2010-Saving Water and Energy using Ultra Filtration and Reverse Osmosis in a Dye House in Western Nebraska, USA
Saving Water and Energy using Ultra Filtration and Reverse Osmosis in a Dye House in Western Nebraska, USA
Robert Wells, Brown Sheep Co.
Running a natural fiber dyeing operation in rural western Nebraska, USA presents some unique environmental and production problems. In this rural area, thermal energy inputs are expensive, and public waste water disposal is non-existent.
There are no public water works to supply suitable water; water is pumped from a local well. In this semi-arid climate the scarcity of valuable surface water makes it worthy of conservation efforts. Local, state, and federal waste water regulations are ever present and must be dealt with in the midst of a full production schedule.
Hence, we were challenged by the problem of what to do with the hot, high strength, and multi-colored dye waste water that is produced when wool, mohair, and cotton are dyed. Our goal was to find a technology that could concurrently treat the waste water, conserve and recycle the water, save thermal energy, and have no environmental impact.
The solution would also have to be within the budgetary constraints of a small business.
While researching potential solutions to the above mentioned problem, we were not able to find ready-made systems to solve the problems found specifically in our textile dyeing operations. A universal treatment system applicable to all textile facilities does not exist.
Existing systems, such as membrane bioreactors, while possibly applicable, were much too expensive to implement for a small business dyeing about 2000 pounds of textiles per day. We were forced to identify and test existing technologies that might work and test them for applicability to our specific goals, problems, and budget.
In the past, waste water was simply pumped to a storage lagoon located close to the mill and dye house. Land application like this is no longer feasible, nor desirable. A lined and sealed storage lagoon is also unfeasible because the area required to store 10,000-20,000 gallons of waste water per day would exceed 10 acres.
A technology that has been used in the past to treat dye waste water is membrane-based separation processes. Ultra filtration (UF) and reverse osmosis (RO) became immediate candidates because of their history in successfully treating various types of wastewater streams and it’s affordability for a small business such as ours. These systems have the added capability to recycle heated water, as described in a recent report.
This paper describes the successful implementation of a two stage filtration system from a small business perspective. UF and RO membranes were used to separate and reuse valuable water and thermal energy. The advantages and future directions of this approach is also discussed.