Fly ash from the municipal solid waste incineration (MSWI) which contains a small amount of heavy metals becomes a threat to human health and other living organisms once emitted into the environment, and has to be treated before disposal. This study focuses on the characteristics of the MSWI fly ash, which involve mineral composing, granularity distributing, specific surface area, pore diameter and pore volume of fly ash, leaching toxicity and chemical species of heavy metals. The experiment results confirm that the fly ashes are mainly composed of sylvite, halite, portlandite and calcium sulfate hydrate, with the the average particle diameter of 15.082 μm and the specific surface area of 4.290 m 2 /g, and the heavy metals such as Pb, Cu, Cr in the MSWI fly ash are mobile except Hg. This research provides critical information for appropriate MSWI fly ash treatment technology.
The geopolymer was chosen to immobilize the municipal solid waste incineration (MSWI) fly ash because of its strong fixing capacity for heavy metals. The fly ash-based geopolymer was synthesized from metakaolinite with MSWI fly ash under activation of sodium silicate solution, and then cured at relative humidity (RH) between 40% and 90% at 20°C. The ability of immobilization of heavy metals in MSWI fly ash with the geopolymer was evaluated in terms of the compressive strength and leaching concentration. The experimental results confirmed that the compressive strength of the resulting solidified body could achieve 35.13 MPa after 7 days of curing. Meanwhile, the leaching concentrations of Pb, Zn, Cu and Cr were 0.0230 mg/kg, 0.186 mg/kg, 0.231 mg/kg, and 6.56 mg/kg, respectively. We confirm that geopolymerisation is an effective alternative in the disposal of various hazardous wastes containing heavy metals.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
'%3e%3cg id='b'%3e%3cpath id='a' stroke='%23000' stroke-width='2' d='M-6-25H6m-12 3H6m-12 3H6'/%3e%3cuse xlink:href='%23a' y='44'/%3e%3c/g%3e%3cpath stroke='%23fff' d='M0 17v10'/%3e%3ccircle r='12' fill='%23cd2e3a'/%3e%3cpath fill='%230047a0' d='M0-12A6 6 0 0 0 0 0a6 6 0 0 1 0 12 12 12 0 0 1 0-24z'/%3e%3c/g%3e%3cg transform='rotate(-123.69)'%3e%3cuse xlink:href='%23b'/%3e%3cpath stroke='%23fff' d='M0-23.5v3M0 17v3.5m0 3v3'/%3e%3c/g%3e%3c/svg%3e)