THM formation during chlorination of treated municipal wastewater

2002 ◽  
Vol 2 (3) ◽  
pp. 235-242 ◽  
Author(s):  
E. Koukouraki ◽  
E. Diamadopoulos
Keyword(s):  
Organic Carbon ◽  
Contact Time ◽  
Municipal Wastewater ◽  
Secondary Effluent ◽  
Batch Experiments ◽  
Limited Effect ◽  
Formation Potential ◽  
Coagulation Tests ◽  
Treated Municipal Wastewater

Chlorination batch experiments were conducted in order to estimate the concentration of THM and their formation potential in nitrified and partially nitrified secondary effluent. The role of contact time (up to 2 hours), chlorine dose (3 levels), pH and temperature on the formation of THM was evaluated. THM formation, as measured by individual concentration as well as formation potential, was high for the nitrified secondary effluent, while for the partially nitrified effluent the respective concentrations were low, due to the reaction of chlorine with ammonia to form chloramines. In general, THM concentrations progressively increased as contact time, pH and chlorine dose increased. Increase in temperature (from 15-25°C) showed a rather limited effect. In addition, coagulation tests were applied prior to chlorination of the nitrified effluent for removing organic carbon and thereby controlling the formation of THM. Alum was used as the coagulant in doses varying from 0.1 mM to 2.5 mM. As the coagulant dose increased, the removal of both DOC and absorbance at 254 nm increased, while THM formation decreased. The reduction in THM formation was more pronounced for coagulant doses higher than 1.5 mM.

Effect of C/N ratio on the bioregeneration of biological activated carbon

1997 ◽  
Vol 36 (12) ◽  
pp. 239-249 ◽  
Author(s):  
Duk-Jin Kim ◽  
Takashi Miyahara ◽  
Tatsuya Noike
Keyword(s):  
Activated Carbon ◽  
Carbon Source ◽  
Organic Carbon ◽  
Removal Rate ◽  
Experimental Period ◽  
Batch Experiments ◽  
Biological Activated Carbon ◽  
Carbon Concentrations ◽  
Insight Into

To obtain insight into the role of biological activated carbon (BAC) in the operation of the denitrification process using external carbon source, the effect of C/N ratio on bioregeneration of BAC was investigated using a fluidized bed reactor. The C/N ratio was controlled by the semi-continuous mode in which NO3-N was continuously supplied to each column. The supply of sucrose as a sole organic carbon was controlled during the experimental period. The BAC under steady state of the continuous experiments was supplied to the semi-continuous experiment. The organic carbon was supplied to each column for 20 minutes in all semi-batch experiments, but the intervals were varied from 8 to 24 hours. The influent organic carbon concentrations were controlled to maintain the average C/N ratio at 7.06 for all semi-batch experiments. In the semi-continuous experiment, the five columns have achieved an average denitrification efficiency ranging from 71% to 99%, though the influent C/N ratios were varied from 0 to 508. This is due to the adsorption and desorption capacities of BAC. BAC plays a role as a storage tank for the residual sucrose using its micropore during the time when sucrose was supplied, and BAC supplied the sucrose to the denitrifying bacteria as a carbon source so as to keep high nitrogen removal rate when sucrose was not fed to the columns. These results suggest that bioregeneration may be influenced by the C/N ratio in the environment around BAC.

Modelling the formation of THM (trihalomethanes) during chlorination of treated municipal wastewater

2003 ◽  
Vol 3 (4) ◽  
pp. 277-284 ◽  
Author(s):  
E. Koukouraki ◽  
E. Diamadopoulos
Keyword(s):  
Contact Time ◽  
Municipal Wastewater ◽  
Nitrogen Concentration ◽  
Ammonia Nitrogen ◽  
Secondary Effluent ◽  
Exponential Models ◽  
Ultraviolet Absorbance ◽  
Independent Variables ◽  
Operational Variables ◽  
Doc Concentration

Trihalomethanes (THM) concentrations were determined during chlorination of nitrified and partially nitrified secondary effluents, as well as tertiary effluent. Coagulation tests, with alum doses varying from 0.1 mM to 2.5 mM, were applied prior to chlorination to the nitrified effluent in order to remove organic carbon and thereby control the formation of THM. The results indicated that the operational variables of contact time, ammonia nitrogen concentration, pH and chlorine dose had significant effects on THM formation. In tertiary effluents, as the coagulant dose increased, THM formation decreased with a more pronounced reduction for doses higher than 1.5 mM. Modelling of the THM formation was made by means of empirical exponential models. For the chlorination of the nitrified secondary effluent, contact time, chlorine dose, pH and temperature were the model's independent variables, while for the partially nitrified secondary effluent the equivalent independent variables were the contact time, the chlorine dose and the ammonia nitrogen concentration. Modelling of THM formation during chlorination of tertiary effluent was based on either the DOC concentration or the ultraviolet absorbance, as well as on a combination of both. The three exponential models fit reasonably well the experimental data for all the coagulant doses, except for the 2 and 2.5 mM dose, where the reduction in organic matter was not as high as the equivalent reduction in THM formation. The use of the ultraviolet absorbance alone as an independent variable in the model provided a slightly better simulation of the measured THM concentrations.

Simultaneous Occurrence of Human Antibodies Directed against Fibrinogen, Thrombin, and Factor V Following Exposure to Bovine Thrombin: Effects on Blood Coagulation, Protein C Activation and Platelet Function

1997 ◽  
Vol 77 (02) ◽  
pp. 343-349 ◽  
Author(s):  
Vibhuti D Chouhan ◽  
Raul A De La Cadena ◽  
Chandrasekaran Nagaswami ◽  
John W Weisel ◽  
Mehdi Kajani ◽  
...  
Keyword(s):  
Protein C ◽  
Simultaneous Occurrence ◽  
Factor V ◽  
Bovine Thrombin ◽  
Plasma Factor ◽  
Coagulation Tests ◽  
Coagulation Protein ◽  
Severe Epistaxis ◽  
Clotting Protein

SummaryWe describe a patient with severe epistaxis, prolonged coagulation tests and decreased plasma factor V following exposure to bovine topical thrombin. Patient IgG, but not normal IgG, showed binding to immobilized thrombin (bovine > human) and fibrinogen, and to factor V by Western blotting; the binding to thrombin was inhibited by hirudin fragment 54-65. Electron microscopy of rotary shadowed preparations showed complexes with IgG molecules attached near the ends of trinodular fibrinogen molecules. Patient IgG inhibited procoagulant, anticoagulant and cell-stimulating functions of thrombin demonstrated by inhibition of fibrinogen clotting, protein C activation and platelet aggregation; thrombin hydrolysis of S-2238 was not inhibited. The results suggest that the antibody is targeted against anion-binding exosite and not catalytic site of thrombin. Antifibrinogen antibodies have not been reported in patients exposed to bovine thrombin. There is a pressing need to re-evaluate the role of bovine thrombin as a therapeutic agent.

A study about the use of chemicals in conventional tertiary treatment. Performances comparison of three municipal wastewater treatment plants and pilot plant experiences

2011 ◽  
Vol 6 (1) ◽  
Author(s):  
A. Iborra-Clar ◽  
J.A. Mendoza-Roca ◽  
A. Bes-Pií ◽  
J.J. Morenilla-Martínez ◽  
I. Bernácer-Bonora ◽  
...  
Keyword(s):  
Water Quality ◽  
Wastewater Treatment ◽  
Pilot Plant ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Secondary Effluent ◽  
Municipal Wastewater Treatment ◽  
Wastewater Reclamation ◽  
Valencian Region ◽  
Municipal Wastewater Treatment Plants

Rainfall diminution in the last years has entailed water scarcity in plenty of European regions, especially in Mediterranean areas. As a consequence, regional water authorities have enhanced wastewater reclamation and reuse. Thus, the implementation of tertiary treatments has become of paramount importance in the municipal wastewater treatment plants (WWTP) of Valencian Region (Spain). Conventional tertiary treatments consist of a physico-chemical treatment of the secondary effluent followed by sand filtration and UV radiation. However, the addition of coagulants and flocculants sometimes does not contribute significantly in the final water quality. In this work, results of 20-months operation of three WWTP in Valencian Region with different tertiary treatments (two without chemicals addition and another with chemicals addition) are discussed. Besides, experiments with a 2 m3/h pilot plant located in the WWTP Quart-Benager in Valencia were performed in order to evaluate with the same secondary effluent the effect of the chemicals addition on the final water quality. Results showed that the addition of chemicals did not improve the final water quality significantly. These results were observed both comparing the three full scale plants and in the pilot plant operation.

WASTEWATER DISINFECTION BY UV AT TRANI MUNICIPAL PLANT

1994 ◽  
Vol 30 (4) ◽  
pp. 125-132 ◽  
Author(s):  
D. Carnimeo ◽  
E. Contini ◽  
R. Di Marino ◽  
F. Donadio ◽  
L. Liberti ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Municipal Wastewater ◽  
Treatment Plant ◽  
Continuous Operation ◽  
Secondary Effluent ◽  
Municipal Wastewater Treatment ◽  
South Italy ◽  
Wastewater Disinfection ◽  
Pilot Investigation ◽  
Effluent Characteristics

The pilot investigation on the use of UV as an alternative disinfectant to NaOCI was started in 1992 at Trani (South Italy) municipal wastewater treatment plant (335 m3/h). The results collected after six months continuous operation enabled us to compare UV and NaOCl disinfection effectiveness on the basis of secondary effluent characteristics, quantify photoreactivation effects, evidence possible DBP formation and assess costs.

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