Arsenic Technologies for Drinking & Industrial Water Treatment

Principal Investigator - Graham Gagnon, Professor, Dalhousie University, 2005 - 2007

Challenge

Arsenic is a natural element that can be found in some drinking water and mine waste and high levels of this element can have adverse health effects on humans.  Biological arsenic removal has been successfully used to treat drinking water as it employs inexpensive biodegradable nutrient sources, and the process produces less contaminated sludge than chemical systems. Yet, while some systems are commercially available, there is little information about system capacity controls or the microbial communities used in biotransformation.

Additionally, little information is available about the fate and stability of the sludge that is produced by the treatment systems. Literature studies can provide some insights, but do not holistically advance the understanding of real-world bioreactor systems. Such knowledge is essential to predicting system performance under changing water compositions or for novel applications.

Project

The project aimed to develop two technologies in parallel: a biological remediation system for arsenic-contaminated mine waste, and a chemical treatment system for small drinking water systems. The two exercises were run in parallel to facilitate knowledge transfer and technology exchange by allowing for the analysis of each arsenic treatment in more than one application.

Arsenic treatment technology for small-scale drinking water treatment

• The objective of this component was to develop a treatment system for arsenic removal applicable for drinking water treatment. The research built on previous studies at Dalhousie using water treatment residuals to remove phosphorus from wastewater. A technology evaluation was implemented with Veolia Water, one of the world’s largest water companies, at the pilot scale. Arsenic removal was tested both in batch and column adsorption tests.

Arsenic treatment technology for mine waste treatment

• The objectives of this component were twofold, involving (i) the characterization of arsenic species; and (ii) determination of the systems’ capacity controls. For the first objective, the researchers sought to identify key microbial populations in the community that influenced arsenic transformations. Microbial community compositions were monitored using an established DNA fingerprinting method. For the second objective, it was found that contact time, as well as organic substrate content were key controlling factors.

Outputs

• Development of a small scale chemical treatment system for household and community use.
• Creation of a patent application for the United States, using the research results.
• Patents filed in Canada and any other countries identified.
• Once feasibility was demonstrated, further opportunities for technology transfer to water utilities and metal mining and smelting industries were explored.

Where appropriate, the team published the project results at leading-edge water quality conferences and in relevant journal publications.

Results of the phosphorus research were presented at conferences:

• Presentation at the AWWA Water Quality and Technology Conference, Quebec City, Quebec, November 6th-9th, 2005Gibbons, M.K., Mortula, M., and Gagnon, G.A. 2005. Finding new opportunities for water treatment residuals. Poster.

• Presentation at the ACWWA 58th Annual Conference, Halifax, Nova Scotia, October 16th-18th, 2005. Gibbons, M.K., Mortula, M., and Gagnon, G.A. 2005. Investigating a reuse option for water treatment residuals.

• Poster presentation at The 16th Annual AEHS Meeting & West Coast Conference on Soils, Sediments, and Water, San Diego, California, USA, March 13 – 26, 2006. Haskins, S.D., Koch, I, Reimer, K.J., Easton, L and Serran, M. Removal of Arsenic from Water.

Outcomes

• Provision of a basis for fast transition from research to knowledge translation and ultimately end-product, which the project addressed through the development and commercialization of innovative arsenic treatment technologies. These water technologies will target the treatment of aqueous mine waste entering ecologically sensitive watersheds, and drinking water in small/decentralized communities.
• Transfer to end users (industry, consumer etc), the treatment technologies were transferred to the project partners: the water industry and the mining community.
• A small scale chemical treatment system was developed for household and community use and was implemented with the assistance of the provincial government.
• Knowledge generated from this research has proved useful to regulatory agencies. In particular, it provided insight to the applicability and limitations of removing arsenic from various source water supplies.