An OUR-based approach to determine the toxic effects of 2,4-dichlorophenoxyacetic acid in activated sludge (original) (raw)
Related papers
Effects of 2,4-dichlorophenol on activated sludge
Applied Microbiology and Biotechnology, 2002
The effects of 2,4-dichlorophenol (2,4-DCP) on both acclimated and unacclimated activated sludge were investigated in batch reactors. The IC 50 values on the basis of maximum specific growth rate (µ m ), percent chemical oxygen demand (COD) removal efficiency and sludge activity were found to be 72, 60 and 47 mg l -1 , respectively, for unacclimated culture. The percent COD removal efficiencies of unacclimated culture were affected adversely, even at low concentrations, whereas culture acclimated to 75 mg 2,4-DCP l -1 could tolerate about 200 mg 2,4-DCP l -1 on the basis of COD removal efficiency. Although yield coefficient values of unacclimated culture increased surprisingly to very high values with the addition of 2,4-DCP, a linear decrease with respect to 2,4-DCP concentrations was observed for acclimated culture. Although no removal was observed with unacclimated culture, almost complete removal of 2,4-DCP up to a concentration of 148.7 mg l -1 was observed with acclimated culture. It was showed that the culture could use 2,4-DCP as sole organic carbon source, although higher removal efficiencies in the presence of a readily degradable substrate were observed. Culture acclimated to 4-chlorophenol used 2,4-DCP as sole organic carbon source better than those acclimated to 2,4-DCP.
Toxic effects of inhibitors in biological wastewater treatment processes
The Canadian Journal of Chemical Engineering, 1988
Toxic effects of inhibitors on microbial growth in the activated sludge process were demonstrated by a kinetic model. The effects of pH and biomass concentration on the degree of inhibition were described. The applicability of the kinetic model to describe the inhibitory effects with respect to various growth measuring parameters like respiration rate, ATP analysis, first and zero order reaction rates were illustrated. The inhibitory effects of heavy metals on the nitrification and denitrification processes were established. Experimental data from other investigations were used to prove the applicability of the model. On a dCmontrC ? i I'aide d'un modkle cinCtique les effets toxiques d'inhibiteurs sur la croissance microbienne dans le procCdC de boues activkes. On a dCcrit les effets du pH et de la concentration en biomasse sur le degrk d'inhibition. On a vCrifie la justesse du modkle cinCtique dans le cas des effets inhibiteurs Ctablis en fonction de diffkrents parambtres de mesure de croissance comme le taux de respiration, le niveau d'ATP et des cinktiques de rkaction d'ordre zCro et d'ordre un. Les effets inhibiteurs des mCtaux lourds sur les processus de nitrification et de dknitrification ont Btb Btablis. Les donntes expirimentales d'autres travaux ont CtC utiliskes pour illustrer I'utilitC de ce modble.
Estimating the toxicities of organic chemicals in activated sludge process
Water Research, 2010
ASP BMLR QSAR a b s t r a c t The experimental log EC 50 toxicity values of 104 compounds causing bioluminescent repression of the bacterium strain Pseudomonas isolated from an industrial wastewater were studied. Using the Best Multilinear Regression method implemented in CODESSA PRO, models with up to 8 theoretical descriptors were obtained. Utilizing a rigorous descriptor selection and validation procedure a reliable QSAR model with four parameters was selected as best. The proposed model emphasizes the importance of the halogen atoms presented in each compound, the possibility of H-bond formation and the flexibility
Biotechnology Letters, 1995
Degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was examined together with nitrogen conversion by using an activated sludge acclimated to artificial sewage containing 2,4-D and urea-N, which were the sole carbon and nitrogen sources, respevtively. Ammonification of urea and nitrification of ammonia proceeded concurrently with 2,4-D degradation by the acclimated activated sludge.
Bioresource Technology, 2009
The effects of phenol, 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP) and 1,2,4-trichlorobenzene (1,2,4-TCB) on the biodegradation kinetics of the conventional activated sludge system (CASS) and the selector activated sludge system (SASS) were investigated. Experiments were carried out using a respirometric method on unacclimated biomass from two lab-scale systems that were operated with the sludge age of 8 days. Toxicity of the test compounds for both reactors were arranged according to EC 50 (effective concentration) values in order as: 1,2,4-TCB > 2,4-DCP > 2-CP > phenol. All selected test compounds induced higher inhibition effect in the CASS. The SASS appeared to reduce inhibition effect in comparison to the CASS, by 21.36%, 66.95%, 64.37% and 33.33% for phenol, 2-CP, 2,4-DCP and 1,2,4-TCB, respectively. Consequently, the SASS may be recommended as a promising configuration alternative for the waste streams containing toxic compounds.
Enzyme response of activated sludge to a mixture of emerging contaminants in continuous exposure
PLOS ONE
The relevant information about the impacts caused by presence of emerging pollutants in mixtures on the ecological environment, especially on the more vulnerable compartments such as activated sludge (AS) is relatively limited. This study investigated the effect of ibuprofen (IBU) and triclosan (TCS), alone and in combination to the performance and enzymatic activity of AS bacterial community. The assays were carried out in a pilot AS reactor operating for two-weeks under continuous dosage of pollutants. The microbial activity was tracked by measuring oxygen uptake rate, esterase activity, oxidative stress and antioxidant enzyme activities. It was found that IBU and TCS had no acute toxic effects on reactor biomass concentration. TCS led to significant decrease of COD removal efficiency, which dropped from 90% to 35%. Continuous exposure to IBU, TCS and their mixtures increased the activities of glutathione s-transferase (GST) and esterase as a response to oxidative damage. A high increase in GST activity was associated with non-reversible toxic damage while peaks of esterase activity combined with moderate GST increase were attributed to an adaptive response.
Evaluation of Toxicity of Pharmaceuticals to the Activated Sludge Treatment Plant
2011
Different toxic pharmaceutical compounds can affect the efficiency of the Biological wastewater treatment plant. Inorder to increase the efficiency of the treatment plant, it is very important to screen these pharmaceuticals for their toxicity towards the activated sludge. Activated sludge is the main component of Biological wastewater treatment system. Therefore, in this work, 50 pharmaceuticals have been tested for their toxicity to the activated sludge. This Masteral Thesis work was done with the support of a pharmaceutical company called Universal Corporation. Pharmaceuticals have been obtained from this Corporation which is located in Nairobi, Kenya. Pharmaceutical industry manufactures many drugs like anti-HIV, anti-malarial, anti-inflammatory, lipid regulators, antibiotics, contraceptives, beta blockers and tranquilizers whose level should be minimum or they should be absent in the treated effluents from the treatment plant. OUR (Oxygen Uptake Rate) method has been used in this process for detecting the toxicity of these chemicals. This is the major principle of this method for the measurement of toxicity of chemicals. The laboratory work was done in the Tampere University of Technology. For this work, OUR (Oxygen Uptake Rate) measurement technique is applied for the toxicity test.The activated sludge was obtained from the Tampere. Oxygen meter WTW Multiline P4 with Oxygen probe CellOx325 device was used to measure the oxygen consumption rate of the activated sludge. The graphs were plotted for all the measurements and the MLSS and MLVSS values were also calculated. In the end, inhibition percentage was calculated for all the tests and EC50 concentration was calculated for the toxic pharmaceuticals. Out of 50 most popular pharmaceuticals, 11 pharmcaeuticals showed the significant inhibition percentage to the activated sludge. Aspirin, Cetrimide, Cetrizine, Chlorpheniramine Maleate, Caffeine Anhydrous, Ephedrine Hcl, Levamisole Hcl, Quinine Dihydrochloride, Diclofenac Sodium and Camphor were found toxic. The EC50 value for Diclofenace Sodium was found 23.7 mg/l. These drugs, due to its toxicity affect the efficiency of the WWTP.
Chemosphere, 2002
Five rapid direct toxicity assessment methods were used in three European partner countries to determine the toxicity of single toxicants, mixed toxicants and real industrial wastes. The final aim was to protect microbial degradation of organic wastes in biological treatment processes and hence enhance the quality of treated effluents to be discharged to the environment. Nitrification inhibition, Respirometry, Adenosine triphosphate luminescence and Enzyme inhibition were tested utilising activated sludge as the testing matrix. The Vibrio fischeri toxicity test was used as a surrogate to compare the various microbial bioassays. The IC 50 (toxicant concentration eliciting a 50% inhibitory effect) was determined for a number of pollutants including single toxicants Cd, Cr, Cu, Zn, 3,5-dichlorophenol, toluene and linear alkylbenzenesulphonate (LAS); a standard mixture of metals and LAS; a standard mixture of organics and LAS, and 16 industrial effluents. The V. fischeri bioassay was also chosen in order to assess quality control of toxicant preparation during testing in the different laboratories of the partner countries. Comparisons of sensitivity, cost of implementation, cost per test, relevance, and ease of use were made. The most sensitive bioassays were V. fischeri and Nitrification inhibition, however, this depended in the main on the pollutant and mixtures tested. It is recommended that during assessment of wastewater toxicity a suite of tests be used rather than reliance on one particular test. Ó
Toxic Effects of Copper-Based and Synthetic Organic Pesticides on Activated Sludge
2012
Toxic effects of five commonly used pesticides on the biomass of a municipal activated sludge system were determined on the basis of the reduction in the oxygen uptake rate (OUR) and specific oxygen uptake rate (SOUR). Toxicity levels of the selected pesticides were determined by employing a modified OECD 209 (Organisation for Economic Cooperation and Development) method which was performed as batch experiments using a respirometer. Copper sulphate (CuSO 4 Á 5 H 2 O), copper oxychloride (Cu 2 Cl(OH) 3), copper calcium oxychloride (CaCu 3 Cl 2 (OH) 6) as copper-based pesticides and chlorsulphuron (C 12 H 12 ClN 5 O 4 S), 2,4-dichlorophenoxyacetic acid (2,4-D) (C 8 H 6 Cl 2 O 3) as synthetic organic pesticides were selected for the experiments. The EC 50 values were determined to be 78, 249 and 281 mg/L for CuSO 4 Á 5 H 2 O, Cu 2 Cl(OH) 3 and CaCu 3 Cl 2 (OH) 6 , respectively. Corresponding values for C 12 H 12 ClN 5 O 4 S and 2,4-D were 860 and 3664 mg/L, respectively. Results indicated that toxicity effects of copper-based pesticides were higher than that of synthetic organic pesticides. CuSO 4 Á 5 H 2 O was found to exert the highest toxicity among the copper-based pesticides, whereas, C 12 H 12 ClN 5 O 4 S was determined to be the most toxic among the organic pesticides on activated sludge biomass.