The installation and operation of advanced wastewater treatment which aims at reducing organic micropollutants left after the biological treatment, will incur additional cost of treatment. The additional treatment cost for using ozone is surprisingly low according to the following referenced studies.
In Switzerland, upgrading large-scale WWTPs (>80 000 person equivalent) with additional ozonation is expected to increase the present biological wastewater treatment cost by 10-20% while the energy consumption is predicted to increase by 5-30%. As expected for small-scale wastewater treatment plants the estimated cost will be 20-50% more (Eggen et al., 2014).
The cost of employing ozone to remove PPCPs and EDCs in wastewater was also estimated by Rocarro et al. (2013) as total unit cost, including annual depreciation charge of capital cost and operation and maintenance cost. For WWTPs with 50 000 – 200 000 person equivalent, the total cost lies between 0.3 and 0.4 €/m3 wastewater (Rocarro et al., 2013).
The cost for removing trace pharmaceuticals including disinfection by ozone in a Danish hospital wastewater following membrane treatment was also investigated. According to Nielsen et al. (2013), the operational cost for this treatment train is estimated to be 0.22–0.4 €/m3 water, for ozone dose of 82 mg/l and 156 mg/l, respectively. In this study, ozone appeared to be the cheapest technology to reduce micropollutants in hospital wastewater compared to other technologies tested.
In Sweden, an estimated total cost of 0.23 €/m3 of wastewater can be expected when ozone is added as a post-treatment at a dose of 10 g/m3. The estimated cost for ozone appears to be lower than other technologies such as UV and activated carbon (See figure below).
Based on the estimated costs presented, it is feasible to upgrade wastewater treatment plants with advanced treatment such as ozonation for micropollutant removal. Such an upgrade will only cause a minor increase in the total treatment cost of the existing biological treatment with reasonable energy consumption. The associated investment costs may vary and is largely dependent on the plant size, treatment goal and desired water quality.
For a comparison of costs between different treatment solutions download the Cost of treatment comparison
adapted from the Swedish study referred to above.