Development of settling flux curves using SVI: An addendum

Abstract

An earlier paper by the authors (1988) introduced a correlation between the Vesilind settling parameters, Vo and K, and SVI performed in a stirred, 1‐L graduated cylinder even though SVIs also were determined in more commonly used containers such as an unstirred, 1‐L graduated cylinder and an unstirred, 2‐L Mallory settlometer. Only the stirred graduated cylinder relationship was given because stirring increases the precision and decreases the variability of the SVI test, and Standard Methods (1975) has included stirring in the SVI test since 1975. Nonetheless, because the SVI test continues to be performed in unstirred containers, the correlations for the other SVI test methods measured during the study are presented herein so that they can be used by the wastewater treatment plant operations community.

An evaluation of the performance and optimization of a new wastewater treatment technology: the air suction flow-biofilm reactor

“…Wahlberg and Keinath [25] noted that the methods proposed in the Standard Methods (APHA) are not used by most wastewater plant operators who use the SVI test. SVI tests are regularly carried out in a simpler manner that does not make use of stirring and has been shown to be effective.…”

“…The hydraulic loading rate during Study 2 was 10.2 l/d equating to area loading rates averaging 2.49 g COD f /m 2 media/d, 0.24 g TN f /m 2 media/d, 0.20 g NH 4 -N/m 2 media/d and 0.064 g PO 4 -P/m 2 media/d. Volumetric loading rates averaged 257.55 g COD f /m 3 reactor/d, 25.00 g TN f /m 3 reactor/d, 20.69 g NH 4 -N/m 3 reactor/d and 6.56 g PO4-P/m 3 reactor/day. Prior to the start of Studies 1 and 2 the reactors were seeded with activated sludge from a local municipal wastewater treatment plant that was achieving nitrification.…”

“…Total nitrogen concentrations were reduced from 207 mg TN/l to an average of 38.2 g TN/l, representing a removal of 82%, at a rate averaging 0.24 g TN f /m 2 media/d or24.90 g TN f /m 3 reactor/d. Filtered total nitrogen concentrations were reduced from 199.4 mg TN f /l in the influent to an average of 23.6 mg TN f /l in the effluent -an 88% reduction at a removal rate averaging 0.24 g TN f /m 2 media/d or25.84 g TN f /m 3 reactor/d.In Study 2, influent concentrations averaging 164.1 mg NH 4 -N/l were reduced by 98% to an average effluent concentration of 3.0 mg NH 4 -N/l. Average removals of 0.21 g NH 4 -N/m 2 media/d and 21.27 g NH 4 -N/m 3 reactor/d were observed.…”

Finite element analysis of flows in secondary settling tanks

“…values to simple sludge settleability parameters (for example, Ekama & Marais (1986), Wahlberg & Keinath (1988), Hltrtel & POpel (1992, and many others). A comprehensive list and a critical review of these relationships is given by Ekama et al (1997).…”

“…Various attempts have been made to determine the settling velocity as a function of the sludge concentration and the sludge volume index (SVI) (see Section 2.4). Such settling approaches can be found for example in Wahlberg & Keinath (1988). The required parameters of these settling functions are calibrated in sedimentation experiments under different activated sludge concentrations.…”