Sustainable design and engineering involve minimizing the everlasting impact on the environment. From a design perspective, it means using of environmentally-friendly construction materials and minimizing the use of non-renewable resources. It also includes engaging in sustainable (a.k.a. green) operation and maintenance activities. For industrial water treatment systems, sustainable design is intrinsically linked to water conservation, water reuse, and wastewater minimization. Already challenged with an increasingly competitive business environment, designers, owners and operators of these systems 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 industrial 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 industrial 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 #reverseosmosis (RO), an incredibly wasteful process, will generally operate at inefficiencies as high as twenty-five percent for most industrial applications. Moreover, common industrial RO applications often rely on a substantial number of pretreatment operations such as water softening, de-chlorination, and suspended solids reduction to operate effectively.
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 lifecycle (i.e. cradle-to grave) cost of different technology options, one must consider the impact 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 is to grapple with the environmental lifecycle cost while still considering the economic lifecycle cost.
A logical extension to the green design of buildings and infrastructure is the promotion of efficient operation and logistics associated with processing and manufacturing. Water, a ubiquitous solvent, is found in most manufacturing operations. #Highpuritywater, 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 - #waterconservation techniques offer a promising solution to minimizing utility costs in the future.
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 parts 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.
High Recovery RO design to minimize wastewater. Methods to improve RO recovery include quality pretreatment methods, novel membrane technology, and sacrificial membrane elements to recover reject water.
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.
Designing and operating an industrial 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.