bluuebunny/crossref_metadata_2025 huggingface dataset:
SCREENING OF CHEMICAL SPILL RISKS TO MUNICIPAL SEWAGE TREA TMENT PLANTS
Authors: Ettala M. , Rossi E.
Published: May 2018

Seven operational mishaps were specified on the basis of a questionnaire on wastewater treatment plants, some of them large. In this study a process was developed for screening the chemical spill risks to municipal biological sewage treatment plant. Data on wastewater treatment processes, potential spill sources and chemical properties were combined to determine the threshold chemical quantities which may inhibit the removal of carbonaceous material, prevent nitrification and methanogenesis, cause sludge contamination or lead to the aeration capacity being exceeded. Two sewage treatment plants and eleven industrial sites were chosen for field studies. The influence of spill duration and maintenance activities on threshold quantities are discussed. A field survey lasting 1-2 hours at each site was long enough for the most relevant data to be obtained when the screening method developed was applied. Several chemical spill risks to the plants studied were specified. In addition, cases were identified in which failure of the pretreatment facilities for industrial wastewaters could cause severe mishaps at a biological wastewater treatment plant.
Use of Artificial Wetlands for the Treatment of Recreational Wastewater
Authors: Vincent Gilles
Published: May 2018

In June 1990 the City of Montreal opened a beach on an artificial lake where a wetland was built to maintain water quality. Occupying an area of 20 000 m2, the wetland consists of four ponds of varying depth where more than 100 000 aquatic plants of different native species were introduced. Intake pipes draw 140 1 sec−1 of water into the first pond and water then circulates by gravity through the three remaining ponds. During 1990 and 1991 several parameters were monitored in order to evaluate the efficiency of the system. The ponds proved to be very good traps for O-PO4 and NO−3. A good interception of soluble phosphorus and suspended solids was also observed. Removal of faecal coliforms however, seems uncertain and long-term effectiveness is also uncertain.
PERFORMANCE OF ROTARY DISK MODULES IN A COLLECTED HUMAN EXCRETA TREATMENT PLANT
Authors: Ohkuma N. , Shinoda T. , Aoi T. , Okaniwa Y. , Magara Y.
Published: May 2018

The tubular type and plate-and-frame type are two conventional kinds of membrane modules used for collected human excreta treatment. However. such modules are hindered by high power consumption. blocking of the membrane by fiber components. the need for frequent cleaning and other such problems. Here, the authors investigated the performance and stability of a collected human excreta treatment plant utilizing rotary disk modules developed for the separation of highly concentrated liquid. As a result, it was found that, whether treating activated sludge or coagulated sludge, continuous operation over more than six months can be achieved at a low power consumption and without chemical cleaning. By this the authors have shown that rotary disk modules can be applied to the treatment of highly concentrated residential wastewater.
Treatment of Nitrogen and Phosphorus by a Constructed Upland-Wetland Wastewater Treatment System
Authors: House C. H. , Broome S. W. , Hoover M. T.
Published: May 2018

An Upland-Wetland wastewater treatment system was installed in Pamlico County, North Carolina in September 1989 to test its effectiveness in wastewater treatment for a single family home. Treatment effectiveness was evaluated from March 1990 to September 1991. The mound provided an aerobic environment that resulted in complete nitrification and reduction of phosphorus. Concentration of total nitrogen (TN) was lowered 64%, from 44.4 mg/L to 16.0 mg/L by the mound component. Nitrogen in the wastewater dosed into the mound was in the ammonium (NH4N) and organic forms, while essentially all the nitrogen present in water that had passed through the mound was in the nitrate (NO3N) form. The mound lowered total phosphorus (TP) concentration 86%, from 4.4 mg/L to 0.6 mg/L. The wetland cell planted with Phragmites australis was more effective than both the implanted cell and the cell planted with Typha angustifolia. Concentrations of (TN), primarily NO3N, were lowered from 16.0 mg/L to 11.1 mg/L or of that entering the cell. Total phosphorus was lowered 31%, from 0.6 mg/L to 0.3 mg/L. The Upland-Wetland Wastewater Treatment System has provided low cost, low maintenance and effective wastewater treatment.
Nutrient Transformations in a Natural Wetland Receiving Sewage Effluent and the Implications for Waste Treatment
Authors: Cooke James G.
Published: May 2018

The processes influencing nutrient (phosphorus and nitrogen) renovation in a natural wetland which had received oxidation pond effluent for twelve years were studied, and compared with current literature perceptions. Mass transport studies showed that 30–70% of the influent P was removed from the water column, which was much greater than published values suggest could be predicted for this highly loaded (∼ 34 g P m−2 y−1) system. Sediment traps studies showed that deposition of particulate P immediately downstream of confluences with arms of the wetland not impacted by sewage effluent (natural wetlands) was the dominant cause of P removal. Separation of the deposited-P into chemically definable fractions along with studies on the water chemistry, suggested that P deposition was associated with iron-organic complexes contributed dominantly from the natural wetlands.

Considerable spatial and temporal heterogeneity was also demonstrated for nitrogen transformations. During summer most of the influent-N was in nitrate form which was all transformed during passage through the wetland. Isotope (15N) dilution studies indicated that ∼ 60–70% was denitrified, 25–35% converted to ammonium (dissimilatory reduction), and 5–10% assimilated. For most of the year, however, influent N was mainly in reduced forms. Despite this, significant quantities of nitrate were exported from the wetland especially at higher flows in spring-early summer. Assays on the sediment showed that there was a marked increase in nitrification activity at the confluence with natural wetlands. It is suggested that marked changes in sediment redox potential at these confluence sites provide ideal conditions for nitrification of sorbed ammonium which is subsequently flushed from the system in ‘flood events’.

The distribution and type of nutrient processing observed in this wetland are attributable to its configuration. The implication of these results to the sustainability of nutrient renovation in wetland treatment systems is discussed.
BOD BIOSENSOR FOR SECONDARY EFFLUENT FROM WASTEWATER TREATMENT PLANTS
Authors: Tanaka H. , Nakamura E. , Minamiyama Y. , Toyoda T.
Published: May 2018

A BOD biosensor which uses irrunobilized yeasts for its receptor and a DO probe for its transducer has made it possible to measure BOD in wastewater in a short time and without any special analytical technique. Since being standardized as Japan Industrialized Standard (JIS) K 3602 in 1990. the BOD sensor has entered into a commercial stage. It has been reported that the BOD sensor is applicable to specific wastewater generated by the food industry, but it is unclear whether the BOD sensor is applicable to domestic wastewater, in particular. to secondary effluent from wastewater treatment plants. This paper discusses the applicability of the existing BOD sensor to domestic wastewater and the necessity of improving the existing BOD sensor. Based on the experimental evaluation of the actual samples in this paper, it was found that the BOD sensor requires modifications when it is applied to less biodegradable samples such as secondary effluents from wastewater treatment plants or river waters. Thus, several modifications were conducted. As a result, selections of microorganisms for the receptor and of BOD standard solutions for calibration resulted in improvement of applicability of the BOD sensor to less biodegradable samples. Using the renovated BOD sensor, satisfactory coincidence was observed between manually analyzed BOD5 and sensored BOD for secondary effluent and river water.
PRELIMINARY STUDY OF SURFACE TREATMENTS FOR PLATINUM ELECTRODES DESIGNED FOR OXIDATION-REDUCTION POTENTIAL DETERMINATIONS IN ACTIVATED SLUDGE
Authors: Heduit Alain , Martin Bénédicte , Thevenot Daniel R.
Published: May 2018

Platinum electrodes with six different surface treatments (polishing, platinization, polypyrrole, polyurethane, cellulose acetate and Nation) were tested for equilibrium exchange current densities and zero-current potential in treated water and activated sludge. Preliminary results show that platinization and polypyrrole treatment increase electron transfer rates, but polypyrrole film breaks up rapidly in activated sludge; polyurethane and cellulose acetate layers did not prevent fouling (and impaired perfonnance) in activated sludge, but Nation seemed more promising.
Approaches for sediment associated pollutant monitoring in the River Danube
Authors: Literathy Peter , Laszlo Ferenc , Csanyi Bela
Published: May 2018

Inorganic and organic pollutants (nutrients and toxic pollutants) are liable to accumulate in suspended and bottom sediments. The major transport of these pollutants takes place in the suspended load. Sedimentation and resuspension are in dynamic equilibrium along the river influenced mainly by physical processes.

International and national surveys on the Danube sediment concluded that the Danube reach between Vienna and Budapest is one of the most polluted ones in addition to the Irongate reservoir and the downstream reach. The main polluting compounds are petroleum hydrocarbons, including PAHs, and heavy metals. Reservoirs are the major traps of sediment-bound pollutants where pollutant “time-bombs” may be developed.

Pollutant monitoring of the bottom sediment requires careful selection of the representative sampling sites where the sediment contains at least 10 percent clay and silt which is enriched in pollutants. Mobilization of the sediment-bound pollutants will result in biological uptake by the benthic organisms. The macrozoobenthons monitoring provides valuable evidence for chronic biological stress associated with contaminated sites. Benthic biodiversity decreased along the studied Danube reach downstream of recognized hot spots such as major cities (Vienna, Bratislava, Budapest) and polluted tributaries (the Vah river, etc.). Harmonization between chemical measurements and biological observations in the sediment could eventually lead to an effective Danube pollution monitoring system.
Nitrogen removal efficiency and capacity in biofilms with biologically hydrolysed sludge as a carbon source
Authors: Æsøy A. , Ødegaard H.
Published: May 2018

The possibility of using biologically hydrolysed sludge as carbon source for the denitrification process in biofilms has been investigated. The goal of the biological sludge hydrolysis process is a high degree of solubilization of the organic matter in the sludge. The soluble organic matter is best dominated by readily biodegradable compounds. The biological hydrolysis of chemical/biological raw sludge resulted in a degree of solubilization (yield) of 11%, where about 84% of the soluble organic matter originated from protein materials. The solubilized nitrogen was found as ammonium-nitrogen. The sludge was composed of 70% chemical sludge and 30% biological sludge. On average 66% of the soluble organic matter was volatile fatty acids. Only the volatile fatty acids were utilized as carbon source in the denitrifying biofilm. The biofilms were around 1000 μm thick, and the denitrification rate with respect to the concentration of volatile fatty acids could be described by a hyperbolic Monod-type function. The effect of the diffusion resistance in the biofilms was reflected by the use of an artificial “half-saturation” constant, K*CODVFA = 3 mg CODVFA/l. The maximum denitrification rate was found to be rmaxNO3-N = 0.57 g NO3-N/g VS· d. The stoichiometric consumption ratio between soluble organic matter and nitrate was 4.5 g CODVFA/g NO3-N on average. A simulation example on the nitrogen removal capacity when the carbon source is provided by sludge hydrolysis is given.
Acetylene inhibition for measuring denitrification rates in activated sludge
Authors: Hallin Sara , Pell Mikael
Published: May 2018

A method of determining the actual and potential denitrification rates in activated sludge samples by measuring accumulation of nitrous oxide after inhibition by acetylene was adapted and applied.Rates obtained with the acetylene inhibition technique were compared with those calculated through mass balances of total nitrogen from process data as well as those measured as nitrate utilisation.The acetylene inhibition technique was a reliable method for determination of denitrifying activity.The influence of acetate, ethanol, methanol and nitrate additions was examined.Acetate gave the best response upon denitrification followed by ethanol and methanol.The bacteria in the activated sludge could not denitrify at full capacity due to limitations in the supply of electron donors.The actual rates measured with the acetylene inhibition technique corresponded to the rates obtained from process data.The potential rates, determined with additions of acetate and nitrate in excess (240 mg l−1 and 28 mg N l−1), were 3–7 times higher than the actual rates and the rates calculated from process data.There is, thus, a potential for a more rapid denitrification rate.The potential denitrification rate measured with the acetylene inhibition technique was equivalent to the nitrate utilisation rate.
Some physiological characteristics of a phosphate removing bacterium isolated from anaerobic/aerobic activated sludge
Authors: Ubukata Y.
Published: May 2018

We succeeded in the isolation of a phosphate removing bacterium which takes up casamino acids while releasing phosphate anaerobically and takes up phosphate aerobically. The function of excess phosphate accumulation was induced by alternating anaerobic incubation with organic substrates and aerobic incubation without organic substrates. The following physiological characteristics were shown by further investigation. (1) The presence of casamino acids in aerobic incubation did not inhibit greatly the induction of excess phosphate accumulation, but suppressed the uptake of phosphate because the cells take up casamino acids using the energy produced by the hydrolysis of polyphosphate even in aerobic conditions. (2) Within one hour in anaerobic conditions the cells had taken up casamino acids to as much as 25% of the cell dry weight and the rate of ammonium excretion was small against that in oxidative metabolism. In anaerobic conditions the synthesis of DNA did not occur and the ratio of excreted phosphorus to removed glutamic acid was about 0.5 M/M. This value is very small against that required for the polymerization of the substrate. Therefore a large amount of low molecular weight material, such as amino acids, seems to be accumulated in the cells.
Phosphate release of sludges from enhanced biological p-removal during digestion
Authors: Jardin Norbert , Pöpel H. Johannes
Published: May 2018

During the start-up phase of an enhanced biological phosphorus removal (EBPR) plant, the amount of eliminated phosphorus during wastewater treatment and the subsequent release during anaerobic sludge digestion was investigated. Different approaches were used to determine the mechanisms of enhanced phosphorus removal. From a comparison of the EBPR plant with a control, a strong correlation between the potassium, the magnesium and the phosphorus content of the sludge and the results gained from phosphorus fractionations we conclude that the major part of the eliminated phosphorus was stored in form of polyphosphate. During digestion of excess and a mixture of excess and primary sludge a complete release of the stored polyphosphate was found. The release of phosphorus was accompanied by a release of potassium and magnesium ions, from which only potassium remains in soluble form. Therefore, the soluble potassium concentration seems to be a good measure for the amount of phosphate released. Only a part of the released phosphate remains in soluble form. When digesting excess and mixed sludge this accounts for approximately 40% of the total phosphorus brought into the digester. The difference between the measured soluble phosphate concentration and the amount of released phosphorus was fixed, mainly due to chemical precipitation. It was found that a fixation in the form of magnesium ammonium phosphate (struvite) was likely to occur under the conditions of anaerobic sludge digestion. The amount of phosphate precipitation as struvite could be estimated using theoretical calculations at approximately 20% of the total phosphorus in the digester. Calcium dosing experiments show that calcium-phosphate precipitation plays only a minor role in phosphate fixation.
Efficient biological nutrient removal in high strength wastewater using combined anaerobic–sequencing batch reactor treatment
Authors: Subramaniam K. , Greenfield P. F. , Ho K. M. , Johns M. R. , Keller J.
Published: May 2018

The abattoir (slaughter house) wastewater used in this study is high both in the nutrient and carbon concentrations. Two laboratory scale Sequencing Batch Reactors (SBR) were fed with wastewater from two different stages of anaerobic pretreatment using waste stabilization ponds. They were operated on a 6 hour cycle at room temperature. The SBR using stage 1 effluent shows very good biological nutrient removal (BNR). The soluble phosphorus concentration was reduced from 30–50 mg/l in the feed to < 0.5 mg/l in the effluent. The removal of COD, TKN, TP and SS were greater than 95%, 92%, 90%, and 94%, respectively. A nonbulking sludge having a Sludge Volume Index (SVI) of less than 100 ml/g was obtained. The results show that the combination of anaerobic pond – SBR treatment is effective in treating high strength abattoir wastewater for carbon and nutrient removal.
Performance and model calibration of R-D-N processes in pilot plant
Authors: de la Sota A. , Larrea L. , Novak L. , Grau P. , Henze M.
Published: May 2018

This paper deals with the first part of an experimental programme in a pilot plant configured for advanced biological nutrient removal processes treating domestic wastewater of Bilbao. The IAWPRC Model No. 1 was calibrated in order to optimize the design of the full-scale plant. In this first phase the R-D-N process, incorporating an anoxic selector, was tested for eight months at three temperatures of approximately 20°C, 15°C and 11°C. Under quasi-steady state conditions the ammonia effluent varied from 1 to 5 mg N/l. A partial inhibition of nitrification in some periods was detected. This was clearly shown by regular maximum AUR batch tests and by the model calibration. The influent COD/TKN ratio was rather low (8-9) and the effluent nitrate concentrations varied from 10 to 12 mg N/l. The DSVI increased from 50 to 115 ml/g as the temperature decreased from 20°C to 11°C. An appropriate balance between floc-forming and filamentous microorganisms was maintained as a consequence of the combined configuration of the anoxic selector and the regeneration zone.
Bacterial Populations in a Biological Nutrient Removal Plant
Authors: Kavanaugh Rathi G. , Randall Clifford W.
Published: May 2018

Research in the area of bacteriological studies of biogical nutrient removal (BNR) systems has emphasized the role of Acinetobacter spp. in phosphorus removal. The present study was undertaken to enumerate, isolate and identify bacterial populations from a BNR/activated sludge system. The most probable numbers (MPN) of volatile fatty acid (VFA) utilizers and denitrifiers were determined. Bacterial populations were isolated from the MPN tubes. Pure cultures of Gram-negative bacteria were identified. Acinetobacter spp. were not the dominant group of bacteria recovered from the system. Bacteria belonging to Aeromonas/Vibrio, coliforms, Pseudomonas and Acinetobacter groups were recovered both on VFA media and denitrification medium, indicating an overlap in their role. In the system studied, both phosphorus and nitrogen removal was carried out by more than one group of bacteria.

1Corresponding Address: The U.S. EPA, Environmental Research Laboratory, 1 Sabine Island Drive, Gulf Breeze, FL 32561. USA
Oxidation of sulfur-containing s-triazines during groundwater hypochlorination
Authors: Lopez A. , Mascolo G. , Tiravanti G. , Santori M. , Passino R.
Published: May 2018

With the aim to identify the reaction by-products, the oxidation of four sulfur-containing s-triazines (prometryne, terbutryne, ametryne and desmetryne) by sodium hypochlorite (NaClO) has been investigated using oxidant and herbicides initial concentrations respectively of 11 ppm and 3 ppm. Furthermore, to study the effect of reagent concentration on the oxidation rate, only for prometryne, the reaction has been carried out at two more oxidant and herbicide initial concentrations (ppm): 3 and 0.003, 0.011 and 0.003. Oxidation reactions were monitored by high performance liquid chromatography (HPLC), while the identification of by-products was at first carried out by HPLC-mass spectrometry (HPLC-MS) and then confirmed by accurate mass measurements. The results indicate that all the investigated triazines react in the same way. In the experimental conditions (T = 20°C, pH = 8, reaction time = 48 h) the reaction gives rise to three identified oxidation by-products: the sulfoxide, the sulfone and the sulfone's hydrolysis product. As expected, the lower the reagent's concentration the slower the oxidation rate. Based on the obtained results, a general pathway for the oxidation of sulfur-containing s-triazines is proposed.
Metabolisms of Different Bacterial Populations in Enhanced Biological Phosphate Removal Processes
Authors: Mino T. , Satoh H. , Matsuo T.
Published: May 2018

The characteristics of two major bacterial populations, phosphate accumulating organisms and “G bacterium”, in the anaerobic–aerobic biological phosphate removal process are discussed with an emphasis on their metabolic functions. It is theoretically indicated that the system of the oxidation-reduction balance in the cell enables the anaerobic uptake of organic substrates and that this system is essential for the microorganisms to survive in anaerobic–aerobic processes.
Bacteria and Protozoa Population Dynamics in Biological Phosphate Removal Systems
Authors: Čech J. S. , Hartman P. , Macek M.
Published: May 2018

Population dynamics of polyphosphate-accumulating bacteria (PP bacteria) was studied in a laboratory sequencing batch reactor simulating anaerobic-oxic sludge system. The competition between PP bacteria and another microorganism (“G bacteria”) for anaerobic-oxic utilization of acetate as the sole source of organic carbon was observed. The competition was found to be seriously influenced by protozoan and metazoan grazing: Predation-resistant “G bacteria” forming large compact flocs outcompeted PP bacteria. Several breakdowns of enhanced biological phosphorus removal were observed. The first one was related to the development of an euglenid flagellate Entosiphon sulcatus and attached ciliates Vorticella microstoma and V. campanula. The second system collapse was connected with a rapid proliferation of rotifers. An alternative-prey predation was thought to be a mechanism of PP bacteria elimination.
Central processing of pig manure in the Netherlands
Authors: Rulkens W. H. , ten Have P. J. W.
Published: May 2018

One of the possibilities to abate the environmental problems caused by pig manure surpluses is separation of the manure into clean water and an organo-mineral fertilizer. An efficient way to realise such a separation is by central processing in large plants. The process in such a plant comprises a large number of logically arranged basic treatment steps. In the Netherlands, practical application of large-scale central processing of pig manure has just been started. Two of these systems are discussed, the Promest system and the Memon system. Based on several studies the investment of a central treatment plant, with a processing capacity of 500,000 tonnes of raw pig manure annually, is estimated at approximately Dfl. 100,000,000. Gross operating costs are estimated at about Dfl. 60 per tonne of raw pig manure. The value of the fertilizer produced per tonne of raw pig manure is estimated at an amount between Dfl. 20 and Dfl. 35. Foreign markets have to be opened for utilisation of this fertilizer in agriculture. To improve such central processing systems, current research focuses on the improvement of existing systems, development of new systems, and production of more valuable products such as lysine.
Aerated Anoxic Biological NdeN Process
Authors: Albertson O. E. , Stensel H. D.
Published: May 2018

The conventional practice for an anoxic denitrification basin has been to minimize oxygen input on the basis that it is detrimental to the process. For existing secondary treatment systems, allotting 25-35% of the aeration volume for an unaerated anoxic zone will significantly reduce plant capacity. Further, one group has held that bulking control is best achieved by eliminating all forms of oxygen from the initial contact or biological selector zones. The Phoenix 91st Avenue WWTP was designed with nitrate recycle to aerated selector zones and the anoxic zones were provided with a dense array of fine bubble diffusers. The prototype NdeN process was able to maintain the 1.31 m3/s secondary capacity with aerated anoxic zone receiving 20-25% of the total airflow. Net sludge yields were 30-50% higher than anticipated due to primary clarifier solids losses at higher flows which reduced SRTT to ≤ 5 days. At 5.0-5.5 day SRTT, effluent averaged 8.3 mg/L TN, 1.75 mg/L NH4N and 5.7 mg/L NO3N. Nitrobacter N oxidation rates were unexplainably lower than the Nitrosomonas N oxidation rates causing effluent NO2N.
Systematic Activated Sludge Bulking and Foam Control
Authors: Foot R. J. , Robinson M. S. , Forster C. F.
Published: May 2018

The value of models to explain growth responses of filamentous microbes in activated sludge is well recognised. A much better understanding of the conditions which promote both bulking and foam formation is now available, as are the methods by which sludge instability can be controlled. What is missing however, is the order by which corrective measures should be implemented. This is one which can be clearly understood by both the operators of the activated sludge process and its designers. This paper offers a logical route by which decisions can be made, presented in order of the effort and the cost required to effect a cure. Process options merely involve valve and aerator adjustments, whereas operational modifications need minor alterations to the plant. The most expensive alternatives are the engineered solutions involving the design and construction of additional reactors, such as selectors. A systematic rather than symptomatic approach to bulking and foaming, using firm data and decision pathways, is a pre-requisite for any modelling exercise or process simulation.
Enumeration of Toxic Compound Degrading Bacteria in a Multi-Species Activated Sludge Biomass
Authors: Silverstein J. , Hess T. F. , Al Mutaari N. , Brown R.
Published: May 2018

A most probable number (MPN) method has been described for the enumeration of bacteria responsible for 2,4-dinitrophenol (DNP) degradation in activated sludge cultures. Because of the encapsulation of cells within the activated sludge floc, the method of pretreatment may be critical for producing a homogeneous distribution of bacteria to insure accurate dilution and enumeration. In these experiments, pretreatments using mechanical shear and incubation of cultures in EDTA have been tested. The combination of mechanical shearing in a high speed blender and incubation in a 0.5% EDTA solution resulted in significantly higher MPN values for DNP-degrading organisms growing in activated sludge in sequencing batch reactors (SBRs) which had been supplemented with glucose. Shearing of flocs and the combination of shearing and EDTA treatment produced the identical MPN values in both pure and activated sludge cultures grown only in DNP.
Improvement and Control of the Microbial Activity of a Mixed Population for Degradation of Xenobiotic Compounds
Authors: Buitrón Germán , Capdeville Bernard , Horny Patrick
Published: May 2018

A computer-aided sequencing batch reactor, CA-SBR, was used in order to monitor, improve and control the microbial activity for xenobiotics degradation. The control parameter for the reactor operation was the carbon dioxide evolution rate. Activated sludge was acclimated to 4-chlorophenol, 4CP, and was used as inoculum for the reactor. A specific substrate degradation rate, qm, of 116 mg 4CP/gMLSS-h was obtained for the best conditions using the CA-SBR. Whereas, with a 24-hour SBR cycle policy, qm was 20 mg 4CP/g MLSS-h. The ability of acclimated micro-organisms to degrade 4CP decreased as a consequence of starvation periods. Inductive enzyme activity decreased by as much as 80 % after 6 hours of starvation. Furthermore, a loss of 60 % in cell viability was found after 20 hours of starvation.
Structure, Activity and Composition of Biofilms
Authors: Zhang Tian C. , Bishop Paul L.
Published: May 2018

The spatial distributions of properties of biofilms have been investigated by using three different kinds of biofilms as test materials. Biofilms, cultured by laboratory-scale rotating drum biofilm reactors with synthetic wastewater, were first cut into 10 to 20 µm thick slices using a microtome, and then apportioned into samples representing 3 or 4 layers. The biofilm properties of each layer were investigated by measuring the densities, phospholipid concentrations, and AR18 dye adsorption abilities. The bacterial population distributions and the metabolically active bacterial distributions were studied by plate count methods or a MPN method, and the tetrazolium dye (INT) reduction method, respectively. Based on statistic evaluations, the micro-slicing technique, the procedure for analyzing phospholipid concentrations of biofilms, and the AR18 dye adsorption tests were suitable to be used in biofilm studies. It was found that the densities of biofilms in the bottom layers were 4 to 7 times higher than those in the top layers. For thick biofilms (thickness > 500 µm), the INT active bacteria decreased from 82-89% in the top layers to 5-11% in the bottom layers. The porosities of thick biofilms changed from 83-92% in the top layers to 56-64% in the bottom layers. For thin biofilms (thickness < 500 µm), the porosities of biofilms changed from 72-75% in the top layers to 35-44% in the bottom layers. Highly spatial distributions of bacterial populations, mean pore radius, and specific surface areas were also observed. As a result of these spatial distributions, the ratio of effective diffusivity to diffusivity in the bulk solution also shows a decrease with depth of the biofilm. Assuming biofilm properties are of a uniform distribution may be an over-simplified assumption, valid only in specific cases.
An Inhibition Study of the Effect of Azo Dyes on Bioactivity of Biofilms
Authors: Fu Yun-Chang , Jiang Hongshen , Bishop Paul
Published: May 2018

An inhibition study showed that toxic compounds caused two responses when present at low concentration. One is stimulation of the biomass by simply serving as an energy source; this caused an increase in the total respiration rate. The other is inhibition of the reaction. AR14 was more toxic than AO7 for biofilm from reactors fed with a primary substrate. However, AO7 demonstrated inhibition for biofilm from reactors fed with AR14 and primary substrate, and AR14 could serve as a carbon source for the same film.
Biofilms in Sewer Systems – Characterization of the Bacterial Biocenosis and Its Metabolic Activity
Authors: Roth D. , Lemmer H.
Published: May 2018

Biofilms sampled from sewers discharging domestic and trade wastewater, respectively, were characterized by determining the population densities of different groups of heterotrophic bacteria as well as by measuring their metabolic activities. Population densities of heterotrophic saprophytes, of proteolytic, amylolytic, and lipolytic bacteria as well as of ammonifying, nitrate reducing and anaerobic bacteria were determined on solid media and by MPN-tests. Metabolic activity was assessed by measuring enzyme activity of esterase, L-alanine-aminopeptidase, phosphatase, as well as of α- and β-glucosidase. Both biofilms revealed high population densities of bacteria from several metabolic groups as well as high enzyme activities. Their heterotrophic activity is in the range of or even higher than that found in high load activated sludges. The high activity of the bacterial biocenosis proves its resistance against high concentrations of chromium and nickel.
Methanogenic granule development in full scale internal circulation reactors
Authors: Pereboom J. H. F. , Vereijken T. L. F. M.
Published: May 2018

Internal Circulation (IC) reactors can be operated at higher reactor volume loading rates than Upflow Anaerobic Sludge Blanket (UASB) reactors. This results in increased gas production rates and subsequently higher average shear rates in IC-reactors. Furthermore, the liquid upflow velocity is 8-20 times higher, still granules develop successfully in IC-reactors. To investigate the granule development in IC-reactors and elucidate the process limitations with respect to granule development and biomass retention, granule samples from three full scale IC-reactors are characterized. Characterization included size distribution, strength, settling velocity, density, ash content and methanogenic activity. Granules were compared with samples from UASB reactors treating similar types of wastewaters. A hydrodynamic model was developed to describe the liquid circulation in IC reactors. The average shear rate in IC reactors is approximately twice as high compared to UASB-reactors. The two stage design of the IC-reactor allows 3-6 times higher loading rate. The experimental results showed that IC-granules are larger than UASB-granules grown on similar wastewater, while the strength of IC-granules is lower as a result of the higher sludge loading rate. Although wash-out is slightly enhanced in IC-reactors, the conditions in the second stage are tranquil enough to ensure adequate biomass retention in IC-reactors. The development of characteristic IC-granules after seeding proceeds within a few months. Physical characteristics of granules are determined mainly by biological factors.
Performance and granule characteristics of UASB process treating wastewater with hydrolyzed proteins
Authors: Fang H. H. P. , Chui H. K. , Li Y. Y. , Chen T.
Published: May 2018

UASB process consistently removed 84% of COD in wastewater with hydrolyzed proteins for loading rates up to 32 g-COD/L/day, corresponding to a food-to-microorganisms ratio of 0.81 g-COD/g-VSS/day, at 37°C and a hydraulic retention time of 9 hours. Of all the COD in the wastewater, about 74% was converted to methane, 16% was unhydrolyzed proteins which remained refractory to degradation, and 10% converted to biomass. The average sludge yield was 0.079 g-VSS/g-COD. There was no noticeable foaming and sludge flotation. The maximum specific methane production rate in the reactor was 0.60 g-methane-COD/g-VSS/day, which was comparable to the specific methanogenic activity (SMA) of 0.59 g-methane-COD/g-VSS/day observed by the serum vial test using hydrolyzed proteins as substrate. The SMA using acetate as substrate was 0.89 g-methane-COD/g-VSS/day, higher than those (0.39–0.59 g-methane-COD/g-VSS/day) using formate, propionate and butyrate, individually, as substrate. The granules did not have a layered structure nor a predominant type of bacteria. Instead, it had a densely packed structure with interwined bacteria of diverse morphologies with scattered microcolonies of Methanothrix, Methanosarcina, and justapositioned syntrophic associations.
Sludge characterization and standardization methods: development, status, trends
Authors: Leschber Reimar
Published: May 2018

A short history of sludge characterization is given leading from sewage and sewage sludge treatment in former times to modern water and soil pollution control with resulting needs of sludge investigation and analysis. The progress in this field in the Federal Republic of Germany from the sixties till today is given as an example and the connections with the development in Europe with special regard to the concerted Action COST 68/681 of the Commission of the European Communities between 1972 and 1990 are described. Finally, the present situation is delineated which is determined by the work of the CEN Technical Committee 308 “Sludge characterization”, which was founded in May 1993.
Decreased sludge production strategy for domestic wastewater treatment
Authors: Canales Angel , Pareilleux Alain , Rols Jean Luc , Goma Ge´rard , Huyard Alain
Published: May 2018

With new EEC regulations, alternative treatment and disposal techniques of the excess sludge produced by Activated Sludge (AS) wastewater treatment plants have to be performed. In order to reduce the excess sludge produced, experiments have been carried out with a Membrane BioReactor (MBR) to study the maintenance and cryptic growth phenomena of Pseudomonas fluorescens culture taken as a model when grown on a limiting substrate complex medium similar to a synthetic urban wastewater. Experiments with various imposed wasting rates showed that viability and sludge production yield decreased when sludge age increased. Same variations were observed on the cell content ratio protein/polysaccharide by analysis of the cell lysis products released after discontinuous thermal treatment. Biomass growth on these cell lysis products was achieved to characterize cryptic growth and its impact on sludge production yield. Finally, a continuous sludge thermal treatment system was operating with MBR to amplify sludge breakage and consequently biomass growth on the lysis products. With the promising results obtained, this work gives a new outlook on the AS process and leads to the development of processes with control and reduction of sludge production.
Effect of centrifugation on the removal of extracellular polymers and physical properties of activated sludge
Authors: Sanin F. Dilek , Vesilind P. Aarne
Published: May 2018

Activated sludge is a flocculated suspension of living and dead microorganisms enmeshed together in a polymer matrix along with some organic and inorganic materials. Extracellular polymers, main components of which are the polysaccharides, proteins, and nucleic acids, act as a protective barrier to the living microbial community, and give the floc its integrity and rigidity. These polymers have been found to affect the dewatering and settling characteristics of activated sludge. Even though they were studied considerably in the past there is not a complete understanding of the relationship between the amount of polymer and changes in the physical properties of sludge. The purpose of this research is to observe the effects of centrifugal force on the extraction of the extracellular polymers from an activated sludge and to correlate the amount of polymer extracted to the subsequent physical properties of the sludge. Centrifugal forces of 2000, 5000, 8000, 11,000, 14,000, and 16,500 G were tested for their effects on the amount of extracellular polymer collected, as well as the final properties of sludge like viscosity, filterability, compactability and supernatant turbidity. Results were evaluated in comparison to those of an uncentrifuged control waste activated sludge. Removal of extracellular polymers seems to affect the viscosity of activated sludge. Filterability, as measured by the capillary suction time instrument, was affected by the extraction of polymers to a great degree. Results of the independent tests correlated well with each other and with the amount of polymers extracted. Results of this study have important implications on sludge pumping and dewatering.
Biodegradation of phenol and monochlorophenols by yeast Rhodotorula glutinis
Authors: Katayama-Hirayama Keiko , Tobita Shusaku , Hirayama Kimiaki
Published: May 2018

Biodegradation of phenol and monochlorophenols (CPs) by a yeast strain of Rhodotorula glutinis was examined. The strain completely degraded 5 mM of phenol and utilized phenol as a sole carbon source. The strain may degrade phenol by the “ortho” type of ring fission because muconolactone was observed in the cultured broth. 3-Chlorophenol (3-CP) and 4-chlorophenol (4-CP) were well degraded and stoichiometric release of chloride ion was observed, but degradation of 2-chlorophenol was low with a small quantity of chloride ions. Biodegradability of 3-CP and 4-CP was increased by the addition of phenol or CPs to the medium at the cell cultivation. Since 4-chlorocatechol and maleylacetic acid were determined as metabolites of 3-CP and 4-CP by GC/MS analysis, dechlorination may take place between the formation of 4-chlorocatechol and maleylacetic acid.
The effect of cosubstrates on phenol degradation kinetics
Authors: Magbanua Benjamin S. , Hoover Pamela A. , Campbell Patrick J. , Bowers Alan R.
Published: May 2018

Kinetic parameters (based on the Monod model) for phenol degradation were measured under single and multiple substrate conditions using batch or fed batch reactor (FBR) techniques. The batch reactor was equivalent to the FBR for qm estimation, but gave higher Ks estimates (5.14 ± 7.34, batch vs. 0.63 ± 0.86, mg/l as phenol). qm was significantly higher with single substrate than multiple substrate feed (120.4 ± 53.9 for phenol only vs. 59.5 ± 23.7 for multiple substrates, mg/g-h); an active biomass correction factor based on the fraction of phenol organic carbon in the stock feed reversed this inequality, but the difference (120.4 ± 53.9 for phenol only vs. 202.5 ± 80.7, corrected, for multiple substrates, mg/g-h) remained significant. Ks was independent of feed composition (0.63 ± 0.86 mg/l as phenol). Paired FBR tests were used to minimize changes in sludge condition, and agreed with unpaired tests. Probability distribution analysis showed that qm and Ks data followed log-normal distributions (r2 > 0.90), and is useful for selecting values for design.
Dephenolization from aqueous solution by treatment with peroxidase and a coagulant
Authors: Tatsumi K. , Ichikawa H. , Wada S.
Published: May 2018

To develop a new enzymatic method for removal of phenols from wastewater, the reaction of phenols with horseradish peroxidase was investigated in the presence or absence of a coagulant. Phenols are effectively removed by treatment with peroxidase and a cationic polymer coagulant. The coagulant precipitated enzymatic products of phenol, and reduced the inactivation of peroxidase caused by reaction of products from phenol with the enzyme. This stabilization of peroxidase lessened the amount of enzyme required for phenol removal. Reaction of the coagulant with products from phenol resulted in a large precipitate and only simple filtration was required for separation.
Pretreatment of Tannery Wastewaters
Authors: Talinli I.
Published: May 2018

High Pollution treatment necessities were aimed at on COD basis (8000 mg/l). Case studies include the treatability study, conceptual design and monitoring of the actual treatment plant performance. To reach a pretreatment standard value of 800 mg/l COD, chemical and biological treatment were necessary including chromium removal and sulfide oxidation. Results of the treatability tests indicate that chemical coagulation is efficient and reliable in terms of COD removal. However, materials used in the process such as sulfuric acid and sodium sulfate and adding of manganese sulfate as catalyst for sulfide oxidation increase the sulfate concentrations in the influent of the biological treatment In this case, lime was used for coagulation both to reach sulfate standard and to protect the biological system.
Evaluating an iron-coated sand for removing copper from water
Authors: Lai C. H. , Lo S. L. , Lin C. F.
Published: May 2018

In drinking water treatment systems, the conventional process (coagulation, sedimentation and filtration units) cannot remove trace metals efficiently. Iron oxide is an excellent, regenerable adsorbent, and often controls free metals through adsorption. The utilization of heating process for coating iron oxide on sand surface allowed the media to be used in a packed column. The adsorbent media were investigated for removing copper ions from water using both batch and column experimental methods. A one-dimensional convective-dispersive transport model with a combination of second-order kinetic adsorption equation was adopted for predicting copper retention in a 80 cm depth filter bed. The concentration of copper ions in influent ranged from 0.64 to 3.2 mg/l. The experimental results indicated that the copper could be removed completely until the breakpoint. Once breakthrough occurred, the regeneration of the media could be achieved by soaking with acid solution (pH = 3.0). The simulation results of the transport-adsorption equation fit experimental data quite well. Consequently, the coated sand can be applied for the conventional rapid filtration process to remove copper ions from water.
Effect of pore size distribution of ultrafiltration membranes on virus rejection in crossflow conditions
Authors: Urase Taro , Yamamoto Kazuo , Ohgaki Shinichiro
Published: May 2018

The ultrafiltration process is successfully used in wastewater reuse systems. It will also be used widely in drinking water supplies. In wastewater reuse and for safer drinking water supplies the potential for virus rejection by membrane processes is advantageous. Rejection of viruses was examined experimentally by using coliphage Qβ as a tracer. Several types of ultrafiltration membranes with molecular weight cutoff size of 20,000-40,000 were tested. All of these membranes leaked phages to some extent, contrary to the expectation from nominal cutoff size. Penetration of virus through ultrafiltration membranes was theoretically examined by taking pore size distribution of the membranes into account. Modified pore theory and a log-normal pore size distribution model gave an unsatisfactory explanation of the results. The presence of abnormally large pores which are not included in the main distribution was indicated.
Treatment and reuse of water for prawn cultivation
Authors: Chin Kee Kean , Ong Say Leong
Published: May 2018

An experimental prawn pond of 600 sq m surface area and 2 m depth was used for the cultivation of tiger prawn. Thirty-thousand 14-day PL flies were stocked. Water treatment systems consisting of primary sedimentation, aerated biofilter and inclined plate final sedimentation were installed for treatment and recycling of the pond water. With complete recycling and reuse of the pond water and occasional replenishing with seawater to make up for losses due to evaporation, water quality was maintained at an acceptable level. Survival rate of the prawn was above 80 %. Prawn yield was estimated to be around 7.6 tonnes/hectare-cycle or 22.8 tonnes/hectare-year.
National and regional surface water quality assessment in the Republic of South Africa
Authors: van Vliet H. R. , Swart S. J. , Roux D. J.
Published: May 2018

Concern over the deteriorating quality of South African surface water resources in the past several decades has resulted in a number of fundamental changes in the approach to national water quality management, the most significant being a shift from a point-source control approach to a more complex and information-intensive receiving-water-quality based strategy. These changes highlighted the urgent need for a new focus on the development of a balanced and integrated strategy for the national and regional assessment of water quality and aquatic ecosystem health. An overview of the current developments, direction and strategies for water quality assessment of the Department of Water Affairs and Forestry, is presented.