Study On Mathematical Models For High Salinity Oilfield Produced Water Oxidation Pond Treating

Oxidation Ponds, which are widely used to treat urban sewerage and some produced wastewater domestically and overseas, is a kind of low function costs sewerage bio-chemical treatment establishments, and have gotten prominent environmental and economic benefits. There have been very systemic experience and analysis for the practice, principle and design of fresh water oxidation ponds system. However, there are few open reports for high-salinity oilfield produced water oxidation ponds treatment. In order to accelerate this techniques perfect and spread use early, this article study further into the oxidation ponds mathematical models at Xianhe Plant, following succeeded in oxidation ponds treatment at Zhuangxi Gathering, Shengli Oilfield.In this article, C.I. Acid Red 73 and SCN" have been selected as tracers for laboratory and actual hydraulic residence time (HRT) respectively. By means of tracer experiments for laboratory rule- miniature model and anomalous- enlarged model, the hydraulic performance and mass transfer situation in them is investigated. The result shows that both of them prominently deviate off the reactor models of ideal plug- flow and completely- mixing, and can be described as reactor model with axial diffusion and model of continuous flow stirred tank reactors in series. The expressions for diffusion coefficient in each model is presented as follow.Rule- miniature model D=3.662H049u0987Anomalous- enlarged model D=8.24H2 7O5u 39.Based on similitude theory, the enlarged model in this paper is a geometrical similitude model, established by the border as short as 1/200 of the real pond's.In this study, credible mathematical models for real oxidation pond is established by using the results of a great deal of experiments; The formula of primary pollutant's reaction outcome in zero- order bio- chemical reactor andactive volume coefficient is deduced as follow.k T kTReactor model with axial diffusion Ce = Cn ~Pi: + .T0 Pe Pe 'Model of continuous flow stirred tank reactors in series Ce = Co - k,T aActive volume coefficient a = 1 - Pe~x (1 - e~Pc)The examination of real oxidation pond can be carried out by using the expressions of diffusion coefficient from enlarged model, the formula of active volume coefficient, and mathematical models of real pond.The results of examination verify the applicability of reactor model with axial diffusion and model of continuous flow stirred tank reactor in series to the produced water oxidation pond at Xianhe. It can be predict that the maximal treatment capability is 28000 m3/d as usual by the measure of setting diversion dykes properly, which increased 2.3 times than of no diversion dykes.This paper provide the field of oxidation ponds treatment for high-salinity organic wastewater with theory groundwork, and can be acted as foundation for project design and function management.