Project Lead(s): Nabeel Khan Niazi
Issue
The contamination of groundwater resources with arsenic is an environmental and health issue affecting over 200 million people worldwide, of which about 110 million people have been affected in the Southeast Asia region, including China, India, Bangladesh, Vietnam and Pakistan.
It is crucial to explore a viable and cost-effective method for removing arsenic from contaminated water.
Use of agricultural and food-industry biowastes (hereafter referred to as biosorbents) such as rice husk, sugarcane bagasse, water chestnut shell and peels of various fruits, are showing promise as agents to remove arsenic from water. These biosorbents have advantages over conventional arsenic removal techniques (e.g., reverse osmosis, coagulation/flocculation) due to their low-cost and eco-friendly nature.
Solution
Implemented in Pakistan, the project aimed to evaluate the potential of various agricultural and food-industry biowastes (such as sugarcane bagasse, water chestnut shell and peels of various fruits) as low-cost agents for removing arsenic from contaminated drinking water.
Groundwater samples were collected from various previously unexplored rural areas of Punjab in Pakistan to determine the level of arsenic concentration.
Different agricultural and food-industry biowastes (biosorbents) such as corn cob, sugarcane bagasse, water chestnut shell, watermelon rind, pomegranate peel, java plum seeds and egg shells were then collected to prepare biosorbents for arsenic removal from the water.
Corn cobs were modified to xanthated corn cobs; sulfuric acid was used for activation of orange peel and sugar cane bagasse (referred to as charred orange peel and charred sugarcane bagasse, respectively). In addition, iron(III) chloride solution was used for modification of sugarcane bagasse to prepare iron(III)-coated sugarcane bagasse; and water chestnut shell was modified by coating with akaganéite mineral.
Those with maximum arsenic removal capacity were further selected for modification, in order to enhance their efficiency and stability to treat arsenic-laced groundwater for application in aqueous environments.
Outcome
The results showed that modified biosorbents removed more arsenic from natural contaminated water samples than that of natural biosorbents in groundwater samples, with arsenic levels ranging from 5–201 μg/L.
The influence of competing ions (such as sulfate, nitrate, phosphate, sodium, calcium and magnesium) was also resolved and it was observed that these competing ions did not have a significant effect on arsenic adsorption except phosphate, which reduced the adsorption of arsenic by 15 to 20%.
Xanthation of corn cob enhanced the arsenic adsorption capacity by 1.9 times, while charred sugarcane bagasse and iron-coated sugarcane bagasse showed 2 and 1.5 times higher adsorption capacity, respectively, compared to natural sugarcane bagasse. Akaganéite-coated water chestnut shell showed 2 times more adsorption capacity than natural water chestnut shell.
The project team plans to further evaluate the developed biosorbent technology to determine its usefulness in removing multi-contaminants (e.g., heavy metals and organic contaminants) from groundwater and/or industrial wastewater.
Additionally, they plan to regenerate the biosorbents by applying various desorbing agents to reuse arsenic-contaminated water and recovered arsenic, which potentially can be used in high-technology manufacturing processes.
The researchers wish to apply for Phase II Transition To Scale funding to scale up the project, as they seek support from the Water and Sanitation Agency (WASA), the Faisalabad and Environmental Protection Agency of district Faisalabad, and the Punjab Government in Pakistan to implement this innovative technology.
