Control system for sewage treatment plant with single-stage activation tank - using fuzzy logic computer to derive regulating value, e.g. for rate of oxygen addn. from inexact measured and input data

摘要

In a new control system for biological processes in a sewage treatment plant with a single-stage activation tank (1), exact or inexact actual values are determined by probes (6, 7), an inexact control values are input manually via an input device (7). The actual and control values are converted to inexact variables (12) in a 'fuzzification' procedure, and are processed in accordance with an inference rule (13). A regulating value is then derived by a 'defuzzification' procedure (14). ('Fuzzy Logic' is a procedure by which a computer derives accurate or precise values from inexact - or 'fuzzy' - input data). USE/ADVANTAGE - Used in partic. for controlling the rate of input of oxygen (16) in aerobic and anaerobic processes in sewage treatment. Allows the treatment process to operate with greatly reduced supervision, and increases the efficiency of the process by enabling the system to cope with inexact input data. This type of data is often the only type available - e.g. the only available assessment of the degree of foaming in a treatment tank may be an operator's judgement of whether foaming is light, heavy or moderate.