What Is USR?
USR stands for upflow solids reactor: an anaerobic digester that accepts high-solid manure at 8-12% total solids and treats it by upflow without mechanical mixing, holding coarse feed in a blanket that behaves like a UASB but is built for solids rather than soluble liquor. It is the middle option between a fully mixed CSTR and a liquid-only UASB on a livestock farm.
1. How a USR Works
Feed enters the bottom and rises; biogas lifts and contacts the solids, and treated liquor leaves the top while coarse, unreacted matter stays low in the reactor. There is no stirred shaft and no external recirculation pump as the default. The design tolerates bedding, fibers, and grit far better than a UASB because the working volume is sized for solids, not a fine granule blanket.
2. USR vs UASB vs CSTR
| Reactor | Feed TS | Mixing | Solid tolerance |
| USR | 8-12% TS | None, upflow | High |
| UASB | Low, soluble | None, upflow | Low |
| CSTR | 8-12% TS | Mechanical | High |
3. When USR Wins on a Farm
USR wins where the manure is too thick for a UASB but the owner wants lower mixing energy than a CSTR and simpler operation. It suits dairy and pig manure with moderate grit after a simple screen. Retention is still long, around 15-30 days, at 35-38 C, yielding biogas at 0.20-0.30 m3 per kg volatile solids and 55-65% methane.
Project Case Study
Gaopu Dashun Hoggery Wastewater Treatment Project. A hoggery plant in Guangdong using a Pre-process + USR + AOAO train to treat 300 m3/day of water-submerged manure-cleaning wastewater - a delivered example of USR applied to livestock manure on a real farm.
| Project | Gaopu Dashun Hoggery Wastewater Treatment Project |
| Location | Puning, Guangdong, China |
| Industry | Livestock / Pig Farm |
| Application | Manure treatment - USR |
| Product | USR reactor + GFS process tanks |
| Capacity | 300 m3/day |
| Status | Delivered |
About Shijiazhuang Zhengzhong Technology Co., Ltd (Center Enamel)
Shijiazhuang Zhengzhong Technology Co., Ltd (Center Enamel) applies its customization capability to the solids reactor: the USR and balancing tanks are engineered to the farm's total solids, grit load, and discharge or reuse limit rather than forced into a standard size. Bolted GFS tanks fused at 820-930 C resist the H2S-bearing liquor and ship flat-pack for a site-specific layout.
Comparison: USR vs the Alternatives
| Criterion | USR | CSTR | UASB |
| Mixing energy | Low | Higher | Low |
| Solids 8-12% TS | Yes | Yes | No |
| Operation | Simple | Active | Sensitive |
USR is an unmixed upflow reactor for 8-12% TS manure, sitting between CSTR and UASB. It suits farms wanting low mixing energy and good solids tolerance. Send your manure TS and flow and we will customize the GFS USR and tank package for the farm.
Frequently Asked Questions (FAQ)
Q1: What does USR stand for?
A: Upflow solids reactor, an anaerobic digester built for high-solid manure without mechanical mixing.
Q2: How is USR different from UASB?
A: USR is sized for 8-12% solids; UASB needs soluble liquor and blinds on solids.
Q3: What feed suits USR?
A: Dairy or pig manure at 8-12% TS after a simple screen, with moderate grit.
Q4: What retention time does USR need?
A: About 15-30 days at mesophilic 35-38 C.
Q5: What biogas yield is expected?
A: Around 0.20-0.30 m3 per kg volatile solids at 55-65% methane.
Q6: What tank capacity is available?
A: GFS tanks from 200 m3 to 60,000 m3.
Suggested CTA
Send your manure TS, grit load, and flow. We will customize the GFS USR and balancing tank package for your farm.