MODELING, SIMULATION AND CONTROL OF ACTIVATED SLUDGE PROCESS IN EFFLUENT TREATMENT PLANT OF TROPICAL HARDWOOD AND BAMBOO BASED KRAFT PAPER MILL

摘要

Bamboo and tropical hardwoods are important raw materials in many Asiancountries including Indian pulp and paper Industry. The effluent characteristics arequite different from those of softwood based industry. In this present investigation,detailed studies are made on the effluent characterization of these raw materials,models of the primary and secondary clarifiers, optimizing both process and designparameters and then simulating the effluent treatment plant (ETP) with the datastipulated by regulatory bodies such as state and central pollution control boards andministry of environment and forests. The industry data are then compared with thedata from simulations and the target values. The problem is further extended tocontrol the entire ETP plant parameters to the desired values. In order to attain theabove objective various multi-loop control strategies are attempted. As an example,application of ratio control for effluent flow and treatment chemicals in primaryclarifier, discharge of effluent to streams and returned activated sludge flow and airto influent flow has been shown. Feed forward, feed back and cascade are also tried.Hybrid control strategy using PID feed back control for dissolved oxygen and feedforward control based on conductivity for nutrient addition has also been analyzed.Finally, system is designed and the responses are tested against those from theexisting single loop (single input, single output) negative feedback or feed forwardconfiguration. The results are found to be very promising.