The Potential for Industrial Wastewater Reuse
Water is a precious commodity that was once available almost free of cost. Times have changed, however. Today water is free neither for people nor for industry. In fact, the cost of water for industry has risen to such a level that it is now considered the same as for any other raw material. Water fulfills several roles and functions in all types of industries. Almost all of the water used in many industries ends up as industrial wastewater. Release of this into the environment creates a significant footprint and may also create other hazards. This is especially true for chemical and allied process industries. It is imperative that every effort is made to reduce water usage and to treat wastewater to make it reusable or at least safer to discharge into the environment.
The world went through a major transformation in the 20th century and there have been spectacular changes in materials, industrial operations and computational process, which themselves are just broad classes for thousands of advances over the last century. Industrialization has resulted in significant lifestyle improvements for human beings, on many levels.
Unfortunately, there is another side to this rosy picture, that of increased risks to humans and the environment caused by the industrialization and development that has taken place. The effects of industrialization can be seen in the form of air, water and soil pollution that may threaten the very existence of living species on the earth if remedial measures are not taken. Continuous extraction of water results in depletion of available water sources in and around industrial areas. In addition, wastewater discharge into natural watercourses causes surface and groundwater pollution, leaving water unsafe for potable use and impairing industrial use without major and costly treatment.
The current low cost end-of-pipe treatment approach will become increasingly expensive as effluent discharge standards become more stringent. Meanwhile, technological advancements now make it possible to treat wastewater for a variety of industrial reuse operations. Most industries, even in developing countries, are already moving toward wastewater reuse; source separation and treatment of separated effluents is gaining more attention. Wastewater reuse potential in different industries depends on waste volume, concentration and characteristics, best available treatment technologies, operation and maintenance costs, availability of raw water and effluent standards. Radical changes in industrial wastewater reuse have to take into consideration rapidly depleting resources, environmental degradation, public attitude and health risks to workers and consumers.
Discharge of wastewater into natural water bodies also increases costs for industries located downstream, which translates into higher production costs that are inevitably passed on to consumers. This discharge may also exceed natural purification capacities and deplete dissolved oxygen below levels that can support aquatic life. Meanwhile, industries using groundwater are causing severe damage to aquifers and their recharge capacity, resulting in lower groundwater levels each year. For countries located in coastal areas, seawater intrusion is also threatening to make groundwater unsuitable for direct use.
Public awareness and government application of effluent standards has forced many industries to implement appropriate treatment technologies. Initially, industries adopted simple physio-chemical treatment systems, but rapid degradation of the environment has forced governments to implement more stringent regulations for wastewater effluent. These standards have led to more advanced biological and membrane technologies. As water for industrial applications becomes less easily accessible, industry must look for ways to recycle and reuse treated water.
The potential for industrial wastewater reuse is dependent on a variety of factors and differs from one industry to another. Industries consuming a large volume of water obviously have greater potential for internal reuse. Similarly, simple physical and chemical treatments may be sufficient for wastewater produced from activities such as washing floors and cooling. Other industrial wastewaters have high concentrations of toxic chemicals, which must be removed, but this is actually an advantage if usable by-products can be recovered.
In the coming years, newer forms of existing methodologies and emerging technologies will dominate continuing developments worldwide and will contribute in a major way to alleviating the risks posed by environmental pollution. Water is a critical element in this scheme for safeguarding the environment and as a result, industrial wastewater treatment is an issue that will remain in the forefront in the future. Another facet to this problem is water scarcity around the world, especially in developing countries. Water management is, therefore, one of the most important problems facing those trying to ensure environmental protection and sustainability. This problem can best be resolved through effective wastewater treatment, recycling and reuse.
Present day industrial wastewater
Present day industrial wastewater treatment involves primary, secondary and tertiary treatment stages. It also tends to employ a combination of chemical and biological treatment methods in order to meet the discharge norms for treated water. In general, industrial wastewater treatment requires a large amount of chemicals, multiple operations and designs, a fairly high degree of process control and regular maintenance. In fact, in many plants, maintenance has been such a serious issue that effluent treatment plants fail to operate as per the desired standards or have to close down. Stringent pollution control norms require maintaining complex systems that are difficult to oversee and thus, require trained operators, especially for the maintenance and operation of biological treatments (anaerobic systems in particular). This complexity also leads to an escalating cost of treatment.
How to reuse industrial wastewater for industrial purposes
Water is one of the most irreplaceable elements in the industrial production equation. More and more manufacturing companies are recycling wastewater whenever reuse can be implemented as a feasible, cost-effective option. Innovative industrial water purification technologies make it economically feasible to convert all kinds of wastewater back into a purified, reusable state. After treatment, this water once again becomes a valuable asset instead of a potential financial and environmental liability.
Industrial water reuse applications
Industries can recapture and purify wastewater that would otherwise be lost, and recycled water can be used for a variety of applications. Those include washing, rinsing, plating, spraying, coating, cooling, boiler water make-up, cooling tower make-up and fire suppression systems. Even unusually problematic and elusive substances such as ammonia, which can corrode and damage copper components of manufacturing facility equipment, can be successfully removed from water using today’s industrial water purification technology. The toughest water treatment problems can be addressed and solved by skilled engineers with access to the right equipment. That includes everything from purifying and recycling of typical grey water, to recycling wastewater used or generated by the oil and natural gas industries
Microfiltration techniques also substantially contribute to the recovery of water for industrial purposes. In the powder-coating industry, huge amounts of water are used in the finishing process. But filtering with reverse osmosis and deionization can allow these businesses to reclaim up to 90 percent or more of their post-process water and use it again.
While lots of companies are focused on removing chemical contaminants from water, there are also manufacturers that benefit from doing just the opposite and separating the water from expensive chemicals. Companies that use expensive raw and intermediate chemicals, for example, can sometimes concentrate and isolate them from a wastewater stream using high-tech membranes and other technologies. They can reuse these chemicals or minerals, while also ensuring that the discharged wastewater is cleaner and will have a less detrimental impact on the environment. One of the most affordable first steps for industrial companies seeking to reclaim wastewater is to conduct a professional water usage audit. Water engineers can pinpoint exactly where the most money can be saved and can then recommend appropriate solutions tailored to a manufacturer’s specific needs and budget.
Available treatment technologies
The degree of treatment required varies according to the specific reuse application and associated water quality requirements. The simplest treatments involve solid/liquid separation such as sedimentation, aerobic biological treatment, oxidation ponds, biological nutrient removal and disinfection. More complex treatment systems involve combinations of physical, chemical and biological processes employing multiple barrier-treatment approaches for contaminant removal, such as activated carbon, air stripping, ion exchange, chemical coagulation and precipitation. More advanced technologies include microfiltration, ultrafiltration, nanofiltration and reverse osmosis.
Use of membrane technology has been successful in removing most contaminants from wastewater, thereby increasing the potential for even greater reuse. The advantages of membrane technologies are the small space requirement compared to other systems, better process control and potential for intermittent operation. Combined with aerated membranes, they can be used in pulp and paper as well as textile wastewater treatment and reuse. Membrane technology provides an attractive alternative to extend the range of wastewater applications.
Zero liquid discharge
Another effective treatment is zero liquid discharge (ZLD), which is an engineering approach to water treatment where all water is recovered and contaminants are reduced to solid waste. While many water treatment processes attempt to maximize recovery of freshwater and minimize waste, ZLD is the most demanding target since the cost and challenges of recovery increase as the wastewater gets more concentrated. Salinity, scaling compounds and organics all increase in concentration, which adds costs associated with managing these increases. ZLD is achieved by stringing together water treatment technology that can treat wastewater as the contaminants are concentrated.
There are a number of benefits to targeting ZLD for an industrial process or facility:
- Lowered waste volumes decrease the cost associated with waste management.
- Recycling water on-site lowers water acquisition costs and risk. It can also result in less required treatment versus treating to meet stringent environmental discharge standards.
- Reduces transportation costs associated with off-site wastewater disposal, as well as associated greenhouse gas impact and community road incident risk
- Improved environmental performance and regulatory risk profile for future permitting
- Some processes may recover valuable resources, for example ammonium sulphate fertilizer or sodium chloride salt for ice melting.
Several methods of waste management are classified as ZLD, despite using different boundaries to define the point where discharge occurs. Usually, a facility or site property line that houses the industrial process is considered the border or boundary condition, where wastewater must be treated, recycled and converted to solids for disposal to achieve ZLD. Some facilities send their liquid waste off-site for treatment, deep-well disposal or incineration and consider this to qualify as ZLD. This approach eliminates continuous discharge of liquids to surface waters or sewers, but can significantly increase cost.
Some engineers describe their designs as near-zero liquid discharge or minimal liquid discharge, to highlight that they discharge low levels of wastewater, but do not eliminate liquid in their waste. For some facilities, it may be more economical to approach (but not achieve) complete ZLD by concentrating brine to lower volumes. Furthermore, it may be possible to avoid the creation of liquid waste on-site through careful water conservation or by treating contaminants at their source before they can enter the main flow of water.
Why is zero liquid discharge important?
In a world where freshwater is an increasingly valuable resource, industrial processes threaten its availability on two fronts, unless the water is treated. Many industrial processes require water and then reduce the availability of water for other uses, or alternately contaminate and release water that damages the local environment.
Although the history of tighter regulations on wastewater discharge can be traced back to the US Clean Water Act of 1972, India and China have been leading the drive for ZLD regulations in the last decade. Due to heavy contamination of numerous important rivers by industrial wastewater, both countries have created regulations that require ZLD. They identified that the best means to ensure safe water supplies for the future is to protect rivers and lakes from pollution. In Europe and North America, the drive toward ZLD has been pushed by the high cost of wastewater disposal at inland facilities. These costs are driven both by regulations that limit disposal options and factors influencing the costs of disposal technologies.
Another important reason to consider ZLD is the potential for recovering resources that are present in wastewater. Some organizations target ZLD for their waste because they can sell the solids that are produced or reuse them as a part of their industrial process. Regardless of an organization’s motivations to target zero liquid discharge, achieving it demonstrates good economics, corporate responsibility and environmental stewardship. By operating an in-house ZLD plant, disposal costs can be reduced, more water is re-used and fewer greenhouse gases are produced by off-site trucking, which minimizes impact on local ecosystems and the climate.
The benefits of ZLD
ZLD has become a popular way to increase the environmental sustainability of industrial plants in a wide variety of different sectors—from the production of chemicals, oil and gas to the generation of energy, particularly in regions with a short supply of freshwater. ZLD not only reduces the ecological footprint of a plant by eliminating wastewater discharge, but also increases water reuse and allows for the recovery of valuable by-products. In this way, it helps companies meet stringent wastewater disposal regulations, as well as water reuse guidelines and also improves their public image. ZLD is an effective method to eliminate wastewater discharge, recycle water and recover valuable solids and chemicals.
About the author
Dennis Abraham Thazhamon, Managing Director of Josab India Pvt Ltd for the India and Southeast Asian regions, is a highly qualified marketing and management professional with a primary focus on entering new markets. A water expert who focuses on sustainable living for everyone, he has been honored with the 51 Fabulous Global Water and Water Management Leaders award. Abraham is currently working toward making a difference in the lives of people via natural treatment of water so they can continue enjoying good health by drinking treated, natural water.
About the company
Josab India Pvt Ltd, a fully owned subsidiary of Josab Water Solutions AB, Stockholm, Sweden, has been providing safe drinking water solutions in India since its launch in 2012. The company produces and sells products, solutions and services for ecologically sound water purification. Because of the Aqualite™filter material, large volumes of water can be purified in an ecologically safe way at a low cost, leading to long-term sustainability. The company’s primary focus is on rural areas, where access to safe drinking water is barely minimal. Since its launch in India, Josab’s Aqualite-based technology has been approved and acclaimed by various public and private entities. Currently Josab India is expanding its territories in terms of acquiring market and diversification where the requirement for pure water is pivotal.