Effects of Waste Lime Sludge on Nitrogen Dynamics and Stability of Mixed Organic waste Using Rotary Drum Composter

Feasibility of waste lime sludge (LS) obtained from acetylene gas production industry was studied during co-composting of vegetable waste for enhanced volatile solids reduction. Four different trials were carried out with varying percentage of LS combinations i.e. trial 1, trial 2, trial 3 and trial 4. Increased addition of waste LS raised the levels of pH in the compost, thereby volatizing the nitrogen as ammonia in trial 3 and 4. However, appropriate addition of LS in trial 2 increased the microbial activity and resulted in higher volatile solids reduction (22.1%) which was found double fold increase when compared to trial 1, where 11% VS reduction was observed. Hence, with proper combination of waste materials and addition of LS, a maximum temperature of 66.5 and 61.4o C was observed in trial 1 and 2 respectively. Temperature level above 50o C for more than 4 to 7 days was observed during the process, thus satisfying the regulatory requirements for PFRP (Process to Further Reduce Pathogens). Therefore, the present study concluded that appropriate amount of LS addition increased the organic matter reduction drastically. However in trial 3 and 4, where 2 and 3% addition of LS were not appreciable in terms of proper degradation and stability at the end of composting period.