Utilization of Water Hyacinth for Removal and Recovery of Silver from Industrial Wastewater

Abstract

The water hyacinth (Eichhorniacrassipes) was studied as a pollution monitor for accumulation of silver and subsequent recovery of the element from the plant tissues. After cultivation of the plants for 24 hours in silver solution containing 40 mg/l the plants were harvested, rinsed with tap water and dried at 110°C for 48 hours. The dried material was submitted to pyrolysis and chemical digestion and the silver absorbed by the plant was precipitated, calcinated and recovered in the metal form. The average concentration of silver was found to be 8,000 mg g−1 of dried plant material. An Atomic Absorption Spectrophotometer was utilized for the analysis. The average concentration of silver recovered from the dried plant material, was 70% of the initial silver concentration of the silver solutions and revealed a purity of 98%. The water hyacinth has the potential of producing 873/ha/day of dried material and can be used for the production of biogas rich in methane (Wolverton, B.C.; McDonald, R.C.). After the wastewater treatment, the harvested plants can be used for biogas production and the residual sludge may be utilized for recycling the valuable metal.

Water quality improvement through macrophytes—a review

“…Eichhornia crassipes has the unique property to accumulate heavy metals Cd, Cu, Pb and Zn from the root tissues of the plant (Muramoto and Oki 1983;Nor 1990). Pinto et al (1987) demonstrated that the Eichhornia crassipes would also remove silver from industrial wastewater for subsequent recovery with high efficiency in a short time. Wolverton and McDonald (1976) observed that Eichhornia crassipes could purify water due to its rapid growth in polluted wastewater and the capacity to absorb heavy metals.…”

Nutrient removal by floating aquatic macrophytes cultured in anaerobically digested flushed dairy manure wastewater

“…The reduction in EC in relation to root biomass could be due to the ability of the roots to take up certain ions. Water hyacinth has the ability to absorb and accumulate or translocate metal, organic and inorganic substances through its roots (Pinto et al, 1987). The marked decrease in Na + concentration in the diluted water hyacinth culture indicates that the uptake of sodium ion during plant growth was substantial (Table 4).…”

Physiological responses induced by copper bioaccumulation in Eichhornia crassipes (Mart.)

“…It is easy to culture in the laboratory, and generally grows well, even in heavily polluted waters. It has a high capacity to take up a variety of heavy metals from aqueous solution, including Cu, Zn, Ni, Cd and Ag (Chua, 1998;Ghabbour et al, 2004;Pioto et al, 1987;Li et al, 1995;Soltan & Rashed, 2003). The bioconcentration factors (BCFs) of the roots of E. crassipes for Cu 2+ are high relative to those of other plants (Zaranyika & Ndapwadza, 1995).…”