bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Nitrate on the Bacterial Flora of Activated Sludge under Anoxic Condition
Authors: Takeuchi Jun-ichi
Published: May 2018

A two-year survey of bacterial populations in activated sludge was carried out in a municipal sewage treatment plant receiving industrial wastewater having a high nitrate content. Phosphorus removal was not improved with a modified operation with a dissolved oxygen (DO)-deficient selector. In these circumstances, the anoxic selector in the aeration tanks acted as a site for denitrification not as a site for phosphate incorporation. The ecological interactions between the different bacterial species are thought to occur in the anoxic zone. Possible competition between the Pseudomonas/Alcaligenes group and the Acinetobacter/Moraxella group was suggested under laboratory conditions. Commensalism between the Enterobacter/Aeromonas group and the Acinetobacter/Moraxella group was observed by using a Nuclepore membrane-dialysis culture technique.
Bulking Sludge Control–Progress, Practice and Problems
Authors: Albertson Orris E.
Published: May 2018

Since bulking sludges are the primary cause of failure of activated sludge systems, the first obligation of the designer is to minimize the possibility of such an occurrence. This paper traces the evolution of bulking control concepts from the earliest date when batch and semi-continuous selectors were employed, to more recent experiences with anaerobic, anoxic, oxic and high F/M biological selectors. This paper also summarizes recent results obtained from 12 USA facilities employing various selectors. Preliminary conclusions support high to low F/M gradient as a dominant selector factor. Whether the system is aerated or not, the available oxygen in the initial contact zones (ICZs) should be substantially less than the oxygen demand in the zone to ensure that anaerobic functions occur within the cell mass. In addition, F/M gradients should be provided in each environment.
Changes in Microfauna at the Time of Occurrence and Disappearance of Filamentous Bulking
Authors: Terashi M. , Hamada S.
Published: May 2018

In the activated sludge process, the cause of filamentous bulking is often the filamentous bacteria Type 021N. At the Kitaminato sewage treatment plant, it was found that when the DO in the aeration tank decreased, filamentous bulking occurred. If the low DO condition is allowed to continue, anaerobic degraded organic matter is produced which creates a favorable condition for the multiplication of Type 021N. Entosiphon sp. is reported to show resistance to low DO; however, sometimes before filamentous bulking occurs, Entosiphon sp. itself multiples. Also if Entosiphon sp. increases and Cinetochilummargaritaceum, of the Ciliophora, multiples, then bulking by Type 021N has been seen not to occur. Cinetochilummargaritaceum has low resistance to hydrogen sulfide; therefore, hydrogen sulfide must not be present in the aeration tank and this means that bulking by Type 021N can not become serious. However, if filamentous bulking becomes serious, only increasing the DO level in the aeration tank will not cause the disappearance of the filamentous bulking. At this stage, if we allow 30% of the final effluent to flow back into the grit chamber, then Type 021N decreases. This is because Trithigmostomacucullulus, of the Ciliophora, increases to 3,000 number/ml, and it ingests Type 021N.
Dynamic Behavior Of Cr(III) in Activated Sludge
Authors: Imai Akio , Gloyna Earnest F.
Published: May 2018

The dynamic behavior of trivalent chromium (Cr(III)) in the activated sludge process receiving a square-wave input of Cr(III) was studied. A laboratory-scale activated sludge reactor was operated under steady-state conditions with respect to the process parameters at pH 7 and a sludge age of 5 days. The CRAS model, an quasi-equilibrium model developed by Imai (1988), was further extended to predict the behavior of Cr(III) as a function of operational time. A comparison between the experimental results and the model predictions revealed that the CRAS model was capable of predicting quantitatively the total chromium (TCr) and dissolved chromium (DCr) concentrations when the TCr concentration was on the increase (average relative error: 5.46% for DCr and 7.45% for TCr), but underestimated the TCr and overestimated the DCr as the TCr was on the decrease. Intracellularly transported Cr(III) seemed to be trapped inside the cell and not released back into solution. Iron(III) coprecipitation treatment indicated that about 35.6% of dissolved Cr(III) was organically complexed, and the CRAS model predicted 35.3%. This agreement supported the validity of the CRAS model for Cr(III) speciation in the solution phase.
Pilot and Full-Scale Experience in Anaerobic Treatment of Brewer's Yeast Processing Wastewater
Authors: Yoda M. , Imabayashi S. , Suzuki N.
Published: May 2018

The anaerobic expanded micro-carrier bed (MCB) process, which utilizes fine particles as expanded bed media to enhance granular sludge formation, was applied to the wastewater from a brewer's yeast processing plant. Based on the results3 of the pilot study, in which 97 to 99 % COD removals were maintained at 13 to 24 kgCOD/m3/day, a full-scale MCB plant with a total reactor volume of 985 m was constructed at Asahi's Koganei plant. Though not found in the pilot study, cobalt and nickel were found to be deficient in the wastewater and had to be supplemented during the start-up. However, a sufficient amount of granular sludge was cultivated BO that the reactor could accept the design loading, within three months of operation and achieve the average COD removal of 93.5% at 9.8 kgCOD/m3/day. Thus, it was clearly demonstrated in the full-scale installation that the MCB process could provide a reliable and predictable way to cultivate granular sludge necessary for efficient anaerobic treatment.
Microbial Corrosion of Concrete Sewer Pipes, H2S Production from Sediments and Determination of Corrosion Rate
Authors: Mori T. , Koga M. , Hikosaka Y. , Nonaka T. , Mishina F. , Sakai Y. , Koizumi J.
Published: May 2018

Little slime layer was found to exist on the walls of sewer pipes in an anaerobic condition when the sewage flow rate was higher than approximately 30 cm/sec. Therefore, H2S is not produced from slime layers but from sediments which existed in the main trunk or the pressure main. The H2S production rates ranged from 5.5 to 64 pg-H2S/g·solid h depending on the contents of organic compounds and the cell numbers of sulfate reducing bacteria (SRB). The limiting nutrients are assumed to be fatty acids by the spike test. The pipe wall in the area just above the sewage level corroded severely, but the crown of the pipe was not heavily corroded. The corrosion rate of the concrete sewer pipe at the Ohmuta treatment plant was 4.3 to 4.7 mm/y in the area just above the sewage level and 1.9 mm/y at the crown. The experiments using mortar as a test specimen showed that the corrosion rate usually ranged from 3.7 to 7.7 ram per year. But an extremely high corrosion rate was observed when the mortar was placed on the stage of the manhole of the pipe at Ohmuta Treatment Plant at temperatures of 25 to 30°C and H2S concentrations of 3 to 400 ppm. Corroded materials found on the surface of the pipe wall and mortar specimens were gypsum at low pH. Ettringite appeared within cracks of the mortar specimens at high pH.
Transient Responses of Wastewater Treatment and Biomass Development in a Methanogenic Fluidized Bed
Authors: Furumai Hiroaki , Kuba Takahiro , Imai Tsuyoshi , Kusuda Tetsuya
Published: May 2018

The objectives of this study are to develop a model which can express the characteristics of anaerobic treatment in a methanogenic fluidized bed reactor in non-steady states, and evaluate the usefulness of the model in which “active” biomass concentration is used as an index of bacteria concentration instead of traditional ones such as volatile suspended solids.

The treatment in the fluidized bed reactor started with biocoated synthetic zeolite as support material. The reactor was supplied with synthetic wastewater, a mixture of volatile fatty acids. An experiment on response was conducted according to changing stepwise the influent concentration. Batch experiments on activity were carried out under several steady state conditions, using a kind of volatile fatty acid as a substrate. Transient responses of water quality are investigated in relation to the growth of bacterial groups which decompose volatile fatty acids. Based on the results, a dynamic model is proposed, in which attached biomass is categorized into “active” biomass and inert organic matter. The transient response of substrate concentrations was clearly expressed by considering the growth of “active” biomass. It was impossible to explain the responses when VSS was regarded as the biomass concentration in the model.
Predictions of Diurnal Fluctuations in an Algal Bacterial Clay Wastewater Treatment System
Authors: Carberry J. B. , Brunner C. M.
Published: May 2018

Carberry's proposed algal bacterial clay treatment (ABCT) process would generate an algal biomass, useful as a food source. This study examined the diurnal fluctuations resulting from alternating light-dark periods and the magnitude of resulting O2, CO2, and pH oscillations. The magnitude of these oscillations was studied under controlled conditions, in order to determine acceptable limits of these fluctuations. The effects of progressive drifts for these parameter values under uncontrolled conditions was also studied in order to determine the rate of decreasing wastewater bacterial biodegradation efficiency and rate of deterioration of algal biomass viability. Experiments were conducted in which algae, bacteria, and substrate were combined at various concentrations in a biostat. Dissolved gas concentrations and pH were continuously recorded; biomass and substrate concentrations were determined over time by periodic sampling. A 12-hour light/dark cycle simulated the natural diurnal light variation. Based on results from these runs, two computer programs were developed to predict the changes in these parameters over a 24-hour period. One model, incorporating redox potential, appeared to be more sensitive to changes in the aqueous environment than the model based on COD. pH values of less that 5 were found to cause system failure due to a continuing decrease in algal concentration. No critical levels were found for either O2 or CO2 although the duration of time spent at a dissolved oxygen concentration of zero depended on initial algal concentration.
Effluent Pollution Control of Osaka North Port Dredged Soil Disposal Site (North Section-Site II & III)
Authors: Fukunaga Isao , Takamizawa Kazuhiro , Inoue Zensuke , Hasebe Toshihiko , Konae Miyoji , Hatano Kiyoshi
Published: May 2018

In Osaka City, the dredged soil has been diposed in a sea-based solid waste diposal site since 1975. The pond of the solid waste disposal site plays a role of sedimentation and purification for a very large bulk of wastewater with the dumped dredged soil. According to monthly observations of the pond, COD value rose in spring and autumn with suspended solids concentration and reached a maximum value of 50.6 mg/l. It was understood that the cause of COD rise was the exponential growth of phytoplankton and evident that removal of suspended solids such as phytoplankton was necessary to improve wastewater quality. Accordingly various wastewater treatment methods were examined. A pollution preventive membrane of 30 m width and 2 m depth was constructed in 1985. The maximum effective level of COD removal was 73 % and below 20 mg/l of COD was kept stable. From the point of both construction and maintenance costs, it was concluded the pollution preventive membrane method was the most economically effective wastewater treatment method.
Application of Coarse-Media Slow Sand Filtration in Aquaculture
Authors: Vigneswaran S. , Casiano V. L. , Polprasert C.
Published: May 2018

Laboratory experiments were carried out with pilot-scale experimental unit of Coarse Media Slow Sand Filter (CMSSF). A 2.7 m high filter column with a diameter of 0.56 m was operated with the filter media size of 1-2 mm and media depth of 1.0 m at filtration rates of 0.5 and 0.2 m3/m2h. This was connected to a circular concrete fish tank with a diameter of 1.16 m. The performance of CMSSF was compared with the 1.5 m × 1.0 m × 1.0 m Biological Filter (BF) operated at a filtration rate of 1.92 m3/m2h which was connected to 8 fish tanks. Experimental results showed that CMSSF has comparatively higher removal efficiency than BF for turbidity, total phosphorous, nitrogen and organic carbon. This study is an initial attempt to introduce CMSSF as a treatment unit in a recirculating aquaculture system which would be an economical solution to improve the water quality and production in aquaculture.
Pretreatment of Yeast Industry Wastewater in an Aerated Balancing Tank and Its Effect on the Municipal Treatment Plant Performance
Authors: Rusten B. , Sandberg K.
Published: May 2018

Organic shook loads from a yeast plant caused severe operational problems and unacceptable effluent qualities at the chemical/biological wastewater treatment plant serving the City of Oslo. to alleviate these problems a pretreatment concept for the yeast wastewater, based on an aerated balancing tank without following solids separation, was proposed. Laboratory tests with aeration of yeast wastewater at hydraulic residence times of 0.5 to 2.3 days showed 25 to 67% removal of soluble COD. Jar-tests indicated that with proper balancing, yeast wastewater aerated for at least 0.8 days would have a very limited influence on the pre-precipitation process at the municipal treatment plant. Based on this information, a full-scale aerated balancing tank was constructed. After pretreatment of the yeast wastewater was introduced, data from the municipal treatment plant show very low and stable effluent concentrations.
A Basic Study of the Efficiency of Spiral Flow Aeration
Authors: Kasakura Tadao , Tomita Yoshiho , Matsubara Kiwamu , Kubo Atsushi
Published: May 2018

The oxygen transfer efficiency of spiral flow aeration is affected by many factors, for example, the shape of aeration tank, the type of diffuser, the air flow rate and so on. The authors tried to determine the relationship between these factors and the efficiency of aeration. We found these factors were restricted by some independent variables, so we analyzed quantitatively the relationship between these variables and the efficiency of aeration based on data from the full scale experiments on spiral flow aeration using porous ceramic diffusers.

Regression equations show that the efficiency of the spiral flow aeration would be higher with a reduction of the air feed rate per tank volume and an increase of the total bubbling area of the diffusers. Other variables would not so greatly affect efficiency.
Analysis of Dewatering Characteristics of Lake and River Sediments
Authors: Tokunaga S.
Published: May 2018

In order to analyze the dewatering characteristics of sediments, settling and filtration tests were made on 25 types of lake and river sediments. Relationships among the indexes of the dewatering characteristics and effects of particle size and ignition loss on the dewatering characterstics are analyzed. A linear correlation exists between the initial settling rate and the compression volume. Particle size shows linear correlations to the initial settling rate, compression volume, and water content of filter cake, indicating that sediments of fine particles are difficult to be dewatered. An existence of organic pollutants strongly reduces the efficiency of gravity settling. By the addition of NaCl (3 w/v%), the initial settling rates and the specific resistances decrease down to 56% and 35% those of the NaCl–free sediments, respectively.
Wastewater Reuse Case Studies in the Middle East
Authors: Banks P. A.
Published: May 2018

Within the past few decades the accelerating demand on natural resources to provide water for urban use, and the associated cost of meeting that demand, has led to an increased interest in the reuse of waste waters for municipal, agricultural, industrial and groundwater recharge purposes.

This paper reports upon the use made of effluent in some of the oil economies of the Middle East. It discusses the features of reuse in this particular context, the processes used and the standards adopted. Tabulated information and operational results are compared and the effect of reuse upon the local environment is commented upon.
The Influence of Different Support Materials to Treatment Efficiency in Packed Bed Reactors
Authors: Roš M. , Vrtovšek J. , Dular M.
Published: May 2018

Biological treatment, especially nitrogen removal, in an upflow packed bed reactor with immobilised biomass was studied. As a support material granulated activated carbon (GAC), ceramic material (crush brick), brown coal and cut polyethylene tubes were used. The size of the support material was 4 to 6 millimetres. In laboratory scale studies pharmaceutical wastewater was treated. Volumetric loading was from 6.8 to 7.6 g/l/day. Results of investigations showed us that aerated packed bed reactors are usable for nitrogen removal because in the reactor originates aerobic and anoxic conditions. In anoxic cones the denitrification of nitrate, nitrite and ammonia ions takes place. The most effective systems for nitrogen removal were reactors filled with granulated activated carbon and with ceramic material. In the reactor with granulated activated carbon also colour from wastewater was degraded.
Flavor Tainting of Fish in the Upper Wisconsin River Caused by Alkyl- and Thiophenols
Authors: Lindsay R. C. , Heil T. P.
Published: May 2018

Compounds responsible for pronounced off-flavors in Walleye pike (Stizostedion vitreum) and other sportfish in the Upper Wisconsin River were identified by gas chromatography-mass spectrometry and sensory techniques. Alkylphenols (2-isopropyl-, 3-isopropyl, 4-isopropyl-, 2,4-diisopropyl-, 2,5-diisopropyl-, 2,6-diisopropyl-, 3,5-diisopropyl-, 5-methyl-2-isopropyl-, and 2-methyl-5-isopropyl-) and thiophenol were found to be the principal contributors to flavor tainting in fish which was most pronounced in the spring. Data indicated that thiophenol entered the river sporadically through discharges from paper mills. Analysis of fish, river sediments, insects, and woods supported a hypothesis that alkylphenols were indirectly derived from paper pulping activities, and that the food chain of fish was involved in the transport of alkylphenols from the environment to fish.
Physical Chemical Characterization of Five Earthy-Musty-Smelling Compounds
Authors: Pirbazari M. , Borow H. S. , Craig S. , Ravindran V. , McGuire M. J.
Published: May 2018

The occurrence of earthy-musty taste and odors in potable water supplies has been attributed to the presence of several organic compounds at ng/l, including geosmin, 2-methylisoborneol (MIB), 2-isobutyl-3-methoxy pyrazine, 2-isopropyl-3-methoxy pyrazine and 2,4,6-trichloroanisole. Microana-lytical techniques were employed for determining the physical/chemical properties of these compounds, hitherto uncharacterized. The properties determined were melting point, boiling point, refractive index, density, aqueous solubility, octanol/water partition coefficient and Henry's law constant. Since standard micromethods could not be employed for geosmin and MIB because of their scarcity, either these methods were refined or new procedures were developed. The experimental techniques were tested with reference compounds, the properties of which were reported in the literature. Statistical analysis reflected the accuracy and reproducibility of these procedures.
A Summary of Problem Areas in Aquatic Off-Flavour Research
Authors: Persson P.-E.
Published: May 2018

In spite of many important advances in the study of aquatic off-flavours, the absence of standardization in sensory methods as applied to water and fish is still an obstacle. The need for standardization is evident both in threshold techniques, flavour descriptors and scaling. The elucidation of biogenic off-flavours should be based on criteria which clearly define the character of evidence needed to establish causality.
Characterization of Polycyclic Aromatic Hydrocarbons (PAHs) by the Kinetics of Depuration in Bivalve Molluscs, Mercenaria mercenaria
Authors: Sato C. , Kim H. , Tanacredi J. T.
Published: May 2018

The objectives of this study were to examine depuration aspects of polycyclic aromatic hydrocarbons (PAHs) in a hard-shell clam Mercenaria mercenaria, and to characterize PAHs by the depuration kinetics. In this investigation, clams were exposed to artificial sea water containing a mixture of eight PAHs (i.e., naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[a]pyrene) for 48 hours. The clams were then transferred into clean (PAH-free) artificial seawater for release, and sampled at predetermined intervals. The target PAHs were extracted from the clam tissue and quantified by a gas chromatograph equipped with a capillary glass column and FID.

The results revealed single- and multi-component release mechanisms which were described by single- and multi-stage first-order kinetics, respectively. Benz[a]anthracene and benzo[a]pyrene exhibited the single-stage depuration, while naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and chrysene showed the two-stage depuration.
Waste Management Solutions at an Integrated Oil Refinery Based on Recycling of Water, Oil and Sludge
Authors: Galil N. , Rebhun M.
Published: May 2018

A research and development project was carried out at an oil refinery in Israel. The developed solutions were based on minimal disposal of wastewater and sludges outside the industrial zone and maximal recycling of water, oil and sludge compounds by the refinery and by adjacent industries. Following the research conclusions, the treatment facilities include: separate treatment of concentrated streams; API type oil-water separators; chemical flocculation - dissolved air flotation; the adopted solution for biotreatment was an aerated pond process followed by lime clarification and completed by the recirculated cooling system of the refinery which uses the renovated effluent as make up and continues the bioprocess. The blow down of the cooling system is treated by lime flocculation - clarification and discharged to the river. The refinery produces two categories of sludge: a) the lime sludge from water and wastewater treatment is gravity thickened and proposed to a neighbor cement factory as a very small part of the calcium carbonate raw material; b) the oily sludge from wastewater treatment and other sources is stored in concrete basins for oil and water separation. The remaining sludge fraction still contains 20 to 50 percent of oil and is proposed to the same cement factory to be added to the crude oil used as fuel. This solution provides excellent and safe incineration, in alkaline conditions, of all the organic and hazardous organic compounds.
Integrated Refinery Waste Management
Authors: Shieh Y.-S. , Sheehan W. J.
Published: May 2018

In response to the RCRA land ban regulations and TC rule promulgated by the U.S. Federal Environmental Protection Agency (EPA) in 1988-1990, an Integrated Refinery Waste Management (IRWM) program has been developed to provide cost-effective solutions to petroleum industry customers. The goal of IRWM is to provide technology based remediation treatment services to manage sludges and wastewaters generated from the oil refining processes, soils contaminated with petroleum distillates and groundwater contaminated with fuels.

Resource recovery, volume reduction and waste minimization are the primary choices to mitigate environmental problems. Oil recovery has been performed through phase separation (such as centrifugation and filtration) and heating of heavy oils. Volume reduction is achieved by dewatering systems such as centrifuges and filter presses, and low temperature thermal treatment. Waste minimization can be accomplished by bioremediation and resource recovery through a cement kiln. In-situ vapor extraction has been applied to remove volatile organic compounds from the vadose zone in contaminated sites. Stabilization has been effective for soils contaminated with heavy metals and nonvolatile substances.

For the listed hazardous wastes generated from the refining process, a combination of liquid/solids separation and thermal treatment has been successfully applied. The sludge from the on-site ponds or continuous operations is pumped to a surge tank before heating, phase separation and volume reduction by a two-stage centrifuge system. The first stage horizontal centrifuge has effectively separated the solids from the liquid phase containing oil and water. The oil in the liquid phase is separated from the water in the second stage vertical centrifuge and is recycled back to the refinery for re-use. The water will be sent back to the wastewater treatment system for further treatment. Pretreatment of the wastewater may be required.
Photocatalyzed Degradation of Adsorbed Nitrophenolic Compounds on Semiconductor Surfaces
Authors: Dieckmann M. S. , Gray K. A. , Kamat P. V.
Published: May 2018

Using semiconductor materials as photocatalysts to degrade hazardous organics has gained much attention in recent years. Colored compounds adsorbed onto semiconducting surfaces such as TiO2 or ZnO have been shown to be excited by visible light and to readily undergo degradation (Gopidas and Kamat, 1989). This same principle can be applied to the photo-induced destruction of colored pollutants such as nitrophenols. Since visible light can be used to initiate the photodegradation of colored pollutants, this type of semiconductor system offers a potentially efficient treatment process. The purpose of this research is to study the mechanisms involved in the photodegradation of nitrophenols by semiconductors.

Steady state diffuse reflectance photolysis studies indicate that TiO2, which exhibits semiconducting properties, gave the smallest half-life for photodegradation of 2,5-dinitrophenol. The metal oxides which acted only as support materials produced little photodegradation. Various nitrophenols are compared to study the effect of substituent nitro groups on rate of reaction. For example, 4-nitrophenol degradation has a half-life of 10 minutes while the half-life of 3-nitrophenol is 70 minutes. Also, an increase in the number of nitro groups decreases the rate of reaction. The half-life of mononitrophenols is on the order of an hour and dinitrophenols on the order of two hours while trinitrophenol still does not degrade to its half-life even after 8 hours of irradiation. Flash photolysis experiments with 4-nitrophenol in ethanol indicate the presence of a 420 nm transient species. Experiments in aerated and deaerated conditions show that the transient is an oxidation product and that it is not a triplet. Pulse radiolysis studies indicate that the transient is most likely a hydroxyl adduct of the parent compound. The presence of ZnO quenched the 420 nm transient.
Test of the Activated Sludge Model's Capabilities as a Prognostic Tool on a Pilot Scale Wastewater Treatment Plant
Authors: Pedersen Jan , Sinkjær Ole
Published: May 2018

A newly developed simulation programme, based on the Activated Sludge Model No. 1, was used to investigate the model's abilities to predict variations in a Bio-Denipho pilot plant. The model was tested under both normal conditions and in connection with an inhibition incident on the pilot plant with positive results.
Evaluation of Sludge Properties at an Activated Sludge Plant
Authors: Eriksson Leif , Steen Inga , Tendaj Marta
Published: May 2018

Composition of pre-settled water, sludge properties in two different lines of an activated sludge plant, and suspended solids (SS) content in outgoing water were followed three times a week during one year. Sludge characteristics were: settling properties, residual turbidity, floc strength, filtration resistance, amount of extracellular polymers, microscope appearance and total length of filamentous organisms.

The outgoing SS could be related to residual turbidity and sludge volume. These factors depended on the floc structure and the filament length. These were determined by sludge load or sludge age, water composition and the hydrodynamic history of the sludge. On basis of these and earlier findings a general model for properties of flocs built by floc-forming organisms in activated sludge is proposed.
Wastewater Treatment Process Theory and Practice: The Emerging Convergence
Authors: Parker D. S. , Merrill M. S. , Tetreault M. J.
Published: May 2018

The state of development of process modeling is assessed from the practitioner's point of view. The history of model development and application within a consulting firm is described. The utility of currently available models is portrayed for the commonly used biological treatment processes. The perspective given is one of assessing model usefulness in its most practical context, that of its utility in a design practice. Areas are identified where additional research and model development are needed.
Acidogenesis in Relation to In-Reactor Granule Yield
Authors: Vanderhaegen B. , Ysebaert E. , Favere K. , Van Wambeke M. , Peeters T. , Pánic V. , Vandenlangenbergh V. , Verstraete W.
Published: May 2018

A systematic study of in-reactor granule yield data was set up in the laboratory. Methanogenic granular sludge growth in fed batch shake flasks for different substrates appeared to decrease with the energy content of the substrate and required the presence of a mixing force. In UASB reactors, granular cell yields were found to be quite variable suggesting the involvement of complex microbiological interactions. The factor foremost in influencing the build-up in the reactor of granular sludge was the presence of high-energy carbohydrates; pre-acidified influents affected in-reactor granular sludge yield very negatively. The influence of sulphate reduction and sulphide concentrations was found not to be of primary importance. The ionic strength of the medium also had no strong influence. Granule formation proceeded somewhat better at low than at nigh strength buffer capacity. High levels of protein, however, reduced the in-reactor granular sludge build-up strongly. Measurement of the acid production by granular and fluffy sludges revealed that the former rapidly produce volatile acids, particularly propionate, while the latter do not. Measurement of the pH in the granule indicated that the outside layer of the granule is rich in acidogens. Calculations of proton and hydrogen fluxes in the granule support the concept that acidogens, able to ferment high energy carbohydrates efficiently to cells and exo-cellular binding materials, might be of primary importance for in-reactor granular growth.
Biochemical Inhibition of Sulfate Reduction in Batch and Continuous Anaerobic Digesters
Authors: Clancy P. B. , Venkataraman N. , Lynd L. R.
Published: May 2018

Two classes of biochemical inhibitors of sulfate reduction were tested in batch and continuous anaerobic digesters. At high phosphate concentrations, molybdate was an effective and selective inhibitor of sulfate reduction in fed-batch systems, although non-specific effects were observed at lower phosphate concentrations. Transition metal divalent cations were effective and selective inhibitors of sulfate reduction at all conditions tested in fed-batch digesters. In continuous digesters, molybdate inhibited sulfate reduction but also resulted in non-specific inhibition independent of phosphate concentration; transition metals proved to be ineffective in curbing sulfate reduction. Experiments were conducted to explain the non-success of inhibitors in continuous digesters.
Kinetic Studies on a UASB Reactor Subjected to Increasing COD Concentration
Authors: Paula D. R. , Foresti E.
Published: May 2018

This paper shows the response of a UASB reactor subjected to increasing influent COD concentrations.

The study was carried out using a 10.5 1 UASB reactor continuously operated during ten months, and fed with synthetic wastes prepared daily using glucose, ammonium acetate, methanol and nutrient solution. The. flow rate of 16 l.d−1 was held constant throughout the experiment, corresponding to a hydraulic retention time (θ) of 15.6 h. Four intermediate sampling ports besides the influent and effluent ones allowed a study of the reactor behaviour along its vertical profile.

For average values of the initial COD concentrations ranging from 1780 to 9700 mg.l−1, corresponding to volumetric loading rates (BV) of 2.7 to 14.8 kg COD.m−3. d−1, COD removal efficiencies varying from 98 to 80% were achieved.

It could be concluded that the step-increase of the influent COD affected the reactor performance in two different ways. First, the reactor could assimilate the shock loads due to the step-increase of the influent COD and BV beyond the transient periods following changes in the operation parameters. Second, the overall efficiency decreased gradually with the step-increase of the initial COD and BV.

Kinetic studies indicate that the overall kinetic parameters are probably affected by the step-increase of influent COD concentrations.
Anaerobic Treatment of Synthetic Sulfate-Containing Wastewater under Thermophilic Conditions
Authors: Visser A. , Gao Y. , Lettinga G.
Published: May 2018

The anaerobic treatment of a sulfate-containing waste water using a UASB reactor was studied at 55 °C. As substrate, acetate and a mixture of acetate, propionate and butyrate were used. With acetate as substrate it was shown that sulfate reducers are capable of using acetate as substrate at 55 °C, and that, under the conditions applied, they even outcompete acetoclastic methanogens. Batch-activity measurements with the sludge revealed temperature optima for acetate, propionate and butyrate degradation of ± 56-59, < 40 and 52-54 °C respectively.

After switching the substrate to a mixture of acetate, propionate and butyrate, the reactor pH dropped from 8.3-8.6 to 7.6-7.9 and the methane production recovered. After the establishment of a pseudo-steady state situation the part of COD removed by methane production and sulfate reduction was ± 60 and 40 %. Results of batch activity experiments showed that the methanogenic activity dropped sharply at pH ≥ 8 and ≤ 6 causing a predominance of sulfate reducers at pH ≥ 8.
Anaerobic Treatment of Municipal Solid Waste Landfill Leachate: Operation of a Pilot Scale Hybrid UASB/AF Reactor
Authors: Iza J. , Keenan P. J. , Switzenbaum M. S.
Published: May 2018

Landfill disposal is a widely used technique for solid waste management. The leachate produced, owing to moisture release and rain and snow infiltration, can cause environmental hazards if it is not properly collected, treated, and disposed. An on-site pilot plant study was carried out to assess the treatability of the leachate from a developing landfill. Details of the designed reactor and data collected during a long term run are presented, showing that a young landfill leachate is amenable to anaerobic treatment of its organic fraction, but special care should be taken with the management of the inorganic compounds, especially heavy metals.
Examination of Sediment Samplers
Authors: Ristenpart E. , Gitzel R. , Uhl M.
Published: May 2018

Different types of newly developed sediment samplers were investigated according to their suitability for operation in sewers and their ability to obtain representative sediment samples. The sediment shovel offers good practicability in small to medium sized sewers. Particles of small size and small specific gravity tend to be washed out while lifting the shovel. Considering these characteristics the sediment shovel is a useful tool for survey investigations focusing operational problems caused by sediments. The cryogenic sediment sampler is complicated to use but it offers the opportunity to get nearly undisturbed samples out of even big sized sewers with high sediment levels. A minimum sediment level of approximately 10 cm is needed. This type of sampler is well applied to special problems concerning either the quality of sediments in different heights or the sampling in big sized sewers. Another type of sampler is described but cannot be recommended for use in sewers.
A Sediment Transport Model for Sewers
Authors: Mark O.
Published: May 2018

This paper describes a mathematical sediment transport model for sewers. The model consists of a full hydrodynamic description running in parallel with a morphological model. Four different sediment transport formulations have been implemented in the model. Fredsøe's method for the calculation of the resistance from bed forms is compared to experiments carried out at Chalmers Technical University, Sweden. The model can be used as a tool for the analysis of sewer systems with sediment deposits. The model is being developed as part of a study being carried out at the University of Aalborg, Denmark and VBB-VIAK, Sweden.
Settleable Solids in a Combined Sewer System – Measurement, Quantity, Characteristics
Authors: Michelbach S. , Wöhrle C.
Published: May 2018

Sediment and transportation of mineral and organic pollution in combined sewer systems are not completely understood. For better understanding, samples of sediment, slime and urban runoff were taken from the combined sewer system of Bad Mergentheim. The sedimentation velocity of settleable solids was measured with a settling apparatus. Typical settling curves for sediment, slime and wastewater were compiled. Some of the samples were analysed for heavy metals and organic micropollutants. By this the relationship between settling velocity and the load of heavy metals can be shown. The gained data are of interest to size clarifier tanks for stormwater treatment.
Sediment Deposition in Storage Tanks
Authors: Saul A. J. , Ellis D. R.
Published: May 2018

The use of storage tanks in sewerage systems has increased in recent years. The primary functions of such tanks are to attenuate flow and to retain pollutants within the sewer system. The size of the required storage volume is dependent on the purpose for which the tank is to be used but the end product of any design analysis is the definition of fixed volume of storage which has to be included as part of the sewerage system. The main problem is to provide storage and effective separation of gross and suspended solids without incurring poor self cleansing and associated high maintenance costs.

The work outlined in this paper involved the development of a laboratory computer controlled monitoring system for the purpose of flow visualisation and for the comparative assessment of the sediment deposition and removal performance of different geometric configurations of storage tank. These systems used sophisticated control procedures and the latter had the facility to generate a flow hydrograph of any shape and duration and to superimpose on this hydrograph a pollutograph of synthetic sediment, in this case crushed olive stone wood flour. Particular attention was focused on the optimum length to breadth ratio for a given storage volume, the configuration of the chamber floor - number, shape and gradient of dry weather flow channels and benching (gradient; the type of roof support and the effect of multiple storms on the redistribution of deposited sediment.

The results of the work illustrated that very complex flow patterns were established within the storage tanks as the flow hydrograph was discharged through the system and that these flow patterns governed the sediment settlement, re-entrainment and transport processes in the tank. The velocity distribution within each chamber was a function of tank geometry, the shape, volume, and duration of the inflow hydrograph and the throughflow setting.

The paper is concluded by a series of recommendations to aid the design of storage tanks.
Appropriate Environmental Standards in Developing Nations
Authors: Ludwig H. F. , Ludwig R. G. , Anderson D. R. , Garber W. F.
Published: May 2018

Developing Countries are increasing their wealth, but have substantial ecological problems including high population growth, mass movement of rural populations to cities, and severe net negative cultural and ecological/environmental impacts. Additionally the World Community is now so closely watched by the media that political leaders of developing countries are forced by their citizens to give the appearance of personal and environmental protection by adopting the same ecological/environmental standards/criteria as the industrialized nations, when the economic and manpower resources make enforcement essentially impossible. The problem is intensified by the fact that the standards/criteria for industrialized countries are often based upon non-scientific/non-economic rationales driven by politically motivated media and environmental pressure groups. The developing countries, as well as the industrialized countries must eventually maximize the utilization of their available resources by utilizing the best scientific/economic rationale possible. Data is presented for the U.S.A. showing its development from about 1890 to the present. From these data it was apparent that the developing countries are following a very similar pattern. It is accordingly very important that these countries be aided to develop and utilize scientific/economic standards/criteria appropriate to their stage of development.
Monitoring of Coastal Ocean Waters Receiving Wastewaters in the USA: Review of Two 1990 Publications of the USA National Research Council – National Academy of Sciences and National Academy of Engineering
Authors: Garber W. F.
Published: May 2018

Required monitoring of the physical, biological and chemical condition of the nearshore waters of the ocean receiving treated wastewaters has been underway in the U.S.A. since 1955 or about 35 years. When established the stated intent had been to utilize the information obtained to evaluate the effects of the diffusion of wastewaters upon the beneficial values of these receiving waters. That is upon the food web including game and food fish; upon water contact sports uses; upon aesthetics; and upon the local, regional, and worldwide ecology. To this end original requirements had included a provision that the regulatory agency reduce the data obtained from the monitoring effort to information useful to themselves as well as to facility design and operational authorities. Inasmuch as the monitoring effort in 1989 was using funds in excess of 130 million dollars per year and had a 35 year data base, the Marine Board of the National Research Council - National Academy of Sciences: National Academy of Engineering established committees of scientists to evaluate the progress of the national monitoring effort and of the longest and most complete program of the Southern California Bight. It was found that the essential portion of the program, that of reducing the data obtained to usable information, had not been carried on so that approximately 35 years of data existed with little to zero information. In addition the data existed in pools of intensive samplings around discharge points with very little overall study of the coastal waters. Whether the discharge points were significantly different from the “normal” coastal waters was not really known because “normal” was not known. The Committees recommended procedures to follow to rectify these basic problems including reallocation of current funding to cover the research, control, design and operational needs. Their findings are summarized in the paper.
Cross-Flow Ultrafiltration Used in Algal High Rate Oxidation Pond Treatment of Saline Organic Effluents with the Recovery of Products of Value
Authors: Rose P. D. , Maart B. A. , Phillips T. D. , Tucker S. L. , Cowan A. K. , Rowswell R. A.
Published: May 2018

An algal high rate oxidation ponding process for treating organic s present in saline effluents has been described. The extreme halophile Dunaliella salina can be made to predominate in the system by manipulating salinity, producing products of value together with a waste treatment function. Application in treating tannery saline organic wastes was examined. Techniques appropriate for the harvesting of micro-algae from this and other algal production systems presents a limiting factor in the development of algal biotechnology. Cross-flow filtration was evaluated as a technique for micro-algal cell separation. Both microfiltration and ultrafiltration were found to produce effective algal removal from the medium, Cross-flow ultrafiltration with a polyethersulfone coated tubular filter produced effective separation with the production of cell concentrates in a viable condition. Flux rates of 30 - 40 LMH fall within acceptable levels for application in industrial processes. Cell shattering observed with microfiltration precludes its use for recovering whole or viable cell concentrates.
Industrial Wastewater Treatment with Membranes - A United States Perspective
Authors: Cartwright P. S.
Published: May 2018

Since the establishment of the U.S. Environmental Protection Agency more than 20 years ago, protection of the environment has steadily been moving up on the priority list of the American public. Concern over issues such as the ozone hole, the greenhouse effect, overflowing landfills, acid rain, destruction of the rain forests and over population have created an attitude of conservation and environmental responsibility throughout the country.

The united States Congress has passed the Pollution Prevention Act of 1990 which emphasizes “point-of-source” reduction, recycle or recovery.

The membrane separation technologies of microfiltration, ultrafiltration and reverse osmosis possess characteristics which make them attractive as recycle and recovery processes.

This paper details the testing requirements dictated by the specific applications and describes a number of case histories where membrane technologies have been evaluated for industrial wastewater treatment.
Contamination of Chlorinated Organic Substances in the Ocean Ecosystem
Authors: Tatsukawa R.
Published: May 2018

Persistent organochlorines such as PCBs, DDTs and HCHs are ubiquitous contaminants found in seas and oceans worldwide. They are transferred from terrestrial contaminant sources to open ocean through atmosphere and ultimately deposit into the oceanic waters. The tropical regions are likely to contribute greatly to the global contamination of some organochlorines in recent years. The contaminants in water phase are taken into ecosystems following the prey-predator relationship in the food-chain. In this context, cetaceans like dolphins, porpoises and whales are recognized as one of the animal groups most at risk from persistent organochlorines in the environment. They accumulate extremely high concentrations of organochlorines through feeding, and transfer large quantities to offspring during lactation. Unfortunately, they have a small capacity to degrade these contaminants. It may be concluded that marine mammals, particularly cetaceans, are among the most vulnerable organisms to long-term toxicity of hazardous man-made chenicals.