How do you size an equalization tank for food and beverage wastewater?

Start from V = (Q peak − Q avg) × t, where V is the required equalization volume, Q peak and Q avg are your peak and average flows in gpm, and t is the number of minutes of peak-flow duration the tank needs to absorb. Add working freeboard and a documented safety margin above that calculated minimum.

How do you set a polymer dose for a dewatering system?

Run a jar test on the actual wastewater stream. Dairy, beverage, and other food-processing solids and fat content shift the optimum polymer dose meaningfully plant to plant, so a catalog default dose is a starting point for the jar test, not a design value.

What happens if an EQ tank is undersized?

Downstream equipment sees swinging, unstable flow instead of a steady stream. That typically drives up polymer/coagulant usage and makes dewatering performance less predictable — a documented, publicly filed California Energy Commission grant record for a food and beverage plant states exactly this problem and funds a properly sized EQ tank as the fix.

Free worksheet / Food & beverage wastewater

Polymer Feed & EQ Tank Sizing Worksheet

For dairy, plant-based beverage, and other food-processing wastewater: fill-in equations for equalization (EQ) tank working volume and polymer feed rate, plus a materials checklist, ahead of a dewatering upgrade. Fill it in before you size a feed pump or order a tank, and you'll have the numbers a supplier needs to quote the package in one pass.

✓The 10 inputs to collect: peak/average flow, production cycle, influent TSS/BOD, solids characteristic, retention time, polymer type, footprint
✓Fill-in equations for EQ tank working volume, polymer dose and feed rate, and a feed-pump turndown check
✓Equipment checklist: EQ tank, polymer feed system, feed pump, flowmeter, dewatering unit and control-panel interlocks
✓Layout & commissioning checklist: injection point, dilution water, overflow path, filtrate return, jar-test re-verification

Built for process and design engineers, food-plant environmental and maintenance managers, and anyone specifying a dewatering or EQ tank upgrade.

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What's inside, in brief

An undersized EQ tank drives up chemical usage. When flow into a downstream dewatering step swings instead of running steady, a polymer dose tuned for average conditions either underperforms during a spike or overdoses during a lull — both waste chemical. The worksheet starts from the working-volume math:

EQ tank working volume

V = (Q peak − Q avg) × t

V = required equalization volume, gal · Q peak / Q avg = peak and average flow, gpm · t = minutes of peak-flow duration to absorb. Add working freeboard and a documented safety margin above the calculated minimum.

Polymer dose & feed rate

F = (Q × D × 8.34) ÷ (C × SG × 60)

F = feed pump rate, gph · D = design dose from a jar test, mg/L · C = active polymer fraction from the supplier's data sheet · SG = specific gravity of the delivered product. Run the dose from a real jar test on your stream — dairy/beverage solids and fat content shift the optimum dose plant to plant.

Feed pump turndown check

F_peak ≤ P_max and F_min ≥ P_max ÷ TD

P_max = pump's rated maximum output at your discharge pressure · TD = the manufacturer's published turndown ratio. A screw-press-fed dewatering cycle runs on batches, not a flat rate — check the real min/max, not just the average.

Worked setting. A public California Energy Commission grant record for a dairy and plant-based beverage plant states this exact problem: an undersized EQ tank "resulting in increased chemical usage and unstable wastewater flows that require more energy-intensive treatment operations." The funded fix pairs a dewatering screw press with a properly sized equalization tank, a polymer feeder, a feed pump, a flowmeter, and a control panel. Read the full EQ tank & polymer feed guide.

Draft Proposal Worksheet, not a procurement-ready specification. Final sizing, materials and control strategy are the engineer of record's call and must be confirmed against the project's design documents, jar-test results, and each manufacturer's published data.

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James Riggins

LibertyCES — Liberty Chemical Equipment & Supply

One supplier for the EQ tank, polymer feed system, feed pump, flowmeter and dewatering package, with submittal-ready cut sheets and "or equal" comparisons. No charge to review a spec before it's issued.

(559) 395-5500 ·james@libertyces.com ·sales@libertyces.com ·libertyces.com

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