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Effects of alkalinity on interaction between EPS and hydroxy-aluminum with different speciation in wastewater sludge conditioning with aluminum based inorganic polymer flocculant

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Journal of Environmental Sciences 2021年第2期33卷 257-268页

作者： Weijun Zhang Mingyue Tang Dandan Li Peng Yang Shiwei Xu Dongsheng Wang School of Environmental Studies China University of GeosciencesWuhan 430074China Hubei Provincial Engineering Research Center of Systematic Water Pollution Control Wuhan 430074China School of Civil and Architecture Engineer Northeast Electric Power UniuersityJilin 132012China CECEP Engineering Technology Research Institution Beijing 100082China

Extracellular polymeric substances(EPS)form a stable gel-like structure to combine with water molecules through steric hindrance,making the mechanical dewatering of wastewater sludge considerably ***/flocculation has been widely applied in improving the sludge dewatering performance,while sludge properties(organic fraction and solution chemistry conditions)are highly changeable and have important effects on sludge flocculation *** this work,the alkalinity effects on sludge conditioning with hydroxy-aluminum were comprehensively investigated,and the interaction mechanisms between EPS and hydroxy-aluminum with different speciation were *** results showed that the effectiveness of hydroxy-aluminum conditioning gradually deteriorated with increase in ***,the polymeric hydroxy-aluminum(Al 13)and highly polymerized hydroxy-aluminum(Al 30)were hydrolysed and converted into amorphous aluminum hydroxide(Al(OH)3),which changed the flocculation mechanism from charge neutralization and complexing adsorption to hydrogen bond ***,both Al 13 and Al 30 showed higher binding capacity for proteins and polysaccharides in EPS than monomeric aluminum and Al(OH)*** 13 and Al 30 coagulation changed the secondary structure of proteins in EPS,which caused a gelation reaction to increase molecular hydrophobicity of proteins and consequently sludge *** study provided a guidance for optimizing the hydroxy-aluminum flocculation conditioning of sludge with high solution alkalinity.

关键词： coagulation/flocculation Hydroxy-aluminum Hydrolysis reaction Extracellular polymeric substances

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Evaluation of activated sludge properties’changes in industrial-wastewater pre-treatment:role of residual aluminum hydrolyzed species with different polymerization degree

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Frontiers of Environmental Science & Engineering 2023年第6期17卷 141-151页

作者： Ziqi Zhao Meng Li Wansong Huang Nuowei Guo Qian Zhang School of Civil Engineering and Architecture Wuhan University of TechnologyWuhan 430070China Hubei Jianke International Construction Ltd.Co Wuhan 430070China Wuhan Hanyang Municipal Construction Group Co.Ltd. Wuhan 430000China Shenzhen Research Institute of Wuhan University of Technology Shenzhen 518000China

With the widespread introduction of pre-coagulation prior to the biological unit in various industrial wastewater treatments,it is noteworthy that long-term accumulation of residual coagulants has certains effect on both micro and macro characteristics of activated sludge(AS).In this study,the morphology distributions of residual aluminum salts(RAS)and their effects on the removal efficiency of AS were investigated under different PAC *** results showed that the dominance of medium polymeric RAS,formed under an appropriate PAC dose of 20 mg/L enhanced the hydrophobicity,flocculation,and sedimentation performances of AS,as well as the enzymatic activity in cells in the sludge system,improving the main pollutants removal efficiency of the treatment *** the species composition with monomer and dimer/high polymer RAS as the overwhelming parts under an over-dosed PAC concentration of 55 mg/L resulted in excessive secretion of EPS with loose flocs structure and conspicuous inhibition of cellular activity,leading to the deterioration of physico-chemical and biological properties of *** on these findings,this study can shed light on the role of the RAS hydrolyzed species distributions,closely relevant to Al dosage,in affecting the comprehensive properties of AS and provide a theoretical reference for coagulants dosage precise control in the pretreatment of industrial wastewater.

关键词： coagulation/flocculation Hydroxyl-aluminum Hydrolysis reaction Reactor performance Activated sludge property Surface properties

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Factorial Optimization and Kinetics of Coal Washery Effluent Coag-flocculation By <i>Moringa Oleifera</i>Seed Biomass

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Advances in Chemical Engineering and Science 2011年第3期1卷 125-132页

作者： Matthew Chukwud Menkiti Chukwuka Ikechukwu Nwoye Chinenye Adaobi Onyechi Okechukwu Dominic Onukwuli Department of Chemical Engineering Nnamdi Azikiwe University Awka Nigeria

Factorial optimization and kinetics of coal washery effluent (CWE) coag-flocculation by Moringa oleifera seed has been investigated at room temperature based on standard method of bench scale jar test. Moringa oleifera coag-flocculant (MOC) was produced according to work reported by Ghebremichael. A 23 full factorial central composite design was employed for the experimental design and analysis of results with respect to optimization. The combined effects of pH, dosage and settling time on the particle (turbidity) removal was studied using response surface methodology. Kinetic data generated were confronted with specified kinetic models for the evaluation of functional kinetics parameters. The optimal values of pH, dosage and settling time were recorded at 8,400mg/l and 25 min, respectively. The results of the major kinetic parameters recorded are 2,0.002l/***, and 0.79 min for order of reaction, coag-flocculation reaction rate constant and coagulation period, respectively. The minimum removal efficiency recorded was 95% at 3mins of coag-flocculation. The results, while re affirming MOC as efficient coag-flocculant, confirmed that theory of perikinetics holds for the studied system at the conditions of the experiment.

关键词： Moringa Oleifera Effluent coagulation/flocculation Optimization

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Nephelometric Performance Evaluation of Oxidized Starch in the Treatment of Coal Washery Effluent

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Natural Resources 2014年第3期5卷 79-89页

作者： P. C. Nnaji B. I. Okolo M. C. Menkiti Chemical Engineering Department Michael Okpara University of Agriculture Umudike Nigeria Chemical Engineering Department Nnamdi Azikiwe University Awka Nigeria

This study investigated the coag-flocculation performance of oxidized starch coagulant (OSC) and its blends with alum and FeCl3 in removing turbidity from coal washery effluent at room temperature. A conventional laboratory bench-scale jar test apparatus was employed for the experiments. Coag-flocculation parameters such as reaction order α, rate constant K, coagulation time τ, etc. were determined. The optimum pH was observed at 4.0, while the blend of 30.0 mg/L FeCl3 and 250.0 mg/L OSC achieved the optimum turbidity removal. Turbidity removal efficiency was recorded between 96.0% and 99.9% for various dosages and pH studied. The coagulation rate constants, K recorded range from 9.393 × 10-5 L/*** to 8.294 × 10-1 min-1, while coagulation periods τ, range from 3.8 s to 235.7 s for various dosages and pH studied. The use of OSC blended with FeCl3 showed high level of efficiency, for the treatment of coal washery effluent.

关键词： Oxidized Starch Coal Washery Effluent coagulation/flocculation Jar Test

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