The high concentration of arsenic in the rural communities' well water has been detected and is of concern in Newfoundland and Labrador. Due to high health risk from arsenic in the drinking water, an effective and inexpensive treatment technique for its removal is highly desired. Commercialized activated carbon products, used for contaminant removal from water, are usually costly due to the high cost of raw materials. The main objective of this study was to develop a metal-impregnated activated carbon filter technology by extracting carbon from Corner Brook Pulp and Paper Mill (CBPPL) ash. This type of carbon is cheaply available and such filters will be easy to install and operate. The activated carbon generated from CBPPL has been previously studied and has potential to be used as an affordable adsorbent. Converting the CBPPL fly ash into valuable activated carbon product will not only provide affordable adsorbents to rural communities but it will also save money in the CBPP waste management.
In this study, the processed carbon from the ash was found very effective not only in removing arsenic from the -contaminated well waters of Wabana, Bell Island - which have arsenic contamination higher than the maximum acceptable limit- but also other elements and components found in this groundwater. After the cleaning process of CBPP fly ash, two different methods were applied for activation: activation with the pure carbon dioxide (CO2) and, the mixture of steam and CO2. Both activations significantly increased the surface area and pore volume of the carbon samples, however, the highest surface area and pore volume achieved was through the activation with the mixture of CO2 and steam (CSAC). The resulting surface area and pore volume obtained with this treatment are much higher than the surface area and pore volume of the cleaned and non -activated CBPP fly ash.
Iron impregnation is recommended for increasing the arsenic removal from water. In this study, the lowest iron concentrations for impregnation on CSAC proved more effective for arsenic adsorption than high iron concentrations. It was found that with lower concentrations of iron, surface area does not decrease significantly and no pore blockage happens. The impregnated CSAC carbon samples are able to remove the arsenic (V) and arsenic (III) from synthesized water up to 99.63% and 86.64%, respectively. The iron distribution is also found as an important parameter during the impregnation of activated carbon for arsenic removal, since accumulation of iron ions in one spot decreases the surface area and cause pore blockage.
The following recommendations were made following this study:
1. Multi component adsorption is an important issues that should be studied thoroughly, as the existence of some other elements and components affect the arsenic removal efficiency.
2. Desorption of the adsorbed elements (especially arsenic) from the activated carbon should be also investigated to find out whether the adsorbent could be reused for treatment, and to determine its cost-effectiveness.
3. The economic aspects of this experiment should be examined.
The full report can be found here.