CI CI Consider a GAC system to provide protection for water customers from subsurface groundwater contamination that is migrating from a release site toward a city's well field. 5 CI H . . CI trichloroethene Identified synthetic organic contaminants 1,3-dichlorobenzene methyl ethyl ketone (aka trichloroethylene) (SOCs) in the ground water include (Fig. 1): (13DCB) (MEK) (TCE) 1,3-dichlorobenzene (2.0 ppmm), Fig. 1. Chemical structures of target SOCs methyl ethyl ketone (1.0 ppmm) trichloroethene (4.0 ppmm). Calgon F-400 GAC is to be evaluated. Adsorption capacity parameters for F-400 GAC are available from table 15-6 of MWH below. A system comprised of parallel columns, each containing two columns in series, one lead and one lag, is to be configured. When the lead column becomes exhausted with the critical SOC, it is to be removed from service for replacement or regeneration of carbon. The lag column must then become the lead column and must fully contain the mass transfer zones until the other column of the pair can be serviced and placed back into service as the lag column. The carbon columns will be cylindrical in shape. For sizing, consider the cross sectional area will be based on a superficial velocity of 5 gpm/ft?, maximum column diameter of 10 ft and minimum height equal to the column diameter. A data sheet for F-400 carbon is provided containing carbon properties. The municipal water utility will process 1.75 MGD utilizing a 16 hour production day (8 AM - midnight) 5. (10pts) Determine the time (in days) for exhaustion of a column by the suite of SOCs. (Computed exhaustion rates for the three SOCs would be additive.) 6. (10pts) Consider that GAC purchased in bulk costs $2500/ton delivered and transferred to on-site bulk carbon storage (remember each parallel set has 2 columns). Estimate the initial cost of the GAC inventory required and the yearly average cost for activated carbon, assuming all carbon is freshly manufactured as opposed to regenerated. 20 Table 15-6 Aqueous-phase Freundlich isotherm parameters K and 1 for selected organic adsorbates Tmin Name of Compound 1 pH (C) Carbon Reference Atrazine 182 0.18 20 F100 Haist-Gulde (1988) Benzoic acid 0.7 1.8 F 300 Dobbs and Carbon (1980) Chlorodibromomethane 45 0.517 11 F 400 Crittenden et al. (1985) Chloroform 15 0.47 20 F 100 Haist Gulde (1988) Cyclohexanone 6.2 0.75 7.3 20 F 300 Dobbs and Carbon (1980) Cytosine 1.1 1.6 20 F 300 Dobbs and Carbon (1980) 1,2-Dichlorobenzene 242.2 0.4 20 F 100 Haist-Gulde (1988) 1,3 Dichlorobenzene 458.8 0.63 24 F 400 Speth and Miltner (1998) 1,2-trans Dichloroethene 3.1 0.51 20 F 300 Dobbs and Carbon (1980) 2,4-Dichlorophenol 141 0.29 20 F 300 Dobbs and Carbon (1980) Ethylbenzene 53 0.79 7.4 20 F 300 Dobbs and Carbon (1980) Methyl ethyl ketone 19.4 0.295 24 F 400 Speth and Miltner (1998) N-Dimethylnitrosamine 0 0 7.5 20 F 300 Dobbs and Carbon (1980) Pentachlorophenol 150 0.42 20 F 300 Dobbs and Carbon (1980) Tetrachloroethene 218.2 0.42 20 F 100 Zimmer et al. (1988) Trichloroethene 55.9 0.48 F 400 Speth and Miltner (1998) 1.1.1-Trichloroethane 23.2 0.6 7.1 20 F 100 Zimmer et al. (1988) Additional Freundlich isotherm parameters are available in the electronic resource E5 at the website listed in App. E. Unts of K are (mg/gXL/mg)!/ Calgon Carbon Corporation, E176777706978777 un
