bluuebunny/crossref_metadata_2025 huggingface dataset:
Surfis: a tool for designing and optimizing dredging schemes
Authors: Fioole Aad , Houwing Erik-Jan , van der Heijdt Lambertus M.
Published: May 2018

Digital Terrain Models (DTM) can be useful tools for the design and evaluation of dredging operations. Nevertheless, DTM's based on linear interpolation of data from a rectangular grid do not provide confidence intervals for unsampled locations. SURFIS is a computer program to develop DTM's that include mapped random errors for complete study areas. Contrary to other geostatistical methods it can easily be applied by non-specialists. Application of SURFIS in the Biesbosch led to significant reduction in the amounts of material that needed to be dredged. We conclude that application of SURFIS may lead to more accurate dredging operations, resulting in lower costs for removal and storage of contaminated sediments.
An estimation of industrial mercury stored in sediments of a confined area of the lagoon of aveiro (Portugal)
Authors: Pereira M. E. , Duarte A. C. , Millward G. E. , Abreu S. N. , Vale C.
Published: May 2018

In the period from 1950 to 1994, most of the mercury discharged to the Lagoon of Aveiro was retained in the sediments of a small area of around 1.7 km2 (25.4 × 103 kg, about 77% of the total), which corresponds to the Estarreja Channel plus a basin named Laranjo Basin located downstream. In 1994, the mercury concentration in surface sediments of the area ranged from 2.3 to 343 μg g−1, with the highest values recorded near the industrial source of the metal. In places of the basin where the sedimentation rate could be considered uniform, the highest levels of Hg (35 μg g−1) were recorded at depths around 40 cm, as result of reduction of the anthropogenic mercury input to the lagoon. Assuming an uniform sedimentation rate and a continuously low industrial input of mercury for the near future, the levels of Hg in the surface sediments would be less than 1 μg g−1 in 20 years. This may be considered the expected restoration time. The feasibility and consequences of several management options for this pollution problems is briefly presented.
Physico chemical characteristics and multivariate analysis of contaminated harbour sediments
Authors: Ausili Antonella , Mecozzi Mauro , Gabellini Massimo , Ciuffa Giuseppina , Mellara Francesco
Published: May 2018

Dredging is a very important procedure within harbour management.

Italian legislation regulates dredging activity requiring high number of sampling stations and physico chemical and biological parameters but the criteria for their interpretation are not reported adequately. The comprehension of the information included in the data is a very critical step of every dredging activity of harbour sediments and the traditional examination of these large database (searching of average values of pollutants or simple correlations among pollutants) does not make easy their interpretation. So the included information can result hidden than clarified.

With the aim to perform a complete characterization of the examined area we applied Principal Components Analysis (PCA) and Cluster Analysis (CA) to the examination of a complex data matrix consisting of the physico chemical characterization (sediment texture, heavy metals, organic pollutants) of the industrial canal sediments in Livorno harbour. The multivariate methods allowed to study the general distribution of pollutants in the Livorno canal, clarifying also the significant parameters for the characterization of the system.
Field-portable X-ray fluorescence spectrometry for metals in marine sediments: results from multiple sites
Authors: Kirtay V. J. , Kellum J. H. , Apitz S. E.
Published: May 2018

The two goals of this study were to (i) test the capabilities of the portable instrument relative to detailed standard chemical analyses, and (ii) evaluate instrument response at multiple sediment sites. Results from FPXRF analyses of sediment samples from various locations have been compared with results from standard analyses (ICP, AAS, Laboratory XRF). The data are used to draw correlations between the different methods, and evaluate the universality of the instrument. The ability to reliably detect metals in sediments allows for the generation of data from sediment grabs in a time frame short enough to guide on site decision-making for mapping strategies and detailed sampling.
Distribution of soluble heavy metals between ionic and complexed forms in a saturated sediment as affected by pH and redox conditions
Authors: Patrick W. H. , Verloo M.
Published: May 2018

Research was undertaken to determine the effects of pH and redox potential on heavy metal speciation and on the size distribution of the organo-metal complexes in the soluble fraction of sediment-water systems. A cation exchange technique was effective in separating free and complexed metal ions. Fe, Mn and Zn differed in the extent of complexation with soluble organic matter. Under reducing conditions approximately two thirds of the soluble Fe was in a complexed form that was not sorbed in passing through the cation exchange resin. Soluble Mn on the other hand, was almost completely ionic under reducing conditions, with only a trace amount passing through the resin column. Over 90 percent of the soluble Zn was complexed under reduced conditions, with only 9 percent sorbed onto the resin. The complexed Fe and Zn were bound to soluble organic matter particles with equivalent molecular weight greater than 25,000 while Mn passed through this size filter. There were marked differences in the size distribution of the various organo-metal complexes under different redox and pH conditions. The soluble Fe was associated with both the largest and smallest size ranges of soluble organic matter. The effect of pH was most evident in the smallest size range with much more complexed iron being present at low pHs. Mn, on the other hand, was associated with only the smallest size range under all pH and redox conditions, reflecting its ionic nature. The greater solubility and mobility of Mn probably accounts for it being depleted relative to iron in Gulf Coast sediments. Hg and Pb were associated with only the largest size soluble complexes and were little affected by pH and redox conditions.
The use of flux-corer experiments in the determination of heavy metal re-distribution in and of potential leaching from the sediments
Authors: Van Ryssen R. , Alam M. , Goeyens L. , Baeyens W.
Published: May 2018

Metal dynamics between sediments, interstitial water and overlying water are particularly complex. The movement of metals, their availability, and possible toxicity are influenced by various chemical and physical reactions and factors such as oxygen/redox gradients, pH, grain size, etc. To study the impact of oxygen on the release from and the re-distribution of Cd, Pb, Zn and Cu in sediments, flux-corer experiments have been optimised and performed.

The flux experiment was carried out using 3 identical sediment cores. The first (control) sediment core was completely characterised before, the two other cores after the experiment. Pore water extractions and sequential extractions were performed on 2 cm depth intervals throughout the 20 cm long sediment cores.

In the flux experiment, the sediment cores were exposed to a small volume of overlying water, which was continuously renewed. The change of trace metal mobility was assessed by following concentration-changes in the outflow. It has been found by the use of the flux-corer experiment, that the Cd, Pb, Zn and Cu concentrations in the outflow are at least 3-6 times higher during oxic conditions. Flux-corer experiments can be useful tools to facilitate the study of the change of heavy metal mobility and distribution in the sediment induced by the change in surface water policy.
Design of a solvent extraction process for PAH-contaminated sediments: the wau-acetone process
Authors: Rulkens W. H. , Bruning H. , van Hasselt H. J. , Rienks J. , van Veen H. J. , Terlingen J. P. M.
Published: May 2018

Solvent extraction is one of the possibilities to clean-up polluted sediments. It is especially attractive when the sediment mainly consists of clay particles polluted with contaminants which are not, or not easily, biodegradable. Using acetone as extracting agent the extraction process has been investigated at laboratory scale for treating sediment of the Petroleum Harbour in Amsterdam. This sediment is characterised by a substantial percentage of particles with diameter <63 μm, a high percentage of organic matter (about 12% on dry matter basis), a high concentration of PAH (500-2,000 mg total EPA-PAH per kg dry matter) and a high concentration of mineral oil (6,000–10,000 mg/kg dry matter). Based on the laboratory scale experiments a process design has been made of a complete solvent-extraction process with acetone. The main process steps in this design consist of a countercurrent flow extractor, a separator for the sediment, a post-treatment step to remove residual acetone from the sediment, a distillation column to recover the acetone for reuse and to concentrate the pollutants and a polishing step for the water to be discharged. The sediment treatment costs with this system are estimated at 115 NGL per tonne dry matter to be treated.
Monitoring environmental effects in the slufter, a disposal site for contaminated sludge
Authors: Nijssen J. P. J. , Zwakhals J. W. , Ammerlaan R. A. , Berger G. W.
Published: May 2018

The Slufter, a disposal site for dredging sludge in Rotterdam, was put into use in 1987. The impacts of constructing and operating the Slufter were predicted in an environmental impact assessment study (EIA). Since 1987, the principal processes on the site (compaction, diagenesis and gas formation) and in the dike encircling the site (formation of freshwater reservoirs) have been monitored by means of measurements. Measurements are also used to monitor emissions of pollution. Some of these measurements are taken using instruments specially developed for this purpose. The results gathered show that the EIA predictions for the processes closely approximate the present situation. No emission of pollution from the site has been measured.
Streamlining contaminated sediment management: the use of advanced sediment characterization — preliminary results
Authors: Apitz Sabine E.
Published: May 2018

Simply knowing the geographic extent of sediment contamination within a bay or estuary does not provide sufficient insight to help a site manager or stakeholder begin to assess how to manage sediments deemed either an ecological risk or regulatory violation. A better approach is to assess contaminant distribution and behavior at a micro-scale in parallel with macro-scale site assessments. In such an approach, a site investigation includes an assessment of contaminant/sediment biogeochemistry, as it will impact bioavailability, risk, and potential management options. This paper reviews some approaches for assessing contaminant bioavailability, distribution and degradability, and presents preliminary results from some biogeochemical sediment assays. Some of the potential uses and limitations of such assays are discussed. Selective leaches, using alcohol or digestive juices to determine bioavailable contaminant fractions still require some validation. Assessments of contaminant distribution as a function of grain size can lend insight into both contaminant mobility and management strategies. Biodegradation studies in real sediments are complicated by analytical and heterogeneity difficulties, but can, if carried out carefully, provide useful information.
Control of activated sludge bulking by operating clarifiers in a series
Authors: Kim Youngchul , Pipes Wesley O. , Chung Paul-Gene
Published: May 2018

A full scale experiment with an activated sludge process in a pharmaceutical manufacturing plant showed that the operation of two settling tanks in series, with the first tank full of sludge, resulted in selection of sludge particles which had a lower than average filament content for retention in the process. Series operation of the two clarifiers was very successful in controlling sludge bulking. The functioning of the settling tanks as selectors of sludge particles which settle and thicken well has not been considered to any great extent. Two laboratory-scale activated sludge plants fed with an artificial wastewater were operated to explore this selection function further. The SVI values were measured and assessed. At the start of operation, the SVI was about 60–80 ml/g in both of the parallel and the series plants. After eight days of the operation, the SVI started to increase rapidly in the parallel plant, and in twenty days of operation, the averaged values of SVI were 163 ml/g and 116 ml/g for the parallel and the series plants, respectively. On day 38, MLSS from two aeration tanks were interchanged. In a few days after that interchange, the SVI values in the parallel, which was originally in the series mode, rapidly increased from 130 ml/g to more than 350 ml/g(SV30 = 930 ml/g). This experiment clearly supports the hypothesis of a microorganism selection function of the settling tank and also corresponds to the results obtained from the field study.
Bulking sludge prevention by an aerobic selector
Authors: Prendl L. , Kroiß H.
Published: May 2018

Activated sludge bulking caused by the filamentous bacteria 021N, was repeatedly detected in the mixed liquor of a beet sugar mill treatment plant, equipped with an aerated selector. The organic pollution of the waste water consisted of about 70% easily degradable dissolved substrate (sugar, fatty acids). Only in cases when the elimination of the readily biodegradable substrate from the liquid phase in the selector was incomplete a rapid increase of filamentous bacteria could be detected consistently. The readily biodegradable substrate is predominantly removed in the selector by uptake and storage by the biomass. The oxygen demand for the storage in the selector depends on the kind of substrate. To obtain storage capacity in the selector, the sludge must have the opportunity to regenerate the capacity for substrate storage in the aeration tank. In the case of overloading and/or oxygen and/or nutrient deficiency the storage capacity can not be regenerated and the aerobic selector loses its effectiveness. From the findings about the factors influencing the elimination of the readily degradable substrate in the selector, a simple calculation method for dimensioning of aerobic selectors as well as a simulation model have been developed. In two plants, (60,000 m3/d, 40 t COD/d) that were built according to these findings it could be verified that the growth of 021N can be avoided effectively by using aerobic selectors, dimensioned with the developed calculation method. The results could be proved by successful operation of the treatment plants during the last two years. In a paper mill plant the SVI reaches values of 300 to 600 ml/g caused by the filamentous bacteria Type 0041 and Type 1701. Some days after installing an “adequate aerobic selector system” the growth of filamentous bacteria could be suppressed and the SVI reached values of 60 to 90 ml/g.
Improving activated sludge floc structure and aggregation for enhanced settling and thickening performances
Authors: Clauss F. , Helaine D. , Balavoine C. , Bidault A.
Published: May 2018

The effluent quality of a sewage plant using the activated sludge process depends upon the flocculation efficiency. Intensive research work has been devoted to understanding flocculation phenomena and to correct biological disorders. The addition of very fine but dense mineral particles to the aeration tank immediately improves floc formation and increases the weight of the new flocs created. The first consequence is an effective separation between the solid and the liquid phases in the secondary clarifier. In the longer term, the fine particles improve floc structuring and form stable and strong flocs. This has been demonstrated by sending a modified activated sludge through the high shear strength of pumps and hydrocyclones. The mineral of choice is a natural blend of talc and related minerals. These fine talc particles offer a solution to solve floc settleability problems which so frequently arise when biological disorders appear in waste water treatment plants. Despite the addition of insoluble particles the amount of sludge expelled does not increase. The thickening and dewatering properties are improved.
Characterisation of efficient denitrifying bacteria strains isolated from activated sludge by 16S-rDNA analysis
Authors: Magnusson Gunnar , Edin Helena , Dalhammar Gunnel
Published: May 2018

In order to investigate the diversity of the most efficient denitrifying bacterial species in activated sludge more than 1500 bacterial strains were isolated from five different municipal wastewater treatment plants. The 24 most efficient denitrifying bacteria strains were selected and submitted for partial 16S rRNA analyses. Result indicated that five strains were members of the Rhodobacter group, 16 of Rubrivivax subgroup, one of Pseudomonas subgroup and two unidentified though showing high similarity to certain members of the Brucella assemblage. This indicates efficient denitrifying bacterial strains in activated sludge are members of a restricted number of bacterial taxa dominated by Rubrivivax subgroup.
Comparison of carbon storage under aerobic and anoxic conditions
Authors: Majone M. , Massanisso P. , Ramadori R.
Published: May 2018

In various activated sludge systems, the biomass grows under transient (unbalanced) conditions and the storage response (formation of internal polymers as the fastest adaptation to the changing environment) becomes important. Till now the role of storage on population dynamics has been deeply investigated under anaerobic (EBPR processes) or aerobic (bulking control) conditions. Little attention has been given to processes including anoxic conditions even though in many of them storage phenomena are likely to occur (anoxic selectors, nitrogen removal processes with addition of an external source of readily biodegradable COD or with aerobic contact/anoxic stabilization). For these reasons, the aim of the present work was to investigate storage and succeeding use of stored products under anoxic and mixed (anoxic/aerobic) conditions. Batch experiments have shown that a mixed culture selected under aerobic conditions and intermittent feed (acetate-limited medium), was also able to take up acetate (90–100 mgCOD/gCOD h) and store it as PHB (35–40 mgCOD/gCOD h) under anoxic conditions. After acetate depletion, the stored PHB was used for growth and maintenance. The NUR on acetate in the presence of storage was 20 mgN/gVSS h (which corresponded to a COD removal of 6.9 mgCOD/mgN) while it dropped to 10–3 mgN/gVSS h in the “endogenous phase” when denitrification was on the stored PHB. The presence of aerobic conditions instead of anoxic ones had a major positive effect on the rate and yield of PHB storage while it had only a minor effect on the rate of PHB consumption. The latter observation can be explained by assuming that the hydrolysis of the stored product is the rate limiting step of the “endogenous” metabolism and that the hydrolysis rate is not highly dependent on aerobic-anoxic conditions. Cross-comparison of PHB storage and consumption under aerobic/anoxic conditions made it possible to determine that, in the particular mixed culture under investigation, all aerobic heterotrophs able to store were also able to denitrify.
A new method for the assessment of heterotrophic endogenous respiration rate under aerobic and anoxic conditions
Authors: Avcioglu E. , Orhon D. , So¨zen S.
Published: May 2018

In this paper, the current practice for the assessment of aerobic endogenous decay rate has been critically evaluated and a new method has been proposed for the experimental determination of heterotrophic endogenous respiration rate under aerobic and anoxic conditions. The suggested method is tested on activated sludge samples grown on domestic sewage yielding bH values markedly lower than the reported results. Further experimental data are needed to support the results of this study.
Association of a UASB reactor and a submerged aerated biofilter for domestic sewage treatment
Authors: Gonçalves Ricardo Franci , de Araújo Vera Lúcia , Chernicharo Carlos Augusto L.
Published: May 2018

This paper presents exploratory results on the association of an Upflow Anaerobic Sludge Blanket - UASB reactor (46 L) and a submerged aerated biofilter – BF (6.3 L) for domestic sewage treatment. The experimental period extended for 322 days, during which the hydraulic and organic loads were gradually increased in both reactors. Having the UASB as a reference, the following hydraulic loads were tested: 0.4 m3/m2.h (θ = 16 h); 0.6m3/m2.h (θ = 10h); 0.8 m3/m2.h (θ = 8 h); 1.0 m3/m2.h (θ = 6 h) and 1.45 m3/m2.h (θ = 4h). During the experiments carried out with the UASB reactor operating at a hydraulic detention time of 6 hours, related to a θ < 11′ in the granular media of the BF, the mean removal efficiency in terms of SS, BOD5 and COD, in both reactors, were respectively 94%, 96% and 91%. The final effluent, related to the BF effluent, presented the following mean characteristics: SS = 10 mg/L, BOD5 = 9 mg/L and COD = 38 mg/L. The results obtained in the last phase of the experiments, when the hydraulic load in the UASB reactor reached 1.45 m3/m2.h (θ = 4h), were similar to those obtained in the previous phase. These results demonstrate that submerged aerated biofilters can be considered a viable alternative for the post-treatment of effluents from UASB reactors treating domestic sewage. These reactors are capable of being operated with very short hydraulic detention times.
Analysis of organic removal rates in the aerated submerged fixed film process
Authors: Hamoda Mohamed F. , Al-Ghusain Ibrahim A.
Published: May 2018

Performance data from a pilot-plant employing the four-stage aerated submerged fixed film (ASFF) process treating domestic wastewater were analyzed to examine the organic removal rates. The process has shown high BOD removal efficiencies (> 90%) over a wide range of hydraulic loading rates (0.04 to 0.68 m3/m2·d). It could also cope with high hydraulic and organic loadings with minimal loss in efficiency due to the large amount of immobilized biomass attained. The organic (BOD and COD) removal rate was influenced by the hydraulic loadings applied, but organic removal rates of up to 104 kg BOD/ m2·d were obtained at a hydraulic loading rate of 0.68 m3/m2·d. A Semi-empirical model for the bio-oxidation of organics in the ASFF process has been formulated and rate constants were calculated based on statistical analysis of pilot-plant data. The relationships obtained are very useful for analyzing the design and performance of the ASFF process and a variety of attached growth processes.
Hydrodynamic behaviour of a full-scale submerged biofilter and its possible influence on performances
Authors: Séguret F. , Racault Y.
Published: May 2018

The hydrodynamic behaviour of a 110 m2 full-scale submerged upflow biofilter, filled with 2.8 m of floating media and used for tertiary nitrification of treated domestic sewage was investigated. Residence time distributions were obtained from lithium chloride tracer experiments. Four trials were performed at 3.7 and 6.5–6.7 mh−1, once without aeration. Spatial differences in the mean residence time of a given cross-section were in the range of 30–40% and can be attributed to the distribution system of the influent at the bottom of the filter. Sampling at the bottom and top of the filter bed media showed that the behaviour of the filter bed itself is close to a dispersed plug flow reactor. The dispersion lengths are in the range 60–100 mm, increase with flow rate and are unaffected by the aeration. From simple model calculations, it was concluded that the heterogeneity observed within the filter bed would have no significant effect on water quality. Heterogeneity due to the distribution of effluent in the lower part of the filter would also have a very limited effect in the case of sudden changes in the effluent substrate concentration.
Environmental management of coastal cooling water discharges in Hong Kong
Authors: Ma S. W. Y. , Kueh C. S. W. , Chiu G. W. L. , Wild S. R. , Yip J. Y.
Published: May 2018

Seawater cooling systems are an essential feature of Hong Kong's large public, institutional, commercial and industrial complexes. Over 25 million cubic metres of seawater are used for cooling purpose everyday. Biofouling, scaling and corrosion are common operational problems encountered. These are generally combatted through the use of chemicals such as chlorine and other antifouling/anticorrosion chemicals which are toxic to marine organisms and potentially harmful to the environment. Due to the continuous daily discharge of large amounts of cooling seawater everyday, significant quantities of heat is dissipated and potentially toxic chemicals are released to the coastal environment. A comprehensive survey of the cooling water system operations in Hong Kong was commissioned by the Hong Kong Environmental Protection Department in 1996. The survey results indicate that some 93 major cooling water systems are currently operating in the territory, about 80% of which are located around Victoria Harbour. The majority of the cooling water systems are the once-through type, causing a temperature rise of 3–5°C above ambient at discharge points. Cooling water discharges from large power plants, on the other hand, may have a discharge temperature increase of 8–10°C above the ambient which is close to the upper thermal tolerance limit of most marine biota. Chlorine and amine-/surfactant-based biocides are the most commonly used antifouling/anticorrosion chemicals. An estimated 11,000 tonnes of chlorine are released into the marine environment of Hong Kong each year by the cooling systems. Chlorine and its reactive by-products are known to be toxic to marine life even at very low concentrations. Despite the large dilution capacity of seawater, chlorinated discharges may cause adverse ecological impacts, particularly in the vicinity of large cooling water outfalls. Sound management of Hong Kong's cooling systems is necessary to allow efficient use of seawater for cooling, while minimizing its adverse environmental impact. Such management practices include improved cooling system design, effective operation and maintenance for biofouling control. Overdosing of toxic chemicals should be avoided and there is a need to regularly monitor the effluents to ensure compliance with discharge standards.
Monitoring of fouling and biofouling in technical systems
Authors: Flemming Hans-Curt , Tamachkiarowa Adriana , Klahre Joachim , Schmitt Jürgen
Published: May 2018

Biofouling is a problem in many different industrial fields, causing damage of product or interfering with production processes, ranging from drinking and purified water systems to paper manufacture, heat exchange or cosmetics, pharmaceutical, medical and electronic device industries. Timely countermeasures, optimization and efficacy control depend on monitoring of biofilm growth on surfaces. As water samples give no information about site and extent of biofilms, surface sampling is mandatory. The information about biofilm development should be recorded on line, in real time and non destructively in order to permit the kinetics of deposition or removal to be followed. Three physical methods are presented here: i) a fiber optical device, ii) a differential turbidity measurement device, and iii) an FTIR flow cell. The first two methods are based on light reflectance and detect the deposition of reflecting material. Thus, they are not specific for biofilms but they allow us to detect deposit formation in situ, non destructively and in real time. The third method gives information about the chemical nature of the deposit, allowing us to identify biological material. However, this increase of information requires a significantly higher technical effort.
Kinetics and fundamental mechanisms of starch removal by activated sludge: hydrolysis of starch to maltose and maltotriose is the rate-determining step
Authors: Ubukata Y.
Published: May 2018

The mechanisms of hydrolysis and uptake of starch, a polymer in sewage, by activated sludge (AS) were investigated, taking into consideration the mechanisms of the maltose transport system, responsible for the uptake of hydrolysis products of starch, in Gram-negative bacteria. AS was acclimated to dextrin, and the molecular weight distributions of the substrates during dextrin removal are analyzed using a GPC method. The removal rates of substrates such as dextrin, various maltodextrins (maltotriose, etc.), maltose and glucose by AS, and the oxygen uptake rates (OURs) of AS during the removal of these substrates were compared. Low-molecular-weight saccharides such as glucose, maltose and maltotriose were undetectable in the substrates during dextrin removal. The removal rates of maltose and maltotriose were higher than those of dextrin and glucose, and the OURs of AS during the removal of maltose and maltotriose were higher than those for other substrates. Therefore, hydrolysis of starch to maltose (dimer) and maltotriose (trimer), and not to glucose (monomer), appears to be the rate-determining step during the removal of starch, although maltodextrins with molecular weights up to 1152 (maltoheptaose) appear to penetrate the bacterial outer membrane.
Development of a two phase anaerobic digester for the treatment of mixed abattoir wastes
Authors: Banks C. J. , Wang Z.
Published: May 2018

A two phase anaerobic digestion system was developed for the treatment of mixed abattoir wastes composed of mixtures of cattle blood and cattle gut fill (rumen paunch contents). The reactor system, and its mode of operation, overcame the problems associated with a single pass anaerobic digestion process by alleviating toxicity problems associated with the accumulation of volatile fermentation intermediates and high ammonia concentrations. The principle of operation of the two phase system was to separate the hydrolysis reactions from those of methanogenesis and, by introducing a hydraulic flush regime, to prevent accumulation of intermediate products in the first phase of the process. The hydraulic flush operates in such a manner whereby the liquid retention time in the first reactor was significantly shorter than the solids retention of the fibrous components of the feedstock. The first phase reactor was run in this mode using solids retention times of 5, 10, 15, 20 and 30 days with a liquid retention time of 2 days. Up to 87% solids reductions were achieved compared to a maximum 50% when control reactors were operated in a single pass mode with solids and liquid retention times of equal duration. The performance of the first phase hydrolysis reactor was also monitored in terms of volatile fatty acid production, COD removal efficiency and ammonia accumulation potential. The liquefied effluent from the hydraulic flush reactor was found to be a suitable substrate for a second phase high rate methanogenic reactor operated over a range of retention times of between 2 - 10 days; this gave equivalent process loadings of 1.4 - 7.0 kg COD/m3/day. Methane conversion efficiencies of around 0.3 m3 CH4/kg COD removed were achieved. By use of the two phase system it was possible to operate at a loading to the first phase of 7.22 kgTS/m3/day with a resultant effluent from the second phase with a COD of 4270 mgl−1. The overall performance of the system showed a process loading of 3.6 kgTS/m3/day was achievable with a methane production rate of 0.27 m3CH4/kgTS added and 63% TS destruction. The results suggest that further optimisation of the two phases might further improve this overall performance.
Temperature and pH control in composting of coffee and agricultural wastes
Authors: Nogueira W. A. , Nogueira F. N. , Devens D. C.
Published: May 2018

One of the by-products of instant coffee production is a solid waste with high organic content. This waste is disposed of either by landfill sites or by burning as fuel. Both alternatives are considered economically and environmentally unsatisfactory due to the physico-chemical characteristics of the waste. This study investigates the applicability of the forced aeration composting process to a mixture of this coffee waste and agricultural wastes. Approximately 40 tons of waste was used to set up the static piles. Temperature was used as the main parameter to enable control of the aeration rate. Other parameters used to monitor the process were humidity, pH and carbon/nitrogen ratio. The results obtained were satisfactory and the experiments lead to the production of a high quality compost presenting a carbon/nitrogen ratio of the order of 131 to 151.
Characterization of textile wastewater and other industrial wastewaters by respirometric and titration biosensors
Authors: Rozzi A. , Ficara E. , Cellamare C. M. , Bortone G.
Published: May 2018

Many industrial effluents, such as textile and tannery wastewater, contain slowly biodegradable, refractory or even toxic compounds at variable concentrations which may interfere with the efficient operation of biological wastewater treatment plants, in particular with the nitrification stage. Agro-industrial effluents may occasionally contain sanitising agents which are by definition biocides. Two different biosensors, based on respirometry (oxygen uptake rate, OUR measurements) and on basic titration respectively, were used to measure degradation rates of industrial wastewater samples by autotrophic bacteria (ammonia oxidizers). Specific sanitisers such as sodium hypochlorite and benzalconium chloride were used to evaluate and compare the nitrifying activity measured by the two different instruments.
Anaerobic treatment of split flow wastewater and concentrates from the textile processing industry
Authors: Minke R. , Rott U.
Published: May 2018

Under anaerobic conditions an almost complete decolorization of many dyes, an efficient COD-removal and a digestion of substances that are refractory under aerobic conditions can be obtained. Therefore anaerobic processes can be used to treat highly loaded split flows and concentrates from the textile processing industry (TPI). Using a large number of biodegradability tests on a bench scale, different types of commercial textile auxiliaries, dyes, real split flow effluents from desizing and dyeing processes and real residual printing pastes were tested in regard to their anaerobic biodegradability. Investigations with anaerobic fixed bed reactors (AFBR) showed that it is possible to treat effluents containing a high organic load from desizing processes and highly coloured effluents from exhaust dyeing processes together resulting in high COD-removal and nearly complete decolorization. With respect to the further aerobic removal of the remaining organic load of the AFBR's effluents it could be seen that the decrease of COD-elimination in AFBR resulting from high portions of effluents from exhaust dyeing processes and short hydraulic retention times is compensated by an increase in aerobic BOD-elimination.
Sugar wastewater treatment with aerated fixed-film biological systems
Authors: Hamoda Mohamed F. , Al-Sharekh Hamed A.
Published: May 2018

Wastewater effluents from the sugar industry contain high concentrations of organic materials which are sometimes discharged into the municipal wastewater collection system and processed in wastewater treatment plants along with domestic wastewater. This study examined the performance of a four-compartment, fixed-film system in which the biofilm is attached to submerged ceramic tiles under diffused aeration, known as the aerated submerged fixed-film (ASFF) process. Field experiments were conducted using four ASFF units each of about 100 1 capacity operated at different hydraulic loading rates to provide hydraulic residence time (HRT) of 2, 4, 6 and 8 hours. Process performance was evaluated under both normal operation with domestic wastewater and under pulse and prolonged organic shock loads with sugar wastewater. The influent and effluent of the process was analyzed for solids, BOD, COD, and nitrogen forms to determine both carbonaceous and nitrogenous substrate removal. The ASFF process was found to be able to handle continuous severe organic loads increasing from about 5 to 120 g BOD/m2.d with slight decrease in organic removal efficiency from 97.9% to 88.5% for BOD and from 73.6 to 67.8% for COD. Nitrification was similarly decreased but at higher rates. The system was also able to cope with pulse injection of sugar wastewater and recovery to normal steady-state COD values was achieved in 10 hours for the 200 g COD/l spikes. An increase in the organic loading rate was accompanied by an increase in biofilm specific oxygen uptake rate until reaching a maximum which determines the optimum loading rate for process operation. Substrate removal rates were evaluated for process design.
Interactive toxic effects of agrochemicals on aquatic organisms
Authors: Kungolos A. , Samaras P. , Kipopoulou A. M. , Zoumboulis A. , Sakellaropoulos G. P.
Published: May 2018

The effects of three common agrochemicals, lindane, methyl parathion and atrazine, on crustacean Daphnia magna, alga Selenastrum capricornutum and marine bacterium Vibrio fischeri were investigated in this study. Methyl parathion was the most toxic compound towards all three organisms, while lindane was more toxic to Daphnia magna and Vibrio fischeri than atrazine, and atrazine was more toxic to Selenastrum capricornutum than lindane. Among the three aquatic organisms, Selenastrum capricornutum was most sensitive in detecting lindane and atrazine toxicity, while Daphnia magna was most sensitive in detecting methyl parathion toxicity. The interactive effects of the pesticides were also investigated. The interactive effect between lindane and methyl parathion on survival of Daphnia magna was synergistic, while the ones between lindane and atrazine and between methyl parathion and atrazine were generally additive. The interactive effect of the three pesticides applied together on Daphnia magna was synergistic. The interactive effect of the three pesticides on the growth of Selenastrum capricornutum was antagonistic with few cases of addition, while the effect of all the three pairs of pesticides on algal growth was also antagonistic. The interactive effect of lindane and methyl parathion on Vibrio fischeri was additive.
Effluent nutrient management and resource recovery in intensive rural industries for the protection of natural waters
Authors: Biswas T. K. , Higginson F. R. , Shannon I.
Published: May 2018

Intensive rural industry is developing rapidly in parts of inland Australia. The usually nutrient and salt rich effluent from these sources has traditionally been disposed to both land and water bodies. Since direct water discharge is no longer permitted, a challenge now exists when applying effluent to land especially where the rate of application exceeds crop requirements. Effluent of high volume and concentration of nutrients and/or salts can easily contaminate land and water resources. Predicting the optimum rate of land application of effluent is complicated by the physical, chemical and biological properties of soils.

This paper addresses the characteristics of effluents from various intensive rural industries and their potential environmental impacts when irrigated to agricultural land in New South Wales, Australia. To assess the environmental sustainability of effluent reuse in land application, a mathematical model (ERIM) has been developed based on a monthly water balance. ERIM includes historical rainfall and evaporation; the amount of nitrogen and phosphorus introduced; their yearly removal by plants to be grown; amount of applied organic matter; and water holding capacity of soil.
The effects of wastewater irrigation on groundwater quality in Mexico
Authors: Gallegos E. , Warren A. , Robles E. , Campoy E. , Calderon A. , Sainz Ma. G. , Bonilla P. , Escolero O.
Published: May 2018

The main aim of this research was to determine the environmental effects of wastewater irrigation on the subsurface at two locations in Mexico; Leon and the Mezquital Valley. Freshly-drilled subsurface sediment samples (both sites) and groundwater samples (Mezquital Valley) were taken at various depths. These were analysed for a range of physico-chemical and microbiological parameters using standard methods. Elevated concentrations of faecal and total coliforms were recorded at both sites indicating that faecal bacteria had been transported through the subsurface. The level of subsurface contamination was affected by both spatial and temporal factors with higher coliform concentrations occurring at shallower depths (<10 m below the surface) and at the top of the water table, and during the wet season. Elevated nitrate concentrations were found in all of the Mezquital Valley groundwaters. Thus, wastewater irrigation appears to have had a negative impact on groundwater quality. In order to mitigate this, treatment of wastewater prior to irrigation and careful irrigation management is recommended. The potential effects of groundwater degradation on public health, and the need for guidelines to protect groundwater quality, are discussed.
Stormwater and lamella settlers: efficiency and reality
Authors: Daligault A. , Meaudre D. , Arnault D. , Duc V. , Bardin N. , Aires N. , Biau D. , Schmid J. , Clement P. , Viau J.-Y.
Published: May 2018

Two settling devices treating rainwater from urban drainage areas and equipped with secondary sludge treatment were monitored over a period exceeding one year. The two devices differ in their design and in the quantity and quality of effluents received. Full analyses over approximately 30 mean samples of the intake and discharge effluents allowed judgment of the mean efficiency of pollution control and the reduction in impact of the storm water. The observed settlement was compared to measurements of settling velocity during several rainfalls. From analyses of the settled or extracted sludge it was possible to characterize the pollutants retained in the sludge. Particular attention was paid to the functioning and operation of the devices.
The requirement of metal cations for enhanced biological phosphorus removal by activated sludge
Authors: Pattarkine Vikram M. , Randall Clifford W.
Published: May 2018

The objectives of the study described in this paper were to study the requirements of potassium, magnesium, and calcium for enhanced biological phosphorus removal (EBPR) and to determine whether either potassium or magnesium could support EBPR on its own.

Batch experiments indicated that phosphorus uptake by the sludge was affected by the availability of potassium, magnesium, and calcium. Both potassium and magnesium were simultaneously required and neither was adequate by itself for EBPR. Calcium did not appear to be required for EBPR, and did not seem to be involved in biologically mediated chemical precipitation.
The impact of intentional stormwater infiltration on soil and groundwater
Authors: Barraud S. , Gautier A. , Bardin J. P. , Riou V.
Published: May 2018

Stormwater infiltration is a principle which is more and more utilized on urban sites in France. However, given the characteristics of urban surfaces, and notably the amounts of the different pollutants that stormwater is likely to contain, it is important to try to assess the impact of intentional stormwater infiltration systems on the soil, and on groundwater. To try to answer that type of question, we present an experiment that was carried out in Valence (France) on two infiltration facilities. Situated in the same street, and serving equivalent catchment areas (i.e. a road network, along with a “classical” urban type of habitat), the first one is a recent cylindrical soakaway (1994) and the second one is a rectangular chamber which is around thirty years old. After explaining the experimental protocol, we shall present a body of data that we monitored. We shall then present our conclusions concerning the role of the soil and the groundwater in the process of “clearing up” the different pollutants that are present in stormwater, as well as the migration patterns of these pollutants.
Pollution retention capabilities of roadside soils
Authors: Dierkes C. , Geiger W. F.
Published: May 2018

Runoff from highways contains significant loads of heavy metals and hydrocarbons. According to German regulations, it should be infiltrated over embankments to support groundwater-recharge. To investigate the decontaminating effect of greened embankments, soil-monoliths from highways with high traffic densities were taken. Soils were analyzed to characterize the contamination in relation to distance and depth for lead, zinc, copper, cadmium, PAH and MOTH. Lysimeters were charged in the field and laboratory with highway runoff to study the effluents under defined conditions.

Concentrations of pollutants in roadside soils depend on the age of embankments and traffic density. Highest concentrations were found in the upper 5 cm of the soil and within a distance of up to two metres from the street. Concentrations of most pollutants decreased rapidly with depth and distance. Lead and cadmium could not be detected in lysimeter effluent. Zinc and copper were found in concentrations that did not exceed drinking water quality limits.
Aerobic microbial transformations of pipe and silt trap sediments from combined sewers
Authors: Vollertsen Jes , Hvitved-Jacobsen Thorkild , McGregor Iain , Ashley Richard
Published: May 2018

Organic matter in sediments from pipes and silt traps in combined sewers was divided into fractions with different settling velocities. Biodegradability of organic matter for these fractions was characterised based on results from a conceptual model of aerobic transformations of resuspended sediments calibrated on oxygen utilisation rates. Pipe sediments as well as silt trap sediments were investigated and no differences between these deposits were detected. It was found that the largest fraction of organic matter is associated with material which settles relatively fast and only a small part is associated with relatively slow settling material. However, the fast settling organic matter was found to be rather slowly biodegradable compared to the slow settling organic fraction. Because the biodegradability of the organic matter discharged during combined sewer overflow (CSO) events is of significant importance to the impact on the dissolved oxygen concentrations in receiving waters, the biodegradability of sewer sediments is argued to be taken into account for detailed characterisation when dealing with CSO impacts.
Constructed Wetlands: A Chance to Solve Wastewater Problems in Developing Countries
Authors: Haberl R.
Published: May 2018

There is a great lack of proper wastewater treatment in developing countries. With respect to the environment this situation should be changed as fast as possible. Due to the financial situation and to the more stringent standards, wastewater sewerage and treatment are much more developed in industrialized countries. Consequently there is an enormous pool of experience and knowledge in these countries with a lot of different systems based on scientific and practical work.

One of the most promising technologies for application in developing countries seems to be constructed wetlands (CW), due to their characteristic properties like utilization of natural processes, simple construction, simple operation and maintenance (O/M), process stability, cost effectiveness, etc.

Our Institute has been dealing a lot with CW and now feels obliged to transfer its know-how in this field to developing countries to help them in solving their problems. At the moment we are cooperating with the following countries: China, Kenya, Mexico, Nepal, Nicaragua, Tanzania and Uganda. Different ways are being followed to realize this together with several organisations and partners.

The paper will deal with these cooperative arrangements in detail, demonstrating different projects, describing the procedures in the projects, discussing experiences and last but not least giving recommendations for future optimum ways of proceeding.