Grantee Research Project Results
2017 Progress Report: Larvae for Managing Food Waste in Northern Cities
EPA Grant Number: SU836810Title: Larvae for Managing Food Waste in Northern Cities
Investigators: Thorn, Brian
Current Investigators: Thorn, Brian , Brownell, Sarah , Purnama, Ria , Carter, Dawn , Win, Shwe Sin , Piscitelli, Alicia
Institution: Rochester Institute of Technology
EPA Project Officer: Page, Angela
Phase: I
Project Period: October 1, 2016 through September 30, 2017 (Extended to September 30, 2018)
Project Period Covered by this Report: September 1, 2016 through August 31,2017
Project Amount: $14,958
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2016) RFA Text | Recipients Lists
Research Category: Sustainable and Healthy Communities , P3 Awards , P3 Challenge Area - Sustainable and Healthy Communities
Objective:
Our proposal, Larvae for Managing Food Waste in Northern Cities, was submitted to compete for an EPA P3 award in December, 2015. The proposal described work that would be done on the RIT campus to assess the viability of black soldier fly larvae (BSFL) as food waste composters in cold climates. Our previous work with BSFL has suggested that they are able to process a wide variety of food waste, thereby reducing the volume of the waste substantially. Advantages of BSFL over traditional composting methods include a relatively rapid waste processing cycle, a compact processing footprint, and low sensitivity to the incoming feedstock.
Because black soldier flies are not native to cold climates, there are important technical challenges associated with scaling up BSFL composting in northern regions. SU-836810 described pilot-scale work to address the challenges associated with maintaining a BSFL breeding colony in a cold weather climate with minimal energy inputs. An aggressive set of objectives were called out in our SU836810 proposal:
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Objective 1: to design and construct a prototype continuous feed BSFL food waste reactor that can be scaled to meet higher food input levels
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Objective 2: construction of a BSFL rearing shed based on passive house building principles
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Objective 3: to determine the energy needed to maintain a 1 m2 BSFL colony in the shed through the Rochester, NY winter
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Objective 4: to assess the emissions generated by the larvae as they process food waste
Progress Summary:
Students enrolled in the Multidisciplinary Senior Design (MSD) program in RIT’s Kate Gleason College of Engineering have made good progress toward Objectives 1 and 2 as described on page 1. Completion of Objectives 3 and 4 is dependent upon successful completion of Objectives 1 and 2.
Objective 1:
Objective 1 specifies the design and construction of a prototype reactor where black soldier fly larvae will feed on waste food from RIT’s dining halls. Current BSFL reactors are batch systems where the larva colony must be stopped periodically to remove wastes. In the reactor the larvae will gain weight, reduce the volume of the food waste, and generate a valuable soil amendment (compost).
Two teams of MSD students (11 students in all) have participated in the preliminary and final design of a novel BSFL reactor. MSD students follow a prescribed engineering design process, assess customer needs and engineering requirements, evaluate concepts, resolve major technical hurdles, and employ rigorous engineering practices to design and ultimately build a prototype device or process. MSD is a “studio” course – it adopts an approach to student interaction that is hands-on, instructor facilitated, and student-centered. Students from other colleges are encouraged to participate.
The initial student team (active from September, 2016 through May, 2017) performed testing with the larvae that allowed the team to become familiar with the BSF life cycle. The team built an insulated test box that was bigger than prior testing containers. This allowed the team to evaluate larger populations of larvae than previously available. A test procedure was drafted to simulate a continuous system. Preliminary testing was performed to better understand the food consumption rates of BSFL under testing conditions. The team conducted experiments to determine reactor configuration with respect to the appropriate mesh size to allow for draining of leachate as well as the geometry of the exit ramps that allow mature larvae to migrate out of the food waste in order to pupate. They built a continuous reactor that was tested with larvae by the PI’s over summer 2017. A more complete description of this team’s work can be found at the EDGE website where students document their progress on their projects: https://edge.rit.edu/edge/P17422/public/Preliminary%20Detailed%20Design.
Results from the initial project team and suggestions for improvements based on using the reactor last summer were passed to the current BSFL team, which has been active since September, 2017. They have engaged in substantial revision and refinement of the BSFL reactor and the proposed rearing shed. Final detail drawings of the BSFL reactor have been generated, and construction of a prototype reactor is set to begin in the Spring semester. Figure 1 shows detail views of the proposed continuous BSFL reactor.
Objective 2
Objective 2 specifies the construction of a BSFL rearing shed based on passive house building principles. Some initial work on the design of the shed was done as a class project by graduate students in our architecture program during Spring 2017. However, the majority of the progress toward this objective has occurred since June, 2017. An RIT architecture student and a local passive home consultant worked together to finalize the design details and we begin the construction of the proposed BSFL breeding shed. An important goal for the construction of the shed is that it maintain ideal conditions for BSFL (a temperature of 35 °C and 75% humidity) with as little added energy as possible. Passive house design generally incorporates features such as orientation of the building to maximizing solar gain in winter, super insulated walls, ceilings and floors with vapor barriers, and overhangs to reduce solar gain in summer, among other energy saving techniques. Figure 2 provides the architect’s rendering of the final shed in place in RIT’s community garden.
Detail drawings and specifications for the shed have been developed and construction is well underway. The shed is built upon a superinsulated platform that is filled with over 9 inches of cellulose insulation and capped with a selectively permeable membrane. The walls of the structure are actually “double walls”. That is, each wall is comprised of two 2 inch x 4 inch wall sections with a gap between them. The interior wall sections are covered with airtight membrane, and the exterior walls are covered with a selectively permeable membrane that allows water vapor to escape. Dense pack cellulose insulation is blown into the space between the interior and exterior wall sections. The detailed floor plan in Figure 3 illustrates the double wall construction. The intent is to create a well insulated (walls with an R rating of 60 or better), airtight structure that will minimize energy consumption.
At this writing, construction of the shed nearly complete. The platform is in place, the walls have been erected, the roof has been installed, and all of the required insulation has been blown in and compacted. A high R window and door are in place and much of the siding has been installed. Figure 4 is a photograph of the BSFL breeding shed prior to the installation of the door, window, and siding. The exterior membrane is visible underneath the wood purlins to which the siding will be affixed.
Objectives 3 and 4
These objectives relate to understanding the mass and energy balance of BSF composting systems. Our goal is to quantify the heat, water vapor and green house gas emissions of larvae/food waste systems. We have had a series of independent study students from our Chemical Engineering program conducting laboratory-scale experiments on feeding larvae using an insulated box with a stirring fan (Figure 5 left). A very low flow of room air is pulled through the system and the temperature and humidity of the air at the inlet and outlet are tracked over 24-48 hours. The difference between the inlet and outlet air are used to estimate the heat generated by larvae. Changes in carbon dioxide concentrations over time for feeding larvae have also been measured using a gas chromatograph (Figure 5 right). We have been working to improve the experimental set-up so results are not yet finalized. Once the reactor and the shed become operational, we will also be able to track the energy and carbon dioxide emissions on the scale of the shed.
Relevant Websites:
EDGE Multidisciplinary Engineering Detailed Design Exit
Progress and Final Reports:
Original AbstractThe 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.