Fate of Alkylphenolic Compounds during Activated Sludge Treatment: Impact of Loading and Organic Composition

Abstract

The impact of loading and organic composition on the fate of alkylphenolic compounds in the activated sludge plant (ASP) has been studied. Three ASP designs comprising carbonaceous, carbonaceous/nitrification, and carbonaceous/nitrification/denitrification treatment were examined to demonstrate the impact of increasing levels of process complexity and to incorporate a spectrum of loading conditions. Based on mass balance, overall biodegradation efficiencies for nonylphenol ethoxylates (NPEOs), short chain carboxylates (NP(1-3)EC) and nonylphenol (NP) were 37%, 59%, and 27% for the carbonaceous, carbonaceous/nitrification, and carbonaceous/nitrification/denitrification ASP, respectively. The presence of a rich community of ammonia oxidizing bacteria does not necessarily facilitate effective alkylphenolic compound degradation. However, a clear correlation between alkylphenolic compound loading and long chain ethoxylate compound biodegradation was determined at the three ASPs, indicating that at higher initial alkylphenolic compound concentrations (or load), greater ethoxylate biotransformation can occur. In addition, the impact of settled sewage organic composition on alkylphenolic compound removal was evaluated. A correlation between the ratio of chemical oxygen demand (COD) to alkylphenolic compound concentration and biomass activity was determined, demonstrating the inhibiting effect of bulk organic matter on alkylphenol polyethoxylate transformation activity. At all three ASPs the biodegradation pathway proposed involves the preferential biodegradation of the amphiphilic ethoxylated compounds, after which the preferential attack of the lipophilic akylphenol moiety occurs. The extent of ethoxylate biodegradation is driven by the initial alkylphenolic compound concentration and the proportion of COD constituted by the alkylphenol polyethoxylates (APEOs) and their metabolites relative to the bulk organic concentration of the sewage composed of proteins, acids, fats, and polysaccharides. Secondary effluents from this study are characterized by low bulk organic concentrations and comparatively high micropollutant concentrations. Based on the biodegradation mechanism proposed in this study, application of high rate tertiary biological treatment processes to secondary effluents characterized by low bulk organic concentrations and comparatively high APEO concentrations is predicted to provide a sustainable solution to micropollutant removal.

Behaviour of pharmaceuticals and endocrine disrupting chemicals in simplified sewage treatment systems

“…In order to compare the pharmaceutical and endocrine removal efficiencies observed in the simplified treatment systems studied here with those shown by the activated sludge (AS) systems, data gathered from different studies and research groups (Carballa et al, 2004;Clara et al, 2005aClara et al, , 2005bJoss et al, 2005;Vieno et al, 2005;Batt et al, 2006;Bernhard et al, 2006;Lishman et al, 2006;Nakada et al, 2006;Göbel et al, 2007;Radjenovic et al, 2007;Tan et al, 2007;Gulkowska et al, 2008;Pothitou and Voutsa, 2008;Ying et al, 2008;Janex-Habib et al, 2009;Kasprzyk-Hordern et al, 2009;Radjenovic et al, 2009;Choubert et al, 2011;Jelic et al, 2011;McAdam et al, 2011;Pedrouzo et al, 2011;Zhang et al, 2011) was compiled and presented in Fig. 5.…”

The effectiveness of anaerobic digestion in removing estrogens and nonylphenol ethoxylates

“…In addition these digesters had the lowest percentage removal of E3 observed (Table 2) where only 17% or 4% was removed in comparison to>43% at mesophilic conditions which implies that E1 had also been converted to E3. possibly due to some operational alterations at the works affecting the solids and/or hydraulic retention times or food to micro-organism ratio in the activated sludge plant which can effect NPEO breakdown [38].…”

Distribution and Removal of Nonylphenol Ethoxylates and Nonylphenol from Textile Wastewater—A Comparison of a Cotton and a Synthetic Fiber Factory in Vietnam

“…In a strong agreement, Vader et al [130] suggested that high removal of estrogens (in the range of 79-95%) was mainly attributed to the nitrifying stage. Findings of McAdam et al [131] also showed the same patterns where nitrifying appeared in higher de-ethoxylation of long-chain nonylphenolic compounds (NP [5][6][7][8][9][10][11][12] EO), at approximately 92%, and partial removal of NP, whereas non-nitrifying process yielded poorer de-ethoxylation and an accumulation of NP.…”