Excessive propagation of tubificid in eutrophic source water can result in its emergence in the drinking water plant, which has been a troublesome problem in recent years. The migration of tubificid, especially drift migration in the source water is the main cause of worm pollution in drinking water plant. Migration modes and correlative factors of Tubifex tubifex, dominating the tubificid frequently, were investigated to help drinking water plant to solve worm pollution. Migration modes were divided into superficial, deep and drift migrations, representing migrations occurring in surface sediment (0–2▒cm), deep sediment (deeper than 2▒cm) and from sediment to overlying water, respectively. The results showed that both temperature and dissolved oxygen (DO) affect the worm migration modes. The maximum drift efficiency occurred at 22°C while DO was controlled around 8▒mg▒O2▒l−1. When the temperature was fixed at 20°C, maximum drift efficiency was observed at 2▒mg▒O2▒l−1. Distinct increase of superficial migration and decrease of deep migration were observed at 28°C compared to 16 and 22°C. Low DO appeared to be the main reason for the increase of worm’s deep migration. The results confirmed that worm drift from sediment to overlying water, which was influenced by the temperature and DO content, was the main cause of worm pollution in the drinking water plant.
Keywords: dissolved oxygen (DO), migration mode, temperature, Tubifex