Carla Mae Pausta
Academic and research departments
Centre for Environmental Health and Engineering, Department of Civil and Environmental Engineering.About
My research project
The assessment of the impact of nutrient recovery for improving urban wastewater management and protecting water quality in lakes using the case study of Laguna de Bay, PhilippinesThe PhD research would particularly address the challenges of eutrophication in lakes and depletion of phosphorus resources for agri-food systems in the context of circular phosphorus economy. The main objective of the research project is to develop a novel tool by integrating a lake model with the life cycle sustainability assessment (LCSA) tool to holistically evaluate the environmental, social, and economical impacts of integrating a nutrient recovery system with wastewater treatment systems on water resources, using Laguna de Bay (Laguna Lake), Philippines as a case study. As such, the current and historical water quality data of Laguna Lake will be examined.
To promote the circular nutrient economy concept in agri-food systems of vulnerable developing countries such as Philippines, a nutrient recovery reactor will be installed to recover phosphorus from septic tank sludge at a farm, Salikneta Farm, Philippines. The recovered phosphorus will be used as an alternative fertiliser for locally-produced crops. The data gathered from the lake water quality studies and nutrient recovery reactor operations will be used as inputs for the integrated lake model to assess different scenarios of pollution and feasible control measures.
Supervisors
The PhD research would particularly address the challenges of eutrophication in lakes and depletion of phosphorus resources for agri-food systems in the context of circular phosphorus economy. The main objective of the research project is to develop a novel tool by integrating a lake model with the life cycle sustainability assessment (LCSA) tool to holistically evaluate the environmental, social, and economical impacts of integrating a nutrient recovery system with wastewater treatment systems on water resources, using Laguna de Bay (Laguna Lake), Philippines as a case study. As such, the current and historical water quality data of Laguna Lake will be examined.
To promote the circular nutrient economy concept in agri-food systems of vulnerable developing countries such as Philippines, a nutrient recovery reactor will be installed to recover phosphorus from septic tank sludge at a farm, Salikneta Farm, Philippines. The recovered phosphorus will be used as an alternative fertiliser for locally-produced crops. The data gathered from the lake water quality studies and nutrient recovery reactor operations will be used as inputs for the integrated lake model to assess different scenarios of pollution and feasible control measures.
Publications
Understanding the resources nexus such as food, energy, water, and land will play a crucial role in our progress towards sustainability and resilience. For example, food production is the main driver behind the excessive global use of mineral fertilisers. Though these fertilisers provide critical nutrients such as nitrogen and phosphorous, they also contribute significantly to the carbon footprint and embodied energy of the agri-food systems. In addition, these nutrients from agricultural runoff and sewage may also pollute and cause dead zones in our water bodies. On the one hand, phosphorous scarcity and food security could also pose an existential risk against the backdrop of feeding ten billion people by 2050. One emerging sustainability pathway is the green circular bioeconomy that encourages nutrient recycling from biowastes such as that agricultural waste, food waste, and domestic wastewater.
Nutrient recovery technologies have been constantly developed and optimised to address challenges in water and wastewater management, sanitation, and agri-food systems, while promoting sustainable management of resources and circular phosphorous economy. However, these technologies have been rarely explored beyond the laboratory-scale in developing countries where it is mostly needed. In this study, a nutrient recovery batch reactor system was installed at a local farm in the Philippines to process raw septage from an onsite sanitation system, a septic tank, to recover a high-value fertiliser for local crop production. The batch reactor was used for two processes, namely acid hydrolysis for pre-treatment of septage and chemical precipitation for recovered phosphorous fertiliser (RPF). The recovered fertiliser was then applied to produce eggplants and tomatoes, which are the common crops grown in the farm. Results show that an average of 290 g of RPF was produced for every 100 L of raw septage processed. With hydrolysis, 77% of the phosphate concentration were released as phosphates from the solid component of the raw septage. About 98.5% of phosphates were recovered from the hydrolysed septage. The RPF when applied to the farm’s eggplants and tomatoes has yields comparable to that of the commercial fertilisers. This study was able to demonstrate the potential of a resource-oriented sanitation system that promotes nutrient recycling towards sustainable agriculture that further leads to meeting the United Nations sustainable development goals, particularly zero hunger (goal 2), clean water and sanitation (goal 6), sustainable cities and communities (goal 11), and responsible consumption and production (goal 12).