2000 Volume 66 Issue 3 Pages 205-213
Pythium aphanidermatum in sludge from a drinking-water plant was eliminated by heat generated during composting of the sludge for horticultural use. The minimum level of heat treatment to eliminate P. aphanidermatum in the sludge in a laboratory incubator was 45°C for 7 days. Fifty m3 of the sludge in a 2.5-m high pile was mixed with a shovel loader at 3-week intervals for field tests. Inoculum of P. aphanidermatum encapsulated in a nylon screen and buried in the pile was eliminated if temperature exceeded 44°C for more than 7 days. P. aphanidermatum in naturally infested sludge was not detected 3 months after composting. Although the fungus was occasionally not eliminated because of low temperature in the sludge caused by rainfall and air temperature, covering the sludge pile with a plastic sheet maintained a high temperature in the pile. Incorporating of bark compost into the sludge (1:2, v/v) also maintained a high temperature in the pile.
