Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 3, Pages: 1089-1092  
J. Environ. Treat. Tech.  
ISSN: 2309-1185  
Journal web link: http://www.jett.dormaj.com  
Optimisation of Heavy Metals Uptake from Leachate  
Using Red Seaweed Gracilaria changii  
1
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Nithiya Arumugam , Shreeshivadasan Chelliapan , Sathiabama T. Thirugnana and Aida  
Batrisyia Jasni2  
1
Department of Engineering, Razak Faculty of Technology and Informatics, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100 Kuala Lumpur,  
Malaysia  
2
School of Civil Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, Johor Bahru, Malaysia  
Received: 28/03/2020  
Accepted: 07/07/2020  
Published: 20/09/2020  
Abstract  
Heavy metal is one of the pollutants in landfill leachate besides organic and inorganic pollutants. The presence of heavy metal is alarming  
due to its harmful nature; makes it incompatible to be discharged into water bodies before treatments. There are many treatment techniques  
to remove heavy metals from wastewater, where some of them even involve the coupling of one or more techniques to facilitate and improve  
the removal efficiency. However, the adsorption using seaweed is one of the known techniques to eliminate heavy metals from wastewater  
efficiently. Therefore, this study introduced a new adsorbent for heavy metal adsorption: red seaweed Gracilari changii. The effect of  
operational parameters such as leachate pH (2-7), seaweed dosage (2-10 g), rpm (10-100), and contact time (10-60 min) on the optimum  
adsorption of Gracilaria changii was studied. At optimum pH (pH=5), seaweed dosage (10g), rpm (rpm=50) and contact time (30min),  
2
+
6+  
2+  
Gracilaria changii showed maximum metal ion removal of 45%, 35%, and 30% for Fe , Cr and Ni respectively. The adsorption was  
rapid and reached equilibrium after t=30min in general. This optimisation result can be used as a reference to study the effect of different  
dosages of the adsorbent towards the removal rate.  
Keywords: Seaweed, Adsorption, Leachate, Heavy metals, Adsorbent  
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adopted for the treatment of leachate: biological, physical,  
1
Introduction  
chemical, and physico-chemical techniques. Nevertheless, the  
preference of a technique or coupling of techniques is solely based  
on the characteristics of leachate (13). Lately, the removal of  
heavy metals by adsorption method using various types of  
adsorbents received great interests, with seaweed being one of  
them. Seaweeds are macroalges and consists of 10,000 naturally  
existing species. These seaweeds can vary in size and typically  
grow up to 30 meters in length. Although seaweed has plant-like  
physical structure and components, they are not genuine vascular  
plants, but are referred as marine algae. Marine algae belongs to  
the Kingdom Protista group, which by default are neither plants  
nor animals.  
Leachate is the dark form of liquid generated via percolation  
of rainwater through dumping of solid wastes into landfills.  
Rainwater undergoes biochemical processes with wastes and also  
with the water contents of the waste itself (1). Random studies  
3
showed that 0.2m of leachate are generated from every one  
metric ton of municipal solid waste (2). The qualities and  
quantities of leachate vary from one site to another depending on  
factors: moisture content, landfill age, climate, site hydrology,  
and the degree of waste stabilisation (3).  
Leachates are a mixture of colour components, heavy metals,  
ammoniacal nitrogen, organic compounds, and inorganic  
compounds (4,5). Among these, heavy metals are the most toxic  
compounds and draw great attention due to their negative impact  
towards both living organisms and the environment as a whole  
There are three different groups of seaweeds and they are  
identified based on the colour of their thallus namely brown,  
green, and red algae. A number of studies show that different  
types of seaweeds have been used for the adsorption of heavy  
metals from wastewater. There are also vast studies on utilising  
red seaweeds as an adsorbent for removal of heavy metals.  
However, to date, there are no reported studies on Gracilaria  
changii specifically as an adsorbent for the purpose of wastewater  
treatment. Therefore, this study focused on determining the  
(
6). The presence of heavy metals in leachate are sourced from  
used batteries, electronic wastes, paint, construction materials,  
mines, fertilisers, and others (7,8) . The most commonly found  
heavy metals in leachate are Iron (Fe), Chromium (Cr), Arsenic  
As), Nickel (Ni), Lead (Pb), Copper (Cu), Cadmium (Cd), and  
Mercury (Hg); are threats to living organisms even in small  
amounts (9–12).  
(
2
+,  
6+  
2+  
optimal conditions for the removal of Fe Cr and Ni from  
In practice, different modes of treatment methods have been  
leachate using the biomass of Gracilaria changii.  
Corresponding author: Nithiya Arumugam, Department of Engineering, Razak Faculty of Technology and Informatics, Universiti  
Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100 Kuala Lumpur, Malaysia. Email: nithiya85.a@gmail.com.  
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Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 3, Pages: 1089-1092  
initial metal ion concentration of 20mg/L. It was visible that the  
removal percentage of all metal ions by Gracilaria changii  
increased with the increment of pH from 2-5 and was  
subsequently reduced as the pH increased further. This could be  
explained based on the functional groups of seaweed and the  
speciation of metal ions at varying pH levels. The cell wall of  
seaweed is made of polysaccharides, carboxyl, and sulphonate  
groups. These functional groups are negatively charged and at  
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Materials and Methods  
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.1 Leachate  
The leachate sample collection was done at Worldwide  
Landfill Sdn. Bhd., Jeram, Selangor. The raw leachate sample  
was collected and immediately transferred to laboratory in a  
sealed high-density polyethylene (HDPE) container and stored at  
4
⁰C to reduce chemical and biological reactions (14).  
+
lower pH,, these groups are protonated with H . Therefore,  
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.2 Metal Solution  
seaweed is unable to hold the positively charged metal ions. At  
The stock solutions of Fe (II), Cr(VI) and Ni (II) were prepared  
+
increased pH level of upto 5, the concentration of H were  
4 2  
from Iron (II) sulphate heptahydrate (FeSO .7H O), Potassium  
dichromate (K Cr ) and Nickel (II) nitrate hexahydrate  
Ni(NO .6H O) being dissolved in distilled water. During the  
course of the experiment, the preferred constant concentration of  
0mg/L for each metal ion solution was achieved by diluting the  
relatively lower and therefore, the metal ions were able to bind  
with the negatively charged surface of the seaweed (15). The  
removal percentage started to reduce at pH>5 and the metal  
precipitation (formation of metal hydroxide complexes) could be  
the reason behind this occurence (27). Therefore, the optimum pH  
for heavy metals adsorption using Gracilari Changii in this study  
was 5. A maximum of 10%, 5% and 5% of metal ions were  
2
2 7  
O
(
3
)
2
2
2
stock solution further with distilled water (15). The pH of the  
solutions was altered to the required level using 0.1 M NaOH and  
0
2 4  
.1 M H SO .  
2
+
6+  
2+  
removed for Fe , Cr , and Ni , respectively.  
2
.3 Preparation of Adsorbent  
The red seaweed was collected from a cultivation pond in  
Kedah. The harvested seaweed was transferred to the laboratory  
in a container filled with seawater. The red seaweed was cleaned  
and dried. The seaweed was firstly washed with sea water,  
followed with tap water and lastly with distilled water to eliminate  
epiphytes, debris, sand and salts (16,17). The cleaned seaweed  
was subsequently oven-dried at 40⁰C (18) for 24 hr in order to  
preserve the phytochemical content of seaweed. The red seaweed  
was not chopped into smaller sizes prior to oven-drying to prevent  
significant loss of bioactive compounds (19). The dried seaweed  
was crushed using a laboratory blender and sieved using a sieve  
shaker to obtain sample sizes ranging from 150 to 300 µm (20–  
2
2).  
Figure 1: Effect of pH on removal percentage of metal ions  
2
.4 Optimization Study  
Batch adsorption experiments were conducted at room  
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.2 Effect of seaweed dosage  
temperature using a jar test apparatus comprised of six rotor  
paddles connected to a speed controller to adjust the rotational  
speed of the rotor paddles. Glass beakers of 1 litre volume was  
filled with 100ml leachate and desired amounts of seaweed was  
added. The solution was stirred for different contact time. After  
the reaction, the solution was allowed to settle and collected for  
heavy metals analysis (23). The supernatant was filtered using a  
glass microfibre filter to detach the solid and liquid phases. The  
precipitant was analysed for residual heavy metals concentration  
in the leachate (24) using atomic absorption spectrometry (25).  
The similar method was used throughout the experiment to  
investigate the effect of different parameters: pH level, seaweed  
dosage, rpm, and contact time on the adsorption rate.  
Seaweed dosage is one of the fundamental parameters in  
determining the optimum uptake of heavy metals. Therefore, the  
effect of seaweed dosage was studied by varying composition.  
Figure 2 shows that metal ion removal is proportional to the  
increasing seaweed dosage. As the mass increased from 2g to 10g,  
the removal percentage increased as well (28–30). As per the  
studied dosage range, 10g of seaweed is the optimum composition  
for maximum metal ion uptake for all three metals (31). Higher  
dosage offers higher surface area or greater active sites for  
binding of a constant metal ion concentration. Therefore, more  
metal ions bind on the surface of the seaweed and increased the  
removal rate (32). A maximum of 60%, 25% and 20% of metal  
2
+
6+  
2+  
ions were removed for Fe , Cr , and Ni , respectively.  
3
Results and Discussions  
3
.3 Effect of agitational speed  
Figure 3 illustrates the effect of agitation speed of the rotor  
3
.1 Effect of pH  
One of the major parameters in deciding the maximum  
towards the heavy metals uptake by Gracilari Changii. The effect  
was studied within the range of 10-100 rpm. The results showed  
that the maximum removal of heavy metal ions occurred at 50  
rpm. At lower agitation speed, the seaweed aggregated and did  
not spread within the liquid. Therefore, the active binding sites of  
the bottom layer were covered and not available for metal  
binding, while only the upper layer of the adsorbent was able to  
adsorb the metal ions. Thus, sufficient agitation speed is  
adsorption ability of an adsorbent is the pH of a leachate. It  
influences the solubility of metals, the surface charge of the  
adsorbent and the ionisation of the functional groups on the cell  
walls. Hence, the effect of the pH value of the leachate varied over  
a range of 2-7 on the removal of metal ions was conducted and  
the results are as shown in Figure 1 (26). The sample was  
collected at t=10min, with seaweed dosage of 2g and showed an  
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