Removal of Emerging Contaminants and Estrogenic Activity from Wastewater Treatment Plant Effluent with UV/Chlorine and UV/H2O2 Advanced Oxidation Treatment at Pilot Scale

Abstract

Effluent of a municipal wastewater treatment plant (WWTP) was treated on-site with the UV/chlorine (UV/HOCl) advanced oxidation process (AOP) using a pilot plant equipped with a medium pressure UV lamp with an adjustable performance of up to 1 kW. Results obtained from parallel experiments with the same pilot plant, where the state of the art UV/H2O2 AOP was applied, were compared regarding the removal of emerging contaminants (EC) and the formation of adsorbable organohalogens (AOX). Furthermore, the total estrogenic activity was measured in samples treated with the UV/chlorine AOP. At an energy consumption of 0.4 kWh/m3 (0.4 kW, 1 m3/h) and in a range of oxidant concentrations from 1 to 6 mg/L, the UV/chlorine AOP had a significantly higher EC removal yield than the UV/H2O2 AOP. With free available chlorine concentrations (FAC) in the UV chamber influent of at least 5 mg/L (11 mg/L of dosed Cl2), the total estrogenic activity could be reduced by at least 97%. To achieve a certain concentration of FAC in the UV chamber influent, double to triple the amount of dosed Cl2 was needed, resulting in AOX concentrations of up to 520 µg/L.

State of the Art of UV/Chlorine Advanced Oxidation Processes: Their Mechanism, Byproducts Formation, Process Variation, and Applications

“…WWTP effluent MP-UV/chlorine >97% removal at chlorine dose >5 mg/L [48] improve the toxicity of treated water. Thus, optimization of the operational condition is important for toxicity control by UV/chlorine AOPs.…”

“…The reported contact time of UV irradiation was widely varied from 6 s to 420 min. However, 6-40 s of contact time was applied in the full and pilot scale experiments [47,48,129]. Since the chlorine dose was relatively low, namely ≤10 mg-Cl 2 /L, a short contact time less than 1 min may be enough for UV/ chlorine AOPs.…”

Influence of Ammonium Ions, Organic Load and Flow Rate on the UV/Chlorine AOP Applied to Effluent of a Wastewater Treatment Plant at Pilot Scale

“…In a study with real effluent of a WWTP (continuous operation with 1 m 3 /h, medium pressure UV lamp operated at 0.4–1.0 kW) by Rott et al [ 7 ] it was shown at pilot scale that the UV/chlorine AOP is superior to the UV/H 2 O 2 AOP [ 8 ] in terms of the elimination of ECs, the bacterial count and the total estrogenic activity, as much lower mass concentrations of oxidant are required. All investigations in this study were carried out at NH 4 + -N concentrations <0.1 mg/L.…”

“…A major concern associated with the UV/chlorine AOP is the formation of potentially toxic and lipophilic halogenated degradation by-products such as adsorbable organohalogens (AOX) [ 7 , 9 , 10 ]. Side reactions contribute to the fact that the dosed chlorine immediately reacts to form combined chlorine (CC) or decomposes into chloride.…”

Insight into the Degradation of Two Benzophenone-Type UV Filters by the UV/H2O2 Advanced Oxidation Process

“…The UV/H 2 O 2 system is a type of AOP, in which hydrogen peroxide (H 2 O 2 ) is added in the presence of UV light to generate hydroxyl radicals [16][17][18]. It is found that the UV/H 2 O 2 process can remove a large range of organic pollutants, including cyanobacterial toxins [19], diclofenac [20], amoxicillin [21], and other emerging contaminants [22][23][24].Benzophenone-type UV filters are usually the hardly biodegradable substances [25]. There are over 20 benzophenone-type UV filters, including HBP, BP, benzophenone-2, benzophenone-3 (BP3), benzophenone-4, benzophenone-5, and benzophenone-9.…”