Abstract
At present, municipal solid waste incineration (MSWI) fly ash is mainly based on the solidification agent and then landfilled. How to make the fly ash harmless and reuse it will become an important step in the circular economy. In this study, the fly ash was treated by water extraction and milling to remove the soluble chloride ions and stabilize the heavy metals, and then the perforated plate was prepared by adjusting the composition and sintering technology. Research on biofilm colonization on the perforated plates is expected to achieve the purpose of stabilizing and recycling the fly ash. The fly ash is subjected to a solid-liquid ratio of 1:5 with two-stage water extraction, 2h ball milling, and then mixed at a mass ratio of waste glass powder, Palygorskite powder and the milled fly ash of 7:2:1, and calcined at 850°C for 20 minutes to prepare perforated plate. The results show that the prepared perforated plate has a rough surface, developed internal porosity, and its water absorption rate is 19.5%. The perforated plate is used as the biofilm carrier to be applied to the biological contact oxidation tank, and the natural biofilm colonization method is adopted for the 36-day biofilm culture. The average growth rate of the biofilm on the perforated plate reached 672.22 mg/(L·d), and the maximum microbial biomass was 12.1g/L.
Highlights
Since 2004, the amount of harmless waste incineration treatment in China has maintained rapid growth
The milled fly ash undergone toxicity leaching experiment to determine the concentration of heavy metals of the leaching solution by adopting the "Solid waste leaching toxicity leaching method-Acetic acid buffer solution method" (HJ/T 300-2007) Three materials of waste glass powder, palygorskite and the milled fly ash were mixed with a ratio of 7:2:1 and the perforated plate was sintered
The municipal solid waste incineration (MSWI) fly ash adopts a solid-liquid ratio of 1:5, and the soluble chloride salt can be effectively removed through two-stage water extractions
Summary
Since 2004, the amount of harmless waste incineration treatment in China has maintained rapid growth. A large amount of the fly ash is produced in the process of municipal solid waste incineration (MSWI), and its production is about 3%-5% (w/w) of the MSW amount [1]. Considering the increasing output of the municipal solid waste incineration (MSWI) fly ash and it is enriched by highly toxic heavy metals and dioxins, which will cause serious harm to the environment. The high concentration of chlorides pollutes the receiving waters during the fly ash disposal, which will increase the hazard risk of heavy metals and other pollutants, such as Pb and Zn. In addition, the inorganic chloride salts will bring difficulties for solidification/stabilization and the resource process of the fly ash. The disposal technologies of the MSWI fly ash mainly include solidification/stabilization and cement kiln co-processing, etc. Due to the large amount of the fly ash and limited land resources, the solidification landfill treatment method is unsustainable. How to effectively harmless and resource incineration fly ash has aroused widespread concern in the field of environmental protection
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