Application of Decanter Centrifuge for Lactic Acid Fermentation Broth Separation

Main functions

1. Continuous separation of biomass and coarse solids Under centrifugal force, bacterial cells and fibrous residues settle on bowl wall, then conveyed continuously by scroll for discharge. Lactic acid supernatant flows out from overflow. Fully continuous operation for large-scale PLA plant.
2. In-situ counter-current cake washing to improve lactic acid yield Washing water sprays the cake inside decanter, to strip entrapped lactic acid from solid cake, recycle lactic acid back to liquid phase and reduce product loss.
3. Dewatering of biomass residue Cake moisture can reach 75%~78%. Dewatered biomass can be reused as animal feed or organic fertilizer, reducing waste volume and evaporator load.
4. Protect downstream clarification & purification units Remove most coarse fiber and high-concentration biomass before disc separator & ultrafiltration, reduce fouling, wear and downtime of downstream equipment.

Key design features for this duty

• Wetted parts: AISI 316L (1.4404), scroll flight hard-faced with tungsten carbide WC
• Seals: FDA FKM, resistant to weak lactic acid corrosion
• Surface finish Ra ≤0.8 μm with built-in CIP cleaning system
• Dual VFD closed-loop differential speed control, DCS signal available
• Working range: feed solid content 3~15%, temperature up to 60℃

Comparison with disc separator

Decanter is optimal for high solid feed, fiber-containing slurry, cake washing and dewatering. Disc separator is used for fine polishing of low-solid supernatant. They are commonly matched as a complete separation package for lactic acid / PLA projects.