PubMed Health⌕ Search

Biomedical subjects

J A Oleszkiewicz

Publications and source records attributed to J A Oleszkiewicz.

15 recordsLinked to original sources
PubMed2007

Hydrogen-dependent denitrification of water in an anaerobic submerged membrane bioreactor coupled with a novel hydrogen delivery system.

Hydrogen-dependent denitrification has gained significant attention due to its potential economic advantage over heterotrophic denitrification. However, effective hydrogen delivery and biomass retention under anaerobic conditions are significant challenges to implementation of this process. An innovative hydrogenotrophic denitrification system, that addresses these challenges, consisting of an anaerobic submerged membrane bioreactor (MBR) and a novel hydrogen delivery unit, was evaluated for removal of nitrate from a synthetic groundwater feed. The hydrogen delivery unit was designed to release hydrogen-supersaturated water to the reactor and was efficient in hydrogen delivery, providing complete mass transfer. The anaerobic submerged MBR was successful in both reducing nitrate from 25 mg NO(3)-Nl(-1) to below detection and separating biomass from treated water to produce effluent free of suspended solids. Nitrogen gas produced during denitrification was internally recycled to effectively achieve membrane scouring and reactor mixing. The total organic carbon was similar to that of the incoming feed water, averaging approximately 6 mgl(-1).

Anaerobiosis↗
PubMed2006

Extracellular polymers in partly ozonated return activated sludge: impact on flocculation and dewaterability.

The purpose of this study was to evaluate the influence of partial ozonation of return activated sludge on settling properties and dewaterability of sludge. Sequencing batch reactors with two sets of aerobic and alternating anoxic/aerobic conditions were used. In each set, one reactor served as a control and the other was subject to the ozone treatment (doses in the range of 0.016-0.080 mg O3/mg TSS of initial excess sludge). The level of total suspended solids (TSS) in each reactor was controlled at 1,800 mg/l. To evaluate settleability and dewaterability, settling kinetic studies, sludge volume index (SVI) and capillary suction time test (CST) were used. For extraction and quantifying sludge biopolymers, thermal-ethanolic extraction was employed. The ratio of bound-to-total extracellular polymer substances (EPS) was higher for the strictly aerobic reactor than for the alternating anoxic/aerobic one, indicating the stronger structure of the aerobic flocs. After ozone treatment, the fraction of bound EPS was released and solubilized, increasing soluble EPS. Increased apparent food-to-microorganism (F/M) ratio favoured production of EPS in ozonated reactors, enhancing flocculation, which had potential to improve settling. Dewaterability, measured by CST test, was better in alternating anoxic/aerobic reactors than in aerobic ones, indicating that incorporation of an anoxic zone for biological nutrient removal leads to improvement in sludge dewatering. The negative impact of ozonation on dewaterability was minimal in terms of the long-term operation.

Aerobiosis↗
PubMed2005

Kinetics of hydrogen-dependent denitrification under varying pH and temperature conditions.

It is important to determine the effect of changing environmental conditions on the microbial kinetics for design and modeling of biological treatment processes. In this research, the kinetics of nitrate and nitrite reduction by autotrophic hydrogen-dependent denitrifying bacteria and the possible role of acetogens were studied in two sequencing batch reactors (SBR) under varying pH and temperature conditions. A zero order kinetic model was proposed for nitrate and nitrite reduction and kinetic coefficients were obtained at two temperatures (25 +/- 1 and 12 +/- 1 degrees C), and pH ranging from 7 to 9.5. Nitrate and nitrite reduction was inhibited at pH of 7 at both temperatures of 12 +/- 1 and 25 +/- 1 degrees C. The optimum pH conditions for nitrate and nitrite reduction were 9.5 at 25 +/- 1 degrees C and 8.5 at 12 +/- 1 degrees C. Nitrate and nitrite reduction rates were compared, when they were used separately as the sole electron acceptor. It was shown that nitrite reduction rates consistently exceeded nitrate reduction rates, regardless of temperature and pH. The observed transitional accumulation of nitrite, when nitrate was used as an electron acceptor, indicated that nitrite reduction was slowed down by the presence of nitrate. No activity of acetogenic bacteria was observed in the hydrogenotrophic biomass and no residual acetate was detected, verifying that the kinetic parameters obtained were not influenced by heterotrophic denitrification and accurately represented autotrophic activity.

Bacteria↗
PubMed2005

Effect of sulfidogenic and methanogenic inhibitors on reductive dehalogenation of 2-chlorophenol.

The potential for reductive dehalogenation of 2-CP in anaerobic batch cultures of fresh-water digested sludge under sulfidogenic and methanogenic conditions was investigated in the presence or absence of respective inhibitors: molybdate and BESA at various concentrations (0 to 10 mM). Triplicate cultures (50% vol/vol) were set-up under an atmosphere of 20% CO2 and 80% N2 in 160 ml serum bottles using anaerobic digester sludge and a mineral medium containing 0.1% yeast extract. The dehalogenation of 2-CP, as well as methanogenesis, occurred at the same rate in the presence or absence of sulphate. Sulphate reduction did not inhibit 2-CP degrading populations. The presence of BESA--a known inhibitor of methane producers partially inhibited methanogenesis and slowed 2-CP dehalogenation at even 1 mM concentration with phenol and acetate accumulation in the cultures. The accumulation was proportional to the increase in concentration of BESA in the system. Molybdate on the other hand completely inhibited both sulphate reduction and 2-CP dehalogenation at a concentration of 10 mM. The dehalogenation of 2-CP continued in the presence of 1 mM molybdate even after the cessation of sulphate reduction indicating that sulphate-reducing bacteria were not directly involved in the dehalogenation of 2-CP in this study. Inhibition of 2-CP dehalogenation and sulphate reduction along with accumulation of propionate at 10 mM molybdate in the cultures strongly suggests that the dehalogenation of 2-CP was more directly linked to syntrophic activity of the mixed culture compared to sulphate reduction.

Anaerobiosis↗
PubMed2005

Incorporating membrane gas diffusion into a membrane bioreactor for hydrogenotrophic denitrification of groundwater.

A hydrogenotrophic denitrification system, comprising a suspended growth membrane bioreactor (MBR) with membrane hydrogen gas diffusion, was developed to remove nitrate from groundwater. A hollow fiber gas permeable membrane module was designed for hydrogen delivery and a commercially available hollow fiber membrane module was used for solid/liquid separation. The MBR was operated at an SRT of 20 days and at room temperature. Four nitrate loading rates of 24, 48, 96 and 192 NO3(-)-N mg I(-1) d(-1) were applied to the system. As the nitrate loading was raised, pH increased due to increased denitrification and release of OH- ions. The oxidation reduction potential (ORP) remained fairly stable when full denitrification was achieved, but increased when nitrate loading rates reached 192 NO3(-)-N mg I(-1) d(-1) and residual nitrate was present in the reactor. Nitrate removal was complete (100%) in the first three nitrate loadings and 72% in the system with 192 NO3(-)-N mg I(-1) d(-1). Nitrate utilization rates of 30.6, 23.4, and 37.7 g NO3(-)-N m(-3) d(-1) were achieved in the first three loadings. Average effluent dissolved organic carbon (DOC) concentration of approximately 8 mg l(-1) was observed in all four nitrate loading regimes, possibly owing to the generation and release of soluble microbial bi-products (SMP).

Bioreactors↗
PubMed2005

Hydrogen-dependent denitrification in an alternating anoxic-aerobic SBR membrane bioreactor.

A novel hydrogenotrophic denitrification system, which consisted of a sequencing batch membrane bioreactor, was evaluated for simultaneous removal of nitrate and soluble microbial products (SMP) from a synthetic groundwater feed. A hollow fiber membrane diffuser was used for bubble-less diffusion of hydrogen into the bioreactor under anoxic condition followed by aerobic SMP removal and biomass filtration. During the anoxic period, the nitrate loading of 0.328 kg N m(-3) d(-1) was completely denitrified to below detectable levels. A denitrification rate of 0.8 kg N m(-3) d(-1) was obtained at steady state biomass concentrations of 1,162 mg I(-1). During the aerobic period when biomass filtration was performed, 81% of SMP produced within the anoxic phase was retained by the membrane, 9% was biologically removed, 5% was passed through the membrane and 5% was discharged during the wasting of mixed liquor. The aerobic cycle was instrumental as it allowed for effective biomass filtration via membrane scouring and assisted in further reduction of effluent organic matter.

Bacteria, Aerobic↗
PubMed2004

Impacts of reduced sulfur components on active and resting ammonia oxidizers.

While there has been significant research on the nature and extent of the impact of inhibitory reduced sulfur with respect to anaerobic (e.g., methanogenic and sulfidogenic) microbial systems, only limited study has yet been conducted on the comparable effects of soluble sulfides which might occur within aerobic wastewater treatment systems. Admittedly, aerobic reactors would not normally be considered conducive to the presence of reduced sulfur constituents, but there do appear to be a number of processing scenarios under which related impacts could develop, particularly for sensitive reactions like nitrification. Indeed, the following scenarios might well involve elevated levels of reduced sulfur within an aerobic reactor environment: (1) mixed liquor recycle back through sulfide-generating anaerobic zones (e.g., in conjunction with biological nutrient removal processes, etc.), (2) high-level side-stream sulfide recycle via sludge digestion, etc., back to aerobic reactors, and (3) high-level influent sulfide inputs to wastewater treatment facilities via specific industrial, septage, etc., streams. The objective of this study was, therefore, to determine the subsequent metabolic impact of soluble sulfide under aerated and unaerated conditions, focusing in particular on ammonia-oxidizing bacteria due to their critical first-step role with nitrification. The obtained results indicated that, under catabolically active conditions, cultures of ammonia oxidizers were extremely sensitive to the presence of sulfide. At total soluble sulfide concentrations of 0.25 mg l(-1) S, active ammonia oxidation was completely inhibited. However, immediately following the removal of this soluble sulfide presence, ammonia oxidation started to recover; and it continued to improve over the next 24 h. Similar sulfide impact tests conducted with inactive ammonia oxidizers exposed during anaerobic conditions, albeit at higher dosage levels, also revealed that their subsequent aerobic activity would correspondingly be retarded. These results indicated that, after sulfide exposure under unaerated conditions, subsequent aerobic oxidative activity rates rapidly decreased as the soluble sulfide exposure was increased from 0.5 gm l(-1) S to 5 mg l(-1) S and that further reductions in this activity progressively developed as the concentration was increased to 200 mg l(-1) S. The recovery following unaerated exposure to sulfide was significantly higher at pH 7, as compared with pH 8, and although the specific nature of this variation was not established, a hypothetical explanation appeared warranted.

Aerobiosis↗
PubMed2004

Bioaugmentation for nitrification at cold temperatures.

Bioaugmentation of nitrifying bacteria for short solids retention time (short-SRT) nitrification is an attractive alternative for wastewater treatment plants in cold climates or for those in the process of upgrading to include nitrification. One possible source of ammonia for the production of nitrifying bacteria is the liquor generated during the dewatering of anaerobically digested sludges. The objectives of this study was to determine the impact of sudden decrease in temperature on nitrification rates and to determine if nitrification could be accomplished in sequencing batch reactors (SBRs) at 10 degrees C by seeding nitrifying bacteria acclimated to 20 degrees C. In this research, biomass produced during warm nitrification of dewatering liquor was seeded into cold SBRs at various hydraulic retention times from 43.3 to 96 h. The average decreases in nitrification rates were 58%, 71% and 82% for biomass cooled to 10 degrees C when the biomass was acclimated to 20 degrees C, 25 degrees C and 30 degrees C, respectively. The seeded SRTs of the cold SBRs were raised above the minimum solids retention time (SRT(min)) required for nitrification. Full ammonia nitrogen removal was achieved in cold SBRs that were operated at an apparent SRT less than SRT(min).

Bacteria, Anaerobic↗
PubMed2004

Endocrine disrupting compounds (EDC) in municipal wastewater treatment: a need for mass balance.

Increasing attention has been focused on endocrine disrupting compounds (EDCs) as pollutants in municipal wastewater. Recent studies have shown that these compounds can have a negative impact on the environment, and that in many cases they are not efficiently removed in wastewater treatment plants (WWTPs). Studies have also revealed that their destruction and transport out into the environment depend on the design and operational characteristics of these treatment systems and on the properties of the chemicals themselves. This paper reviews the current knowledge on EDCs, natural and synthetic hormones including estrone (E1), 17beta-estradiol (E2), and 17alpha-ethinylestradiol (EE2) in WWTP. Several key data gaps are addressed when assessing the removal of EDCs in WWTPs. First, analytical methods used by most researchers do not account for the inactive or conjugated form of the compounds, yet they can become deconjugated to active forms during treatment, leading to an additional source of contaminant load. Next, insufficient measurements are made at various stages within the WWTP preventing adequate analyses on how each u nit process contributes to degradation. Currently, there is no standardized procedure for assessing degradation of EDCs in WWTPs, and it is often difficult to compare published data generated by individual test protocols. This paper identifies streams that should be sampled in WWTPs and suggests a mass balance approach that takes into account all forms of the compound in both liquid and solid phases. Issues of potential concern in performing mass balances are discussed leading to a proposal of variables that should be analyzed and included in published articles. The adoption of similar methods by researchers in future work will produce a better picture of the presence and fate of these compounds in the environment.

Adsorption↗
PubMed2004

Bench-scale assessment of the effectiveness of an anaerobic selector in controlling filamentous bulking.

A laboratory scale sequencing batch reactor (SBR) was used to assess the ability of an anaerobic selector to control filamentous growth in an activated sludge plant experiencing bulking problems. The SBR was operated under a sequence of 60 min anaerobic followed by 120 min of aerobic period at 20 degrees C, with a total solids retention time (SRT) of 4 d and a hydraulic retention time (HRT) of 8 h. The apparent soluble organic carbon (SOC) removal from the liquid phase averaged 18% during the anaerobic period, which is significantly less than the 80-90% removal generally considered to be required to suppress the growth of filamentous bacteria. The anaerobic selector was, however, able to control sludge bulking, resulting in an average sludge volume index (SVI) below 140 ml g(-1). The true amount of the SOC uptake was masked by simultaneous hydrolysis of particulate organic matter during the anaerobic period, a process which should be considered in future studies and comparisons.

Bacteria, Anaerobic↗
PubMed2004

Feasibility studies and pre-design simulation of Warsaw's new wastewater treatment plant.

The proposed transfer of wastewater from the western part of Warsaw, across the Wisla (Vistula) River for joint treatment at the existing eastern side "Czajka" wastewater treatment plant (WWTP) will result in combined winter flows of approx. 580,000 m3 d(-1). One-year of pilot-scale studies defined the COD characteristics and kinetics of nitrogen removal and VFA production from primary sludge. BioWin simulation was used to size and price the optional processes and pointed to the Westbank process as the most cost-effective. The process consists of a sequence of a RAS pre-denitrification zone followed by an anaerobic, anoxic and aerobic zone. Some 100-150 t d(-1) of 10% methanol would be needed to remove 2-4 mg l(-1) of NO3-N above the recommended effluent level TN = 10 mg l(-1). Applying the principle of annual average 80% TN removal, and allowing for use of daily composite samples (rather than grab) could annually save the municipality over 1.5 million Euro on external carbon source.

Bioreactors↗
PubMed2003

Effects of predation and ORP conditions on the performance of nitrifiers in activated sludge systems.

Effects of changing oxidation-reduction potential (ORP) and grazing of protozoa on nitrifiers in activated sludge systems was investigated. This study used sequencing batch reactors which were acclimated under aerobic and alternating anoxic/aerobic conditions, with and without inhibition of protozoa, the predatory microorganisms. The feed used was a synthetic wastewater containing beef and yeast extracts as a carbon source. It was found that the biomass, determined by mixed liquor volatile suspended solids (MLVSS) in the reactors, was significantly affected by predation while ORP (aerobic and alternating anoxic/aerobic conditions) has no impact on the MLVSS regardless of the presence or absence of predation. However, the nitrification rates in the reactors show completely different trends indicating that the ORP of the system has a significant impact on the rates while predation does not. It was found that nitrification rates in alternating reactors were almost double the rates in the aerobic reactors, both with and without predatory inhibition. The decay rate of autotrophic bacteria (b(A)) in aerobic reactors was determined by tracking the decrease of the maximum nitrification rate under both anoxic and aerobic starvation conditions. The b(A) in alternating anoxic/aerobic reactors was also determined under alternating starvation conditions. It was found that, in any case, the alternating anoxic/aerobic autotrophic biomass b(A) was much smaller that the b(A) of aerobic biomass determined under aerobic and anoxic starvation conditions. The alternating anoxic/aerobic b(A) was 62.1% less than the aerobic biomass b(A) under aerobic starvation and 40.2% less for the aerobic biomass starved under anoxic conditions. No statistically significant differences in b(A) were observed between reactors with or without the inhibition of predators.

Animals↗
PubMed2003

Impact of landfill leachate on anaerobic digestion of sewage sludge.

The feasibility of mesophilic anaerobic co-digestion of landfill leachate and sewage sludge was examined in a bench-scale experiment. Three complete-mix, flow-through digesters were operated in a semi-continuous mode. During both phases of research all digesters received 500 ml d(-1) of raw sludge and Reactor 1 was always the control reactor--fed sludge only. During Phase 1, leachate volumes less than 12% of the sludge volume were fed to Reactors 2 and 3. During Phase 2 larger amounts of leachate were added, exceeding 20% of sludge volume which led to an overall decrease in the hydraulic residence time of the digesters. All reactors achieved stable operation, which indicated that the co-digestion of sewage sludge and landfill leachate is feasible During Phase 1, an increase in the average daily methane production from 2.5 l d(-1) to 3.1 l d(-1) and 3.2 l d(-1) was observed; the biomethanation production (BMP) increased from 0.46 to 0.6 m3 - 0.7 m3 CH4 (kg VS rem.)(-1). The average volatile solids reduction (VSR) increased from 46.1% to 48.6% and 49.0%. In Phase 2, the total methane production in the control reactor was significantly higher, at 4.6 l d(-1), while the addition of larger, by volume, amounts of leachate, decreased the methane production to 4.3 l d(-1) and 4.2 l d(-1), respectively. The average BMP values were 0.8, 0.87, and 0.81 m3 CH4 (kg VS rem.)(-1), respectively. In Phase 2, leachate addition decreased the average VSR from 51% to 49% and 45.6%. After calculating that leachate addition to digesters would not increase heavy metal concentrations in the produced biosolids it was concluded that mesophilic anaerobic co-digestion of sewage sludge and landfill leachate is feasible, and provides a promising alternative to aerobic co-treatment.

Bacteria, Anaerobic↗
PubMed2002

Co-processing of organic fraction of municipal solid waste and primary sludge--stabilization and disinfection.

Batch mesophilic digesters were fed a mixture of the organic fraction of municipal solid waste (OF-MSW) and primary sludge (PS), and operated under non-mixing condition at a 30-day influent mass retention time. The reactors were started in a slurry mode and brought to the target level of 26-30% total solids in about 3 months from start. Two feed characteristics, the level of PS solids in the feed, and the particle size of the OF-MSW, were the variables used to determine their effect on methane production during digester operation. Higher biodegradable volatile solid reductions and methane yields matched increased fractions of primary sludge in the feed (5%, 10%, and 15% as dry solids). Incomplete digestion, limited to fermentation, took place in reactors that did not receive primary sludge. The particle size did not have any effect on specific weight of the feed but the amount of primary sludge did. Addition of vitamins and micronutrients to the inhibited reactors did not stimulate methane production, which narrowed the range of possible causes to the lack of available macronutrients, namely nitrogen. On the other hand, possible un-ionized ammonia (NH3) inhibition of reactors fed with the highest primary sludge-amended feed hindered organic conversion rates. Elimination of pathogenic microorganisms from the high-solids residue via long-term storage, followed by low-dose lime disinfection, was also investigated. Storage alone reduced fecal coliform and Salmonella sp. bacteria to below detection, but bacterial spores of anaerobic Clostridium perfringens survived. Subsequent liming of the residue caused irreversible inactivation of the spores because of high pH and, possibly, free ammonia (NH3) inherent to sludge.

Biodegradation, Environmental↗