Acidic Wastewater Treatment
Many wastewaters have a pH of less than 7. Plating rinse waters are one example. Moderately acidic wastewater can often be processed in an ENCON Evaporator with standard materials of construction. Highly acidic waste streams or those with both high chlorides and low pH may need elementary pH adjustment and/or more corrosion resistant alloys of construction.
What is Acidic Waste Water
Many common wastewaters are considered acidic. Acidic is defined as having a pH of less than 7. The pH scale measures how acidic or alkaline (basic) a substance is. The scale is logarithmic and each pH value below 7 is ten times more acidic than the next level. So, for example, a pH of 5 is ten times more acidic than a pH of 6 and one hundred times more acidic than a pH of 7.
- What are the Concerns with Acidic Wastewater?
A pH below 2 is considered corrosive by the RCRA and is classified as hazardous. Even acidic wastewaters above 2 can be a concern due to its potential to prematurely corrode metals and other materials.
In industrial wastewater evaporation, the pH, temperature, and inorganic chloride levels have the greatest impact on potential material corrosion. The ideal pH range for wastewater evaporation is 6-7. At elevated temperature, this pH range minimizes the corrosivity of the wastewater as well as any foaming tendency.
- Using an Evaporator for Acidic Wastewaters
ENCON Evaporators uses 316ss as the standard material of construction on all wetted parts in our evaporators. This durable stainless steel is appropriate for most applications, but if the combination of wastewater pH and level of inorganic chlorides is determined to be too corrosive, ENCON offers a number of solutions.
1. Often the simplest solutions is to do an elementary pH adjustment to bring the waste stream to a pH between 6-7. This solution is generally affordable and can be automated. If your waste stream is deemed hazardous by RCRA due to the low pH, adjusting makes even more sense. In many cases, adjusting the pH to a more neutral level eliminate the hazardous RCRA designation and can often be done without permitting. We typically recommend pH adjustment with rayon grade sodium hydroxide due to the low chloride content of that chemistry.
2. Another option is using a more corrosion resistant alloy of construction for the tank and heat exchanger.
- How is the need for pH adjustment or Corrosion Resistant Alloys Determined?
The centerpiece of our consultative approach is the wastewater qualification process. Not all waste streams are good candidates for evaporation. We believe it’s better to find that out in our laboratory than on your factory floor.
This free analysis determines how appropriate the waste stream is for evaporation and how it will function in the ENCON evaporator. This analysis also helps determine materials of construction and allows us to determine operating procedure recommendations. If more detailed analysis of specific parameters is needed, ENCON can prepare appropriate samples and send them for outside lab analysis for a nominal cost (prices for analytical tests vary).
Once the analysis is complete, your ENCON Sales Engineer will deliver a report detailing the results to you. This report includes material of construction and pH adjustment recommendations, if needed. This allows you to make an informed decision if an ENCON evaporator is right for you.
- How do I Find Out if Evaporation is the Right Solution for my Waste Stream?
That's easy! Just contact one of our Sales Engineers. Use the quick question form on the left, or call us at (603) 624-5110.
It all starts with your initial conversation with an ENCON Sales Engineer. These experts take the time to truly understand your needs and your own unique wastewater challenges.
Their thorough knowledge of the wastewater industry in general and evaporation technology in particular allows them to manage ENCON’s resources toward addressing your unique wastewater disposal project.
They’ll get to know the processes in your plant that generate wastewater. How you currently deal with it. Even what processes you might implement in the future that may affect the volume and quality of your wastewater. This allows them to help you select the right evaporator for today and tomorrow.