Abstract:
In a developing urban society, the waste water generation is usually 30 — 70 m3 per person per year. The quality of waste water (mixture of black and gray water) after treated with activated sludge process was monitored for seven different constituents (turbidity, dissolved solids, chlorides, sodium ratio, conductivity, BOD and COD). This waste water can be used for irrigation purposes after the proper treatment through treatment plants. From treated water, more than one hundred water samples have been takenand analyzed for the concentration of their constituents. Water samples have been categorized for quality on the basis of water quality indices (WQI) which transformed all the seven constituents and their concentrations present in a single value through empirical method (equal and unequal weightage of different constituents).
A new emerging technique like Fuzzy technique is employed for water quality modeling. Fuzzy — Mamdani technique is used to frame the fuzzy rules and get the result as water quality of the samples. Using water sample's data, all input data are fuzzified. Trapezoidal membership functions are drawn for all inputs and output. A final model is developed which is useful to find the quality of water for any concentration of these constituents in future.
The model has given the water quality index of the treated water. It is found that the quality index of water after treatment is not very poor. It lies between 60 to 90 for most of the samples. This water can be used for irrigation purpose. Water having quality index less then 60 can be used for gardening flushing etc. Sometime in crucial situations water with quality index above 80 can be use for domestic purpose. It is also concluded that the weights should be specified according to the importance of the parameter rather equal distribution.
