Passive bioremediation technology incorporating lignocellulosic spent mushroom compost and limestone for metal- and sulfate-rich acid mine drainage

ABSTRACT

Passive bioremediation of metal- and sulfate-containing acid mine drainage (AMD) has been investigated in a batch study. Multiple substrates were used in the AMD remediation using spent mushroom compost (SMC), limestone, activated sludge (AS), and woodchips (WC) under anoxic conditions suitable for bacterial sulfate reduction (BSR). Limestones used were of crushed limestone (CLS) and uncrushed limestone, provided at two different ratios in mixed substrates treatment and varied by the proportion of SMC and limestone. The SMC greatly assisted the removals of sulfate and metals and also acted as an essential carbon source for BSR. The mixed substrate composed of 40% CLS, 30% SMC, 20% AS, and 10% WC was found to be effective for metal removal. Mn, Cu, Pb, and Zn were greatly removed (89–100%) in the mixed substrates treatment, while Fe was only removed at 65%. Mn was found to be removed at a greatly higher rate than Fe, suggesting important Mn adsorption onto organic materials, that is, greater sorption affinity to the SMC. Complementary with multiple treatment media was the main mechanism assisting the AMD treatment through microbial metal reduction reactions.

KEYWORDS:

• Acid mine drainage
• bacterial sulfate reduction
• passive bioremediation
• spent mushroom compost
• limestone
• heavy metal

Acknowledgments

The authors gratefully acknowledge the technical assistance by the Minerals and Geoscience Department, Perak, Imerys Minerals Malaysia Sdn. Bhd, and laboratory assistants of Faculty of Environmental Studies, Universiti Putra Malaysia.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was primarily supported by Universiti Putra Malaysia under the research project no. GP-IPS/2014/9438721. The authors also thank the support from research grants no. FRGS 5524261 (Ministry of Higher Education, Malaysia), IPM 9433300, and UNESCO TWAS-COMSTECH Joint Research Grant FR:3240270866.