Paques BIOCYCLONE^™ reduces sand cleanouts at a dairy manure RNG site

This site operates four CSTR digesters with a total working volume of about 9 million gallons. Feed manure slurry was managed around 8.1–8.5% total solids to maintain ability to pump.

Despite operational controls, inert solids remained a major burden:

• 6–8 feet of sand buildup in the manure feed pit
• Fiber separation plugging occurring weekly or biweekly
• 15-20% of operational volume of digesters replaced by sand, reducing effective working volume
• Frequent third-party de-sanding, reported at a cost of $1.2M per year
• Cleaning events that could take days to weeks, depending on the unit and location

However, the real impacts were not limited to not labor and contractor cost, but also capacity loss and wear on downstream equipment. Therefore, the site focused on removing heavy inerts before they became a shutdown driver or diminished capacity.

A cyclone principle, engineered for manure and digestate slurries

Paques BIOCYCLONE^™ uses the same separation physics operators know from hydrocyclones. Using centrifugal force, inert solids separate through differences in specific gravity and particle size.

However, Paques BIOCYCLONE^™ is designed for high-solids slurry variability and selective removal of heavy inerts.

What’s different versus a generic hydrocyclone

In many hydrocyclone configurations, the underflow discharges through the apex to an open outlet, often near atmospheric conditions. That “free discharge” is a common benchmark, but it limits how precisely you can control underflow behavior on changing digestate and resulting solids discharge liquid portion as well as the sizing of hydrocylones.

Paques BIOCYCLONE^™ controls solid discharge, using:

• A heavy-duty discharge valve to manage the bottom outlet
• Proprietary internals to stabilize the flow field and enhance separation
• VFD speed control plus timers to tune how often, and how long, underflow is discharged

As a result removing sand and grit while also minimizing volatile solids loss.

Small footprint, low-disruption integration

For this dairy RNG facility, Paques BIOCYCLONE^™ was installed as a sidestream “tank dialysis” unit:

1. Pull from the manure pit via a high-solids feed pump
2. Separate heavy inerts in the BIOCYCLONE^™ vessel
3. Return clarified manure back to the pit
4. Discharge concentrated grit on a controlled cycle

This approach avoided rerouting the full plant influent and reduced integration scope demonstrating ability to retrofit into operating facilities where uptime matters.

Paques BIOCYCLONE^™ delivered high solids underflow and stable clarification:

Operational impact

Because wasting is controlled and underflow is thickened, the site also reduced water burden over approaches that rely on heavy dilution.

If you are dealing with bedding sand, grit, or recurring cleanouts, a short assessment can clarify fit and timing. Contact Paques experts to discuss:

• Where grit enters and settles on your site
• Expected installation scope and set-up time
• The business case, based on avoided cleanouts and reduced wear