The treatment characteristics of dilute milk wastes (1500 mg COD/l) were investigated by the two phase anaerobic digestion system consisting of a completely mixed reactor for acidogenesis and an upflow filter for methanogenesis. The system removed 92% of the influent COD at an overall hydraulic detention time of 4.4 days. Carbohydrates in the milk were most extensively decomposed (95%), next proteins (50%), while lipids were rapidly hydrolized to long-chain fatty acids but not degraded during the acid phase. The phase separation had an effect on reducing the toxicity of long-chain fatty acids to both acetogenic and methanogenic bacteria. The rates of sludge production were 0.257 mg VS/mg COD utilized during the acid phase and 0.043 mg VS/mg COD utilized during the methane phase. This low sludge production in the methane filter made possible long periods of operation without sludge wasting. The system proposed in this study could accept shock loads of a three-fold increase of the influent COD.

This content is only available as a PDF.
You do not currently have access to this content.