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Phenol and chlorophenols are long-lived pollutants frequently found in industrial effluents. Phenols are widely used for the commercial production of a wide variety of resins including phenolic resins, epoxy resins and adhesives, and polyamide for various applications. Adsorption process has been proven one of the best water treatment technologies around the world and the removal of diverse types of pollutants from water. However, widespread use of commercial adsorbent is sometimes restricted due to its higher costs. Attempts have been made to develop inexpensive adsorbents utilizing for the reduction of phenol from water. Four types of adsorbent clay, algae, moringa oleifera and rice husk has been used. Among all rice husk shown 97 % of phenol adsorption at 1mm particle size, pH 4, 3 g/l dosing and 150min contact time.

In this paper, quantitative synthesis of a multivariable two-matrix-degree-of-freedom feedback system for a 3 x 3 distillation column with sidestreams example having significant plant parameter uncertainty, is performed. The synthesis procedure is that of multi-input multi-output (MIMO) quantitative feedback theory (QFT) (Horowitz,1979). From the given MlMO problem, equivalent single-loop problems are derived whose solution guarantees the solution of the original problem. Using the basic single-input single-output (SISO) QFT procedure (Horowitz and Sidi,1972), t k single-loop problems are then solved to satisfy the frequency domain specifications (specs) on the tracking and disturbance-rejection properties. The design is verified in both frequency and time domains for 81 plants picked randomly from the set of uncertain plants. The results show that the performance specs are successfully achieved for the range of parameter uncertainty considered.