|
| Extraction of humic acid from excess sludge and its effects on crop seedling establishment |
| Received:October 19, 2023 |
| View Full Text View/Add Comment Download reader |
| KeyWord:excess sludge humic acid;extraction condition;seedling establishment;seed germination;cotyledon photosynthetic pigment |
| Author Name | Affiliation | E-mail | | QIAO Sheng | College of Resources and Environment, Shanxi Agricultural University, Taiyuan 030031, China
Shanxi Provincial Key Laboratory of Soil Environment and Nutrient Resources, Taiyuan 030031, China | | | YAN Min | College of Resources and Environment, Shanxi Agricultural University, Taiyuan 030031, China
Shanxi Provincial Key Laboratory of Soil Environment and Nutrient Resources, Taiyuan 030031, China | | | MENG Qiuxia | College of Resources and Environment, Shanxi Agricultural University, Taiyuan 030031, China
Shanxi Provincial Key Laboratory of Soil Environment and Nutrient Resources, Taiyuan 030031, China | | | ZHANG Jiaxing | College of Resources and Environment, Shanxi Agricultural University, Taiyuan 030031, China
Shanxi Provincial Key Laboratory of Soil Environment and Nutrient Resources, Taiyuan 030031, China | | | LUO Yuan | College of Resources and Environment, Shanxi Agricultural University, Taiyuan 030031, China
Shanxi Provincial Key Laboratory of Soil Environment and Nutrient Resources, Taiyuan 030031, China | luoyuansxau@163.com | | YANG Zhiping | College of Resources and Environment, Shanxi Agricultural University, Taiyuan 030031, China
Shanxi Provincial Key Laboratory of Soil Environment and Nutrient Resources, Taiyuan 030031, China | |
|
| Hits: 396 |
| Download times: 304 |
| Abstract: |
| The aim of our study is to solve the problems of unclear parameters of the humic acid extracted from excess sludge using the International Humic Substances Society（IHSS）recommended method and lack of evaluation of the toxic effects of the humic acid. The optimum conditions for the extraction of humic acid from excess sludge were obtained using the response surface methodology, and the physicochemical properties of the humic acid and its effect on crop seedling establishment were analyzed. Results showed that the optimum conditions for humic acid extraction were as follows： alkali concentration of 0.19 mol·L-1, alkali sludge ratio（mL∶g）of 11.6, shaking time of 3.8 h, and extraction amount of 96.1 mg·g-1. Compared with the IHSS recommended method, the amount of the humic acid extracted by this method increased by 118%. Elemental analysis of humic acid showed that the O/C ratio was 0.84, the H/C ratio was 0.14, and the C/N ratio was 4.43. Fourier transform infrared spectroscopy and gel permeation chromatography analyses showed that there were oxygencontaining functional groups such as carboxyl, alcohol hydroxyl, and phenolic hydroxyl groups, and the weight-average molecular weight was 8 856 Da. In addition, the application of humic acid at 500 mg·L-1 did not significantly affected the germination rate and the photosynthetic pigment content of cotyledons of Chinese cabbage and radish seeds, but significantly affected radicle elongation in Chinese cabbage seeds. The extraction amount of humic acid can be significantly increased by optimizing the extraction conditions. Humic acid has high degrees of humification and aromatization, small molecular weight, strong biological activity, and no adverse effect on early growth stage of crops at low concentrations. |
|
|
|
