bluuebunny/crossref_metadata_2025 huggingface dataset:
A new approach to education and training in water and environmental management
Authors: Tebbutt T. H. Y. , Woods D. R.
Published: May 2018

The paper describes the development of a programme of interdisciplinary professional education and training in the UK as influenced by new practices in environmental management. The roles of academic institutions and professional qualifying bodies are considered in relation to career development needs. The concepts behind a radically new professional qualification are discussed and methods for its delivery in practice are explained. The importance of clearly defined aims and objectives for such a course is stressed.
Monitoring the marine environment for small round structured viruses (SRSVS): a new approach to combating the transmission of these viruses by molluscan shellfish
Authors: Henshilwood K. , Green J. , Lees D. N.
Published: May 2018

This study investigates human enteric virus contamination of a shellfish harvesting area. Samples were analysed over a 14-month period for Small Round Structured Viruses (SRSVs) using a previously developed nested RT-PCR. A clear seasonal difference was observed with the largest numbers of positive samples obtained during the winter period (October to March). This data concurs with the known winter association of gastroenteric illness due to oyster consumption in the UK and also with the majority of the outbreaks associated with shellfish harvested from this area during the study period. RT-PCR positive amplicons were further characterised by cloning and sequencing. Sequence analysis of the positive samples identified eleven SRSV strains, of both Genogroup I and Genogroup II, occurring throughout the study period. Many shellfish samples contained a mixture of strains with a few samples containing up to three different strains with both Genogroups represented. The observed common occurrence of strain mixtures may have implications for the role of shellfish as a vector for dissemination of SRSV strains. These results show that nested RT-PCR can identify SRSV contamination in shellfish harvesting areas. Virus monitoring of shellfish harvesting areas by specialist laboratories using RT-PCR is a possible approach to combating the transmission of SRSVs by molluscan shellfish and could potentially offer significantly enhanced levels of public health protection.
Automatic control for DO and pH in the activated sludge process in a coke wastewater treatment plant
Authors: Lee B. K. , Sung S. W. , Chun H. D. , Koo J. K.
Published: May 2018

The objective of this study is to develop an automatic control system for dissolved oxygen (DO) and pH of the activated sludge process in a coke wastewater treatment plant. A discrete type autotuned proportional-integral (PI) controller using an auto-regressive exogenous (ARX) model as a process model was developed to maintain the DO concentration in aerators by controlling the speed of surface aerators. Also a nonlinear pH controller using the titration curve was used to control the pH of influent wastewater. This control system was tested in a pilot scale plant. During this pilot plant experiment, there was small deviation of pH and the electric power consumption of surface aerators was reduced up to 70% with respect to the full operation when the DO set point was 2 mg/l. For real plant operation with this system, the discrete PI controller showed good tracking for set point change. The electricity saving was more than 40% of the electricity consumption when considering surface aerators. As a result of maintaining the DO constantly at the set point by the automatic control system, the fluctuation of effluent quality was decreased and overall improvement of the effluent water quality was achieved.
Surveys monitoring the sea and beaches in the vicinity of Durban, South Africa: a case study
Authors: Rathbone P.-A. , Livingstone D. J. , Calder M. M.
Published: May 2018

A microbiological surveillance programme was initiated in Durban, South Africa, to provide an objective assessment of changes in the local seawater quality before and after the commissioning of two submarine outfalls in 1969 and has been ongoing until the present day. A classification system including Escherichia coli I, helminthic parasite ova, pathogenic staphylococci, salmonellae, shigellae, and salinity was used. This system, functioning as an audit, has proved useful in detecting problem areas which may have passed unnoticed in the routine E coli I assessments performed by the Durban Municipality. The salient features that have manifested themselves are (a) alterations in the seawater quality have been shown to be invariably a consequence of changes effected upon the shore or meteorological events and (b) that measuring more than one indicator of water quality, plus the use of salinity as a physical parameter for assessing the dilution or impairment of pristine seawater, has proved valuable.
Biofilms in drinking water systems - a possible reservoir for Helicobacter pylori
Authors: Mackay W. G. , Gribbon L. T. , Barer M. R. , Reid D. C.
Published: May 2018

Helicobacter pylori is a major bacterial pathogen involved in several gastrointestinal diseases. Transmission routes and reservoirs of H pylori are not well understood despite several studies. In contrast to many other infectious diseases, clinical symptoms allowing definitive diagnosis of infection are absent. Person-to-person transmission with faecal-oral and oral-oral routes have been proposed with socio-economic status and density of living as associated factors. Studies have shown that H pylori can survive in water for prolonged periods leading to a waterborne transmission route being proposed but not conclusively identified. This paper describes studies using mature heterotrophic mixed-species biofilms grown under oligotrophic conditions using a continuous-culture chemostat system. The biofilms were challenged with Helicobacter pylori (NCTC 11637). Results indicate the presence of H pylori associated with the biofilm for up to 192h post-challenge, suggesting that biofilms in water distribution systems could be a possible and as yet unrecognised reservoir of H pylori.
Model-based characterisation of hydraulic, kinetic and influent properties of an industrial WWTP
Authors: Coen F. , Petersen B. , Vanrolleghem P. A. , Vanderhaegen B. , Henze M.
Published: May 2018

This paper illustrates the modelling of a full-scale industrial wastewater treatment plant. First, the hydraulics of the plant were characterised by a model-based interpretation of the results of a tracer test. The plant consists of three parallel reactors. The hydraulics of each reactor could be modelled by two tanks in series with non-equal volume. These results were confirmed by calculation of the single pass residence time distribution. Also it was found that the influent flow and the recycle flow were not distributed equally to the three reactors, resulting in different loading rates. Secondly, off-line respirometric experiments were performed to characterise the influent and to determine the sludge kinetics. The same model structure could be applied to describe the influent characteristics and the biokinetics over a period of 1 year. It was found that all wastewaters could be fractionated into three fractions and that one of the fractions was acetate-like. Concentrations of the fractions changed significantly over the year. From on-line respirometric experiments the diurnal dynamics of the influent characteristics and the kinetics of the sludge were assessed. Analysis of the respirograms showed that the wastewater composition and kinetics of the sludge did not change significantly over a short-term period of 40 hours.
Some physiological properties of an Italian isolate of “microthrix parvicella”
Authors: Tandoi Valter , Rossetti Simona , Blackall Linda L. , Majone Mauro
Published: May 2018

“Microthrix parvicella” strain RN1, isolated by micromanipulation from an activated sludge treatment plant in Italy, is phylogenetically identical to two other isolates from Australia. Our Italian isolate of “M. parvicella” is a slow growing (μmax ranging from 0.3 to 0.5 d−1), aerobic organism that exhibits nutritional versatility, being able to utilize simple and complex compounds as carbon and nitrogen sources. In pure culture, the organism cannot grow anaerobically nor is it able to denitrify. Strain RN1 is able to grow both in aerobic and in microaerophilic conditions and this metabolic versatility could give it a metabolic advantage in the activated sludge milieu.
Influence of temperature and sludge loading on activated sludge settling, especially on Microthrix parvicella
Authors: Knoop S. , Kunst S.
Published: May 2018

During recent years modern full scale wastewater treatment plants with biological nitrification, denitrification and phosphorus removal have had increasing problems with foam formation on the surfaces of aerobic tanks and with bulking activated sludge. The results of a survey in 1995 (Kunst and Knoop, 1996) showed that most often the filamentous bacterium Microthrix parvicella is responsible for these problems. Up to today there is only little knowledge about its selection criteria in activated sludge. Therefore several experiments were done in full scale activated sludge plants and in laboratory systems under defined conditions to investigate the influence of low (< 0.1 kg/(kg·d)) and high (≤ 0.2 kg/(kg·d)) BOD5-sludge loading rates on the growth and morphology of M. parvicella and the settlement of activated sludge. Furthermore the influence of temperatures of 5°C, 12°C and 20°C on the growth of M. parvicella was investigated. It was shown that M. parvicella grows at low BOD5-sludge loading rate and low temperature and is the main causative organism of bulking and foaming sludge in nutrient removal plants. On the basis of this investigation it was concluded that the growth of M. parvicella and the settling problems of the activated sludge resulting from excessive growth of this filament will always appear in modern municipal wastewater treatment plants with BOD5-sludge loading rate ≤ 0.1 kg/(kg·d) especially under low temperature conditions.
Foaming in anaerobic digesters caused by Microthrix parvicella
Authors: Westlund Åsa Dillner , Hagland Eva , Rothman Maria
Published: May 2018

Three large wastewater treatment plants in the greater Stockholm area have experienced serious anaerobic digester foaming. Microscopic studies of the sludge from the foam phase showed a network of the filamentous organism Microthrix parvicella. The morphology of the long, coiled filament appeared to be affected by the anaerobic conditions where it became broken up into to shorter and thicker filaments. The operating strategy to prevent foam in the anaerobic digesters at these plants is to control the growth of M. parvicella in the activated sludge tanks by increasing the sludge load. Top installed stirrers and the addition of poly-aluminium salt have also been used to prevent foam formation.
Two-reactor system with partial phase separation for anaerobic treatment of olive oil mill effluents
Authors: Beccari M. , Majone M. , Torrisi L.
Published: May 2018

Previous works on the anaerobic treatment of olive oil mill effluents (OME) have shown that the inhibition of methane production is mainly caused by the presence of lipids. Saturation of unsaturated long-chain fatty acids (LCFAs) is the key factor to prevent inhibition of methanogenesis. This paper reports the experimentation carried out in a semi-continuous lab scale two-reactor system fed with diluted OME. Phase separation (acidogenesis and methanogenesis) was not complete in the two reactors. Indeed, a moderate methanogenic activity was allowed to be established in the first reactor. This scheme proved to be suitable to obtain an almost quantitative biotransformation of unsaturated LCFAs to palmitic acid in the first reactor, thus drastically lowering lipid inhibition on methanogenesis in the second reactor. The addition of an easily biodegradable substrate such as glucose did not improve biodegradation of polyphenols. A continuous flushing of N2/CO2 through the ‘acidogenic’ reactor did not promote the β-oxidation of palmitic acid. The two-reactor system with partial phase separation could find useful application for the anaerobic treatment of any lipid-containing wastewater.
Comparison of activated sludge microbial communities using biologTM microplates
Authors: Kaiser S. K. , Guckert J. B. , Gledhill D. W.
Published: May 2018

Laboratory models of wastewater treatment plants (WWTP) provide controlled systems for studying chemical biodegradability and removal as well as WWTP microbial ecology and engineering. In this study, Continuous Activated Sludge (CAS, 3-L) and Semi-Continuous Activated Sludge (SCAS, 2.5-L) units were maintained for up to 17 weeks using feedstocks of either fresh WWTP sewage, a complex synthetic wastewater, or a simple glucose/peptone feed (SCAS only). The goal of this research was to evaluate the microbial communities of the WWTP and the CAS and SCAS units to determine which laboratory models, and which feedstocks, were able to maintain the complexity of the WWTP microbial communities in the laboratory. One endpoint evaluated in this study was microbial community metabolic profiles, as measured using Biolog MicroPlates. Biolog Microplates contain 95 different pre-dried carbon sources and a tetrazolium dye used to spectrophotometrically measure oxidation of carbon sources. The Biolog carbon source utilization patterns of the CAS communities were similar to the SCAS communities when both were fed WWTP sewage. In addition, the profiles for these laboratory models remained similar to the WWTP microbial communities, even over an extended cultivation time (16 weeks) in the CAS systems. Amendment with a complex synthetic wastewater (25% by chemical oxygen demand) did not affect microbial metabolic response in the CAS systems, but amendment (100% by chemical oxygen demand) with a simple glucose-peptone wastewater in the SCAS system resulted in a measurable shift in microbial metabolic response.
Strategies for improvement of sludge quality and process performance of sequencing batch reactor plant treating municipal and tannery wastewater
Authors: Kabacinski M. , Hultman B. , Plaza E. , Trela J.
Published: May 2018

Advanced process technology has been implemented at newly built wastewater treatment plants in Central and Eastern Europe. The wastewater treatment plant (WWTP) in Nowy Targ, Poland, the largest in Europe based on sequencing batch reactor (SBR) technology, has shown that newly constructed plants must be integrated into the system of water, wastewater, and sludge management in the city and the region. A significant supply of tannery wastewater with increasing chromium concentrations in the influent to the WWTP has resulted in many operational problems related mainly to sludge treatment. Evaluation of the process performance and sludge handling for 2 years of plant operation is presented. Efficient biological phosphorus removal with concentrations lower than 1 mg/l in effluent is obtained. Nitrogen removal is characterised by a low nitrification rate and a high denitrification rate. Problems with sludge handling are related to high excess sludge production, insufficient sludge stabilisation, low sludge dewatering efficiency and high chromium content in the sludge. Different strategies for sludge handling improvement are discussed. Sludge should be treated as a resource, which is recirculating in an eco-cycle with recovery of nutrients and energy. Such a process is proposed for the WWTP in Nowy Targ.
Process optimisation of a combined system of floating medium and sand filter in prawn farm effluent treatment
Authors: Ngo H. H. , Vigneswaran S.
Published: May 2018

A treatment technology known as “a combined system of floating medium and sand filter (FMSF)” was developed and tested successfully with prawn farm effluent. This system has a remarkable techno-economical advantages. Laboratory and semi pilot-scale studies were carried out to optimise the filter bed depth, backwash method and other operating conditions. The dewatering characteristics of sludge from filter backwash was also analysed. The filter was operated at a high rate. The experimental results indicated that: (i) in case of no in-line chemical addition, the smaller ratio between floating medium and sand filter depth gave rise better filter performance. At the filtration rate of 7.5–20 m3/m2.h and with an in-line chemical addition, the suitable depth of floating medium varied from 400–1000 mm for a sand filter depth of 400 mm; (ii) frequent (once in every 90–120 minutes) but short duration of backwash (not more than 60 seconds) was found to be suitable. During the backwash, the water and air were sent for 30 seconds in upward direction and then followed with upflow of water for another 30 seconds. Backwash water amount comprised only 1.2–1.8% of the filtered water production. A mechanical backwash system using rotating paddles is a promising alternative for floating medium filter; and (iii) the filterability of the sludge from filter backwash was low in case of no in-line chemical addition (specific resistance, r = 9.34 × 1010 m/kg) but improved with in-line flocculant addition (r = 3.07 × 109 − 1.29 × 1010 m/kg).
Effect of controlled drainage and tillage on soil structure and tile drainage nitrate loss at the field scale
Authors: Tan C. S. , Drury C. F. , Soultani M. , van Wesenbeeck I. J. , Ng H. Y. F. , Gaynor J. D. , Welacky T. W.
Published: May 2018

Conservation tillage has become an attractive form of agricultural management practices for corn and soybean production on heavy textured soil in southern Ontario because of the potential for improving soil quality. A controlled drainage system combined with conservation tillage practices has also been reported to improve water quality. In Southwestern Ontario, field scale on farm demonstration sites were established in a paired watershed (no-tillage vs. conventional tillage) on clay loam soil to study the effect of tillage system on soil structure and water quality. The sites included controlled drainage and free drainage systems to monitor their effect on nitrate loss in the tile drainage water.

Soil structure, organic matter content and water storage in the soil profile were improved with no-tillage (NT) compared to conventional tillage (CT). No-tillage also increased earthworm populations. No-tillage was found to have higher tile drainage volume and nitrate loss which were attributed to an increase in soil macropores from earthworm activity. The controlled drainage system (CD) reduced nitrate loss in tile drainage water by 14% on CT site and 25.5% on NT site compared to the corresponding free drainage system (DR) from May, 1995 to April 30, 1997. No-tillage farming practices are definitely enhanced by using a controlled drainage system for preventing excessive nitrate leaching through tile drainage. Average soybean yields for CT site were about 12 to 14% greater than the NT site in 1995 and 1996. However, drainage systems had very little effect on soybean yields in 1995 and 1996 due to extremely dry growing seasons.
Molecular microbial ecology of nitrification in an activated sludge process treating refinery wastewater
Authors: Ballinger S. J. , Head I. M. , Curtis T. P. , Godley A. R.
Published: May 2018

The diversity of autotrophic ammonia-oxidizing bacteria (AOB) of the b-subdivision of the class Proteobacteria was investigated in a laboratory-scale denitrification-nitrification bioreactor (DNB) treating a synthetic waste stream. 16S ribosomal RNA (rRNA) gene sequences were amplified from DNA extracted from the oxic DNB sludge. Comparative analysis of the rRNA sequences revealed considerable diversity among the AOB-like sequences. The majority of sequences recovered were related to Nitrosomonas spp. but a smaller number of Nitrosospira-like sequences were obtained. Since different AOB may have different kinetic properties the high diversity of AOB, even in a simple laboratory biotreater treating a simple waste stream, has important implications for the operation of nitrifying wastewater treatment processes.
Sorption properties of biofilms
Authors: Späth R. , Flemming H.-C. , Wuertz S.
Published: May 2018

The distribution and fate of pollutants in biological wastewater treatment is highly influenced by sorption processes. Biofilms can provide a sink for dissolved matter with extracellular polymeric substances (EPS), cell walls, cell membranes, and cytoplasm serving as sorption sites. These sites display different sorption properties, preferences, and capacities. The distribution of organic pollutants such as BTX or heavy metals such as cadmium and zinc in biofilms could be investigated by fractionating the biomass. Therefore, an EPS extraction method with a crown ether was used which allowed the detection of organic and inorganic substances in the different fractions. After extraction, more than 60% of BTX could be localized in the EPS In contrast to organic substances, more than 80% of the total content of cadmium and zinc was found in the cellular fraction.
Adsorption and degradation of synthetic dyes on the mycelium of Trametes versicolor
Authors: Wang Yuxin , Yu Jian
Published: May 2018

Adsorption and degradation of three synthetic dyes with representative chromophores (azo, anthraquinone and indigo) were investigated on living mycelium of white rot fungus, Trametes versicolor. The maximum adsorption capacity (Qmax) and adsorption affinity (K) of the dead and living fungal mycelia to the three dyes were measured and estimated by using the Langmuir model; Qmax has a range from 50 to 105 mg dye/g dry mycelium and K from 17 to 120 mg dye/L. The adsorbed dye molecules could be degraded by the extracellular and/or intracellular enzymes that were produced by a 10-day old fungal mycelium after the essential nitrogen nutrient (NH4+) had been consumed completely. Fungal mycelium was saturated by the dyes in one hour and its adsorption capacity was regenerated at different rates depending on dye structure and enzymes. Compared to the enzymatic regeneration of dye-saturated living mycelium (8-19 mg dye/g dry mycelium. h), physical desorption of adsorbed dye molecules was consistent ranging from 2-3 mg dye/g dry mycelium. h.
Treatment of kraft condensates in a feedback-controlled sequencing batch reactor
Authors: Milet G. M. D. , Duff S. J. B.
Published: May 2018

A feedback-controlled sequencing batch reactor was used to treat kraft accumulator and evaporator condensates. The control strategy used the level of dissolved oxygen to terminate the oxidation phase and commence the settling phase of each cycle. The duration of the oxidation phase was automatically adjusted to achieve 100% removal of methanol, the major carbon source in the condensates. While the treatment rate varied substantially in response to influent variability, the overall level of treatment remained constant, averaging 88±5% and 64±2% COD removal for the accumulator and evaporator condensates, respectively. Generally over 90% of the reduced sulfur compounds were removed, apparently almost completely by stripping. Metal ion addition was found to be necessary to support biological growth in accumulator condensate.
A national survey of activated sludge separation problems in the Czech Republic: filaments, floc characteristics and activated sludge metabolic properties
Authors: Wanner Jirí , Ruzicková Iveta , Jetmarová Petra , Krhutková Olga , Paraniaková Jana
Published: May 2018

The extent of activated sludge separation problems associated with excessive growth of filamentous microorganisms has increased recently in the Czech Republic. Most of the activated sludge plants in the country were contacted by mail with a questionnaire, the aim of which was to obtain the basic technological data on the plants and on the nature and intensity of activated sludge separation problems. Selected activated sludge plants were visited at different periods of the year and samples of activated sludge mixed liquor and foam were collected for microscopic examination and kinetic batch tests. It was found that good settling properties were associated more with good quality activated sludge flocs than with the absence of filaments. On the other hand, a very high abundance of filaments always resulted in bulking or foaming. The most common filamentous microorganisms in activated sludge mixed liquors were M. parvicella, N. limicola and Types 0092, 0041 and 0803 while the foams were mostly dominated by M. parvicella, NALOs (GALOs) and N. limicola. Seasonal shifts in filamentous population diversity were also observed. M. parvicella, Type 0092, N. limicola, Type 0803 and Type 0041 were dominant in both conventional and biological nutrient removal activated sludge plants whereas the other Eikelboom's types of filaments dominated mostly in conventional activated sludge plants. The ability of foams to denitrify depended on the dominating filamentous microorganism and type of substrate.
Survey of filamentous populations in nutrient removal plants in four European countries
Authors: Eikelboom Dick H. , Andreadakis Andreas , Andreasen Kjaer
Published: May 2018

A joint EU research project aimed at solving activated sludge bulking in nutrient removal plants was initiated in 1993. The project started with a survey of the size and composition of the filamentous population in nutrient removal plants in Denmark, Germany, Greece and the Netherlands.

The results show that biological nutrient removal process conditions indeed favour filamentous microorganisms in their competition with floc forming organisms. An increase in the size of the filamentous population resulted in a deterioration of the settling properties of the biomass, except for plants with Bio-P removal conditions. It is assumed that in the latter case the dense clusters of Bio-P bacteria increase the weight of the flocs, and compensate for the effect of the larger number of filaments.

Although exceptions frequently occur, the following sequence in decreasing filamentous organism population size was observed for the process conditions indicated:

- completely mixed + simultaneous denitrification;

- completely mixed + intermittent aeration/denitrification;

- alternating anoxic/oxic process conditions, with an anaerobic tank for biological phosphate removal (Bio-Denipho);

- alternating anoxic/oxic process conditions (Bio-Denitro);

- predenitrification

The surveys provided little information about the effect of nutrient removal in plants with plug flow aeration basins. Simultaneous precipitation with aluminium salts nearly always resulted in a low number of filaments and a good settling sludge.

The size of the filamentous organism population showed a seasonal pattern with a maximum in winter/early spring and a minimum during summer (in Greece: during autumn). This seasonal variation is primarily caused by the effect of the season on the population sizes of M. parvicella, N. limicola and Type 0092.

M. parvicella is by far the most important filamentous species in nutrient removal plants. In Denmark only, Type 0041 also frequently dominates the filamentous population, but seldom causes severe bulking. Considering their frequency of occurrence, approx. 10 other filamentous micro-organisms are of minor importance. Growth of some of these species, viz. those which use soluble substrate, can be prevented by the introduction of Bio-P process conditions.

M. parvicella and Type 0041 (and probably also Actinomycetes and the Types 1851 and 0092) seem to compete for the same substrates i.e. the influent particulate fraction. Most of the differences in composition of the filamentous microorganism population can be explained by whether or not premixing of influent and recycled sludge is used. In general, premixing for a short period of time followed by anoxic conditions favours Type 0041. M. parvicella seems to proliferate if the particulate fraction is first hydrolysed or if it enters the plant via an oxic zone. It is concluded that bulking in nutrient removal plants is mainly caused by filamentous species requiring the particulate fraction for their growth.
Enhanced degradation of lignosulfonated compounds by Streptomyces viridosporus
Authors: Hernandez-Pérez G. , Goma G. , Rols J. L.
Published: May 2018

Degradation of lignosulfonated compounds by S. viridosporus strain T7A on nutritive or mineral culture media was quantified. Two lignosulfonated compounds, differing in their molecular mass distributions and chemical structures, were used: lignosulfonate (1–80 kDa) and vanisperse, a sulfonated oxylignin (1–20 kDa). The use of nutritive culture medium (containing Biosoyase) enhanced both the growth of S. viridosporus and production of lignin peroxidase (LiP) leading to enhanced lignocellulose degradation, but no lignosulfonated compound degradation was observed. A fraction of these compounds underwent a molecular transformation, producing non-biodegradable acid precipitable polymeric lignin (APPL). When a mineral culture medium (containing glycerol as additional organic carbon source) was used, approximately 21 and 35% of lignosulfonate and vanisperse were respectively degraded, with little APPL production. LiP activity was growth-associated and significant modifications of molecular mass distributions of both lignosulfonated compounds were observed. A mixed natural microbial population, collected in an aerated lagoon treating Fluff pulp effluent, was used to evaluate the biodegradability of lignosulfonate products from S. viridosporus cultures. This population was (i) unable to degrade lignosulfonate products, and (ii) decreased the lignosulfonate degradation capacity of S. viridosporus. Antagonistic effects of the mixed population on S. viridosporus were observed. In the light of this, bioaugmentation strategies involving addition of S. viridosporus are unlikely to be successful and alternative degradation strategies need to be developed.
Composition of extracellular polymeric substances in the activated sludge floc matrix
Authors: Bura R. , Cheung M. , Liao B. , Finlayson J. , Lee B. C. , Droppo I. G. , Leppard G. G. , Liss S. N.
Published: May 2018

The precise role of extracellular polymeric substances (EPS) in relation to the formation and physicochemical properties of microbial floc in wastewater treatment systems is not well known. Studies were undertaken to provide more comprehensive descriptions of EPS and properties of microbial floc. Acidic polysaccharides and DNA were relatively labile components of the EPS when biomass was stored at 4°C or at −20°C, and significant losses of these components were observed within 24 hours. The composition and properties of activated sludge were found to vary between different full-scale treatment systems reflecting the importance of wastewater composition and operation conditions on microbial communities and the response to environmental conditions. The COD:N:P ratio was found to influence hydrophobicity, surface charge and the EPS composition of microbial flocs in well-controlled bench-scale sequencing batch reactors. Phosphorus depleted and P-limited conditions resulted in a decrease in surface charge but increases in acidic polysaccharides which corresponded to a strong carboxyl stretch at 1740 cm−1 when the biomass was analysed by FTIR-spectroscopy. Electron dense particles, identified by energy-dispersive spectroscopy as containing iron, phosphorus and sulfur, were observed in the fibrils of the floc matrix by transmission electron microscopy.
Comparison of hydrolytic enzyme systems in pure culture and activated sludge under different electron acceptor conditions
Authors: Goel Rajeev , Mino Takashi , Satoh Hiroyasu , Matsuo Tomonori
Published: May 2018

Enzymatic hydrolysis under different electron acceptor conditions in nutrient removal activated sludge treatment processes is a weak link in the Activated Sludge Model no. 2 (Henze et al., 1995). An experimental study was undertaken to gain insight into the hydrolysis process with specific focus on hydrolysis kinetics and rates under different electron acceptor conditions. Two pure cultures, Bacillus amyloliquefaciens (Gram positive) and Pseudomonas saccharophila (Gram negative) were chosen for the study. In addition, activated sludge grown in an anaerobic-aerobic system was tested for enzymatic activity using starch as the model substrate. The hydrolytic enzymes were found to be released into the bulk in pure cultures whereas the enzyme activity was found to be mainly associated with the cell surfaces in activated sludge. Further, it was observed that the development of the hydrolytic enzyme system in Bacillus amyloliquefaciens and P. saccharophila is strongly suppressed under anoxic and anaerobic conditions. However, the effect of anaerobic and aerobic incubation on hydrolytic enzyme activity in activated sludge was found to be small. Starch hydrolysis kinetic data from batch experiments with activated sludge followed substrate saturation kinetics that were linear with biomass concentration. Finally, the similar hydrolytic enzyme activities observed under anaerobic and aerobic phases of a sequencing batch reactor are explained by considering the aspects of enzyme location and enzyme system development under aerobic and anaerobic phases. It is proposed that the floc bound enzymes are recycled in a single sludge system so that an equilibrium exists between enzyme loss and synthesis at steady state.
Measurement of polysaccharides and proteins in biofilm extracellular polymers
Authors: Zhang Xiaoqi , Bishop Paul L. , Kupferle Margaret J.
Published: May 2018

The structure of biofilm extracellular polymers (ECPs) was studied by measuring their polysaccharide and protein spatial distributions along biofilm depth. Biofilm was collected from two aerobic heterotrophic biofilm reactors, which were seeded with Sphingomonas sp. and Sphingomonas sp. plus mixed liquor, respectively, and operated under toxic organic (in this case, azo dye) degrading conditions. Complete mixing conditions in the two reactors were verified by measuring water content, and polysaccharide and protein quantities from three vertical sampling positions over time. Experimental results showed that: (1) the biofilm water content of either reactor did not change with sample position or biofilm age, with an average biofilm water content in both reactors of 97%; (2) polysaccharides and proteins in the ECPs did not change with sample position; (3) the profiles of polysaccharides and proteins along the biofilm depth showed a stratified biofilm structure, with their ratio (proteins/polysaccharides) being relatively stable over the depth. Oxygen and substrate transport and interactions among species were considered to be the main reasons for producing such a non-uniform biofilm structure; and (4) Sphingomonas sp. could not compete well with microorganisms derived from the mixed liquor of a wastewater treatment plant aeration basin.
Application of full-scale evaporation-incineration technology for hazardous wastewater
Authors: Kaul S. N. , Nandy T. , Deshpande C. V. , Srivastava A. , Shastry S. , Szpyrkowicz L.
Published: May 2018

An attempt has been made to present the data relating to full-scale application of evaporation incineration technology for containment of wastewater emanating from H-acid (mono sodium salt of 1 amino-8-hydroxynapthalene 3,6-disulphonic acid) production with recourse to zero wastewater discharge. The wastewater is acidic with high concentrations of COD and total dissolved salts and BOD/COD ratio of 0.09–0.11. NOx SOx, SPM and CO from stack emissions are within the standards stipulated by the statutory bodies.
A new method for extraction of exopolymers from activated sludges
Authors: Azeredo Joana , Oliveira Rosário , Lazarova Valentina
Published: May 2018

The exopolymeric matrix that surrounds the biomass greatly contributes to the efficiency of activated sludge systems. To study the composition of this matrix a preliminary extraction method is required. In this work three extraction methods (vapor, sonication and combined treatment by sonication and Dowex resin) were used and compared with a new method which uses glutaraldehyde. The extraction effectiveness was estimated by measuring the total protein, the total organic carbon in the extracted solutions and by determining the monosaccharide constituents of the extracted polysaccharides. The proposed new method proved to be the most suitable because it extracted a great quantity of organic matter without disrupting the cells.
Biodegradation of phenolic compounds by an acclimated activated sludge and isolated bacteria
Authors: Buitrón Germán , González Ariel , López-Marín Luz M.
Published: May 2018

The degradation of a mixture of phenol, 4-chlorophenol (4CP), 2,4-dichlorophenol (24DCP) and 2,4,6-trichlorophenol (246TCP) by acclimated activated sludge and by isolated bacteria was studied. Activated sludge was acclimated for 70 days to 40 mg phenols/l then the microorganisms responsible for the CP degradation were isolated and identified. Four types of Gram-negative bacteria (Aeromonas sp., Pseudomonas sp. Flavomonas oryzihabitans, and Chryseomonas luteola) were identified. Also, two acid-fast bacilli with distinct glycolipid patterns were isolated. From their chemical composition and their growth characteristics, both isolates appeared to be mycobacteria closely related to Mycobacterium peregrinum. The degradation kinetics of each phenol by Aeromonas sp., Pseudomonas sp. Flavomonas oryzihabitans, Chryseomonas luteola and activated sludge were determined. The acclimated activated sludge degradation rates were from one to two orders of magnitude higher than those of pure strains when uptake rates were calculated in terms of the viable biomass (CFU). The specific substrate uptake rate for acclimated activated sludge varied between 8.2 and 15.8 × 10−7 mg/CFU·d (407-784 mg/gVSS·d). Aeromonas sp. had the highest specific substrate uptake rate of the pure strains, based on a VSS basis (33-57 mg/gVSS·d) but, in terms of viable biomass (5.0-15.6 × 10−8 mg/CFU·d), the Pseudomonas sp. rate was the highest. Specific substrate uptake rates were 1.8 mg chlorinated phenols/g VSS·d for unacclimated activated sludge.
Vitamin addition in biological wastewater treatment
Authors: Lemmer Hilde , Lind George , Metzner Gerhard , Nitschke Lutz , Schade Margit
Published: May 2018

Vitamin supplementation is advertised in wastewater treatment to compensate for a deficiency of growth factors and thereby increase sludge activity and purification efficiency. Addition of vitamins of the B-complex was tested with activated sludge from 5 plants and compared to municipal sludge. Auxotrophy of bacteria isolates turned out to be compensated in most cases by vitamin producers in the activated sludge biocenoses.
A dual function membrane bioreactor system for enhanced aerobic remediation of high-strength industrial waste
Authors: Scott J. A. , Neilson D. J. , Liu W. , Boon P. N.
Published: May 2018

A ceramic micro-filtration cross-flow membrane coupled to an aerobic bioreactor has been successfully operated as alternatively the system aerator or as a filter of treated waste in the biological remediation of a food industry waste-stream. Membranes with nominal pore sizes ranging from 1.2 to 0.2 μm with the same air supply provide 20 to 70% higher aeration rates than a traditional ring-sparger. In addition, by acting as a physical barrier, the membrane allowed an indigenous waste-specific microflora to develop (109 cfu/ml) which under conditions of nitrogen deficiency, provided a high level of remediation coupled to very low sludge production. At 25°C (typical waste-stream temperature), with COD inputs of up to 9600 mg/l and BOD5 up to 5300 mg/l, reductions in excess of 95% in membrane permeate levels were obtained. Suspended solids in the permeate were also kept low at less than 25 mg/l.
Intensified activated sludge process with submerged membrane microfiltration
Authors: Davies W. J. , Le M. S. , Heath C. R.
Published: May 2018

A pilot bio-reactor based on the Kubota membrane filtration system using screened domestic sewage has shown impressive results. Operating with an average MLSS of 16,000 mg/l and 4.5 hours HRT the bio-reactor produced a very high quality effluent with typical values of 4 mg/l and 5 mg/l for BOD and NH4-N respectively. The sludge age from the bio-reactor was about 45 days. The cost of secondary treatment by membrane bio-reactor (including land and civil costs) starts from 12 p/m3 for a 1.4 Ml/d plant and reduces to 6p/m3 for a 22.5 Ml/d plant based on full treatment up to 3DWF. The corresponding treatment costs by conventional technologies are 13 p/m3 for a 1.4 Ml/d SBC plant and 5 p/m3 for a 22.5 Ml/d FBDA activated sludge plant.
Applying phenotypic fingerprinting in the management of wastewater treatment systems
Authors: Schneider C. A. , Mo K. , Liss S. N.
Published: May 2018

Carbon substrate utilization profiles, phenotypic fingerprints, of microbial communities from different pulp and paper effluent treatment systems are being determined using Biolog plates. The substrates from the Biolog GN plates that were deemed to be most significant in differentiating between communities are being employed as substrate panels on Biolog MT plates. Correlative microbiological tests including FAME analysis, heterotrophic plate counts, and epifluorescent microscopy are performed on the samples. By correlating the phenotypic fingerprints to pulp and paper mill processes and operation parameters in the treatment systems, the carbon substrate utilization profile has shown potential as a useful management tool.
New foam-forming nocardioforms found in activated sludge
Authors: Soddell Jacques A. , Seviour Robert J. , Blackall Linda L. , Hugenholtz Phil
Published: May 2018

In a numerical taxonomic survey of foam-forming actinomycetes, representatives of four groups were selected for further taxonomic study because they either did not cluster with known reference strains of nocardioforms or their relationship to them was uncertain. Phylogenetic studies, using 16S rDNA sequencing, showed that one group probably represented a previously described species, Rhodococcus erythropolis, but two possibly represented new species of Gordona and Rhodococcus. The fourth group represented an independent line of descent, possibly a new genus. These, together with strains of foam-formers Gordona amarae and Skermania piniformis, were evaluated for their growth on hydrophobic substrates likely to be found in activated sludge plants. All grew well on vegetable oils (olive, safflower and coconut) and on mixtures of hydrocarbons like paraffin oil, but at varying rates. However, growth on kerosene and hexadecane was less consistent. One feature of growth on the hydrophobic substrates was the attachment of most cells to the hydrophobic substrate rather than growth in the aqueous phase. This suggests a possible method for competing for nutrients with faster-growing (but not hydrophobic) organisms in activated sludge.
Modeling of biofouling by extracellular polymers in a membrane separation activated sludge system
Authors: Nagaoka H. , Yamanishi S. , Miya A.
Published: May 2018

A Laboratory-scale experiment was conducted to investigate the mechanism of the bio-fouling in the submerged membrane separation activated sludge system. Flat-sheet-type membrane module was used and the change of the pressure and the filtration resistance was measured. Two reactors were operated in parallel to investigate the influence of organic loading rate on the reactor performance. A mathematical model was developed to simulate temporal changes of suction pressure, flux and filtration resistance considering accumulation, detachment and consolidation of EPS on the membrane surface. Parameters in the model were determined so that the calculated results fit to the measured variation curves. The high load reactor (1.5g-TOC L−1 day−1) showed a sudden increase of the pressure and a decrease of flux after 40th days, which could not be recovered even by membrane cleanings, while the low load reactor (0.5g-TOC L−1 day−1) showed little increase of the pressure until 120th days. The measured pattern of the flux, the pressure and the resistance were well explained by the developed model. Using the model, influence of operational parameters, such as organic loading rate, flux and shear stress working on the membrane, on the reactor performance was evaluated. It was concluded that the flux is the most influential parameter and when the flux is more than a critical value, which is as low as 0.1 m day−1, maximum time during which the set flux can be maintained becomes very short.
Advanced analysis of membrane-bioreactor performance with aerobic-anoxic cycling
Authors: de Silva D. G. V. , Urbain V. , Abeysinghe D. H. , Rittmann B. E.
Published: May 2018

Mathematical modeling and intensive chemical analysis are used to quantify the relationships among the heterotrophic bacteria, autotrophic bacteria, and key inorganic (NH4+-N and NO3−-N) and organic (COD) compounds of municipal wastewater treated in a pilot-scale membrane bioreactor (MBR) operated with aerobic-anoxic cycles. Key features of the model for MBR are no biomass in the effluent, partial removal of biomass-associated products by the membrane, and D.O. cycling with 9 mg/L during aeration period and 0.5 mg/L for the anoxic period. The model explains the key trends in the cyclic data: NH4+-N is consumed only during aerobic periods and rises steadily during anoxic period; NO3−-N is produced only during aerobic periods, but declines in anoxic periods; The soluble COD in treated water mainly consists of BAP and is relatively constant through the cycle. Advantages of introducing an anoxic cycle to the continuous-flow MBR process are reduction of total effluent nitrogen, oxygen consumption, and sludge production as a consequence of denitrification. On the other hand, the anoxic period causes an increase in the average effluent NH4+-N.
Bioassay for glycogen determination in biological phosphorus removal systems
Authors: Brdjanovic Damir , van Loosdrecht Mark C. M. , Hooijmans Christine M. , Mino Takashi , Alaerts Guy J. , Heijnen Joseph J.
Published: May 2018

Glycogen plays an important role in biological phosphorus removal from wastewaters. Existing measurement techniques often overestimate the glycogen content of the biomass due to the presence of glucose and/or other carbohydrates than glycogen in the cell material. As an alternative to conventional methods a bioassay for glycogen determination in biological phosphorus removal systems was developed. The bioassay is based on the strict stoichiometric coupling between anaerobic acetate uptake and glycogen consumption. In other words, the glycogen concentration of the sludge was determined indirectly by measuring the maximal total acetate uptake by the activated sludge in anaerobic batch tests. The bioassay was successfully tested for the determination of glycogen content of the sludge taken from the lab-scale, acetate-fed, anaerobic-aerobic-settling sequencing batch reactor operating at pH 7±0.1 and temperature of 20°C. This determination of glycogen requires that glycogen (not poly-P) is the limiting factor for anaerobic acetate uptake. A method to verify this assumption based on the effect of pH on phosphate/acetate ratio is proposed and used. The bioassay is easy to apply and gives a direct measure of the glycogen content of bio-P bacteria, but its reliability still needs to be verified at full-scale biological P-removal plants.
Prediction of trace metal distribution coefficients (KD) for aerobic sediments
Authors: Koelmans Albert A. , Radovanovic H.
Published: May 2018

Distribution coefficients for suspended sediments may be estimated from water and sediment quality variables, using detailed conceptual chemical models or semi-empirical models. The predicted KD values find application in trace metal fate modelling and risk assessment. The detailed chemical model SWAMP (Sediment Water Algorithm for Metal Partitioning) which expresses trace metal distribution coefficients as a function of environmental variables and sediment characteristics was used to described field KD values. Besides SWAMP, semi-empirical models were derived from field-KD values. The field KD-values for Cd, Cu, Ni, Pb and Zn were measured on samples taken monthly from four surface waters in The Netherlands. In this paper we discuss the differences between the two modeling approaches.