Study On The Removal Mode Of Organism In Wastewater Biological Treatment Process

On the basis of the experimental investigation, the major factors effecting themicrobial growth and substrate removal in the unsteady reactor were determined. Theremoval mode of organic matter was proposed by an analysis of the process of adsorption,penetration and metabolism. Furthermore, a set of formulas regarding the concentration ofmicroorganisms, sludge and substrate in the unsteady reactor was educed. Therefore, theseresults will provide a theoretical basis for the analysis and numerical simulation of themicrobial growth and substrate removal in activated sludge system.The biological adsorption is the decisive factor influencing the wastewater treatment,functioning in the whole wastewater treatment process. Organic matter is first adsorbed onthe surface of microbial and then penetrates into the interior of the cell, followed by themicrobial metabolism. Then the microbial surface vacates adsorption sites and adsorbs theorganic matter again. As a consequence, organic matter in wastewater is removed. Thewhole process is divided into three stages （rapid absorption, saturated adsorption andunsaturated adsorption）. When the unsaturated adsorption period is identified, sludge load（F/M） is the key factor affecting the adsorption capacity. At the same time, the adsorptioncapacity （per unit mass of microorganisms adsorb the amount of organic matter） is the keyfactor affecting microbial specific growth rate. In addition, the curve of adsorptioncapacity versus sludge load and the curve of microbial specific growth rate versusadsorption capacity are measured. The relationship between adsorption capacity andsludge load, microbial specific growth rate and adsorption capacity are obtained,respectively. Furthermore, a number of kinetic parameters and stoichiometric parameters(saturated adsorption capacity qs, adsorption rate v, the rate of COD to the quality oforganic matter f_c/m, the minimum sludge load at adsorption saturation （F/M）) aremeasured.The results show that the adsorption capacity functions as sludge load （F/M） in theunsaturated adsorption period, and microbial specific growth rate varies according toadsorption capacity in the entire wastewater treatment process. When the saturatedadsorption period is achieved, the adsorption capacity （qs） and the microbial specific growth rate are constant.Based on the extensive literature research and the experiment analysis, the newremoval mode of the organic matter in the wastewater treatment system is proposed,which is derived from the process of adsorption, penetration and metabolism. A set offormulas of the concentration of microorganisms, sludge and substrate in the unsteadyreactor is also obtained. This study will provide the methods and theoretical basis for themathematical simulation of the activated sludge in the unsteady reactor.