A new approach to the Raw Water Quality Index using the Fuzzy Logic

For the performance evaluation of water treatment plants, the raw water quality presents significant relevance. In Brazil, the Index of Quality of Raw Water for Public Supply (IAP) and the Index of Quality of Raw Water (IQAB), developed according to deterministic models, can evaluate the treatability of natural waters. However, the IAP presents a high cost for actual implementation and the IQAB needs some adjustments related to the input parameters and grading criteria. Aiming at a non-deterministic model, able to deal with uncertain, nonlinearity of the parameters and expert knowledge, Fuzzy Logic was applied to a new approach of the IQAB. The Fuzzy Raw Water Quality Index (IQABF), in comparison with the original IQAB, presented more restrictive, more consistent and more flexible for future adjustments. Its application for six water sources of Southeast Region showed practically the same hierarchy in terms of the treatability in comparison with the original IQAB.