bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anaerobic digestion of solid waste: state-of-the-art
Authors: De Bere L. 
Published: May 2018

In order to make a correct assessment of the state-of-the-art of the technology, a study was made on the development of digestion capacity for solid waste in Europe. The study was limited to plants in operation or under construction that were treating at least 10% organic solid waste coming from market waste or municipal solid waste. A total treatment capacity for solid waste organics, excluding the tonnage used for sewage sludge and manures, evolved from 122,000 ton per year in 1990 to 1,037,000 ton available or under construction by the year 2000 in 53 plants across Europe, an increase by 750%.
Both mesophilic and thermophilic technologies have been proven, with about 62% of capacity being operated at mesophilic temperatures. Wet and dry digestion are almost evenly split, while a clear choice was made for one-phase systems instead of two-phase systems, which represent only 10.6% of capacity. The capacity provided by co-digestion systems is limited, while there is a rising interest in digestion of mixed household waste.
The reliable performance has been demonstrated for all types of anaerobic digestion systems. On the basis of the Dranco technology, a single-phase thermophilic dry digestion process, performances were reached similar to high-rate wastewater digestion. An annual average loading rate of 18.5 kg COD/m3.day, resulting in a biogas production of 9.2 m3/m3reactor.day was obtained at a full-scale plant. The plant operated at a retention time of 15.3 days. Feedstocks range from clean organic wastes (31% dry matter) to heavily polluted grey waste organics (57% dry matter). Average dry matter concentrations of the digested residue of 41% were obtained.
Odour measurement: A code of practice
Authors: Sneath R. W. , Clarkson C. 
Published: May 2018

Odour emission is as much a part of the adverse effect of any new or existing process as noise, water pollution, VOC emissions or radiation. It is essential to quantify it whenever plans are being made for new or modified processes.
The first aspect of quantification of odour emission is the need to use a standard method of measurement of odour concentration. Aswith liquid effluents where we use standard laboratory methods for each characteristic, e.g. BOD, COD, TSS etc., the analysis method for measurement of odour concentration is the CEN/TC264/wg2 (draftprEN13725) standard (ComittéEuropéen de Normalisation/Technical committee 264/Working Group 2). This standard is often specified in tender documents as the methodology to be used in the assessment of abatement equipment performance. In this paper the standard, with what it can and can not do, is described in detail.
The second aspect is that methodologies should be agreed for sample collection. The collection protocol, at the lowest level, is agreed so that significant day to day comparisons can be made. More rigorous protocols must be drawn up when legal requirements need to be met so there is consistent enforcement of regulations or discharge consents.
It is most important that a representative odour sample is collected from the source. This is most problematic when the odour is emitted from a large surface either with or without airflow through it. Best practice methods are presented and discussed. The statistical significance of the analysis, as with any other measurement, depends upon the precision of the laboratory analysis and the number of samples analysed. An example will be used to illustrate the importance of calculating the number of samples required for a given purpose.
An optimised and standardised test to determine the presence of the protozoa Cryptosporidium and Giardia in water
Authors: Stanfield G. , Carrington E. , Albinet F. , Compagnon B. , Dumoutier N. , Hambsch B. , Lorthioy A. , Medema G. , Pezoldt H. , de Roubin M-R. , de Lohman A. , Whitmore T. 
Published: May 2018

With funding from the European Commission, a consortium of members of the European Water Research Institutes is carrying out a programme of work with the objective of optimising and standardising a method for determining the presence in water of (oo)cysts of Cryptosporidium and Giardia. Each of the stages of the conventional analysis procedure (initial concentration, recoveryand identification and enumeration) are being investigated and the relative merits of existing and new methods are being assessed. Newly developed filters (Envirochek and Filta-Max) have been shown to be more efficient for initial recovery of (oo)cysts from water than the previously used Cuno cartridge filters. In addition, for the analysis of raw waters, flocculationwith ferric sulphate has been shown to give recoveries similar to the Envirochek and Filta Max.
Modern purification systems such as immunomagnetic separation have also been assessed and found to offer some advantages over flotation although optimisation of the latter has brought improved efficiency. Preliminary assessment of solid phase cytometry has indicated that this technique could offer significant time savings compared to conventional microscopic counting. The results of the study will be used to propose a revised standard method to CEN.
Modelling and test of aeration tank settling (ATS)
Authors: Nielsen M.K. , Bechmann H. , Henze M. 
Published: May 2018

The use of aeration tank settling during high hydraulic loads on large wastewater treatment plants has previously been demonstrated as a reliable technique and proven valuable. The paper proposes a simplified deterministic model to predict the efficiency of the method. It is shown that a qualitatively correct model can be established. The simplicity of the model allows for on-line identification of the necessary parameters, so that no maintenance is needed to use of the on-line model for control.
The practical implementation on three plants indicates that implementation of STAR with ATS control gives 50% increase of plant capacity for 3% extra cost.
Thermophilic process and enhancement of excess activated sludge degradability – two ways of intensification of sludge treatment in the Prague central wastewater treatment plant
Authors: Zábranská J. , Dohányos M. , Jenícek P. , Kutil J. 
Published: May 2018

The paper describes two ways of intensification of sludge treatment in the Prague Central Wastewater Treatment Plant: full-scale experiment with thermophilic anaerobic digestion and full-scale experiment with lysis thickening centrifuge.
Increasing temperature from the mesophilic to thermophilic level in the full-scale digesters leads to a better utilization of the existing facilities and consequently avoids digester overloading. The higher degradation efficiency is associated with higher biogas production and improvement of the energy balance of the process. Due to a careful and slow increasing of the operating temperature the thermophilic process was very stable.
The partial destruction of excess activated sludge cells during the thickening by means of a lysis-thickening centrifuge produces cell lysate. The presence of the cell lysate in thickened excess activated sludge causes a substantial increment in the methane yield and the biodegradability of thickened activated sludge in comparison with untreated excess sludge. The improvement of methane yield from thickened activated sludge was on average 11.5–31.3% dependent on the sludge quality. The operation of lysis-thickening centrifuges in the Prague Central Wastewater Treatment Plant proved the possibility of full-scale application of the disintegration method.
Comparative study of oil accumulation characteristics in attached and suspended growth reactors
Authors: Abadi Y. , Galil N. 
Published: May 2018

In this study, the sorption extent and characteristics of low biodegradability hydrocarbons to biomass in attached growth (AG) and suspended growth (SG) processes were compared. Distinction was made between settled biomass from the settling chamber (sludge biomass) and non-settled biomass from the process effluent (effluent biomass). In both processes the sorption to the sludge biomass was the main oil removal mechanism, however, differences in the extent and characteristics of oil sorption were observed. The AG sludge biomass sorbed more oil than the SG sludge biomass and the sludge biomass oil fraction was always higher than the effluent biomass oil fraction. In the SG process, the sludge biomass oil fraction was lower than the effluent biomass oil fraction for the first 42 days of operation and then the trend reversed.
The settling quality in the SG process was damaged during the sorption of oil and biomass concentration in the reactor decreased, while the AG process suffered only from short-term disturbances in the settling quality. Furthermore, the results indicated that effluent suspended solid concentration in the AG process decreased when the oil sorption rate was high.
Trichloroethylene elimination assay by naural consortia of heterotrophic and methanotrophic bacteria
Authors: Hourbron E. , Escoffier S. , Capdeville B. 
Published: May 2018

Xenobiotic compounds generated from the various industrial activities are toxic and could affect the natural ecosystem. So far biological processes have been used for treatment of those compounds. It has been reported that xenobiotic compounds can be degraded in pure cultures of methanotrophic bacteria. Therefore, the aim of this study is to demonstrate the capacity of several natural consortia of heterotrophic and methanotrophic bacteria in degradation of trichloroethylene (TCE). Treatability of TCE was studied using 3 different consortia of heterotrophic and methanotrophic bacteria. After a first culture with methane and contact with TCE, all the consortia tested showed a biological TCE degradation efficiency between 29 and 43%. Using acetylene as MMO inhibitor, the implication of this enzyme on the three inocula was demonstrated very well. It was found that the toxicity threshold of TCE to the tested bacteria fell into a range of 30 to 40 mg/l. At not toxic TCE concentration of 5 and 10 mg/l, the maximal TCE specific activity was observed after an incubation of 15 minutes. This initial degradation rate could be used as indicator of the efficiency of a natural inoculum for TCE degradation. The impact of the initial TCE and biomass concentration on the TCE degradation kinetics was also evaluated. In the experiments, the TCE degradation was subject to first order kinetics. The maximum specific degradation rate of TCE was estimated at 48.9 mg TCE/mg SST.h.
These experiments clearly demonstrate that methanotrophic bacteria are ubiquitous in the environment, and a lot of them can degrade TCE. This shows good perspectives for in situ treatment of TCE-contaminated sites by enrichment of the methanotrophic natural populations.
Fouling performance in the filtration of water containing humic acid and/or kaolin with microporous membrane
Authors: Fukada S. , Tsuji T. , Minegishi T. , Yamamoto S. , Itazawa T. , Matsumoto K. 
Published: May 2018

Acceleration tests were done using the small-scale microporous membrane (MF) module to predict the increase in transmembrane pressure at the constant flow rate dead-end filtration in a pilot plant for treating the river water or dam water. The kaolin suspension, solution of humic acid and the mixture of kaolin and humic acid were used as feed water in the acceleration tests. The conventional equations of medium blocking filtration were applied to predict the pressure increase for both pilot plant tests and small-scale ones. The experimental results are summarized as follows:
(1) The pilot plant tests: The time course of transmembrane pressure was expressed by the complete blocking filtration equation or the standard one when the unstable time at the beginning of operation was excluded.
(2) The acceleration tests using small-scale membrane module:(a) No increase in transmembrane pressure was observed when the kaolin suspension and the bentonite one were used as feed water, (b) The increasing rate of transmembrane pressure was lowered by the addition of coagulant into the humic acid solution, (c) The humic acid had a great influence on the increasing rate of transmembrane pressure in the filtration of water containing kaolin or no kaolin and (d) Similar curves of filtration time vs. transmembrane pressure were obtained in the acceleration tests as were obtained in pilot plant tests.
Understanding membrane fouling in ultrafiltration of WWTP-effluent
Authors: Roorda J.H. , van der Graaf J.H. 
Published: May 2018

The application of ultrafiltration to effluent of waste water treatment plants (WWTP-effluent) is getting increasing attention. However, many experiments show a rapid decrease in flux urging frequent and intensive cleaning. In order to understand the mechanisms of the occurring fouling process, various filtration and cleaning experiments were performed, giving information about the filterability of the feedwater (F) and the reversibility of the occurring fouling layer (R). Short-term fluxes are mainly determined by the filterability, while both the filterability and the reversibility greatly affect long-term fluxes. The objective of this research is to measure the filterability of WWTP-effluent and the reversibility of the occurring fouling layer in ultrafiltration of wwtp-effluent with and without pre-treatment.
The results of the filtration experiments show a rapid decrease of flux resulting in a low value for the filterability, which also decreases during progressing filtration. The filterability is mainly related to the volume of treated water. Pre-treatment of the WWTP-effluent by in-line coagulation or by deep-bed filtration has little influence on the filterability. However, results on the reversibility show an improvement of the reversibility by pre-treatment. Both filterability of the WWTP-effluent and reversibility of the fouling layer are found to be independent of the applied flux.
As to the applied cleaning methods, the back flush is far more effective than the forward flush even if combined with air. In all experiments the remaining fouling layer still has to be removed by an intensive chemical cleaning. This research indicates the very importance of reducing the formation of an irreversible, non-removable fouling layer.
Kinetics of azoreductase and assessment of toxicity of metabolic products from azo dyes by Pseudomonas luteola
Authors: Hu T.-L. 
Published: May 2018

This is a continuous study on a decolorization strain, Pseudomonas luteola, which involves treating seven azo dyes with different structures. This study focuses mainly on determining both the mechanism of decolorization by P. luteola and the activity of azoreductase from P. luteola as well as identifying and assessing the toxicity of metabolic products of azo dyes.
The growth of P. luteola reached the stationary phase after shaking incubation for 24 hours. Then, while being kept static, the color of seven tested azo dyes (100 mg/l) could be removed. The proportion of color removal was between 59–99%, which figure is related to the structure of the dye. Monoazo dyes (RP2B, V2RP and Red 22) showed the fastest rate of decolorization, i.e. from 0.23–0.44 mg dye-mg cell–1 hr–1. P. luteola could remove the color of V2RP and a leather dye at a concentration of 200 mg/l, and as to the rest of the azo dyes, it could remove at a concentration of up to 100 mg/l.
Decolorization of RP2B and Red 22 required activation energy of 7.00 J/mol and 6.63 J/mole, respectively, indicating that it was easier for azoreductase to decolorize structurally simple dyes. The kinetics of azoreductase towards seven azo dyes suggested a competitive inhibition model be applied.
Microtox® was used to analyze the toxicity of the metabolic products of azo dyes. EC50 showed differences in toxicity before and after the azo dyes had been metabolized. Analysis revealed significant differences between the results obtained by EC50 with Blue 15 and those obtained with the leather dye, indicating that the toxicities of the metabolic products were increased. The differences obtained by EC50 with Red 22, RP2P and V2RP were small, and Black 22 showed no such difference. Sulfanic acid and orthanilic acid may be the intermediate products of Violet 9 and RP2B, respectively. However, according to FT-IR analysis, aromatic amines were present in the metabolic product.
Preserving the (water) harvest: effective water use in agriculture
Authors: Kijne Jacob W. 
Published: May 2018

The alternative to increasing the world's irrigated area by an estimated 30% to secure food security for all, seems to be limited irrigation expansion and consequently higher food prices and probably food shortages. This paper explores other options for ensuring food security. It discusses meaningful similarities between innovative approaches for land and water management in rainfed and irrigated agriculture. The focus is on innovative approaches to increase yields in sub-Saharan Africa and South Asia.
Innovative technologies, such as improved tillage practices and water harvesting are important. But at least as important are the processes by which new agricultural practices are developed, improved and extended. In the end it comes down to human inventiveness.
Post-treatment of anaerobic effluents in constructed wetland systems
Authors: de Sousa J. T. , van Haandel A. C. , Guimarães A. A.V. 
Published: May 2018

This papers describes the behaviour of wetlands as a post-treatment unit for anaerobically treated sewage for the removal of organic matter, suspended solids, nutrients (nitrogen and phosphorus) and faecal coliforms. Raw sewage was treated in a UASB reactor with a retention time of 5 h and the effluent was used in four units of wetlands with coarse sand as the medium and operated with different hydraulic loads. Three of the units had emerging macrophytes (Juncus sp), whereas the fourth one was operated as a control unit without plants.
During the 12 months of operation, the organic material removal efficiency (measured as COD) was in the range of 79 to 85%, whereas suspended solids removal varied from 48 to 71%. Faecal coliform removal was very high (99,99%); phosphorus was also efficiently removed (average efficiency of 90% for the lowest hydraulic load), but nitrogen removal was only partial (45 to 70% for ammonia and 47 to 70% for TKN). The experimental results clearly show the technical feasibility of using wetlands for treatment of municipal sewage after a pre-treatment in the UASB reactor.
Polishing ponds for post-treatment of digested sewage part 1: flow-through ponds
Authors: Cavalcanti P. F.F. , van Haandel A. , Lettinga Gatze 
Published: May 2018

Polishing ponds are used to improve the quality of effluents from efficient anaerobic sewage treatment plants like UASB reactors, so that the final effluent quality becomes compatible with legal or desired standards. The residual organic material and suspended solids concentrations in the digested sewage are reduced, but often the main objective of polishing ponds is to improve the hygienic quality, measured by the concentration of two indicator organisms: helminth eggs and faecal coliforms (FC). The FC removal is normally the slowest process and for that reason becomes the main design criterion for a polishing pond. By contrast in conventional waste stabilisation pond (WSP) systems the organic material removal is the governing design parameter.
The feasibility of operating a single polishing pond for the post-treatment of UASB effluent is shown in this paper and the final effluent quality as a function of the retention time is discussed. Even under the most adverse weather conditions (several weeks of rain) the population of algae remained stable and produced enough oxygen to maintain a predominantly aerobic environment. The final effluent TSS and BOD concentrations were not very low for retention times of less than 1 week, but this could be attributed to the presence of algae in the final effluent. Filtered effluent BOD and TSS concentrations were very low. For retention times of more than 1 week algae were efficiently removed from the liquid phase by the action of predators and algae flocculation and settling, so that a final effluent with a very low BOD and TSS concentrations was produced.
To maximise the FC removal efficiency the polishing pond was constructed with the objective of approaching a plug flow regime. However, the observed efficiency was well below the expected value for all retention times, which was attributable to imperfections of the flow regime. From tracer studies it was established that the dispersion number was in the range of 0.14 to 0.16, which means that moderate mixing occurred, even though the pond was designed to avoid mixing as much as possible. Also the dead volume fraction ranging from 0.12 to 0.15 was quite considerable. Due to these imperfections the required retention time for an effluent to be used in unrestricted irrigation was produced for a retention time of about 10 days, twice the value of the minimum retention time for a batch or true plug flow pond. Although the plug flow regime could not be approached in practice, the required retention time of 10 days is still very much shorter than the value used in conventional WSPs (20 to 30 days).
Study of impacts of treated wastewater to the Krka river, Slovenia
Authors: Cotman M. , Zagorc-Koncan J. , Droic A. 
Published: May 2018

Surface waters are used for disposal of treated effluents from wastewater treatment plants. These effluents usually contain only small amounts of various contaminants but these harmful components accumulate over time in the river, especially in sediments.
An integrated approach for the evaluation of the impact of treated effluents was used to predict an ecological risk assessment to the Krka river beside Novo Mesto. The effluents from pharmaceutical and municipal wastewater treatment plants were discharged too closely into the receiving stream, so that separate impacts could not be distinguished. Biologically treated industrial effluents contained great amounts of barely biodegradable organic pollution, organic nitrogen, ammonia and phosphorus, and sometimes zinc. The toxicity of effluents was mostly dependent on their chemical composition. The municipal discharge contained greater amounts of organic pollution that was completely biodegraded but still had a great nutrient pollution load. The effluents were nontoxic. The harmful substances from the effluents were traced in the river. In the downstream site slightly higher concentration of organic pollutants, organic nitrogen, phosphorus, and zinc were detected due to discharges. The river water was over-saturated with oxygen, especially in the summer. In toxicity tests, samples of the river water were nontoxic. Sediments at the downstream site accumulated from discharged organic nitrogen, phosphorus, or zinc.
The results of our study show that the main problem is eutrophication of the river Krka, so it is obvious we must reduce the quantity of nutrients in the effluents from wastewater treatment plants. In both effluents it will be necessary to reduce the polluting load of phosphorus, the limiting element for growth of algae and macrophytes in the receiving stream. In the industrial effluent it will be necessary to reduce substances which cause toxicity, such as zinc and nonbiodegradable organic compounds that may be accumulated in the water ecosystem over time.