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A. In drinking water treatment, the two mechanisms important in the coagulation process are: ~harge'--../ neutralization and bridging b. filtration and cation exchange c. osmosis and electrostatic repulsions d. aggregation and s~.!!!i!!g
B. The single-most important purpose of secondary treatment is the: a. Removal of suspended solids b. Removal of phosphorus r'2Removal of BOD
'a:Conversion of ammonia to nitrogen gas
C. The main chemical species typically responsible for the alkalinity of natural waters are: a. HSiOL HZP04', HP04Z- @03Z', HC03', OH' c. Caz+,Mgz+,Fez+ d. HC03', Cl', HS'
D. The Ju!rpose of a comminutor is to: ( a. ~educe large materials to smaller sizes b.'Remove suspended particles and organic material c. Remove discrete particles d. Dampen diurnal flow variations
~eaSing the ultimate BOD in a stream is likely to result in what? (Mark all
a. A decrease in the critical time C§:!An increase in the critical time ## C9 decrease in the critical DO level d. No change in the DO deficit . e. A decrease/^ in kl^ -^ ettQ^ )<. decrease in kz - _Y{.1'1eN_ ### 2. (20 points) Draw a schematic of a traditional wastewater treatment plant that ### includes unit processes for preliminary treatment, primary treatment, secondary ### treatment, tertiary treatment, and sludge stabilization. Label the specific unit ### processes. Below the figure, provide one sentence for each unit process that ### accurately describes what the process removes and how it works. w?'.rf0' _:J C-'-'v 12'\ eel.._ - "N"-CL 5 "? \;~,\', IJ'ff 0""''' L _"/\~;'V\.'(J_ .&-1' J I _06'_ ,',t"A. \ _11' ,. \'J, , ,_ b9v ,/' _Y {vv'o s-:_ -e. \ c.. to _1V\' ~_ ).A) ty, Z. ld-- _oy~""_ ~St'~\~~ \~~\~,\. _@J_ o,vvv-.j [U\'Wv\ '. _vV"'?"-_ e...r v l?-Ij V'£. " {V\,<- _,/'\1 W. 'IV-V_ ### 4. (15 points) - You are designing a drinking water treatment plant for the city of ### Zioroda. For the settling tank, you have a design flow of 0.036 m3/s and the settling ### velocity of your particles is 22 m/day. Your boss tells you that the length:width ### ratio of your tank should be 2:1 and the retention time should be 2.5 hours. If your ### goal is to remove 100% of the particles in the clarifier (settling tank), what should ### be the dimensions of the clarifier? _'N ~_ 0·1\ YV\ -------fs L-,.lv"OVV) -t l-\/ _/ / CJUJJ (-\ Vo. V( .., _D.ow254\.9 ---_ /t: ·t( **5. (20 points)** Water with the following chemical characteristics is to be softened. The quicklime (CaO) used to soften is 95% pure and the soda ash is 96% pure. How much quicklime (CaO) and soda ash (NazC03) are required if we only need to treat carbonate hardness? ==- Report in g per million gallons of treated water.- Component C Ca2+ Mg2+ Na+ HCO~ 8042 - Cl- mg/L 7 70 18. 18. 195 48 21. f/W 22- 40/2 -, 2Q 24-.3/<> < l;zl~ 22.'1< (9\ qu-/;2 - <j'D 2>~. s- ### Note: The equivalent weight of C02 is 22 mgjmeq, quicklime is 28 mgjmeq, and ### soda ash is 53 mgjmeq. Soften to the solubility limit (1.25 meqjL CaO excess). -=~ _____ ~L--- _^ _M~j_^ __ .9'¢"~C'L(,"""\U 0vdC\ _~_ /;22-- < _0,:;>\_ ' Ti/;/zo ---3. ~ ICI (^) /(p\<;/ ~ (^3). _'_ (L. **\<\** _mejll-- (21'0_ m~,yq) K _( ~ Z'"_ 4 3~\ ) ( ~ ~ 3 "'5) " ### 3 \/'/.;:; (g:J C'-l. ) u.~l _>t_ (0-/.9 ::%:\'Y\\..\\ - 0-r> 9;' \ oj- q "'\..01£. L-V.V\ C _(Cf ~_ 7. --t:1lA..- e... ) ;l. fY\ vJ '- _C av-f'-L.-_ {..V -tveClt' @ _x-\"{\_^ _2- U_^ '05^ _x-_^ (O-lP^ _!J<_ -lJ"vv" 'J _c.L of_ qIACU<- (,vYV..-(, _(f>r_ q ~ 7 \?lA / J.,; -t; I) _Ole_ T (}l-J _(F iOJ_ -7 _FVp,-_ <. )
