id	author	title	date	pages	extension	mime	words	sentence	flesch	summary	cache	txt
cet-12758		cet-12758		6	.pdf	application/pdf	2988	108	51	Since AMD persists long after abandonment of mine operations, passive treatment system may provide the long-term solution that can be made sustainable using materials that are cheap and derived from waste. Passive treatment systems are viewed as a method that is better economically because they do not need continuous chemical inputs like in active treatment systems (Kefeni et al., 2017).	cache/cet-12758.pdf	txt/cet-12758.txt