Prediction of microbial toxicity of industrial organic chemicals

Trevizo, C.; Nirmalakhandan, Nagamany

doi:10.1016/s0273-1223(99)00254-1

Cited by 14 publications

(1 citation statement)

References 8 publications

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“…Most of the studies on the effect of micropollutants on microorganism activity are batch tests measuring immediate effect on nitrification activity. − However, the actual nitrogen removal in a continuous process fed with micropollutants cannot be directly predicted by short-term batch tests because of two main reasons. First, for a given extent of inhibition, the actual nitrogen removal in the continuous process depends on the steady-state amount of autotrophic microorganisms, which in turn depends on process parameters such as ammonia load and sludge age.…”

Section: Introductionmentioning

confidence: 99%

Effect of Micropollutants (Organic Xenobiotics and Heavy Metals) on the Activated Sludge Process

Dionisi

Levantesi

Majone

et al. 2007

Ind. Eng. Chem. Res.

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Four experiments were performed in sequencing batch reactors, two by two in parallel, to study the effect of micropollutants (organic xenobiotics and heavy metals) on the performance of activated sludge processes. The reactors were operated for long times (at least 11 months each) and in a wide range of sludge ages (5-30 days). It was observed that production of biological solids, COD removal, and settling properties were not affected by the presence of micropollutants significantly. On the other hand, ammonia removal was much lower in the reactors fed with micropollutants (29-37% removal) than in the reactor without micropollutants (82% removal). Batch tests allowed the measurement of maximal activities of heterotrophic and autotrophic biomass. The activity of nitrifying microorganisms grown without micropollutants was greatly reduced (about 50%) by the addition of the micropollutants, but the residual micropollutants after treatment did not exert any inhibiting effect. Nitrate balances on the four runs confirmed that the fraction of nitrifying microorganisms was much higher in the reactor without micropollutants (4.5% of overall VSS) than in the reactors fed with micropollutants (maximum 0.5% of VSS). In spite of the fact that in the reactors fed with micropollutants the fraction of nitrifying microorganisms increased at increasing sludge age, a satisfactory nitrogen removal was not achieved in the whole tested range of experimental conditions, even after the 11-month acclimation. With regard to nitrogen removal in processes operated with micropollutants, the results obtained in this study seem to indicate the effectiveness both of processes with separate nitrification after a first treatment stage and of single-sludge processes carried out at very high sludge ages, as acheivable, e.g., by the use of membranes or of attached growth systems.

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Section: Introductionmentioning

confidence: 99%

Effect of Micropollutants (Organic Xenobiotics and Heavy Metals) on the Activated Sludge Process

Dionisi

Levantesi

Majone

et al. 2007

Ind. Eng. Chem. Res.

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Determination of acute and early life stage toxicity of fat‐plant effluent using zebrafish (Danio rerio)

Şi̇şman

İncekara

Yildiz

2008

Environmental Toxicology

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The present study examines the effects of an effluent from a fat plant (FP) on zebrafish (Danio rerio) embryos and larvae using the whole effluent toxicity testing methods (WET). The method is based on acute toxicity using 96-h larval mortality and chronic toxicity using endpoints such as the time to hatch, hatching success, deformity, growth rate, swim-up failure, accumulative mortality, and sex ratio. On the basis of larval mortality the 96-h LC(50) (the concentration was lethal to 50% of newly hatching zebrafish larvae) was 68.9%. In chronic toxicity test, newly fertilized embryos (<5-h old) were exposed to 1, 6, 12, 25, 50% effluent concentrations in a 24-h static renewal system at (27 +/- 0.5) degrees C until 15-day posthatch. The results showed that all chronic endpoints were significantly different from the control at 50% dilution. Embryos began to show lesions on third day at higher concentrations (12, 25, 50% FP effluent concentrations). Treatment group of 25% dilution showed delayed time to hatch. Morphological abnormalities were observed in newly hatched larvae at 25 and 50% FP effluent concentrations. At 25% dilution, sex ratio of larvae was alternated and there was feminization phenomenon. On the basis of the study, the FP effluent tested here may cause increasing embryotoxicity in the zebrafish embryos. We conclude that the test using zebrafish is feasible to evaluate both acute and chronic toxicities of industrial effluents.

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Incorporation of Toxicity Tests into the Turkish Industrial Discharge Monitoring Systems

Sponza

2001

Arch. Environ. Contam. Toxicol.

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A toxicity evaluation is an important parameter in wastewater quality and in the monitoring of discharged effluents. Some organic and inorganic compounds at toxic levels have been detected in industrial discharges, resulting in plant upsets and discharge permit violations. In some cases, even though the effluent does not exceed the chemical-specific discharge limits, the results of toxicity tests show potential toxicity. Knowledge of the toxicity of effluents can benefit treatment plant operators in optimizing plant operation, protecting receiving water quality, and establishing sewer discharge permits. In the Turkish regulations only toxicity dilution factor with fish is part of the toxicity monitoring program of permissible wastewater discharge. This study investigated the acute toxicity of pulp-paper, leather, and petrochemical 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 and Coliform bacteria) algae (Chlorella sp.), fish (Lepistes sp.), and protozoan species (Vorticella sp.) to represent four trophic 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 five cases for the leather and four cases for the pulp-paper and petrochemical industries. The results clearly showed that the use of bioassay tests produce additional information about the toxicity potential of industrial discharges and effluents.

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Prediction of microbial toxicity of industrial organic chemicals

Cited by 14 publications

References 8 publications

Effect of Micropollutants (Organic Xenobiotics and Heavy Metals) on the Activated Sludge Process

Effect of Micropollutants (Organic Xenobiotics and Heavy Metals) on the Activated Sludge Process

Determination of acute and early life stage toxicity of fat‐plant effluent using zebrafish (Danio rerio)

Incorporation of Toxicity Tests into the Turkish Industrial Discharge Monitoring Systems

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