Green Materials for Sustainable Water Remediation and Treatment
By Anuradha Mishra, James Clark
The Royal Society of Chemistry Copyright © 2013 The Royal Society of Chemistry
All rights reserved.
Greening the Blue: How the World is Addressing the Challenge of Green Remediation of Water
ANURADHA MISHRA AND JAMES CLARK
The waters of the oceans, rivers and lakes have always been of vital importance for humanity. They are the very basis of life on the planet Earth and have enticed poets and artists. The availability of clean water is an essential requirement for humans and all other creatures. Good quality water is needed for direct consumption and for many types of industries.
There is a serious water quality crisis across the world and many factors are responsible for a continuous deterioration of water quality. These include rapid population growth, widespread urbanization, massive industrialization, and expanding and intensifying food production. Worldwide, the need for drinkable water is increasing while the supply is decreasing. In certain places, water is very scarce, but in many other areas there is plenty of water that is not drinkable. The situation tends to increase the unregulated or illegal discharge of contaminated water within and beyond national boundaries. This presents a global threat to human health and well-being, with both immediate and long-term consequences and a detrimental effect on poverty alleviation. Water supply and sanitation are key factors determining human well-being. The Millennium Development Goals' report shows that, worldwide, 1.1 billion people lack access to safe drinking water, 2.6 billion people lack adequate sanitation, and 1.8 million people die every year from diarrheal diseases, 90% of which are children under the age of five.
Water remediation can be described as the process to render water free from any contamination. Water remediation is applicable for groundwater, which is the predominant source of water used in cities as well as for farming, for wastewater from industries, which needs to be remediated to prevent contaminants entering the environment, and for several other types. Water remediation is important for several reasons. Firstly, water that is considered unsafe for human consumption must always be completely cleansed to meet well-established health criteria. Furthermore, water remediation is also important to keep the environment free from contamination. Impurities in wastewater can potentially damage the local topography and negatively affect agriculture and all types of farming. It can also adversely impact plant and animal life.
Water recycling is the reuse of treated wastewater for beneficial purposes, such as agricultural and landscape irrigation, industrial processes, toilet flushing, and replenishing the groundwater basin that is often referred to as groundwater recharge. Sometimes water is recycled and reused on site as, for example, when an industrial facility recycles wastewater for cooling processes. A common example of recycled water is water that has been reclaimed from municipal wastewater, or sewage. The term "water recycling" is often used synonymously with water reclamation and water reuse. If adequately treated to ensure water quality appropriate for the end use, recycled water can meet most but not all water demands. Recycled water is most commonly used for non-potable (not for drinking) purposes. Common uses of recycled water include agriculture, landscapes, public parks, and golf course irrigation. Other non-potable applications include cooling water for power plants and oil refineries, industrial process water for such establishments like paper mills and carpet dyers, toilet flushing, dust control, construction activities, concrete mixing, and artificial lakes. Figure 1.1 shows types of treatment processes and suggested uses at each level of treatment. In uses where there is a greater chance of human exposure to water, more treatment is required.
In order to live and reproduce, plants, wildlife, and fish depend on sufficient water flows to their habitats. Lack of adequate flow can result from diversion of water for agricultural, urban, and industrial purposes. Such diversions can cause deterioration of water quality and ecosystem health. Use of recycled water can significantly reduce diversion of freshwater from sensitive eco- systems. Human non-drinking water requirements can be supplemented by using recycled water, which can free considerable amounts of water for the environment and increase flows to vital ecosystems. In recent years, many changes have been made in the processes of wastewater management. These changes are made because of tighter governmental regulations, on the one hand, and the fact that wastewater infrastructure needs major repairs, on the other. This has led to a new trend in wastewater management systems. Instead of considering wastewater as waste, it is now being increasingly considered as a carrier for raw materials for definite end uses.
Common water remediation techniques include phytoremediation, bio-augmentation, ozone and oxygen gas injection, and chemical precipitation. In most water remediation centers across the world, a combination of various methods is used. As such, no single water remediation method can completely rid the water of all contaminants and impurities.
1.2 Green Remediation (Greening the Blue)
Sustainability initiatives have addressed both the broader scope of applications as well as the selected elements of green remediation. The concept of sustainability has been derived from the realization that the Earth's natural resources are limited, and that human activity is depleting these resources at an alarming rate. This activity in turn has a significant impact on the environment. The concept of sustainability first found shape in the form of sustainable development. Sustainable development was defined in 1987 in the Brundtland Commission's report to the United Nations as "development that meets the needs of the present without the ability of future generations to meet their own needs". Issues such as climate change and resource conservation have brought increasing focus on protection of the environment. As a result, sustainability has evolved to become a holistic approach to environmental management. Sustainable practices are such practices that consider the preservation and augmentation of economic and natural resources, ecology, human health and safety, and quality of life.
With advancing cleanup technologies and evolving incentives, green remediation, green materials, or technologies for making clean water offer significant potential for increasing the net benefit of cleanup (Figure 1.2).
Such strategies would tend to reduce project costs and expand the scope of long-term property use or reuse, without compromising the cleanup goals. Green remediation reduces the deleterious after-effects on the environment during cleanup processes, otherwise known as the "footprint" of remediation. It also avoids the potential for any collateral environmental damage. Green remediation promotes application of sustainable strategies at every site requiring environmental cleanup, whether conducted under federal, state, or local cleanup programs or by private parties. Green remediation requires close coordination between cleanup processes and reuse planning. Reuse goals influence the choice of remedial processes, cleanup standards, and the cleanup schedule. In turn, those decisions affect the approaches for investigating a site as well as selecting and designing a custom-made remedial process. They also affect planning future operations and establishment of in-house remedial processes to ensure environmental protection.
The green solutions for water and wastewater remediation include bioremedial processes and chemical processes. Bioremedial processes are done either through plants (phytoremediation) or through microbes such as bacteria, algae, fungi, and yeast. Phytoremediation encompasses phytoextraction, phy- tostabilization, phytovolatilization, and rhizofiltration. The chemical solutions include chemical precipitation, ion exchange, liquid–liquid extraction, electrodialysis, and solid-phase extraction using natural materials or biodegradable synthetic materials.
1.3 Policy Directives for Water Remediation and Reuse
Different countries have specific policies for water remediation, and there are regulatory bodies to supervise and control water treatment plants. Additionally, global standards are maintained by international environment protection agencies and water regulatory bodies in accordance to which water remediation is carried out. The process of water remediation was initially emphasized only for potable water. Over the years, however, wastewater treatment has also become equally important due to environmental concerns.
The US Environmental Protection Agency (EPA) regulates many aspects of wastewater treatment and drinking water quality. Most states in US have established definite criteria and guidelines for the beneficial use of recycled water. In the year 1992, the EPA developed a technical document entitled "Guidelines for Water Reuse", which contains all the necessary information as a summary of state requirements and guidelines for the treatment and uses of recycled water. State and federal regulations have been successful in providing a framework to ensure the safety of the many water recycling projects in the US. There is a wide range of EPA programs that tend to ensure sustainability of the cleanup processes along the categories of the built environment, water ecosystems and agriculture, energy and environment, and materials and toxics. There are many programs, tools, and incentives available to help governments, business houses, communities, and individuals to serve as good environmental stewards, make sustainable choices, and effectively manage resources.
In its mission to protect human health and the environment, the EPA is dedicated to developing and promoting innovative cleanup strategies that can restore contaminated sites to productive use, along with a reduction of costs and promotion of environmental quality. The EPA strives for implementation of cleanup programs that tend to use natural resources and energy efficiently, reduce negative impacts on the environment, minimize or eliminate pollution at its source, and reduce waste to the greatest extent possible in accordance with the agency's strategic plan for compliance and environmental stewardship. The practice of "green remediation" uses these strategies to positively impact all environmental effects of the remedial processes for contaminated sites, and also incorporates options to maximize the net environmental benefit of cleanup actions. Strategies for green remediation also incorporate sustainability. This essentially means that while, on the one hand, environmental protection does not preclude economic development, on the other, economic development is ecologically viable today and in the long run.
The UN envisioned and formulated the "Millennium Development Goals" (MDG), dedicated to reduce poverty and ensure sustainable development. Goal number 7 of target 10 of the MDG states: "Halve, by 2015, the proportion of people without sustainable access to safe water and basic sanitation". The mandate of the UN-Water Decade Programme on Capacity (UNW-DPC) is to strengthen the activities of UN-Water members and partners (more than two dozen UN organizations and programmes) and support them in their efforts to achieve the Millennium Goals related to water. UNW-DPC is directly working with members and partners towards improved human well-being through enhanced water and sanitation that is a core element of the green economy.
1.4 Eco-Labels and Standards
Eco-labels are often affixed to products by manufacturers to indicate to customers that the products meet certain environmental standards. These standards may be developed by private entities, by governmental or public agencies, or jointly by stakeholders and experts from the public and private sectors. As part of its mission, the EPA is working with a variety of non-governmental standards developers to promote the development of voluntary consensus towards standards for environmentally preferable goods and services. The National Technology Transfer and Advancement Act (NTTAA) and OMB Circular A-119 direct the US federal government to use and participate in the development of reference standards compatible with best environmental goals. The consensus standards should meet government needs.
The number of standards for green products has increased in recent years due to a growth in market demand for "green" products. The Federal Trade Commission (FTC) has created its Green Guides to help ensure that marketing claims regarding the environmental friendliness of products and production processes are truthful and documentarily substantiated. These guidelines largely address the issues of when and how very specific and narrow environmental attributes can be claimed, and not how to construct a broad- based environmental standard or eco-labeling program. A green label demonstrates a product's sound environmental performance and the supplier's commitment to protect the environment. The society has become so environmentally conscious that now green labeling improves the corporate image, brand reputation, and recognition of high product quality. Many countries use the international standard ISO (International Organization for Standardization) 14021 on self-declared environmental claims as a basis to inform the aware consumers. The green label should include within it standards on water use and recycling.
The EU Ecolabel system helps one to identify products and services that have a desirable environmental impact throughout their life cycle, right from the extraction of raw material through to production, use, and final disposal and would be expected to include aspects of water management. Recognized throughout Europe, the EU Ecolabel is a highly trustworthy label, promoting environmental excellence. The EU Ecolabel scheme is indeed a safeguard for environmental sustainability. The criteria have been developed and agreed upon by scientists, NGOs, and stakeholders to create a credible and reliable way to make environmentally responsible choices.
From the raw materials to manufacturing, packaging, distribution, and disposal, EU Ecolabel products are evaluated by independent experts to ensure they meet the predefined criteria that ensure their desired environmental impact. The EU Ecolabel is an easy way to make an informed choice about the products that one may be buying. Although the scheme is voluntary, hundreds of companies across Europe have joined up because of EU Ecolabel's competitive edge and firm commitment to the environment. Customers can rely on the logo as every product is checked by independent experts.
Defra's (UK) guidelines have also drawn from ISO 14021 and in this re spect tend to align with international practices. For clarity and ease of reference, the Defra guidelines refer to the relevant provisions of ISO 14021. In the year 2003, Defra published sector-specific guidelines where research showed that further guidance may be useful.
1.4.1 Globalization of Green Labels
Eco-labeling schemes have been widely used worldwide since the late 1970s. As of today, there are close to 30 different green label schemes worldwide. Most of them are run on a voluntary basis. They all provide opportunities to include the provision of clean water and to encourage water recycling.
Germany's "Blue Angel" eco-label, the first national scheme in the world, was introduced in 1977.
In Asia, countries such as China, Japan, Korea, India, Thailand, Malaysia, and Singapore have already established their own eco-labeling schemes. The Green Council (GC) of Hong Kong started the Hong Kong Green Label Scheme (HKGLS) in December 2000. The scheme sets environmental standards and awards a "green label" to products that match the criteria regarding their environment performance. In establishing the standards, HKGLS takes inputs from relevant international standards. It is benchmarked with well-developed eco-labels to ensure credibility of the standards. As with the majority of eco-labeling programs, HKGLS is an ISO 14024 compliant Type 1 label, which involves a third-party certification requiring considerations of lifecycle impacts. Some of the key criteria contained in these standards also require compliance with applicable legislation. (Continues...)
Excerpted from Green Materials for Sustainable Water Remediation and Treatment by Anuradha Mishra, James Clark. Copyright © 2013 The Royal Society of Chemistry. Excerpted by permission of The Royal Society of Chemistry.
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