Treating Wastewater with Ozone
Ozone is an intense and highly reactive form of oxygen with oxygen atoms that have been used for Treating Wastewater worldwide. Similar to drinking water, ozonation has been implemented in wastewater as a disinfectant before its discharge to the receiving water bodies
Oxidation of micropollutants for potable water reuse purposes
Potable water reuse requires a multibarrier approach to guarantee microbial and chemical drinking water safety. Currently, most of the water reuse facilities rely on systems that treat municipal wastewater effluent by a sequence of membranes (micro- or ultrafiltration and reverse osmosis (RO)) followed by an advanced oxidation
process (most commonly UV/H2O2) and a disinfection step for the distribution system. This scheme can also include a pre-ozonation for disinfection as the primary treatment step.
Oxidation of micropollutants to reduce their discharge to water bodies
Ozonation is selected as the oxidation process for enhanced wastewater treatment in many countries, because of the broad spectrum of micropollutants that can be abated during ozonation. It was shown that biologically active compounds such as estrogens, antibiotics, antivirals, and pesticides lost their primary target effects during ozonation and other AOPs in the laboratory in vitro studies. During the ozonation of real wastewaters in laboratory pilot and full-scale studies, mixed results were obtained with various toxicological endpoints such as the fish early life stage toxicity test, the chironomid toxicity test, the Lumbriculus toxicity test, the Ceriodaphnia dubia toxicity test with mostly a reduction in toxicity but in some cases also an increase. However, biological post-treatment by sand or activated carbon filtration led mostly to a significant reduction of the toxicity, wherefore, typically, a biological post-treatment step is implemented after the ozonation of wastewater.
Ozone for Watercolor
It has been demonstrated that ozone oxidation satisfactorily removes the color of tannery wastewater. However, it is an expensive method and Pre-determination of the applied ozone dosage is an important factor for cost-effective applications in full-scale Ozonation plants. Under laboratory conditions, sometimes it is observed that the applied ozone can escape through the reactor. However, in full-scale applications, a maximum amount of ozone should be used in the reactions due to economical considerations.
Ozone is effective in removing the color from all dyes used in textile processing. The amount of ozone can vary depending on a number of factors: how much color was removed in the biological process, the type of dye used, where ozone is applied in the process, etc. Knowing the proper amount of ozone required to meet the color removal objective for the receiving water body is critical to the economics of the ozone system. In general, it is not easy to predict the amount of ozone required, so in virtually all cases where specific previous experience is not available, pilot testing is employed.
Tosik has shown that about 1 mg ozone/mg dye is required to achieve 95% color removal, although this ratio varies by dye type. The ratio increases to about 1.5 for 100% removal. Reaction times were on the order of 10 minutes. In the textile industry, a typical dosage might be 15 mg/l post-biological treatment, but the levels could easily reach 25 mg/l. It is important to note that the ozone dose only needs to make the dye compound uncolored and not necessarily completely mineralize the material.
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