Application of buoy for water quality measurement using wireless systems

Kongphope Chaarmart* Program of Electrical and Electronic, Faculty of Industrial Technology, Sakon Nakhon Rajabhat University,

Sakon Nakhon, 47000, Thailand Simulation Research Laboratory, Center of Excellence on Alternative Energy, Research and Development

Institute, Sakon Nakhon Rajabhat University, Sakon Nakhon, 47000, Thailand * kongphope@snru.ac.th

Abstract— This paper report application of buoy in the

essence of Science, technology, engineering and mathematics (STEM), we proposes to design and build prototype of buoy for water quality measurement. The wireless controller system was applied in buoy for motion and sends the measurement data. This system was used evaluate the water quality at wastewater treatment plant 2nd

of Sakon Nakhon municipality. It was found that, the buoy can control by wireless controller system at maximum distance 80 meter without obstacles. While, the measurement data can send at maximum distance 120 meter. This system exhibits the maximum error of pH value at 0.83% when compared with laboratory of Sakon Nakhon municipality.

Keywords—STEM, buoy, water quality measurement, wireless controller system, wastewater treatment

I. INTRODUCTION The STEM is an innovative learning model that

integrates science, technology, engineering and mathematics [1-2] together with provide students with knowledge to solve problems including the development of new processes or products that are beneficial to the lifestyle and occupation through experience project-based learning activities are based on or problem-based learning. STEM instruction in engineering is an integration the troubleshooting steps as follows: (1) identifying a challenge process of understanding for problematic; (2) explores ideas with integration of information which the ideas related to solving problems and finding the advanced and drawback; (3) planning and development of work processes that have an objective and timeline as well as design and development prototype; (4) testing and evaluating that used to improve the efficiency of problem solved and (5) present the solution of the process by experimental which must present the result and designed to present an information [3].

From mention above, the STEM principle applies to measurement of water quality. Monitoring of water quality has been important for the water quality of the treated wastewater before discharge to the water source and takes the data from the monitoring to the water quality management plan, it’s amend and prevent the effects of pollution on water resources in a timely manner before the water source changes.

Wireless sensor network (WSN) can be applied for medical [4], agriculture [5], environmental [6], and industries [7]. WSN composed arduino for controller, node MCU for module wireless ESP8266, and Zigbee for wireless communication, respectively. Advantages of WSN is easy to move and cover area for study [8]. Several researchers used the WSN for monitoring another system, such as, Wireless electrical appliance control system via web browser [9]. This research brings general equipment: the MCS-51 microcontrollers are used to control centralized control of the on-site power control, which is a single point of control and remote control from the center to the client via a wireless communication device using the Radio Matrix or BiM2-433-64-5V Transceiver is a data receiver and transmitter; the PLC based on ZigBee [10], the Zigbee concept is used to communicate in the near term or to connect the PLC to the controller. Advantages of Zigbee compared to Bluetooth is that Zigbee can receive and send data in a network with the technology Ad- Hoc, Peer to Peer, Star and Mesh can be used to select the technology model to map the plant's production line; and water quality online monitoring in intensive fish culture [11], The remote wireless control system for online water quality monitoring in fish farms for predicting or forecasting water quality values using the CDMA system in combination with the VPN network. The overall structure is divided into two components. With the

Fig. 1 Conceptual framework.

Remote Monitoring Platform (RMP) and the Central Monitoring Platform (CMP), the RMP will measure the acidity parameter. Value of dissolved oxygen Salinity and temperature, CMP receives data from RMP, analyzes and sends information to the system administrator and stores it in the database. In this work, we present the WSN and wireless controller system (WCS) applied in buoy for water quality measurement. This system was test at wastewater treatment plant 2nd

of Sakon Nakhon municipality. The conceptual framework is show in Fig. 1.

II. MATERIAL AND METHOD The model of buoy is highlight in Fig. 2. The buoy

composed propeller, DC motor 12 V with speed 800 rpm, PVC pipe (diameter 7.62 cm), box for control, potential of hydrogen ion (pH) sensor probe (analog pH meter kit), alarm, and solar cell 20 W. To design the buoy, regardless the rotation of the tides or the

rapidity of the water, the direction of the wind and other factors that affects the sinking of the buoyancy. From the relation of the buoyancy force ( BF ), in which is not only one device. It is necessary to calculated of the total force from each of the device, therefore we calculated of the mass that floating above the water. It is another device in the PVC pipe, polyethylene is high density. It is another device. There are parts drowning and floating. In this case, we can calculate buoyant force [12].

Fig. 2 Prototype of buoy for water quality measurement, composed propeller (1), DC motor (2), PVC pipe (3), box for control (4), pH sensor probe (5), alarm (6), and solar cell (7).

(c) Fig. 4 Scheme of wireless controller system for (a) motion of buoy and (b) water quality measurement. (c) Monitoring of Blynk - Arduino, ESP8266, RPi application on smart phone.

Fig. 3 Scheme of PVC pipe.

Fig. 5 Finish prototype of water quality measurement composed (a) control buoy system, (b) water quality measurement and (c) input pH meter probe.

Fig. 6 Test buoy on wastewater treatment plant 2nd of

Sakon Nakhon municipality.

B water dipF V g (1)

Where BF , water , g and dipV are buoyant force of a water acting on a buoy, density of the water

3(1 )g cm , gravitational acceleration 9.8 (m/s2), volume of water displaced, respectively.

The airV can be calculated by equations (2);

( )( )

( )B pvc pvc total

air air water dip

M VV V

(2)

Where BM , pvc , ( )pvc totalV and air are mass total of buoyant, density of PCV (950 kg/m3), density of air (1.2 kg/m3) and total volume of PVC. Due to the value of airV similar dipV ; air dipV V , therefore;

( )( )( )

B PVC PVC totaldip

water air

M VV

(3)

( ) 1 2 3PVC total PVC PVC PVCV V V V (4)

2 21 3 ( )PVC PVCV V R L r l (5)

2 22 ( )

4PVC N nhV D D

(6)

2 2 2 2( ) 2 ( ) ( )

4PVC total N nhV R L r l D D

(7)

where 1PVCV , 2PVCV and 3PVCV are volume of PVC at point 1, 2 and 3; and the parameters of R , r , L r , h,

ND and nD as shown in Fig. 3. In this work, the 516.45 NBF therefore the buoy for water quality

can be maximum load about 52.65 kg.

We use solar cell for generate electrical energy. After that electrical energy was keep in battery for power supply. The wireless controller system for motion of buoy composed smart phone, control circuit, relay, and motor. The wireless controller system for water quality measurement composed pH sensor, transmitter for send data of pH, receiver for receive the data of pH and display real time in monitoring. The scheme of WCS as shown in Fig. 4. For WCS (Fig. 4(a)), first we install application “Blynk - Arduino, ESP8266, RPi” in smart phone. Next, we use smart phone control motor such monitor in application as Fig. 4(c). For water quality measurement, the analog data of pH was obtained probe pH and send to arduino board. After that, the data of pH was send between arduino and computer by using Xbee at bit rat 2.4 GHz and 250 Kbps. This prototype is show in Fig. 5.

This device was test motion and water quality measurement in wastewater treatment plant 2nd

of Sakon Nakhon municipality as shown in Fig. 6.

III. RESULTS AND DISCUSSION The monitoring of water quality measurement is

highlight in Fig. 6. The measurement show pH value at real time, which we set around 5 minute.

The transmitter of pH values was tested five times, the average result as shown in Table 1. It was found that, it can be good signal for transmit at maximum distance about 100 m, while at 120 m exhibits poor of signal. However, the buoy can’t transmit at more than 140 m.

The results of system control motion of buoy at a direction of forward, turn right, and turn left. The design experiments order to fund moves to 10 m, then gradually increase the distance control moving up to 10 m as shown in Table 2. It can observe that, the controlled at 10-50 m can control the movement of capital, at distance 60 m show relay time about 10-20 s. At 70-80 s can control but its shows signal poor and large relay about 20-30 s. The absence of a signal in the distance of 90-100 m. These result can concluded that the buoy control system can’t be controlled wirelessly over a distance of 80 m without obstacles.

(c)

Fig. 7 Monitoring of pH value at real time.

Table 1 The result of transmitter of pH value at versus distance.

Distance (m) Result (Yes or No) 20 Yes 40 Yes 60 Yes 80 Yes 100 Yes 120 Yes (The signal is poor ) 140 No

Table 2 The result of control buoy system.

Moving direction

Distance (m)

Results (Yes or No)

Relay Time (s)

Forward Turn right Turn left

10 Yes 20 Yes 30 Yes 50 Yes 60 Yes 10-20 70 Yes (The signal

is poor ) 20-25

80 Yes (The signal is poor )

20-30

90 No - 100 No -

The table 3 had shown the pH value of the

wastewater treatment plant 2nd of Sakon Nakhon

municipality. Comparison of the information was obtained from the system designed with the information provided by the laboratory. It can explain that the highest pH error was 0.83 on 9 Feb, 2017. The reason for the high error caused by the wastewater treatment plant 2nd

of Sakon Nakhon municipality was wide. Therefore, staff's laboratory may be at different points in the buoy measurement, and the other is the difference in temperature during the measurement.

IV. CONCLUSION This research proposes to design and build of buoy

for water quality measurement. From the buoy control, floating buoys can be controlled to move the buoys according to their requirements and the water quality monitoring system can send data on the pH of the water in the wastewater treatment pond. The comparisons of pH measurement show error about 0.08-0.83 %.

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Table 3 The comparison of pH measurement between buoy and laboratory. Date pH Error

(%) System Laboratory 6 Feb, 2017 7.87 8.43 0.56 7 Feb, 2017 8.16 8.56 0.4 8 Feb, 2017 8.92 8.00 0.08 9 Feb, 2017 8.92 8.09 0.83 10 Feb, 2017 9.69 9.01 0.28 11 Feb, 2017 8.59 9.13 0.31 12 Feb, 2017 8.59 8.11 0.48 13 Feb, 2017 9.04 9.64 0.60