Ammonia Salts in Taste Elimination

Abstract

year; second, the desire to retard or prevent during the later summer months bacterial aftergrowths in the sedimentation basin of the slow sand filter plant. Our experience in control of the latter problem is not sufficient to justify discussion here. We are quite well satisfied with regards to minimization of taste the process has been effective. It is important to point out that at no time prior to the use of ammonia has the supply been subject to continued objectionable tastes. In the extreme cold of midwinter, at times of high rainfall in midwinter or early spring, at times in early summer when the water temperature was rising, occasional consumer comments have been made. We believe that Indianapolis has a low rate of comment regarding taste, but not so low as to justify indifference to the conditions. So the ammonia process was studied. The filtration system consists of two plants deriving their supply through a common intake structure. The supply leaves the intake through two 48-inch diameter pipes one leading to each set of filters. The slow sand plant consists of 6 units of a total capacity of 36 m.g.d., the supply for which is first coagulated and then settled in a basin having a detention capacity of 1.25 days at maximum rates. During the recent months low demand has increased the detention up to 2.5 days. The rapid sand plant has a normal rating of 12 m.g.d. with six-hour settling basins. Recent reduction in demand has increased this detention up to ten hours. Coagulant is applied at the head of each 48-inch pipe and pre-chlorine about ten seconds flow down the line. All filtered water flows to a contact basin where the post chlorine is applied. Approximately thirty minutes elapse before the operator checks the residual chlorine and forty-five minutes before the water reaches the pumps.