Failure mode and effects analysis of common effluent treatment plants of humid sub-tropical regions using fuzzy based MCDM methods

Abstract

Common effluent treatment plants (CETPs) are used to collectively treat the effluents generated from different types of manufacturing industries of an industrial cluster before discharge so as to prevent the environment from the harmful effects of the effluents. There are several failure modes (FMs) that may lead to the failure of the CETP which may result in discontinuation of its operation. Thus, it is imperative to identify and estimate the criticality of the various FMs using failure mode and effects analysis (FMEA) in order to minimize the risk of failure of the CETP. This study identifies 24 potential FMs of the CETP, installed in humid subtropical regions, with the help of consensus among 5 experts who are the managers of CETPs installed at five different industrial regions of Delhi, the capital town of India. Subsequently, it applies a combined fuzzy based multi criteria decision making (MCDM) methods i.e. fuzzy analytic hierarchy process (FAHP) and fuzzy technique for order of preference by similarity to ideal solution (FTOPSIS) to derive rank of FMs. FAHP is applied to calculate the weights of three risk factors (RFs) i.e. occurrence (O) which refers to the chance of a failure cause occurring; severity (S) which measures the extent of effect of a failure cause on the system and the detection (D) which represents the chance of detecting the failure cause before the failure actually occurs. Then FTOPSIS is employed to determine rank of the FMs which signifies their criticality. The data required to implement FAHP and FTOPSIS are gathered from the experts in linguistic terms which are subsequently converted into equivalent triangular fuzzy numbers. Finally, sensitivity analysis is carried to ensure robustness of the ranking results produced by the combined FAHP and FTOPSIS method.