The Research Of Technique For Repairing And Keeping The Xi'an Moat

The Xi'an moat, that flows around the Xi'an city wall, is an originally pure and beautiful city river .But with the development of the city and the progress of the residents' living level, the contramination of the Xi'an moat is serious gradually . To improve the quality of the water in the Xi'an moat, and to make a good environment for the residents, the government of Xi'an makes a firm decision to harness the moat. This text can be a beneficial reference to the plan of curing the moat with its investigations and experiments.The continent of this text divides tow parts . One is the investigations and experiments of the sources of pollution . Another part is the experiments and the analysis of the programs to harness the moat. And the first part include: the analysis of pollution caused by the water from the sewer pipes and the rain water pipes at each side of the moat, the analysis of the quality of the rain-water in Xi'an, the research of characters that the polluted sediments' releasing that in different bottom of the moat and analysis on its result, the influence that the plant growing in each littoral of the moat makes . From this study we can know a quantity of domestic wastewater and a great deal of living garbage are casted into the Xi'an moat and these will make a serious effect on the river. The rain water in Xi'an can bring a huge influence on the water . The characters that the polluted sediments' releasing indicate that from different site the sediment taken , the speed and strength of the sediments' releasing are different. The concentration of COD vary in scope of 20 mg/L to 120 mg/L, and its dates matching the logarithmic curve basically . The concentration of PO43- from 0.02 mg/L to 0.06 mg/L .The experiment of the plant growing besides the moat indicate that the plant make a bad influence on the water and under the existing thelevel of management, the plant pollute the moat seriously . And this period is almost 15 days , then the situation will become the most serious . The maximum of COD can get to 48.2 mg/L , PO43- can get to 0.04 mg/L and NH3- can get to 5.83 mg/L . The program of harnessing the moat we research are follow . First , keep the present condition , and aerating in the moat to increasing DO in the water , make the various microorganism in the river to degrade the pollutant. Second , digging up the polluted sediments and aerating in the river . Third , using the creature growing in artificial float to purify the river . Forth , adding effective microorganisms into the moat to decline the pollutant. To manage the pollutant in the moat we suggest that the whole engineering be divided into two stages . We can start it with harnessing the moat from outer. Now the point sources can not be managed effectively, we should control it by generating oxygen or adding effective microorganisms or the creature in artifical float and make the water satisfy the requisition . Then by digging up the polluted sediments or repairing and reforming the pipe network we can keep the moat pure permanently . And the oxygen generator can be the emergency facility, and make the losing least.