Effect of Composting with Bark Amendment on Nitrogen and Manganese Content in Water Clarifier Sludge

Abstract

Effect of pre-mixing bark amendment into water purification sludge before auto-composting on nitrogen and manganese content of the sludge and quality as material for potting media was investigated. Each of the sludge with and without pre-mixing bark amendment was piled to a volume of about 50 m³, 2.5 m height and was fermented at factory production scale. Pre-mixing the sludge with bark amendment accelerated the fermentation of the compost and decreased the amount of manganese ion(Mn²⁺) in the sludge. Inorganic nitrogen content of the pre-mixed composed was smaller than that of non-premixed compost. Each composted sludge was used as potting media for bottle guards. The plants with potting media of 70% pre-mixed sludge grew better than those with potting media of 70% non-premixed sludge. One of the main reasons for these results was considered the reduction in Mn²⁺ content of the sludge pre-mixing with bark amendment. However, this phenomenon was not seen when potting media consisted of 40 or 55% sludge.