Study On Phosphorus Removal Activated Sludge Granulation By Starch And Getting P-rich Solution

In a large number of phosphorus removal process, biological phosphorus removal process is widely used in wastewater treatment because of its low cost, high efficiency, no more pollution and so on. The A/O process is widely used in the biological phosphorus removal process, which has a good effect of phosphorus removal. However, there are some problems in practical operation: the performance of phosphorus removal in system is instable, the excess sludge not only consumes much of energy but also causes the loss of phosphorus. Granular sludge has the advantages of good setting performance, high microbial content, strong ability of resistance to impact load, with good prospect for development. Compared with the traditional aerobic granular sludge or anaerobic granular sludge, the culture time of phosphorus removal granular sludge is longer, which limits its application in wastewater treatment. So how to quickly develop phosphorus removal granular sludge has become a problem to be solved. Starch can promote the condensation of the flocculent sludge and acts as carbon source. Taking the hydraulic selection pressure and biological selection pressure into consideration, starch may be accelerate the granulation of sludge. This paper uses two SBR reactors, study the rapid granulation of phosphorus removal floc sludge, getting p-rich solution by enrich phosphorus experiment, which is prepared for the subsequent phosphorus recovery.In order to explore the effect of starch on the granulation of phosphorus removal floc sludge, the activated sludge was inoculated from the wastewater treatment plant. In fact, the completion of granulation in reactor 2# which has starch used only 24 days, a quarter shorter than 1# which has sodium propionate, which showed that starch helps to accelerate the granulation of phosphorus removal sludge. The TP and COD removal rate of 2# are 95% and 90% respectively, which was similar with the COD and TP removal ability of 1#, indicating that starch has no much effect on the system. Furthermore, starch plays the role of carbon source can induce free microorganisms to move to it, makes a larger biomass and density of the particle is higher, which are conducive to the stable operation of the system.Efficient phosphorus recovery should be carried out in higher phosphorus concentration solution, so get p-rich solution is a prerequisite for phosphorus recovery. In order to obtain the p-rich solution, in this test, the phosphorus removal granular sludge is regarded as the carrier, PAOs takes up P from simulated wastewater at aerobic phase, P-release happens in circulating fluid at anaerobic phase, It can continuously release P into circulating fluid by such a cycle of operation. So the concentration of phosphorus in the circulating fluid increased to 102mg/L finally and easy to carry on the follow-up phosphorus recovery processing. In the process of enrich-p experiment, the COD and TP concentration at below 45mg/L and 0.5mg/L respectively in effluent, indicating a good processing performance. In order to improve the efficiency of p-release in the system, it should increase the proportion of PAOs in microbial population. By discharging the partial surface sludge can effectively improve the P/C of system, increasing the rate of P-release and saving the time of the experiment.At last, carry out the experiment of enrich-p in domestic sewage to prepare for the phosphorus recovery from domestic sewage. Gradually increase the proportion of domestic sewage under the conditions of stable operation of the system. Because of the complex composition of pollutants in domestic sewage, the highest phosphorus concentration in circulating fluid is 96mg/L, which is less than that from simulated wastewater. The experiment provides a prerequisite for the recovery of phosphorus in domestic sewage. The COD and TP concentration of effluent in aerobic terminal are reached the effluent standards, however, the NH4+-N concentration is too high, which can considered using CANON process to removal the N in raw water.Through these studies, we can provide technical reference for the practical application of the phosphorus removal granular sludge and how to obtain the p-rich solution.