What Reactor Is Best for Dairy Manure?
For dairy manure, a continuously stirred-tank reactor (CSTR) or an upflow solids reactor (USR) is the right choice, because dairy manure arrives at 8-12% total solids with bedding and sand that defeat a UASB; the CSTR or USR mixes or holds the thick slurry at 35-38 C and converts it steadily to 55-65% methane biogas. UASB is reserved for the liquid fraction only, after solids are separated out.
1. Why Dairy Manure Is a Thick Feed
Dairy manure is not a clean liquid. With bedding, sand, and straw it sits at 8-12% total solids and carries grit that sinks and inerts that do not ferment. A reactor for it must move the mass, tolerate grit, and keep biology warm. That points to CSTR (mechanically mixed) or USR (upflow, unmixed but built for solids), not to a UASB whose blanket would blind with solids.
2. CSTR vs USR for Dairy
| Reactor | Handles solids | Mixing | Best dairy use |
| CSTR | 8-12% TS | Mechanical, continuous | Whole manure, steady feed |
| USR | 8-12% TS | None, upflow | Manure with coarse feed |
| UASB | Low, soluble only | None, upflow | Separated liquid only |
3. What the Digester Must Do
At 35-38 C (mesophilic) the digester holds biomass in contact with the slurry for 20-40 days (HRT) so the volatile solids are consumed. The gas is buffered or used on site; the digestate is separated and spread. Bolted GFS tanks (200-60,000 m3, glass fused at 820-930 C) resist the acidic, H2S-bearing liquor and ship flat-pack for fast assembly on the farm.
Project Case Study
Inner Mongolia Cattle Farm Biogas Project (Wushenqi). A cattle-manure biogas plant in Ordos, Inner Mongolia, using a CSTR with a dedicated insulation system for stable digestion in extreme cold, with cattle manure as the feedstock - a delivered example of the right reactor matched to thick livestock manure.
| Project | Inner Mongolia Cattle Farm Biogas Project |
| Location | Ordos City, Inner Mongolia, China |
| Industry | Livestock / Cattle Farm |
| Application | Dairy-relevant manure digestion - CSTR |
| Product | CSTR reactor with insulation system |
| Feedstock | Cattle manure |
| Status | Delivered 2013 |
About Shijiazhuang Zhengzhong Technology Co., Ltd (Center Enamel)
Shijiazhuang Zhengzhong Technology Co., Ltd (Center Enamel) delivers the manufacturing capability behind the digester: bolted GFS tanks are fused at 820-930 C to form an inert, impermeable barrier against corrosive, H2S-bearing digestate, built to ISO 28765 and AWWA D103, shipped flat-pack, and assembled on site. That is the hardware a dairy CSTR or USR is built around.
Comparison: Right Reactor for Dairy
| Criterion | CSTR | USR | UASB |
| Solids 8-12% TS | Yes | Yes | No |
| Mixing | Mechanical | None | None |
| Grit tolerance | Good | Moderate | Poor |
| Dairy fit | Best | Good | Liquid only |
Pick CSTR or USR for whole dairy manure and reserve UASB for the separated liquid. Size the digester to 8-12% TS and 35-38 C. Send your manure TS and daily volume and we will configure the GFS digester and insulation for your dairy.
Frequently Asked Questions (FAQ)
Q1: What reactor is best for dairy cow manure?
A: A CSTR or USR, because both handle the 8-12% solids and bedding that blind a UASB.
Q2: Why not UASB for whole manure?
A: Dairy manure solids and grit blind the granular blanket; UASB suits only the separated liquid fraction.
Q3: What temperature does a dairy digester run?
A: Mesophilic 35-38 C, sometimes with an insulated tank in cold climates.
Q4: How long is the manure retention time?
A: About 20-40 days for wet anaerobic digestion of manure.
Q5: What tank capacity is available?
A: GFS digester tanks from 200 m3 to 60,000 m3.
Q6: What methane content is expected?
A: Raw biogas is about 55-65% methane.
Send your dairy manure TS and daily volume. We will configure the GFS CSTR or USR digester and insulation for your farm.
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