Application of a model-based HACCP system to turbidity control in a conventional waterworks

A model-based HACCP system for managing drinking water safety has been proposed by introducing a previously developed Integrated Water Supply System (IWaSS) model for the determination of critical control points (CCPs) and the establishment of critical limits (CLs). In such a HACCP system, hazard analysis is conducted as a quantitative risk assessment through Monte Carlo simulation with the IWaSS model, CCPs are identified through a regional sensitivity analysis, while the CLs for the CCPs are determined through an iterative simulation also with the IWaSS model. The methodology is then applied to a typical conventional waterworks to assess the potential of the waterworks to comply with the standard for turbidity and formulate effective strategies for turbidity control. Coagulation and filtration are found to be the CCPs to improve the performance of the waterworks in turbidity compliance, while source water and sedimentation are the quality control points (QCPs). CLs for the CCPs and QCPs are also quantitatively determined, based on which requirements for monitoring system and corrective actions are proposed.