500 5th St NW - KWS 502
Washington, DC 20001
Tel: (202) 334-2800
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|Cycle 2 (2012 Deadline)
Field assessment of arsenic-bearing waste treatment options
PI: Ahammadul Kabir (Asia Arsenic Network)
U.S. Partner: Lutgarde Raskin (University of Michigan)
Project Dates: August 2013 to February 2016
Water quality and supply issues in South Asia, dominated by concerns of arsenic contaminated groundwater and microbially contaminated surface water, are expected to worsen with the effects of climate change. Arsenic removal systems are essential for providing drinking water but generate arsenic-bearing wastes that can re-release arsenic to the environment. This project focuses on arsenic-bearing waste management, an issue preventing greater implementation of arsenic removal systems. By collaborating with researchers at the University of Michigan (UM) and consultants at Carollo Engineers, Dr. Kabir and his group will apply techniques developed through their lab studies to evaluate field-scale arsenic-bearing waste management options. Specifically, they will (1) analyze arsenic wastes from two types of arsenic removal systems, (2) evaluate alternative waste disposal options, and (3) quantify the arsenic-transforming potential of microbial communities in disposal environments.
A Sidko filtering machine in an arsenic iron removal plant (Photo courtesy Dr. Kabir).
| A backwash sludge water sample is collected from the arsenic removal plant (Photo courtesy Dr. Kabir).|
Collection of solid sludge samples nearby the arsenic removal plant (Photo courtesy Dr. Kabir).
The mitigation of arsenic contamination in drinking water in Bangladesh has the potential to improve the lives of millions of people in Bangladesh. Arsenic contamination of drinking water threatens human health and productivity by increasing morbidity and mortality (Argos et al. 2010). To properly address this barrier to development, guidelines for disposal of arsenic-bearing waste from arsenic removal systems must be established. This project will provide region-specific recommendations for arsenic-bearing waste management, enabling improved implementation of arsenic removal systems and enhancing the capacity of the Asia Arsenic Network (AAN) to provide clean drinking water. The results from this study will also inform decisions about how best to manage arsenic solids produced during water treatment to avoid recontamination of nearby soils and surface water with arsenic. AAN’s extensive outreach experience will be used to communicate findings with local arsenic removal plant operators and community members. AAN also works closely with local government officials and will communicate results and recommendations to policymakers. Planned training visits to the University of Michigan will also facilitate AAN’s capacity to conduct research and monitor water quality in Bangladesh, while upgrades to AAN’s lab equipment will enhance the organization’s capacity to test for multiple pollutants in drinking water, including not only arsenic but also microbial contaminants.
Summary of Recent Activities
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The project team made progress on multiple fronts in the first quarter of the year. Pure backwash sludge was collected from each of the eight technologies (five arsenic iron removal plants and three SIDKO plants) and lined pit sludge was collected form four technologies (two arsenic iron removal plants and two SIDKO plants) at regular interval of three weeks. The collected pure liquid backwash sludge and the lined pit sludge were then transported to the AAN laboratory where it was filtered by using a water bath and after filtering, the solid part of the sludge was dried. The dried sludge was subjected to dominant anions and cations testing namely arsenic, iron, manganese, magnesium, calcium, sulphate, bicarbonate, phosphate, silicate. The sludge collected from each of the study technologies was also subjected to TCLP, SPLP and Cal WET analysis for arsenic leaching.
To test one the cow dung arsenic removal method, a fixed amount of cow dung was mixed with pure dried solid sludge samples collected from study technologies at normal environmental condition in the laboratory and kept for a month. The amount of arsenic remained in the semi solid mass after 30 days (for a complete microbiological activity) were determined by AAS. Leaching characteristics from the mixture was also determined through TCLP, SPLP and Cal WET analysis and arsenic leaching tests were done for 21 of such samples. The team also attempted to use bricks to remove arsenic and after the sludge was mixed into bricks, they will be burned in the brick field in mid-April. Five bricks for each composition of the sludge and the mud were prepared.
Md. Shamim Uddin and Abu Shamim Khan at the University of Michigan (Photo courtesy Dr. Kabir).
The month-long training session allowed the chemists to exchange ideas with their U.S. counterparts such as Tara Clancy, left (Photo courtesy Dr. Kabir).
Routine collection of raw water, treated water, lined pit sludge, soil and plant samples continued during this period with ten samples of raw and treated water collected and tested for arsenic, iron, manganese and phosphate; eight liquid sludge samples were collected and tested for arsenic, iron, manganese and phosphate; six pit tank sludge samples were collected and tested for arsenic, manganese, calcium, magnesium, iron, bicarbonate, sulphate, phosphate, silicate, and arsenic leaching test were conducted by TCLP, SPLP and Cal WET analysis; 63 soil samples were collected and tested for arsenic; nice plant samples were collected and tested for arsenic form different sites of study technologies.
In the coming months DNA extracted from soil samples will be submitted for Illumina sequencing of the 16S rRNA genes to characterize the microbial community present at sites surrounding arsenic removal filters. An online tool PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) will be used to predict microbial community functions and compare the potential abundance of arsenic transformation genes based on predictions from complete genomes. Differences in functional potential between sites at the same filter and across filters will also be compared. The team will also continue collecting samples from the project areas for testing and will also continue to make and monitor the arsenic-laced concrete and mud bricks.Project Activity Process