A new way of measuring very low concentrations of MIB allows calculation of the PAC dose needed to mitigate odors caused by MIB. Kinetic and equilibrium studies using five powdered activated carbons (PACs) and 14C‐labeled 2‐methylisoborneol (MIB) in Lake Michigan water produced guidelines for determining the dose of PAC needed to remove MIB. The equilibrium data, supported by predictions from the equivalent background compound competitive adsorption model, indicate that the percent MIB remaining at equilibrium is a function of the carbon dosage, independent of the initial MIB concentration. Kinetic experiments, analyzed in terms of the homogeneous surface diffusion model, demonstrated that the surface diffusion coefficient, Ds, is independent of both carbon dosage and initial MIB concentration. Together these equilibrium and kinetic studies show that for any given PAC dosage in natural water and for any fixed time of contact, the percent MIB remaining in an ideal reactor is independent of the initial MIB concentration. Thus the PAC dosage required to mitigate any MIB episode for any contact time of interest may be quickly determined from a Ct/C0 × 100 percent versus Cc plot. These studies have also exhibited a new application of 14C‐MIB allowing for the rapid collection of reproducible and accurate adsorption data.

Laboratory columns closely simulated the performance of a pilot plant for taste and odor control. This study developed a way to rapidly and effectively evaluate the remaining life of a granular activated carbon (GAC) bed used to mitigate taste and odor episodes. The maximum attenuation of a 2‐methylisoborneol (MIB) episode, a representative taste and odor compound, can rapidly be determined using laboratory‐scale columns packed with partially spent GAC taken from full‐scale operating adsorbers. These laboratory‐scale columns closely simulated the performance of pilot‐scale columns. The percent of a transient MIB load removed by GAC did not depend on the influent MIB concentration but did depend on the amount of natural organic matter adsorbed on the GAC surface. This approach can be used to determine GAC's potential percentage removal of taste‐ and odor‐causing compounds as a function of GAC service time. It allows GAC to be tested to estimate its readiness for summer taste and odor episodes. Adsorption alone in GAC adsorbers that used < 10 min of empty bed contact time was insufficient to fully protect against typical MIB episodes.

DISINFECTIONu sty or earth y odors, generally attribu ted to 2-m eth ylisoborn eol (MIB) an d geosm in , are th e m ost frequ en tly observed odors in water su pplies. 1 Su rveys of u tilities h ave fou n d th at th e u se of activated carbon seem s to be on e of th e m ost effective m eth ods for con trollin g tastes an d odors. 2,3 However, activated carbon is often applied with ou t a fu ll u n derstan din g of h ow oth er treatm en t ch em icals m ay affect adsorption .Th e application of ch lorin e as a part of th e water treatm en t process is still a com m on practice for disinfection , taste an d odor con trol, an d am m on ia rem oval. As a resu lt, ch lorin e is on e of th e ch em icals th at often com es in to con tact with activated carbon . Wh en free ch lorin e, m on och loram in e, an d dich loram in e con tact activated carbon , th ey oxidize its su rface an d in th e process are con verted prim arily to ch loride ion an d oth er produ cts. 4 Oxidation of th e su rface of activated carbon resu lts in a decrease in adsorptive capacity for a variety of Ex p e rim e n ts w e re co n d u cte d in n atu ral an d d e io n ize d d istille d w ate r to e stablish th e e x te n t to w h ich ch lo rin e d im in ish e s th e ability o f activate d carbo n to ad so rb 2-m e th yliso bo rn e o l (MIB). Th e au th o rs d e te rm in e d th at th e d e gre e o f re d u ctio n in MIB ad so rp tio n cap acity w as co n tro lle d by th e am o u n t o f ch lo rin e re acte d p e r u n it m ass o f activate d carbo n . A lth o u gh th e cap acity re d u ctio n w as attribu te d to th e o x id atio n o f MIB ad so rp tio n site s, th e au th o rs fo u n d th at ch lo rin e co u ld re ad ily o x id ize site s alre ad y co n tain in g MIB, th e re by re le asin g it back in to th e aqu e o u s p h ase . A sign ifican t p o rtio n o f th is lo st cap acity co u ld be re co ve re d by d ryin g th e o x id ize d carbo n . To m ax im ize th e e fficie n cy o f bo th th e ch lo rin e an d p o w d e re d activate d carbo n (PA C), co n tact be tw e e n th e ch lo rin e an d PA C sh o u ld be e lim in ate d o r m in im ize d . For executive summary, see page 175.

Summary.-Cyclophosphamide (Cy) produces an interstitial pneumonitis in CBA mice. The extent of the lung damage has been quantified by measuring the increase in ventilation rate over 6 weeks after an i.p. injection of Cy 200,250 and 300 mg/kg. A dose-dependent response was found. When a preliminary ("priming") dose of Cy at 50 mg/kg was given 7, 9 or 14 days before a single large dose of 250 mg/kg, lung damage was reduced, as shown by a smaller increase in ventilation rate than in those receiving 250 mg/kg alone, and this difference was significant (P < 0 01) in the Day-14-and highly significant (P<0-001) in the Day-7-"primed" groups. When primed less than 7 days before, there was a relative increase in ventilation rate, which was statistically significant (P <0.01) in the Day-i -primed group. Similar effects were also seen in the survival of the mice.

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