A new decentralized biological treatment process based on activated carbon targeting organic micropollutant removal from hospital wastewaters

Abstract

Although hospital wastewaters (HWWs) are usually discharged in urban sewage systems, their separate treatment has several benefits, such as the specific treatment of potential toxics as well as avoidance of further dilutions. In this work, an integrated industrial pilot plant (2200 L) corresponding to the technology SeMPAC is proposed and validated for such purpose. The process consists of a sequential batch reactor (SBR) connected to an external submerged microfiltration membrane, in which powdered activated carbon (PAC) is directly added into the biological reactor to enhance the removal of the organic micropollutants (OMPs). The combination of different redox conditions in the SBR, as well as the operation at long sludge retention times (SRTs) and high biomass concentrations favored OMP biotransformation in the SBR, being their final removal efficiencies enhanced clearly after PAC addition, especially for the recalcitrant compounds. A periodical renewal of the adsorbent is necessary to overcome its gradual saturation. The main operational conditions were influenced by (i) the recalcitrant OMP carbamazepine, which defines the PAC dosage; (ii) the easily degradable OMP ibuprofen, which can be used to optimize the duration of the aerobic cycle; and (iii) the denitrification efficiency, which defines the correct time length of the anoxic period.

Hospital wastewater treatment and the role of membrane filtration – removal of micropollutants and pathogens: A review

“…With an increase in PAC concentration, even hydrophilic substances, such as contrast media, are removed to a high degree. The direct dosage of PAC to the biological stage of a MBR was investigated by Alvarino et al (2020). In this study, a one-time dose of a PAC suspension was performed to establish a concentration of 1 g PAC /L and elimination efficiencies of 5 micropollutants were evaluated.…”

Trends, new insights and perspectives in the treatment of hospital effluents

“…Some interesting investigations have dealt with enhanced biological processes based on the combination of MBRs coupled with granular or powder activated carbons (GAC or PAC), or characterised by modified membranes, or operating under specific and controlled conditions. The Spanish group at the University of Santiago of Compostela ( 35 ) applied their patented system SemPAC© to hospital effluent and evaluated its performance with regard to 5 CECs: ibuprofen, 17α-ethynylestradiol, diclofenac, carbamazepine, and trimethroprim. It consists of a sequential batch reactor followed by an external submerged microfiltration membrane tank where PAC is added to enhance the sorption of residues of CECs.…”

Removal of micropollutants from municipal wastewater using different types of activated carbons

“…The disadvantage of using coagulants is their cost and high sludge production that can be overcome by using them in a small amount or along with flocculants (Alvarino et al, 2018a).…”