Meeting the safe sludge matrix with liquid lime

I have uploaded this excellent piece by Southern Water on the liming of digested municipal sludge; titled "Low Dose Liming of Digested Liquid Sludge" as presented at the 19th European Biosolids & Organic Resources Conference & Exhibition, still worth looking over again in my opinion. Abstract:

Southern Water (SW) was seeking a low cost alternative to the operation of thermal drying plant post digestion for sludge treatment. A land-bank survey indicated sufficient land-bank within the region for biosolids treated to conventional standards as defined by the Safe Sludge Matrix. After bench scale laboratory trials SW decided to pursue lime dosing as an add on treatment process in order to ensure robust compliance. Results indicated that pH increases to 8.5 in the digested sludge stream and a lime dose rate of 1% were sufficient to achieve biosolids compliance.


  1. Post MAD low dose liquid liming is a low-cost, energy efficient and sustainable treatment process for the production of biosolids compliant to conventional standards.
  2. Lime dosing to produce a pH of 8.5 in the treated biosolids provides sufficient bacteriological reduction in the final product to maintain compliance with the SSM as well as zero odour nuisance.
  3. Improved mixing of liquid lime into the digested sludge stream results in improved bacteriological compliance.