Method and apparatus for biological treatment of spent caustic

A biological treatment and bioreactor technology, applied in biological water/sewage treatment, water/sewage treatment, water treatment parameter control, etc., can solve problems such as large reactors

Inactive Publication Date: 2011-01-12
SHELL INT RES MAATSCHAPPIJ BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

A disadvantage of the process described in US6,045,695 is that in order to convert the spent caustic to a level low enough to meet today's regulatory requirements for discharge into the environment, very large reactors are required

Method used

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  • Method and apparatus for biological treatment of spent caustic
  • Method and apparatus for biological treatment of spent caustic
  • Method and apparatus for biological treatment of spent caustic

Examples

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Embodiment 1

[0089] Two standard bioreactors of 2 l working volume each were provided and configured to work as continuous cultures. Inoculate the bioreactor with sludge. SOB is taken from full size H mixed with SOB from soda lake 2 S oxidation device. The temperature of the bioreactor was controlled at 30°C by a water jacket, providing an internal temperature of 28±1°C in both reactors.

[0090] The redox potential and pH of each bioreactor were measured online using the redox potential. Nutrients are supplied intermittently by pulse / intermittent pumps or manually. An air supply was provided to the bioreactor to aerate the solution. Set the aeration level so that the redox potential is greater than -100 mV / cm. The air supply is adjusted using a humidifier so that humid air is supplied to the bioreactor. The humidity level of the air supply was set to maintain the liquid level in the bioreactor at a constant level.

[0091] Table 2 shows the composition of the synthetic spent causti...

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Abstract

The invention provides a method and apparatus for biologically treating a spent caustic to provide a treated spent caustic, said method comprising the steps of : (a) passing a spent caustic stream (25) comprising water, alkali metal hydroxide and sulphide to a first bioreactor (30); (b) biologically oxidising sulphide in the first bioreactor (30) with sulphide-oxidising bacteria to form sulphur (S0) and sulphate to provide a partially oxidised spent caustic comprising sulphur (S0) and sulphate; (c) passing the partially oxidised spent caustic to a second bioreactor (40) where at least a portion of the partially oxidised spent caustic is further oxidised with sulphide-oxidising bacteria to generate sulphate from sulphur (S0) to provide a treated spent caustic comprising sulphate.

Description

technical field [0001] The present invention relates to a method and a device for the biological treatment of spent caustic, especially spent caustic having a high chemical oxygen demand (COD), and a device therefor. Background technique [0002] Processes in the natural gas and petroleum refining industries use sodium hydroxide (caustic) solutions to remove hydrogen sulfide (H 2 S) and other organosulfur compounds such as thiols (RSH, R is an alkyl or aryl substituent). Hydrogen sulfide in hydrocarbon streams first dissolves into solution to form aqueous species: [0003] [0004] Aqueous hydrogen sulfide then reacts with hydroxide anions in the caustic solution to form HS - Anions and water: [0005] [0006] Similarly, thiols are converted to RS - . HS - and RS - can be further deprotonated to S 2- . As used herein in the specification and claims, the terms "sulfide" and "sulfide anion" mean S 2- 、HS - or RS - One or all of the anions. [0007] Once the...

Claims

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Application Information

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IPC IPC(8): C02F3/00
CPCC02F2209/04C02F3/345C02F1/444
Inventor A·J·H·詹森
Owner SHELL INT RES MAATSCHAPPIJ BV
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