bluuebunny/crossref_metadata_2025 huggingface dataset:
Degradation of Xylene by a Biofilm Growing on a Gas-Permeable Membrane
Authors: Debus O. , Wanner O.
Published: May 2018

In a laboratory reactor, in which a biofilm was grown on a gas-permeable silicone membrane through which oxygen was supplied, the removal of xylene from the bulk fluid was investigated. A mathematical model, by which aerobic xylene degradation, biofilm growth, transport processes in the gas, biofilm and bulk fluid compartment and pH in the biofilm are described, was developed and used to analyse the effect of various experimental parameters on xylene removal. It was found that a few days after the experiment was started, the biofilm thickness reached an optimal value for which all xylene added to the reactor was microbially degraded and xylene was no longer transferred to the gas phase. Beyond the optimal thickness, biofilm growth led to a decrease of the percentage of the xylene which was degraded. This tendency could partly be compensated by an increase of the hydraulic shear stress, oxygen supply or buffer concentration in the reactor influent. A computer simulation showed that the model was able to adequately reproduce the experimental data and allowed to identify relevant experimental parameters, which can be used to control the microbial removal of volatile organics in membrane-biofilm systems.
Disinfection and Attachment of Bacterial Cells
Authors: Hermanowicz S. W. , Filho F. L.
Published: May 2018

Attachment of a mixed bacterial population isolated from well water was investigated using a rotating disk apparatus. The effects of two disinfectants (chlorine and monochloramine) applied to bacterial suspensions on subsequent cell attachment were examined. Both chlorine and chloramine appeared to adversely affect cell attachment.
Explanation of Biological Meaning of the So/Xo Ratio in Batch Cultivation
Authors: Chudoba P. , Capdeville B. , Chudoba J.
Published: May 2018

It is shown that the most important parameter in batch cultivation of mixed cultures is the ratio of the initial substrate concentration to the initial biomass concentration (So/Xo as COD/biomass). When the ratio is sufficiently low (below 2-4 depending on the mixed culture history) no cell multiplication takes place during the exogenous substrate removal. Under these conditions, a biomass increase is mostly due to the synthesis of storage polymers. It is also shown that the observed yield, Yobs, decreases with increasing So/Xo ratio. Under the high So/Xo conditions, more energy is spent for cell multiplication, which results in greater part of substrate being oxidized. Batch cultivation at high So/Xo ratios results also in higher concentrations of microbial polymers produced as waste products of mixed culture microorganisms. It is concluded that for the biodegradation studies with the aim to obtain kinetic constants it is necessary to work at low So/Xo ratios to prevent mixed culture microorganisms from substantial multiplication. This is necessary because cell multiplication during batch cultivation of mixed culture changes the proportion among slow-growers and fast-growers. This is the only way to obtain the kinetic constants which are representative of the original mixed culture.
The Treatment of Liquor Wastewater Containing High-Strength Suspended Solids by Membrane Bioreactor System
Authors: Nagano A. , Arikawa E. , Kobayashi H.
Published: May 2018

The wastewater from a Shochu liquor distillery contains high-strength organic compounds, especially ultra-high-strength suspended solids(SS). We investigated the treatment of the Shochu liquor wastewater using a pilot-scale membrane bioreactor system(MBS) for 190 days. The wastewater was fed to MBS at a concentration of 13,000 mg/l in SS and 40,000 mg/l in COD. It was proved that this system has a high performance in SS decomposition and organic compound elimination. The effluent BOD was less than 100 mg/l and the COD was less than 600 mg/l. The COD removal was more than 98 % at the COD loading rate of 7 kg/m3/d. More than 0.28 m3 of methane was obtained from 1 kg-COD. The VSS decomposition ratio calculated from a VSS balance was 85% and the VSS conversion ratio of feed COD was 0.057 kg-VSS/kg-COD. The withdrawal rate exerted the significant influence on the performance of the MBS.
Nitrogen Reduction – Volume Demand
Authors: Palmgren T.
Published: May 2018

Due to the slow growth of nitrification bacteria at low temperatures, nitrogen reduction normally requires long hydraulic retention time during winter. Important for the nitrification process is the aerated sludge age. Factors influencing the sludge age are aerated volume, mixed liquor suspended solids concentration, organic loading and sludge yield. In an existing plant you cannot easily expand the volume and the load is difficult to decrease. But the suspended solids concentration can be increased by running the biological step with the contact stabilisation process.

At the Käppala Association sewage treatment plant in Lidingö just outside Stockholm, one of the six aeration tanks has been reconstructed for full scale nitrogen removal experiments. In this tank the old aeration system has been replaced with rubber membrane diffusers. Further more there are several zones separated by walls in the tank. The tank can thereby be run with great flexibility. By running it with the contact stabilisation process, the sludge age has been improved by a factor between 1.5 and 2 and thereby it succeeds in keeping the nitrification bacteria in the system even during snow melting. At temperatures of about 9 °C and hydraulic retention times of less than 3 hours in the contact zone there has been a nitrification degree of up to 50 to 60 %. The experiment was conducted with a stabilisation zone of up to half the total volume of the aeration tank.

The main purpose for the experiments during the winter seasons was to improve nitrification. Keeping the nitrifiers in the system had been a crucial problem during previous years. When the nitrifiers were lost with an increased flow and decreased temperature the nitrification process didn't restart until the temperature was increased and the load decreased. Usually this didn't occur until the middle of the summer meaning a loss of nitrification for up to six months.

In Sweden there is a goal set for 50 % nitrogen reduction for the plants in the Stockholm region. At Käppala we manage to keep 60 to 70 % nitrogen reduction during the warm season, that is from July to December. If we can keep up the nitrification the whole year we can achieve 50 % as a yearly average under normal conditions even though we can't keep the nitrogen reduction rate as high during the cold season.
Fast Digester Start-Up under Mesophilic Conditions Using Thermophilic Inoculum
Authors: Cecchi F. , Pavan P. , Mata-Alvarez J.
Published: May 2018

The paper deals with fast procedures adopted for starting-up anaerobic digesters treating biological wastes. In particular, results related to the behaviour of a digester treating sewage sludge with a fast start-up (in 22 days) and using a thermophilic inoculum are presented and compared with those related to a passage from mesophilic to thermophilic temperatures (from 37 to 55°C, in 31 days) and to a direct re-start-up under thermophilic conditions (27 days). In the latter cases, the organic fraction of municipal solid wastes was digested. Main findings concern: the identification of two retention times as the necessary period for reaching the first steady-state condition; the usefulness of performing a real time process monitoring the observation that thermophilic inoculum allows better digester performances in the first start-up period, a finding however, that requires more experimental work.
Uptake of Organic Substrates and Accumulation of Polyhydroxyalkanoates Linked with Glycolysis of Intracellular Carbohydrates under Anaerobic Conditions in the Biological Excess Phosphate Removal Processes
Authors: Satoh H. , Mino T. , Matsuo T.
Published: May 2018

Anaerobic uptake mechanisms of acetate, propionate and lactate by the sludge developed in an anaerobic aerobic biological phosphate removal process was investigated. Anaerobic batch experiments were conducted with these substrates, and mass balances of materials involved in substrate uptake metabolism were calculated. These substrates were accumulated in the sludge as polyhydroxyalkanoates composed of 3-hydroxybutyrate, 3-hydroxyvalerate, 3-hydroxy-2-methylbutyrate and 3-hydroxy-2-methylvalerate. The reducing power necessary for the formation of polyhydroxyalkanoates from acetate and/or propionate was shown to be supplied from glycolysis of intracellular carbohydrates. Lactate was converted to 3-hydroxyvalerate rich polyhydroxyalkanoate via acetyl-CoA and propionyl-CoA by using propionate fermentation pathway. Redox balance was found to be a factor regulating the anaerobic uptake of substrates and their further metabolism. Glycogen seemed to serve not only as a source of reducing power necessary for the redox balance regulation but also as an important energy source, because glycolysis can provide both reducing power and energy. It was indicated that some bacteria might be able to get energy necessary for substrate uptake under strict anaerobic conditions not by the polyphosphate hydrolysis but by the consumption of intracellular carbohydrates.
Significance of External Carbon Sources on Simultaneous Removal of Nutrients from Wastewater
Authors: Tam N. F. Y. , Wong Y. S. , Leung G.
Published: May 2018

Laboratory-scale studies were undertaken to examine the effects of easily-biodegradable organic substances upon the nutrient removal by a simulated sequencing batch reactor (SBR). The fill and react period of the SBR was 14 hours, including an instant fill, 7 hours aeration, 4 hours anoxic and 3 hours aeration period. Three kinds of commonly used carbon sources, namely methanol, glucose and sodium acetate, at the concentrations equivalent to theoretical COD values of 50, 100 and 150 mg O2 l-1 were added to each reactor prior to the anoxic stage. The results showed that the concentration of NH4+-N dropped from its initial 50 to 18 mg l-1 (64 % removal) during the first aeration period, with the NO3−-N content increased from 2 to 33 mg l−1. A 60% depletion of COD was also recorded in this period. Denitrification occurred during the anoxic period, higher amount of NO3−1-N was removed in the reactors supplemented with carbon substrates at the concentrations of 100 and 150 mg l-1. The final inorganic nitrogen content was less than 5 mg l-1 in the reactor supplemented with 150 mg l-1 sodium acetate. Simultaneous removal of phosphorus was reported in reactors supplied with high concentration of sodium acetate. In these reactors, large amount of P was released during the anoxic/anaerobic period but the released P was taken up by bacterial cells in the subsequent aeration stage, and the final P content was less than 1.5 mg l-1 (84 % removal was achieved). Among the three carbon sources used, sodium acetate was the most efficient and effective source in removing wastewater nutrients, followed by methanol, and glucose was the least reliable substrate.
Full-Scale Application of Nitrogen Removal with Methanol as Carbon Source
Authors: Nyberg U. , Aspegren H. , Andersson B. , Jansen J. la C. , Villadsen I.S.
Published: May 2018

In Sweden many advanced sewage treatment plants for BOD and phosphorus removal have to be extended with nitrogen removal. Due to existing plant configuration and wastewater composition, denitrification with supply of an external carbon source can be a cost-effective solution in many cases.

At the Klagshamn wastewater treatment plant in Malmo investigations for extensive nitrogen removal have been made in a single-sludge system with pre-precipitation and post-denitrification where methanol was added for denitrification. Results from the tests showed that a high level of nitrogen removal can be reached, and that the process was stable and easy to operate. The process application gave less supplementary cost for an extended nitrogen removal than for upgrading the plant with larger basin volumes.

In order to examine the purification performance caused by the addition of methanol, the starting period was followed extensively with online nitrate sensors and daily composite samples. The development of the denitrif ication capacity of the sludge with methanol and acetate as carbon sources was followed and microbiological changes were examined microscopically.

Complete denitrification was obtained after approximately one month at 10°C. The denitrification capacity of the sludge with methanol reached that of acetate after about the same time. The microscopic examination revealed a growing population of budding and/or appendaged bacteria, presumably Hyphomicrobium spp, reaching a stable maximum at the time when optimal nitrate removal occurred.
Nitrification Inhibition - A Source Identification Method for Combined Municipal and/or Industrial Wastewater Treatment Plants
Authors: Kroiss H. , Schweighofer P. , Frey W. , Matsche N.
Published: May 2018

Inhibition of nitrification at combined municipal and/or industrial treatment plants can cause serve problems in regard to the future low effluent standards for ammonia nitrogen. As inhibition problems often occur only for limited periods and are caused by different substances it is very difficult to find the sources of these substances within the sewer system. Using a two step strategy based on a respiration test it is possible to locate these sources within a short time and to concentrate then on the abatement of the inhibiting wastewaters. The method of the respiration test was developed and the relationship between dilution and inhibition could be described by a new mathematical inhibition model. The method was applied at an Austrian city (Linz) with more than 50% wastewater load coming from industry during the design period for the extension of the existing plant (800 000 PE).
Improvement of Secondary Clarifiers Efficiency by Porous Walls
Authors: Krebs P. , Vischer D. , Gujer W.
Published: May 2018

Parameters influencing the flow field in final settling tanks are discussed. The effects of a porous wall on the hydraulics as well as on the flocculation of activated sludge are described. The flow upstream of the wall is rendered more uniform by the increased overall pressure and by deflecting the bottom current to the upward direction, while the hole jets beyond the wall induce velocity gradients to enhance flocculation and improve settling properties of the sludge. Installing several porous walls improves the effects, such as increasing the volume with forward flow, preventing strong density currents and improving the stability of tank performance at wet-weather flow. A method to optimize the porosity and the hole size is introduced.
Reuse of Wastewater Sludge in Manufacturing Non-Conventional Construction Materals - An Innovative Approach to Ultimate Sludge Disposal
Authors: Tay J. H. , Show K. Y.
Published: May 2018

The increased requirements for the treatment of wastewater, coupled with industrial growth, have created a need to treat and dispose of an over-proportional sludge volume. At the same time increasingly stringent regulations have resulted in limitations on the ultimate sludge disposal options. In highly urbanized municipalities, scarcity of landfill sites and increasing environmental awareness pose major public concern on the disposal of sludge. This situation has prompted the interest in recycling and reuse of sludge into building and construction materials as means of alleviating sludge disposal problems. This paper presents the results of the use of wastewater sludge to produce lightweight aggregates and cementitious binder as non-conventional construction materials. Lightweight coarse aggregates were produced from the incineration of sludge-clay mixture. Test results of porosity, specific gravity, bulk density, ten percent fines, water absorption and concrete strength, indicate that clay-blended sludge could be used to produce lightweight aggregates. The feasibility of using dried sludge mixed with lime as a cementitious binder after incineration was also studied. Evaluation of the mortar cube strengths shows that it is possible to produce masonry binder from sludge that will satisfy the strength requirements in the ASTM standard for masonry cement.
Sorption onto and Recovery of Cr(VI) Using Iron-Oxide-Coated Sand
Authors: Bailey R. P. , Bennett T. , Benjamin M. M.
Published: May 2018

A new adsorbent media has been prepared consisting of iron oxide coated onto sand surfaces. The oxide coating is made by adding a solution of a ferric salt and base to a mixture of sand and applying various heating protocols. The iron oxide is an excellent, regenerable adsorbent, and the process of coating it on sand allows the media to be used in a packed column. Depending on solution pH, the media can be made to adsorb either cationic or anionic metals. In this work, the media was used to collect hexavalent chromium from a synthetic waste stream. The influent contained 20 mg/L Cr(VI), and better than 99% removal was achieved consistently. Once breakthrough occurred, the media could be regenerated by exposure to base. The pH of the regenerant solution determined the kinetics and efficiency of the regeneration process. With further development, the process represents an inexpensive and effective method for removal and recovery of metals from industrial waste streams.
Optimal Fiber Spacing in Externally Pressurized Hollow Fiber Module for Solid Liquid Separation
Authors: Kiat W. Y. , Yamamoto K. , Ohgaki S.
Published: May 2018

Flux decline and clogging mechanism in hollow fiber bundle by activated sludge and kaolin clay suspensions were investigated experimentally. Filtration characteristics of hollow fiber bundles consisting of 10 fiber threads but different in packing density were observed. The main reason for severe flux decline was due to the accumulation of particles at the space in between fibers. The results showed that there was no particle accumulation when fiber packing density β was lower than a critical value βa. Maximum filtration flux and maximum membrane productivity Q/Vr,which is defined as the filtration rate per unit volume of bundle, were obtained below and at this point, respectively. When fiber packing density β was increased, accumulation of particles happened and flux declined rapidly to a minimum, then increased to a maximum and then decreased when surface clogging predominated in the case of activated sludge filtration, but remained almost constant for the case of kaolin clay suspensions. The critical point where accumulation of particles started was related to cross flow velocity. The higher the cross flow velocity, the higher the value of βa obtained.
Practical Guide to Determine the Impact of Radon and Other Radionuclides on Water Treatment Processes
Authors: Martins K. L.
Published: May 2018

During treatment of groundwater, radon is often coincidentally removed by processes typically used to remove volatile organic compounds (VOCs)-for example, processes such as liquid-phase granular activated carbon (LGAC) adsorption and air stripping with vapor-phase carbon (VGAC). The removal of radon from drinking water is a positive benefit for the water user; however, the accumulation of radon on activated carbon may cause radiologic hazards for the water treatment plant operators and the spent carbon may be considered a low-level radioactive waste.

To date, most literature on radon removal by water treatment processes was based on bench- or residential-scale systems. This paper addresses the impact of radon on municipal and industrial-scale applications. Available data have been used todevelop graphical methods of estimating the radioactivity exposure rates to facility operators and determine the fate of spent carbon.

This paper will allow the reader to determine the potential for impact of radon on the system design and operation as follows.Estimate the percent removal of radon from water by LGAC adsorbers and packed tower air strippers. Also, a method to estimate the percent removal of radon by VGAC used for air stripper off-gas will be provided.Estimate if your local radon levels are such that the safety guidelines, suggested by USEPA (United States Environmental Protection Agency), of 25 mR/yr (0.1 mR/day) for radioactivity exposure may or may not be exceeded.Estimate the disposal requirements of the waste carbon for LGAC systems and VGAC for air stripper “Off-Gas” systems.

Options for dealing with high radon levels are presented.
Dynamic Models for Clarifiers of Activated Sludge Plants with Dry and Wet Weather Flows
Authors: Otterpohl R. , Freund M.
Published: May 2018

Dynamic simulation of wastewater treatment plants becomes more realistic, if models of primary and secondary clarification are implemented. A simple model of the primary clarifier can describe dynamics of buffered influent or sludge water concentrations. Different changes in ratios of particulate fractions of COD depending on influent flows are modelled as well.

Processes in activated sludge plants are affected by the replacement of sludge to the clarifier and by the loss of solids through the effluent. These effects are very strong at combined water flows. The two models best applicable as of yet did not meet measured values for effluent solids. One of them describes thickening and storage of sludge quite well. The developed two component model presented here is able to represent the behaviour of secondary clarifiers at dry and wet weather flows.
Sequential Batch-Fed Effluent Storage Reservoirs: A New Concept of Wastewater Treatment Prior to Unrestricted Crop Irrigation
Authors: Mara D. D. , Pearson H. W.
Published: May 2018

A modification of the Israeli system of holding pond effluents in single storage reservoirs prior to restricted irrigation is presented which enables the treated wastewater to be used for unrestricted irrigation. The modification comprises the use of 3 or 4 sequential batch-fed effluent storage reservoirs, each of which is operated on a cycle of fill, rest, use. The rest period permits the faecal coliform levels to drop below 1000 per 100 ml, in accordance with the current WHO recommendations for unrestricted irrigation. The number of storage reservoirs and the timing of the fill/rest/use cycle depends on the length of the irrigation season; design examples are presented for irrigation seasons of 12, 6 and 4 months, and these are compared with a conventional pond design.
Waste Water Reuse by Freeze Concentration with a Falling Film Reactor
Authors: Müller M. , Sekoulov I.
Published: May 2018

Experiments with a falling film reactor were conducted to examine the potential of the freeze concentration to reuse municipal waste water. The waste water was recycled in the falling film reactor while ice films were frozen on the cooled inner walls. Pure water was removed from the solution by crystallization, and the liquor was concentrated. Finally, the separated clear ice was melted. Various parameters such as conduction, TOC, COD and NH4-N of the melted ice and waste water concentrate were measured. A clearance efficiency up to 99% was observed for municipal waste water and 91% for high concentrated waste water. In addition, particulate solutions were removed from the aqueous phase as efficiently as the organic and inorganic solutes.
Comparison Between Chlorine Dioxide and Chlorine for Use as a Disinfectant of Wastewater Effluents
Authors: Narkis N. , Kott Y.
Published: May 2018

The aim of this research was to investigate the possibility of using chlorine dioxide as an alternative to chlorine as a disinfectant of effluents from municipal sewage treatment plants, in order to obtain an environmentally safe source of water that can be reused for a variety of purposes. The main task was to compare the effect of chlorine dioxide and chlorine as a disinfectant of effluents from various types of sewage treatment plants. Residual chlorine dioxide, chlorite ion, chlorine and MPN/100mL of the surviving total coliforms, fecal colifonms, fecal streptococcus and E-coli phages were determined as a function of these disinfectants' doses and contact times.
Monitoring Large Scale Wastewater Reclamation Systems – Policy and Experience
Authors: Azov Y. , Juanico M. , Shelef G.
Published: May 2018

The two largest wastewater reclamation systems in Israel are monitored for both quality and operational parameters by a group of experts from the Environmental and Water Resources Engineering Center at the Technion in cooperation with Mekorot - Water Company for Israel. The Greater Haifa wastewater reclamation project is monitored now for the eighth year successively and the Greater Tel Aviv reclamation complex for the second year. Our experience indicates that the establishment of a comprehensive monitoring program for such systems is essential for the successful operation of the reclamation projects. However, periodic fundamental reviews of the monitoring program are necessary in order to improve and update its components. The basic trend of the two monitoring programs was to reduce to a great extent the number of both sampling points and parameters tested, while increasing specific research studies concerning particular problems that arose during the regular monitoring procedure.
Use of Constructed Wetlands to Treat Domestic Wastewater, City of Arcata, California
Authors: Gearheart R. A.
Published: May 2018

This paper summarizes 10 years of experience applying oxidation pond effluent to constructed wetlands in Arcata, California. The first five years (1980-1986) was spent experimenting with 6×66 metre constructed wetland mesocosm. The second five years involved fullscale analysis of 2.8 hectares and 12 hectares effluent receiving marshes. Experience to date has verified the capability of constructed wetlands to reliably and effectively meet advanced secondary water quality standards. Effluent BOD and suspended solids concentrations of 30 and 30 mg/l respectively can be met ninety percent of the time with weekly samples; fecal coliform levels of 20 CFU/100 can be met 90 percent of the time. Total inorganic nitrogen levels of 5 can be met in the growing season at 12 mg/l in the non-growing season. Design criteriaaregiven for BOD, SS, coliform, and TIN removal for a temperature range of 6 to 20°C. Experience gained to date on the construction details, vegetation planting, and operational consideration is also summarized in the paper.
Modelling Coliform Reduction in Wastewater Stabilization Ponds
Authors: Saqqar M. M. , Pescod M. B.
Published: May 2018

The paper addresses faecal coliform reduction in a large wastewater stabilization pond system. It was found that values of the faecal coliform reduction rate coefficient (Kb) increased with increasing water temperature (Tw), solar radiation (Rs) and pH and with decreasing total BOD5 (CBOD), soluble BOD5 (SBOD) and surface organic loading (BA,CBOD) Correlation analysis has shown that Kb is more responsive to Tw than to Rs and to SBOD than to CBOD. An optimized-parameter model was developed to describe Kb in secondary ponds.
Model of Algal Bacterial Clay Wastewater Treatment System
Authors: Carberry J. B. , Greene R. W.
Published: May 2018

A computer model is presented for an innovative wastewater treatment process known as the Algae-Bacterial-Clay Treatment (ABCT) system. In this process the photosynthetic production of dissolved oxygen by algae supports the bacterial breakdown of organic matter in wastewater. Clay is added to the plug flow reactor to dampen input BOD variation. The model was developed to gain an improved understanding of transient behavior of dissolved oxygen and pH in the treatment reactor during typical operation.

The model consists of five nonlinear ordinary differential equations describing the time rate of change of algae mass, bacterial mass, organic substrate, dissolved oxygen, and dissolved carbon dioxide. A fourth-order Runge-Kutta integration technique was used to predict system response at discrete time steps. The pH variation expected from changes in dissolved carbon dioxide was based upon presumptions that the system is buffered by the carbonic acid system, and that alkalinity does not change appreciably during the course of time. These assumptions were confirmed by experimental results.

The model successfully predicted diurnal fluctuations in dissolved oxygen, carbon dioxide, and pH in the ABCT process. The model predicted that algae will supply sufficient oxygen during sunny and partly sunny days to eliminate the need for continuous mechanical aeration. This feature should result in significant cost savings over conventional secondary wastewater treatment schemes. Surplus dissolved oxygen produced by algae during the day should be completely depleted at night due to bacterial respiration. This lack of oxygen, in turn, resulted in reduced substrate utilization and potential effluent discharge violations. Mechanical aeration during the night might be one possible remedial strategy. Despite its dynamic behavior, the ABCT process would be a viable and potentially cost efficient wastewater treatment strategy.
Research on the Operational Regularity and Management Technology of Stabilization Ponds
Authors: Bian J. , Li X.
Published: May 2018

This paper studies the treatment of municipal wastewater in Tianjin by intensified facultative ponds. Based on the analyses and calculation of a great quantity of data, the removal efficiencies and influencing factors of BOD, COD, SS, TN etc. should be taken to promote the purification effects of stabilization ponds. Moreover, from the process of the purification of wastewater, some relationship with DO level, concentration of algae chlorophyll and daphnia could be found and be investigated as basis of controlling and optimising of the normal operation of ponds. It also provides a significant index on applying technology and scientific management methods for the treatment of wastewater by stabilization ponds.
The Biosorption of Selected Pesticides from Water by Biologically Activated Carbon
Authors: Dalmacija B. , Tamaš Z. , Miškovic D. , Karlovic E. , Petrovic O.
Published: May 2018

The work describes a study of the possibility of removal of organo-phosphorus insecticide quinalphos and organochlorine herbicide lindane from water by using the biofilm formed on active carbon. It was established that two similtaneous processes took place in the biosorption column - adsorption and microbiological degradation of the adsorbed matter. At the shock concentrations of lindane in the influent, an inhibition of microbiological processes in the biofilm occurred. It was observed that the biosorption system was more efficient in the removal of the organo-phosphorus insecticide than of the organo-chlorine herbicide.
Anaerobic–Aerobic Treatment of a Dye Wastewater by Combination of RBC with Activated Sludge
Authors: Zaoyan Y. , Ke S. , Guangliang S. , Fan Y. , Jinshan D. , Huanian M.
Published: May 2018

The mechanism, technology and character of the anaerobic-aerobic treatment of dye wastewater by combination of fixed film with suspended growth after acclimatization are discussed in this paper. The results show that the COD decreased from 600-900mg/l of influent to about 150mg/l of effluent. The BOD and the dilution times of colourity decreased from 200-300mg/l and 200-500 times to less than 50mg/l and about 80 times respectively, when the HRT and COD RBC-area load of anaerobic and aerobic RBC were 7-8hrs and 4.5-5hrs and 40-50g/m2·d and 30-40g/m2 respectively. This treatment process has the advantage of very low waste sludge. Either anaerobic or aerobic RBC has better quality transmission and mixing ability, so that MLSS in the tank were about 1000-3000mg/l without any blockages of RBC. The efficiency of a 3 stage alone oblique cross passageways packing RBC with sludge return was also high, except in regard to colour under aerobic conditions only.
The Effects of the Secondary Carbon Source on the Biodegradation of Chlorinated Phenols in Biofilm Reactors
Authors: Lu C. J. , Chen S. J.
Published: May 2018

The effects of the presence of a secondary carbon source on the biodegradation of chlorinated phenols were studied with column biofilm reactors. The biodegradability of chlorinated phenols was studied with a series of batch reactors. The biodegradability of chlorinated phenols was to follow the order of phenol > 2,4-dichlorophenol > 4-chIorophenol > 2,4,6-trichlorophenol > 2-chlorophenol > 3-chloro-phenol. The presence of a relatively more biodegradable but higher chlorinated phenol, such as 2,4,6-trichlorophenol, enhanced the biodégradation of a less chlorinated butrecalcitrantphenol, such as 2-chlorophenol. The addition of phenol, an easily biodegradable compound, generally decreased the biodegradation of chlorinated phenols.
Decrease in Toxicity of Pentachlorophenol and Toluene to Growth of Selected Microbial Consortia and Activated Sludge by Pretreatment with Phanerochaete chrysosporium
Authors: Bower Carberry J. , Kovach L. E.
Published: May 2018

The white rot fungus Phanerochaete chrysosporium can degrade toxic compounds under specific nutrient conditions. This attribute was utilized in order to determine the effect of fungal pretreatment on model compounds pentachlorophenol and toluene. The fungal culture was purchased from ATCC, cultured on dextrose agar, and the mycelia harvested to degrade the model compounds. P. chrysosporium was able to degrade up to 74% of initial pentachlorophenol concentration in eight days and up to 31% initial toluene in 31 hours.

Specific growth rates of activated sludge and selected microbial consortia were determined on untreated and fungal-pretreated parent model compounds. Specific growth rates for activated sludge and selected microbial consortia were enhanced by fungal pretreatment of both model compounds. Specific growth rates indicated more efficient use of toluene by activated sludge than by toluene-selected microbial consortia, while pentachlorophenol- selected microbial consortia exhibited more favorable growth rates on pentachlorophenol than did activated sludge. Pretreatment results indicated that the toxicity of model compounds was reduced by fungal pretreatment. The growth rates were compared and used as an indication of toxicity reduction which can be exploited at contaminated waste sites or at industrial pretreatment facilities.
Experimental Evaluation of Microbial Metal Uptake by Individual Components of a Microbial Biosorption System
Authors: Pradhan A. A. , Levine A. D.
Published: May 2018

Some microorganisms have the capacity to concentrate metal ions. Besides binding metal ions to cell walls, it is also possible that chemical complexation occurs between metal ions and extracellular enzymes. Experimental studies were conducted to evaluate metal uptake by cells and extracellular material. Dialysis studies demonstrated that extracellular material possesses a greater capacity of binding metals when binding is considered on the basis of chemical oxygen demand (COD).
Cross-Coupling of a Chloroaniline and Phenolic Acids Catalyzed by a Fungal Enzyme
Authors: Tatsumi K. , Wada S. , Ichikawa H. , Liu S.Y. , Bollag Jean-Marc
Published: May 2018

The reaction between 3,4-dichloroaniline and vanillic, syringic and protocatechuic acids was investigated in the presence of a laccase isolated from the fungus Rhizoctoniapraticola. The aniline alone was not oxidized by the laccase, but if incubated with the phenolic acids and the laccase, cross-linking took place. Particularly the protocatechuic acid and syringic acid reacted with 3,4-dichloroaniline, and cross-linked dimers were isolated as main products.
Effect of Temperature on Prosperity and Decay of Genetically Engineered Microorganisms in a Microcosm System
Authors: Murakami K. , Inamori Y. , Sudo R. , Kurihara Y.
Published: May 2018

This study was conducted to evaluate the effect of temperature on prosperity and decay of genetically engineeredmicroorganisms (GEMs) in a microcosm system. GEMs such as Escherichia coli strain HB101 and HB101/pBR325 were injected into an aquatic flask-size microcosm which consisted of bacteria, Cyclidium glaucoma, Lepadella sp., Philodina sp., Aeolosoma hemprichi, Chlorella sp. and Tolypothrix sp.. As a result, the prosperity and decay of GEMs was changed depending on temperature and a microbiota in the microcosm system was changed by temperature. It was suggested that the predatory activities of protozoa and metazoa were greatly affected by the cultivation temperature, and the prosperity and decay of GEMs was also greatly affected by temperature. Consequently, it was considered that temperature should be regarded as an important factor for evaluating environmental release of GEMs.
Achievement of Biological Nutrient Removal in a Full-Scale Rotating Biological Contactor Wastewater Treatment Plant
Authors: Neu K. E.
Published: May 2018

A Central Wisconsin municipal treatment plant (WWTP) with a significant industrial contribution and seven (7) years of Rotating Biological Contractor (RBC) operation was the demonstration site for process modifications which provided significant biological nutrient removal (BNR). The study was conducted June-October, 1990. The plant was near 70% of hydraulic design load and averaged 90% of organic design load, with numerous excursions above organic design load. The BOD:P ratio was above 20:1, and the BOD:TKN ratio was above 10:1. Process modifications resulted in total phosphorus and total nitrogen reductions of 60-90% without chemical addition. Other benefits realized include increased clarity of the secondary effluent and an approximate 50% reduction of RBC shaft biomass weight.
Treatment Strategy for Cr(VI)-Bearing Wastes
Authors: Lin C. F. , Rou W. , Lo K. S.
Published: May 2018

The effects of reductants and alkali on the sludge quantity of chromium wastes and the teachability and physical properties of solidified chromium matrix are investigated in this study. FeSO4 and NaHSO3 are model reductants, and NaOH and Ca(OH)2 serve as bases, respectively. Portland cement was used to solidify Cr sludges generated from real wastes. Results from potentiometric redox titration showed that a 99.9% destruction of Cr(VI) at equivalence point is not achievable unless additional dosage is imposed. The extra amounts of reducing agent necessary for 99.9% conversion of Cr(VI) to Cr(III) is dependent on system parameters such as pH and type of reductants applied. An increase in operating pH where redox proceeds may acquire much more reducing chemicals than lower pH does. The optimum pH range for maximum precipitation is from 8.5 to 9.0. Chromium sludges generated from synthetic wastewater have a specific resistance from 8.7×l011 to 1.28×l013 m/kg. The use of Ca(OH)2 as base to precipitate Cr(III) produces sludge with lower specific resistance and larger particle size (near 20 to 60 µm). When examined with TCLP test, the chromium leachated out to the solution from matrix is generally less than 1 mg/L. Compressive strength of solidified sludge can reach near 10 kg/cm2 in 3 days based on 1:1 sludge/cement ratio. The compressive strength is affected by the type of reductants as well as the bases employed in the wastewater treatment processes. To producc a matrix with better compressive strength, it is recommended to use FeSO4 along with Ca(OH)2; however, if NaOH is used to control system pH, NaHSO3 is suggested to serve as reductant.
Heavy Metals Removal from Wastewater by Using Activated Peat
Authors: D'Avila J. S. , Matos C. M. , Cavalcanti M. R.
Published: May 2018

The processes used to remove heavy metals from inorganic wastewater have in general low efficiency. The use of activated peat obtained by using a process similar to a cation exchange reaction increases the removal efficiency up to five times when compared with peat “in natura”. The main objective of this work is to show the fundamental mathematical model, governed by diffusion process and the algorithms utilized to design the batch and the continuous feed stirred tank reactors or in some cases a fixed bed reactor. The principal dimensions of these equipments are obtained from the knowledge of the activated peat's cation exchange capacity used in the process, and the main chemical characteristics of the heavy metal ion contained in the wastewater. Besides, two important parameters are also included: the ion concentration and the efficiency of the process obtained from laboratory kinetics experiments. For example Pb+2 is removed l:rom a wastewater at a concentration of 50g/m3 in five minutes or less, with an efficiency of 98%.
Rapid Removal of Colloidal Organics from Domestic Wastewater
Authors: Bunch B. W. , Griffin D. M.
Published: May 2018

Batch experiments were conducted with raw wastewater and preaerated microbial sludge to investigate the removal behavior of the contact stabilization activated sludge process. This process was originally developed based on observed rapid drops in BOD which were attributed to rapid adsorption of colloidal organics. To date no data have been presented verifying that rapid colloidal adsorption occurs or is responsible for rapid BOD decreases.

Food to Microorganism (F:M) ratios were varied from 0.047 to 0.447 mg COD/mg MLSS during batch tests conducted with thirty minute contact times. Mixed liquor samples were collected at predetermined times, poisoned with mercuric chloride to halt microbial activity, and settled. Samples of the supernatant were drawn off and the COD of organics in different size ranges determined using a sequential filtering technique. Colloidal COD was defined to be the difference between the COD of organics passing a 1.5 µm filter and those passing a 0.03 µm filter.

Results indicated that rapid colloidal removal occurred. Colloidal COD concentrations decreased from initial values (maximum 85 mg/l) to near 0 mg/l within five minutes after mixing. Such behavior was only observed for the colloidal fraction and occurred regardless of the initial colloidal COD, total COD, or F:M ratio. It was concluded that physical coagulation was most likely the mechanism responsible for rapid colloidal removal.
A Study of Controlled Recirculation of Anaerobic Activated Sludge Digestion Reactors
Authors: Ouyang C.-F. , Lin H.-Y.
Published: May 2018

A bench scale anaerobic activated sludge digestion (AASD) process was developed to study the effect of biomass recycling at different amounts of digested sludge recirculation and various solids concentrations in feed sludge. It was selected to observe how the anaerobic digestion can be improved and stabilized by using municipal wastewater sludge. The mathematical model of AASD process was developed.The positive effect of biomass recycling on the sludge concentration depends on the settling rate of the sludge. The performance parameters such as SRT, methane yield and DHA of the reactor with R= 0.5 were found best among those of the other recycle ratio reactors. With the reactor with sludge loading of 1.1 kg TVS/m3 day, SRT/HRT = 1.493 can be obtained.
Operational Determination of the Activated Sludge Process Using Neural Networks
Authors: Tyagi R. D. , Du Y. G.
Published: May 2018

A steady-statemathematical model of an activated sludgeprocess with a secondary settler was developed. With a limited number of training data samples obtained from the simulation at steady state, a feedforward neural network was established which exhibits an excellent capability for the operational prediction and determination.
An Experimental Investigation of Mechanism and Operating Conditions of Multi-Stage Reversing-Flow Bioreactor (MRB) in Treating Domestic Wastewater
Authors: Arora S. , Mino T.
Published: May 2018

An experimental investigation of mechanism and operating conditions of Multi-Stage Reversing - Flow Bioreactor (MRB) in treating domestic wastewater was carried out. Aerobic degradation, dissimilation of Sulfur compounds and assimilation of Sulfur microorganisms were the main mechanisms involved in COD removal. Methane production was found to be negligible. At an upflow velocity of 73 m/d with an organic loading upto 1.66 kg COD/cum.d, without recycling of wastewater, 85-90 % COD removal efficiency and 15-20 mg/l of effluent SS were observed. However by recycling of wastewater same performance was achieved with an upflow velocity of 109 m/d and an organic loading of 2.4 kg COD/cum.d. Yield coefficient was found to vary between 0.12-0.18.
Influence of Motor Vehicle Exhausts on Chemical Components in Rainwater
Authors: Adachi A. , Kobayashi T.
Published: May 2018

In order to clarify the possibility of NO3− being one of concomitants for acid rain, we have measured pH, electric conductivity (EC) and cationic and anionic ion levels in rain water collected from three different locations in Kobe, Japan: The distances from the highway (Hanshin Highway) are 50 m at the A point, 1,500 m at the B point and 2,900 m at the C point, respectively. Significant correlations were observed between the respective NO3− and Ni2+ levels in the rain water obtained from the A and B points. Since these ions are usually included in motor vehicle exhausts, the results suggest that acidity in rain water is mainly derived from NO3− due to motor vehicles and that the levels of Ni2+ in rain water are evaluated as an indication of air pollution by motor vehicle exhausts.
Total Discharges Taken into Account for Comprehensive Planning of Urban Drainage and Waste Water Treatment
Authors: Kollatsch D.-Th.
Published: May 2018

The most important task of urban drainage and waste water treatment in the future is the environmental care of rivers and receiving waters. For this it is necessary to have a look at all discharges of sewer systems and treatment facilities. With simulation models the interactions between surface, sewer systems, overflow structures and treatment facilities can be shown. With these models the efficiency of upgrading measures can be proved in all parts of urban water systems.
The Izmir Bay Wastewater Management Project – Economical Considerations
Authors: Balkas I. T. , Juhasz F. , Yetis U. , Tuncel G.
Published: May 2018

Izmir Bay is one of the great natural areas of the Mediterranean and compares well with similar coastal areas in the world. Izmir which is the main urban area around the Bay is an important industrial, commercial and cultural focal point. It has the second biggest harbour and is the third largest city in the country. The Izmir metropolitan area has experienced rapid population increase which placed an intense pressure on the environment of the bay, housing, infrastructure and social services. The main sources of pollution in the bay are domestic and industrial effluents which account for 50% of the observed organic pollution. Rivers discharging to the Izmir Bay carry mostly industrial discharges. The main forms of pollution in the Izmir Bay are organic pollution, nutrients, pathogenic organisms and toxic material carried by rivers. Scientific evidence suggests if no pollution control measures are taken immediately pollution in the Bay will soon reach a critical level leading to the collapse in the ecosystem. With this understanding Izmir Sewerage and Stream Control Project which foresees the reestablishment of the Bay's water quality was started in 1983. The preliminary assessment of the costs and benefits of the project suggests that the benefits of the proposed pollution control system could significantly outweigh the costs of the control measures by a factor of about eight.