Page 251 - Materials Chemistry, Second Edition

232 Life Cycle Assessment of Wastewater Treatment

TABLE 11.2
Advantages and Disadvantages of Different Treatment Methodologies for
Heavy Metal Removal from Groundwater
Treatment
Methodology Advantages Disadvantages
Chemical Some treatment chemicals are Extensive amount of sludge containing
precipitation relatively inexpensive. Minimal metals; financially expensive; high
maintenance and skilled operator synthetic requirements; parameters must
requirement are needed for be observed amid this strategy, which is
completely enclosed systems hazardous; transport of large amounts of
chemicals; addition of treatment
chemicals, especially lime, may increase
the volume of waste sludge up to 50%
Ion exchange Specific removal of metal particles Expensive (synthetic resins), large-scale
application, smaller number of metal
particles removed, high upkeep and
operational cost, regeneration can cause
serious secondary pollution, cannot be
used on a large scale
Adsorption High effectiveness of metal High cost of activated carbon, execution
particle removal, low energy, relies on the adsorbent
broad scope of target toxins, easy
operation, minimization of
biological sludge, no additional
nutrient requirements, prospect
of metal recovery, and moreover,
the adsorbent material is cheap
Membrane Extremely high selectivities, little Membrane fouling, capital cost,
filtration space required maintenance, limited flow rates, lower
efficiency at lower metal particle
concentration, process complexity,
membrane fouling, and low permeate flux
Coagulation Dewatering qualities More sludge settling, costly reagents,
chemical use
Electrochemical No substance use Necessity of filtration process for flocs,
treatment practical and running expenses, high
initial capital investment, and expensive
electricity supply
Electro-winning Environmental compatibility Waste generation, recycling
Cementation Recovery of metals in relatively Excess sacrificial metal consumption
pure metallic form, simple
control requirements, low energy
consumption, and is in general a
low-cost process