Factors affecting the removal of organic micropollutants from wastewater in conventional treatment plants (CTP) and membrane bioreactors (MBR)

Abstract

As a consequence of insufficient removal during treatment of wastewater released from industry and households, different classes of organic micropollutants are nowadays detected in surface and drinking water. Among these micropollutants, bioactive substances, e.g., endocrine disrupting compounds and pharmaceuticals, have been incriminated in negative effects on living organisms in aquatic biotope. Much research was done in the last years on the fate and removal of those compounds from wastewater. An important point it is to understand the role of applied treatment conditions (sludge retention time (SRT), biomass concentration, temperature, pH value, dominant class of micropollutants, etc.) for the efficiency of conventional treatment plants (CTP) and membrane bioreactors (MBR) concerning the removal of micropollutants such as pharmaceuticals, steroid- and xeno-estrogens. Nevertheless, the removal rates differ even from one compound to the other and are related to the ph ysico-chemical characteristics of the xenobiotics

Coupling granular activated carbon adsorption with membrane bioreactor treatment for trace organic contaminant removal: Breakthrough behaviour of persistent and hydrophilic compounds

“…In fact, significant variations in the removal of hydrophilic and biologically persistent compounds in the same study and between different studies have been reported in the literature for both MBR and CAS (Clara et al, 2005;Nakada et al, 2006;Tadkaew et al, 2011). Our results regarding the persistence of the above-mentioned six compounds are consistent with the results obtained from our own preliminary study (Nguyen et al, 2012) and other available studies (Clara et al, 2005;Joss et al, 2005;Urase et al, 2005;Nakada et al, 2006;Kimura et al, 2007;Cirja et al, 2008). Similarly, the presence of the strong electron-donating functional groups (such as hydroxyl and aliphatic) and/or absence of strong electron-withdrawing groups appear to be the reason of the high removal of the other hydrophilic compounds such as acetaminophen and salicylic acid , ibuprofen (Clara et al, 2005;Joss et al, 2005) and estriol (Urase et al, 2005;Hai et al, 2011) (Clara et al, 2005;Joss et al, 2005;Urase et al, 2005;Hai et al, 2011).…”

“…However, MLVSS/MLSS ratio, supernatant turbidity, SVI and SOUR values were all stable throughout the study (Supplementary Data Table S5), suggesting continuous biological stability. Notably, at a significantly long sludge retention time, as applied in this study, slow-growing microorganisms, which may achieve efficient degradation of trace organic contaminants, can have the opportunity to proliferate in the bioreactor (Cirja et al, 2008). Performance of the MBR with respect to the removal of TOC and TN was stable during the entire study (Supplementary Data Table S5).…”

Ecotoxicological aspects related to the presence of pharmaceuticals in the aquatic environment

“…Depending both on the particular technology resorted to and the active substance properties they may undergo: (i) degradation (mineralization) to low molecular weight compounds (e.g. CO2 and water); (ii) entrapment by suspended solids; (iii) discharge of the parent compound through chemical cleavage of the respective con-jugate forms and (iv) conversion to a more hydrophilic, persistent form which will short-circuit the treatment process [39,41,56,57]. Thus, in hospitals use of specific antibiotics, antineoplasic or diag-nostic agents subsequently requires a sewage treatment process more embracing and directed to these kind of drugs, which are only used in hospitals [35,58], and that must be different to the more specific procedure adopted at STPs receiving industrial discharges from drug manufactures [47][48][49]59].…”

Removal of carbamazepine and sulfamethoxazole by MBR under anoxic and aerobic conditions

“…In the quest to enhance micropollutant removal, to date the effects of operational parameters such as HRT, SRT, pH and temperature on the removal efficiency of micropollutants by MBR treatment have been extensively studied (Cirja et al, 2008). However, as a notable omission, little is known about the effects of dissolved oxygen (DO) concentration on the removal of micropollutants by MBR treatment.…”