"DESIGNING TO REMOVE PHOSPHORUS BY USING
METAL SALTS AND POLYMERS IN CONVENTIONAL PLANTS"
James E. Laughlin, P.E.
Note: This discussion guide supplements material in "Process
Design Manual For Phosphorus Removal". That manual is
listed (1) among references cited here.
1. What is covered here - and why?
a. Discussion covers use of metal salts and polymers in otherwise conventional
plants. Tertiary systems are not included.
b. Recent reports (2) (3) (4) (5) (6) (7) show progress has occurred.
c. Designers can - and must - proceed with positive pragmatism.
d. Material is based on fundamentals proven in plant scale operations.
e. Operational aspects are included, and deserve design emphasis.
f. Designers must be part of startup and initial operations.
2. Should you use these processes? When and Where:
a. Ignoring "the great P debate" (8) (9) (10), are these processes attractive?
Local quality standards yield the answer. Concurrent improvement
in BOD and suspended solids may be key factors.
b. Modification of existing plants is usually simple, and inclusion in new
plants is minor. Capital costs are quite low.
c. Degree of treatment dilemma: going from 80% to 95% phosphorus
removal may increase operation costs 50% or more. However, the physical
facilities are identical in either case and operational flexibility
allows choice at later time.
d. Owner's decision should be carefully made. Reduction in suspended solids
and BOD may be pivotal. Success demands his commitment to:
- 1 -
-------
...intelligent 24-hr, operation (does not mean 3 meii)
...lab support beyond conventional plant operations
...total cost increase of 1$ or 8C/1000 gal (chemicals are 5C of this).
3. Points of application: several possibilities lead to one clear choice
a. Primary clarifier ...greatest sludge yield of any variation, but
substantial reduction of subsequent biological
sludge
...escaping colloids are reduced in following units
...lowest ortho-P fraction
...50% BOD reduction appeals in overloaded plant.
b. Biological unit ...trickling filter may blotch and slough but won't
plug. However, not an effective point of
application. Offers no advantages over other choices.
...contact stabilization modification proposed (11)
...MLSS provide great sorptive area and biofloc-
culation reduces amount of chemical required
...aeration tanks afford flocculation and detention;
can add at middle or near end, but enroute to final
clarifier is most popular
...effect of metals on MLSS biota still unclear (12)
but apparently not detrimental
...large MLSS floe may agglomerate and this could reduce
exposure of active biota and impede transfer of
oxygen, offgases, and substrate
...nitrification may be suppressed by pH shock.
- 2 -
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c. Final Clarifier ...loss of control here means poor effluent in a hurry;
but quite effective and reliable in practice
...stearic hindrance of detergents reduced here
...ortho-P predominates, and is desired form
...underflow stimulates primary settling if
returned there in trickling filter plant
...activated sludge unit has far more solids
handling capacity, but has more load too
...fairly high chemical demand because must add
enough to complete precipitation, coagulation
and glue suspended solids together.
d. Multipoint facilities: inexpensive approach to effective performance
...allows total feed to any of several points
...permits split feed, a popular approach at
several plants.
4. Trial efforts: How big and how long? A bold approach is justified
a. Jar test (13) ...a vital but treacherous ally
...auxiliary flash mix for thorough dispersal
...stator is key accessory, an assembly of plastic
fins
...hydraulic similitude by eyeball (stare at plant
unit then adjust jar turbulence to match)
...assume plug flow in setting agitation times
in jars
dynamic "settling" is a must (5-8 rpm)
...practice, practice, practice.
- 3 -
-------
b. Other lab tests work (14) (15) but dawn comes slowly at "the sewer
plant".
c. Pilot facilities: an exercise in futility due to cost, operational
vagaries, and the perfidious scale factor.
d. Full plant (or isolated module) trial: going in style, with confidence,
without going broke. Fig. 1: typical 1.6 MGD plant in Richardson,
Texas (16) .
5. Chemicals: who are they, what do they do, and how?
a. Available forms (17)
Metal salts: FeCl , pickle liquor, alum, and sodium aluminate
(which also provides alkalinity)... liquids are best
(cost, effectiveness, flexibility, ease of handling)
Polymers: most come dry; no universal choice; 3 categories
b. Technical Details on Coagulants
...alum (48.5% soln of filter alum is 8.25% aluminum
oxide) weighs 11.1 Ib/gal, and 4.37% of this is
available aluminum
...sodium aluminate (46% soln) is 15.1% Al by weight,
but different suppliers offer different
concentrations
...ferric chloride varies from 35% to 45% soln,
according to weather (agitated 45% soln freezes
at 45°F, and 37% soln at 15°F); 40% soln
weighs 11.9 Ib/gal, and 16.4% of that is iron
...see manufacturers' technical bulletins for
complete details on all coagulants and polymers.
- 4 -
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»LUO«C a *CCI*CU.ATIO«
EFFLUENT
JUNCTION FINAL
OK CLARIFIED
J&'
^^ (UHNMTCD)
DRYINO
I I I I
TMKKLINC
FILTERS
Primary Clarifier No. 1
2
3
All Primary Clarifiers
Final Clarifier
Filter No. 1
2
Filters Combined
Digester No. 1
2
3
Digesters Combined
Diam
(Ft)
40
40
40
70
84
120
40
40
40
Depth
(Ft)
8
10
10
6
6.5
6.5
14.3(2)
14.3(2)
14.3(2)
Circum
(Ft)
126
126
126
378
220
Area
(Sq Ft)
1257
1257
1257
3771
3848
5542(D
1131od)
16852(]-)
1257
1257
1257
Volume
(Cu Ft)
10,054
12,570
12,570
35,194
23,088
36,000
73,500
109,500
13,000
13,000
13,000
39,000
(Gal)
75,200
94,000
94,000
263,200
173,000
135,000
135,000
135,000
404,000
Sludge Drying Beds 12,000 Square Feet
(1) Area in acres: 0.127, 0.260 and 0.387, respectively
(2) 14.3 Effecitve, 18.0 SWD, 15.8 Clear @ Center
I TREATMENT PLANT WITH CHEMICAL PRECIPITATION FACILITIES (REF 12)
-------
c. Three key functions involved in mineral addition:
...Precipitation of ortho-P to insoluble colloid
...coagulation (destabilization) of all colloids
...flocculation (agglomeration) of destabilized
colloids
d. Precipitation: reactions and kinetics (18)
...solely by metal salts
...produces metal phosphates, of some sort (19) (20)
...fast, essentially complete in one second
...pH will be depressed; 6.5 good value, but watch
to see alkalinity in effluent is 50 mg/1
...polyelectrolytes not involved, defer their addition.
e. Coagulation: reactions and kinetics (21)
...key developments in coagulation: reduction of
surface charge on hydrophobes, dehydration of
water layer on hydrophyls (same as water treatment)
...coagulation competes with P-precipitation for metal
species
...metal coagulation very rapid: one second
...metal radicals are complicated, probably
polymerize into complicated transient forms (22)
...polymer coagulation less rapid: seconds to minutes,
and it should not be started until metal reaction is
through; allow lag time of 2 to 5 minutes
...homegrown polymers have obscure role (23) (24)
they are generated during biological treatment.
- 5 -
-------
f. Flocculation: reactions and kinetics
...flocculation proceeds languidly thru decreasing
energy levels over a period of minutes; involves
both metals and polys; we can see it occur
...key developments in flocculation: glue colloids
together at moment of collision/ provide skeleton
for dense floe, act as broomstraws for sweeping
up surviving colloids.
g. Physical arrangments inferred:
...flash mix intensely for 1-30 seconds (adding metal
salt)
...high energy flocculation 1-5 minutes (add polys
near midpoint)
...low energy flocculation 5-20 minutes
...facility requirements are modest, largely inherent
in conventional existing plant.
6. Hardware: type, size, location and use (25)
a. Storage tanks
...fiberglass (filament wound or layup) from good
supplier, exceeding minimum standards (26) (27)
...natural amber, or colored tanks are attractive
...coagulant: size for 7-10 day supply on 2/1
mole ratio; approx 400 gal/MGD/day for alum
(equals 3 weeks for FeCl or aluminate); 6000
gal tank will accept 5000 gal tank truck lots
~ 6 -
-------
...tank hardware: strip or float gauge, mansized
manhole, fill inlet with snap coupling, pump
suction, vent, flush-bottom drain
...use one-inch thick polyurethane pad between slab
and tank, unless weather dictates heated pad to
keep coagulant warm
...polymer: size for 2-3 day supply of 0.5% soln;
this is 400 gal/MGD at 2 mg/1 dose. Can always
dilute below 0.5% and will probably want to
...same tank fittings as coagulant, plus overpowered
mixer for 1000 cp viscosity; fill inlet connects
to water; disperser funnel also requires water
..consider shelter for polymer units; operators
appreciate this
...auto poly dispersers available and have been
successfully used at two dozen plants; check with
equipment vendors (28) (29) (30) (31)
b. Piping
...PVC or FRP, protected from freezing as required
...provide flushing tees following pumps
...accumulators not necessary; manual air blowoffs
recommended at high points in line (using 3-way
valve, these make good sampling-calibrating ports)
...put strainers on pump suctions, and make lines
big and we11-reinforced against physical abuse
- 7 -
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...dilute poly pump discharge with about 20 gpm water,
followed by at least 50-ft run of -pipe; use jet or
turbulence section if pipe run is too short.
c. Feeding equipment
...many types of variable discharge positive dis-
placement pumps can serve: diaphram, plunger,
gear, progressing cavity
...proper selection of pump materials allows inter-
change between coagulant and polymer service
...use pumps designed for 500 psi service, put in a
40 psi backpressure valve and neglect head loss
in piping that follows
...backpressure seats check valves to improve
accuracy; double check valves are good
...don't select too large a pump: low-range control
difficult; some pumps have interchangeable heads
of different sizes
...ratio control helpful, in addition to percent out-
put control
...no problems in calibration and recalibration;
pump water for original curve, then chemical solution
...pumpage record often based on operator's log
...Fig 2: another approach: gravity flow; use mag
meter, T-I-R and air or electric throttling valve
...Fig 3: any system should include or adapt to auto
control; can go as far as compound loop system
- 8 -
-------
STORAGE
TANK
T-hR
SETPOWT
CONTROLLER
FEED
POINT
MAG METER
FIG2 GRAVITY CHEMICAL FEED SYSTEM
CHEMICAL PUMP CONTROLLER
I
INTEGRATOR B SET POINT SELECTOR
I
I
FLOW METER
P ANALYZER
FIG 3 CHEMICAL FEED CONTROL BY COMPOUND LOOP
-------
if reliable P-analyzer is included; figure shows
"feed forward" system where effluent monitoring
can be used to trim base dose.
...include hose stations for washdown of spillage,
plus service as emergency shower and eye fountain
d. Chemical injection: two chemicals and two exhortations
...Coagulant: inject full strength (to prevent pre-
mature hydrolysis) into intense dispersion zone,
with one inlet pipe per mixing unit up to 8-10 MGD;
current unpublished work may open trend to
controlled predilution to enhance flash mix
operation (32) but this practice not yet established
...Polymer: have several inlet points available,
injecting a diluted stream (multiport or header
device above 3 MGD). Aim for thorough dispersion
at moderate energy levels.
e. Flash mixing: our most grevious shortcoming (33) (34)
...raw inflow requires hydraulic jump, drop box, drop
manhole, air agitation, or pump discharge; all
relatively unsatisfactory due to low energy levels
...with treated flow, use propeller or turbine
mixer, vortex unit, jet, or other devices (35)
(36) (37). Inline approach is excellent. Baffled
basin is poor choice
...Gt has little value; G is suspect because it does
not measure local intensity but use it anyway,
- 9 -
-------
supplying an input of 800-1000 for up to 30
seconds. Be prepared to adjust hardware (baffles,
etc.)
..for electrically driven mechanical mixer, calculate:
G = >/(WHP)(550) / (u) (V) , where
(WHP) is delivered water horsepower or
(KVA) (Mtr Eff) (Pwr Factor)/(0.746)
(u) is absolute viscosity, (2 x 10) (exp-5)
at 70°F
(V) is mixed volume in cubic feet
.analyzing a baffled basin (or other head loss
unit) for G:
G = \/(62.4) (H) / (T) (u) , where
H = head loss thru basin; one foot for
example
T = detention time; 31.2 seconds for
example
u = absolute viscosity; (2 x 10) (exp-5)
-V(62.4) (1.0) / (31.2) (0.2 x 10) (exp-5)
= (316 sec) (exp-1)
but (1) G value of 316 less than 800-1000 recommended
(2) Introduction of energy over a 31-second
period is inefficient when chemical reactions
are complete in 5% of that time
(3) In a drop box detaining flow for 3.12
seconds, G becomes 1000. Required volume
- 10 -
-------
of 4.5 Cu Ft/MGD (a cube with 20-inch edges)
presents design challenge.
...proper mix in aeration basin is problematical;
just put chemical in and see how it works. Cannot
analyze for G value because bubble energy not totally
spent within the hydraulic system
...in an open flash mix box, mix at front end and
leave at least threefold following volume for
future needs (e.g. controlled high energy flocculation);
Fig. 4: junction box can be modified to serve.
f. Flocculation: Special mechanisms and tankage not needed; use water
plant technology for analysis (38) (39) (40)
...high energy flocculation occurs in effluent end of
mix unit, pipe, and clarifier centerwell (or
equivalent); energy level is declining; clarifier
inlet hydraulics are critical
...low energy flocculation occurs in blanket near
clarifier inlet; donut may be extensive with
activated sludge; extra baffle may be needed
...can flocculate in last section of activated sludge
aeration tank, and in pipe and clarifier inlet
which follow.
7. Dosage selection and control: key to success
a. Coagulant: here is where the money and performance are
...key parameters: mole ratio fed, and effluent P
...generally primary addition requires more than final
- 11 -
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Flow Rates
MGD
1
1.5
2
2.5
3
GPM
700
1,050
1,400
1,750
2,100
Coagulation
(Minutes)
1.42
0.95
0.71
0.57
0.48
Flocculation Time (Minutes)
High Energy Low Energy
71
81
86
28
1.91
28.6
19.1
14.3
11.4
9.5
Total
34.3
22.8
17.1
13.7
11.4
FIG 4 JUNCTION BOX MODIFIED TO FLASH MIX (REFI2)
-------
clarifier, which requires more than aeration tank;
these variations in demand relate to coagulation
because precipitation demand is relatively constant
.Fig. 5: assess P income both on hourly and daily
composite basis; if serving urban or suburban
areas, expect high P income on Saturday, low on
Sunday, typical on weekdays
.convert Ib/day to Ib-mole/day; set mole ratio at
2/1 or 1.5/1; factors are 31 for P, 27 for Al, and
56 for Fe; typical calculation would be:
If Phosphorus Income (As P) is 310 Ib/day:
310/31 = 10 Ib-moles/day
If Desired Mole Ratio (M/P) is 2/1:
(2/1) (10) = 20 Ib-moles metal required
Using Liquid Alum:
(20) (27) = 540 Ib Al required
(540) / (11.1 Ib/gal) (4.37% Al)
= 1100 gal liquid alum required
.dose rate should be varied 3-5 times per day to
meet P income at point of feeding; this is critical
.cam regulated feed control is attractive (41) (42)
.Figs. 6-7: plot effluent P to see if peaks occur,
adjust feed to correct; don't overcompensate
.Fig. 8: keep varying coagulant feed until reaching
desired P removal; stay on a given schedule at
least 5 days (giving scant weight to the first).
- 12 -
-------
18
9
to
^
o
(C
o
Q.
tf)
o.|0
I
13.8 COMPOSITE
TOTAL PHOSPHOROUS
IN PLANT INFLUENT
IDA NOON
6P
MID-
NIGHT
6A
9A
PHOSPHOROUS LOAD
IN PLANT INFLUENT
SOLUBLE
X 70% TOTAL
MID-
NIGHT
FIGS PHOSPHOROUS INCOME PLOTS (REF 12)
-------
3.0
,2.0
V)
o
K
O
X
Q.
OT
O
1.0
S
o
PLANT INFLUENT
8.9 COMPOSITE
1 I T
EFFLUENT PHOSPHOROUS
ALUM IN FINAL AI/P - 1.9/1
MONDAY, SEPT 21. 1970
LIQUID ALUM FED AT 20.5 6PH
IOA NOON
15.5 GPH 120.5
MID-
NIGHT
9A
FIG6 TOO FEW CHEMICAL PUMP SETTINGS GIVE POOR CONTROL (REF 12)
-------
3.0
e
2.0
PLANT INFLUENT
8.5 COMPOSITE
20.5 6PH
EFFLUENT PHOSPHOROUS
ALUM IN FINAL AI/P - 2.1/1
TUESDAY, SEPT 22, 1970
22.5 6PH
15.5
13.5 8PH
.20.
to
o
-------
EFFLUENT PHOSPHOROUS VS IRON DOSAGE
E 6
4
V)
§ 3
K
O
O.
w
o -
<
o
TREATMENT IN
FINAL CLARIFIER
I I
TREATMENT OF
PLANT INFLOW
o
o
8
I I
MOLE RATIO
I 2
IRON (Iff) TO PHOSPHOROUS (P)
FIG. 8 STUDY OF RESULTS ALLOWS SELECTION OF DESIRED MOLE RATIO
-------
b. Polymer: usually improves solids capture; may reduce metal salt
demand enough to be economically attractive
...jar test several, then try in plant
...typical dose is less than one mg/1
...proper dose and dispersion: "slick fingers"
test (slippery feel to effluent) means overdose
or poor dispersion or both
...turbidity, by eye or instrument, is good test
...feed rate is sometimes constant, perhaps reduced
at night or interlocked with rate of wastewater
flow.
c. Sampling and analysis: clear some space in the lab, Fig. 9
...analyses for conventional treatment are continued
...coagulant analysis involves both anion and cation
...alkalinity is optional, unless effluent level drops
to 50 mg/1
...turbidity of final effluent is good test; lab
unit or submerged disc
...observation of clarifier blanket is good control
tool
...P analysis can be automated;- daily composite also
required, and is main test in stable operation.
8. Sludge harvesting and disposal
a. Clarifiers: make it drop like a rockand stay there
...be conservative in design: min 9-ft SWD for
trickling filter plant, 12-ft for activated
- 13 -
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ANALYSES FOR
CONVENTIONAL TREATMENT
FLOW
TTVT QfM
TnT wni <^i
SUS SOL
Cl 1C MTU GTtf
OUo VvLoUL.
SET SOL
BOD
DO
ron
PH
TEMP
R
A
W
P
R
1
M
E
F
F
F
L
T
E
F
F
F
1
N
A
L
E
F
F
R
E
C
1
R
C
S
L
U
D
G
E
S
U
P
E
R
N
A
T
ADDITIONAL ANALYSES FOR
CHEMICAL TREATMENT
PHOS
ALK
FE
AL
S04
CL
TURB
R
A
W
P
R
1
M
E
F
F
F
1
L
T
E
F
F
F
1
N
A
L
E
F
F
R
E
C
1
R
C
s
1
u
0
G
E
S
u
p
E
R
N
A
T
FIG 9 CHEMICAL PRECIPITATION INVOLVES ADDED LABORATORY ANALYSES
-------
sludge, 500 or 600 gpd/SF based on average flow;
900 to 1100 gpd/SF on peak flow; good inlet system
is important (try reaction jets or energy
dissipating centerwells); tube settlers are working
well
...preserve blanket, if possible, to serve as solids
contact process; keep recirculation low in
trickling filter plant; in activated sludge, have
rapid sludge removal capability but throttle down
as much as possible.
...floe is a good tracer, can indicate modifications
...modification can improve existing units (43).
b. Sludge treatment and disposal: the ever-present residue, but twice
as much?
...expect good digestion, good gas production
...amt additional sludge depends on operation
percent solids should be higher than conventional;
will probably gravity thicken better, but treat
thickner overflow with suspicion; sludge volume
can vary from slightly less than to double previous
volume
...typical weight (Ib/million gal) when treating in
aeration tank or final clarifier:
Act.SI. HRTF SRTF
Primary Sludge 1000 1000 1000
Biological Sludge 1000 500 100
Chemical Sludge 500 500 500
Increase from chemical 25% 33% 50%
- 14 -
-------
...when treating in primary clarifier expect:
50% more total pounds in activated sludge
(with less secondary sludge), and 75% more
total pounds in trickling filter plant
...be courageous with digesters (often over-
designed or underoperated anyway); provide
heat and mix; consider thickening but treat
overflow suspiciously; P will stay bound in
sludge but supernatant will include colloidal
P; consider operation toward high-rate range
...chemical cost for vacuum filter or centrifuge
should be reduced in raw or digested sludge
dewatering
...on drying beds: Fe sludge does better than Al
which does better than conventional; drying time
may be halved; don't draw beds too deep, and
replace sand attrition for clear sweet underflow
9. Supernatant, Rogue Pollution, and other happy thoughts
a. Simple supernatant systemthat works
...fill-and-draw tanks; can be modified for
continuous service
...Al/P dosage of 2/1, plus 20 minutes air, then
settle
...draw sludge to beds or digesters; return clear
water to head of plant
- 15 -
-------
...coagulant costs 0.2C/1QOO gal total plant flow
...lime may permit some ammonia stripping.
b. Iron leakage: a new form of pollution, especially in trickling filter
plants
...Fig. 10: treating in final is worst
...polymer reduces escaping colloids
...Figs. 11-12: iron is reduced thru plant, when
added in primary.
c. Other radicals may be pollutants too; impact depends on local
situation
...one pound Al (III) as alum adds 5.35 Ib sulfate
...one pound Al (III) as aluminate adds 0.85 Ib
sodium
...one pound Fe (II) as chloride adds 1.26 Ib
chloride
...one pound Fe (III) as chloride adds 1.91 Ib
chloride
...one pound Fe (II) as sulfate adds 1.72 Ib sulfate
...one pound Fe (III) as sulfate adds 2.58 Ib sulfate
10. Costs
a. Capital investment: $3 to $5 to $7/capita, or about 2C/1000 gal
...FRP tanks: $l/gal up to 1000; 60
-------
10
e
~ 8
I-
u
_i
It 6
Ul
z
§ 4
IRON LEAKAGE IN PLANT EFFLUENT
WHEN TREATING IN
FINAL CLARIFIER
WHEN TREATING
'PLANT INFLOW
Q8 1.0 1.2 1.4 16 IS 2.0 2.2 2.4
MOLE RATIO- Fe (ED/P
I-
z
UJ
UJ
P I
IRON LEAKAGE WHEN TREATING PLANT INFLOW
o
IRON LOST IN
EFFLUENT
W/0 POLYMER
o
IRON LOST IN EFFLUENT
"W/POLYMER IN FINAL
CLARIFIER
0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
MOLE RATIO- Fe (IH)/P
FIG 10 IRON LEAKAGE MAY BE A PROBLEM, POLYMER CAN HELP
-------
PRIMARY
EFFLUENT
8.9 mg/l
35% REMOVAL
FILTER
EFFLUENT
5.8 mg/l
64% REMOVAL
FINAL
EFFLUENT
3.2 mg/l
IRON (TJI) LEVELS WITHIN PLANT
DURING TREATMENTS PRIMARY CLARIFIERS
PLANT IN FLOW-0.85 mg/l Feb 10-Mar 9,1971
FIG
IRON REMOVAL WHEN FEEDING Fe Cl, TO PRIMARY (REF 12)
-------
to
I"
ui
o
o
o
UI
111
EFFECT OF IRON
FED TO FINAL Ft/P-233
TUE.2FEB.I97I
LIQUID
IRON AT IIGPH
I46PH
IIGPH
8 6PH
PHOSPHOROUS (P)
1131
NOON
6P
MID-
NIGHT
6A
EFFECT OF IRON (HI)
FED TO PRIMARY F«/P- 1.9
THURS.4 MAR, 1971
NOON
MID-
NIGHT
FIG 12 IRON MAY PERFORM BEST IN PRIMARY (REF 12)
-------
controls, electric gear, shelter, etc.:
estimate according to situation
...ratio of material/labor is high in these facilities
...capital costs are small part of total
b. Chemical costs: here's where the money is
...liquid alum (48.5% soln) at 24<=/lb Al; add
freight (12
-------
REFERENCES
1. "Process Design Manual For Phosphorus Removal," Black Si Veatch, Consulting
Engineers, sponsored and published by U. S. Environmental Protection Agency,
Oct., 1971.
2. "Phosphorus Removal - The State of the Art," Nesbitt, J. B., Jour. WPCF,
May 1969, p. 701-13.
3. "Phosphorus Removal - Past, Present, and Future," Hall, M. W., and
Engelbrecht, R. S., Water and Wastes Engrg., Aug. 1969, p. 50-3.
4. "Phosphate Removal: Summary of Papers," Scalf, M. R., et al, Jour. SED,
ASCE, Oct. 1969, p. 817-27.
5. "Wastewater Treatment and Renovationstatus of Process Development,"
Stephan, D. G., and Schaffer, R. B., Jour. WPCF, Mar. 1970, p. 399-410.
6. "Soluble Phosphate Removal in the Activated Sludge ProcessA Two Year
Plant Scale Study," Long, D. A., et al, 26th Purdue Ind. Waste Conf., 1971.
7. "Phosphate Removal by Mineral Addition to Secondary and Tertiary Treatment
Systems," Directo, L. S., Miele, R. P., and Masse, A. N., 27th Purdue Ind.
Waste Conf., 1972.
8. "ABCs of Cultural Eutrophication and its Control," Sawyer, C. N., Water &
Sewage Works, Sept. 1971, p. 278 et seq.
9. "Listen! Phosphate Removal Isn't the Answer," Kappe, S., Water and
Wastes Engrng, April 1972, p. 38.
10. "Mr. Kappe is Wrong," Gulp, R., Water and Wastes Engrng., Aug. 1972, p. 40.
11. "Chemical Flocculation of Microoorganisms in Biological Waste Treatment,"
Tenney, M. W., and Stumm, W., Jour. WPCF, Oct. 1965, p. 1320.
12. "The Microbiology of an Activated Sludge Waste-Water Treatment Plant
Chemically Treated for Phosphorus Removal," Ung, R. F., and Davis, J. A.,
26th Purdue Ind. Waste Conf., 1971.
13. "Floe Volume Concentration," Camp, T. R., Jour. AWWA, June 1968,
p. 656-673.
14. "Coagulation Testing: A Comparison of Techniques - Part I," Te Kippe,
R. J., and Ham, R. K., Jour. AWWA, Sept. 1970, p. 594-602.
15. op. cit., "...-Part 2," Oct. 1970, p. 620-628.
16. "Modification of a Trickling Filter Plant to Allow Chemical Precipitation,"
Laughlin, J., Proc. Adv. VJaste Treat, and Water Reuse Symp., EPA, Dallas,
Texas, Jan. 1971.
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17. "Coagulants for Waste Water Treatment," Chem. Engrg. Prog., Jan. 1970, p. 36.
18. "Kinetics and Mechanism of Precipitation and Nature of the Precipitate
Obtained in Phosphate Removal from Wastewater using Aluminum (III) and Iron
(III) Salts," Recht, H. L., and Ghassemi, M., Water Poll. Control Res.
Rep. 17010EKI 04/70, FWQA, April 1970.
19. "Chemistry of Nitrogen and Phosphorous in Water," AWWA Committee, Jour.
AWWA, Feb. 1970, p. 127-140.
20. "Phosphate Removal: Summary of Papers," discussion by Theis, T. L., et al,
Jour. SED ASCE, Aug. 1970, p. 1004-9.
21. "State of the Art of Coagulation," AWWA Committee, Jour. AWWA, Feb. 1971,
p. 99-108.
22. "Aluminum and Iron (III) Hydrolysis," Bilinski, H., and Tyree, S. Y.,
Jr., Jour. AWWA, June 1971, p. 391-2.
23. "Colloids Complicate Treatment Processes," Dean, R. B., Envir. Sc. and
Technol., Sept. 1969, p. 820-4.
24. "Chemical Interations in the Aggregation of Bacteria Bioflocculation in
Wastewater," Busch, P. L., and Stumm, W., Envir. Sc. and Technol.,
Jan. 1968, p. 49-53.
25. "Water Quality and Treatment," AWWA, 3rd ed., McGraw-Hill Book Co.,
New York, 1971, p. 66-159.
26. "Custom Contact-Molded Reinforced-Polyester Chemical-Resistant
Process Equipment," NBS Voluntary Product Standard PS 15-69, U.S. Dept.
of Commerce, Govt. Printing Office, Cat. No. C 13.20 2:15-69.
27. NBS Voluntary Product Standard, PS 15-69 Series, covering filament
wound fiberglass products, scheduled for release fall 1972.
28. "Automatic Volumetric Chemical Mixer," chemix Corp., Troy, Mich., 1969.
29. "Series 85.600 Polyelectrolyte Feeding System," Wallace & Tiernan, Inc.,
Belleville, N. J., 1971.
30. "Polypak Packaged System for Dry Polymers," Ref. 28.20-1, BIF, A Unit of
General Signal Corp., Providence, R. I., 1972.
31. "Polymer Feeder Handbook," Calgon Corp., Subsidiary of Merck & Co., Inc.,
Pittsburgh, PA., 1972.
32. Private communications with David Griffith of Phoenix, Ariz, and Don
Walker of Aurora, 111. Publication of their work due in 1972.
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33. "Rapid Mixing in Water Treatment," Vrale, L., and Jorden, R. M., Jour.
AWWA, Jan. 1971, p. 52-8.
34. "Turbulence in Aeration Basins," Kalinske, A. W., Ind. Water Engrg.,
March 1971, p. 35-8.
35. "Mixing Theory and Practice," ed. by Uhl, Vincent W., and Gray, Jos. B.,
Vol. 1 (1966), Vol. 2 (1967), Academic Press, New York, 1966-7.
36. "Liquid Mixing and Processing in Stirred Tanks," Holland, F. A., and
Chapman, F. S., Reinhold, New York, 1966.
37. "Guide to Trouble-Free Mixers," Penney, W. Roy, Chem. Engrg., June 1,
1970, p. 171-180.
38. "Design of Mixing and Flocculating Basins," Hudson, H. E., Jr., and
Wolfner, J. P., Jour. AWWA, Oct. 1967, p. 1257-67.
39. "Determination of Optimum Velocity Gradients for Water Coagulated with
Polyelectrolytes," Hemenway, D. R., and Keshaven, K., Water & Sewage
Works, Dec. 1968, p. 554-9.
40. "Turbulence and Flocculation," Argaman, Y., and Kaufman, W. J., Jour.
SED ASCE, Apr. 1970, p. 223-241.
41. "Phosphate Removal from Municipal Sewage," McAchran, G. E., and Hogue,
R. D., Water & Sewage Works, Feb., 1971, p. 36-9.
42. "Model 40 Programmed Controllers," Bull. D-12A, The Foxboro Co., Foxboro,
Mass., 1968.
43. "Improved Settling Tank Efficiency by Upflow Clarification," Sparham,
V. R., Jour. WPCF, May 1970, p. 801-11.
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