Evaluation of Sewage Sludge for Incineration (Case study: Arak Wastewater Treatment Plant)

Abstract

Sewage sludge treatment has become a primary subject in wastewater treatment and energy production. This paper aims to study the feasibility of power generation by incineration from sewage sludge enriched with impurities like heavy metals. For this purpose, we chose Arak wastewater treatment plant (AWWTP) and used calorific bomb test for examination. The experimental results showed that the heating values of sewage sludge are much less than the predicted records. This relates to the heavy metal and impurities content of sludge. These totally involved 5 to 18% of dried biomass. Therefore, we modified the predicting equation of heating value with respect to both water and impurities content of excess sludge. Finally, regarding the sludge characteristics of AWWTP, an annealing hierarchy programming (AHP) was used to find optimal technologies for dewatering and sludge minimization. Here, 21 criteria are classified in three main categories to rank the technologies regarding their costs, risks and performance. By all these means, a practical solution is introduced for optimal sludge management.