Introduction:

Humic acid is an organic origin fertilizer that improves soil conditions and favors the plants development. Filter cake, a waste from sugar production, is a rich and renewable source of organic matter.

Objective:

To determine operational conditions of humic acid from filter cake extraction process

Materials and Methods:

The extraction is carried out in two stages, a basic treatment with sodium hydroxide and then with sulfuric acid. A central compound experimental design is planned, with the solid-liquid ratio and treatment time as variable factors. The process is optimized from response surface graphs. Multiple regression analysis is applied to obtain the mathematical models that allow to predict optimal conditions.

Results and Discussion:

Filter cake had a 74.57%, organic matter content which indicates a high degree of maturation of the organic source; in addition, it presents a pH equal to 6.2 and 65.02% of humidity. The optimal conditions obtained were solid-liquid ratio equal to 0.12 g/ml and 10 h of extraction in each stage, with a humic acid extraction percentage equal to 15.37% and a gross profit of 694.23 $/h.

Conclusions:

With a 10% level of significance, solid-liquid ratio and extraction time, influence in humic acid from the filter cake extraction process. A 15.37% extraction of organic matter is obtained in humic acid.

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