Page 795 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

750 Fundamentals of Water Treatment Unit Processes: Physical, Chemical, and Biological

Yoshinaga et al. (1995) using a laboratory chemostat Required
were measured as A similar installation using the same wastewater must
be designed with a requirement that S ¼ 15 mg=L.
^ m ¼ 0:45 h 1 Determine the depth required for the same HLR.
mg substrate 23.7 Bio-Filter Depth for Loading Increase
K s ¼ 1:88
L Given
mg cells synthesized For a trickling-filter reactor, assume HLR ¼ 0.0034
Y ¼ 0:99 3 2 2
mg substrate degraded m =m =s (5.0 gpm=ft ). Assume that S o is increased
by 50%.
and let Required
1. Estimate S for the new condition, i.e., S(S o ¼ 1.5).
mg cell mass lost
k d ¼ 0:05 2. What new depth will result in the same S as before
mg cells in reactor h
the 50% increase, i.e., S(S o ¼ 1.0)?
23.8 Bio-Filter Depth for Toluene and HLR Increase
Required
Given
1. Determine the detention time, u, for the reactor.
A biofilm filter reactor pilot plant (D ¼ 1.8 m) was
2. Calculate the sludge-wasting rate,, R , for the stated
0
developed for the treatment of toluene at 258C. The
conditions.
influent concentration is, S o ¼ 60 mg=L and the efflu-
3. The influent concentration increases to S o ¼ 95 mg=L.
ent concentration, S, was measured, S ¼ 15 mg=L.
Determine S for this new condition. 3 2 2
Assume HLR ¼ 0.0034 m =m =s (5.0 gpm=ft ).
Required
BIO-FILTERS 1. Determine the depth needed to obtain an effluent
concentration, S ¼ 4mg=L.
23.5 Bio-Filter Performance
2. For whatever depth was worked out in ‘‘1’’, assume
Given
that it becomes necessary to handle a new flow,
A trickling filter for municipal wastewater treatment, 3 2 2
giving an HLR ¼ 0.0048 m =m =s (7.0 gpm=ft ).
after primary treatment, has been in place for some
Determine the associated S.
30 years, The filter bed is 2000 mm in depth. The
BOD in , i.e., S o ¼ 200 mg=L and BOD out , i.e., ANAEROBIC
2
S e ¼ 30 mg=L; the corresponding HLR 5 gpm=ft .
2
For the diurnal peak, HLR 8gpm=ft , estimate the 23.9 Effect of Sludge Thickening on SRT
associated effluent BOD. Sketch the associated S(Z) Given
curves for each case. 3
[SS] o ¼ 4.75% [¼47.5 kg=m ]
3
Data summary [VSS] o ¼ 0.80 [SS] o [¼0.80 47.5 kg SS=m ¼ 38.0
3
D ¼ 2.0 m kg VSS=m ]
3
3
HLR(normal) ¼ 5 gal=min=ft 2 Q(solids) ¼ 40,000 gal=day [¼151.4 m =d ¼ 6.31 m =h]
3
2
¼ 0.2037 m =m =min V(reactor) ¼ 750,000 gal ¼ 2839 m 3
2
3
¼ 0.003395 m =m =s Required
HLR(peak) ¼ 8 gal=min=ft 2 If the solids inflow is increased to [SS] o ¼ 6.5% [ ¼ 65
3
kg=m ], calculate the new SRT.
2
3
¼ 0.005432 m =m =s
23.10 Anaerobic Reactor Volume and Gas Production
S o ¼ 200 mg BOD=L
Given
S e ¼ 30 mg BOD=L
An anaerobic reactor (a ‘‘digester’’) treats municipal
3
Required primary sludge. The plant flow is Q ¼ 0.044 m =s
2
S e when HLR(peak) ¼ 8 gal=min=ft . (1.0 mgd), and T ¼ 358C.
23.6 Bio-Filter Depth
Required
Given Determine
Assume the following data apply for trickling filter that 1. Reactor volume
treats municipal wastewater: 2. Rates of VSS(destroyed) and gas production
3
Q ¼ 0.066 m =s (1.5 mgd) 23.11 Anaerobic Reactor Volume with SS Increase and
Depth of reactor, D(reactor) ¼ 1.8 m VSS Destroyed
A(reactor) ¼ 194 m 2 Given
3
S o ¼ 260 mg=L Although not needed, plant flow, Q ¼ 0.044 m =s (1.0
S ¼ 30 mg=L mgd). For the problem, let the suspended solids
3
T ¼ 258C concentration be 4%, i.e., [SS] o ¼ 40 kg=m , and let