bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of bacterial community in membrane-separation bioreactors by fluorescent in situ hybridization (FISH) and denaturing gradient gel electrophoresis (DGGE) techniques
Authors: Luxmy B.S. , Nakajima F. , Yamamoto Kazuo
Published: May 2018

The bacterial communities of membrane-separation bioreactors (MBR) fed with raw sewage were analyzed by a pilot scale study. The community was analyzed by both Fluorescent in Situ Hybridization (FISH) and PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) techniques. Five rRNA targeted group specific oligonucleotide probes showed that the alpha- and beta- subclasses of proteobacteria were the most dominant groups among them. The identification of ammonia-oxidizing bacteria in MBR was confirmed by three probes: NEU, Nsv 443 and Nso 190. Mostly the ammonia-oxidizers were found in groups and present in the form of clusters or aggregates. The ratio of NEU/EUB was estimated by double hybridization and image analysis techniques as 6%. The Nitrobacter sp. was also identified inside the MBR with the help of a NIT3 probe and they were also found to be present in the form of a cluster. Usually the clusters formed by the Nitrobacter sp. were smaller than those of ammonia-oxidizing groups. After numerical analysis on the band pattern of DGGE, it was found that the MBR bacterial communities were different from that of conventional activated sludge (CAS) communities with dissimilarity indexes more than 0.6. The diversity of the microbial community was estimated by the Shannon-Weaver index of general diversity. It was found that the value of the diversity index for the CAS process was 1.61 while those for two MBR processes were 1.68 and 1.59.
Dispersion studies in anaerobic ponds: implications for design and operation
Authors: Peña M. R. , Mara D. D. , Sanchez A.
Published: May 2018

The design procedure for anaerobic ponds is based on calculations of the influent volumetric organic load as a function of temperature and wastewater strength. Hydraulically either a plug flow or a completely mixed model is assumed. However, factors such as sludge sedimentation patterns, biogas bubbling and sludge accumulation may influence the hydrodynamic behaviour of the pond and hence its removal efficiency. The results obtained show that sludge accumulation and incorrect positioning of inlets and outlets influence the hydraulic performance of the ponds. The dispersion number values obtained from experimental data (δ> 0.01) show the predominance of flow mixing patterns within the ponds. Nevertheless, short-circuiting as well as dead zones coexist. Pond desludging as well as improvement of the inlet-outlet arrangements increased the removal efficiency of both BOD and TSS. It would seem that desludging of the anaerobic pond has a higher impact on the effluent quality compared with improvements to the inlets and outlets. Furthermore,the removal efficiency of suspended and soluble organic matter might be improved by enhancing mixing within the pond volume. Finally, apart from conventional dispersion studies, other tools like computational fluid dynamics are essential in order to understand the complex hydrodynamic phenomena taking place in anaerobic ponds.
Fouling performance in the filtration of water containing humic acid and/or kaolin with microporous membrane
Authors: Fukada S. , Tsuji T. , Minegishi T. , Yamamoto S. , Itazawa T. , Matsumoto K.
Published: May 2018

Acceleration tests were done using the small-scale microporous membrane (MF) module to predict the increase in transmembrane pressure at the constant flow rate dead-end filtration in a pilot plant for treating the river water or dam water. The kaolin suspension, solution of humic acid and the mixture of kaolin and humic acid were used as feed water in the acceleration tests. The conventional equations of medium blocking filtration were applied to predict the pressure increase for both pilot plant tests and small-scale ones. The experimental results are summarized as follows:

(1) The pilot plant tests: The time course of transmembrane pressure was expressed by the complete blocking filtration equation or the standard one when the unstable time at the beginning of operation was excluded.

(2) The acceleration tests using small-scale membrane module:(a) No increase in transmembrane pressure was observed when the kaolin suspension and the bentonite one were used as feed water, (b) The increasing rate of transmembrane pressure was lowered by the addition of coagulant into the humic acid solution, (c) The humic acid had a great influence on the increasing rate of transmembrane pressure in the filtration of water containing kaolin or no kaolin and (d) Similar curves of filtration time vs. transmembrane pressure were obtained in the acceleration tests as were obtained in pilot plant tests.
Understanding membrane fouling in ultrafiltration of WWTP-effluent
Authors: Roorda J.H. , van der Graaf J.H.
Published: May 2018

The application of ultrafiltration to effluent of waste water treatment plants (WWTP-effluent) is getting increasing attention. However, many experiments show a rapid decrease in flux urging frequent and intensive cleaning. In order to understand the mechanisms of the occurring fouling process, various filtration and cleaning experiments were performed, giving information about the filterability of the feedwater (F) and the reversibility of the occurring fouling layer (R). Short-term fluxes are mainly determined by the filterability, while both the filterability and the reversibility greatly affect long-term fluxes. The objective of this research is to measure the filterability of WWTP-effluent and the reversibility of the occurring fouling layer in ultrafiltration of wwtp-effluent with and without pre-treatment.

The results of the filtration experiments show a rapid decrease of flux resulting in a low value for the filterability, which also decreases during progressing filtration. The filterability is mainly related to the volume of treated water. Pre-treatment of the WWTP-effluent by in-line coagulation or by deep-bed filtration has little influence on the filterability. However, results on the reversibility show an improvement of the reversibility by pre-treatment. Both filterability of the WWTP-effluent and reversibility of the fouling layer are found to be independent of the applied flux.

As to the applied cleaning methods, the back flush is far more effective than the forward flush even if combined with air. In all experiments the remaining fouling layer still has to be removed by an intensive chemical cleaning. This research indicates the very importance of reducing the formation of an irreversible, non-removable fouling layer.
Hydrodynamics and oxygen balance in a high-rate algal pond
Authors: El Ouarghi H. , Boumansour B. E. , Dufayt O. , El Hamouri B. , Vasel J. L.
Published: May 2018

As for any other system used in wastewater treatment, it is important to know the mixing characteristics and net oxygen balance in high-rate algal ponds (HRAPs). The design of HRAPs obviously is conducive to plug flow, but with a large recirculation flow rate. The pond's treatment capacity will also depend on the net oxygen balance resulting from photosynthesis and respiration. In order to define an appropriate model describing the oxygen balance in the system, two techniques are respectively used for determining the hydrodynamic parameters and oxygen transfer coefficients of HRAPs.
Viability of nematode eggs in high rate algal ponds: the effect of physico-chemical conditions
Authors: Araki S. , González J. M. , de Luis E. , Bécares E.
Published: May 2018

The viability of Parascaris equorum eggs was studied in two experimental pilot-scale high-rate algal ponds (HRAPs) working in parallel with 4 and 10 days hydraulic retention time respectively. Semi-permeable bags of cellulose (15000 daltons pore size) were used to study the effect of physico-chemical conditions on the survival of these helminth eggs. Three thousand eggs were used in each bag. Replicates of these bags were submerged for 4 and 10 days in the HRAPs and egg viability was compared with that in control bags submerged in sterile water. After 4 days exposure, 60% reduction in viability was achieved, reaching 90% after 10 days, much higher than the 16% and 25% found in the control bags for 4 and 10 days respectively. Ionic conditions of the HRAP may have been responsible for up to 50–60% of the egg mortality, suggesting that mortality due to the ionic environment could be more important than physical retention and other potential removal factors.
Reducing phosphate discharges: the role of the 1991 EC urban wastewater treatment directive
Authors: Farmer A. M.
Published: May 2018

This paper reviews the status of implementation of the 1991 EC urban wastewater treatment Directive in relation to its requirements for phosphate removal from wastewater discharges. Transposition of the Directive is satisfactory in most Member States as is implementation of requirements regarding collection and secondary treatment of sewage, with the notable exceptions of Belgium and Italy. A range of approaches has been adopted for the designation of sensitive areas under the Directive and designation is still not complete. It is likely that most Member States will have met the treatment requirements for sensitive areas by the end of 1998. Exceptions will include France and Spain (where implementation will be incomplete), the UK (which designated more sensitive areas in 1998 and will meet requirements for these at a later date) and Greece and Italy (for which sensitive area designation is lacking or uncertain). The Commission has indicated that it will examine compliance for both designation and treatment closely. This may place further pressure on Member States to designate further sensitive areas. It is estimated that currently in ten EU Member States, containing 90% of the EU population, about 375,000 tonnes of phosphorus are produced in domestic wastewater each year. In 1994 39-45% of this was removed in wastewater treatment works.
Biolog for the determination of microbial diversity in activated sludge systems
Authors: van Heerden J. , Ehlers M. M. , Cloete T. E.
Published: May 2018

In this study, different carbon source profiles were generated by inoculating Biolog GN microwell plates, with different dilutions of microbial communities from a number of activated sludge systems. This led to the successful generation of patterns reflecting diversity and evenness in the different systems. The high number of substrates utilized at the lower dilutions (10–1 and 10–2) indicated a high microbial diversity in the community, but not necessarily evenness of each species. Evenness of each species was reflected upon further dilution. Our results indicated differences in the microbial community composition amongst some of the activated sludge systems studied. These differences were not specifically related to phosphate removing and non phosphate removing systems.
Development of a real-time control strategy with artificial neural network for automatic control of a continuous-flow sequencing batch reactor
Authors: Cho B. C. , Liaw S.-L. , Chang C.-N. , Yu R.-F. , Yang S.-J. , Chiou B.-R.
Published: May 2018

The purpose of this study is to develop a reliable and effective real-time control strategy by integrating artificial neural network (ANN) process models to perform automatic operation of a dynamic continuous-flow SBR system. The ANN process models, including ORP/pH simulation models and water quality ([NH4+-N] and [NOx--N]) prediction models, can assist in real-time searching the ORP and pH control points and evaluating the operation performances of aerobic nitrification and anoxic denitrification operation phases. Since the major biological nitrogen removal mechanisms were controlled at nitritification (NH4+-N→NO2--N) and denitritification (NO2--N→N2) stages, as well as the phosphorus uptake and release could be completely controlled during aerobic and anoxic operation phases, the system operation performances under this ANN real-time control system revealed that both the aeration time and overall hydraulic retention time could be shortened to about 1.9-2.5 and 4.8-6.2 hrs/cycle respectively. The removal efficiencies of COD, ammonia nitrogen, total nitrogen, and phosphate were 98%, 98%, 97%, and 84% respectively, which were more effective and efficient than under conventional fixed-time control approach.
Effects of temperature on biodegradation characteristics of organic pollutants and microbial community in a solid phase aerobic bioreactor treating high strength organic wastewater
Authors: Lim B.-R. , Huang X. , Hu H.-Y. , Goto N. , Fujie K.
Published: May 2018

The BOD removal rate and microbial community structure in a solid phase aerobic bioreactor using polyvinyl alcohol gel particles as packing material for the treatment of high strength organic wastewater were investigated at various temperatures. The BOD removal rate in the bioreactor increased when the temperature increased from 20°C to 30°C, 40°C, and 50°C, but it decreased when the temperature increased from 50°C to 60°C. Higher temperature enhanced the endogenous respiration of microbes in the bioreactor. The microbial community structure in the bioreactor was analyzed with quinone profile. The experimental results showed that the microbial community structure in the bioreactor was significantly affected by temperature. The dominant quinone of the microbes inhabiting the bioreactor was ubiquinone-8 at 30°C, but that at 50°C and 60°C was menaquinone-7. It was estimated that the thermophilic Bacillus having menaquinone-7 dominated in the bioreactor at higher temperature. The microbial diversity in the bioreactor varied with temperature.
Sludge digestion enhancement and nutrient removal from anaerobic supernatant by Mg(OH)2 application
Authors: Wu Q. , Bishop P. L. , Keener T. C. , Stallard J. , Stile L.
Published: May 2018

Anaerobic sludge digestion is a widely adopted process for sludge stabilization. Phosphate removal from anaerobic supernatant is necessary to limit the phosphate returned to the head of the treatment plant, thereby improving the overall treatment efficiency. In this study, magnesium hydroxide (Mg(OH)2) was used to improve the sludge digestion efficiency and to remove phosphorus from anaerobic supernatant. The anaerobic sludge digestion experiment was conducted at a pilot scale, and the results showed that applying Mg(OH)2 to anaerobic sludge digester resulted in a larger reduction in SS and COD, a higher biogas production rate, a lower level of phosphate and ammonia nitrogen concentrations in the sludge supernatant and an improved sludge dewaterability. Research results at both lab scale and pilot scale on phosphorus removal from anaerobic supernatant using Mg(OH)2 showed that a high removal of phosphorus can be achieved through the addition of Mg(OH)2. The required reaction time depends on the initial phosphorus concentration and the Mg(OH)2 dosage.
Transformation of lipids in activated sludge
Authors: Dueholm T. E. , Andreasen K. H. , Nielsen P. H.
Published: May 2018

Transformation of lipids in activated sludge treatment plants is of interest for two reasons: lipids contribute 30–40% of the chemical oxygen demand (COD) in wastewater, and they may stimulate the growth of filamentous microorganisms in nutrient removal activated sludge plants. The transformation of lipids was investigated under aerobic and anoxic conditions by measuring the oxygen and nitrate uptake rates (OUR and NUR). The maximal OUR and NUR of long-chain fatty acid was found to be at the same level as acetate indicating that long-chain fatty acid was as easily consumable. However, the adsorption of long-chain fatty acid to surfaces of sludge flocs made it difficult to determine initial uptake rates of long-chain fatty acids. It was not possible to describe the hydrolysis rate of triacylglyceride by OUR and NUR to long-chain fatty acids because the hydrolysis rate was very slow. For a better description of the processes involved in transformation of lipids, a conceptual model was suggested. The processes in the suggested model were the adsorption/desorption of both triacylglyceride, and long-chain fatty acid onto surfaces of sludge flocs, hydrolysis of triacylglyceride by lipases and the uptake of long-chain fatty acid by bacteria under various conditions. The model can be helpful to structure design and evaluation of activated sludge experiment with lipids.
Denitrification in submerged biofilters of concentrated-nitrate wastewater
Authors: Oh J. , Yoon S. M. , Park J. M.
Published: May 2018

To understand the possibilities and limitations of the treatment of concentrated nitrate in wastewater, a space-saving biofilm process was introduced to investigate how efficiently concentrated nitrate was utilized in a biofilm process. Lab-scale submerged biofilters stuffed with plastic pall-ring media were developed for the treatment of wastewater containing high nitrate concentration. Two identical biofilters were operated at 2 and 4 hr media HRT in parallel and the concentration of nitrate in the influent was increased stepwise from 50 to 3000 mg-N/L. The concentration of NOx in the effluent was measured at various volumetric loading rates that were proportional to influent nitrate concentrations. There was a critical point for volumetric loading rate (9 kg NO3–N/m3/day) distinguishing the biofilter performances. At the volumetric loading rate below this critical point, the effluent NOx concentration was maintained steadily in spite of the drastic change in the loading rates. However, the effluent NOx concentration severely fluctuated for the small change when the loading rate was higher than the critical point. It was found that the reactor performance was closely related with the biomass concentration (g-dw/ring) in the biofilters.
Feasibility of the BIOFIX-process for treatment of municipal wastewater
Authors: Temmink H. , Klapwijk A. , de Korte K. F.
Published: May 2018

The feasibility of the so-called BIOFIX-process to treat municipal wastewater was investigated in a pilot-plant. The innovative element of this process is that carrier material to which a biofilm is attached is recirculated between a sorption reactor to take up COD from the wastewater and a reactor where this COD is used for (post-) denitrification. In between the sorption and denitrification reactor the wastewater passes two subsequent reactors for removal of the remaining COD and for nitrification, respectively. The results showed that COD uptake by the biofilm in the sorption reactor with a maximum of 34% of the influent load was far below expectations and did not meet the COD requirement for denitrification (50–60% uptake). Also, 9–21% of the influent load of ammonia was taken up by the biofilm. In the denitrification reactor this ammonia was released to the bulk and in this manner discharged with the effluent without having passed the nitrification reactor. Nitrification was inhibited by the presence of high concentrations of suspended solids (50–60 mgl–1) discharged from a COD removal reactor. Together these bottle-necks caused effluent concentrations which were well above the effluent demands and it therefore can be concluded that the BIOFIX-process is not a feasible process to treat domestic wastewater.
Removal of organics from wastewater using a novel biological hybrid system
Authors: Al-Sharekh H. A. , Hamoda M. F.
Published: May 2018

This paper summarizes the results obtained using the hybrid aerated submerged fixed-film (HASFF) process. HASFF is an innovative system comprising a four-compartment reactor having an array of fixed ceramic plates maintained under diffused aeration to support attached biomass, with activated sludge recycle to promote suspended growth in the reactor. Wastewater from a municipal treatment plant was fed to the reactor and its activated sludge was used for recycling in the hybrid system. Four pilot units were operated in the plant at various hydraulic retention times, HRTs (2, 4, 6 and 8 h), using primary-settled wastewater under organic loading rates up to 0.7 g BOD/gMLTVS · d. Data obtained showed that the overall BOD percentage removal efficiencies were consistently above 94.0% at all HRTs including the 2 hours while the COD percentage removal efficiencies ranged between 65.7–76%. The effluent's mean filtered BOD concentration ranged between 4.5–7.5 mg/l whereas the mean filtered COD concentration ranged between 70.0–89.6 mg/l. Increasing the hydraulic loading rate by four-folds from 0.08 to 0.32 m3/m2 · d had a minor effect on the unit's BOD and COD percentage removal efficiencies indicating a robust biological process that is resilient to hydraulic shock loads, thereby offering a viable upgrading option.
Advanced treatment of sewage by pre-coagulation and biofilm process
Authors: Tsuno H. , Somiya I. , Kanjo Y. , Hidaka T.
Published: May 2018

Treatment performance and operational parameters of a pre-coagulation and biofilm process were experimentally discussed with the pilot-scale plant treating actual municipal sewage. Perfect nitrification was accomplished within total hydraulic retention time (HRT) of 4 h at 20% volumetric added ratio of attached-growth media of biofilm in the aerobic tanks under temperature conditions as low as 17°C. Treatment efficiencies in organic matter, T–N and T–P were high and stable with the total HRT of 8 h in the biological reactor. Concentrations of T–N and T–P in effluent were kept about 2 mgN/L and under 1 mgP/L, respectively. Attached growth bacterial mass and the potential activity of nitrification and denitrification in each tank in cold season were high enough to accomplish excellent treatment performance. Then the process was proved to be applicable to municipal sewage treatment for removal of nitrogen and phosphorus as well as organic matter.
Stability of a lab-scale biofilm for simultaneous removal of phosphorus and nitrate
Authors: Falkentoft C. , Harremoës P. , Mosbæk H. , Wilderer P.
Published: May 2018

A lab-scale biofilm reactor for simultaneous removal of phosphorus and nitrate was operated for one and a half years. Despite using only well defined synthetic wastewater and well defined operation, the activity varied significantly over the months. It was speculated that microbial population shifts were causing this phenomenon. This could also explain a sudden break down of the process following a slight change in the operation. Over shorter periods of time (time-scale:days), the biofilm could be considered stable enough to perform series of comparable batch experiments. Batch experiments with different start concentrations of acetate, nitrate or phosphate were conducted. These verified 0.5 and 0 order removal rates in the bulk water depending on the concentration. This was taken as an indication of a zonation of the biofilm. Due to the measured variability in the activity and due to the importance of the history of the bacteria when considering biological P removal, on-line measurements are strongly recommended for research on this subject. Microbial characterisation methods are recommended as an assisting tool in further research.
Ecological co-inhabitance index (ECI) as a management tool for ecosystem preservation in rivers
Authors: Yoshimura C. , Kumagai Y. , Fukushi K. , Omura T.
Published: May 2018

The number of novel man-made hazardous substances produced by industries is increasing year after year, resulting in conventional discharge standards ineffective to preserve the natural ecological environment. A novel index, ecological co-inhabitance index (ECI), was proposed in order to evaluate the river ecosystem sensitively. The river benthic community with a high value of ECI is formed in the healthy ecosystem where benthic animals can share resources in the river environment efficiently, keep the ecosystem functioning, and give the least adverse effect to lower reaches of the river. In order to clarify the characteristic of ECI, the relationship between ECI and water quality in the river was investigated using the data on benthic animals obtained from 17 various rivers. Results of this investigation indicated that ECI could synthetically evaluate the river environment without a bias toward a specific water quality. Moreover, ECI had the significant correlation coefficients with diversity index, biotic index and pollution index at significance level 0.05, respectively. Therefore, ECI is a promising index for managing the river ecosystem.
Ozone treatment for biorefractory COD removal
Authors: Baig S. , Liechti P. A.
Published: May 2018

A two case study of industrial wastewater treatment is reported in order to prove the suitability of ozonation for biorefractory COD removal. The ozone application as an end treatment is shown to provide an excellent oxidation yield of organic matter in a landfill leachate. The combination of ozonation and fixed bed biofilm process appears quite effective for the post-treatment of two biological effluents from paper industry.
Kinetics of azoreductase and assessment of toxicity of metabolic products from azo dyes by Pseudomonas luteola
Authors: Hu T.-L.
Published: May 2018

This is a continuous study on a decolorization strain, Pseudomonas luteola, which involves treating seven azo dyes with different structures. This study focuses mainly on determining both the mechanism of decolorization by P. luteola and the activity of azoreductase from P. luteola as well as identifying and assessing the toxicity of metabolic products of azo dyes.

The growth of P. luteola reached the stationary phase after shaking incubation for 24 hours. Then, while being kept static, the color of seven tested azo dyes (100 mg/l) could be removed. The proportion of color removal was between 59–99%, which figure is related to the structure of the dye. Monoazo dyes (RP2B, V2RP and Red 22) showed the fastest rate of decolorization, i.e. from 0.23–0.44 mg dye-mg cell–1 hr–1. P. luteola could remove the color of V2RP and a leather dye at a concentration of 200 mg/l, and as to the rest of the azo dyes, it could remove at a concentration of up to 100 mg/l.

Decolorization of RP2B and Red 22 required activation energy of 7.00 J/mol and 6.63 J/mole, respectively, indicating that it was easier for azoreductase to decolorize structurally simple dyes. The kinetics of azoreductase towards seven azo dyes suggested a competitive inhibition model be applied.

Microtox® was used to analyze the toxicity of the metabolic products of azo dyes. EC50 showed differences in toxicity before and after the azo dyes had been metabolized. Analysis revealed significant differences between the results obtained by EC50 with Blue 15 and those obtained with the leather dye, indicating that the toxicities of the metabolic products were increased. The differences obtained by EC50 with Red 22, RP2P and V2RP were small, and Black 22 showed no such difference. Sulfanic acid and orthanilic acid may be the intermediate products of Violet 9 and RP2B, respectively. However, according to FT-IR analysis, aromatic amines were present in the metabolic product.
Fungal mediated decolorization of media containing procion dyes
Authors: Sumathi S. , Manju B. S.
Published: May 2018

An isolated fungus, Aspergillus foetidus was found to effectively decolorize media containing azo reactive dyes, namely Procion dyes, under aerobic conditions. The extent of colour removal was 90% within 48 h of growth of the fungus. The entire colour was found to be strongly bioadsorbed to the rapidly settling spherical fungal biomass pellets. Our investigations reveal that the process of decolorization is concomitant with the exponential growth phase of the fungus and has an obligate requirement for a biodegradable substrate such as glucose. Kinetic analyses of fungal decolorization indicate that the rates of colour uptake decrease to a significant extent with increasing initial concentrations of dye. The fungus was able to grow and decolorize media in the presence of 5 ppm of chromium and 1% sodium chloride. An alternate and cheaper carbon source such as starch supported the growth and decolorization process. These results suggest that the dye uptake process mediated by Aspergillus foetidus has a potential for large-scale treatment of textile mill discharges.
Removal of chlorinated pollutants by a combination of ultrasound and biodegradation
Authors: Tiehm A. , Kohnagel I. , Neis U.
Published: May 2018

Chlorinated organic compounds are hazardous pollutants found in waste water, surface water, and ground water. Our study shows that a combination of ultrasonic pretreatment and biodegradation effectively removes the solvent chlorobenzene and the disinfectant 2,4-dichlorophenol, also reduces Adsorbable Organic Halogens (AOX) and Chemical Oxygen Demand (COD). In our experiments, the ultrasonic dechlorination was not influenced by the presence of other soluble organic compounds like acetate or glucose. Dechlorination of chlorobenzene by ultrasound did not lead to toxic or inhibiting reaction products. More than that, the ultrasonic pretreatment significantly reduced the toxicity of 2,4-dichlorophenol and biological activity was initiated after sonication. Residual organic pollutants after ultrasonic pretreatment were eliminated by biodegradation.
Nitrification in sequencing biofilm batch reactors: lessons from molecular approaches
Authors: Daims H. , Purkhold U. , Bjerrum L. , Arnold E. , Wilderer P. A. , Wagner M.
Published: May 2018

The nitrifying microbial diversity and population structure of a sequencing biofilm batch reactor receiving sewage with high ammonia and salt concentrations (SBBR 1) was analyzed by the full-cycle rRNA approach. The diversity of ammonia-oxidizers in this reactor was additionally investigated using comparative sequence analysis of a gene fragment of the ammonia monooxygenase (amoA), which represents a key enzyme of all ammonia-oxidizers. Despite the “extreme” conditions in the reactor, a surprisingly high diversity of ammonia- and nitrite-oxidizers was observed to occur within the biofilm. In addition, molecular evidence for the existence of novel ammonia-oxidizers is presented. Quantification of ammonia- and nitrite-oxidizers in the biofilm by Fluorescent In situ Hybridization (FISH) and digital image analysis revealed that ammonia-oxidizers occurred in higher cell numbers and occupied a considerably larger share of the total biovolume than nitrite-oxidizing bacteria. In addition, ammonia oxidation rates per cell were calculated for different WWTPs following the quantification of ammonia-oxidizers by competitive PCR of an amoA gene fragment. The morphology of nitrite-oxidizing, unculturable Nitrospira-like bacteria was studied using FISH, confocal laser scanning microscopy (CLSM) and three-dimensional visualization. Thereby, a complex network of microchannels and cavities was detected within microcolonies of Nitrospira-like bacteria. Microautoradiography combined with FISH was applied to investigate the ability of these organisms to use CO2 as carbon source and to take up other organic substrates under varying conditions. Implications of the obtained results for fundamental understanding of the microbial ecology of nitrifiers as well as for future improvement of nutrient removal in wastewater treatment plants (WWTPs) are discussed.
Generation and properties of aerobic granular sludge
Authors: Etterer T. , Wilderer P. A.
Published: May 2018

A sequencing batch reactor (SBR) was used to investigate the generation of different granules cultured under aerobic and alternating anaerobic/aerobic conditions. The reactor was fed with synthetic wastewater. A substrate loading rate of 3.6 kg COD/ (m3 day) was applied. Granules of heterotrophic microorganisms were formed. After the first experimental period of 8 weeks the average granule diameter was 3.2 mm. In the second period, alternating anaerobic/aerobic conditions were applied to form granular sludge with an average diameter of 3.0 mm. An isopycnic centrifugation procedure was used to determine the characteristic density of the aerobic granular sludge. The average density of the granular sludge was 1.044 g/ml and 1.048 g/ml, respectively. In free-settling tests the final settling velocity of single aggregates was examined to estimate porosity. Settling velocities up to 2.0 cm/s could be measured. Calculations based on the experimental results showed an average granula porosity of 72% for the first run and 65% average porosity for the second run. This paper indicates the validity of general assumptions in free-settling tests.
Comparative investigations on COD-removal in sequencing batch reactors and continuous flow plants
Authors: Dockhorn T. , Dichtl N. , Kayser R.
Published: May 2018

Investigations on enhanced COD removal from municipal wastewater were performed over a period of 2.5 years, comparing three different types of reactor. The main idea was to determine the influence of the mixing characteristics of the reactor on the treatment processes and the effluent quality. Therefore three pilot plants (a completely mixed reactor, a cascade of three reactors and a SBR) were operated under equal conditions (wastewater, hydraulic load, temperature, sludge age) in parallel to each other. Investigations were carried out at different sludge ages. It could be shown that within one sludge age the CODf removal efficiency increased, when mixing characteristics came closer to the plug flow and it also increased with higher temperatures. A significant correlation was observed between the COD removal efficiency and the sludge load. The higher the sludge load was the greater the CODf concentration in the effluent. Especially the SBR reactor showed an excellent performance under the given operating conditions. Dynamic simulation calculations were carried out, to investigate whether the influence of the type of reactor on the COD-elimination could be described theoretically by combining growth kinetics and the mixing characteristics of the individual reactors. The results showed that performance was better when mixing characteristics came closer to plug flow.
Biological denitrifying phosphorus removal in SBR: effect of added nitrate concentration and sludge retention time
Authors: Merzouki M. , Bernet N. , Deigenès J.-P. , Moletta R. , Benlemlih M.
Published: May 2018

Optimizing anoxic biological phosphorus removal in the anaerobic-anoxic sequencing batch reactor (A2 SBR) was observed to depend on two parameters: the amount of added nitrate and the sludge retention time (SRT). The concentration of 120 mg N-NO3 · l-1 in the anoxic medium and the SRT of 15 days were determined as optimal for a complete phosphorus removal in the A2 SBR. The reactor was supplied with synthetic wastewater containing 800 mg COD.l-1 acetic acid, 240 mg N-NH4·l-1 and 30 mg P-PO4·l-1. This study was completed by microscopic observations which revealed three morphological types of phosphate-accumulating bacteria (PAB).
Simulation and applications of a novel modified SBR system for biological nutrient removal
Authors: Wu W. , Timpany P. , Dawson B.
Published: May 2018

Dynamic simulation and applications of a novel, continuous-fed, constant level modified sequencing batch reactor for biological nutrient removal are presented. The underlying mathematical model and practical applications of the simulation are discussed. Case studies are presented to illustrate the applications as well as the flexibility of the system in meeting different wastewater treatment requirements. Operation experience from full-scale wastewater treatment plant demonstrates the reliability, ease of operation and high efficiency of the system. Average BOD5, total nitrogen, total phosphorus and TSS removals of 97, 81, 88 and 94% are achieved respectively on an annual basis with little operator attention. Consistently high waste activated sludge concentrations are demonstrated, averaging approximately 20,000 mg/L.
Period biofilter operation for enhanced performance during unsteady-state loading conditions
Authors: Irvine R. L. , Moe W. M.
Published: May 2018

In conventional biofilter operation, contaminated air is passed continuously through packed beds containing microbial consortia capable of contaminant biotransformation. This paper describes how biofilters can be designed and operated as controlled unsteady-state, periodic processes for the destruction of gas-phase contaminants. Such operation, previously limited to applications in wastewater treatment and soil remediation, increases an operator's ability to control the physiological state, “robustness,” and spatial distribution of the microbial communities established within the biofilter and, thus, minimizes uncertainties that often accompany design and operation of biological systems. Results are presented from toluene degrading biofilters that used polyurethane foam packing medium. These studies demonstrate how controlled periodic operations can enhance contaminant removal during transient periods of elevated contaminant load.
Characterization and treatment of the liquid effluents from the anaerobic digestion of biogenic solid waste
Authors: Graja S. , Wilderer P. A.
Published: May 2018

The process wastewater generated by the fermentation of biogenic fractions of solid waste (biowaste) is characterized by very specific composition features, which sets it apart from the well known categories of wastewater. Up to now, there is a definite lack of practical experience and know-how in the treatment of those effluents. In view of the increasingly wide acceptance awarded to the fermentation process, it appears necessary, however, to include the treatment of the generated wastewater in the overall process and to grant it the same priority as the fermentation step. In this study, pilot-scale experiments were conducted over 200 days in a sequencing batch reactor (SBR), with the wastewater from a full-scale Bavarian biowaste digestion plant. Characterization of the influent implementing molecular size distribution studies showed that 97% of the components were either in particular form or <1 kD. The main classes of compounds present in these fractions have been identified. The treatment objectives of the SBR plant were carbon and nitrogen removal. Soluble COD removal efficiencies were comprised between 40 and 60%, yielding a residual, refractory COD concentration of about 2000 mg/L in the effluent. Ammonium removal efficiencies averaged 96% and denitrification occurred with the addition of acetic acid or pretreated biowaste as a carbon source. Pretreated biowaste also showed synergetic effects as a co-substrate for COD removal.
Creating anoxic and microaerobic conditions in sequencing batch reactors treating volatile BTX compounds
Authors: Ma G. , Love N. G.
Published: May 2018

An experimental strategy is introduced for studying the biodegradation of wastewaters containing volatile contaminants using an alternating anoxic/microaerobic sequencing batch reactor (SBR). Benzene, toluene, and the xylene isomers (BTX) served as model volatile contaminants for this study. The reactor was configured to overcome stripping the volatile BTX compounds into the atmosphere to provide opportunities for BTX biodegradation. Oxygen-free anoxic and microaerobic (< 0.2 mg/L dissolved oxygen) conditions were established using a novel laboratory reactor configuration. ORP was successfully used to monitor different electron acceptor conditions in the SBR. Toluene and m-xylene were amenable to anoxic (denitrifying) metabolism while benzene, o-, and p-xylene were biodegradable under microaerobic conditions. The results demonstrate that establishing microaerobic conditions in full-scale bioreactors may be an appropriate way to encourage the biodegradation of aerobically biodegradable volatile contaminants. Additionally, the laboratory reactor configuration introduced in this paper may be useful in subsequent studies involving microaerobic metabolism.
Explosive biodegradation in soil slurry batch reactors amended with exogenous microorganisms
Authors: Shen C. F. , Hawari J. A. , Paquet L. , Ampleman G. , Thiboutot S. , Guiot S. R.
Published: May 2018

The present study explores the feasibility of biotreatment of 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)-contaminated soils in slurry batch reactors. Radiorespirometric assays showed that anaerobic sludge was able to mineralize 59% RDX to CO2 although significant mineralization of TNT was not observed in all cases. TNT and RDX at concentrations higher than 50 and 100 mg/L respectively were inhibitory to methanogenesis (used as a bioindicator), however, methanogenesis recovered after TNT was transformed into less toxic triaminotoluene. Bioslurry batch reactors containing 40% of contaminated soil (2000 mg RDX and 1000 mg TNT/kg dry soil) were operated under various conditions. Both TNT and RDX were persistent to soil indigenous microbes. Degradation of both TNT and RDX was enhanced by the municipal sludge amendment, although degradation of RDX was only achieved under anaerobic conditions.
Cyclic activated sludge technology - recent operating experience with a 90,000 p.e. plant in Germany
Authors: Demoulin G. , Rüdiger A. , Goronszy M. C.
Published: May 2018

Cyclic activated sludge technology was selected for the Potsdam Wastewater Treatment Plant (90,000 p.e.). The cyclic activated sludge facility comprises four modules integrated into two circular basins. Construction was commenced in February 1998 with seeding of the plant for start up taking place in October 1998. Process performance has been met since Spring 1999 at 80-90% of design load. In order to optimize start-up procedures, respiration rates were used as a guidance for process stabilization and online process optimization during normal operation. Operation for co-current nitrification denitirification provided an ammonia removal of 1.1 mg NH4-N/gMLSS · h (15°C) and a corresponding nitrate respiration rate of 0.85 mg NO3-N/gMLSS · h under aerated conditions. Enhanced biological phosphorus removal generated an effluent mean total phosphorus concentration of 0.38 mg/L without precipitant addition.
Sequencing batch reactor technology: the key to a BP refinery (Bulwer Island) upgraded environmental protection system - a low cost lagoon based retro-fit
Authors: Hudson N. , Doyle J. , Lant P. , Roach N. , de Bruyn B. , Staib C.
Published: May 2018

BP Refinery (Bulwer Island) Ltd (BP) located on the eastern Australian coast is currently undergoing a major expansion as a part of the Queensland Clean Fuels Project. The associated wastewater treatment plant upgrade will provide a better quality of treated effluent than is currently possible with the existing infrastructure, and which will be of a sufficiently high standard to meet not only the requirements of imposed environmental legislation but also BP's environmental objectives. A number of challenges were faced when considering the upgrade, particularly; cost constraints and limited plot space, highly variable wastewater, toxicity issues, and limited available hydraulic head. Sequencing Batch Reactor (SBR) Technology was chosen for the lagoon upgrade based on the following; SBR technology allowed a retro-fit of the existing earthen lagoon without the need for any additional substantial concrete structures, a dual lagoon system allowed partial treatment of wastewaters during construction, SBRs give substantial process flexibility, SBRs have the ability to easily modify process parameters without any physical modifications, and significant cost benefits. This paper presents the background to this application, an outline of laboratory studies carried out on the wastewater and details the full scale design issues and methods for providing a cost effective, efficient treatment system using the existing lagoon system.
Use of activated carbon and natural zeolite as support materials, in an anaerobic fluidised bed reactor, for vinasse treatment
Authors: Fernández N. , Fdz-Polanco F. , Montalvo S. J. , Toledano D.
Published: May 2018

In Cuba, the alcohol distillation process from cane sugar molasses, produces a final waste (vinasse), with an enormous polluting potential and a high sulfate content. Applying the anaerobic technology, most of the biodegradable organic matter can turn into biogas, rich in methane but with concentrations of sulfide above 1%. The present work develops two experiences with anaerobic fluidized bed reactors (AFBR) using both Cuban raw material, activated carbon and natural zeolite, as support media, with the purpose of obtaining high organic matter removal rates and keeping sulfide and ammonium concentrations in the permissible ranges. The reactors were operated during 120 days, achieving an organic loading rate of 10 kg COD/m3 day, with COD removal above 70%, and a methane production of 2 L/d. The activated carbon and natural zeolite used support materials in anaerobic fluidized bed reactors, and showed good results of distillery waste removal.
Missing and neglected links in water management
Authors: Biswas K.
Published: May 2018

In the current revolution in water management; issues that must be addressed include both urbanisation and ruralisation, water quality, and globalisation and energy policy. Water management must struggle against inappropriate research, myths and inadequate data
Effects of organic, hydraulic and fat shocks on the performance of UASB reactors with intermittent operation
Authors: Nadais H. , Capela I. , Arroja L. , Duarte A.
Published: May 2018

Three lab-scale UASB reactors operated at 35°C in an intermittent mode were subject to different step shocks: hydraulic, organic and feed fat content. The results show that the reactors have good resistance to the applied shocks and suggest that a feedless period is beneficial to the performance of the reactors, due to stabilisation of accumulated organic matter.
The critical role of water in sustainable growth
Authors: Tebo Paul V.
Published: May 2018

Business can play an important role in protecting and improving water quality by: raising public awareness; reducing and recycling water within manufacturing operations; reducing the use of/impact on water in the use of products; forming partnerships with private sector organizations focused on pilot programs to improve water quality; and by integrating water as a critical and strategic issue in all business strategies.
Sustainable urban water systems in rich and poor cities - steps towards a new approach
Authors: Newman Peter
Published: May 2018

The ‘big pipes in, big pipes out’ approach to urban water management was developed in the 19th century for a particular linear urban form. Large, sprawling car-dependent cities are pushing this approach to new limits in rich cities and it has never worked in poor cities. An alternative which uses new small-scale technology and is more community-based, is suggested for both rich and poor countries. The Sydney Olympics and a demonstration project in Java show that the approach can work.
Enhanced decolourisation of acid orange 7 in a continuous UASB reactor with quinones as redox mediators
Authors: Cervantes F. J. , van de Zee F. P. , Lettinga G. , Field J. A.
Published: May 2018

The reductive biotransformation of acid orange 7 (AO7) was explored in a lab-scale upflow anaerobic sludge blanket (UASB) reactor at low hydraulic residence times (HRT). A colour removal of 85% was achieved when the reactor was operated at a HRT of 6 hours, but decreased up to 70% when the HRT was lowered to 2 hours. Addition of the quinone model compound, anthraquinone 2,6-disulfonate (AQDS), as redox mediator, allowed for a considerably higher decolourising efficiency (>90% at all the HRT evaluated). The results indicate that the use of catalytic concentrations of AQDS (AQDS/AO7 molar ratio about 0.01) can accelerate decolourising processes achieving satisfying extent of decolourisation.