LCA of Disposal Practices for Arsenic-Bearing Iron Oxides Reveals the Need for Advanced Arsenic Recovery.

Iron (Fe)-based groundwater treatment removes carcinogenic arsenic (As) effectively but generates toxic As-rich Fe oxide water treatment residuals (As WTRs) that must be managed appropriately to prevent environmental contamination. In this study, we apply life cycle assessment (LCA) to compare the toxicity impacts of four common As WTR disposal strategies that have different infrastructure requirements and waste control: (i) landfilling, (ii) brick stabilization, (iii) mixture with organic waste, and (iv) open disposal. The As disposal toxicity impacts (functional unit = 1.0 kg As) are compared and benchmarked against impacts of current methods to produce marketable As compounds via As mining and concentrate processing. Landfilling had the lowest non-carcinogen toxicity (2.0 × 10-3 CTUh), carcinogen toxicity (3.8 × 10-5 CTUh), and ecotoxicity (4.6 × 103 CTUe) impacts of the four disposal strategies, with the largest toxicity source being As emission via sewer discharge of treated landfill leachate. Although landfilling had the lowest toxicity impacts, the stored toxicity of this strategy was substantial (ratio of stored toxicity/emitted As = 13), suggesting that landfill disposal simply converts direct As emissions to an impending As toxicity problem for future generations. The remaining disposal strategies, which are frequently practiced in low-income rural As-affected areas, performed poorly. These strategies yielded ∼3-10 times greater human toxicity and ecotoxicity impacts than landfilling. The significant drawbacks of each disposal strategy indicated by the LCA highlight the urgent need for new methods to recover As from WTRs and convert it into valuable As compounds. Such advanced As recovery technologies, which have not been documented previously, would decrease the stored As toxicity and As emissions from both WTR disposal and from mining As ore.

A methodology for the sustainability assessment of arsenic mitigation technology for drinking water.

In this paper we show how the process analysis method (PAM) can be applied to assess the sustainability of options to mitigate arsenic in drinking water in rural India. Stakeholder perspectives, gathered from a fieldwork survey of 933 households in West Bengal in 2012 played a significant role in this assessment. This research found that the 'most important' issues as specified by the technology users are cost, trust, distance from their home to the clean water source (an indicator of convenience), and understanding the health effects of arsenic. We show that utilisation of a technology is related to levels of trust and confidence in a community, making use of a composite trust-confidence indicator. Measures to improve trust between community and organisers of mitigation projects, and to raise confidence in technology and also in fair costing, would help to promote successful deployment of appropriate technology. Attitudes to cost revealed in the surveys are related to the low value placed on arsenic-free water, as also found by other investigators, consistent with a lack of public awareness about the arsenic problem. It is suggested that increased awareness might change attitudes to arsenic-rich waste and its disposal protocols. This waste is often currently discarded in an uncontrolled manner in the local environment, giving rise to the possibility of point-source recontamination.