In this study, polyhydroxyalkanoates (PHAs) production integrated with the via-nitrite nitrogen removal from anaerobic reject water was investigated at pilot scale under long term period. The pilot plant was located in Carbonera wastewater treatment plant (WWTP) (Treviso, Italy) and comprised the following units: i) rotating belt dynamic filter (RBDF) for the recovery of cellulosic primary sludge (CPS); ii) fermentation unit for the production of volatile fatty acids (VFAs); iii) ultrafiltration unit (UF) for solid/liquid separation of the fermented sludge; iv) nitritation sequencing batch reactor (N-SBR) for the oxidation of ammonia to nitrite; v) selection SBR (S-SBR) where aerobic-feast and anoxic-famine conditions were established to select PHA-accumulating biomass and vi) an accumulation SBR (A-SBR) were intracellular PHA content was maximized through the feed-on-demand strategy. Results showed that around 80% of the influent ammonia was efficiently removed by the system when both N-SBR and S-SBR operated with volumetric nitrogen loading rate (vNLR) of 1.64-1.72 kgN/m³ d and 0.60-0.63 kgN/m³ d. Accumulation tests showed PHA yields ranging between 0.58 and 0.61 g CODPHA/g CODVFA, indicating an effective selection strategy. The overall mass balance assessment demonstrated that around 0.32 grams of COD per gram of COD treated can be recovered as bio-based products. The integration of nitrogen removal and PHA production in the sidestream resulted in a methane recovery up to 4.0 m³CH4/PE y and a maximal PHA production of 1.2 kgPHA/PE y with a potential revenue for the WWTP up to 6.5 €/PE y.
Long-term validation of polyhydroxyalkanoates production potential from the sidestream of municipal wastewater treatment plant at pilot scale
Vincenzo Conca;Nicola Frison
Supervision
;
2020-01-01
Abstract
In this study, polyhydroxyalkanoates (PHAs) production integrated with the via-nitrite nitrogen removal from anaerobic reject water was investigated at pilot scale under long term period. The pilot plant was located in Carbonera wastewater treatment plant (WWTP) (Treviso, Italy) and comprised the following units: i) rotating belt dynamic filter (RBDF) for the recovery of cellulosic primary sludge (CPS); ii) fermentation unit for the production of volatile fatty acids (VFAs); iii) ultrafiltration unit (UF) for solid/liquid separation of the fermented sludge; iv) nitritation sequencing batch reactor (N-SBR) for the oxidation of ammonia to nitrite; v) selection SBR (S-SBR) where aerobic-feast and anoxic-famine conditions were established to select PHA-accumulating biomass and vi) an accumulation SBR (A-SBR) were intracellular PHA content was maximized through the feed-on-demand strategy. Results showed that around 80% of the influent ammonia was efficiently removed by the system when both N-SBR and S-SBR operated with volumetric nitrogen loading rate (vNLR) of 1.64-1.72 kgN/m³ d and 0.60-0.63 kgN/m³ d. Accumulation tests showed PHA yields ranging between 0.58 and 0.61 g CODPHA/g CODVFA, indicating an effective selection strategy. The overall mass balance assessment demonstrated that around 0.32 grams of COD per gram of COD treated can be recovered as bio-based products. The integration of nitrogen removal and PHA production in the sidestream resulted in a methane recovery up to 4.0 m³CH4/PE y and a maximal PHA production of 1.2 kgPHA/PE y with a potential revenue for the WWTP up to 6.5 €/PE y.
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