Abatement of gaseous VOCs using activated sludge systems: Technology feasibility and cost analysis

 

Sustain. Environ. Res., 22(5), 295-303 (2012)

 

AUTHORS

Wen-Hsi Cheng and Yi-Chin Fang

KEY WORDS

Volatile organic compounds (VOCs), emission, wastewater treatment plant (WWTP), VOC tax, Water 9

ABSTRACT

This study assessed the air exhaustion control of corrugated plate interceptor (CPI) oil separators in a refinery wastewater treatment plant for biodegradation of volatile organic compounds (VOCs) by deep activated sludge aeration systems. Three approaches were used to derive VOC emission factors: (a) Calculating using the aeration rate and VOC gas-liquid equilibrium concentration (Cg*), (b) Simulation using the Water 9 model, and (c) VOC mass balance calculation. Based on field sampling and laboratory analysis, lipophilic alkanes (900-1,200 ppm as total hydrocarbons (THCs)) were removed by the activated sludge system and only 0.40-0.60 ppm THC VOCs were emitted, and VOC emission factors were 0.055-0.548 g m-3 wastewater using the different calculation approaches. We recommended using the Cg* and installed air aeration rates as more effective accurate method for  simulating VOC emissions rates than examining individual aqueous VOC concentrations for Water 9 model simulation. In comparing with the capital costs of reconstructing pipelines from CPI oil separators to the activated sludge system as well as those of sampling and analysis, to pay legal VOC taxes, the former demonstrates its economic efficacy of reducing the amount of VOC exhausts.

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