Reliability, Maintainability and Sensitivity Analysis of Biological and Chemical Processing Unit of Sewage Treatment Plant

Abstract

Purpose:The most difficult problem facing by the society is inadequate water resources and for its rectification sewage treatment plants (STP) play a key role. In STP, after initial processing throughphysicalprocessing unit (PPU) all the soiled waste removed from sewage water. After the removal of soiled waste,biological and chemical processing unit remove bacteria, impurities and all the materials remain after the physical processing unit. These processing unitsarevery important part as it removes all the bacteria and maintain the quality of treated water and it has sixcomponents arranged in series configuration.

Design/Methodology:Performance has been analysed by considering reliability, availability, maintainability, and dependability (RAMD) methodology. With the help of Markovian birth–death processChapman–KolmogorovDifferential equations are derived,and failure and repair rates of the subsystems are considered as exponentially distributed. Sensitivity analysis has been performed along withmean time between failures, mean time to repair and dependability ratio.

Results/Findings:According to RAMD investigation, it is observed thataeration tank is the most sensitive subsystem having reliability0.135335 while system achieved availability 0.95649. Due to aeration tank system’s reliability reduced at level 0.070088 and 0.000344 after 20 and 60 days respectively thoughthere are 73.96% chances that system repaired within 20 days after failure supported by dependability ratio value 0.958299.

Originality: In previous literature, no work has been identified related to the performance of biological and chemical unit of sewage treatment plant. So, here an effort has been made to derive RAMD measure of such system.