bluuebunny/crossref_metadata_2025 huggingface dataset:
Batch test procedures as tools for calibration of the activated sludge model - a pilot scale demonstration
Authors: Kristensen Gert Holm , Jansen Jes la Cour , Jørgensen Per Elberg
Published: May 2018

Various mathematical models have been developed to facilitate the design and operation of biological nutrient removal plants. Proper calibration of such models can be a difficult task due to the large number of variable process coefficients. The paper describes a strategy for model calibration based on batch characterizations of wastewater and activated sludge biomass and demonstrates its applicability through modelling of the process dynamics in a highly dynamic activated sludge pilot plant. A comprehensive experimental programme was undertaken comprising batch characterizations of readily degradable and easily hydrolysable COD in influent wastewater, maximum and endogenous process rates for functional microorganism groups in the activated sludge, and half-saturation process constants to describe the impact of oxygen on nitrification and denitrification. An on-line measurement of ammonia and nitrate and nitrite using a Flow Injection Analysis System was conducted for two consecutive days to study the process dynamics in a BioDenitro pilot plant for two parallel activated sludge process tanks. It was possible to closely mimic the dynamics of the nitrogen removal processes in the two tanks based on the model calibration strategy using wastewater and biomass characteristics determined in batch experiments.
Modeling the activated sludge floc microenvironment
Authors: Scuras Sean , Daigger Glen T. , Grady C. P. Leslie
Published: May 2018

Integrated modeling of activated sludge systems will only be complete when settling characteristics can be determined within the model. These characteristics are fundamentally related to the size, shape and porosity of both the sludge flocs and their component microcolonies. Microcolony porosity is of particular interest since it may both influence, and be influenced by, the substrate and electron acceptor gradients that establish competitive microenvironments. A model was developed to explore the relationship between biomass growth, death, and hydrolysis; soluble component diffusion and microcolony porosity. A key element of the model is the assumed distribution of daughter cells following replication. Preliminary results indicate rapid progression toward minimum porosity with relatively slow expansion of the microcolony surface. Although little is documented on porosity variation within flocs, these results contrast with observations for biofilms and may emphasize the difference between the mechanisms involved in the structural development of microcolonies and larger scale aggregates.
Demulsification of oily wastewater through a synergistic effect of ozone and salt
Authors: Song Young-Chae , Kim In-Soo , Koh Sung-Cheol
Published: May 2018

Emulsion wastewater is one of the important industrial wastewaters, which is resulting from the various manufacturing industries including the metal manufacturing and its processing. Wastewater treatment technologies utilizing flocculation and electrolysis have been used but these technologies have not been very helpful in resolving the problems in view of process consistency and economic merit. Selection of appropriate electrolytes and rapid separation techniques of the demulsified oil will be important factors to be considered for development of an efficient treatment system. The objective of this study was to investigate the roles of salt and ozone in the treatment of the emulsion wastewater by examining the effects of salt concentration, ozone intensity, pH, and emulsion concentration on the demulsification reaction. A synergistic effect of salt and ozone treatment on the demulsification was observed, where the demulsification efficiency was at least 40% higher than the only salt or ozone treatment. The economic level of salt concentration was evaluated to be 3%. Other conditions such as pH and the initial emulsion concentration did not critically affect the demulsification efficiency (95% at least) after 20 min reaction. The emulsion wastewater treatment technology utilizing the synergistic effect of salt and ozone activities was found to be relatively simple in its process and moderate in the operation conditions, hence may be an attractive alternative technology to the conventional demulsification processes.
Evaluation of filamentous microorganism growth factors in an industrial wastewater activated sludge system
Authors: Scruggs Caroline E. , Randall Clifford W.
Published: May 2018

An investigation comprising four studies was undertaken to determine possible factors affecting the growth of several different types of filamentous microorganisms present in a bulking industrial wastewater activated sludge. Results from laboratory-scale continuous-flow and full-scale studies suggested that DO concentration and F:M ratio were the likely key factors affecting filamentous growth in the activated sludge. From the results of two laboratory studies isolating the effects of DO concentration and F:M ratio on filamentous growth, favorable growth ranges of DO concentration or F:M ratio were estimated for the following filaments: Microthrix parvicella, Nocardia spp., Nostocoida limicola II, and Types 0041, 1851, and 1863. Most of the bacteria causing filamentous bulking of the activated sludge were found to be filaments typically associated with low F:M, and increasing the F:M ratio appeared to cause N. limicola II to lose its competitive advantage in the activated sludge system. Type 1863, on the other hand, was found to be a low DO filament, as DO concentrations of 0.1 mg O2/l or less appeared to be a necessary condition for its filamentous growth. Though Nocardia was found to be a low F:M filament, its growth also seemed to be affected by DO concentration, as its growth was stimulated by concentrations of 1.0 mg O2/l or greater, with a near linear relationship up to at least 5 mg O2/l.
Substrate utilization characteristics of the predominant filamentous and floc-forming bacteria isolated from a chemical fiber factory wastewater treatment plant
Authors: Tsai Yi-Chen , Lee Chi-Mei
Published: May 2018

To supply theoretical verification of the function of a selector to control aerobic activated sludge bulking in the wastewater treatment plant for a chemical fiber factory in Taiwan, the filamentous and floc-forming bacteria in the aeration tank in the full-scale plant were examined microscopically and isolated. The kinetic characteristics of filamentous and floc-forming bacteria were also investigated.

The predominant filamentous organism was Sphaerotilus natans. In addition to this organism, 21 strains of non-filamentous bacteria were isolated using the plate count method. These included Aeromonas jandaei DNA group 9, Acinetobacter johnsonii/genospecies 7, Bacillus pasteurii and Bacillus sp. (using the Biolog identification system). Nine strains showed the ability to form flocs when cultivated in glucose mineral salts medium.

With glucose and acetate as sole substrates, the 4 floc-forming bacteria tested showed different substrate utilization characteristics. The 4 strains could be divided into 3 groups. The first group was the substrate degrading bacteria, the second group was the acid degrading bacteria and the other strains were those that had the highest substrate degradation rates at low substrate concentrations (below 800 mg/l). None of the floc-formers could utilize ethylene glycol, which is the major wastewater component. The kinetic characteristics of filamentous bacterium S. natans (Km = 4.0 mg glucose/l, Vm = 0.43 μl O2/l) and the floc-forming bacterium Aeromonas jandaei DNA group 9 (Km = 34.8 mg glucose/l, Vm = 0.59 μl O2/l) provided information for selector design.
Biological iron(II) oxidation as pre-treatment to limestone neutralisation of acid water
Authors: Maree J. P. , Dingemans D. , van Tonder G. J. , Mtimkulu S.
Published: May 2018

Iron(II) should be oxidised to iron(III) before the neutralisation of acid water with limestone, otherwise the oxidation will occur downstream of the neutralisation plant with the formation of acid (reactions 1 and 2). This study aimed at investigating the effect of surface area of the medium that supports bacterial growth on the rate of biological iron(II) oxidation. The study showed that the biological iron(II) oxidation rate is directly proportional to the square root of the medium specific surface area.
The effect of chemical settling on the kinetics and design of activated sludge for tannery wastewaters
Authors: Orhon D. , Sözen S. , Çokgör E. Ubay , Genceli E. Ates
Published: May 2018

The effect of chemical settling of tannery wastewaters on the kinetic behaviour and performance of activated sludge process is investigated on the basis of experimentally supported model evaluations. Experiments involved besidese conventional characterization, detailed COD fractionation and assessment of major kinetic and stoichiometric coefficients by means of respirometric measurements. A multi-component model based on the endogenous decay concept was used for the kinetic interpretation and design of activated sludge. Results indicated that chemical settling as a pretreatment step induced a totally different kinetic pattern, significantly improving the biological treatability of tannery wastewaters. Design implications were evaluated in terms of major parameters of practical importance, such as effluent quality, activated sludge composition, aeration volume, oxygen demand and sludge generation.
Can microfiltration of treated wastewater produce suitable water for irrigation?
Authors: Vera L. , Villarroel R. , Delgado S. , Elmaleh S.
Published: May 2018

Water requirement for irrigation dramatically exceeds the traditional resources of Tenerife island that are becoming more and more brackish. An important programme of wastewater recovery is actually implemented; it is focused on the reuse of the secondary treated wastewater of the city of Santa Cruz for the irrigation of banana and tomato crops. Considering the hard competition with South American producers, the programme demands water completely disinfected. Microfiltration meeting the required standards, this study was then devoted to preliminary results obtained by cross-flow filtering through a 0.14 mm inorganic composite membrane, i.e. Carbosep M14, which was indeed a total barrier for suspended solids, total coliform, fecal coliform and fecal streptococci. The removal of turbidity and total COD were also significant, 93% and 60%. There was no rejection of the soluble fraction of size lower than 0.01 mm. Some 45% abatement of phosphorus was also obtained. The microfiltered water was therefore perfectly adapted for irrigation. In spite of a fouling mechanism difficult to identify, a critical flux of 100 l/m2 h was obtained at 1 bar driving pressure and 3 m/s cross-flow velocity and this value was close to the permeation rate for tap water. A phenomenological approach of the operation allowed us to define two dimensionless groups: the shear stress number and the fouling number. These numbers allowed us to display all the experimental results in only one curve.
Activated sludge foaming: the true extent of actinomycete diversity
Authors: Goodfellow Michael , Stainsby Fiona M. , Davenport Russell , Chun Jongsik , Curtis Tom
Published: May 2018

Isolates from activated sludge foam were provisionally assigned to the genera Gordona and Tsukamurella on the basis of colony morphology and pigmentation. Representatives of the first group were compared with marker strains of validly described species of Gordona by using Curie-point pyrolysis mass spectrometry. Most of the isolates fell into a number of taxa which were equated with groups of marker strains which corresponded to the known Gordona species. In a corresponding experiment the activated sludge isolates, which were provisionally labelled “Tsukamurella spumae” formed a group which was well separated from the marker strains of the genus. Representatives of the isolates were found to have chemical properties consistent with their classification in the genus Tsukamurella. 16S rDNA sequence data, when taken with previous DNA:DNA relatedness results, suggest that Tsukamurella paurometabola is heterogeneous. Similarly, the sequence data provide some evidence that “Tsukamurella spumae” may merit recognition as a novel species.
Achieving nitrification in pure oxygen activated sludge by seeding
Authors: Neethling J. B. , Spani Carlo , Danzer Joe , Willey Bruce
Published: May 2018

An innovative “seeding” approach was used to increase the nitrification capacity of a pure oxygen activated sludge plant. In this approach, waste activated sludge from a parallel air activated sludge system was used to seed nitrifiers to the pure oxygen plant to increase the apparent sludge age and achieve nitrification under the high loading in the pure oxygen system. Calculations indicate that nitrification can be achieved at a traditional sludge age of 3 days with a seeding rate of 20 percent. Full-scale tests showed that nitrification can be achieved at a seed rate of 35 percent and a traditional sludge age of 4.6 days, producing effluent ammonia below 5 mg/l. Secondary clarification remained good during the operation of the system even at the higher solids loading rates, with effluent TSS concentrations at 6 mg/l.
Phosphorus and polyhydroxyalkanoates variation in a combined process with activated sludge and biofilm
Authors: Chuang S. H. , Ouyang C. F. , Yuang H. C. , You S. J.
Published: May 2018

This study investigates variations of phosphorus and polyhydroxyalkanoates (PHAs) in a combined activated sludge - biofilm process, operating under various sludge retention times (5, 10 and 15 days) and different dissolved oxygen conditions (0.1, 0.5, 1.0 and 2.0 mg/l in aerobic stage). Experimental results indicate that phosphorus uptake closely corresponds to utilization of PHAs during anoxic and aerobic stages. Moreover, the sludge in the anoxic stage exhibits a higher PHAs utilization efficiency with respect to phosphorus uptake than sludge in the aerobic stage, when it is under low COD-SS loading conditions. The values of rP/PHAs, representing sludge capacity on phosphorus uptake, range from 0.1-1.0 mg P/mg PHAs. In addition, analyzing the distribution of 3-hydroxybutyrate (3HB), 3-hydroxy-2-methylbutyrate (3H2MB), 3-hydroxyvalerate (3HV) and 3-hydroxy-2-methylvalerate (3H2MV) reveals that 3HB and 3HV are the major components of PHAs. The values of 3HB/PHAs and 3HV/PHAs vary with COD-SS loading of the process. When F/M ratio increases, 3HV/PHAs value increases and 3HB/PHAs value decreases simultaneously. This phenomenon implies that more bacteria accumulated 3HV as storage matter under high COD-SS loading conditions. The kind of bacteria population shift would intensify the competition of “G bacteria” with polyphosphate accumulating organisms, possibly causing process deterioration during phosphorus removal.
Source identification of PCBs in sediments from the Milwaukee Harbor Estuary, USA
Authors: Rachdawong P. , Christensen E. R. , Chi S.
Published: May 2018

This work focuses on the determination of PCB source profiles and their contributions to sediments in the Milwaukee Harbor Estuary by a principal component analysis (PCA) model. The model was recently developed and, for the first time, applied to apportion pollutant sources in sediments. Factor loadings and scores were computed, rotated via nonnegative constraints, and matched with candidate Aroclor profiles. Contamination by Aroclors 1016, 1242, 1254, and 1260 were identified for cores VC 6, 9, and 12 based on a log Q2 criterion. The majority of PCB contribution was from a combination of Aroclors 1016 and 1242. Similarity between Aroclors 1016 and 1242 obscured resolution between the two profiles. Results from a chemical mass balance (CMB) model with known Aroclor profiles were in good agreement with the prediction from the PCA model.
Concentration and distribution patterns of naturally occurring radionuclides in sediments and flood plain soils of the catchment area of the river Elbe
Authors: Barth A. , Jurk M. , Weiß D.
Published: May 2018

The impact of uranium mining and milling as well as that of traditional mining activities on river sediments and flood plain soils in the catchment area of the river Elbe was investigated over the years 1994 to 1995. Contamination resulting from mining activities has been identified by comparing the median values for the measured radionuclides, and by establishing the ratio between Ra-226 and Ra-228. The transport and deposition of contaminated materials as a result of high water events, and river discharge of waste water from mining and milling facilities, can be considered to be the main paths of sediment and soil contamination. Sediments and flood plain soils located in the vicinity of former uranium mining and milling sites are primarily influenced by discharges of waste water. Long distance transport and deposition at dams, barrages and on flood plains has mainly been caused by high water events. In many cases the radionuclide concentrations were higher in the subsurface layer than in the top layer of flood plain soil. Due to termination of uranium mining and milling activities, no significant contamination of newer or fresh sediments was found. Radiation exposure arising in relation to angling or walking on flood plains is low.
Large scale treatment of contaminated sediments in The Netherlands, the feasibility study
Authors: Roeters Peter B.
Published: May 2018

In The Netherlands, contaminated sediments have to be removed from waterways. Environmental policy is directed at treatment of 20% of the contaminated dredged materials, thus generating reusable materials and saving on the required capacity in large scale disposal sites. The huge volume of material that will become available annually, can only be dealt with when treatment will take place on a large scale. A feasibility study was carried out for presenting treatment alternatives and compare these on technical, environmental and organisational aspects, as well as costs and financing. This paper presents the main results of the feasibility study. Three treatment scenarios were developed, each using a different combination of treatment techniques. The treatment scenarios are compared with a reference. It is shown that all treatment scenarios can meet policy goals. Costs for large scale treatment depend on the scenario that will be selected.
Comparison of results for chemical and thermal treatment of contaminated dredged sediments
Authors: Rienks Johan
Published: May 2018

This article describes the main results of research work on chemical and thermal treatment techniques from a special programme, subsidised by the Dutch government. The aim was development and demonstration of treatment processes for contaminated dredged sediments. Studied treatment processes were thio-leaching, EDTA-extraction, solvent-extraction, extraction with supercritical carbon dioxide, wet air oxidation and thermal desorption. All processes were performed on laboratory scale, some also on pilot scale or even at full scale. Three processes were selected as potential remediation processes based on their clean-up results (>99% removal of specific contaminants): solvent-extraction, wet air oxidation and thermal desorption. Wet air oxidation of slurred fines and thermal treatment of dewatered sediment were demonstrated successfully at full scale. The demonstrations were performed respectively by the VerTech plant for wet air oxidation of sewage sludge at Apeldoorn and Ecotechniek's plant for thermal treatment of contaminated soil at Rotterdam. Pilot-plant testing of solvent-extraction with acetone in counter current was delayed due to mixing problems in the settler-extractor. A description of the three selected processes is presented, as well as the performance characterised by treatment results, re-use of treated sediments, consumption of energy and raw materials, emissions to air and surface water, investment costs and operational costs.
Modelling of sediment treatment and disposal scenarios in the Netherlands
Authors: Gadella J. M. , Honders A.
Published: May 2018

This paper discusses the results (in terms of costs, reuse of sand and reduction of disposal volume) of a modelling study on various disposal and sand separation scenario's. The model is based on the following input data: (i) the quantity of annually dredged sediments divided over four types of sediment; (ii) the physical composition of these four types of sediment; (iii) the costs for wet disposal and sand separation. Based on the input data of the model, the SCG concludes that sand separation is an environmentally and economically attractive alternative for disposal. The costs for sand separation are in the same range as the costs for disposal, even at relatively low disposal costs (10–20 US $ per m3 ex-situ). Therefore large savings on both disposal volume and primary sand seems achievable.
Biomass deflocculation and process disturbances exerted by phenol induced transient load conditions
Authors: Galil N. I. , Schwartz-Mittelman A. , Saroussi-Zohar O.
Published: May 2018

Turbidity and relatively high concentrations of polysaccharides (biopolymers), indicating deflocculation of suspended biomass, could be observed as a result of phenol supplied in transient load conditions. The importance of preliminary acclimation could be observed in terms of the phenol removal rates at relatively low transient loading of phenol, up to 500 mg/l. As shock intensity increased to 1,000 and 1,500 mg/l, the acclimated reactors did not show relevant differences when compared to either partially acclimated or on-acclimated reactors. Transient load conditions created by phenol caused immediate reduction of the oxygen uptake rates and affected biomass respiration. Preliminary acclimation of the biomass indicated possible improvements of these influences, especially for phenol loads of up to 500 mg/l. The period following the application of phenol transient load was characterized by symptoms which could indicate that sorption-desorption mechanisms are involved by biomass, in addition to biodegradation. Preliminary collection and temporary storage of concentrated phenolic wastewater streams followed by gradually controlled release to the treatment facilities would provide reasonable solutions for avoiding biomass deflocculation and process disturbances caused by transient load conditions.
Kinetics and fundamental mechanisms of protein removal by activated sludge: hydrolysis of peptone to amino acids is the rate-determining step
Authors: Ubukata Yuu
Published: May 2018

Most ninhydrin reactants in primary effluent are proteins (polymers), and activated sludge (AS) bacteria can only directly take up monomers such as amino acids (AAs) which are produced from proteins by hydrolysis. Whether the hydrolysis of protein to amino acids by AS is the rate-determining step in the removal of protein was examined by comparing not only the removal rate of peptone and a mixture of free AAs but also the oxygen uptake rates of AS during the removal of these substrates, as well as analyzing the time courses of the concentration of each AA during the removal of these substrates. The removal rates of the AA mixture by AS were higher than those of peptone, and the oxygen uptake rates of AS during AA mixture removal were higher than those during peptone removal. The composition ratios of AAs during peptone removal were almost constant, whereas those of AAs markedly changed during AA mixture removal. The important difference between the two substrates used in this study (peptone and an AA mixture) is whether or not peptide bonds exist in the substrates. It was therefore verified that the hydrolysis of protein to AAs by AS was the rate-determining step in the removal of protein from municipal sewage.
Carbon tetrachloride biodegradation in a fixed-biofilm reactor and its kinetic study
Authors: Jin G. , Englande A. J.
Published: May 2018

Kinetics of Carbon Tetrachloride biodegradation are evaluated in a continuous-flow fixed-biofilm reactor with controlled initial redox potential. The column was seeded with a mixed culture of indigenous microorganisms Pseudomonas cepacia and Providencia stuartii. The fixed biofilm reactor exhibited 98%–99.9% biodegradation of CT introduced into the reactor at an initial concentration of about 200 μg/l for retention times of 1 to 4 days respectively. Four models were employed to evaluate the kinetics of CT biodegradation. These included: Eckenfelder (1989), Arvin (1991), Bouwer and McCarty (1985) and a biphasic model. Comparison of calculated results with observed results between these models agreed very closely to each other (0.968 < R2 < 0.999). Predicted performance was best described by the model of Bouwer and McCarty (1985). However, the biphasic and Eckenfelder models provided excellent correlations and were much simpler to apply. The biphasic model yielded very good correlations of the data for all detention times evaluated; whereas, the Eckenfelder model effected comparable results only at the longer retention times studied.
A new fixed-film mobile bed bioreactor for denitrification of wastewaters
Authors: Chudoba P. , Pannier M. , Truc A. , Pujol R.
Published: May 2018

An innovative fixed-film mobile bed bioreactor for high-rate denitrification of wastewaters has been developed and tested. This reactor, called the Mixazur® enables a high denitrification efficiency due to high kinetics. These properties are combined with a very simple system, particularly due to the choice of a suitable mineral granular support for bacterial growth, enabling a very low filling ratio. This low filling ratio, usually smaller than 5% vol., offers a sufficient surface area for fixed-film development, easily moved by a simple mechanical agitation with low energy consumption (< 30 W/m3 of reactor). The experimental study showed that this reactor can achieve an eliminated loading rate of 0.6 kg NOx-N/m3 of reactor per day at a removal efficiency more than 80% and at water temperatures between 13 and 20°C. The separation of a denitrifying biomass in a specific pre-denitrifying bioreactor led to a development of a very active biofilm with denitrification rates as high as 10 mg NOx-N/g MLVSS.h at 18°C. The scale-up of this system does not need any sophisticated wastewater inlet distribution system, any additional material/biomass separation device and any recirculation loop for maintaining a constant fluidization velocity. Moreover, the reactor is characterized by its low-cost equipment, continuous operation and by auto-regulation of both biofilm thickness and activity due to a controlled shear stress and by an overall easy operation. The first full-scale facility, for 1200 p.e., using this system has been operating since 1996.
Modelling bacteriological water quality in drinking water distribution systems
Authors: Piriou P. , Dukan S. , Kiene L.
Published: May 2018

Because on-site experimentation raises numerous problems, the study and the modelling of bacterial regrowth phenomena in drinking water distribution systems has been performed using a pipe loop pilot under various operating conditions. As a result, experiments have shown that inlet bacterial counts have little influence on the biofilm behavior which is mainly driven by the amount of available nutrients (BDOC). Biofilm detachment has a significant influence on the increase of suspended bacterial counts with time in relation to the net growth in the bulk water. All these results have been used to develop and validate a deterministic type of model, called PICCOBIO. Some guidelines to achieve water bacteriological stability have been proposed using model simulations.
Granulation and sludge retainment during start-up of a thermophilic UASB reactor
Authors: Syutsubo Kazuaki , Harada Hideki , Ohashi Akiyoshi
Published: May 2018

A laboratory-scale UASB reactor was operated at 55°C over 600 days in order to investigate the granulation mechanism under thermophilic conditions. The reactor was seeded with a thermophilic digested sewage sludge, and fed with a synthetic wastewater composed of sucrose and volatile fatty acids. As a result of establishment of the whole granulated sludge bed, the reactor allowed ultimately a volumetric COD loading of 45 kgCOD m−3 d−1 with 90% COD removal. The maximum sludge loading achieved was 3.7 gCOD·gVSS−1 d−1, that is two to three times as large as that of mesophilically grown sludge. The behavior of SRT (sludge retention time) was closely correlated with the biogas evolution flux: excessive biogas evolution at the highest COD loading (45 kgCOD m−3 d−1) enhanced the sludge washout, and thus led to shortening of SRT into less than 7 days. Methanogenic activities of the retained sludge increased finally up to 110 times for acetate, 25 times for propionate, and 3.6 times for hydrogen as large as those of the seeded sludge.
Application of the down-flow fluidized bed to the anaerobic treatment of wine distillery wastewater
Authors: García-Bernet D. , Buffière P. , Elmaleh S. , Moletta R.
Published: May 2018

This paper presents the results of the operation of a down-flow anaerobic fluidized bed treating red wine distillery wastewater during 1.5 years (laboratory scale). The carrier employed was ground perlite, an expanded volcanic rock (density 213 kg m−1, diameter 0.968 mm). After a 2 months start-up period, organic loading rate (OLR) was increased stepwise by reducing hydraulic retention time (HRT). The system attained carbon removal efficiency rates between 75 and 95%, at a OLR of 17 kg TOC m−3 d−1 (total organic carbon), at an HRT of 0.35 days. The results observed showed that the inverse fluidized bed can be an interesting option for anaerobic wastewater treatment.
Anaerobic digestion of solid substrates in an innovative two-phase plug-flow reactor (TPPFR) and a conventional single-phase continuously stirred-tank reactor
Authors: Liu Tuanchi
Published: May 2018

An innovative mesophilic continuous-feed anaerobic plug-flow reactor was employed to study system performance with solid feeds from 3% to 16% TS and hydraulic retention times from 32.0 to 13.1 days. The reactor performance under high-solid feeds (>10% TS) corresponding to phase separation along the longitudinal distance of the plug-flow reactor was discussed. The two-phase plug-flow reactor (TPPFR) always recovered from acidogenic conditions prevailing at the head end of the TPPFR, and the methanogenic phase was dominant within the remainder of the TPPFR. As the feed solids concentration increased to greater than 16% (loading capacity of the feed solids concentration) and as the acidogenic phase was extended, the methanogenic bacteria could not recover from the “sour” digestion as shown by the decreased gas/or methane production rate. With same feeds and under same operating conditions, the performance of the plug-flow reactor with phase separation is much better than that of the conventional single-phase continuously stirred-tank reactor (CSTR) in terms of efficiency and overall bioconversion.
Wastewater characterization in metropolitan areas with significant agro industries
Authors: Görgün E. , Babuna F. Germirli , Orhon D. , özbaşaran M. , Seçkin N.
Published: May 2018

Basic principles and details on the assessment of wastewater characterization are reported for metropolitan areas with significant industrial activities, with great capacity for future development. The conceptual approach related to the evaluation of pollution loads in terms of major parameters is defined both for domestic and industrial sources. Methods for extrapolating generated data for the future are discussed. A procedure is developed for the evaluation of the expected industrial pollution profiles on the basis of inadequate data. The proposed methodology is illustrated for Çorlu as a case study, a region with rapid industrialization in Turkey.
Estimation of treatability of different industrial wastewaters by activated sludge oxygen uptake measurements
Authors: Orupõld K. , Hellat K. , Tenno T.
Published: May 2018

The activated sludge short-term respiration measurement is proposed for assessing the properties of activated sludge and biological treatability of wastewaters. Different influents to the wastewater treatment plant were analyzed and compared on the basis of exogenous oxygen uptake rates of activated sludge. The kinetic parameters of biodegradation processes were determined by monitoring the degradation-associated oxygen consumption in tests with different amounts of wastewaters from textile industries and tanneries. The short-term oxygen demands in the tests formed 25-45% of the biochemical oxygen demand of the textile industry wastewater.
Treatability of kraft pulp bleaching wastewater by biochemical and photocatalytic oxidation
Authors: Balcıoǧlu Işıl Akmehmet , Çeçen Ferhan
Published: May 2018

In this study the biological treatability and TiO2 photocatalyzed oxidation characteristics of sulfate pulp bleaching effluents were investigated. The original wastes had a low biodegradability as determined by BOD5/COD ratios. Biological treatment was conducted in a batch activated sludge reactor. The non-biodegradable fraction amounted to 60% of the initial COD and compounds specific to these wastes were not removed during biotreatment. In order to enhance the biodegradability of these wastes, mixed raw effluent, C/E-H stage effluent, D/E-D stage effluent and biologically pretreated wastes were subjected to TiO2 photocatalyzed oxidation. Photocatalytic oxidation led to an increase in the BOD5/COD ratio of D/E-H stage raw and biologically treated wastewater, while chloride formation was observed in both cases in a five-hour reaction period in the presence of 1g 1−1 TiO2 and 15×10−3 M H2O2 at pH=6.5. The specific absorption values (A272nm/CODs, A254nm/CODs, A346nm/CODs, A436nm/CODs) exhibited parallel decreases during photocatalytic oxidation which indicate that oxidation reactions were nonspecific with respect to the organics present in these wastes. As a conclusion it can be suggested that biological treatment should be placed before the photocatalytic oxidation method. Even in this scheme, the application of photocatalytic oxidation could only then be favored when the COD and chloride concentrations in the wastewater were below certain values or when wastewater was diluted.
Biological treatability of poultry processing plant effluent - a case study
Authors: Eremektar G. , Çokgör E. Ubay , Övez S. , Babuna F. Germirli , Orhon D.
Published: May 2018

Poultry processing generates strong wastewaters with characteristics that may be tailored by appropriate adjustment of the operation. The organic content has a residual fraction in the order of 200-400 mgl−1, depending on the strength of the wastewater. The values of kinetic and stoichiometric constants related to biological treatability are observed to be quite comparable with domestic sewage. The hydrolysis of slowly biodegradable organics is best described by dual-hydrolysis kinetics with appreciably different rate constants for soluble and particulate components. The experimental results of the study may be used to evaluate the achievable compliance with existing effluent limitations and to define the optimum in-plant operation and wastewater treatment and disposal strategy.
The feasibility of flocculation in a storage sedimentation basin
Authors: De Cock W. , Blom P. , Vaes G. , Berlamont J.
Published: May 2018

For the Flemish situation, storage sedimentation basins are one of the best ‘end-of-pipe’ solutions to reduce the impact of combined sewer overflows on the receiving waters. In some cases, when the spilled pollution load is too high, the settling efficiency of the basin has to be improved. Adding coagulants could be a reasonable alternative for building larger basins. To estimate the effect of enhancing the settling by flocculation, a floc growth and break-up model is worked out and is implemented in the numerical model Phoenics. The evolution of the floc dimensions and the sedimentation behaviour of the particles in the basin is calculated for different inflow rates and initial settling velocity profiles. Finally, the efficiency increase by mixing (creating a higher velocity gradient) in the agitation chamber or by adding coagulants in the trunk sewer upstream of the basin is also investigated.
Mineral oil bio-degradation within a permeable pavement: long term observations
Authors: Pratt C. J. , Newman A. P. , Bond P. C.
Published: May 2018

The paper reports on the first 300 days of a research project conducted at Coventry University, which has focused on the ability of a permeable pavement, reservoir structure to retain and treat petroleum-derived pollutants through in situ microbial bio-degradation. The research has required the construction of a full-scale model permeable pavement in the laboratory, which has been subjected to prolonged low-level hydrocarbon contamination, representative of typical loadings to urban surfaces such as highways and car parks. Water quality and bio-degradation indicators have been monitored over several months so that the capability of the permeable pavement to maintain a viable and effective microbial population could be assessed. The research has demonstrated that the structure can be used as an effective in situ aerobic bioreactor.
Mathematical modeling – a tool for coastal water quality management
Authors: Mahajan A. U. , Chalapatirao C. V. , Gadkari S. K.
Published: May 2018

This paper suggests an approach to solve the Indian coastal water quality management problem based on waste load allocation studies and application of modelling techniques. The waste load allocation procedure suggested in this paper assists in deriving a quantitative relationship between the waste load discharged and the receiving coastal water concentrations or effects of concern as presented by water quality standards. The approach sequentially addresses the topics of hydrodynamics, mass transport, water quality kinetics and problems of bioaccumulation and toxicity.

The water quality modelling section describes the role of water quality modelling in WLA procedure. The paper also discusses the criteria and procedures for formulation of coastal zone management plans. The second part of the paper illustrates the concept with the help of brief case studies wherein simple screening procedures and the water quality modeling techniques have been applied. The first case study describes the application of the WASP model to arrive at the level of treatment required for municipal wastewater being discharged into Mumbai coastal waters so that the designated coastal water quality criteria is not violated and the degree of treatment is optimized. The second case study deals with the study of different options relating to disposal of tailings from an iron ore beneficiation plant keeping in view the impact of these tailings on marine water quality and ecology.
Diffuse pollution from agriculture - a worldwide outlook
Authors: Novotny Vladimir
Published: May 2018

Until the 1950s most farming was carried out on smaller family farms that used organic fertilizers and essentially their waste production was easily assimilated by soils and receiving water bodies. The period post 1950 has seen a worldwide shift to larger monocultural, intensively operated farm units. The farm yields have increased dramatically, however, to sustain the increasing yields and productivity farms are using large quantities of chemical fertilizers and pesticides. At the same time, deforestation has occurred on a large scale since the 1950s and the deforested land has been converted to agricultural (mostly in developing countries) and urban (both developed and undeveloped countries) land uses. Also, a massive shift of population from rural areas to the cities has occurred in developing countries since the 1950s. Surface and groundwater quality degradation due to agricultural practices and conversion of land to agriculture can be categorized as follows: a) degradation due to land use conversion from native lands to agriculture; b) increased erosion and soil loss due to agricultural practices; c) chemical pollution by fertilizers and pesticides; and d) pollution from animal operations. Abatement of agricultural diffuse sources of pollution can and must be conducted in the context of moving toward sustainable agriculture. Some trends toward sustainable agriculture are already emerging in the US and Europe.
Removal of BOD5 in Constructed Wetlands with Horizontal Sub-surface Flow: Czech Experience
Authors: Vymazal Jan
Published: May 2018

Constructed wetlands with horizontal sub-surface flow (HSF CWs) usually provide high removal of BOD5. Organic compounds are degraded by both aerobic and anaerobic bacteria in the rhizosphere of vegetated beds. The results from the Czech HSF CWs showed an average treatment efficiency of 86.6% with an average effluent BOD5 concentration of 13.2 mg 1−1. The BOD5 loading of vegetated beds of HSF CWs varied between 2.6 and 99.6 kg ha−1 d−1 with an average of 33.5 kg ha−1 d−1. The results also indicated that the removal of BOD5 is not temperature dependent and is steady throughout the year.
Agricultural land use changes and water quality: a case study in the watershed of the lagoon of Venice
Authors: Giupponi Carlo , Rosato Paolo
Published: May 2018

The effects of alternative agricultural land use scenarios in terms of environmental impact assessment on surface and ground water were simulated by means of combined socio-economic and environmental models. The economic model produced and evaluated alternative farming systems, defined in terms of land use (in farm crop allocations and regional statistics of crop distributions) and cultivation practices as influenced by different macro-economic scenarios of agricultural policies. These scenarios were defined on the basis of the present Common Agricultural Policy of the European Union and possible future measures for reducing the impact of current agricultural systems on the environment. The farmers' decisional process has been simulated with multi-objective functions aimed at maximising profits and minimising risk. The methodology for the environmental impact assessment of farming systems is based on a simulation model for non-point source agricultural pollution which determines the impact of agriculture on a single field basis as influenced by environmental variables (soil and climate) and farmers' decisions (crop, soil management, fertilisation, etc.). The results obtained from this model were used to calculate a series of comparative indices capable of describing the effects of the use of fertilisers and pesticides on surface and ground waters. A geographical information system supported the spatial data management in particular for: a) the definition of simulation environments; b) the integration of physical and statistical geographical information; c) the cartographic presentation of results and the comparison of alternative scenarios. The model has been applied in the area of the Watershed of the Lagoon of Venice (WLV), located in northern Italy and has demonstrated how alternative policy scenarios determine not only significant variations in the overall environmental impacts in the study area, but also remarkable differences in their spatial distribution.
Constructed Wetlands for Rehabilitation and Reuse of Surface Waters in Tropical and Subtropical Areas – First Results from Small-scale Plots Using Vertical Flow Beds
Authors: Perfler Reinhard , Laber Johannes , Langergraber Guenter , Haberl Raimund
Published: May 2018

The application of constructed wetlands is seen to be a valuable way to treat polluted surface waters for rehabilitation of the water body (shallow lakes) and for reuse as irrigation and drinking water. In a first step a construction and operation design was worked out for small-scale plots which have been operated in Europe and at a site in China. The small-scale plots are designed as subsurface flow systems with a downflow and upflow compartment in series. The different layers consist of sand and gravel with a minimum hydraulic conductivity of about 10−4 m/s. Several small-scale plots, planted with different species, have been tested in parallel. During almost one year of operation the monitoring of the systems aimed at: checking the effectiveness of different plant species, variation of loading rates and intervals and variation of recirculation to the system. The results for some relevant parameters (BOD5, NH4-N, N, P) show a high overall efficiency – strongly depending on operation conditions such as feed rate, alternate feeding and resting time. As a result the construction design has been modified for the construction of pilot systems in China. The whole project was carried out within the INCO-DC programme of EC with partners from Germany and China.
Constructed Wetlands for Wastewater Treatment in Colombia
Authors: Williams J. B. , Zambrano D. , Ford M. G. , May E. , Butler J. E.
Published: May 2018

A modular wastewater treatment system has been installed for the Colombian Coffee Growers Federation (FEDERACAFE) at the Fundacion Manuel Mejia residential training centre. This system was designed by the University of Portsmouth, UK, and based on previous experience with the Gravel Bed Hydroponic (GHB) constructed wetland system. The steep topography of the site posed constraints on the design and a modular system composed of a rock filter in gabions for primary treatment, GBH beds for secondary treatment and a pond for tertiary treatment was selected. This system was designed to follow the contours of the site and maximise treatment.

The GBH reed bed was planted with Typha angustifolia in early 1997. The system is being monitored by CENICAFE, the research division of FEDERACAFE. Monitoring of the system has shown large BOD removals from more than 350 to less than 20 mg/l. Initial results have also suggested 4 log cycle reductions in indicator bacteria.

It is hoped that the success of this system will result in the replication of the treatment process at many villages in the Colombian coffee growing region where conventional sanitation technologies are impractical.
Potential Use of Aquatic Macrophytes to Enhance the Treatment of Septic Tank Liquids
Authors: Perdomo S. , Bangueses C. , Fuentes J.
Published: May 2018

In several urban and suburban areas, the problem of the disposal and treatment of septic tank liquids has not been solved yet. This paper deals with the primary operational evaluation of a conventional system of ponds used at Tarariras, in the Department of Colonia, Uruguay, as well as the potential use of aquatic macrophytes to enhance such treatment. The conventional system was sampled over a period of approximately one month at the end of the summer in order to determine the main parameters. Groups of up to 20 samples were studied to determine the normal distributions. Correlation coefficients were obtained for the normal probability plot between 0.84 and 0.99. The most relevant statistical characteristics were calculated for each parameter. The removal efficiency was 80.0% of BOD5, 58.5% of COD, 75.8% of NH4+-N, 9.5% of PO4−3-P and 38.5% of TSS. At the same time, batch and semi-continuous trials were carried out at bench scale with Eichhornia crassipes (floating macrophyte) and Typha latifolia (emergent macrophyte). The best efficiencies were obtained for the latter, with values of 96.6% of BOD5, 93.0% of COD, 99.6% of NH4+-N, 95.2% of PO4−3-P and 95.5% of TSS. It was concluded that constructed wetlands could be the answer to a more complete treatment process.