Solidification/Stabilization Of Polluted Sediment From Urban River And Its Performance For Plant Growing

Treatment and disposal of dredged sediment has become a key project of comprehensivecontrol planning for urban water environment. In order to explore the feasibility andsecondary pollution of dredged sediment reutilization, lime, desulfurized fly ash, bentonitewere used along with ordinary cement to solidify/stabilize the polluted sediment of Chebeiriver in Guangzhou, China. Solidification properties, stabilization of pollutants, andperformance of plant growing of solidification/stabilization (S/S) treatments were evaluated toinvestigate S/S effectiveness.Experimental results are as follows:(1)In this study, S/S treatments significantly increased unconfined compressivestrength. Most of S/S products were observed to be sufficient to achieve compressive strengthof300kPa, which reached the suggested disposal requirement of Resource Protection andRestoration Act (RCRA) promulgated by American.(2)While fly ash was used together with cement, lime and bentonite, fly ash collectedfrom different sources had different contribution on compressive strength of S/S products. Inthis study, fly ash collected from Zhujiang power plant is better on compressive strength thanthe one from Hengyun power plant.(3)The leaching test results showed that leaching ability of heavy metals in S/Sproducts was significantly reduced. Compared with the dry sediment(not added any materials),Pb, Cd, Mn, Fe, Cr, and Ni leaching concentration of S/S products reduced24.5%~33.5%,32.1%~53.8%,51.3~89.3%,45.5%~90%,14.3%~57.1%and53.9%~86.9%, respectively.(4)In the neutral conditions of pH, pollutant releasing concentration of S/S productswas significantly reduced. S/S treatment effectively slowdown and reduce the releasing ofpollutants under static condition. During the period of our experiment, different heavy metalhas different releasing regulation. Ni releasing showed no obvious rules, while Cr, Pb and Cdperformed a increase-stable trend. The release of Fe and Mn stably kept in a low level.(5)The leaching test and static releasing experiment results showed that fly ashcollected from Zhujiang power plant is better on performance of pollutants stablization than the one from Hengyun power plant.(6)In the experimental conditions, S/S products caused physiological stress to vetivergrass to some extent. Vetiver grass would adjust their shape and physiological response, thusadapting the growth environment of S/S products.