Experimental Investigation On Alternated Activated Sludge Sequencing Reactor For Municipal Wastewater Treatment

A modified type of SBR process, called alternated activated sludge sequencing reactor, has been suggested in the thesis. It is an integrated activated sludge bioreactor with intermittent areation, compact structure, less area, high automatization, and flexible operational mode. It can also sustain impact load.The municipal wastewater from Wuhan Economical Development Zone was treated in the reactors. These experiments of the bench and pilot scale were carried out in two reactors. The reactor of bench scale can treat the wastewater for 0.5 m³ /d. The reactor of pilot scale can do for 500 m³/d. The nitrogen and phosphorus removals were studied in the reactor of the pilot scale. Flow pattern of this reactor was tested in the reactor of the bench scale. A method of cultivation and domestication of activated sludge was researched in the bench scale reactor. Phosphorus removal mechanism was analysed. In addition, a new method of determination of COD was suggested, and a rapid method of determination of MLSS concentration was obtained. This thesis demonstrates the phosphorus removal mainly relies on microorganism growth other than the accumulated phosphorus organiams (PAOs). This is a new finding.The experiment results show the reactor can be restarted and operated successfully when deterwater sludge from beer wastewater treatment plant was added as the originated sludge in a short time. The experiment results demonstrate that this process can remove nitrogen and phosphorus effectively from the wastewater. The effluent COD, NH₄^--N, TN and TP concentrations can meet the B grade in the first grade of the criterion of of the national discharging limits (GB18918—2002).The experiment results also demonstrate the deterwater sludge from beer wastewater treatment plant can be used as the originated sludge to cultivate the activated sludge in wastewater treatment plant. It needs short time for the cultivation and the certified effluent. The method of determination of COD using home-made reagents show many advantages such as less reagents, low cost, high accuracy and precision. The MLSS equation obtained by the experiment show many advantages for example real convenience, high precision and short time of determination. The MLSS equation obtained by MATLAB procedure is difficult to be reminded. The MLSS equation obtained by man-maded statistical way can be reminded easily and used in the practical work. Its accuracy and precision can be mitted for the determination of the practical work. NaCl was used as tracer. The 3 E(t) profiles were obtained by 3 experiments. The flow pattern characteristic of the reactor show the reactor is high efficiency. In the meantime the optimal hydraulic condition is obtained after the experimental data are analyzed by the mathematically statistic method. The phosphorus removal experiment implies the increasing 100 mg/L MLSS concentrations can remove about 1 mg/L TP. The phosphorus removal efficiency can be improved by the increasing rate of MLSS concentrations. When everyday increasing rate of MLSS concentrations are about 500mg/L, the phosphorus removal efficiency would higher than 90%, effluent TP would be lower than 1 mg/L. When MLSS concentrations are fluctuating, effluent phosphorus would fluctuate correspondingly. Everyday the amount of discharging excess sludge can be prejudged by the amount of influent TP. The nitrogen removal experiment implies that the nitrogen removal efficiency is very high. The ratio of NH₄^--N/TN is approximately equal to the ratio of TN removal. TN removal efficiency is mainly affected by the influent NH₄^--N concentration, and the optimal TN removal efficiency can be prejudged by the ratio of influent NH₄^--N/TN.