Bioproducts for Sludge Reduction in Activated Sludge Systems Treating Oil Refinery Wastewater

V.M.F Alexandre,V.M.J Santiago,A.C.F.P De Cerqueira,M.C Cammarota

doi:10.2516/ogst/2015002

Abstract

The use of bioproducts that change the cellular metabolism and reduce microbial growth without affecting the organic matter removal is very promising for reducing the amount of sludge in wastewater treatment systems. In this study, two bioproducts were evaluated and compared with a well-known chemical (2,4-DiNitroPhenol – DNP) in activated sludge treating petroleum refinery wastewater. In batch experiments, 10 mg/L of DNP, 0.8 mg/L of a bioproduct based on Folic Acid (FA) and 10 mg/L of a bioproduct based on Stress Proteins (SP) led to 30.6%, 43.2% and 29.8% lower disposal of total solids, respectively. Operating on a continuous regimen, the addition of 10 mg/L of the bioproduct based on SP led to 45.7% lower disposal for 50 days. In all cases, no loss of efficiency in the Chemical Oxygen Demand (COD) removal was observed.

Highlights

Despite the development of new technologies and products such as biofuels, oil still has great commercial importance and will continue to play a critical role in the global energy industry for many decades, especially with the discovery of the pre-salt layer [1].Oil refineries process extremely high volumes and are major contributors to pollution, both in volume and in the concentration and toxicity of contaminants [1, 2].Among the solid wastes generated in an oil refinery, oily residues, sediments from the bottom of storage tanks, treatment clays, biological sludge, residues arising from the cleaning of heat exchangers and solid materials contaminated with oil stand out [3]
Three commercial products were used: DNP (Vetec, Brazil), one bioproduct based on Folic Acid (FA) (Neotex, Brazil) and one bioproduct based on chemical surfactants and Stress Proteins (SP) produced by Saccharomyces cerevisiae (Advanced Biocatalytics Corporation, USA)
The Chemical Oxygen Demand (COD) in the feed of both bioreactors varied considerably during the experiment because the wastewater was collected at different operating conditions in the industrial plant

Summary

Introduction

Among the solid wastes generated in an oil refinery, oily residues, sediments from the bottom of storage tanks, treatment clays, biological sludge, residues arising from the cleaning of heat exchangers and solid materials contaminated with oil stand out [3]. In studies evaluating in detail the management of solid waste in oil refineries, biological sludge is little discussed. Wastewaters generated by oil refining plants have variable composition, depending on the units in operation and type of oil processed [1, 5]. Regardless of their characteristics, the activated sludge system is one of the most used in the treatment of these wastewaters. Even accounting for only 1-2% of the total volume of treated wastewater, the cost of managing the excess sludge can reach 60% of the total operating cost of the refining plant [4]

Objectives

Methods

Results