bluuebunny/crossref_metadata_2025 huggingface dataset:
Remote sensing and GIS integration for land cover analysis, a case study: Bozcaada Island
Authors: Bektas F. , Goksel C.
Published: May 2018

In this study, remote sensing and geographic information system (GIS) techniques were used in order to accomplish land cover change of Bozcaada Island, Turkey, by using multitemporal Landsat Thematic Mapper data. Digital image processing techniques were conducted for the processes of image enhancement, manipulation, registration and classification for land cover change analysis. The land cover changes between two different dates were visualized and analyzed by using Geographic Information System techniques. The results showed that remotely sensed data and GIS are effective and powerful tools for carrying out changes on land cover of the island and monitoring of its impact on the environment.
Bioflocculent algal–bacterial biomass improves low-cost wastewater treatment
Authors: Gutzeit G. , Lorch D. , Weber A. , Engels M. , Neis U.
Published: May 2018

An innovative technology for the biological treatment of wastewater in regions with sufficient solar radiation based on the simultaneous growth and degradation processes of algal and bacterial biomass is presented. The aim of the work is the improvement of pond technology through the formation of stable algae–bacteria aggregates, which a) permit a simple separation of the algal biomass by gravity sedimentation, b) enable a high removal efficiency for organic carbon and nutrients, and c) are independent in terms of oxygen provision through algal photosynthesis. Algae–bacteria aggregates could be developed with a suitable algal species (Chlorella vulgaris, Strain Hamburg) as a ‘model organism’ in a wastewater environment. The morphology of algal–bacterial flocs is similar to activated sludge flocs. They are stable and settle quickly. Floc size ranged between 400 and 800μm. Results of our experiments with an artificially irradiated lab-scale system, operated in continuous flow mode, revealed that even at a relatively short hydraulic detention time of two days, a high elimination capacity of 9.96g Nm−2d−1 and 0.87g Pm−2d−1 can be achieved. Recent investigations confirmed that floc formation of unicellular algae and wastewater bacteria also could be developed and maintained in a pilot-scale system with a water depth of 0.5m.
Twenty years' monitoring of Mèze stabilisation ponds: part II – removal of faecal indicators
Authors: Brissaud F. , Andrianarison T. , Brouillet J.L. , Picot B.
Published: May 2018

The WSP system serving Mèze and Poussan (French Mediterranean coast) was constructed in 1980 and enlarged and upgraded from 1994 to 1998. Water quality along the waste stabilisation pond to (WSP) system has been monitored over the years, thus allowing us to assess the influence of enlargement and upgrading works. A significant enhancement of the average microbiological quality of the effluent was observed, with respective E. coli and streptococci average abatements of 4.1 and 3.4 log. units. Former seasonal variations of microbiological removal have vanished. The contribution of the different ponds to the disinfection performance of the WSP system was analysed. A microbiological quality model was proposed to evaluate the die-off kinetics related to the different ponds and as a tool for the design and management of WSP systems. Though the relationships between die-off coefficients and environmental factors appeared somewhat frail, this modelling is considered a promising approach for the prediction of WSP microbiological performance.
A performance review of small German WSPs identifying improvement options
Authors: Barjenbruch M. , Erler C.
Published: May 2018

Natural methods such as lagoon plants are often a reasonable and economically interesting alternative to the technically intensified methods, particularly in rural areas with connection sizes up to a maximum of 5,000 PE. In the last 30 years, numerous analyses yielded information about the biological degradation in natural wastewater treatment plants, on the basis of which respective directives were created. Lately, there are reports that in rural areas of Germany there are a large number of older, mostly unaerated wastewater ponds which cause problems with the observation of the effluent values. This report will give some reasons for non-efficient purification performance (unsuitable design of the ponds, incomplete mixing of aerated ponds, insufficient maintenance, sludge removal etc.). After presenting some operational results several methods of optimisation will be discussed (efficient sludge removal, optimisation of the flow behaviour, combination with a technical step, etc.). Some examples like re-construction into a SBR system are presented at the end.
Urban water tariff structure and cost recovery opportunities in India
Authors: Singh M.R. , Upadhyay V. , Mittal A.K.
Published: May 2018

Given the high level of capital investment and the history of government subsidized services, full cost pricing of water services has yet to take hold in India. As a result, it remains broadly underpriced leading to public perception that water is “free”

The current tariff levels in India are too low to cover even operating costs. This paper examines the existing Indian urban water tariff models (fixed tariff, volumetric tariff, increasing block tariff etc.), their relevance and problems. It was found that none of the tariff structures could satisfy all the design objectives (cost recovery, economic efficiency, equity, affordability etc.). Also subsidies are not explicit and well targeted for poor population. There are several studies and issues that do demonstrate the opportunities for tariff increase and improved cost recovery. This paper highlights the results of such studies and brings out issues needing consideration. Improved cost recovery would lead to improved financial status of the water utilities. Also, subsidies, if designed suitably and well targeted, would serve the concerns of the economically weaker sections. Such reform process would eventually lead to socio-economic sustainability.
Development of water quality models for supporting NH3-N control in a dam regulated river
Authors: Chung S.W. , Kim J.H.
Published: May 2018

A seasonal occurrence of high ammonia nitrogen (NH3-N) concentrations has hampered chemical treatment processes of a water plant in Geum river of Korea. Monthly flow allocation from upstream dam is important for downstream NH3-N control. In this study, water quality models based on multiple regression (MR) and artificial neural network (ANN) methods were developed to support dam operations through providing forecasted NH3-N concentrations. The models were calibrated with 7 years of monthly data, and verified with another 3 years of independent data. In the models, the NH3-N concentration for next time step is dependent on dam outflow, river water quality such as alkalinity, temperature, and NH3-N of previous time step. During the calibration phase, the ANN models compared to MR models showed a better agreement with observed data as indicated with small RMSE and high R2 values. However, in the verification phase, the performance of ANN models was decreased and showed a little difference to MR models. From the model comparisons, it is recommended for both ANN and MR models to include the autocorrelation of NH3-N concentrations up to 3-lag months to avoid overestimation during low flow season.
Removal of E. coli and helminth eggs in UASB: polishing pond systems in Brazil
Authors: von Sperling M. , Bastos R.K.X. , Kato M.T.
Published: May 2018

Ponds following anaerobic reactors, such as Upflow Anaerobic Sludge Blanket (UASB) reactors, have been termed polishing ponds in the literature. The present paper analyses the removal of E. coli and helminth eggs in five UASB–polishing pond systems in Brazil. Since there were ponds in series, the total number of ponds was 10. The ponds had average retention times varying from 2 to 21 days, and depths ranging from 0.40 to 2.00 m. The shallow ponds in series, even with low retention times, were able to produce effluents complying with the coliform WHO guidelines for unrestricted irrigation (≤1000 MPN/100 ml). An equation for the coliform decay coefficient was proposed: Kb (dispersed flow)=0.710 H−0.955 (20 °C). The equation highlights the inverse relationship between the pond depth and the decay coefficient. All polishing pond systems were able to produce effluents with helminth eggs concentrations predominantly equal to zero, and satisfying the WHO guidelines for unrestricted and restricted irrigation (≤1 egg/L, arithmetic mean). The approximate range of helminth eggs removal efficiency was predicted satisfactorily.
Benchmarking management of sewer systems: more to learn than cost effectiveness
Authors: Beenen A.S.
Published: May 2018

Thirty-nine municipalities in the Netherlands conducted a pilot study to develop and try out a methodology to compare the quality of their sewerage management. The participants chose a multidimensional benchmarking with an emphasis on the aim of improving the working processes within sewerage management. A second goal was accountability to the stakeholders. The benchmarking methodology was based as well on analysing data within a “balanced-score-card” system as on intensive exchange of knowledge and experiences. The pilot resulted in a state of the art overview of the quality of sewerage management in the Netherlands. However, above all, it resulted in the shocking fact that the work is carried out in many different ways which cannot be explained by technical reasons or local circumstances. To pinpoint best practices and actually implement these improvements the learning process must continue after the analysis and presentation of the data. A start has been made to form regional specialist networks for further discussion and exchange of experiences.
Mosquito development and biological control in a macrophyte-based wastewater treatment plant
Authors: Noumsi I.M. Kengne , Akoa A. , Eteme R. Atangana , Nya J. , Ngniado P. , Fonkou T. , Brissaud F.
Published: May 2018

A one-year study of the proliferation of mosquito in a Pistia stratiotes-based waste stabilization ponds in Cameroon revealed that Mansonia and Culex were the main breeding genera with about 55% and 42% of the total imagoes respectively. Though the ponds represent a favorable breeding ground for mosquitoes, only 0.02% of captured imagoes was Anopheles gambiae, suggesting that this wastewater treatment plant does not significantly contribute to the development of the malaria vector in the area. Gambusia sp. introduced to control mosquito population in the ponds acclimatized relatively well in most of the ponds (B3–B7) and their feeding rate without any diet ranged from 15.0 to 50.2 larvae/day for a single fish.
Municipal wastewater treatment with pond–constructed wetland system: a case study
Authors: Wang X. , Bai X. , Qiu J. , Wang B.
Published: May 2018

The performance of a pond–constructed wetland system in the treatment of municipal wastewater in Kiaochow city was studied; and comparison with oxidation ponds system was conducted. In the post-constructed wetland, the removal of COD, TN and TP is 24%, 58.5% and 24.8% respectively. The treated effluent from the constructed wetland can meet the Chinese National Agricultural and Irrigation Standard. The comparison between pond–constructed wetland system and oxidation pond system shows that total nitrogen removal in a constructed wetland is better than that in an oxidation pond and the TP removal is inferior. A possible reason is the low dissolved oxygen concentration in the wetland. Constructed wetlands can restrain the growth of algae effectively, and can produce obvious ecological and economical benefits.
Metabolic interactions in methanogenic and sulfate-reducing bioreactors
Authors: Stams A.J.M. , Plugge C.M. , de Bok F.A.M. , van Houten B.H.G.W. , Lens P. , Dijkman H. , Weijma J.
Published: May 2018

In environments where the amount of electron acceptors is insufficient for complete breakdown of organic matter, methane is formed as the major reduced end product. In such methanogenic environments organic acids are degraded by syntrophic consortia of acetogenic bacteria and methanogenic archaea. Hydrogen consumption by methanogens is essential for acetogenic bacteria to convert organic acids to acetate and hydrogen. Several syntrophic cocultures growing on propionate and butyrate have been described. These syntrophic fatty acid-degrading consortia are affected by the presence of sulfate. When sulfate is present sulfate-reducing bacteria compete with methanogenic archaea for hydrogen and acetate, and with acetogenic bacteria for propionate and butyrate. Sulfate-reducing bacteria easily outcompete methanogens for hydrogen, but the presence of acetate as carbon source may influence the outcome of the competition. By contrast, acetoclastic methanogens can compete reasonably well with acetate-degrading sulfate reducers. Sulfate-reducing bacteria grow much faster on propionate and butyrate than syntrophic consortia.
Fundamentals of the fermentative production of hydrogen
Authors: Hallenbeck P.C.
Published: May 2018

The molecular details behind hydrogen evolution during fermentation are reviewed. Hydrogen is evolved by hydrogenase, a class of enzymes containing complex metallo-centers. In most cases, sugars are degraded to pyruvate which in turn is converted to a variety of fermentation products. Various pathways leading to fermentative hydrogen generation are outlined and discussed. Thermophilic fermentations have higher yields than mesophilic ones. Yields are thought to be limited to 4H2 per glucose under standard conditions. The highlights of some actual studies of fermentations are presented and ways of potentially increasing hydrogen yields are discussed. It may be possible to achieve higher hydrogen yields by carrying out fermentations under microaerobic conditions where limited respiration could provide additional reducing power to drive the nearly complete conversion of sugar substrates to hydrogen.
The efficacy of ozone as a pre- and post-treatment option for UASB-treated food processing wastewaters
Authors: Sigge G.O. , Britz T.J. , Fourie P.C. , Barnardt C.A.
Published: May 2018

The efficiency of ozone as a pre- and post-treatment to UASB treatment was investigated, followed by a study into UASB reactor performance with ozonated wastewater as substrate. Combinations of pre- and/or post-ozonation with UASB treatment gave better results than ozonation or UASB alone and COD reductions of 53.0–98.9% were achieved for treatment of canning and winery wastewaters. A UASB reactor was fed with pre-ozonated cannery wastewater for over 70 d. COD removal improved from between 58.8 and 64.4% to between 85.3 and 91.8% after pre-ozonated substrate feed commenced. Subsequent increases in organic loading rate (OLR) from 2.4 to 3.4 kgCOD m−3.d−1 did not affect reactor performance. By including a final post-ozonation treatment to this UASB effluent a total COD reduction of 99.2% was achieved.
Assessment of electrochemical and chemical coagulation as post-treatment for the effluents of a UASB reactor treating cellulose pulp mill wastewater
Authors: Buzzini A.P. , Motheo A.J. , Pires E.C.
Published: May 2018

This paper presents results from exploratory experiments to test the technical feasibility of electrolytic treatment and coagulation followed by flocculation and sedimentation as post-treatment for the effluent of an UASB reactor treating simulated wastewater from an unbleached Kraft pulp mill. The electrolytic treatment provided up to 67% removal of the remaining COD and 98% of color removal. To achieve these efficiencies the energy consumption ranged from 14 Wh.l−1 to 20 Wh.l−1. The coagulation-flocculation treatment followed by settling required 350–400 mg.l−1 of aluminium sulfate. The addition of a high molecular weight cationic polymer enhanced both COD and color removal. Both post-treatment processes are technically feasible.
Solving fecal coliform growth/reactivation in biosolids during full-scale post-digestion processes
Authors: Iranpour R. , Palacios R. , Cox H.H.J. , Abkian V.
Published: May 2018

Fecal coliform recurrence has been observed at the City of Los Angeles Hyperion Treatment Plant during pilot-scale experiments with a designated thermophilic battery of six anaerobic digesters, while other digesters were still at a mesophilic temperature. Several lab and full-scale experiments indicated the following possible causes of the growth/reactivation of fecal coliforms in post-digestion: a) contamination of thermophilically digested biosolids with mesophilically digested biosolids; b) a large drop in the biosolids temperature between the centrifuges and silos, which could have allowed the reactivation and/or growth of fecal coliforms. These were resolved by the full plant conversion to thermophilic anaerobic digestion and design modifications of the post-digestion train.
Leachate pre-treatment strategies before recirculation in landfill bioreactors
Authors: Vigneron V. , Bouchez T. , Bureau C. , Mailly N. , Mazeas L. , Duquennoi C. , Audic J.M. , Hébé I. , Bernet N.
Published: May 2018

Nitrified leachate recirculation represents a promising strategy for a more sustainable landfill management. Our objective was to determine the reactions involved in nitrate reduction in municipal solid waste batch biodegradation tests. Anaerobic digestion of waste in the three control reactors showed a good reproducibility. In two test reactors, nitrate was added at various moments of the waste degradation process. We observed that: (1) H2S concentration controlled the nitrate reduction pathway: above a certain threshold of H2S, dissimilatory nitrate reduction to ammonium (DNRA) replaced denitrification. (2) N2O/N2 ratio varied with the organic carbon concentration: the lower the easily biodegradable carbon concentration, the higher the N2O/N2 ratio. (3) N2 was consumed after denitrification. The possibility of a nitrogen fixation reaction in the presence of NH4+ is discussed. Nitrified leachate recirculation during acidogenesis should be avoided because of higher H2S production which could induce DNRA.
Treatment of municipal wastewater UASB reactor effluent by unconventional flotation and UV disinfection
Authors: Tessele F. , Monteggia L.O. , Rubio J.
Published: May 2018

Post-treatment of an UASB reactor effluent, fed with domestic sewage, was conducted using two-stage flotation and UV disinfection. Results were compared to those obtained in a parallel stabilisation pond. The first flotation stage employed 5–7.5 mg L−1 cationic flocculant to separate off more than 99% of the suspended solids. Then, phosphate ions were completely recovered using carrier flotation with 5–25 mg L−1 of Fe (FeCl3) at pH 6.3–7.0. This staged flotation led to high recoveries of water and allowed us to separate organic matter and phosphate bearing sludge. The water still contained about 1 × 102 NMP/100 mL total coliforms, which were removed using UV radiation to below detection levels. Final water turbidity was <1.0 NTU, COD <20 mg L−1 O2 and 71 mNm−1, the liquid/air interfacial tension. This flotation-UV flowsheet was found to be more efficient than the treatment in the stabilisation pond and appears to have some potential for water reuse. Results were discussed in terms of the biological, chemical and physicochemical mechanisms involved.
Reductive decolourisation of azo dyes by mesophilic and thermophilic methanogenic consortia
Authors: Cervantes F.J. , dos Santos A.B. , de Madrid M.P. , Stams A.J.M. , van Lier J.B.
Published: May 2018

The contribution of acidogenic bacteria and methanogenic archaea on the reductive decolourisation of azo dyes was assessed in anaerobic granular sludge. Acidogenic bacteria appeared to play an important role in the decolourising processes when glucose was provided as an electron donor; whereas methanogenic archaea showed a minor role when this substrate was supplemented in excess. In the presence of the methanogenic substrates acetate, methanol, hydrogen and formate, methane production became important only after colour was totally removed from the batch assays. This retardation in methane production may be due to either a toxic effect imposed by the azo dyes or to the competitive behaviour of azo dyes to the methanogenic consortia for the available reducing equivalents.
Microbial sulphate reduction during anaerobic digestion: EGSB process performance and potential for nitrite suppression of SRB activity
Authors: O'Reilly C. , Colleran E.
Published: May 2018

The present study investigated mesophilic anaerobic treatment of sulphate-containing wastewater in EGSB reactors and assessed the inclusion of nitrite in the reactor influent as a method for control of biological sulphate reduction. Two EGSB reactors, R1 and R2, were operated for a period of 581 days at varying volumetric loading rates, COD/SO42− ratios and influent nitrite concentrations (R2 only). COD removal efficiencies of >93% were achieved in both reactors at influent sulphate concentrations of up to 3,000 mg l−1. A two-fold increase in the influent sulphate concentration, giving an influent COD/SO42− ratio of 2, resulted in a reduction in reactor COD removal efficiency to 84% and 89%, in R1 and R2, respectively. Despite inclusion of nitrite in the R2 influent at concentrations up to 500 mg NO2-N l−1, sulphate reduction proceeded similarly in R2 and R1, suggesting the ineffectiveness of nitrite as a potential inhibitor of SRB activity.
Anaerobic digestion as a sustainable solution for biosolids management by the Montreal Metropolitan Community
Authors: Frigon J.C. , Guiot S.R.
Published: May 2018

The Quebec Waste Management Policy (1998–2008) is requesting that the municipalities prepare a waste management plan, including a global objective of 60% of these wastes to be diverted from landfill sites by reduction, re-usage, recycling and valorization. Around 5.8 million tons of wastes were generated on the territory of the Montreal Metropolitan Community in 2001 for a population of about 3.5 millions citizens. In this paper, we present different management scenarios in which anaerobic digestion was used as a valorization step, focusing on the energetic value of the methane produced and the reduction in greenhouse gas (GHG) emissions. The four scenarios prepared cover the valorization of the organic fraction of municipal solid wastes, green wastes and excess sludge and showed potential methane generation of 17–140 Mm3 with a GHG reduction of 62,000–500,000 tons of CO2-equivalents.
Simulation supported scenario analysis for water resources planning: a case study in Northern Italy
Authors: Facchi A. , Gandolfi C. , Ortuani B. , Maggi D.
Published: May 2018

The work presents the results of a comprehensive modelling study of surface and groundwater resources in the Muzza–Bassa Lodigiana irrigation district, in Northern Italy. It assesses the impact of changes in land use and irrigation water availability on the distribution of crop water consumption in space and time, as well as on the groundwater resources. A distributed, integrated surface water-groundwater simulation system was implemented and applied to the study area. The system is based on the coupling of a conceptual vadose zone model with the groundwater model MODFLOW. To assess the impact of land use and irrigation water availability on water deficit for crops as well as on groundwater system in the area, a number of management scenarios were identified and compared with a base scenario, reflecting the present conditions. Changes in land use may alter significantly both total crop water requirement and aquifer recharge. Water supply is sufficient to meet demand under present conditions and, from the crop water use viewpoint, a reduction of water availability has a positive effect on the overall irrigation system efficiency; however, evapotranspiration deficit increases, concentrated in July and August, when it may be critical for maize crops.
Assessment of the spatial heterogeneity of weathering rates in upland catchments using the sodium dominance index and its significance in integrated catchment management
Authors: Smart R.P. , Cresser M.S. , Dahl D. , Clarke M.J.
Published: May 2018

The sodium dominance index was developed to quantify weathering rates and critical loads in Scotland, where atmospheric aerosols of maritime origin dominate over biogeochemical weathering in providing base cation inputs to catchment soils and drainage waters. High sodium dominance in river or lake water indicates low weathering rate. Here, this concept is evaluated using intensive temporal and spatial sampling strategies in two substantial catchments, one in Scotland and the other in central England, with particular reference to detection of groundwater inputs, and to possible problems from road salting in the calibration. In the Dee network, the spatial distribution of sodium dominance reflects the distribution of soil parent material geology, but land use also influences the equations. It is postulated that road density, via winter road salting, influences the sodium dominance calibration in lowland agricultural areas. Although road salting can also be problematic in some upland areas, the index still can provide clear indication of the likely severity of acid flush events in remote upland streams. In the Etherow catchment, sodium dominance varies markedly, sometimes over relatively small distances, reflecting soil type distribution, the occurrence of ground-water inputs to streams, and the influence of water in tributaries above the sampling point.
Including non-point sfources in a water quality trading permit program
Authors: Collentine D.
Published: May 2018

There has been overwhelming interest in addressing water quality issues through the use of economic instruments. Much of this attention has focused on the cost efficiencies offered by Transferable Discharge Permit (TDP) systems. Unfortunately, the attempts to start up permit markets which are able to exploit abatement cost differences between sources have not met with the success expected. Two of the reasons for the lack of success that have been taken up in analysis of these programs have been the problem of transaction costs and in the case of non-point sources (NPS), undefined property rights. The composite market design is a proposal for a TDP system which specifically includes agricultural non-point source (NPS) dischargers and addresses both property rights and transaction cost problems. The composite market consists of three interrelated markets each serving a particular function. When the composite market is mature, the total number of permits issued represents the cap on discharges allowed in the catchment. The structure of the composite market allows this system to be phased in over time with existing institutions and limited demands on financing.
Buffer zones as a sink for sediment and phosphorus between the field and stream: Danish field experiences
Authors: Kronvang B. , Laubel A. , Larsen S.E. , Andersen H.E. , Djurhuus J.
Published: May 2018

Rill erosion, surface runoff and storage of sediment and phosphorus in buffer zones were investigated during three winters on ca. 140 arable field slope units in twenty places in Denmark covering all landscape types, climate gradients and dominant soil types. The dominant soils are Alfisols and Spodosols, with textural composition typically ranging from sand to loam. The average slope is 7% (range: 2–20%) and median buffer zone width was 8.3 m (range: 0.6–125 m). The geometric mean annual rill erosion was 0.33 m3 ha−1 equalling to 495 kg sediment ha−1 and 0.25 kg P ha−1. The deposition of sediment on the field, in the buffer zone and delivery of soil to the stream was surveyed within the 140 slope units following three winters. Deposition of sediment in the buffer zone was observed in 31% (1997/98), 31% (1998/99) and 29% (1999/2000) of the slope units. Delivery of soil across the edge of the stream was observed in 23% (1997/98), 17% (1998/99) and 25% (1999/2000) of the 140 slope units. Median dissolved P concentration in surface runoff was 0.18 mg P l−1 (range: 0.029–16.294 mg P l−1). A probability model was developed to predict the efficiency of different widths of buffer zones.
The impact of bird populations on the microbiological quality of bathing waters
Authors: Wither A. , Rehfisch M. , Austin G.
Published: May 2018

To ensure optimum quality at Bathing Waters, the control of diffuse sources of bacterial contamination is receiving increasing attention. As part of an initiative to improve the quality of the EU designated bathing waters on the Fylde Coast (North West England), a project was undertaken to quantify the faecal indicator load from birds and assess the significance on water quality. High bird counts are encountered on the Fylde Coast with gulls, feral pigeons and starlings being prominent. The piers at Blackpool make an attractive roost for starlings with numbers peaking at over 30,000 in late summer. Systematic recording of bird numbers and locations was undertaken during 2001/2. Estimates were also made of the daily faecal organism production by the different species. The spatial distribution of faecal organisms from the bird population was statistically linked to synoptic water quality data. This allowed estimates to be made of the contribution from birds to the faecal pollution load at the bathing waters. The work confirmed a statistically significant link between bird populations and water quality with a marked seasonal bias.
GIS-based influence analysis of geomorphological properties on pollutant wash-off in agricultural area
Authors: Bae M.S. , Ha S.R.
Published: May 2018

This study improves the estimation of the self-purification coefficient for runoff analysis of pollution load using geomorphological factors. Formerly, the assimilative capacity, K, was estimated using a single geomorphological factor, Horton's form ratio, Sf. Here, K was divided into two factors, namely, a watershed self-purification coefficient (k) and a watershed form ratio (Sf). The watershed form ratio, Sf, is the equivalent stream density and is considered an index of accessibility of the pollution load to the water body. Even though Sf had shown a clear reciprocal relationship with k, in agricultural areas, there is a limitation that the k, estimated by using an Sf only can't reflect the variability of land coverage characteristics and/or land use. In this study, a new geo-characteristic index (GCI), SR, which is composed of Sf and weighted flow accumulation ratio (Fr), is suggested. GIS and remote sensing technique were used to calculate Sf and Fr. Interestingly, a clear reciprocal relationship exists between k and SR, and this relationship seems to be stronger for agricultural areas, as urbanized areas have easier wash off due to the sewer network or paved surfaces.
Modelling nitrate losses from agricultural activities on a national scale
Authors: Dunn S.M. , Vinten A.J.A. , Lilly A. , DeGroote J. , McGechan M.
Published: May 2018

The Nitrogen Risk Assessment Model for Scotland (NIRAMS) has been developed as a screening tool for prediction of streamwater N concentrations draining from agricultural land in Scotland. The objective of the model is to be able to predict N concentrations for ungauged catchments, to fill gaps in monitoring data and provide guidance in relation to policy development. The model uses national land use, soils and meteorology data sets and has been developed within an ArcView GIS user interface. The model includes modules to calculate N inputs to the land, residual N remaining at the end of the growing season, weekly time-series of leached N and transport of N at the catchment scale. The N leaching and transport are controlled by hydrological modules, including a national water balance model and a catchment scale transport model. Preliminary testing of NIRAMS has been carried out on eight Scottish catchments, diverse in terms of geographic location as well as land use. The model is capable of predicting the correct mean level of stream N concentrations, as well as the basic characteristics of seasonal variation. As such the model can be of value for providing estimates of N concentrations in ungauged areas.
Incorporating uncertainty into predictions of diffuse-source phosphorus transfers (using readily available data)
Authors: Murdoch E.G. , Whelan M.J. , Grieve I.C.
Published: May 2018

Phosphorus (P) is a limiting nutrient in many freshwater ecosystems and increases in its availability can lead to eutrophication. Effective management of P in freshwaters requires quantitative estimates of P supply from all significant sources. A simple GIS-based model, capable of predicting total diffuse source phosphorus export from catchments using readily available data, has been developed. The model is based on the idea of export coefficients but includes the effects of topography (slope and cumulative area), soil type (using the UK Hydrology of Soil Types (HOST) classification) and climate (hydrologically effective rainfall) as well as land use. Uncertainty in key model parameters is accounted for using Monte Carlo simulation which involves random sampling from probability density functions in a large number of iterations. This reduces the need for subjective optimisation of export coefficients. The model has been applied to the Greens Burn catchment, Scotland and predicts P exports within the confidence limits of the measured values.
Quantitative analysis of biological effect on membrane fouling in submerged membrane bioreactor
Authors: Cho J. , Song K.G. , Yun H. , Ahn K.H. , Kim J.Y. , Chung T.H.
Published: May 2018

The objective of this study is to investigate solids concentration and extracellular polymeric substance (EPS) effects on the membrane fouling in the submerged membrane bioreactor. The relationship between the solids retention time (SRT) and the amount of EPS is observed in three lab-scale MBRs. Additionally, the EPS effect on membrane fouling is quantified by calculating the specific cake resistance (α) using an unstirred batch cell test. By observing the sludge over a long period under various SRT scenarios, a wide range of EPS and membrane fouling data is obtained. These observations provide sufficient evidence of the functional relationship between SRT, EPS and α. As SRT decreases, the amount of EPS bound in sludge floc becomes higher in the high MLSS condition (>5,000 mg/L). The amount of EPS in the sludge floc has positive influence on α. A sigmoid trend between EPS and α is observed and the functional relationship obtained by dimensional analysis is consistent with the experimental results.
Membrane fouling and selectivity mechanisms in effluent ultrafiltration coupled with flocculation
Authors: Soffer Y. , Ben Aim R. , Adin A.
Published: May 2018

Membrane filtration is adequate for producing disinfected clear water suitable for various kinds of applications. However, fouling of membranes is the main limitation. The scope of the present study is to examine the effect of iron coagulation of primary wastewater effluent on membrane filtration, in parallel to fouling characterization of the iron itself. The fouling of ultrafiltration membranes by colloidal iron hydroxide-oxide has been studied by measuring the pore streaming potential of PES UF membrane. pH 5.5 (charge neutralization zone) provided better removal and lower fouling intensity than pH 7.8 (sweep coagulation zone), but the internal clogging at acidic pH was higher. Fouling of the membrane as measured by flux reduction was usually accompanied by a positive change in zeta potential and iso-electric point (IEP) of the membrane. An initially large change in zeta potential (without charge reversal) was seen even after relatively small amounts of iron solution were filtered through the membrane. A control experiment showed this is not due to iron adsorption equilibrium, but should probably be attributed to fouling. Change in zeta potential, can be used as an indicator for commencement of fouling even for small flux reductions. UF membrane critical flux after iron filtration can be evaluated more accurately by zeta potential than pressure drop or change in iron concentration.
Development of a hybrid ozonation biofilm-membrane filatration process for the production of drinking water
Authors: Leiknes T. , Lazarova M. , Ødegaard H.
Published: May 2018

Drinking water sources in Norway are characterized by high concentrations of natural organic matter (NOM), low alkalinity and low turbidity. The removal of NOM is therefore a general requirement in producing potable water. Drinking water treatment plants are commonly designed with coagulation direct filtration or NF spiral wound membrane processes. This study has investigated the feasibility and potential of a hybrid process combining ozonation and biofiltration with a rotating disk membrane for treating drinking water with high NOM concentrations. Ozonation will oxidize the NOM content removing colour and form biodegradable organic compounds, which can be removed in biological filters. A constructed water was used in this study which is representative of ozonated NOM-containing water. A rotating membrane disk bioreactor downstream the ozonation process was used to carry out both the biodegradation as well as biomass separation in the same reactor. Maintenance of biodegradation of the organic matter while controlling biofouling of the membrane and acceptable water production rates was the focus in the study. Three operating modes were investigated. Removal of the biodegradable organics was consistent throughout the study indicating that sufficient biomass was maintained in the reactor for all operating conditions tested. Biofouling control was not achieved through shear-induced cleaning by periodically rotating the membrane disks at high speed. By adding a small amount of sponges in the membrane chamber the biofouling could be controlled by mechanical cleaning of the membrane surface during disk rotation. The overall results indicate that the system can favorably be used in an ozonation/biofiltration process by carrying out both biodegradation as well as biomass separation in the same reactor.
Performance comparison of a pilot-scale membrane bioreactor and a full-scale sequencing batch reactor with sand filtration: treatment of low strength wastewater from a northern Canadian Aboriginal Community
Authors: Frederickson K. , Cicek N.
Published: May 2018

Northern Aboriginal communities in Canada suffer from poor wastewater treatment. Treatment systems on 75% of Manitoban Aboriginal communities produce substandard effluent despite the presence of sophisticated treatment systems. A 200-litre, pilot-scale membrane bioreactor (MBR) was established on the Opaskwayak Cree Nation to investigate the feasibility of MBRs in mitigating Aboriginal wastewater treatment issues. The pilot system was remote controlled and monitored via the Internet using the program pcAnywhere. The community utilized two existing sequencing batch reactors (SBR) and three sand filters for wastewater treatment. The community wastewater was relatively weak and highly fluctuating which led to poorly settling sludge that readily fouled the sand filters. A comparison study between the MBR and SBR was undertaken from September to December 2003. Operated at a 10-hour hydraulic retention time and 20-day solids residence time, the MBR outperformed the SBR and sand filtration on BOD and suspended solids removal. Furthermore, the MBR showed high levels of nitrification despite relatively cold water temperatures.
Limitations of ASM1 and ASM3: a comparison based on batch oxygen uptake rate profiles from different full-scale wastewater treatment plants
Authors: Guisasola A. , Sin G. , Baeza J.A. , Carrera J. , Vanrolleghem P.A.
Published: May 2018

The two most popular models for the description of the biological COD removal are ASM1 and ASM3. However, some numerical inconsistencies arise when using these models to interpret the data obtained in short-term respirometric batch experiments. In this study, both models are fitted to four different respirometric batch profiles obtained with biomass from different WWTP. The parameter estimation results and the practical (local) identifiability are analysed, and the limitations of both models are discussed. The growth yield obtained by fitting ASM1 to the short-term respirometric batch profiles is higher than the default one, as well as the storage yield obtained by fitting ASM3 is lower than the default one. Based on these values, possible improvements to the modelling of the biological COD removal, such as the inclusion of simultaneous growth and storage on external substrate, are proposed.
High Performance Biofilm Process for Treating Wastewater Discharged from Coal Refining Plants Containing Nitrogen, Cyanide and Thiocyanate
Authors: Jeong Y. , Park B.-G. , Chung J.S.
Published: May 2018

Wastewater discharge from coal refining plants contains a number of biologically toxic compounds; 2000–2500mg/l of COD of which 40% is composed of phenol, 100–400mg/l of thiocyanate, 10–40mg/l of cyanide, 100–250mg/l of NH4+-N and 150–300mg/l of total nitrogen. In order to treat this kind of high strength wastewater, we have developed a high performance biofilm process using fluidizing bio-carriers of the tube chip type. The fluidizing biofilm carriers are made of a composite of polyethylene and several inorganic materials, whose density is controlled at 0.97–0.98g/ml. The fluidizing biofilm carriers show sound fluidization characteristics inside bioreactors. The wastewater is treated using three consecutive series reactors in oxic–anoxic–oxic arrangement. Each reactor is charged with the fluidizing biofilm carriers of 50 vol%. Furthermore, newly cultured active microorganisms for the thiocyanate biodegradation are added in the biofilm process. At total hydraulic retention time of 2.2 days, this process can achieve steady state removal efficiencies: COD, 99%; thiocyanate, 99%; NH4+-N, 99% and total nitrogen, 90%.
Simultaneous nitrification and de-nitrification in MBR
Authors: Wang B. , He S. , Wang L. , Shuo L.
Published: May 2018

Experiments have been carried out to get an understanding of the effect of DO, C/N ratio and pH on the performance of a bench scale membrane bioreactor (MBR) in simultaneous nitrification and de-nitrification. It was found that under the conditions of MLSS in the range of 8000–9000mg/L and temperature of water in the MBR of 24°C, influent COD and NH3-N in the range of 523–700mg/L and 17.24–24mg/L respectively, the removals of COD, NH3-N and TN were 98%,99% and 60%; 96.5%,98% and 75%; 96%,95% and 92%; 90%,70% and 60% respectively at DO of 6, 3, 1 and 0.5mg/L. It was also found that the changes in C/N ratio and pH in a certain range have a slight effect on COD removal but have significant influence on the removal of NH3-N and TN. The results showed that only under the conditions that each ecological factor was maintained relatively steadily, simultaneous nitrification and de-nitrification proceeded smoothly. It was found that when C/N ratio was 30, the influent pH 7.2, the temperature of water in MBR 24°C and DO 1mg/L, as optimum conditions, the removals of COD, NH3-N and TN were 96%, 95% and 92% respectively. In addition, mechanism research on simultaneous nitrification and de-nitrification in MBR has been conducted as well.
Biological nutrient removal in simple dual sludge system with an UMBR (upflow multi-layer bioreactor) and aerobic biofilm reactor
Authors: Kwon J.-C. , Park H.-S. , An J.-Y. , Shim K.-B. , Kim Y.-H. , Shin H.-S.
Published: May 2018

In this study, a simple dual sludge process was developed for small sewage treatment. It is a hybrid system that consists of upflow multi-layer bioreactor (UMBR) as anaerobic and anoxic reactor with suspended growth microorganisms and post aerobic biofilm reactor with inclined plates. UMBR is a multi-function reactor that acts as primary sedimentation tank, anaerobic reactor, anoxic reactor, and thickener. The sludge blanket in the UMBR is maintained at a constant level by automatic control so that clear water (30mg-SS/L) can flow into the post aerobic biofilm reactor. It leads to improving performance of the biofilm reactor due to preventing of excess microbial attachment on the media surface and no requirment for a large clarifier caused by low solid loading. The HRT in the UMBR and the aerobic biofilm reactor were about 5.8h and 6.4h, respectively. The temperature in the reactor during this study varied from 12.5°C to 28.3°C. The results obtained from this study show that effluent concentrations of TCOD, TBOD, SS, TN, and TP were 29.7mg/L, 6.0mg/L, 10.3mg/L, 12.0mg/L, and 1.8mg/L, which corresponded to a removal efficiency of 92.7%, 96.4%, 96.4%, 74.9%, and 76.5%, respectively. The sludge biomass index (SBI) of the excess sludge in the UMBR was about 0.55, which means that the sludge in the UMBR was sufficiently stabilized and may not require further treatment prior to disposal.
Characteristics of nitrogen removal and microbial distribution by application of spent sulfidic caustic in pilot scale wastewater treatment plant
Authors: Park S. , Lee J. , Park J. , Byun I. , Park T. , Lee T.
Published: May 2018

Publisher‘s note. We regret that the published version of this article erroneously denoted the first author as corresponding author; in fact the formal corresponding author of this paper is Professor Taeho Lee, whose address is repeated below.
Práticas agroecológicas e conhecimentos tradicionais na Chácara Santo Antônio, Cáceres-MT, Brasil
Authors: Santos Thaís Aparecida Coelho , Carniello Maria Antonia , Barros Flávio Bezerra
Published: May 2018

As práticas agroecológicas nos remetem à recuperação dos saberes tradicionais. Com isso, o objetivo este estudo foi investigar o manejo da agrobiodiversidade na Chácara Santo Antônio, Cáceres, MT. Para tanto, empregamos técnicas de história oral, entrevista informal, entrevista não estruturada e observação. Os dados foram registrados por meio de fotografias e diário de campo. Foram registrados uma riqueza de 72 espécies, dos quais 42 são alimentares, 28 medicinais, 10 ornamentais e quatro sem categoria do uso definido. O manejo da agrobiodiversidade é realizado com técnicas simples, robustas e sem muitos custos financeiros, alguns exemplos são: utilização de restos vegetais como adubo, a resistência ao uso do agrotóxico e a origem das sementes, estas geralmente obtidas por troca.
Prospection on Yeasts from Stingless Bees Honey in BrazilianTropical Dry Forest (Caatinga)
Authors: Barbosa Renan Nascimento , Bezerra Jadson , Souza-Motta Cristina , Gomes Bruno Severo , Costa Cynthia , Melo Hélio
Published: May 2018

The richness of the yeasts associated with honey obtained from the stingless bees Melipona mandacaia, M. asilvai, Patarmona sp. and Scaptotrigona sp. living in Brazilian tropical dry forest (Caatinga) was studied. Based on morphological and physiological characters 12 species were identified belonging to the phylum Ascomycota, with eight Candida species. This study has shown that the honey of stingless bees is an important source of yeasts, particularly in tropical dry environments, where the diversity of fungi is still largely unknown.