The Characteristics And Effects Of A Reducing Sludge Composited Uncoupler On Treatment Efficiency

Utilizing metabolic uncoupler to reduce the yield of excess sludge was basedon the mechanism of metabolic uncoupling, and the importance of the method wasto disrupt the tightly coupling of catabolism and the synthesis of adenosinetriphosphate (ATP). The application of metabolic uncouplers in activated sludgeprocess could facilitate high-efficient excess sludge reduction performance, while,the oxidation of the substrate still occurred. The objective of this study was toexploit a composited uncoupler which could more effectively inhibit the growth ofsludge than TCS or TCP, and therefore fundamentally reduce the yield of excesssludge.According to the practical problems and the analysis of previous studies,apply3,3’,4’,5-tetrachlorosalicylanilide (TCS) and2,4,6-trichlorophenol (TCP) tomake up the composited uncoupler. By the analysis of response surfacemethodology to found TCS and TCP had coupling effect to inhibit sludge growth.Model equations were built to obtaion the optimal dosage of the compositeduncoupler which was TCS at0.8mg/L and TCP at2.8mg/L. The observed growthyield (Yobs) was reduced from0.72to0.398by dosing composited unpoupler atoptimal dosage. According to single experiments, found the composited uncouplercould most effectively inhibit the growth of sludge when temperature at25℃andpH at7.0±0.3.Four sequence batch reactors were operated in60-day batch model in parallel.Reactor1conducted as the control reactor. Reactor2and reactor3operated withsingle TCS dosing and TCS dosing. Reactor4performed with the compositeduncoupler addition. The amount of excess sludge was reduced by52%because ofthe effects of composited uncoupler which obviously higher than TCS or TCP. Thesubstrate removal rate was not seriously by the present of composited uncoupler bythe study of COD removal efficiencies, TOC removal efficiencies, N removalefficiencies and P removal efficiencies. The addition of composited uncoupler ledto an increased production of soluble microbial products (SMP) and the mainincreased materials of SMP were proteins. The increased products of SMP wereconsidered the main reason to affect the COD removal efficiencies. According tothe results of Gel Permeation Chromatography and Fourier transform infraredanalysis, the SMP growth might by attributed to the extracellular polymericsubstances (EPS) released from sludge flocs.Single dosing TCS, TCP and composited uncoupler all could stimulate the production of EPS by chemical methods and three-dimensional excitation-emissionmatrix (EEM) fluorescence spectroscopy. The main increased substances wereproteins, fulvic acids and polycarboxylate-type humic acid. Applied sludge volumeindex and zeta potential to study the effects of composited uncoupler on settlingproperties and flocculability of activated sludge. The stability of sewage treatmentsystem was not disrupted, though the composited uncoupler had a slight effect onsludge volume index and zeta potential.By the measurement of contact angle and element analysis found thecomposited uncoupler could not affected sludge dewater and sludge incineration.Utilized polymerase chain reaction and denaturing gradient gel electrophoresis toanalyze the effects of composited uncoupler on microbial community structure ofactivated sludge. The transformation of community structure implied that afterfeeding of the composited uncoupler, some sensitive microbes in the sludge systemwere replaced by some new microbes that might be resistant to compositeduncoupler.