Analysis and reliability of a wastewater treatment plant: the contribution of operational safety at Tlemcen WWTP, Algeria

This research mainly aims to analyse the overall operation of a wastewater treatment plant by establishing a monitoring system for the work of the plant equipment (e.g. aeration basin, sand separator, filter device, etc.) as well as the operating process. This analysis allows for rapid and effective intervention in the event of a breakdown, while still monitoring the substances released into the water after the purification process. In our study, we conducted a case study of the performance of the Tlemcen treatment plant located in north-western Algeria from January 2013 to March 2016. We show and demonstrate the effectiveness and efficacy of treatment with respect to total suspended matter and chemical oxygen demand (COD), with some recordings exceeding the standard levels for NO 3 - and NH 4 + . The relationship between the parameters and the contamination level could be useful to find an explanatory relationship between the physical and chemical parameters; we noted a positive correlation between biological oxygen demand (BOD 5 ) and COD with ( r = 0.86), and a strong negative correlation between temperature and dissolved oxygen ( r = − 0.64). The what-if method was applied, which allows the implementation of a global vision of the whole system by identifying failures, and thus assessing and classifying the risks associated with the plant. This is accomplished by defining the areas controlled according to the quality standards of discharges and the danger areas, which require intervention for improvement; hence, we include a criticality diagram which summarizes the different failures defined.