Water Efficiency Magazine

Reuse: Wastewater as a Resource

In times of water scarcity, reuse can be a game-changer.

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NOWADAYS, WATER SCARCITY AND SUSTAINABILITY are big concerns for organizations of all sizes. Interest in water recycling has been growing in many industries because of the way it transforms a waste product into a valuable resource that can be used for many purposes, both in-house and in the community. This can save money and make operations more sustainable.

Through reuse, water-intensive industries can reduce their environmental footprint. For instance, a beverage bottler can use more than 2 liters of water for every liter of bottled water that it produces. Using recycled water for production significantly reduces demand for fresh water taken from surface or groundwater sources.

Advanced wastewater treatment technol­ogies can safely produce water for reuse from industrial, agricultural, or municipal effluent streams in a cost-efficient way. The water can be used within an industrial plant, around the facility, and even in the surrounding community.

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At a manufacturing facility, recycled water has many potential non-potable uses, including flushing toilets, washing fleet vehicles, and controlling dust.

Effluent can be treated to higher standards for specific types of industrial reuse. This includes the production of pure and ultrapure water for reuse in power generation, industrial cooling, and steam production, as well as in food and beverage production.

Outside the facility, recycled water is typically used where no direct human contact with the treated water is anticipated such as for irrigating crops and watering landscaping. It can also be used for recharging groundwater, preserving wetlands, and for addressing other types of ecological needs such as site remediation.

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Economics and regulatory compliance are the overarching drivers for industrial water reuse. Two key advantages of water reuse are that it decreases the consumption of fresh water, and it reduces the volume of wastewater (and thereby the cost of effluent disposal or discharge).

Water supplies continue to diminish as the population
grows, which means less water is available to everyone, including the industry. As water supplies decrease, the cost goes up. So, it makes financial sense for industrial users to conserve existing supplies by using less water in the process of turning raw materials into commercial products.

Corporations are also under increasing pressure to meet both corporate goals and environmental standards. Water reuse can help balance these often divergent challenges.

In one example, when Coca-Cola planned to expand production at its Alcorta plant in Argentina, it not only had to increase its water treatment capacity, but it also needed to meet higher corporate standards related to the ratio between beverages produced and water consumed.

Coca-Cola solved this problem by converting its sequential bioreactor to a continuous bioreactor, and adding an ultrafiltration step. The clarified water can be reused for industrial processes, thus reducing the amount of fresh water needed.

Wastewater recycling reduces the amount of effluent to be discharged or disposed of, which can result in large savings on surcharges and fees based on the volume and chemical composition of the wastewater. Hauling liquid effluent is costly. Options such as deep-well injection and evaporation ponds not only are expensive, but also may have adverse environmental effects, and may not be feasible in all locations.

Before water can be released into the environment, it must be treated to meet strict standards to prevent pollution of surface and groundwater. If it doesn’t, fines and penalties can be considerable—not to mention the reputation damage that can occur whether the pollution is intentional or accidental.

Another important consideration is that reducing effluent allows an operation to increase production capacity without surpassing maximum permitted discharge flow or pollutant mass discharge limits. This saves the trouble of applying for a new or amended permit—a complicated, expensive, and time-consuming process that sometimes ends in rejection.

Many industrial processes produce effluent with special disposal needs.

In oil production, for example, a large quantity of liquid is extracted with petroleum. Pacific Rubiales Energy Corp., a large oil company in Colombia, was disposing of its produced water via deep-well injection. Eventually, disposal costs and environmental constraints meant the company had to find another way to reduce its effluent.

The company opted for a multistage, advanced water treatment solution—including a desalination step—to treat the brackish water left over from the drilling process, maximizing water reuse and lowering the cost of brine disposal.

The facility, designed by RWL Water, produces 500,000 barrels a day of treated produced water, 90% of which is used for irrigation. Only about 10% of the water, including reverse osmosis brine, is still disposed of via deep-well injection. Ultimately, the facility provides a new water resource and saves both money and fresh water.

People often ask which industries are best suited for effluent reuse. In fact, all industries are candidates for water reuse with the right treatment. The exact process depends on the characteristics of the effluent and the desired quality of the end product.

Common wastewater treatment processes—including dissolved air flotation, ultrafiltration (conventional or with a membrane bioreactor), and disinfection—can be used in the treatment of water for reuse. Other technologies, such as reverse osmosis, may be needed. Many of these technologies are becoming more popular, and as their use increases, their cost goes down.

Pacific Rubiales Energy Corp. adopted an advanced multistage water reuse treatment system to recycle its brackish produced water. A desalination step allows the water to be treated to the point that 90% can be used for irrigation.
Pacific Rubiales Energy Corp. adopted an advanced multistage water reuse treatment system to recycle its brackish produced water. A desalination step allows the water to be treated to the point that 90% can be used for irrigation.

Even effluents considered difficult due to high levels of solutes or suspended solids are candidates for reuse.

Water recycling technology can be added to an existing operation, but just how hard and how expensive that will be depends on many factors.

First, a comprehensive audit will be required to identify the sources of wastewater and where the plant’s water is going (this information also can inform water conservation decisions that could reduce the facility’s water footprint).

When the Alcorta Coca-Cola bottling plant in Argentina needed to increase its wastewater treatment capacity and lower its use of fresh water, RWL Water installed a membrane bioreactor and an ultrafiltration step to treat wastewater for industrial reuse.
When the Alcorta Coca-Cola bottling plant in Argentina needed to increase its wastewater treatment capacity and lower its use of fresh water, RWL Water installed a membrane bioreactor and an ultra filtration step to treat wastewater for industrial reuse.

Most industrial or manufacturing plants have existing wastewater treatment systems designed for compliance with discharge regulations. Upgrading such a plant for water reuse will require additional equipment, but shouldn’t affect the existing treatment plant or the facility’s operations. Proper planning and engineering can ensure a smooth transition, with minimal, if any, operational downtime or interference.

In some instances, a project may require significant modification of the existing treatment plant. Construction can be done in stages and scheduled to coincide with maintenance stoppages to minimize disruption of operations.

The addition of a water reuse component may require the upgrade or replacement of existing equipment that uses excessive amounts of water. But the cost of this capital expenditure is often outweighed by other positive economic benefits.

Sometimes traditional water treatment solutions aren’t feasible, particularly in remote locations that lack access to conventional utilities. In these cases, packaged or containerized treatment may be the solution. These self-contained systems include all the necessary features and technologies of a functioning plant, but eliminate many of the expenses and hurdles associated with permanent construction. They can be set up and commissioned within just a few months, which is particularly valuable in disaster zones.

When reopening the Boleo Mine in Baja California, Mexico, the mine’s ownership needed a fast, reliable wastewater treatment system at the remote camp, which lacked access to a main wastewater treatment facility.

Environmental concerns and local regulations made a packaged wastewater recycling plant an ideal solution.

The company chose a 150,000-gallon-per-day packaged plant to treat wastewater, which is reused in dust suppression and for flushing toilets. The water meets local environmental regulations for outdoor use.

Another example of decentralized treatment is RWL Water’s EcoBox, which provides users with wastewater treatment in a 40-foot shipping container that can be operational within 30 days of delivery to the site. EcoBox is a complete water reuse system with all needed equipment, instrumentation, and controls. It’s modular, which makes it easily scalable.

The water produced is suitable for reuse across industries, including mining, power generation, and agriculture. Treatments are specifically tailored based on the intended end use, whether it’s industrial or municipal.

In areas of water scarcity, where clean water sources are limited by geography or drought, water reuse may be the best way to secure a consistent water supply. Even in areas where the situation is less dire, reuse can help preserve existing surface and groundwater resources.

Yet, many organizations that could benefit from water recycling aren’t using it. This is partly because of a lack of incentives, or because current practice—although wasteful—may still conform to regulations.

As a result, industrial reuse systems remain expensive to manufacture. A combination of legislative mandates and incentives should spur demand and competition in the field, ultimately reducing the cost to end-users.

By being better stewards of water, organizations of all sizes can make a significant contribution to protecting fresh water resources for future generations.  WE_bug_web

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