Natural Resources Extraction: Stressors and Impact Management - Sustainable Practices in Geoenvironmental Engineering - page 167

TABLE 5.5
Monitoring Requirements for an AMD Drainage Remediation Process

Category Parameter

Physicochemical pH

Redox potential
Total dissolved solids
Speciic conductance
Dissolved oxygen

Fe, Cu, Pb, Zn, Cd, Hg, As, SO 2−

Cationic and anionic species

Gases O 2 , CO 2 , SO 2 , H 2 S

Flow AMD low rate, hydrostatic pressure

Meteorological conditions Precipitation, temperature, sunlight, wind speed

Source: Adapted from Fytas, K. and Hadjigeorgiou, J., Environmental Geology , 25, 36-42, 1995.

(20 to 40 mm) placed in a trench of 3-5 m wide and 0.6-1.5 m in depth (Brodie et al., 1993).
The anoxic conditions in the trench are ensured by backilling with clay. A plastic geotex-
tile is placed between the clay and limestone. The inlet of the trench is placed at the source
of the AMD. However, when oxygen content in the drainage is greater than 2 mg/L or the
pH is greater than 6 and the redox potential is greater than 100 mV, use of the ALD is detri-
mental due to the formation of oxide coatings. Installation of a sedimentation pond before
the wetland treatment with or without ALD is preferred since it is easier to remove iron
precipitation from the pond than the wetlands. Sanders et al. (1999) have indicated that
wetlands systems were used to remove Zn, Fe, Cu, Pb, and some other heavy metals from
a moderate to severe acidic drainage from a mining complex in Montana. This treatment
will be required for decades. Long-term monitoring will be needed as shown in Table 5.5.

5.5.2.3 Biosorption

Biosorption is a potentially attractive technology for treatment of water containing dilute
concentrations of heavy metals. Activated carbon is the currently recognized adsorbent
for removal of heavy metals from wastewater. However, the high cost of activated carbon
limits its use in adsorption. A search for a low-cost and easily available and renewable
adsorbent has led to the investigation of wastes of agricultural and biological origin as
potential metal sorbents (Hammaini et al., 1999). Biosorption is the ability of certain types
of microbial biomass to accumulate heavy metals from aqueous solutions by mainly ion
exchange mechanisms. A large number of microorganisms belonging to various groups,
such as bacteria, fungi, yeasts, and algae have been reported to bind a variety of heavy
metals to different extents (Volesky and Holan, 1995).
The main requirement of an industrial sorption system is that the sorbent can be utilized
as a ixed or expanded bed for use in a continuous process. Immobilization techniques have
been developed, but the employment of immobilization procedures is expensive and com-
plex (Liu et al., 2003). Two attempts to market two different types of immobilized microbial
biomass, one by BV SORBEX and the other by the U.S. Bureau of Mines were not commer-
cially successful application (Tsezos, 2001). The feasibility of anaerobic granules for indus-
trial wastewater reactors was investigated as a novel type of biosorbent for the removal of
cadmium, copper, nickel, and lead from aqueous solution by Al Hawari and Mulligan (2006).