Sewage sludge composting and fate of pharmaceutical residues –recent studies in Estonia

E. Haiba¹, L. Nei¹*, M. Ivask¹, J. Peda¹, J. Järvis¹, M. Lillenberg², K. Kipper³ and K. Herodes³

¹Tartu College, Tallinn University of Technology, Puiestee 78, EE51008 Tartu, Estonia
²Estonian University of Life Sciences, Kreutzwaldi 58A, EE51014 Tartu, Estonia
³Institute of Chemistry, University of Tartu, Ravila 14A, EE51010 Tartu, Estonia *Correspondence: lembit.nei@ttu.ee

Abstract:

This review is to reflect the work addressed to the application of biosolids and especially sewage sludge as a resource in composting. A considerable drop in the use of P fertilisers can be followed since early 1990s. Due to this fact crop production in Estonia takes place at the expense of soil phosphorous (P) resources. One of the ways of increasing the fertility of agricultural lands is to use nutrient-rich sewage sludge. Unfortunately, this may cause several undesired consequences due to biological and chemical contaminants. The presence of some widely used pharmaceuticals, as ciprofloxacin (CIP), norfloxacin (NOR), ofloxacin (OFL), sulfadimethoxine (SDM) and sulfamethoxazole (SMX), was evident in sewage sludge of the two Estonian largest cities, Tartu and Tallinn. The concentrations of pharmaceuticals decreased after sewage sludge digestion and composting, but they were still present in detectable amounts. Sewage sludge co-composting experiments with sawdust, peat and straw showed the degradation of fluoroquinolones (FQ) and sulfonamides (SA). Additions of sawdust clearly speeded up this process, whereas the mixtures with peat and straw performed lower abilities to decompose pharmaceutical residues. Novel methodologies were developed and experiments conducted to study the potential accumulation of fluoroquinolones FQs and SAs by food plants. Due to the low adsorption of SAs on soil particles they are ‘free’ to migrate into plants. Different behaviour is characteristic to FQs as they are accumulated in sludge. Recent years have also shown progress in vermicomposting work and in using compost in afforestation.

Key words:

composting technologies, fertilizers, pharmaceuticals, plant uptake, sewage sludge, vermicomposting

Enrofloxacin and Ciprofloxacin Uptake by Plants from Soil

M. Lillenberg¹, S. V. Litvin², L. Nei², M. Roasto¹ and K. Sepp³

¹Department of Food Science and Hygiene, Estonian University of Life Sciences,
Kreutzwaldi 58A, 51014 Tartu, Estonia
²Department of Environmental Protection, Tartu College of Tallinn University of
Technology, Puiestee 78, 51008 Tartu, Estonia, e-mail: lembit.nei@ttu.ee
³Institute of Agricultural and Environmental Sciences, Estonian University of Life
Sciences, Kreutzwaldi 64, 51014 Tartu, Estonia

Abstract:

Very small amounts of pharmaceuticals present in everyday food may generate
strains of resistant microorganisms in human and animal organisms. This study involves the
uptake and accumulation of some widely used fluoroquinolones – enrofloxacin and
ciprofloxacin – by plants cultivated in soil augmented with drugs using the microbiological agar
diffusion method. Bacillus subtilis was used as the test bacterium. The three plants chosen for
the experiment were lettuce (Lactuca sativa), common barley (Hordeum vulgare L.) and
cucumber (Cucumis sativus L.), which were cultivated in a laboratory in soils mixed with enroor
ciprofloxacin at nominal concentrations of 500, 200, 50 and 10 µg/g. The concentrations of
fluoroquinolones remained unchanged in the soil during the experiment. The presence of
enrofloxacin was detected in all plants grown at enrofloxacin concentrations of 500, 200 and 50
µg/g. The presence of ciprofloxacin was only detected in barley and cucumber grown in soil
with a base concentration of 500 µg/g. In lettuce, which had a longer vegetation period, the
presence of ciprofloxacin was detected at all concentrations. The content of ciprofloxacin in the
lettuce was 44 µg/g at a soil concentration of 10 µg/g: fluoroquinolones accumulate in a plant
during the vegetation period.

Key words: