explored, fibrous activated carbon (FAC). Experiments were carried out with two FACs having different specific surface areas (1500 and 1300 m2.g−1) and pore-size distributions to study adsorption of various organic compounds from aqueous solution. Results were compared with adsorption onto one GAC with a specific surface area of about 1000 m2.g−1. Classic models were applied and kinetic constants were computed. In most cases, FAC with the higher specific surface area (named CS 1501) showed better adsorption capacities and kinetics than the two other FACs. For example, adsorption velocity of benzaldehyde was 7.2 ξ 10−5 1.mg−1·min−1 with CS 1501 and about 3 ξ 10−5 1.mg−1.min−1 with other FACs. Furthermore, adsorption onto CS 1501 of a great number of organic compounds (aliphatic and aromatic) depended on solute molecular characteristics. For instance, solute molecular size seemed to play an important role: adsorption capacity of high molecular weight compounds (humic substances) was about 3 mg.g−1, a value much lower than those of low molecular weight compounds, which were respectively 200 mg.g−1 and 400 mg.g−1 for phenol and benzoic acid. From experimental results, a correlation of QSAR (Quantitative Structure-Activity Relationship) type has been set up. This relationship predicts the adsorbability of organics compounds onto fibrous activated carbon from the molecular properties of these compounds.
Comparison of chemical and thermal regeneration of aromatic compounds on exhausted activated carbon
Authors: Chiang P. C. , Chang E. E. , Wu J. S.
Published: May 2018

In this investigation, nine typical compounds, i.e., phenol, 2-aminophenol, aniline, 2-chlorophenol, chlorobenzene, β-naphthol, naphthalene, α-naphthylamine and α-chloronaphthalene were introduced to evaluate the effects of the molecular structure and physicochemical properties of these selected adsorbates on the adsorption capacity and desorption efficiency of the activated carbon. Both the thermal and chemical regeneration methods were employed to compare the regeneration efficiencies among these adsorbates and adsorbent.
Pilot-plant experiments for improvement of polluted canal/klong water by rock-bed filtration
Authors: Fujii Shigeo , Niwa Chiaki , Mouri Mitsuo , Jindal Ranjna
Published: May 2018

Applicability of the rock-bed filtration technique was investigated through pilot-plant experiments in Bangkok, Thailand. Polluted canal water was used as horizontal flow influent to two reactor channels filled with rocks. During one year operation, HRT, filter media, and aeration mode, were changed in several runs. The results showed that 1) the rock-bed filtration with aeration and the HRT more than 6 h can successfully improve polluted klong water by reducing the pollutants (e.g. 60-120mg/L of SS to 20-40 mg/L and 15-30 mg/L of BOD to 5-20 mg/L); 2) main removal mechanism seems to be the sedimentation resulting from the settleability enhanced by aeration, and the biofilm attached onto rocks also works in the reduction of soluble organic matter; 3) a combination of three rock sizes arranged in descending order showed best results; 4) longer HRT (13 h) produces better effluent but is not so effective if it exceeds 9 hours; 5) 60-70% of sediment IL was decomposed in a year, and porosity in rock beds reduced approximately 16%.
Investigation of nitrification by co-immobilized nitrifying bacteria and zeolite in a batchwise fluidized bed
Authors: Yang Lei
Published: May 2018

A new biotechnology of immobilization of nitrifying bacteria is developed to improve the effect of nitrification, in which a concentrated enriched culture of nitrifiers is entrapped into a special biomass carrier and immobilized by sodium alginate to form spherical pellets with diameters ranged from 1 to 2 mm. In addition, zeolite, which is a natural ion exchanger of ammonium, was co-immobilized into the pellets to enhance the efficiencies of transferring ammonium into the pellets as nitrifiers' substrate. The system was operated under five different initial applied ammonia concentration levels. The experimental results showed that physical air stripping effect was stronger than both chemical ion exchange and biological nitrification effects occurring in the system applied with initial ammonia concentration levels of both 10 and 20 mg N/I. In the experiments applied with initial ammonia concentration levels of 50, 70, and 100 mg N/I to the system, due to high nitrite concentrations detected in the effluents, it was inferred that both ion exchange and nitrification effects were dominant over air stripping effect. The reasons might be due to higher ammonium concentrations existing in the system causing stronger effects of ion exchange by zeolite entrapped inside the pellets. Hence, this new ammonia removal biotechnology appeared to be suitable to treat the wastewaters containing higher ammonia concentrations.
Microbial removal of polycyclic aromatic hydrocarbons by phanerochaete chrysosporium
Authors: Liao Wan-Li , Tseng Dyi-Hwa , Tsai Ying-Chieh , Chang Shenq-Chyi
Published: May 2018

Inoculation of pure microbial culture to biodegrade recalcitrant organic compounds has had increased interest in the field of biological treatment of polluted waters or wastewater effluents. The removal of benzo(a)pyrene by the free cells of Phanerochaete chrysosporium strains, including ATCC 24725, ATCC 32639, and ATCC 34541, in a shaking vessel with a nitrogen-limited incubation medium was observed. This study also investigated the removal efficiencies of naphthalene, fluoranthene, and benzo(a)pyrene by immobilized white-rot fungus in a shaking flask and an aeration batch bioreactor. The biocarrier used in this investigation was a mixed gel composed of alginate and powdered activated carbon (PAC). The results showed that these polycyclic aromatic hydrocarbons (PAHs) were removed with an increased rate during the stationary growth phase, and strain ATCC 24725 exhibited the best PAH removal efficiency. No PAH residuals could be detected by HPLC from the immobilized-cell cultures in the shaking flask or aeration bioreactor during the incubation. However, a likely metabolite of PAH was identified in the chromatogram. The alginate-PAC biocarriers presented availability accessible pore volume for the colonization of fungus mycelia, moreover, the PAC fraction of the biocarrier obviously affected adsorptive capacities of PAHs.
Towards designing sustainable urban wastewater infrastructures: a screening analysis
Authors: Chen J. , Beck M. B.
Published: May 2018

Whether sustainability can, or should, be defined in a practical operational sense, it is clear that the emergence of such a notion has prompted what seems to be a profound re-thinking of whether our society, economic system, and technology are as we would wish them to be. Sustainable development, clean technology, life-cycle analysis, pollution prevention, and so on, are expressions of a willingness to leave no stone unturned, as it were, in the search for what would be appropriate. With respect to the design and operation of a city's wastewater infrastructure, in particular, this search is characterised by a seeming explosion in the possible combinations of appropriate technologies, gross uncertainty about how novel technologies - only now emerging - might perform in the very long term, and a continuing absence of specific criteria of sustainability for determining the grounds on which any candidate technology might be preferred over another. The paper introduces a simple computational procedure for generating and screening candidate combinations of unit-process technologies for an urban wastewater infrastructure. This is based on the use of Monte Carlo simulation, with the identification of those specific technologies (and combinations thereof) that appear to have the greatest probability of being selected for use under different, possibly evolving, criteria of sustainability. Application of the procedure is illustrated with respect to just a part of this infrastructure, i.e., the wastewater treatment plant.
Sustainable water and waste management in urban areas
Authors: Otterpohl Ralf , Grottker Matthias , Lange Jörg
Published: May 2018

Sewerage system and centralised aerobic wastewater treatment plants (WTP) should not be considered as the only possible solution for sanitation. Systems with source control can avoid many problems of the end-of-pipe technology by respecting different qualities of wastewater and by treating them appropriately for reuse.

Different qualities of waste and wastewater in human settlements and appropriate treatment technologies can be: 1. low diluted faeces with/without urine and bio waste (composter or anaerobic digester), 2. grey ·water/aerobic biofilm plant, 3. storm water (usage and infiltration) and 4. non-biodegradable waste (reuse as raw material). In order to perform resource management, the material originating from agriculture should be returned to the soil as fertiliser. Of similar importance is the organic material. This helps maintaining or building up humus and creates a sink for carbon when the C-content in the soil is increased. Energy will be saved, too: energy-intensive aerobic treatment with nitrification is obsolete as well as the production of the respective amount of replaced artificial fertiliser. A pilot project for a new settlement for about 300 inhabitants in Lübeck, Germany, shall demonstrate the feasibility of a new integrated system with vacuum toilets and pipes for the collection of black water. This will be mixed with shredded bio waste and fed to a semicentralised biogas plant that produces liquid fertiliser without dewatering. Grey water will be treated in decentralised biofilm systems. Storm water is collected, retained and infiltrated in a trench system. This way the expensive centralised sewerage system can be avoided for this settlement.
A study of a urine separation system in an ecological village in Northern Sweden
Authors: Hanæus Jörgen , Hellström Daniel , Johansson Erica
Published: May 2018

The development of a sustainable sewerage system includes the utilisation of nutrients from human urine and faeces in agriculture. One strategy for developing a sustainable sewerage system is to handle urine separately and use it as a fertiliser. One important reason for this strategy is the fact that urine is the source of around 70% of phosphorus and around 90% of nitrogen in black wastewater (wastewater from water closets). However, experience from systems with urine separation is limited. In this study a urine separation system in an “ecological” village in northern Sweden has been investigated. The village consists of 17 self-contained houses and the number of inhabitants have varied around 55 persons. The sewerage system is equipped with urine separation toilets. Thus, the urine is intended to be collected separately and led through a sewer system to a collection tank for urine. However, the collected urine was found to be relatively diluted. This could to some extent be explained by errors in the construction of the toilet. However, the main reason for the dilution is probably leakage of water into the urine sewer system. The study also showed that less than about half of the nitrogen and phosphorus from human urine disposed of through the toilets of the village was successfully collected. Thus, the study shows that the successful operation of a urine separation system is very dependent on well-designed toilets and a user behaviour that promotes a high degree of separation.
Towards a more sustainable municipal wastewater treatment system
Authors: Jetten Mike S. M. , Horn Svein J. , van Loosdrecht Mark C. M.
Published: May 2018

The present day wastewater treatment practise can be significantly improved when new microbial processes are introduced. In this paper a new concept is discussed along general lines. The concept consists of a first stage in which a maximal sludge production is achieved. In this way COD is removed as sludge and aeration requirements minimized. This sludge can be digested to yield methane for energy generation. The nitrogen removal is based on a partial oxidation to nitrite and subsequent denitrification with ammonium as electron donor.
Application of computational intelligence for on-line control of a sequencing batch reactor (SBR) at Morrinsville sewage treatment plant
Authors: Cohen A. , Janssen G. , Brewster S. D. , Seeley R. , Boogert A. A. , Graham A. A. , Mardani M. R. , Clarke N. , Kasabov N. K.
Published: May 2018

Morrinsville Sewage Treatment Plant has recently been upgraded to an Extended Aeration SBR. The plant needs to comply with stringent discharge requirements despite the variations in organic and hydraulic load caused by tradewaste discharges and stormwater infiltration. Effluent data from a nearby dairy factory is transmitted to the treatment plant by radio and processed by a back propagation neural network trained to correlate the data with the corresponding BOD. BOD oxidation, nitrification and denitrification rate constants are estimated by fuzzy systems as function of temperature and MLVSS. Output data generated by the model are used to assist control of SBR cycle duration, sludge wasting, and temporary storage of excessive load in a lagoon. The model does not pretend to provide an accurate description of the process, nor a fully optimised control system, but rather a common-sense approach to the very challenging operating conditions. This is a plant receiving a low level of supervision and it is expected that the control system will improve process performance and compliance with discharge requirements.
N2O producing capability of nitrosomonas europaea, nitrobacter winogradskyi and alcaligenes faecalis
Authors: Inamori Yuhei , Wu Xiao-Lei , Mizuochi Motoyuki
Published: May 2018

Nitrosomonas europaea, Nitrobacter winogradskyi and Alcaligenes faecalis—typical ammonia-oxidizer, nitrite-oxidizer and heterotrophic nitrifier were immobilized in PVA gel and employed in the study. Continuous experiments were conducted in their pure and mixed cultures with DO concentrations in the cultures kept at 4, 2, 0.5 mg·l−1. Comparisons among N2O emission from different cultures were made to show their N2O producing capabilities. Results showed that: compared with N. europaea and A. faecalis, N. winogradskyi produced negligible N2O. On the other hand, N. europaea had the highest N2O producing ability. Unit N. europaea produced N2O 18–53 times higher than unit A. faecalis did. However, due to the higher population of A. faecalis, N2O production of the A. faecalis culture was higher than that of the N. europaea culture when DO concentration in the cultures was 2 mg·l−1; whereas, N2O yields of the A. faecalis culture were smaller than those of the N. europaea culture at DO concentrations of 4 and 0.5 mg·l−1. N2O emitted from most the mixed cultures was lower than that from pure cultures under the experimental conditions.
Feasibility of treatment of low polluted waste water in municipal waste water treatment plants
Authors: Dorussen Harry L. , Wassenberg Wilfried B. A.
Published: May 2018

In many cases municipal waste water treatment plants receive considerable amounts of low polluted waste water like pretreated industrial waste water, polluted ground water etc. It is not known to what extent treatment of this type of waste water in a municipal waste water treatment plant is feasible with regard to environmental effects and costs. In this paper the effects of this type of waste water on the removal efficiencies of nitrogen, heavy metals and organic micropollutants have been described and costs have been given to prevent an increase of emission loads. For an estimation of the effects on the emission loads simulation models have been used. For an existing oxidation system with a relatively high amount of low polluted waste water simulation runs have been made for situations with and without low polluted waste water. On basis of the results of this case study a system has been developed for the assessment of the feasibility of treatment of low polluted waste water in a municipal waste water treatment plant.
Verification of anoxic phosphate uptake as the main biochemical mechanism of the “dephanox” process
Authors: Sorm R. , Wanner J. , Saltarelli R. , Bortone G. , Tilche A.
Published: May 2018

The phenomenon of anoxic phosphate uptake with simultaneous denitrification was studied. For this purpose kinetic batch tests have been carried out by using the activated sludge samples from three modifications of nutrient removal activated sludge systems: two based on an anaerobic-anoxic-oxic (A2/O) system and a third on an anaerobic-oxic (A/O) system.

The results showed significant differences in anoxic phosphate uptake rate between activated sludge which was alternatively exposed to anoxic conditions and activated sludge from the A/O arrangement. These differences were also accompanied by different denitrification rates. Simultaneously with batch experiments the microscopic observation of activated sludge samples was carried out. Neisser and Gram stained samples showed clear differences in shape, size and distribution of polyphosphate accumulating bacteria between A2/O and A/O Processes. Moreover, experiments performed using genetic probes confirmed the differences in microbiological composition of activated sludge samples from different nutrient removal system arrangements.
Anaerobic treatment of inuline effluent in an internal circulation reactor
Authors: Habets L. H. A. , Engelaar A. J. H. H. , Groeneveld N.
Published: May 2018

Sensus Operations C.V. is a 100 percent subsidiary of the Dutch Suiker Unie group (Cosun). At the site in Roosendaal it operates an inuline and fructose production line, using chicory beet as raw material. Inuline is a product which is gaining more and more popularity as a structural improver in food, as a low calory replacement in ice-cream and chocolate bars and as moisturizer to improve the spreadability of cleaning products. It consists of a polyfructose fibre which is hardly degraded in the human body.

The cleaning and chipping process of the chicory beet is similar to the sugar beet preparation process and so is the effluent. The production process itself is different and the effluent released, also contains the effluent from a demineralisation plant, which results in an additional high COD and salt loaded effluent. During the first two years of inuline production the “heavy water” (high COD, salty effluent) was simply added to one of the existing UASB reactors, because the inuline factory was running at a very low capacity. However since 1995 the production could be increased drastically to 1500 tpd so that an extra anaerobic treatment unit had to be installed. The third would require enough capacity to convert 30 tons of COD per day (COD load 37.5-40 tpd). However, the investment was quite high and the reactor volume would be of such a size that it would be more difficult to operate, considering the sludge weight and the important ground surface. At the moment the size of the reactor was known, the idea was born to consider the installation of an Internal Circulation (IC) reactor. This reactor was 25% lower in investment cost and space occupation was only 55 m2 instead of 450 m2. This paper reveals the performance of the IC reactor during the first campaign in 1995.
Evaluation and role of rheological properties in sludge management
Authors: Dentel Steven K.
Published: May 2018

Rheological characterization of sludges represents one of the few examples of fundamentally derivable properties that has also been successfully related to actual sludge treatment processes. In understanding the relevance and utility of sludge rheology for practical applications, an historical perspective is of some initial value, and this paper summarizes previous developments in the rheological characterization of sludges and other non-Newtonian slurries, both from a theoretical and empirical perspective. In both cases, attention is brought to subtleties that must be considered if uniform and consistent rheological descriptions are to be obtained. Causes of the complex and variable rheological properties observed in sludges are then considered, with attention brought to particular aspects of upstream processes where some influence on sludge viscosity might be exerted. Finally, some practical aspects of rheometry are described. Recent research suggests that a variety of methods for sludge characterization and process optimization can be based on rheological measurements. Examples are presented that utilize both complex and relatively simplified technologies for this purpose, and some predictions are attempted of the probable directions for future developments. Internationally, approaches have differed and, while this diverse and competitive environment favors technological advances, the paper concludes by pointing out the need for consistency in rheological methods where fundamentally based parameters or regulatory concerns may be involved.
The rheological characterisation of sludges
Authors: Slatter P. T.
Published: May 2018

The rheological characterisation of sludges can be broken down into three steps: viscometry, rheological modelling and correlation of parameters. Viscometry can be performed in either rotational or tube instruments, but the tube instrument is preferred. Data analysis techniques are described and problem areas highlighted. Rheological modelling of sludges has been done traditionally using the pseudoplastic or Bingham plastic models. It is shown that the use of the yield pseudoplastic model provides a more accurate basis for further analysis and a pumped pipeline example is presented as illustration. The correlation of rheological parameters against concentration using a priori methods is discussed and illustrated using a sludge example.
The use of ultrasound to accelerate the anaerobic digestion of sewage sludge
Authors: Tiehm A. , Nickel K. , Neis U.
Published: May 2018

The slow degradation rate of sewage sludge in anaerobic digesters is due to the rate limiting step of sludge hydrolysis. The effect of ultrasound pretreatment on sludge degradability was investigated using ultrasound at a frequency of 31 kHz and high acoustic intensities. Ultrasound treatment resulted in raw sludge disintegration as was demonstrated by increase of Chemical Oxygen Demand in the sludge supernatant and size reduction of sludge solids. Semi-continuous fermentation experiments with disintegrated and untreated sludge were done for four months on a half-technical scale. One fermenter was operated as a control with a conventional residence time of 22 days. Four fermenters were operated with disintegrated sludge and residence times of 22, 16, 12, and 8 days, respectively. In the fermenters operated with identical residence times of 22 days reduction of volatile solids was 45.8% for untreated sludge and 50.3% for disintegrated sludge. The fermentation of disintegrated sludge was stable even at the shortest residence time of 8 days with biogas production 2.2 times that of the control fermenter. Due to ultrasound disintegration a better degradability of raw sludge was achieved that permitted a substantial increase in throughput.
Anaerobic digestion and dewatering characteristics of mechanically disintegrated excess sludge
Authors: Kopp Julia , Müller Johannes , Dichtl Norbert , Schwedes Jörg
Published: May 2018

Mechanical cell disintegration and its influence on anaerobic digestion was investigated using four different methods. Methods to describe the degree of cell-disruption were developed and the release of organic components into the sludge water was measured. The best results were optained using a stirred ball mill and a high-pressure homogenizer. The influence of disintegration rate and digestion time on the performance of the anaerobic process and the dewatering characteristics were investigated. The degradation is accelerated and the digestion time can be reduced, especially when using immobilised microorganisms. It could be shown that the mechanical disintegration results in a disruption of particle structure and an increase of polymer-demand. As a result of better anaerobic degradation the density and dewatering results of disintegrated sludges are improved in comparison to non-treated sludges.
Full scale application of manufacturing bricks from sewage
Authors: Okuno Nagaharu , Takahashi Shiro
Published: May 2018

Brick making from 100 percent of incinerated sewage sludge ash is developed. There are already 8 full scale plants in Japan. All of them employ high pressure molding of incinerated sewage sludge ash and firing at about 1000°C. The end products are widely accepted for public works such as flooring of plazas or pedestrian walk ways. Early in the history of the development, overall quality of the sewage brick was not competitive. They were subject to get moss growth on the surface because of its high moisture content, or whitening because of leaching of Calcium Carbonate. The problems were solved by increasing the temperature of the firing process and by chemical coating. The manufacturing cost of one sewage brick is around two dollars and the retail price is one dollar.
Effects of heavy metals on nitrifying bacteria
Authors: Lee Yong-Woo , Ong Say-Kee , Sato Chikashi
Published: May 2018

Laboratory evaluations were conducted to study the toxic responses of heavy metals such as copper and nickel of an autotrophic culture of strict nitrifiers (Nitrosomonas sp. and Nitrobacter sp.) in continuous flow stirred tank reactors (CSTR). One of the CSTRs was operated as a suspended growth (SG) system while the other was operated as an attached & suspended growth (A&SG) system. Nitrification inhibition in a SG and A&SG systems was investigated with the emphasis on the effect of shock loading of copper and nickel. As a result of the copper and nickel test, Nitrosomonas sp. was found to be equally or more sensitive than Nitrobacter sp. However, a higher influent nickel concentration of 50 mg/L was needed to cause a similar percent inhibition of ammonium oxidation than the copper concentration of 5 mg/L. A geochemical equilibrium speciation model, MINTEQA2/PRODEFA2, was used to compute the concentrations of various chemical species present in the wastewater for both systems. The high correlations of Cu(NH3)4+2 and Ni(NH3)4+2 with percent inhibition were found and it was thought that they were probably the species responsible for the inhibition of ammonia oxidation.
Biofilm formation: the effects of hydrodynamic and substrate feeding patterns in three phase draft-tube fluidized bed for nitrification process
Authors: Cheng Sheng-Shung , Chen Wen-Chin , Hwang Hui-Hsiang
Published: May 2018

Various influences of hydrodynamic parameters and substrate feeding patterns on the biofilm formation in the three-phase fluidized bed bioreactor for the nitrification process were investigated in this study. The results clearly indicated that the biofilm formation was significantly affected by the mean liquid velocity. While the mean liquid velocity increased from 444 to 563 m/h, the biomass attached on to the GAC obviously decreased from 30.4 to 15.6 mgVSS/gGAC due to hydraulic sloughing off. Higher velocity was shown to exert a profound influence on the amount of attached biomass. It was caused by the abrupt intensification of shear stress and frictional forces both acting on the bioparticle surfaces. On the other hand, the nitrifying bacteria were induced to secrete more exopolymers covering the bacterial colony onto the GAC at a higher liquid velocity. It would be useful for accumulation of the low growth-rate nitrifiers to attach better on the biofilm carrier in the bioreactor. Consequently, the suspended biomass was attached onto the GAC again and grown up on the GAC surface after 30 days of operation while the primary biofilm was formed. With long-term operation and microbial acclimation, a high efficiency of ammonium removal was achieved and independent of the volumetric loadings of ammonium in the range of 1.5∼3.8 kgNH4+-N/m3/day. It clearly indicates the potential of the three-phase fluidized bed to treat wastewater with a high volumetric loading of ammonium.
Treatment of photographic processing wastewater using anaerobic-aerobic biofilm reactor
Authors: Hirata Akira , Lee Haeng-Seog , Tsuneda Satoshi , Takai Tomotake
Published: May 2018

Two types of anaerobic-aerobic biofilm processes were applied to the treatment of the photographic processing wastewater. Two-phase fixed bed reactor packed with sponge cubic media and completely mixing three-phase fluidized bed reactor, respectively, were used as an anaerobic and aerobic biofilm reactors. One of the aerobic biofilm reactors was packed with cement balls (CB) made by crushed cement particles, and another packed with biological activated carbon (BAC). The fivefold diluted photographic processing wastewater, from which Ag had been removed previously, was used as an influent (BOD 5,700 g/m3, CODcr 17,000 g/m3, T-N 2,600 g/m3). During long-term continuous biological treatment, BOD values in effluent decreased gradually and reached 280 g/m3, which could fulfill the sewage discharge control value in Japan (BOD < 600 g/m3). It took more than one year to acclimatize the sludge and to get the effective microorganisms for degrading the compounds in the photographic processing wastewater. However, pH values in the aerobic biofilm reactors fell down to 3∼4. This was possibly because thiosulfate (5,700 g/m3) in the photographic processing wastewater was almost oxidized to sulfate by sulfur-oxidizing bacteria. For the purpose of obtaining higher BOD removal efficiency, pH in the aerobic biofilm reactor was adjusted to 7 using pH controller. As a result, BOD removal ratio was gradually improved, and the sewage discharge control value was steadily achieved after 181 days. The number of bacteria in the anaerobic biofilm reactor and the aerobic biofilm reactor with pH controller were 6.0×109 N/mL and 1.1×108 N/mL, respectively.
A mechanical pretreatment of waste activated sludge for improvement of anaerobic digestion system
Authors: Hwang Kyung-Yub , Shin Eung-Bai , Choi Hong-Bok
Published: May 2018

This study evaluated the effectiveness of sewage pretreatment as it affected the subsequent anaerobic digestion of waste activated sludge (WAS). The key to this sludge pretreatment process was that microorganism cells within WAS were ruptured by mechanical jet and smash under pressurized conditions, 5–50 bar pressure. Cell rupture was estimated by soluble protein concentration (SPC) because the cytoplasm of microorganisms is mainly composed of protein. The SPC in the WAS varied significantly before and after pretreatment. In particular, cell rupture increased from 6% to 43% with the increase of the pretreated pressure (5–30bar), volatile solids concentration and thickening time of WAS. In the WAS pretreatment with long-thickening time (12h < thickening time ≤ 48h), cell rupture was monitored 5–10 % higher than short-thickening time (Oh <thickening time ≤ 12h). Generally, it was observed that higher anaerobic digestion efficiencies of WAS could be obtained according to the increase of microorganism cell rupture through mechanical pretreatment of WAS.
Comparison of lime and alum as oily sludge conditioners
Authors: Hwa Tay Joo , Jeyaseelan S.
Published: May 2018

Chemical conditioning improves sludge dewatering. Choice of chemical conditioners is very much dependent on the characteristics of the sludges and the type of dewatering devices. Lime, alum, ferric chloride and polyelectrolytes are commonly used chemical conditioners. Anaerobic digested sludge samples collected from a sewage treatment plant with different oil contents varying from 1.8% to 8.0% by weight have been examined in the laboratory to find out their specific resistance, capillary suction time and filter yield. Lime and alum were used separately as conditioners. Different dosages of conditioner varying from 2% to 12% by weight were used to determine the optimum chemical dosage for varying oil contents. Lime dosages of about 6% were found to yield favourable characteristics. Addition of alum decreases the specific resistances and capillary suction times of oily sludges rapidly up to 4% dosages. Alum dosages beyond 4% only increase the solids content in the sludge cake and increase the sludge volume to be handled. A correlation between CST and specific resistance to filtration was established. CST can be measured easily and quickly in the laboratories. Using the CST and the correlation a quick prediction on dewaterability can be established.
Fuzzy expert system to determine stream water quality classification from ecological information
Authors: Lee H. K. , Oh K. D. , Park D. H. , Jung J. H. , Yoon S. J.
Published: May 2018

Water quality classification for stream has been major tool for water quality management in Korea. This paper examines the application of the fuzzy inference mechanism to develop a fuzzy expert system for proper determination of WQCS from uncertain and imprecise ecological information. This study proposes a rule matrix composed of seven water quality grades, toxicity of water and rarity of cases. From this rule matrix, 30 rules for WQCS determination are generated. From the comparison of performance of the fuzzy expert system and the conventional expert system for the determination of class, toxicity, and rarity, it seems that the smoothly varying curves of WQCS determination from the fuzzy expert system represent our real-world experience more realistically than stepwise curves from the conventional expert system.
Characteristics of competitive adsorption of aquatic humic substances onto activated carbon
Authors: Yuasa Akira , Fusheng Li , Matsui Yoshihiko , Ebie Kunio
Published: May 2018

The competitive adsorption of aqueous humic substance onto activated carbon was characterized. A technique to determine its composition in terms of both the molecular weight and the adsorbability was developed. This technique required the equilibria of molecular weight fractions in the mixture and that of the hypothetical components which could account for the competitive adsorption of the total organics. The former was obtained by measuring the molecular weight distributions of the humic substance remaining in solution over various carbon dosages with size exclusion HPLC. The latter was achieved by using a method developed on the basis of ideal adsorbed solution theory (IAST) to describe the overall adsorption isotherms for background organics of known composition. Using this technique, the adsorption equilibria of all the molecular weight fractions in the mixture were quantitatively described, and the existence of a correlation between the molecular weight and the adsorptive strength was confirmed. This technique was shown to be also effective in clarifying the composition of the remaining humic substance over different carbon dosages.