Develop a green sludge treatment: Effects of a new additive on sludge properties and co-removal of bound water, organics and toxic elements in sludge. (1st July 2021)

• Record Type: Journal Article
• Authors: Dai, Quxiu; Xie, Longgui; Guo, Zhiying; Yang, Jie; Tian, Guocai; Ma, Liping; Ning, Ping; Ren, Nanqi
• Is Part Of: Journal of cleaner production. Volume 304(2021)
• Publication Date: 2021-07-01
• Subjects: Sludge -- Toxic element -- Immobilization -- Automatic linear regression -- Reduction; Factory and trade waste -- Management -- Periodicals; Manufactures -- Environmental aspects -- Periodicals; Déchets industriels -- Gestion -- Périodiques; Usines -- Aspect de l'environnement -- Périodiques; 628.5
• DOI: 10.1016/j.jclepro.2021.127148
• Languages: English
• ISSNs: 0959-6526

Abstract

Abstract: In this work, a green, cost-saving and energy-saving chemical was produced to dehydrate and detoxify sludge. Variations of chemical properties, and its effects on co-removal of bound water, organics and risky toxic elements (including Cd, Crtotal, Cu, Pb, Zn, Ni and As) from sludge were investigated. Results showed that potential distribution was a key aspect of sludge reduction and detoxification. Cationic chemical could release almost 86% of bound water from sludge through producing potential difference and re-aggregating sludge flocs. Proteins reduction could largely remove organics with molecular weight between 3.5 × 10 3 to 7.5 × 10 3 Da, and moreover, humic acids were highly effective on toxic elements removal due to its ion exchange, chelation and complexation on it. Thus, variations of proteins and humic acids can reflect the distribution of organics and elements in sludge. Approximately 73% of organics was removed in flocculation process, and additionally, 54% of risky toxic elements was removed through chelating process and flocs sweeping, weakening its ecological risk by 53.71%. Comparing with the commonly used cationic polyacrylamide, the product can save 38.05–40.64% of electric energy in releasing per-unit bound water, and also can acquire much more environmental benefit at unit cost. This further suggested that chemical addition was a clean and environmentally sustainable way for sludge reduction and detoxification. Graphical abstract: Image 1 Highlights: Organics (2–6 KDalton) was vital for sludge network destruction. Reducing protein may promote organics removal from sludge. Humic acid was effective on risky heavy metals removal due to its multi-function. Polymer largely reflected the distribution of organics and heavy metals. Potential ecological risk of heavy metals was reduced by 53.71%.