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. 2022 Feb 16;15(4):1475.
doi: 10.3390/ma15041475.

Humus Acids in the Digested Sludge and Their Properties

Anna M Anielak  1 , Aneta Kłeczek  1
Affiliations

Humus Acids in the Digested Sludge and Their Properties

Anna M Anielak et al. Materials (Basel). .

Abstract

Fulvic acids, alpha (α) humic acids and hymatomelanic acids were extracted digested sludge in two Cracow sewage treatment plants: Kujawy and Płaszów. Their elemental composition was examined and micropollution and ash content were determined. Based on the IR and UV-VIS spectrum, their similarities were determined with the occurring interactions with micropollution. Strong correlations between the acids coming from different sources depend on acid type and micropollution accompanying them, depending on concentration, influences to a specific extent their IR and UV-VIS spectra. Absorption analysis in infrared constitutes a simple method for characterizing fulvic and humic acids from wastewater treatment plants. The extracted fulvic acids were characterized by moderate maturity, while humus acids were well developed. In the fermentation process, the N bond increases together with the level of humification of the humus acid. The characteristics of the extracted humus acids comply with other humic substances presented in the literature. Quantitative analysis showed that digested sludge contains, on average: FA from 5.07 to 5.30 g/kg dry matter, αHA from 59.22 to 74.72 g/kg dry matter, HMA from 20.31 to 43.66 g/kg dry matter. It was thus demonstrated that wastewater treatment, in particular digested sludge, constitutes an attractive source of humus acids with a wide range of applications in numerous areas, such as agriculture, ecological rehabilitation, environmental protection, animal breeding, aquaculture, veterinary as well as medicine and is a precious source of soil fertilizers.

Keywords: alpha (α) humic acids; digested sludge; fulvic acids; humus acids; hymatomelanic acids.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 1
Scheme 1
Technological system for extraction of humic substances from digested sludge.
Figure 1
Figure 1
Infrared (FTIR) spectra HAs were recorded from digested sludge of the Płaszów plant: FA-Płaszów, αHA-Płaszów, HMA-Płaszów and form digested sludge of the Kujawy plant: FA-Kujawy, αHA-Kujawy, HMA-Kujawy.
Figure 1
Figure 1
Infrared (FTIR) spectra HAs were recorded from digested sludge of the Płaszów plant: FA-Płaszów, αHA-Płaszów, HMA-Płaszów and form digested sludge of the Kujawy plant: FA-Kujawy, αHA-Kujawy, HMA-Kujawy.
Figure 2
Figure 2
UV-VIS spectra of humus acids extracted from digested sludge of the Kujawy wastewater treatment plant.
Figure 3
Figure 3
UV-VIS spectra of humus acids extracted from digested sludge of the Płaszów wastewater treatment plant.
Figure 4
Figure 4
Effect of HAs, nitrogen fertilizer and phosphorus on the growth of Sorghum saccharatum. (A) Has. (B) nitrogen fertilizer. (C) phosphorus fertilizer.
See this image and copyright information in PMC

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