Comparison between the conventional anaerobic digestion of sewage sludge and its combination with a chemical or thermal pre-treatment concerning the removal of pharmaceuticals and personal care products.
Many novel treatment technologies, usually representing a pre-treatment prior to the biological degradation process, have been developed in order to improve the recycling and reuse of sewage sludge. Among all the methods available, a chemical (alkaline) and a thermal treatment have been considered in this study. The behaviour of 13 substances belonging to different therapeutic classes (musks, tranquillisers, antiepileptic, anti-inflammatories, antibiotics, X-ray contrast media and estrogens) has been studied during the anaerobic digestion of sewage sludge combined with these pre-treatments (advanced operation) in comparison with the conventional process. Two parameters have been analysed: the temperature (mesophilic and thermophilic conditions) and the sludge retention time. While organic matter solubilization was higher with the alkaline process (55-80%), no difference between both pre-treatments was observed concerning volatile solids solubilization (up to 20%). The removal efficiencies of solids and organic matter during anaerobic digestion ranged from 40-70% and 45-75%, respectively. The higher removal efficiencies of pharmaceuticals and personal care products were achieved for the antibiotics, Naproxen and the natural estrogens (>80%). For the other compounds, the values were in the range 20-70%, except for Carbamazepine, which was not removed at any condition tested.
Carballa
M
M
Department of Chemical Engineering, University of Santiago de Compostela, Ria Lope Gomez de Marzoa, s/n. 15782 Santiago de Compostela, Spain. mcarbala@usc.es
Omil
F
F
Alder
A C
AC
Lema
J M
JM
D000468:Alkalies; D000693:Anaerobiosis; D001421:Bacteria, Anaerobic; D001673:Biodegradation, Environmental; D006795:Household Products; D004364:Pharmaceutical Preparations / Q000378:metabolism; D012722:Sewage / Q000382:microbiology*; D012995:Solubility; D013696:Temperature; D018505:Waste Management / Q000379:methods*
D000468:Alkalies; D004364:Pharmaceutical Preparations; D012722:Sewage