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This study investigates the effect of hypochloride application for controlling bulking and foaming on the microbial ecology of an activated sludge system treating tannery wastewater. Detailed characterization of the wastewater treatment influent and effluent is also reported for the study period. During the study, bulking and foaming are first monitored with a sudden burst in the sludge volume index over 250 mL g(-1), creating a significant deterioration of the effluent quality. The corresponding upset in the microbial ecology is the combined excessive proliferation of M. parvicella, N. limicola II and Gordona (Nocardia) spp., but mainly triggered by Gordona contamination of the floc structure and the rapid outward growth of this filamentous microorganism extending to adjacent flocs. Chlorine application at an average rate of 3 g Cl(-1)(kg MLSS.day)(-1) for 12 days provide an effective solution for bulking and foaming, restoring the effluent quality. It destroys filamentous texture between the flocs, leaving only a lot of loose and chopped filament fragments and, totally removes the Gordona spp. from solution which retrieves back into the flocs. Therefore, chlorine remediation of bulking and foaming, although temporarily effective, is only superficial as the Gordona seeding inside the floc remains intact and potentially available for excessive growth in the next favorable conditions.

The chemical treatability of wastewaters generated from a textile manufacturing plant performing wool, polyester, wool-polyester blends, woven fabric as well as yarn dyeing and finishing operations was investigated. Coagulation and flocculation experiments were conducted with alum, sodium bentonite and iron salts on wastewaters collected from both the fabric finishing line, after being subjected to in-plant control measures covering water conservation practices and segregation of reusable streams, and dyeing line. The effect of optimum treatment alternatives on the chemical oxygen demand (COD) values of different molecular weight cut-off fractions was also examined.

This paper explores the merit of the oxygen uptake rate (OUR) profile obtained by means of respirometry as the basic mechanistic instrument for evaluating activated sludge inhibition. Experimental OUR data are generated using the synthetic peptone-based substrate and inhibition is tested with 60 mg/L hexavalent chromium and 33 mg/L nickel additions, corresponding to EC50 levels determined using the standard ISO 8192 procedure. Experimental results are evaluated by model calibration using ASM1 modified for dual hydrolysis and ASM3 modified for simultaneous growth. Model evaluations indicate that inhibition affects not only growth, but also other significant microbial mechanisms such as substrate storage and hydrolysis, leading to conclude that the proposed approach will enable to visualize the overall impact of the inhibitory compound on every stage of substrate biodegradation, through inspection and evaluation of the entire OUR profile.

Distribution and occurrence of Archaea and methanogenic activity in a laboratory scale, completely mixed anaerobic reactor treating pharmaceutical wastewaters were investigated and associated with reactor performance. The reactor was initially seeded with anaerobic digester sludge from an alcohol distillery wastewater treatment plant and was subjected to a three step feeding strategy. The feeding procedure involved gradual transition from a glucose containing feed to a solvent stripped pharmaceutical wastewater and then raw pharmaceutical wastewater. During the start-up period, over 90% COD removal efficiency at an organic loading rate (OLR) of 6 kg COD m(-3)d(-1) was achieved with glucose feeding, and acetoclastic methanogenic activity was 336 ml CH4 gTVS(-1)d(-1). At the end of the primary loading, when the feed contained solvent stripped pharmaceutical wastewater at full composition, 71% soluble COD removal efficiency was obtained and acetoclastic methanogenic activity decreased to half of the rate under glucose feed (166 ml CH4 gTVS(-1)d(-1)). At the end of secondary loading with 60% (w/v) raw pharmaceutical wastewater, COD removal dropped to zero and acetoclastic methanogenic activity fell to less than 10 ml CH4 gTVS(-1)d(-1). Throughout the course of the experiment, microbial community structure was monitored by DGGE analysis of 16S rRNA gene fragments. Five different archaeal taxa were identified and the predominant archaeal sequences belonged to methanogenic Archaea. Two of these showed greatest sequence identity with Methanobacterium formicicum and Methanosaeta concilii. The types of Archaea present changed little in response to changing feed composition but the relative contribution of different organisms identified in the archaeal DGGE profiles did change.

This study involves a comprehensive survey of the microbial ecology of the activated sludge process treating tannery wastewater, emphasizing evaluation during periods of bulking and foaming. The survey also includes a detailed characterization of process influent and effluent. Observations always associate bulking with significant increase in protozoa species and rotifers, but decrease or disappearance of nematodes. Activated sludge sustained under normal conditions with a sludge volume index lower than 80 ml g(-1), exhibits all the properties of a compact and healthy zoogleal floc structure. Three types of filamentous bacteria prevail in the microscopic examinations. Two of the filamentous bacteria, Microthrix parvicella and Nostocoida limicola II, always appear as components of the floc structure under normal conditions and abundant or even excessive levels. The study identifies Gordona spp. as the main microorganism responsible for bulking and foaming, which starts by a Gordona contamination process inside the floc, later branching out and extending through adjacent flocs. When completed, this process increases sludge volume index values to over 200 ml g(-1). Microscopic examinations indicate significant morphological differences between filamentous microorganisms observed in this study and reported in the literature mostly for domestic sewage treatment.

In the present study, oxidative pre-treatment of pharmaceutical wastewater originating from the formulation of the penicillin Sultamycillin Tosylate Diydrate via ozonation at varying pH and ozone feed rates was investigated. Biological treatability studies were performed with a synthetic wastewater alone and supplemented with raw and ozonated penicillin formulation effluents. The highest COD (34%) and TOC (24%) removal efficiencies were obtained at pH 11.0, whereas the BOD5 value increased from 16 mg l(-1) to 128 mg l(-1) after 40 min of ozonation, corresponding to an applied ozone dose of 1670 mg l(-1) and 33% relative ozone absorption. The studies showed that no degradation of raw penicillin fraction (30% of total COD) occurred, and degradation of the synthetic wastewater being completely treatable without penicillin addition, was inhibited by 7%. Upon 40 min ozonation, the synthetic wastewater could be completely oxidized and at the same time 35% of ozonated penicillin wastewater removal was obtained. Respirometric studies were conducted in parallel and produced results indicating a 22% decrease in the total oxygen consumption rate established for raw penicillin formulation effluent compared to the results obtained from the aerobic batch reactor. No inhibition of the synthetic fraction was observed for the 40 min-ozonated penicillin formulation effluent, biodegradability of the 60 min-ozonated penicillin effluent decreased possibly due to recalcitrant oxidation product accumulation. The modeling study provided experimental support and information on inhibition kinetics in activated sludge model no. 3 (ASM3) by means of respirometric tests for the first time.

The study is focused on defining a conceptual approach for the design of activated sludge systems treating strong wastewater for nitrogen removal. The effect of major factors such as COD/N ratio, denitrification potential, available nitrate, anoxic volume fraction, and recycle ratio is evaluated in terms of basic stoichiometry. An algorithm for appropriate design is developed for a continuous flow activated sludge and sequencing batch reactor, both operated in a pre-denitrification mode. The design approach is tested for two types of strong industrial wastewaters with different N contents and COD/N ratios and a typical domestic sewage for comparative evaluation.

This study evaluates the feasibility of water minimization and wastewater reuse for a wool finishing textile mill. The evaluation process is based upon a detailed analysis on water use, process profile and wastewater characterization, indicating a potential for 34% reduction in water consumption and for 23% of wastewater recovery for reuse. Wastewater reuse requires treatment and results in a remaining wastewater stream with stronger character and consequently more costly to treat. The feasibility includes technical considerations for appropriate treatment alternatives and related cost factors for water consumption, treatment for reuse and for discharge either to sewer or to receiving media.

Stringent standards for nitrogen discharge necessitate the implementation of new systems for the sustainable removal of ammonium from wastewater. One of such systems is based on the process of anaerobic ammonium oxidation (Anammox), which is a new powerful tool especially for strong nitrogenous wastewaters. In this study, the Anammox process performance was tested with synthetic wastewater in a completely stirred tank reactor (CSTR). The reactor was operated for 511 days and fed with increasing amounts of ammonium and nitrite. In this period, an increase of ammonium and nitrite utilization rates were observed as a result of the increase of nitrogen loads in the influent. After 272 days, about 60% of the biomass was removed from the reactor and the system was restarted. Throughout 511 days 90% of the ammonium and more than 99% of the nitrite were converted mainly to dinitrogen (N2) and nitrate. The microbial community in the reactor was characterized with Fluorescence in situ Hybridization (FISH). The study showed that the population in the reactor was dominated by the deep-branching planctomycete Candidatus "Brocadia anammoxidans" strain Dokhaven 2.

The study explores the impact of ozonation on the fate of different soluble COD fractions in the tannery wastewater at different phases during the course of biological treatment, in order to identify the phase where ozonation is likely to generate the maximum beneficial effect on biological treatability. Samples from the biological treatment influent and from the mixed liquor at periods significant for the fate of COD fractions have been ozonated. Ozone treatment at the phase where the readily biodegradable COD component was biologically depleted is determined as the most promising alternative among others, since the highest COD removal efficiencies are achieved even with low feeding time of 5 min at the selected ozone flow-rate of 42.8 mg min. The merit of ozonation at this stage in the formation of simpler more biodegradable compounds deserves further attention.

This paper proposes a new metabolic model for acetate uptake by a mixed culture of phosphate- and glycogen-accumulating organisms (PAOs and GAOs) under anaerobic conditions. The model uses variable overall stoichiometry based on the assumption that PAOs may have the ability of using the glyoxylate pathway to produce the required reducing power for polyhydroxyalkonate (PHA) synthesis. The proposed model was tested and verified by experimental results. A sequencing batch reactor system was operated for enhanced biological phosphorus removal (EBPR) with acetate as the sole carbon source at different influent acetate/phosphate ratios. The resulting experimental data supported the validity of the proposed model, indicating the presence of GAOs for all tested HAc/P ratios, especially under P-limiting conditions. Strong agreement is observed between experimental values and model predictions for all model components, namely, PHB production, PHA composition, glycogen utilization, and P release., (Copyright 2003 Wiley Periodicals, Inc.)

To help confirm and interpret the Enhanced Biological Phosphorus Removal (EBPR) performance of the microbial populations in a laboratory-scale activated sludge (AS) system, conventional microscopic examinations were carried out. A lab-scale sequencing batch reactor (SBR), named ARC, was fed with acetate, as the sole carbon source, and operated for EBPR. Daily monitoring and cyclic behavior evaluation studies indicated that the system always worked for EBPR in the long run, with efficiencies depending on the influent characteristics and operational stability. Poly-P and PHB-staining experiments revealed that the enriched biomass of the reactor was quite diverse in terms of morphology, hosting populations of traditional rod-shaped PAOs, tetrad/sarcina-like cells (referred here as TFOs, rather than GAOs), diplococci-shaped cells, and staphylococci-like clustered populations, in addition to few filaments. Although the microscopic observations were qualitative, rather than quantitative, they seemed likely to correlate well to the biochemical performance of the reactor.

Availability of water to the industry often becomes prohibitive, both in terms of quality and cost, in coastal areas. This study takes the textile industry and evaluates the prerequisites of water recovery and reuse. In this context, a large spectrum are studied for their water, the general quality of wastewater generated, quality and treatability of reuse wastewater streams, and expected changes in the overall effluent quality after segregation of the recovery wastewater portion.

Enhanced biological phosphorus removal (EBPR) requires an anaerobic-aerobic sequence and short chain fatty acids, namely acetate. It is also known that the presence of nitrate in the anaerobic phase inhibits EBPR. This study describes a lab-scale experimentation carried out to study the effect of different substrates on EBPR and behaviour of PAOs under anoxic conditions in a sequencing batch reactor operated using synthetic wastewater. Experimental data show that the EBPR performance is significantly affected by glucose rich influent. Low COD/TKN ratios caused lower phosphorus removal performance since nitrate entering the anaerobic zone consumes substrate for denitrification. The results also show that anoxic phosphate uptake took place together with nitrate reduction when there was no external substrate. However, the uptake rate under anoxic conditions was lower than that under aerobic conditions.

Water Framework Directive aiming to maintain and improve the aquatic environment in the EU was launched by the European Parliament in 2000. According to this directive, control of quantity is an ancillary element in securing good water quality and therefore measures on quantity, serving the objective of ensuring good quality should also be established. Accordingly, it is a comprehensive and coordinated package that will ensure all European waters to be protected according to a common standard. Therefore, it refers to all other Directives related to water resources management such as Urban Wastewater Treatment Directive Nitrates Directive, Drinking Water Directive, Integrated Pollution Prevention Control etc. Turkey, as a candidate state targeting full-membership, should comply the necessary preparations for the implementation of the "Water Framework Directive" as soon as possible. In this study, the necessary legislative, political, institutional, and technical attempts of the pre-accession countries have been discussed and effective recommendations have been offered for future activities in Turkey.

A laboratory-scale sequencing batch reactor was started-up with flocculated biomass and operated primarily for enhanced biological phosphate removal. Ten weeks after the start-up, gradual formation of granular sludge was observed. The compact biomass structure allowed halving the settling time, the initial reactor volume, and doubling the influent COD concentration. Continued operation confirmed the possibility of maintaining a stable granular biomass with a sludge volume index less than 40 ml g-1, while securing a removal efficiency of 95% for carbon, 99.6% for phosphate, and 71% for nitrogen. Microscopic observations revealed a morphological diversity.

This paper covers an evaluation of more than twenty full-scale industrial wastewater treatment plants employing sequencing batch reactor (SBR) process mainly for carbon removal and a pilot-scale SBR designed for carbon and nitrogen removal from tannery effluent. The study highlights the major features of the SBR technology and proposes a rational dimensioning approach for carbon and nitrogen removal SBRs treating high strength industrial wastewaters based on scientific information on process stoichiometry and modeling, also emphasizing practical constraints in design and operation.