The fundamentals of water reuse
Questions to ponder before beginning a recovery process
Food and beverage industrial water reuse has increased substantially during the last 20 years, and the practice is only growing. The reasons for the sharp upswing in the industry’s water reuse are the same for many other sectors, including the municipal arena with increased water shortages, particularly in drought areas, and legislation regarding water conservation and environmental compliance.
Recovering water and putting it back into use is less a notion of appearing “green” and more about sustainable processing and fiscal common sense. However, the recovery process is not without inherent challenges.
As engineers, many of us want to jump right into a technology solution to solve water reuse. The better reaction is to step back and answer some fundamental questions about your process. The following are three basic questions Woodard & Curran starts with when walking into a new client’s facility:
1. Have you reduced the amount of water you use in the process as much as possible? Nearly every processing facility has at least a few water use inefficiencies. Although it is nearly impossible to be flawless, uncovering areas of leakage, evaporation or other water losses can be the first step in establishing a successful water reuse program. This is the process of “water use minimization” and should precede any efforts to recover any water. An example of water minimization would be evaluating the efficiency of your cleaning processes.
2. Do you understand the water quality requirements for the areas in which you want to use the “cleaned” water? Creating a baseline understanding of the water quality is crucial. Facility personnel managing the different process areas must answer how clean they need the reused water to be. Irrigation, cooling tower makeup, boiler makeup, rinsing process lines, product contact, floor washing and sanitation can all have a range of water standards. What are your standards?
3. What is the most economical way to collect and treat the water? Water reuse generally involves redirecting the wastewater that typically goes down the drain to some method of storage. Reusing sanitary wastewater is never recommended due to the food safety issues that can quickly arise at a processing plant. The best solution is to collect the “cleanest” industrial wastewater possible in two vessels that equalize the flow between incoming wastewater and outgoing clean water.
Lastly, once you have prioritized the wastewater streams based on how economical it is to collect it, you need to identify the most economical treatment technology. Do solids need to be removed? Do you need to remove organic contaminants? Does pH need to be adjusted? Is disinfection required? The technology can be as simple as settling chambers and filtration or as complex as reverse osmosis and ultraviolet light treatment.
Intelligently constructed recovery plans are blueprints. Many food and beverage companies have found contracting water recovery experts who understand both planning and technology to be the best method to a successful recovery system. Additionally, water reuse regulations vary from state to state and from municipality to municipality. Fully understanding these regulations is crucial in developing a facility water reuse plan. Identical facilities in different geographies can have very different plans. BI