Anaerobic on-site treatment of synthetic black water (BW) and dairy parlour waste water (DPWW) was studied in two-phased upflow anaerobic sludge blanket (UASB)-septic tanks at low temperatures (10–20 1C). At all temperatures, total chemical oxygen demand (CODt) removal was above 90% with BW and above 80% with DPWW and removal of total suspended solids (TSS) above 90% with both waste waters.