Abstract
The removal efficiency by photolysis and advanced oxidation (AOP) of some estrogeniccompounds was investigated in tap water and biologically treated sewage. The compoundsinvestigated included parabens, industrial phenols, sunscreen chemicals and steroid estrogens.Treatment experiments were performed using a UV lamp optimized for photochemicaltreatment in a flow through set-up. The effect of different concentrations of H2O2 anddifference between tap water and treated sewage was investigated for all compounds.The treatment effectiveness is evaluated based on the Electrical Energy per Order (EEO) (unitkWh/111e3), which is defined as the electrical energy consumed per unit volume of water treatedrequired for 90 % removal of the investigated compound.It was found that the removal efficiency was better in tap water than in wastewater which isdue to the shadow effect from the inorganic and organic substance in the wastewater. Further,it was found that the removal of all the compounds was dependent of the UV dose for bothtreatment methods. The energy required for 90% removal of the compounds was between 28kWh/111e3 ± 2.9 (butylparaben) and 1.2 kWh/ 111e3 (estrone) for the UY treatment. The AOPresults in a more unifom1 value of EEO, which is between 8. 7 kWh/m3 (bisphenol A andbenzophenone-7) and 1.8 kWh/m3 ( I 7a-ethynyl estradiol).The removal at different concentration of H2O2 was investigated and it was found thatremoval effectiveness increased with concentration until 60 mg/L, but decreased at I 00 mg/L,which may be caused by H2O2 scavenging the HO'-radicals.
Highlights
The presence of estrogenic compounds in the environment has in recent years received considerable attention due to their damaging effects on the aquatic life
2.1 Regents and materials All the estrogenic compounds investigated (See Table I) were purchased from Sigma Aldrich, Methanol, acetone, and heptane together with 35 % hydrogen peroxide, potassium titanium oxide oxalate dihydrate, sodium phosphate monobasic dehydrate and 85 % ortho phosphoric acid were obtained from Sigma-Aldrich as well, The chemicals for derivatisation of the steroid estrogens (dithioerytrol, trimethylsilyl imidazole, and N-methyl-N-tri- fluoroacetamide) were purchased from Sigma-Aldrich, All chemicals were of analytical grade except potassium titanium oxide oxalate dihydrate which was of technical grade, The water used for experiment was wastewater effluent from Ussernd wastewater treatment plant, The effluent was collected 17th and 26th of April together with 14th of May 2007 and 14th of August
The activation of hydrogen peroxide was higher in the tap water (2 1%) than in the wastewater ( 1 1%), which may be due to less shadow effect in the tap water resulting in a larger amount of the light being used for photolysis of H202
Summary
The presence of estrogenic compounds in the environment has in recent years received considerable attention due to their damaging effects on the aquatic life. Behavior, feminization of fish and have even been linked to reduced spem productivity in humans [I], Degradation of estrogenic compounds by UV photolysis and the advanced oxidation process (AOP) UY/ H202 in laboratory setups has been reported in literature [2,3,4], While degradation by these mechanisms are well known, the present literature does not give the data needed for estimating the real cost of treatment if the techniques were applied as a real treatment since they do not consider realistic flow through conditions, radical scavengers and the shadow effect seen in real wastewater, this work has used a setup with realistic dimensions from a UY-treatment plant intended for disinfection of a wastewater treatment plant effluent by medium pressure UV lamps, With this the removal efficiency by photolysis and advanced oxidation (AOP) of estrogenic compounds was investigated in tap water and biologically treated sewage,
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