Effects of pilot‐plant photochemical pre‐treatment (UV/H2O2) on the biodegradability of aqueous linear alkylbenzene sulfonate (LAS)

Mehrab Mehrvar,Gelareh Bankian Tabrizi,Nabil Abdel-Jabbar

doi:10.1155/s1110662x05000255

Abstract

The effects of the photochemical pre‐treatment by using a pilot‐plant UV/H2O2 process on the biodegradability of aqueous linear alkylbenzene sulfonate (LAS) were studied. It was observed that the photochemical pre‐treatment of the LAS solutions by UV‐254/H2O2 increased the biodegradability of LAS solutions. Aqueous solutions with higher concentrations of LAS (> 100 mg/L) were non‐biodegradable. The ratio of BOD5/COD of the pre‐treated LAS solutions was increased, indicating that the pre‐treated LAS solutions were more biodegradable. This ratio was improved as the LAS solutions were more pre‐treated. Also, the biodegradability factor for the pre‐treated LAS solutions was increased as the time of the photochemical pre‐treatment was increased.

Highlights

Linear alkylbenzene sulfonate (LAS) is the major anthropogenic source of organic compounds in primary sludge in municipal wastewater treatment plants
To decompose 60 mg/L of H2O2, 0.1 mg of catalase was added to 100 mL of sample without stirring for 100 min [16]
The concentration of H2O2 was measured by DPD method and it was observed that its concentration was close to zero

Summary

INTRODUCTION

Linear alkylbenzene sulfonate (LAS) is the major anthropogenic source of organic compounds in primary sludge in municipal wastewater treatment plants. LAS and its intermediates are degradable in activated sludge system by consortia of aerobic microorganisms up to 99.5 and 99.1%, respectively [5, 6]. It has been reported that the intermediates produced by biological treatment are 10–100 times less toxic than the parent compounds [2]. It has been reported that LAS with the concentrations of less than 10 mg/L is biodegradable under aerobic activated sludge treatment and its degradation follows Monod’s equation over the ranges of 0.1–20 mg/L [9]. It has been reported that the fate of LAS can follow first order kinetics for the similar ranges of concentrations [10]. Aqueous LAS degradation is possible by different chemical processes [12].

EXPERIMENTAL SET-UP AND PROCEDURES

RESULTS AND DISCUSSIONS

CONCLUSIONS