Phytoremediation of heavy metal-contaminated wastewater by some - - PowerPoint PPT Presentation

Phytoremediation of heavy metal-contaminated wastewater by some aquatic plants

Nguyen Viet Hung, Nguyen Van Noi, Nguyen Dinh Bang

Faculty of Chemistry, Hanoi University of Science, Vietnam National University

Introduction

! With her “Open door” policy, Vietnam is on

the way of industrialization and modernization.

! Recently, living standard of Vietnamese has

been improved considerably. However, environmental pollution has also become a concerning problem in Vietnam.

! Heavy metal-contaminated wastewater has

posed threats to public health in many areas

• f the country

! In this study, phytoremediation--an

environment-friendly method--was tested for feasibility in treatment of metal contaminants

Sources of heavy metal pollution in Vietnam

! Mining activity – spread of mine spoil and

tailings and, in some cases, by the use of heavy metals in ore processing, e.g. the use of mercury in gold mining

! I ndustrial activity the processing and

reclamation of metals by industry has led to the widespread contamination of soils and water

! Wastewater reuse due to the lack of

treatment and the mixing of industrial and domestic wastewaters

! Fertilizers containing various trace metals

Advantages of Phytoremediation

! Phytoremediation is cheaper than

conventional treatment approaches such as incineration and soil washing

! Phytoremediation may increase the slow pace

• f hazardous waste cleanup. More sites may

be cleaned up simultaneously

! Phytoremediation leave topsoil in usable

condition and reduce the amount of contaminated material to be landfilled or incinerated.

!

Phytoremediation makes landscape acceptable for neighboring residents

Potential of applying phytoremediation in Vietnam

! Vietnam, a tropical country, has a vast

biodiversity of flora

! Many aquatic plants (submersed, emersed

and floating) are capable of cleaning organic contaminants from polluted water. Moreover, inorganic contaminants (including heavy metals) can also be treated (remove, transfer, stabilize, and destroy) by using different aquatic macrophytes.

Selected aquatic plants

! Water hyacinth (Eichhornia crassipes ) ! Water lettuce (Pistia stratiotes)

Heavy metal contaminants, experimented with phytoremediation in this study

! Pb2+ ! Cu2+ ! Ni2+ ! Cr6+ ! Cr3+

Industrial wastewater discharge standards

According to the Vietnam Standards TCVN 5942-1995

0.5 0.1 0.05 mg/l Arsenic 7 0.01 0.005 0.005 mg/l Mercury 6 2 1 0.2 mg/l Chromium (III) 5 0.5 0.1 0.05 mg/l Chromium (VI) 4 2 1 0.2 mg/l Nicken 3 5 1 0.2 mg/l Copper 2 1 0.5 0.1 mg/l Lead 1 C B A Limitation values Unit Parameters No

Experimental Design

ReferenceTank Experimental Tank

Magnetic Stirrer Water lettuce

Picture of the experimental tank with water lettuce

Analytical methods

! Water samples (from both experimental

and reference tanks) were analyzed

! Samples underwent filtration and

acidification steps prior to AAS analysis

! Calculation of concentrations of metal

contaminants in samples were based on the pre-established calibration curve

Obtained results

Temporal change of Pb concentration in the phytoremediation experiment using water hyacinth

2 4 6 8 10 12 14 1 2 3 4 5 6 Time (days) Concentration of Pb

2+(mg/l)

Reference tank Experimental tank

Obtained results

Temporal change of Cu concentration in the phytoremediation experiment using water lettuce

1 2 3 4 5 6 1 2 3 4 5 6 7 Time (days) Concentration of Cu2+ (mg/l) Reference tank Experimental tank

Obtained results

Temporal change of Ni concentration in the phytoremediation experiment using water lettuce

1 2 3 4 5 6 1 2 3 4 5 6 7 Time (days) Concentration of Ni

2+ (mg/l)

Reference tank Experimental tank

Obtained results

Temporal change of concentrations in mixture of Ni and Cu during the phytoremediation experiment using water lettuce

1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 Time (days) Concentration of Ni

2+ & Cu 2+

(mg/l) Concentration of Cu Concentration of Ni

Obtained results

2 4 6 8 10 12 1 2 3 4 5 6 7 8 9 10 11 12

Time (days) Concentration of Cr

3+ (mg/l)

Experimental tank

Temporal change of concentration of Cr (III) during the phytoremediation experiment using water lettuce

Conclusion

! Obtained results show that water

hyacinth and water lettuce can be applied effectively to treat wastewater containing heavy metal contaminants at concentrations less than 10 mg/l.

! Phytoremediation with its proved

advantages is very suitable for Vietnam, which has abundant and bio-diversified aquatic plants