Volatile fatty acids(VFAs),which are largely generated during the anaerobic acidification process,are considered to be reliable indicators of the stable process operation.However,the common methods for monitoring VFAs are offline,and they are typically manual requir-ing time-consuming,costly and complex instruments.This study aims to develop a novel online analyzer for automatic measuring VFAs,which was based on the 5-pH point titra-tion,embedded with a proportional-integral-derivative(PID)feedback control system.The results show that it can achieve accurate and rapid monitoring of VFAs ranging between 0-400 mg/L(＜9 min/sample)but simultaneously faces the problems of overtitration and in-terference of complex characteristics of wastewater.In order to improve its accuracy and stability,the effects of three general coefficients(KI,KP,and KD)of PID on the titration were investigated,and the optimal values of KI,KP,and KD were found to be 1.5,1.0,and-1.0～0.5,respectively.Besides,the initial titration speed was set at 0.06 mL/min,equal to the mini-mum speed of the peristaltic pump,and the dichotomy approach was integrated into the PID feedback controller.Owing to the above improvements,the relative mean deviation and standard deviation of measuring VFAs in both synthetic and real wastewaters were mostly lower than 5.0％and 5.0 mg/L,proving the online analyzer is rapid,accurate and reliable.

Qingshan Lin;Yanchao Yuan;Feixiang Zan;Hui Lu;Zongping Wang;Gang Guo

School of Environmental Science and Engineering,Huazhong University of Science and Technology(HUST),Key Laboratory of Water and Wastewater Treatment,MOHURD,Wuhan 430074,China;Department of Environmental Science and Engineering,Beijing University of Chemical Technology,Beijing 100029,China;School of Environmental Science and Engineering,Sun Yat-sen University,Guangzhou 510275,China

环境科学学报（英文版）

[1]Qingshan Lin;Yanchao Yuan;Feixiang Zan;Hui Lu;Zongping Wang;Gang Guo-.A novel online analyzer for accurate and rapid measurement of volatile fatty acids in anaerobic wastewater treatment)[J].环境科学学报（英文版）,2022(12):72-82

requir,titra,overtitration

novel,online,analyzer,accurate,rapid,measurement,volatile,fatty,acids,anaerobic,treatment,Volatile,VFAs,which,are,largely,generated,during,acidification,process,considered,reliable,indicators,stable,operation,However,common,methods,monitoring,offline,they,typically,manual,consuming,costly,complex,instruments,This,study,aims,develop,automatic,measuring,point,embedded,proportional,integral,derivative,PID,feedback,system,results,show,that,can,achieve,ranging,between,sample,but,simultaneously,faces,problems,terference,characteristics,In,order,its,accuracy,stability,effects,three,general,coefficients,KI,KP,KD,were,investigated,optimal,values,found,respectively,Besides,initial,speed,set,equal,mini,mum,peristaltic,pump,dichotomy,approach,integrated,into,controller,Owing,above,improvements,relative,mean,deviation,standard,both,synthetic,real,wastewaters,mostly,lower,than,proving

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