Sustainable design and engineering involve minimizing the everlasting impact on the environment.  From a design perspective, it involves the use of environmentally friendly materials of construction and minimizing the use of non-renewable resources.  For pharmaceutical water treatment systems, sustainable design is intrinsically linked to water conservation, water reuse, and wastewater minimization.  Designers, owners, and operators of these systems, already challenged with an increasingly competitive business environment, are realizing the synergies between environmental stewardship and efficient operation.  Companies are aligning policies that aim to simultaneously produce lean operations and promote a culture of social and environmental responsibility.

Pure water used as a utility or an ingredient in pharmaceutical processing applications can be one of the most costly items to produce efficiently and consistently.  Water conditioning technologies often involve the use of chemicals, energy, and consumables to maintain this high-degree of reliability required for most stakeholders.  Additionally, techniques such as cross-flow filtration and distillation, which involve purification by dilution of process streams, produce concentrated streams as by-products of operation.  Traditional Reverse Osmosis (RO) systems have historically operated at inefficiencies as high as twenty-five percent.  Moreover, common pharmaceutical RO applications often rely on a substantial number of pretreatment operations such as water softening, de-chlorination, and suspended solids reduction to operate effectively.

Green Design Principles

Applying green design concepts to high-purity water systems may include a focus on materials of construction, disposable technologies, and the use of chemical agents.  To properly assess the total environmental life cycle (cradle-to grave) cost of different technology options, one must consider the impact on the environment to create or manufacture a certain technology or component, the effect on the operation over the useful life, and the demolition or disposable effect.  The challenge for water treatment system design engineers to grapple with the environmental life cycle cost while still considering the economic life cycle cost can be difficult.

A logical extension to the green design of buildings and infrastructure is the promotion of efficient operation and logistics associated with processing and manufacture.  Water, a ubiquitous solvent, is found in most manufacturing operations.  Pharmaceutical water, a critical substance or product of many operations, would be a logical target for green design because of the limited availability of source water and the concern regarding protection and contamination, as well as the inefficiencies and cost of production.  As water utility and discharge costs increase and with tightening regulation regarding potable water quality, water conservation techniques offer a promising solution to minimizing utility costs in the future.

Water Conservation

The consumption of raw water and the return to the environment is regulated at the federal level by the Environmental Protection Agency, and at the state and local levels by municipalities or local cities and towns.  Improving the efficiency of process operations and minimizing consumption and discharge of water and wastewater can be both environmentally and economically rewarding.  All manufacturing processes that require the use of high-purity water; from microchip rinsing, to medical device washing, to pharmaceutical manufacturing, will likely have concentrate or reject streams.  Water recycle or reuse may not be practical in all applications, but the efficiency of all water treatment processes can be improved.

Water Treatment System Design and Operation

There are many opportunities to conserve water and improve the efficiency of high purity water systems. 

• Improved process monitoring may lead to less maintenance.  Examples include backwashing media filters based on differential pressure across the filter rather than time and regeneration of water softeners and ion-exchange units based on effluent quality.  Digital monitoring of key process variables is being used successfully to optimize many unit operations by extending service cycles based on actual operating data rather than arbitrary values.
• High Recovery RO design to minimize wastewater.  Methods to improve RO recovery include quality pretreatment methods, novel membrane technologies, and sacrificial membrane elements, and brine recovery systems to recover reject water.  Designing and operating a pharmaceutical water system at feed water recovery as low as 75% percent is unacceptable for today’s environmental and business standards.  Many opportunities exist to improve operating efficiencies for both new and existing systems.
• Reuse of RO and Electrodeionization (EDI) Reject Water.  These streams are often softened, dechlorinated, and filtered, making their application for reuse suitable for most boiler feed waters or cooling tower make-up.  Additional non-potable uses such as toilet feed water and irrigation have also been employed.
• Cleaning and Sanitization Technologies.  The use of ozone technology for cleaning and sanitization can be a substitute for traditional chemical technologies that require excessive amounts of rinse water.

Minimizing Environmental Impact

Additional industry trends for sustainable beyond water conservation include the following:

• Reduction in Plant Steam Usage – Steam has long been used as a sanitization method for pharmaceutical water systems.  In an effort to minimize steam consumption and reduce operating costs, many pharmaceutical water system designs are now based on electric steam heaters for sanitization of generation systems and ozone for storage and distribution systems.
• Recycle of Activated Carbon – Spent activated carbon can be recycled, reactivated, and reused in secondary markets.  This minimizes the amount of materials sent to landfills
• Repurposing of Membrane and Ion-exchange Resin – Although a widespread recycling program for membranes and resins does still not exist in the industry, a secondary market does exist for some of these components.  Having been applied to high-purity process streams, they may be suitable industrial or wastewater applications after their useful life in a pharmaceutical water system.
• Optimization of Consumable Lifespan – Consumable replacements, such as filters and UV bulbs, can be minimized by developing a changeout program based on the performance of the components rather than an arbitrary value suggested by a supplier.

Note that improving a water footprint may not necessarily reduce the overall carbon footprint for a pharmaceutical water system.  Conserving water at the expense of additional strain on process components may result in decreased lifespan or increased system maintenance.  For example, single use or disposable technology to replace a backwash or regenerable processes should be evaluated based on the overall environmental impact.  Water conservation alone should not be the sole consideration for sustainable design and operation of systems.

Note: This piece is a revision of a previous post.  It has since been revised and updated.