Optimization of ozonation process for the reduction of excess sludge production from activated sludge process of sago industry wastewater using central composite design.

B Subha,M Muthukumar

doi:10.1100/2012/239271

Abstract

Sago industries effluent containing large amounts of organic content produced excess sludge which is a serious problem in wastewater treatment. In this study ozonation has been employed for the reduction of excess sludge production in activated sludge process. Central composite design is used to study the effect of ozone treatment for the reduction of excess sludge production in sago effluent and to optimise the variables such as pH, ozonation time, and retention time. ANOVA showed that the coefficient determination value (R 2) of VSS and COD reduction were 0.9689 and 0.8838, respectively. VSS reduction (81%) was achieved at acidic pH 6.9, 12 minutes ozonation, and retention time of 10 days. COD reduction (87%) was achieved at acidic pH 6.7, 8 minutes of ozonation time, and retention time of 6 days. Low ozonation time and high retention time influence maximum sludge reduction, whereas low ozonation time with low retention time was effective for COD reduction.

Highlights

Sago, the edible starch globules processed from the tubers of tapioca (Manihot esculenta), is the staple diet of middle income populations in India
response surface methodology (RSM) model used for the optimization of the operating condition for maximizing the Volatile suspended solids (VSSs) and Chemical oxygen demand (COD) reduction in ozonation condition
analysis of variance (ANOVA) results showed that the coefficient determination value, (R2) of VSS and COD reduction were 0.9689 and 0.8838, respectively

Summary

Introduction

The edible starch globules processed from the tubers of tapioca (Manihot esculenta), is the staple diet of middle income populations in India. There are 3,226 industries in Tamil Nadu, of these 1,522 are small, 388 medium, and 205 are of larger scale. They produce about 15 to 30 tonne of sago per unit/day and discharge about 40,000 to 50,000 litres of sago wastewater per tonne of sago [1]. Both at medium and large scale, suffer from inadequate treatment and disposal problems. They generate more than 85% of the total wastewater output, and about 400 units discharge directly into rivers. Sago wastewater is complex and acidic in nature with high organic matter, intense COD and BOD, suspended solids, obnoxious odour, and irritating colour [2]

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