Energy Effectiveness of Direct UV and UV/H₂O₂ Treatment of Estrogenic Chemicals in Biologically Treated Sewage

Continuous exposure of aquatic life to estrogenic chemicals via wastewater treatment plant effluents have in recent years received considerable attention due to the high sensitivity of oviparous animals to disturbances of estrogen controlled physiology. The removal efficiency by direct UV and the UV/H2O2-treatment were investigated in biologically treated sewage for most of the estrogenic compounds reported in wastewater.

The investigated compounds included parabens, industrial phenols, sunscreen chemicals and steroid estrogens. Treatment experiments were performed in a flow through set-up. The effect of different concentrations of H2O2 and different UV doses was investigated for all compounds in an effluent from a biological wastewater treatment plant.

Removal effectiveness increased with H2O2 concentration until 60 mg/L. The treatment effectiveness was reported as the electrical energy consumed per unit volume of water treated required for 90 % removal of the investigated compound. It was found that the removal of all the compounds was dependent of the UV dose for both treatment methods.

The required energy for 90% removal of the compounds was between 28 kWh/m3 (butylparaben) and 1.2 kWh/ m3 (estrone) for the UV treatment. In comparison the UV/H2O2-treatment required between 8.7 kWh/m3 (bisphenol A and benzophenone-7) and 1.8 kWh/m3 (17α-ethynylestradiol).