Study On The Automation Control And Its Performance Of The Sequencing Batch Reactor (SBR)

This paper systematically summarizes the development, process style and biology theories involved in the SBRs process. And on that basis, the paper searches automatic control, the change of COD value and the shock resistant capacity of typical SBR process, as well as the influence of the heavy metals chrome ion on SBR and the activated sludge of SBR to the absorption of the chrome ion is also studied. Now the summary of the research result is as follows:(1) The experiment adopts the PLC technique to carry out the SBR process automatization circulation successfully, summarizing its PLC plait distance technique to the movement characteristics of SBR process. In the light of the experiment the thesis puts forward the concept of the cyclic performable occurrences ,and give a plait distance mode of the cyclic performable occurrences.(2) Making use of SBR to treat the organic wastewater can obtain good result .But the ways of treating the high concentration and the low concentration organic sewage are not the same: To the low concentration organic sewage, we must raise the organic loading by high drain rate or shortening the time of the period of reaction; and to the high concentration organic sewage, we must reduce the organic loading by low drain rate or lengthening the time of the period of reaction(3) The SBR process has a very strong ability to bear the impact load .The ability of its bearing the organic impact load, on the one hand, has something to do with the concentration of the activated sludge, on the other hand, has something to do with the time of reaction of SBR process. The influence of the organic impact load to the SBR process is not to destroy the activated sludge system of SBR, but to cause absorption ability of the activated sludge to be exceeded by the organic sewage .While recovering the primary wastewater normally, the system will also recover normally. In order to explain the bearing impact load phenomenon of SBR, this text puts forward a hypothesis," the stockpile - usage (generation)", to explain the ability of the bearing organic impact load of SBR. (4) The chrome load can be divided four scopes according to the toxicity function of the chrome ion to the mixed liquor volatile suspended solid (MLVSS): beating scope (0～～30mg/gmlvss),collapse scope(30～～65mg/gmlvss),flocculation scope (70～～100mg/gmlvss),the scope of breaking cell (＞100mg/gmlvss). The size of SVI has influence to this scope value. When the SVI value is low, the scope value of top and bottom limit will increase; and when the SVI value is high, the scope value of top and bottom limit will decrease.(5) The chrome load and SVI all influence the absorption of the chrome ion by the activated sludge of SBR process. When the chrome load is under 30mg/gmlvss, its influence on the absorption of chrome ion by the activated sludge of SBR system isn't very much, but will diminish with the aggrandizement of SVI. When the chrome load level is over 30mg/gMLVSS, because of the toxicity function of the chrome ion, the absorption ability to the chrome ion of the activated sludge of SBR process will descend consumedly.(6) The toxicity function of the chrome ion will cause the physical volume of the activated sludge to enlarge, but the flocculation function of the chrome ion will then cause the physical volume of the activated sludge decrease. Their interactions will cause the sediment sludge volume in 30 minutes present a wave type variety with the aggrandizement of the chrome load (namely the aggrandizement of the chrome ion concentration in the aqua). The size of SVI influences the function of the chrome ion to the size of the sediment sludge volume in 30 minutes, and makes the wave type variety characteristic become obvious or not obvious.(7) All the chrome ion toxicity function, the flocculation function and the activated sludge specific gravity gain that the chrome ion result in are the factors that influence the subsidence process of the activated sludge. The SVI value also influences the function of the chrome ion to the subsidence process of the activated sludge obviously in the meantime. The factors of controlling the settling velocity of sludge and controlling the final sediment sludge volume are not same. The settling velocity of the activated sludge will increase with the increment of the chrome ion concentration, and it will increase with the increment of the chrome ion concentration, but the finial volume of the activated sludge is the interactive result of the toxicity function and the flocculation function by the chrome ion.(8) The activated sludge whose SVI is in 120ml/gmlvss or so is more special .The activated sludge at this SVI or so, along with the aggrandizement of the chrome load, will cause negative bulge phenomenon, namely, in the low chrome concentration, the settling velocity of sludge will speed, but in the high chrome load level, the sludge volume becomes bigger than the sludge volume of comparison, and the settling velocity of sludge become slow. Certainly, this is in the scope of the chrome load in the article experiment.