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Settleability and dewaterability of sewage sludge with modified diatomite
Ling-Yu Wang1, Xue Li2, Kun Luo1
1College of Biological and Environmental Engineering, Changsha University, Changsha, 410022, China.
Environmental Science and Pollution Research International
|April 23, 2022
Summary
Cationic polyacrylamide (CPAM)-modified diatomite significantly improves sewage sludge dewatering and settling performance compared to CTAB-modified diatomite. This novel conditioner enhances sludge cake dewaterability and reduces filtration resistance.
Area of Science:
- Environmental Engineering
- Materials Science
- Water Treatment
Background:
- Sewage sludge dewatering and settling are critical for efficient wastewater treatment.
- Diatomite, a natural porous material, has potential as a sludge conditioner.
- Modification of diatomite can enhance its performance in sludge treatment.
Purpose of the Study:
- To synthesize and evaluate CPAM-modified and CTAB-modified diatomite as conditioners for sewage sludge dewatering.
- To compare the effectiveness of CPAM-modified diatomite versus CTAB-modified diatomite.
- To elucidate the mechanisms behind the improved sludge dewaterability and settling.
Main Methods:
- Synthesis of cationic polyacrylamide (CPAM)-modified diatomite and cetyl trimethyl ammonium bromide (CTAB)-modified diatomite.
- Testing the performance of modified diatomites as conditioners for activated sludge dewatering and settling.
- Analysis of sludge properties including specific resistance to filtration (SRF) and water content.
- Mechanism investigation using scanning electron microscopy (SEM) and analysis of extracellular polymeric substances (EPS).
Main Results:
- CPAM-modified diatomite demonstrated superior performance over CTAB-modified diatomite in improving sludge settleability and dewaterability.
- Addition of 0.4% CPAM-modified diatomite at pH 3.5 reduced SRF from 8.52 × 10^12 to 0.92 × 10^12 m/Kg.
- Water content in the sludge cake decreased from 92.2% to 68.1% with CPAM-modified diatomite treatment.
- Modified diatomites improved dewaterability by stripping EPS and damaging sludge structure, facilitating bound water release.
Conclusions:
- CPAM-modified diatomite is an effective conditioner for enhancing sewage sludge dewatering and settling.
- The porous structure of modified diatomite is maintained, with improved uniformity and completeness.
- The findings offer a promising approach for improving sludge management in wastewater treatment plants.
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