Knowledge-based fuzzy system for diagnosis and control of an integrated biologi...

• Author(s): Pires, O. C. ; Palma, C. ; Costa, J. C. ; Moita, I. ; Alves, M. M. ; Ferreira, E. C.
• Date: 2005
• Persistent ID: http://hdl.handle.net/1822/2651
• Origin: RepositóriUM - Universidade do Minho
• Subject(s): Anaerobic digestion; Activated sludge; Fuzzy logic based system; Nutrient removal; Distributed supervision; Expert system
• Document Type: Conference Object
• Language: English

Description

A supervisory expert system based on fuzzy logic rules was developed for diagnosis and control of a lab- scale plant comprising anaerobic/anoxic/aerobic modules for combined high rate biological N and C removal. The design and implementation of a computational environment in LabVIEW for data acquisition, plant operation and distributed equipment control is described. A step increase in ammonia concentration from 20 to 60 mg N/L was applied during a trial period of 73 hours. Recycle flow rate from the aerobic to the anoxic module and by-pass flow rate from the influent directly to the anoxic reactor were the output of the fuzzy system that were automatically changed (from 34 to 111 L/day and from 8 to 13 L/day, respectively), when new plant conditions were recognized by the expert system. Denitrification efficiency higher than 85% was achieved 30 hours after the disturbance and 15 hours after the system response at an HRT as low as 1.5 hours. Nitrification efficiency gradually increased from 12 to 50% at an HRT of 3 hours. The system proved to properly react in order to set adequate operating conditions that timely led to recover efficient N and C removal rates.