Grantee Research Project Results
Final Report: Phosphorus Recovery from Sewage
EPA Grant Number: SU832482Title: Phosphorus Recovery from Sewage
Investigators: Carlarne, Cinnamon P , Oerther, Daniel B. , Bove, Adam , Hoerst, Amy , Herman, Billie , Lieberth, Brett , Kinkle, Brian , Luedeker, Christopher , Zdinak, Christopher , Maurer, Eric , Weinkam, Grant , Lubbers, Hannah , Umberg, Katie , Parsons, Mike , Majed, Nahreen , Lamendella, Regina , Shane, William
Institution: University of Cincinnati
EPA Project Officer: Page, Angela
Phase: I
Project Period: September 1, 2005 through May 31, 2006
Project Amount: $10,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2005) RFA Text | Recipients Lists
Research Category: P3 Challenge Area - Chemical Safety , Pollution Prevention/Sustainable Development , P3 Awards , Sustainable and Healthy Communities
Objective:
The purpose of The University of Cincinnati’s P3 project is to develop and promote the sustainable use of phosphorus in developing countries by finding multiple, socio-economically targeted solutions for recovering and reusing phosphorus from wastewater. In addition, the project seeks to alleviate the pandemic deterioration of agricultural conditions by providing a readily available and reliable new form of fertilizer. In order to achieve a sustainable approach to the recycling of phosphorus, we chose to recover the nutrient from wastewater and reuse it as a key component in fertilizing agents. The scope of this project focuses on the developing country of Kenya; an EastAfrican country with a 3% growth rate in 2005 (World Factbook, 2005) and declining crop production, due in part to nutrient removal. For Kenya’s long term environmental and economic health, it is imperative that we find a sustainable agricultural resource that can improve agricultural productivity without resulting in further depletion of exhaustible natural resources. The UC team developed and implemented a multi-tiered approach that designed and tested feasible means of recovering phosphorus within Kenyan cities and villages, which rely on municipal wastewater treatment plants and agricultural farmlands.
We followed a three-tiered approach to reflect the differing levels of development within Kenya, i.e., cities with wastewater treatment facilities, smaller towns, and local villages. The first approach focuses on urban settings with large populations and existing wastewater treatment facilities. The idea is that the existing facilities could be updated to incorporate a method of biological phosphorus removal and recovery, with the recovered phosphorus being converted into fertilizer for use in agricultural sectors.
The third and final method is designed for the rural areas of Kenya, which are predominantly populated by farming communities. For these areas, the proposed method for phosphorus recovery and reuse is to rely on the direct application of diluted urine to crops via a drip bucket irrigation system. Urine contains phosphorus, nitrogen, calcium, and potassium and, when applied appropriately, can be used as a cheap and effective fertilizer. The UC P3 design proposed diluting and applying urine through a drip bucket irrigation method, which is currently supported by the Kenyan Agricultural Research Institute (KARI, 2006). To design and test the methods of phosphorus recovery and reuse discussed above, we team created innovative design teams with specific objectives:
Team 1: Design the Enhanced Biological Phosphorus Removal (EBPR) lab-scale reactors and struvite precipitation (Targeting phosphorus-removal and recovery in larger cities).
Team 2: Cash crop growth and analysis (Assessing struvite, urine, and wetland effluent and biomass as potential practical fertilizers)
Team 3: Drip bucket irrigation design (Targeting phosphorus-reuse from urine and its application to agricultural farms)
Team 4: Wetlands design and construction (Targeting phosphorus-removal and recovery in small-scale communities)
Summary/Accomplishments (Outputs/Outcomes):
Overall, the project was viewed as a success. As identified in the original proposal, our major milestones included:
- developing a microbiological bioprocess reactor to dramatically increase the mass fraction of phosphorus in wastewater biomass;
- developing a precipitator reactor to capture phosphorus from wastewater as a struvite precipitate (magnesium ammonium phosphate);
- demonstrating that the recovered phosphorus is bioavailable and capable of stimulating the growth of plants as a fertilizer;
- demonstrating that drip bucket irrigation using a diluted concentration of urine as a source of nutrients enhances biomass of plants;
- demonstrating that wetlands are a viable method for phosphorus recovery and reuse; and
- developing a socio-economic analysis to demonstrate the value of recovering phosphorus from sewage as a sustainable technology to improve best agriculture practice.
Bioprocess Engineering: EBPR
Throughout the operation of the bioreactor (seen at right), the levels of phosphorus in the influent were maintained between 20 and 30 mg/liter, while maximum levels observed were 45 to 55 mg/L in the anaerobic phase. The kinetic studies indicated release of phosphorus during the anaerobic phase and uptake in the aerobic phase. This orthophosphate profile is consistent with current model of enhanced biological phosphorus removal (MetCalf and Eddy, 2004).
Struvite Precipitation: Experimental studies were performed to evaluate the kinetics of struvite precipitation using reagent grade MgCl2 as well as supernatant from the anaerobic phase of the bioreactor, where orthophosphate concentrations were maximal (45-55 mg/liter). The identity of the putative struvite precipitate was confirmed through solubility tests, analytical chemistry, and microscopic identification (400X mag., Nikon Eclipse E400) of crystal formation. Kinetic studies were performed to characterize the average production of struvite derived from our EPBR per day and yielded an average result of approximately 12.57 g of struvite precipitate/L-day.
Struvite as a potential fertilizer: Fertilizer analysis indicated that the struvite treatment enhanced growth of French beans and onion replicates, as compared to the negative control treatment. The French beans fertilized with struvite produced nearly 2.5 times the amount of bean biomass as compared to the triple superphosphate control treatments.
Drip Irrigation: Use of urine as a potential P-containing fertilizer: Visual assessments of each treatment revealed that the urine-fertilized plants had larger, denser, more vibrant foliage (Seen below), while the non-urine treatment showed signs of nutrient deficiency, as characterized by pale leaf color and leaf necrosis. Bean harvest numbers for the urine fertilized plants were also significantly higher than the control, with an average of 14.08 and 8.58 beans per plant for the urine and non-urine treatments, respectively (n=12: p=7.59*10-5). Dry mass data indicated root, shoot, and bean biomass were all significantly higher in the urine fertilized plants as compared to the non-urine control. Thus, the drip irrigation system (seen above) in combination with diluted urine as a fertilizer potentially provides a sustainable approach for smaller Kenyan agricultural farms by reducing water loss in irrigation and enhancing production of a well-known Kenyan cash crop.
Wetlands: Community-based Approach to P-reuse: The wetland system, seen at left, was fed with 32 L of synthetic wastewater containing 30 mg/L orthophosphate, which was retained for a period of one week. Preliminary results indicate that, after a one week retention time, wastewater effluent from the wetland was reduced to 6 mg/L orthophosphate. Thus, the improved effluent quality of wastewater from the wetland may be applied via irrigation to nearby farms, or the biomass accumulating nutrients in the wetland can be harvested and used as composted fertilizer.
Conclusions:
The University of Cincinnati’s P3 project aims to integrate different technologies to lead much-needed efforts to recycle and reuse phosphorus in order to help people by ensuring adequate and affordable global food supplies, to help prosperity by increasing agricultural productivity and the development of a healthy and equitable global food market, and to help the planet by reducing the intensity of phosphorus mining, and by decreasing eutrophication of our water systems by closing the phosphorus loop.
Proposed Phase II Objectives and Strategies:
Phase II will build upon our successful results from Phase I and from our previous findings during the 2004-2005 EPA P3 Competition to implement phosphorus recovery and reuse technologies in “real world” contexts. Phase II will focus on implementing phosphorus recovery and reuse methods in the developing world, specifically in East Africa. The primary objectives of Phase II include: (1) refining low tech, minimal cost alternatives for bioprocessing and precipitation technology; (2) working with partners in developed and developing countries to implement, monitor and assess the use of bioprocessing and precipitation technologies in practice in East Africa; and, (3) working with international and local NGOs, governmental, and international organizations (e.g., development banks) to develop policy frameworks that support and incentive the use of bioprocessing and precipitation technologies on multiple scales in the developing world.
The focus of EPA’s P3 Award Competition is on improving sustainability, with a view towards understanding the relationships between people, prosperity and the planet. One of the key elements in ensuring that sustainable development becomes an integral part of global and state development strategies and legal systems is abiding by another central international environmental law principle, common but differentiated responsibilities. The principle of common but differentiated responsibilities suggests that (1) there is a common responsibility of all states to protect the environment, or parts of it, at the national, regional and global levels, but that (2) we need to take account of differing circumstances, particularly in relation to each state's contribution to the creation of a particular environmental problem and its ability to prevent, reduce and control the threat when we allocate responsibilities for environmental protection.
Thus, the primary objective of Phase II is to put the principles of sustainable development and common but differentiated responsibilities into practice by promoting joint work between the University of Cincinnati and partners from developed and developing countries to implement systems of phosphorus recovery and reuse in East Africa. In this way, we will promote sustainable resource use, agricultural practices and life styles while also reflecting the fact that both developed and developing countries are responsible for addressing the problem of unsustainable phosphorus use and the concomitant environmental problems. This approach also reflects that developed countries, such as the United States, both bear primary responsibility for past depletion and misuse of phosphorus and possess the resources and technology necessary to initiate, enable, and incentivize the creation and adoption of more sustainable practices at home and abroad.
To put our principles into practice, we will rely on the findings of Phase I and our connections with on-going projects in Eastern Africa, e.g., with the Village Life Outreach Program and Engineers without Borders, to initiate on-site case studies to test our new phosphorus recovery and reuse technologies in villages and rural areas in East Africa. In addition, we intend to move beyond simply establishing on-site case studies to addressing the legal, political, and economic structures that aid or impede the adoption of new, more sustainable practices. To this end, we will utilize the PI’s experience with international environmental policy development and connections with international NGOs operating in Kenya (e.g., Nature & Culture International) to develop a more comprehensive understanding of current policy structures in Kenya and how these contribute to or impede efforts to improve agricultural sustainability and food security. This collaboration between a developed and developing country and between engineers, scientists, and policy-makers furthers the underlying purpose and goals of the P3 program.
Supplemental Keywords:
agriculture, analytical, bacteria, bioavailability, engineering, innovative technology, precipitation, renewable, sustainable development, water, drip bucket irrigation, wetland, Scientific Discipline, Water, Chemical Engineering, Wastewater, Environmental Chemistry, Environmental Engineering, eutrophication of surface water, phosphorus recovery, alternative technology, economically feasible technology, socioeconomics, industrial sewers, effluents, aqueous waste streamRelevant Websites:
Food and Agriculture Organization of the United Nations Exit
CoinMill.com - The Currency Converter Exit
The Kenya Agricultural and Livestock Research Organisation (KALRO) Exit
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.