In the last posting we discussed the use of oxidation in wastewater treatment. We noted that very high levels of organic in wastewater are likely to make oxidation technologies less economical than other techniques, especially biological. In this post, we will discuss the types of applications where oxidation may be the preferred solution.
In general oxidation techniques are more compatible with applications that have lower levels of oxidizable materials than higher ones. Typically this means in the hundreds of ppm (mg/l) versus thousands of ppm. Second, the contaminants are typically dissolved in water and cannot be filtered. Thirdly, they are either difficult to absorb on carbon or are biorefractory, i.e. bacteria cannot digest them readily.Other factors that would influence a choice for oxidation include:
- Limited Floor Space: An ozone generator for example, can produce a large amount of oxidant in a small space. Biological treatment systems normally require much more space than an equivalent oxidation system, especially where the compounds are bio refractory.
- Carbon Regeneration Cost: Carbon regeneration costs include the cost of renewing the carbon as well as filling and emptying the carbon beds.
- Hauling and Offsite Treatment Costs: In some cases, the wastewater can be hauled off site to a treatment facility. Here the costs include the transport cost for the water as well as the treatment costs.
- Purchase and Storage of Chemicals: Certain oxidation techniques such as ozone, UV and UV/ozone, do not require an purchases of chemicals. Any oxidants that are used can be generated on site.
- Intermittent Generation of Wastewater: Biological systems are efficient when operated continuously. Oxidation systems can be turned on and off readily.
A few examples of wastewater treatment employing chemical oxidation include:
- Color Removal. Ozone has been shown to be very effective at removing even high levels of color from water in both drinking water applications and textile processing.
- Acetone. Acetone is the oxidation by product of isopropyl alcohol. It is not readily absorbed on carbon, but can be mineralized (reduced to CO2) using advanced oxidation techniques.
- CN/Phenol. These compounds are sometimes found together in the foundry industry. While phenol could be biologically treated with proper technique, CN cannot. On the other hand both can be oxidized readily by ozone.
Selecting the proper treatment technique requires understanding the site constraints, the economics for each treatment process, and the final treatment objective. Oxidation can be an effective option for relatively low levels of difficult to treat organic and inorganic materials. Spartan Environmental Technologies offers a broad range of oxidation technologies. Contact us with your wastewater problem to see if oxidation might be a solution.