ABSTRACT
This paper, as part of a study carried out for the recovery of the acid dye bath wastewaters of a carpet manufacturing industry by membrane processes, describes the evaluation of alternative strategies for the pre-treatment of acid dye bath wastewaters. Dead-end microfiltration (MF) simulating sand filtration with MF media having pore sizes of 2.5, 1.0, 0.45 and 0.2 microm and ultrafiltration (UF) with an UF membrane having a molecular weight cut off (MWCO) of 50,000 Da were tested in single and sequential stages in order to achieve the best treatment efficiency. Four alternative process trains were tested; single MF, sequential MF, single UF, and MF followed by UF. For both MF and UF, application of sequential filtration did not provide any significant benefit over single processes. In addition, chemical oxygen demand (COD) removal performance of all the alternative processes was similar where the highest removal was only 5%. On the other hand, color removals were much better; ranging from 15 to 100%, even with single MF. Comparison of all the process alternatives revealed that, single MF (0.45 microm), as the simplest process, is the most suitable pre-treatment method for the acid dye bath wastewaters.
Subject(s)
Acids/chemistry , Coloring Agents/chemistry , Waste Disposal, Fluid/methods , Water Pollutants, Chemical , FiltrationABSTRACT
The occurrence of trihalomethanes (THMs) in the water supply in the Ankara, Turkey was investigated. Total THMs and total organic carbon measurements were carried seasonally in the samples collected form 22 different districts along with the samples taken from the Ivedik Water Treatment Plant serving 90% of the city. The average summer nonpurgeable organic carbon (NPOC) concentration in the raw water was 4.2 mg/L, and the NPOC removal achieved in the treatment plant was 31%. The concentration of total THMs ranged from 25 to 74 microg/L, from 28 to 73 microg/L, and from 25 to 110 microg/L in winter, spring, and summer, respectively. In all of the samples chloroform existed at the highest concentrations, while bromoform was almost absent. The total THM concentrations were highest in summer for all districts. However, none of the concentrations detected exceeded the USEPA's Stage I limit of 80 microg/L and the EU's limit of 100 microg/L. However, the total THM level in 64% of the districts exceeded the USEPA's Stage II limit of 40 microg/L. The risk estimations carried out indicated that each year 1 of the 5 million Ankara residents could get cancer from the daily intake of water, mainly because of exposure to chloroform through oral ingestion.
Subject(s)
Disinfection/methods , Neoplasms/etiology , Trihalomethanes/analysis , Trihalomethanes/poisoning , Water Purification , Environmental Monitoring , Humans , Risk Assessment , Seasons , TurkeyABSTRACT
The effectiveness of granular activated carbon (GAC) adsorption for the removal of natural organic matter and trihalomethanes from Ivedik Water Treatment Plant of Ankara City is investigated. Freundlich Isotherm constants K and n were determined as 17.61 and 1.66, respectively. Bench-scale GAC columns were run with empty bed contact times (EBCT) varying from 0.40 to 2.67 min to evaluate adsorption performance. 50% exhaustion values were used for comparison. The treated volumes of water increased with EBCT, showing a linear increase in GAC service life. Correspondingly, the carbon usage rate decreased. The capacities calculated by the isotherm equation and achieved by columns were also compared. The column capacities were within 43-65% of the isotherm capacities at complete breakthrough. However, they were only within 8-17% of the isotherm capacities at 50% breakthrough.
