Mushrifah Idris

A Review on Heavy Metals (As, Pb, and Hg) Uptake by Plants through Phytoremediation

Heavy metals are among the most important sorts of contaminant in the environment. Several methods already used to clean up the environment from these kinds of contaminants, but most of them are costly and difficult to get optimum results. Currently, phytoremediation is an effective and affordable technological solution used to extract or remove inactive metals and metal pollutants from contaminated soil and water. This technology is environmental friendly and potentially cost effective. This paper aims to compile some information about heavy metals of arsenic, lead, and mercury (As, Pb, and Hg) sources, effects and their treatment. It also reviews deeply about phytoremediation technology, including the heavy metal uptake mechanisms and several research studies associated about the topics. Additionally, it describes several sources and the effects of As, Pb, and Hg on the environment, the advantages of this kind of technology for reducing them, and also heavy metal uptake mechanisms in phytoremediation technology as well as the factors affecting the uptake mechanisms. Some recommended plants which are commonly used in phytoremediation and their capability to reduce the contaminant are also reported.

Phytoremediation of Wastewater Containing Lead (Pb) in Pilot Reed Bed Using Scirpus Grossus

Phytoremediation is a technology to clean the environment from heavy metals contamination. The objectives of this study are to threat Pb contaminated wastewater by using phytoremediation technology and to determine if the plant can be mention as hyperaccumulator. Fifty plants of Scirpus grossus were grown in sand medium and 600 L spiked water in various Pb concentration (10, 30 and 50 mg/L) was exposed. The experiment was conducted with single exposure method, sampling time on day-1, day-14, day-28, day-42, day-70, and day-98. The analysis of Pb concentration in water, sand medium and inside the plant tissue was conducted by ICP-OES. Water samples were filtered and Pb concentration were directly analyzed, Pb in sand samples were extracted by EDTA method before analyzed, and Pb in plant tissues were extracted by wet digestion method and analyzed. The results showed that on day-28, Pb concentration in water decreased 100%, 99.9%, 99.7%, and the highest Pb uptake by plant were 1343, 4909, 3236 mg/kg for the treatment of 10, 30, and 50 mg/L respectively. The highest BC and TF were 485,261 on day-42 and 2.5295 on day-70 of treatment 30 mg/L, it can be mentioned that Scirpus grossus is a hyperaccumulator.

Phytoremediation of lead (Pb) and Arsenic (As) by Melastoma malabathricum L. from Contaminated Soil in Separate Exposure

This study was conducted to investigate the uptake of lead (Pb) and arsenic (As) from contaminated soil using Melastoma malabathricum L. species. The cultivated plants were exposed to As and Pb in separate soils for an observation period of 70 days. From the results of the analysis, M. malabathricum accumulated relatively high range of As concentration in its roots, up to a maximum of 2800 mg/kg. The highest accumulation of As in stems and leaves was 570 mg/kg of plant. For Pb treatment, the highest concentration (13,800 mg/kg) was accumulated in the roots of plants. The maximum accumulation in stems was 880 mg/kg while maximum accumulation in leaves was 2,200 mg/kg. Only small amounts of Pb were translocated from roots to above ground plant parts (TF < 1). However, a wider range of TF values (0.01–23) for As treated plants proved that the translocation of As from root to above ground parts was greater. However, the high capacity of roots to take up Pb and As (BF > 1) is indicative this plants is a good bioaccumulator for these metals. Therefore, phytostabilisation is the mechanism at work in M. malabathricums uptake of Pb, while phytoextraction is the dominant mechanism with As.

Phytotoxicity of wastewater containing lead (Pb) effects scirpus grossus

Phytoremediation is an environment-friendly and cost-effective method to clean the environment of heavy metal contamination. A prolonged phytotoxicity test was conducted in a single exposure. Scirpus grossus plants were grown in sand to which the diluted Pb(NO3)2 was added, with the variation of concentration were 0, 100, 200, 400, 600, and 800 mg/L. It was found that Scirpus grossus plants can tolerate Pb at concentrations of up to 400 mg/L. The withering was observed on day-7 for Pb concentrations of 400 mg/L and above. 100% of the plants withered with a Pb concentration of 600 mg/L on day 65. The Pb concentration in water medium decreased while in plant tissues increased. Adsorption of Pb solution ranged between 2 to 6% for concentrations of 100 to 800 mg/L. The Bioaccumulation Coefficient and Translocation Factor of Scirpus grossus were found greater than 1, indicating that this species is a hyperaccumulator plant.

A phytotoxicity test of bulrush (Scirpus grossus) grown with diesel contamination in a free-flow reed bed system.

In this study, bulrush (Scirpus grossus) was subjected to a 72 day phytotoxicity test to assess its ability to phytoremediate diesel contamination in simulated wastewater at different concentrations (0, 8700, 17,400 and 26,100mg/L). Diesel degradation by S. grossus was measured in terms of total petroleum hydrocarbon (TPH-D). The TPH-D concentration in the synthetic wastewater was determined with the liquid-liquid extraction method and gas chromatography. S. grossus was found to reduce TPH-D by 70.0 and 80.2% for concentrations of 8700 mg/L and 17,400mg/L, respectively. At a diesel concentration of 26,100mg/L, S. grossus died after 14 days. Additionally, the biomass of S. grossus plants was found to increase throughout the phytotoxicity test, confirming the ability of the plant to survive in water contaminated with diesel at rates of less than 17,400mg/L.

Performance assessment of pilot horizontal sub-surface flow constructed wetlands for removal of diesel from wastewater by Scirpus grossus

One of the appropriate development technology options for the treatment of wastewater contaminated with diesel is constructed wetlands (CWs). Throughout 72 days of exposure, sampling was carried out for monitoring of physical parameters, plant growth and the efficiency of total petroleum hydrocarbon (TPH) removal, as an indication for diesel contamination, to assess the pilot-scale performance. Four pilot CWs with a horizontal sub-surface flow system were applied using the bulrush of Scirpus grossus. The CWs were loaded with different diesel concentrations of 0, 0.1, 0.2 and 0.25% (Vdiesel/Vwater). The TPH removal efficiencies were 82, 71, and 67% at the end of 72 days for diesel concentrations of 0.1, 0.2, and 0.25% respectively. In addition, the high removal efficiency of total suspended solids and chemical oxygen demand (COD) were 100 and 75.4% respectively, for a diesel concentration of 0.1%. It was concluded that S. grossus is a potential plant that can be used in a well-operated CW for restoring 0.1% diesel-contaminated water.

Isolation and screening of arsenic resistant rhizobacteria of Ludwigia octovalvis

Ludwigia octovalvis was characterized for its potential in arsenic phytoremediation. Epiphyte rhizobacteria from the roots of L. octovalvis were isolated in five different arsenic concentrations (4, 20, 40, 60 and 80 mg kg -1 ) and control after single exposure for 35 days. Results show that 109 colonies were isolated which were further grouped into 29 groups of isolated rhizobacteria. After preliminary screening, 17 rhizobacterial isolates were considered to be resistant to arsenic (arsenate or As[V]) and after secondary screening, 12 rhizobacterial isolates showed potential resistance to arsenic. Identification was conducted using biolog GEN III microbial identification system. One of the arsenate potentially resistant rhizobacterial was identified as Arthrobacter globiformis . The k (growth rate constant) value of A. globiformis was 0.112 h -1 with g (generation time) value of 8.943 h and i (specific growth rate) value of 0.077 h -1 . Minimal inhibitory concentration (MIC) value of A. globiformis on arsenate exposure was 500 mg L -1 and has the potential to promote arsenic phytoremediation at contaminated site. Key words : Phytoremediation, arsenic, isolation, screening, identification, minimal inhibitory concentration (MIC).

Saringan tumbuhan akuatik tropika tempatan untuk rawatan penyudahan sisa pulpa dan kertas

Pulp and paper mill industry is one of the biggest water users that produce wastewater containing dye and various toxic compounds. The study was conducted to screen for potential tropical native aquatic plants, which can be used in phytoremediation mainly for the removal of colour and chemical oxygen demand (COD) from pulp and paper mill effluent. Three selected tropical native aquatic plants, Scirpus grossus, Azola pinnata and Salvinia molesta were planted in a greenhouse at UKM for screening test. Real final effluent from a pulp and paper mill in Pahang was characterized and contained 181 PtCo for colour and 72.4 mg/L COD at pH 8.1. This wastewater was exposed to weed plant, Scirpus grossus and floating plants, Azola pinnata and Salvinia molesta. The final effluent was analysed after 28 day of exposure. The percentage of colour removal for the three tropical native plants Scirpus grossus, Azola pinnata and Salvinia molesta were 50.28%, 43.09% and 49.72% respectively. While for COD removal, all the three plants successfully removed 100% COD. From the result, the best tropical native aquatic plant to remove colour and COD for pulp and paper mill effluent is Scirpus grossus.

Rawatan metilena biru dalam air sisa menggunakan Scirpus grossus

Phytoremediation is an emerging technology that should be considered for the remediation of contaminated sites because of its aesthetic advantages and long-term applicability. The possibility of Scirpus grossus for degradation of a basic dye, methylene blue (MB) was investigated. The effect of the operational parameter of different dye concentrations (0, 200, 400, 600, 800 and 1000 mg/L) was determined, and the water quality parameters namely pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total organic carbon (TOC) were monitored. The UV-Visible absorption confirmed the degradation of MB within 72 days. The removal efficiency of methylene blue dye from synthetic wastewater was determined to be in the range of 86 – 38% for all treatments at different concentrations (200 – 1000 mg/L) respectively. Furthermore, the highest removals for BOD, COD in 400 mg/L and TOC in 200 mg/L MB were 69, 58 and 63% respectively.

Artificial Aeration for the Enhancement of Total Petroleum Hydrocarbon (TPH) Degradation in Phytoremediation of Diesel-Contaminated Sand

Phytoremediation, one of the green technologies, is an alternative method to remediate contaminated soil. An important factor in the degradation of organic matter in phytoremediation is the availability of oxygen. Plants were known to enhance an aerobic condition especially in roots area. Therefore, to enhance the degradation of TPH in soil, one of the alternatives was to increase the oxygen concentration. Three treatments with different diesel concentrations (50, 1,525 and 3,000 mg/kg) and aeration rate (0, 1 and 2 L/min) were employed. After 72 days, the highest degradation of TPH in sand (73.7 %) was achieved in diesel concentration of 3,000 mg/kg and an aeration rate of 1 L/min. This degradation was higher than TPH degradation in bed with aeration rate of 0 L/min (65.4 %). TPH concentration in plant for all diesel concentration with aeration rate of 1 L/min was higher than aeration rate of 0 and 2 L/min even though S. mucronatus was observed to grow well at the aeration rate of 2 than 1 L/min. The highest TPH concentration in plant was achieved by S. mucronatus that grew on diesel concentration of 50 mg/kg, i.e. 416.6 mg/kg for aeration rate of 1 L/min. At the end of experiment, bacteria population on 50 mg/kg diesel concentration with an aeration rate of 1 L/min was 52 × 103 CFU/mL. These indicated that aeration with a higher rate did not always give a better result than a low rate.