title: Mechanism of red mud combined with Fenton's reagent in sewage sludge conditioning.
abstract: Red mud was evaluated as an alternative skeleton builder combined with Fenton's reagent in sewage sludge conditioning. The results show that red mud combined with Fenton's reagent showed good conditioning capability with the pH of the filtrate close to neutrality, indicating that red mud acted as a neutralizer as well as a skeleton builder when jointly used with Fenton's reagent. Through response surface methodology (RSM), the optimal dosages of Fe(2+), H2O2 and red mud were proposed as 31.9, 33.7 and 275.1 mg/g DS (dry solids), respectively. The mechanism of the composite conditioner could be illuminated as follows: (1) extracellular polymeric substances (EPS), including loosely bound EPS and tightly bound EPS, were degraded into dissolved organics, e.g., proteins and polysaccharides; (2) bound water was released and converted into free water due to the degradation of EPS; and (3) morphology of the conditioned sludge exhibited a porous structure in contrast with the compact structure of raw sludge, and the addition of red mud formed new mineral phases and a rigid lattice structure in sludge, allowing the outflow of free water. Thus, sludge dewatering performance was effectively improved. The economic assessment for a wastewater treatment plant of 370,000 equivalent inhabitants confirms that using red mud conditioning, combined with Fenton's reagent, leads to a saving of approximately 411,000 USD/y or 50.8 USD/t DS comparing with using lime and ordinary Portland cement combined with Fenton's reagent, and approximately 612,000 USD/y or 75.5 USD/t DS comparing with the traditional treatment.
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China. Electronic address: jkyang@mail.hust.edu.cn.
authors.forename: Jiakuan
authors.initials: J
authors.lastname: Yang
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China.
authors.forename: Wenbo
authors.initials: W
authors.lastname: Yu
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China.
authors.forename: Sen
authors.initials: S
authors.lastname: Luo
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Peng
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China.
authors.forename: Xingxing
authors.initials: X
authors.lastname: Shen
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China.
authors.forename: Yafei
authors.initials: Y
authors.lastname: Shi
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China.
authors.forename: Shinan
authors.initials: S
authors.lastname: Zhang
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Song
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China.
authors.forename: Nan
authors.initials: N
authors.lastname: Ye
authors.affiliation: Universtar Science & Technology (Shenzhen) Co., Ltd., Shenzhen, Guangdong, 518057, PR China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Li
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China.
authors.forename: Changzhu
authors.initials: C
authors.lastname: Yang
authors.affiliation: School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, PR China. Electronic address: liangsha@mail.hust.edu.cn.
authors.forename: Sha
authors.initials: S
authors.lastname: Liang
mesh_terms: D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D010084:Oxidation-Reduction; D012722:Sewage / Q000737:chemistry*; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods; D014867:Water / Q000737:chemistry
chemical_list: C045076:Fenton's reagent; D012722:Sewage; D014867:Water; D006861:Hydrogen Peroxide; D007501:Iron
keywords: Bound water; Extracellular polymeric substances (EPS); Fenton's reagent; Red mud; Sewage sludge conditioning