bluuebunny/crossref_metadata_2025 huggingface dataset:
Start-up of a multi-stage system for biogas production and solid waste treatment in low-tech countries
Authors: Biey E.M. , Musibono E.D. , Verstraete W.
Published: May 2018

Vegetable fruit garden wastes were treated anaerobically using a multistage Dranco system. The digesters were composed of three 50 L vessels kept in mesophilic conditions. They were operating at 14.5-17% TS. By controlling the pH in the system, the start-up for biogas production was shortened to 60 days. The pH correction was a buffering which enhanced methanogenic activity in the digesters. With a loading rate of 4.1 kg VS/m3reactor.day, the production of biogas was 5 m3/m3reactor.day, and 60-70% methane content. This allowed making a multisystem by starting every 3 weeks with new vessels in order to maintain biogas production, to be used in industries or in local communities in low-tech countries. The designed model was started in Kinshasa (Congo) where a project is expected to treat one ton of solid waste on a daily basis, for a production of 100 m3 biogas. This cost effectiveness of the system is demonstrated and presents the opportunity for biowaste treatment coupled with environmental protection and substantial energy recovery.
Establishment of a continuous model system to study Helicobacter pylori survival in potable water biofilms
Authors: Azevedo N.F. , Vieira M. J. , Keevil C.W.
Published: May 2018

Close association of the pathogen Helicobacter pylori in drinking water biofilms has been suggested. Using a two-stage water model, the survival and development of the pathogen in potable water biofilms was monitored. Filter sterilized tap water was used as the growth medium and the inoculum consisted of a naturally occurring consortium of microorganisms. Biofilms were generated on removable stainless steel coupons that were placed in the second vessel. Novel technology peptide nucleic acid (PNA) molecular probes were used to detect and locate the pathogen in the biofilms. The PNA-labelled oligonucleotide probes were highly specific, and complementary to the helix 6 region of H. pylori 16S rRNA. The pathogen was tracked in the biofilms using epifluorescence microscopy and episcopic differential interference contrast microscopy. Results show that H. pylori can successfully incorporate within biofilms and its presence was detected for up to five days after inoculation. PNA probes provided an easy and quick way of performing fluorescence in situ hybridisation assays in heterogeneous biofilms.
Nitrogen removal from domestic effluent using subsurface flow constructed wetlands: influence of depth, hydraulic residence time and pre-nitrification
Authors: Bayley M.L. , Davison L. , Headley T.R.
Published: May 2018

This paper describes two studies into the BOD and TN removal performance of horizontal subsurface flow wetlands (reed beds) in subtropical Australia. The aim of the first study was to determine the influence of HRT and vertical position on BOD and TN concentration and removal performance in a 0.5m deep reed bed (System 1) by taking samples from three levels (or layers) in the water column at five points along the length of the bed. The aim of the second study was to investigate the TN removal performance of a treatment train consisting of a vertical flow intermittently dosed sand filter preceding a reed bed (System 2). Both systems were dosed with primary settled municipal wastewater (BOD 194 mg L-1; TN 49 mg L-1). System 1 achieved a TN load removal of 58% under a HLR of 22 mm day-1 (HRT 10.5 days), producing effluent BOD concentrations consistently less than 8 mg L-1. There was no significant difference in BOD attenuation rate between the three layers. While there were differences in both the nitrification and denitrification rates between the three layers, the TN concentration was found to decline steadily in all layers up to an HRT of 8.7 days. System 2 reduced TN influent load by 33%, less than half of which was removed by the reed bed. The lack of substantial TN removal within this reed bed was attributed to the low concentrations of BOD and consequent lack of dissolved organic carbon to drive the denitrification process.
Image analysis, methanogenic activity measurements, and molecular biological techniques to monitor granular sludge from an EGSB reactor fed with oleic acid
Authors: Pereira M.A. , Roest K. , Stams A.J.M. , Akkermans A.D.L. , Amaral A.L. , Pons M.-N. , Ferreira E.C. , Mota M. , Alves M.M.
Published: May 2018

Morphological changes in anaerobic granular sludge fed with increasing loads of oleic acid were quantified by image analysis. The combination of this technique with data on the accumulation of adsorbed long chain fatty acid and with the molecular characterization of microbial community gave insight into the mechanisms of sludge disintegration, flotation and washout. It was found that the bacterial domain was more affected than the archaeal domain during this process. However, no acetoclastic activity and only a residual hydrogenotrophic activity were detected in the sludge at the end of the operation.
Enrichment and immobilization of quinone-respiring bacteria in anaerobic granular sludge
Authors: Cervantes F.J. , Duong-Dac T. , Roest K. , Akkermans A.D.L. , Lettinga G. , Field J.A.
Published: May 2018

The capacity of an anaerobic granular sludge for serving as an immobilizing mechanism for quinone-respiring bacteria was evaluated. The inoculum was continuously fed with a basal medium containing the humic model compound, anthraquinone-2,6-disulfonate (AQDS), as a terminal electron acceptor. Complete reduction of AQDS was achieved by the granular sludge for a prolonged period in an anaerobic bioreactor provided with a mixture of volatile fatty acids as a substrate. Phylogenetic analysis revealed the enrichment and immobilization of AQDS-respiring bacteria appearing as dominant organisms in the microbial population of the AQDS-supplemented reactor, compared to a reactor control operated under methanogenic conditions. The consistent quinone-reducing capacity observed in the consortium indicates that it is feasible to apply quinone-reducing microorganisms in continuous bioreactors and this ability can potentially be important in wastewaters rich in humic substances. The quinone reducing activity could also be applied to accelerate the conversion of xenobiotics susceptible to reductive biotransformations such as azo dyes and polychlorinated compounds in continuous bioreactors.
Molecular ecology of anaerobic granular sludge grown at different conditions
Authors: Díaz E. , Amils R. , Sanz J.L.
Published: May 2018

Qualitative and quantitative diversity of microorganisms present in anaerobic granular sludges fed with different substrates, as well as the structure of these granules have been studied using fluorescent 16S rRNA-targeted in situ hybridization and electron microscopy. The granules showed a multi-layered structure, in which both densely packed and loose micro-colonies, channels and holes could be observed. Only bacteria were found in the outer shell of the granules, while both archaea and bacteria were detected in the inner core. Although high cell density was found in the granules (more than 1011 cells/gram, determined by DAPI-stain) only a low percentage of cells was able to hybridize with the rRNA-targeted probes. Significant quantitative and qualitative differences were observed in the composition of granules fed with different substrates (formate, acetate at high and low concentrations, propionate, sucrose, starch and peptone). Bacterial cells were mostly gram-positives. Active proteobacteria were scarce in the granules exposed to VFA. Syntrophobacteria became dominant in the propionate-grown biomass. Concerning methanogenic archaea, Methanosaeta was the predominant species using complex substrates or low acetate concentration fed granules, while Methanosarcina and members of Methanobacteriales were predominant in the granules grown at high concentration of acetate or formate, respectively. Other Methanomicrobiales and Methanococcales, have been detected in the anaerobic granular sludge in the conditions used in this work.
Anaerobic treatment of natural tannin extracts in UASB reactors
Authors: López-Fiuza J. , Omil F. , Méndez R.
Published: May 2018

Tannin extracts are substances commonly used in leather production processes. Since most of the steps of tannery manufacturing processes are carried out in aqueous environments, the presence of these compounds in the wastewaters is important. The aim of this work is to study the feasibility of the anaerobic degradation of three natural tannin extracts in three Upflow Anaerobic Sludge Blanket (UASB) reactors, which were fed with increasing concentrations of two condensed (quebracho and wattle) and one hydrolysable tannin extract (chestnut). Concentrations of applied extracts were 100, 200, 400, 800 and 1,000 mg/l, and 5 g/l of glucose was used as cosubstrate. Reactors were operated during 210 days and their performance was evaluated from the values of total and soluble COD, total and intermediate alkalinity, volatile fatty acids, pH and UV absorption at 280 nm. COD removal efficiencies higher than 85% were achieved in all cases. However, tannin extract removal efficiencies (based on UV-280 nm absorption measurements) were significantly lower, around 20% for condensed extracts and 60% for the hydrolysable one, when the reactors operated with the highest tannin extract concentration. The operation of the reactors was stable, commonly with alkalinity ratios below 0.30. Mass balances carried out indicate that most of the COD removal efficiencies are due to the removal of the readily biodegradable organic matter (glucose), whereas the tannin extracts are hardly anaerobically biodegradable, especially condensed extracts (wattle and quebracho).
Workshop 6 (synthesis): water pricing
Authors: Rouse M. , Fallenius U.-B. , Tortajada C.
Published: May 2018

Water shold be costed so that it is valued, and fees should be transparent and contribute to adequate cost recovery with consideration of social, economic and environmental effects. There is a need for targeted subsidies to assist the poor. Water pollution fees for point sources can reduce discharges.
Towards a typology of water-related conflicts in the urban environment
Authors: Vlachos E.
Published: May 2018

Rapid urban population growth is occurring, particularly in developing countries, and has led to problems of providing adequate water supply and sanitation. Two dominant policy recommendations have been put forward - raise fees to existing users or increase the role of the private sector in the provision of water and sanitation services. A number of civil disturbances and riots have occurred in response to such proposals. More pragmatic policy initiatives are required to prevent and solve water-related conflicts, as well as new institutional structures to better handle competing and conflicting water demands.
The river Ganga of northern India: an appraisal of its geomorphic and ecological changes
Authors: Sarkar S.K. , Bhattacharya A. , Bhattacharya B.
Published: May 2018

The Ganga is the most important perennial river originating from Gangotri in the snow-bound Himalayas about 3,900 m above mean sea level. Gorging a distance of about 220 km in the Himalayas, it enters the plain at Hardwar and after meandering and braiding over a distance of about 2,525 km through the Indo-Gangetic plains, ultimately joins the Bay of Bengal. The course of this river has been changed due to: (i) subsurface geotectonic movement leading to change in slope of the deltaic plain and subsidence of the Bengal basin; (ii) changing pattern of water discharge with time; (iii) variations in sediment load. The environment of Ganga basin is also deteriorating with time due to severe natural episodes of periodic floods and storms as well as anthropogenic factors such as population growth, deforestation, agricultural activities, urbanisation, fertiliser and fossil fuel consumption and construction activities such as dams and bridges. All these have inconceivable adverse impacts on the health and natural regeneration capacity of the river basin. The presence of micropollutants in water and sediments of this river turns the system into being unsustainable to the biota. The present study synthesises the available information on the changes of its geological, geomorphological and ecological aspects and suggests some remedial measures to be adopted now and in future.
Modelling the economic impact of environmental flows for regulated rivers in New South Wales, Australia
Authors: Jayasuriya R.T.
Published: May 2018

The management of water resources across Australia is undergoing fundamental reform in line with the priorities identified by the Council of Australian Governments (COAG) in 1994. This includes reforms to the specification of property rights, the way the resource is shared between the environment, irrigators and other users, charges for water use and the operational management of the river systems. In New South Wales (NSW), a series of water sharing plans (WSPs) is being developed for each water source in the State including regulated rivers, unregulated rivers and groundwater aquifers. These plans, which are the mechanisms by which COAG reforms are being implemented, are being developed by community-based water management committees (WMCs). The role of the WMCs is to develop a plan that achieves a balance between environmental, economic and social outcomes. NSW Agriculture has assisted a number of WMCs by quantifying the economic impact of proposed WSP options on the irrigation community. This paper outlines the approach taken by NSW Agriculture to quantifying economic impacts on irrigators in regulated catchments and provides results of case studies in the Lachlan River Catchment which is heavily developed for irrigation.
Microbial activity of biofilm during start-up period of anaerobic hybrid reactor at low and high upflow feeding velocity
Authors: Suraruksa B. , Nopharatana A. , Chaiprasert P. , Tanticharoen M. , Bhumiratana S.
Published: May 2018

With an aim to shorten start-up time of an Anaerobic Hybrid Reactor (AHR), initial biofilm development was studied, particularly at different upflow feeding velocities. At a low (0.01 m·h-1) upflow velocity, initial biofilm was found to develop via the attachment of suspended biomass in the packed zone, while microbial growth on the film was insignificant. Contrarily, with higher (1.0 m·h-1) upflow velocity, initial biofilm development was from both microbial attachment and growth on supporting media. Biofilm thickness was determined using confocal laser scanning microscopy (CLSM), which indicated that the biofilm developed faster with the higher velocity, due to the contribution of the microbial growth on supporting media. When operated beyond the initial biofilm development with the lower velocity, both the activity of acetogens and the methanogens increased, although there was a lower amount of attached biomass on the supporting media. Whereas, both groups were found to decrease with higher upflow velocity, but acidogenic activity increased. It can be concluded that higher upflow velocity positively affected the initial stage of biofilm development and has the potential to accelerate attached biomass on supporting media during the initial phase. Subsequently, the upflow velocity should be reduced to the normal rate to enhance the methanogenic activity.
The microbial community analysis of a 5-stage BNR process with step feed system
Authors: Lee H.W. , Lee S.Y. , Lee J.O. , Kim H.G. , Park J.B. , Choi E. , Park Y.K.
Published: May 2018

The microbial communities of 5-stage BNR activated sludge samples were analyzed using fluorescence in-situ hybridization (FISH) and 16S rDNA characterization. The total cell numbers of each reactor were from 2.36 × 109 cells/ml to 2.83 × 109 cells/ml. From 56.5% to 62.0% of total DAPI cell counts were hybridized to the most bacterial specific probe EUB 338. Among them, b-proteobacteria were most dominant in each tank. The number of phosphate accumulating organisms (PAOs) was almost 50% of the total cell number in anoxic-1 tank, and these results indicate that this process has a high content of denitrifying phosphorus accumulating organisms (dPAOs). In contrast with FISH, 16S rDNA analysis showed that dominant groups were the Cytophaga-Flavobacterium group and high G+C% gram-positive bacteria, which were determined as PAOs in anoxic-1 tank. The beta subclass Proteobacteria did not accumulate a large amount of polyphosphate. The overall results indicate that high G+C% gram-positive bacteria and the Cytophaga-Flavobacterium group might play a key role as dPAOs in this process.
Bioleaching of metals from sludges and acid production under increased metal concentrations
Authors: Bickers P.O. , Chong R.C. , Bhamidimarri R. , Killick M.G.
Published: May 2018

To remove heavy metals from sludge and slurries the heavy metals must first be solubilised. In this study, metal bioleaching using sulphuric acid producing microorganisms is investigated. The inhibitory effects of four metals (zinc, chromium, nickel and copper) on acid production were firstly assessed for concentrations of each metal up to 1,000 mg/l. Low concentrations of zinc and chromium (50 mg/L) appear to stimulate the production of sulphuric acid but concentrations of those metals at 500 mg/L and above inhibited acid production (20 to 30% of the control rate at a concentration of 1,000 mg/L). The average sulphuric acid production of the metal free control was 0.78 g/L/day over a 10 day period. At all concentrations of nickel and copper, sulphuric acid production was suppressed and was less than 10% of the control at 250 mg/L or more after 10 days.

Activated sludge was also loaded with the four metals in individual bioleaching tests, in increments from zero up to 5,050 mg of metal/kg solids on a dry basis. In these bioleaching trials the sulphuric acid production averaged 0.9/g/L/day and the pH after 7 days was less than 2.0. Sludge copper concentrations of 3,850 and 5,050 mg/kg partially inhibited acid production (pH after 7 days was 2.4 and 2.7). The solubilisation for each metal after 7 days was Zn: 82–97%, Ni: 12–70%, Cu: 28–55%, and Cr: <20%. Bioleaching of a sludge loaded with a mixture of the four metals gave peak solubilities of 99% for Zn after 3 days, 68% for Ni after 6 days, 57% for Cu after 9 days and 33% for Cr after 9 days.
Evaluating bioaccumulation of suspected endocrine disruptors into periphytons and benthos in the Tama River
Authors: Takahashi A. , Higashitani T. , Yakou Y. , Saitou M. , Tamamoto H. , Tanaka H.
Published: May 2018

There are two major routes through which fish are exposed to endocrine disruptors (EDs); one route is through water that is a habitat; the other is through aquatic food such as algae and benthos. Few studies on the bioaccumulation of EDs in food have been conducted. Therefore, we evaluated the concentration in food of nonylphenol (NP), bisphenol A (BPA) and 17β-estradiol (E2), which were frequently detected in river water and in final discharge of Wastewater Treatment Plants (WWTPs) in Japan. We also evaluated the estrogenicity of samples using recombinant yeast.

NP concentrations ranged 0.1-0.4 mg/L in the river water, while they ranged 8-130 mg/kg-wet in the periphytons and 8-140 μg/kg-wet in the benthos. BPA concentrations ranged 0.02-0.15 μg/L in the river water, while they ranged 2-8.8 μg/kg-wet in the periphytons and 0.3-12 μg/kg-wet in the benthos. E2 concentrations ranged 0.0001-0.0076 μg/L in the water, while they ranged 0.09-2.26 μg/kg-wet in the periphytons and <0.01-0.22 μg/kg-wet in the benthos.

The estrogenicity ranged 0.0001-0.0464 μg-E2equivalent/L in the water, while it ranged 3.4-66.8 μg-E2equivalent/kg-wet in the periphytons and 7.4-5458 μg-E2equivalent/kg-wet in the benthos. Bioaccumulation factors of NP are estimated as 160-650 for the periphytons, and 63-990 for the benthos, respectively. Bioaccumulation factors of BPA are estimated as 18-650 for the periphytons, and 8-170 for the benthos, respectively. Bioaccumulation factors of E2 are estimated as 64-1,200 for the periphytons, and 100-160 for the benthos, respectively. The ratios of the periphytons and the benthos to the water in terms of the estrogenicity were larger than those in terms of the chemicals. In particularly, the ratio of the benthos to the water is about 106 in the maximum. The results suggest that food may be a more important route for fish exposed to EDs in water environment.
Adhesion and releasing of Poliovirus to activated sludge of wastewater purifying plants
Authors: Nakajima M. , Uwatoko K. , Kobayashi K. , Pan I.-J. , Iwabuchi N. , Sunairi M.
Published: May 2018

Pathogenic enteric viruses are released from infected persons through domestic wastewater to the environment. From that point of view, the knowledge of the viral behavior in wastewater purifying process is important: it is, however, still poorly understood. In this study, we reported the adhesion of Poliovirus to activated sludge samples taken from wastewater purifying plants by using a model system. More than 108 particles adhered to one gram (wet) of activated sludge, and the adhered viral particles maintained infectivity for longer period of time and showed higher thermo-resistant than the free viral particles. The adhered viral particles were released by increase of salt concentration or alkaline pH buffer as infectious particles.

The data suggest that pathogenic viruses could be enriched and maintain the infectivity in the activated sludge, and released to environments under certain conditions.
Removal of endocrine disruptors by tertiary treatments and constructed wetlands in subtropical Australia
Authors: Chapman H.
Published: May 2018

The controversial topic of endocrine disrupting chemicals (EDC) in aquatic environments is of international and Australian significance with the need for sustainable management of water resources increasing. The issues have been highlighted on the major continents of Europe and North America but so far have received less attention in Australia. A major source of these compounds has been identified as sewage effluent, which is treated prior to release to the environment with a primary focus on pathogen and nutrient removal. Sewage effluent is a complex mixture, which can contain many organic and inorganic compounds some of which may remain after treatment processes. More recently, technologies such as ozonation, UV treatment and advanced filtration have improved the quality of effluent discharged to the environment but there are still unresolved issues relating to poorly understood chemistries relating to EDCs in effluent discharges and the possible impacts in aquatic environments and to human health.

This paper reports on an investigation of the removal from sewage effluent of selected chemicals that are known or suspected environmental endocrine disruptors (EEDs) by sand filtration, ozonation and UV treatment at the Landsborough Water Reclamation Plant in Queensland, Australia. Compounds detected in the raw effluent included pesticides, herbicides, some heavy metals and the human hormones 17bestradiol and estrone. Most of these were removed by the advanced treatments at the water reclamation plant, with only trace concentrations of some compounds present in the final effluent. Removal of toxicants by a free water surface wetland is also reported on. Some of the constraints of direct chemical measurements are discussed and some solutions proposed.
The role of organic matter lost in kraft pulping material balances
Authors: Luonsi A. , Lento S. , Halttunen S. , Ala-Kaila K.
Published: May 2018

Efficiency improvement in a pulp mill includes minimisation of environmental discharges simultaneously with the development of pulp quality and production economy. Material balances in production processes, including fate of sidestreams, are key in proceeding these matters. Different approaches of determining the material balances increase understanding of process behaviour. We have focused on measuring sidestream (carryovers, washing water, filtrate) dissolved organic matter (DOM) in fibreline unit process blocks of softwood ECF bleached kraft production. The DOM was analysed by traditional wastewater methods (volatile solids, organic carbon, chemical oxygen demand). The measured data was combined with primarily simulated water balances and routine operational mill data in a simulation model. From this balance, yield estimate included, lost organic matter through complete degradation (CD) and volatile organic compounds (VOC) can be calculated throughout the fibreline. The sensitivity of this considerable amount (23-35 kgDVS/adt in total) to various factors is discussed in this paper.
Biodegradation of aliphatic and aromatic hydrocarbons at high temperatures
Authors: Feitkenhauer H. , Märkl H.
Published: May 2018

In this paper, the high temperature (65-75°C) biodegradation of aliphatic and aromatic hydrocarbons is investigated and kinetic parameters are derived. The shift of the physico-chemical system properties with rising temperature will be discussed in detail. For example, the solubility of naphthalene is increased by a factor of about ten if the temperature is increased from 20 to 75°C. This effect is essential to increase the bioavailability of sparingly soluble hydrocarbons. It is also demonstrated in experiments that very high oxygen transfer rates can be obtained at high temperatures in the presence of hydrocarbons.

It is shown that efficient phenol biodegradation is essential for high temperature hydrocarbon degradation because some microorganisms tend to transform phenols into polyphenols which are very inhibitory for microbial growth. A defined mixed culture adapted to phenol converted more than 90% of a mixture of phenol, hexadecane and pyrene and a very high maximal growth rate of 0.19 h−1 was determined. A yield coefficient YX/S of about 0.8 g (biomass)/g (hydrocarbons) was calculated in this experiment. In a separate experiment the influence of the hydrocarbon droplet size on the biodegradation is investigated at 70°C using a newly isolated Thermus sp. In this case, the growth on a hexadecane/pyrene mixture was described by a model based on the Monod equation and the corresponding kinetic parameters are derived.

A mixed culture was used for the bioremediation of soil in a slurry reactor. The initial contamination of 11 g/kg was lowered to about 2 g in a reactor inoculated by an immobilized culture of extreme thermophilic microorganisms, while 9 g/kg remained in a sterile control.
The ScanDeNi® process could turn an existing under-performing activated sludge plant into an asset
Authors: Rosén B. , Huijbregsen C.
Published: May 2018

With tightening up of effluent discharge standards from wastewater treatment facilities, many plants are facing costly augmentations and in many cases completely new plants will have to be constructed. The ScanDeNi® process was developed in Sweden for increased nitrogen removal at the Västerås Sewage Treatment Plant (STP), 125,000 p.e. near Stockholm, and can be described as a modified contact stabilisation process with pre-denitrification and a selector stage for nitrification. The STP was upgraded at a cost of some 25 Mill. SEK (2.5 Mill. USD). It has been successfully in operation since 1998, exceeding all expectations. The process is showing the following major advantages.•25-35% less volume for the same Sludge Retention Time (SRT) and secondary sedimentation sludge load, compared to conventional pre-denitrification; or a 25-35% higher load can be applied within the same volume with the same removal efficiencies. • The selector mechanism appears to be not limited to the nitrifying bacteria alone. Other microorganisms appear to be responsible for the reduction of surface active matter from the return activated sludge (RAS), as well as in the reject stream from sludge dewatering, resulting in an increase in a-values of approximately 50%.•Due to the high a-values less aeration is required, resulting in significant operating cost savings.•‘Automatic’ creation of anaerobic conditions, enabling biological phosphorus removal. Whilst rarely a concern in warmer climates, BNR plants in cold climates in winter often lose their capacity to nitrify. The Västerås STP has consistently maintained excellent effluent quality even with effluent temperatures as low as 7°C, and at an SRT of some 7-9 days, proving the effectiveness of the nitrifier selector. The ScanDeNi® process could offer excellent effluent discharge standards (T-N < 10 mg/L, T-P <0.5 mg/L) in smaller tank volumes and at a significantly lower operating cost, compared to conventional pre-denitrification systems.
Adaptive control of the nitrate level in an activated sludge process
Authors: Ekman M. , Samuelsson P. , Carlsson B.
Published: May 2018

In an activated sludge process for nitrogen removal, nitrate may be reduced to nitrogen gas by facultative heterotrophic bacteria in an anoxic environment. In order to guarantee sufficient supplies of readily biodegradable carbon compounds, an external carbon source often needs to be added. In this paper, an automatic control strategy for controlling the nitrate level using an external carbon source is presented. The external carbon source is added in the first anoxic zone to control the nitrate concentration in the last anoxic zone. Key process parameters are estimated on-line for a simplified Activated Sludge Model No 1. The estimated parameters are used for updating a linear quadratic controller. The strategy is illustrated in a simulation study with realistic influent data and is shown to perform very well.
Fenton's reagent and coagulation-flocculation as pretreatments of combined wastewater for reuse
Authors: Moreno A. Durán , Lorenzo E. González , De Bazúa C. Durán , De La Torre J. Malpica , Zamora R.M. Ramírez
Published: May 2018

In Mexico City, drinking water is mainly produced from groundwater (70%). This practice has caused collateral problems such as Mexico City's soil sinking (5-30 cm/year). One of the most viable alternatives to palliate this problem is the treatment of wastewater for reuse in either irrigation or for groundwater artificial recharge. This paper presents the evaluation of two physicochemical pretreatment systems to treat the wastewater from the metropolitan area of the Mexican Valley that are conducted by two main sewage systems called Great Canal and Churubusco River. In this research two treatment processes were studied: 1) coagulation-flocculation and, 2) Fenton's reagent. For each one of these processes suggested, tests were performed with wastewater samples of the Great Canal and the Churubusco River mixed in a volume ratio of 1:1. In the case of the coagulation-flocculation process, additional experiments were performed to determine the optimal conditions by applying an experimental design technique. In this experimental design, six coagulant agents were considered (alum, ferric chloride, three coagulant reagents of polymeric kind with aluminium and a coagulant reagent of natural origin), and three flocculant agents (an anionic, a cationic, and a non ionic polymers). Concerning the application of the Fenton's reagent (Fe2+:H2O2), the experimental variables were the weight ratio of the ferrous iron and the hydrogen peroxide and the concentrations of these reagents. The pH value was controlled to be near to 4. For the best experimental conditions, the effluent of the Fenton's method showed similar physicochemical characteristics to the wastewater treated by coagulation-flocculation. Nevertheless, Fenton's reagent showed two very important advantages compared to the coagulation-flocculation process: a disinfecting effect and a lower production of residual sludges.
Pre-nitrification by encapsulated nitrifiers - a possibility for self-sufficient energy operation of domestic WWTPs
Authors: Sievers M. , Vorlop K.D. , Hahne J. , Schlieker M. , Schäfer S.
Published: May 2018

The overall energy consumption of domestic wastewater treatment plants (WWTPs) increases with treatment efficiency. Approximately 30 to 45 kWh per people equivalent and year is mostly necessary for advanced nitrogen and phosphorus removal, while the aeration contains the main part of approximately 60%. A new process using encapsulated nitrifiers on gel lens beads is introduced to overcome the high energy consumption of aeration. A more selective nitrification process was found at a nitrification rate of between 50 and 60 mg nitrogen per hour and litre reaction volume corresponding to a hydraulic retention time (HRT) of about 30 to 60 minutes while the soluble Chemical Oxygen Demand (COD) removal could be less than 30% depending on operational conditions of the bio-reactor. The latter enables internal use of wastewater's COD for a post denitrification. For the new process the energy consumption as well as total volume of bio-reactor are much less (approximately 30 to 50% for both) than conventional processes due to the low sludge age for COD and nitrate removal and the avoidance of internal wastewater recycle. Therefore, self-sufficient energy operation of domestic WWTPs operating with advanced treatment efficiency could become possible, if energy recovery by anaerobic sludge digestion is included.
The effect of organic loading rate on the aerobic granulation: the development of shear force theory
Authors: Tay J.-H. , Pan S. , Tay S.T.L. , Ivanov V. , Liu Y.
Published: May 2018

The effect of organic loading rate (OLR) on aerobic granulation was studied by adopting three column-shaped, sequential aerobic sludge blanket reactors (SASBR). The reactors had been fed with laboratory prepared, synthetic dextrose-nutrient broth substrate. Experimental results showed clearly that the formation, characteristics and stability of aerobic granules had a close relationship with the strength of OLR applied. Aerobic granules appeared firstly under the OLR of 4 kg COD×(m3·day)−1. The system stabilization was demonstrated by its little-changed amount and morphology of granules. The characteristics of the stabilized granules were: 5.4 mm in mean diameter, 1.29 in roundness, 118 mg O2·(mg VSS·hr)−1 in SPOUR. The respective biomass SVI was 50 mL·(g MLVSS)−1 and the averaged COD removal rate was 95%. Under the OLR of 8 kg COD·(m3·day)−1, granules appeared two days later than those for 4 kg COD·(m3·day)-1 and they always coexisted with flocs. The formed granule bed was not as compact as that under 4 kg COD·(m3·day)−1. There were no granules formed under the OLR of 1 kg COD·(m3·day)−1. Instead, flocs with rather loose structure dominated reactor mixed-liquor. The respective SVI's were 65 and 138 mL·(g MLVSS)−1 under OLR of 8 and 1 kg COD·(m3·day)−1. It was proposed that the growth and maintenance of aerobic granules follow the shear force balance theory. Under the OLR of 4 kg COD·(m3·day)−1, a balance was reached between the aeration shear force and organic loading rate. Under this favored condition aerobic granules formed quickly and, became stabilized with the experimental parameters remained unchanged.
Coarse media filtration - an alternative to settling in wastewater treatment
Authors: Ødegaard H. , Liao Z. , Hansen A.T.
Published: May 2018

In this paper coarse media filtration has been analysed as an alternative to the traditional settling in primary, secondary and tertiary treatment of wastewater. Various filter media configurations were evaluated for enhanced primary filtration. It was found that a dual media configuration based on Kaldnes biofilm media (K1 and K2modified) were most suitable when taking both separation efficiency as well as filter run time into consideration. SS removal efficiencies of around 75% were achieved in the dual Kaldnes primary filter at around 20 m/h without any chemical addition and around 85% at low dosage (1-2 mg/l) of a high MW cationic polymer FO4440SH. In the latter case COD was removed by around 70%. Further experiments were carried out on a multi-media Kaldnes-Filtralite-Sand (KFS) filter for enhanced primary treatment as well as for secondary filtration directly downstream of a high-rate moving bed biofilm reactor, resulting in an extremely compact secondary treatment process. The secondary KFS-filter gave SS-removal efficiencies around 90% (effluent SS < 15 mg/l) and filter run times of around 24 hrs at filtration rates of 10 m/h (sludge loading rates of around 1 kg /m2h) when a small dose (2 mg/l) of polymer was used. It is also demonstrated that the primary filter may also be utilised as a pre-denitrification reactor. A denitrification rate of 1.5 kg NO3-Nequiv./m3d was achieved when the filter was operated at a filtration rate of 5 m/h.
A new one-dimensional clarifier model - verification using full-scale experimental data
Authors: De Clercq J. , Devisscher M. , Boonen I. , Vanrolleghem P.A. , Defrancq J.
Published: May 2018

A new one-dimensional clarifier model was developed, including components of existing models, and extended with a height-dependent cross-sectional area and two flowrate-dependent dispersion coefficients. This model is evaluated using data from a detailed one-month measuring campaign on a full-scale wastewater treatment plant. The data included hourly sludge concentration profiles, sludge bed heights at 10 minute intervals, sludge concentrations in inlet, effluent and recycle flows and regular settling properties characterised by batch settling tests. Due to the poor quality concentration measurements at the surface of the clarifier, the model was not calibrated to perform well in concentration predictions at this surface. However, excellent descriptive capabilities were obtained for sludge profiles and blanket level. The Cho et al. settling velocity function was found to be significantly better in terms of description capability than the more traditional Vesilind function.
A cost-effective method for detoxification of sludge containing lead
Authors: Banerjee K. , Blumenschein C.D.
Published: May 2018

The industrial wastewater treatment plant discussed in this paper generates sludge containing heavy metals, including lead. Occasionally, the concentration of lead in the Toxic Characteristics Leaching Procedure (TCLP) extract from the sludge exceeded the U.S. Environmental Protection Agency (EPA) regulatory limit of 5 mg/l and resulted in the solid waste exhibiting the characteristics of toxicity. The technical and economic feasibility of a process for conditioning the lead-containing sludge was investigated. The results revealed that the lead-laden sludge could be made non-hazardous by chemical conditioning. The lead reduction efficiency of triple super phosphate (TSP) is higher than that of either calcium carbonate or magnesium hydroxide. The laboratory and pilot-scale tests indicated that the conditioning system consistently reduced the lead in the TCLP extract below the regulatory limit of 5 mg/l. The economic feasibility evaluation demonstrated that more than US$450,000 could be saved annually by conditioning the sludge with TSP and disposing it as a non-hazardous material in a landfill. The results obtained from the laboratory as well as from the pilot-scale operation are described and discussed in this paper.
High-performance closed loop anaerobic digestion using pre/post sludge ozonation
Authors: Goel R. , Yasui H. , Shibayama C.
Published: May 2018

To maximize the sludge degradation efficiencies during anaerobic digestion, pre-ozonation of raw activated sludge and/or post-ozonation of anaerobically digested sludge were used in combination with a reactor operated without solid withdrawal (closed loop operation scheme). Out of the two studied configurations, the configuration with the post-ozonation of digested sludge was found to be superior with respect to degradation efficiencies, lower accumulation of total volatile solids (TVS) and lower required ozone dose. The TVS concentration in the reactor with post ozonation was found to be around 26 ± 2 g/l at an average TVS loading of 0.6 kgTVS/m3.d. The maximum TVS removal efficiencies were observed to be around 85% with average specific gas recoveries of 0.36 l CH4/gTVS fed. The ozone dose of 3% on the recycle sludge was found to be sufficient as it was observed that the higher ozone doses of 6% neither improved the TVS reduction efficiency nor reduced the TVS concentration in the reactor. The ozone requirements were estimated at around 0.054 gO3/gTVS removed or 0.045 gO3/gTVS fed. The soluble COD concentrations from the reactor ranged from 500-875 mg/l with negligibly small amount of VFA. The average COD in the centrate of the digested sludge was around 3000 mg/l suggesting the presence of colloidal COD in the reactors.
A conceptual framework for the sustainable management of wastewater in Harare, Zimbabwe
Authors: Nhapi I. , Gijzen H.J. , Siebel M.A.
Published: May 2018

The aim of this study was to formulate an integrated wastewater management model for Harare, Zimbabwe, based on current thinking. This implies that wastewater is treated/disposed of as close to the source of generation as possible. Resource recovery and reuse in a local thriving urban agriculture are integrated into this model. Intervention strategies were considered for controlling water, nitrogen and phosphorus flows to the lake. In the formulation of strategies, Harare was divided into five major operational areas of high-, medium-, and low-density residential areas, and also commercial and industrial areas. Specific options were then considered to suit landuse, development constraints and socio-economic status for each area, within the overall criteria of limiting nutrient inflows into the downstream Lake Chivero. Flexible and differential solutions were developed in relation to built environment, population density, composition of users, ownership, future environmental demands, and technical, environmental, hygienic, social and organisational factors. Options considered include source control by the users (residents, industries, etc.), using various strategies like implementation of toilets with source separation, and natural methods of wastewater treatment. Other possible strategies are invoking better behaviour through fees and information, incentives for cleaner production, and user responsibility through education, legislative changes and stricter controls over industry.
The Three Rivers Project - water quality monitoring and management systems in the Boyne, Liffey and Suir Catchments in Ireland
Authors: Earle J.R.
Published: May 2018

The “Three Rivers Project” is a government initiative and one of a series of catchment based water quality monitoring and management systems being developed throughout Ireland since 1997. The establishment of these multi-sectoral, basin-wide and community based systems is a response to historically perceived disjointed, legalistic and non-participative approaches to water resource management and purports to transcend the restrictions of traditional local authority administrative boundaries. The new management model embodies the concepts and objectives contained in the European Union (EU) Water Framework Directive (WFD) enacted in December 2000. Ireland, in common with many EU countries, has failed to halt decades of increasing levels of eutrophication of surface waters due principally to phosphorus loading. The “Three Rivers Project” is promoting the benefits of an integrated and cooperative approach to the management of three important river systems in Ireland, namely, the Boyne, Liffey and Suir. The project objective is to protect and improve water quality to conform with “good ecological status”. The implications of the Project findings for agricultural, municipal and industrial policy are grave and one of the greatest challenges now is to organise and fund Irish River Basin Management Systems as envisaged by the WFD to continue and build on the work which the “Three Rivers Project” has undertaken.
Field monitoring and evaluation of innovative solutions for cleaning storm water runoff
Authors: Papiri S. , Ciaponi C. , Capodaglio A. , Collivignarelli C. , Bertanza G. , Swartling F. , Crow M. , Fantozzi M. , Valcher P.
Published: May 2018

Urbanization increases the variety and amount of pollutants transported to receiving waters. Sediment from development and new construction; oil, grease, and toxic chemicals from automobiles; nutrients and pesticides from turf management and gardening; viruses and bacteria from failing septic systems; road salts; and heavy metals are examples of pollutants generated in urban areas. Sediments and solids constitute the largest volume of pollutant loads to receiving waters in urban areas.

When runoff enters storm drains, it carries many of these pollutants with it. In older cities, this polluted runoff is often released directly into open waterways without any treatment. Increased pollutant loads can harm fish and wildlife populations, kill native vegetation, foul drinking water supplies, and make recreational areas unsafe.

The objective of the study, performed by University of Pavia (Italy), University of Brescia (Italy) and GreenTechTexas International (US), reported herein is to evaluate the use of an innovative stormwater technology (EcoDräin(tm)) to reduce pollution due to urban runoff in existing urban areas.

The paper describes the methodology and the results achieved with tests conducted in laboratory in Pavia University in Italy and in two pilot areas in Italy and in Australia to investigate the EcoDrain's effectiveness for oil and heavy metals retention and sediment trapping. In the tests performed in a marina near Sidney in Australia a reduction has been achieved in oil and grease concentration higher than 95% and a reduction in metal concentration (particularly Copper, Lead and Zinc) close to 98%.

The paper also describes the methodology of the analysis on the absorbing material after its use and the consequent determination of the most efficient and environmentally safe way to dispose of consummated absorbent.
Pathogen removal efficiency from UASB + BF effluent using conventional and UV post-treatment systems
Authors: Keller R. , Passamani-Franca R.F. , Passamani F. , Vaz L. , Cassini S.T. , Sherrer N. , Rubim K. , Sant'Ana T.D. , Gonçalves R.F.
Published: May 2018

The aim of this study was to verify the efficiency of removal of microorganisms in effluents of a Wastewater Treatment Plant (WWTP) comprising an association of a UASB reactor followed by three submerged aerated biofilters (BAF) and one tertiary filter. The WWTP designed to treat domestic wastewater from a population of 1,000 inhabitants showed high removal efficiency for organic matter and suspended solids. Helminth eggs were also efficiently removed from the tertiary effluent and were found in the sludge from the UASB reactor; however, removal of bacteria in this system was very low. To enhance the efficiency of the system, the effluent from tertiary filters was submitted to UV disinfection in a real scale reactor. Our results showed that UV irradiation was very effective at lowering the concentrations of E. coli, thermotolerant coliforms and coliphages to acceptable levels for agricultural reuse. Salmonella spp. and helminth eggs were seeded into the tertiary effluent before passing through the UV reactor. Salmonella was not found in the final effluent, but helminth eggs were not completely inactivated by UV irradiation and viable eggs were detected after 28 d of incubation.