| The Chemical Enhanced Primary Treatment (CEPT) Process, which can remove more Pollutants at less cost and greatly increase the removal of organic substances in Primary treatment Process, or reduce the load of secondary treatment. In recent years, CEPT has been the subject of growing attention to water treatment industry. The determination of accurate dosage and treatment of coagulation sludge hindered the rapid development of CEPT.FeCl3 has been widely applied to wastewater enhanced primary treatment due to its low price and good results. Based on the mechanism of wastewater treatment, in this paper it has analyzed that the effect FeCl3 in the pretreatment of wastewater treatment, and the optimum dosage and comparative analysis of the ferric coagulation sludge and biological sludge in anaerobic digestion.The removal of phosphorus show well when the higher dosage of FeCl3; GT on the removal of phosphorus has little effect and pH6-8 is a better range for phosphorus removal; comprehensive economic considerations, PAM is not suitable for large dosage. Analysis the sediments of the FeCl3 with XRD showed that, when Fe:P is high (eg 2.0,2.5), sediments mainly includes hydroxy-iron phosphate and FeOOH (s) exist; however when Fe:P is low, mainly in sediments is primarily FePO4. The energy spectrum analysis shows that when adding high doses of FeCl3, the iron and phosphorus when the molar ratio higher than 1, resulting in waste of iron salt.Aiming at the issues that there are many factors in treating wastewater with chemically enhanced primary treatment system, and it is difficult in controlling properly and predicting the effect of treatment, the article sets up a forecasting model of treating wastewater with FeCl3 that based on BP neural network model and simulates beaker experiments. The model is three layers BP neural network, and hidden layers are respectively from 5 to 14. The model performance goal is 0.001 and the largest training steps of network are 1000. The performance of the final model with 12 hidden layers is 0.0092. The results indicate that the data of forecast are coincident with the experimental data well. The average relative errors of removal rates of COD, total phosphorus, PO43- and SS between forecast value and actual value were 11.2%,8.39%,9.92% and 8.99% respectively.This research compared the relative digestibility of iron-dosed with undosed activated sludge during two batch test trials. Results showed that both iron-dosed sludge and undosed activated sludge can produce a lot of methane which can used for combined heat and power production plant, and the VS degradation rates were 26% and 29% respectively. VS, particle of the sludge were obvious smaller after batch test trials which will be benefit for the further processing. Because some organic wrapping in the floc, the accumulation rates of methane in the iron-dosed sludge is slower and result in the gas yield is also less than undosed activated sludge. |
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