Biomedical subjects

D Orhon

Publications and source records attributed to D Orhon.

36 records · Page 2Linked to original sources

PubMed2002

Appropriate basis of effluent standards for industrial wastewaters.

Designing industrial discharge standards should reflect the numerical compromise between what can be achieved to prevent environmental pollution and sustainable development. They should involve categorical limitations for specific sources. Micropollutants represent the major concern for industrial effluents. A micropollutant-based subcategorization is needed for an effective control of industrial effluents. Regulations imposed require a comprehensive knowledge of polluting processes and sources, and technological limits of available treatment technologies.

Industrial Waste↗

PubMed2002

Important limitations in the modeling of activated sludge: biased calibration of the hydrolysis process.

The merit of activated sludge models depends on the accuracy and reliability of the information they contain on the wastewater to be treated and the biochemical mechanisms involved. In most advanced calibration studies, respirometry i.e. the measurement of the oxygen utilization rate, (OUR), provides the majority of the required experimental database. However, currently used procedures still involve a number of basic and practical problems. Model evaluation of the OUR data may generate a distorted image of the processes involved. Hydrolysis is the most important, yet the most vulnerable process as far as the experimental assessment of accurate kinetic parameters is concerned. This study intends to provide an overview of major experimental limitations in the modeling of activated sludge, with emphasis on the appropriate experimental design for the assessment of the hydrolysis rate.

Calibration↗

PubMed2002

Effect of chemical treatment on soluble residual COD in textile wastewaters.

The effect of chemical treatment on the magnitude of soluble residual COD in the biological treatment effluent is investigated for knit fabric finishing wastewater. Bentonite is selected for its potential to remove soluble COD together with color and particulate components. Chemical treatment using bentonite, when applied prior to biological treatment removes around 40% of the biodegradable as well as soluble inert COD initially present in the wastewater. As a chemical post-treatment, it acts as a polishing step, removing particulate matter and a minor portion of around 20% of the remaining soluble COD. These findings suggest chemical pre-treatment as a better alternative for the optimization of soluble COD removal.

Bentonite↗

PubMed2002

In-plant control applications and their effect on treatability of a textile mill wastewater.

Water minimization and exploration of the potential for wastewater recovery and reuse are priority issues of industrial wastewater management. They are extremely significant for the textile industry commonly characterized with a high water demand. The study presents a detailed in-plant control survey for a wool finishing plant. A comprehensive process profile and wastewater characterization indicate that process water consumption can be reduced by 34%, and 23% of the wastewater volume can be recovered for reuse. Treatability of reusable wastewater fraction and the effect of in-plant control applications on effluent treatability were also investigated.

Conservation of Natural Resources↗

PubMed2002

Ozonation application in activated sludge systems for a textile mill effluent.

The study investigates the effect of partial ozonation of textile wastewater, both at the inlet (pre-ozonation) and the outlet (post-ozonation) of biological treatment, for the optimization of COD and color removals, both typical polluting parameters associated with the textile industry. Pre-ozonation provides at optimum contact time of 15 minutes 85% color removal, but only 19% COD reduction. Removal of the soluble inert COD fraction remains at 7%, indicating selective preference of ozone for simpler compounds. Post-ozonation is much more effective on the breakdown of refractory organic compounds and on color removal efficiency. Ozonation after biological treatment results in almost complete color removal and a 14% soluble inert COD reduction. The polishing effect of post-ozonation also proves quite attractive from an economical standpoint, involving approximately 50% of the ozone utilization at the same ozone flux rate and contact time, yet providing a lower soluble residual COD level.

Bioreactors↗

PubMed2002

Biological treatability of a corn wet mill effluent.

Corn wet mill effluents are studied in terms of their characteristics relevant for biological treatment. They have a high COD of mainly soluble and biodegradable nature, with practically no soluble inert components. They generate a relatively high level of soluble residual metabolic products, which affects the choice of the appropriate biological treatment and favors aerobic activated sludge process. Experimental assessment of process kinetics yields typical values. Hydrolysis of the slowly biodegradable COD, the rate limiting step for the utilization of substrate, is characterized by an overall rate coefficient, which is within the range commonly associated for the hydrolysis of starch.

Biodegradation, Environmental↗

PubMed2002

Experimental assessment and modelling of nitrate utilisation for primary sludge.

Electron acceptor utilisation potential of filtered primary sludge under anoxic conditions was experimentally investigated. Major kinetic and stoichiometric parameters were assessed by means of model evaluation of nitrate profile obtained in batch reactors. ASM1, modified for endogenous decay, and ASM3 were used for model simulation. Both models provided consistent interpretation of experimental data. ASM1 yielded mu(H) and Y(HD) values of 6.1 d(-1) and 0.64 g cell COD(g COD)(-1) respectively for heterotrophic anoxic growth. The corresponding storage mechanism associated with ASM3 could be characterised by a k(STO) of 13 g COD (g COD d)(-1) and a Y(STO) of 0.78 g COD(g COD)(-1). The high k(STO) value suggests re-evaluation of the concept of readily biodegradable substrate as defined in ASM3 and tested in the study.

Biodegradation, Environmental↗

PubMed2002

Respirometric assessment of storage yield for different substrates.

A new procedure has been defined for the respirometric assessment of bacterial storage yield as defined in the Activated Sludge Model No.3. The procedure was used to determine the storage yield, Y(STO), associated with acetate, glucose and domestic sewage, together with mixtures of acetate/glucose and acetate/domestic sewage at different initial F/M ratios. Y(STO) was calculated as 0.78 gCOD(gCOD)(-1) for acetate, 0.87 gCOD(gCOD)(-1) for glucose and 0.96 gCOD(gCOD)(-1) for domestic sewage. The Y(STO) of substrate mixtures was found to reflect the characteristics of the dominant fraction in the mixture.

Acetates↗

PubMed2002

Innovative technologies for wastewater treatment in coastal tourist areas.

The selection of appropriate wastewater treatment technologies for coastal tourist areas is important in the sense that they have to meet stringent effluent limits in a simple and easy to operate flow scheme. This paper outlines different effluent standards implemented in sensitive coastal areas and briefly discusses the merit of a number of innovative technologies, namely the sequencing batch reactor, the intermittent aeration process, the moving bed reactor and the biofim-filter-sequencing batch reactor system, either as a batch or continuous flow process applicable in these areas.

Biofilms↗

PubMed2002

Retrofitting activated sludge systems to intermittent aeration for nitrogen removal.

The paper provides the basis and the conceptual approach of applying process kinetics and modelling to the design of alternating activated sludge systems for retrofitting existing activated sludge plants to intermittent aeration for nitrogen removal. It shows the significant role of the two specific parameters, namely, the aerated fraction and the cycle time ratio on process performance through model simulations and proposes a way to incorporate them into a design procedure using process stoichiometry and mass balance. It illustrates the effect of these parameters, together with the sludge age, in establishing the balance between the denitrification potential and the available nitrogen created in the anoxic/aerobic sequences of system operation.

Bioreactors↗

PubMed2002

Design of SBR systems for nutrient removal from wastewaters subject to seasonal fluctuations.

Designing SBR systems for simultaneous biological nitrogen and phosphorus removal is evaluated and defined for wastewaters from small coastal areas subject to seasonal fluctuations in quantity and quality. A design procedure is developed using basic process stoichiometry and significant operating parameters. A stepwise approach was utilized to secure full nitrification, available nitrate limitation for denitrification, a mixed phase with enough anaerobic fraction for P removal. A fundamental relationship between the effective sludge age, the recycle ratio and the cycle time was developed and used for the determination of physical design parameters.

Bioreactors↗

PubMed2002

Sequencing batch reactor treatment of tannery wastewater for carbon and nitrogen removal.

The paper evaluates the organic carbon and nitrogen removal performance of the sequencing batch reactor (SBR), technology for tannery wastewater. For this purpose, a pilot-scale SBR was installed on site to treat the plain-sealed tannery effluent. The study involved wastewater characterization, start-up and operation of the reactor for carbon and nitrogen removal and model evaluation of system performance. Its removal efficiency was compared with that of the existing continuous-flow activated sludge system providing full treatment to wastewater from the Istanbul Tannery Organized Industrial District.

Bioreactors↗

PubMed2002

Assessment of the denitrification potential for biological nutrient removal processes using OUR/NUR measurements.

The denitrification potential, a key parameter in nutrient removal activated sludge systems, is mathematically described in terms of mass balance expressions for different carbon sources, namely, easily biodegradable substrate, slowly biodegradable substrate and biomass. Mass balance was derived both for single-anoxic (pre-denitrification) and dual anoxic (Bardenpho) systems. Correction factors for anoxic growth were experimentally determined using respirometry for domestic sewage and meat processing wastewater. The denitrification potential expressions were evaluated for different process configurations such as pre-denitrification, Bardenpho process and University of Cape Town (UCT) process.

Biodegradation, Environmental↗

PubMed2001

The mechanism and design of sequencing batch reactor systems for nutrient removal--the state of the art.

The Sequencing Batch Reactor (SBR) process for carbon and nutrient removal is subject to extensive research, and it is finding a wider application in full-scale installations. Despite the growing popularity, however, a widely accepted approach to process analysis and modeling, a unified design basis, and even a common terminology are still lacking; this situation is now regarded as the major obstacle hindering broader practical application of the SBR. In this paper a rational dimensioning approach is proposed for nutrient removal SBRs based on scientific information on process stoichiometry and modelling, also emphasizing practical constraints in design and operation.

Biodegradation, Environmental↗

PubMed2001

A scientific approach to wastewater recovery and reuse in the textile industry.

Wastewater recovery and reuse in industries requires all the basic steps of quality management. It should involve a comprehensive in plant survey of processes with wastewater generation, identification of recoverable streams, and treatment requirements for reuse. It should equally undertake evaluation of wastewater quality remaining after segregation of the recovered portion, with specific emphasis on technological implications of appropriate treatment and compliance with effluent limitations. In this study, all these factors were experimentally assessed and evaluated for a knit fabric processing textile plant.

Biodegradation, Environmental↗

PubMed2001

Retrofitting SBR systems to nutrient removal in sensitive tourist areas.

Retrofitting of existing SBR systems for nutrient removal is evaluated and defined for small communities in sensitive coastal areas, with seasonal fluctuations in wastewater quantity and quality. The proposed approach is developed by means of basic process stoichiometry and verified using ASM2d. The efficiency of retrofitting is found to rely on the delicate balance between the overall sludge age, the initial settled sludge volume in the reactor, and the ratio of the initial volume to the feed volume in each cycle, a parameter corresponding to the recycle ratio in continuous systems.

Bioreactors↗

PubMed1997

Characterization and COD fractionation of domestic wastewaters.

Results of a comprehensive study are reported for wastewater characterization in relation to modelling and design of biological nutrient removal systems for the Metropolitan Area of Istanbul. Domestic sewage quality was experimentally assessed in terms of major polluting parameters. Size distribution and calculation of significant ratios such as BOD5:COD and COD:N were used to evaluate the merit of candidate physical, chemical and biological treatment alternatives. COD fractionation was effected to assess biological treatability and to yield the necessary process components to the recent modelling approaches.

Journal Article↗

PubMed1994

Wastewater management for Istanbul: basis for treatment and disposal.

A number of studies have so far been conducted to assess the magnitude of pollution generated by domestic and industrial sources in the Istanbul Metropolitan Area. They indicate that a management scheme for wastewater treatment and disposal should involve a total discharge of 15.4 m3 s(-1) with a potential pollution load of 330 tons BOD5 day(-1) for 1990. A scheme of this magnitude inevitably requires careful evaluation of receiving water characteristics, both from an oceanographic and a quality standpoint. In this paper significant water quality parameters related to the Black Sea-Bosphorus Strait-Marmara Sea System are reviewed and incorporated in the evaluation of treatment and disposal alternatives. In this context, the pollution exchange between the Mamara Sea and Bosphorus is quantified, pollutant contents of the Mamara Sea and discharges from the Istanbul Metropolitan Area are compared, and a number of scenarios are evaluated to define the optimum treatment and disposal strategy.

Journal Article↗