title: Research on the influence of anaerobic stabilization of various dairy sewage sludge on biodegradation of polycyclic aromatic hydrocarbons PAHs with the use of effective microorganisms.
abstract: Sewage sludge was taken from a dairy WWTP belonging to Mlekovita Cooperative in Wysokie Mazowieckie. There were excess sludge, flotation sludge and a mixture of excess and flotation sludge from pre-treatment of dairy sewage. The initial content of 16 PAHs in excess sludge before fermentation was approximately 689µg·kg-1in dry mass, whereas in post-flotation sludge (which constituted around 30% of raw sludge) it was approximately 95µg·kg-1in dry mass. A mixture of excess and flotation sludge had the content of 497,7µg·kg-1in dry mass. Through comparison of particular hydrocarbons content in raw sewage sludge to the total PAHs content, it was shown that tricyclic compounds, which constituted 46,3% of the PAHs sum (excess sludge), and tetracyclic compounds, which constituted 60,0% of the PAHs sum (flotation sludge), were the dominating fractions. In the sludge subjected to fermentation in reactors with mixed sludge and surplus activated sludge, the general trend of the course of changes in concentrations of PAHs was similar. Both in the sludge inoculated with EM and in that not inoculated with EM, a significant increase in the total PAHs contents was observed in the first fermentation phase (acidic fermentation) after 7 days of the process. Addition of EM into the sludge did not prevent the PAHs release, and therefore higher concentrations of PAHs sum were recorded during the hydrolysis stage than in sludge before fermentation. A decrease in the sum of PAHs was observed after 2 weeks of fermentation in relation to the quantity observed after 1 week of fermentation (except from post-flotation sludge). In the following weeks, there was further decrease in the concentration of the 16 PAHs sum in all sludge types. However, in sludge without EM inoculation, it was lower than in sludge with EM inoculation. The loss of the majority of tested hydrocarbons was reported in the final phase of fermentation.
authors.affiliation: Faculty of Civil and Environmental Engineering, Bialystok University of Technology, 45A Wiejska St., Bialystok 15-351, Poland. Electronic address: d.boruszko@pb.edu.pl.
authors.forename: Dariusz
authors.initials: D
authors.lastname: Boruszko
mesh_terms: D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D019149:Bioreactors; D003612:Dairying; D005285:Fermentation; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism*; D012722:Sewage / Q000382:microbiology*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014873:Water Pollutants / Q000378:metabolism*
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D012722:Sewage; D014873:Water Pollutants
keywords: Dairy sewage sludge; Effective microorganisms bacteria; Polycyclic aromatic hydrocarbons