Biomedical subjects

Delia Teresa Sponza

Publications and source records attributed to Delia Teresa Sponza.

14 recordsLinked to original sources

PubMed2006

Toxicity studies in a chemical dye production industry in Turkey.

This study investigated the acute toxicity of chemical dye production industry wastewaters by traditional and enrichment toxicity tests and emphasized the importance of toxicity tests in wastewater discharge regulations. The enrichment toxicity tests are novel applications indicating whether there is potential toxicity or stimulation conditions. Different organisms were used including bacteria (floc-Zoogloea ramigera and coliform-Escherichia coli bacteria), algae (Chlorella vulgaris), fish (lepistes-Poecilia reticulate) and protozoan (Vorticella campanula) to represent four tropic levels. The toxicity test results were compared with chemical analyses to identify the pollutants responsible for the toxicity in the effluent wastewater samples. Toxicity of the effluents could not be explained by using physicochemical analyses in four cases. The results clearly showed that the use of bioassay tests produce additional information about the toxicity potential of industrial discharges and effluents.

Animals↗

PubMed2006

Co-digestion of mixed industrial sludge with municipal solid wastes in anaerobic simulated landfilling bioreactors.

In this study, the feasibility of the anaerobic co-digestion of a mixed industrial sludge with municipal solid wastes (MSW) was investigated in three simulated anaerobic landfilling bioreactors during a 150-day period. All of the reactors were operated with leachate recirculation. One of them was loaded only with MSW (control reactor); the second reactor was loaded with mixed industrial sludge and MSW, the weight ratio of the MSW to mixed industrial sludge was 1:1 (based on dry solid) (Run 1); the third reactor was loaded with mixed industrial sludge and MSW, the weight ratio of the MSW to mixed industrial sludge was 1:2 (based on dry solid) (Run 2). The VFA concentrations decreased significantly in Run 1 and Run 2 reactors at the end of 150 days. The pH values were higher in Run 1 and Run 2 reactors compared to control reactor. The differences between leachate characteristics, the biodegradation and the bioefficiency of the reactors were compared. The NH(4)-N concentrations released to leachate from mixed sludge in Run 1 and Run 2 reactors were lower than that of control reactor. The BOD(5)/COD ratios in Run 1 and Run 2 reactors were lower than that of control reactor at the end of 150 days. Cumulative methane gas productions and methane percentages were higher in Run 1 and Run 2 reactors. Reductions in waste quantity, carbon percentage and settlement of the waste were better in Run 1 and Run 2 reactors compared to control reactor at the end of 150 days. Furthermore, TN and TP removals in waste were higher in reactors containing industrial sludge compared to control. The toxicity test results showed that toxicity was observed in reactors containing industrial mixed sludge.

Anaerobiosis↗

PubMed2005

Effects of alkalinity and co-substrate on the performance of an upflow anaerobic sludge blanket (UASB) reactor through decolorization of Congo Red azo dye.

The effect of substrate (glucose) concentrations and alkalinitiy (NaHCO3) on the decolorization of a synthetic wastewater containing Congo Red (CR) azo dye was performed in an upflow anaerobic sludge blanket (UASB). Color removal efficiencies approaching 100% were obtained at glucose-COD concentrations varying between 0 and 3000 mg/l. The methane production rate and total aromatic amine (TAA) removal efficiencies were found to be 120 ml per day and 43%, respectively, while the color was completely removed during glucose-COD free operation of the UASB reactor. The complete decolorization of CR dye under co-substrate free operation could be attributed to TAA metabolism which may provide the electrons required for the cleavage of azo bond in CR dye exist in the UASB reactor. No significant differences in pH levels (6.6-7.4), methane production rates (2000-2700 ml/day) and COD removal efficiencies (82-90%) were obtained for NAHCO3 concentrations ranging between 550 and 3000 mg/l. However, decolorization efficiency remained at 100% with decreasing NaHCO3 concentrations as low as 250 mg/l in the feed. An alkalinity/COD ratio of 0.163 in the feed was suggested for simultaneous optimum COD and color removal.

Bacteria, Anaerobic↗

PubMed2004

Effect of alkalinity on the performance of a simulated landfill bioreactor digesting organic solid wastes.

This study investigated the effects of alkalinity on the anaerobic treatment of the organic solid wastes collected from the kitchen of Engineering Faculty in Dokuz Eylul University, Izmir, Turkey and the leachate characteristics treated in three simulated landfill anaerobic bioreactors. All of the reactors were operated with leachate recirculation. One reactor was operated without alkalinity addition. The second reactor was operated by the addition of 3 g l-1 d-1 of NaHCO3 alkalinity to the leachate and the third reactor was operated by the addition of 6 g l-1 d-1 NaHCO3 alkalinity to the leachate. After 65 d of anaerobic incubation, it was observed that the chemical oxygen demand (COD), volatile fatty acids (VFA) concentrations, and biochemical oxygen demand to chemical oxygen demand (BOD5/COD) ratios in the leachate samples produced from the alkalinity added reactors were lower than the control reactor while the pH values were higher than the control reactor. The COD values were measured as 18900, 3800 and 2900 mg l-1 while the VFA concentrations were 6900, 1400 and 1290 mg l-1, respectively, in the leachate samples of the control, and reactors containing 3 g l-1 NaHCO3 and 6 g l-1 NaHCO3 after 65 d of anaerobic incubation. The total nitrogen (TN), total phosphorus (TP) and ammonium nitrogen (NH4-N) concentrations in organic solid waste (OSW) significantly reduced in the reactor containing 6 g l-1 NaHCO3 by d 65. The values of pH were 6.54, 7.19 and 7.31, after 65 d of anaerobic incubation, respectively, in the aforementioned reactors results in neutral environmental conditions in alkalinity added reactors. Methane percentage of the control, reactors containing 3 g l-1 NaHCO3 and 6 g l-1 NaHCO3 were 37%, 64% and 65%, respectively, after 65 d of incubation. BOD5/COD ratios of 0.27 and 0.25 were achieved in the 3 and 6 g l-1 NaHCO3 containing reactors, indicating a better OSW stabilization. Alkalinity addition reduced the waste quantity, the organic content of the solid waste and the biodegradation time.

Bacteria, Anaerobic↗

PubMed2004

Monitoring of toxicity and intermediates of C.I. Direct Black 38 azo dye through decolorization in an anaerobic/aerobic sequential reactor system.

An Upflow Anaerobic Sludge Blanket Reactor/Continuous Stirred Tank Reactor was used sequentially to decolorize and mineralize C.I. Direct Black 38 azo dye (3200 mg/L) in a synthetic wastewater containing glucose as co-substrate. At the steady state conditions color was effectively removed under anaerobic condition, while the total aromatic amines and organic fraction could be mainly reduced under aerobic conditions. NO(3)(-)--N, COD, BOD(5,) aromatic amine, HPLC and GC analyses showed that Direct Black 38 could be chiefly mineralized by the sequential system. The toxicity levels were determined using three different test organism (ATA-anaerobic toxicity, respiration/inhibition and Daphnia magna tests) through the continuous operation of anaerobic/aerobic sequential system treating Direct Black 38 dye containing synthetic wastewater. Feed and anaerobic effluent had greater toxicity than the aerobic effluent after mineralization of dye.

Aerobiosis↗

PubMed2004

Influence of nitrate and COD on phosphorus, nitrogen and dinitrotoluene (DNT) removals under batch anaerobic and anoxic conditions.

In this study, the effects of COD to NO(3)-N ratio in the feed on PO(4)-P removal was investigated. Maximum PO(4)-P uptake was obtained in the anoxic reactor when the COD to NO(3)-N ratios were between 2 and 3.75. With the influent COD of 800-1500 mg COD/L a total of the maximum removable PO(4)-P was 56 mg PO(4)-P/L through 20 days of anaerobic/anoxic incubation, indicating 98% P removal in the anoxic reactor. Similarly, for the COD to NO(3)-N ratios varying between 2 and 3.75 maximum denitrification was observed. Through anoxic operation the poly-P bacteria are capable of removing NO(3)-N using VFA, COD as carbon source and NO(3)-N as the electron acceptor after methanogenesis has been completed. High NO(3)-N concentrations stopped significantly the P uptake. A total of 97-99% dinitrotoluene removal efficiencies in the reactors containing COD to NO(3)-N ratio of 2 and 3.75 after 20 days of incubation period. For maximum NO(3)-N and PO(4)-P removals optimal COD to NO(3)-N ratios, COD and NO(3)-N concentrations were 2-3.75, 2000-4000 mg COD/L and, 800-1500 mg NO(3)-N/L, respectively.

Journal Article↗

PubMed2004

A batch kinetic study on decolorization and inhibition of Reactive Black 5 and Direct Brown 2 in an anaerobic mixed culture.

Decolorization and inhibition kinetic characteristics of two azo dyes namely Reactive Black 5 (RB 5) and Direct Brown 2 (DB 2) were investigated with partially granulated anaerobic mixed culture using glucose (3000 mg l(-1) COD) as carbon source and electron donor during batch incubation. Monod, zero-, first-, and second-order reaction kinetic models were tested in order to determine the most suitable rate model of substrate and color removal kinetic. The course of the decolorization and substrate removal process approximates to first-order kinetic model under batch conditions. Decolorization, and substrate removal were achieved effectively under test conditions but ultimate removal of azo dyes and substrate were not observed at high dye concentrations. Aromatic amine and volatile fatty acid accumulation were observed proportionally at a higher azo dye concentration. A competitive kinetic model that describes the anaerobic co-metabolism of increasing RB 5 and DB 2 dye concentrations with glucose as co-substrate has been developed based on the experimental data.

Anaerobiosis↗

PubMed2004

Decolorization of azo dyes under batch anaerobic and sequential anaerobic/aerobic conditions.

Batch anaerobic and sequential anaerobic upflow anaerobic sludge blanket (UASB)/aerobic continuous stirred tank reactor (CSTR) were used to determine the color and COD removals under anaerobic/aerobic conditions. Two azo dyes namely "Reactive Black 5 (RB 5)," "Congo Red (CR)," and glucose as a carbon source were used for synthetic wastewater. The course of the decolorization process approximates to first order and zero order kinetics with respect to dye concentration for RB 5 and Congo Red azo dyes, respectively, in batch conditions. The decolorization kinetic constant (K0) values increased from 3.6 to 11.8 mg(L h)(-1) as increases in dye concentrations from 200 to 3200 mg L(-1) for CR. Increases in dye concentrations from 0 to 3200 mg L(-1) reduce the decolorization rate constant (k1) values from 0.0141 to 0.0019 h(-1) in batch studies performed with RB 5. Decolorization was achieved effectively under test conditions but ultimate decolorization of azo dyes was not observed at all dye concentrations in batch assay conditions. Dye concentrations of 100 mg L(-1) and 3000 mg L(-1) of glucose-COD containing basal medium were used for continuous studies. The effect of organic loadings and HRT, on the color removal efficiencies and methane gas productions were monitored. 94.1-45.4% COD and 79-73% color removal efficiencies were obtained at an organic system during decolorization of Reactive Black 5. 92.3-77.0% COD and 95.3-92.2% decolorization efficiencies were achieved at a organic loading rate of 1.03-6.65 kg (m3 day)(-1) and a HRT of 3.54-0.49 for Congo Red treatment. The results of this study showed that, although decolorization continued, COD removal efficiencies and methane gas production were depressed at high organic loadings under anaerobic conditions. Furthermore, VFA accumulation, alkalinity consumption, and methane gas percentage were monitored at organic loading as high as 2.49-4.74 kg (m3 day)(-1) and 24.60-30.62 kg (m3 day)(-1), respectively, through the decolorization of RB 5 and CR dyes in the UASB reactor.

Bacteria, Aerobic↗

PubMed2004

Effect of aeration on the performance of a simulated landfilling reactor stabilizing municipal solid wastes.

In this study, the effects of intermittent aeration on the anaerobic treatment of domestic solid waste and leachate characteristics were investigated in three simulated landfill anaerobic bioreactors. All of the reactors were operated with leachate recirculation and recirculation rate was 300 mL/d. All the reactors were loaded with solid waste having different operational mode. The first reactor was operated with recirculation (control-no aeration). The second reactor was aerated three days in a week during 1 h (Run 1) and the last reactor was aerated one day in a week during 1 h (Run 2). pH, chemical oxygen demand (COD), volatile fatty acids (VFA), ammonium nitrogen (NH4-N), nitrate nitrogen (NO3-N) concentrations, total, and methane gas productions in the leachate samples were regularly monitored. 96, 85, and 97% COD and 86, 77, and 93% VFA removals were obtained, in the leachate samples of the control, R1 and R2 reactors, respectively, after 79 days of anaerobic incubation. The TN, TP and NH4-N concentrations in MSW reduced to 4300, 1100, and 160 mg/g from 11,100, 2450, and 630 mg/g in R1 reactor by day 79. The values of pH were 6.98, 6.76, and 7.98, respectively, after anaerobic incubation, respectively in the aforementioned reactors. It was observed that the aeration decreased the methane percentage and the quantity in the simulated bioreactor. The maximum cumulative methane gas production was recorded as 11.2, 0.9, and 3.6 L in control, R1 and R2 reactors, respectively, at the end of 79 days. A BOD5/COD ratio of 0.23 achieved in the R2 reactor indicated the better MSW stabilization resulting in a high rate than that of R1 and control reactors. It was observed that the aerated reactor one day in a week during one hour (R2) reduced the COD and VFA concentrations in leachate samples. The aerated reactor three days in a week during 1 h (R1) reduced the waste quantity, the organic content of the solid waste. The final leachate quantities of aerated runs were lower than that of control reactor operated under strictly anaerobic conditions.

Bacteria, Anaerobic↗

PubMed2003

Application of toxicity tests into discharges of the pulp-paper industry in Turkey.

The aim of this study was to investigate the acute toxicity of pulp-paper industry wastewater using traditional and enrichment toxicity tests and to emphasize the importance of toxicity tests in wastewater discharge regulations. Enrichment toxicity tests are novel applications and give an idea of whether there is potential toxicity or growth-limiting and -stimulating conditions. Different organisms were used such as bacteria (floc and coliform bacteria), algae (Chlorella sp.), protozoa (Vorticella sp.), and fish (Lepistes sp.) to represent four trophic levels. Furthermore, chemical oxygen demand (COD) fractionation results were compared with these tests to assess the effect of COD subcategories on the determination of possible toxicity. The pulp-paper industry results revealed acute toxicity to at least two organisms in 6 of 20 effluent samples. The toxicity test results were assessed with chemical analyses such as COD, biochemical oxygen demand (BOD), color, absorbable organic halogen (AOXs), and phenol. It was observed that the toxicity of the effluents could not be explained by using physicochemical analyses in four cases for the pulp-paper industry. The results clearly indicate that bioassay tests provide additional information on the toxicity potential of industrial discharges and effluents.

Animals↗

PubMed2003

Treatability of 2,4 dinitrotoluene in anaerobic/aerobic sequential processes.

Lab-scale anaerobic upflow anaerobic sludge blanket (UASB) completely stirred tank (CSTR) activated sludge reactor system was used to investigate the treatability of 2,4 dinitrotoluene (DNT) using molasses as primary substrate in continuous fed mode. The treatment efficiencies in anaerobic and aerobic reactors were determined by monitoring the chemical oxygen demand (COD), DNT removals, total and methane gas productions. The effect of increasing DNT concentrations on bicarbonate alkalinity, volatile fatty acid accumulation and methane gas percentage were investigated in UASB reactor. Based on the anaerobic toxicity (ATA) test results, although 12 mg L(-1) of DNT is toxic to unacclimatized partially granulated sludge; over 85 and 90% COD and DNT removal efficiencies were obtained at loadings rates of 250 mg DNT L(-1) day(-1) in anaerobic reactor at a HRT of 0.5 day. Total volatile fatty acid (TVFA) accumulation is associated with methane productions as low as 40% of total gas, at loading rate as high as 500 and 1000 mg DNT L(-1) day(-1) through anaerobic DNT biodegradation. The treatment efficiencies in the aerobic reactor were determined by monitoring the COD and DNT removals. The intermetabolite products released through anaerobic and aerobic phases were detected. The TVFA, total aromatic amines, ammonia, total nitrogen and toluene concentrations were monitored. The aerobic step was used for the ultimate mineralization of the remaining COD, DNT, toluene and aromatic amines from the anaerobic treatment. The specific methanogenic activity (SMA) of DNT degrading granules were 2.2 and 0.43g CH4-COD g(-1) VSS day(-1) at DNT loading rates of 12 and 500 mg L(-1) day(-1), respectively. The anaerobic breakdown products of DNT were effectively oxidized in the CSTR reactor since the COD and DNT were ultimately mineralized under aerobic conditions. It can be suggested that DNT, the breakdown products and the COD were ultimately mineralized in combined UASB/CSTR reactor. More than 95% COD and DNT removal efficiencies were obtained in combined UASB,CSTR system at an initial DNT concentration of 125 mg/L(-1) and a loading rate of 250 mg DNT L(-1) day(-1).

Bacteria, Aerobic↗

PubMed2003

Aromatic amine degradation in a UASB/CSTR sequential system treating Congo Red dye.

In this study an anaerobic (upflow anaerobic sludge blanket reactor)/aerobic (completely stirred tank reactor) sequential system was used to treat a synthetic wastewater with minerals and co-substrate together with 100-4000 mg L(-1) of Congo Red dye (Direct red 28) (CR), which is a banned azo dye in Turkey. The effect of hydraulic retention time (HRT) on the decolorization and the COD removal efficiency was investigated at constant 100 mg L(-1) Congo Red concentration. 77% of COD and 95% of color was removed at a HRT of 0.486 days and a maximum organic loading rate of 6.656 kg COD m(-3) day(-1) in the anaerobic/aerobic stage. In the continuous operations, 88% of COD, 99% of color and 91% of total aromatic amine (TAA) were removed at a HRT of 3.60 days and at a CR concentration of 4000 mg L(-1). This corresponds to an organic loading rate of 1.81 kg COD m(-3) day(-1), and a CR dye loading rate of 46.37 g dye m(-3) h(-1), respectively, in the whole system. The TAA produced under anaerobic conditions was ultimately removed in the aerobic stage, resulting in very low aromatic amine recoveries (5-18%) in the last one. Therefore the aerobic effluents exhibited higher IC50 and specific methanogenic activities (SMA) compared to anaerobic and dye containing samples, indicating the reduced toxicity.

Amines↗

PubMed2002

Necessity of toxicity assessment in Turkish industrial discharges (examples from metal and textile industry effluents).

Toxicity of some organic and inorganic chemicals to microorganisms is an important consideration in assessing their environmental impact against their economic benefits. Microorganisms play an important role in several environmental processes, both natural and engineered. Some organic and inorganics at toxic levels have been detected in industrial discharges resulting in plant upsets and discharge permit violations. In addition to this, even though in some cases the effluent wastewater does not exceed the discharge limits, the results of toxicity tests show potential toxicity. Toxicity knowledge of effluents can benefit treatment plant operators in optimising plant operation, setting pre-treatment standards, and protecting receiving water quality and in establishing sewer discharge permits to safeguard the plant. In the Turkish regulations only toxicity dilution factor (TDF) with fish is part of the toxicity monitoring program of permissible wastewater discharge. In various countries, laboratory studies involving the use of different organisms and protocol for toxicity assessment was conducted involving a number of discharges. In this study, it was aimed to investigate the acute toxicity of textile and metal industry wastewaters by traditional and enrichment toxicity tests and emphasize the importance of toxicity tests in wastewater discharge regulations. The enrichment toxicity tests are novel applications and give an idea whether there is potential toxicity or growth limiting and stimulation conditions. Different organisms were used such as bacteria (Floc and Coliform bacteria) algae (Chlorella sp.). fish (Lepistes sp.) and protozoan (Vorticella sp.) to represent four tropic levels. The textile industry results showed acute toxicity for at least one organism in 8 out of 23 effluent samples. Acute toxicity for at least two organisms in 7 out of 23 effluent sampling was observed for the metal industry. The toxicity test results were assessed with chemical analyses such as COD, BOD, color and heavy metals. It was observed that the toxicity of the effluents could not be explained by using physicochemical analyses in 5 cases for metal and 4 cases for the textile industries. The results clearly showed that the use of bioassay tests produce additional information about the toxicity potential of industrial discharges and effluents.

Animals↗

PubMed2002

Tetrachloroethylene (TCE) removal during anaerobic granulation in an upflow anaerobic sludge blanket (UASB) reactor.

The anaerobic biotransformation of TCE was investigated during the granulation process by reducing the HRT and increasing the chemical oxygen demand (COD) and TCE loadings in a 21 laboratory-scale upflow anaerobic sludge blanket (UASB) reactor. Anaerobic unacclimated sludge and glucose were used as seed and primary substrate, respectively. Initial granules were developed after 1.5 months of start-up, which grew at an accelerated pace for 7 months and then became fully grown. The effect of operational parameters such as influent TCE concentrations, COD and TCE loading, food to microorganism (F/M) ratio and specific methanogenic activity (SMA) were also considered during granulation. The granular sludge cultivated had a maximum diameter of 2.5 mm and SMA of 1.32 gCOD (gTSS day)(-1) while 94% COD and 90% TCE removal efficiencies were achieved when the reactor was operating at loading rates as high as 160 mg TCE (1 day)(-1) and 14 gCOD (1 day)(-1), respectively after 230 days of continuos operation. This corresponds to HRT of 0.28 day and F/M ratio of 0.60 gCOD (gTSS day)(-1). Kinetic coefficients of k (maximum specific substrate utilization rate), Ks (half velocity coefficient), Y (growth yield coefficient) and b (decay coefficient) were determined to be 2.38 mgCOD (mgTSS day)(-1), 108 mgCOD 1(-1), 0.17 mgTSS (mgCOD)(-1) and 0.015 day(-1), respectively during TCE biotransformation based on glucose-COD during granulation.

Bacteria, Anaerobic↗