Lixiviate Stripping on Manure Treatment Plants
Manure treatment plants using an anaerobic process to produce methane biogas, produce liquid lixiviates with usually dissolved NH3 that has to be stripped before disposing such waters away.
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In such plants usually lixiviates with NH3 dissolved are produced. This ammonia must be degassed before disponsing these waters away.
The most common in this type of plants is to perform a two-step process:
In this first stage, a stripping or degassing of NH3 contained in the liquid effluent is performed. This gets into a stripper in which air is injected counterflow. To promote degassing previously an alkaline pH is set. The obtained liquid is collected in a tank where by means of an automatic pH control, H2SO4 is dossified to obtain a final pH around 7.
In this second stage the air contaminated with NH3 from the previous stage is fed to a scrubber in which a solution of H2SO4 is recirculated, with automatically controlled pH, producing a solution of (NH4) 2SO4 that once reached a concentration close to 40 % is discharged to a storage tank . This concentration is measured by a conductivity controller .
We must emphasize that the air circulates in a closed loop to preserve heat energy , thus favoring the degassing, which would be impossible if outside air is continuously introduced.
It should also be added that if the effluent to be treated has no solids is not expected clogging of the packing. However during the first months of operation it will be necessary inspections of the packing fill and bottom of stripper and scrubber .