Study Of Biochar Immobilized Bacteria And Its Phenol Removal

Biocar, as precursor of activated carbon, have high surface area, large pore volumeand environmental stability, and had been used as a substitute of activated carbon toremove organic pollutants and heavy metal in water enviroment. Biocar had also beenused as biofilm carriers in sewage treatment. This paper investigate characteristic ofbacteria adsorption onto biochars, which were pyrolysised by different temperatures300℃,500℃,700℃in different pyrolysis stage. Then biochars were modified and usedas bacteria carriers to investigate effect of surface areas, pore volumes and quantity offunctional groups on bacteria adsorption of biochar carriers, the bacteria adsorptioncapacities were characterized though point of zero charge and iodine number ofbiochars.Those conclusions are gained:①Biomass of bacteria adsorbed on biochar carriers depend on surface areas, porevolumes, quantity of functional groups and surface charge of biochar carriers. The porestructure increased dramatically from300℃to500℃. From500℃to700℃, added by204.8and426.2for surface areas;and added by26.69and38.4for pore volumes; Lowquantity of functional groups and high point of zero charge contribute to bacteriaadsorption onto biochar carriers. Bacteria adsorption performance of B500reach92%of B700. Preparation of biochars by pyrolysis should be ended when the raw materialscarbonized completely, because the surface areas, pore volumes, point of zero chargeand quantity of functional groups are more favourable for bacteria to adsorb comparedto biochars carbonized uncompletely.②Modified biochar carriers have a better bacteria adsorption performancecompared to unmodified carriers. HNO3modification increase surface areas, porevolumes, quantity of functional groups of biochars, while bacteria adsorption decrease,which indicated that quantity of functional groups, expspecially carboxyl group, have amore important effect on bacteria adsorption.③Quantity of functional groups，especially carboxyl group affect pHPZCofcarriers,which increase with quantity of functional groups. The higher pHPZCof biocharcarriers have,the better bacteria adsorption performance biochar carriers have. Bacteriaimmobiliztion increase the pHPZCof the carriers, the increasment of it proportionatetobiomass of bacteria adsorbed onto biochar carriers.④Acidic functional groups in aqueous solution incline to be protonated and produce H+, which inhibite bacteria activity. Developed pore structure promote masstrsformation and oxygen adsorption,which make bacteria keep active.Bacteria adsorbedon HNO3modified biochar carriers have the lowerst bacteria activity while NaOH havethe highest.⑤Bacteria immobiliztion enhence phenol removal performance of biochar. In thefirst3h, adsorption and biodegradation of immobilized bacteria carrier resimable thebiochar alone, because phenol was absorbed on cell wall of bacteria, after3h,biodegradation of phenol begain, immobiliztion increase phenol removal efficiency by30%. After the biochar absorption saturated, immobilized bacteria carrier still show abiodegradation of phenol. Biodegradation of phenol by bacteria immobilized on surfaceof biochar carrier was fit well with pseudo-zero-order-model with a low reactionconstant, which indicated that activity of bacteria was inhibited by phenol.Results indicate that factors affectting bacteria immobiliztion of biochars carriers ispore structure and functional groups. Modification can promote the bacteriaimmobiliztion performance of of biochars and NaOH modified carriers is the bestcarriers for bacteria to removel phenol in woter.