Study On The Prediction Of Water Supply Boundary Zone And Iron Release Control

There are water supply boundary zones between different water plants in multi-source water supply areas.Due to long water age and unstable hydraulic water quality conditions,water quality problems such as excessive iron release are easy to occur.To determine the location of water supply boundary zone and control its iron release by physical and chemical methods can improve local water quality and water safety.In this paper,the "spatial correction interpolation method of characteristic water quality index" is proposed to predict the water supply boundary zone.Through EPANET hydraulic simulation,the improvement effect of the fluctuation of the pressure regulating control boundary zone on the water age of nodes is studied,and a"multi factor fitting comparison method" is proposed to comprehensively compare the corrosion inhibition effect of different phosphates,which provides a reference for physical and chemical methods to control the iron release of the boundary zone pipe section.Taking H City,which is supplied by two waterworks as an example,the interpolation results of the spatial correction of the general characteristic index conductivity and the total iron concentration of the sensitive characteristic index in this city are basically consistent with the simulation results of the hydraulic model,and the frequent changes of the flow velocity and flow direction are observed in the predicted boundary zone,which shows that the prediction results are correct and the method is feasible.Compared with the hydraulic model,the prediction results of characteristic indexes can more directly reflect the influence range of mixing in water quality change,which is more instructive for the actual monitoring of water quality in the boundary zone.Hydraulic simulation pressure regulation controls the fluctuation of the boundary zone.In the original zone,about 90%of the nodes with water age more than 72h are effectively reduced(water age is reduced by more than 15%);the nodes with iron concentration exceeding the standard are reduced by 44.7%,which shows that the water age can be effectively reduced and iron release can be controlled theoretically.Comparison of corrosion inhibition effects of five kinds of phosphates on ductile iron pipe and gray cast iron pipe by multi factor fitting method.The results show that NaH2PO4 has the best effect and applicability,and the corrosion inhibition effect can be enhanced by increasing dissolved oxygen in water.