Towards the Development of an Affordable and Practical Light Attenuation Turbidity Sensor for Remote Near Real-Time Aquatic Monitoring

Abstract

Turbidity is a key environmental parameter that is used in the determination of water quality. The turbidity of a water body gives an indication of how much suspended sediment is present, which directly impacts the clarity of the water (i.e., whether it is cloudy or clear). Various commercial nephelometric and optical approaches and products exist for electronically measuring turbidity. However, most of these approaches are unsuitable or not viable for collecting data remotely. This paper investigates ways for incorporating a turbidity sensor into an existing remote aquatic environmental monitoring platform that delivers data in near real-time (i.e., 15-min intervals). First, we examine whether an off-the-shelf turbidity sensor can be modified to provide remote and accurate turbidity measurements. Next, we present an inexpensive design for a practical light attenuation turbidity sensor. We outline the sensor’s design rationale and how various technical and physical constraints were overcome. The turbidity sensor is calibrated against a commercial turbidimeter using a Formazin standard. Results indicate that the sensor readings are indicative of actual changes in turbidity, and a calibration curve for the sensor could be attained. The turbidity sensor was trialled in different types of water bodies over nine months to determine the system’s robustness and responsiveness to the environment.

Multiparametric System for Measuring Physicochemical Variables Associated to Water Quality Based on the Arduino Platform

“…A parabolic fitting has also been reported in other turbidity sensors like the ones of Reference [28] but having an inverted curvature. Other aspects that must be accounted for when using the sensor are that the reading is influenced by ambient light.…”

“…There are low-cost commercial options if there is no need to measure turbidity with very high accuracy or when its value is less than 1000 NTU. For example, the Robot Gravity turbidity sensor and the TS-300B sensor [28].…”

“…There is no consensus on the most approp ampriate sampling period for real-time water quality monitoring. It can go from a few seconds to even minutes or hours [1], [2], [28]- [33].In any case, the filter of the SCC having the cut-off frequency of f c = 10 Hz reduces the amplitude of unwanted noise of 60 Hz. This stage of the circuit does not affect the amplitude, nor the phase of low-frequency signals, as Figure 15 shows.…”

Open-Source, Low-Cost, In-Situ Turbidity Sensor for River Network Monitoring

“…Gillet 38 found that these analog attenuation sensors could not achieve a sufficiently high resolution to monitor small changes in turbidity. Trevathan 39 recalibrated an appliance sensor (DF Robot SEN0189 Gravity -also attenuation style) and built a waterproof housing for field deployments. However, they did not report on the accuracy of the sensor and were not able to calibrate below 100 Nephelometric Turbidity Units (NTU) (although their test measurements were between 0-20 NTU).…”

Open-source, low-cost, in-situ turbidity sensor for river network monitoring

“…Gillet 37 found that these analog attenuation sensors could not achieve a sufficiently high resolution to monitor small changes in turbidity. Trevathan 38 recalibrated an appliance sensor (DF Robot SEN0189 Gravity - also attenuation style) and built a waterproof housing for field deployments. However, they did not report on the accuracy of the sensor and were not able to calibrate below 100 Nephelometric Turbidity Units (NTU) (although their test measurements were between 0-20 NTU).…”