Partition coefficients for metals in surface water, soil, and waste

Reactions involved in the sorption of heavy metal cations and anions to the surfaces of inorganic and organic components of solid wastes are examined. The properties of various waste materials (e.g., fly ash, slag, red mud, water treatment sludge, fungal and bacterial biomass, tree bark, sawdust, paper mill sludge, seafood processing waste, and composted organics) and the use of these materials as heavy metal sorbents, in situ immobilizing agents, and stabilization-solidification agents are then reviewed and discussed. Specific adsorption/surface precipitation onto various mineral phases present on composite inorganic waste materials explains the capacity of such materials to sorb metals. Similarly, reactions of various functional groups (e.g., carboxyl, amine, hydroxyl, sulphydryl) on organic molecules (e.g., lignin, chitin, humic substances) with heavy metals explain the sorption capacities of biosorbents. Differences in operational parameters between studies make a comparison of sorption capacities bet...

Sorption of heavy metals by inorganic and organic components of solid wastes: Significance to use of wastes as low-cost adsorbents and immobilizing agents

Equilibrium studies for the sorption of zinc and copper from aqueous solutions using sugar beet pulp and fly ash.

This paper presents the shear strength characteristics of a low lime class F fly ash modified with lime alone or in combination with gypsum. Unconfined compression tests were conducted for both unsoaked and soaked specimens cured up to 90 days. Addition of a small percentage of gypsum (0.5 and 1.0%) along with lime (4–10%) enhanced the shear strength of modified fly ash within short curing periods (7 and 28 days). The gain in unsoaked unconfined compressive strength ( qu ) of the fly ash was 2,853 and 3,567% at 28 and 90 days curing, respectively, for addition of 10% lime along with 1% gypsum to the fly ash. The effect of 24 h soaking showed reduction of qu varying from 30 to 2% depending on mix proportions and curing period. Unconsolidated undrained triaxial tests with pore-pressure measurements were conducted for 7 and 28 days cured specimens. The cohesion of the Class F fly ash increased up to 3,150% with addition of 10% lime along with 1% gypsum to the fly ash and cured for 28 days. The modified fly a...

Strength Characteristics of Class F Fly Ash Modified with Lime and Gypsum

Fly ash for the removal of Mn(II) from aqueous solutions and wastewaters

A simple and inexpensive method of stabilization/solidification (S/S) of hazardous wastes using C-grade fly ash as the only binding agent is presented. The process involves mixing the waste and fly ash and compacting the mixture for less than 3 s at 1.4–6.9 MPa to form a monolith. Toxicity characteristic leaching procedure (TCLP) results for a simulated mixed waste showed that the chromium concentration in the leachate is well below current Environmental Protection Agency (EPA) limits. For this particular waste, TCLP results were not significantly affected by the ratio of waste:fly ash in the block due to the limited range of waste concentration that can be processed. Furthermore, it is shown that the optimum operating conditions are at a waste pH of 9.2 and an applied pressure of 4.65 MPa.

Jafar Parsa

Papers

Stabilization/Solidification of Hazardous Wastes Using Fly Ash