Experimental Research On The Remediation Of Sediment In Black-Odorous Rural River By Using Biostimulant And Microbial Agent

In order to explore an in-situ remediation technology of sediment in black-odorous Zhupai Creek, the biostimulant and microbial agent were used to carry out pilot experiments. And aeration was used as a supporting measure. The sediment, as well as the overlying water, of black-odorous rural river was restored during the experiment. Results show that:(1) The remediation effects of sediment and overlying water by biostimulant and microbial agent can be improved by aeration. Results of intermittent aeration were much close to those of continuous aeration. And intermittent aeration is more appropriate for the growth of facultative bacteria and energy saving. Thus intermittent aeration can be used as a supporting measure from the point of view of remediation effect and energy saving.(2)20mL/m3dosage of biostimulant had better remediation effect when the biostimulant was used separately to restore sediment in black-odorous Zhupai Creek. After60days of experiment, the sediment reduction, removal of organic matters, growth rate of G and the oxide layer were4.31cm,11.10%,269.00%and2.35cm respectively. The removal of NH3-N and TN in overlying water was relatively high (98.44%and67.73%respectively). However, the removal of CODCr and TP by biostimulant was not up to much. The removal rates were46.02%and57.63%respectively. The overlying water changed from serious black-odorous to mild black-odorous by using biostimulant seperately. The improvement effect is not so perfect enough to eliminate the black-odorous phenomenon.(3) Restoration of overlying water by microbial agent is relatively satisfactory although the remediation of sediment is not as good as that of biostimulant. The growth rate of G value of sediment reached317.00%(1mL/L dosage). The highest removal rate of NH3-N, TN and TP were99.29%(10mL/L dosage,70.74%(1mL/L dosage) and67.19%(1mL/L dosage) respectively. Removal rate of CODCr was relatively low (45.25%,1mL/L dosage). The overlying water changed from serious black-odorous to mild black-odorous and the black-odorous index was pretty much to the critical value, which means that the restoration effect of overlying water was evident.(4) The combination of biostimulant and microbial agent can have excellent restoration effect to sediment as well as overlying water. The optimal dosages were20mL/m3biostimulant and1mL/L microbial agent. Under this dosage, the sediment reduction, removal of organic matters, growth rate of G and the oxide layer were4.95cm,18.98%,336.00%and3.25cm respectively after60days experiment. The removal rate of CODCr, TN, NH3-N and TP were62.86%,74.25%,99.42%and63.64%respectively. And the black-odorous phenomenon was eliminated.(5) The remediation speed has been increased and the remediation time has been reduced by the combination of biostimulant and microbial agent. The microbial community structures of sediment were analyzed by ERIC-PCR technology and the results showed that when BS or MA was used separately, microbial community reached stable stage after30days. The change rates of indexes of sediment stabilized after30days, and the concentration of pollutants in overlying water stabilized after50days. However, when BS and MA were used together, microbial community reached stable stage after15days. The change rates of indexes of sediment stabilized after20days, and the changes of concentration of pollutants in overlying water slowed down and tend to stabilize after35days.From the results above we can see that biostimulant and microbial agent have satisfactory remediation effects on sediment and overlyling water in black-odorous Zhupai Creek. They are suited for in-situ remediation of black-odorous Zhupai Creek.