Influence of different bulking agents on the disappearance of polycyclic aromatic hydrocarbons (PAHs) during sewage sludge composting

Abstract

In order to improve properties of compost produced from sewage sludge, a wide range of additives is used. The aim of the present study has been to determine the influence of fly ash and sawdust on the range of losses of 16 PAHs (US EPA). Composting was carried out in containers in which there was sewage sludge (100%), sewage sludge with fly ash added (20 or 30% w/w) and sewage sludge with sawdust added (30% w/w). Composting was carried out for 353 days. Then the compost obtained was stored for another 300 days. The content of 16 PAHs was determined using the HPLC-UV method.After composting, in all the experimental treatments, ie, with sludge alone, and with the additions of 20% and 30% fly ash, and sawdust, decreases in the total PAH load of 87.5, 83.4, 82.9 and 88.1% respectively, were found. The content of the total PAH load was mainly determined by 3-ring compounds. In the case of these last PAHs the highest level of their disappearance (>90%) was noted after composting. In all composts obtained, the content of PAHs was within allowable limits for biosolids that can be used for agricultural purposes.A significant lowering of total concentration of the 16 PAHs after storage period was noted only in the experimental variant with 20% of fly ash. However, the process of composts storage influenced individual PAHs.

Effect of Composting on Polycyclic Aromatic Hydrocarbons Removal in Sewage Sludge

“…A clean-up and separation chromatography column was used to remove lipids and sulphur from extracts. The column was packed with layers of silica gel (200-300 mesh), neutral aluminium oxide (100-200 mesh), anhydrous sodium sulphate and activated copper powder (Berset and Holzer 1999;Oleszczuk 2006b;Manoli and Samara 1999). In order to remove hydrophobic impurities, the column was washed three times using 10 ml hexane in each washes and subsequently eluted three times with 15 ml hexanedichloromethane (3:7) in each elution step.…”

Trace organic contaminants in biosolids: Impact of conventional wastewater and sludge processing technologies and emerging alternatives

“…Significant TrOC removal (e.g. >60%) of linear alkyl sulphonate [132,133], nonylphenol [68,[130][131][132], polycyclic aromatic hydrocarbons [129], and certain pharmaceuticals (e.g. ciprofloxacin and norfloxacin) [40] have been reported depending on composting conditions (Table 1).…”

“…Bulking agents are carbon-based materials added to the compost to provide structure and regulate odour, but they can adsorb organic compounds and therefore limit the bioavailability of TrOCs. Oleszczuk [129] found that the addition of 20-30% fly ash to the compost decreased the biodegradation of PAHs from 87.5…”

The Toxicity of Two Types of Sewage Sludge From Wastewater Treatment Plant for Plants in Czech Republic

“…Studies carried out so far [Smith et al 2001, Oleszczuk 2006a showed that sewage sludge in the conditions of its land application can be a significant source of a lot of undesirable substances in soil and plants. Heavy metals and organic compounds are among the "most popular" pollutants present in sewage sludge [Stevens et al 2003, Oleszczuk 2006b]. The influence of pollutants contained in sewage sludges on their toxicity has not, so far, been demonstrated un-equivocally [Oleszczuk et al 2011].…”