Use of ballasted flocculation (BF) sludge for the manufacturing of lightweight aggregates

Kang Hoon Lee; Muhammad Qasim; Ki Gang Lee; Muhammad Ali Inam; Imtiaz Afzal Khan; Rizwan Khan; Young Min Wie

doi:10.1016/j.jenvman.2021.114379

Use of ballasted flocculation (BF) sludge for the manufacturing of lightweight aggregates

J Environ Manage. 2022 Mar 1:305:114379. doi: 10.1016/j.jenvman.2021.114379. Epub 2021 Dec 24.

Authors

Kang Hoon Lee¹, Muhammad Qasim², Ki Gang Lee³, Muhammad Ali Inam⁴, Imtiaz Afzal Khan⁵, Rizwan Khan⁶, Young Min Wie⁷

Affiliations

¹ Department of Civil &Environmental Engineering, Hanyang University, 222 Seongdong-gu, Seoul, 04763, South Korea. Electronic address: diasyong@hanyang.ac.kr.
² Department of Civil &Environmental Engineering, Hanyang University, 222 Seongdong-gu, Seoul, 04763, South Korea. Electronic address: engrqasim00@hanyang.ac.kr.
³ Department of Materials Engineering, Kyonggi University, Suwon, Gyeonggi-do, 16227, South Korea. Electronic address: gglee@kyonggi.ac.kr.
⁴ Institute of Environmental Sciences and Engineering (IESE), School of Civil and Environmental Engineering (SCEE), H-12 Campus, National University of Sciences and Technology (NUST), Islamabad, 44000, Pakistan. Electronic address: ainam@iese.nust.edu.pk.
⁵ Department of Civil &Environmental Engineering, Hanyang University, 222 Seongdong-gu, Seoul, 04763, South Korea. Electronic address: imtiaz1234@hanyang.ac.kr.
⁶ Department of Chemical Engineering, Quaid-e-Awam University of Engineering, Science and Technology (QUEST), Nawabshah, 67480, Pakistan. Electronic address: rizwansoomro@quest.edu.pk.
⁷ Department of Materials Engineering, Kyonggi University, Suwon, Gyeonggi-do, 16227, South Korea. Electronic address: supreme98@kyonggi.ac.kr.

PMID: 34959062
DOI: 10.1016/j.jenvman.2021.114379

Abstract

Ballasted flocculation (BF) is an efficient way to remove the turbidity from surface water. The objective of the present study is to optimize the ballast (magnetite), coagulant (poly aluminum chloride) concentration and pH for efficient turbidity removal from surface water. To do this, the sludge produced from an optimized dose of a BF treatment was utilized for the production of lightweight (LW) aggregates by combining it with hard clay and sewage sludge. The LW aggregates were formed by means of rapid sintering in the temperature range of 1000-1200 °C with an exposure time of 10 min. The physical properties of the LW aggregates, in this case the leaching of heavy metals, the bulk density and the microstructure, were investigated. The results indicated that corresponding ballast and coagulant concentrations of 0.75 g/L and 30 mg/L (poly aluminum chloride (PAC)) resulted in the maximum removal efficiency of ≈95%. Using a mixture of BF sludge (30 wt%), dry sewage sludge (20 wt%), and hard clay (50 wt%), aggregates with a density of around 1.0 g/cm³ could be produced. In addition, it was confirmed that the manufactured aggregate was environmentally stable as the elution of heavy metals was suppressed.

Keywords: Artificial aggregates; Ballasted flocculation; Lightweight aggregates; Sewage sludge.

MeSH terms

Clay
Flocculation
Metals, Heavy* / analysis
Sewage*
Water

Substances

Metals, Heavy
Sewage
Water
Clay