The table below details the nutrient and micronutrient availability over two years for typical applications of cake and limed cake.

Our quality assurance procedure is also detailed.

Product analysis

Potential nutrient availability over first two years following application
Biosolid cake
Dry matter 22.0% Nitrogen 4.5% Phosphate 4.7%
Phosphate (P2O5) 210kg/ha
Nitrogen 79kg/ha
Sulphur (SO3) 63kg/ha
Magnesium (Mg0) 16kg/ha
Biosolids liquid lime cake
Nitrogen 4.35% Phosphate 3.67% Neutralising value 5.4%
Lime equivalent 1.8t/ac 2t/ha
Phophate (P2O5) 182kg/ha
Nitrogen 78kg/ha
Potash 7kg/ha
Sulphur (SO3) 49kg/ha
Magnesium (Mg0) 19kg/ha

Application rate of 25t/ha based on total of 250kg total N/ha

Quality assurance with HACCP

Southern Water incorporates Hazard Analysis Critical Control Point (HACCP) quality assurance systems within its treatment processes.

These systems ensure that the required bacterial standards for biosolid products are guaranteed.

The HACCP system was developed in the food industry to ensure that the required standards at each process stage are continually met.

In the UK the same HACCP approach has been adopted by the Water Industry for its treatment of raw sludges to treated biosolids.

Under this system limits are set for factors which are critical to maintaining end product quality.

These factors are defined as Critical Control Points (CCPs) under the HACCP system. By operating the treatment process within the CCP limits, the end product quality is assured.