Resumen de The integration of resource recovery strategies in enhanced biological phosphorus removal
As the global demand for water grows, the amount of wastewater produced and its overall pollution load are continuously increasing worldwide. Therefore, wastewater treatment is becoming a critical point in water management in view of its potential threat to public health as well as environmental problems. In this sense, wastewater treatment plants (WWTPs) are being transformed into water resource recovery facilities (WRRFs) with the aim to achieve a good effluent quality, as well as to recover resources (such as carbon (C), nitrogen (N) and phosphorus (P)), water and energy in a sustainable way.
Enhanced biological phosphorus removal (EBPR) is the most efficient way for P removal. The new paradigm in WWTP evolving to WRRF attempts to change P removal to P recovery from wastewater due to its significance on food production and the limited deposits on our planet. In EBPR-based WWTPs, the most reported location to precipitate/recover P is the digestate from the sludge treatment process. However, it can result in an undesired precipitation in reactors, tubes as well as the instrumentation. As an alternative, anaerobic reactor seems to provide an ideal scenario with high concentration of P: mainstream P-recovery. The integration of A-stage and EBPR (A-stage-EBPR) is promising for simultaneous P and COD removal as well as the energy recovery.
The nature of the carbon source in the influent wastewater plays an important role in the EBPR process. Recent microbiological advances in full-scale WWTPs have shown a high diversity of putative PAO other than Accumulibacter that are selected due the presence of other substances in the real wastewater. More perspectives on the different carbon source utilization need to be improved. Therefore, this thesis reviews the utilization of different carbon sources strategies with particular emphasis on the fermentation products from biosolids as additional carbon source. Secondly, a low concentration of COD is one of the main causes for EBPR failure in full-scale WWTP. The side-stream sludge fermenter (SSSF) is proposed to solve this problem by introducing part of the waste sludge for fermentation to provide additional COD for the mainstream process, which not only saves the cost but also decreases the carbon footprint dispensed with the external carbon addition.
Chapter 4 evaluates different P recovery strategies, especially the start of the art of the novel mainstream P-recovery. In addition, the effect of different carbon source on EBPR performance was comprehensively assessed to go beyond the knowledge of the common carbon sources (acetate and propionate) and specifically to the feasibility of solid waste as carbon source. A continuous pilot-scale A/O system (42 L) was operated in a low SRT and DO for P removal with the minimum of carbon mineralization for energy recovery (Chapter 5). Lastly, the performance of the incorporation of a SSSF into an A2O configuration (S2EBPR) under a low COD influent condition was investigated and the microbial communities were evaluated (Chapter 6).
