An Assessment of Mass Flows, Removal and Environmental Emissions of Bisphenols in a Sequencing Batch Reactor Wastewater Treatment Plant.

This study analyzed 16 bisphenols (BPs) in wastewater and sludge samples collected from different stages at a municipal wastewater treatment plant based on sequencing batch reactor technology. It also describes developing an analytical method for determining BPs in the solid phase of activated sludge based on solid-phase extraction and gas chromatography-mass spectrometry. Obtained concentrations are converted into mass flows, and the biodegradation of BPs and adsorption to primary and secondary sludge are determined. Ten of the sixteen BPs were present in the influent with concentrations up to 434 ng L-1 (BPS). Only five BPs with concentrations up to 79 ng L-1 (BPA) were determined in the plant effluent, accounting for 8 % of the total BPs determined in the influent. Eleven per cent of the total BPs were adsorbed on primary and secondary sludge. Overall, BPs biodegradation efficiency was 81%. The highest daily emissions via effluent release (1.48 g day-1) and sludge disposal (4.63 g day-1) were for BPA, while total emissions reached 2 g day-1 via effluent and 6 g day-1 via sludge disposal. The data show that the concentrations of BPs in sludge are not negligible, and their environmental emissions should be monitored and further studied.

Performance evaluation of a novel pilot-scale pinned disc rotating generator of hydrodynamic cavitation.

This study investigates hydrodynamic performance of a novel pinned disc rotating generator of hydrodynamic cavitation in comparison with a serrated disc variant on a pilot-scale. Experimental results show that at a given rotational speed and liquid flow rate, the pinned disc generates more intense cavitation (i.e. lower cavitation number, higher volume fraction of vapor and higher amplitude of pressure fluctuations) than the serrated disc, while also consuming less energy per liquid pass (i.e., higher flow rate and pumping pressure difference of water at similar power consumption). Additionally, mechanical and chemical wastewater treatment performance of the novel cavitator was evaluated on an 800 L influent sample from a wastewater treatment plant. Mechanical effects resulted in a reduction of average particle size from 148 to 38 µm and increase of specific surface area, while the oxidation potential was confirmed by reduction of COD, TOC, and BOD up to 27, 23 and 30% in 60 cavitation passes, respectively. At optimal operating conditions and 30 cavitation passes, pinned disc cavitator had a 310% higher COD removal capacity while consuming 65% less energy per kg of COD removed than the serrated disc cavitator. Furthermore, the specific COD-reduction energy consumption of the pinned disc cavitator on the pilot scale is comparable to the best cases of lab-scale orifice and venturi devices operating at much lower wastewater processing capacity.