Composting paper mill deinking sludge with forced aeration

Brouillette, M., Trepanier, L., Gallichand, J. and Beauchamp, C. 1996. Composting paper mill deinking sludge with forced aeration. Can. Agric. Eng. 38: 115-122. Static pile forced aeration was used as an alternative to mechanical pile turning to compost paper mill deinking sludge. The experimental set-up consisted of two pile heights (2 and 3 m) and three aeration pipe spacings (no aeration, I-m and 2-m aeration pipe spacing) resulting in different aeration levels. Aeration was provided for 10 consecutive months. Results showed that 3-m piles required longer aeration times to maintain temperatures in the required range. All aerated treatments maintained temperatures between 50 to 65°C compared to 30 to 40°C for nonaerated treatments. Temperatures in aerated treatments were maintained between 50 to 65°C even when the temperature of the air injected into the material was as low as -20°C. Water content remained within the optimum range (60 to 71 %) for efficient composting for all treatments. Fibre levels gradually decreased during the experiment with cellulose being the most degraded. The compost fibre contents was only affected by depth within the piles. The degree of composting, as evaluated by the light absorbency test, was higher for aerated treatments, especially for the I-m pipe spacing treatment. Depth within the piles also affected light absorbency measurements. More nitrogen was converted into the organic form in the aerated treatments, especially for the I-m pipe spacing treatment. Composting deinking sludge with forced aeration is feasible in Eastern Canada even under winter conditions.