OPTIMISED OPERATION AND DESIGN OF ALTERNATING ACTIVATED SLUDGE PROCESSES FOR NREMOVAL

摘要

This paper presents a simulation study with the scope to optimise the plant design and oper- ation strategy of 2-reactors alternating activated sludge processes with only flow. schedule and aeration on/off as control inputs. The methodology is to simulate the application of receding horizon optimal control (RHOC) to a range of different plant designs within this class of systems and select the combi- nation of design and operation strategy with the best performance. Subsequently a simple feedback con- troller is designed that closely imitates the optimal operation strategy. Starting-point is the plant layout with maximal degree of freedom within the above-mentioned class (Fig. l ), which is commercially avail- able under the name BIODENITROD. The simulation results indicate that in the optimal combination of plant design and operation strategy the performance in terms of nitrogen removal improves signifi- cantly as compared to current practice, especially if a shorter cycle length is used. In the optimal pro- cess design the two reactors are placed in series, the first reactor is about four times as large as the second one. The possibilities of feeding influent to reactor 2 and withdrauwing effluent from reactor 1 are redundant. A conceptually simple feedback controller (OSCAR, operating a series connection of two alternating reactors) is presented that straightforwardly implements the improved operation strategy.