Embedded Wireless Dissolved Oxygen Monitoring Based on Internet of Things Platform

Recently, Internet of Things (IoT) applications are distributing into many areas, such as industry and agriculture. This article presents the embedded wireless Dissolved Oxygen (DO) monitoring system based on IoT platforms. The module contains two types of data sensing, which are water temperature and DO sensors. Both devices are embedded with a wireless IoT module using NodeMCU-ESP8266, an integration WiFi-Microcontroller on a single board. The proposed IoT-DO monitoring system detects information data from the aquaculture pond environment. Namely, the parameters studied are water temperature and DO values. The cloud internet network collects and stores the experimental data and link to the users. The relationship between both parameters is analyzed using Statistical Package for the Social Sciences based Pearson correlation coefficient theory. The findings found that the water temperature and DO values are negatively related, with a statistically significant .05. Water temperature is the principal affection to other parameters of water. In this work, the DO value is studied to relate the water temperature. It was found that when the water temperature increases, the DO decreases accordingly and vice versa.

Towards Energy Efficient Onsite Wastewater Treatment

The objective of this work is to demonstrate that some weaknesses of the onsite packaged WWTP associated with high operational costs and energy inefficiency could be overcome by improved management. The research methodology consists of series of batch studies with sludge from municipal or onsite WWTP, which simulate different working regimes of the onsite WWTPs – daily operation, toilet flushing and dishwasher machine. A simple classical tool, Oxygen Uptake Rate (OUR) is used to prove the hypothesis that regardless the specificity of the onsite WWTPs, namely the irregularity of the flow and load, three parameters follow similar increasing and decreasing trends – inflow rate, inflow pollution load and oxygen demand in the reactor. The literature review has not shown research publication about applicability of (OUR) for management of onsite WWTPs, but has shown experience and knowledge with municipal WWTPs, which were utilized in our study. The results prove that when there is no wastewater generation in the household, the (OUR) in the reactor is very low, 0.0007 to 0.0015 mg/l.s, thus do not require high oxygen supply. However, when wastewater flushes into the onsite WWTP, the oxygen demand increases rapidly and (OUR) reaches the range of 0.0040 to 0.0063 mg/l.s depending on the type and the quantity of the incoming substrate (pollution load). These results, if verified in filed experiments will enable optimization of the energy use during onsite WWTP operation. The suggestion is that the oxygen supply in the reactor should be adjusted according to the demand, respectively proportional to the inflow rate. In addition to the benefit of saving energy, the comprehensive sensors for dissolved oxygen monitoring, which require qualified maintenance could be avoided and replaced by simple sensors for level, which are anyway part of the equipment of most of the onsite packaged WWTP.

Active Potentiometry for Dissolved Oxygen Monitoring with Platinum Electrodes

Potentiometric oxygen monitoring using platinum as the electrode material was enabled by the combination of conventional potentiometry with active prepolarization protocols, what we call active potentiometry. The obtained logarithmic transfer function is well-suited for the measurement of dissolved oxygen in biomedical applications, as the physiological oxygen concentration typically varies over several decades. We describe the application of active potentiometry in phosphate buffered salt solution at different pH and ion strength. Sensitivity was in the range of 60 mV/dec oxygen concentration; the transfer function deviated from logarithmic behavior for smaller oxygen concentration and higher ion strength of the electrolyte. Long-term stability was demonstrated for 60 h. Based on these measurement results and additional cyclic voltammetry investigations a model is discussed to explain the potential forming mechanism. The described method of active potentiometry is applicable to many different potentiometric sensors possibly enhancing sensitivity or selectivity for a specific parameter.