The Technological Study On The Remove Of Organic Substances In Secondary Treated Sewage Effluent By Lime

Water resources are seriously insufficient in china, and the reuse of sewage effluent is an important method to alleviate the shortage of the water resources. The reuse of sewage effluent is practicable in technology, and have more advantages than the use of water across valleys and the use of seawater. The amount of the use of water in industry take much percentage in that in city, and it is mostly the cooling water, which is low in the demand of water quality. After the appropriate treatment, the secondary treated sewage effluent can be up to the water quality of the circulating cooling water.In the dissertation, as to the problems of the treatment with lime coagulating in the water treatment, and on the base of the remove of alkalinity with lime, the research removing the COD of the secondary treated sewage effluent was carried out, in order to be up to the water quality of the circulating cooling water.At firstly, the optimum conditions of which lime coagulating technology remove organic substances in the secondary treated sewage effluent were studied . The experimental results showed that the high removing rate of COD was attained by adding the amount of lime according to the calculation of hydroxide precipitation, which was about 30%, and the effluent was controlled under the 11.2 of pH value; adding powder lime had higher efficiency than other methods; that COD was efficiently removed by the order that lime was added at first, then flocculants; that by the compared experiment and the orthogonal experiment, it was proved that the optimum technology was lime + (PFS-PDMDAAC) +HPAM, by which the removing rate of COD was about 50%, the optimum dose of PFS was15~25mg/L, and the optimum dose of-PDMDAAC was 1.0~2.0mg/L, and the optimum dose of HP AM was 0.5~ 1mg/L.Secondly, lime coagulating technology to remove organic substance in the secondary treated sewage effluent were reformed, in which the active sludge was recycled, and the subsequent technologies was studied. The results showed that when that active sludge was added after lime and before PFS ,which improved the remove rate of organic substances, attaining about 70%; recycling active sludge which was fitted to the secondary treated sewage effluent in high quality with low turbidity; the secondary treated sewage effluent was treated with the reformed coagulating technology, which removed about 70% carbonate alkalinity , after the treatment with acid sulphate, and attained the demand of circulating cooling water, even the higher demand of water quality.