The Study On Sludge Solidification/Stabilization Using Cement With Sepiolite As Additive

With the increase of population and the development of industrial, the volume of urban sewage increased, so as the increases of sludge. High moisture content and organic content,smelly and easy to corrupt, containing large amounts of toxic and hazardous materials that hard to refractory are the characteristics of sludge, if not proper disposaled or if directly discharged into the environment, it is easily cause secondary pollution to the environment .Therefore, the safe disposal of sludge has caused global concern.In order to solve the problem of treatment and disposal of sweragesludge in China, based on the skeleton construction technology, by adding cement and other auxiliary curing agent into sludge ,the practical method using cement for sludge solidification/stabilization with sepiolite as additive was put forward.Through the unconfined compressive strength test, different curing agent content, water content, curing age on strength were studied, through the comparation of the effect of curing strength between the two curing materials as additive, the results showed that the use of sepiolite as a supplement did well on promting the cement hydration process,and the method using cement for sludge solidification/stabilization with sepiolite as additive was put forward. Leaching toxicity extraction test was performed to assess the stability of heavy metals in solidified sludge. The results show that sepiolite reduces the leaching ratio of Zn,Cu from the solidified sludge. The studies on compressive strength,volume change and wet and dry duration showed that incorporation of sepiolite can keep the solidifiedsludge with high compressive at low cement content,little Volume change, and good wet and dry durability.Though orthogonal test, the result showed that the factor influence on solidification body compressive strength primary and secondary was sepiolite> cement; by optimizing design, the relationship between the amount of curing agent was got, based on it as constraint conditions,made the cost to a minimum as objective function, after optimization ,the ratio of cement and sepiolite was obtained,that is 0.2:0.15,and under the ratio the cost was the minimum.Mechanical development of strength of the solidified sludge was researched by X-ray diffraction analysis and Scanning Electron Microscope/EnergyDispersive X-ray Spectrometry(SEM/EDS)analysis.The results show that: the strength of solidified sludge promoted with sepiolite as additive ware mainly for its strong absorption, for its inorganic properties to be the skeleton mixing with sludge and can promote the hydration of cement, and so on.