Preliminary Detailed Design
Team Vision for Preliminary Detailed Design PhaseWhat did the team plan to do:
During the Preliminary Detailed Design Phase our team planned to setup tests that allowed us to get familiar with the larvae. We planned on learning about how to collect food for the larvae, their feeding rates, and their bi-products. From the standpoint of our system, we planned on testing whether the larvae stay in the top layers of food as new layers as added, filter options for the leachate, analyzing the digestate left by the larvae, and different options for collecting the pupae.
What did the team actually accomplish:
During this phase the team performed testing with the larvae that allowed the team to familiarize themselves with the larvae. The team built an insulated test box that was bigger than prior insulated containers. This allows the team to test bigger containers than previously available. A test procedure was drafted for a larger test to simulate a continuous system in order to answer the necessary questions about the design of our system.
Link to Data/Graphs.
- What is the process for feeding larvae and collecting data?
- What is an appropriate feeding rate for the larvae?
- What does the digestate look like?
- No one in our group has experience with BSFL composting. This is a starting point for the MSD group to familiarize themselves with BSFL composting.
- Learn the process for feeding larvae and collecting data.
- Learn about the feeding rates for larvae.
- Learn about the digestate.
- Acquire information for future tests.
- 600 Larvae
- 1 Container of prepared frozen food
- 2 Tupperware containers
- Insulated Container
- Beaker of water
- Come up with a feeding schedule for when people will be available to feed the larvae on certain days of the week.
- Measure the weight of the two containers and label them. The way the container was initially measured needs to remain consistent for future measurements (ex: with the lid attached or without the lid)
- Measure the initial weight of the larvae and calculate the weight per larvae.
- Split the larvae between two containers with each accommodating 300 larvae. Don’t count them, split in half by their weight.
- Start the larvae with 2 days’ worth of food, at an initial feeding rate of 100mg/larvae/day. This is used to start forming a layer of digestate. This should be 60g of food per container.
- Feed the larvae and collect data every 2 days. If the digestate builds quickly, reduce the feeding rates to 50mg/larvae/day. If further action is needed, reduce the feeding rates to 25mg/larvae/day.
- After you think larvae are in the pupating phase, stop feeding the larvae and communicate with Shwe for dealing with the pupae.
- Analyze the digestate after the larvae have been vacated from the containers.
- Measure the weight of the container.
- Measure the weight of 10 larvae for each container. Use tweezers to pick 10 random larvae.
- Place the container on the scale and zero it. Then add the necessary weight of food per container.
- Record the data in the Larval Feeding Schedule excel document in Dropbox.
- 100mg/larvae/day-Digestate built up quickly.
- 50mg/larvae/day-Seemed to be the right feeding rate for the larvae.
- 25mg/larvae/day-At this point it could be observed that most larvae were in the pupating stage. Also, it still has to be seen how many larvae are still alive.
- Larvae were wandering around the containers even before they reached the pupating stages.
- Larvae had no trouble in climbing the container walls which were a smooth plastic material and almost 90 degrees.
- We need multiple trials for weighing 10 larvae to acquire an accurate average weight per larvae.
- Big chunks of fibrous food remained as if they were not touched by the larvae.
- The containers started to develop a pungent odor due to minimal airflow.
Outcomes of Familiarization Test
- We learned about the larvae feeding process and collecting data from a composting test.
- If we want digestate to build up a feeding rate 100mg/larvae/day will accomplish that.
- Larvae can climb vertical walls meaning ramp design should focus more about how the ramp is integrated into our system and how to capture wandering larvae.
- Determine survival rates from the containers for our selected feeding rates. This will determine if our feeding rates are viable for future tests.
- Test filtration methods developed for future tests with the digestate developed from this test.
Prototyping ContainerDesign Requirements:
- Sealed/doesn't leak to prevent escape of larvae and wastes
- Disposable or easy to clean
- Enables separation of layers for bottom layer extraction
- Cheap and easy to build
- Clear walls can see layers
Challenge: To develop a container to use for digestate studies
Plan: Develop ideas and selected the optimal container
Prototype 3 was selected to be the optimal container based off of ease of use and reusability.
Prototyping Layer DividerIdea: Develop an integrated divider system that would make our container system more reusable.
Prototyping Hot Box
Challenge: To develop a large box to house all container studies that will be used for digestate and larvae studies.
Plan: Develop and build a container that will provide an ideal environment for larvae.
- Dark space
- Well ventilated
- Contains a heat source
- Contains a heat measurement device
- Height: 2'
- Width: 2'
- Lenght: 4'
Final built Product
Bill of Material (BoM)
Link to Bill of Material (BoM) BSFL Composter and Hot Box live document.
See below for screenshot of our BoM:
Test Plan for Larvae Evacuation Study
Feasibility Question: Do the larvae evacuate the bottom two-three inches of a container when the food waste is higher than 10 plus inches suggesting that the larvae migrate to the top 7” of food?
Background: All current concepts for waste removal assume larvae automatically migrate towards recently-added food and evacuate the digestate zones containing inedible leftovers. This test attempts to verify that the evacuation assumption is correct. It will also verify that the larvae will relocate to the top 7 inches of food even when the bottom layer contains edible food.
- Primary: Count larvae in bottom layer after the bottom layer is removed from the system. Calculate the percent loss of larvae from the entire system.
- Secondary: Use the removed digestate to test multiple filter systems for the filtration of leachate.
- Third: Continue to document information of the feeding and growth rates of the larvae.
The test plan includes
- Insturments to be used
- Personnel schedule during the study
- Testing procedure
- Accuracy measurements of equipment
- Controlled variation in measurements
Engineering requirements that will be satisfied
- Required height of the container
- Depth of larvae occupancy
- Temperature sensitivity
- Food consumption rates
- Leachate filtration mechanisms
- Digestate removal mechanisms
Test Plans for Engineering Requirements
Link to live Test Plans excel sheet.
Design and Flowcharts for the Upcoming Test Plan
Risk AssessmentLink to our Risk Management Table.
Design Review Materials
Plans for next phase
Link to Detailed Design Phase Plan live document.
See below for screenshot of our plan:
See below for screenshot of our Gantt chart:
See below for individual plans: