Nitrogen loss reduction by adding sucrose and beet pulp in sewage sludge composting

In this study, the impacts of sucrose addition and the application of beet pulp as carbon source on nitrogen loss during sewage sludge composting were evaluated in a lab-scale reactor. Response surface methodology (RSM) was used to optimize the method of sucrose addition. The relationship between biodegradability (5 day biochemical oxygen demand (BOD₅) content) of sludge extraction solution and ammonia emission was investigated. With the nitrogen loss ratio as a dependent variable, the conditions (adding ratio of 0.02 (w (sucrose):w (sewage sludge)), adding time of 59.3 h and adding solid sucrose (without water) were chosen. The developed model was verified to have a high degree of accuracy. The BOD₅ content of sludge extraction was obviously increased to 62.3 mg/g volatile solid (VS) and 213.9 mg/gVS by adding sucrose and beet pulp. Ammonia emission could be further reduced by 56.7% through adding beet pulp. The results suggested that the high biodegradability of carbon source might be the main reason that beet pulp could efficiently reduce the nitrogen loss during composting.