A study on the effects of pH buffering on various wastewater characteristics from a denim finishing plant using the fluidized-bed reactor system

Date of Publication


Document Type

Master's Thesis

Degree Name

Master of Science in Chemical Engineering

Subject Categories

Chemical Engineering


Gokongwei College of Engineering


Chemical Engineering

Thesis Adviser

Pag-asa Gaspillo

Defense Panel Chair

Carlito Salazar

Defense Panel Member

Servillano Olano,Jr.
Noel Cabigon


This study aims to investigate on the effects of pH buffering on the various wastewater characteristics in the biological treatment of denim finishing wastewater, making use of the fluidized-bed reactor system. It includes the determination of the minimum fluidization velocity, as well as the determination of the microorganisms that predominate in such wastewater. For the determination of the minimum fluidization velocity, visual observation was used as criterion. The microorganisms are from a mixed culture from a denim finishing plant, which utilizes the attached growth activated sludge process. Denim finishing wastewater is biologically treated in the three-phase fluidized-bed reactor via the continuous mode of operation employing activated carbon granules as the solid support particles. Samples are collected for BOD5, COD, TS, TSS, TDS, and color analyses. For the application of pH buffering, the same set of experiments is done except that the pH of the incoming wastewater is maintained at 7.2 +/- 0.1 with the use of phosphate buffer.

A relatively high BOD removal was achieved with 5-day fluidization. BOD reductions were nearly consistent at 80 percent and 40 percent with and without the application of pH buffering, respectively. Reductions in COD did not improve with the application of pH buffering, except for wastewater with pH range of 9 to 10. Percent reductions in COD ranged from 18 percent to 36 percent. Solid reductions in terms of TS, TSS, and TDS increased with the addition of phosphate buffer. Percent reductions in TS ranged from 22.5 percent to 84.5 percent in TSS, from 48 percent to 86 percent in TDS, from 27 percent to 85 percent. Color removal also improved with the addition of phosphate buffer. Percent reductions in color changed from 4.92 percent to 76.67 percent.

Abstract Format






Accession Number


Shelf Location

Archives, The Learning Commons, 12F Henry Sy Sr. Hall

Physical Description

104 leaves


Sewage -- Purification -- Biological treatment; Factory and trade waste; Denim; Fluidized reactors; Hydrogen-ion concentration; Buffer solutions; Garment industry

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