In-situ turbidity measurement of model wastewater using cationized bioflocculant induced from aspergillus flavus

Abstract

The aim of this study was to develop a cost-effective alternative technique for turbidity measurement. Nowadays, different instruments have been used for turbidity measurement such as turbidimeter and spectrophotometer. However, each technique encountered with limitations. Conventional techniques for turbidity measurements usually are expensive, unsafe data collection, the delay between samples collection and posting results. Furthermore, conventional techniques for estimating flocculation efficiency through spectrophotometer can reduce the accuracy of bioflocculant efficiency. In-contrast, in-situ turbidity measurement techniques that mainly use in-situ sensors, could be a possible solution to the mentioned problems because it measures turbidity directly and continuously. To find an appropriate solution and shrink the expenses of bioflocculation, a relatively inexpensive and novel millilitre scale-based bioflocculator was successfully fabricated for in situ turbidity measurements of cationized bioflocculant. Bioflocculator was fabricated with different control systems such as rotational speed controller, temperature controller and microcontroller platform. Moreover, bioflocculator was equipped with different sensors such as turbidity sensor, hall-effect sensor and temperature sensor to ensure the automation and high throughput of bioflocculator. Also, the data retrieve system was developed to avoid manually data collection and save time. The entire process of wastewater treatment such as mixing and online measurements of turbidity was performed within the bioflocculator. The flocculating activity of bioflocculant produced by A. flavus S-44 was compared using conventional techniques and bioflocculator. The average flocculating efficiency of 94 % was recorded using conventional techniques, however, it was reduced to 89.87 % by on-line measurements using bioflocculator. The possible reason for low flocculating efficiency using bioflocculator could be due to the real measurements which may give the actual bioflocculant efficiency. Using conventional techniques, the samples collection delay shows the flocculating efficiency higher than the real rate. The whole bioflocculation process was performed within 11 min in bioflocculator. However, using conventional techinques, the whole bioflocculation process was conducted within 17 min because of the manual sampling. Besides that, bioflocculator is cost-effective, high throughput, automated, and control system for real-time turbidity measurements of cationized bioflocculant. Meanwhile, the results can be posted online via PLX-DAQ. The data obtained from the online measurements were able to easily analysed. The data retrieved via PLX-DAQ can also be plotted to make graphs, tables and figures. However, using conventional techniques for turbidity measurements, data need to be manually collected and analysed, which cause time-consuming.