env6666exam1_solutions

env6666exam1_solutions - ENV6666 Exam 1 (DUE 2/14/11 by 10...

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1 ENV6666 Exam 1 (DUE 2/14/11 by 10 am either by email or under KOPP 220 door) Name: ____________________________ Problem Pts / 1 4.5 2 4.0 3 3.0 4 3.5 Total /15 1. (4.5 pts) We recently received a rsvp from Professor James Symons for the Legacy Dinner being held as a part of the 2011 AEESP Research and Education Conference ( aeesp2011.com ). Prof. Symons has written "The Early History of Disinfection By-Products: A Personal Chronicle" in Environmental Engineer, 37, Part I (1) 20-26 (Jan., 2001), Part II (2) 7-15 (Apr., 2001) and the popular AWWA book Plain Talk About Drinking Water . Piqued by Prof. Symons’ contribution to the field, I found an interesting paper that discusses Disinfection By Products (DBPs) found in swimming pools disinfected by either chlorine or bromine. The first page of the article is provided below along with a table of their results of various by products formed when chlorine reacts with ammonia (chloramines form) or organic matter (Trihalomethanes, THMs, form) in the water (e.g. from your perspiration). Use Table 1 (taken from the Richardson et al. article) to answer the following questions: a. (3 pts) What is the average TOTCl as mg/L and mole/L in the swimming pool water based on the concentrations given for all of the various Cl containing compounds in Table 1? Assume free chlorine is reported as mg/L Cl 2 . unit Mean MW mole/L mole Cl/mole __ mole Cl/L g Cl/mole g Cl/L mg Cl/L Free Chlorine (as Cl2) mg/L 1.28 70 1.83E-05 2 3.66E-05 70 0.00128 1.28E+00 NH2Cl mg/L 0.29 51.5 5.63E-06 1 5.63E-06 35.5 0.0002 2.00E-01 NHCl2 mg/L 0.38 85 4.47E-06 2 8.94E-06 70 0.000313 3.13E-01 NCl3 mg/L 0.1 120.5 8.30E-07 3 2.49E-06 106.5 8.84E-05 8.84E-02 CHCl3 ug/L 14.4 119.4 1.21E-07 3 3.62E-07 106.5 1.28E-05 1.28E-02 CHCl2Br ug/L 14.2 163.8 8.67E-08 2 1.73E-07 70 6.07E-06 6.07E-03 CHClBr2 ug/L 12.8 208.3 6.14E-08 1 6.14E-08 35.5 2.18E-06 2.18E-03 Avg Cl 5.42E-05 M 1.90 mg/L b. (0.5 pt) Four chief constituents (chloroform, bromoform, bromodichloromethane, and dibromochloromethane) are referred to as total trihalomethanes (Total THMs or TTHMs) for which the EPA has set a drinking water limit at 80 parts per billion in treated water. Based on the Total THMs reported, are the swimming pools violating drinking water standards?
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2 80 ppb = 80 ug/L, TTHMs from Table 1 average 49.6 ppb with a maximum seen at 75 ppb. So, the swimming pool water has not exceeded the drinking water limit (not that one intentionally jumps into a pool to drink the water). c. (1 pt) Please list two other potential human exposure pathways to DBPs from swimming pools (the page printed from the article provides some information, but you may use other sources). Inhalation of the air above the water and absorption through the skin are two other human exposure pathways to DBPs in pool water.
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4 2. (4 pts) What are the equilibrium pH values and activities of the species at equilibrium for the following systems (a-c): a. (1 pt) 5 x 10 -4 M hydrocyanic acid (HCN), where the pK
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This note was uploaded on 03/06/2011 for the course ENV 6666 taught by Professor Fuss during the Spring '11 term at Uni San Francisco de Quito.

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env6666exam1_solutions - ENV6666 Exam 1 (DUE 2/14/11 by 10...

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