Abstract

TORRES, Patricia; MARMOLEJO, Luis Fernando  and  BOTINA, Adriana. Improving anaerobically digested sludge’s agricultural potential by adding lime. Agron. colomb. [online]. 2005, vol.23, n.2, pp.310-316. ISSN 0120-9965.

This study evaluated the natural thermal drying technique on a sludge bed for dehydrating digested sludge from an anaerobic pound which treats domestic wastewater. It also evaluated its influence on dehydration efficiency and the removal of pathogens and worm eggs by adding different percentages of lime (20%, 40% and 65% CaO) aimed at improving potential agricultural use. A negative effect was generally observed on dehydration efficiency when lime was added at the beginning, a reduction of sludge water content to 65% to 70% being thus recommended before adding lime. Such dehydration level was reached after 7 to 9 d, once sludge dehydration had begun. The evaluated range of lime content guaranteed that pH rose to 12 during contact time, which was sufficient for removing pathogens and parasites. This research showed that the best treatment for pathogens and worm egg removal was obtained by adding 20% lime in the study conditions employed here. The product’s final characteristics suggest that it could be used for agricultural purposes such as total or partial chemical fertiliser replacement, for improving soil conditions, composting, etc. it is thus recommended that pilot greenhouse experiments be carried out.

Keywords : agricultural use; alkaline stabilization; dehydratation; ensuring hygiene.

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