Abstract:
The objective of research was to improve the mixing charateristics of equalization tank
located in the wastewater treatment plant of BASF (Thai) Company Limited for capacity
enchancement. Three sets of air diffusers were installed into the equalization tank to improve the
mixing of wastewater. Seven different patterns of mixing positions were operated in the studies.
The wastewater samples were collected from 18 different locations at three different time at 0, 4
and 8 hours within the equalization tank for pH and Chemical Oxygen Demand (COD) analyses.
The results were used to compare the mixing characteristics before and after mixing
improvement. The experimental results indicated that the mixing pattern No. 4 that operated the
mixing positions provided the approximately constant of pH and COD before flowing to the next
treatment process. The best mixing time of 4 hours removed the COD the removal efficiency of
22.9%. Chemical consumptions in the coagulation and flocculation process located next to the
equalization tank including aluminium sulphate, sodium hydroxide, and polymer decresed at the
rates of 42.28%, 56.37% and 45.35%, respectively. Thus, the mixing improvement resulting from
these studies improved the effectiveness of the BASF (Thai) Company Limited wastewater
treatment plant and resulted in the reduction of chemical consumptions.