Settleability and Dewaterability of Sewage Sludge with Modified Diatomite

Abstract

In this study, cationic polyacrylamide (CPAM) modified diatomite and cetyl trimethyl ammonium bromide (CTAB) modified diatomite were synthesized and used as conditioner in sewage sludge dewatering. The effects of these two types of modified diatomite on the dewaterability and settling performance of activated sludge were studied. The mechanism of the two types of modified diatomite in the activated sludge system was elucidated. The efficiency of CPAM-modified diatomite was better than that of CTAB-modified diatomite in improving the settleability and dewaterability performance of sludge. The results indicated that specific resistance to filtration (SRF) was decreased from 8.52×1012m/Kg to 0.92×1012 m/Kg, and the water content in the remaining sludge cake after pumping filtration was decreased from 92.2% to 68.1%. by adding 0.4% of CPAM-modified diatomite and pH=3.5, which result in optimal sludge settling of activated sludge. Further studies showed that the polymer/surfactant adsorbed in diatomite increased sludge dewaterability and improved the sedimentation rate as a result of stripping extracellular polymer substances (EPS) and damaging the internal structure of sludge conduce bound water releasing. According to scanning electron microscope(SEM) images, two types of modified diatomite powder not only kept the porous, but also shown more complete and uniform structure in comparison to nature diatomite.

Quaternization-based Graft Modification of Straw Fibers for Conditioning the Sludge Dewatering Performance

“…The straw becomes adsorptive and rigid after modi cation, making it a suitable skeleton-aided ltration conditioning agent for sludge dewatering [10,11]. Wang et al grafted polyacrylamide onto calcium lignosulfonate using graft copolymerization, which decreased the moisture content of active sludge from 85.64 ± 0.25% to 76.84 ± 0.41% and reduced the sludge SRF from 0.61 ± 0.05 × 10 12 to 0.14 ± 0.02 × 10 12 m/kg to show a good conditioning effect on the sludge [12]. Besides, grafting additional functional groups onto rice straw contributed to its functionality, such as a stable and rigid structure and a high adsorption capacity [13].…”

Energy-water-climate governance from interdisciplinary perspectives

“…The first paper is entitled "Settleability and dewaterability of sewage sludge with modified diatomite" (Wang et al 2022a) that aims to investigate the role of modified diatomite particles in the dewatering performance of an activated sludge system. A typical polymer (CPAM) and surfactant (CTAB) were used to modify diatomite, respectively.…”

“…The third paper is entitled "From waste tire to high-valueadded chemicals: an analytical Py-GC/TOF-MS study" (Wang et al 2022b). It mainly focuses on the anlysis of the decomposition behavior of waste tire using a Pyroprobe 5000 pyrolyzer connected to a gas chromatography-timeof-flight mass spectrometry (Py-GC-TOF-MS).…”