Assessing Arsenic Remediation Technologies and Waste Stabilization Methods in Rural India

What is it about?

Arsenic pollution of groundwater is a serious concern in the developing world. Over the last decade, significant progress has been made in arsenic remediation in India, where millions of households are exposed to arsenic poisoning through drinking water drawn from contaminated aquifers. Arsenic-treatment units (ATUs) have been effective in helping regions where piped-water supply of surface water is unachievable due to logistic constraints. However, no policy measure exists on environmental and economic management of the voluminous wastewater produced by ATUs. The waste is highly toxic in terms of its arsenic content and leachability and therefore can readily re-contaminate local environments if suitable stabilisation methods are not implemented. This paper presents an investigation of the recent developments in arsenic-wastewater-management practices of a severely affected state called West Bengal. Commercial fixation of the waste by incorporation into building materials is often seen as a potent method for ultimate encapsulation of arsenic toxicity. By analysing the practical efficacy of such a prospective project, the author has made an attempt to model scenarios involving non-hazardous and financially beneficial arsenic waste management for sustainable arsenic mitigation in the region.

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Photo by VD Photography on Unsplash

Photo by VD Photography on Unsplash

Why is it important?

Geogenic arsenic contamination of aquifers is a major public health crisis in the developing world where rural habitations rely on groundwater for drinking. In India, millions of households have been affected by this situation for over two decades. Remedial measures range from establishment of surface-water-based PWS schemes to installation of ATUs. Stabilisation of arsenic waste generated from the ATUs is also a crucial aspect for the entire process of arsenic remediation. Certain ATUs called ARPs have arrangements within their premises to stabilise the toxic wastewater in situ. However, ARPs require a large area and skilled manpower for installation and operation, which may not be feasible in the long run in a rural setting with sparse population. On the other hand, many small-scale ATUs called ARUs have been widely accepted by rural households due to ease of their use and maintenance. However, the ARUs produce high volumes of hazardous arsenic sludge, which is generally kept stored locally, which ultimately requires effective stabilisation for safe disposal. As setting up of ARPs is not quite feasible in remote habitations due to socio-economic barriers, an arsenic-remediation plan composed of installation of ARUs and subsequent ex situ stabilisation of arsenic wastes with bricks must be done to for ultimate and effective encapsulation of arsenic in the local environment. For profit or non-profit, the practice of selling arsenic wastes to manufacturers of construction materials has been adopted by a few private agencies and NGOs running certain ATUs. However, similar ex situ arsenic stabilisation practices are yet to be adopted by the West Bengal government on a wide scale so as to effectively dispose of the enormous volumes of toxic waste produced by various ARUs annually. With a thriving brick production market in India’s Gangetic plain, it may be beneficial to have a waste-management plan focused on reusing arsenic waste with bricks, taking into account the location, type and quantity of waste that is to be stabilised. Ex situ stabilisation, where most of the waste will be used to make bricks and therefore isolated from the environment, will help in avoiding long-term storage of waste and subsequent disposal elsewhere, which has an associated risk of accidental leaching of arsenic into the environment. Therefore, ex situ stabilisation should help the government in achieving better arsenic mitigation (i.e. groundwater remediation with waste management) in the state. Execution of the proposed groundwater arsenic-remediation and waste-management plan, combined with the implementation of surface-water-treated PWS schemes as planned by the state government, would minimise the net arsenic exposure to the society through drinking water with time, thereby reducing the risk to public health. The objectives of modelling the arsenic-mitigation scenarios as a ‘system’ shall be to (a) assess B/C to the government by arsenic remediation, with in situ or ex situ waste management, and (b) calculate B/C for society. In the case that the model determines the financial benefits for the state government in installing ARUs to be similar to that with regard to ARPs, the policymakers might opt to construct more ARUs for safe drinking water and at the same time address safe disposal of arsenic sludge. Additionally, the energy consumption involved in the entire process of arsenic fixation at the brick-making factory can also be quantified. The enlightening insights presented by dynamic modelling of the scenarios shall assist government bodies in planning an effective and sustainable mitigation project over a wider scale in the region. Unlike decentralised water-supply projects franchised by NGOs and local businesses, the state government (in the study area, West Bengal, India) has no provision for recovery of full O&M cost in any of its water-supply schemes. Hence, water tariffs for households in drawing water from such schemes are subsidised, thereby implying that B/C is less than zero in the groundwater-remediation aspect. However, by recognising the tangible earnings and intangible savings of ex situ and in situ stabilisation, respectively, of voluminous arsenic sludge generated by ATUs, a hefty and stable growth in fiscal benefits of arsenic mitigation (i.e. groundwater remediation and waste management, together) can be contemplated. This justifies the rationale in computation of fiscal benefits in arsenic mitigation. Certain NGOs reinvest some of the water tariff revenues in other rural development projects. Likewise, fiscal benefits obtained by executing the most sustainable ATU-based mitigation strategy can be administered into construction of civil infrastructure in remote villages for modernisation and economic empowerment, to increase society’s standard of living and willingness to pay for using the SWSSs (which include PWS and ATUs) and thus enhance the sustainable development, particularly in a post-COVID-19 world. In many ways, this paper is a first of its kind in the literature. It presents a key research concept based on a rigorous scientific investigation of two scenarios. Through a case study in India, this investigation aims to provide a methodological framework that would equip policymakers with a strategic decision-making tool to come up with an economical and sustainable environmental management plan in the context of arsenic mitigation. The scenarios explained in the paper have never been defined anywhere in policy discussions before, in which case presenting a detailed theoretical review of the scenarios has been vital.

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