Some industrial processes produce contaminated wastewater, either from organic compounds, dissolved gasses or other matter. In these cases, you need to use some kind of scrubber to prevent those organic compounds from polluting the local environment. A steam stripping column is one of these scrubbing methods.
Uses of a Steam Stripping System
In a steam stripping system, steam is used to remove volatile organic compounds (or VOCs), such as methanol, ethanol, benzene and hexane, or dissolved gasses such as ammonia from wastewater streams. Steam stripping is a VOC scrubber and is also known as steam distillation.
Steam stripping is one of the most cost-effective forms of VOC scrubbing and can remove up to 99% of VOCs. Steam stripping does require a very tall column to be efficient, however. This can lead to somewhat high initial construction costs.
Steam stripping systems are most often used when wastewater needs to be recuperated to prevent pollution — which means a wide range of industries use them. Wastewater steam stripping can prevent organic compounds from being introduced into the environment when wastewater is disposed of.
How Wastewater Steam Stripping Works
In a steam stripping system, the contaminated wastewater first enters the steam stripping column, where it is heated and put into contact with high-pressure steam. You will likely have a mix of several organic compounds you need to scrub from the wastewater.
The VOCs are separated from the wastewater by one of two mechanisms. First, these compounds can have a lower boiling point than water. If so, they’ll simply turn to gas and exit the tower with the steam. Some organic compounds won’t boil, but if they are not particularly soluble in water, they’ll also travel with the steam.
Steam scrubbing can pose an environmental risk if the steam is left to simply escape out of a flue. To keep VOCs from becoming air pollution, the steam will need to be captured and treated. This is usually accomplished by passing the steam into a condenser, and then using a decanter to filter out the captured VOCs. Some steam columns will contain tower packing — small, often hollow objects used to increase the contact area between steam and wastewater.
In some cases, not all the organic compounds will completely mix with the steam. This can happen when the concentration of compounds in the steam has passed steam’s solubility limit. Instead, these compounds will separate into an organic phase that will flow out with the water.
You will need to further treat the scrubbed wastewater stream after steam stripping, but this can usually be achieved with a decanter, as the organic material is separate and lighter than the water.
Customized Scrubbing Solutions
Every industry’s scrubbing needs are different. If you need help searching for the right steam stripping system, MACH Engineering is here for you. Our team will meet with you and design the right system for your company. From design to installation, you can count on MACH Engineering. Contact us today for more information.