Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 801, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2021.149609
Keywords
Sewage sludge; Anaerobic digestion-solar drying-land utilization; Heavy metals; Nutrients; Persistent organic pollutants; Particle size distribution
Categories
Funding
- Scientific Research Project of China Three Gorges Corporation, China [202003081]
- National Natural Science Foundation of China (NSFC) [51878469]
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The study investigated the variations of multiple substances and particle size distribution during the sludge treatment process, demonstrating the positive effect of anaerobic digestion on the removal of pollutants. The degradation of extracellular polymers led to the deterioration of sludge dewatering performance. Changes in nutrients and water content during solar drying were beneficial for subsequent land utilization of the sludge product.
Sewage sludge was rich in pollutants such as heavy metals, nutrients and persistent organic pollutants. Anaerobic digestion can effectively degrade the pollutants while achieving sludge stabilization and reduction. This study took a sludge treatment plant located in Anhui Province, China as a case study, investigating the variations of multiple substances and particle size distribution during sludge anaerobic digestion-solar drying-land utilization process. The results demonstrated anaerobic digestion had a positive effect on the removal of heavy metals, nutrients and persistent organic pollutants, for polycyclic aromatic hydrocarbons, antibiotics and disinfection by-products with 41.38%, 62.26% and 68.68%, respectively, which were related to their molecular weight and structure. Large amounts of heavy metals would flow away with liquid digestate, in which Cr and Hg were the most and least, 90.44% and 41.95% respectively. The degradation of extracellular polymers in this process led to a decrease in particle size distribution, which caused the deterioration of sludge dewatering performance. Nutrients and water content increased and decreased respectively during solar drying along with the volatilization of organic matter under high temperature, which was beneficial for the final sludge product to subsequent land utilization. No significant correlation was demonstrated between heavy metals and sludge properties besides electrical conductivity. The study provided a new thinking on the variations of different substances and the way of actual treatment and disposal from the perspective of sludge anaerobic digestion-solar drying-land utilization process, which had a considerable significance for the further promotion and application of anaerobic digestion process in China's engineering community. (c) 2021 Elsevier B.V. All rights reserved.
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