RESUMEN
This work describes a comprehensive assessment of operating parameters of a bench-scale electrodialysis (ED) plant for nutrient concentration from an Anaerobic Membrane BioReactor (AnMBR) effluent. The ED bench-scale plant serves a dual purpose. Firstly, to generate a concentrated stream with a high nutrient content, and secondly, to produce high-quality reclaimed water in the diluted stream, both sourced from real wastewater coming from the effluent of an AnMBR. Two sets of experiments were conducted: 1) short-term experiments to study the effect of some parameters such as the applied current and the type of anionic exchange membrane (AEM), among others, and 2) a long-term experiment to verify the feasibility of the process using the selected parameters. The results showed that ED produced concentrated ammonium and phosphate streams using a 10-cell pair stack with 64 cm2 of unitary effective membrane area, working in galvanostatic mode at 0.24 A, and operating with an Acid-100-OT anionic exchange membrane. Concentrations up to 740 mg/L and 50 mg/L for NH4-N and PO4-P, respectively, were achieved in the concentrated stream along with removal efficiencies of 70% for ammonium and 60% for phosphate in the diluted stream. The average energy consumption was around 0.47 kWh·m-3.
Asunto(s)
Reactores Biológicos , Eliminación de Residuos Líquidos , Aguas Residuales , Aguas Residuales/química , Eliminación de Residuos Líquidos/métodos , Fosfatos/química , Nutrientes , Compuestos de Amonio/química , Anaerobiosis , Diálisis/métodos , Membranas ArtificialesRESUMEN
A pilot-scale microalgae (Chlorella spp.) and primary sludge anaerobic co-digestion (ACoD) plant was run for one year in an anaerobic membrane bioreactor (AnMBR) at 35 °C, 70 d solids retention time and 30 d hydraulic retention time, showing high stability in terms of pH and VFA concentration. The plant achieved a high degree of microalgae and primary sludge substrate degradation, resulting in a methane yield of 370 mLCH4·gVSinf-1. Nutrient-rich effluent streams (685 mgN·L-1 and 145 mgP·L-1 in digestate and 395 mgNH4-N·L-1 and 37 mgPO4-P·L-1 in permeate) were obtained, allowing posterior nutrient recovery. Ammonium was recovered from the permeate as ammonia sulphate through a hydrophobic polypropylene hollow fibre membrane contactor, achieving 99% nitrogen recovery efficiency. However, phosphorus recovery through processes such as struvite precipitation was not applied since only 26% of the phosphate was available in the effluent. Composting process of the digestate coming from the ACoD pilot plant was assessed on laboratory-scale Dewar reactors, as was the conventional sludge compost from an industrial WWTP digestion process, obtaining similar values from both. Sanitised (free of Escherichia coli and Salmonella spp.) and stable compost (respirometric index at 37 °C below 0.5 mgO 2 g organic matter-1·h-1) was obtained from both sludges.