How Industry Can Help Maintain a Healthy Environment Conservation among residential consumers has become a mainstay of utility operations, but opportunities abound among industrial users to put conservation measures into practice. This e-mail interview with wastewater expert Daniel Theobald details the ways in which industry can incorporate recycling and reuse into their daily operations.
Theobald, proprietor of Environmental Services, is also a professional wastewater and safety consultant/trainer. He is known in the industry as “Wastewater Dan” and has more than 24 years of hands-on industry experience operating various wastewater treatment processing units.
Theobald is a trainer in wastewater and industrial health and safety topics and is eager to share his knowledge with others to promote conservation of water (www.ConserveOnWater.com).
In what ways can industry conserve water?
In order to conserve water, industrial users should first analyze the water requirements of each procedure they implement, going through each one step by step to determine the most water-efficient ways to complete each work task while also preserving the locally restrained supply of quality potable water. For instance, in our homes, we can do things like install low-flow toilets, limit our shower time, minimize water use by not let- ting the water run when we’re brushing our teeth, adjusting the water level to match the size of a load in the washing machine, and only run the dishwasher when it’s full. Similar principles can be applied to industrial water use, such as analyzing exactly how much water is needed for each process, installing timers or high-pressure flow restrictors, reusing water, or eliminating water use from tasks whenever possible.
What is industrial water recycling and reuse?
Although recycling easily comes to mind when people are disposing of aluminum cans, glass bottles, and newspapers, water is not always considered for recycling. Industrial water recycling, which offers both resource and financial savings, simply means reusing treated wastewater in certain industrial processes. Wastewater treatment can be tailored to meet the water quality requirements of virtually any proposed reuse.
Water is sometimes recycled and reused onsite, such as when an industrial facility recycles water used for cooling processes. A common type of recycled water is water that has been reclaimed from municipal wastewater or sewage. The term water recycling can be used synonymously with water reclamation and water reuse.
Recycled water can comply with most water demands as long as it is adequately treated to ensure water quality that is appropriate for the use.
Another type of recycled water is “gray water.” Gray water includes reusable wastewater from industrial bathroom sinks, bathtub shower drains, and clothes washing equipment drains. The use of nontoxic and low-sodium soap—which is defined as no added sodium or substances that are naturally high in sodium—and personal care products is required to protect vegetation when reusing gray water for irrigation. Gray water is reused onsite, typically for landscape irrigation or general spray applications.
Recycled water is most commonly used for non-potable uses. However, recycled water can also be used for a number of industrial purposes, including boiler or cooling tower feed water supplementation, pH adjustment, washing equipment, hardstands and vehicles, fire protection, process rinse water or processing water for production lines in manufacturing industries, toilet flushing, dust control, construction activities, and concrete mixing.
What are some of the benefits of recycling industrial water?
In addition to providing a dependable, locally con- trolled water supply, water recycling provides tremendous environmental benefits. By providing an additional source of water, water recycling offers ways to decrease the diversion of water from vital, sensitive eco- systems, thus ensuring that sufficient water flows to plant,
wildlife, and fish habitats—allowing them to live and reproduce. A lack of adequate
flow, as a result of diversion for agricultural, urban, and industrial purposes, can cause
deterioration of both water quality and ecosystem health. Water users can fulfill their
demands by using recycled water, which can free substantial amounts of water for the
environment. Other environmental benefits include a reduction in wastewater dis-
charges and reducing or preventing the potential for pollution.
Recycled water can save energy. As the demand for water increases, more water is
extracted, treated, and transported—sometimes over great distances—which can
require a lot of energy. Also, if the local source of water is groundwater, as more
water is removed the water level drops, which in turn increases the energy needed to
pump the water to the surface. Recycling water onsite or nearby reduces the energy
needed to move water longer distances or to pump water from deep within an aquifer.
Tailoring water quality to a specific water use also reduces the energy needed to treat
water. The water quality required to flush a toilet is less stringent than the water
quality needed for drinking water and requires less energy to achieve. Using recycled
water that is of lower quality for uses that do not require high-quality water saves
energy and money by reducing water or wastewater treatment requirements.
What are the strategic industrial applications for recycling and reusing water?
Industries in general should adopt overall management strategies for reducing the
consumption of and increasing the use of reclaimed water in a number of ways:
• Group industries in a particular site, such as in industrial park, to support
the utilization of combined treatment methods and reuse policies.
• Ration water use within each unique industry by analyzing each work task or
process to define the acceptable quantity of water that should be used. Reorganizing
water use in different processes allows for greater efficiencies to be established in
such processes as countercurrent washing, high-pressure air-rinsing, cascading
circuits, and so on.
• Replace a water use application by pneumatic or mechanical systems instead
of using water for transportation. These substitutions could easily be made in both the
poultry and food industries.
• Apply enforceable economic sanctions such as penalties, water charges,
subventions, credits, and grants.
• Adopt process modification to minimize water consumption. These could
involve open to closed systems of manufacturing processes.
Specific industries should value critical strategic steps in industrial water recycling
and reuse, which includes an analysis of the quality and quantity of industrial water
produced. The resulting values may be highly variable depending on a range of factors,
including but not limited to the raw process material; the industrial process that
generates the water—for example, raw material washing, finished goods wash water,
process filtrates, centrifugations and pressings, and boiler and cooling tower blow
down; the number of times the water has been reused, potentially increasing or
decreasing the concentration levels of contaminants; the characteristics of the
products and surfaces the water contacts; reactions that occur during the industrial
process; additives such as biocides, anti-scaling agents, and pH adjusters; and the
temperature of the water.
Another vital step in industrial water recycling and reuse includes an analysis of the
quality and quantity of industrial water use requirements that are highly variable,
depending on specific industrial demands. There are several major areas in which
recycled wastewater could be used by industry.
• Cooling consumes a large volume of water that can easily be supplied by
recycled wastewater. Cooling water discharge generally contains low amounts of
pollutants. Justifications for using recycled water for cool- ing purposes includes the
fact that more than half of all industrial water is used for cooling. Most of the intake
water in electric power plants and oil refineries is used as cooling water. Cooling
water is easy to treat, and thus it is easy to reuse. In addition, reusing cooling water
would eliminate the problems associated with discharging heated water into aquatic
• Boiler feed water consumes a large volume of potable water that can be
replaced with recycled wastewater. Boiler feed water discharge is generally low in
pollutants. Boiler feed water is used in a number of industries primarily for the
generation of steam for manufacturing processes and after simple treatment can be
• Washing depletes a comparatively small volume of water that can be
supplied with recycled wastewater. Wash water discharge is generally high in
• Process water uses a comparatively small volume of water for which
recycled wastewater could be substituted. Process water discharge is generally high
in pollutants. Processes depend on varying water quality. Washing and transporting
processes such as flocculation, sedimentation, and filtration of water for and from
other processes requires only low-quality water. Oil well injection requires high-
quality water, which would need to undergo treatment by advanced membrane
filtration processes such as micro- and ultrafiltration. Reuse water for the chemical,
food, and textile industries would generally require treatment by reverse osmosis.
• Industry in general may make use of reclaimed municipal wastewater. This
practice has been in place for years, especially for replacing cooling and boiler feed
water. Secondary effluent can be used in industrial processes after proper disinfection,
for example in the mining and metal processing industries for washout. Secondary
effluent must undergo tertiary treatment before reuse. The specific requirement of the
treatment process depends on the final industrial reuse application.
What are some of the industries that could easily accommodate reuse into their
There are several industries that immediately come to mind. Industries that consume
large volumes of water would be excellent prospects for reuse. These industries
include paper and pulp manufacturers, power plants, water treatment plants, soft
drinks, canned foods, and steel industries to name a few. Industries that discharge
highly toxic effluent are also candidates.
These include organic and inorganic chemical processes and plastics and resins
Are there other industries that could incorporate reuse into their daily practices?
Industries that produce wastewater, such as photographic processing, could recover
Industries that have the potential for higher future growth and water consumption
include pharmaceutical products, semiconductor manufacturing, and computer
How do water conservation and water recycling and reuse protect aquifers?
Every gallon of water recycled and reused replaces water use formerly supplied by an
aquifer. This strategy helps protect aquifers because such water bodies are rapidly
being depleted by human activities.