Release behavior of soluble salts in MSWI bottom ash used as road basement materials under continuous rainfall conditions

Release behavior of soluble salts in MSWI bottom ash used as road basement materials under continuous rainfall conditions

Zhao, Lingqin (Zhejiang University)
Zhang, Dongming (Zhejiang Zheneng Xingyuan Energy Saving Technology Co. Ltd)
Hu, Yanjun (Zhejiang University)
Guo, Qianqian (Zhejiang University)
Jiao, Long (Zhejiang University)
Zhou, Nan (Zhejiang University)
Di Maio, F. (TU Delft Resources & Recycling)

2023

The bottom ash is increasingly used as a substitute aggregate material in road construction in China, and road salting is the major salt source in groundwater. Continuous rainfall releases soluble salts from the bottom ash subgrade into the surrounding soil and groundwater, resulting in potential hazards. Different methods were employed to simulate and collect runoff water during rainfall events, including batch leaching test, dynamic leaching test and constant head test, to assess environmental impact of bottom ash as road basement materials under continuous rainfall conditions. This study simulated the seepage of bottom ash backfill roads under different rainfall intensities, rainfall times, and rainfall pH values. A comprehensive sampling and laboratory testing program was undertaken to characterize the environmental impact of soluble salts from bottom ash. The obtained results reveal that the leaching concentrations of Cl⁻ and SO₄²⁻ exceed the limit specified in the class V standard of surface water, which are 2.06–2.17 times and 1.08–1.25 times, respectively. By examining the long-term environmental influence under the condition of continuous rainfall, the leaching of Cl⁻ mainly occurs in the early leaching stage, and the maximum leaching concentration reaches 19,700 mg/L. The release concentration of Cl⁻ begins to be lower than the class V standard of surface water when continuous rainfall approaches the total rainfall for 13 months. The cumulative release of Cl⁻ in the bottom ash is 2.8–5.4 mg/g. Both rainfall intensity and rain pH affect the release of Cl⁻. The obtained results derived from the constant head tests indicate that stagnant water caused by rainfall deteriorates the release of soluble salt into the groundwater in only 1 day, especially at the early stage of 12 h. This work provides some basic information about how to minimize damage to the surrounding environment caused by the leaching of salt in bottom ash.

Continuous rainfall
Incineration bottom ash
Leaching
Municipal solid waste
Salts

http://resolver.tudelft.nl/uuid:3e98f1e9-10ab-4573-857b-8e72d285a37a

https://doi.org/10.1007/s42768-023-00161-3

2024-03-02

2524-7980

Waste Disposal and Sustainable Energy, 5 (4), 525-534

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2023 Lingqin Zhao, Dongming Zhang, Yanjun Hu, Qianqian Guo, Long Jiao, Nan Zhou, F. Di Maio