bluuebunny/crossref_metadata_2025 huggingface dataset:
Model calibration of deep-bed filtration based on pilot-scale treatment of secondary effluent
Authors: Shandalov Semion , Yakirevich Alexander , Brenner Asher , Oron Gideon , Rebhun Menahem
Published: May 2018

A mathematical model of deep-bed filtration has been calibrated and verified based on experimental results. The experimental system, used for testing of the secondary treatment quality and the tertiary filtration phase, incorporates an SBR system followed by a filtration column. The turbidity of the incoming SBR effluent was in the range of 12 to 34 NTU. The bed grain size was in the range of 1.4 to 2.0 mm. The examined filtration velocities were 11, 15, 20 and 25 m/h. The filtration process is simulated by equations of balance and kinetics. The latter includes the attachment and detachment process, characterized by rate coefficients KA and KD, respectively. These coefficients , as well as the parameters of hydrodispersivity and effective porosity, are found on the basis of nonlinear optimization, using numerical solution of the model and the experimental breakthrough curves. The method demonstrates good agreement between experimental and simulated results.
Landfill leachate treatment by a photoassisted fenton reaction
Authors: Kim Soo-M. , Geissen Sven-U. , Vogelpohl Alfons
Published: May 2018

A combination of the classical Fenton reaction (Fe(II)+H2O2) with UV light, the photoassisted Fenton reaction, has been investigated for the treatment of landfill leachate. The investigation has been carried out with an experimental set-up to establish the optimal treatment conditions. The degradation rate of organic pollutants is strongly promoted by the photoassisted Fenton reaction. The degradation rate depends on the amount of H2O2 and Fe(II) added, pH value, and radiation intensity. At a specific energy input of 80 kW m−3 the oxidation rate was increased to six times the rate without radiation (0 kW m−3). At the higher radiation intensity of 160 kW m−3 the degradation rate was about two times faster than at that of 80 kW m−3. Due to the regeneration of the consumed Fe(II) ions through the irradiation, the amount of ferrous salt to be added can be remarkably reduced. The optimum conditions were obtained with 1.0 × 10−3 mol 1−1 Fe(II) added, a pH value of 3, and a molar ratio of COD: H2O2 = 1:1. At a COD volume loading of less than 0.6 kg m−3 h−1, a COD degradation of more than 70% could be obtained with an energy input of 80 kW m−3.
Ozonation of azo dyes
Authors: Liakou S. , Pavlou S. , Lyberatos G.
Published: May 2018

Ozone pretreatment studies of wastewater containing a specific azo dye – Orange II - were conducted in order to assess the kinetics of ozone oxidation and to evaluate the effect of ozonation on the biodegradability of the wastewater. Batch experiments were performed at different initial concentrations of the dye, showing that ozone is capable of a rapid disruption of the dye molecule. Moreover, the production of biodegradable compounds is apparent from the evolution of COD and BOD5 measurements. A mathematical model which describes the dye elimination, the COD and BOD5 variation, and the amount of ozone reacted has been developed.
Electrochemical versus photochemical pretreatment of industrial wastewaters
Authors: Ribordy P. , Pulgarin C. , Kiwi J. , Péringer P.
Published: May 2018

Electrochemical and photochemical treatments have been applied on industrial non-biodegradable effluents originated from a flavour manufacturing facility. The efficiency has been measured in each case. Such an approach has been used before successfully on model substances and is confirmed in the present study as a valid approach for industrial waste water.

During electrochemical treatment, the values for the temperature, pH, electrode characteristics, initial concentration of effluents and NaCl used have been optimized through preliminary experiments. After a charge of 5 Ah/l the TOC observed decreased by 52% and the ratio TOC/COD decreased from 3.3 to 1.7. After electrochemical treatment and chlorine neutralization the effluents become easily biodegradable and no toxicity was observed.

Photo-Fenton system under solar lamp have shown to be efficient in the photochemical degradation of industrial effluent when Fe3+-ion (4.3 mg in 40ml) and H2O2 (30μl/h in 40 ml) is added to the solution. After 10 hours a degradation of 56% of TOC was observed. The toxicity and biodegradability of pretreated wastewater were evaluated after having decomposed the residual H2O2 with catalase. Toxicity did not increase during photochemical treatment but the biodegradability strongly increased.
Change of particle structure of sewage sludges during mechanical and biological processes with regard to the dewatering result
Authors: Nellenschulte Thomas , Kayser Rolf
Published: May 2018

Particle size seems to be the most important parameter, to describe the dewatering behaviour and result of sludges. But there are many other parameters, which can influence the dewatering result. The dewatering result of a sludge depends on the type of sludge, the mechanical and biological process. Out of the numerous parameters to characterize wastewater sludges five were selected, which describe the properties of the particulate matter. These parameters are the suspended solids (SS), the volatile suspended solids (VSS), the density of the particles (ρ), the fraction of small particles (fines) and a new parameter, called φ-value, which is the ratio of the mass of waste activated sludge to the total mass of sludge. The tested sludges were analysed for the Zeta Potential, but there could not be found a correlation between this parameter and the dewatering result.

Combining the parameters in a model led to an overall sludge parameter, the so-called “Integral Property Parameter, fE”. A correlation between the fE-values and the dewatering results of municipal sludges (n = 49) can be found. A proposal was made to transfer the experimental results to a full scale dewatering process with high performance centrifuges.
The use of oxidation and other processes for the treatment of liquid organic waste at BNFL, Sellafield, UK
Authors: Hutson G. V.
Published: May 2018

British Nuclear Fuels plc has since its inception 1971 had a policy of reducing its discharges of radioisotopes and other possible hazardous substances to as low as reasonably possible. In support of this, a substantial research & development programme was initiated in the mid nineteen eighties to establish suitable processes for treating both free phase and soluble liquid organic wastes.

This paper describes major processes studied and the selection criteria applied, which has resulted in the choice of alkaline hydrolysis for the free phase waste organics and both catalytic chemical oxidation and electrically enhanced photooxidation for soluble organics.
Biogeochemical indicators to evaluate pollutant removal efficiency in constructed wetlands
Authors: Reddy K. R. , D'Angelo E. M.
Published: May 2018

Wetlands support several aerobic and anaerobic biogeochemical processes that regulate removal/retention of pollutants, which has encouraged the intentional use of wetlands for pollutant abatement. The purpose of this paper is to present a brief review of key processes regulating pollutant removal and identify potential indicators that can be measured to evaluate treatment efficiency. Carbon and toxic organic compound removal efficiency can be determined by measuring soil or water oxygen demand, microbial biomass, soil Eh and pH. Similarly, nitrate removal can be predicted by dissolved organic C and microbial biomass. Phosphorus retention can be described by the availability of reactive Fe and Al in acid soils and Ca and Mg in alkaline soils. Relationships between soil processes and indicators are useful tools to transfer mechanistic information between diverse types of wetland treatment systems.
Wildlife habitat and public use benefits of treatment wetlands
Authors: Knight Robert L.
Published: May 2018

Constructed and natural wetlands are being utilized for water quality management of a broad variety of wastewater types worldwide. While water treatment is a primary goal of many of these systems, there is a general recognition that ancillary benefits for public use and wildlife habitat are typical of some of these wetlands. Also, there are growing numbers of constructed wetlands that are primarily focused on providing habitat and/or public use while relying on pretreated wastewater as the principal water supply. Efforts are currently underway to document the normal ranges of human and wildlife use benefits of treatment wetlands, and to provide a reasoned assessment of the potential environmental risks associated with these systems. Information collected from existing surface-flow treatment wetlands indicates consistent net benefits for wildlife habitat and public use. An understanding of the relationship between design and operation of treatment wetlands, and their positive and negative ecological and societal responses, will allow for optimization of new wetland systems.
Identification of model structure for photosynthesis and respiration of algal populations
Authors: Stigter J. D. , Beck M. B. , Gilbert R. J.
Published: May 2018

The paper introduces a methodology for model evaluation based upon (i) a controlled random search algorithm used for calibration and (ii) a recursive prediction error algorithm used as a verification tool. The method is applied to a case study in north west Georgia involving the dynamic simulation of a population of algae in a standing body of water. Efforts to identify a model structure for the dissolved oxygen dynamics associated with photosynthesis and respiration are made, with some success.
Identification of the parameters describing primary production from continuous oxygen signals
Authors: Aalderink R. H. , Jovin J.
Published: May 2018

The parameters of a simple dissolved oxygen (DO) model have been estimated on a day to day basis from continuous oxygen measurements. Oxygen was measured in a shallow ditch (0.38 m) dominated by bentic algae. The main objective was to study the identifiability of the parameters Pmax and Iopt in the photosynthesis vs. irradiance (P/I) curve, in order to determine the seasonal variations of the parameters and to study relationships with environmental conditions. For this purpose joint parameter confidence regions, parameter correlation, and the eigenvalues of the Fisher information matrix have been determined. The results show that Pmax can be estimated fairly well, whereas for Iopt the confidence regions are much larger. In particular for days in winter and spring extremely long elongated confidence regions can be found. However, it can be concluded that for a sufficient number of days, both parameters in the P/I curve can be estimated sufficiently accurately to study seasonable variability and dependency with temperature and light conditions.
Phosphorus sorption and chemical characteristics of lightweight aggregates (LWA)-potential filter media in treatment wetlands
Authors: Zhu T. , Jenssen P. D. , Mæhlum T. , Krogstad T.
Published: May 2018

Five light-weight aggregates (LWAs), suitable for filter media in subsurface flow constructed wetlands, were tested for potential removal of phosphorus (P). P-sorption variation is dependent on the chemical characteristics of the LWA. All LWAs exhibited high pH and high total metal content; however, P-sorption capacity varied by two orders of magnitude. Of the LWAs' chemical characteristics (total metal content, cation exchange capacity, and oxalate soluble Fe and Al), total metal content has the closest relationship with the P-sorption capacity. Among the four major metal ions (Mg, Ca, Fe and Al), Ca has the strongest correlation with the P-sorption capacity.
Relevance of the H2U model to predict the discharge of a catchment
Authors: Duchesne J. , Cudennec C. , Corbierre V.
Published: May 2018

The new deterministic model H2U (from French “Hydrogramme unitaire universel”) is validated for two Mediterranean catchments, both in natural conditions, in the south of France and in the very anthropic catchment of Paris-Orly airport. It starts from a description of the drainage network by means of a density function of the hydraulic lengths. Through the mean water speed in the channels, this function is proved to be the unit hydrograph, or transfer function of the catchment. Moreover, in some cases, the production function can be directly known, for instance when the rain intensity is very high, or, if rain intensities are rather low, when the impervious surface area ratio is known and can be considered as the effective rainfall/total rainfall ratio. Then, the H2U model can give directly a good simulated curve of discharge, without any calibration except for the estimation of the mean water speed. The model can probably give good simulations in any situation provided that the production function has been evaluated. Even better, it can be used as the known kernel function in order to obtain the effective rainfall, i.e. the production function, by deconvolution of the actual hydrograph.
Advantages and limitations of duckweed-based wastewater treatment systems
Authors: Bonomo L. , Pastorelli G. , Zambon N.
Published: May 2018

In order to find a reliable, simple and cost-effective small wastewater treatment system, an experimental research programme on duckweed-based treatment systems was carried out. In spite of the profitable characteristics of duckweed (high productivity, high protein content, wide geographic distribution, control of negative impacts from conventional wastewater treatment ponds), the results obtained confirm that their extensive use in Italy seems difficult because of the high requirement of land area and the ceasing of growth in winter months (at least in Northern Italy). In temperate climates, a reasonable use of duckweed looks to be the production of good quality secondary effluents (BOD and SS removal) from small communities, especially in seasonal (summer) wastewater treatment plants. Another use is algae removal from facultative lagoon effluents. Nitrogen removal can only be reasonably obtained in duckweed-covered ponds with supplemental aeration. Because of several constraints due to the markets and to environmental regulations, harvested duckweed has to be disposed of as sewage sludge (e.g. compost or biogas production).
Improvements to a stoat model of a full scale wastewater treatment works through the use of detailed mechanistic studies
Authors: Stokes A. J. , West J. R. , Forster C. F. , Kruger R. C. A. , de Bel M. , Davies W. J.
Published: May 2018

The performance of a wastewater treatment works has been simulated using a dynamic modelling package from WRc, STOAT. The estimation of appropriate parameter values has been performed both prior to and after detailed investigations of the mechanisms of oxygen transfer and mixing within the aeration lanes of the activated sludge plant. Interpretation of reactor mixing characteristics in the light of dissolved oxygen data is considered. The need for accurate information concerning solids retention times is exemplified by the model's sensitivity to sludge wastage rates.
Reed beds for biosolids drying in the arid northwestern United States
Authors: Burgoon Peter S. , Kirkbride K. Frank , Henderson Mike , Landon Evan
Published: May 2018

Reed beds for dewatering biosolids have been successful throughout Europe and in the northeastern temperate United States. This paper reports on the use of reed beds in the arid Columbia Basin in the state of Washington, USA. Native stands of the common reed, Phragmites australis were propagated and planted in the reed beds. The hot, dry, windy, climate has required simple changes in standard operation of the reed beds. The reeds were stressed by the hot dry winds and lost top shoot growth when beds remained drained in the Spring Summer and Fall months. Maintenance of water levels in the cells has reduced symptoms of heat stress in the plants. These operational changes may have an effect on oxidation of organic matter and nitrogen in the filtrate. The operational changes may have effected the dewatering and decomposition of the biosolids. The dry hot summers, and freezing winters enhance the dewatering ability of the reed beds and make them an appropriate solids dewatering technology for the region.
Real time control of a combined sewer network using graph theory
Authors: Vazquez J. , Bellefleur D. , Gilbert D. , Grandjean B.
Published: May 2018

In order to reduce overflow pollution load during rainfall, a real time control strategy has been implemented for the combined sewer network of Saverne (Alsace, France). It consists of optimizing various gate and pump commands over a specified prediction horizon, using graph theory. Flows, trough collectors, weirs and stormwater retention tanks have been represented by a graph and a primal-dual algorithm has been used in order to satisfy rainfall discharge with lower overflow. This strategy has been tested successfully using 685 rainfall events collected over a decade and attractive reductions of both volume and frequency overflows have been observed.
Simultaneous nitrification-denitrification process in extended aeration plants: pilot and real scale experiences
Authors: Bertanza G.
Published: May 2018

This work deals with the study of technologies aimed to upgrade the existing waste water treatment plants, paying attention to high process efficiencies and low costs. We verified the possibility to reach high N removal efficiencies in extended aeration activated sludge plants which are not equipped with specific denitrification steps. The experimented process is based on particular conditions, kept in the biological reactor, which allow simultaneous nitrification and denitrification, even without alternating (in time or in space) of anoxic and aerobic phases: aeration system is controlled by means of dissolved oxygen and redox potential measurements. Our research was carried out, for about three years, on a laboratory plant (V = 40 L) fed with synthetic waste water, a pilot scale plant (V = 1,400 L) fed with waste water coming from a real plant, and two full-scale plants (1,500-2,000 p.e.). The main advantages of the studied process are the following: high total N removal efficiencies (up to 90%) without the realization of new specific basins for the denitrification process; decreasing of operating costs (savings in Electric Energy consumption) due to the low oxygen concentration required in the biological reactor.
Performance of hybrid small wastewater treatment system consisting of jet mixed separator and rotating biological contactor
Authors: Watanabe Yoshimasa , Iwasaki Yoshihiko
Published: May 2018

This paper describes a pilot plant study on the performance of a hybrid small municipal wastewater treatment system consisting of a jet mixed separator(JMS) and upgraded RBC. The JMS was used as a pre-treatment of the RBC instead of the primary clarifier. The treatment capacity of the system was fixed at 100 m3/d, corresponding to the hydraulic loading to the RBC of 117 L/m2/d. The effluent from the grid chamber at a municipal wastewater treatment plant was fed into the hybrid system. The RBC was operated using the electric power produced by a solar electric generation panel with a surface area of 8 m2 under enough sunlight. In order to reduce the organic loading to the RBC, polyaluminium chloride(PAC) was added to the JMS influent to remove the colloidal and suspended organic particles. At the operational condition where the A1 dosage and hydraulic retention time of the JMS were fixed at 5 g/m3 and 45 min., respectively, the average effluent water quality of hybrid system was as follows: TOC=8 g/m3, Total BOD=8 g/m3, SS=8 g/m3, Turbidity=6 TU, NH4-N=7 g/m3, T-P=0.5 g/m3. In this operating condition, electric power consumption of the RBC for treating unit volume of wastewater is only 0.07 KWH/m3.
An evaluation of performance and process stability of different processes for small wastewater treatment plants
Authors: Ødegaard H. , Skrøvseth A. F.
Published: May 2018

An investigation on the treatment results and process stability of 356 Norwegian wastewater treatment plants of different process categories has been carried out. It is demonstrated that chemical plants have better process stability than biological plants and that biological/chemical plants have the best process stability.
Study of the physical and chemical characteristics of a range of chemically treated, lignite based carbons
Authors: Duggan Orna , Allen Stephen J.
Published: May 2018

It is already known that activated carbons may be developed by chemically treating the adsorbent precursor to produce a carbon which displays improved adsorption characteristics and possibly preferential adsorption of one particular molecule over another. For the purposes of this study, a selection of carbons produced by the chemical treatment of N.I. lignite were studied. A range of transition metal compounds were used for the study as oxo-complexes of these metals have previously been associated with micropore widening in activated charcoal cloth. The adsorption of different concentrations of aqueous solutions of phenol, basic red dye and copper ions onto each carbon was examined. The adsorption equilibrium isotherms obtained for the carbons were plotted to obtain the Freundlich and Langmuir constants for each system. The adsorption capacity of each carbon was found to depend on its method of activation. In order to make a connection between the adsorptive behaviour of each carbon and its method of treatment, the physical and chemical morphology of the carbon was studied. Gas sorption on the Fisons instruments Sorptomatic 1900 and mercury porosimetry on the Fisons instruments Porosimeter 2000 were the methods used to study the micro-, meso- and macropore volumes, surface areas and pore radius distributions of the carbon samples. Infra-red spectroscopy showed that only minor changes occurred in the surface functional groups between the untreated lignite and the carbons and also between carbons themselves. Finally data obtained for these carbons was compared with the results of a previous study of untreated Northern Ireland lignite and lignite chars.
Adsorption and ion exchange of some groundwater anion contaminants in an amine modified coconut coir
Authors: Baes Aloysius U. , Okuda Tetsuji , Nishijima Wataru , Shoto Eiji , Okada Mitsumasa
Published: May 2018

The adsorption of nitrate, chromium (VI), arsenic (V) and selenium (VI) anions in an amine modified coconut coir (MCC-AE : with secondary and tertiary amine functionality) were studied to determine the capability of this easily prepared and low-cost material in removing typical groundwater anion contaminants.

Batch adsorption-ion exchange experiments were conducted using 200 mg MCC-AE, initially containing chloride as the resident anion, and 50 ml of different anion-containing water of varying concentrations. It is presumed, at this low pH, that only SeO42− remained as a divalent anion, while monovalent species H2AsO4− and HCrO4− predominated in their respective exchanging ion solutions. The adsorption data were fitted using the Freundlich equation and maximum adsorption for each anion was estimated using their respective Freundlich equation constants. MCC-AE exhibited preference for divalent Cr (VI) and Se (VI) anions compared with the Cl− resident ion. Maximum As (V) adsorption was 0.086 mmol/g, while maximum adsorption of Cr (VI), NO3− and Se (VI) anions was 0.327 mmol/g, 0.459 mmol/g, and 0.222 mmol/g, respectively. The ion exchange capacity of MCC-AE is estimated, based on its exchange capacity for nitrate, to be within 0.46 mmol of positive charges per gram. Similar adsorption experiments were conducted for comparison using commercial chloride-form Amberlite IRA-900 strong base (quaternary amine functionality) anion exchanger, with an exchange capacity of 4.2 meq/g. Maximum adsorption of the different ions in IRA-900 was about 3 times higher for NO3−, 9 times higher for Se (VI), 10 times higher for As (V) and 9 times higher for Cr (VI), than that in MCC-AE. Differences in the ion exchange behavior of MCC-AE and IRA-900 were probably due to the different amine functionalities in the two exchangers. The results suggest that MCC-AE may be used as a low-cost alternative adsorbent/ion exchanger for treatment of anion contaminants in groundwater.
Competitive removal of dissolved organic carbon by adsorption and biodegradation on biological activated carbon
Authors: Kim Woo Hang , Nishijima Wataru , Shoto Eiji , Okada Mitsumasa
Published: May 2018

Improvement of biodegradability of dissolved organic carbon (DOC) by ozonation does not always induce improvement of DOC removal and extension of activated carbon service time, because most of biodegradable DOC increased by ozonation is adsorbable on activated carbon. The objective of this study is to clarify the fate of the biodegradable DOC increased by preozonation on biological activated carbon (BAC) and to evaluate effects of preozonation on BAC performance for the removal of DOC and extension of activated carbon service time. DOC breakthrough curve for BAC process obviously shifted to the right by combination with ozonation, indicating that preozonation extended BAC service time. Higher removal of DOC was noted in the ozone-BAC process than the BAC process after saturation with DOC. Ozonation increased biodegradable DOC by 2.89 mg·l−1 (31%). Although the increased biodegradable DOC had possibilities to be removed both by adsorption and biodegradation, most of it was removed by biodegradation on BAC which resulted in longer BAC service time. Biodegradation of the increased biodegradable DOC was responsible for the higher removal of DOC after saturation with DOC in the ozone-BAC process.
Potentiality of temperature-swing adsorption for removal of hydrophobic contaminants in water
Authors: Yamagiwa Kazuaki , Katoh Mikinori , Yoshida Masanori , Ohkawa Akira , Ichijo Hisao
Published: May 2018

Temperature-sensitive poly (vinylmetylether) gel (PVMEG) reversibly changes its surface property from hydrophilic to hydrophobic and vice versa in response to a temperature change across the phase transition temperature. The adsorbed amount of nonionic surfactant, one of the most serious contaminants in aqueous stream, on PVMEG was comparable to that on a commercial adsorbent Amberlite XAD-2. Desorption of the surfactant from PVMEG was carried out only by shifting temperature within a few degrees. Successive adsorption and desorption was possible by a temperature swing without any decrease in the adsorption capacity. High potentiality of temperature-swing adsorption process with PVMEG was demonstrated.
New approaches to the simulation and optimisation of adsorption processes
Authors: Weingartner A. , Schäfer E. , Staubmann K. , Urban W. , Loiskandl W. , Rassinger M. , Schachner H.
Published: May 2018

A new adsorption procedure showed that adsorption competition can be successfully influenced in favour of organic micropollutants by generating variable velocity fields and thus reducing the adsorption of competing harmless natural organic matter (NOM). A satisfying optimisation of the method can effectively be done with the help of a mathematical model. The model to be developed had to meet two main targets: firstly, it had to be able to simulate the adsorption processes under hydraulic conditions that change with time and space, and secondly, the implementation of the carbon fouling effect had to be improved. First results showed that the calculated breakthrough curves agreed to experimental data. However, batch experiment results indicated that the assumption of adsorption reversibility is only valid for some substances, which is important to consider when modelling competitive adsorption. An improved adsorption analysis method that integrates kinetic behaviour of NOM is expected to give evidence about NOM's carbon fouling properties.
Treatment of taste and odor causing substances in drinking water
Authors: Kim Youngsug , Lee Yeongho , Gee Chai S. , Choi Euiso
Published: May 2018

To collect fundamental data for the improvement of drinking water quality, focusing on the removal of 2-MIB, Geosmin, IPMP, IBMP and TCA, a total of 20m3/d pilot plant was operated with process schemes of GAC with post-O3(PP-I), and without ozonation(PP-II). Five taste and odor causing substances could be removed to non-detectable concentration with PP-I, but GAC alone was not so effective as PP-I. The larger the EBCT and Iodine Number of GAC column employed, the higher the removal efficiencies expected. The minimum EBCT and Iodine Number were respectively 15 min and 1,000 mg/g of GAC column. Geosmin removal efficiencies ranged 30 to 40% at 15.6 ng/l during conventional process scheme, but 70 to 80% removal was achieved by the PP-I and 60 to 70% by PP-II was achieved. IPMP removal efficiencies were 60 to 80% with GAC only. IBMP and TCA were seldom detected in raw water samples, but TCA was the most difficult to remove of five taste and odor causing substances.
Application of the ceramic membrane with hydrophobic skin layer to separation of activated sludge
Authors: Nomura Tsuyoshi , Fujii Takao , Suzuki Motoyuki
Published: May 2018

Porous membrane of poly(tetrafluoroethylene) (PTFE) was formed on the surface of porous ceramic tubes by means of heat treatment of the PTFE particles deposit layer prepared by filtering PTFE microparticles emulsified in aqueous phase. By means of inert gas permeation, pore size was determined and compared with scanning electron micrograph observation. Also rejection measurement of aqueous dextran solutions of wide range of molecular weights showed consistent results regarding the pore size. Since the membrane prepared by this method is stable and has unique features derived from PTFE, it is expected that the membrane has interesting applications in the field of water treatment. Membrane separation of activated sludge by this composite membrane and original ceramics membrane showed that the PTFE membrane gives better detachability of the cake layer formed on the membrane. This might be due to the hydrophobic nature of the PTFE skin layer.
A simple mathematical model for anaerobic digestion process
Authors: Jeyaseelan S.
Published: May 2018

Six different conversion processes have been identified in the anaerobic digestion of particulate organic material to methane. Hydrolysis followed by intermediate acids formation and fermentation to produce methane by five different groups of microorganisms. These may be largely grouped into two major groups, namely the acid producing microorganisms and methane producing microorganisms. Monod kinetic rate equation applies to a strain of bacteria growing on a single rate-limiting substrate. By identifying the kinetic coefficients of the Monod kinetic rate equation for every single component of the solids in wastewater an improved prediction of the anaerobic digestion process can be made using Monod kinetic rate equation. Separate kinetic coefficients for acid formation and methane formation must be identified from the literature or determined through laboratory analysis. Municipal wastewater may be considered as a mixture of carbohydrates, proteins, lipids and a very small proportion of other materials. By an extensive literature review, many Monod kinetic coefficients for the above said components were selected and a very few assumed. Several loading conditions for different proportions of influent wastewater characteristics simulating actual operations were tested using this model. The model can be used to set operating parameters such as BOD loadings, retention times and temperatures that will produce desired efficiency in the systems within practical limits.
Effects of thermochemical pretreatment on the anaerobic digestion of waste activated sludge
Authors: Tanaka Shuzo , Kobayashi Toshio , Kamiyama Ken-ichi , Signey Bildan Ma. Lolita N.
Published: May 2018

Effects of pretreatment on the anaerobic digestion of waste activated sludge (WAS) were investigated in terms of VSS solubilization and methane production by batch experiments. The methods of pretreatment studied are NaOH addition (chemical), heating (thermal) and heating with NaOH addition (thermochemical) to the domestic WAS and to the combined WAS from domestic, commercial and industrial wastewaters. The thermochemical pretreatment gave the best result among three methods in the combined WAS, i.e., the VSS was solubilized by 40-50% and the methane production increased by more than 200% over the control when the WAS was heated at 130°C for 5 minutes with the dose 0.3 g NaOH/g VSS. In the domestic WAS, the VSS solubilization rate was 70-80% but the increase of the methane production was about 30% after thermochemically pretreated. The domestic WAS consists of 41% protein, 25% lipid and 14% carbohydrate on COD basis, and the solubilization rate of protein, which is the largest constituent of the WAS, was 63% in the thermochemical pretreatment. Although the effect of the thermochemical pretreatment on the methane production was higher to the combined WAS than to the domestic WAS, the methane production rate was 21.9 ml CH4/g VSSWAS·day in the domestic WAS and 12.8 ml CH4/g VSSWAS·day in the combined WAS.
Conditioning of oily sludges with municipal solid wastes incinerator fly ash
Authors: Hwa Tay Joo , Jeyaseelan S.
Published: May 2018

Conditioning of sludges improves dewatering characteristics and reduces the quantity of sludge to be handled. Anaerobic digested sludge collected from a sewage treatment plant contained 1.8% to 8% oil. The increase of specific resistance and capillary suction time (CST) with increasing oil content observed in these samples indicates the interference of oil in dewatering. It has been found that addition of municipal solid wastes incinerator fly ash decreases the specific resistances and capillary suction times of oily sludges rapidly up to 3% dosage. Beyond 3% fly ash, the decrease is less significant and the solids content in the sludge cake increases. This optimum dosage remains the same for sludges with varying oil contents from 1.8% to 12%. The total suspended solids of filtrate decreases with fly ash dosage but the toxic concentrations of heavy metals increases considerably. However at the optimum dosage of 3%, concentrations of heavy metals are within the limits for discharging into the sewers. The correlations of CST with the dewatering characteristics such as specific resistance, filter yield and corrected filter yield are established. These correlations can be used to obtain a quick prediction on dewaterability.
Inhibition of methanogenic activity of starch-degrading granules by aromatic pollutants
Authors: Fang Herbert H. P. , Lau Ivan W. C. , Chung Denis W. C.
Published: May 2018

The effects of nine common aromatic pollutants from chemical industry on the bioactivity of anaerobic granules were examined. The granules were obtained from an upflow anaerobic sludge blanket (UASB) reactor treating wastewater containing colloidal starch. The specific methanogenic activities (SMA) of granules were measured at 37°C in serum vials using 3000 mg/l of colloidal starch as substrate, plus individual pollutants at various concentrations. The toxicity was expressed by the IR50 and IC50 values, i.e. the toxicant/biomass ratio and concentration at which levels the granules exhibited only 50% of their original bioactivities. Results showed that in general the granules exhibited mild resistance to toxicity of aromatic pollutants, probably due to the granules' layered microstructure. The toxicities, which were dependent on the nature of chemical functional group, of the aromatic pollutants were in the following descending order: cresols > phenol > hydroxyphenols/phthalate > benzoate. There was only marginal difference between the toxicity of the steric isomers. For the seven phenolic pollutants, the more hydrophobic the functional group the higher the toxicity. The granules' resistance to toxicity suggested the plausibility of anaerobic treatment of wastewater from the chemical industry.
Tyger
Authors: Blake W. , Henze M.
Published: May 2018

Tigers and water resources are both endangered.
The concept of sustainable urban water management
Authors: Larsen Tove A. , Gujer Willi
Published: May 2018

Urban Water Management involves the fields of water supply, urban drainage, wastewater treatment and sludge handling. On the basis of the Agenda 21, principles and guidelines for sustainable urban water management are discussed. Sustainable technology leads to acceptable gradients in state variables. New technologies departing from an analysis of required services rather than stepwise improvement of existing technology is preferred. An efficient use of resources will lead to a minimal increase of entropy and will require an active rather than a reactive approach. The analysis of the transition period from today's to a sustainable situation is important. An example is introduced which deals with global cycling of nutrients and which may be approached on a regional scale.
Global urbanization and urban water: can sustainability be afforded?
Authors: Varis Olli , Somlyódy László
Published: May 2018

Urbanization is definitely one of the most characteristic global changes of today and of the coming few decades. Whereas the world population grows with almost one billion per decade, around four fifths of this growth is in urban areas. The challenges due to the development of urban centers, especially great urban agglomerations in developing countries in a sustainable way are huge. Water is one of the key figures in this equation. It has many roles; this paper discusses sustainable urban water infrastructure. First, solutions and experiences from the industrialized countries are summarized, and possibilities and difficulties to adapt them to large urban areas of the Third World are discussed. A particular focus in the affordability issue is taken. Various development indicators and their applicability are discussed. A summary and discussion on technical, economical, financial, and institutional alternatives follows.
Towards sustainable urban drainage
Authors: Butler David , Parkinson Jonathan
Published: May 2018

The issue of sustainable development is now high on the global agenda, but there is still a considerable degree of uncertainty in its definition, let alone implementation. The aim of this paper is to reappraise the provision of urban drainage services in the light of this current debate. The approach advocated is not to strive for the unattainable goal of completely sustainable drainage, rather to actively promote “less unsustainable” systems. To do this requires both an understanding of the long-term and widespread impacts of continuing current practices and an understanding of the implications of making changes. Sustainable urban drainage should: maintain a good public health barrier, avoid local or distant pollution of the environment, minimise the utilisation of natural resources (e.g. water, energy, materials), and be operable in the long-term and adaptable to future requirements. Three strategies are proposed that can be carried out immediately, incrementally and effectively and these are to reduce potable water “use”, to reduce and then eliminate the mixing of industrial wastewater with domestic waste, and to reduce and then eliminate the mixing of stormwater and domestic wastewater. A number of techniques are described which may allow adoption of these strategies, many of them small-scale, source control technologies. An incremental approach containing both high-tech and low-tech answers to appropriate problems is the most likely to be implemented but each case must be decided on its merits.
Waste design for households with respect to water, organics and nutrients
Authors: Henze M.
Published: May 2018

Waste design couples handling and treatment of waste with the production and control of waste materials. This integrated approach will allow for a reduced use of non renewable resources in waste treatment. The paper discusses the use of waste design for households and its impact on the composition of household wastewater. This will allow for the design of a wastewater with characteristics quite different from those normally found. The separation of toilet wastes or just urine can reduce the amount of nitrogen and phosphorus in the wastewater to a level where no further nutrient removal is needed. The BOD and COD load to wastewater can be significantly reduced by separating toilet wastes and part of the kitchen wastes. The phosphate content of detergents influences the phosphorus load significantly. Kitchen wastes can be diverted to the solid waste system or the compostable fraction of solid wastes can be incorporated into the wastewater by use of garbage grinders. The change in pollutant load can be achieved separately or in combination with water savings. It is thus possible to reduce or increase the overall concentration of pollutants, and to design wastewater with a given COD/TN or COD/TP ratio, which is of significant influence on biological nutrient removal processes.
A sustainable municipal wastewater treatment process for tropical and subtropical regions in developing countries
Authors: Hanqing Yu , Tay Joo-Hwa , Wilson Francis
Published: May 2018

In this paper, a feasible municipal wastewater treatment process, using the upflow anaerobic sludge blanket (UASB) or the anaerobic baffled reactor (ABR) as an anaerobic pre-treatment system, and the reed bed or the stabilization pond with supporting media as a post-treatment system, is presented and discussed. Results obtained in pilot- and full-scale treatment plants clearly reveal that the anaerobic treatment is indeed a very attractive option for municipal wastewater pre-treatment at temperatures exceeding 20C in tropical and subtropical regions. The UASB system has been commonly employed as an anaerobic pre-treatment system. The ABR provides another potential for the anaerobic pre-treatment. The effluents from the anaerobic treatment system should be post-treated to meet discharge standards. Because of the advantages of the reed bed system when it is employed for tertiary treatment, this system could be considered as a post-treatment system. Another cost-effective system, the stabilization pond packed with attached-growth media, is also a potential post-treatment system.
Degradation of benzo[a]pyrene, dibenz[a,h]anthracene and coronene by burkholderia cepacia
Authors: Juhasz Albert L. , Britz Margaret L. , Stanley Grant A.
Published: May 2018

A Burkholderia cepacia strain (VUN 10,001) isolated from manufacturing gas plant soil was selected for its ability to grow on and degrade pyrene as a sole source of carbon and energy. VUN 10,001 was able to grow on fluorene, phenanthrene benz[a]anthracene, fluoranthene and pyrene, but not benzo[a]pyrene and dibenz[a,h]anthracene when tested using inocula with low cell numbers. However, a small decrease in the concentrations of these latter compounds was observed. When media were inoculated at a high cell density, VUN 10,001 degraded the high molecular weight PAHs benzo[a]pyrene, dibenz[a,h]anthracene and coronene when these were present as individual substrates or as components of a complex mixture. Degradation of the high molecular weight PAHs was found to increase in the presence of the lower molecular weight compounds.
Experimental evidence for the need of thermodynamic considerations in modelling of anaerobic environmental bioprocesses
Authors: Hoh Choon-Yee , Cord-Ruwisch Ralf
Published: May 2018

For modeling of biological processes that operate close to the dynamic equilibrium (eg. anaerobic processes), it is critical to prevent the prediction of positive reaction rates when the reaction has already reached dynamic equilibrium. Traditional Michaelis-Menten based models were found to violate the laws of thermodynamics as they predicted positive reaction rates for reactions that were endergonic due to high endproduct concentrations. The inclusion of empirical “product inhibition factors” as suggested by previous work could not prevent this problem. This paper compares the predictions of the Michaelis-Menten Model (with and without product inhibition factors) and the Equilibrium Based Model (which has a thermodynamic term introduced into its rate equation) with experimental results of reactions in anaerobic bacterial environments. In contrast to the Michaelis-Menten based models that used traditional inhibition factors, the Equilibrium Based Model correctly predicted the nature and the degree of inhibition due to endproduct accumulation. Moreover, this model also correctly predicted when reaction rates must be zero due to the free energy change of the conversion reaction being zero. With these added advantages, the Equilibrium Based Model thus seemed to provide a scientifically correct and more realistic basis for a variety of models that describe anaerobic biosystems.
The influence of the anaerobic digestion process on the sewage sludges rheological behaviour
Authors: Monteiro Paulo Santos
Published: May 2018

During the anaerobic digestion process, a significant part of the organic matter in sewage sludge is decomposed to form other organic and inorganic compounds in dissolved form. This biological transformation of a substantial part of the organic solids has, certainly, a strong influence on the rheological characteristics of the sludge. In this paper a test facility was set up to simulate sewage sludge digestion and periodic observations on the evolution of the sludge characteristics were carried out. Results of this study show that important changes on the sludge rheological behaviour occur during anaerobic digestion and that the evolution of those changes is related to the degree of digestion. Moreover, it is shown that the verified high degree of physical changes can not be explained only by the total solids concentration variation and two hypotheses are proposed to explain those changes.
Morpho-chemistry in secondary sludge filtration cakes: a case study
Authors: Deneux-Mustin Sylvie , Lartiges Bruno , Villemin Genevieve , de Donato Philippe , Bersillon Jean-Luc , Thomas Fabien , Snidaro Denis
Published: May 2018

Light Microscopy, Transmission Electron Microscopy (TEM, EDXS), and Fourier Transform Infra Red MicroSpectroscopy (FTIRMS) were used to describe the organization and chemical distribution of major constituents in a sludge filtration cake. Samples were obtained from a municipal wastewater treatment plant using conventional ferric chloride and lime sludge conditioning. Various samples collected at different stages of the process were embedded in an Epoxy resin after acetone-dehydration, and sectioned using an ultra-microtome. The thickness of the sections was adapted to the experimental techniques used.

TEM showed that in the activated sludge, bacterial colonies, isolated bacteria and debris are trapped within a gel matrix of exocellular polymeric substances, whereas those same components are compacted and distorted in the filtration cake. Furthermore, conditioning chemicals appeared in the cake as amorphous aggregated colloids and acicular particles which do not form inside the colonies. A chemical mapping was obtained by determining and integrating FTIR bands characteristics of specific components of the cake. Preliminary results showed that the amounts of resin can be used to assess the relative compacity at different levels of the cake.