Analysis of stagnant floodwater quality after treatment with Effective Microorganisms (EM) balls

Abstract

This study aimed to evaluate the quality of stagnant floodwater after treatment with Effective Microorganisms (EM) balls in flood-prone areas of Thawi Watthana District, Bangkok, Thailand. Water samples were collected from three stagnant floodwater sites and treated with EM ball under both field and laboratory conditions for one month. Physical, chemical, and microbiological parameters, including pH, turbidity, biochemical oxygen demand (BOD), dissolved oxygen (DO), total Kjeldahl nitrogen (TKN), total phosphorus, and total coliform bacteria, were determined before and after treatment. The results showed that EM ball improved certain water quality parameters in field conditions, particularly by reducing total coliform bacteria by approximately 7–29-fold in two sampling sites and improving water clarity. However, laboratory-treated samples exhibited higher BOD values (up to 290 mg/L) and lower DO levels (less than 1.0 mg/L), indicating deterioration in water quality under confined conditions. In addition, total coliform bacteria increased substantially in laboratory-treated samples, whereas field-treated samples showed variable responses depending on environmental conditions. These findings indicated that EM ball alone could not consistently improve the quality of stagnant floodwater and that their treatment efficiency depended on the characteristics of the water body and surrounding environmental conditions. Further studies should optimize EM ball formulations, treatment duration, and field application strategies to enhance their effectiveness for sustainable floodwater management. Future research should optimize EM ball formulations, investigate appropriate treatment durations, and evaluate their effectiveness under varying environmental conditions and pollution levels to enhance their practical application for treating stagnant floodwater.