Sustainable strategy for wastewater treatment and production of bioproducts using microalgae-bacteria biotechnology

• Grant number: 24/09344-9
• Support Opportunities: Regular Research Grants
• Start date: November 01, 2024
• End date: October 31, 2026
• Field of knowledge: Engineering - Sanitary Engineering - Water Supply and Wastewater Treatment
• Principal Investigator: Gustavo Henrique Ribeiro da Silva
• Grantee: Gustavo Henrique Ribeiro da Silva
• Host Institution: Faculdade de Engenharia (FE). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil
• Associated researchers: Caroline Moço Erba Pompei ; Daniel Rodrigues Cardoso ; Graziele Ruas Lagôas da Silva ; Inês Cechin ; Juliane Silberschmidt Freitas ; Raul Muñoz Torre ; Rodrigo Braga Moruzzi ; Tânia Vasconcelos Fernandes

Abstract

The sanitation systems currently in use, despite significant progress, especially in sewage treatment, result in the undervaluation of waste, loss of nutrients, improper water use, and release of residual pollutant loads into the environment. It is known that the agricultural sector relies on the use of synthetic fertilizers and herbicides for global food production; however, the sector has come under great pressure due to water scarcity, low nitrogen (N) utilization by crops, future phosphorus (P) scarcity, and pollution caused by conventional herbicides. In addition to this, the new concept of sewage treatment aims at maximizing energy and resource recovery from wastewater, minimizing the use of potable water, and reducing micropollutant emissions. In this context, the present project aims to develop and refine technologies for sanitary sewage treatment (ES) together with agricultural sewage from pig farming and dairy cattle farming (EAgr.), enabling the transition to a circular economy, and bringing environmental, economic, and social benefits. For this purpose, a treatment process consisting of an anaerobic system followed by photobioreactors (FBRs) for the cultivation of a consortium of native microalgae-bacteria (activated sludge) operated in semi-continuous and continuous modes to treat ES + EAgr will be evaluated. The quality of the final effluent and algal biomass for bioproduct production will also be monitored. Microalgal biomass separation will also be investigated through coagulation/flocculation and sedimentation/dissolved air flotation, monitored by non-intrusive imaging techniques and image velocimetry to determine aggregate attributes and their performance in separation. The resulting algal biomass will be evaluated for its quality as a nutrient and/or substrate for agricultural bio-inputs, whether bioherbicides or growth inducers. Algal biomass, in addition to the final effluent, will be evaluated for its quality as a biofertilizer and viability in corn (Zea mays) cultivation. Furthermore, the potential for recovering value-added bioproducts such as exopolymers behaving like alginate (Alginate-like exopolymer, ALE) will be assessed. The removal of metals and human pathogens will also be evaluated throughout the system to ensure suitable final effluent and algal biomass quality for reuse. With the proposed treatment system, nutrient, energy, and water cycles will be closed sustainably for the treatment of ES and a portion of anaerobically pre-treated EAgr. sewage, while producing valuable algal biomass products. (AU)