title: Leaching of nitrogen, phosphorus, TOC and COD from the biosolids of the municipal wastewater treatment plant of Thessaloniki.
abstract: Biosolids from the WWTP of Thessaloniki were examined for the leaching of phosphorus (as PO4(3-) -P), nitrogen (as NH4+ (-N) and NO3- (-N)), and organic matter (as TOC and COD), using two tests: (1) a pH static leaching test and (2) a characterization test, relating contaminant release to the liquid to solid (L/S) ratio. Moreover, a Microtox toxicity test was conducted, to examine the pH dependency of the toxicity of the sludge leachate on the Vibrio fischeri bacterium. Maximum phosphorus release was observed at pH < 3 and at pH > 10. Ammonium nitrogen exhibited maximum leachability at near neutral pH conditions, while nitrate nitrogen exhibited a mild increase in the leachate, as the leachant pH increased from 2 to 12. Both TOC and COD exhibited an increase in the leachate concentration, as the leachant pH was increased from 2 to 12. Ecotoxicological analysis showed that maximum toxicity occurred at very low and very high pH-conditions. As liquid-to-solid ratio increased, the leachate concentration (in mg/l) of all parameters studied decreased. The results of the study were used to conduct a release assessment estimate for the case of Thessaloniki.
authors.affiliation: Environmental Pollution Control Laboratory, Department of Chemistry, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece.
authors.forename: V
authors.initials: V
authors.lastname: Batziaka
authors.forename: K
authors.initials: K
authors.lastname: Fytianos
authors.forename: E
authors.initials: E
authors.lastname: Voudrias
mesh_terms: D048908:Aliivibrio fischeri / Q000187:drug effects; D006115:Greece; D009584:Nitrogen / Q000032:analysis* / Q000302:isolation & purification; D010100:Oxygen / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis* / Q000302:isolation & purification; D012722:Sewage; D014873:Water Pollutants / Q000032:analysis* / Q000302:isolation & purification / Q000633:toxicity
chemical_list: D012722:Sewage; D014873:Water Pollutants; D010758:Phosphorus; D009584:Nitrogen; D010100:Oxygen