The pasteurisation of sludge

Abstract

SYNOPSIS The aim of this research was to determine the sterilisation characteristics of a fuLL-scaLe continuously operated wastewater sludge pasteuriser. ! The unit was monitored over a three year period in the foLLcwing ways: 1. At fixed temperatures in the range 50 - 70"C, with feeds of raw and digested sludge, over one-hour experimental periods. 2. Under routine conditions in the pre-pasteurisation made [pasteurisation before anaerobic digestion] with target conditions of 7Q"C for a minimum of 30 minutes, and a feed of raw sludge pLus waste activated sludge thickened in a dissolved air flotation unit. 4 It was found that a temperature of 53"C for 30 minutes was sufficient to inactivate Ascaris Lumbricoides ova, but that 66'C was required for fae- , caL coL i farms. There was good agreement between decimal decay rates I obtained in these full-scale experiments, with sLudge feeds, and those in the literature for various media and conditions.

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