Effect of air and water on the release of chlorine from semi-aerobic landfill

ABSTRACT

Landfill leachate has a high chloride (Cl⁻) content. Because it is highly mobile, and cannot be sorbed or transformed bio-chemically, it is important to have detailed information about how it migrates in landfill sites. In this study, we set up four lab-scale simulated landfills, including an anaerobic landfill (AL), an anaerobic landfill with leachate recirculation (RAL), an anaerobic/semi-anaerobic landfill with leachate recirculation (RASL), and an anaerobic/semi-aerobic landfill (ASL), to explore how, when regulated, moisture and air affected the migration of chlorine. We found that water and air had a strong influence on the release of Cl⁻. Leachate obviously promoted Cl⁻ dissolution in refuse when recirculated. When air was introduced into landfill, thereby changing it from anaerobic to semi-aerobic, the leachate Cl⁻ concentration increased sharply from around 4–9 g L⁻¹ (RASL) and 18 g L⁻¹ (ASL), respectively. In principle, Cl⁻ is released continuously when leachate is recirculated in landfills (RAL and RASL), but it can also be found a terminal when the leachate recirculation stops (AL and ASL). Cumulative amounts of 64, 66, 27, and 53 g of Cl⁻ were released from the AL, RAL, RASL, and ASL, respectively. Lower COD/Cl and $\text{N}{\text{H}}_4^{+}$-N/Cl ratios in ASL and RASL after day 175 indicated that lower Cl⁻ pollution risk than that in AL and RAL.

GRAPHICAL ABSTRACT

KEYWORDS:

• Chloride
• landfill
• leachate
• migration behaviour

Acknowledgements

The work was supported by the [National Natural Science Foundation of China] under Grant [41977331, 51778579, 21876165, and 51878617], and [Natural Science Foundation of Zhejiang Province] under Grant [LY18B070009].

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Natural Science Foundation of China [grant number 21876165,41977331,51778579,51878617]; Natural Science Foundation of Zhejiang Province [grant number LY18B070009].