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

• Published in: Water science and technology 2006-01, Vol.53 (8), p.109-117
• Main Authors: Carballa, M, Omil, F, Alder, A C, Lema, J M
• Format: Article
• Language: English
• Subjects: Alkalies; Anaerobic digestion; Anaerobic treatment; Anaerobiosis; Antibiotics; Bacteria, Anaerobic; Biodegradation; Biodegradation, Environmental; Biological activity; Carbamazepine; Consumer products; Contrast media; Digestion; Drugs; Estrogens; Heat treatment; Household Products; Naproxen; Organic matter; Personal grooming; Pharmaceutical Preparations - metabolism; Pharmaceuticals; Pretreatment; Process parameters; Removal; Retention time; Sewage; Sewage - microbiology; Sewage sludge; Sludge; Sludge digestion; Solubility; Solubilization; Temperature; Volatile solids; Waste Management - methods
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2006.241

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.