Behavior of Micropollutants in Polishing Units that Combine Sorption and Biodegradation Mechanisms to Improve the Quality of Activated Sludge Effluent

Abstract

The current study evaluated the removal of six micro pollutants (Estrone (E1); 17β-estradiol (E2); 17α-ethynylestradiol (EE2); Ibuprofen (IBP), Diclofenac (DCF) and Paracetamol (PCT)) from the final effluent of an activated sludge domestic sewage treatment plant using polishing filters. Four polishing filters were assembled as columns and filled with a mixture of sand and vermiculite, sand and charcoal, sand and granulated activated carbon (9:1 by volume) and sand only. The column filters were placed near the outlet of a full-scale activated sludge treatment plant and were fed with a treated effluent containing from 4.71 ng/L to 28.93 ng/L of the target compounds at a hydraulic loading rate (HLR) of 50 m³.m -2 .d -1 . Samples were collected periodically from the influent (biologically treated sewage) and effluent of the four columns and analysed for estrogens, anti-inflammatories and analgesic compounds. Liquid samples were submitted to a solid phase extraction (SPE) and analysed by gas chromatography coupled with mass spectrometry after their derivatization. Among the compounds found, Diclofenac was distinguished by the high ocurrence of detection in the samples (85%) and higher mean concentration (~17ng.L -1 ). High removal efficiency (>90%) of the estrogens was observed in the polishing systems studied, whilst for the other targets, the removal efficiency varied from 10% to 30%. Observe that the compounds concentrations were low, maybe this fact is because the rainfall in the collect period.

Can high rate algal ponds be used as post-treatment of UASB reactors to remove micropollutants?

“…Removal rates obtained for the five PhACs in the anaerobic phase of the treatment were lower than 30%, which agrees with previous results (Brandt et al, 2013;de Graaff et al, 2011;Reyes-Contreras et al, 2011). PhACs have pK a values between 4 and 5 and log K ow between 3 and 4, (with the exception of paracetamol, pK a = 9.8 and log K ow = 0.46) (Castro, 2017;Castro et al, 2018). Therefore, sorption could be the main removal mechanism and the ionization of these PhACs may be the factor that causes these compounds to remain in the liquid phase.…”

17α-Ethinylestradiol (EE2): concentrations in the environment and methods for wastewater treatment – an update

“… 52 The removal efficiency for granular activated carbon was over 99% after 30 d at an initial concentration of 10 μg L −1 . These results are well comparable to the results achieved by de Castro et al 51 The two teams used different experimental setups and were able to obtain satisfying results with removals of close to 100%.…”

“…The initial mean concentration for EE2 was approximately 10 ng L −1 and a removal efficiency of over 99% was achieved for every experimental setup. 51 This study connects to earlier investigations by Snyder et al , who had conducted experiments on the removal efficiency of membranes and activated carbon for pharmaceuticals and endocrine disruptors. EE2 was one of the investigated substances.…”

Valorisation of agricultural waste derived biochars in aquaculture to remove organic micropollutants from water – experimental study and molecular dynamics simulations

“…This observation is significant because aquaculture farmers will only periodically top up their ponds with canal water to compensate for evaporative water losses, mainly during the dry season ( Mrozik et al, 2019 ). Retention of micropollutants in the filter bed during these sporadic loadings with canal water then provides the opportunity for subsequent micropollutant biodegradation in the filter bed during the much longer interim periods when there is no exchange of water between the canal and the pond ( de Castro et al, 2018 ). The pilot-scale outcome can help with the design of optimized water exchange strategies which will depend on site-specific settings i.e.…”