LIZuo-yue,ZHANGYi-biao,SHENYao,et al.Adsorption Characteristics of Microbial Nutrient Stimulants in Sludge Alkaline Thermal Hydrolysate by Biochar with Different Particle Sizes[J].China Water & Wastewater,2025,41(15):8-16.
Adsorption Characteristics of Microbial Nutrient Stimulants in Sludge Alkaline Thermal Hydrolysate by Biochar with Different Particle Sizes
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第41卷
Number:
第15期
Page:
8-16
Column:
Date of publication:
2025-08-01
- Keywords:
- sludge alkaline thermal hydrolysate; biochar; microbial nutrient stimulants (MNS); size effect; adsorption mechanism
- Abstract:
- Microbial nutrient stimulants (MNS) derived from alkaline thermal hydrolysate of activated sludge are rich in nitrogen (N), phosphorus (P), amino acids, minerals, and plant hormones, offering potential benefits for soil improvement, crop quality enhancement, and stress resistance. However, MNS application as water-soluble fertilizers remains limited by nutrient loss and low utilization efficiency. This study systematically investigated the adsorption characteristics and mechanisms of biochar with different particle sizes (40 nm, 45 μm, and 150 μm) on stimulants in MNS. Results showed that all three type of biochar exhibited high carbon content (54.05%-55.95%) but low N and sulfur (S) levels, indicating limited nutrient supplementation capacity as the soil amendment. Adsorption experiments revealed that 40 nm biochar effectively immobilized N substances (total nitrogen, TN; free amino acids, FAA) and P, whereas 45 μm and 150 μm biochar demonstrated superior adsorption capacity of total organic carbon (TOC), with efficiencies of 66.62% and 68.70%, respectively. Notably, adsorption by 150 μm biochar increased P and potassium (K) levels in MNS, suggesting that biochar particle size can modulate nutrient adsorption and release. Additionally, all biochar exhibited high immobilization efficiencies for fluorescent components (tryptophan-like proteins, 98.54%-99.60%), plant hormones and allelochemicals. Functional group and pore structure analysis revealed that nano-sized biochar primarily relied on physical adsorption to immobilize N and P efficiently, whereas micron-sized biochar facilitated nutrient retention through hydrogen bonding, covalent cross-linking, and π-π interactions mediated by surface functional groups, alongside macropore-driven enrichment of macromolecular organic matter. Overall, 45 μm biochar exhibited superior adsorption-desorption equilibrium properties, 40 nm biochar was optimal for controlled N release, and 150 μm biochar enhanced the slow release of P and K. This study proposes biochar particle size-based precision regulation strategy to improve the efficiency of MNS utilization and nutrient release control.
Last Update:
2025-08-01