bluuebunny/crossref_metadata_2025 huggingface dataset:
Olive oil mill wastewater as carbon source in post anoxic denitrification
Authors: Tsonis S. P.
Published: May 2018

A study was undertaken to evaluate the efficiency of applying olive oil mill wastewater as a non-nitrogenous external carbon source in the second anoxic stage of a five stage modified Bardenpho system for nutrients removal in order to assure consistently very low concentrations of total nitrogen (well below 3 mg/l) in the treated effluent. Addition of olive oil mill wastewater was found acceptable only up to 50 mg sCOD of mill waste/l of wastewater fed to the system because at higher additions color problems in the treated effluent were encountered. The required dosage of olive oil mill wastewater was found to be in the range 4.6-5.4 mg sCOD/mg N-NO3 removed. Operation with olive oil mill wastewater effects at the same time higher removal of phosphorus. Addition of physicochemically pretreated olive oil mill wastewater with lime to the second anoxic tank at a rate of 22-45 mg sCOD/l of municipal type wastewater fed (ratio of volume of the mill waste added to the volume of the municipal type wastewater fed 1:1000-1:2000) resulted in a treated effluent with total nitrogen below 3 mg/l and soluble phosphorus well below 1 mg/l.
The influence of high phenol concentration on microbial growth
Authors: Yoong E. T. , Lant P. A. , Greenfield P. F.
Published: May 2018

This investigation looked at the influence of high phenol concentrations (1000-1500 mg/l) on the growth yield of phenol degrading organisms in batch culture. The yield coefficient varied from 0.16 to 0.27. These values are considerably lower than those determined by others at lower phenol substrate concentrations. Although the conversion efficiency to biomass was low, the removal of phenol in terms of COD in the batch cultures was high (93.6% average). Present results did not show a relationship between yield and specific growth rate over the range 1000-1500 mg/l phenol. More work is required over a wider range of substrate concentration. With increasing phenol concentrations, the specific growth rate declined, consistent with Haldane inhibition kinetics.
Treatment system response to transient AOX (adsorbable organic halogen) loadings
Authors: Barton D. A. , Woodruff J. D. , Bousquet T. M. , Parrish A. M.
Published: May 2018

If promulgated as proposed, effluent guidelines for the U.S. pulp and paper industry will impose average monthly and maximum daily numerical limits of discharged AOX (adsorbable organic halogen). At this time, it is unclear whether the maximum-day variability factor used to establish the proposed effluent guidelines will provide sufficient margin for mills to achieve compliance during periods of normal but variable operating conditions within the pulping and bleaching processes. Consequently, additional information is needed to relate transient AOX loadings with final AOX discharges. This paper presents a simplistic dynamic model of AOX decay during treatment. The model consists of hydraulic characterization of an activated sludge process and a first-order decay coefficient for AOX removal. Data for model development were acquired by frequent collection of influent and effluent samples at a bleach kraft mill during a bleach plant shutdown and startup sequence.
Pre-treatment and elimination systems of toxic industrial waste and sludges. The case study of the department of Attika
Authors: Malliaros C. , Guitonas A.
Published: May 2018

In the departments of Attika and Viotia there are about 1,100 industries. The total amount of produced waste from the above mentioned branches is 20 × 106 t/year, 600,000t of which contain toxic substances. By contract from October 1st, 1992 between the Ministry of the Environment, Regional Planning and Public Works and three collaborating offices (among them the office of C. Malliaros) has been assigned to the latter, the realisation of a study of the management of toxic waste (liquid) and sludges, in the Departments of Attika and Viotia. The study presented in this paper investigates the following: - collection and evaluation of data and estimation of the hydraulic and pollution loads - classification of industries according to sewage facilities - further possibilities for changes of improvements in the production process of the industrial branches for the reduction of pollution and representation of these industries on maps - proposals for the collection and transport of the liquid toxic waste and sludges - pre-treatment at the source and disposal of the liquid waste and sludges - presentation of administrative and legislative regulations - forming a policy for the management and monitoring of this waste - technical and financial evaluation and investigation of the alternative methods of treatment - suggestions for the development of the area concerning the activities and the expenses at various levels.
Wet oxidation as a pretreatment method for wastewaters contaminated by bioresistant organics
Authors: Mantzavinos Dionissios , Lauer Erik , Hellenbrand Rolf , Livingston Andrew G. , Metcalfe Ian S.
Published: May 2018

The partial wet air oxidation of aqueous solutions of polyethylene glycol, a model organic pollutant typically found in wastewaters of polymer-manufacturing, has been investigated at temperatures from 383 K to 513 K and oxygen partial pressures from 2 MPa to 3 MPa. The progress of the reaction was investigated in terms of COD and TOC removal, while fragmentation of the original polymer to lower molecular weight compounds was followed by means of liquid chromatography. The impact of various heterogeneous and homogeneous catalysts on the kinetics and mechanisms of the reaction has also been studied. Conversion of the model compound through various oxidation intermediates to end-products, such as carboxylic acids and oligomers, could be easily achieved even under mild operating conditions, while further total oxidation proved to be difficult even under more severe conditions. Catalysts were found to be, in general, capable of increasing the rates of total uncatalysed oxidation. The implications for complete removal of bioresistant organic pollutants by partial wet oxidation followed by a biological treatment step are also discussed.
Using caged bivalves to characterize exposure and effects associated with pulp and paper mill effluents
Authors: Salazar Michael H. , Salazar Sandra M.
Published: May 2018

Routine environmental effects monitoring (EEM) should include field bioassays with caged bivalves -- chemical exposure is characterized by measuring the concentration of chemicals in tissues and biological effects are characterized by measuring growth. This field bioassay combines the experimental control of laboratory bioassays with the environmental realism of field monitoring. Transplanting caged bivalves in the immediate vicinity of discharges ensures maximum exposure; if bioavailable chemicals are present in the effluent they will be accumulated within the tissues, and if the concentrations are sufficiently high to be deleterious, the effect of the exposure can be quantified. The transplant methodology described herein can be used to identify the following: (1) site-specific differences; (2) short-term and long-term trends; (3) temporal and spatial variability; (4) source identification; and (5) exposure-dose-response relationships. These results will help answer one of the most commonly asked questions asked by industry, government, and the public: “Are conditions getting better, worse, or staying the same?” Further, using the bivalve transplant approach as part of an integrated program will help reduce uncertainties associated with more traditional approaches like fish monitoring, laboratory bioassays and benthic community assessments.
Physicochemical treatment of industrial wastewater with the multistage neutralization process
Authors: Paraskevas P. A. , Lekkas T. D.
Published: May 2018

A complex industrial wastewater case is studied. The great variety of the products and the complexity of the production procedures render it impossible to apply a conventional technology for wastewater treatment. Initially an attempt was made to reduce the quantity and the organic load by reusing wastewater and by reclaiming useful substances or products from the wastewater. To further reduce COD the multistage neutralization process is studied by regulating the pH of the acid wastewater first in the alkaline region and then at pH 7. In this way COD removal is 18% greater than with the simple neutralization process at pH 7. Once this process was completed, since the effluent COD was not within the permissible limits, oxidation of the wastewater by using ozone was recommended.
PACTTM process for treatment of kraft mill effluent
Authors: Narbaitz R. M. , Droste R. L. , Fernandes L. , Kennedy K. J. , Ball D.
Published: May 2018

The PACTTM process (powdered activated carbon addition to the activated sludge process) was evaluated for the treatment of Kraft pulp mill wastewater in a series of bench scale experiments. Possibly due to the relatively low strength wastewater, the PACTTM process with carbon doses between 0.5 and 1.0 g/L of influent only performed marginally better than the conventional activated sludge process. Chemical oxygen demand and toxicity, evaluated with the Microtox® assay, were among the parameters monitored. For the operating conditions tested the solids retention time had no impact on performance. The main improvement was increased in adsorbable organic halides (AOX) removal, the magnitude of the improvement was dependent on the wastewater batch and the carbon dose. However conventional activated sludge treatment will meet Ontario's year 2000 AOX regulations. An empirical model from the literature described the data fairly well.
Management of water resources in South Africa with respect to the textile industry
Authors: Gravelet-Blondin L. R. , Barclay S. J. , Carliell C. M. , Buckley C. A.
Published: May 2018

South Africa is a water scarce country with an average annual rainfall of less than 60% of the world average. It is therefore important to encourage industries to minimise water consumption, and recycle and re-use water and effluent where possible. The South African Department of Water Affairs and Forestry is responsible for the management of water resources in South Africa, thereby ensuring the provision of adequate water supplies of acceptable quality for all recognised users. Of the industrial effluents produced in South Africa, textile effluents are considered to be one of the most problematic in the KwaZulu-Natal coastal area, especially in terms of colour, chemical oxygen demand (COD) and salinity (total dissolved solids, TDS). Of these, colour is perceived to be the most problematic as it is visual pollution and gives rise to public complaints. The Department has been actively involved, through negotiations with management and local authorities, in encouraging the textile industries to reduce the colour load discharged from the factories. Four case studies will be presented describing the approach taken by the Department to solve the problem of textile effluent discharge.
Two examples of anaerobic pre-treatment of wastewater in the beverage industry
Authors: Austermann-Haun Ute , Rosenwinkel Karl-Heinz
Published: May 2018

Two examples of full scale UASB-reactors in a fruit juice factory and a brewery are given. In both cases, the design was based on semi-technical tests. Although the wastewater concentrations are rather similar and move within a low range, the parts of the anaerobic treatment plants and their design are different. In both cases, the COD removal efficiency in the UASB-reactors is consistently above 80%. It becomes apparent that UASB-reactors are very suitable for industries with seasonal load variations. The co-fermentation of a kieselguhre-sludge-mixture was tested in lab-scale experiments. It became obvious that the pellet structure of the biomass gets lost. Furthermore, it is shown that the running expenses of anaerobic pre-treatment are very low, even when combined with an aerobic stage.
Full scale experiences with anaerobic pre-treatment of wastewater in the food and beverage industry in Germany
Authors: Austermann-Haun Ute , Seyfried Carl Franz , Rosenwinkel Karl-Heinz
Published: May 2018

In Germany, there are currently 106 full-scale anaerobic treatment plants treating industrial wastewater. This paper describes the operational experiences of several industries (beet sugar, starch, pectin, brewery, distillery, vegetable) which undertake anaerobic wastewater treatment, with particular emphasis on specific wastewater problems and their solutions. Also presented are experiences of the handling of high nitrate concentrations, with the treatment of mixtures of industrial wastewater from different origins, with the chance to prevent the emergence of lime, magnesium ammonium phosphate (MAP) or aluminium precipitation.

This paper deals with the first municipal wastewater treatment plant combined with a separate anaerobic stage to treat a wastewater mixture of several small factories. One particular asset of this plant is the construction of the acidification tank: using the “teapot effect” to enrich the solid material in the centre of the bottom, the solids can be taken from the bottom of the tank and pumped to the municipal sludge digester.
ASBR treatment of low strength industrial wastewater at psychrophilic temperatures
Authors: Banik Gouranga C. , Dague Richard R.
Published: May 2018

Anaerobic treatment of dilute wastewater was studied using three laboratory-scale anaerobic sequencing batch reactors (ASBR), each with an active volume of six (6) liters. The reactors were fed a synthetic substrate made from non-fat dry milk supplemented with nutrients and trace metals. The COD and BOD5 of the feed was 600 mg/l and 285 mg/l, respectively. Steady-state performance data were collected at reaction temperatures of 25, 20, 17.5, 15, 12.5, 10, 7.5 and 5°C over a period of two years. Hydraulic retention times (HRT) were maintained at 24, 16, 12, 8 and 6 hours.

Results showed that the ASBR process was capable of achieving in excess of 90% soluble COD and BOD5 removal at temperatures of 25°C and 20°C at all HRTs. At the low temperature of 5°C and the six hour HRT, soluble COD and BOD5 removals were 62% and 75%, respectively. At the intermediate temperatures from 20°C down to 5°C and HRTs between 24 and 6 hours, removal of soluble organics ranged between 62 and 90 % for COD and 75 and 90 % for BOD5. In all cases, SRT were high enough to maintain good performance. Substrate utilization rates and half-velocity constants were also determined at all temperatures. The temperature correction coefficient was found to be 1.08 in the temperature range from 25°C to 7.5°C which follows the Q10 or Van't Hoff's rule.
Application of a granular activated carbon-biological fluidised bed for the treatment of landfill leachates containing high concentrations of ammonia
Authors: Horan N. J. , Gohar H. , Hill B.
Published: May 2018

The Envirex granular activated carbon biological fluidized bed (GAC-BFB) process was used to treat landfill leachate containing organic material with typical COD values in the range 800 to 2,700 mg/l, but with high concentrations of ammonia in the range 220 to 800 mg/l. Prior to treatment the leachate was softened by raising the pH to 9.0 using lime in order to remove any contaminating heavy metals. Two identical pilot-plant GAC-BFB's were used in series to treat the softened leachate. The first of these was intended to achieve carbonaceous removal whilst the second was used for ammonia removal by nitrification. During the first four months of operation at a loading rate of 1.56 kg ammonia-N/m3 d, the reactors removed 70% of the ammonia, 60% of COD and achieved a complete removal of BOD. After optimising the reactor operating regime, it proved possible to achieve greater than 90% removal of ammonia at a loading rate of 0.71 kg N/m3 d; however the COD removal remained unchanged. In order to compare the ammonia removal efficiency of the GAC-BFB system, two conventional activated sludge reactors were operated in parallel at hydraulic retention times of 24 and 36 hours (equivalent to ammonia loadings of 0.72 and 0.48 kg ammonia-N/m3 d) and with a sludge age of 20 days. These reactors were not able to nitrify and although a BOD removal of 90% was achieved the COD removal was poor at 20%. Thus the GAC-BFB system offers a highly effective option for the biological removal of ammonia from high ammonia leachates, with the additional advantage of a good COD removal.
Fraser river action plan resident fish condition and contaminants assessment
Authors: Raymond B. A. , Shaw D. P.
Published: May 2018

The condition of resident mountain whitefish and peamouth chub in the Fraser River basin was assessed based on health and tissue contaminant levels. All fish were examined in the field for external and internal abnormalities (HAI) and tissue samples were collected for histological examination. Analyses of mixed function oxygenase enzyme activity (EROD) in liver and tetrachlorinated dioxins in muscle and liver were used as indicators of contaminant exposure. A high incidence of HAI abnormalities occurred in these species throughout the basin and the HAI was not strongly correlated with age, EROD activity, or histological abnormalities. Tetrachlorinated dioxin (TCDD) residues in fish tissue and EROD activity in liver were elevated downstream of pulp mills and urban centres, but dioxin levels were low, near or below detection limits and guidelines.
Environmental and molecular regulation of methanogenesis
Authors: Reeve John N. , Morgan Roderick M. , Nölling Jörk
Published: May 2018

Hydrogen plays a central role in regulating the anaerobic biodegradation of organic materials to carbon dioxide and methane. At an intermediate stage, alcohols and fatty acids are fermented to acetate, CO2 and H2. Methanogens consume this H2, gaining energy by reducing CO2 and the CH3-moieties of methanol, methylamines and acetate to CH4, and growing by assimilating these same substrates into biomass. There are seven biochemical steps in the H2-dependent pathway of CO2 reduction to CH4 in Methanobacterium thermoautotrophicum, a very common inhabitant of anaerobic digestors, several of which can be catalyzed by more than one enzyme. The choice of which enzyme is synthesized and therefore used in methanogenesis is determined by the availability of H2. With high H2 availability, M. thermoautotrophicum cells grow rapidly but their overall growth yield (YCH4; biomass synthesized per mole of CH4 synthesized) is lower than for cells growing more slowly under H2-limited conditions. Experiments are reported that document the relationships between H2 availability, alternative methane gene expression and growth yield, and that demonstrate H2-dependent reversible switching between rapid, relatively inefficient growth and slower more efficient growth. This switch is controlled by the mixing rate of the impeller in fed-batch fermentors sparged with CO2 and H2.
Anaerobic transformation kinetics and pathways of chlorophenols in fresh water lake sediment
Authors: Susarla S. , Yonezawa Y. , Nakanishi J. , Masunaga S.
Published: May 2018

The reductive dechlorination of six dichlorophenol (DCP) isomers was examined in a fresh water sediment collected from Kasumigaura lake in Japan. Short lag periods were observed for all the DCPs examined varying between 1–20 days. The relative degradation rates of six DCP isomers were 2,5- > 2,4- > 2,3- > 2,6- > 3,5- > 3,4- DCP with half- lives of ranging between 7-39 days. The specificity of chlorine removal indicated a preference for ortho-chlorine removal for dichlorophenol isomers substituted at ortho position, while meta and meta/para chlorine removal was observed for 3,5- and 3,4-DCP, respectively. Intermediate products of transformation, 2-, 3- and 4-MCP and phenol were identified with a combination of gas chromatography and mass spectrometry using standards.
Controlling granular sludge floatation in UASB reactors
Authors: Yoda M. , Nishimura S.
Published: May 2018

Granule floatation may occur at higher organic loadings, resulting in a loss of active granules and a decrease in the treatment capacity of UASB reactors. Granular sludge sampled from full-scale UASB reactors was studied to investigate the mechanism of granule floatation. It was found that granules float due to the buoyant force created by the gas bubbles entrapped in the hollow spaces of granules. Two hypotheses on the mechanisms of hollowing were presented, and in order to prevent granule floatation, the protocol, i.e., grinding of floating granules by a mechanical device and dosing of Fe into the reactors, was proposed. The protocol was evaluated in a series of lab-scale experiments and proven to be effective and practical for use in full-scale UASB reactors.
A VFA measuring biosensor based on nitrate reduction
Authors: Rozzi A. , Massone A. , Antonelli M.
Published: May 2018

A modified version of a biosensor (DENICON) used to measure nitrates in wastewaters is presented which allows for the determination of VFA concentration as readily biodegradable COD (rbCOD). A sample of the digested effluent is mixed to denitrifying microorganisms in excess of nitrates. As a consequence, a fraction of NO3, proportional to the biodegradable organic carbon, is reduced and may be measured by titration.

The concentration of rbCOD is then derived from the consumption of nitrates as Biodegrable Nitrate Demand (BND). Taking into account that the prevailing fraction of rbCOD in digested anaerobic liquors is made of VFA, this paper investigates the possibility of measuring VFA concentration with the proposed biosensor. Extensive tests have been carried out on a laboratory instrument, using acetate, butyrate and propionate as model compounds.

A satisfactory correlation (R2 > 0.95) between organic carbon and reduced nitrate has been found for the three substrates. Mixtures of acids, especially acetic + propionic have also been tested because this association is the one often found when unstable conditions arise in a digester. It has been observed that the reaction rate increases with respect to acetic acid only when a solution of acetic + propionic acids is denitrified. This effect might allow for a qualitative evaluation of incoming instability.

The instrument can be easily automated and might allow a VFA determination every 20-40 minutes, which is sufficient for most anaerobic applications.
Mathematical modelling and simulation of an industrial scale fluidized bed reactor for anaerobic wastewater treatment – scale-up effect on pH-gradients
Authors: Schwarz Alexander , Mösche Marek , Wittenberg Ahrend , Jördening Hans-Joachim , Buchholz Klaus , Reuss Matthias
Published: May 2018

A mathematical model of anaerobic wastewater treatment in an industrial scale fluidized bed reactor (FBR) is presented together with simulation results for reactors in lab-scale (1 l) and industrial scale (500 m3). The model was developed to study the effect of scale up on the anaerobic wastewater treatment in FBRs by examining the interactions between biological degradation and the physico-chemical environment upon the outcome of this process. Material balance equations for substrates and products in gas and liquid phase are basis of the model. Hereby, the following effects were taken into account: biological degradation steps, convection and dispersion, chemical equilibria and calcium carbonate precipitation under consideration of ion activities. Model extensions are discussed, for example the calcium carbonate precipitation and the pH-dependency of degradation reactions. Simulation results show the strong impact of reactor performance on axial pH-gradients and thus on process stability in dependence of reactor scale. In this context the crucial role of the precipitation reaction together with the substrate degradation und carbon dioxide production reactions on local pH-values in the system is illustrated.
Modeling of the fate and effect of chlorinated phenols in anaerobic treatment processes
Authors: Kim In S. , Tabak Henry H. , Young James C.
Published: May 2018

Studies were conducted to assess the biotransformation kinetics and inhibitory effects of mono-, di-, and trichlorophenol on acetogenic and methanogenic reactions using a standardized anaerobic protocol (Young and Tabak, 1993). Intrinsic kinetic parameters were estimated for each reaction using the Monod model. Reductive dechlorination of the toxicants was investigated using acclimated mixed cultures under methanogenic conditions. The studies indicated that inhibition of acetogenesis and methanogenesis was best described using exponential rather than linear inhibition terms. A second significant observation was that acclimated test cultures had a finite biodegradation capacity for each chemical that was related to the mass of microorganism present. A unique feature of the test program was that inhibition and biodegradation were modeled using the specific biomass responsible for acetogenesis and methanogenesis rather than the total anaerobic biomass.
Combined pre-degradation and anaerobic digestion for the treatment of a baker's yeast factory effluent
Authors: Van Der Merwe-Botha M. , Britz T. J.
Published: May 2018

A Chryseomonas luteola strain was isolated from raw baker's yeast factory effluent as the dominant part of the microbial community and evaluated for its biodegradative activity, using the raw effluent as substrate. The strain was able to utilise the raw effluent and produce higher concentrations of energetically favourable metabolites and thereby, could contribute to the first degradation step in an anaerobic biological treatment process. A 3×4×3 factorial design indicated optimal degradation conditions in a specific environmental framework of 48 h incubation time, COD concentration of 30 g/l, pH of 6.0 and temperature of 35°C. The C. luteola strain was thereafter used in a pre-degradation step followed by an anaerobic digestion step in a 5 1 laboratory-scale hybrid digester. With the use of the pre-degraded effluent, significant improvements were found in the overall anaerobic digestion performance. These included increased COD (>15%) and TVFA (>50%) removals, especially propionic acid (88%) removal, as well as higher biogas yields (18%). The results also showed a prominent improvement in fatty acid utilisation and methanogenesis. The pre-degradation step resulted in better process control and increased stability of the system, even at relatively high organic loading rates (10 kg COD/m3.d). When the raw effluent was not pre-treated (control bioreactor), no improvement in bioreactor efficiency was observed.
Anaerobic treatment of partly acidified wastewater in a two-stage expanded granular sludge bed (EGSB) system at 8°C
Authors: van Lier Jules B. , Rebac Salih , Lens Piet , van Bijnen Friso , Elferink Stefanie J. W. H. Oude , Stams Alfons J. M. , Lettinga Gatze
Published: May 2018

Psychrophilic (8 °C) anaerobic treatment of partly acidified waste water was investigated using a two stage EGSB system with a total volume of 8.6 dm3. The reactor system was operated at an up-flow velocity of 10 m·h−1 and was fed with a sucrose-VFA mixture of 550–1100 mg COD dm−3. The average CODsol and VFA-COD removal efficiencies were 97 and 90 %, respectively, at total organic loading rates (OLR) ranging between 5.1–6.7 g COD dm−3·day−1, sucrose loading rates up to 1 g COD dm−3 day−1 and a hydraulic retention time (HRT) of 4 h. An increase in the sucrose loading rates resulted in a significant wash-out of biomass from the first stage. The second stage satisfactory served as a scavenger of non-degraded VFA from the first stage.

Specific activity assays showed an increase of 15 % in the specific methanogenic activity of the sludge present in the second stage and a decrease of 9 % in the first stage. Apparently, an enrichment of methanogens and acetogens in the anaerobic sludge in the second stage took place at temperatures as low as 8°C. The acidogenic population became much more dominant in the first stage, resulting in a higher acidifying activity and a decreased methanogenic activity. 16S rRNA probe-techniques (dot blot hybridization) showed that the acetate consuming Methanosaeta (formerly Methanothrix) and the hydrogenotrophic Methanobrevibacter species (or relatives) were the most abundant methanogens present in the psychrophilic sludge. The ratio between bacterial and methanobacterial hybridization signal of the first stage was 3 times higher than that of the second stage. By using NMR techniques, a higher effective diffusion coefficient was found for the smaller sized granules in both reactors, which is in congruent with the higher maximum specific acetate degrading activity of the smaller granules.
Anaerobic digestion of primary sludge from chemical pre-precipitation
Authors: Ghyoot Wouter , Verstraete Willy
Published: May 2018

Many existing wastewater treatment plants are to be upgraded for phosphorus removal. In our study, ferric chloride was used as a coagulant in pre-precipitation of municipal sewage. Using a Fe/P molar ratio of 0.8, removal efficiencies for suspended solids (64%), chemical oxygen demand (50%), Kjeldahl nitrogen (22%), total phosphorus (43%) and orthophosphate (51%) were obtained. Anaerobic digestion of raw primary sludge yielded a volatile solids (VS) destruction of 35% at VS loading rates of 0.60 to 0.79 kg VS/m3.d. Digestion of chemically enriched primary sludge (CEP-sludge) yielded a VS destruction of 57% at a VS loading rate of 1.36 kgVS/m3.d. Comparison of the methane production per kg VS destroyed (519 to 612 1 CH4/kgVS destroyed for primary sludge, 299 to 395 1 CH4/kgVS destroyed for CEP-sludge) evidenced a change in the composition of the organic material after precipitation with coagulants; the latter sludge was enriched in less reduced compounds. The precipitated phosphorus was not released to the supernatant during anaerobic digestion. No evidence for reduced digester stability was found for digestion of CEP-sludge. These results indicate that retro-fitting a plant by chemical pre-precipitation and subsequent anaerobic digestion of the CEP-sludge is a feasible option.
The anaerobic treatment of low strength wastewaters in UASB and EGSB reactors
Authors: Kato Mario T. , Field Jim A. , Lettinga Gatze
Published: May 2018

The application of the UASB and EGSB reactors for the treatment of low strength wastewaters was investigated. The effect of dissolved oxygen on the methanogenic activity of granular sludges, the low substrate levels inside reactors and lower temperatures on the treatment performance were evaluated. The results showed that methanogens located in granular sludge have a high tolerance to oxygen. The concentration to cause 50% inhibition to methanogenic activity was between 7% and 41% oxygen in the head space of flasks, corresponding to 0.05 mg/l and 6 mg/l of DO prevailing in the media, respectively. The feasibility of UASB and EGSB reactors at 30°C was demonstrated. In UASB reactors, COD removal efficiencies exceeded 95% at organic loading rates up to 6.8 g COD/l.d and influent COD concentrations ranging from 422 to 722 mg/l, during the treatment of ethanol substrate. In EGSB reactors, efficiencies were above 80% at OLRs up to 12 g COD/l.d with COD as low as 100 to 200 mg/l. The studies confirmed that in practice DO does not constitute any detrimental effect on the reactor treatment performance. Lowering the temperature down to 15°C in EGSB reactors also showed that the potentials of anaerobic technology can be further explored in the treatment of dilute wastewaters.
Anaerobic digestion of municipal solid organic waste: valorga full-scale plant in Tilburg, the Netherlands
Authors: de Laclos Hélène Fruteau , Desbois Serge , Saint-Joly Claude
Published: May 2018

Anaerobic digestion has been up to now essentially applied to wastewater. However, anaerobic treatment of organic solid waste fits in well with the new requirements for waste management. The Valorga full-scale plant in Tilburg (the Netherlands) is designed to process 52,000 tons per year of organic municipal solid waste separately collected. The Valorga digestion process is a semi-continuous, high-solid, one-step, plug-flow type process. The main characteristic is the complete absence of any mechanical equipment inside the reactors. The waste to be treated consists of food and garden waste. The characterization of the waste stream revealed a seasonal fluctuation in quantity and quality, that was correlated with seasonal garden waste production. The methane yield is varying from 210 to 290 m3 STP per Mg of volatile solids. It is related to waste composition. During the slack winter period the waste contains proportionally more food waste that is more biodegradable than lignocellulosic garden waste. The biological process was stable based on volatile acidity, alkalinity and ammonia measurements in the effluent. The organic residue, after dewatering and storage under aerobic conditions, can be considered as soil conditioner.
Analysis of environmental factors affecting methane production from high-solids organic waste
Authors: Lay J. J. , Li Y. Y. , Noike T. , Endo J. , Ishimoto S.
Published: May 2018

A simple model developed from the Gompertz equation was used to describe the cumulative methane production curve in the batch culture. By using this model, three key parameters, namely methane production rate, potential and lagphase time, in a cumulative methane production curve were exactly estimated based on the experimental data. The results indicate that each gram of dry organic waste of a sludge cake, meat, carrot, rice, potato and cabbage had a methane production potential of 450, 424, 269, 214, 203 and 96 mL, respectively. The methanogenic activity of these digesters decreased with a decrease in the moisture content. The moisture content threshold limit, at which the methanogenic activity dropped to zero, was found to be 56.6% for the sludge cake, but greater than 80% for meat, carrot and cabbage. In the high-solids sludge digestion, the relative methanogenic activity dropped from 100% to 53% when the moisture content decreased from 96% to 90%. The rate of methane production at moisture contents of 90% to 96% functioned in a pH range between 6.6 and 7.8, but optimally at pH 6.8, and the process may fail if the pH was lower than 6.1 or higher than 8.3. On the other hand, the methanogenic activity was dependent on the level of ammonium, NH4+, but not free ammonia, NH3, indicating that the NH4+ was the more significant factor rather than the NH3 in affecting the methanogenic activity of a well-acclimatized bacterial system. In the wide pH range of 6.5 to 8.5, the methanogenic activity decreased with the increase in the NH4+; dropped 10% at the NH4+-N concentration of 1670-3720 mg·L−1, 50% at 4090-5550 mg·L−1 and dropped to zero at 5880-6600 mg·L−1. However, the lagphase time was dependent on the NH3 level, but not on NH4+, and when NH3-N was higher than 500 mg·L−1, a notable shock was observed. This suggests that the NH3 level was the more sensitive factor than the NH4+ level for an unacclimatized bacterial system.
Atmospheric methane: sources, sinks, and strategies for reducing agricultural emissions
Authors: Minami K. , Takata K.
Published: May 2018

Methane (CH4) is one of the most abundant organic gases in the atmosphere. Recently the importance of CH4 as a greenhouse gas has been recognized and studies have been carried out to asses its contribution to global warming. In this paper we show that atmospheric CH4 is produced by a wide variety of natural and anthropogenic processes. Then, we discuss mainly production, consumption and emission of CH4 in paddy fields. Finally, we provide an estimate of the mitigation potential in agricultural systems including rice production, ruminant animals and animal waste.
Measurement properties of tipping bucket rain gauges and their influence on urban runoff simulation
Authors: Fankhauser R.
Published: May 2018

Tipping bucket rain gauges (TBR) have become the most common device for measuring rainfall intensity in urban hydrology. Due to the measurement principle, the time resolution depends on rainfall intensity and bucket size. The present study investigated the influence of calibration uncertainties and bucket size on the accuracy of rainfall measurement and runoff simulation. Synthetic rainfall events with a time resolution of 6 seconds were generated from measured data. These rainfall series were taken as input to a model that simulated a TBR. Different TBR data series were produced by changing calibration parameters and bucket size of the simulated rain gauge. These data series together with the original rainfall events were used as input to a rainfall-runoff model. Computed runoff and overflow volume from a CSO weir were compared. The differences in rainfall depth, intensity peak and computed runoff due to the depth resolution of the TBR were smaller than expected. A depth resolution of the TBR of 0.2 - 0.3 mm per tip seems to fulfil the requirements in urban hydrology. Errors resulting from depth resolution are small compared to those of calibration (especially false rainfall depth per tip), site exposure, the influence of wind or disregarded areal rainfall distribution.
A novel approach to the real-time modelling of large urban drainage systems
Authors: Norreys Richard , Cluckie Ian
Published: May 2018

Conventional UDS models are mechanistic which though appropriate for design purposes are less well suited to real-time control because they are slow running, difficult to calibrate, difficult to re-calibrate in real time and have trouble handling noisy data. At Salford University a novel hybrid of dynamic and empirical modelling has been developed, to combine the speed of the empirical model with the ability to simulate complex and non-linear systems of the mechanistic/dynamic models. This paper details the ‘knowledge acquisition module’ software and how it has been applied to construct a model of a large urban drainage system. The paper goes on to detail how the model has been linked with real-time radar data inputs from the MARS c-band radar.
Total emission of an urban area considering the interaction between drainage system and treatment plant
Authors: Deyda Susanne
Published: May 2018

Continuous longterm calculations of quantity and quality processes on the catchment surface, the sewerage system and the treatment plant of the City of Hildesheim have to be carried out in order to estimate the effect of the urban area on the receiving water. The calculations are performed with a pollutant-load-calculation model including a coupled hydrologic-hydrodynamic runoff-transportation module. The achievement of the developed model is shown in the example of two different subcatchments of the City of Hildesheim. With the help of this concept, it is possible to consider the existing transport, storage and treatment capacity more flexible and to find optimal rehabilitation concepts concerning the emission loads just like the resulting costs.
Simpol: a simplified urban pollution modelling tool
Authors: Dempsey Paul , Eadon Andy , Morris Gerard
Published: May 2018

In the UK, the standards which protect river aquatic life against the effect of short term intermittent pollution events are expressed in terms of river concentration/duration thresholds for return periods ranging from 1 month to 1 year. To demonstrate compliance with these standards, it is necessary to simulate the performance of a drainage system and the river impact for a number of wet weather events, chosen such that the return periods of critical concentrations/durations can be estimated with confidence. Many events must be simulated leading to long computer runs and large result files when using detailed simulation models.

This paper describes how this problem has been addressed within the UK Urban Pollution Management procedure by developing a simplified urban pollution model called SIMPOL. This model is designed to represent the key urban processes in a relatively simple way. Accuracy is preserved by calibrating the model against a small number of detailed model results. As multiple runs can be carried out easily, SIMPOL modelling allows greater account to be taken of the variability in rainfall, river conditions and foul flow quality. Potential solutions can be rapidly tested against both environmental and emission standards. A case study is used to illustrate the application of SIMPOL.
Sediment transport over fixed deposited beds in sewers - An appraisal of existing models
Authors: Nalluri C. , El-Zaemey A. K. , Chan H. L.
Published: May 2018

An appraisal of the existing sediment transport equations was made using May et al (1989) and Ackers (1991) sediment transport equations for the limit of deposition design criterion and with a deposit depth of 1% of the pipe diameter allowed in the sewers. The applicability of those equations for sewers with larger fixed bed deposit depth was assessed, the equations generally over-estimated the transport velocity. Modifications were made to enable the equations to apply to sewers with large fixed bed deposits present.
Urban stormwater discharges: ecological effects on receiving waters and consequences for technical measures
Authors: Borchardt Dietrich , Sperling Frank
Published: May 2018

Effluents from combined and separated sewer systems cause discharges of water and pollutants to receiving waters, that can be critical for the integrity of these ecosystems. The nature of factors affecting aquatic life in running waters can be either physical (i.e. shear stress), chemical (i.e. oxygen deplition, non-ionized ammonia) or combined, dependent on local conditions. Over the last years, extensive studies signifiantly improved the knowledge on receiving water impact, whereas little effort was introduced to methods for the specific assessment of effects caused by urban stormwater discharges from particular catchments. Therefore, a working group of the German Association of Water Pollution Control (ATV) developed a systematic approach in order to identify critical combinations of urban stormwater catchments and receiving water properties. Based on meso-scale laboratory experiments, model calculations and analysis of field studies, a data base was generated in order to quantify the potential of both single and combined physical and chemical stress to aquatic life. The data base was proved to be sufficient to derive a scheme describing the ecological impact of urban stormwater discharges. For selected parameters, ‘critical thresholds’ were used to assess the relative importance of hydraulic and chemical factors being harmful for the ecological properties of receiving waters. These were linked with the effects of meaures and summarized in decision schemes.
Continuous quality control of measurements in a real time controlled sewer system in the municipality of Copenhagen
Authors: Hansen Morten Møller , Carstensen Jacob
Published: May 2018

Experience has shown that RTC systems are vulnerable to failures in the on-line monitoring system. It is therefore crucial to have a small and well functioning monitoring system than a larger monitoring system with many failures. This paper describes the results of a project with the aim of investigating the on-line monitoring system 4 years after put into operation. The outcome was a cut down in the number of on-line level transmitters and an automatic routine for detecting failures in the level transmitters. The routine has been programmed into the SCADA system and checks for 15 commonly occuring errors. Furthermore, an automatically generated report prints out statistics for larger rain events.
Waterborne adenovirus: a risk assessment
Authors: Crabtree K.D. , Gerba C.P. , Rose J.B. , Haas C.N.
Published: May 2018

Adenoviruses have been detected in raw sewage throughout the world and are associated with a number of human illnesses but their occurrence and pathogenicity have not been well studied. A risk assessment approach was used to determine their significance as a waterborne pathogen. There are 47 types of adenoviruses and the diseases resulting from infections include conjunctivitis, pharyngitis, pneumonia, acute and chronic appendicitis, exanthematous disease, bronchiolitis, acute respiratory disease, and gastroenteritis (types 40 and 41). Adenovirus is considered to be only second to rotavirus in terms of its significance as a pathogen of childhood gastroenteritis. Adenovirus infections are usually acute and self-limiting with a greater severity of illness occurring in the immunocompromised (e.g. AIDS patients and transplant recipients). They are reported to be more resistant to inactivation by UV than enteroviruses and are sometimes detected at higher levels in polluted waters. There are documented outbreaks of conjunctivitis due to adenovirus types 3 & 4 associated with swimming in contaminated recreational waters. Based on the data obtained from human dose-response studies, the exponential model [Pi = 1 -exp(-rN); r = 0.4172] was chosen for this risk assessment. Annual risks of infection in drinking water for adenovirus at average levels of 1/1,000L to 1/100L ranged from 8.3/10,000 to 8.3/1,000, respectively. Using monitoring data from a recreational water, risks were calculated to be as high as 1/1,000 for a single exposure.
Development of a risk assessment approach for evaluating wastewater reuse standards for agriculture
Authors: Shuval H. , Lampert Y. , Fattal B.
Published: May 2018

A risk assessment approach was developed to arrive at a comparative risk analysis of the various recommended wastewater irrigation microbial health guidelines for unrestricted irrigation of vegetables normally eaten uncooked. The guidelines compared are those of the WHO and the USEPA/USAID. The laboratory phase of the study determined the degree of contamination of vegetables irrigated by wastewater. Based on these estimates of the risk of ingesting pathogens, it is possible to estimate the risk of infection/disease based on the risk of infection and disease model developed for drinking water by Haas et al. (1993). For example, the annual risk of infectious hepatitis from regularly eating vegetables irrigated with raw wastewater is shown to be as high as 10−3. The study indicates that the annual risk of succumbing to a virus disease from regularly eating vegetables irrigated with effluent meeting WHO guidelines (1,000 FC/100mL) is negligible and of the order of 10−6 to 10−7 The risk of the more infectious, but less serious, rotavirus is 10−5 to 10−6. The USEPA considers an annual risk of 10−4 to be acceptable for microbial contamination of drinking water. The additional health benefit that might result from a further reduction of risk gained by adhering to the USEPA/USAID Reuse Guidelines (1992), which require no detectable faecal coliforms/100mL, appears to be insignificant in relation to the major additional costs associated with the expensive technology required to treat effluent to such a rigorous standard. Our preliminary estimates show that meeting the USEPA Guidelines would result in an extra expenditure of $3–30millions/case of disease prevented.
Microbiology of the space shuttle water system
Authors: Koenig D. W. , Pierson D. L.
Published: May 2018

The Space Shuttle has a once-through water system that is initially filled on the ground, partially drained before launch and then refilled with fuel-cell generated water on orbit. The microbiological standard for the Space Shuttle potable water system during this study period allowed only 1 microbe of any kind per 100mL and no detectable coliforms. Contamination episodes in more than 15 years of Shuttle operation have been rare; however, for the past 24 missions, bacterial contamination has been detected in 33% of the samples collected 3d before launch. These samples have had on average 55CFU/100mL of bacteria, with the median less than 1CFU/100mL. Burkholderia cepacia has been the primary contaminant of the Shuttle water supply system both before and after flight. Water samples assessed during the STS-70 mission aboard the Space Shuttle Discovery were found to be contaminated (<20CFU/100mL) with B. cepacia and B. pickettii. In 1991, waste and water lines were removed from the Space Shuttle Columbia and the waste lines were found to harbor biofilms containing Bacillus spp. Nevertheless, the water systems of the four Space Shuttle vehicles provide extremely pure water.