Food Processing DAF Upgrade

Client Overview

A large beef and pork processing facility in Eastern Europe slaughtering 1,200 cattle and 3,500 pigs daily. The site's effluent contained high concentrations of blood, fat, protein, and suspended solids from slaughtering, cutting, rendering, and cleaning operations. The existing treatment system — a simple septic tank followed by aerated lagoon — was failing to meet tightening EU Urban Waste Water Treatment Directive requirements.

The Challenge

The plant's effluent characteristics were extreme even by food industry standards:

• Peak COD: 12,000 mg/L (average 6,500 mg/L) — 20× typical municipal sewage
• TSS: 2,800-4,500 mg/L with high fat and grease content
• Variable hydraulic load: 25 m³/h overnight to 180 m³/h during CIP and shift changes
• High temperature: Hot wastewater from rendering reaching 55°C
• Odour risk: Anaerobic conditions in existing lagoon generating H2S and mercaptans

The Solution

Reynolds & Bauhm was involved in the design, fabrication supervision, and commissioning of a complete 4-stage Treatment Process:

Stage 1: Mechanical Pre-Treatment

• Coarse screen: 10 mm bar screen with automatic rake removing bone fragments and packaging debris
• Rotary drum screen: 1 mm perforated drum for hair, fine solids, and fat capture
• Flow equalisation: 800 m³ buffer tank with mixer to dampen hydraulic and organic peaks

Stage 2: DAF & Fat Recovery

• DAF unit: 120 m³/h capacity with lamella plate pack for enhanced separation
• FeCl3 coagulation: 250 mg/L dose for protein precipitation and flock formation
• Cationic polymer: 3.5 g/tonne for floc conditioning and rapid rise rates
• Fat skimming: Automated surface skimmer recovering 2.8 tonnes/day of renderable tallow

Stage 3: Biological Treatment

• MBBR: 2,400 m³ moving bed biofilm reactor with PVC carrier media at 65% fill
• Fine bubble aeration: Membrane disc diffusers at 5.5 m depth, SOTE 28%
• Anoxic zone: 600 m³ pre-denitrification chamber for TN reduction

Stage 4: Sludge Management

• Thickening: Gravity thickener for DAF float and MBBR waste sludge
• Multi-disc screw press: Dewatering to 22% cake solids for agricultural disposal

Results

Financial & Operational Impact

Compliance

The plant now operates in full compliance with local discharge consent and EU UWWTD requirements. Monthly composite sampling over 12 months confirmed consistent performance below all consent limits. The facility has received two consecutive annual environmental compliance excellence awards from the national environment agency.

Key Learning

Meat processing effluent cannot be treated by biological systems alone — the high fat and solids load would rapidly foul biofilm carriers. The DAF pre-treatment stage is essential for both compliance and output: fat recovery alone offset 38% of the total project Capital expenditure within the first year.