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Abstract of the Article

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Investigation on Factors Causing Viscous Bulking and Treatment Method in Activated Sludge System

Authors:
[ Esfahani ] - Member of academic board and project manager, RIPI-NIOC, Tehran, IRAN
[ Soheili ] - Senior researcher RIPI-NIOC, Tehran, IRAN
[ Tarkian ] - Member of academic board and project manager, RIPI-NIOC, Tehran, IRAN

Abstract:

Some of the wastewater treatment plants, which operated by activated sludge process, have viscous bulking problem. In this situation sludge has gelatinous nature and the growth of bacteria is heavily dispersed. Drawbacks of this phenomenon are “increasing SVI”, “High TSS content in effluent” and overall reduction in organic pollutants removal. In this study, high load sugar substances and non- proportionality of monovalent to Divalent Ions ratio are considered important. In This investigation the pilot plant including. Biological selector, aeration basin, secondary clarifier and related chemical injection vessels were used. All tests such as pH, COD, MLSS and MLVSS were ‍carried out based on standard method 1998. Application of biological selector with retention time of about 20 hr. reduces influent pH from 12 to 6.5 and organic load (COD) to about %50. Due to unfavorable ratio of Na/Ca, reduction of bacteria surface hydrophobicity and finally dispersion of flocs were appeared. Calcium salt solution was used to remedy in the way that the equivalent concentration ratio of monovalent to divalent Ions was about 2:1. Application of aforementioned methods improved settling, made flocs stronger and reduced SVI to below 150 ml/mg. The viscous bulking problem was completely solved.

Keywords:

Soft drink industry, Viscous bulking, Activated sludge, Settelability, Monovalent, Divalent, Biological selector