COMPOSTING PAPER-MILL DEINKING SLUDGE WITH FORCED AERATION

Static pile forced aeration was used as an alternative to mechanical p ile turning to compost paper mill deinking sludge. The experimental se t-up consisted of two pile heights (2 and 3 m) and three aeration pipe spacings (no aeration, 1-m and 2-m aeration pipe spacing) resulting i n different aeration levels. Aeration was provided for 10 consecutive months. Results showed that 3-m piles required longer aeration times t o maintain temperatures in the required range. All aerated treatments maintained temperatures between 50 to 65 degrees C compared to 30 to 4 0 degrees C for non-aerated treatments. Temperatures in aerated treatm ents were maintained between 50 to 65 degrees C even when the temperat ure of the air injected into the material was as low as -20 degrees C. Water content remained within the optimum range (60 to 71%) for effic ient composting for all treatments. Fibre levels gradually decreased d uring the experiment with cellulose being the most degraded. The compo st fibre contents was only affected by depth within the piles. The deg ree of composting, as evaluated by the light absorbency test, was high er for aerated treatments, especially for the l-m pipe spacing treatme nt. Depth within the piles also affected light absorbency measurements . More nitrogen was converted into the organic form in the aerated tre atments, especially for the I-m pipe spacing treatment. Composting dei nking sludge with forced aeration is feasible in Eastern Canada even u nder winter conditions.