Ref ID : 7189
R.D. Vashon, W.J. Jones, and A.G. Payne; The Effect of Water Hardness on Nitrilotriacetate removal and Microbial Acclimation in Activated Sludge. Water Research 16:1429-1432, 1982
Reprint
In File
Notes
The effect of water hardness on microbial acclimation to the removal of nitrilotriacetate (NTA) in the wastewater treatment process was examined in 4 laboratory-scale activated sludge reactors. Consistent high removal (i.e. >90%) was observed in all 4 reactors after acclimation occurred. Removals of greater than 60% of added NTA after 8 days and greater than 90% after 15 days were observed in a continuously fed, hard water (250 mg l-1 as CaCO3) reactor. In soft water (50 mg l-1 as CaCO3) comparable removals were observed after 20 and 28 days respectively. In 24 hr, semi-continuous activated sludge reactors (24 hr, fill-and-draw type) removal was greater in hard water than in soft water initially, but was greater than 95% in both hard and soft water after 4 weeks. The proportion of bacteria in the activated sludge with the ability to utilize NTA increased approx. 100-fold during the acclimation period. This proportion increased faster in hard water than in soft water and faster in semi-continuous activated sludge reactors than continuous activated sludge reactors. Ultimate biodegradation of 14C[U]NTA was greater than 85% in both hard and soft water acclimated units. Accumulation of 14C in the sludge solids was negligible (<1%).