Final Buffer Iteration

The first iteration has been changed by taking into account the needs of the stakeholders as an extra controllable outlet to the garden has been added to the buffer. The municipality of Enschede wants to reduce the strain on the sewerage system as much as possible which can be done by discharging water into the garden instead of the sewerage system. This was said during an interview which can be found in Appendix I. When users would attach a garden hose or a sprinkler installation to this outlet, watering the garden could be made a lot easier.

Experience showed that a downspout diverter is not working properly in this setup and therefore it was chosen to replace the downspout diverter and have a separate inlet and overflow. In order to measure the water level very accurately and detect leakages, water flow sensors have been added to every in- and outlet.

Therefore, the smart rainwater buffer consists out of 5 water flow sensors that measure the in- and outflow of the rainwater, one ultrasonic sensor that measures the water level inside the buffer and two solenoid valves that control the discharge of the harvested rainwater to the sewerage system and to the garden. The final buffer iteration can be seen in Figure 18. When for example a water flow sensor measures a water flowing through when a valve is closed according to the microcontroller, the system can detect this as a valve malfunctioning.

Figure 18. Final buffer iteration

Unfortunately, the water flow sensors are not very accurate and not capable of measuring the in- and outflow in litres correctly. Therefore, they have been given the sole purpose to detect if water flows into or out of one of the in- and outlets and detect potential malfunctions of the valves and faucet.

Finally, a box has been attached inside the lid of the buffer. This box contains a microcontroller, the Arduino Mega and a microcomputer, the Raspberry Pi 3B, a breadboard with the circuits for the solenoid valves and an ultrasonic sensor for which holes have been cut out of the box for the sensor to fit in.

The connections between the hardware components can be seen in Figure 19. The Raspberry Pi is powered with a micro USB cable and has a wireless internet connection with which it can connect to the database. The Arduino is powered by a 12V power plug which also supplies the Vin that switches the transistors.

Figure 19. Components overview

Prototype

For the prototype, a rain barrel was bought at a physical store and adjusted to fit the requirements and the sketch. A radiator faucet has been installed on the place of the original faucet, because of its screw- thread, making it easier to attach a water flow sensor to this type of faucet.

In addition, two extra holes have been drilled in the bottom of the buffer where a solenoid valve has been installed in each hole, one for the garden outlet and one for the sewerage system outlet. To both valves, two water flow sensors have been connected.

Unfortunately, due to restrictions of the university building, the downspout could not be altered. To fit a water flow sensor into a downspout, a top part of a plastic bottle has been transformed and melted around a downspout pipe, acting as a funnel. Furthermore, the downspout was not connected to the sewerage system. Therefore, pipes have been installed at the overflow outlet, directing the water towards the ground with pipes. At the end of these pipes, a water flow sensor has been installed.

Finally, wires for the sensors and valves have been cut and soldered to fit the breadboard and Arduino pins. The wires have been directed into the box with the Raspberry Pi, Arduino, breadboard and ultrasonic sensor where everything has been connected. The box has been attached to the barrel with cable ties for easy assembly and de-assembly. Photos of the prototype can be seen on the next page in Figure 20.

Figure 20. Photos of the buffer prototype

Top left: Inlet with funnel and flow sensor. Top right: Smart rainwater buffer. Bottom left: Solenoid valve with flow sensor and faucet with flow sensor. Bottom right: Blue box with hardware components.

6.5 Interface

For the smart rainwater buffering system project, two different end users have been defined; the citizens of de Bothoven and Velve-Lindenhof and the municipality of Enschede. For both end users, a different interface will be designed to interact with the smart rainwater buffer. However, this report focusses solely on the design of the interface for the citizens of the two neighbourhoods1_.

This section will describe three different iterations of interface mock-ups after which the final interface has been programmed. The third iteration of the interface has been tested with test participants which will be described in chapter 7. All text present on the interfaces are written in Dutch, the native language of the majority of the target users.