Reduce disposal requirement and cost for brewery spent grain, winery pomace, and cider lees with screw press and decanter centrifuge dewatering systems. Turn waste streams into output-generating by-products.
Dewatering Residues from Brewing, Winemaking & Cidermaking
Brewery spent grain is the single largest solid by-product of beer production, typically generated at 75–80% moisture content. A 1,000 hl brewery produces 15–20 tonnes per day of wet spent grain, representing a significant disposal and logistics challenge. Without dewatering, this material is transported and landfilled at full wet weight, increasing volumes and carbon footprint. Screw presses and decanter centrifuges cut spent-grain moisture to around 65–70%, slashing haulage weight and turning a disposal cost into a saleable animal-feed or biogas feedstock. We size the dewatering line to the brewery’s throughput so it keeps pace with production without becoming a bottleneck.
Winery pomace — the skins, seeds, and stems remaining after grape pressing — carries 82–85% moisture and higher polyphenol content, which can inhibit advanced biological treatment if sent to wastewater. Cidery apple pomace sits at 80–83% moisture with lower protein but high fibre content. Effective dewatering reduces these residues to approximately 20% dry solids, achieving up to 75% volume reduction and transforming disposal liabilities into saleable commodities.
Dewatered cake commands –150 per tonne as ruminant animal feed, compost amendment, or anaerobic co-digestion substrate. Regulatory compliance under DAERA/Defra requires pathogen reduction — achieved through pasteurisation at 70°C for 60 minutes or thermal drying — before by-products can enter the animal feed chain. Reynolds & Bauhm is involved in supplying integrated dewatering systems designed specifically for the fibrous, abrasive nature of brewery and winery residues.
Anaerobic co-digestion of dewatered brewery grain with dairy or food waste can increase biogas yield by 15–30% compared to single-substrate digestion. The high COD content (120,000–180,000 mg/kg DS) and favourable C:N ratio make spent grain an ideal co-substrate for on-site or regional anaerobic digestion facilities. For sites with existing digesters, dewatering filtrate contributes valuable soluble COD without the solids-handling burden of whole grain.
Screw press, belt press, and decanter centrifuge technologies compared for beverage solids dewatering.
| Parameter | Screw Press | Belt Press | Decanter Centrifuge |
|---|---|---|---|
| Dry Solids (DS) | 18 – 22% | 20 – 25% | 22 – 28% |
| Throughput (kg DS/hr) | 100 – 500 | 200 – 1,000 | 300 – 2,000 |
| Power (kWh/tonne DS) | 15 – 25 | 20 – 35 | 30 – 50 |
| Best For | Spent grain | Pomace | Fine lees |
Screw presses are the default choice for brewery spent grain due to their tolerance of long fibres, low Capital expenditure, and minimal operator intervention. Belt presses excel with winery pomace where higher cake solids justify the wider footprint. Decanter centrifuges handle fine cider lees and high-volume operations where maximum dryness offsets higher energy consumption.
For seasonal operations such as wineries and cideries, mobile or skid-mounted screw press units allow equipment to be stored off-season, protecting capital investment. Year-round breweries benefit from permanent installations with automated wash cycles and SCADA integration for unmanned operation during night shifts.
Five-stage dewatering process optimised for brewery spent grain, winery pomace, and cider lees.
Wet grain or pomace is collected in a stainless steel hopper with agitator to prevent bridging. Level sensors automate feed to the maceration stage.
High-shear macerator breaks clumps and opens cell structure, increasing surface area for water release and improving downstream dewatering efficiency by 10–15%.
Tapered screw with variable pitch compresses material against a conical discharge end. Screen aperture 0.3–1.0 mm balances filtrate clarity with throughput.
Dewatered cake exits at 18–22% DS via adjustable cone pressure. Pneumatic or hydraulic cone regulation maintains consistent solids regardless of feed variability.
Filtrate is routed to the equalisation tank or DAF inlet. Typical filtrate TSS <500 mg/L, BOD 2,000–5,000 mg/L, suitable for downstream advanced biological treatment.
Brewery spent grain contains abrasive silica from malt husks, generating significant wear on screw flights and screen baskets. Reynolds & Bauhm specifies:
Motor sizing follows a two-peak torque profile: an initial spike of 2.0–2.5× nominal torque during feed compaction, followed by steady-state at 0.8–1.2× nominal. We specify motors with 3× service factor and vector-controlled VFDs to handle these transients without nuisance tripping. For winery pomace with higher polyphenol stickiness, PTFE-coated screens and reduced compression ratios (3:1 vs. 5:1 for grain) prevent blinding and extend run length between washes.
Ensuring dewatered cake meets animal feed, composting, and regulatory standards.
Brewer's spent grain contains 25–30% protein on a dry basis, making it a valuable protein supplement for dairy and beef cattle. Winery pomace protein is lower at 10–15% but rich in polyphenol antioxidants.
Fibre content of 15–20% in spent grain aids rumen digestion and provides structural bulk. Apple pomace fibre reaches 20–25%, suitable for swine and poultry rations at inclusion rates up to 15%.
DAERA/Defra mandates pasteurisation at 70°C for 60 minutes or equivalent thermal treatment to eliminate Salmonella, E. coli, and Listeria before ruminant feed use. This is achieved via steam injection or drying.
Storage moisture must be maintained below 14% to prevent aflatoxin and ochratoxin growth. Dewatering to 20% DS followed by sun-drying or mechanical drying achieves safe long-term storage.
All by-products entering the animal feed chain require hazard analysis, traceability records, and documented processing parameters. Reynolds & Bauhm systems include temperature logging and batch tracking.
Dewatered brewery grain has a C:N ratio of 20–30:1, ideal for rapid composting. Winery pomace requires carbon amendment (straw, sawdust) to balance higher nitrogen and moisture for aerobic composting.
Worked example for a 1,000 hl brewery demonstrating project benefits from dewatering investment.
Typical screw press Capital expenditure for this scale: Typical project benefits: 1–3 months. Decanter centrifuge project benefits is longer at 6–12 months but justified for high-volume or year-round operations.
Winery example: 10 t/day pomace at wet disposal = cost. Dewatering to 22% DS yields 3.5 t/day cake ( output =) plus 6.5 t/day disposal saving ( =). Net benefit: against baseline, with belt press project benefits in 4–7 months.
Typical system configurations and budgets for brewery, winery, and cidery dewatering applications.
Installation requires 6 m × 4 m floor space with 3 m headroom. Foundation loading: 15 kN/m². Electrical: 415 V 3-phase 32 A supply. Commissioning and operator training included. Warranty: 24 months on mechanical, 12 months on electrical.
Designed for seasonal harvest operation (September–November peak). Belt width 1.0 m, wash water consumption 2 m³/h at 3 bar. Cake solids 20–25% achievable with cationic polymer dosing at 3–5 kg/tonne DS. Polymer station included in scope.
Decanter bowl diameter 420 mm, length/diameter ratio 4.2:1, differential speed 2–15 rpm variable. G-force up to 2,500 g for maximum solids recovery. Polymer preparation station: automatic powder dissolving with 1,000 L aging tank. Control: Siemens S7-1200 PLC with 7" HMI and remote access modem.
Daily operation, maintenance, and seasonal factors for beverage solids dewatering systems.
Brewery screw presses typically run 8–16 hours/day, 5–7 days/week, matching brewhouse production. Winery belt presses operate intensively during harvest (6–12 weeks) and may sit idle for 9–10 months. Decanter centrifuges suit continuous operation at large breweries with three-shift schedules.
Screw press: inspect flight wear monthly, replace segments at 50% thickness loss, grease bearings every 250 hours. Belt press: track alignment weekly, wash cloth daily, replace at 2,000–3,000 hours. Decanter: bowl inspection every 4,000 hours, gearbox oil change annually.
For seasonal winery and cidery operations, mobile skid-mounted units can be returned to our depot for winter storage, preserving capital and eliminating frost protection costs. Permanent installations require trace heating and lagging on filtrate lines for sub-zero operation.
Returned filtrate contains 2,000–5,000 mg/L BOD and should be directed to the EQ tank or DAF inlet. High-strength filtrate from winery pomace may require pH adjustment before advanced biological treatment due to tartaric and malic acid content.
Why dewater spent grain, pomace, and lees
Reduce wet material volume by up to three-quarters, dramatically cutting storage, transport, and disposal requirements.
Convert disposal requirement into income by selling dewatered cake to livestock farmers at –150 per tonne.
Fewer lorry movements reduce haulage bills, carbon emissions, and road congestion around your facility.
Returned filtrate retains soluble BOD and nutrients, reducing fresh water demand and supporting advanced biological treatment.
Systems designed to meet UK pathogen reduction and traceability requirements for by-products entering the feed chain.
Diverts organic solids from landfill or sewer, cutting gate fees and helping achieve zero-waste targets.
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