What is it about?
Arsenic is a toxic carcinogen found mainly in subsurface environments. Geological and hydrological processes are generally responsible for its release into groundwater. Human health is seriously affected by the consumption of such contaminated water. This environmental phenomenon has greatly impacted the rural areas of developing countries in South Asia, particluarly India. Several remedial measures have been undertaken by the Indian authorities to provide safe drinking water to rural habitations. Such measures include tapping surface water sources (e.g., rivers, ponds, etc.) for piped water supply schemes and establishing groundwater treatment facilities. The purpose of this article is to present a review of the scientific literature that details the current critical situation in India's fourth most populous state, West Bengal, and the engineering advances that have been made to mitigate this crisis. Policy discussions often fail to consider the issue of how to safely dispose of or stabilize arsenic wastewaters generated from treatment units. In conclusion, this article proposes innovative solutions that are necessary to achieve sustainable arsenic mitigation in the region that combine both groundwater remediation and waste management methods.
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Why is it important?
Many developing countries, like India, are experiencing challenges in practicing sustainable environmental management plans, including insufficient technology and infrastructure establishments to implement the methods, and skepticism about the long-term viability of the schemes for scientific reliability and social acceptance. Naturally occurring arsenic contamination of groundwater in economically poor and rural territories of these nations is a serious public health concern, that exposes thousands or millions of people to arsenic poisoning through drinking water extracted from the contaminated aquifers. An attempt is made in this Review Article to put together all the significant literature on the arsenic disaster in India and the remedial measures undertaken for mitigation. The best solution to save the masses is to have arsenic-free surface water provided on a large scale. But geographic and economic obstacles prevent these types of schemes from helping many remote rural habitations, which are often the most severely affected by this environmental crisis. In order to provide immediate relief to rural masses in remote areas, extraction of groundwater for treatment and drinking water supply has become vital through the use of appropriate Arsenic Treatment Units (ATUs). When it comes to the extent of relief provided and the number of households remedied, ATUs are often classified as ARPs (i.e., Arsenic Removal Plants) and ARUs (i.e., Arsenic Removal Units). In spite of the successful reduction of arsenic levels in the water by ATUs, the wastewater generated from backwashing the ATUs harbors a high concentration of arsenic. In connection with the careless dumping of such a hazardous waste, a serious environmental threat is created, as arsenic is easily leached into surface and subsurface environments. As a result, all of the efforts made by the ATUs, in terms of reducing the net arsenic toxicity in the environment by removing arsenic from groundwater, go in vain. Therefore, the stabilization of the wastewater is vital to encapsulate the arsenic. According to this Review Article's conclusion, the incorporation of waste into building materials, especially clay-bricks, seems to be a promising option for ensuring sustainable wastewater management in arsenic mitigation projects in India.
Perspectives
Presented in an attempt to address and review the widely known arsenic calamity of India, this paper proposes a system for arsenic mitigation that is both environmentally safe and financially sustainable, taking into account groundwater remediation as well as waste management simultaneously. The first half of the paper presents a meticulous analysis of scientific developments concerning this topic, based on the information documented in the literature and a field investigation conducted by the author. A discussion of 'in-situ' and 'ex-situ' strategies for the disposal of arsenic waste is presented in the second half of the paper. A significant component of the in-situ management is the recycling of arsenic-bearing wastewater through iron-rich sand filters that are situated adjacent to groundwater treatment plants, followed by adsorption and sequestration of residual arsenic. In contrast, the ex-situ aspect has been conceptualized as a hazard-free way to stabilize the toxic sludge with clay bricks, off-site, in a brick-making factory. In summary, this article seeks to summarize the significant studies on the arsenic disaster in India and the related developments in groundwater treatment and wastewater disposal methods. The purpose of this article is to present a review on the assessment and management of environmental risks associated with groundwater treatment and wastewater management systems based on green technologies, rather than focusing on the already known chemical or toxicological aspects of the topic. Most of the essential information is provided pictorially, in a concise manner, via diagrams and photographs. Being the first comprehensive Review Article in recent times, that discusses the arsenic situation in India's state of West Bengal, the paper proposes solutions to achieve effective arsenic mitigation in the region. The aim of this paper is to lay the foundation for a sustainable future by integrating the theories and applications of resource recovery and concentrate management strategies in the clean production science.
Soumyajit Koley
Indian Institute of Technology Kanpur
Read the Original
This page is a summary of: Future perspectives and mitigation strategies towards groundwater arsenic contamination in West Bengal, India, Environmental Quality Management, July 2021, Wiley,
DOI: 10.1002/tqem.21784.
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Resources
Contemporary practices in groundwater arsenic remediation and wastewater management in West Bengal, India: a systematic review
Arsenic is a notorious carcinogen that is released into subsurface waters by virtue of natural geological and hydrological processes. Such a contaminated water has detrimental effects on human health when it is consumed for drinking. This paper is an effort to address the widely recognized public health crisis of arsenic poisoning in India’s state of West Bengal. It is intended to provide an environmentally safe and financially feasible solution for arsenic mitigation that combines both ground water remediation and waste management situations. Treatment of pumped groundwater by Arsenic Treatment Units (ATUs) for providing potable water has been a major arsenic remediation measure in rural villages of West Bengal. But, backwash cleaning of these units generates hazardous sludge rich in toxic arsenic, disposal of which is an environmental concern. Through a field examination, detailed information on the prevalent sludge management practices at remote ATU sites were acquired and reviewed for their suitability. It was ascertained that wrongful dumping of sludge can be avoided by disposal on certain iron–rich sand filters, constructed in–situ using naturally available ingredients. Also, the incorporation of sludge in building materials, especially the clay–bricks, can be an emphatic option for arsenic waste management at commercial scales. This paper thus presents a comprehensive overview of ‘in–situ’ and ‘ex–situ’ strategies of arsenic mitigation. An ‘in-situ’ management aspect utilizes iron–rich sand filters located within the premises of groundwater treatment units for recycling of arsenic-containing wastewater, followed by adsorption and concealment of residual arsenic. An alternative, hazard–free means of stabilizing toxic sludge off–site, with clay–bricks, at a brick manufacturing factory, has been proposed for the 'ex–situ' aspect. Many policy discussions around the globe do not feature arsenic–sludge disposal or stabilization as a topic. Keeping this is viewed, this review article concludes with innovative approaches to sustainable arsenic remediation and waste management in India.
Sustainability appraisal of arsenic mitigation policy innovations in West Bengal, India
Treatment of arsenic-contaminated shallow groundwater upon extraction has become imperative to provide safe drinking water in remote villages in West Bengal, India. Arsenic removal plants (ARPs) stabilising arsenic-rich waste water ‘in situ’, despite saving valuable time and money, require high technical expertise for operation and maintenance, which is difficult to facilitate in rural communities lacking the necessary infrastructural support. Contrarily, arsenic removal units (ARUs) have been widely accepted by the society for their user-friendliness. However, most of them produce a high volume of hazardous sludge, safe commercial reuse of which can be done by ‘ex situ’ stabilisation with clay bricks. Based on the number of ARPs and ARUs needed to help households seeking remedy, a cost–benefit analysis of the remediation and waste-management aspects is performed by system dynamics modelling. For a major arsenic-affected district of the state, the simulation results suggest that in lieu of ARPs, installation of ARUs is deemed to be financially sustainable for at least 15 years from now, if the arsenic-laden bricks are sold at a price 20% higher than normal. Future projections of groundwater draft and stress in the region commensurately confirm the economic and environmental sustainability of the arsenic remediation.
Arsenic calamity in India’s West Bengal: a critical review of mitigation scenarios
Arsenic catastrophe 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 via 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. But no policy measure exists on environmental and economic management of the voluminous wastewater produced by the 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 article 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 via incorporation into building materials is often seen as a potent method for ultimate encapsulation of arsenic toxicity. By analyzing 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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