RESUMEN
The integration of high-rate activated sludge (HRAS), an effective carbon redirection technology, with partial nitritation/anammox (PN/A) is a novel AB treatment process for municipal wastewater. In this study, an airlift HRAS reactor was operated in the continuous inflow mode for 200 d at a wastewater treatment plant. The balance between potential PN/A system stability and peak HRAS performance under decreasing hydraulic retention time (HRT) was optimized. Energy consumption and recovery and CO2 emissions were calculated. The results showed that the optimal HRT suitable with the PN/A process was 3 h, achieving 2-3 g/L mixed liquor volatile suspended solid, 67.8 % chemical oxygen demand (COD) recovery, 81 % total COD removal efficiency, 2.27 ± 1.03 g COD/L/d organic loading rate, 62 % aeration reduction, and 0.24 kWh/m3 power recovery potential. Such findings hold practical value and contribute to the development of the optimal AB process capable of achieving energy autonomy and carbon neutrality.
Asunto(s)
Reactores Biológicos , Aguas del Alcantarillado , Purificación del Agua , Purificación del Agua/métodos , Aguas Residuales/química , Análisis de la Demanda Biológica de Oxígeno , Eliminación de Residuos Líquidos/métodos , Factores de Tiempo , Nitrógeno , Dióxido de Carbono , Oxidación-Reducción , CiudadesRESUMEN
The aim of this work was to study the key parameters affecting fermentation of high rate activated A-sludge to carboxylates, including pH, temperature, inoculum, sludge composition and iron content. The maximum volatile fatty acids production was 141mgCg(-1) VSSfed, at pH 7. Subsequently the potential for carboxylate and methane production for A-sludge from four different plants at pH 7 and 35°C were compared. Initial BOD of the sludge appeared to be key determining carboxylate yield from A-sludge. Whereas methanogenesis could be correlated linearly to the quantity of ferric used for coagulation, fermentation did not show a dependency on iron presence. This difference may enable a strategy whereby A-stage sludge is separated to achieve fermentation, and iron dosing for phosphate removal is only implemented at the B-stage.
Asunto(s)
Reactores Biológicos , Ácidos Carboxílicos , Ácidos Grasos Volátiles , Metano , Aguas del Alcantarillado/química , Ácidos Carboxílicos/química , Ácidos Carboxílicos/metabolismo , Ácidos Grasos Volátiles/química , Ácidos Grasos Volátiles/metabolismo , Fermentación , Metano/química , Metano/metabolismoRESUMEN
This manuscript presents a comparison of the A-stage and B-stage sludges in terms of anaerobic biodegradability and low molecular weight compounds present in the supernatant using Gas Chromatography-Mass Spectrometry (GC-MS). The GC-MS analysis of A-stage and B-stage supernatants identified respectively 43 and 19 organic compounds consisting mainly of aromatics (27.9% and 21%), alcohols (25.6% and 15%) and acids (30.2% and 15%). The methane potential was found to be 349±1 mL CH4/g VS and 238±12 mL CH4/g VS, respectively. After anaerobic digestion of these sludges, a greater proportion of aromatics (42% and 58%) and a lower proportion of acids (10% and 10%) and alcohols (16% and 10%) was observed.