Counting Poo
| Counting Poo | |
|---|---|
| Primary Contact | Matt Little |
| QR code | |
Outline
This is a project via Nicola Greene to assist International NGO, Water for People with their work in Uganda.
The NGO install latrines in various urban and rural areas in Uganda. They have been having an issue with the fill rates of the latrines and are wanting to get real data on the use of the latrines. This means recoding visits to the latrines and counting the number of flushes made. Knowledge of the volume and weight of the deposits made each visit would be an added bonus.
A good overview of the problem and project is available here: http://www.slideshare.net/NicolaGreene/nicola-greene-msc-introduction-slideshare-28634508 For more on why sanitation is important: http://www.wateraid.org/uk/what-we-do/the-crisis/sanitation?gclid=CNm0p7nz67sCFQPmwgodFRYAug
The device must be:
- Robust
- Easy to install on existing equipment
- Low cost ($50-$200 budget per unit)
Hackday 11/1/14
Primary Objective:
- Produce a prototype to monitor a 'flush' event and record that data.
Secondary Objectives:
- Determine flush volume
- Determine solid/liquid proportion in flush
- Determine pit volume
Brainstormed ideas
Flush Sensing
| Idea | Description | Advantages | Disadvantages |
|---|---|---|---|
| Mechanical Flap | A hinged/moving cover on the waste pipe outflow that is moved by a flush. | Simple and robust. Maintainable in-situ. Low or zero power. |
Risk of causing blockage. Metallic components will corrode in high humidity/heat? |
| Beam break (across pipe) | An IR/visible light beam is transmitted across the pipe. A flush breaks the beam. | Cheap components Solid-state solution |
Waste on either transmitter or receiver will cause false readings |
| Reflective Sensor | An IR/visible Tx/Rx pair is underneath the outflow pipe. The beam is reflected by a flush into the receiver. | Cheap components Solid-state solution Can be "baffled" to stop waste interfering with sensing |
Can waste be completely eliminated from getting in the way? |
| Temperature Sensor | A temperature sensor (probably a thermistor) is mounted on/in the waste pipe. A flush changes the temperature. | Cheap components Solid-state solution Not affected by buildup of waste (unless large amounts are present |
Relies on temperature difference between waste and ambient pit temperature May be too slow to react to changes May have to be placed within flow, possible restriction/blockage May require designing to be flush with pipe surface |
| Piezo/microphone Sensor | A piezo or microphone is placed on the pipe. A flush causes vibrations that are picked up and amplified for sensing. | Solid-state solution | Requires significant analog circuitry for signal conditioning Requires significant software for signal processing Unknown effect of other vibration sources (e.g. nearby road) Possible that waste on sensor will dampen/alter vibration characteristics |
| Moisture Sensor | A moisture sensor is placed within the pipe. A flush changes the resistance of the sensor. | Low cost, solid-state solution | Has to be placed within flow, possible restriction/blockage May require designing to be flush with pipe surface |
Waste Volume Sensing
| Ultrasonic Sensor | An ultrasonic Tx/Rx pair placed on the pit lid will measure distance from lid to top-of-waste With knowledge of the dimensions of the pit, this will allow volume calculation. |
Non-contact, solid-state sensing | Relatively high cost Must be calibrate to pit dimensions for best data Likely to be incompatible with "tiger worm tray" composting addition? |
| Resistive/Capacitive Sensor | A series of sensors on a "pole" mounted vertically in the pit will be used to measure depth. | Potential to be very simple, low-cost solution | Sensors in contact with waste need to be protected against corrosion |