| Sewage disposal is a new industry that comes up with seeking the method of dealing with the environment pollution because of the rapid development of industrialin sation and citification. It has existed for about a hundred years. Traditional sewage disposal aimed removing organism and float off but neglected removing nitrogen and phosphorus off. Up to last century 60s and 70s, The technic of conventionality second biology disposal was all-pervading in industrialized country and then it was found that only removing organism and float off is not enough and the exit of ammonia and nitrogen all the same bring on a series of environment pollution such as black water or low consistency of dissolving oxygen etc. Up to 70s and 80s, it come into being the phenomenon of Eutrophication of water bodies with the incessant increasing eduction of sewage, the abroad using of complex scour, fertilizer and pesticide and rapid increasing content of N, P in the entrance water. The immediate result is that large numbers of fish died and it engendered disadvantage influence to industry product, agriculture irrigation and life use water. So it has engendered disastrous economy direct or indirect. Therefor, our country has recently promulgated the standard of contamination put out by sewage disposal factory in the town(GB18918-2002) which bring forward a strict eduction standard of nitrogen and phosphorus. It predicate that most establishment of dealing with city sewage and industry waste water all need to be consider removing nitrogen and phosphorus. Accordingly, this research aimed water disposal process of Jinan water decontamination first factory which primary object is removing organism including carbon. Based on analysis of manyyears operation condition of the factory, integrating various ripe biological nitrogen removal system and fully considering the process character of the factory, based the fundamental of little change, economic invest, mature technology, steady operation, simple manage, seemly or lower cost etc, ameliorate scheme of the process has been put forward and carried through calculation and test. And then the process and the effect of nitrogen removal system have been ameliorated at operation under the design parameter. The result be as follows:1. Analysis by the ingoing water quality and operation effect last many years of existing traditional process of Jinan water decontamination first factory, can know:The factory ingoing water BOD5 at about 150mg/l, CODcr at about 350mg/l, TN=25-45mg/l (average 40mg/l), NH3-N=15-35mg/l (average30mg/l),C/N=CODcr/TN=350/35>8 or BOD5/TN=150/35>4, indicating it can be carrying through biological nitrogen removal.Effluent water: because of the adapted city sewage transportation conduit net hasn't been consummate. Therefore the actual disposal water is 1/4-1/2 of design capability of the factory almost time. Additional not too high consistency of the ingoing water, the lower operation burthen and adopting the intermittent aeration operation, So the effluent water has better nitrogen removal effect sometimes. But it is very instable. BOD5 at about 10mg/l, CODcr at about 40mg/l, TN=25-40mg/l, NH3-N=15-30mg/l.2. Based on the factory basic process equipment, the instance of ingoing water and the request of effluent water quality of GB18918-2002, prefix anoxic denitrification-aerobic process namely A/O process based on analysis of each mature nitrogen removal process has been chosen to be the rebuilding scheme of the oldfactory to enhancing nitrogen removal effect.3. The design and calculation of A/O process: Based on the character of the quality and quantity of ingoing water, combining with air temperature condition (water temperature 14 °C -25 °C ), combining with the condition of existing tradition process of the old factory sufficiently, carrying through the design and calculation has been carried through for the purpose of the request (first grade B) for effluent water quality of GB18918-2002. The result have been received via calculation such as SRT=15.6d, availability cubage of formation process container etc. And it has used to instructing the design and operation of small test model.4. Model Test in Laboratory:After stabile operation, the effluent water and nitrogen conditions and the nitrogen removal effect have been gained at the chosen conditions (parameter: DO=2-3mg/l, MLSS=4000mg/L, SRT=15.6d) via testing guide line of CODCr, TN, NH3-N of ingoing and effluent water and DO, MLSS, MLVSS, SV%, SVI etc of reaction cubage.5. The result acquired via series works so you say as follows: At the conditions of using exiting process flow and equipment of old factory, the exiting primary clarifier shorten waterpower settle time. The leaving part has been rebuilt to anoxic reactors (waterpower settle time 1.78h). Foregone treatment plant has been broaden (waterpower settle time by 4.8h enhance to 6.4h). The exiting send-back system has been changed. Inner send-back system has been increased. In this way the system has been changed to MLE (A/O) process. In the condition of MLSS=4000mg/l, SRT=15.6d , the nitrogen removal effect of water could be attained. |
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