White River Resource Recovery Facility (WRRRF)

Our training plant. It is fictional: every number on this page was made up for teaching and does not describe any real utility.

Fictional training plant

White River Resource Recovery Facility (WRRRF) is a made-up plant in central Indiana on the White River. It has the equipment, data and problems of a real 8.0 MGD plant, so operators can practice on it without risk. Our classes, manuals and calculators all use it.

8.0 MGDdesign average flow

6.4 MGD2025 average flow

24 MGDdesign peak hour

72,000people served

4 trainsMLE activated sludge

4 x 90 ftsecondary clarifiers

3 x 60 ftanaerobic digesters

Class Bbiosolids, land applied

Process: conventional activated sludge with Modified Ludzack-Ettinger (MLE) biological nitrogen removal, chemical phosphorus removal (alum), UV disinfection, mesophilic anaerobic digestion with CHP, centrifuge dewatering, Class B land application. Built 1978; upgrades 1998, 2014, 2026. Staff (fictional): 12 operators (24/7 coverage), 5 maintenance, 2 lab, 1 I&C technician, superintendent, assistant superintendent.

Process flow

How we use the plant in class

Every exercise follows the same five steps, the way a good operator works a problem on shift.

ObserveWhat do you see? Blanket depth, foam, color, the settleometer, the trend screen.
VerifyIs the data right? Check the meter, the sample, the lab bench sheet and the field reading.
CalculateRun the numbers: SVI, SRT, loads, state point, polymer dose.
DecidePick one change, sized to the math, within your procedures and your authority.
RecheckDid it work? Set a time to look again, and write down what you did and why.

Try it on the September storm. On Monday, September 14 the blankets are at 6 to 7 ft and effluent TSS is 28 mg/L. Load the Sunday night peak hour (about 21 MGD) in the clarifier calculator: the model predicts thickening failure at that day's RAS, which is how the blanket got so high. Then load September 14: at 10.2 MGD and 5.2 MGD of RAS both checks pass, so the blanket should come down. Recheck: it was back to 2 to 3 ft by September 17 and 18.

Open the clarifier calculator

The process units

Headworks

4 influent pumps, 24 MGD firm capacity
2 multi-rake bar screens, 1/4 in openings
2 vortex grit chambers, 16 ft
Flow: 24 in Parshall flume (FIT-100)

Primary clarifiers

4 x 65 ft, 9 ft side water depth
Overflow rate 603 gpd/sq ft at design
Removes about 32% of BOD and 60% of TSS
Primary sludge 1.2% solids

Activated sludge

4 trains: anoxic zone, then a plug-flow aeration basin
Aeration volume 3.6 MG; MLSS 2,500 to 3,500 mg/L (design 3,000)
SRT 10 to 14 days aerobic; SVI 80 to 150 mL/g, target under 130
4 turbo blowers (3 duty), ammonia-based aeration control
Alum for phosphorus removal

Secondary clarifiers

4 x 90 ft, 14 ft side water depth, 25,447 sq ft in all
Overflow rate 314 gpd/sq ft at design, 943 at peak hour
Suction header (Unitube) sludge collectors
RAS: 5 pumps of 2.0 MGD (4 duty); design RAS 4.0 MGD
Blanket target 1-3 ft (alarm at 4 ft)

UV disinfection

2 open channels, 384 lamps
Season: April 1 to October 31
Dose paced on flow and UV transmittance
Cascade step aerator for effluent DO

Thickening

Primary sludge: 2 gravity thickeners, 1.2% to 5.0%
WAS: 2 gravity belt thickeners, 2.0 m belts, 0.9% to 5.5%
GBT capture 95%, polymer 6 lb active per dry ton
40,000 gal blend tank

Anaerobic digestion

3 x 60 ft digesters at 98 F (Digester 3 being commissioned)
VA/ALK: under 0.10 normal, 0.10 to 0.30 watch, over 0.30 act
Biogas to a 300 kW CHP engine, 2 boilers and a flare
Hauled FOG and food waste up to 5,000 gpd

Dewatering and biosolids

2 decanter centrifuges (1 duty), 21 in bowl, 3,000 rpm
Cake target 24% (range 22 to 26%); capture 95% or better
Polymer about 25 lb active per dry ton
Class B cake, land applied; 120-day covered storage

Cutaway illustration of one activated sludge train, flow left to right: anoxic tank with submersible mixers, aeration basin with fine-bubble diffusers and a dissolved oxygen probe, and a secondary clarifier with a suction header sludge collector. Lines show the internal mixed liquor recycle, return activated sludge to the anoxic tank, waste activated sludge, blowers in the pipe gallery below grade, and secondary effluent to disinfection. — One activated sludge train: anoxic tank, aeration basin and secondary clarifier.

Animated diagram of WRRRF Digester 2: sludge recirculates from the digester through a chopper mixing pump and a spiral heat exchanger, hot water comes from the CHP engine and boilers, and biogas leaves the headspace through a drip trap, gas meter and H2S removal to the CHP engine, with a waste gas flare. — Digester 2: mixing, heating and gas flow.

Permit limits (fictional)

Permit IN0099991, Outfall 001 to the White River. Summer is May 1 to October 31; winter is November 1 to April 30.

Parameter	Summer	Winter
CBOD5 (mg/L)	10 monthly / 15 weekly	25 monthly / 40 weekly
TSS (mg/L)	12 monthly / 18 weekly	30 monthly / 45 weekly
Ammonia nitrogen (mg/L)	1.5 monthly / 3.0 daily max	2.5 monthly / 5.0 daily max
Total phosphorus (mg/L)	1.0 monthly	1.0 monthly
E. coli (cfu/100 mL)	125 geometric mean / 235 daily max (April to October)	Not required
Dissolved oxygen (mg/L)	at least 6.0	at least 5.0
pH	6.0 to 9.0	6.0 to 9.0

September 2026: a month of operating data

Our classes work through one month of daily data. September averaged 7.09 MGD, MLSS 2,616 mg/L, SVI 126 mL/g and effluent TSS 9.0 mg/L, but it was not a quiet month.

How White River measures SVI. The plant's SVI comes from the standard unstirred 30-minute settling test in a 2 L settleometer: SVI (mL/g) = settled volume at 30 minutes (mL/L) × 1,000 / MLSS (mg/L). Stirred and unstirred tests give different numbers, so compare only results from the same method. The calculators give training estimates; check every result against your own plant data before you change anything.

Sep 7-12. Blower B-2 out of service (bearing fault); only 2 blowers available, aeration DO averaged about 1.0 mg/L. Low-DO filaments (S. natans / type 1701) began to grow; SVI climbed from about 115 to about 150.

Sep 9 (Wed). Centrifuge polymer feed pump failed mid-shift (VFD fault). Cake dropped to 18.6% and capture to 88%; centrate TSS > 6,000 mg/L returned to headworks.

Sep 12-13 (Sat-Sun). Storm event: flow 12.8 and 14.6 MGD (peak hour about 21 MGD Sunday night). First-flush solids on Sep 13.

Sep 14 (Mon). Secondary clarifier blankets 6-7 ft, effluent TSS 28 mg/L, effluent NH3-N 3.4 mg/L (daily max exceedance above 3.0 mg/L summer limit), E. coli 260 (daily max exceedance). SVI 172. Response: RAS increased to 5.2 MGD, WAS temporarily cut, RAS chlorination considered, blower B-2 returned to service Sep 13.

Sep 15-20. Recovery: SVI trending down, blankets back to about 2-3 ft by Sep 17-18.

Sep 19-20. Hauled FOG slug (5,000 gpd each day) fed mostly to Digester 2; D2 mixing pump tripped Sep 21 (seal failure) and restarted Sep 23.

Sep 21-24. Digester 2 VA/ALK rose from about 0.04 to 0.33; boiler trip Sep 22 dropped D2 to 93.4 F; CH4 fell to about 58%. Response: stopped FOG, cut D2 feed 40% and shifted to D1, restored mixing and heat; ratio back below 0.10 by Sep 28.

Sep 29 (Tue). Centrifuge high scroll torque alarms and drop in cake solids (21.4%); polymer dose raised to 31.5 lb/dt; vibration trending up, scroll wear suspected, inspection scheduled.

Two charts of WRRRF data for September 2026. Top: SVI climbs from about 106 on September 8 to a peak near 178 mL/g on September 15, past the bulking concern line at 150, after blower B-2 was out from September 7 to 12 with DO near 1.0, while daily flow peaks near 14.6 MGD on September 13. Bottom: the clarifier sludge blanket climbs to almost 7 ft and effluent TSS to 28 mg/L on September 14, against a weekly TSS limit of 18 mg/L, then both recover by September 18. — Settling, blanket and effluent TSS through September.

Animated 30-minute settleometer test with three 2-liter settleometers side by side: WRRRF on September 3 with good settling (300 mL/L, SVI 114), WRRRF on September 14 while bulking (390 mL/L, SVI 172), and an old sludge with pin floc (215 mL/L, SVI 65 with a turbid supernatant). A timer counts the 30 minutes and a panel explains SVI = SSV30 x 1,000 / MLSS. — The settleometer on a good day, a bulking day and with old pin floc.

Line chart of the WRRRF digester VA/ALK ratio for September 2026. Digester 1 stays near 0.03 all month. Digester 2 stays near 0.04 until a FOG slug on September 19 to 20, a mixing pump trip on September 21 and a boiler trip on September 22, then climbs to 0.33 on September 23, above the act line of 0.30, and recovers below the normal line of 0.10 by September 28. — The Digester 2 VA/ALK upset after the FOG slug, pump trip and boiler trip.

WRRRF dewatering mass balance for September 1, 2026, with 97.5% capture: feed of 95 gpm digested sludge at 2.83% solids (1,345 lb/hr) and 81.1 gph of 0.25% polymer solution (23.1 lb active per dry ton) enter centrifuge Unit 1 at 3,000 rpm. Cake leaves at 24.1% solids (1,312 lb/hr dry) and centrate of about 115 gpm with about 799 mg/L TSS returns to the headworks. — One day of centrifuge dewatering as a mass balance.

Work the numbers yourself. The clarifier, SVI and pounds per day calculators load White River days with one button.

Open the operator tools

Classes that use the White River plant

Activated Sludge Process Control Indiana Class I and II Certification Indiana Class III and IV Certification Anaerobic Digestion Centrifuge Operation Using AI for Plant Performance

The White River Resource Recovery Facility (WRRRF), its permit, its staff and its data are fictional and were made up for teaching. Any likeness to a real plant or utility is by chance.

Plan training for your plant

Tell us about your plant and your staff. We will talk through the classes and the training that fit.

Call 503-701-2766 or email help@ActivatedSludge.com.