BIOLOGICAL DESULFURIZATION

Desulphurization is the most difficult part for all biogas engineering projects. Normally Chemical Scrubber costs many NaOH and additives, while Dry Type Desulfurization has to replace the filling mass regularly and cost many manpower.

 

Environtec has completed more than 600 projects for Biological Desulfurization (BDS). Using microbial metabolic principle without consuming any chemicals, BDS has proofed its lowest operating cost and the Best Practice Technology.

 

Environtec manufacturers the big PP-H tower and packing materials in China to reduce the cost. The complete system including all pumps, valves, piping, instrument and control unit are still manufactured in German workshop to ensure the quality. The experienced project management team in China has learned the knowledge of special bacterial, so they are able to provide installation and start-up service smoothly in China and Southeast Asia region.

 

PRINCIPLE

 

A certain amount of air is introduced into the biogas. Then the mixture of raw gas is passed through the ENVIRONTEC reactor for removal of H2S. Inside this reactor a big amount of packing materials (more than 10,000 pieces) are installed to provide a big growth area for bacteria. Nutrient and water solution is recycled over the package continuously. In most cases, the nutrient supply can be from natural source or man-made fertilizer i.e. : Digested waste water ,Liquid phase of digested sludge or manure, Landfill leachate, Artificial fertilizer NPK.

 

H2S + 2O2  → H2SO4

2 H2S + O2  → 2 S + 2 H2O S + H2O + 1.5 O2  → H2SO4

 

 

The sulfuric acid is neutralized by the buffering capacity of the nutrient solution. It is then removed out of the system with PH control and water level control philosophy.

 

 

 

PROCESS DESCRIPTION

 

The raw biogas (3) enters the reactor (1) at the bottom and passes through the package from top to bottom. Air (4) is added at the gas inlet point. The air flow is controlled via the residual oxygen concentration or via the biogas flow meter signal (10). In case of no flow or extremely low gas flow, the air supply is switched off by the security flow switch (16). The water and nutrient solution (7) is stored at the bottom of the reactor and recycled through the package continuously by pump (8). The level of the nutrient solution is controlled by the level switches (13). For best activity of the bacteria, the temperature is controlled by the heat exchanger (9) and the temperature sensor (12). The quality of the nutrient solution is controlled by the PH transmitter (11). Waste nutrient solution (15) is automatically discharged while fresh water is injected to system by adding nutrient supply NPK886 (5) and also dilution water (6).

 

CHARACTERISTICS

    High efficiency: up to 99%

    High scope: up to 1.5% (15000ppm) inlet

    Low cost: the lowest operating cost ccompared with other process

    High security: multiple security devices

    Fully automatic: automatic operation

    Easy operation: easy maintenance work

 

PARAMETERS

    Flow range：50 - 5,000 Nm³ / h

    H2S inlet：500 - 15,000 ppm

    Removal efficiency：90% - 99%

    Inlet temperature：25 - 35 ℃

    Gas pressure：15 - 50 mbar

    Ambient temperature：-30 - + 50 ℃