bluuebunny/crossref_metadata_2025 huggingface dataset:
Biogas production, sludge accumulation and mass balance of carbon in anaerobic ponds
Authors: Picot B. , Paing J. , Sambuco J.P. , Costa R.H.R. , Rambaud A.
Published: May 2018

This work concerned the application of anaerobic ponds for the primary treatment of urban wastewater in a Mediterranean climate. It was carried out on anaerobic ponds at large scale in Mèze (France). The anaerobic ponds constitute a good primary treatment with the removal of 55% of SS and 30% of BOD5, with a small surface area. The accumulation rate of sludge was only 0.017 m3/capita.year, due to their intensive anaerobic degradation. The anaerobic digestion reached equilibrium after one year of operation. The accumulation of sludge then showed seasonal variations with a substantial accumulation in winter and the digestion of the stock in summer. This change can be related to the influence of the temperature on methanogenesis. The production of biogas (83% CH4) was measured by gas collectors especially developed for this study and was also strongly dependent on temperature. The mass balance of carbon showed that 74% of the removed organic carbon was converted into CH4, 13% into dissolved inorganic carbon and 15% was stored in sludge. However, the anaerobic ponds presented a risk of creating odor nuisances with the emission of H2S.
Drinking water contamination in Walkerton, Ontario: positive resolutions from a tragic event
Authors: Holme R.
Published: May 2018

In May 2000, Escherichia coli 0157:H7 and Campylobacter jejuni contaminated the drinking water supply in Walkerton, Ontario. Seven people died and over 2,000 were ill as a result. The Ontario Provincial Government set up a judicial Inquiry into the circumstances surrounding the outbreak and also moved quickly to introduce a new Drinking Water Regulation that incorporated some significant requirements for drinking water providers. The Inquiry itself was in three parts: (a) part 1 related to the events that occurred in Walkerton and why the water contamination occurred; (b) part 1A related specifically to the role of the Provincial Government in the event; and (c) part 2 related to the future of drinking water safety in Ontario with potential to influence regulation on a wider basis. A number of other actions were taken after Walkerton. In August 2000, the Ontario Government, through the Regulatory body, the Ontario Ministry of the Environment (MOE) (a) re-issued and revised the Ontario Drinking Water Objectives (ODWO) as the Ontario Drinking Water Standards (ODWS) and (b) introduced new regulations governing drinking water in Ontario - the Ontario Drinking Water Protection Regulation. One of the key features of the Drinking Water Protection Regulation was the requirement to produce an independent Engineers’ Report on all water systems. This paper provides a unique perspective on the Walkerton tragedy and its aftermath. The author was active in many aspects of the resulting activity (Chair of the Ontario Water Works Association's (a section of the AWWA) Special Committee involved in Part 2 of the Walkerton Inquiry; author of several of the Engineers’ Reports mandated by Regulation; reviewer on behalf of the Regulator of Engineers' Reports submitted by others). The Engineers’ Reports were of interest because (1) the drinking water providers (mostly municipalities) were mandated by regulation to complete the Reports by specific dates and are paying for the Reports, (2) the work had to be done by a registered professional engineer who is not an employee of the owner or the operator if a different entity and (3) the engineer had to sign a declaration that the Regulator could rely on the accuracy of the Report. In other words, the Municipality retained the Engineer and paid them to produce the Report - the Engineer essentially carried the liability while the Regulator had the final say in the acceptability of the Report, a sort of eternal triangle of responsibilities. The paper will outline how the drinking water profession in North America worked together to provide the Walkerton Inquiry with the benefit of its experience and knowledge of best practices to the benefit of consumers and the drinking water providers. It will also outline the procedures adopted to produce the independent Engineers’ Reports and how the findings are being applied to further improve drinking water safety in Ontario, across Canada and in similar situations around the world.
Identification and genetic characterisation of Giardia and Cryptosporidium strains in humans and dairy cattle in the Waikato Region of New Zealand
Authors: Learmonth J.J. , Ionas G. , Pita A.B. , Cowie R.S.
Published: May 2018

Giardia intestinalis and Cryptosporidium parvum are commonly acquired waterborne parasites but little is known about their transmission cycles with regard to humans and animals. Faecal samples were collected over two time periods within the Waikato region of New Zealand from dairy cattle and humans and all positive isolates were genotyped. Of the 724 faecal specimens examined (354 cows, 304 calves and 66 humans), 16 cows, 32 calves and 5 humans were positive for G. intestinalis. Phylogenetic group 1 was found in 26 G. intestinalis positive dairy cattle with 22 being group 2. One G. intestinalis positive human isolate was group 1 and four were group 2. Of the 724 faecal specimens examined two cows, 33 calves and 66 human specimens were positive for C. parvum. All 35 C. parvum positive dairy cattle exhibited the bovine genotype while the 66 positive humans showed a seasonal shift in the prevalent genotype with the bovine dominating the spring (100%) and the human dominating the late summer period (96%).
Elucidation of potential transmission routes of Campylobacter in New Zealand
Authors: Savill M. , Hudson A. , Devane M. , Garrett N. , Gilpin B. , Ball A.
Published: May 2018

Campylobacter is the most commonly reported notifiable disease in New Zealand. The cost of Campylobacter infections in the country during 1994 was estimated as $61.7M although the true cost was probably higher. Investigation of the main environmental reservoirs and routes of transmission to humans is necessary to formulate the most appropriate intervention strategies. This project investigated the reservoirs of Campylobacter in a defined geographical area within New Zealand and compared strains isolated from humans and environmental sources within this area as a prelude to investigating the likely transmission routes to humans. Campylobacter jejuni was commonly found in faeces from dairy cows, beef cattle, sheep and ducks, chicken carcasses, sheep offal and surface waters and C. coli was commonly found in sheep faeces. Preliminary analysis of Penner types was suggestive of transmission to humans from dairy and beef cattle and possibly from sheep.
Geo-referencing of probabilistic risk of new chemicals in rivers
Authors: Verdonck F.A.M. , Janssen C.R. , Jaworska J. , Vanrolleghem P.A.
Published: May 2018

The characterisation of the risk of (new) chemicals to species/communities, when both the exposure/environmental concentration and effects (species sensitivity) are variable and uncertain, is the central issue in Probabilistic Environmental Risk Assessment. The spatial variability is one of the largest components of the total variability. This paper tries to explicitly account for this spatial variability by geo-referencing the exposure, effect and finally probabilistic risk. Geo-referencing makes the risk assessment more refined and realistic. In addition, it is also highlighted that geo-referencing the effects of chemicals (species sensitivity distribution) is still a large unexplored area but has large potential to improve probabilistic ecological risk assessments.
Microbiological aspects of an urban river used for unrestricted irrigation in the semi-arid region of north-east Brazil
Authors: Ceballos B.S.O. , Soares N.E. , Moraes M.R. , Catão R.M.R. , Konig A.
Published: May 2018

This study compared the behaviour of pathogenic bacteria (Salmonella and Listeria), faecal indicators (faecal coliforms FC and faecal streptococci FS), somatic coliphages and F-specific bacteriophages in an urban river contaminated with domestic sewage and surface run-off from agricultural and cattle grazing lands. The influence of physical and chemical parameters was also investigated as well as Salmonella and Listeria serotype diversity and drug resistance patterns. Faecal contamination was high (FC = 5 × 106 - 4 × 103 CFU/100 mL; FS = 4 × 105 - 2 × 102 CFU/100 mL) but decreased along the river by up to 99.5% following 47% reduction of BOD5 and 91% increase of DO, both associated with the self purification process. Somatic coliphages (6.9 × 105 - 1 × 103 PFU/100 mL) and F-specific bacteriophages (5.8 × 104 - 65 PFU/100 mL) behaved similarly with reductions of 99.85%. Salmonella and Listeria were isolated at all sampling points with highest frequencies (91-100%) at those with sewage discharge and rural water run-off. The lowest value (35%) occurred at the end of the river where it was (a) wider and shallower, (b) it ran slower and was warmer (29-33°C), (c) the pH was alkaline (8.2-9.9), (d) electrical conductivity (2,200-5,800 μS/cm) and DO (6-13 mg/L) were highest. Pathogen decline did not follow exactly FC and FS reduction patterns, while physical and chemical parameters apparently did not interfere with Salmonella and Listeria survival to the same extent as they did with FC and FS. Somatic coliphages and F-specific bacteriophages did not show more resistance than bacterial indicators. Catchment area contribution seemed to be more significant for pathogens than for indicators and rainy periods increased pathogenic isolation frequency. Five Salmonella serotypes and five serogroups were identified. S. hadar and serogroup E were predominant (50%); both are increasing in Brazil apparently from animal sources. Nearly 25% of Salmonella strains were resistant to at least one of twelve antimicrobials tested. Resistance to tetracycline was common (17%) followed by cefalotine (3%). Five Listeria serogroups were isolated and L. grayi (43%) and L. monocytogenes (9%) were present at all points. Listeria drug resistance rates were 100% for oxaciline followed by clindamicine (97%), tetracycline (34%) and vancomycin (32%). Both pathogenic bacterial strains presented resistance to the same drugs observed in humans and warm blood animals but the high number of sensitive strains and the low numbers of strains resistant to more than one drug was not expected because of the heavy anthropogenic impact in this basin.
Scope of potential bacterial agents of diarrhoea and microbial assessment of quality of river water sources in rural Venda communities in South Africa
Authors: Obi C.L. , Potgieter N. , Bessong P.O. , Matsaung G.
Published: May 2018

The microbial quality of several, usually untreated, surface domestic water sources, used by rural communities in the Venda Region of South Africa, was assessed to gauge their fitness for human consumption and to highlight the possible impact of waterborne diseases. The water sources studied were six points on the Levubu River and the rivers Mutale, Ngwedi, Tshinane, Makonde, Mutshindudi and Mudaswali. Total and faecal coliform, heterotrophic bacteria, enterococci and coliphage counts were used as indicators/surrogates to estimate the degree of bacterial and viral contamination respectively by standard methods. The presence of potential bacterial agents of diarrhoea such as Salmonella, Shigella, Campylobacter, Plesiomonas, Aeromonas and Vibrio was also determined. Results showed that the ranges of counts with regard to all the water sources investigated were 2.9 × 102 - 6.3 × 104 CFU/100 mL for faecal coliforms, 6.0 × 102 - 3.7 × 104 CFU/100 mL for total coliforms, 1.8 × 102 - 1.3 × 106 CFU/mL for heterotrophic plate count, 1.0 × 101 - 3.7 × 104 CFU/100 mL for enterococci and 0-13 PFU/100 mL for coliphages. These values are far higher than the acceptable maximum limits prescribed for South Africa by the Dept of Water & Forestry and the Water Research Commission - 0 CFU/100 mL, 5 CFU/100 mL, 1.0 × 102 CFU/mL, 0 CFU/100 mL and 1 PFU/100 mL for faecal coliforms, total coliforms, heterotrophic bacteria, enterococci and coliphages respectively. Salmonella, Shigella, Vibrio cholerae, Campylobacter, Aeromonas and Plesiomonas were isolated from several of the water sources investigated. The use of these water sources for drinking and domestic purposes poses a serious threat to the health and well being of the users and calls for urgent government intervention.
Evaluation of sequencing batch reactor (SBR) and sequencing batch biofilm reactor (SBBR) for biological nutrient removal from simulated wastewater containing glucose as carbon source
Authors: Manoj Kumar B. , Chaudhari S.
Published: May 2018

In general, conventional activated sludge (ASP) or enhanced biological phosphorus removing (EBPR) sludge has been used as seed culture for developing EBPR sludge and the time reported for development varies from months to year. In the present study cow-dung has been used as seed culture and EBPR sludge was developed within 36 days. The developed EBPR sludge has been used to evaluate the performance of sequential batch reactor (SBR) and sequential batch biofilm reactors (SBBR) for simultaneous nitrogen and phosphorus removal from synthetic wastewater containing glucose as carbon source. Three reactors were operated, SBR-1 containing only suspended biomass, SBBR-2 and SBBR-3 containing 5% and 10% polyurethane foam (PUF) media respectively along with suspended biomass. In all the reactors phosphorus removal was nearly the same and was more than 80%. In all the three reactors greater than 90% nitrification was achieved. Nitrogen removal in SBR-1 was 48% and in SBBR-2 and SBBR-3 it was more than 62%. On line monitoring of oxidation-reduction potential (ORP), pH and phosphorus during a cycle indicated that ORP and pH can be useful for real time control and optimization of the process.
PCR as a test for the presence or absence of Legionella in (cooling) water
Authors: Declerck P. , Verelst L. , Duvivier L. , Van Damme A. , Ollevier F.
Published: May 2018

Legionella pneumophila, a Gram-negative bacterium, is the causative agent of legionellosis. Traditionally, culture methods are normally used to detect Legionella species in different types of water (e.g. surface or tap water, circulating systems, air conditioners and their cooling devices). In this study the PCR conditions to detect Legionella were optimised based on the EnviroAmp Legionella kit (Perkin-Elmer) which is no longer commercially available. The PCR is very sensitive and specific in indicating the presence or absence (no quantification with classical PCR) of Legionella spp in general and more specifically L. pneumophila. To identify L. pneumophila. DNA sequences from the mip (macrophage infectivity potentiator) gene were amplified. The mip gene is conserved and specific for L. pneumophila although mip-like genes are also present in other Legionella spp. The PCR techniques were able to detect small amounts of Legionella in tap water samples. Cooling water, however, often contained PCR-inhibiting substances that could result in false negative PCR results for Legionella.
Nitrite accumulation in the treatment of wastewaters with high ammonia concentration
Authors: Yang W. , Vollertsen J. , Hvitved-Jacobsen T.
Published: May 2018

Different operational parameters of the nitritation process were investigated in both jar tests and pilot scale Sequencing Batch Reactors (SBRs). In the laboratory study, 100-1,200 mg N l-1 of ammonia was used. The pH and temperature were varied. Batch experiments were done on municipal sludge, pectin industrial sludge and sludge from a reject water treatment unit. Ammonia oxidation was observed with relative nitrite accumulations from 2% to 100% and ammonia oxidation rates from 0.01 to 0.58 g N g VSS-1 d-1. The nitritation process and relative nitrite accumulation were highly affected by pH, temperature and the sludge type. pH 8.0-8.5 and temperature 30°C were found favourable for the nitritation. Pilot SBR systems for treating reject water achieved 100% of nitrite accumulation under the operational conditions of pH 7.5-8.0, temperature 30°C and dissolved oxygen (DO) 1.0 mg l-1. Six months of operation revealed that pH regulations were essential to avoid the inhibitions by either free ammonia or nitrous acid. At an unionized ammonia concentration of approximately 20 mg NH3-N l-1, half of the normal nitritation ability still remained. Total inhibition occurred when the concentration of nitrous acid reached 3.0 mg HNO2-N l-1. However, both types of inhibitions were reversible in the SBR with a proper operation control. Stable and controllable nitritation could be achieved in pilot scale.
Parasite contamination of liquid sludge from urban wastewater treatment plants
Authors: Schwartzbrod J. , Banas S.
Published: May 2018

This study was performed on sludge samples from 20 wastewater treatment plants located in the north west of France with capacities of 1,000-20,000 inhabitant equivalents. The types of treatment studied were activated sludge low charge with and without denitrification. Respectively, 110 samples of fresh sludge and 84 samples of discharged sludge for spreading were analysed. Globally 78.6% of samples contained helminth eggs belonging to the cestodes (6.1%) and nematodes (93.9%). Most of the nematode eggs detected were viable with 135 positive samples. The distribution, according to genera, indicated a high prevalence of Toxocara eggs (77.4%) followed by Capillaria (13.2%), Trichuris (8.1%) and Ascaris (1.3%). For viable nematode eggs, the concentrations detected ranged from <1 to 28/4 gDM for fresh sludge and from <1 to 9.6/4 gDM for discharged sludge.
Chlorination and safe storage of household drinking water in developing countries to reduce waterborne disease
Authors: Sobsey M.D. , Handzel T. , Venczel L.
Published: May 2018

Simple, effective and affordable methods are needed to treat and safely store non-piped, gathered household water. This study evaluated point-of-use chlorination and storage in special plastic containers of gathered household water for improving microbial quality and reducing diarrhoeal illness of consumers living under conditions of poor sanitation and hygiene. Community families were recruited and randomly divided into intervention (household water chlorination and storage in a special container) and control (no intervention) households. Microbes in stored household water were extensively inactivated by 1-5-mg/L doses of hypochlorite. Escherichia coli levels in stored household waters were <1/100 mL in most intervention households but readily detectable at high levels in control households. Stored water of intervention households was also lower in Clostridium perfringens and heterotrophic plate count bacteria than in control households. The intervention reduced household diarrhoeal illness. In Bolivia, monthly episodes of household diarrhoeal illness were 1.25 and 2.2 in intervention and control families, respectively (P = <0.002) indicating that 43% of community diarrhoea was preventable by using the intervention. In Bangladesh, mean episodes of child diarrhoea/1,000 d were 19.6 and 24.8 in intervention and control groups respectively (P = <0.03) indicating that about 24% of observed diarrhoea was preventable by using the intervention. Chlorine disinfection and storage in an appropriate container significantly improved the microbiological quality of non-piped household drinking water and reduced community diarrhoeal disease. Widespread use of this simple treatment and storage system for non-piped domestic water has the potential to dramatically reduce the global burden of waterborne diarrhoeal disease.
Process enhancement in anaerobic bioreactor landfills
Authors: Kim J. , Pohland F.G.
Published: May 2018

The development of bioreactor landfills originated with the recognition that the sequential acid and methane fermentation phases of anaerobic waste stabilization could be accelerated by leachate recirculation. Original studies suggested the potential for such a change in design and management of landfills receiving both municipal and industrial solid wastes, followed by both pilot- and full-scale bioreactor landfill demonstrations. The enhancement of waste transformation within controlled bioreactor landfills is addressed in terms of the sequential phases of waste stabilization, temporal and spatial distribution of leachate and gas generation patterns, mechanisms of conversion, and proposed process and operational modifications. Selected results from investigations on bioreactor landfills include co-treatment of organic and inorganic constituents and the use of dedicated treatment zones.
Movement mechanisms of gross solids in intermittent flow
Authors: Littlewood K. , Butler D.
Published: May 2018

Gross solids, such as used tampons, sanitary towels and faecal stools, are introduced into the sewer network via the WC. Although small diameter pipes (≤ 150mm diameter) make up a large proportion of most sewer networks, the transport behaviour of gross solids in these smaller pipes is not fully established. In particular, there are concerns about the effect of water conservation measures on the transport of gross solids in the intermittent flow regime prevalent in small pipes. This paper introduces a study carried out on the movement of solids in this flow regime. An extensive series of experiments has been carried out to investigate the movement mechanisms and behaviour in detail. It was found that there are three different mechanisms of movement, and photographic evidence is provided in the paper. The concept and implications of the “limiting solid transport distance” is also introduced. It is argued that solid movement is dependent on factors other than just WC flush volume and that increased blockage potential is not inevitable.
Using quantitative real-time PCR to determine the hygienic status of cattle manure
Authors: Lebuhn M. , Effenberger M. , Gronauer A. , Wilderer P.A. , Wuertz S.
Published: May 2018

We developed a suitable system of DNA extraction and real-time quantitative polymerase chain reaction (qPCR) for the specific and sensitive quantification of pathogens and other relevant (indicator) organisms in recalcitrant material such as cattle manure. PCR inhibition by coextraction of humic compounds was minimized in this system, resulting in detection sensitivity of one target DNA copy per reaction well. Data from qPCR analysis for Escherichia coli agreed with cultivation based results, but orders of magnitude more fecal enterococci, Enterobacteriaceae and Campylobacter jejuni, were determined by qPCR than by cultivation. These bacteria may have been in a potentially hazardous active but non-cultivable state. The qPCR system is much less time consuming than conventional cultivation, highly specific, can detect non-cultivable organisms, provides high measurement throughput, and is cost attractive. It should be considered as an alternative in various application areas for (prescribed routine) cultivation based assays, e.g. for biosafety and hygiene monitoring.
Investigation of variations in microbial diversity in anaerobic reactors treating landfill leachate
Authors: Calli B. , Mertoglu B. , Tas N. , Inanc B. , Yenigun O. , Ozturk I.
Published: May 2018

A young landfill leachate containing elevated total ammonia concentrations frequently as high as 2,700 mg/l was anaerobically treated for 1,015 days in two different laboratory-scale anaerobic reactors configured as sludge blanket and hybrid bed. In this paper, the last 265 days of this long-term anaerobic treatability study are presented. Effects of high ammonia concentrations on reactor performances were correlated to the variations in microbial diversity by identifying the dominant microorganisms with FISH (fluorescent in-situ hybridization), cloning, DGGE (denaturing gradient gel electrophoresis) and morphological analysis. The results have indicated that the high ammonia landfill leachate can be treated successfully by using either an UASB or a hybrid bed reactor if temporary pH adjustments in the reactor influents are made when high ammonia concentrations are experienced. Consequently, COD removal efficiency is independent of microbial diversity and reactor configuration and it depends on the biodegradable portion of the leachate. Under this circumstance, stability of the reactors with low levels of acetate was supported by the abundance of Methanosaeta population. In both of the reactors, some populations of Methanobacteriaceae were also detected while other methanogenic species were virtually absent. However, after the termination of pH adjustment at Day 860, reactors immediately became unstable due to the sudden increase in free ammonia concentration up to 400 mg/l. COD removal efficiency decreased to 42% in the hybrid bed and to 48% in the UASB reactor. The durations of inhibitions were not long enough to severely deteriorate the massive Methanosaeta cells; therefore, many of them were again identified after two free ammonia inhibitions. However, subsequently, long filamentous morphologies of Methanosaeta cells shifted to shorter filaments and they lost their aggregating property.
Continuous biogas production from fodder beet silage as sole substrate
Authors: Scherer P.A. , Dobler S. , Rohardt S. , Loock R. , Büttner B. , Nöldeke P. , Brettschuh A.
Published: May 2018

Since April 2000 a two-step anaerobic plant with two subsequent 500 m3 reactors has been producing biogas from fodder beet silage (pH 4.1) as the sole substrate. The plant is located at Kirchlengern near Bielefeld, Germany. Initially the reactors were inoculated with swine manure at 37°C. After a start-up phase the process was sustained at pH 7.5-8.0 by feeding with the silage as sole substrate twice a day. Parallel to the biogas plant at Kirchlengern four one-step laboratory reactors were continuously driven at temperatures of 37°C, 45°C, 60°C and 65°C. They were fed with the same silage, but only once per day (one impulse). The organic loading rate (OLR) was adjusted to 3.9 g volatile solids (VS)/(l*d) with a concomitant hydraulic retention time (HRT) of 27 d. There was no problem with starting the reactors, but after 86 days the volumetric gas production of the 65°C reactor ceased and a high amount of approximately 130 mM propionate could be determined. By decreasing the temperature down to 60°C a stable reactor performance was recovered for a period of at least 250 further days. During impulse feeding it was observed that the quickest recovery of gas production could be observed at 37°C or at 45°C. Recovery of 75% gas volume (related to the value before or after impulse feeding) was obtained after 5.5 and 7.5 h of feeding time point whereas the 60°C reactor needed 16 h. Slight significant differences were seen in the spectrum of volatile fatty acids (VFA) reaching at 37° or 45°C its maximum with 10-30 mM total VFA at 2-3 h after feeding. After this the VFA level declined to nearly zero (except for the 60°C reactor). Therefore the 37°C reactor was favoured. A double experiment with a second 37°C reactor was started by a somewhat different inoculation procedure from the remaining 3 reactors, but revealed similar results. By increasing the temperature no significantly different specific gas production rates and methane yields could be observed, e.g. it gave 600-700 l biogas from 1 kg VS. The corresponding methane content ranged between 62-64%. With a methane content of 63 ± 1% a yield of 40.1 ± 2 m3 methane/ton fresh fodder beet silage was obtained.
Start-up of full-scale anaerobic digesters treating municipal solid waste
Authors: Ohmura T. , Sakai T. , Shindo Y. , Nakamura K. , Ike T. , Katayama Y.
Published: May 2018

Raising organic loading rate, and the behavior of dissolved CODcr (D-CODcr), VFA and specific methanogen activity, were investigated through a laboratory experiment for the start-up of a sludge recycling center. Moreover, application for MPN-PCR methods using a gene as a direct technique to measure the quantity of methanogen was attempted. It was recognized that specific methanogen activity depends on the quantity of methanogen, and that gas production does not reflect the condition of methane fermentation. The methane fermentation condition was checked through the specific methanogen activity and analysis of D-CODcr. The target organic loading rate was reached in the short period of about 30 days, and rapid start-up was successfully attained for a full-scale anaerobic digester.
Monitoring biofilm formation by using cyclic voltammetry - effect of the experimental conditions on biofilm removal and activity
Authors: Gião M.S. , Montenegro M.I. , Vieira M.J.
Published: May 2018

The effect of experimental conditions on cyclic voltammetry experiments on platinum electrodes covered with biofilms formed by Pseudomonas fluorescens for 2 hours was investigated. Results show that recycling the potential stabilizes the shape of the cyclic voltammogram after 135 cycles, but the observation of the electrodes by epifluorescence microscopy showed that cells are still adhered to the platinum surface. Some experimental conditions were changed during the electrochemical measurements - sweep rate, pH of the buffer and applied potential range. Some of these parameters had a strong impact on the bacteria that are adhered to the surface, increasing the death and removal in some circumstances.
Elucidation and control of biofilm formation processes in water treatment and distribution using the unified biofilm approach
Authors: van der Kooij D. , Vrouwenvelder J.S. , Veenendaal H.R.
Published: May 2018

Controlling biological processes in water treatment and distribution is a major challenge to water supply companies. In the Netherlands, the use of chlorine-based disinfectants in water treatment is limited as much as possible and treated water is distributed without disinfectant residual in most cases. Biofilm formation processes in water treatment and distribution are studied using adenosinetriphosphate (ATP) as the parameter for active biomass. ATP measurements are applied to assess biofilm concentrations in distribution systems, in the biofilm monitor to determine the biofilm formation rate of treated water, in the biomass production potential test to determine the effect of pipe materials on microbial growth and in membrane systems to quantify biofouling. The use of a single parameter enables to compare biofilm concentrations in all situations and contributes to the understanding and control of biofilm formation processes in water treatment and distribution. This approach has been designated as the Unified Biofilm Approach.
Monitoring biofilm formation and activity in drinking water distribution networks under oligotrophic conditions
Authors: Boe-Hansen R. , Martiny A.C. , Arvin E. , Albrechtsen H.-J.
Published: May 2018

In this study, the construction a model distribution system suitable for studies of attached and suspended microbial activity in drinking water under controlled circumstances is outlined. The model system consisted of two loops connected in series with a total of 140 biofilm sampling points. The biofilm from the system was studied using 11 different microbial methods and the results were compared and discussed. The methods were used for biomass quantification (AODC, HPC and ATP determination), visualisation of structure (CLSM), activity measurement (leucine incorporation, AOC removal rate, respiration of benzoic acid, CTC and live/dead stains), and microbial diversity profiling (clone libraries and DGGE).
Phosphorus sorption characteristics of a light-weight aggregate
Authors: Zhu T. , Maehlum T. , Jenssen P.D. , Krogstad T.
Published: May 2018

A light-weight aggregate (LWA) made of expanded clay used as a filter media in wastewater treatment, was tested for sorption of phosphorus (P) in laboratory experiments. The objectives were to investigate the different P retention pools and how grain size, time, temperature and changed P concentration influenced the P binding mechanisms in this type of filter. Three different grain sizes (0-2 mm, 2-4 mm and 0-4 mm) were tested in a batch experiment. The isotherm for the P sorbed by the contact medium (including retention and fixation) was obtained under laboratory conditions. Fifty percent of the P sorption occurred in the first 4-8 hours. Temperature did not substantially influence P sorption for 0-2 mm grain size LWA. In the LWA suspension system, P desorption did not occur when the P content in the loading solution decreased. Fractionation analysis indicated that Ca-bound P, loosely-bound P, and Al-bound P were the predominant P retention pools. The loosely-bound P pool was determined primarily by the equilibrated P concentration in the system. Fe-bound P was negligible in the P sorption of LWA.
Monitoring the effects of biocide treatment of Pseudomonas fluorescens biofilms formed under different flow regimes
Authors: Simões M. , Pereira M.O. , Vieira M.J.
Published: May 2018

The effectiveness of glutaraldehyde (GTA), a very common biocide for controlling biofilms formed by Pseudomonas fluorescens on stainless steel slides, in laminar and turbulent flow, was investigated. Tests were performed using a concentration of biocide of 200 mg L+1 and a range of exposure times. The GTA action was assessed by means of activity tests and dry weight of the biofilms. The physical stability of the biofilm without biocide application and after exposure to GTA for different periods of time was also studied and evaluated through the variation of the mass of the deposit after submission to different rotation velocities. The results showed that, in all the situations studied, biofilms were not controlled after the treatment with biocide, since they remained on the metal surface and were still active. The results also demonstrated that the physical stability of the biofilms increased with biocide application.
The role of regulatory agencies in multiple water use
Authors: Braga B.P.F.
Published: May 2018

This paper presents the conceptual framework for regulating water use in cases where water is a public good. Public agencies with an independent directive board can successfully manage such a situation. Through a comprehensive system of water permits, charging and control it is possible to effectively manage water resources. Together with the conceptual framework a practical application is presented. The case of the National Water Agency of Brazil - ANA - shows that it is possible to implement modern water resources management concepts in less developed countries. The benefits of this institutional arrangement are demonstrated in the case of managing water conflicts among water users. Two situations are described: the semi-arid water allocation for agricultural use in the Jaraguaribe River Basin in Ceara State and the conflict between the hydropower and navigation sectors in the Parana River Basin.
Water pricing in England and Wales - institutions and objectives
Authors: Day G.
Published: May 2018

Water pricing in England and Wales reflects a range of influences. Cost recovery is generally the primary influence over prices. The privatised public water supply sector dominates water usage. Water abstractions are licensed and allocated mainly on an administrative basis. Charges are levied to recover the water management costs of the licensing authority (the Environment Agency), and are not closely related to the scarcity of water resources, or the environmental impact of abstractions. Public water supplies are subject to price cap regulation. This provides incentives to reduce costs. Public water suppliers are expected to choose an optimal combination of water resource interventions in planning water supplies. The system of regulation has exposed choices. Tariffs for customers reflect company and regulatory concerns to share the burden of cost recovery equitably. Tariff innovation to influence behaviour has been limited by the low extent of metering of household customers. The cost recovery and institutional framework has led to discipline in investment decision-making.
Improvement of the properties of granular sludge in UASB reactors by flow pulsation
Authors: Franco A. , Roca E. , Lema J.M.
Published: May 2018

The objective of this work is to improve the characteristics of granular sludge by modification of the hydraulics of the bed through flow pulsation. Three UASB reactors, two operated with pulsing flow (P1 and P2) and a third without pulsation (NP), were started-up. Both recycling and feeding flow were pulsed in the reactor P1, while in reactor P2, only the feeding was pulsed. A high increase in the removal capacity and stability were achieved by applying pulsation in reactors P1 and P2 when compared to the non-pulsed one. Besides, pulsation promotes the formation of particles of smaller size and higher porosity, thus increasing the specific surface of the bed and consequently, the specific activity. In fact, while reactors P1 and P2 had a 95% COD removal when working at high organic loading rates (12 kg COD/m3·d), reactor NP only reached 6 kg COD/m3·d with 85% of removal capacity.
The effect of the supplementation with a primary carbon source on the resistance to oxygen exposure of methanogenic sludge
Authors: Estrada-Vázquez C. , Macarie H. , Kato M.T. , Rodríguez-Vázquez R. , Esparza-García F. , Poggi-Varaldo H.M.
Published: May 2018

Anaerobic methanogenic consortia have a considerable resistance to oxygen exposure. Yet, most research has been focused on the study of the tolerance to oxygen of anaerobic immobilized biomass. Less is known on the potential of the anaerobic suspended biomass for withstanding exposure to oxygen and the effect of a primary degradable substrate on such resistance. Thus, the objective of this work was to determine the effect of the amount of a primary degradable substrate (sucrose) on the resistance of a methanogenic suspended biomass to oxygen exposure. It was found that the inhibition of disperse anaerobic sludge by oxygen exposure decreases when the concentration of the supplemented carbon source increases. This is in agreement with the fact that aerobic respiration of the added substrate by the facultative heterotrophic bacteria, always present in this type of sludge, has been found in previous studies as one of the main mechanisms protecting methanogens against O2. From a practical point of view, this suggests that aeration of anaerobic systems should be possible without inhibiting the activity of methanogenic bacteria if an adequate ratio between oxygen and COD feeding is maintained. Such a ratio will depend however on the wastewater initial COD concentration.
Workshop 4 (synthesis): criteria for priorities between competing water interests in a catchment
Authors: Braga B. , Granit J.
Published: May 2018

Growing demand for water leads to increased competition between water users. A holistic, participatory and decentralized water management approach is promoted to reach a fair allocation mechanism between competing water uses. Domestic political discourse has a strong influence on water policies being developed.
Dyadic design interface between energy and agriculture: the case of Pinthali micro hydro system in Nepal
Authors: Regmi A.
Published: May 2018

Technology, like society, is heterogeneous. It mirrors the context in which it operates. Micro hydro development in Nepal is a rural energy strategy, which relies on technology and innovation and takes place in a specific social context. In designing this energy strategy, both technology and its social context, therefore, need to be considered seriously. In technical design processes, the interplay between the content (technology) and the context (society) needs to be considered, as the outcome will affect the people. For example, the content - micro hydro system - in the domain of the context - agriculture - provides an arena for an integrated water control system. Thus, it is possible to control water for two purposes: to produce power and to provide irrigation. The end product will be “energy” as a “consumptive” output and improved food security as a “productive” output of water. Therefore, within a sociotechnical framework, energy and irrigation become constitutive outputs of the sacrosanct “water”. Thus, the metaphor of power - the “sociotechnical code” of “content” and “context” - can be used with the term “agro-energy” in the design process of micro hydro systems. Evidence suggests that this interaction can lead to a transformed water use system for both productive and consumptive output for the benefit of rural communities.
Decentralised treatment of concentrated sewage at low temperature in a two-step anaerobic system: two upflow-hybrid septic tanks
Authors: Elmitwalli T.A. , Sayed S. , Groendijk L. , van Lier J. , Zeeman G. , Lettinga G.
Published: May 2018

The decentralised treatment of concentrated sewage (about 3,600 mgCOD/l) at low temperature was investigated in a two-step anaerobic system: two-anaerobic hybrid (AH) septic tanks (each 0.575 m3). The two reactors were placed in a temperature controlled-room and the HRT was 2.5 days for each reactor. The system was fed with concentrated domestic sewage, mainly black water from about 40 toilets flushed with only 4 litre of water and a limited amount of grey water. The system showed high removal efficiency for the different COD fractions. Mean removal efficiencies in the two-step AH-septic tank at 5 days HRT and 13°C were 94, 98, 74 and 78% for total COD, suspended COD, colloidal COD and dissolved COD respectively. The results of short run experiments indicated that the presence of reticulated polyurethane foam (RPF) media in the AH-septic tank improved the removal of suspended COD by 22%. The first AH-septic tank was full of sludge after 4 months of operation due to the high removal of particulate COD and the limited hydrolysis at low temperature conditions. Therefore, a simple mathematical model was developed based on ADM1 (the IWA model in 2002). Based on the experimental results and the mathematical model, only a one-step AH septic tank is required. An HRT of 5.5-7.5 days is needed for that one-step AH septic tank to treat concentrated sewage at a low temperature of 13°C. Such a system can provide a total COD removal as high as 87% and will be full of sludge after a period of more than a year.
Performance evaluation of an UASB reactor used for combined treatment of domestic sewage and excess aerobic sludge from a trickling filter
Authors: Pontes P.P. , Chernicharo C.A.L. , Frade E.C. , Porto M.T.R.
Published: May 2018

This work aimed at evaluating the influence of the excess sludge produced in a trickling filter (TF) on the performance of a UASB reactor used for the combined treatment of domestic sewage and aerobic sludge. During phase 1 of the research, the UASB reactor/TF system was fed with domestic sewage pumped directly from the sewer collector of Arrudas stream, in Belo Horizonte - Brazil. During phase 2, besides feeding the reactor with domestic sewage, the UASB reactor was also fed with the aerobic sludge from the trickling filter. The UASB reactor, with a volume of 420 litres, was operated at a mean hydraulic detention time of 5.6 hours in both operational phases. After 133 days of continuous monitoring, no detrimental effect was noticed on the performance of the UASB reactor regarding the return of the aerobic sludge produced in the TF. On the contrary, the COD results indicated a higher percentage of compliance with the discharge standards set forth by the Brazilian environmental legislation. During phase 2 of the research, when the UASB reactor was used for combined treatment of domestic sewage and excess aerobic sludge from the TF, the anaerobic effluent presented mean concentrations of 108 mgCOD.L-1, 57 mgBOD.L-1 and 18 mgTSS.L-1.
Liquefaction and methanization of solid and liquid coffee wastes by two phase anaerobic digestion process
Authors: Houbron E. , Larrinaga A. , Rustrian E.
Published: May 2018

This study attempted to investigate the feasibility of volatile fatty acid (VFA) production from coffee pulp hydrolyse, and further to determine the potential of methanization of both the pre-acidified effluent and the coffee wastewater. The experiments were carried out in 2 completely mixed reactors, each one with a working volume of 4 litres. Coffee pulp was used as substrate in the acidogenic reactor and different mixtures of pulper and wash-water and pre-acidified effluent in the methanogenic one. The acidogenic and methanogenic reactors were operated at an organic loading rate of 5 COD g.l-1.d-1 and 0.5 COD g.l-1.d-1. The total, soluble and VFA's effluent COD concentrations of the acidogenic reactor present average values of 57.75, 17.00 and 13.92 g.l-1 respectively. Under these experimental conditions, 23% (COD based) of coffee pulp was hydrolysed with a rate of 1.32 gCOD.l-1.d-1 and the soluble fraction was transformed to VFA's with an acidification efficiency of 82%. Total VFA's concentration reached a value of 13.9 gCOD.l-1, and acetate, propionate, butyrate and valerate represented 52%, 28%, 9% and 11% respectively of the liquid phase COD. In the methanogenic reactor, COD removal and methanization of fresh coffee wastewater, pre-acidified effluent and both combined occur with an efficiency of 85% to 95% respectively, with a characteristic biogas composition of 80% CH4 and 20% CO2. These results show that a humid coffee ‘Beneficio’ processing daily 23 tons of cherry coffee (fresh fruit), equipped with a two stage anaerobic digestion process could generate at least 1,886 CH4 m3.d-1. This represents an increase in methane production by a factor 3 to 5 compared to a ‘Beneficio’ using anaerobic digestion only for the treatment of its wastewater.
Effect of natural and modified zeolite addition on anaerobic digestion of piggery waste
Authors: Milán Z. , Villa P. , Sánchez E. , Montalvo S. , Borja R. , Ilangovan K. , Briones R.
Published: May 2018

The effect of natural and modified zeolites on the anaerobic degradation of acetate and methanol was evaluated by the determination of specific methane productivity (SMP) in batch minidigesters of 50 mL at doses of 0.01, 0.05 and 0.1 g of zeolite/g of VSS. The effects of the different zeolite concentrations were determined by the results of the SMP. A kinetic characterization with data of accumulated methane gas volume was also carried out. In the second phase of the study, the effects of natural and nickel zeolite concentrations were tested with piggery waste in laboratory scale digesters of 2.5 L operating at semi continuous mode, by increasing the organic load applied from 0.2 to 22.0 g TCOD/d corresponding to organic loading rates (OLR) of 0.1-8.8 g TCOD/l.d. A greater effect of modified zeolite on SMP was observed, with an increase of 8.5 times with magnesium zeolite, 4.4 times with cobalt zeolite and 2.8 times with nickel zeolite. Two phases were defined in the kinetic study and an increase of more than 2 times the apparent constant of digesters with modified zeolites was observed in the second phase when compared to unmodified natural zeolite. Modified natural zeolite addition to digesters can allow an increase in the potential biodegradability of piggery waste solid fraction and/or a considerable reduction of digestion volume.