Guideline for pH Adjustment of Biosolids

If lime or a similar chemical is used to treat the sludge, BioVir clients should consider the following guidelines for immediate adjustment (neutralization) of biosolids pH after sampling:

Weigh out a minimum of 34g (dry weight) for a full Class A, 503 set of analyses (Fecal Coliform, Salmonella, Helminth Ova and Enteric Virus).

If necessary, depending upon the percent solids, add sufficient volume of buffered dilution water (see Standard Methods 18th, 9050C) to give sufficient fluidity to conveniently measure and adjust the pH. Use 5M HCL to adjust the pH to approximately 7 and record the volume of dilution water and HCL added. Include this information with the sample shipping information.

A minimum concentration of high pH biosolids in the slurry is about 10% dry weight. Do not add a volume of buffered dilution water and acid that would result in a lesser concentration of biosolids.

  • Examples:

  • Example #1. Wet Sample

    Assume the solids concentration in the sludge is 10% dry weight; weigh out a minimum 340g of the "wet" material and record the weight. This sample should be liquid enough to allow for the adjustment of the pH without the addition of dilution water. Adjust the pH with 5M HCL and record the volume of acid added. Send the adjusted sample to the laboratory accompanied with the pertinent sample information (biosolids % dry wt., wet wt. of sample; and, volume of acid added) including final pH.

    Example # 2. Dry Sample

    Assume the solids concentration in the sludge is 80% dry weight. Weigh out a minimum 43g of the "wet" material and record the weight. Add the minimum volume of buffered dilution water required to conveniently make pH measurement and adjustment (do not exceed 500 mL). Record the volume of dilution water and acid added. Send the adjusted sample to the laboratory accompanied with the pertinent sample information (biosolids % dry wt., wet wt. of sample; and, volume of dilution water and acid added) including final pH.

     

     

     

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